Heat Treater's Guide Practices and Procedures for Irons and Steels

Heat

Treating

Processes

and Related

Technology

Introduction Heat treating is defined as heating and cooling a solid metal or alloy in such a way as to obtain desired conditions or properties. Reasons for heat treating include the following:

l

l

l l l

Remove stresses. such as those developed in processing a part Refine the gram structure of the steel used in a part Add wear resistance to the surface of a part by increasing its hardness, and, at the same time. increase its resistance to impacts by mamtaining a soft, ductile core

Iron-carbon equilibrium

diagram

l l l

Beef up the properties of &an economical grade of steel, making it possible to replace a more expensive steel and reduce material costs in a given application Increase toughness by providing a combination of high tensile strength and good ductility to enhance impact strength Improve the cutting properties of tool steels ltpgrade electrical properties Change or modify magnetic properties

The focus in this chapter is on heat treatments associated with getting the desired result.

and the technology

2 / Heat Treater’s Guide Fist, key components abstracts on:

of the heat treating

process are summarized

Second, practical, how-to information

in l

. Normalizing

l

l

hneding

l

l

Stress relieving Surface hardening Quenching/quenchants Tempering Cold/cryogenic treatments Furnace atmospheres

l l l l l

Heat

Treating

l l l l

by overview

atticles on:

Causes of distortion and cracking in quenching Stress relief heat treating Furnace atmospheres Cold and cryogenic treatments of steel Representative applications of heat treating furnaces Statistical process control of heat treating operations Practical applications of the computer in heat treating

Processes tion in resistance to brittle fracture. Lf a steel, such as austenitic stainless steel, is not prone to brittle fracture, residual stresses can cause stress-corrosion cracking (SCC). Warping is the common problem.

Normalizing The term normalize does not characterize the nature of this process. More accurately, it is a homogenizing or grain refining treatment, with the aim being unifotmity in composition throughout a part. In the thermal sense, normalizing is an austenitizing heating cycle followed by cooling in still or slightly agitated air. Typically, work is heated to a temperature of approximately 55 “C (100 “F) above the upper critical line of the iron-iron carbide phase diagram, and the heating portion of the process must produce a homogeneous austenitic phase. The actual temperature used depends upon the composition of the steel; but the usual temperature is around 870 “C (1600 “F). Because of characteristics inherent in cast steel, normalizing is commonly applied to ingots prior to working, and to steel castings and forgings, prior to hardening. Air hardening steels are not classified as normalized steels because they do not have the normal pearlitic microstructure typical of normalized steels.

Surface

A generic term denoting a treatment consisting of heating to and holding at a suitable temperature, followed by cooling at a suitable rate; used primarily to soften metals and to simultaneously produce desired changes in other properties or in microstructures. Reasons for annealing include improvement of machinability, facilitation of cold work, improvement in mechanical or electrical properties, and to increase dimensional stability. In ferrous alloys. annealing usually is done above the upper critical temperature, but time-temperature cycles vary widely in maximum temperature and in cooling rate, depending on composition of the steel, condition of the steel, and results desired. When the term is used without qualiftcation. full annealing is implied. When the only purpose is relief of stresses, the process is called stress relieving or stress relief annealing. In full annealing steel is heated 90 to I80 “C ( I60 to 325 “F”) above the A3 for hypoeutectoid steels and above the At for hypereutectoid steels, and slow cooled, making the material easier to cut and to bend. In full annealing, the rate of cooling must be very slow, to allow the formation of coarse pearlite. ln process annealing, slow cooling is not essential because any cooling rate from temperatures below At results in the same microstructure and hardness.

Hardening

These treatments, numbering more than a dozen, impart a hard, wear resistant surface to parts, while maintaining softer, tough interior which gives resistance to breakage due to impacts. Hardness is obtained through quenching, which provides rapid cooling above a steel’s transformation temperature. Parts in this condition can crack if dropped. Ductility is obtained via tempering. The hardened surface of the part is referred to as the case, and its softer interior is known as the core. Gas carburizing is one of the most widely used surface. hardening processes. Carbon is added to the surface of low-carbon steels at temperatures ranging from 850 to 950 “C ( I560 to 1740 “F). At these temperatures austenite has high solubility for carbon. In quenching, austenite is replaced by martensite. The result is a high-carbon, mattensitic case. Carburizing steels for case hardening usually have carbon contents of approximately 0.2%. Carbon content of a carburized case is usually controlled between 0.8 to I% carbon. Other methods of case hardening low-carbon steels include cyaniding, ferritic nitrocarburizing, and carbonitriding.

Annealing

Stress

is provided

Quenching/Quenchants Steel parts are rapidly cooled from the austenhizing or solution treating temperature, typically from within the range of 815 to 870 “C (1500 to 1600 “F). Stainless and high-alloy steels may be quenched to minimize the presence of gram boundary carbides or to improve the ferrite distribution, but most steels, including carbon. low-alloy, and tool steels, are quenched to produce controlled amounts of martensite in the microstructure. Objectives are to obtain a required microstructure, hardness, strength, or toughness, while minimizing residual stresses, distortion, and the possibility of cracking. The ability of a quenchant to harden steel depends upon the cooling characteristics of the quenching medium. Quenching effectiveness is dependent upon steel composition, type of quenchant, or quenchant use conditions. The design of a quenching system and its maintenance are also keys to success.

Relieving

Residual stresses can be created in a number of ways, ranging from ingot processing in the mill to the manufacture of the finished product. Sources include rolling, casting, forging, bending, quenching, grinding, and welding. In the stress relief process, steel is heated to around 595 “C (I IO5 “F), ensuring that the entire part is heated uniformly, then cooled slowly back to room temperature. Procedure is called stress relief annealing, or simply stress relieving. Care must be taken to ensure uniform cooling, especially when a part has varying section sizes. If the cooling rate is not constant and uniform, new residual stresses, equal to or greater than existing originally, can be the result. Residual stresses in ferritic steel cause significant reduc-

Quenching

Media

Selection here depends on the hardenability of the steel, the section thickness and shape involved, and the cooling rates needed to get the desired microstructure. Typically, quenchants are liquids or gases. Common liquid quenchants are: l l l l

Oil that may contain a variety of additives Water Aqueous polymer solutions Water that may contain salt or caustic additives

Heat Treating Processes and Related Technology / 3 Most common gaseous quenchants are inert gases, including helium, argon, and nitrogen. They are sometimes used after austenitizing in a vacuum. A number of other quenching media and methods are available, including fogs, sprays, quenching in dry dies and fluidized beds. Ln addition, some processes, such as electron-beam hardening and high frequency pulse hardening are self-quenching. Very high temperatures are reached in the fraction of a second, and metal adjoining the small. localized heating area acts as a heat sink, resulting in ultrarapid cooling.

Tempering In this process, a previously hardened or normalized steel is usually heated to a temperature below the lower critical temperature and cooled at a suitable rate, primarily to increase ductility and toughness, but also to increase gram size of the matrix. Steels are tempered by reheating after hardening to obtain specific values of mechanical properties and to relieve quenching stresses and ensure dimensional stability. Tempering usually foUows quenching From above the upper critical temperature. Most steels are heated to a temperature of 205 to 595 “C (-NO to I I OS “F) and held at that temperature for an hour or more. Higher temperatures increase toughness and resistance to shock, but reductions in hardness and strength are tradeoffs. Hardened steels have a fully martensitic structure. which is produced in quenching. A steel containing 100% martensite is in its strongest possible condition, but freshly quenched martensite is brittle. The microstructure of quenched and tempered steel is referred to as tempered martensite. Martempering of Steel. The term describes an interrupted quench from the austenitizing temperature of certain alloy, cast, tool, and stainless steels. The concept is to delay cooling just above martensitic transformation for a period of time to equalize the temperature throughout the piece. Minimizing distortion, cracking, and residual stress is the payoff. The term is not descriptive of the process and is better described as marquenching. The microstructure after martempering is essentially primary martensite that is untempered and brittle. Austempering of Steel. Ferrous alloys are isothermally transformed at a temperature below that for pearlite formation and above that of martensite formation. Steel is heated to a temperature within the austenitiz-

Causes

of Distortion

and Cracking

This problem usually is the result of an imbalance in internal residual stresses that can lead to cracking, ranging from microcracking to bulk failure of a part, Ref I. Factors, singly or in combination, that can influence the nature and extent of shape distortion during quenching include: l l l l l l l

Steel composition and hardenability Geometry of part Mechanical handling Type of quenching fluid Temperature of quenchant Condition of quenchant Circulation (agitation) of quenchant

Composition The quenchant

ing range, usually 790 to 9 I5 “C ( I455 to 1680 “F); then quenched in a bath maintained at a constant temperature, usually in the range of 260 to 400 “C (500 to 750 “F); allowed to transform isothermally to bainite in this bath; then cooled to room temperature. Benefits of the process are increased ductility, toughness, and strength at a given hardness; plus reduced distortion that lessens subsequent machining time, stock removal, sorting, inspection. and scrap. Austempering also provides the shortest possible overall time cycle to through harden within the hardness range of 35 to 55 HRC. Savings in energy and capital investment are realized. Maraging Steels. These highly alloyed, low-carbon, iron-nickel martensites have an excellent combination of strength and toughness that is superior to that of most carbon hardened steels, and are alternatives to hardened carbon steels in critical applications where high strength and good toughness and ductility are required. Hardened carbon steels derive their strength from transformation hardening mechanisms, such as martensite and bainite formation, and the subsequent precipitation of carbides during tempering. Maraging steels, by contrast, get their strength from the formation of a very low-carbon, tough, and ductile iron-nickel martensite, which can be further strengthened by subsequent precipitation of intermetaUic compounds during age hardening. The term marage was suggested by the age hardening of the martensitic structure.

Cold and Cryogenic

Treatment

of Steel

Cold treatment can be used to enhance the transformation of austenite to martensite in case hardening and to improve the stress relief of castings and machined parts. Practice identities -84 “C (-120 “F) as the optimum cold treatment temperature. By comparison, cryogenic treatment at a temperature of around -190 “C (-3 IO “F), improves certain properties beyond the capability of cold treatment. Furnace Atmospheres. Atmospheres serve a variety of functions: acting as carriers for elements used in some heat treating processes, cleaning surfaces of parts being treated in other processes, and providing a protective environment to guard against adverse effects of air when parts are exposed to elevated temperatures. Principal gases and vapors are air. oxygen, nitrogen. carbon dioxide and carbon monoxide, hydrogen, hydrocarbons (i.e., methane, propane, and butane), and inert gases, such as argon and helium.

during

Quenching

Part Geometry Two considerations

here:

I. Quenching at the slowest possible speed as dictated by thickest section of the part 2. Or resorting to hot oil quenching techniques (more later)

Mechanical

Handling

Care is advised because steel in the austenitic condition is only one-tenth as strong as it is at room temperature. Avoid dropping parts into the bottom of a quench tank; and when continuous furnaces are used, quench chute design can cause damage when thin section parts strike pick-up slots in conveyor systems (see Figure).

and Hardenability Type of Quenching

selected should:

I. Just exceed the critical cooling rate of the steel used 2. Provide a low cooling rate in the Ms to Mr transformation Compromises in cooling rate often are necessary range of steels with a range of cooling rate.

range

to accommodate

a

Fluid

The importance of the characteristics of a quenchant during the three stages of cooling (vapor phase, boiling phase, and convection phase) is illustrated by an example involving precision auto transmission gears (see Figure). During oil quenching, vapor retention in tooth roots, combined with the onset of boiling on flanks can cause “‘unwinding” of thin section gears. Use of accelerated oils with special additives that reduce the stability

4 / Heat Treater’s

Guide

Schematic continuous

heat treatment installation.

Ref 1

Example: Because PAG (a polymer quenchant) has higher cooling rates than oils in the convection phase, parts are more susceptible to distortion. Use of PAG requires careful consideration to steel hardenability, part section size(s), and surface finishes. By comparison, other polymer quenchants (ACR. PVP, PEO) have cooling rates similar to those of oils, which means they can be applied in treating critical alloy steel parts outside the scope of PAG quenchants. which are suitable in quenching plain carbon, low-alloy, carburized steels, or higher alloy steel parts with thick section sizes.

Quenchant

Vapor retention in gear tooth roots during oil quenching. Ref 1

Temperature

In conventional quenching, the surface and thinner sections of a part cool to the his temperature and are beginning to transform while center and thicker sections are still in the soft, austenitic condition. This means that when soft sections begin to transform, their changes in volume are restricted by the hard. brittle martensite previously formed on surfaces and thin sections, creating stresses that can lead to distortion or to quench cracking. Hot oil quenching, a two-step process, is one remedy. Parts are Fu-st quenched in specially formulated oils, usually at temperatures within the range of I20 to 300 ‘C (250 to 390 “F). depending on part complexity and tendency to distort. Holding time at the temperature chosen is based on the time required to obtain a uniform temperature throughout a part. In the next step, parts are removed from the oil and cooled slowly in a furnace containing an atmosphere (see Figure).

Hot oil quenching techniques to reduce distortion.

of the vapor phase and promote boiling in cooling is the payoff.

Convection

is one remedy. Greater uniformity An alternative is marquenching in hot oil ( I50 to 200 “C, or 300 to 390 “F’). The hlS temperature of typical engineering steels is in the 250 to 350 “C range (480 to 660 “F).

Phase Characteristics

A temperature of 300 “C (570 “F) generally is accepted as the nom1 for cooling in this phase because it is within the M&t temperature range of a number of different engineering steels, and therefore a critical consideration in controlling distortion. Typical values for several types of quenchants are as follows: Quencbant Normal sped oil Acceleratal oil Polymers PAG (polyalk\ylene glycol) ACR (sodium polyacrylate) PVP(polyvinyl pyrrolidene) PEO(polyethyl oxazolrne)

Ref 1

Cooling rate at 300 ‘C (570 OF) “C/s s-15 IO-15

Condition

Regular monitoring of the quenching fluid is preferred practice. The minimum: testing for acidity and water content of quenching oil and checking the concentration of polymer quenchants. An added control: periodic evaluation of quenching characteristics. Increases in quenching speeds, especially in the convection phase, are a common problem. Possible causes include: l

30-80 I o-25 I o-25 I O-30

of Quenchant

l

Contamination of quenching oils with water. As little as 0.05% water can have a dramatic effect on the maximum cooling rate and on the convection phase cooling rate. Oxidation of mineral oils reduces the stability of the vapor phase and accelerates maximum cooling rates.

Heat Treating Processes and Related Technology / 5

l

Contamination or thermal degradation of polymer quenchants increases the cooling rate in the convection phase. Higher polymer concentrations are a parIial solution.

Circulation of quenchant is important in maintaining a uniform bath temperature and in assisting the breakdown of the vapor phase. The degree of agitation has a significant influence on the cooling rates of both quenching oils and polymer quenchants. With increases in the agitation of oil, three things happen: l l l

Duration of the vapor phase is shortened Maximum cooling rate rises Cooling rate in the convection phase also goes up

The last named effect adds to the risk of cracking, meaning that excessive agitation of oils should be avoided. Agitation of polymer quenchants has a pronounced effect on the vapor phase and maximum cooling rate, but little effect on the cooling rate in the convection phase. Vigorous agitation of polymer quenchants normally is recommended to ensure uniform quenching characteristics, a practice that does not enhance the risk of cracking.

Stress

Relief

Heat

Treating

Finally, the direction influence on distortion. provide relief.

of quenchant flow over the workpiece can have an Reversing the direction of flow, for example, can

Reference I. R.T. van Bergen, conference paper, ‘The Effects of Quenchant Media Selection and Control of Distortion of Engineered Steel Parts.” Houghton Vaughan plc. Birmingham. England, ASM Conference Proceedings, “Quenching and Distortion Control,” 1992

Other References Quenching Principles and Practice, Houghton Vaughan plc, UK G.E. Hollox and R.T. von Bergen, Heat Treatment of Metals, 1978.2 hlEl Course 6. Heat Processing Technology, ASM International, 1977 R.T. von Bergen, Heat Treatment of Metals, 1991.2

of Steel

Residual stresses are built up in a part during the course of a manufacturing sequence. Technically, a part is stressed beyond its elastic limit and plastic flow occurs.

long distance or highly localized. Postweld heat treating has two objectives: relief of residual stresses and the development of a specilic metallurgical structure of properties (Ref 4.5).

Causes

Relieving

Bending, quenching, grinding, and welding are among the major causes of the problem (see adjoining Figure). Bending a bar during fabrication at a temperature where recovery cannot occur (as in cold forming) can cause a buildup on residual tensile stresses in one location, and a second location, 180” from the Fust location, will contain residual compressive stresses (Ref I). Quenching of thick sections results in high residual compressive stresses on the surface of a part. They are balanced by residual tensile stresses in the interior of the part (Ref 2). Residurtl stresses caused by grinding can be compressive or tensile in nature. depending on the grinding operation. Such stresses tend to be shallow in depth, but they can cause warping of thin parts (Ref 3). In welding, residual stresses are associated with steep thermal gradients inherent in the process. Stresses may be on a macro-scale over a relatively

Relief is a time-temperature related phenomenon rically correlated by the Larson-hliller equation:

Examples of the causes of residual stresses: (a) Thermal due to welding.

(c) Residual

stresses

due to grinding

distortion

Residual

Stresses (see Figure), paramet-

where T is the temperature (Rankin) and I is time in hours. Example: holding a part at 595 “C (I I05 “F) for 6 h provides the same result as heating at 650 “C ( 1200 “F) for I h. Other Factors. Creep resistant materials such as chromium bearing, low-alloy steel and chromium rich, high-alloy steel normally require higher stress relief temperatures than con\ entional low-alloy steels. Typical treatment temperatures for low-alloys are between 595 and 675 “C (I I05 and 1245 “Fj. Temperatures required for the treatment of high alloys, by comparison. range from 900 to 1065 “C ( 1650 to 1950 “F).

in a structure

due to heating

by solar radiation.

(b) Residual

stresses

6 / Heat Treater’s Guide

Relationship between time and temperature in the relief of residual stresses in steel

925 “C (895 to 1695 “F). However,

at the higher end of this range stress-corrosion cracking can occur (Ref 6). Solution annealing temperatures of approximately 1065 “C (1950 “F) are frequently used to reduce residual stresses in these aBoys to acceptably low levels.

References I. GE. Dieter, Mechanical Merallurgy, 2nd ed, McGraw-Hill, 1976 2. J.O. Almen and RH. Black, Residual Stresses and Fatigue in Merals, McGraw-Hill, 1963 3. Machining, Vol 3, 8th ed, Merals Handbook, American Society for Metals, 1967, p 260 4. N. Bailey, The Metallurgical Effects of Residual Stresses, in Residual Stresses, The Welding Institute, I98 I, p 28-33 5. C.E. Jackson et al., Metallurgy and Weldabili& of Sleek, Welding Research Council, 1978 High alloys such as austenitic stainless steels are sometimes treated at temperatures as low as 400 “C (750 “F). But in this instance stress reduction is modest. Better results are obtained at temperatures ranging from 480 to

Furnace

6. Properties and Selecrion: Stainless Sleels, Tool Materials and Special Putpose Metals, Vol 3.9th ed, Metals Handbook, American Society for Metals,

1980, p 4738

Atmospheres

Properties of common gases and vapors are listed in Table I. They include air, oxygen, nitrogen, carbon dioxide, carbon monoxide, hydrogen, water vapor, hydrocarbons, and inert gases. Ref I. Air provides atmospheres in furnaces in which protective atmospheres are not used. Air is also the major constituent in many prepared amiospheres. The composition of air is approximately 79% nitrogen and 2 I % oxygen, with trace elements of carbon dioxide. As an atmosphere, air behaves like oxygen, the most reactive constituent in air. Oxygen reacts with most metals to form oxides. It also reacts with carbon dissolved in steel, lowering surface carbon content. Nitrogen in its molecular state is passive to ferrite and can be used as an atmosphere in annealing low-carbon steels; as a protective atmosphere in heat treating high-carbon steels, nitrogen must be completely drysmall amounts of water vapor in nitrogen cause decarburization. Molecular nitrogen is reactive with many stainless steels and can’t be used to heat treat them. Atomic nitrogen, which is created at normal heat treating temperatures, is not a protective gas-it combines with iron, forming finely divided nitrides that reduce surface hardness.

Carbon dioxide and carbon monoxide are used in steel processing atmospheres. At austenitizing temperatures, carbon dioxide reacts with surface carbon to produce carbon monoxide, a reaction that continues until the supply of carbon dioxide is exhausted and the steel surface is free of carbon. Hydrogen reduces iron oxide to iron. Under certain conditions, hydrogen can decarburize steel, an effect that depends on furnace temperature, moisture content (of gas and furnace), time at temperature, and carbon content of the steel. Water vapor is oxidizing to iron and combines with carbon in steel to form carbon monoxide and hydrogen. It is reactive with steel surfaces at very low temperatures and partial pressures. It is also the principal cause of bluing during cooling cycles. Carbon hydrocarbons are methane (Cb). ethane (C2H6). propane (C$-Js), and butane (CtHtu). They impart a carburizing tendency to furnace atmospheres. Inert gases are especially useful as protective atmospheres in the thermal processing of metals and alloys that can’t tolerate the usual constitu-

Table 1 Properties of Common Gases and Vapors

Gas

Chemical symbol

Air

Approximate molecular weight

k&m3

lb/d’

I.293 0.760 0.178 I.965

0.0807 0.047-l 0.0111 0.1228 0.0780 0.0112 0.0056 0.0447 0.0780 0.0892 0.1229 0. I785

Density(a)

AINllOllitl

NH3

Argon Carbon dioxide Carbon monoxide Helium Hydrogen Methane Nitrogen Oxygen Pv= SulFurdioxide

Ar CO?

28.97(c) 17.03 39.95 44.02

CO

28.01

I.250

He H? CH-I N? 02

4.00 2.02 16.04 28.01 32.00

0.179 0.090 0.716 I.250 I.429 I.968 2.860

C3Hx

SO?

44.09

64.06

(a) Standard temperature and pressure: 0 “C (32 “F) and 760 mm Hg. (b) Relative is the average molecular weight of its constituents.

density compared

SpCifiC

to air. (c) Because air IS a mixture,

gravity(b) l.ooo 0.588 I.380 1.520 0.967 0.138 0.070 0.552 0.968 I.105 I.522 2.212

it does not have a true molecular

weight. This

Heat Treating Processes and Related Technology / 7 Table 2 Classification Dfscription

Cla5.S

101 102 201 202 301 302 402 501 so2 601 621 622

and Application

Lean exothemic Rich exothermic Lean prepared nitrogen Rich prepared nitrogen L.eaoendothemic Rich endothermic Charcd Leanexothemric-endothermic Rich enothennic-endothermic Dissociated ammonia Lean cornbusted ammonia Rich cornbusted ammonia

of Principal Furnace Atmospheres

Common application

NZ

Oxide coating of steel Bright annealing; copper brazing; sintering Neutral heating Annealing, brazing stainless steel Clean hardening Gas carburizing Carburizing Clean hardening Gas carburizing Brazing. sintering Neutral heating Sintering stainless powders

86.8 71.5 97. I 75.3 45.1 39.8 64. I 63.0 60.0 25.0 99.0 80.0

reactive metals and their alloys. Argon costs about half as much as helium, and is frequently favored; air contains approximately 0.93% argon by volume, and is recovered by liquefying air, followed by the fractionation of liquid air: helium is recovered from natural g,as deposits by cryogenic methods.

ents in protective

Classifications The American tions:

of Prepared Gas Association

Atmospheres

is the source of the following

classitica-

Class 100, exothermic base: formed by the combustion of a gas/air mixture; water vapor in the gas can be removed to get the required dew point Class 200, prepared nitrogen base: carbon dioxide and water vapor have been removed Class 300. endothermic base: formed by the reaction of a fuel gas/air mixture in a heated, catalyst tiller chamber Class 400, charcoal base: air is passed through a bed of incandescent charcoal Class 500, exothermic-endothermic base: formed by the combustion of a mixture of fuel gas and air; water vapor is removed and carbon dioxide is reformed to carbon monoxide by reaction with fuel gas in a heated, catalyst tilled chamber Class 600. ammonia base: can consist of raw ammonia. dissociated ammonia, or combusted dissociated ammonia with a regulated dew point Subclassifications supplement the six basic classitications for prepared atmospheres-the two zeros in the latter are replaced by the two-digit numbers that follow. These atmospheres are prepared by special techniques. l l l

l

l

l

l

l

l

l

01: prepared from a lean air and gas mixture 02: prepared 6om a rich air and gas mixture 03 and 04: preparation is completed within the furnace itself without the use of a special machine or generator 05 and 06: original base gas is subsequently passed through incandescent charcoal before admission to work chamber 07 and 08: raw hydrocarbon fuel gas is added to base gas before admission to work chamber 09 and IO: raw hydrocarbon fuel gas and rah dry anhydrous ammonia are added to base gas before admission to work chamber I I and 12: combustible mixture of chlorine, hydrocarbon fuel gas and air is added to base gas before admission to work chamber I3 and 14: all sulfur or all sulfur and odors are removed from gas before admission to work chamber IS, 16, I7 and 18: lithium vapor is added to base gas before admission to work chamber I9 and 20: gas preparation is completed inside the furnace chamber bith the addition of lithium vapor

co

Nominal composition, ~01% co2

I.5 IO.5 1.7 II.0 19.6 20.7 31.7 17.0 19.0

IO.5 5.0

82

CB,

1.2 12.5 I.2 13.2 34.6 38.7 I.2 20.0 2 I .o 75.0 I.0 20.0

0.4

OS 0.5 0.3 0.8 ... .

Table 3 Potential Hazards and Functions of Heat Treating Atmosphere-Constituent Gases Potential hazard Stole Gas

Flammable

Nitrogen Hydrogen Carbon monoxide

Toxic

Yes Yes

Yes Yes

Yes

Carbon dioxide

Yes

Natural gas

Yes

Ammonia Methanol

Yes Yes

Yes Yes

Yes Yes

Table 4 Physiological

Atmosohere

a5phyknt

..

fUll&Oll

tnell Strongly reducing Carburizing and mildly reducing Oxidizing and decarburizing Strongly carburizing and deoxidizing Strongly niniding Carbon monoxide and hydrogen generating

Effects of Ammonia

Conceotrstion, Physiological

mm

30

First perceptible odor Slight eye irritation in a few individuals Noticeable irritation of eyes and nasal passages after a few minutesofexposure Were irritation of the duoat, nasal passages. and upper respiratory tract Severe e)e irritation; no permanent effect if the exposure is limited to less than r/z h Serious coughing, bronchial spasms; less than ‘/z h of exposure may be fatal Serious edema strangulation, asphyxia; almosl immediately fatal

-lo I00 m 700 1700 moo

l

l

l

effects

21 and 22: base gas is given an additional special treatment before admission to work chamber 23 and 24: steam and air ‘are added and in conjunction with a catalyst in a generator convert carbon monoxide to carbon dioxide, which is then removed 25 and 26: steam is added to a generator containing a catalyst, converting CHJ to Hz and CO?, which is then removed Few

cially

of the atmospheres important.

Principal

in the subclassification furnace

atmospheres

category and their

are commer-

common

appli-

cations are listed in Table 2. Potential hazards in the use of constituents in heat treating atmospheres and their functions are listed in Table 3. Physiological effects of ammonia are listed in Table 4, and physiological effects of carbon monoxide are given in Table 5.

8 / Heat Treater’s Guide Exploswe

ranges of typical

atmosphere

constituents

are:

their use as intentional ture operations.

Concentration

Constituent

in Air Q

Hbdrogcn

-I o-74

Carbon mono\idc hlrtic Ammonia hkthm0l

12.5-71 5.3-13 15.0-28

Endothermic-Based

agents or in special, low tempera-

Atmospheres

These atmospheres are suitable for practically all furnace processes requiring strong reducing conditions. Their most common applications are as carrier gases in gas carburizing and carbonitriding operations. Other applications include bright hardening of steel. carbon restoration in forg-

6 7-36

Exothermic-Based

surface oxidizing

Atmospheres

Class 100 atmospheres of this type are \\idelj used as lo\rer cost alternatives to other atmospheres. The) are available in two classes: rich (class 102) and lean (class 101). The rich types have moderate reducing capabilities of IO to 2 I% combined carbon monoxide and hydrogen. The lean types. usually with I to 1 Q combined carbon monoxide and hydrogen. have minimal reducing qualities. Rich exothermic atmospheres are used mainlj in the tempering of steel and sintering of powder meval compacts. Heat treating applications of lean exothermic atmospheres are generally limited, particularI) in the treatment of ferrous metals. Exceptions include

Table 5 Physiological

Effects of Carbon Monoxide

Concentralion, PPm

Physiological effects Allo\\sble for an exposure of several hours Can be inhaled for I h without appreciable effect Causes a barely appreciable effect tier I h of exposure Causes unpleasant symptoms. hut not dangerous aher I h

100

400 6ofl IO00 I ml

Dangerous for exposure of I h Fall for exposure of less than I h

4000

Table 8 Comparison of Generated Atmosphere Systems Versus Commercial Nitrogen-Based Generated ppe of atmosphere

Designation

Application

Protacti\e

Annealing

Reacti\c

Brazing Siniering

Carbon controlled

Hardening Carburizing Decarburizing

Table 7 Compositions

Exolhermi~ Dissociated ammonia Exothermic Dissociated arnmon~a Endothemlic Dissociated ;unmonia Endothemlic Endothemlic Erolhermic

atmosphere Nominal composition, N2 HZ

70-100

O-16

25 70-80 75 40 2s 10 10 85

7s IO- I6 75 -IO 75 40 10 5

% CO O-II

8-11 70 20 20 3

Designation

Systems

Nitrogen-based atmosphere Nominal composition, N? co 82

Niuwgen-hydrogen Nitrogen-methanol Nitrogen-hydrogen Niaogen-hydrogen

9% IO0 91-100 60-90 95

O-IO O-h IO-40 5

o-3 ,..

Nitrogen-hbdrogcn Nitrogen-merhanol Nitrogen-mehane Nitrogen-tnclhanol Nitrogen-hydrogen

95 85 97 40 90

5 IO I JO IO

5 I 30

of Protective Generated Atmosphere and Commercial Nitrogen-Based Furnace

atmosphere

analysis,

Carbon steel sheet. rube. wrc Carbon steel rod

Copper n ire. rod .Alunlinurn Skinless

sheet steel sheet. wire

Srainless sleel tube

hlalleahle Nick-uon

iron anneal laminaoons

atmosphere

Exolhermic-purified N:-S5 Hz E\othetis-puritird Exothermic-cndolhemtiii N,- I!“1 C,H, N,-55, H>-3=c CH, N;-3% Ct? 0.4QC)

Brass. bronze simering

Stainless steel sintering Tungsten carhide Sintering and brazing Sintering Presinrering Nickel sintering

ings and bar stock, and the sintering requiring a reducing atmosphere.

Prepared

Nitrogen-Based

NZ

82

Exothetic-rich Endothermic N,-55% H, N;-3% CH,OH Dissociated ammonia N2-25’% H, Dissociatei ammonia t Hz0 N,-10% H--?-B H,O E~othermi~ N,- 10%.H,-L?q, H,O Endother&

70 40 95 91 1s 75 2s 90 75 88 40

I-l 39 5 6 7s 25 75 IO 9 I0 39

N2-S% H, Endothermic N2-endothermic

9.5 -lo 87

5 39 8

N+? CH,OH N,-8% H1-2Q CH Dissociated ammoha Endothermic NvIO% H, Dissociates ammonia HZ

76 90 2s -lo 90 25

I6 8 75 39 10 75 100

Dissociated ammonia H, N;-20Q H, Dissociated ammonia N,-IO% H,

2s

7s 100 20 75 IO

of powder

metallurgy

80 25 90

compacts

Atmospheres

Applications in this instance extend to almost all heat treatments that do not require highly reducing atmospheres. They are not decarburizing and can be used in annealing. normalizing, and hardening of medium- and high-carbon steels: the low carbon monoxide content of lean gases makes them suitable for heat treating lou-carbon steels. Because of their low dew point and virtual absence of carbon dioxide, these atmospheres (in the absence of oxygen-bearing contaminants introduced in furnace operations) are neither oxidizing or decarburizing, in contrast with exothermic-based atmospheres. In addition, they are lower in cost than all but one type of protective atmosphere: the exothermics. Nitrogen-based atmospheres enriched with methane or other hydrocarbons are used occasionally as carrier gases in annealing. gas carburizing. and carbon restoration; but endothermic and other protective atmospheres are generally preferred for their high carbon potentials and greater ease of control. Lean. nitrogen-based atmospheres are also used in large. seni-continuous and continuous annealing furnaces. Their rich counterparts can be used in the sintering of iron powder compacts. Generated atmosphere systems and commercial. nitrogen-based systems are compared in Table 6.

Commercial

Nitrogen-Based

Atmospheres

These products fall into three major categories. based on function: protective atmospheres, reactive atmospheres, and carbon-controlled atmospheres.

co

CE4

II I9

I 2

3

7 I9

2

I9 -I

7 ;

7 I

I I

I9

2

‘Itace impurities 820 Co2 0.0s 0.05 0.001 0.001 0.001 0.001 3 2 3 2 0.05 0.001 0.0s 0.01 0.005 0.005 0.00 I 0.05 0.00 I 0.001 0.001

4 0.1 0.01

6 0. I 0.2 0.05 0.05

0.01 0.3

0.001 0.001 0.001 0.001 0.001

Protective atmospheres prevent oxidation or decarburization during heat treatment. Typical applications include batch and continuous annealing of most ferrous metals. Reactive atmospheres have concentrations of reactive gases greater than S%--to reduce metal oxides or to transfer small amounts of carbon to ferrous surfaces. Hydrogen and carbon monoxide are usual reactive components. Typical applications: brazing. sintering powder metal compacts, and powder metal reduction. Carbon-Controlled Atmospheres. Their main function is to react I{ ith steel in a controlled manner so that significant amounts of carbon can be added to or removed from the surface of a steel. Typical atmosphere components can include up to SO8 hydrogen, 5 to 20% carbon monoxide, and traces (up to 3%) of carbon dioxide and water vapor. Most common apptications are carburizing and carbonitriding machined parts. neutral hardening. decarburization of electrical laminations, sintering of powder metals, and carbon restoration of hot worked or forged materials. Advantages of commercial. nitrogen-based atmospheres include the technical viability of substituting them for generated ahnospheres in most heat treating operations. Compositions of protecti\ e generated atmospheres and commercial, nitrogen-based systems are listed in Table 7. Compositions of reactive atmospheres for brazing and sintering are given in Table 8. Compositions of carbon-controlled atmospheres for selected applications are summarized in Table 9.

Dissociated,

Ammonia-Based

Atmospheres

Applications include: bright heat treating of some nickel alloys and carbon steels; bright annealing of electrical components. and use as a carrier mixed gas for certain nitriding processes, including the Floe nitriding system. a method of controlling the formation of white layer.

10 / Heat Treater’s Guide Table g Compositions

of Carbon-Controlled

Atmospheres for Selected Applications Furnace

Input Neutral harden

Carburize

Carbonitride

Lamination decarburize

atmosphere

NZ

82

Endothermic + CH, N,-2% CH,. or 1% C,H,

39 97 8-l 37 37 70 55 36 36 68 53 75 83 79

40 I IO Xl 40 I6 28 xl 40 I8 30 9 IO IO

N,-5% CH,OH-I% CH, Endothetic + CH, N?-20% CH,OH + CH, N--17% CH,-4% CO, N;-20%. CH,-5% Hz6 Endothermic + CH, + NH, N,-20% CH,OH + CH, + NH, NJ- 17% CH,-4% CO, + NH, N,-20% CH,-5% H,O t NH, Exothermic + H,O N?- 10% H,-4% H,O Nz-5%. CH,OH-4C Hz0

Table 10 Physiological Effects of Contamination by Ammonia in Various Concentrations Ammonia concentration in air, ppm 53

100 30@5cKl 408 698

17’0 2s00-4500 5ooo- lO.ooo

Physiological

of Air

effect

Smallest concentration at which odor can he detected Maximum concenaation allowable for prolonged exposure Maximum concenuation allowable for short exposure (‘/?-I h) Least amount causing immediare irritation to the throat Least amount causing immediate irritation to the eye Least amount causing coughing Dangerous for short exposure (‘12 h) Rapidly fatal for short expsure

atmosphere

analysis,

co

Hydrogen

Atmospheres

T’he commercially available product is 98 to 99.98 pure. All cylinder hydrogen contains traces of water vapor and oxygen. Methane. nitrogen, carbon monoxide, and carbon dioxide may be present in very small amounts as impurities. Hydrogen is a powerful deoxidizer, and its deoxidizing potential is limited by moisture content only. Its thermal conductivity is about seken times that of air. Its main disadvantage is that it is readily absorbed by most common metals, either by occlusion or by chemical composition at elevated temperature. Absorption can result in serious embrittlement. especially in high-carbon steels. It may also reduce oxide inclusions in steel to form water, which builds sufftcient pressure at elevated temperatures to cause intergranular fracture of steel. Dry hydrogen will decarburize highcarbon steels at elevated temperature by reacting with carbon to form methane.

lhwe HZ0

C&

I9 I 5 I8 I8 7 IO I8 I8 7 IO 7 I 2

0.05

2 I I 5 5 7 7 5 5 7 7

0.001 O.OOS 0.0s 0.05 O.OOS 0.0 I 0.05 0.05 0.005 0.01 3 3 3

impurities CO2

0.1 0.01 0.01 0.1 0.1 0.05 0.05 0. I 0.1 0.05 0.05 6 3 6

Table 11 Equipment Requirements for Sintering Stainless Steel Powder Metallurgy Parts in Hydrogen Production

requirements

Load weight. kg (lb) Heating cycle, min Output per hour, kg (Ih) Equipment

9(30) 40 l4(3OJ

requirements

Bumoff furnace Size ofhearth. mm (in.) Length of cooling chamber. m (ft) Power, hp (kW) *rating temperature, “C (“F) Atmosphere. m’/h tft3/h) High-heat furnace Size ofhearth, mm (in.)

This atmosphere (class 601) is a medium cost product which provides a dry, carbon-free source of reducing gas. Typical composition: 75% hydrogen, 2YZ nitrogen, less than 300 ppm residual ammonia. Dew point is less than -SO “C (- 60 “F). High hydrogen content provides a strong deoxidizing potential, an advantage in removing surface oxides or preventing oxide formation during high temperature heat treatment. Care is advised in selecting heat processing applications that might result in unwanted hydrogen embrittlement or surface nitriding reactions. Physiological effects of the contamination of air with ammonia in different concentrations are set forth in Table IO.

5%

Lengthofcoolingchamber.mm(li~ Power. hp (kW) Operating temperature. “C (“F)

Pusher. electrically heated; forced circulation 25Sby lSOby915(lOby6by36) I .8 (6) 17 (‘0) 43 (800)

Dissociated ammonia, 4.2 ( 150) OPen chamber, electrically heated; front push rear pull 255by610(10by24)(preheating) 255 by 9lS(lOby 36)(high heating) U(8) 17(35) I275 (2325)

Hydrogen best suited for metallurgical purposes is made by the electrolysis of distilled water. In most heat treating procedures requiring hydrogen, hater vapor and oxygen are objectionable, and hydrogen must be puritied before it can be used. Applications for dry hydrogen include the annealing of stainless steels, low-carbon steels, electrical steels, some tool steels. nickel brazing of stainless steel and heat resisting alloys, the annealing of metal powders, and the sintering of powder metal compacts. Equipment requirements for sintering stainless steel powder metallurgy parts in hydrogen are found in Table I I.

Steam Atmospheres Scale-free tempering and stress relieving of ferrous metals in the temperature range of 3-U to 650 “C (655 to I200 “F) are among the applications here. Steam causes a thin, hard, and tenacious blue-black oxide to form on a metal surface. The film, approximately 0.00127 to 0.008 mm (0.00005 to 0.0003 in.) thick, improves properties of various metal parts. Steam treating decreases the porosity of sintered iron compacts and provides increased compressive strength and resistance to wear and corrosion. Steam penetrates the pores of compacts and forms the oxide internally as well as on the surface. The oxide seals pores and partially fills voids.

Heat Treating Processes and Related Technology / 11

Exothermic and Endothermic Furnace Atmospheres.

Source:

Cast iron and steel parts, treated at 345 “C (655 “F) or higher, have increased resistance to wear and corrosion. Before parts are processed their surfaces must be clean and oxide-free, to permit the formation of a unique coating. To prevent condensation and rusting, steam should not be admitted until workpiece surfaces are above 100 “C (210 “F). Air must be purged from the furnace before the temperature exceeds 425 “C (795 “F), to prevent the formation of a brown coating instead of the desired blue-black coating

Charcoal-Based

Atmospheres

These atmospheres (AGA classes 402 and 42 I ) are on the day to becoming obsolete. Their main use currently is by small manufacturing

Electric

Furnace

Co.

plants wanting a generator low in initial cost and for intermittent use. Principal uses today are in the manufacture of malleable iron castings and as atmospheres in small toolroom, heat treating furnaces.

Exothermic-Endothermic-Based

Atmospheres

These atmospheres (classes 501 and 502) are m-formed exothermicbased types and are less reducing than conventional endothermic-based atmospheres. Potentially. they can be substituted for exothermic, endothermic, and nitrogen-based atmospheres in virtually all applications for which any one of the three amlospheres is recommended. Also, they are used as carrier gas in carburizing and carbonitriding.

12 / Heat Treater’s Guide Equipment requirements for hardening small parts made of 1070 steel in cxothermic-endothermic atmospheres are provided in Table I?.

Atmospheres for Backfilling Quenching in Vacuum

and

Production

Backfilling with a cooling gas in a vacuum furnace speeds up the cooling rate. Other uses of backfilling include: suppressing the vaporization of oil in integral quench vacuum furnaces and providing an atmosphere for carburizing and nitriding. Inert gases, nitrogen, and hydrogen (rarely) are used for cooling; contaminants in cooling gases must be held to a minimum to maintain the surface intefity of workpieces and to avoid damage to furnace parts. Backfilling and forced circulation increase cooling rates. aid in hardening, and in some instances are used to anneal metal alloys. Cooling gas is usually introduced into a vacuum chamber at the end of the high temperature soaking period. Vacuum furnaces can be used for carburizing by the injection of any one of several atmospheres that induce carburizing at appropriate temperatures. Nitrogen enriched with a hydrocarbon gas is most frequently used. Carburizing is normally carried out in the range of 870 to 980 YI t 1600 to 1795 “F). ln the carburizing and diffusion process, surface carbon content of 1% or more is formed initially. The high-carbon case is then diffused in vacuum to the desired surface content and case depth.

Ion Carburizing

Atmospheres

A hydrocarbon gas that is ionized by a high voltage system in a vacuum is a suitable atmosphere for this process. Methane is frequently used. The process is faster than conventional atmosphere carburizing. and surface carbon content approaches saturation. For carbon control, other diluting gases are added. An AISI 1018 steel can be ion carburized to a depth of I .O mm (0.040 in.) with a IO min cycle in an atmosphere of methane at I .3 to 2.7 kPa ( IO to 30 torr) and a temperature of 1050 “C (1920 “F). Carburizing is followed by a 30 min diffusion cycle in vacuum at the same temperature. About 100 V is needed to produce the plasma.

Cold and Cryogenic

Table 12 Equipment Requirements for Hardening Small Parts Made of 1070 Steel in an ExothermicEndothermic Atmosphere

Treatment

Common practice for cold treatment is regarded to be -84 “C (-120 “F). In cryogenic treating. parts are chilled to approximately - 190 “C (-3 IO “F). Ref I. Benefits from cold treatment range from enhancing transfomiation from austenite to martensite to improving the stress relief of castings and machined parts. In each case, even greater gains are realized \ ia cryogenic treatment.

Cold Treating As a rule. I h for each inch of cross section is adequate. All hardened steels treated in this manner have less tendency to develop grinding cracks and grind easier after retained austenite and untempered martensite are eliminated-100% transformation to martensite in hardening is rare. Cold Treating vs. Tempering. The best opportunity for maximum transformation to martensite is to cold treat parts immediately after hardening (and before tempering) when parts cool down to room temperature, or at a temperature within the range for quenching. A caveat is attached to this procedure: cracking could result. For this reason, it is important to ensure that the grade of steel and product design will tolerate immediate cold treating. rather than immediate tempering. Some steels must be trans-

requirements

Number of parts per load Weigh1 of each part. kg I lb) AIa.\imum nel wright of load. kg(lh) Production rale. kg I lb) Equipment

2625 00069~0.015) 18(-K)) 7.5 loads ( 135. or 300) per h

requirements

Hardening furnace Size of hearth, m (ti) Heat input. H’/h I Btu/h) Operating Iempzrature. “C c”F) Capacir) of generator. nil/h (ft-l/hJ T> pe of atmosphere Capacih’ofoil-quench tank. Ltgal) lJprofoil,“C(“F) Tmmperarure ofoil. “C IOF) Oil agilation

Ion Nitriding

Gas-tired radiant-tube single-row pushertype \virh automatic quench 0.9 (3) wide by 2.9 (9%) long 2.2 x I oi HhKs (7.5 x 105) 900 i 1650) 68 (1400) Class so1 1250(330, Fas& I80 (360) flash point

70 ( 160) (controlled) ~ldhll

Atmospheres

The process is similar to that of ion carburizing. except that the atmosphere gas generates nitrogen ions. and the process is carried out at lower temperatures. Suitable sources for nitrogen ions are ammonia or mixtures of hydrogen and nitrogen. A typical cycle of 8 h at 5 IO “C (950 “F) with a mixture of 75% hydrogen and 2% njtrogen at a pressure of0.9 kPa (7 torr) and a current density of 0.8 mA/cm- will produce a nitrided case of 0.30 mm (0.012 in.) in AISI 4140 steel. About 400 V is needed to generate the plasma.

Reference I. XX

hler~~ls Hmdbook. Vol4.

10th ed. ASM International

of Steel ferred to a tempering furnace when they are still warm to the touch to minimize chances of cracking. Design features such as sharp comers and abrupt changes in section create stress concentrations and promote cracking. In most instances, cold treating does not precede tempering. Ln several applications, tempering is followed by deep freezing and retempering uithout delay. Such parts as gages and pistons are treated in this manner for dimensional stability. In critical applications, multiple freeze-temper cycles are used. In addition, in cases where retained austenite could result in excessive wear. the wear resistance for several different materials is improved, ie., tool steels; high-carbon. martensitic stainless steels, and carburized alloy steels (see adjoining table).

Process

Limitations

In some applications, explicit amounts of retained austenite are considered beneficial, and treatment could be detrimental. Also, multiple tempering, rather than alternate freeze-temper cycles, is generally more practical in transforming retained austenitc in high speed and high-carbon/highchromium steels.

Heat Treating Processes and Related Technology Hardness Testing. Lower than expected HRC values may indicate excessive following

retained austenite. Significant increases in hardness readings cold treatment indicate conversions from austenite to martensite. Precipitation-Hardening Steels. Specifications for these steels may include a mandatory deep freeze after solution treatment and prior to aging. Shrink Fits. This result can be obtained by cooling the inner member of a complex part. Care is advised to avoid brittle cracking when the inner member is made of heat treated steel containing large amounts of retained austenite, which converts to martensite in subzero cooling. Stress Relief. Cold treating is beneficial in stress relieving castings and machined parts of even or nonuniform cross section. Features of the treatment include: l

l

l

l

l l l

Transformation of all layers is accomplished when the material reaches -84 “C (-I 20 “F) The increase in volume of the outer martensite is somewhat counteracted by the initial contraction due to chilling Rewarm time is more easily controlled than cooling time, allowing equipment flexibility The expansion of the inner core due to transformation is somewhat balanced by the expansion of the outer shell The chilled parts are more easily handled The surface is unaffected by low temperature Parts that contain various alloying elements and that are of different sizes and weights can be chilled simultaneousI)

Advantages

/ 13

Wear Resistance as a Function of Cryogenic Soak Temperature for Five High-Carbon Steels Wear

reistance,

&(a) SOaked

Alloy

Untreated

52100

25.2

D2

22-l

A2 hl2 01

85.6 1961 237

-tLaT(-12oT) 19.3 308 174.9 2308 382

-l!mT(-31oT) 135 878 565 3993 996

(a) R, = R’AVH,. where Fis the normal force in newtons. N. pressing the surfaces together; \‘isthesliding velocib inmm/s; \\‘is theaearrate in mm’/s;and Hv is the Vickers hardness in MPa. R, is dimensionless. Source: Ref 3

Plot of temperature vs. time for the cryogenic treatment proc_ ess. Sour&

Ref 2

of Cold Treating

Success depends only on reaching the minimum low temperature, and there is no penalty for a lower temperature. As long as -80 “C t,- I IS “F) is reached transformation takes place. Reversal is not caused by additional chilling. Also. materials with different compositions and different configurations can be chilled at the same time. even though each may have a different high temperature transformation point.

Cryogenic

Treatment

A typical treatment consists of a slow cool-down rate (25 “C/min equivalent to 3.5 “F/min) from ambient temperature to the temperature of liquid nitrogen. When the material reaches approximately 80 K (-3 IS “F). it is soaked for an appropriate time (generally 24 h). Then the part is removed from the liquid nitrogen and allowed to warm to room temperature in ambient air. The temperature-time plot for this treatment is shown in the adjoining Figure. By using gaseous nitrogen in the cool-down cycle. temperatures can be controlled accurately. to avoid thermal shock. Single cycle tempering usually is the next step-to improve impact resistance, although double or triple tempering cycles are sometimes used for the same reason.

Kinetics

of Cryogenic

Treatment

According to one theory with this treatment, transformation of retained austenite is nearly complete-a conclusion that has been verilied by x-m> diffraction measurements. Another theorq is based on strengthening a

Representative

Applications

Pit Furnaces

Normalizing Stress relieving

References I. ,&SM &m/s Hmdhook. Heat Treating, Vol 3. 10th ed., ASM Lntemational 2. R.F. Barron and R.H. Thompson, Effect of Cryogenic Treatment on Corrosion Resistance, in Adwnces in C~ogenic Engineering, Vol 36, Plenum Press. 1990. p I375 I379 3. R.F. Barron, “How Cryogenic Treatment Controls Wear,” 2lst InterPlant Tool and Gage Conference. Western Electric Company, Shreveport, LA, 1982

of Heat

Representative applications of 36 different types of heat treating furnaces, reported by suppliers of equipment. are listed in this section. Ref I

Soaking

material via the precipitation of submicroscopic carbides. An added benefit is said to be a reduction in internal stresses in the martensite developed during carbide precipitation. Lo\\er interior stresses may also reduce tendencies to microcrack.

Treating

Furnaces

Reheating

Batch or In-and-Out Normalizing Annealing Aging

Furnaces

14 / Heat Treater’s Guide Carburizing (diffusion Stress relieving

Normalizing Carburizing Nitrocarburizing Carbonitriding AMeding Carbon restoration Stress relieving Austenitizing

phase)

Box Furnaces Annealing Tempering Hardening Normalizing Stress relieving Aging Carburizing Malleabilizing Solution heat treating

Carbon

Bottom

Tip-Up

Annealing, i.e., wire, long bars, rods, pipe Hardening Spheroidizing Normalizing Malleabilizing Tempering Stress relieving

Furnaces

Annealing, i.e., coatings Hardening Normalizing Malleabilizing Stress relieving Carburizing Tempering Spheroidiiing Homogenizing

Wraparound

Vertical

Annealing, including long cycle annealing Hardening Tempering Normalizing Stress relieving Steam treating Homogenizing Carburizing Carbonitrid’mg Carbon restoration Bluing Nitriding Solution heat treating

Bell and Hood Furnaces Hardening Nitriding Aging Bluing Tempering Stress relieving Solution heat treating

Hearth

Quench

Case hardening Neutral hardening Clean hardening

of ferrous parts

Furnaces

Continuous

Slab and Billet

Solution heat treating Homogenizing Carbunzing

Walking

Beam Furnaces

Hardening Annealing Tempering Stress relieving Normalizing Sintering stainless steel compacts

Hearth

Furnaces

Hardening Annealing Carburizing Carbonitriding Carbon restoration Malleabilizing Tempering Austempering

Pusher Furnaces

Furnaces

Annealing Hardening Normalizing Malleabilizing Tempering Stress relieving Austempering Carburizing

Rotary

Solution heat treating Hardening Aging Malleabilizing Tempering Annealing Stress relieving Lab work

Integral

and Split Furnaces

Annealing Stress relieving

Pit Furnaces

Elevating

Furnaces

Furnaces

Annealing Carbonitriding Carburizing Hardening Normalizing Clean hardening

Heating

Furnaces

Heat Treating Processes and Related Technology

Screw Conveyor

Ferritic nitrocarburizing Malleabiliziig Solution heat treating Tempering Stress relieving Carbon restoration Spheroidizing

Furnaces

Hardening Tempering Annealing Stress relieving

Slotted Roof, Monorail Roller Hearth Furnaces

Nitriding. i.e.. extrusions Carburizing steel parts

Hearth Furnaces

cover gas

Rotary Hearth Furnaces Small ferrous parts Process and production testing Small volume production Hardening Tempering Austempering Anneahg Carburizing Carbon restoration Carbonitriding

chains. and other long and

Furnaces

and D? tool steels

Annealing. i.e.. bright annealing Hardening Tempering Stress relieving Cnrburizing Carbonitriding Depassinp Carbon deposition

Bed Furnaces

Nitrocarburizing Nitriding Carbonitriding Steam oxidizing Carburizing Hardening. bright type Tempering

Salt Bath Pot Furnaces

Shaker Hearth Furnaces Hardening, i.e.. neutral hardening Carburizinp Carbonittiding Stress relieving Normalizing Anneding Tempering Austempering

Furnaces

Vacuum Furnaces

Fluidized

Furnaces

Applications requiring hydrogen Heat treating stainless steel Annealing Stress relieving Carburizing Hardening

crankshafts.

Ion NitridingKarburizing

Tempering Hardening, i.e.. clean hardening Carbon restoration Annealing, i.e.. bright annealing Carbonitriding Austempering Carburizing Spheroidizing Homogenizing

Humpback

Conveyor

Annealing. i.e.. large castings, unusually shaped parts Hardening Tempering Annealing Normalizing Stress relieving

Solution heat treating Stress relieving Bluing Spheroidizing Tempering Nomutlizing Malleabilizing Hardening, i.e., clean hardening Tempering Carburizinp Carbonitriding Carbon restoration

Conveyor

/ 15

carbon steel and light case hardenmg

Austempering Martempering Hardemng Tempering Carburizing Cyaniding

Salt Bath Furnaces: Austempering. i.e.. ductile Carburizing Carbonitriding Nitrocarburizinp Nomtalizing Neutral hardening

Salt Bath Furnaces:

Austemper

Batch Austemper iron. steel

Mesh Belt

System

Austempering. i.e.. ductile Carboaustempenng steel

iron. steel

System

16 / Heat Treater’s Guide Neutral

Salt Based Furnaces

Quartz Tube Furnaces

Austempering Martempering Hardening

Cyanide

Sintering Heat treating

Rotating

Based Salt Type Furnaces

Furnaces

Heat treating, continuous long lengths of pipe, turbine, bars, rods, billets Included in quench and temper lines for high grades ofoil country tubing

Cloverleaf

Induction

Furnaces

primarily.

Treating

hardenable

Heating

types

Systems

Aging Stress relieving Hardening Annealing. i.e., bright annealing Carbonitriding Normalizing

Equipment

i.e., martensitically

Systems

i.e.. surface and localized

Resistance

Beam Surface

Surface hardening metals

Heat Treating

Hardening, Tempering

Hardening Normalizing Tempering Carburizing Annealing Carbonitriding Carbon restoration

Electron

Furnaces

Hardening Normalizing Tempering Annealing Stress relieving

Carburizing Case Hardening

Barrel

Finger

ferrous

Reference

Laser Heat Treating

Furnaces

I. Joseph H. Cireenberg, lndrtstrial Tirenml Processing Equipment Handbook, ASM International, 199-I

Annealing

Statistical

Process

Control

of Heat

Statistical process control (SPC) is being applied to advantage in heat treating shops with continuous, hatch, and single part operations. (A case history of how one shop has integrated this technology into its operations is reported in a sidebar feature to this article. In many instances. as in this one, teaming SPC with the computer is the next step). Ref I. Continuous equipment, such as rotary retorts, pusher carburizers, and belt furnaces, offer the most straightforuard approach to applying both statistical quality control (SQC) and SPC techniques to improle process performance. The high volume of work handled by continuous equipment provides many opportunities for sampling key product characteristics.

Treating

Operations

Problems can be predicted and corrective action taken in a timely manner. Also, special causes of prohlems are often more identifiable because process variables are steadier in continuous processes than they are in batch operations. Batch operations alloh a significant amount of sampling and analysis within a load. However, the only net payoff is a degree of confidence in treating an entire load. Process vmables must be monitored and analyzed to ensure that the process is under control, and that there is load-to-load and day-to-day repeatabilit~-especiall~ when each load is different in terms of part geometry. matenal. and/or specification.

Contribution of Selected Parameters to Variations in Effective Case Depth for Required 0.85 to 1.OO%Surface Carbon Level at 870 “C (1600 “F) Processing Temperature Variation Case depth mm in.

OS1 I .O? I .52 2.03

0.020 0.040 0.060

0.080

Temperature variation 28 T 11°C

(2OW 6 6 7 9

(AT) 56 =‘C

(50OF) (1~W I-l 16 17 19

33 34 35 36

in case depth for selected parameters,

Timevariation Smin 10 min 3 1 >I >I

7 ‘) ;

>I

(A I ) 30 min 30 5 2

I

0.10%

a a a a

Atmosphere 0.15% 13 13 13 13

%(a) Carbon 0.25% 27 27 17 27

tariatioo

(AC ) Quench uniformity(b) 0.05% 0.10% 0.20% I1 II

II II

23 23 23 23

45 45 45 45

(a) Total process variation = dA2+ B’ + C’ + D’ + Z-‘, where r\. B. C, D, and Zare ‘7%variations attributed 10AT. .I 1.aunosphere X. quench uniformity AC, and additional vtiahles. respectively (b) Variation in case c&on level u hen quenched to SOHRC

Heat Treater’s

Guide: Practices

and Procedures

for Irons and Steels

Copyright@ ASM International@ 1995

Heat Treating Processes and Related Technology / 17

Final hardness

Identification

distribution

of heat-treating

analysis

for a typical

variables

quench

for the neutral

and temper

hardening

operation

process

18 / Heat Treater’s

Guide

Variation in natural gas composition

monitored in the Canton, OH, area over nearly a 2l&year period

Plot of furnace temperature versus elapsed time to show that heat input equilibrium lags behind attaining of setpoint temperature after furnace loading

Plot of furnace temperature versus elapsed time to show effect of load size on heat balance equilibrium

Single part treatment, as with induction or flame treating, does not lend itself to using part evaluation techniques to predict negative results. The focus must be shifted to SPC and to the identification, monitoring, and control of process variables to ensure repeatability of results. Some variables that need to be considered are electrical power, flame temperature, scan speed, coil dimension, part positioning, and quenchant temperature. Trending of process variables can be utilized to determine special causes. Process deterioration is another factor that must also be taken into account in all types of heat treating operations. The challenge is to counter wear and tear on equipment with corrective action before out-of-specification parts are produced. Key process variables fall into three categories: those which ;LTecontrollable, those which aren’t, and those which are secondary. Controllable variables include temperature, atmosphere carbon potential. and quenchant temperature.

Uncontrollable variables include quench transfer time, temperature recovery time, and quench temperature rise. However, suitable courses of action are available. Examples follow: l

l

l

With most furnace systems. control of quench transfer time is not possible, but is often a critical parameter in producing good parts. A possible course of action is to monitor and analyze transfer time to get an early warning of trouble. One automatic control system compares maximum allowable transfer time needed to get the desired result with actual transfer times; an alarm is triggered when the maximum is exceeded, indicating a mechanical failure or deterioration in the system. Temperature recovery time can be determined, for instance, by measuring and analyzing the time taken by a batch furnace (with a standard load weight or empty) to reach set temperature. In this manner, trends, plotted

Heat Treating Processes and Related Technology / 19

Calculated CCT diagram from actual part composition to form during

l

heating.

Ac3: temperature

at which

with modeled part cooling rates. AC,: temperature

transformation

of ferrite

on an WC chart, may indicate a loss in furnace performance which, via investigation, could be traceable to damaged insulation, poor door seals, or heating system malfunction, for example. Knowing how quench temperature cycles from quench to quench can be important. Findings may trigger an investigation of the entire quenching system, which may suggest problems with quench agitation or quench cooling, for example. Furnace overloading is another possibility.

Secondary process variables, such as fuel consumption and additive atmosphere gas, are caused by deterioration in control loops. By monitoring gas or electrical consumption for a standardized furnace cycle and loading (or the furnace could be empty), diminished performance in the heating system can be detected. By monitoring and trending the amount of natural gas or propane addition required to control a given carbon potential setpoint, deterioration of furnace atmosphere integrity can be detected. Examples of parameters with an influence on effective case depth are given in an adjoining Table. A variable distribution analysis of hardness of a job is shown in an adjoining Figure. Heat treating variables involved in neutral hardening are given in an adjoining Figure. Changes in natural gas composition over an extended period are plotted in an adjoining Figure. How heat input equilibrium lags setpoint temperature after a furnace is loaded is shown in an adjoining Figure.

to austenite

is completed

during

at which heating

Effect of load size on heat balance equilibrium ing Figure.

Integrating

austenite

is indicated

begins

in an adjoin-

SPC and SQC

Potentials for real time process improvement can be realized by combining the disciplines of SPC. which focus on process variables, and SQC. which focus on product quality. The computer is needed to statistically analyze data in a way that allows timely adjustment of process. As a product characteristic (as-quenched hardness, for example) is shown to be trending away from average, a special cause, such as quench temperature. may be identified quickly. Ability to compare process variable trend charts to the product characteristic trend chart, for the same time period, offers a valuable tool for continuing improvement. Information can be valuable even if no special cause can be. identified among monitored process variables to correlate with a change in product quality. Such knowledge could lead the heat treater to an uncontrollable variable, such as material, more quickly than he could otherwise. An example of hou the computer is being utilized is shown in an adjoining Figure.

Reference I. Memls Hmcfbook. IO ed. Vol3.

Heat Treating,

ASM International

20 / Heat Treater’s

Guide

How a Commercial

Heat l’kater

This shop decided in 1989 to look into statistical processcontrol (SPC) as a way to track down sources of persistent processing problems. At the time. rework jobs (in carburizing and nitriding) were running at a rate of 25 to 30 per quarter. Ref 1. Consultants were hired to train the plant’s thirty-plus employees in the application of WC lo heat treating. how to recognize out-ofcontrol conditions. and how lo react correctly lo them. Training was thorough. but stopped short of teaching how-to-be statisticians. The program consisted of I2 h in the classroom(three 4 h sessions),plus followups on the shop floor lo answer questions as WC was being installed. The key to making SPC work, it was stressedcontinuously, is accuracy of data. At the same time. employees were assuredthat these data would be used as spotlight opportunities for impmvemen¬ to point the finger of blame at anyone.

The First Step The program was started by gathering data from carburizing furnaces.using simple SPC charts.Operatorsuseda shim shock test

9n early control chart shows large variations, with a low Drocess capability caused by poor understanding of Jariables

Uses SPC and the Computer to compare actual carbon in the working zone compared with the level set on the furnace controller and measuredwith an oxygen pl-0bl.L Resultsfell short of expectations-a typical chart from that period is shown in an adjoining Figure. Note the largediscrepancybetween oxygen probe and shim shock data. A seriesof meetings followed. which included the quality manager,production manager,and all shop employees.In addition. furnace operators.maintenancepeople, and all other employeeswere encouraged to submit suggestions for improvements. Ultimately. a decision was made to do capability studies of all carburizing and nitriding furnaces in the shop. covering, for instance,natural gas flow, air flow, nitrogen/methanol flow, load size, time in furnace. carbon control instrument settings,methodsoperators used lo run furnacesand to correct out-of-control conditions. Much of the inconsistency in performance, it was learned. was accountedfor by differences in practice from operator lo operator. To improve control here,procedureswere written, basedon proven strategiesfor correcting out-of-control conditions.

The same furnace, eight months later, remains within control limits of kO.O7% C

Heat Treating

With time, operators managedto keep data points closer to the target mean (for carbon potential setpoint), and control limits were set at ?0.07%. Improvement in the performance(seeprevious Figure) over a period of eight months is shown in the secondFigurenote that control limits were maintained within 0.07%. By 1992, reworks were down by a factor of four (see Figure). Reasonsfor rework, along with percentagesattrihutahle for each cause, are shown in the next Figure. Shallow case depth was the most common causefor rework, with a 23.3% rating. CauseNo. 2 was operator error, accounting for 20% of all rework. For each rework. the company evaluates findings, investigates, and corrects any areasof concern.

Statistical

Methods

The company now tracks performanceby processcapability values, C, and Cpk (see Figure for definitions of theseand other SPC terms). Information collected by operatorsis loadedinto a statistical program, which producesall values neededfor review by management.

Tighter

Shallow

control

and more-predictable

case depth and operator

process

results

and Related Technology

A processcapability study of furnace number 37 for one month is shown in an adjoining Figure. The Cpk is I.41 and the process capability index (C,) is I S2, showing that the natural variation in the process is less than the maximum acceptable range for the product. One year earlier, this furnace had a Cpkvalue of 0.55 and a C, value of 0.63. The company performs a Paretoanalysis (seeprevious Figure for definition) for all rework. Reasonsfor rework, the furnace. and the operatorsare recorded.

The Next Step The company has computerized all carburizers and oil hardening furnaces with atmosphereand temperaturecontrollers. With these controllers, furnace operation and tinal results are much more consistent than before. Controllers are also programmable. Operators simply input the correct program number to control all parametersrelated IO the carburizing cycle, ensuring that all temperatureand carbonpotential

have reduced

error were the most common

Processes

the number of reworks

reasons

for

reWOrk

in

1992

required

(30

reWOrkS

by a factor of four

total)

/ 21

22 / Heat Treater’s

Guide

SPC Terminology Mean, x: The central value in the range of processvariables, also known as the average.It is calculated by adding all readings and dividing by the total number of readings. Standarddeviation, O: A measureof the spreadof data values that is, the how far the data varies from the mean. It is calculated by the formula

whereXi is the valueof datapoint numberi. Zis the mean,andn is the total numberof datapoints. Control limits: Upper and lower control limits are defined as three times the standarddeviation (30) from the mean (X ) of a processvariahle.Statistically.99% ofreadingsshouldfallwithin thesecontrollimits.unlessthereisachangeintheprocess. Control chart: A graph used to record the readings of process variables. Each point in an x chart is typically an averageof four or more readings. Each point in an R chart is the difference

betweenthe highest and lowest readings(range).Trendsin control chart data can be signs of trouble. Examples include a point outside the control limits. sevenconsecutivepoints drifting in the samedirection, or fewer than two-thirds of the points within the middle third of the chart. Natural variation: Processvariable fluctuations that are beyond the control of the operator. The only way to reduce the amount of natural variation is to improve the process. Pareto analysis: A process used to identify what J.M. Juran talk the “vital few projects” for which quality improvement is justified; that is. those which contain the bulk of the opportunity for improvement. Named for Italian economist Vilfredo Pareto (1848-1923). Process capability index, C,,: The product specification or tolerance range divided by six times the standarddeviation. Cp indicates whether the process is able to meet the customer’s requirements.A value lessthan one indicates that natural variation will produce results that are out of spec. Actual Process Capability Index, Cpk: A stricter index than C, Cpk measurescentering as well as the amount of natural variation. It is defined asthe difference betweenthe processmean and its closest specification limit, divided by 30.

Heat Treating

Practical

Applications

of the Computer

A quick overview of available simulation software for on-line programs that control processes and those that assist in decision-making and process analysis is provided by the adjoining Table, which also lists and describes available databases developed by computers. Software programs can be subdivided as follows: l l l l

l

Property prediction programs Process planning programs Material selection programs and their databases Programs for special technical and economic programs related to heattreating, such as energy consumption for a given process or calculating the expense of a heat treatment Finite element analysis for modeling the effecti of quench severity or distortion and dimensional control of parts Simulation modeling with the computer can be subdivided thusly:

l

Static models based on empirical formulas

l

l

Processes

in Heat

and Related Technology

/ 23

Treating

Dynamic models based on differential equations or differential equation systems Programs with both static and dynamic models

Static models are based on simple empirical formulas that can be derived by physical principles and observation or from statistical methods. Generally, regression analysis is used in statistical modeling. Example: Formulation or prediction of Jominy hardenability from austenitic grain size and chemical composition (Ref l-3). Dynamic models are based on the solution of differential equations, differential equation systems, or finite element analysis. Examples of the differential equation approach: predicting carbon and nitrogen profiles (Ref 4-6) phenomenological models that describe the transformation of austenite under nonisothermal conditions (Ref 7-l I). Finite element analysis is used, for example, to predict residual stress and distortion (Ref 12-14) and in determining suitable quenchants (gas, oil, or water) for a given alloy (Ref 12).

24 / Heat Treater’s Guide Examples of Available Computer Programs and Databases Pertaining to Steel Selection, Microstructure, and Heat-Treatment Technologies

Computerized hlat.DB

Features

Availability

Name of the sofhvare materials

properties storage, retrieval, AShl lntemational. U.S.A.

and use

Database Steelhiaster

PERlTUS

A LlETA

SACfTSteel Advisory Centre for Industrial Technologies, Hungary

KOR

SACfTSteel Ad\ isory Cenue for Jndustrtal Tu-hnologies. Hungary

Computer

programs

Materials data base management program containing the designations, chemical compositions, forms (sheet bar and so forth), and properties t up to -MI properties). It is designed to select alJoys on the basis of many characteristics Contains the chemical compositions. meshanicaJ properties, application fields, and the international comparison tequiv alent steels) of 6500 standard steels from I8 countries Contains compositions, mechanical properties. heat-treatment parameters, CCTdiagrams. tempering charts for commonly used German structural and tool steels The heat-neaanent technologies designed by the user of the softwate can be stored and retrieved This data hase pro\ ides engineers uith up-to-date information about materials ranging from traditional met& to new polvmers. The range of information: mechanical and physical properties, environmental r&istance. material forms. processing methods, trade names, and standan% This data base of individual measured steel properties contains data collected from laboratories of industry quality control departments. The range ofdata: steel designation, heat number, dimensions of the machine part. composition, heat treatment of the part, results of tensile tests, impact test results, measured Jominy curve of the heat, and other tests. The system makes statistical analysis of the data KOR is a corrosion information system. which contains a data base of 3OOcorrosive media, more than IS 000 individual corrosion dataset I50 metallic structural materials. and 200 isocorrosion diagrams. Structural material selection is possible according to prescribed mechanicrd. physical, technological properties. or it is possible to find a suitable resisting material fora corrosive medium withgtven temperatureandconcentratJon.The system #ill alsoaccept the user’sowndata

SACIT Ste4 Advisory Cenae for Industrial Technologies, Hungary Dr. F?Sommer Wkrkstoftiechnik GmbH. Germany hlatsel Systems Ltd., Great Britain

EQUJST 2.0

for calculation

of processes

occurring

in steels during

PRJZDIC & TECH

SACIT Steel Ad\ isory Centte for industrial Technologies. Hungary

AC3

Marathon

CETfM-SICLOP

PREVERT

Cenue Technique des Industries Mechaniques PROGETfM. France Comline Engineering Software, Great Britain and ASM International Creusot-Loire Industries. France

CHAT

lntemational

hlfNlTECH

hlinitech

PRJZDCARB

SACfTSteel Advisory Centm for Industrial Twhnologies. Hungary

SINULAN

Lammar.

Ensam Bordeaux.

C4RBCALC

Marathon

hlonitors

CARBODIFF

Process Electronic.

Carbo-O-Proof

lpsen Industries Ltd.. U.S.A.

SYSM’ELD

Framasoft.

SteCal

Examples

of programs

Monitors

Limited.

Company.

Calculates the micmsmtcture and mechanical properties ofquenched and tempered low-alloy steels from composition and heat-treating parameters CHAT is a two-part system for selecting the optimum steel composition to be used where heat treating is perfomted to develop required engineering pmperties The hlinitech Alloy Steel Information System consists of tvvelve computer programs which generate a series of hardenability-related properties of steels. such as Jominy curves. hardenahility bands, mechanical properties of hot rolled products. hardness distributions for quenched and tempered and carburized products This computer program detemunes the gas carburizing technology and calculates the carbon profile and hardness distribution in the case and core on the basis of chemical composition, dimensions of the workpiece. cooling intensity of the quenchant, prescribed characteristics of the case Simulates the gas carburization and inductton hardenmg process. and calculates the carbon and the hardness profile Smtulates the carburirmg reactions between a steel and surrounding atmosphere. It calculates the carbon profile hlonitoring of carbon protile dunng carburizing and prediction of hardness distribution after quenching ofcase-hardened steels This software is able to optimize the carburizing process, calculates continuously the carbon profile, and regulates the process in accordance \v ith program target values This system is based on finite-element technique and simulates the transformation processes in steel during heat treatment or welding. The program calculates the temperaturedistribution. microsnucture, hardness. and stresses

U.S..\.

Canada

France

Ltd.. Great Britain Gemtatty

Great Britain

based on finite

element

analysis

heat treatment

Stmulates the cooling. transfomtation of austenite in cylindrical. plate-shaped workpieces, Jominy specimens made of case-hardenable and quenched and temprrcd low-alloy steels and calculates the microstructure and mechanical properties in any location of the LTOSSsection of the workpiece taking into account the actual chemical composition, dimensions. austenitizing temperature, duntions, cooling intensity of quenchant, tempering temperature. and time. The same program worksas technology plannmg program if the prescribed mechanical properties and composition are given Hardenability model designed to predict the response to quenching of through-hardening and carburized loa -ahoy steels in terms of microstructure and hardness distribution Contains a steel data base for the selection of structural and tool steels and calculates the mechanical properties along the cross section of \5 orkpieces Calculates the heat-treatment response and properties of lo\\-alloy steels from composition

Ltd.. Great Britain

Harvester

include:

tinuous

cooling

H ith the results l

CONTA

program-for

l

TOPAZ

2D program-for

calculating

l

NIKE

2D program-for

surface

calculating cttkulating

heat fluxes

temperatures stresses

overviews

of the subject

Database systems metal alloys them include

are being chemical

containing marketed. composition,

are found

(Ref

(Ref

(Ref

State of the Art Uses of Computer General

Properties,

13)

I-%)

ISj

Simulation

in Ref

I6 and

17.

the main characteristics of several lnfomtation that can be retrieved front mechanical characteristics. and con-

transformation

(CCT)

of user process

planning.

curves.

Databases

can

be loaded

Example: Research Ltorkers at hlinitech Ltd (Canada) designed a soliware package to estimate such properties as weldability. phase diagrams, and hardenability of low-. medium-, and high-carbon steels (Ref 16). Example: Chrysler Corporation developed an interactive system that makes it possible for designers and technologists to get material information on their own local computer terminals (Ref 16). Example: Utilization of databases of measured steel properties is discussed in Ref 18. The CETIM Institute (France) has developed a program for the planning of heat rrcatment technology and for steel selection. An essential part of the

Heat Treating Processes and Related Technology software is a database containing chemical composition, mechanical properties, and Jominy curves of the most often used quenched and tempered and case hardened steels as a function of section size (Ref 19). Hardenability prediction has been of longstanding theoretical and practical interest (Ref 20-24). In applying a static model, Murry et al. (Ref 25) developed a computing method for predicting the hardness of cylindrical workpieces along their cross section after quenching. Input data are: chemical composition. austenite grain size, geometrical characteristics, and cooling time from 700 to 400 “C ( 1290 to 750 “F). Creusot-Loire (Ref I6 and 26) used nonlinear multiple regression analysis to derive a series of formulas for the estimation of critical cooling rates from 700 “C ( I290 “F). The steelmaker aJso published equations to calculate as-quenched and tempered hardness from chemical composition and cooling rate from 700 “C ( 1290 “F). Starting from a thermodynamic basis, researchers at McMaster Llnivershy (Hamilton, Ontario, Canada) developed methods for the computeraided determination of equilibrium diagrams of multicomponent steel alloys and for the calculation of starting curves (incubation time) of isothemtal transformation diagrams as well (Ref 17. 23, 37). They also investigated the tempering process and developed usable computer programs for the prediction of hardenability and its application in steelmaking.

Programs for material selection and/or analysis of heat treatment processes usually contain a system for property or hardenabilit! prediction. Liscic and Ftletin (Ref 21. 22). for example, published a computerized process designing a system for the heat treatment of quenched and tempered steels. The system is suitable for the determination of technological parameters (austenitization and tempering temperatures), knowing the steel type and required properties. More sophisticated models based on finite element analysis are being investigated as a way of modeling distortion and analyzing quenching methods (Ref 12). Analysis of residual stresses and distortion generally in\ elves finite element anaJysis of internal stresses developed during transformation sequences. Typical examples are given in Ref I?, 28-30. A method of calculating transformation sequences in quenched steels is found in Ref41. A software package has been developed for the prediction of residual stresses in case hardened steels by tracing the transformation of the case and core of the workpiece (Ref 32 and 43). Simulation of Case Hardening. New type models predict carbon and nitrogen profiles during and after gas carburizing and nitriding t Ref 5. 6.28-31). In this field, calculation methods can be used to model case depth and hardness proftles (Ref 30, 35. 36). lngham and Clarke developed a computerized method of predicting the microstructure and hardness profile of case hardened parts. Methods of microstructure prediction are described in Ref 8 and 37. A description of how a commercial heat treater is using SQC. SPC. and Process Control in Heat the computer is found in the article. “Statistical Treating Operations,” preceding this one. This article is based on article, “Computerized Properties Prediction and Technology Planning in Heat Treatment of Steel,” AShl hietals Handbook, Heat Treating, Vol 4. IO ed.. Hear Treatirrg Handbook. ASM International.

References I. C.A. Siebert, D.V. Doane. and D.H. Breen. The Hurdetu~biliy of.Sireels-

Cor~cep~s.Memlhrrgical Itljluences and Indrrsrrial Applicarions, American Society for Metals. I977 2. E. Just, Formeln der Hartbarkeit, Hiin.-Tech. Min., Vol23 (No. 2). 1968. p 85-99 3. E. Just, New Formulas for Calculating Hardenability Curves, Mer. Prog.. NW 1969, p 87-88 4. J. Slycke. T. Ericsson, and P Sjoblom. Calculation ofcarbon and Nitrogen Profues in Carburizing and Carbonitriding. Corrzpwers iu Marerials Technology, Proceedings of the International Conference. Linkoping Llnivershy. 4-S June 1980. T. Ericsson. ed.. Pergamon Press. p 69-79

/ 25

5. EA. StiU and H.C. Child, Predicting Carburizing Data. Hear. Treat. Met.. No. 3, 1978. p 67-72 Carburizing Process, Mefull. 6. CA. Stickcls, Analytical Models for the GZLS Trans. B., Vol30B, Aug 1989. p 535-546 7. T. R&i. G. Bobok, and M. Gergely, “Computing Method for Nonisothernlal Heat Treatments.” Paper presented at Heat Treatment ‘8 I, The Metals Society, 1983, p 91-96 8. E. Ftiredi and M. Gergely, A Phenomenological Description of the Austenite-Martensite Transformation in Case-Hardened Steels, Pmceedings of lhe 3rh Ituernarional Congwss on Hear Treamwtrr of Materials, Vol I, 3-7 June 1985. p 291-301 9. T. R&i. hl. Gergely. and P. Tardy, hlathematical Treatment of Non-isothermal Transformations. Aluclrer:Sci. Technol.. Vol 3, May 1987, p 365-371 IO. E.B. Hawbolt. B. Chau. and J.K. Brimacombc, Kineticof Austenite-Pearlitc Transformations in a 1025 Carbon Steel, Melall. Trans. A, Vol l6A. April 1985. p 568-578 I I S. Denis. S. Sjosuiim. and A. Simon. Coupled Temperature, Stress, Phase Transformation Calculation Model: Numerical Jllustration of the Internal Stresses Evolution during Cooling of a Eutectoid Carbon Steel Cylinder, h~lemll. Trans. A, VOI l8A, July 1987, p I203- I2 I2 I2 R.A. Wallis et al., Application of Process hlodeling to Heat Treatment of Superalloys. /rid. Hear.. Vol 55 (No. I). Jan 1988, p 30-33 13. J.V. Beck. “Users Manual for CONTA: Program for Calculating Surface Heat Fluxes from Transient Temperatures inside Solids.” Report SAND83-7 131. Sandia National Laboratories, Dee 1983 I-2. A.B. Shapiro. ‘TQPAZZD: A Tvvo-Dimensional Finite Element Code for Heat Transfer Analysis. Electrostatic and Magnetostatic Problems,” Report LJCJD-20824. Lawrence Livemtore National Laboratory, July 1986 IS. J.O. Hallquist. “NlKE2D: A Vectorized, Implicit, Finite Dcfomtation. Finite Element Code for Analyzing the Static and Dynamic Response of 2-D Solids.” Report LJCJD- 19677. rev. I, Lawrence Livermore National Laboratory, Dee I986 16. D.V. Deane and J.S. Kirkaldy, ed.. Hardenabiliry Concepts with Applications ro Sled. Symposium proceedings, 24-26 Ott 1977, American Society for hletals. p 493-606 17. T. Ericsson, Ed.. Conrpurers in Materials Technolog?: Proceedings of the International Conference. 4-S June 1980, Linkoping University, Pergamon Press, p 3-68 18. hl. Gergely, T. Reti. G. Bobok. and S. Somogy i. “Lltihzation of Databases of Measured Steel Properties and of Heat Treatment Technologies in Practice,” Paper presented at hlatcrials ‘87, The Metals Society, I l-14 May 1987 19. C. Lebreton and C. Tout-trier. CETlM-SICLOP: Un nouvel outil logiciel pour le tmitment themtique. Traif. 77rrrrn.. No. 308.1987. p l-8 (in French) 20. hl.E. Dakins. C.E. Bates, and G.E. Totten. Calculation of the Grossmann Hardenability Factor from Quenchant Cooling Curves, Memlhtrgic~, Furnace supplement. Dee 1989. p 7 2 I. B. Liscic and T. Fiietin, Computer-Aided Evaluation of Quenching Jntensity and Prediction of Hardness Distribution. J. Hear Trear.. Vol 5 (No. 2). 1988. p 115-124 32. B. List+ ,and T. Fiietin, Computer-Aided Determination of the Process Parameters for Hardening and Tempering Structural Steels. Hear Treur. hder.. No. 3. 1987. p 62-66 23. J.S. Kirkaldy, G.O. Pazionis. and SE. Feldman, “An Accurate Predictor for the Jominy Hardenability of Low-AUoy Hypoeutectoid Steels,” Paper presented at Heat Treatment ‘76. The hletals Society. 1976 2-t. hl. Umemoto, N. Komatsubara, and I. Tamura Prediction of Hardenability Effects from lsothemtlll Transfomtation Kinetics, ./. Hear Trrrrr, Vol I (No. 3). 1980. p 57-6-l 25. G. blurry. hl&hode Quantitative d’ Appreciation de la Trempabihte des Aciers: Esemples d’ Application. R~I: Mc~~ull..Vol 12. 197-l. p 873-895 (in French) 26. l? hlaynier. Le Pretert: hlodcl dr: Prevision des Charncteristiques hlechaniques des Aciers, Ir,,ri/. Tltentt.. Vol223. 1988. p 55-62 (in French) 27. J.S. Kirkaldv and R.C. Sharma. A New Phenomenology for Steel IT and CCT Cun es. Scr: MeraIl.. \;bl 16. 1982. p I I93- I 198

26 / Heat Treater’s Guide 28. M. Gergely

29.

30.

3 I.

32.

33.

34.

35.

36.

and T R&i. Application of a Computerized Information System for the Selection of Steels and Their Heat Treatment Technologies, J. Hear Tmat., Vol5 (No. 2). 1988.~ 125-140 T. R&i, M. RCger, and M. Gergely, Computer Prediction of Process Parameters of Two-Stage Gas Carburizing, J. Hear Treat., Vol8, 1990, p 55-61 U. Wyss, Kohlenstoff und Hglrteverlauf in der Einsatzb&tungsschicht-verschiedenen legierter Einsatzhlihle, Htirr. -7kh. Mirt.. Vol43 (No. I ), 1988, p 27-35 (in German) T. R&i and M. Cseh. Vereinfachtes mathematisches Model fiir awistugige Autlcohlungsverfahren. H&f.-Tech. Min., Vol42 (No. 3). 1987, p 139-146 (in German) J. Wiinning, Schichtwachstum bei S~ttigungs- und Gleichgewichtsaulkohlung-sverfahren, H&.-Tech. Mu.. Vol 39 (No. 2). 1984, p 50-54 (in -) B. Edenhofer and H. ffau. Self-Adaptive Carbon Pmfik Regulation in Carburizing, Proceedings of the 6th International Congress on Heat Treatment of Materials, 28-30 Sept 1988. p 85-88 D.W. lngham and PC. Clarke, Carburize Case Hardening: Computer Prediction ofStructure and Hardness Distribution, Hear Treat. Met., Vol IO (No. 4). 1983, p 91-98 N.F. Smith Computer Prediction of Carbtuized Case Depth: Some New Factors lnlluencing Accuracy of Practical Results, Heat Treat. Met., No. I, 1983. p 27-29 D. Roempler and K.H. Weissohn. Kohlenstoff und Hglrteverlauf in der Eiiaehslrtungsschicht-Zusatzmodul fk Dilkionsrechner, Hiin.-Tech.

Min. Vol44,1989, p 360-365 (in German) 37. M. Gergely, T. R&i, P Tardy, and G. Buzz. “Prediction of Transformation Chamctaistics and Microstructure of Case Hardened Engineering Components,” Paper presented at Heat Treatment ‘84. 24 May 1984. The Institute of Metals 38. S. Kamamoto et al., Analysis of Residual Stress and Distortion Resulting loom Quenching in Large Low-Alloy Steel Shafts, Mare,: Sci. TechnoL.Vol 1,Oct 1985, p 798-804 39. P. Jeanmart and J. Bouvaist, Finite Element Calculation and Measurement ofThermal Stresses in Quenched Plates of High-Strength 7075 Aluminum Alloy, Mater: Sri. Technol., Vol I, Ott 1985, p 765-769 40. A.J. Fletcher and A.B. Soomro, Effects of Transformation Temperature Range on Generation of Thermal Stress and Stress during Quenching, Mater: Sci. Technol., No. 2, July 1986, p 7 14-7 19 41. M. Gergely, S. Somogyi, and G. Buza, Calculation of Transformation Sequences in Quenched Steel Components to Help Predict lntemal Stress Distribution, Mates Sci. Tech&., Vol I, Ott 1985. p 893-898 42. B. Hildenwall and T. Ericsson, Prediction of Residual Stresses in CaseHardening Steels, in Hardenability Concepts with Applications to Steel, Symposium proceedings, 24-26 Ott 1977, D.V. Doane and J.S. Kirkaldy. ed, American Society for Metals, p 579-606 43. B. Hikienwall and T. Ericsson, How, why, and When Wii the Computed Quench Simulation be Useful for Steel Heat Treaters, in Compufers in Materials Technolog?: Proceedings of the Lntemational Conference, Linkiiping University, 4-S June 1980, T. Ericsson, ed.. Pergamon Press, p 45-53

Guidelines

for the Heat Treatment

of Steel

introduction Articles

in this chapter address the hands-on aspects of:

l

Normalizing

l

Annealing

l

Surface hardening

The Normalizing

l

l

Quenching/quenchants other processes) Tempering (including

(articles

on eight conventional

articles on martempering

processes and 17

and austempering)

Process

This process is often considered from both thermal and microstructural standpoints. In the thermal sense, normalizing is an austenitizing heating cycle, followed by cooling in still or agitated air. qpical normalizing temperatures for many standard steels are given in an accompanying Table. ln terms of microstructure, areas that contain about 0.8% C are pearlitic. Those low in carbon are ferritic.

Range of Applications AU standard, low-carbon, medium-carbon, and high-carbon wrought steels can be normalized, as well as many steel castings. Many weldments are normalized to refine the structure within the weld-affected zone, and maraging steels either can’t be normalized or are not usually normalized. Tool steels are generally annealed by the supplier. Reasons for normalizing are diverse: for example, to increase or decrease strength and hardness, depending on the thermal and mechanical history of the product.

Comparison of time-temperature cycles for normalizing and full annealing. The slower cooling of annealing results in higher temperature transformation to ferrite and pearlite and coarser microstructures than does normalizing. Source: Ref 1

In addition, normalizing functions may overlap with or be confused with annealing, hardening, and stress relieving. Normalizing is applied, for example, to improve the machinability of a pact. or to refine its grain structure, or to homogenize its grain structure or to reduce residual stresses. Tie-temperature cycles for normalizing and full annealing are compared in an adjoining Figure. Castings are homogenized by normalizing to break up or refine their dendritic structure and fo facilitate a more even response to subsequent hardening. Wrought products may be normalized, for example, to help reduce banded grain structure due fo hot rolling and small grain size due to forging. Details ofthree applications are given in an adjoining Table. including mechanical properties in the normalized and tempered condition. Normalizing and tempering can be substituted for conventional hardening when parts are complex in shape or have sharp changes in section. Otherwise. in conventional hardening such parts would be susceptible to cracking, distortion, or excessive dimensional changes in quenching. Rate of cooling in normalizing generally is not critical. However, when parts have great variations in section size. thermal stresses can cause distortion. Tie at temperature is critical only in that it must be sufficient to cause homogenization. Generally, a time that is sufticient to complete austenitization is all that is required. One hour at temperature, after a furnace has recovered, per inch of part thickness, is standard. Rate of cooling is significantly influenced by amount of pearlite. i& size, and spacing of pearlite IameUae. At higher cooling rates more pearlite forms and lamellae are finer and more closely spaced. Both the increase in pearlite and its greater fineness result in higher strength and hardness. Lower cooling rates mean softer parts. Cooling rates can be enhanced with fans to increase the strength and hardness of parts, or to reduce the time required, FoUowing the furnace operation, for sufficient cooling to allow workpieces to be handled. After parts cool uniformly through their cross section to black heat below Arl, they may be water or oil quenched to reduce total cooling time. Cooling center material in heavy sections to black heat can take considerable time.

Carbon

Steels

Steels containing 0.20% C or less usually are not treated beyond normalizing. By comparison, medium- and high-carbon steels are often tempered

28 / Heat Treater’s Typical

Normalizing

Guide Temperatures

Temperature(a) OF OC

Grade

Plain carbon steels 1015 915 1020 915 10’1 91s IO3 900 1030 900 IO35 88.5 lo40 860 104s 860 ioso 860 I060 830 IO80 830 1090 830 109s 8.45 III7 900 II37 885 II-II 860 II44 860 Standard alloy steels I330 900 1335 870 13-m 870 313s 870 31-m 870 3310 92s (a) Based on Production should be cooled in still

Typical

Grade

of Normalizing Steel

Cast50mm(?-in.)~akhcdy. 191025 mm C3/,to I in.) in section thickness

Ni-Cr-hlo

41.37 forging

Temperature(a) T OF

1IUl

and Tempering

Temperature(a) T OF

Grade

of Steel Components

Beat treatment Full annealed at 955 “C (I 750 “FI. notmtizedat 870°C (1600°F). tempered at 665 “C ( 1275 “F) Nomtized at 870 “C ( l6lXl ‘F). tempered at S70 “C ( 1060 “F) Normalized at 870 “C ( 1600 “Rand tempered

after normalizing, i.e., to get speciftc properties such as lower prior to straightening. cold working. or machining.

Alloy

Temperature(a) oc OF

Grade

I675 I675 1675 I650

Part

\‘d\r-honnet

Carbon and Alloy Steels

Standard alloy steels (continued) Standard alloy steels (continued) Standard alloy steels (continued) 4027 900 16.50 1700 8645 870 1600 1817 92s 4028 900 1650 1700 8650 870 1600 -1820 925 403’ 900 1650 870 1600 8655 870 1600 SO% 4037 870 1600 1700 8660 870 1600 5120 925 1650 4042 870 1600 5130 900 8720 92s 1700 1650 8740 92s 1700 I615 ‘m-17 870 1600 5132 900 870 1600 8742 870 1600 4063 870 1600 513s I575 4118 925 1700 870 1600 8822 925 1700 IS75 5140 870 I600 9255 900 16.50 IS75 4130 900 1650 51-E 413s 870 1600 870 1600 9260 900 1650 1525 5147 9262 900 1650 Jl37 870 1600 870 1600 IS?5 SISO 9310 925 1700 ‘II40 870 1600 870 1600 1515 5155 I.550 4142 870 1600 870 1600 9840 870 1600 5160 41-15 870 I600 1700 98SO 870 1600 6118 925 1650 41.47 870 I600 1700 SOB40 870 1600 I63 6120 9’5 1650 4150 870 1600 6150 900 SOB-M 870 1600 I575 4320 925 1700 1700 5OB-l.6 870 1600 157s 8617 925 4337 a70 1600 1700 508.50 870 1600 8620 91s 43-u) 870 I600 1700 60860 870 1600 8622 935 I650 4520 92s I700 1650 81835 870 1600 862.5 900 1600 86845 870 1600 4620 925 1700 1650 8627 900 I600 1650 4621 925 1700 8630 900 91BlS 925 1700 1600 870 1600 91Bl7 925 1700 4718 92s 1700 8637 I600 4720 925 1700 870 1600 91830 900 16.50 86-m 1700 4815 925 1700 870 1600 94B-U) 900 l6SO 8642 experience, normalizing trmpenture may \ary from as much a 28 “C (50 “F) helow. to as much as 55 “C (100 “FJ above. indicated temperature. The steel air from indicated tstitperature.

Applications

Forged flange

for Standard

hardness

Steels

Forgings, roUed products. and alloy steel castings are often normalized as a conditioning treatment before tinal heat treatment. Normalizing also reftnes grain structures in forgings. rolled products. and castings that have been cooled nonuniformly from high temperatures. Some alloys require more care in heating to prevent cracking from thermal shock. They also require long soaking times because of louer austenitizing and solution rates for c,arbon. Cooling rates in air to room temperature for many alloys must be carefully controlled. Some alloys are forced air cooled from the normalizing temperature to develop specific mechanical properties.

Forgings When forgings are normalized prior to carburizing or before hardening and tempering, the upper range of normalizing temperatures is used. But

Properties after treatment

Reason for

qormaRiing

To meet mechanical-property Tensile strength. 620 MPa (90 ksi); 0.X yield strength. -I IS hlPa (60 I&): requirements elongation in SOmm. or 1 in.. 20%; reduction in area. 40% To reline gmin size and obtain required Hardness. XXI to 23 HE hardness Hardness. 220 to 210 HB To obtain uniform structure, improved machinability, and required hardness

when normalizing is the tinal heat treatment, the lower temperature range is used. Small forgings are typicall> normalized as-received from the forge shop. Large. open die forgings are usually normalized in batch furnaces pyrometrically controlled to a narrow temperature range. Low-carbon steel forgings containing 0.2% C or less are seldom normalized. Multiple Treatments. Carbon and low alloy steel forgings with large dimensions are double normalized when forging temperatures are extremelj high (Ref 2) to obtain. for example, a uniform fine grain structure to pet specific properties such as impact strength to subzero temperatures.

Bar and Tubular

Products

Nomlalizing is not necessary and may be inadvisable when properties of these products obtained in the finishing stages of hot mill operation are close to those produced in normalizing. But reasons for normalizing bar and tube are generally the same as those that apply lo other steel products.

Guidelines

Castings In industrial practice, castings may be normalized in car bottom, box. pit, and continuous furnaces. Heal treatment principles are standard for all these furnaces. When higher alloy castings, such as C5, C I?, and WC9, are loaded, furnace temperatures should be controlled to avoid thermal shock that could cause metal failure. A safe loading temperature in this instance is in the range of 315 to 425 “C (600 to 795 “F). Lower alloy grades tolerate furnace temperatures as high as 650 “C (I200 “F). Carbon and low-alloy steel castings can be charged at normalizing temperatures. After charging, furnace temperatures are increased at a rate of approximately 225 “C (400 “F) per h, until the normalizing temperature is reached. Depending on steel composition and casting configuration, the heating rate

Annealing

Cycles

Cycles fall into three categories, cooling methods (see accompanying l

l

l

of Steel / 29

may be reduced to approximatelq 28 IO 55 “C (SO to 100 “F) per h, to avoid cracking. Extremely large castings may be heated more slowly to prevent the development of extreme temperature gradients. After normalizing temperature is reached. castings are soaked for a period that ensures complete austenitization and carbide solution. After soaking, parts are unloaded and allowed to cool in still air. Use of fans, air blasts. or other means of speeding up the cooling process should be avoided.

References I. G. Ksauss, Sleels: Heor Treurrnerrr cm1 Processing Principles, International. Metals Park, OH, 1990 2. A.K. Sinha. Ferrars Pi~~sical Memll~r~~, Butterworths, 1989

ASM

of Steel

Ln this process, steels are heated to a specific temperature, held at Ihat temperature for a specific time, then cooled at a specific rate. Generally, in treating plain carbon steels, a ferrite-pearlite microstructure is produced (see adjoining Figure). Softening is the primreason for annealing. Other important applications are to facilitate cold work or machining, IO improve mechanical or electrical properties, or LO promote dimensional stability.

Annealing

for the Heat Treatment

based on heating table):

temperatures

and

Subcritical annealing-the maximum temperature may be below the lower critical temperature, A 1 Inlercritical annealing--the maximum temperature is above Al, but below the upper critical temperature, A3, for hypoeutectic steels. or AC,,, for hypereutectic steels Full annealing-the maximum temperature is above A3

Austenite is present at temperatures above Al, so cooling practice (see Table) through transformation is a critical factor in getting the desired microstructure and properties. Steels heated above A 1 are subjected LO slow, continuous cooling, or to isothermal treatment at a temperature below

A fully annealed 1040 steel showing a ferrite-pearlite structure. Etched in 4% picral plus 2% nital. 500x

micro-

Al, at which transformation to the microstructure wanted can occur in a reasonable time. In some applications, two or more annealing cycles are combined or used in succession to get a specilied result.

Subcritical

Annealing

Austenite is not formed in this type of treatment. The prior condition of a steel is modified by such processes as recovery, recrystallization, grain growth. and agglomeration of carbides. The prior history of a steel is important in subcritical annealing. In treating as-rolled or forged hypoeutectoid steels containing ferrite and pearlite, the hardnesses of both constituents can be adjusted. But if substantial softening is the objective, times at temperature can be excessively long. Subcritical annealing is most effective on hardened or cold worked steels, which recrystallize readily LOform new ferrite grains. The rate of softening increases rapidlq as the temperature approaches Al. A more detailed discussion of subcritical annealing is found in Ref I.

Intercritical

Annealing

Austenite begins to form when the temperature of the steel exceeds Al. Carbon solubility rises abruptly (nearly 1%) near the Al temperature. In hypocutectoid steels. the equilibrium structure in the intercritical range between Al and A3 consists of ferrite and auslenite, and above Aj. the smcture becomes totally austenitic. But the equilibrium mixture of ferrite and austenite is not obtained immediately. For example. Ihe rate of solution for a typical eutectoid steel is shown in an accompanying Figure. In hypereutectoid steels. carbide and austenite coexist in the intercritical range betn een A I and A,-,,,. The most homogeneous structure developed at h&her austenitizing temperatures tends to promote lamellar carbide struclures on cooling. while lower austenitizing temperatures result in less homopenous nustenite. which promotes the formation of spheroidal carbides. Temperature-time plots shoiving the progress of austenite formation under isothermal (IT) or continuous transformation (CT) conditions for many steels have been published (Ref 2,3). Cooling After Full Transformation. After complere transformation to austenite. little else of metallurgical consequence can occur during cooling to room temperature. Extremely slow cooling can cause some agglomeration of carbides, and, consequently. some slight additional softening of the steel: but in this case. such slow cooling is less effective than high-temperature transformation. This means there is no reason for slow cooling after transformation is completed and cooling from the uansformation temperature may be as rapid as is feasible to minimize the time needed for the operation.

30 / Heat Treater’s

Approximate

Steel 1010 I020 1030 IO40 1050 loa 1070 1080 1340 3140 4027 4042 4130 4140 4150 4340 4615 5046

5120 51-U) 5160 52100 6150 8115 8620 8640 9260

Austenitizing

Guide

Critical

Temperatures

Critical temperaACI T OF 725 725 725 725 725 725 725 730 715 735 725 725 760 730 745 725 725 715 765 740 710 725 750 720 730 730 745

1335 I335 1340 I340 1340 1340 1340 1345 1320 1355 1340 1340 I395 1350 1370 1335 1340 I320 1410 1360 1310 1340 1380 1300 1350 I350 1370

for Selected

Carbon and Low-alloy

on heating at 28 “C/h (SOOF/h) AC, T OF 875 845 815 795 770 745 730 735 775 765 805 795 810 805 765 775 810 770 840 790 765 770 790 840 830 780 815

1610 1555 I495 1460 1415 I375 I350 I355 1430 I-110 1485 1460 1490 I480 I410 1325 1490 I-120 I540 I450 1410 I415 l-150 I540 I525 1135 1500

Steels Critical temperatures on cooling at 28 “c/b (50 OF/h) An An OF T T OF 850 815 790 755 740 725 710 700 720 720 760 730 755 745 730 710 760 730 800 725 715 715 745 790 770 725 750

1560 1500 I450 I395 I365 1340 1310 1290 1330 1330 1100 I350 I390 1370 1335 1310 I400 1350 1470 1340 I320 I320 I370 1450 141.5 1340 1380

680 680 675 670 680 685 690 695 620 660 670 655 695 680 670 655 650 680 700 695 675 690 695 670 660 665 715

1260 I250 I240 1260 1265 I275 1280 II50 1220 I240 1210 1280 1255 I240 1210 1260 1290 1280 1250 1270 1280 1240 I220 1230 1315

rate-temperature curves for comnmercial plain carbon eutectoid steel. Prior treatment was normalizing from 675 “C (1605 OF); initial structure, fine peariite. First curve at left shows beginning of disappearance of pearlite; second curve, final disappearance of pearlite; third curve, final disappearance of carbide; fourth curve, final disappearance of carbon concentration gradients.

Guidelines

for the Heat Treatment

of Steel / 31

The iron-carbon binary phase diagram showing region of temperatures for full annealing (Ref 4)

Recommended

Temperatures

and Cooling

Cycles for Full Annealing

Data are for forgin s up to 75 mm (3 in. in section thickness. Time at temperature thick; l/2 h is adde 8 for each additional 3 5 mm (1 in.) of thickness.

of Small Carbon Steel Forgings usually is a minimum of 1 h for sections up to 25 mm (1 in.)

Cooling cycle(a) Annealing

temperahwe

T

OF

Steel

T

OF

From

To

From

1018 IO.20

85WOO

lo22

85WOO 855~900

1575-1650 1575-1650 lS75-1650 1575-1650 ISSO-1625 ISSO-162s 1350-I600 IJSO-1600 IdSO-1600 1450-1550 1450-1550 1150-1550 1450-1525 1450-1525

855 855 855 855 8-U 845 790 790 790 790 790 790 790 790

705 700 700 700 650 650 650 650 650 650 6.50 650 650 655

1575 1575 1575 1575 1550 1550 1150 I-150 1150 1150 1450 l-150 l-i50 I-WI

1025 1030

1035 1040 1045 IO50 1060 1070 1080 1090 IO95 (a)

ass-900 845-885 845-885 790-870 790-870 790.870 790-845 790-845 79o-a-is 790-830 790-830

Furnacecooling at 28 “C/h (SO”F/h)

To

Eardness range, FIB Ill-149 Ill-149 Ill-14cf Ill-187 126-197 137-207 137-207 156-217 156-217 156-217 167-229 167-229 167-229 167-229

32 / Heat Treater’s Guide Recommended Annealing Temperatures for Alloy Steels (Furnace Cooling) AISI/SAE Steel 1330 1339 13-m I345 31-m 4037 -Ku2 40.47 4063 1130 -II35 4137 -1140 314S 1147 1150 1161 3337 -t34O SOB40

SOB-U SO46 SOB-t.6 SOB60 5130 Sl32 513s 51-m 5145 Sl47 5150 515s 5160 SIB60 so100 51100 VI00 6150 81815 8627 X630 8637 8640 8643 86-E 86B4S x61650 86SS 8660 8740 874' 9360 94B30 94B10 9840

Supercritical

Annealing temperature T OF &Is-900 849-900 84S-900 81.5-900 815.870 8 I S-855 815.8SS 790.845 790-815 790-815 790-849 790-815 790-a-15 790-845 790-845 790-845 79c-8-n 790.845 790-845 815-870 815-870 8 I S-870 8 I S-870 815-870 8 I S-870 790-815 790-845 815-870 815-870 8 I S-870 815-870 X15-870 815-870 8 I S-870 81%870 730-790 730-790 730-790 845900 845-900 815-870 790-845 8 I S-870 8 I S-870 8 I S-870 815-870 815-870 815870 815-870 815870 t-415-870 8 I S-870 815.870 790-x15 790-84.5 790-845

ISSO- I650 ISSO-1650 ISSO-I650 ISSO-I650 I SOO- I600 1500-1575 1500-157.5 I -Iso- I 550 I GO- I sso I4SO- ISSO 1450-1550 I -so- I SSO l-150- ISSO 1450-1550 14.50-1550 l-150. ISSO l1SO- ISSO l-150- ISSO I-m- I SSO 1500-1600 1500-1600 1500-1600 1500-1600 ISOO-I600 ISO@ I-ISO- ISSO 1450-1550 ISOO-I600 ISO@ ISO@ 1500-1600 1500-1600 1500-1600 1500-1600 1500-1600 I3SO- I450 I3SO- I -is0 1350. IJSO 1550-1650 I SSO- I650 1500-1600 l1SO- I sso 1500-1600 1500-1600 1500-1600 1500-1600 ISOO-I600 ISCO-1600 1.500.1600 1500-1600 1500-1600 1500-1600 lSOWl600 11.50-1550 I-150- IS50 I -Iso- I sso

Spheroidized microstructure of 1040 steel after 21 h at 700°C (1290 oF). 4% picral etch. 1000x

HWdlll?SS

@au), RB 179 I87 I92 I87 I83 I92 201 233 I74 192 197 '07 212

223 I87 197 I92 I92 201 217 I70 170 17-I I87 I97 197 201 717 2'3 223 I97 197 207 201 I92 I74 179 I92 197 201 207 207 212 "3 --. '29 203 229 I74 192 207

or Full Annealing

Full annealing, a common practice, is obtained by heating hypoeutectoid steels above the uppercritical temperacure, Aj. Ln treating these steels (they are less than 0.77% in carbon content). full annealing takes place in the austenite region at the annealing temperature. However. in hypereutectoid steels (they are above 0.77%, in carbon content), annealing takes place above the At temperacure. which is the dual phase austenite region. In an

adjoining Figure. the annealing superimposed on an iron-carbon,

temperature range for full annealing is binary phase diagram. Austenitizing Time and Dead Soft Steel. Hypereutectoid steels can be made extremely soft by holding for long periods at austenitizing temperatures: there is little effect on hardness, i.e., at a change from 241 to X9 HB, the effect on machining or cold forming properties may be substantial.

Annealing

Temperatures

In specifying many annealing operations, it isn’t necessary to go beyond stating that the steel should be cooled in the furnace from a designated austenitizing temperature. Temperatures and associated hardnesses for simple annealing of carbon steels are given in an adjoining Table: requirements for alloy steels are in another Table. Heating cycles in the upper austenitizing temperature ranges shown in the Table for alloy steels should result in pearlitic structures. At lower temperarures. structllres should be predominately spheroidized. Most steels can be annealed by heating to the austenitizing temperature then cooling in the furnace at a controlled rate, or cooling rapidly to, and holding at, a lower temperature for isothemutl transformation. With either procedure, hardnesses are vir~ally the same. However, isothermal transformation takes considerably less time.

Spheroidizing This treatment is usually chosen to improve cold formability. Other applications include improving the machinability of hypereutectoid steels and tool steels. This miCroStruCture is used in cold forming because it lowers the flow stress of the materials. Flow stress is determined by the proportion and distribution of ferrite and carbides. Ferrite strength depends on its grain size and rate of cooling. The formability of steel is signiticantly affected by whether carbides are in the lamellae or spheroid condition. Steels may be heated and cooled to produce globular carbides in a ferritic matrix. An adjoining Figure shows IO-IO steel in the fully spheroidized condition. Spheroidization can take place by using the FoUowing methods: l Prolonged holding at a temperature just belo- the Act l Heating and cooling alternately between temperatures that are just above Act and just below Art l Heating to a temperature just above Act, and then either cooling very slowly in the furnace. or holding at a temperature just above Art l Cooling at a suitable rate from the minimum temperature at which all carbide is dissolved to prevent the reformation of carbide networks, then reheating in accordance with the fist or second methods described

Guidelines for the Heat Treatment of Steel / 33

The iron-carbon binary phase diagram showing region of temperatures for spheroidizing

Effect of prior microstructure [as-quenched).

on spheroidizing

(b) Starting from a ferrite-pearlite

(Fief 4)

a 1040 steel at 700 “C (1290 OF) for 21 h. (a) Starting from a martensitic microstructure microstructure

(fully annealed).

Etched in 4% picral plus 2% nital. 1000x

34 / Heat Treater’s Guide previously work)

The extent of spheroidization at 700 “C (1290 OF)for 200 h for the 1040 steel starting from a ferrite-pearlite microstructure etched in 4% picral. 1000x

(applicable

to hypereutectoid

steel containing

a carbide net-

The range of temperatures for spheroidizing hypoeutectoid and hypereutectoid steels is shown in an adjoining Figure. Rates of spheroidizing depend somewhat on prior microstructures, and are the greatest for quenched structures in which the carbide phase is fine and dispersed (see Figures). Prior cold work also increases the rate of the spheroidizing reaction in a subcritical spheroidizing treatment. For full spheroidization, temperatures either slightly above Act or about midway between Act and ACJ are used. Low-carbon steels are seldom spheroidized for machining because in this condition they are excessively soft and gummy, and produce long, tough chips in cutting. Generally, spheroidized low-carbon steel can be severely deformed. Hardness after spheroidization depends on carbon and alloy content. Increasing carbon or alloy content, or both, results in an increase in as-spheroidized hardness, which generally ranges from I63 to 212 HB (see adjoining Table).

Process

Annealing

As a steel’s hardness goes up during cold working, ductility drops and further cold reduction becomes so difficult that the material must be annealed to restore its ductility. The practice is referred to as in-process

Recommended Temperatures and Time Cycles for Annealing of Alloy Steels Conventional

Steel

temperature OF T

To obtain a predominantly I340 a30 2340 800 2345 800 312qd) 88s 31-m a30 3150 a30 33low a70 4042 a30 w7 a30 4062 a30 4130 ass 4l4O 83s 41.50 a30 432qd) a85 a30 4340 4620(d) 885 4640 a30 3820(d) 5045 a30 Sl2qd) 88s 5132 a45 SIUI a30 5150 a3o S2loom 6150 a30 a62qd) 88s a630 a45 a640 a30 8650 a30 a660 a30 8720(d) a85 8710 a30 8750 a30 9260 860 93 IO(e) a70 98-m a30 9aso a30

cooliog(a)

Ikmperahu-e

Austenitixhg

T From

pearlitic structure(c) IS25 735 1475 655 1475 655 1625 1525 735 IS25 705 I600 74s 1515 I525 735 IS25 695 I575 765 I550 755 IS25 745 1625 1525 705 1625 1525 715

OF

Cooling rate OClh OFlh

Tie, h

To

From

To

610 555 550

I350 1210 I210

II30 1030 1020

IO as as

20 I5 IS

II I2 12.7

650 64s

1350 I300

I200 ll9o

IO IO

20 20

7.5 5.5

640 630 630 665 665 670

1370 I350 1280 1310 I390 1370

ii80 II70 1170 1230 1230 I240

IO IO a.5 20 I5 a.5

20 20 I5 3s 25 IS

9.5 9 7.3 5 6.4 8.6

565

13cil

1050

a.5

IS

16.5

600

I320

Ill0

7.6

1-I

IS

IS25 I635 I550 IS25 152s

755

66s

I390

I230

IO

20

a

755 7-m 705

670 670 650

I390 I360 I300

l2Ul 1240 I200

IO IO IO

20 10 20

7.5 6 5

I525 16’5 I550 IS’5 IS25 1525 I625 I525 1525 IS75 16cQ IS25 I525

760

675

I-NO

I250

as

I5

735 725 710 700

6-m 640 650 655

I350 l34o 1310 I290

ii80 ii80 1200 I210

IO IO a.5 a.5

20 20 IS IS

as a 7.2 a

725 720 760

645 630 705

13-w 1330 I-too

II9o II70 I300

IO a.5 a.5

20 I5 IS

7.5 10.7 6.7

695 700

640 645

I 280 1290

ilao II9O

a.5 a.5

IS I5

6.6 6.7

IO

Isothermal method(b) Cool to OF Eold,h T

Elardness (PpProX), EJ3

620 595 595 650 660 660 595 660 660 660 675 675 675 660 650 650 620 605 660 690 675 675 675

II50 Iloo Iloo 1200 I225 I225 Iloo I225 1225 I225 1250 I250 1250 1225 IXO 1200 II50 II25 I225 I275 I250 1250 I250

4.5 6 6 4 6 6 I4 4.5 5 6 4 5 6 6 a 6 a 4 4.5 4 6 6 6

la3 201 201 179 la7 201 la7 197 207 223 174 197 212 197 223 la7 197 I92 I92 179 la3 la7 201

675 660 660 660 650 650 660 660 660 660 595 650 650

1250 1225 1225 I225 I200 1200 1225 I225 I235 1225 llccl IZOO I200

6 4 6 6 a a 4 7 7 6 I4 6 a

201 la7 I92 197 212 229 la7 201 217 229 ia7 207 223

Guidelines for the Heat Treatment of Steel / 35 Recommended Temperatures and Time Cycles for Annealing of Alloy Steels (continued) Attstenitizii

Steel

temperature T OF

T From

Conventional cooling(a) Temperature OF Cooling rate To To From “CP Wl

Tie, h

Isothermal method(b) Cool to T OF Hold, h

Eardness (apF)v

To obtaio a predominantly ferritic and spheroidized carbide structure 1320(d) 1340 23-U) 2345 3 120(d) 3140 3150 9840 9850

805 750 715 71s 790 745 750 745 745

1180 1380 I320 1320 1450 1370 1380 1370 I370

.. 735 655 655

.‘. 610 555 550

... 1350 1’10 I210

1130 “’ 1030 IO20

5 5 5

IO IO IO

22“’ 18 I9

735 705 695 700

650 64s 640 64s

1350 1300 I280 I290

I200 ... I190 I I80 II90

5 5 5 5

IO IO IO IO

ii II II II

650 640 605 605 650 660 660 6SO 650

I200 II80 II25 II25 1200 1225 1225 I200 I200

8 8 IO IO 8 IO IO IO I2

170 174 I92 I92 163 I74 I87 I92 207

(a) The steel is cooled in the furnace at the indicated rate through the temperature range shown. (b) The steel is cooled rapidly to the temperature indicated and is held at that temperature for the time specified. (c) ln isothermal annealing to obtain pearlitic StrucNre. steels may be austenitized at temperaNreS up to 70 “C ( I25 “F) higher than temperatures listed. (d) Seldom annealed. !hIKNreS of better machinability are developed by normalizing or by transforming isothermally after rolling or forging. (e) Annealing is imptactical by the conventional process of continuous slo\c cooling. The louer transformation temperature IS markedly depressed, and excessively long cooling cycles ate required to obtain are seldom desired in this steel. transformation to pearlite. (I) Predominantly pearlitic struc~res

The iron-carbon binary phase diagram showing region of temperature for process annealing (Ref 4)

36 / Heat Treater’s Guide annealing or simply process annealing. ln most cases, a SubcriIical treatment is adequate and the least costly procedure. The term process annealing, without further qualification. refers to the subcritical treatment. The range of temperatures normally used are shown in an adjoining Figure. It is often necessary to call for process annealing when parts are cold formed by stamping, heading, or extrusion. Hot worked, high-carbon and alloy steels are also process annealed to prevent them from cracking and to soften them for shearing, turning. and straightening. The process usualI> consists of heating to a temperature below AC,. soaking for an appropriate time. then cooling-usually in air. Generally, heating to a temperature between IO and 22 “C (20 and 10 “F) below AC] produces the best combination of microstructure, hardness, and mechanical properties. Temperature controls are necessary only to prevent heating above Act. which would defeat the purpose of annealing. When Ihe sole purpose is to soften for such operations as cold sawing and cold shearing, temperatures are usually well below Act. and close control isn’t necessary.

Annealed

Structures

for Machining

Different combinations of microstructure and hardness are important for machining. Optimum microstructures for machining steels with different carbon contents are usually as follows: Carbon, W 0.c60.20 0.20-0.30

0.30-0.40 0.00-0.60 [email protected]

Optimum microslructure As-rolled (,mosteconomical) Under75 mm (3 in.)diameter,normaliz.ed: 75 mm diameterando\er. as-rolled Annealed to produce coarse pearlite. minimum ferrite Coarse Iamellar pearlite to coarse spheroidized carbides 100%.spheroidizrd carbides. coarse to fine

qpe of machining operation must also be taken into consideration, i.e., in machining 5160 steel tubing in a dual operation (automatic screw machines. plus broaching of cross slots), screw machine operations were the easiest with thoroughly spheroidized material. H hilt a pearlite smcture was more suitable for broaching. A senispheroidized structure proved to be a satisfactory compromise-a structure that can be obtained by austenitizing at lower temperatures, and sometimes at higher cooling rates, than those used to get pearlitic structures. In the last example, the 5 160 tubing was heated to 790 “C ( I455 “F) and cooled to 650 “C ( I200 “F), at 28 “C (50 “F) per h. When this grade of steel is austenitized at about 775 “C (I125 “F), results are more spheroidization and less pearlite. Medium-carbon steels are harder to carburize than high-carbon steels, such as IO95 and 52 100. In the absence of excess carbides to nucleate and

Surface

Hardening

promote the spheroidization reaction, it is more difficult to get complete freedom from pearlite in practical heat-treating operations. At lower carbon levels, structures consisting of coarse pearlite in a ferrite matrix are the most machinable. With some alloy steels, the best way of getting this type of structure is to heat well above Ac3 to establish coarse austenite gram size, then holding below Art to allow coarse, lamellar pearlite to form. The process is sometimes referred to as cycle annealing or lamellar annealing.

Annealing

Annealing

Significant tonnages of these products are subjected to treatments that lower hardness and prepare the steels for subsequent cold working and/or machining. Short time, subcritical annealing is often enough to prepare low-carbon steels (up to 0.204; C) for cold working. Steels higher in carbon and alloy content require spheroidization to get maximum ductility.

Annealing

of Plate

These products are occasionally annealed to facilitate forming or machining operations. Plate is usually annealed at subcritical temperatures, and long annealing times are generally avoided. Maintaining flatness of large plate can be a significant problem.

Annealing

of Tubular

Products

Mechanical tubing is frequently machined or formed. Annealing is a common treatment. In most instances, subcritical temperatures and short annealing times are used to lower hardness. High-carbon grades such as 52100 generally are spheroidized prior to machining. Tubular products made in pipe mills rarely are annealed. and are used in the as-rolled, the normalized, or quenched and tempered conditions.

References B.R. Banerjee, Annealing

Heat Treatments,

Met. frog..

Nov 1980, p 59

Atlas of Isorhent~al Transfomtariot~ and Cooling Transformation Diagratns. American Society for Metals, 1977 hl. Atkins, Ailas for Cotlriturous Cooling Transfomtarion Diagramsfor Engineering Steels, American Society for Metals, in cooperation with British Steel Corporation.

G. Krauss, Sleek: International.

processes

l l l

Induction hardening l Flame hardening l Gas carbutizing l Pack carbutizing l Liquid carburizing and cyaniding l Vacuum carburizing l Plasma (ion) carburizing . Carbonitriding

Bar, Rod, Wire

1980

Hear Treammenr and Processing Principles, ASM

1989

Treatments

In the articles that follow, overvie\% s of I6 surface hardening are presented. They include. in the order that follows: l

of Forgings

Forgings are most often annealed to facilitate subsequent operationsusually machining or cold forming. The method of annealing is determined by the kind and amount of machining or cold fomting to be done, as well as type of material being processed.

l l l l l

Gas nitriding Liquid nitriding Plasma (ion) nitriding Gaseous and plasma nitrocarburizinp Fluidized bed hardening Boriding Laser surface hardening Electron beam surface hardening For more detailed

information

and hundreds of references, see the ASM IO ed., ASM International, 1991.

Metals Handbook. Hear Treating. Vol1.

Guidelines

Induction

h4any problems associated with furnace processes are avoided. Rate of heating is limited only by the power rating of the alternating current supply. Surface problems such as scaling and decarburization and the need for protective atmospheres often can be bypassed because heating is so fast. Heating is also energy efficient-as high as 80 percent. In gas fued furnaces. by comparison, a fairly substantial amount of consumed energy in hot gases is lost as they exit the furnace. HoNever, the process seldom competes with gas or oil-based processes in terms of energy costs alone. SaGngs emanate from other sources:

Characteristics In designing treabnents, consideration must be given to the workpiece materials, their starting condition, the effect of rapid heating on the ACT or Accm temperatures, property requirements, and equipment used.

and Production

Material

Rounds 13 19 ‘5 29 49

4130 IO35 mod IMI 1041 13B3SH

‘/z

Flats 16 I9 22 25 29

5/g 34 ‘4% I I ‘/8

lrregularshapes 17.5-33 “/16-15/lb 17.529 ‘Vlh-lt/~

Data for Progressive FIX?quencyb), Ez

Section size mm in.

% I I ‘/8 I ‘V,6

of Steel / 37

Hardening

Steels are surface hardened and through-hardened, tempered, and stress relieved by using electromagnetic induction as a source of heat. Heating times are unusually rapid-typically a matter of seconds, Ref I.

Operating

for the Heat Treatment

1038 1038 1043 1043 lo-13 t037mod t037mod

9600 9600 9600 180

Induction

Tempering

Power(a), kW

Total heating time,s

II 12.7 18.7 20.6 23

17 30.6 d-I.2 51 196

0.39 0.71 I .01 1.18 2.76

I 1.8 2.6 3.0 7.0

SO SO so SO 50

120 I20 I20 I20 I20

56s 510 565 565 56.5

1050 9.50 IOSO 1050 IOSO

I23 I64 312 25-l 328

0.59 0.79 I so 1.22 I .57

I.5 2.0 3.8 3I 1.0

40 40 -lo 10 40

loo 100 100 loo loo

‘90 31s 290 290 290

550 600 950 550 550

0.9-l 0.67

2.1 I.7

65 65

IS0 IS0

550 125

IO70 800

60 60 60 60 60

88 too 98 85 90

9600 9600

I92 IS-I

64.8 46

Sean time s/cm sjm.

Work temperature Leabing coil Entering coil OF T T OF

Production rate ki# lblb

Inductor illput kW/cmz kWlm.2

0.064 0.050

92 II3 I11 IS3 I95

202 ‘SO 311 338 429

0.054 0.053 0.031

0.4 I 0.32 0.35 0.34 0.20

I449 1576 1609 1365 1483

319-t 3171 3548 3009 3269

0.01-l 0.013 0.008 0.01 I 0.009

0.089 0.08 I 0.0.50 0.068 0.060

2211 3875 2276 5019

0.043 0.040

0.28 0.26

(a) Power tmnsmitted by the inductor at the operating frequency indicated. For con! erted frequencies. this po\\er is approximately ?S@kless than the power input to the machine, because of losses within the machine. (b) At the operating frequency of the inductor

Examples

of quench

rings for continuous

hardening

and quenching

of tubular

members.

Courtesy

of Ajax Magnethermic

Corp.

38 / Heat Treater’s

Guide

Power Densities

Required

Frequency, KEZ

Depth of hardening(a) in. mm

500

for Surface

0.381-1.143 1.143-2.286 1.524-2.286 2.286-3.048 3.0483.064 2.286-3.048 3.048-4.064 4.064-5.080 5.080-7. I I2 7.112-8.890

IO

3

I

Hardening

Of Steel ~PMJ)W Optimum(e) kW/cmz kWrm.2

Low(d) kW/cmz

kW[m.’

I .08 0.46 I .24 0.78 0.78 I s5 0.78 0.78 0.78 0.78

7 3 8 5 5 IO 5 5 5 5

0.015-0.045 0.045-0.090 0.060-0.090 0.090-0. I20 O.I20-0.160 0.090-0. I20 0.120-O. I60 0.160-0.200 0.200-0.280 0.280-0.350

I.55 0.78 I .ss I ss I .55 2.33 2.17 I .55 I .55 I.55

em kW/cm

10 5 IO IO IO I5 I4 10 IO IO

kWtin.2 I2 8 I6 I5 I4 I7 I6 I4 I2 I2

I.86 I .24 2.48 2.33 2.17 2.64 2.48 2.17 1.86 I.86

(a) For greater depths of hardening, lower kilowatt inputs are used. (b) These values are based on use of proper frequency and normal overall operating efficiency of equipment. These values may be used for both static and progressive methods of heating; however, for some apptications. higher inputs can be used for progressive hardening. (c) Kilowattage is read as maximum during heat cycle. (d) Low kilowatt input may be used when generator capacity is limited. These kilowatt values may be used to catculate largest part hardened (single-shot method) with a given generator. (e) For best metatturgical results. (f) For higher production when generator capacity is available

Approximate Operations

Power Densities

Required

for Through-Heating

of Steel for Hardening,

Tempering,

or Forming

Input(b) 150-425T (30Mtoo°F) kW/cm’ kWrm.2

~uency(a), 62 60 I80 1009 3000 10000

0.009 0.008 0.006 0.00s 0.003

421760 T (soo-1400°F) kW/cmz kWlin.2

0.06 0.05 0.04 0.03 0.02

0.023 0.022 0.019 0.016 0.012

76M80 T (1400-BOOoF) kW/cmz kwp.*

0.15 0.14 0.12 0.10 0.08

(c) w 0.08 0.06 0.05

980-lo!zOc (1&300-2ooooF) k W/cm2 kW/in.” Cc) (c) 0.155 0.085 0.070

0.5 0.4 0.3

1095-l205oc (2tmo-2200 OF) kW/ii2 kW/cml w w 0.22 0.11 0.085

I .o 0.55 OX?

(c) w 1.4 0.7 0.55

(a) The values in this table are based on use of proper frequency and normal overall operating efficiency ofequipment. (b) In general, these power densities are for section sizes of I3 to SOmm ( ‘/? to 2 in.). Higher inputs can be used for smaller section sizes, and lower inputs may be required for larger section sizes. (c) Not recommended for these temperatures

Typical

Operating

section size mm in. Rounds I3

‘/z

Conditions

for Progressive

Through-Hardening

of Steel Parts by Induction

Material

Frequency(a), El2

Power(b), kW

Total beating time,s

4130

I80

20 21 28.5 20.6 33 19.5 36 19.1 35 32

38 I7 68.4 28.8 98.8 44.2 II4 fit 260 II9

0.39 0.39 0.7 I 0.71 I .02 1.02 I.18 I.18 2.76 2.76

I I8 I.8 2.6 2.6 3.0 3.0 7.0 7.0

75 sto 75 620 70 620 75 620 75 635

I65 950 I65 II50 I60 II50 I65 II50 I65 II75

510 925 620 955 6’0 955 630 95s 635 95.5

950 1700 IISO I750 II50 1750 IISO I750 II75 1750

92 92 II3 II3 I41 I31 IS3 I53 19.5 I95

202 202 250 250 311 311 338 338 429 429

0.067 0.122 0.062 0.085 0.054 0.057 0.053 0.050 0.029 0.048

0.43 0.79 0.40 0.55 0.35 0.37 0.34 0.32 0.19 0.31

I80 9600 I80 9600 I80 9600 I80 9600

scao time s/cm Sri.

I

Work temperature Entering coil Leaving coil ‘=C OF T “F

Production rate lblh k%h

Inductor input(c) kW/cml kW/in.l

I9

34

1035 mod

25

I

1041

29

I ‘/*

IO41

19

I ‘V, 6

I4B3SH

% 3/a ‘4 I I ‘/8

1038 1038 1043 IO36 1036

3000 3000 3000 3000 3000

300 332 336 30-I 34-l

II.3 I5 38.5 26.3 36.0

0.59 0.79 I so I .38 I.89

I.5 2.0 3.8 3.5 4.8

20 ‘0 20 20 ‘0

70 70 70 70 70

870 870 870 870 870

1600 1600 1600 1600 1600

1449 1576 1609 IS95 I678

3193 347-l 3548 3517 3701

0.361 0.319 0.206 0.225 0.208

2.33 2.06 I .33 I .45 I.34

t037mod

3ooo

580

25-t

0.94

2.4

20

70

885

1625

2211

4875

0.040

0.26

Flats I6 I9 22 25 ‘9

Irregular shapes 17.5-33 t’/te-15/ts

(a) Note use of dual frequencies for round sections. (b) Power transmitted by the inductor at the operating frequency indicated. This poaer is approximately 25% less than the power input to the machine, because of losses within the machine. (c) At the operating frequency of the inductor

Guidelines

Eleven basic arrangements for quenching induction-hardened

shortened processing times, reduced labor, and the ability to heat treat in a production line or in automated systems, for example. Surface hardening and selective hardening can be energy competitive because only a small part of the metal is heated. [n addition, with induction heating it often is possible to substitute a plain carbon steel for a more expensive alloy steel. Short heating times make it possible to use higher austenitizing temperatures than those in conventional heat-treating practice. Less distortion is another consideration. This advantage is due to the support given by the rigid, unheated core metal and uniform, individual handling during heating and quenching cycles.

Operating

Information

Power densities for surface hardening are given in an adjoining Table. Approximate power densities needed for through-heating of steel for hardening and tempering are given in an adjoining Table. Typical operating conditions for progressive through-hardening are given in an adjoining Table.

for the Heat Treatment

of Steel / 39

parts. See text for details.

Operating and production data for progressike induction tempering are given in an adjoining Table. Frequency and power selection influence case depth. A shallow, fully hardened case ranging in depth from 0.25 mm to I .5 mm (0.010 to 0.060 in.) provides good resistance to wear for light to moderately loaded parts. At this level, depth of austenitizing can be controlled by using frequencies on theprder of IO KHz,to 2 MHz, power densities to the coil of 800 to 8000 W/cm’ (5 to 50 kW/i.-) and heating times of not more than a few seconds.

For parts subjected to heavy loads, especially cyclic bending, torsion, or brinneling. case depths must be thicker. i.e.. 1.5 IO 6.4 mm (0.060 to 0.250 in.j. To get this result. frequencies range from 10 KHz down to I KHz; power densities are on the order of 80 to 1550 W/cm2 (l/2 to IO kW/in.2). and heating times are several seconds. Selective hardening is possible, as is in volume surfacing hardening, in which parts are austenitized and quenched to greater than usual depths. Depth of hardness up to 25 mm (I in.) measuring over 600 HB has been obtained with a I percent carbon. I .3 to I .6 percent chromium steel that has been water quenched. Frequencies range from 60 Hz to 1 KHz. Power

40 / Heat Treater’s

Guide

Power Input for Static Hardening. Slope of graph indicates that 35 to 40 kW-seciin.’ (5 to 6 kW-secicm’) is correct power input for static hardening most steels. Source: Park-Ohio Industries

Straight-line Relationships Between Depth of Hardnessand Rate of Travelfor Surface Hardening by Induction of long Bars Progressively. Source: Park-Oh10 lndustrles

Effect of Varying Power Density on Progressive Hardening. Power density at 10 000 cycles. Case, 0.100 in. (2.54 mm) deep. Park-Ohio Industries

Source:

Guidelines

for the Heat Treatment

of Steel / 41

Minimum Power Density VersusStock Diameter for Static Hardening and VersusRate of Travel for Progressive Hardening. Source: Park-Oh10 Industries

Influence of Prior Structure on Power Requirements for Surface Hardening. Prior structure consists of fine microconstituents.

Source: Park-Ohio Industries

42 / Heat Treater’s

Guide

Effect of Varying Power Density on Progressive Hardening. Power density at 500 000 cycles. Case, 0.050 In. (1.27 mm) deep. Source: Park-Ohio Industries

densities are expressed in a fraction of kW/in.‘. Heating times run from about 20 to 140 s. Through-hardening is obtained in the medium frequencies (180 Hz to IO KHz). In some instances, two hequencies may be used, a lower one to preheat the steel to a subcritical temperature, followed by a higher ti-equency to obtain the full austenitizing temperature. Tempering with induction heating is highly efficient. The two most common types of quenching systems are spray quench rings (see Figure) and immersion techniques. Eleven other systems are shown in an adjoining Figure. Water and oil are the most frequently used quenching media. Oil typically is used for high hardenability parts or for those subject to distortion and cracking. Polyvinyl alcohol solutions and compressed air also are commonly used, i.e., the former where parts have borderline hardenability. where oil does not cool fast enough, and where water causes distortion or cracking. Compressed air quenching is used for high hardenability, surface hardened steels from which little heat needs to be removed.

Flame

Applications The process is applied mostly to hardenable grades of steel; some carburizing and slow cooled parts often are reheated in selected areas by induction heating. Typical applications include: l

l

l

Medium-carbon steels, such as 1030 and 1045, for parts such as auto driveshafts and gears High-carbon steels, such as 1070, for parts such as drill and rock bits and hand tools Alloy steels for such parts as bearings, valves, and machine tool parts

Reference I. ASM Metals Handbook. Heat Treating, Vol 4. 10th ed., ASM lntemational.

1991, p 164

Hardening

In this process, a thin surface shell of a steel part is heated rapidly to a temperature above the critical point of the steel. After the structure of the shell becomes austenitic, the part is quenched quickly, transforming the austenite to martensite. The quench must be fast enough to bypass the pearlite and bainite phases. In some applications, self-quenching and selftempering are possible, Ref I. (See articles on other self-quenching processes-electron beam, laser, and high frequency, pulse hardening-elsewhere in this chapter.)

Characteristics Hardening is obtained by direct impingement of a high-temperature flame or by high-velocity combustion product gases. The flame is produced by the combustion of a mixture of fuel gas and oxygen or oil. The mixture is burned in flame heads: depth of hardness ranges from approximately 0.8 to 6.4 mm (0.03 125 to 0.25 in.), depending on the fuels used,

design of the flame head, duration of heating, hardenability of the workpiece, the quenching medium, and quenching method. Flame hardening differs from true case hardening in that hardness is obtained by localized heating. The process generally is selected for wear resistance provided by high levels of hardness. Other available gains include improvements in bending properties, torsional strength, and fatigue life. Comparative benefits of flame hardening, induction hardening, nitriding, carbonitriding. and carburizing are summarized in an adjoining Table.

Operating

Information

Methods of flame hardening include these types: spot (or stationary), progressive, spinning, and combination progressive-spinning. Spot and progressive spinning are depicted in a Figure, spinning methods in a second Figure.

Guidelines

for the Heat Treatment

of Steel / 43

Fuel Gases Used for Flame Hardening usual Beatingvalue Gas Acetylene City gas Natural gas (methane) Propane MAPP

MJ/m’

Bhr/ft’

53.4 1433 I I .2-33.5 300900 37.3 loo0 93.9 90

2520 2406

Ftarne temperature With oxygen With air OF OC OC OF

nltioof oxygen to fuel gas

Beating value of oxy-fuel gas mixture hfJjtn’ Bhr/ftJ

Notmal velocity of buruiug mm/s i0.p

Combustion intensity(a) mm/sx tn./s x I\lJ/m’ Btu/ftJ

USUd ratio of

airI0 fuel gas

3105 2540 2705

5620 4600 4900

2325 1985 1875

4215 3605 3405

I.0 (b) I .75

26.1 (hi 13.6

716 (b) 364

535 (b) 280

II (b) II

I4 284 (b) 3808

15 036 (W 4004

12 W 9.0

2635 2927

477s 5301

192s 1760

3495 3200

4.0 3.5

18.8 20.0

504 53s

30s 381

I2 I5

5 734 7 620

6oJ8 8025

25.0 22

(a) Product of normal velocity of burning multiplied by heating value of oxy-fuel gas mixture. (b) Varies with heating value and composition

Procedure

for Spin Flame Hardening

the Small Converter

Preliminary operation Turn on water, air, oxygen, power, and propane. Line pressures: water, 220 kPa (32 psi); air. 550 kPa (80 psi); oxygen, 825 kPa ( 120 psi); propane. 20.5kPa (30 psi). Ignite pilots. Loading and positioning Mount hub on spindle. Hub is held in position by magnets. Flame head pm\ iously centered in hub within 0.4 mm (‘1~ in.). Distance front flame head to inside diameter of gear teeth, approximately 7.9 mm &te in.) Cycle start Spindle with hub advances over flame head and starts to rotate. Spindle speed. I-10 rpm Beating cycle Propane and oxygen solenoid valves open (oxygen flow delayed slightly). Mixture of propane and oxygen ignited at flame head by pilots. Check propane and oxygen gages for proper pressure. Adjust flame by regulating propane. Heating cycle controlled by timer. Tune ptedetemtined to obtain specified hardening depth

Shallow hardness patterns of less than 3.2 mm (0.125 in.) deep can be obtained only with oxy-gas fuels. When specified hardnesses are deeper, oxy-fuels or air-gas fuels may be used. Time-temperature depth relationships for various fuel gases used in the spot (stationary), spinning, and progressive methods are shown in an adjoining Figure. Burners and Related Equipment. Burners vary in design, depending on whether oxy-fuel or air-fuel gas mixtures are used. Flame temperatures of the air-fuel mixtures are considerably lower than those of oxy-fuel mixtures (see Table). Flame heads for oxy-fuel gas are illustrated in an adjoining Figure, while those for air-fuel gas are shown in a second Figure. Operating Procedures and Control. The success of many applications depends largely on the skill of the operator. Procedures for two applications are summarized in adjoining tables. Preheating. Difficulties in getting the required surface hardness and hardness penetration in treating parts large in cross section often can be overcome by preheating. When available power or heat input is limited, depth of hardness can also be increased by preheating. Results in one application are shown in an adjoining Figure. Quenching Methods and Equipment. Method and type of quenchant vary with the flame hardening method used. hnrnersion quenching generally is the choice in spot hardening, but spray quenching is an alternative. In quenching after progressive heating, the spray used is integrated into the flame head. However, for steels high in hardenability, a separate spray-quench sometimes is used. Parts heated by the spinning method are quenched several ways. In one, for example, the heated part is

Gear Hub Beating cycle (continued) Propane and oxygen solenoid valves close (propane flow delayed slightly). Spindle stops rotating and retracts. Hub stripped from spindle by ejector plate. Machine ready for recycling Propane regulated pressure, I25 kPa ( I8 psi ); oxygen regulated pressure, 550 kPa (80 psi); oxygen upstream pressure, ux) kPa (58 psi); oxygen downstream pressure, I40 kPa (20 psi). flame velocity (ap roximate), I35 m/s (450 ft/s). Gas consum tions (approximate); propane, 0.02 rn.7 (0.6 fts) per piece: oxygen, 0.05 m3 ( I .9 ft ) per piece. Total heating time, 95 s Flame pan design: I2 ports per segment; IO segments; port size, No. 69 (0.74 mm. or 0.0292in.).withNo.56(1.2mm,orO.O46Sin.)counterbore

f

Quench cycle Hubdrops into quench oil, is removed from tank by conveyor. Oil temperatute. S4f 5.6 “C (130-t IO “F); time in oil (approximate), 30s Eardoess and pattern aim Hardness, 52 HRC minimum to a depth of 0.9 mm (0.035 in.) maximum above toot of gear teeth

Relative

Benefits

carburizing

Carbonitriding

Nitriding

induction hardening

Flame hardening

of Five Hardening

Processes

Hard. highly wear-resistant surface (medium case depths); excellent capacity for contact load; good bending fatigue strength; good resistance to seizure; excellent freedom from quench cracking; low-to-medium-cost steels required; high capital investment required Hard, highly wear-resistant surface (shallow case depths): fair capacity for contact load; good bending fatigue strength: good resistance to seizure; good dimensional control possible; excellent freedom Fromquench cracking; low-cost steels usually satisfactory; medium capital investment required Hard. highly we=-resistant surface (shallow case depths); fair capacity for contact load; good bending fatigue strength;excellent resistance toseizure; excellent dimensional control possible; good 6eedom Fromquench cracking (during pretreatment): medium-to-high-cost steels requited; medium capital investment required Hard. highly wear-resistant surface (deepcase depths); good capacity for contact load; good bending fatigue strength; fair resistance to seizure; fair dimensional control possible: fair freedom from quench cracking; low-cost steels usually satisfactory; medium capita) investment required Hard, highly wear-resistant surface (deepcase depths); good capaci3 for contact load; good bending fatigue strength; fair reststance to seizure; fair dimensional control possible; fair freedom from quench c73cking; low-cost steels usually satisfactory; low capital investment requited

44 / Heat Treater’s

Guide

Spot (stationary) and progressive methods of flame hardening. (a) Spot (stationary) internal lobes of a cam; quench not shown. (b) Progressive hardening method

Spinning methods Quench not shown

Response

of flame hardening.

In methods shown at left and at center, the part rotates. In method at right, the flame head rotates.

of Steels and Cast Irons to Flame Hardening

hlaterial Plain carbon steels 1025-1035 I043 IO.50 10.55-1075 1080-1095 11’5-1137 ll38-114-l 114&1151

Qpical hardness, EIRC, as affected by quenchant Air(a) Oil(b) Water(b)

SO-60 55-62

92-58 58-62 S8-62

15-55 SO-55

52-57(C) s5-60

33-50 55-60 60-63 62-65 AS-55 55-62 58-61

58-62 60-63

62-65 62-65

52-57(C) 55-60 58-62 61-63 SO-55 52-56 58-62 53-57 56-60 52-56

S-62 60-6-I 63-65 63-65 55-60 55-60 62-65 60-63 62-6s 60-63

Carburized grades of plain carbon steels(d) SO-60 1010-1020 50-60 1108-1120 Alloy steels 13-u)-1335 3110-3115 3350 4063 4130-413s 4l40-4I-15 11-17~1150 13374340 4347 -I640

method of flame hardening a rocker arm and the

35-55 50-60 55-60

55-60 52-56 M-62 53-57 56-60 52-56

‘l)pical hardness, EIRC, as affected by quenchant Air(a) Water(b) oil(b)

hiaterial Allo] steels (continued) 52100 6150 8630-8640 86x-8660

M-60 48-53 55-63

Carburized 3310 461.54620 86 I S-8620

grades of alloy steels(d) 55-60 58-62

hlsrtensitic -llO.-tl6 -II-l1131 120 UOttvpical) .

stainless steels

55-60 5260 52-57 55-63

62-64 Xi-60 58-62 62-64

58-62 62-65 58-6’

63-65 64-66 62-65

-11-l-I G-47 -t9-56 55-59

41-U 12-47 49-56 55-59

Cast irons (ASThI classes) Class 30 class 40 Class-!5010 s0007.53004.6lmJ3 Class 80002 52-56 class &l-45- IS

43-48 -18-52 3543 52-56 56-59

43-18 38-52 35-45 55-60 X1-61 35-45

ta)Toobtainthe hardnessresultsindicated. thoseareasnotdirectly heatedmust be kept relativelycoolduring the heatingprocess.~b)Thinxctionsaresusceptible~ocracking when quenched with oil or water. (c) Hardness is slightly lo\rer for material heated by spinning orcombination progressive-spinning methods than it is for material heated by progressive or stationary methods, td) Hardness values of carburized cases containing 0.90 IO I. 10% C

Guidelines

Calculated time-temperature-depth ness given in millimeters

relationships

Typical

gas. (a) Radiant type. (b) High-velocity

burners

for use with air-fuel

for spot (stationary),

spinning,

for the Heat Treatment

and progressive

convection

flame hardening.

type (not water cooled)

of Steel

/ 45

Depth of hard-

46 / Heat Treater’s

Guide

Flame heads for use with oxy-fuel gas

Effect of preheating on hardness gradient in a ring gear

Progressive

Flame Hardening

of Ring Gear Teeth

Workpkxe Bevel ring gear made of 87-12 steel with 90 teeth. Diametral mm (8 in.); outside diameter, I.53 m (60.112 in.)

pitch, 1.5; face width. 200

hlouoting Gear mounted on holding fixture to within 0.25 mm (0.010 in.) total indicator runout Flame beads ILvo IO hole. double-row. air-cooled flame heads. one on each side of tooth. Flame heads set 3.2 mm (‘/s in.) 6om tooth Operating

removed tank.

from the heating area and quenched

by immersion

conditions

Go.sp~ssurps. Acetylene, 69 kPa ( IO psi); oxygen. 97 kPa ( I4 psi) Speed. I .9 mm/s (4.5 in./min). Complete qcle (hardening pass, overtravel at each end, index rime. preheat return stroke on next tooth), 2.75 min hdering. Index every other tooth. index four times before immening in coolant. Coolanr. Mixture of soluble oil and hater. at I3 “C (55 “Fj Hardnessaim. 53 to 55 HRC

in a separate

Quenching Media. Water, dilute polymer solutions, and brine solutions are used. Oils are not: they should not be allowed to come into contact with oxygen, or to contaminate equipment. In many types of flame hardening (excluding through hardening) selfquenching speeds up cooling. The mass of cold metal underneath the heated layer withdraws heat, so cooling rates are high compared with those in conventional quenching. During progressive hardening of gear teeth made of medium-carbon steels, such as 4140, 4150. 4340, and 4610, for instance, the combination of rapid heating and the temperature gradient between the surface and interior of a gear results in a selfquench. Results are similar to those obtained with oil. Tempering. Flame hardened parts usually are tempered, with parts responding as they do when they are hardened by other methods. Standard procedures, equipment, and temperatures may be used. If parts are too large to be treated in a furnace. they can be Hame tempered. Also, large parts hardened to depths of about 6.4 mm (0.25 in.) can be self-tempered by

residual heat in the part: hardening stresses are relieved separate operation may not be necessary.

and tempering

in a

Applications flame hardened plain carbon steels, carburized grades of plain carbon steels, alloy steels, martensitic stainless steels, and cast irons that are flame hardened are listed in an adjoining Table.

Reference I. ASM Merals Handbook tional, 1991, p 368

Hear Treating, Vol 4. 10th ed., ASM lntema-

Gas Carburizing In this process, carbon temperatures required to carbon steels. Austenite quenching and tempering,

is dissolved in the surface layers of parts at the produced an austenitic microstructure in lowis subsequently converted to martensite by Ref I.

Characteristics This is the most important carburizing process commercially. The gradient in carbon content below the surface of a part produced in the process causes a gradient in hardness; resulting surface layers are strong and resistant to wear. The source ofcarbon is a carbon-rich furnace atmosphere,

including gaseous hydrocarbons, such as methane, propane, and butane, or vaporized hydrocarbon liquids. Lou-carbon steels exposed to these atmospheres carburize at temperatures of 850 “C (I 560 “F) and above.

Operating

Information

In present practice, for two reasons: l

carbon content in furnace atmospheres

To hold tinal carbon concentration solubility limit in austenite

is controlled

at the surface of parts below

the

Guidelines

Plot of total case depth versus

l

To minimize

carburizing

time at four selected

071 ‘C IMOO ‘FI

.899T116M’F1

l

927 ‘C 11700 ‘FI

in.

mm

in.

“Ill

in.

mm

in.

I , ;

0.46 0.64 0.89

0.018 0.035 0.03

0.53 0.76 1.07

0.02 I 0.0-P 0.030

0.6-I 0.89 I.27

O.OY 0 050 0.035

0.‘4 I.04 I.30

0.029 0.051 I 0.04

8 I? I6 .?4 30

I.27 I.55 1.80 2.18 2.46

0.050 0.061 0.071 0.086 0.097

I.52 18.5 2.13 2.62 2.95

0.060 0.073 oon4 0.103 0.116

I.80 2.21 ?..(-I 3.10 3 -In

0.07 I 0.087 0.100 0.1’2 O.li?

2.11 2 59 2.9: 3.M 4.09

0.083 O.lO! 0.117

Residual stresses put into parts prior to heat treating Shape changes caused by heating too rapidly

/ 47

951 ‘C 11750 “FI

mm

sooting of the furnace atmosphere

of Steel

Graph based on data in table

Time. h

Endothermic gas, the usual carrier, plays a dual role: it acts as a diluent and accelerates the carbutizing reaction at the surface of parts. Parts, trays, and fixtures should be thoroughly cleaned before they are charged into the furnace-often in hot alkaline solutions. In some shops, these furnace components are heated to 400 “C (750 “F) before carburizing to remove traces of organic contaminants. Key process variahles are temperature, time, and composition of the atmosphere. Other variables are degree of atmosphere circulation and the alloy content of parts. Temperature. The rate of diffusion of carbon in austenite determines the maximum rate at which carbon can be added to steel. The rate increases significantly with increasing temperature. The rate of carbon addition at 925 “C (1695 “F) is about 40 percent higher than it is at 870 “C (1600 “F). At this temperature, the carburizing rate is reasonahly rapid and the deterioration of furnace components, especially alloy trays and futtures, is not excessive. When deep cases are specified, temperatures as high as 966 “C (1770 “F) sometimes are used to shorten carburizing times. For consistent results, temperatures must be uniform throughout the workload. The desired result can be obtained, for example, with continuous furnaces with separate preheat chambers. Time. The combined effect of time and temperature on total case depth is shown in an adjoining Figure. The relationship of carburizing tune and increasing carburizing temperature is shown in a second Figure. Dimensional Control. To keep heat-treating times as short as possible, parts should be as close to final dimensions as possible. A number of other factors also have an influence on distortion, including: l

temperatures.

for the Heat Treatment

0.I.t.l 0 Ihl

Reducing effect of increased process temperature on carburizing time for 8620 steel. Case depth: 1.5 mm (0.060 in.)

Properties

of Air-Combustible

Gas Mixtures

Autoignition temperahwe

Flammable limits in

Gas

OC

OF

Methane Propane Hydrogen Carbon mono.tiurde Methaool

S-IO 466 -mo

100s

5.1IS

870 750 1130 72s

2.19,s 4.0-7s 12.5-74 6.7-36

609 385

air, vol %

48 / Heat Treater’s

Guide

Plot of stress relief versus tempering temperatures held for 1 h for two carbon concentrations in austenite

A high-productivity

l

l

The manner in which quenching Severity of quenching

A pit batch carburizing furnace. Dashed lines outline location of workload.

gas-fired integral quench furnace

parts are stacked or fixturcd

in carburizing

and

Quenchants include brine or caustic solutions, aqueous polymers, oils, and molten salt. In some industries, parts are carburized at 917 “C (I 700 “F) or above, cooled slowly to ambient temperature. then reheated at 843 “C (I 550 “F), then quenched. Benefits include refinement in microstructure and limiting the amount of retained austenite in the case.

Tempering. Density changes during tempering affect the relief of residual stresses produced in carburizing. An adjoining Figure shows the effect of tempering for I h at various temperatures on stress relief. Stress relief occurs at lower tempering temperatures as the amount of carbon dissolved in austenite is increased. Selective Carburizing. Some gears, for example, are carburized only on teeth, splines, and bearing surfaces. Stopoffs include copper plating and ceramic coatings. Safety Precautions. The atmospheres used are highly toxic and highly inflammable. When combined with air, explosive gas mixtures are

Guidelines

Relation Between Dew Point and Moisture Content of Gases. Hydrogen can be purified by a room-temperature catalytic reaction that combines oxygen with hydrogen, forming water. Then, all water vapor is removed by drying to a dew point of -60 “F (-51 “C).

Composition Steel

of Carburizing C

Mn

for the Heat Treatment

of Steel / 49

Iron Oxides from CO, or H,O. Data point 1: an atmosphere consisting of 75 H, and 25 H,O will reduce scale on iron (Fe0 or Fe,O,) at 1400 “F (760 “C). Data point 2: same atmosphere will scale metal at 900 “F (480 “C)

Steels Composition, Q Ni Cr

MO

Other

Carbon steels 1010 1019 1018

0.08-0.13 0.30-0.60 0.15-0.20 0.70-1.00 0.60-0.90

. ...

.. . .

.. .. .

i”? IZ $ ;;;

1020 1021

0.18-0.23

0.30-0.60 0.60-0.90

..

. ..

. ..

$1: y;

1022 1524 1527

0.18-0.23 0.19-0.25 0.22-0.29

0.70-1.00 1.35-1.65 1.20-1.50

... .

... ..

. ..

(:I: (b) (4, (b)

Resulfurized steels 1117 0.14-0.20

1.00-1.30

..

.. .

..

0.08-O. 13 S

Alloy steels 3310 0.08-0.13 4023 0.20-0.25 4027 0.25-0.30 4118 0.18-0.23 4320 0.17-0.22 4620 0.17-0.22 4815 0.13-0.18 4820 0.18-0.23 5120 0.17-0.22 5130 0.28-0.33 8617 0.15-0.20 8620 0.18-0.23 8720 0.18-0.23 8822 0.20-0.25 9310 0.08-0.13

0.45-0.60 0.70-0.90 0.70-0.90 0.70-0.90 0.45-0.65 0.45-0.65 0.40-0.60 0.50-0.70 0.70-0.90 0.70-0.90 0.70-0.90 0.70-0.90 0.70-0.90 0.75-1.00 0.45-0.65

3.25-3.75 1.40-1.75 ... . . . 0.40-0.60 1.65-2.00 0.40-0.60 1.65-2.00 3.25-3.75 3.25-3.75 0.70-0.90 0.80-1.10 0.40-0.70 0.40-0.60 0.40-0.70 0.40-0.60 0.40-0.70 0.40-0.60 0.40-0.70 0.40-0.60 3.00-3.50 1.00-1.40

0.40-0.70 0.40-0.60

2.75-3.25

0.35

2.00

Special alloys CBS-600 0.16-0.22 CBS0.10-0.16 1OOOM Alloy 53

0.10

(a)0.004Pmax,0.05

Smax.(b)0.15-0.35Si.

... 0.15-0.25 0.15-0.25 0.20-0.30 0.30-0.40 0.08-0.15

1.25-1.65 0.90-1.10 0.90-1.20 4.00-5.00 1.00

(b)> Cc) (b). Cc) (b), Cc) (b). Cc) (b)> Cc) (b). Cc) (b). (cl (b), (cl (b). Cc) (b), (c) (b). Cc) (b)> Cc) (b), Cc) (b)> Cc) (b), Cc)

0.20-0.30 0.20-0.30 0.08-0.15 0.20-0.30 0.20-0.30 0.20-0.30 0.20-0.30

3.25

0.90-1.25 Si 0.40-0.6OSi 0.15-0.25 V 1.OOSi, 2.00 cu,o.1ov

(c)O.035 Pmax,O.O4Smax

Available Carbon (the Weight of Carbon Obtained for Carburizing from a Given Gas at a Given Temperature). Charcoal gas analyzes 20 CO, 80 N,. Natural gas is principally methane. Data point 1: at 1700 “F (925 “C), the available carbon in charcoal gas is 0.0000272 lb/k3 (0.004357 kg/m3). Data point 2: in natural gas, there is 1200 times as much or 0.0337 IbW (0.5398 kg/ma)

50 / Heat Treater’s

formed. Properties ing Table.

Guide

of air-combustible

gas mixtures

are given in an adjoin-

Water Gas Reaction, CO + H,O CJ CO, + H,. Variation of equilibrium constant K with temperature. K is independent of pressure, since there is no volume change in this reaction.

Carburizing Equipment. Both batch and continuous furnaces are used. Among batch types, pit and horizontal furnaces are the most common in service. A pit furnace is illustrated in an adjoining Figure. Adisadvantage of the pit type is that when parts are direct quenched, they must be moved in air to the quenching equipment. The adherent black scale developed on parts with this practice may have to be removed by shot blasting or acid pickling. Horizontal batch furnaces with integral quenching facilities are an alternative (see Figure). Continuous furnaces used in carburizing include mesh belt, shaker hearth. rotary retort, rotary hearth, roller hearth, and pusher types.

Compositions Carbon steel, resulfurized In an adjoining Table.

steel, and alloy steel compositions

are listed

Reference I. ASM Metals Handbook, Hear Treating, Vol 4, 10th ed., ASM Intemational,

Pack

1991, p 312

Carburizing Operating

Information

In this process, carbon monoxide derived from a solid compound decomposes at the metal surface into nascent carbon and carbon dioxide. Carbon is absorbed into the metal; carbon dioxide immediately reacts with carbonaceous material in the solid carburizing compound to produce fresh carbon monoxide. Carbon monoxide formation is enhanced by energizers or catalysts such as barium carbonate, calcium carbonate, potassium carbonate, and sodium carbonate present in the carburizing compound. Energizers facilitate the reduction ofcarbon dioxide with carbon to form carbon monoxide, Ref I

The common commercial carburizing compounds are reusable and contain IO to 20 percent alkali or alkaline earth metal carbonates bound to hardwood charcoal, or to coke by oil, tar, or molasses. Barium carbonate is the chief energizer, usually accounting for 50 to 70 percent of total carbonate content. Process Control. Two parameters are unique to the process:

Characteristics

l

Both gas carburizing and liquid carburizing have labor cost advantages over this process. This disadvantage may be offset in jobs requiring additional steps, such as cleaning and the application of protective coatings in carburizing stopoff operations. Other considerations favor pack carburizing: A wide variety of furnaces may be used because the process produces its own contained environment l It is ideally suited for slow cooling from the carburizing temperature l It offers a wider selection of stopoff techniques than gas carburizing for selective carburizing techniques On the other side of the ledger, pack carburizing is less clean and less convenient to use than the other carburizing processes. In addition:

l

Case depth may vary within a given furnace due to dissimilar thermal histories within the carburizing containers Distortion of parts during carburizing may be reduced because compound can be used to support workpieces

Carbon potential of the atmosphere generated by the compound, as well as the carbon content obtained at the surface of the work, increase directly with an increase in the ratio of carbon monoxide to carbon dioxide.

l

l

l l

l

It isn’t well suited for shallow case depths where depth tolerances are strict It is labor intensive It takes more processing time than gas or liquid carburizing because of the heating time and cooling time required by the extra thermal mass associated with the solid carburizing compound and the metal container used It isn’t suited for direct quenching or quenching in dies

Effect of time on case depth at 925 “C (1700 “F)

Guidelines

Typical Applications

for the Heat Treatment

of Steel / 51

of Pack Carburizing CprbUIiZiIlg Dimensions(a) OD

Pall Mine-loader bevel gear flying-shear timing gear Crane-cable drum HigIl-misaligNnent coupting gear Continuous-miner drive pinion Heavy-duty ir~Iustrial gear Motor-brake wheel l-Qll-performance crane wheel Calender bull gear Kiln-uunnion roller Leveler roll Blooming-mill screw Heavyduty rotting-mill gear Prccessor pinch roU

OA

mm

in.

102 216 603 305 I27 618 457 660 2159 762 95 381 914 229

4.0 8.5 23.7 12.0 5.0 24.3 18.0 26.0 85.0 30.0 3.7 IS.0 36.0 9.0

mm

Weight in.

76 92 2565 152 I27 I02 215

3.0 3.6 101.0 6.0 5.0 4.0 8.9 6.0 24.0 16.0 31.3 131.0 159.0 212.0

I.52 610

406 794 3327 4038 5385

kg I.4 23.6 1792 38.5 5.4 IS0 IO4 335 5885 1035 36.7 2950 II 800 1700

lb 3.1 52.0 3950 84.9 II.9 331 229 739 I2975 2’80 80.9 6505 26015 3750

Steel 2317 2317 I020 46617 2317 I022 10’0 103s 1025 1030 3115 311s 2325 8620

Case depth to 50 ERC mm in. 0.6 0.9 I.2 I.2 I.8 I.8 3.0 3.8

4.0 4.0 4.0 5.0 5.6 6.9

0.02-I 0.036 0.048 0.048 0.072 0.072 0.120 0.150 0.160 0.160 0.160 0.200 0.220 0.270

Temperahue OF T

925

1700 I650 I750 I700 1700 I725 1700 1725 I750 I725 1700 1700 1750 I925

900 955 925 925 940 925 940 955 940 925 925 955 1050

(a) OD, outside diameter; OA, overall (axial) dimension

Operating temperatures normally run from 815 to 955 “C ( 1500 10 1750 “F). However, temperatures as high as 1095 “C (2005 “F) are used. The rate of change in case. depth at a given temperature is proportional to the square root of time. This means the rate of carburization is highest at the beginning of the cycle and gradually diminishes as the cycle continues. Case Depth. Even with good process control, it is difficult to hold case depth variation below 0.25 mm (0.010 in.) from maximum to minimum in a given furnace load, assuming a carburizing temperature of 925 “C (1695 “F). The effect of time on case depth is shown in an adjoining Figure. Furnaces are commonly of the box, car bottom, and pit types. Temperature uniformity must be controllable within &5 “C (+99 “F). Containers normally are made of carbon steel, aluminum coated carbon steel, or iron-nickel-chromium, heat-resisting alloys.

Liquid

Carburizing

and Properties

and workpiece is not provides good support

Applications

Reference I. ASM Metals Hundbook. Hear Treating, Vol 4, 10th ed.. ASM Intemational, 1991, p 325

and Cyaniding

Both are salt bath processes. In liquid carburizing. cyanide or noncyanide salt baths are used. Cyaniding is a liquid carbonitriding process. 11differs horn liquid carburizing because it requires a higher percentage of cyanide and the composition of the case produced is different. Cases produced in the carburizing process are lower in nitrogen and higher in carbon than cases produced in cyaniding. Cyanide cases are seldom deeper than 0.25 mm (0.010 in.); carburizing cases can be as deep as 6.35 mm (0.250 in.). For very thin cases, low-temperature liquid carburizing baths may be used in place of cyaniding, Ref I.

Compositions

Packing. Intimate contact between compound necessary, but with proper packing the compound for workpieces.

of Sodium

Cyanide

Liquid carburizing. Parts are held at a temperature above Act in a molten salt that introduces carbon and nitrogen, or carbon, into the metal being treated. Diffusion of the carbon from the surface toward the interior produces a case that can be hardened, usually by fast quenching, from the bath. Cyaniding. In this process, steel is heated above Act in a bath containing alkali cyanides and cyanates, and its surfaces absorb both carbon and nitrogen from the molten bath.

Mixtures specificgravity

ktktwegrade designation

NaCN

%98(a) 75(b) 45(b) 30(b)

97 75 45.3 30.0

Composition,w(% NaCOJ

Melting point NaCl

OC

OF

2.3 3.5 37.0 40.0

Trace ‘I.5 17.7 30.0

560 590 570 625

ICUI 1095 1060 115s

25oc (75W I.50 I .60 I.80 2.09

I.10 I .25 I.40 I.54

(a) Appearance: white crystalline solid. This grade contains 0.5%, sodium cyanate (NaNCO) and 0.X. sodium hydroxide (NaOH); sodium sulfide (Na,S) content. nil. (b) Appearance: white granular mixture

52 / Heat Treater’s

Typical Applications

Guide

of Liquid

Carburizing

Weight Part

In Cyanide

Baths

Depth of case mm in.

Temperature OC OF

Steel

Disk Flange Gage rings, knurled Hold-down block hen. tapered Lcwr Link Plate Plug Plug gage Radius-cutout toll Torsion-barcap

0.9 0.5 0.7 3.5 I.1 I.1 0.03 0.09 0.9 4.75 0.05 0.007 0.007 0.7 O.-IS 7.7 0.05

2 I.1 I5 7.7 2.5 3 0.06 0.2 2 IO.5 0.12 0.015 0.015 1.6 I I7 0. I

CR 1020 CR 1020 CR I020 1020 1020 CR 1020 1020 1018 IO10 CR 10’0 CR IO’2

I.0 IS I.5 1.3 1.3 I.3 0.4-0.5 I5 I.0 1.3 0.13-0.2s 0 13-0.2s 0 ‘S-O.-l I.5 I .s I .s 0.02-0.05

0.040 0.060 0.060 0.050 0 050 0.050 0.0 I s-0.020 0.060 0.040 0.050 0.005-0.010 0005-0010 0.010-0.015 0.060 0.060 0.060 0.001-0.002

940 9-10 9-lO 9-h) 940 9-10 815 9-10 9-10 9-to a-15 8-15 8-e 9.40 9-10 910 900

I720 I720 I720 I720 I720 I720 I550 I720 I720 I720 1550 1550 1550 I720 I720 I720 I650

4 6.5 6.5 5 5 5 -I 6.5 4 5 I I 2 6.5 6.5 6.5 0.12

AC AC AC AC AC (h) Oil AC AC AC Oil AC Oil AC AC AC Caustic

(a) (a) (a) (a) (a) (b) (C) (a)

Resulfurized steel Bushing Dash sleeve Disk Drive shah Guide bushing Nut Pm

0.01 3.6 0.0009 3.6 0.1 0.0-I 0.003

0.09 8 0.002 8 OS 0.09 0.007

III8 III7 III8 III7 III7 III3 III9

0.25-0.-l I.1 0.13-0.2s I.1 0.75 0.13-0.2s 0.13-0.25

0.010-0015 0.015 00050.010 0.045 0.030 0.005-0.010 0.009-0.010

815 915 81s 91.5 915 84.5 8-15

I550 I675 1550 1679 1675 IS50 1550

7 7 I 7 5 I I

Plug Rack Roller screw Shah Spring seat slop collar Stud Valve bushing Valve retainer Washer

0.007 0.31 0.0 I 0.003 0.08 0.009 0.9 0.007 0.02 0.15 0.007

0.015 0.75 0.03 0.007 0.18 0.02 2 0.015 0.05 I 0.015

III3 III3 1118 III3 III8 III8 1117 1118 III7 1117 III8

0.075-o. I3 0.13-0.2s 0.25-0.1 0.0750. I3 0.25-0.-l 0.2.5-0.4 I.1 0.13-0.2s 1.3 I.1 0.25-0.-l

0.003-0.005 0.0050.010 0.0 I o-0.0 IS 0 003-0.00.5 0.0 I o-0.0 I s 0.010-0.015 0.045 0.0050.0I0 0.050 0.045 0.0 I O-O.0IS

815 U-15 845 x-15 845 81s 925 x-l.5 915 915 a-15

I sso I550 IS50 1550 I550 I.550 1700 1550 1675 1675 ISSO

0.9-36 0.20 0.03 0.9 0.31 0.03 O.-IS 4.586 0.20 0.15-82 2.3-23 0.0009 0.45-5-I 0.20 S.-l I.8 0.0 I 0.20 0.45-3.6

2-80 0.5 0.06 2 0.75 0.06 I IO-190 0.5 l-180 S-50 0.002 I-120 0.5 I’ -I 0.03 0.5 l-8

8620 8620 8620 8620 8620 8620 8620 8620 8620 8620 8620 9317 86’0 8620 86’0 8620 8620 8620 8620

2.3 2.3 0.25-0.4 I .o I .o 0.075cl. I3 0.75 I .5 1.3 I.3 I.1 0. I-O.2 I.3 I.1 ‘3 I .s 0.1-03 I.1 I3

0.090 0.090 0.0 I o-0.0 IS 0.040 0.040 0.003-0.005 0.030 0.060 0.050 0.050 0.045 0 00-l-0.008 0.050 0.045 0.090 0.060 0.01 s-o.020 0.045 0.050

9’5 925 8-15 915 915 8-15 915 9’9 915 91s 91.5 81s 925 915 925 915 84s 915 915

I700 I700 I.550 I675 I675 1550 I675 1700 I675 1675 1675 I s50 1700 I675 I 700 I675 IS50 I675 I675

Carbon steel Adaprcr Arbor. tapered BWJliflg Die block

Alloy steel Beating races Bearing rollers Couplmg Crankshaft Gear Idler shah Pintle Piston Plunger Ram Retainer Spool Thrust cup Thrust plate Universal socket Valte valve seat Wear plate

Tie,

h

Quench

Subsequent treatment

lb

kg

Eardnes., ERC

(a) (a) (c)

62-63 62-63 62-63 62-63 59-61 56-57 55 mitt(d) 62-63 62-63 62-63 W

(C) (a) (a) (a) (0

(e) 62-63 62-63 62-63 45-47

Oil AC Brine AC (j) Oil Oil

(d (iit) Cc) (h)

Cd 58-63 (e) 58-63 58-63 W (e)

0.5 I 7 OS 2 2 6.5 I 8 7 2

Oil Oil Oil Oil Oil Oil AC Oil AC ci) Oil

(CJ w (C) (C) Cc) (C) (I?) (c) (8)

II II 2 6.5 6 0.5 5 I’

AC AC Oil AC AC Oil (i) tit AC (ii (ij Oil ti) tit AC AC Oil AC AC

(is) (I3

8

8 7 0.33 7 7 I-l IO -I 7 7

w (C)

(c)

IL; w (c)

(8

ti)

(P) $ (ia (8)

1:; l:; W (e) 60-63 k) 58-63 58-63 (e) 61-64 61-64 (e) 60-63 60-63 (e) 58-63 58-63 60-63 58-63 58-63 (a 58-63 58-63 60-6-I 58-63 60 mm(d) 60-63 60-63

(a) Reheatedat79O”C( 1150”F),quenched incaustic. temperedat 150”C(30O”F~. tb~Transferrrd~o neutralsalt at 79O’C( 1450°F).qurnchedincaustic, temperedat I75 “C(350 “F). (c)Tempered at I65 “C (325 “Ft. (d) Or equivalent. te) File-hard. (0 Tempered at 205 “C (400 “F). tg) Reheated at 8-U OC( I SSO“FJ. quenched in salt al I75 “C (350 “F). (h) Reheatedat775”C( 1325”F).quenched insaltat 19S”Ct380°Ft.(i)Quencheddirectl~ insaltar 17S”Ct3SO”Ft.tj)Temprredat 16s 0C~3250F)andtreatedat-850C(-1300Ft

Guidelines

Liquid

Operating

Carburizing

Characteristics The case produced is comparable to one obtained in gas carburizing in an atmosphere containing some ammonia. In addition, cycle times are shorter because heat up is faster, due to the excellent heat transfer characteristics of the salt bath solution.

Operating

Information

Most of these baths contain cyanide. Both nitrogen and carbon are introduced into the case. A noncyanide process uses a special grade of carbon, rather than cyanide, as the source of carbon. These cases contain only carbon as the hardening agent. Low-temperature (for fight cases) and high-temperature (for deep cases), cyanide-containing carburizing baths are available. In addition to operating temperatures, cycle times can also be different. Low-Temperature Baths. Typical operating temperatures range from 845 to 900 “C (1555 to 1650 “F). Baths generally are of the accelerated cyanogen type. Operating compositions of liquid carburizing baths are listed in an adjoining Table. Baths usually are operated with a protective carbon cover. Cases that are 0. I3 to 0.25 mm (0.005 to 0.010 in,) deep contain substantial amounts of nitrogen. High-Temperature Baths. Operating temperatures usually are in the range of 900 to 955 “C (1650 to 1750 “F). Rapid carbon penetration may be obtained at operating temperatures between 980 and 1040 “C ( I795 to 1905 “F). Cases range from 0.5 to 3.0 mm (0.020 to 0. I20 in.) deep. The most important application of this process is for the rapid development of cases I to 2 mm (0.040 to 0.080 in.) deep. These baths contain cyanide and a major amount of barium chloride (see Tablej.

Applications Typical applications an adjoining Table.

of liquid carburizing

Noncyanide

Liquid

in cyanide

baths are listed in

Carburizing

A specirll grade of carbon is used in place of cyanide as the source for carbon. Carbon particles are dispersed in the molten salt by mechanical agitation with one or more simple propeller stirrers. The chemical reaction is thought to be adsorption of carbon monoxide on carbon particles. Carbon monoxide is generated by a reaction between carbon and carbonates in the salt bath. Carbon monoxide is presumed to react with steel surfaces in a manner similar to that in pack carburizing.

Operating

Information

Operating temperatures usually are higher than those for cyanide-type baths. The common range is about 900 to 955 “C ( I650 to I750 “F). Case depths and carbon gradients are in the same range as those for hightemperature, cyanide-type salts. Carbon content is slightly lower than that of standard carburizing baths containing cyanide.

Cyaniding Operating

(Liquid

Constituent

for the Heat Treatment

Compositions

of Liquid

of Steel / 53

Carburizing

Baths

Composition ofbath, % Light case, Deep case, low temperature high temperature 8.l~900°C (1550-16SO“F) 9oo-95S°C (16-W175oT)

IO-23 Sodiumcyanide 6-16 Barium chloride 30-55(a) Salts ofother alkaline O-IO O-IO earth met&t h) Potassium chloride O-25 O-20 Sodium chlonde ‘O-40 O-20 30 max Sodium carbonate 30 max Accelerators other than O-5 o-2 those in\olvingcompounds of alkaline earth metals(c) 0.5 milx Sodium cyanate I .Oniax Den.@ of molten salt I .76 g/crdat 900 “C tO.0636 2.00 gkm’at 92s “C (0.0723 Ih/in.‘at 1650°F) Ib/in.‘at 1700°F) (a) Proprietary barium chloride-free deep-case baths are available. (b) Calcium and strontium chlorides ha\e hecn employed. Calcium chloride is more effective, but its hyqoscopic nature has limited its use.(c) Among theseacceleratorsare manganesedioxtde. boron oxide, sodium fluoride, and sodium pyrophosphate.

Effect of Sodium Cyanide in 1020 Steel Bars

Concentration

on Case Depth

Samples are 25.4 mm diam (1 .O in. diam) bars that were cyanided minat815”C(1500”F). NaCN in bath, 96

mm

ill.

9-l.3 76.0 SO8 -13.0 30.2 20.8 15.1 10.8 52

0 IS 0.18 0.15 0.15 0.15 0.14 0.13 0.10 0.05

0.0060 0.0070 0.0060 0.0060 0.0060 0.0055 0.0050 0.0040 0.0020

30

Deptb of case

Faster carbon penetration is obtained by using operating temperatures above 950 “C (I 730 “Ft. Nancy anide baths are not adversely affected at this temperature because no cyanide is present to break down and cause carbon scum or frothing. Parts quenched after treatment contain less retained austenite than those quenched following cyanide carburization.

Carbonitriding)

Information

In this instance, sodium cyanide is used instead of the more espensive potassium cyanide. The active hardening agents (carbon monoxide and nitrogen) are produced directly from sodium cyanide.

A sodium cyanide mixture such as grade 30 (containing 30 percent NaCN, -IO percent Na2C.03. and 30 percent NaCI) generally is the choice for production applications (see Table shorn ing compositionsj. A 30 percent cyanide bath operating at 8 IS to 850 “C ( IS00 to IS60 “F) produces a 0. I3 mm (0.005 in.) case containing 0.65 percent carbon at the surface in

54 / Heat Treater’s

Guide

45 min. Similar

case depths can be obtained with sodium cyanide in treating 1020 steel. The effect of sodium cyanide on case depth in treating the steel is in an adjoining Table.

brine. The case contains less carbon and more nitrogen oped in liquid carburizing.

Applications

Reference

A fde hard, wear-resistant surface is produced on ferrous parts. The hard case is produced in quenching in mineral oil, paraffin-base oils, water, or

I. ASM Metals Handbook, Heat Treating, Vol4. tional. 1991, p 329

Vacuum

in a then

Characteristics Benefits of the process include:

l l

Excellent uniformity and repeatability due to the degree of process control inherent in the process Improved mechanical properties due to a lack of intergranular oxidation Reduced cycle times due to higher processing temperatures

A continuous

10th ed., ASM Intema-

Carburizing

In this process, steel is austenitized in a rough vacuum, carburized partial pressure of hydrocarbon gas, diffused in a rough vacuum, quenched in oil or gas, Ref I.

l

than those devel-

ceramic

vacuum-carburizing

furnace

Operating

Information

A continuous vacuum carburizing furnace is pictured in an adjoining Figure. Furnaces usually are designed for vacuum carburizing. with or without vacuum quenching capability. Controls and plumbing are modified to accommodate the process. Heat and Soak Step. Steel is fust heated to the desired carburizing temperature (typically in the range of 845 to 1040 “C (1555 to 1905 “F). Soaking follows at that temperature, but only long enough to get temperature uniformity throughout the part. In this step, surface oxidation must be prevented, and any surface oxides present must be reduced. In a graphite-lined heating chamber with graphite

Guidelines

for the Heat Treatment

Comparison of Time Required to Obtain a 0.9 mm (0.035 in.) and 1.3 mm (0.050 in.) Effective 8820 Steel at Carburizing Temperatures of 900 “C (1850 “F) and 1040 “C (1900 “F) Carburizing temperature

Effective depth mm in. 0.9

0.035

1.3

0.050

T 900 I040 900 1040

OF

lkatiog to carburizing temperature

1650 1900 1650 1900

78 90 78 90

smkiog prior to carburizing

Boost

45 30 45 30

Time, mio Gas quench toHoT Diffusion (ItWOoF)

101 1s 206 31

83 23 169 46

of Steel / 55

Case Depth in an AISI

Reheat to 845 oc (1550°F)

soak at 845T (155OV)

oil quench

Total

(a) 22 (a) 22

(a) 60 (a) 60

1s 1s 15 I5

>322 275 >s13 314

(3) 20 (Jo 20

(a) Not available

heating elements, for example, a rough vacuum in the range of 13 to 40 Pa (0. I to 0.3 torr) usually is satisfactory. Boost Step. The result here is carbon absorption by the austenite to the limit of carbon solubility in austenite at the processing temperature for the steel being treated. The operation in this instance is backfilling the vacuum chamber to a partial pressure with either a pure hydrocarbon gas, such as methane or propane, or a mixture of hydrocarbon gases. A minimum partial pressure of the gas is needed to ensure rapid carburizing of the austenite. Minimum partial pressure varies with carburizing temperature, gas composition, and furnace construction. ‘Qpical partial pressures vary between I .3 and 6.6 kPa ( IO to 50 torr) in furnaces of graphite construction and I3 to 25 kPa ( 100 to 200 [err) in furnaces of ceramic construction. Diffusion Step. In this instance, carbon is diffused inward from the carburized surface, resulting in a lower surface carbon content (relative to the limit of carbon solubility in austenite at the carburizing temperature) and a more gradual case/core transition. Diffusion usually is in a rough vacuum of 67 to I35 Pa (0.5 to I .O torr) at the carburizing temperature. Oil Quenching Step. Steel is directly quenched in oil, usually under a partial pressure of nitrogen. When temperatures are higher than those in conventional atmosphere carburizing. requirements usually call for cooling to a lower temperature and stabilizing at that temperature prior to quenching. If a reheating step is needed for grain refinement, the steel is gas quenched from the diffusion temperature to room temperature, usually under partial pressure of nitrogen. Reheating usually consists of austenitizing in the range of 790 to 845 “C (1455 to 1555 “F), followed by oil quenching.

Plasma

(Ion)

Characteristics The process has several advantages ing:

l l l l

l l

Gas Circulation.

For uniform

case depths the chief re-

are:

Temperature uniformity of +8 “C (fl4 “F) or better Uniform circulation of carburizing gas

High-Temperature

Vacuum

Carburizing

Typical atmosphere furnace construction generally limits maximum carburizing temperatures to about 955 “C (1750 “F). Vacuum furnaces permit higher carburizing temperatures, 14ith correspondingly reduced cycle times. The process can significantly reduce overall cycle times required to get effective case depths in excess of 0.9 to I .O mm (0.030 to 0.040 in.). There is no advantage for lower case depths. In an adjoining Table, the times needed to get 0.9 to I .O mm (0.030 to 0.040 in.) case depths with vacuum carburizing at 900 “C (I650 “F) and 1040 “C (1905 “F) for an AISI 8620 steel are compared.

Applications The process is well suited to process the more highly alloyed, highperformance grades of carburizing steels and the moderately alloyed grades being used. Gas pressure quenching in vacuum opens up opportunities for treating high-performance, low distortion gearing.

Reference I. ASM Metals Handbook, Hear Treating, Vol 4, 10th ed.. ASM tional, 1991. p 3-18

Intema-

Carburizing

This is basically a vacuum process utilizing glow discharge technology to introduce carbon bearing ions to steel surfaces for subsequent diffusion below the surfaces, Ref I.

l

Carburizing quirements

Higher carburizing rates Higher operating temperatures Improved case uniformity Blind hole penetration Insensitivity lo steel composition

over gas and atmosphere

carburiz-

Carburizing rates are higher because the process involves several steps in the dissociation process that produce active soluble carbon. With methane, for example, active carbon can be formed due to the ionizing effect of the plasma. Carburizing rates of plasma and atmosphere carburizing are compared in an adjoining Figure. Note that the results obtained in atrnosphere carburizing for 240 min at 900 “C (1650 “F) were obtained with the plasma process in half the time. In some applications, higher temperatures are permissible because the process takes place in an oxygen-free vacuum. Improvements in unifomlity of case depth in gear tooth profiles are shown in an adjoining Figure. Results obtained with the plasma process at 980 “C (I795 “F) and those obtained \sith atmosphere carburizing at the same temperature are compared.

56 / Heat Treater’s

Guide

Carbon concentration profiles in AISI 1020 steel after ion carburizing for 10,20,30,60, and 120 min at 900 “C (1650 “F). Carbon profile after atmosphere carburizing (1650 “F) shown for comparison

Production installation

for 240 min at 900 “C

Comparing uniformity of case depth over gear-tooth profiles. (a) Ion carbunked at 980 “C (1800 in a 980 “C (1800 “F) boost-diffuse its more consistency, particularly Courtesy of Surface Combustion,

“F). (b) Atmosphere carburized cycle. Case depth in (a) exhibin the root of the gear profile. Inc.

of two dual-chamber ion carburizing furnaces. Courtesy of Surface Combustion,

Inc.

Guidelines

Racked array of universal-joint Courtesy

components ready for ion carburizing. Two stacked

fixtures

for the Heat Treatment

constitute

one furnace

of Steel / 57

load of 1500 parts.

of Dana Corporation

Carbon concentration profiles in three carburizing steels after ion carburizing illustrating insensitivity to steel composition. Data are based on a boost-diffuse cycle of ion catburizing at 1040 “C (1900 “F) for 10 min followed 1000°C (1830°F).

by diffusion

for 30 min at

1

The ion carburizing rate for a given steel is quite insensitive to alloy composition, as shown in an adjoining Figure. The process is also insensitive to the hydrocarbon gas used as a source of carbon. A two-chamber ion carburizing furnace is shown in an adjoining Figure. As in other carburizing processes, time and temperature are the parameters that determine surface carbon and case depth. Temperature, and indirectly time, dcterrnine grain size and mechanical properties. Higher operation temperatures are used to speed up diffusion rates. After a time/temperature cycle is established, operating pressure is chosen, which can be any value. provided the plasma covers the parts and no hollow cathode effect is evident; a low pressure usually is chosen, in the range of 130 to 670 Pa (I to 5 torr). Optimum uniformity in carburizing is obtained in this range. The gas may be any hydrocarbon. The simplest and most commonly used is CHJ (methane). Propane (C3Hs) is also used. To be successhtl in plasma carburizing, the plasma envelope must surround the parts, meaning that parts must be finned. or positioned so that they do not touch each other (see Figure). In the figure universal joint components are stacked in layers separated by a woven wire screen between layers.

Applications The range of applications

includes

1020, 1521, and 8620 steels.

Reference I. ASM Metals Handbook, tional, 1991. p 353

Heat Treating,

Vol 4. 10th ed., ASM

Intema-

58 / Heat Treater’s

Guide

Carbonitriding This is a modified form ofgas carburizing. rather than a form of nitriding. The modification: ammonia is combined with the gas carburizing atmosphere to add nitrogen to the carbutized case as it is being produced. Nascent nitrogen is at the work surfaces. Ammonia dissociates in the furnace atmosphere: nitrogen diffuses into the steel simultaneously with carbon. Ref I.

Characteristics Carbonitriding is similar to liquid cyaniding in terms of its effects on steel. The process is often substituted for liquid cyaniding because of problems in the disposal of cyanide-bearing water. Case characteristics of carburized and nitrided parts are also different; carburized cases normally

Effect of Material/Variables Formation in Carbonitrided

hlaterial/processing

variables(a)

Tempenture increase Longer cycles Highercase nitrogen levels Higher case carbon levels Alumintu~-killed steel tncrcased alloy content of steel Severe prior cold working of material Ammonia addition during heat-up cycle

on the Possibility Cases

of Void

do not contain nitrogen, and nitrided cases are primarily nitrogen, while carbonitrided cases contain both carbon and nitrogen. Ability to produce hard, wear-resistant cases, which are generally in the range of 0.075 to 0.75 mm (0.003 to 0.030 in.), is the typical reason for selecting this process. Cases have better hardenability than carburized types (nitrogen increases the hardenability of steel); nitrogen is also an austenite stabilizer. and high nitrogen levels can result in retained austenite. particularly in alloy steels. Economies can be realized with carbonitriding and quenching in the production of hard cases within a specific case depth range and for either carbon or low-alloy steel. With oil quenching, full hardness with less distortion can be obtained, or in some cases, with gas quenching, using a protective atmosphere as the quenching medium. Another plus: carburizing and carbonitriding often are combined to get deeper case depths and better performance in service than are possible with carbonitriding alone.

Operating Possibility of void formation Increased Increased Increased increased Increased DeWXsed Increased Increased

Information

Industrial practice for time and temperature is indicated in an adjoining Figure. which shows the effects of time and temperature on effective depth (as opposed to total case depth). Effects of total furnace time on the case depth of 1020 steel is shown in adjoining Figure (a). Specimens were heated to 705.760,815. and 870 “C

Results of a survey of industrial practice regarding effects of time and temperature on effective case depth of carbonitrided cases

(a) All other variables heldconstant

Effects of temperature and of duration of carbonitriding on effective case depth. Both sets of data were obtained in the same plant. Note that upper graph (for 1020 steel) is in terms of total furnace time, whereas bottom graph (for 1112 steel) is for 15 min at temperature.

End-quench hardenability curve for 1020 steel carbonitrided at 900 “C (1650 OF) compared with curve for the same steel carburized at 925 “C (1700 “F). Hardness was measured along the surface of the as-quenched hardenability specimen. Ammonia and methane contents of the inlet carbonitriding atmosphere were 5%; balance, carrier gas.

Guidelines

Typical

Applications

and Production

Cycles

for the Heat Treatment

of Steel / 59

For Carbonitriding

Part

Steel

Case depth mm 0.001 in.

Furnace temperature T OF

Carhoo steels Adjusting yoke, 25 hy 9.5 mm ( I by 0.37 in. j Bearing block,64 by 32 by 3.2 mm (2.5 by I.3 by 0.13 in.) Cam. 2.3 by 57 by 64 mm (0. I bj 2.25 hy 2.5 in.) cup. I3 g (0.4602) Distributordriveshaft. I25 mmOD by 127 mm (5 by 5 in.) Gear,-U.Smmdiamby3.2mm(l.75by0.l2Sio.) Hex nut. 60.3 hy 9.5 mm (2.4 b] 0.37 in.) Hood-latch bracket, 6.1 mm diam (0.25 in.) Link 2 hy 38 by 38 mm (0.079 hy I .S b> I.5 in.) hlandrel, 40 g ( I .AI 02) Paper-cutting tool, 4 IO mm long Segment 2.3 hy 44.5 hy 44.5 mm (0.09 by I.75 by I .7S tn.) Shaft. 1.7 mm diam hy IS9 mm (0. I9 bj 6.25 in.) shiftcollar,s9g(2.loz) Slidingspurgear,66.7mmOD(2.625 in.) Spring pin, 14.3 mmOD by I l4mm(O.S6 by-l.5 in.j Spur pinion shaft. II .3 mm OD (I ,625 in.) Transmission shift fork. I27 hy 76 mm (5 by 3 in.)

1020 1010 1010 101s 1015 1213(h) 1030 1015 1022 III7 1117 1010 1213(b, III8 1018 1030 1018 1040

0.05-O. IS 0.05-O. I5 0.38-0.45 0.08-o. I3 0. IS-O.25 0.30-0.38 0. IS-O.25 0.05-0.1.5 0.30-0.38 0.20-0.30 -0.7s 0.28-0.45 0.30-0.38 0.30-0.36 0.38-0.50 0 25-0.50 0.38-0.50 0.25-0.50

2-6 2-b IS-18 3-s 6-10 12-15 6-10 2-6 11-15 8-l’ -30 15-18 12-15 12-l-l 15-20 IO-20 IS-20 I O-20

775 and 715 775 and 7-lj 855 790 8lSand7-15 855 815and745 775 and 745 855 845

1125and 1375 1125 and I375 IS75 I150 I SO0and I375 I575 IS00 and I375 I-I?i and I375 IS15 IS50

855 815 77s 870 815and7-15 870 815and7-15

I S75 I.500 I-130 1600 IS00 and I375 I600 I500 and I375

Alloy steels Helical gear, 82 mm OD (3.23 in.) Input sti I.2 kg (2.6 lb) Pinion gear. 0.2 kg (O.-U lb) Ring gear, 0.9 kg (2 lb) Segment I .4 hy 83 mm (0.OS.Tby 3 17 in.j Spur pinion shaft. 63.5 mm OD by 203 mm (2.S by 8 in.) Stationary gear plate, 0.32 kg (0.7 Ihj Transmission main shaft sleeve, 38 mm OD by 25 mm (I .S by 2 in.) Transmission main shaft washer, 57 mm OD b! 6.4 mm (2.25 b> 0.25 in.)

8617H 5140 4017 1047 8617 5 I40H 5110 8622 8620

0.50-0.7s 0.30-0.3s 0.30-0.3s 0.20-0.30 0. IX-0.2s 0.0.5-0.20 0.30-O 35 0. I s-0.25 0.25-0.50

20-30 12-14 12-11 8-10 7-10 2-8 12-l-l 6-10 IO-20

845 775 77s 760 815 845 775 8I5and715 8lSand715

IS50 I430 l-130 l-m0 1500 1550 I430 I SO0and I375 15OOand 1375

Total time in Furnace

Quench

64min @mitt 2’/?.h ‘/? h 108min I v4 h 64min &min I ‘/? h I ‘/z h

Oil Oil Oil Oil Gas(a) Oil(c) Oil Oil Oil Oil

2h:fj I44min 2 h(lI I62 min

Oil Gas(a)(d) Oil(e) Oil(g) Oil Oil(h) GW)

6h(f)

Oil(g)

51/?h 5 ‘/2 h 9h I 1/Zh I MD 51/, h 108min I62 min

Oil(e) Oil(e) Oil(i) Ga.sW Oil(j) Oil(e) Gt3.W

(a) Modifiedcarboniuidingatmosphere. (b) Leaded. rc) Tempered at 190°C (375 “F). td)Temperedal 150°C (300 “FJ. (c)Tempered ;II 16.5“C (325 “F). (f Tiieat (g)Oilatl50”C(300”F):temperedatlS0”C(300”~forIh.(h)oilatl50”C(,300”F)temper~dat76O”C(500”F)forIh.(i)Temprredatl75”C(350oF).(i)OilatISO”C(300 “F); tempered at 230 “C (150 “F) for 2 h. OD, outside diameter

Effect of ammonia additions on nitrogen content and formation ‘C(1695 “F) 0.13% (c) 950 “C (1720 “F) 0.10% CO,

co,.

of subsurface

Gas(a) temperature,

voids in foils. (a) 850 “C (1580 “F) 0.29% CO,. (b) 925

60 / Heat Treater’s Guide (1300,1400,1500, and 1600 “F). An adjoining Figure(b) shows total case depthsobtained with 1112steelheld at 15 min at temperaturesbetween750 and 900 “C (1380 and 1650 “F). Depth of Case. l

l

l

l

l

Casedepthsof 0.025 to 0.075 mm (0.001 to 0.003 in.) commonly areput on thin parts requiring wear resistanceunder light loads. Casedepthsup to 0.75 mm (0.030 in.) are applied to parts such ascams for resistanceto high compressiveloads. Casedepthsof 0.63 to 0.75 mm (0.025 to 0.030 in.) are applied to shafts and gears subjectedto high tensile or compressive stresses,or contact loads. Medium-carbon steel with hardnessesof 40 to 45 HRC normally require less casedepth than steelswith core hardnessesof 20 HRC or below. Low-alloy steelswith medium-carbon content, i.e., those used in transmission gears for autos, often have minimum case depths of 0.2 mm (0.008 in.).

Hardenability of Case. Case hardenability is significantly greater when nitrogen is addedby carbonitriding than when the samesteel is only carburized (seeFigure). This opensup the use of steelsthat could not have uniform hardnessif they were only carburized and quenched. When core properties are not important, carbon&riding permits the use of low-carbon steelsthat cost less and may provide better machinability or formability. Because of the hardenability effect of nitrogen, the process makes it possible to oil quench such steels as 1010, 1020, and 1113 to obtain martensitic casestructures. Void Formation. Casestructuresmay contain subsurfacevoids or porosity if processing conditions are not adjustedproperly (seeFigure). The problem is related to excessiveammonia additions. Factorsthat contribute to the problem are summarizedin an adjoining Table. Furnaces. Almost any furnace suitable for gas carburizing can be adaptedfor carbonitriding. Atmospheresgenerally are a mixture of carrier gas, enriching gas, and ammonia. Basically, the required atmospherecan be obtained by adding 2 to 12 percent ammonia to a standardgas-carburizing atmosphere. Quenching. Whether parts are quenched in water, oil, or gas depends on allowable distortion, metallurgical requirements,caseor core hardness, and type of furnace used.

Tempering. Many shallow caseparts are used without tempering. Nitrogen in the caseincreasesresistanceto softening-the degreedepending on the amount of nitrogen in the case.

Applications Applications are more restricted than those for carburizing. The process is largely limited to case depths of approximately 0.75 mm (0.03 in.). Typical applications and production cycles for a number of steelsare listed in an adjoining Table. On the plus side, resistanceto softening during tempering is markedly superior to that of a carburized surface. Other benefits include residual stresspatterns,metallurgical structure, fatigue and impact strength at specific hardnesslevels, and the effects of alloy composition on caseand core hardness characteristics. In many applications, properties equivalent to those obtained in carburizing alloy steelscan be obtained with less expensive gradesof steel. On the minus side, a carbonitrided caseusually contains more retained austenite than a carburized caseof the samecarbon content. However, the amount of retained austenite can be significantly reduced by cooling quenchedparts to -40 to -100 “C (-40 to -150 “F). P/M Applications. The processis widely usedin treating ferrous powder parts. Partsmay or may not be copper infiltrated prior to carbonitriding. The processis effective in casehardening compactsmadeof electrolytic powders which are difficult to harden by carburizing. To avoid such problems,parts are treatedat 790 to 8 15 “C (1455 to 1500 “F). Lower rates of diffusion at these temperaturespermit control of casedepth and allow the buildup of adequate carbon in the case. The presence of nitrogen provides sufficient hardenability to allow oil quenching. File hard cases(with microhardness equivalent to 60 HRC) with predominately martensitic structurescan be consistently obtained. Partsusually are temperedeven though there is little danger of cracking untemperedpieces. However, there is a reasonfor tempering: it facilitates tumbling and deburring operations.

Reference 1. ASM Metals Handbook, Heat Treating, Vo14, 10th ed., ASM Intemational, 1991,p 376

Gas Nitriding In this process,nitrogen is introduced into the surface of a solid ferrous alloy at a temperaturebelow AC] in contact with a nitrogen gas, usually ammonia, Ref 1.

Nitriding downgradesthe corrosion resistanceof stainlesssteel because of its chromium content. On the upside, surface hardnessis increasedand resistanceto abrasion is improved.

Characteristics

Operating

A hard case is produced without quenching. Benefits of the process include:

The nitriding temperaturefor all steelsis 495 to 565 “C (925 to 1050OF). All hardenablesteelsmust be hardenedand temperedprior to nitriding. The minimum tempering temperature usually is at least 30 “C (55 “F) above the maximum nitriding temperature. Either a single- or double-stageprocess may be used in nitriding with anhydrous ammonia. The operating temperatureof the single-stageprocessis in the range of about 495 to 525 ‘C (925 to 975 “F). A brittle, nitrogen-rich layer, called the white layer, is produced on the surfaceof the case. Reducing white layer thicknessesis a benefit of the double-stageprocess-also called the Floe process.Nitriding applications for both processes are listed in an adjoining Table. White layers produced in the single- and double-stageprocessesare comparedin an adjoining Figure. Examples of where nitriding eliminates production or service problems with parts case hardenedby other methodsare found in an adjoining Table.

l l l l

High surfacehardness Improved resistanceto wear and galling Improved fatigue life Improved corrosion resistance(stainless steel is an exception)

In addition, distortion and deformation are less than they are in carburizing and other conventional hardening processes.Best results are obtained with steels containing one or more of the nitride-forming alloying elements-aluminum, chromium, vanadium, tungsten, and molybdenum. Other alloying elements such as nickel, copper, silicon, and manganese have little, if any, effect on nitridmg characteristics.Alloys containing 0.85 to 1.50 percent aluminum yield the best results (seeTable).

Information

Guidelines

Hardness gradients and case depth relations for single-stage nitrided aluminum-containing

for the Heat Treatment

SAE 7140 steel

of Steel / 61

62 / Heat Treater’s

Nitriding

Guide

Applications

and Procedures

Part

Dimensions or weight of part

Single-stage nitriding Hydraulic barrel Trigger for pneumatic h-er Governor push button Tachometer shaft Helical timing gear Gear Generator shaft Rotor and pinion for pneumatic drill Sleeve for pneumatic tool clutch hlarine helical transmission gear Oil-pump gear Loom shuttle Double-stage nitriding Ring gear for helicopter main transmission Aircraft cylinder barrel Bushing Cutter spindle Plunger CtXtlkShilft Piston ring Clutch Double helical gear Feed screw Pumper plunger Seal ring Stop pin Thrust collar Wear ring Clamp Die Gib Spindle Torque gear Wedge Pumper plunger

SOmtn(2in.jOD.

19mm(3/~in.jfD.

Steel

ISOmm(6in.jlong

Nitriding

time, h

6mm(‘/Iin.)diam 380mm(l5in.)long 205mm(8in.)OD(-t.Sk or IOlb) 9 Ltin.)thick 50mm(2in.)OD.6mm( 25 mm (I in.) OD. 355 mm (14 in.) long 22 mm (7/8in.)diam 38 mm ( I ‘/J in.) diam 635 mm (3-Sin.) OD (227 kg or 500 lb) SOmm(2in)OD. 180mmt7in.)long I SOmm by 25 mm by 25 mm (6 in. by I in. by I in.)

AMS 6170 A hf.5 6-470 AMS 6-!70 AhlS 6-47s -1140 -II-IO -II-t0 -II-IO 4l-u) -II42 1330 4lOstainless

230

380mm(lSin.)OD.3S0mm(l3.8in.)a),~mm(3.Sin.)long 180mnt(7in.)DD,305mmt,12in.)long lOkg(23Ibj 3 kg(7 lb) 7Smm(3in.jOD.l52Smnt16Oin.)long 205 mm (8 in.) OD (journals). -I m (I3 ft) long lSOmm(6in.)OD.4.2Sm(I-lti)long I kg(2 lb) 50kg(l08lb) 4 kg (9 lb) 0.5 kg t I lb) 9.S kg (2 I Ihj 3 kg (7 lb) 3.6 kg(8 lb) 40kg(87lh) 7kg(l5Ib) 21 kg(A7lbj IO kg(23 Ibj I22 kg(270lb) 62Skg(l38Ib) I8kg(Ilb) I.lkg(3lb)

AhlS 6-170(a) A MS 6470 AhlS 6170 AhlS 6470 AMS 6-t7s -1130 3130 -II40 -II-l0 -11-M) 4l-tO -1130 41-u) 11-M -II40 1150 43u) -t3Jtl 1330 J3-u) -I340 -120stainless

60(b)

2 24 24 9 9 32 25 8

35(c) 90 4s 72 65 65 2 45 I27 90 2 90 2 2 90 42 127

Note: OD,outerdiameter; ID, innerdiameter. (a) Vacuum melted. (h)9 hat 525 “C (975 “F). 5 I hat S-t5 to SSO”C( 1015 to 1025 “F). (c)6 hat S’S “C(975 “Fj, 29hat S65 “C( 1050°F)

Examples of Parts for Which Nitriding Requirements Part

Proved Superior

to Other Case-hardening

Requirement

Gear High-speed pinion (on gear motor) Bushings (for conveyor rollers handling ahrasive alkaline material) Spur gears (in train of power geats; IO-pitch. tip modified)

Good wear surface and fatigue properties Provide teeth with minimum (equivalent) hardness of SOHRC High surface hardness for abrasion resistance; resistance to alkaline corrosion Sustain continuous Hertz stress of 1035 klPa ( I50 ksi) (overload of I MO hlPa, or 275 ksi). continuous Lewis stress of 275 hlPa(40 ksijto\erloadof725 hlPa or IO5 bij(c)

Processes

for Meeting

Material and process originally

used

Carhurized 33 IO steel 0.4 to 0.6 mm (0.017 to 0.02.5 in.) case X620 steel gas carburized at 900 “C ( I650 OF)to 0.5 mm (0.02 in.) case, direct quenched fmnt 815 “C ( 1550 “F), and tempered at 205 “C (300°F) Carburized bushings Carbutired AhlS 6260

Resultant problem Gear

Good wear surface and fatigue properties

High-speed pinion (on gear motor)

Pro\ ide teeth with mintmunt (equivalent) hardness of SOHRC

Difficulty in obtaining satisfactory case to meet a reliability requirement Distortion in teeth and bore caused high rejection rate

Bushings (for comevorrollers site alkaltne material)

handbngahra-

High surface hardness for abrasion resistance; resistance to alkaline corrosion

Sen ice life of bushings was short because of scoring

Spurgears(in trainof powergeats; IO-pitch, tip modified)

Sustain continuous Hertz stress of 1035 hiPa t 150 ksij (overload of IS50 hIPa. or 235 ksi ). continuous Lea is stress of 275 hlPa (-IO hi) (overload of 72s hlPs or IO.5ksij(c)

Gears failed because of inadequate scuffreststartce. also suffered property losses at high operating temperatures

Solution Ah1.86170substituted for33lOand double-stage nitrided for 25 h ll4Osteel. substituted for 8620, was heat treated to 255 HB; parts were rough machined tinish machined. niuided(a) Substitution of Nitralloy I35 type G (resulfurired) heat treated to 269 HB and nitrided(hj Substitution of material of H I I type, hardened and multiple tempered (3 h + 3 h) to 18 to 52 HRC, then doublestage nitrided(d)

(a) Single-stage nitrided at5 IO’C (950°F) for 38 h. Cost increased 55,. but rejection rate dropped to zero. (b) Single-stage ninidedat S 10°C (950°F) for 38 h. Casedepth wasO.-l6 mm (0.018 in.), and hardness was 94 HR IS-N: parts had three times the senice life of carburized parts tc) hlust withstand operating temperatures to 290°C (550 “Fj. (d) IS hat 5 IS “C (%O “F) ( IS to 25% dissociation); then 525 ‘C (980 “F) (80 to 83% dissociation). Effective case depth (IO 60 HRC). 0.29 to O.-l mm (0.010 to 0.015 in.): case hardness, 67 to 72 HRC (converted from Rockwell IS-N scale)

Guidelines The fust stage of the double-stage process is the same as that for the single-stage process, except for time (see Table). The operating tcmperature in the second stage may nc the same as that in the first stage, or it ma! be increased from 550 to 565 “C ( IO20 to IO50 “F). The higher temperature increases case depth. Prior to nitriding. parts should be thoroughly cleaned ttypicall> mrith vapor degreasing) after they are hardened and tempered. Furnace Purging. After loading and sealing the furnace at the start of the nitriding cycle. air must be purged from the retort before the furnace is heated above IS0 ‘C (300 “F). Purging pre\.ents osidation of workpieces and furnace components. When ammonia is the purging atmosphere, pur_ging avotds the production of a potentially explosi\.c mixture. Nitrogen IS the preferred quenching medium. Under no circumstances should ammonia be introduced into a furnace containing air at 330 ‘C (6X “F) because of the explosion hazard. Furnaces should also be purged at the conclusion of the nitriding cycle. during the cool-down period. At this time. it is common practice to remobe an) ammonia in the retort with nitrogen. Emergency Purging. If the ammonia suppI is cut off during the nitriding cycle or a suppI! line hreaks. air can be sucked into the fumncethe greatest danger is dunng the cooling cycle. The common safety measure is an emergency purging system that pumps dry rutrogen or an oxygenfree. generated gas and maintains a safe pressure. Case Depth Control. Case depth and case hardness VW \\r;th the duration of the nitriding cycle and other process conditions. Hardness

Nominal Composition Gas Nitrided

SAE

7140

Steel AMS

6470 6475

Nitralloy

and Preliminary

C

hln

Si

G 135hI

0.35 0.42

0.55 0.55

N EZ

0.2-l 0.35

0.55 0.80

0.30 0.30 0.30 0.30

(a) Sections up IO SO mm (2. in.) in diameter.

Microstructure

Heat-Treating

3.5

of Steel / 63

gradients and case depths obtained in treating SAE 7l-lO (AhlS 6470) as a function of cycle time and nitriding conditions are indicated in an adjoining Figure. Equipment. Several designs are in common use, including the vertical retort furnace (see Figure). bell bpe movable furnace, box furnace. and tuhe retorts. hlost furnaces ‘are of the batch type. Furnace fixtures are similar in design to those used in gas carburizing. Ammonia and dissociated products can react chemically with material in retorts. fans. work baskets. and fixtures. Alloys containing a high percentage of nickel and chromium normally are used in furnace parts and fixtures (see Table). Ammonia Supply. Anhjdrous liquid ammonia (refrigerator grade. 99.98 percent NH? hy lbeight) is used.

Applications The list of applications l l

l

l

l

includes:

Aluminum containing. low-alloy steels (see Table) Medium-carbon. chromium-containing, low-alloy steels of the 4100. -l300. 5 100.6 100, 8600. 8700. and 9800 series Hot-work die steels containing 5 percent chromium. such as HI I. HI?. and HI? Lo)5 pm; surface hardness runs around 350 HV. Parts are cooled under controlled vacuum conditions. Applications. The plasma equipment shown in an adjoining Figure has been treating seat slider rails for autos for a number of years without significant technical or metallurgical problems. Applications include lowalloy, chromium-bearing steels. some plain carbon steels, and, recently, sintered P/M parts, replacing the salt bath process (see adjoining Figure). Reference I. ASM hlnols Handbook. tional. 199l.pd25

Hem Trmtitlg,

Vol 4. 10th ed., ASM Intema-

Bed Hardening

Steel parts are nitrocarburized, carburized, and carbonitrided in fluid bed hmaces. The process also is used in quenching (see article in this chapter). In heat-treating applications, a bed of dry, finely divided (80 mesh to I80 pm) particles, typically aluminum oxide, is made to behave like a liquid bj a moving gas fed upward through a diffuser or distributor into the bed of the furnace.

Characteristics Fluidized beds, using atmospheres made up of ammonia. natural gas, nitrogen, and air or similar combinations, are capable of doing low-temperature nitrocarburizing. Results are equivalent to those with conventional salt bath processes or other atmosphere processes. High-speed steel tools

72 / Heat Treater’s

Fluidized-bed

Guide

furnace

with external

heating

by electrical

resistance

oxynitrided in a fluidized bed have properties similar to those of tools treated by the more conventional gas processes. In carburizing and carbonitriding, results can be similar to those obtained with conventional ammosphere processes. In an adjoining Figure, results in treating SAE 8620 steel are compared with those obtained in gas carburizing. An effective case depth of I mm (0.04 in.) was obtained in I .5 h. Advantages of the process include: l l l l

Carbtizing is rapid because treatment temperatures are high Temperature uniformity is ensured Furnaces are tight; upward pressure of gases minimizes leakage of air Part finishes are uniform

Operating

Information

The carbon potential of the atmosphere varies with the air-to-gas ratio. For each hydrocarbon gas (typically propane, methane, or vaporized methanol) a relationship can be established. Furnaces are equipped with ports and probes to facilitate necessary measurements. Dense phase furnaces are the most widely used in heat treating. In this instance. parts are submerged in a bed of fme. solid particles held in suspension, without any particle entrainment, by a flow of gas. Several methods of heating are available, including external-resistance-heated beds (see Figure); external-combustion-heated beds, submerged-combustion

elements

Comparison of hardness profiles obtained by fluidized-bed and conventional gas carburizing. SAE 8620 steel, rehardened

from 820 “C (1510 “F)

Guidelines

Fluidized-bed

applications;

beds, intemalcombustion, tion. gas-fired beds.

Operational

gas-fired

decision

beds; and two-stage,

into the majority

of Steel

/ 73

model

intemal-combus-

Safety. As with all forms of gas heating, accepted safety

devices are incorporated

for the Heat Treatment

of today’s

furnaces.

Applications Applications of fluidized beds and those of competing processes are listed in an adjoining Figure. Note that the information includes operating temperatures.

Reference I. ASM M~mls Hmcfhok. tional. I99 I, p 43-I

Hmt Trraring. Vol 1. 10th ed., ASM lntema-

74 / Heat Treater’s

Boriding

Guide

(Boronizing)

Process

This is a thermomechanical surface hardening process which is applied to a number of ferrous materials. During boriding, the diffusion and subsequent absorption of boron atoms into the metallic lattice on the surface of workpieces form initial boron compounds, Ref I.

Characteristics The process has advantages over conventional case hardened parts. One is extremely high hardness (between 1450 and 5000 HV) with high melting points of constituent phases (see Table). Typical surface hardness values are compared with those of other treatments in an adjoining Table. In addition, a combination of high surface hardness and low surface coefftcients of the borided layer helps in combating several types of wear, i.e., adhesion, tribe-oxidation, abrasion, and surface fatigue. On the negative side, boriding techniques lack flexibility and are labor intensive, making the process less cost effective than other thermomechanical treatments, such as gas carburizing and plasma &riding. Alternative processes include gas boriding. plasma boriding. fluidized bed boriding. and multicomponent boriding. A diagram of a lluidized bed for boriding is shown in an adjoining Figure.

Typical Surface Hardness of Borided Steels Compared with Other Treatments and Hard Materials MiCl.Ob~dlless,

Material

Multicomponent

Boriding

1600 1800 1900 900 S-IO-600 630-700 900-910 6SO-1700 650-950 looo-1200 ll60-1820(30kg) 1483 (30 kg) I738 (30 kg) lS69(30kg) 2ooo 3500 4ooo 5ooo >I0000

Information

Welt-cleaned material is heated in the range of 700 to 1000 “C (I290 to 1830 “F) for I to I2 h in contact with a boronaceous solid powder, paste, liquid, or gaseous medium. In the multicomponent process, conventional boronking is followed by applying one or more metallic elements, such as ahuninum, silicon, chro-

Melting Point and Microhardness Phases Formed During Boriding Materials

Substrate Fe co

co-‘7.5 Cr

Ni

k&mm~orEV

Boride mild steel Bonded AtSI H I3 die steel Borided AtSl A2 steel Quenched steel Hardened and tempered H I3 die steel Hardened and tempered A2 die steel High-speed steel BM42 Niuicted steels Carburized low-alloy steels Hard chromium plating Cemented carbides, WC t Co AI,O, + ZrO: ceramic Alz03 t TC t ZrO, cemmic Sialon ceramic TIN -liC SIC B,C Diamond

Constituent Phases in tbe boride layer FeB Fe?B COB CozB Co3B COB CozB Co,B(‘?) Ni&3 Ni:B Ni3B

ho lccl MO

Ta

MozB MOB> Mo:Bs WzBs IiB TIBZ TiB TIB: NbB: NbB.l Ta:B

Hf zr Re

TaB: HI-& ZrB: ReB

w Ii Ti-6AI-4V Nb

of Different Boride of Different Substrate

MiCl.0hanlnCS.S

of layer, EV or kg/mm*

Melting point OF OC

1900-2100 1800-2000 I850 1500-1600 700-800 2200 (lOOg)(a) -l55O(lOOg)(a) 700-800 1600 IS00 900 1700~3-00g)(b) 1660 2330 2400-2700 2600 2500 3370

1390

2535

... . .

. ... . . .

2txxl -2100 2100 2300 -1900 2980 .

“’ 3630 -3810 3810 4170 3450 5395

3OOO(lOOgj(a) 2200

3050

5520 “’

2500 2900 2250 2700-2900

32003500 3200 3250 3040 2100

57906330 5790 5880 5500 3810

(a) IOOg load. (bj 2oOg load

Treatments

Multicomponeot boridhrg technique

Media type

61 62

Boroaluminizing Boroaluminizing

Electrolytic salt bath Pack

2

Borochromizing

Pack

2

Borosiliconizing

Pack

2

Borovanadizing

Pack

Reference

Operating

Media composition(s), wt k

Process steps investigated(a)

Substrate(s) treated

S S B-AI AI-B S B-Cr Cr-B B-Si Si-B B-V

Plain carbon steels Plain carbon steels

900( 1650) lOSO( 1920)

Plain carbon steels

Borided at 900 ( 1650) Chromized at loo0 (1830)

3-20% AlzOr in borax 8% B,C t 16% borax 974 ferroaluminum t 3%, NHJZI 5% B.&Z+ 5% KBF, t 905, Sic (Ekabor ffj 78%. ferrochrome + 20% AI?03 + 2C WC1 SB B,C t I% KBF, + 90%. SIC (Ekabor Oj IOOB Si 5% BJ t 5% KBR + 90% Sic (Ekabor U) 60%, ferrovanadium + 37% Al:01 + 3%, NH,CI

(a) S. simultaneous boriding and metallizing: B-Si. borided and then siliconized; Al-B. aluminized and then bonded

0.44 Steel I .O%-C steel

Ikmperature,

OC (OF)

900-lOOO(l650-1830) Borided at 900 ( 1650) Vanadized at 1000 ( 1830)

Guidelines Proven Applications AIS1

for Borided

Substrate material HSI

I020 10-n 1138 1042

E C2 HII HI3

Ferrous

BHI I ...

HI0

I15CrV3 4OCrMnMo7 X38CrMoV5 I X4OCrMoVS I X32CrMoV33

D2

.

s”li

-BSI

D2 L4i

BS224

02

-802

XlSSCrVMol21

Xl6SCrVMol2 56NiCrMoV7

X$k4SrY4

Materials

Diagram

of a fluidized

for the Heat Treatment

of Steel / 75

bed for boriding

Application Bushes, bolts. nozzles. conveyer tubes. base plates, runners, blades, th&d guides Gear drives, pump shafts Pins, guide nngs. gnndmg disks. bolts Casting inserts, nozzles. handles Shaft protection sleeves, mandrels Swirl elements, nozzles (for oil burners). rollen. t&s. gale plates Gate plates Clamping chucks, guide bars Bushes, press tools, plates. mandrels, punches, dies Drawing dies, eje,cton: guides, insen pins Gate platqs,,ben,dmg*es ~h~i~Z%~~~~$ZZlrL~wer dies and matrices for hot forming, disks injection molding dies, fillers. upper and lower dies and matrices for hot forming Threaded rollers, shaping and pressing rollers. pressing dies and matrices Engraving rollers Straightening mllerj Press and drawing matrices. mandrels. liners, dies, necking rings Drawing dies. rollers for cold mills Extrusion dies. holts. casting inserts, $%;$$;;~~~~d en&ving

dies

rollers. bushes, drawing dies,

Microstructure of the case of a borochromtitanized tion alloy steel

construc-

Es2100

4140 4150 4317

708A42 (EnlW -708A42 (CDS-15) .

X5OCrMnNiV229 42CrMd SOCrMo4 I7CrNihlo6

5115

16MnCrS

6152

5CCrV-l

302 316

302825 (EnSgA) -3 16s I6

05580 410 420

4lOS21 (En56A) -42OS45 (En56D)

X I2CrNi I88

exuuder barrels. non-Rturn valves Nozzle base plates Bevel gears. screw and wheel gears, shafts, chain components Helical gear wheels, guide bars, guiding collmlns Thrust plates. clamping devices. valve sprin&. spring c&t&s Screw cases, bushes

XSCrNiMo I8 IO Perforated or slotted hole screens. parts for the textile and tubber industries GXIOCrNiMol89 Valve plugs, parts forthe textileand chemical industries Valve components, fittings XIOCrl3 XjOCrl3

X3SCrMo I7 Gray and ductile cast iron

Valve components. plunger rods. fittings. guides, parts for chemical plants Shafts, spmdles, valves Parts for textile machinery, mandrels. molds, sleeves

mium. vanadium, or titanium (see Table). The operating temperature ranges from 850 to 1050 “C (1560 to 1920 “F). It is a two-step process: I. Boding by conventional methods, such as pack, paste, and electrolpic salt bath techniques 2. Dillitsing me.taliic elements through the powder mixture or borax-based melt into the borided surfaces. With the pack method, sintering of particles is avoided by passing argon or hydrogen into the reaction chamber. The mierosttucture of a borocbromtitanized alloy steel is shown in an adjoining Figure..

Quenching

and Tempering.

Borided

steels are quenched

in air, oil,

salt baths, and aqueous Polymers.

Applications Marty ferrous materials can be borided, including structural steels, tool steels, stainless steels, cast steels, Armco CP iron, gay and ductile irons,

and ferrous P/M materials. Proven applications are shown in an adjoining Table. Air-hardening steels can be simultaneously hardened and borided; waterhardening steels are not borided because of the susceptibility of the boride layer to thermal shock. Also excluded are resulfurized and leaded steels (because of tendencies toward case spalling and case cracking), and nitrided steels (due to their sensitivity to cracking).

Reference I. ASM Memls Ha&book, tional. 1991, p 137

Hear Trt~~tir~g. Vol 3, 10th ed., ASM Intema-

76 / Heat Treater’s

Laser

Guide

Surface

Hardening austenitizing temperatures without unduly affecting the bulk temperature of the workpiece. fn laser surface hardening, as in the electron beam process and high frequency, pulse hardening methods (see article on these self-quenching processes in this chapter), a quenching medium is not needed. Self-quenching occurs when the cold interior of the workpiece is a large enough heat sink to quench the hot surface by heat conduction fast enough to allow the formation of martensite on the surface.

A laser heats the surface of a part to its austenitic temperature. The laser beam is a beam of light, is easily controlled, requires no vacuum, and does not generate combustion products. However, complex optics are required, and coatings are required on surfaces to be hardened because of the ION infrared absorption of the steel, Ref I.

Characteristics Lasers are effective in selective hardening of wear and fatigue prone areas of irregularly shaped machine componems such as camshafts and crankshafts. Distortion is low. Lasers are not efficient from an energy utilizaGon standpoint. Energy efficiency may be as low as IO percem.

Operating

Applications More than 50 applications of the process have been reponed. Materials include plain carbon steels (I 010. 1050, 1070). alloy steels (4340.52 100). tool steels, and cast irons (gray, ductile, and malleable types). Reported case depths on steels run from 250 10 750 pm; those on cast irons about 1000 pm.

Information

This surface hardening process is not fundamentally different from conventional through hardening of ferrous materials. In both instances, increased hardness and strength are obtained by quenching the material from the austenite region to form hard martensne. Wilh laser hardening, however, only a thin surface layer is healed to the austenitizing temperature prior to quenching, leaving the interior of the workpiece essentially unaffected. Because ferrous materials are fairly good conductors of heat, ir is necessary IO use very intense heat fluxes to heat the surface layer to

Electron

Beam

Reference I. ASM hlerals Handbook, Hevat Trtvaring, Vol 4. 10th ed., ASM tional, 199 I, p 286

Intema-

Hardening

This is a shon surface hardening process for martensitically hardenable ferrous malerials. Energy for austenilizing is provided by electron beams, Ref I.

(see article on process in this chapter). To accommodate self-quenching, workpiece thickness should be at least 5 LO IO times the depth of austenitizing.

Characteristics

Applications Carbon, alloy, and 1001 steel applications

are listed in the adjoining

Table.

Extremely low hardening distortion and relatively low energy consumption give the metallurgist an alternative to conventional hardening processes In some instances. the technique is competitive with case hardening and induction hardening processes.

Reference

Operating

I. ASM hl.erals Handbook, Heat Treoring, Vol 4. 10th ed., ASM Intemational. 1991. p 297

Information

Typical hardening depths range from 0. I to I.5 mm (0.004 to 0.006 in.). Rapid cooling of austenite to martensite occurs mrough self-quenching

Steels Commonly Material UNS No.

Used in Electron

Beam Hardening

C

Si

Carbon and low alloy 4140 GA 1400 12 CrMo 1 1340 Cl3400 42MnV7 Exloo GS2986 IOOCr6 1015 G10150 c IS 1045 GlOjSO C-IS I070 Gl0700 Ck 67 SSCrl SOCrV J

0.38.O.-IS 0.38-0.1s 0.9s- I .os 0.17-0.19 0.42-0.50 0.650.72 0.52-0.60 0.47.0.59

0.17-0.37 0.17-0.37 0.17-0.37 0.17-0.37 0.17-0.37 0 25-0.50 0.17-0.37 0 4 max

I 60-I .90 0.20-0.45 0.35-0.65 0.50-0.80 0.60-0.80 050.8 0.7-1.1

Tool steels T31502 02 WI T72301

0.85-0.95 0.95-1.04

0.15-0.35 0.15-0.30

1.80-2.00 0.03Omax 0.030max 0.15-0.25 0.02Omsx 0.020max

AlSl

DWa)

9OMnV8 c IOOWI

(a) Deutsche tndusu-ie-Normen. ihj 0.25 max Cu

Mn

Applications P

S

Composition, ~1% hlo Cr

0.50-0.80 0.035max 0.035 max 0 90-I 20 O.lS-0.25 0.035 mx 0.027 mm 0.040 max 0.040 max 0.035 mar 0.035 max 0.035

0.035 maa 0.020 max 0.040 max 0.040 max 0.035 max _. 0.03 max

0.30 ma\ O.lOmax I .30-I .6S 0.50 mas O.lOma 0.50 max O.lOma 0.35 m;Lx 0.2-0s 0.9-l 1 ___ 0.20max

___ ,._

Ni

v

Al

cu

Ti

0.30max 0.30mcu 0.30max 0.30mrtv 0.30maK 0.3Smax 0.3max

0.06max 0.07-0.12

,,. __. _..

,,_

___

__. 0.10 max(hj

0.07-0.12

0.25 ___

_..

___ 0.02-0.05

0.35 0.3 max

0.015 0. I-O.2 .

.

Steel

Quenching

Technology

Introduction “Quenching is one of the least understood of the various heat treating technologies,” in the words of a world authority on the subject, George E. Totten of Union Carbide Chemical & Plastics Co., Inc. Other dimensions of the problem are identified in the follouing quotes from other experts: l

l

l

“Quenching is critically important, but often the neglected part of heat treating.” “Quenching is the most critical part of the hardening process... [it] must be designed to extract heat from the hot horkpiece at a rate required to produce the desired microstructure, hardness, and residual stresses.” “Distortion is perhaps one of the biggest problems in heat treating... little information on the subject has been published.”

The subject was introduced in the previous chapter by two articles on the subject: “Causes of Distortion and Cracking during Quenching” and “Stress Relief Heat Treating of Steel.” In this section, the topic is surveyed in depth in eight articles on conventional quenching processes: l l l l l l l l

Air quenching Water quenching Oil quenching Polymer quenching Molten salt quenching Brine quenching Caustic quenching Gas quenching

l l l l l l l l l l l l l

Austempering hlartempering Isothermal quenching Aus-bay quenching Spray quenching Fop quenching Cold die quenching Press quenching Vacuum quenching fluidized bed quenching HIP quenching CUtrasonic quenching Quenching in electric and magnetic fields Quenching flame and induction hardened parts Self-quenching processing-electron beam hardening, and high frequency pulse hardening

laser hardening,

Process

of Process

Air, a gas high in nitrogen,

cools by extended

vapor phase cooling.

Information

As with other quenchants. heat transfer rates are dependent on flow rate-in this instance, flow rate of air past the hot part (see Figure). Cooling can be speeded up by increasing the velocity of air 110~. but the accelerated rate is not sufficient to quench harden man) steels. The ability of air to harden plain carbon steels drops dramatically with increasing carbon content (see Figure).

Application

l

methods of quenching are discussed in articles:

I. George E. Town. preface to AShl Conference Proceedings, “Quenching and Distortion Control.” ASM International, ‘92 2. Totten et al, “Handbook of Quenchants and Quenching Technology,” ASM International. ‘93

Air is the oldest most common. least expensive quenching medium, Ref I.

Operating

l

I7 alternative

References

Air Quenching Characteristics

In addition.

Range

Air is used in quenching steel and several nonferrous metals. The comparative heat transfer coefficients of different metals as a function of surface temperature are shoun in an adjoining Figure. To get optimal hardness, it is often necessary to use a more actike quenching medium. such as brine or oil.

Reference I. Totten et al, Handbook oj Qwttclrottts ASM International. 1993

md Qutwclriny Teclrtrolog~:

Heat transfer coefficients face temperature

for air cooling as a function of sur-

78 / Heat Treater’s

Guide

Hardness values obtained with different quenching media

Cooling capacities of still and compressed air

Water

Quenching

Process

Like air, water is an old, common, inexpensive quenchant (Ref I). It is applied in several ways: in straight, immersion quenching; in a special, double-step, hot water quenching process; and in conjunction with polymer quenchants and with brine quenchants.

Characteristics

of Process

Water, especially cold water, is one of the most severe available. Vigorously agitated water produces a cooling the maximum with liquid quenchants (Ref 2). As water the vapor phase is prolonged and the maximum rate sharply (see Figure).

Operating

quenching media rate approaching temperature rises, of cooling drops

Information

l l

Maintaining water at a low temperature through cooling Vigorous agitation to disperse the vapor blanket Addition of an organic salt (see Brine Quenching)

Double-step, hot water quenching ing of steel wire. It consists of: l

l

Range

Water is the choice where a severe quench does not result in excessive distortion and cracking. Use generally is restricted to quenching simple, symmetrical parts made of shallow hardening grades of steel. Other applications include austenitic stainless steels and other metals that have been solution treated at elevated temperatures.

Effect of temperature

Generally, good results are obtained in straight immersion quenching by maintaining water temperatures in the range of I5 to 25 “C (60 to 75 “F) and by agitating water to velocities greater than 0.25 m/s (50 ft/min). Water temperature, agitation of water, and amount of contamination in the water must be controlled. The comparative cooling properties of hard water and distilled water are indicated in an adjoining Figure. The detrimental effect of temperature dependence and vapor phase stability can be minimized (Ref 3) by: l

Application

is a possible alternative

to lead patent-

Heating wire to 920 to 950 “C ( 1690 to 1710 “F) and immersing boiling hot water for an appropriate time Removing wire from water and air cooling (Ref I)

into

Source:

ES. Houghton

&

on quenching Co.

properties

of water.

Steel Quenching Technology / 79 Cooling curves for hard water and distilled water

References I. Totten et al., Handbook of Quenchanrs ASM International, 1993

Oil Quenching

and Quenching

Technology,

Process

AU modem quenching oils are based on mineral oil, usually paraffin based, and do not contain fatty oils. Usage of oils opens up a number of options for the heat treater: l l l

l

l

Normal-speed oil for treating steels high in hardenability Medium-speed oils for medium hardenability steels High-speed oils for treating low hardenability steels and for other applications Hot oil quenching (also called marquenching or martempering) provides another option Water-washable quenching oils: for removing oils on treated parts with plain water

Characteristics

of Process

Oils are characterized in various ways, depending upon operating requirements. Quenching speed and operating temperature are among these considerations. The importance of quenching speed is that it influences hardness and depth of hardening. Cooling rate curves for normal-, medium-, and highspeed quenching oils are shown in an adjoining Figure (Ref I). Cooling curves for different quenchants are given in an adjoining Figure (Ref 7). Almost all quenching oils produce lower quenching rates than water or brine solutions, but they remove heat from workpieces more uniformly than water normally does, meaning less likelihood of distortion and cracking (Ref 3). Temperature of operation is important because it influences: l l l l

2. ASM Metals Handbook, Heat Treating, Vol 4, 10th ed.. ASM lntemational. 1991 3. Houghron on Quenching, E.F. Houghton & Co., Valley Forge, PA

Oil life Quenching speed Viscosity of oil Distortion of workpieces

Effect of temperature on quenching shown in an adjoining Figure (Ref I).

speed for a hot quenching

oil is

Changes in viscosity can indicate oxidation and thermal degradation, or the presence of contaminants. Ln general, viscosity goes up as an oil degrades and can result in changes in quenching speed. Flash point, another consideration, is the lowest temperature at which oil vapors ignite in the presence of an ignition source; it is important because

Cooling rate curves for quenching oils. Source: & co.

E.F. Houghton

80 / Heat Treater’s

Guide

Cooling rates for different quenchants

Effect of temperature on quenching speed of hot oil. Source:

Characteristics

of Quenching

Oils

E.F. Houghton&Co.

‘Qpe ofoil

Bath temperature “C “F

FlZL5b point OC OF

Con\rntionaI Accelerated hlarquenching

~65 dispersed alloy carbides, exists for high-alloy steels. It has been found that stage I of tempering is often preceded by the redistribution of carbon atoms. called autotempering or quench tempering, during quenching and/or holding at room temperature (Ref 5). Other structural changes take place because of carbon atom rearrangement preceding the classical stage I of tempering (Ref 6,7). Dimensional Changes. Martensite transformation is associated with an increase in volume. During 1empering. martensite decomposes into a mixture of ferrite and cementite with a resultant decrease in volume as tempering temperature increases. Because a 100% martensitic structure after quenching cannot always be assumed, volume may not continuous11 decrease with increasing tempering temperature. The retained austenite in plain carbon steels and low-alloy steels transforms to bainite with an increase in volume, in stage II of tempering. When certain alloy steels are tempered. a precipitation of finely distributed allo) carbides occurs. along with an increase in hardness, called secondq hardness, and an increase in volume. With the precipitation of allo) carbides. the MS temperature (temperature at which martensite starts to foml from austenite upon cooling) of the retained austenite will increase and transform to martensite during cooling from the tempering temperature. Tempering Temperature. Several empirical relationships have been made between the tensile strength and hardness of tempered steels. The measurement of hardness commonI> is used to evaluate the response of a steel to tempering. An adjoining Figure shous the effect of tempering

Effect of tempering

temperature

of 1050 steel that was forged heat: 0.52% C, 0.93% Mn

on room-temperature

to 38 mm (1 SO in.) in diameter,

mechanical then water

Processes/Technology

/ 97

temperature on hardness, tensile and yield strengths, elongation, and reduction in area of a plain carbon steel (AISI 1050) held at temperature for I h. It can be seen that both room-temperature hardness and strength decrease as the tempering temperature is increased. Ductility at ambient temperatures. measured by either elongation or reduction in area, increases with tempering temperature. hlost medium-allo) steels exhibit a response to tempering similar to that of carbon steels. The change in mechanical properties with tempering temperature for 4330 steel is shorn n in an adjoining Figure. There is no decrease in ductility in the temperature range of tempered martensite embrittlement. or ThIE (also known as 160 “C [SO0 “F] embrittlsment or one-step temper embrittlement) because the tensile tests are performed on smooth. round specimens at relatively low strain rates. Home\sr. in impact loading. catastrophic failure may result when alloy steel is tempered in the tempered martensite embrittlement range (260 to 370 “C. or SO0 to 700 “F). H’hereas elongation and reduction in area increase continuously with tempering temperature. toughness. as measured by a notched-bar impact test. \ aries uith tempering temperature for most steels, as shown in an adjoining Figure. Tempering at temperatures from 260 to 320 “C (500 to 610 “F) decreases impact energy to a value below that obtained at about IS0 “C (300 “F). Above 320 “C (610 “F), impact energy again increases mith increasing tempering temperature. Both plain carbon and alloy steels respond IO tempering in this manner. The phenomenon of impact energy centered around 300 YY (570 ‘Fj is called tempered martensite embrittlement (ThlE) or 160 “C (SO0 “F) embrittlement. Tempering Time. The difision of carbon and alloying elements necessarj for the formation of carbides is temperature and time dependent. The effect of tempering time on the hardness of a 0.828 C steel tempered at various temperatures is shown in an adjoining Figure. Changes in hardness are approximateI) linear over a large portion of the time range when the time is presented on a logarithmic scale. Rapid changes in room temperature hardness occur at the start of tempering in times less than IO s. Less rapid. but still large. changes in hardness occur in times from I to IO min. and smaller changes occur in times from I IO 2 h. For consistency and less dependency on variations in time. components generally are tempered for I to 2 h. The levels of hardness produced by very short tempering cycles,

properties

of 1050 steel. Properties

quenched

and tempered

at various

summarized temperatures.

are for one heat Composition of

98 / Heat Treater’s

Guide

Effect of tempering temperature on the mechanical properties of oilquenched 4340 steel bar. Single-heat results: ladle composition, 0.41% C. 0.67% Mn, 0.023% P, 0.018% S, 0.26% Si, 1.77% Ni, 0.78% Cr, 0.26% MO; grain size, ASTM 6 to 8; critical pointsAc,, 770°C (1420”F);Ar,, 475°C (890°F); Ar,, 380°C (720 “F); treatment, normalized at 870 “C (1600 “F), reheated to 800 “C (1475 “F), quenched in agitated oil; cross section, 13.46 mm (0.530 in.) diam; round treated, 12.83 mm (0.505 in.) diam; round tested; as-quenched hardness, 601 HB. Source: Ref 8

Notch toughness as a function of tempering temperature for 4140 (UNS G41400) ultrahigh-strength steel tempered 1 h

Alloy Content

Carbon Content

The main purpose of adding alloying elements to steel is to increase hardenability (capability to form martensite upon quenching from above its critical temperature). The genera) effect of alloying elements on tempering is a retardation of the rate of softening, especially at the higher tempering temperatures. Thus. to reach a given hardness in a given period of time, alloy steels require higher tempering temperatures than do carbon steels. Alloying elements can be characterized as carbide forming or non-carbide forming. Elements such as nickel, silicon, aluminum. and manganese, which have little or no tendency to occur in the carbide phase, remain essentially in solution in the ferrite and have only a minor effect on tempered hardness. The carbide forming elements (chromium, molybdenum. tungsten, vanadium, tantalum. niobium, and titanium) retard the softening process by the formation of alloy carbides. Strong carbide-forming elements such as chromium, molybdenum, and vanadium are most effective in increasing hardness at higher temperatures above 205 “C (100 “F). Silicon was found to be most effective in increasing hardness at 3 I5 “C (600 “Fj. The increase in hardness caused by phosphorus, nickel. and silicon can be attributed to solid-solution strengthening. Manganese is more effective in increasing hardness at higher tempering temperatures. The carbide-forming elements retard coaJescence of cementite during tempering and foml numerous small carbide particles. Under certain conditions, such as with highly alloyed steels, hardness may actually increase. This effect, mentioned previously. is known as secondary hardening. Other Alloying Effects. In addition to ease of hardening and secondary hardening. alloying elements produce a number of other effects. The higher tempering temperatures used for alloy steels presumably permit greater relaxation of residual stresses and improve properties. Furthermore, the hardenability of alloy steels requires use of a less drastic quench so that quench cracking is minimized. However, higher hardenability steels are prone to quench cracking if the quenching rate is too severe. The higher hardenability of alloy steels may also permit the use of lower carbon content to achieve a given strength level but with improved ductility and toughness. Residual Elements. The elements that are known to cause embrittlement are tin. phosphorus. antimony, and arsenic.

The principal effect of carbon content is on as-quenched hardness. An adjoining Figure shows the relationship between carbon content and the maximum hardness that can be obtained upon quenching. The relative difference in hardness compared with as-quenched hardness is retained after tempering. An adjoining Figure shows the combined effect of time. temperature, and carbon content on the hardness of three carbon-molybdenum steels of different carbon contents. Another Figure shows the hardness of these steels after tempering for I h. as a function of tempering temperature. The effect of carbon content is evident.

furnaces or in molten salt. hot oil. or molten metal baths. The selection of furnace type depends primarily on number and size of parts and on desired temperature. Temperature ranges. most likely reasons for use. and fundamental problems associated with four types of equipment are given in an adjoining Table. Selective tempering techniques ;LTeused to soften specific areas of fully hardened parts or to temper areas that were selectively hardened previously. The purpose of this treatment is to improve machinability, toughness, or resistance to quench cracking in the selected zone.

such as in induction tempering, would be quite sensitive to both the temperature achieved and the time at temperature. By the use of an empirical tempering parameter developed by Holloman and Jaffe (Ref IO), the approximate hardnesses of quenched and tempered low- and medium-alloy steels can be predicted. Reasonably good correlations are obtained except when significant amounts of retained austenite are present. Cooling Rate. Another factor that can affect the properties of a steel is the cooling rate from the tempering temperature. Although tensile properties are not affected by cooling rate. toughness (as measured by notchedbar impact testing) can be decreased if the steel is cooled slowly through the temperature range from 375 to 575 “C (705 to 1065 OF). especially in steels that contain carbide-forming elements. Elongation and reduction in area may be affected also. This phenomenon is called temper embrittlement.

Tempering Procedures Bulk processing may be done in convection

Tempering

Effect of time at four tempering temperatures on room-temperature

Processes/Technology

/ 99

hardness of quenched 0.82% C steel. Note nearly straight lines

on logarithmic time scale. Source: Ref 9

Relationship between carbon content and room-temperature hardness for steels comprising 99.9% untempered martensite

Temperature Ranges and General Conditions Four Types of Tempering

PP of

Temperature range OC OF

equipment

Comection furnace

SO-750

Salt bath

l6O-7SO 320. I380

I70- I380

Oil hath

390

>735

of Use for

Service conditions For large volumes of nearly common parts: variable loads m&e control of lemperattw moredifficul~ Rapid. uniform heating; low to medium volume; should not be used for parts whose configurations make them hard toclean Good if long exposure is desired; special ventilation and fire control are required Very rapid heating: special fixhning is reauired (high densiw)

For certain steels, the tempering mechanism is enhanced by cyclic healing and cooling. A particularly important procedure employs cycles between subzero temperatures and the tempering temperature to increase the transformation of retained austenite. The term used for this procedure. multiple tempering, is also applied to procedures that use intermediate thermal cycles to soften parts for straightening prior to tempering.

Cracking Induction and flame tempering are the most commonly used seleclive techniques because of their controllable local heating capabilities. Immersion of selected areas in molten salt or molten metal is an alternative. but some control is sacriliced. Special processes that provide specitic properties. such as those obtained in steam treating or the use of protective atmospheres. are available.

in Processing

Because of their carbon or alloy contents, some steels are likely to crack if they are permitted to cool to room temperature during or immediately following the quenching operation. Causes include high tensile residual stresses generated during quenching due to thermal gradients. abrupt changes in section thickness, decarburization, or other hardenability gradients. Another potential source is cracking due to quenchant contamination and the subsequent change in quenching severity.

100 / Heat Treater’s

Guide

Accordingly. for carbon steels containing more than 0.4% C and alloy sleek containing more than 0.35% C. transfer of parts to tempering furnaces hefore they cool to below 100 to IS0 “C (210 LO 300 “F) is recommended. Alternately, quenching oil may he used in tempering operation (martempering), or 10 avoid cooling below I25 “C (255 “F). Steels that are known to be sensitive IC) this type of cracking include 1060. 1090. 1340, 1063.4 I SO. 3340,52 IOO,6 I SO. 8650, and 9850. Other carbon and alloy steels generally are less sensitive to Uris type of delayed quench cracking but may crack as a result of part configuranon or surface defects. These steels include 1030. 1050. I I-II. I I-L!. -W7.-ll32. -I I10.4640.8632.8710. and 9840. Some steels, such as 1020. 1038, I IX. 1130. 5 130. and 8630. are not sensitive. Before being lempered. parts should be quenched to room temperature to ensure the transformation of most of the austenhe to martensite and to

Effect of tempering time at six temperatures on room-temaerature hardness of carbon-molybdenum steels with differznt carbon contents but with prior martensitic structures

achieve maximum as-quenched hardness. Austenite retained in low-alloy steels will. upon healing for tempering, transform to an intermediate structure. reducing overall hardness. However. in medium- to high-alloy steels containing austenite-stabilizing elements (nickel. for example). retained austcnite may transform LOmartensile upon cooling From tempering, and such steels may require additional tempering (double tempering) for the relief of transformation stresses.

Temper Embrittlement When carbon or low-alloy steels are cooled slowly from tempering ahove 575 ‘C ( 1065 “F) or are tempered for extended times between 375 and 575 “C (70s and 1065 “F). a loss in toughness occurs that manifests itself in reduced notched-bar impact strength compared IO that resulting from normal tempering cycles and relativelv fast cooling rates. The cause of temper embrinlement is belkved 10 be the precipitation of compounds containing trace elements such as tin, arsenic. antimony, and phosphorus, along with chromium and/or manganese. Although manganese and chromium cannot he restricted. a reduction of the other elements and quenching from ahove 575 “C (I065 “F) are the most effecuve remedies for this type of embrittlement. Steels that have been embrittled because of temper embrinlement can he de-embritkd by heating 10 about 575 ‘C ( 1065 “F). holding a few minutes. then cooling or quenching rapidly. The time for de-embrittlemen~ depends on the alloying elements presenr and the temperature of reheating (Ref I I).

Blue Brittleness The heating of plain carbon steels or some alloy steels to the temperature range of 230 to 370 ‘C (-US to 700 “F) ma,y.result in increased tensile and yield strength. as well as decreased ducuhty and impact strength. This embrittling phenomenon is caused by precipitation hardening and is called blue brittleness because it occurs within the blue heat range. If susceptible steels are heated H ithin the 230 IO 370 “C (US to 700 “F) range. they may be embrittled and thus should not be used in pru~s suhjrcted to impact loads.

Tempered

Martensite

Embrittlement

Both inrergranular (Ref I3- IS) and transgranular fracture modes may be observed in tempered martensite embrittlement (Ref 13, 16). The comhination of the segregation of impurities such as phosphorus to the austenitic grain boundaries during austenitizing and the formation of cementite at prior austenitic grain boundaries during tempering are responsible.

Effect of carbon content and tempering temperature on room-temperature hardness of three molybdenum steels. Tempering time: 1 h at temperature

Tempering

There is a loss in impact toughness for steels tempered in the temperature range of 250 to 300 “C (380 to 570 OF). Steels with lower phosphorus content have superior impact properties than steels with a higher phosphorus level. Also. impact toughness decreases with increasing carbon content (Ref 17). Generally, with steels containing either potent carbide forms such as chromium or other impurities that make them susceptible to tempered martensite embrittlement, tempering between 200 to 370 “C (390 to 700 “F) should be avoided.

Hydrogen

Embrittlement

The selection of tempering temperature and the resultant hardness or plasticity must include the consideration of the potential problem of hydrogen embrittlement under these conditions: the part will be exposed to hydrogen through electroplating. phosphating, or other means. or where environmental conditions will cause the cathodic absorption of hydrogen during service. Generally, the restricted notch ductilit) of steels with hardnesses above 10 HRC presents ideal conditions for the development of stress concentrations in parts containing notches or defects that would. in the presence of relatively low hydrogen concentrations. lead to failure at stresses far below the nominal tensile strength of the material. Such parts should be tempered to hardness below 10 HRC if they are to be subjected to relatively high stresses and probable exposure to hydrogen.

References I. C.S. Roberts, B.L. Auerbach. and M. Cohen, The Mechanism and Kinetics of the Fit Stage of Tempering. Trarrs. ASM, Vol35. 1953, p 576-60-I 2. B.S. Lement. B.L. Auerbach. and hf. Cohen, Microstructural Changes on Tempering iron Carbon Alloys, Trarrs. ASM. Vol46. 19%. p 85 l-88 I 3. F.E. Werner. B.L. Auerbach. and M. Cohen, TheTempering of iron Carbon Martensitic Crystals. Trans. ASI%~.Vol-19. 1957. p 823-841

Martempering

tional process.

transformation

(b) Mattempering.

/ 101

4. G.R. Speich. Tempered Ferrous hlartensitic Structures. in Mm/s Huruibook. Vol8,8th ed., American Society for Metals, 1973, p 202-204 5. G.R. Speich and WC. Leslie. Tempering of Steel, Merd. Trms., Vol 3, 197’. p l@l3-1054 6. S. Nagakwra. Y. Hirotsu. hl. Kusunoki. T Suzuki, and Y. Nakarnura, C~stallog~aphic Stud> of the Tempering of hlartensitic Carbon Steel by Electron hlkroscopy and Diffraction. hfe!o/l. Trorrs. A, Vol I4A. 1983, p 1025-1031 7. G. Krauss. Tempering and Structural Change in Ferrous Martensitic Struttures. in Ptme Insrrlrtt,u~nroriorls in Fertms Allop, A.R. Marder and J.I. Goldstein. Ed., TMS-AIhlE. 198-l. p 101-123 8. Modem Sleek cm/ Ttreir Propenies. Handbook 3757.7th ed., Bethlehem Steel Corporation, 1972 9. EC. Bain and H.W. Paston. Altq\ing Ekarrrm in Steel. Anlerican Society for hletds, 1966, p 185, 197 IO. J.H. Holloman and L.D. Jaffe. Tie-Temperature Relations in Tempering Steels, Trans. A/ME, Vol 162. 1945, p 223-249 I I B.J. Schulz. Ph.D. thesis. University of Pennsylvania. 1972 I?. T. lnoue, K. Yamamoto. and S. Seki;ieuchi. Trms. /ml Srrel Insr. Jp., Vol I-l. 1972. p 372 13. J.P. hlaterko~sski and G. Krauss. Tempered hlartensitic Embrittlement in SAE -tNO Steel, hferd. Trczrrs. 4. Vol IOA. 1979. p 1643-1651 I-4. SK. Bane@. C.T. hlcMahon. Jr., and H.C. Feng. lnter~ular Fracture in 4340 Steel Types: Effects of Impurities and Hydrogen, Me&l. Trms. A, Vol9A. 1978. p 737-347 IS. C.L. Briant and S.K. Banerji. Tempered Martensite Embrittlement in Phosphorus Doped Steels. Alrrtrll. Trms. A. Vol I OA, 1979, p l729- I736 16. G. Thomas, Retained Austenite and Tempered Martensite Embrittlement, AlemIl. Trms. .4, Vol 9A, 1978. p 439150 17. F. Zia Ebrahimi and G. Krauss. hlechanisna of Tempered Martensitic Embrittlement in h,ledium Carbon Steels, .4crcl h!eerul/., Vol 32 (No. IO). 198-&p 1767-1777

of Steel

The process entails an interrupted quench from the austenitizing temperature of certain alloy, cast. tool, and stainless steels. Cooling is delq,ed just above martensitic transformation for the lime needed to eyuahze temperature throughout a part, for the purpose of minimizing distortion.

Time-temperature

Processee/Technology

diagrams with superimposed (c) Modified

mat-tempering

cracking. and residual stress. The resulting microsuucture is primarily martcnsitic. and is unvmperrd and brittle. Differences bet\teen conventional quenching and martempering (aka marquenching) are shown in an adjoining Figure (see a and b).

cooling curves showing quenching

and tempering. (a) Conven-

102 / Heat Treater’s

Mechanical

Guide

Properties

of 1095 Steel Heat Treated by Two Methods

Specimen number

Heat treatment

I

Water quench and temper

3 3 4

Water quench and temper Martemper and temper Martemper and temper

Eardoess, ERC

J

Impact enemy ft. Ibf

53.0 52.5 53.0 52.8

16 19 38 33

12 II 28 24

Eloogstion(a),

40

0 0 0 0

(a) In 25 mm or I in.

Marquenching steps: l

l

l

of wrought

steel and cast iron consists of the following

Cooling curves for 1045 steel cylinders quenched in salt, water, and oil. Thermocouples were located at centers of specimens.

Quenching from the austenitizing temperature into a hot fluid medium (oil, molten salt. molten metal, or a fluidized particle bed) at a temperature usually above the martensitic range (M, point) Holding in the quenching medium until the temperature throughout a part is uniform Cooling. usually in air, at a moderate rate to prevent large differences between temperatures on the outside and center of a section

During cooling to room temperature. the formation of martensite throughout a part is fairly uniform. which avoids excessive residual stresses. When the still-hot part is removed from the bath. it is easy to straighten or to form, and will hold its shape on subsequent cooling in a fixture, or in air cooling after removal from a forming die. Following marquenching, parts are tempered in the same manner as conventionally quenched parts. The time lapse between martempering and tempering is not so critical as it is in conventional quenching and tempering operations.

Advantages

of Martempering

Properties of steel treated in conventional water quenching and tempering and steel treated in martempering are compared in an adjoining Table. In martempering residual stresses are lower than those developed in conventional quenching because the greatest thermal variations come while the steel is still in its relatively plastic austenitic condition and because final transformation and thermal changes occur throughout a part at essentially the same time. Other advantages of the process: l l

l

l

l

Susceptibility to cracking is reduced or eliminated When the austenitizing bath is a neutral salt and is controlled by the addition of methane or by proprietary rectifiers to maintain its neutrality. parts are protected with a residual coating of neutral salt until they are immersed in the marquench bath Problems with pollution and tire hazards are greatly reduced if nitratenitrite salts are used. rather than marquenching oils Quenching severity of molten salt is greatly enhanced by agitation and by water additions to the bath Martempering often eliminates the need for quenching fixtures. which are required to minimize distortion in comentional quenching

Modified

Martempering

The only difference between this process and standard martempering is the temperature of the quenching bath-it is below that of the his pointwhich increases the severity of the quench (see c in Figure cited previously). This capability is important for steels with lower hardenabilitj that require faster cooling to get greater depth of hardness. When hot oil is used, the typical martempering temperature in this instance is I75 “C (34.5 “F). By comparison, molten nitrate-nitrite salt baths with water additions and agitation are effective at temperatures as low as I75 “C (345 “F). The molten salt method has some metallurgical and operational advantages.

Martempering

Media

Molten salt and hot oil are widely used. Operating temperature is the most common deciding factor in choosing between salt and oil. For oil, the upper temperature is 205 “C (400 “F). Temperatures up IO 230 “C (445 “F) are an occasional exception. The range for salt is 160 to 400 “C (320 to 750 “F). Composition and Cooling Power of Salt. A commonly used salt contains SO to 60% potassium nitrate, 37 to 50% sodium nitrite, and 0 to IO%, sodium nitrate. This salt’s melting point is approximately I40 “C (285 “F); its working range is I65 to 540 “C (330 to 1000 “F). Salts with a higher melting point (they cost less than the one just described) can be used to get higher operating temperatures. Their composition: 40 to SO8 potassium nitrate. 0 to 30% sodium nitrite, and 20 to 60% sodium nitrate. The cooling power of agitated salt at 205 “C (400 “F) is about the same as that of agitated oil in conventional oil quenching. Water additions increase the cooling power of salt. as indicated by cooling curves in an adjoining Figure and hardness values in a second Figure, in which the cooling power of water is compared with that of water and three types of oil. Salt VS. Oil. Advantages of salt include the following: l l

l

Changes in viscosity are slight over a wide temperature range Salt retains its chermcal stability. Replenishment. usually, is needed only to replace dragout losses Salt is easily washed from work u ith plain water

Disadvantages, l l

salt vs. oil include the following:

Minimum operating temperature of salt is 160 “C (320 “F) Quenching from cyanide-based carburizing salt is hazardous because of possible explosion: explosion and splatter can occur if wet or oily parts

Tempering

Processes/Technology

/ 103

Effects of quenchant and agitation on hardness of 1046 steel

Physical of Steel

Properties

of Two Oils Used for Martempering Value, for oil with operating temperafurebf 95 to ISO~C 150 to 230 T (200 to 300 T)(a) (300 to 45oT)

f%shpoin~(min).“C(“F) Fire pcin~ (min). “C (“F) Vwosity. SUS, at: 38”C(IOO°F) loo”C(210°~ 150”C(300”R 17s”c(3so”F) 20.5 “C (400 OF) 230 “C (-IS0 “I3 Viscosity index (min) Acid number Faq -oil coment C&on residue

Color (a)Temperature

210~110) 2-u f-170) 23S-575 SOS-S I 36.5-37.5

9s 0.00 None 0.05 Optional

175 (525) 310(59S)

Oils For Martempering Properties of two commonly used oils are listed in an adjoining Table. Compounded for the process, they provide higher rates of cooling than conventional oils during the initial stage of quenching. At temperatures between 95 to 230 “C (205 to 445 “F) quenching oil requires special handling. It must be maintained under a protective atmosphere (reducing or neutralj to prolong its life. Exposure to air at elevated temperatures speeds up the deterioration of oil. For every IO “C above 60 “C i I8 above I30 “F) the oxidation rate approximately doubles, causing the formation of sludge and acid, which can affect the hardness and color of workpieces. Oil life can be extended and the production of clean work can be maintained by using bypass or continuous filter units containing suitable tiltering media (clay, cellulose cartridge. or waste cloth). Oils should be circulated at a rate no lower than 0.9 m/s ( I80 ft/min) to break up excessive vapor formed during quenching. Advantages of oil vs. salt include the following:

118-122 5 I-52 -12-13 38-39 35-36 95 0.00 None 0.45

l

Optional

l

range for moctitied martempering

l

Oil can be used at lower temperatures Oil is easier to handle at room temperature Dragout is less

Disadvantages l l

l

of oil vs. salt include the following:

hlaximum operating temperature of oil is 230 “C (445 “F) Oil deteriorates with usage Workpieces require more time to reach temperature equalization Oil, hot or cold, is a fire hazard Soap or emulsifier is needed to wash off oil. Washers must be drained and refilled periodically. Oil wastes present disposal problems

are immersed in high-temperature salt; and there is potential for explosive reactions when atmosphere furnaces are connected to martempering salt quenches and atmospheres are sooty Quenching salt can be contaminated by high-temperature. neutral salt used for heating. To maintain quench severity. sludging is required

l

Niche for Fluidized Beds. Marquenching

Alloy steels generally are more adaptable than carbon steels to martempcring (see Figure). In general. any steel that is normally quenched in oil can be martempered. Some carbon steels that are normally water quenched can be mat-tempered at 205 “C (100 “F) in sections thinner than 5 mm

applications are limited. They have the advantage of equal heat transfer throughout the entire quenching temperature range. The quench rate is reproducible. does not degrade with time, and can be adjusted within wide limits.

l l

Martempering

Applications

104 / Heat Treater’s

Guide

(0.1875 in.), using vigorous agitation of the martempering medium. In addition, thousands of flay cast iron parts are martempered on a routine hasis. The grades of steel that are commonly martempered to full hardness include 1090.3130. ~l3O,-llSO. -1340. 300M (-!3AOhIj. -MO, 5 I-IO. 6150. 8630.86-H~. 8710. 8715. SAE I I-I I, and SAE 52 100. Carburizing Fades such as 33 I2.163O.S 120.8620, and 93 IO also are commonly martempered after carhurizing. Occasionally, higher-alloy steels such as type -l IO stainless are martempered. but this is not a common practice.

Temperature ranges of martensite formation and low-alloy steels

in 14 carbon

Success in martempering is based on a knowledge of the transformation characteristics (TlTcurvesj of the steel being considered. The tempe.rature range in which martensite forms is especially important. Low-carbon and medium-carbon steels 1008 through 1040 are too low in hardenability to be successfully martempered, except when carhurized. The IIT curve for the 1034 steel in an adjoining Figure is characteristic of a steel that is unsuitahle for martempering. Except in sections only a Few thousandths of an inch thick. it would be impossible to quench the steel in hot salt or oil without encountering upper transformation products. Borderline Grades. Some carbon steels higher in manganese content such a< lo-11 and I I-II can be martempered in thin sections. Low-alloy steels that have limited applications for martempering are listed (the lowercarbon grades are carburired before martempering): 1330 to I315.4017- to

Time-temperature transformation diagrams for 1034 and 1090 steels. The 1090 steel was austenitized at 885 “C (1625 “F) and had a grain size of 4 to 5.

Approximate maximum diameters of bars that are hardenable by martempering, oil quenching, and water quenching.

Effects of austenitizing temperature temperature of 52100 steel

on grain size and M,

Tempering Processes/Technology

material being austenitized be uniform. Also, use of a protective atmosphere (or salt) in austenitizing is required because oxide or scale will act as a barrier to unifomr quenching in hot oil or salt. Process variables that must be controlled include austenitizing temperature. temperature of martempering bath, time in mar-tempering bath, salt contamination. \vater additions to salt, agitation, and rate of cooling from the martempering bath. Austenitizing temperature is important because it controls austenitic grain size. degree of homogenization, and carbide solution, and because it affects the M, temperature and increases grain size. (See adjoining Figure.) Temperature control during austenitizing is the same for mar-tempering as for conventional quenching: a tolerance of f8 “C (+I4 “F) is common. The austenitizing temperatures most commonly used for several different steels are indicated in an adjoining Table. In most instances, austenitizinp temperatures for martempering are the same as those for conventional oil quenching. Occasionally, however, medium-carbon steels are austcnitized at higher temperatures prior to martempering to increase as-quenched hardness. Salt Contamination. When parts are carburized or austenitized in a salt bath, they can be directly quenched in an oil bath operating at the martempering temperature. However. if the parts are carburized or austenitized in salt containing cyanide. they must nor be directly mar-tempered in salt because the two types of salts are not compatible and explosions can occur if they are mixed. Instead, one of two procedures should be used: Either air cool from the carburizing bath. wash. reheat to the austenitizing temperature for case and/or core in a chloride bath, and then martemper; or quench from the cyanide-containing bath into a neutral chloride rinse bath maintained at the austenitizing temperature and then martemper. Temperature of the mat-tempering bath varies considerably, depending on composition of workpieces, austenitizing temperature, and desired results. In establishing procedures for new applications. many plants begin at 95 “C (205 “F) for oil quenching, or at about 175 “C (3-15 “F) for salt quenching, and progressively increase the temperature until the best combination of hardness and distortion is obtained. Mar-tempering temperatures (for oil and salt) that represent the experience of several plants are listed in the Tab12 pre\ iously cited.

4032,3118to4137.~22and4~27,1520,5015and50~6,6l1Xand6120. 8115. Most of these alloy steels are suitable for mar-tempering in section thicknesses of up to 16 to 19 mm (0.625 to 0.75 in.). Martempering at temperatures below 205 “C (-100 “F) will improve hardening response, although greater distortion may result than in mar-tempering at higher temperatures. Effect of Mass. The limitation of section thickness or mass must be considered in mar-tempering. With a given severity of quench. there is a limit to bar size beyond which the center of the bar will not cool fast enough to transform entirely IO martensite. This is shown in an adjoining Figure. which compares the maximum diameter of bar that can be hardened by martempering, oil quenching, and water quenching for IO-t.5 steel and five alloy steels in various hardenabilities. For some applications, a fully martensitic structure is unnecessary and a center hardness IO HRC units lower than the maximum obtainable value for a given carbon content may be acceptable. By this criterion, maximum bar diameter is 25 to 300%, greater than the maximum diameter that can be made fully martensitic (see lower graph in Figure just cited). Non-martensitic transformation products (pearlite. ferrite, and bainite) were observed at the positions on end-quenched bars corresponding to this reduced hardness value, as follows: Steel

~ansformation

1045

159, pearlire

8630 1340 52100

IO% ferrite and hainite 20% ferrite and hainite

4150

SOCrpearlitemd btinirr 20% binite

1340

SQ binitc

Control

of Process

Variables

The success of martempering depends on close control of variables throughout the process. It is important that the prior structure of the

Typical Austenitizing

and Martempering Temperatures for Various Steels Austenitizing temperature

Grade

OC

Through-hardening 102-l

/ 105

Mat-tempering

temperature

Oil(a) OF

T

Salt(b) OF

OF

T

steels

I070 II46 1330 4063 4130 -II-to -1140 4340. -1350 52100 52100 8740

Carburizing

steels

3312 1320 4615 1720 8617.8620 8620 9310

(a) Trme in oil varies from 1 to 20 min. depending on section thi&nrss. tb) hlutempttnng range (and sometimes

aho\c range) are used for thinner sections and more intrtcate parts.

temperature

dcpads

on shape and ma>) of part, king

quenched:

higher temperatures

in

106 / Heat Treater’s

Guide

Time in the martempering bath depends on section thickness and on the type, temperature. and degree of agitation of the quenching medium. The effects of section thickness and of temperature and agitation of the quench bath on immersion time are indicated in an adjoining Figure. Because the object of martempering is to develop a martensitic structure with low thermal and transformation stresses, there is no need to hold the steel in the martempering bath for extended periods. Excessive holding lowers foal hardness because it permits transformation to products other than martensite. In addition, stabilization may occur in medium-alloy steels that are held for extended periods al the martempering temperature. The martempering time for temperature equalization in oil is about four fo five times that required in anhydrous salt at the same temperature. Water Additions to Salt. The quenching severity of a nitrate-nitrite salt can be increased significantly by careful addition of water. Agitation of the salt is necessary to disperse the water uniformly, and periodic additions are needed to maintain required water content. The water can be added with complete safety as follows: l

l

l

l

Martempering time versus section size and agitation of quench bath for 1045 steel bars. Effects of bar diameter and agitation of quench bath on time required for centers of 1045 steel bars to reach martempering temperature when quenched from a neutral chloride bath at 845 “C (1555 “F) into anhydrous nitrate-nitrite martempering salt at 205,260, and 315 “C (400,500, and 600 OF). Length of each bar was three times the diameter.

Waler can be misted at a regulated rate into a vigorously agitated area of the molten bath In installations where the salt is pump circulated. returning salt is cascaded into the quench zone. A controlled fine stream of water can be injected into the cascade of returning salt The austemperinp bath can be kept saturated with moisture by introducing steam directly into the bath. The steam line should be trapped and equipped with a discharge Lo avoid emptying condensate directly into the bath Steam addition of water to the bath is done on baths with operating temperatures above 260 “C (500 “F)

Austempering

of Steel

In this process, a ferrous alloy is isothermally quenched at a temperature below that of pearlite formation. Workpieces are heated 10 a temperature within the austenitizing range. usually 790 to 915 “C (l-155 to 1680 “F). Quenching is in a bath maintained at a constant temperature. usually in a range of 260 Lo 400 “C (500 to 750 OF). Parts are allowed to transform isothermally to bainite in this bath. Cooling to room temperature completes the process. The basic differences between austempering and conventional quenching and tempering is shown schemalically in an adjoining Figure. In true austempering. metal must be cooled from the auslenitic temperature to the temperature of the austempering bath fast enough to ensure complete transformation of austenite to bainite.

Compositions austempering

and characteristics

Sodium nitrate. Q Potassium nitrate. % Sodium nitrite, B Melting Point (approx). “C (“F) Working temperature range. “C t0F)

of salts used for

tlibh range

Wide range

G-55 35-5s

O-25 15-55 25-55 150.165(300-330, 17s-540(315-1000,

220 (430) 360-595 (500- I IO0

Treatment of hardenable cast irons is another application. In this case, a unique acicular matrix of bainitic ferrite and stable high-carbon austenite is formed. Advantages of austempering include higher ductility. toughness. and strength at a given hardness (see Table) and reduced distortion. In addition, the overall time cycle is the shortest needed to get through hardness within the range of 35 to 5S HRC.

Quenching

Media

Molten salt is the most commonly used. Formulations and characteristics of two typical baths are given in an adjoining Table. The high range of salt is suitable for only austempering. while the wide range type is suitable for ausrsmpering, martempering, and variations thereof. Quench severities under different conditions are compared in an adjoining Table. The quenching severity of a nitrate-nitrite salt can be boosted significandy with careful additions of water. The salt must be agitated to disperse the water uniformly. Periodic additions are needed to maintain required water contenl. Water usually is added bj directing a stream onto the molten salt at the agitator vortex. A protective water shroud surrounds the water spray Lo prevent spattering. Turbulence of the water carries it into the bath without spattering. a hazard to the operator. Water should never be added from a pail or dipper. Water is continuously evaporating from the bath at a rate H hich increases as hot work is quenched. The amount of waler added to an

Tempering

Comparison of time-temperature

Mechanical

Properties

transformation

HtUdllesS, HRC

Beat treatment

Water quenched and tempered Waler quenched and tempered Martempered and tempered Martempered and tempered Austempered Austempered

I

2 3 4 5 6

open bath varies with the operating temperature the following recommended concentrations: Temperature T

OF

205 260 315 370

400 500 600 700

quenching and tempering and for austempering

J

R Ibf

53.0

16

12

52.5 53.0 S2.8

19 38 33 61 5-t

1-l 28 2-I 4s 40

52.0 52.5

of the salt, as indicated

by

Water concenh-atioo, % ‘4 to 2 ‘/z 10 I ‘I4 10 ‘/2 ‘4

The presence of water can be visually detected by the operator because steam is released when hot work is immersed into the nitrate-nitrite salt. Oil as Quenching Media. Usage is restricted to quenching below 245 “C (475 “F), because of oil’s chemical instability, resulting in changes of viscosity at austempering temperatures.

Quench

severity

comparison

l

II 8

for salt quenches

Still and dry

Agitated and dry A@ated with 0.5% water Agitated with 2% water Agitated with IO%,water 131 Scr “Crossmann number (H)” lb, Requirrs

feasible in treating characteristics.

0.15-0.20 0.25-0.35

0.40-0.50 0.50-0.60

(a)

0.15 0.20-0.2s

0.30-0.40 0.50-0.60(r) Nor possible of Terms Related to Heat

090.I.?lbl In the “Glossar) special enclosed quenching apparatus

5140 and other

steels with

similar

transformation

steels include:

Steels

Selection is based on the transformation characteristics as indicated by time-temperature-transformation (TIT) important considerations are:

l

in., %

Estimated Grossmann number (IQ at temperature 18o~C (36oOF) 370 Yz (7ooOF)

Agitation

Other austempering

l

Elongation In 25 mm, or 1

Impactstrength

Trrating.”

Austempering

/ 107

of 1095 Steel Heat Treated by Three Methods

Specimen

No.

cycles for conventional

Processes/Technology

of a specific steel diagrams. Three

Location of the nose of the IIT curve and the speed of a quench Time needed for complete transformation of austenite to bainite at the austempering temperature Location of the MS point

Because of its transformation characteristics, 1080 carbon steel has limited applicability for austempering (see Figure). Cooling must take place in about I s to avoid the nose of the TIT curve to prevent transformation to pearlite on cooling. Because of this disadvantage, austempering of 1080 is limited to thin sections-the maximum is about 5 mm (0.1 in.). On the other hand, 5 140, a low-alloy steel. is well suited to the process (see TIT curves for 1080.5 140, 1034, and 9261 in an adjoining Figure). About 2 s are allowed to bypass the nose of the curve; transformation to bainite is completed within I to IO tin at 3 I5 to 400 “C (600 to 750 “F). This means that sections thicker than those possible with 1080 steel are

l

l

l

l

Plain carbon steels containing 0.50 to I .OO% carbon and a minimum of 0.604 manganese High-carbon steels containing more than 0.90% carbon and, possibly, a little less than 0.60% manganese Some carbon steels, such as IO-II. with less than O.SO%, carbon and manganese in the range of I .OO to I .6S% Certain low alloys, such as 5 IO0 series alloys, that contain over 0.40% carbon, plus other steels such as -II-u). 6145, and 9440

Some steels sufficient in carbon or alloy content to be hardenable are borderline or impractical because transformation at the nose of the TIT curve sms in less than I s. ruling out the quenching of all but thin sections in molten salt witbout forming some pearlite. or transformation takes excessively long times. Chemical composition is the main determinant of the martensite start (Ms) temperature. Carbon is the most significant variable. Direct effects of other alloying elements are less pronounced, but carbide-forming elements such as molybdenum and vanadium can tie up carbon as alloy carbides and prevent complete solution of carbon.

108 / Heat Treater’s

Time-temperature

Guide

transformation

When applied to wire, the modification

Transformation

diagram for 1080 steel, showing difference between conventional

and modified austempering.

shown is known as patenting.

characteristics of 1080,5140,1034, and 9281 steels, in relation to their suitability for austempering. 1080. limited suitability for austempering because pearlite reaction starts too soon near 540 “C (1000 “F); 5140, well suited to austempering; 1034, impossible to austemper because of extremely fast pearlite reaction time at 540 to 595 “C (1000 to 1105 “F); 9261, not suited to austempering because of slow reaction to bainite at 260 to 400 “C (500 to 750 “F)

Tempering

Hardness

of Various

Steels and Section

Sizes of Austempered

Section size mm

in.

1050 1065 IQ66 108-t

3(b) S(C) 7(C) wi 13(c) S(C)

1086 lo90 1090(e) 10% 1350 4063 -tlSO 436s 5140 5160(e) 8750 so100

20(C) YC) 16(Cl 16(C) 13(C) 25(c)

26(C) 3(b)

8(c)

OF

0.12% b) 0.187(C) 0 281(C)

315 W (d)

655 Id) (d)

0.218(c) 0.516(c) 0.187(c) 0.810(c) 0.118(C) 0.625~) 0.625(c) 0.500(c)

(di W (d) 315(f) Cd) W (d) W (di 345 315(f) 31s (d)

(d) td) (d)

(a~Calculnted. (b) Sheet thickness. (c) Diamelerofsection. (d) Salt temperature condned pearlile as nell as binite. if) Salt with waler addilions. (g) Ehperiment3l

Typical

Production

Applications

hl, temperature(a)

T

I .ooo(c) 0.125(b) I .035(C) 0. IX(b) 0.312(C)

3(b)

T

OF

Badness, HRC

320

610 52s 500 39s 430

-tl-47 53-56 53-56 55-58 ss-58 57-60 443 (a\*@ 57-60 53-56 53-56 52 max 5-l m3.x 4348 46.7 (avg) 1748 57-60

27s 260 200 215

600( f)

adjusted logi~e \nlur

/ 109

Parts

Salt temperature

steel

Processes/Technology

(d) (d) (d) id, (db

21o(gl 235 Z-IS 285 210

410(g) -Iso

6SS 6OOtfj 600 td)

330 2.55 289

630 19Q 51s

maximum

-17s S-IS 110

hardness and 1005, bsinite. (el hlodlfied

austempering:

microsuucr~re

of Austempering

Parts listed in order of increasing section thickness

Part

steel

hlaximum section thiekness mm in.

Parts per unit weight lb kg

Salt temperature OC OF

77Olkg

360 3SS 330 330 370 360 370 360 345 34s 290

Immersion time, mm

6ardlless, ERC

IS IS I5

-I2 -I’ -I8 e-so -I2 J2 1’ 35 -Is-so JS 53 so so

Plain carbon steel parts Clevis Follower arm Spring Plate Cam lever Plae 7)pzbu Tabulator srop Lever Chain link Shoe-last link Shoe-toe cap Lawn mower Made Leter Fastener Stabilizer bar Boron steel bolt

1050 IOSO I080 1060 106.5 1050 106s 106s I050 IOSO 106s 1070 106s 1075 1060 1090 IOB20

0.75 0.7S 0.79 0.81 I .O I .o IO 1.2’ I.25 I.S 1.5 I.5 3.18 3.18

6.35 I9

6.35

0.030 0.030 0.03 I 0.032 0.040 0.041 0.0-w 0.048 0 OS0 0.060 0.060 0.060 0. I IS 0. I25

0.250 0.750 0.250

IlMig 22Okg xx/kg b2kg 0.S kg I4llkg UQlkg

187/lb IQwlh lonb ‘8nb ‘!iIh 6Mb

S72kg 86nig

26011b 39nh xnh ?j I b I l/lb sonb IOlh 4vlb

18/kl. I Sb@ 7alig I I O/kg ‘? kg I-iJ/kg

315 315 385 310

370 -110

680 675 625 b.10

6

7OO

IS IS IS IS IS IS

b75

700 680 650 690 SSO Et 72s F90 700 790

30 60 IS 5 25 6-9 5

b9O 550 620 3nJ

IS 2s -IS I-l

700 700 700 72s 580

30 IS 15 IS

30

s3 18 -to 37 45 30 35-40 15

72s 72s 550-600

5 5 30

30-35(C) 30-39(C) SO(C)

30-3s so -IO--IS 38-43

Alloy steel parts Socket wrench Chain link Pin Cylinder liner Anvil Shovel blade Pin Shaft

6lSO Cr-Ni-V(a) 3140 1140

Gecv Carburized Lever

I :60 I60 ‘5-1

0063

86-10

3.18

4068 3140 111Oibj

3.18

0.063 0.100 0. I25 0.115

6.39 9.53

0.250 0 37s

6150

12.7

o.sQn

0.3 kg I IO/kg s500/kg I5 kg 165kg

‘jib SO/lb 2mYlb 7 lb ‘,, lb

I wkg 0.5 kg -I.-l kg

4vib “, lb 2 Ih

365 290 37s 260 370 370 370 38s 305

33 kg 664

IS lb 30/Ib honb

38S 385 290-3 I5

-IS

steel parts 1010 III7

Shti Block (a1ContainsO.65

8620 to0.7%

C (b) Ladedgrade.

3.06 6.35 II.13

0.1.56 O.lSO 0.438

ICI Case hardness

l3Yhg

110 / Heat Treater’s

Guide

Effect of carbon content in plain carbon steel on the hardness of fine pearlite formed when the quenching curve intersects the nose of the time-temperature diagram for isothermal transformation

pering is a tbo-step process: austenitizing and isothermal transformation in an austempering bath. Generally, applications are limited to parts made from small-diameter bars or from sheet or strip which is small in cross section. The process is especially suitable for the treatment of thin section, carbon steel parts calling for exceptional toughness at hardnesses between 40 and 50 HRC. Reduction in the area of austempered, carbon steel parts usually is much greater than it is for parts conventionally quenched and tempered, as indicated in the following tabulation for 5 mm (0.180 in.) bars of 0.85% carbon, plain carbon steel:

Austempered mechanical properties Tensile strength. MPa (ksi) Keld strength. MPa (ksi) Reduction in area. %, Hardness, HRC

1780(258) 1450(210) 45

SO

Quenched and tempered mechanical properties Tensile strength. MPa (ksi) Yield strength. MI% (hi )

I795 (260) 1550(225) 28

Austenitizing temperature has a significant eFfect on the time at which transformation begins. As this temperature rises above normal (for a given steel) the nose of the TTT curve shifts to the right because of grain coarsening. Use of standard austenitizing temperatures is recommended.

Reduction in area. %, Hardness. HRC

Section Thickness

In commercial austempering practice, acceptable results are obtained with parts having less than 100% bainite. In some instances, 85% bainite is satisfactory. Representative practice in a dozen plants for a variety of parts and steels is summarized in an adjoining Table. Dimensional Control. Dimensional change in austempering usually is less than that experienced in conventional quenching and tempering. The process may be the most effective way to hold close tolerances without excessive straightening or machining after heat treating. Modified Austempering. hlodifications of the process that result in mixed pearlitelbainite structures are quite common in commercial practice. Patenting of wire is an example. Wire or rod is continuously quenched in a bath maintained at 5 IO to 540 “C (950 to 1000 “F) and held forperiods ranging from IO s (for small wire) to 90 s (for rod). Result: Moderately high strength combined uith high ductility. Modified practice varies from true austempering in that the quenching rate is different; instead of being rapid enough to avoid the nose of the TIT tune. it is sufficiently slow to intersect the nose, which results in the formation of tine pearlite. Practice is similar for plain carbon steels at hardnesses between 30 and 12 HRC. In this instance. the hardness of steel quenched at a rate that intersects the nose of the TIT curve varies with carbon content (see Figure).

Limitations

Maximum section thickness is important in determining if a part is a candidate for austempering. The maximum for a 1080 steel, for instance, is about 5 mm (0.2 in.), if the part requires a fully bainitic structure. Steels lower in carbon are restricted to proportionately less thicknesses. However. heavier sections can be handled if a low-carbon steel contains boron. Also, sections thicker than 5 mm (0.2 in.) are regularly austempered in production when some pearlite is tolerated (see Table that lists section thicknesses for specific steels).

Applications Austempering usually is substituted tempering for these reasons: l l l l

To To To To

for conventional

quenching

and

improve mechanical properties reduce the likelihood of cracking and distortion upgrade wear resistance at a given hardness add resistance to subsequent embrittlement

At times. austempering is more economical than conventional quenching and tempering-most likely when small parts are treated in an automated setup in competition with conventional quenching and tempering, which is a three-step operation: austenitizing. quenching, and tempering. Austem-

SO

Carbon Designation

& Alloy

Steels

Introduction

System

Much study and effort have been put into providing a simplified list of steel compositions to serve the metallurgical and engineering requirements of fabricators and users of steel products. These studies have resulted in the carbon and alloy steel compositions listed in Tables 2 to IO and are generally known as the Standard Grades.

Table 1 Types and Approximate Percentages of Identifying Elements in Standard Carbon and Alloy Steels Series designation

AISI-SAE Grades

Carbon

With few exceptions. steel compositions established by the American iron and Steel Institute and the Society of Automotive Engineers (AISI and SAE) use a four-numeral series to designate the standard carbon and alloy steels. specified to chemical composition ranges. In two instances of alloy steels. a five-numeral designation is used. In the alloy steel tables which are presented later in this section. some grades bear the prefix letter E. This denotes that the steel was made by the basic electric furnace process with special practice. In the designations of certain carbon and alloy steels. the suffix letters H and RH signify that the steel is made to comply with specific hardenability limits Carbon or alloy steel designations showmg the letter B inserted between the second and third numerals indicate that the steel contains 0.0005 to 0.003 boron. The letter L inserted between the second and third numerals of the designation indicates that this steel contains 0. IS to 0.35 lead for improved machinability. Table I represents an abbreviated listing of the AISI or SAE carbon and alloy steels. The fust two digits of each series have a detinite meaning, providing the approximate composition of elements other than carbon. The last two digits of the four-numeral designations and the last three digits of the five-numeral designations indicate the approximate mean carbon content of the allowable carbon range. For example. in Grade 1035. the 35 indicates a carbon range of 0.98 to 1.10. These last digits are replaced by XX in Table I. It is ohen necessary to deviate slightl) from this system and to interpolate numbers for some carbon ranges and for variations in manganese. sulfur, or other elements with the same carbon range.

Table 2 Compositions

steels

IOXX IIXX IZXX ISXX Alloy

Description

Nonresulhrize~. RlWlfWiZ~d Rephosphorized Nonresulfurized.

I .oO manganese maximum and resulfurized over I .OO manganese mwmum

steels

13XX 4OXX 4lXX 43xX 46xX 17xx -lxxx 51X.X SIXXX 52xXx 61XX 86XX 87XX 88XX 92xx SOBXX(ab SIBXXw BIBXX(a) 94BXXb)

I .7S manganese 0.20or0.25 molybdenum or0.2S molybdenum and 0.042 sulfur 0.50.0.80.or0.95shronium~d0.I?.0.30.or0.30molyhdenum I .83 nickel. 0.50 to 0.80 chromium. and 0.25 molybdenum 0.85 or I .83 nickel and 0.20 or 0.25 molybdenum I .OS nickel, 0.15 chronuum. 0.20or0.35 molphdenum 3.50 nickel and 0.25 molybdenum 0.80.0.88.0.93.0.9S.or l.oOchromium I 03shromium I .4S chromium 0.60or0.9.5 chromium and 0. I3 or0. IS vanadium minimum 0.55 nickel. O.SOchromium. and 0.20 molybdenum O.SS nickel, O.SOchromium. and 0.25 molybdenum 0.55 nickel, O.SOchromium. and 0 35 molybdenum 2 OOsilicon or I .40 silicon and 0.70 chromium 0.28 or 0.50 chromium 0.80 chromium 0.30 nickel. 0.45 chromium. and 0. I2 molybdenum 0.15 nickel. 0.40 chromium. and 0. I2 molybdenum

(a) B denotes horon steel. Sourw

r\/S/Swe/

Pmducrs Mmrrral

of Standard Carbon H-steels and Standard Carbon Boron H-steels

Steel UNS

designation AISI or SAE Standard

carbon

carbon

ISBZIH, lSB35H. ISB37H ISB-IIH lSB-%H lSB62H

ISBZIRH 15B35RH

C

H 10380 HI0450 H I5220 H 15240 H IS260 HI5110

0.3co.13 0.42-0.5 I 0.17-0.2s 0.18-0.26 0.2 I-O.30 0.35-0.4s

o.so- I .oo o.so- I 00 I .OO- I .SO 1.25-I 7Ya, 1.00-1.50 I .25-l 75(a)

HIS211 HIS351 HI5371 HIS411 HIS381 HIS621

O.I7-0.21 0.31-0.39 0.30-0.39 0.3s-O.-IS 0.43-05.3 0.5-i-0.67

0.70-I .20 O.70- I.20 I .OO- I.50 1.25-1.7S(aJ I .OO- I .50 I.OO-I 50

composition, Pmar

I S max

Si

0.040 0.040 0.040 0.010 0.040 0.040

0.050 0.050 o.oso o.oso 0.050 0.050

0. I s-0.30 0. I s-0.30 0. IS-O.30 0. I s-o.30 0.15.0.30 0. IS-O.30

0.040 0.040 o.@lo 0.040 0.040 0.040

0.050 0.050 0.050 0.050 0.050 o.oso

0. IS-O.30 0. I s-o.30 0. I s-0.30 0. I s-0.30 0. I s-o.30 0.40-0.60

A-steels

l038H IOJSH lS22H lS21H lS26H ISJIH Standard

Cheoucal hIo

No.

boron

(a) Standard AISI-SAE

E-steels

H-steels u ith I .7S manganese maximum

are slassitied

as cxhon

steels

112 / Heat Treater’s Guide Table 3 Compositions of Standard Nonresulfurized Carbon Steels (1 .O Manganese Maximum)

Table 4 Compositions of Standard Nonresulfurized Carbon Steels (Over 1.O Manganese)

Steel designation

Steel

UNS

AISlorSAE

No.

C

GlOO50 G 10060 GlOO80 GIOIOO GlOl20 GIOI30 G10150 GlOl60 GlOl70 Cl0180 GlOl90 GIOXO GlO210 G IO’20 Gl0230 GIO’SO Gl0260 GIO290 Gl0300 G10350 G 10370 G I0380 Gl0390 GIWOO GIO-PO GlO430 GIOUO Gl@iSO Gl0460 GlO490 GIOSOO Gl0530 GIOSSO GlOS90 GlO6OO GlO6-W Cl0650 GlO690 Gl07Oil Gl0750 Gl0780 Gl0800 GlO8-m Gl0850 Cl0860 GlO900 GlO950

0.06 max

0.35 max

0 08 mas

0 25 max

0. IO mu.

0.30-O 50 0.30-0.60 0 30-0.60 0.50-0.80 0.30-0.60 0.60-0.90 0.30-0.60 0 60-O 90 0 70-1.00 0.30-0.60 0.60-0.90 0.70. I .oo 0.30-0.60 0 30-0.60 0 60-O 90 0.60-0.90 0 60-O 90 0 60-0.90 0.70. I Ml 0.60-0.90 0.70. I .OO 0.60-0.90 0 60-0.90 0.70. I .OO 0.30-0.60 0.60-0.90 O.70- I.00 0.60-0.90 0 60-0.90 0.70. I .OO 0.60-0.90 0.50-0.80 0.60-0.90 0.50-0.80 0.60-O 90 0.40-0.70 0.60-O 90 0.40-0.70 0.30-0.60 0 60-O 90 0.60-0.90 0.70-I .OO 0.30-0.50 0.60-O 90 0.30-O so

Ions(ab

lOO6ta, 1008 1010 1012 1013 IO15 IO16 1017 1018 1019 1020 1021 IO22 1023 102s 1026 1029 1030 I035 1037 IO38 IO39 IO-K) IO-11 lo-l3 104-4 lo-15 1046 IO.49 1050 1053 IO.55 1059(a) IO60 106-l 1065 1069 1070 107.5 1078 I080 108-l IO85 1086(a) I090 IO9S

0.08-O. I3 0.10-0.15 0.11-0.16 0.13-O. I8 0.13-0.18 0. I s-0.70 0.150 ‘0 0.15-o ‘0 0.18-0.23 0.18-0.23 0.18-0.23 0.20-0.25 0.22-0.28 0.22-O 28 0 15-0.31 0.28-0.3-I 0.32-0.38 0.32-0.38 0.35-O 12 0 37-0.4-l 0.37-0.4-l 0.10-0.17 o.mo.17 0.13-0.50 0.13-0.50 o.-l3-0.50 0 -16.O.S? o.wo.ss o.-l8-o.ss 0 SO-O.60 0.59-0.65 055-0.65 0.60-0.70 0.60-0.70 0.65-0.75 0.65-O 75 0.70-0.80 0.72-0.85 0.75-0.88 0.80-0.93 0.80-0.93 0.80-0.93 0.85-0.98 0.90. I .03

Chemical composition, “0 Pmav hill 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.010 0.040 0.040 0.040 0040 0.040 0.040 0.010 0.0-N) 0.010 0.010 0.040 0.040 0.040 0.040 0.040 0.040 O.OXJ 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.010 0.040 0.040

UNS

AlSlorS.AE

No.

C

hln

0 OS0

IS13 1522 152-l IS26 IS’7 I.541 IS-18 IS51 I5S2 1561

GlSl30 GlS220 G I SXO GlS260 GlS270 GlS4lO G IS180 GISSIO G I.5520 Gl.5610 G IS660

0.10-0.16 0.18.0.24 0.19.0.2S 0.22-0.29 0.22-0.29 0 36-0.U O.-wo.s2 O.-IS-O.56 0.-+7-0.55 0.55-O 65 0.60-0.7 I

l.lO-1.u) 1.10-I.-IO 1.35-1.65 1.10.I.40 I .20- I .so 1.35-1.65 l.lO-I.40 0851.15 1.20-1.50 0.75-1.05 OX?-I.15

0.050 o.oso 0.050 0.050 0 050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.040 0.050 0.050 0.050 0.050 0.050 O.OSO 0.050 0.050 0.050 0.050 0.050 0 050 0.050 0.050 0.050 0.050 0 OS0 0.050 0.050 0 OS0 o.oso 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050

(a) Standard steel grades for w ire rods and u ire only

Detailed composition ranges will be pro\tded senes in other tables which follow.

Unified Numbering

Chemical composition, %

designation S max

for each member of each

System

The standard carbon and alloy grades established by AISI or SAE have now been assigned designations in the Unified Numbering System (UNS) by the American Society for Testing and hlaterials (ASTM ES27) and the Society of Automotive Engineers (SAE Jl868). In the composition tables which follow. the CJNS numbers are listed along with their corresponding AISI-SAE numbers. The UNS number consists of a single letter prefix followed by Eve numerals. The prefix letter G indicates standard grades of carbon or alloy steels. while the pretix letters H and RH indicate standard grades which meet certain hardenability limits. The first four digits of the UNS designa-

Pmax

S may

004 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040

0.050 o.oso 0.0.50 o.oso 0.050 0.050 0.050 0.050 0.050 0.050 0.050

tions usually correspond to the standard AISI-SAE designations, while the last digit (other than zero) denotes some additional composition requirement such as lead or boron. The digit is sometimes a 6. which is used to designate steels which are made by the basic electric furnace with special practices. The tern1 carbon steel does not necessarily mean that the steel does not contain any other alloying elements. There are, however. sharp restrictions on the amounts of alloy that may be contained in carbon steels. These generally agreed upon restrictions are summarized in the paragraphs which follow. Steel is considered to be a carbon steel when no minimum content is specified or required for aluminum (except as related to deoxidization or gram size control). chromium. cobalt. columbium (niobium). molybdenum, nickel. tmum.m~. tungsten. vanadium. ztrconium. or any other element added to obtarn a desired alloymg effect. Further restrictions include: (a) when the specified minimum for copper does not exceed O.-IO or(b) when the maximum content specified for any of the following elements does not exceed the percentages noted: I .6S manganese. 0.60 silicon, 0.60 copper. Boron may be added to carbon steels to improve hardenability (see Table 2). In all carbon steels. small quantities of alloying elements or residuals. such as nickel. chromium. and molybdenum. are present. Their existence is unavoidable because they are retained from the raw materials used for melting. As a rule, small amounts of these elements have little or no meaning to the fabricator. For purposes of identity and because of the wide variations in properties. compositions of the standard carbon steels are presented in five separate tables.

Standard

Nonresulfurized

Grades

Compositions for -t8 standard nonresulfurized grades. I.0 manganese maximum. are given in Table 3. hlany of these grades are available with an addition of 0. IS to 0.35 lead to improve machinability. When lead is added. it is denoted by the letter L between the second and third digtts. For example. a leaded grade of 1035 IS denoted as I0L-G. Similarly. many of these grades ‘are available with a boron addition. A letter B IS mserted between the second and thud digits, such as lOB35. Compositions for I I additional standard carbon steels are presented in Table -1. The essential difference between the steels listed in Table 3, assuming the same carbon content. and those listed in Table 4 is the higher manganese content of the latter group. For one grade, it is as high as I .6S. which is the borderline between carbon steels and alloy steel. Higher manganese increases hardenability. The grades listed in Table -I may also be produced with additions of lead or boron as described above for the grades listed in Table 3.

Standard

Resulfurized

Carbon Steels

Compositions listed in Table 5 represent those grades of standard carbon steels which ha\e been resulfurizcd. as high as 0.33 sulfur, for improved

Carbon

Table 5

Compositions

of Standard

Resulfurized

Note data point, 0

SICA designation AlSl or SAE

UNS No.

C

GI 1080 GIIIOO Glll30 Glll70 Glll80 Gll370 Gll390 GII-IOO GIlllO GIIUO Gll460 GIISIO

0.08-o. I3 0.08-O. I3 0. I3 “,M 0.11-0.20 0.11-0.20 0.32-0.39 0.35-0.43 0.37-0.44 0.37-0.1s 0.40-0.48 0.12-0.49 0.18-0.55

Chemical hlo

composition, Pmax

0.50-0.80 0.30-0.60 0.70-I .OO I .OO- I .30 1.30-1.60 I .35- I .6S I .35- I .65 0.70-I 00 1.35-1.6.5 1.35-1.65 0.70. I on 0.70. I .OO

Table 6 Compositions of Standard and Resulfurized Carbon Steels Steel designation AISI or SAE I211 I212 1213 1215 12LI-1

/ 113

Fig. 1 Relationship Between Carbon Content and Maximum Hardness. Full hardness can be obtained with as little as 0.60 C.

Carbon Steels

1108 1110 1113 1117 1118 1137 1139 II-IO 1141 114-l 1146 1151

& Alloy Steels Introduction

UNS No. Gl2llO GI2120 Gl2130 Gl2lSO GI2I.U

Chemical lull

C 0.13max 0.13max 0.13miu 009mrul O.lSmax

0.60-0.90 0.70-1.00 0.70-1.00 0.75-1.05 0.85-1.15

Standard Rephosphorized Carbon Steels

s

0.040 0.040 0.07-O. I2 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.010 0.040

0.08-O. I3 0.08-O. I3 0.24-0.33 0.08-O. I3 0.08-O. I3 0.08-O. I3 O.I3-0.20 0.08-O. I3 0.08-O. I3 0.2-t-0.33 0.08-o. I3 0.08-O. I3

Fig. 2 Relationship Between Carbon Content and Maximum Hardness. Usually attained in commercial hardening

Rephosphorized

composition, P 0.07-0.12 0.07-012 0.07-0.12 0.04-0.09 0.0-l-0.09

These grades are also available funher improvement in machinability.

machinability.

8

% S

&IO-0.15 0.16-0.23 0.2-bO.33 0.26-0.35 0.26-0.35

Pb .__

0.15-0.35,

afith lead additions

for

and Resulfurized

Table 6 lists compositions for four grades ofcarbon steels which contain higher than normal amounts of phosphorus as Nell as sulfur. One grade. IZLI-1. has been rephosphorized. resulikized. and leaded. All of the above conditions and additions contribute to the superior machining characteristics of these grades. Any steel from this group ma! be produced H ith additions of 0. I5 to 0.35 lead.

Alloy Steels A steel is considered to be an alloy grade u hen the maximum of the range given for the content of alloying elements exceeds one or more of the following limits: (a) I .6S manganese. (b) 0.60 silicon. (c) 0.60 copper. It is also considered an alloy steel uhen a definite minimum quantity of any of the following elements is specified or requued mfithin the limits of the recognized constructional alloy steels: (a) aluminum. (b) chromium. (c) cobalt. (d) columbium (niobium). (e) molybdenum.(f) nickel. (g) titanium, (h) tungsten. (f) vanadium. (b) zirconium. or any other alloying element added to obtain a specific alloying effect. As a rule. the total amount of alloy in these AISI-SAE Standard Grades of Alloy Steels does not exceed approximately 4.0 over and abobe that amount normally permitted in carbon steels. Compositions of Standard Alloy Steels. Compositions for a total of 58 different alloy steels are listed in Table 7. It might seem that there is great similarity among grades in some instances and that the liht could easily be reduced in number of grades. Houe\er. many different cornpow tions are required to fulfill the thousands of mechanical and physical propeny requirements for manufactured products. The demands of fabricability and economy are also factors which must be satisfied. often with ver> precise chemical compositions.

While the various compositions listed in Table 7 are not produced in equal quantities. each of the steels listed in this table is produced in significant quantities by numerous mills. A large number of them are also available through steel service centers. Almost all of the 58 compositions listed in Table 7 are available with lead additions for improved machinabiliry. and some manufacmrers produce certain alloy grades as resulfunzed steels. also to induce better machinabilit). Compositions of Standard Boron Steels. Compositions of the standard alloq grades which contain 0.0005 to 0.003 boron are listed in Table 8. The boron pro\ ides an increase in hardenability for these steels which are relativeI> lean alloys.

Hardenability Hardenabilitj and methods for increasmg this property. such as boron additions. are referred to several times uithin this article. However. hardenability does not necessarily mean the ability to be hardened to a certain Rockwell or Brine11 value. For example. Just because a given steel is capable of beI” hardened to 65 HRC does not necessarily mean that it has high hardennblhtj. Also. a steel that can be hardened to only 40 HRC may have very high hardenability. Hardenability refers to capacity of hardening tdeprh) rather than to mn\imum attainable hardness.

Role of Carbon The carbon content of a steel deremtines the maximum hardness attainable. urith particular emphasis on rhe word attainable. The effect of carbon on attainable hardness is demonstrated in Fig. I The maximum attainable hardness requires onlj about 0.60 carbon. Houever. the data shohn in Fig. I are actually theoretical. because the) are based upon heat treating of wafer-thin sections which are cooled from their austenitizing temperature to room temperature within a matter of seconds. thus developing 100%

114 / Heat Treater’s Guide martensite throughout their sections. Therefore, the ideal condition shown in Fig. I is seldom attained in practice. Figure 2 shows a better example of hardness versus carbon content because it is a more accurate condition, one expected in commercial practice. The most important factor influencing the maximum hardness that can be attained is mass of the metal being quenched. In a small section, the heat is extracted quickly, thus exceeding the critical cooling rate of the specific

Table 7 Compositions Steel designation AISI or SAE 1330 I335 1340 I345 4023 4002-l 4027 4028 4037 4047 4118 4130 4137 1140 1142 4115 1117 3150 4161 4320 43-m E1340 4615 4620 4626 3720 1815 4817 1820 5117 5120 5130 5132 5135 5140 5150 51s 5160 E5llOO E52lOO 6118 6150 8615 8617 8620 8622 8625 8627 8630 8637 8640 8641 8645 8655 8720 8740 8822 9260

steel. The critical cooling rate is that rate of cooling which must be exceeded to prevent formation of nonmartensitic products. As section size increases. it becomes increasingly difficult to extract the heat fast enough to exceed the critical cooling rate and thus avoid formation of nonmartensitic products. A typical condition is shown in Fig. 3, which illustrates the effect of section size on surface hardness and is a good example of the mass effect. For small sections up to I3 mm (0.5 in.), full hardness of approxi-

of Standard Alloy Steels

IJNS No.

C

hill

Pmax

Gl3300 Gl3350 G13400 Gl31SO G-40230 G-IO240 GUI270 G-l0380 G-l0370 G-IO-170 G-Ill80 G113OO G4 I370 GII-KlO G-l1420 G11150 G-II 470 G-l1500 G-l1610 GA3200 G-t3400 G-i3406 G-16150 G-t6200 G-l.6260 G17’OO G-R? I50 G38 I70 G-18200 GSll70 GSl200 GSl300 G5 I320 G5 I350 GSI400 G51500 G5lSSO GSl600 GSl986 GS2986 G6l I80 G615OO G86 I so G86170 G86200 G86220 G86250 G86270 G86300 G86370 G86400 G86120 G864SO G86SSO G87200 G87UKl G88220 G92600

0.28-0.33 0.33-0.38 0.38-0.13 0.43-0.48 0.20-0.2s 0.20-0.25 0.25-0.30 0.25-0.30 0.35-0.40 O.-e-0.50 0.18-0.23 0.28-0.33 0.35-0.40 0.38-0.43 0.40-0.4s 0.13-0.48 0.45-0.50 0.18-0.53 0.56-0.6-l 0.17-0.22 0.38-0.13 0.38-0.13 0.13-0.18 O.I7-0.22 0.2-1-0.29 0.17-o 22 0.13-O. I8 0. I S-O.20 0.18-0.23 0.15-020 0.17-0.22 0.28-0.33 0.30-0.3s 0.33-0.38 0.38-0.13 0 48-0.53 0.5 I-O.59 0.56-0.64 0.98-1.10 0.98. I. IO 0.16-0.2 I 0.18-0.53 0.13-0.18 0.15-0.20 0.18-0.23 0.20-0.25 0.23-0.28 0.25-0.30 0.28-0.33 0.35-0.40 0.38-0.43 0.40-0.45 0.13-0.48 0.5 I-O.59 0.18-0.23 0.38-0.13 0.20-0.2s 0.56-0.64

I .60- I .90 1.60-1.90 I .60-I .90 1.60-1.90 0.70-0.90 0.70-0.90 0.70-0.90 0.70-0.90 0.70-0.90 0.70-0.90 0.70-0.90 O.-iO-0.60 0 70-0.90 0.7s I .OO 0.7s I 00 0.75-I 00 0.75-1.00 0.7s-I 00 0.75. I.00 0.15465 0.60-0.80 0.65-0.85 0.15-0.65 0.15-0.65 0.45-0.65 0.50-0.70 0.10-0.60 0.10-0.60 0.50-0.70 0.70-0.90 0.70-0.90 0.70-0.90 0.60-0.80 0.60-0.80 0.70-0.90 0.70-0.90 0.70-0.90 0.75-1.00 0.25.0.15 0.3-0.45 0.50-0.70 0.70-0.90 0.70-O 90 0.70-0.90 0.70-0.90 0.70-0.90 0.70-0.90 0.70-0.90 0.70-0.90 0.75 I 00 0.7% I .OO 0.75-I .Oo 0.7sI Ml 0.75 I.00 0.70-0.90 0.7.5. I .oo 0.75 I .OO 0.75-l 00

0.03s 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.03s 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.039 0.02s 0.035 0.03s 0.035 0.03s 0.035 0.035 0.035 0.035 0.03s 0.035 0035 0.035 0.035 0.035 0 035 0.035 0.025 0.025 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.03s 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035

Chemical S max

composition,

0.040 0.040 0.040 O.UlO 0.040 0.035-0.050 0.040 0.035-O OS0 0.040 0.040 0.040 0.040 O.O-lO o.o-lo O.O-lO 0.040 0.040 0.040 0.040 0040 0.040 0 01s 0.040 0.040 0040 0.UK.l 0.040 0040 0Q-W O.O-lO O.UUl 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.03 0.03 0.040 0.040 0.040 OUUI 0.040 0040 0.040 0.040 0.040 0.040 0040 0.040 OUUI 0.O-U.l O.WO 0.040 0040 0.040

% Si

0. IS-O.30 0.15-0.30 0.15-0.30 0. IS-O.30 0. I S-0.30 0. I s-o.30 0.15-0.30 0. I SO.30 0. I s-o.30 0. I s-o.30 0. I S-O.30 0. I S-0.30 0.15-0.30 0.15-o 30 0.15-o 30 O.I5-0.30 0. I S-0.30 0.15-0.30 0. I S-0.30 0.15-0.30 0.15-0.30 0.15.0.30 0. IS-O.30 0. I s-o.30 0.15-0.30 0.15-0.30 0. I S-O.30 0. I s-o.30 0. IS-O.30 0. I s-0.30 0 IS-O.30 0. I s-0.30 0.15-O 30 0 IS-O.30 0 IS-O.30 0.15-o 30 0.15-0.30 0. IS-O.30 0. I s-0.30 0. I S-O.30 0.15-0.30 0. I s-o.30 0.15-0.30 0. I s-0.30 0. I s-o.30 0.15-0.30 0. I s-o.30 0.15.0.30 0.15-0.30 0.15-0.30 0. IS -0.30 0.15-0.30 0. I s-o.30 0. I s-o.30 0. I s-o.30 0 I s-0.30 0.15-0.30 I 80-2.20

Ni

Cr

0.40-0.60

I .hS-2.Ou I .6S-2.00 I .65-2.00 I .65-2.00 I .65-2.00 070-,100 0.9U I .20 3.35-3.7s 3.25-3.7s 3.25-3.7s

0.40-0.70 0.40-0.70 0 40-0.70 0.40-0.70 0.10-0.70 0.40-0.70 0.40-0.70 0.10-0.70 0.4UO.70 0.4UO.70 0.40-0.70 0.40-0.70 0 30-0.70 0.10-0 70 0.10-0.70

0.8Ul.10 0.8Ul.10 0.8Ul.10 0.80- I. IO 0.8Ul.10 0.80-1.10 0.8Ul.10 0.7uo.90 0.40-0.60 0.7uo.90 0.7uo.90

0.35-0.55

0.7uo.90 0.7uo.90 0.80-1.10 0.7s- I 00 0.8U I .05 0.70-0.90 0.70-0.90 0.7uo.90 0.7uo.90 0.90-1.1s I .3u I.60 o.suo.7o 0.80. I. IO O.JUO.60 0.10-0.60 0.40-0.60 0.40-0.60 0.40-0.60 0.40-0.60 0.40-0.60 0.10-0.60 0.40-0.60 0.40-0.60 0 40-0.60 0.40-0.60 O.NLO.60 O.-K-O.60 0.40-0.60

MO

0.20-0.30 0.20-0.30 0.20-0.30 0.20-0.30 0.20-0.30 0.20-0.30 0.08-o. I5 0. IS-O.25 0. IS-O.25 0. IS-O.25 0. I s-o.25 0. IS-O.25 0. I s-o.25 0. I s-o.25 0.25-0.35 0.2UO.30 0.20-0.30 0.2uo.30 0.20-0.30 0.20-0.30 0. I s-0.25 0.15-0.25 0.20-0.30 0.20-0.30 0.2uo.30

0.10-0.15 v O.lSVmin 0. IS-O.25 0.15-0.2s 0. I s-o.25 0.1%0.25 0.15.0.25 0. I s-o.25 0. I s-o.25 0. I s-o.25 0. I s-o.25 0. I5-0.25 0. I SO.25 0. I so.25 0.20-0.30 0.20-0.30 0.3uo.40

Carbon & Alloy Steels Introduction Table 8 Compositions Steel designation AISI or SAE 508-u 50B-l.6 SOB50 SOB60 SIB60 8lBxi 94817 93830

Steel designation AISI or SAE I330H I335H l34OH I .34SH 33lORH 4027H 4027RH m28H 4032H 3037H 4042H 4047H 4118H -lllOH 4I2ORl-l -ll30H 413SH Jl37H 414OH 1112H 4l4SH ll45RH ll47H 4150H 416lH 116lRH 1320H J32ORH 434OH U34OH WOH 4626H 4720H 18lSH 4817H 4820H 4820RH SW6H 5120H 5130H 513oRH Sl32H 5135H 514OH SI-IORH SISOH SISSH 516OH 516ORH 6ll8H

of Standard Boron (Alloy) Steels

UNS No.

C

GSOUI G504.61 GSOSO I GSXOI GSl601 G81351 G9-1171 G9330 I

0.43-0.48 0.44-0.19 0.48-0.53 0.56-0.6-I 0.56-0.6-l 0.43-0.48 0. I s-o.20 0.28-0.33

Table 9 Compositions UNS No. HI3300 H I33SO HI3400 H I3150 H40270 H-U)280 HA0320 HA0370 H40420 H40470 H-II I80 H41200 H-i1300 H41350 H1 I370 HJl400 HJI-120 HJl-450 HA1470 H1lSOO H41610 H33200 H-t3400 H-13406 H-i6200 H-W60 H-17200 H48150 H48170 H-i8200 H50460 HSl200 HSl300 H51320 HSl350 HSl400 HSISOO HS I550 H51600 H61180

/ 115

MO 0.75. 0.7s 0.7s0.75 0.7s0.7s 0.75-I 0.7s

I .OO I .Ocl I .OO I .OO I .OO I Ml .OO I .OO

Pmax

Chemical Smax

0.035 0.035 0.035 0.035 0.03s 0.035 0.035 0.035

0.040 0.040 0.040 0.040 0040 0.040 0.040 0040

composition,

% Si

0.15-0.30 0.15-0.30 0. I s-0.30 0. IS-O.30 0.15-0.30 0. IS-O.30 0. IS-O.30 0. I s-o.30

Ni

Cr

MO

0.20-0.40 0.30-0.60 O.30-0.60

0.40-0.60 0.20-0.35 0.40-O 60 0.40-0.60 0.70-0.90 0.3s-0.55 0.30-0.50 0.30-0.50

0.08-O. IS 0.08-O. IS 0.08-O. I5

Ni

Cr

hlo

of Standard Alloy H- and RH-Steels

C 0.27-O 33 0.32-0.38 0.37-0.4-l o.-lz-0 49 0.08-O. I3 0 240.30 0.2s-0.30 0.24-0.30 0.29-0.35 0.3-I-0.1 I 0.39-0.16 O.-w0.5 I 0.17-0.23 0 18-0.23 0.18-0.23 0.27-0.33 0 32-0.38 0.31-0.1 I 0.37-0.4-l 0.39-0.16 0.12-0.49 0.43-0.48 0.44-0.5 I 0.47.05-l 0.55-0.65 0.56-0.6-l 0.17-0.23 O.I7-0.22 0.37-0.-u 0.37.0.u 0.17-0.23 0.23-0.29 0.17-0.23 0.12-0.18 0.13-0.20 0.17-0.23 0.18-0.23 0.13.o.so 0.17-0.23 0.27-0.33 0.28-0.33 0.29-0.3s 0.32-0.38 0.37-0.44 0.38-0.33 0.47-0.54 O.SO-0.60 0.55-0.65 0.56-0.63 0.15-0.21

hln I .-Is-1.05 I .-Is-2.05 I .J5-2.05 1.35-2.05 0.10-0.60 0.60- I.00 0.70-0.90 0.60. I.00 0.60- I.00 0.60-I .OO 0.60. I .OO 0.60-I .OO 0.60. I .OO 0.90-I .2O 0.90. I.20 0.30-0.70 0.60- I.00 0.60. I.00 0.65-1.10 0.65-1.10 0.65-1.10 0.75-1.0 0.65-1.10 0.65-1.10 065-1.10 0.75 I .o 0.40-0.70 0.45-0.65 0.55-0.90 0.60-0.95 0.35-0.7s 0.40-0.70 O.-IS-0.75 0 30-0.70 0.30-0.70 0.40-0.80 O.SO-0.70 0.65-1.10 0.60- I .OO 0.60-I .OO 0.70-0.90 0.50-0.90 0.50-0.90 0.60- I .OO 0.70-0.90 0.60- I .OO 0.60. I .OO 0.65- I .OO 0.75 I.00 0.40-0.80

Pmax

Chemical Smav

composition,

B Si

0 15-0.30 0 15-0.30 0.15-0.30 0 15-0.30 0.15-0.35 0. IS-O.30 0. IS-O.35 0. IS-O.30 0. I S-0.30 0. IS-O.30 0. IS-O.30 0. IS-O.30 0. I s-o.30 0. I s-o 35 0. I s-0.35 0.1s.0 30 0. I j-O.30 0. IS-O.30 0. I s-o.30 0. I s-0.30 0. I s-o.30 O.ls:b.30 0.15-0.30 0. I s-o.30 0.15-0.35 0. IS-O.30 0 15-0.3s 0. IS-O.30 0.15.0.30 0.15-0.30 0. IS-O.30 0 15-0.30 0. I s-o.30 0. IS-O.30 0.15-0.30 0 15-o 35 O.lS-0.30 0 15-0.30 0.15-0.30 0. I s-o.35 O.IS-0.30 0. IS-O.30 0. I s-0.30 11.IS-O.35 0. IS-O.30 0. I s-0.30 0. IS-O.30 0. I s-o.35 0. I s-o.30

3.2S-3.7.5

I .SS-2.00 I .6S-2.00 I .ss-2.00 I .ss-2.00 I .SS-2.00 0.65. I .05 0.85 I.25 3.20-3.80 3.20-3.80 3.20-3.80 3.25-3.7s

I.-u-I.75

0.30-0.70 0.40-0.60 0.40-0.60 0.75-l .?O 0.75-1.20 0.75- I.20 0.75-1.20 0.75-1.20 0.7sI.20 0.80-1.10 0.75 I.20 0.75-1.20 0.65-0.95 0.70-0.90 0.35-0.65 0.10-0.60 0.65.0.9s 0.65-0.95

0.30-0.60

O.I3-0.43 0.60-I .OO 0.75-l .20 0.80-l IO 0.65-1.10 0.70-1.15 0.60-I .cKl 0.70-0.90 0.60- I .cKl 0.60-I .Oo of3 I .oo 0.70-0.90 0.U0.80

0.20-0.30 0.20-0.30 0.20-0.30 0.20-0.30 0.20-0.30 0.20-0.30 0.20-0.30 0.08-o. IS 0.13-0.20 0.13-0.20 0. I s-o.15 0. I so.25 0. I so.25 0. I s-o.25 0. I WI.25 0. I s-o.25 0. I S-O.25 0. I s-o.25 0.15-0.2.5 0.25-0.3s 0.25-0.3s 0.20-0.30 0.20-0.30 0.20-0.30 0.20-0.30 0.20-0.30 0. I s-o.25 0. I so.25 0.20-0.30 0.20-0.30 0.204.30 0.20-0.30

0.10-0.15

118 / Heat Treater’s Guide Table 9 Compositions Steel designation AISI or SAE 6150H 8617H 8620H 8622H 8611RH 862SH 8617H 863OH 8637H 564OH 8642H 864SH 8650H 8655H 866OH 871OH 8720RH 874lH XKEH 8811RH YXOH 9310H 93 IORH

of Standard Alloy H- and RH-Steels (continued)

1rNs No.

C

bin

Pmax

Chemical S mar

H6lSOO H86 I70 H862OO H86220

0.17-0.51 0. I-LO.20 0.17-0’3 0. I9-0.25 0.20-0.2s 0.22-0.28 0.21-0.30 0 ‘7-0.33 0 3-l-0.41 0.37-0.4-l 0.39-0.46 0.42-0.19 0.47-0.51 0.50-0.60 0.55-0.65 O.I7-0.23 0.18-0.73 0.37-0.4-l O.I9-0.25 0.20-O 25 O.SS-0.65 0.07-O 13 0.084. I3

0.60-l 00 0.60-0.95 0.60-0.95 0.60-0.95 0.70-0.90 0.60-O 9.5 0.60-O 95 0.60-0.95 0.70-I OS 0.70. I .OS 0.70-I .os 0.70-I OS 0.70. I 05 0.70. I 05 0.70. I .os 0.60-0.95 0.70-0.90 0.70-I .os 0.70-I .Oj 0.7% I .OO 0.65.I.10 0.10-0.70 0.45-0.65

0.03S 0.035 0.03s 0.035

0.040 0.040 0.040 0.040

0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035

0.040 0.040 0.040 0.040 0040 0.040 0.040 0.040 0040 0.040 0040

H862SO H86270 H86300 H86370 H86400 H86-420 H86-150 H86SOn H865SO H866OO H87200 H874OO H88220 H926OO H93100

Table 10 Compositions Steel designation Al!31 or SAE

0025 0 035

00-m 0.040

0035 0.035

O.&J 0.040

Z Si

Ni

0.1s0.30 0.15-O 30 0. I S-0.30 0. I s-o.30 0. I S-0.35 0. I s-o 30 0. IS -0.30 0. I S-O.30 0. I5-0.30 0. I s-o.30 0.15-030 0.15-0.30 0.15-0.30 0.15-0.30 0.15-0.30 0.15-0.30 0. IS-O.35 0 IS-O 30 0. I j-O.30 0.1s0.35 I .70-z 20 0.1%0.30 0. I s-o 35

0.35-0.75 0.3.5-0.7s 0.35-0.7s 0.10-0.70 0.35-0.7s 0.35-0.75 0.35-0.7s 0.35-0.75 0.35.0.7.i 0.35-0.7S 0.35-0.75 0.35-O 75 0.35-0.75 0.35-0.75 0.35-0.7s 0.10-0.70 0.35-0.7s 0.35-0.7s 0.40-0.70 2.95-3 55 3.00-3.50

Cr

MO

0.75 I.20 0.35-0.65 0.35-0.65 0.35-0.65

O.lSVmin 0. IS-O.25 0. I S-O.25 0. IS-O.25 0.15-0.25 0. I s-o.25 0.15-0.25 0.15-0.2s 0. I S-O.65 0. IS-O.25 0. IS-o.29 0.15-0.25 0. I5-0.25 0.15-0.25 0.15-0.25

0.40-0.60 0.35-0.65 0.35-0.65 0.35-0.6.5 0.3.5-0.6.5 0.35-0.65 0.35-0.65 0.35-0.65 0.35-0.65 0.35-0.65 0.35-0.65

0.35-0.65 0.40-0.60 0.3S-0.65 0.35-0.65 0.10-0.60

0.20-0.30 0.2uo.30 0.20-0.30 0.3uo.-lo 0.3uo.40

I .OO- I .45 I .OO- I .-IO

0.08-O. IS 0.08-o. IS

of Standard Boron (Alloy) H- and RH-Steels

UNS No.

Chemical S max

c

hln

Pmax

0.65-1.10 0.75. I On 0.65I.10

0.03s

0.040

0.035 0.035

0040 0 040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040

SOB-NIH

HSOJOI

WB-IORH SOBUH 50B16H SOBSOH SOB60H 5 I BhOH 81 B1SH 86830H 86815H 9-IBlSH 91B17H Y-IB30H

0.37-0.u 0.38.O.-l3

HSOUI HSO-161 HS050 ! HS060 I H516Ol H81151 H863111 H8615 I H93151 H91171 H9-l-1301

0.42-O 19 0.43.O.SO 0.-!7-051

055-0.65 055-0.65 0.42-0.49 0.27-0.33

O.-EO.-l9 0.12-O I8 0. I-I-O 20 0.27-0.33

0.65-1.10 0.65-1.10 0.65-l IO 0.65-1.10 0.70. I .os 0.60.0.9s 0.70. I .os 0.70-I .os 0.70-I .os 0.70. I .os

0.035 0.035

0.03s 0.035 0.035 0.035

0.035 0.03.i 0035

mately 63 HRC is attainable. As the diameter of the quenched piece is increased. cooling rates and hardness decrease. because the critical cooling rate for this specific steel was not exceeded. Thus. Fig. 3 also serves as an escellent example of a low-hardcnabilitj steel. Plain carbon steels are characterized by their low hardenability, with critical cooling rates lasting only for brief periods. Hardcnability of all steels is directly related to critical cooling rates. The longer the time of critical cooling rate. the higher the hardenability for a given steel. almost regardless of carbon content.

Role of Alloying

composition,

Elements

The principal reason for using alloying elements In the standard grades of steel is IO increase hardenabilitj. The alloying elements used in the standard alloy steels in Table 7 are confined to:(a) manganese. (b) silicon. (cl chromium. cd) nickel, (e) mol) bdenum. and (f) vanadium. Because of the small amounts used, boron is not usually called an alloy. Steels that contain boron. whether they are carbon or alloy grades. are more often termed as boron-treated steels. The use of cobalt. tunps’en. zirconium. and

composition,

% Si

0. I s-o.30 0 IS-O.35 0 IS-O 30 0 15-o 30 0. I S-O.30 0. I s-o. 30 0.15-0.30 0.15-0.30 0. I s-o.30 0.15-O 30 0.15.0.30 0.15-0.30 0. I s-0.30

Ni

0. I S-O.45 O..lS-0.75 0.35-0.7s 0.25-O 6S 0.50 65 0.25-0.6S

Cr 0.3uo.70 0.40-0.60 0.30-0.70 0.13-0.13 0.30-0.70 0.30-0.70 0.60-I MI 0.30-0.60 0.35-0.65 0.35-0.65 0.25-0.55

0.25-0.55 0.2s0.55

MO

0.08-O. IS 0.15-0.25 0. I s-025 0.08-o. IS 0.08-O. IS 0.08-0.15

titanium is generally confined to tool or other specialty steels. Tool steels and other highly alloyed steels are covered in other sections of this book. hlanganese. silicon. chromium. nickel. molybdenum. and vanadium all have their separate and unequal effects on hardenability. However, the individual effects of these alloying elements may be completely altered when two or more of these are used together. In periods of alloy shortages. extensive investigations were conducted. and it has been established that more hardenabilitj can be attained with less total alloy content when two or more alloys are used together. This practice is clearly reflected in the standard steel compositions shown in Table 7. This approach not only saves alloys that x2 often in scarce supply. but also results in more hardenability al lob4 er cost. Therefore. all of the steels listed In Tables 7 and 8 have significantly greater hardenability than the carbon steels listed in Tables 3 to 6. It must be further emphasized that the hardenability varies widely among the alloy grades. which is a principal reason for the existence of so many grades. It is oh\ ious that hardenability is an all important factor in the discriminating selection of a steel grade for heat treated parts. A standard procedure

Carbon & Alloy Steels Introduction

Fig. 3 Effect of Section Size on Surface Hardness of a 0.54 Carbon Steel. Quenched in water from 830 “C (1525 “F)

/ 117

Fig. 5 Method of Developing End-Quench Curve by Plotting Hardness Versus Distance from Quenched End. Hardness plotted every quarter inch for sake of clarity, although readings were taken in increments of one-sixteenth shown at top of illustration

Rockwell inch,

C as

Fig. 4 Standard End-Quench (Jominy) Test Specimen and Method of Quenching in Quenching Jig

for evaluating the hardenability of steels is necessary for initial selection as well as a tool for controlling quality.

Methods for Evaluating

Hardenability

A number of hardenability tests have been devised. each ha\ing its advantages and limitations. Most of these tests are either no longer used or their use is restricted to specialized applications. The endquench test has proved to be the method u ith the highest degree of reproducibility and has thus heen almost universally adopted for evaluating hardenability of virtualI> all standard alloy steels and for some grades of carbon steels. The test is relatively simple to perform and can produce much useful information for the designer as well as for the fabricator. Test Bars for the End-Quench Test. Although \ ariations are sometimes made to accommodate specific requirements, the test bars for the end-quench test are nomlally 25.5 mm (I in.) in diameter b> I02 mm (1 in.) long. A 25.5 mm (I in.) diameter collar is left on one end to hold it in a quenching jig. as illustrated in Fig. -I. In this test. the water flow is controlled by a suitable valve. so that the amount striking the end of the specimen (Fig. -I) is constant in volume and velocib. The Hater impinges on the end of the specimen onI). then drains away. By this means. cooling rates vary from about the fastest possible on the quenched end to very slogs. essentially equal to cooling in still air. on

the opposite end. This results in a u Ide range of hardnesses along the length of the bar. After the test bar has been quenched. tno opposite and flat pamllel surfaces are ground along the length of the bar to a depth of 0.381 mm (0.015 in.). Rocknell C hardnessdeterminations are then madeetery I.588 mm (0.60 in.). A specimen-holding indexing fixture is helpful for this operation for convenience as well as accuracy. Such fixtures are available as accessory attachments for conventional Rocknell testers. The next step is to record the readings and plot them on graph paper IO develop a curve, as illustrated in Fig. 5. Bj comparing the curves resulting from end-quench tests of different grades of steel. their relative hardenability may be established. The steels having higher hardenability will be harder a~ a given distance from the quenched end of the specimen than steels having lower hardcnabilit). Thus, the flatter the curve. the greater the hardenability. On the end-quench curves. hardness is not usually measured beyond approximately 51 mm (2 in.). because hardness measurements beyond this distance are seldom of an! significance. At about this 51 mm (2 in.) distance from the quenched end. the effect of uater on the quenched end has deteriorated. and the effect of cooling from the surrounding air has become signiticant. An absolutely flat txn P demonstrates conditions of very high hardenability \< hich characterize an air-hardening steel such as some of the highI> alloyed tool steels. u hich u ill be discussed later in this book. Variations in Hardenability. Because hardenability is a principal factor in steel selection and because hardcnabilit) varies over a broad range for the standard carbon and alloy steels. many grades are available. As a rule. hardenability of the standard carbon grades is very ION. although there is still a prsar deal of variation in hardenability among the

118 / Heat Treater’s

Fig. 6 End-Quench

Guide

Hardenability

Curve for 1541 Carbon

Fig. 6 Hardenability

Band for an Alloy Steel. 4150H: 0.47 to

0.54 C, 0.65 to 1 .I0 Mn. Normalized nealed at 845 “C (1555 “F)

Fig. 7 Hardenability

Curves for Several Alloy Steels

H and RH Steels Because of the normal variations within prescribed limits of composition. it would be unrealistic to expect that the hardenability of a given grade would always follow a precise curve such as shown in Fig. 6 and 7. Instead. the hardenability of any grade will vary considerably, which results in a hardenability band such as the 1150H hand in Fig. 8. This steel was normalized at 870 “C ( 1600 “F). then austenitized at 8-15 “C ( IS55 “F) before end quenching. The upper and lower curves that represent the boundaries of the hardenability band not only show the possible variation

“F). An-

in hardness at the quenched end, caused by the allowable carbon range of 0.47 to 0.5-t. but also the difference in hardenability as a result of the alloying elements being on the high or low side of the prescribed limits. The need for hardenability data for steel users has been recognized. Cooperative work by AlSl and SAE has been responsible for devising hardenability bands for a large numher of carbon and alloy steels, principally the latter. Steels that are sold with guaranteed hardenability bands are known as the H-steels. The numericaJ parts of the designation are the same as for the other standard grades. but the suffix letter H. such as 4lAOH. identifies it as a steel that will meet prescribed hardenability limits.

Chemical

different grades. This variation depends to a great extent upon the manganese content and sometimes to a smaller extent on the residual alloys which are sometimes present. A hardenahility curve for a high-manganese grade of carbon steel. 1511. is shobn in Fig. 6. This curve represents near maximum hardenability that can be obtained from any standard carbon grade. In contrast to the curve shohn in Fig. 6. typical hardenability curves for four different 0.50 carbon alloy steels are presented in Fig. 7. These data emphasize the fact that maximum attainable hardness is provided by the carbon content. while the differences in alloy content markedly affect hardenability. Hardenability also depends on grain size (i.e.. deoxidation practice) and melting practice (i.e.. BOF vs electric furnace). Electric furnace steel tends to have high levels of nickel. copper. chromtum. and molyhdenum residuals that improve hardenability. On the other hand, fine gained. alummum killed steels (premium grades with respect to formability) have lower hardenability than coarser grained. silicon killed steels.

at 670 “C (1600

Composition

Limits

Not all of the steels listed in Tables 3 to 8 are available as H or RH steels, although most of the alloy steels can be purchased as H-grades. Tables 2. 9. and IO list those carbon and alloy grades which are presently availahle as H or RH steels. In order to give steel producers the latitude necessary in manufacturing for common hardenability limits. the chemical compositions of normal grades have been modified to form the H and RH steels. These moditications permit adjustments in manufacturing ranges of chemical composition. These adjustments correct melting practice for individual plants which might otherwise influence the hardenability bands. However, the modifications are not great enough to influence the general characteristics of the original compositions of the steels. Figure 8 is presented merely as an example of a hardenability band. In the section which follows. the hardenahility bands. if available. are included hith heat treating and other data for individual carbon and alloy steels. Restricted hardenability (RH) steels are defined in SAJZ Jl868. Composition ranges are the same as those for the standard alloy grades. and hardenahility hands are narrower than those for the H grades. For example. 3130 and -II-IO RH have the same specified composition ranges, while -II-IO H has broader ranges. The Jominy hardenability band of4130 RH is about half the width of the -II10 band. RH grades open the door to substantial benefits to the heat treater. A major metalworking company. for instance. had a part forged to four different dimensions. Four different procedures were required to heat treat the parts to a set of common properties. Restrictive steel chemistries eliminated the need for the four procedures and made it possible to consolidate specifrcations. The RH grades also made it possible to design a new specilication that provides Jominy hardenability bands lying with the overlap of tUo older specifications. Over a five year period, this company was able to reduce its material specifications in this manner from a total of 3 I down to nine.

Carbon & Alloy Steels Introduction

Alloying I Elements. Source: Climax Molybdenum

/ 119

120 / Heat Treater’s

Guide

Carbon Plus Grain Size. Source: Climax Molybdenum

Carbon (1000,

Steels

1100,1200,

and 1500 Series)

introduction Carbon steels are now classified in four distinct series, in accordance with the AlSl system of designations: the 1000 series. which are plain carbon steels containing not more than I .OO Mn maximum; the I100 series, which are resulfurized carbon steels; the 1200 series, which are resultiu-ized and rephosphorized carbon steels: and the I500 series. which are high-manganese (up to 1.65) carbon steels and are nonresulfurized. These four series differ in certain fundamental properties, thus justifying the series differentiation. However, in temls of their response to heat treatment, all four series can be discussed in temts of their carbon content, the principal controlling factor in heat treating. Other factors areconsidered for the individual steels on the pages that follow. To simplify consideration of the treatments for various applications. the steels in this discussion are classified as follows: Group I, 0.08 to 0.25 C; Group II. 0.30 to 0.50 C: Group lfl. 0.55 to 0.95 C. A relatively few steels. such as 1026 and 1029. can be assigned to more than one group. depending on thetrcarbon content. Group I(O.08 to 0.25% C). The three principal types of heat treatment used on these low-carbon steels are: (aj process treating of material to prepare it for subsequent operations; (b) treating of finished parts to improve mechanical properties: and t,c) case hardening. notably by carburizing or carbonitriding, to develop a hard, wear-resistant surface. It is often necessary to process anneal drawn products between operations, thus relieving work strains in order to permit further working. This operation is normally carried out at temperatures between the recrystallization temperature and the lower transformation temperatures. The effect is to soften by recrystallization of the grain growth of ferrite. It is desirable to keep the recrystallized grain size relatively fine. This is promoted by rapid heating and short holding time at temperature. A similar practice may be used in the treatment of low-carbon, cold-headed bolts made from cold-drawn wire. Sometimes the strains introduced by cold working so weaken the heads that they break through the most severely worked portion under slight additional stratn. Process annealing is used to overcome this condition. Stress relieving at approximately 540 “C t 1000 “F) is more effecttve than annealing in retaining the normal mechanical properties of the shank of the cold-headed bolt. Heat treating is frequently used to improve machinability. The generally poor machinability of the low-carbon steels. except those containing sulfur or other alloying elements. results principally from the fact that the proportion of free ferrite to carbide is high. This situatton can be modified by putttng the carbide into tts most voluminous form, pearlite. and dispersing tine particles of this pearlite evenly throughout the ferrite mass. Normalizing is commonly used with success. but best results are obtained by quenching the steel in oil from 815 to 870 “C (1500 to 1600 “Fj. With the exception of steels containing a carbon content approaching 0.255,. little or no martensite is formed. and the parts do not require tempering. Group II (0.30 to 0.50% C). Because of the higher carbon content. quenching and tempering become increasingly important when steels of this group are considered. They are the most versatile of the carbon steels. because their hardenability (response to quenching) can be varied over a wide range by suitable controls. Ln this group of steels. there is a continuous change from water-hardening to oil-hardening types. Hardenability is very sensitive to changes in chemical composition. particularly to the content of manganese. silicon. and residual elements, as well as gram size. These steels are also very sensitive to changes in section.

The medium-carbon steels should be either normalized or annealed before hardening in order to obtain the best mechanical properties after hardening and tempering. Parts made from bar stock are frequently given no treatment prior to hardening (the prior treatment having been performed at the steel mill). but it is common practice to normalize or anneal forgings. These steels. whether hot Fished or cold finished, machine reasonably well in bar stock fomt and are machined as received, except in the higher carbon grades and small sizes that require annealing to reduce the as-received hardness. Fotgings are usually normalized to improve machinability over that encountered with the fully annealed structure. These steels are widely used for machinery parts for moderate duty. When the parts are to be machined after heat treatment, the maximum hardness is usually held to 320 HB and is frequently much lower. In hardening. the selection of quenching medium will vary with the steel composition. the design of the part. the hardenability of the steel, and the hardness desired in the finished part. Water is the quenching medium most commonly used. because it is best known and is usuaUy least expensive and easiest to install. Caustic soda solution (5 to 10% NaOH) is used in some instances with improbed results. It is faster than water and may produce better mechanical properties in all but light sections. It is hazardous, however. and operators must be protected against contact with it. Salt solutions (brine) are often successfully used. They are not dangerous to operators. but their corrosive action on iron or steel parts or equipment is potentially serious. When the section is light or the properties required after heat treatment are not very high. oil quenching is often used. Finally, the medium-carbon steels are readily case hardened by flame or induction hardening. Group Ill (0.55 to 0.95% C). Forged parts made of these steels should be annealed because: l

l

Refinement of the forged structure is important in producing a high quality, hardened product The parts come from the forging operation too hard for cold trimming of the flash or for any machining operations

Ordinary annealing practice. followed by furnace cooling to approximately 600 “C t I I IO “F) is satisfactory for most parts. Hardening by conventional quenching IS used on most parts made from steels in this group. However. special techniques are required at times. Both oil and water quenching are used: water. for heavy sections of the lower carbon steels and for cutting edges: oil. for general use. Austempering and martempenng are often successfully applied. The principal advantages of such treatments are considerably reduced distortion, elimination of breakage. and. m many instances. greater toughness at high hardness. Tools with cutting edges are sometimes heated in liquid baths to the lowest temperatures at which the part can be hardened and are then quenched in brine. The fast heating of the liquid bath plus the low temperature fail to put all of the available carbon into solution. As a result. the cutting edge consists of martensite containing less carbon than indicated by the chemical composition of the steel and containing many embedded particles of cementite. In this condition. the tool is at its maximum toughness relative to its hardness, and the embedded carbides promote long life of the cutting edge. Final hardness is SS to 60 HRC. Steels in this group are also commonly hardened by Flame or induction methods.

122 / Heat Treater’s

Guide

Effect of mass and section size on cooling curves obtained for the water quenching of plain carbon steels

Carbon

Steels (1000, 1 100,1200,

Effect of mass and section size on cooling curves obtained for the oil quenching of plain carbon steels

and 1500 Series) / 123

124 / Heat Treater’s

Guide

Influence of tempering temperature on room-temperature

hardness of quenched carbon steels

Carbon

Influence of tempering temperature on room-temperature

Steels (1 000, 1 1 00.1200,

and 1500 Series) / 125

hardness of quenched carbon steels (continued)

126 / Heat Treater’s

Guide

Room-temperature hardness of three carbon steels after production tempering. (a) Automotive steering-arm forgings made of fine grain 1035 steel. Section thickness varied from 16 to 29 mm (5/8to 1 ‘/sin.). Forgings were austenitized at 625 “C (1520 “F) in oil-fired pushe conveyor furnace, held 45 min. quenched in water at 21 “C (70 “F), and tempered 45 min at 560 to 625 “C (1080 to 1160 “F) in oil-fired link belt furnace to required hardness range of 217 to 285 HB. Hardness was checked hourly with a 5% sample; readings were taken on polishec flash line of 29 mm (1 l/s in.) section. Survey of furnace revealed temperature variation at 605 “C (1120 “F) of 8, -4 “C (15, -7 “F). Data rep resent forgings from four mill heats of steel and cover a 6-week period. (b) Woodworking cutting tools forged from 1045 steel. Section o cutting lip was hardened locally by gas burners that heated the steel to 815 “C (1500 “F). Tools were oil quenched and tempered at 305 tc 325 “C (585 to 615 “F) for 10 min in electrically heated recirculating-air furnace to a desired hardness range of 42 to 48 HRC. Data wen recorded during a g-month period and represent forgings from 12 mill heats. (c) Plate sections, 19 to 22 mm (3/d to 7/8 in.) thick, of 1045 stee were water quenched to a hardness range of 534 to 653 HRB and tempered 1 h at 475 “C (890 “F) in continuous roller-hearth furnaces. Dat: represent a e-month production period. (d) Forged 1046 steel heated to 830 “C (1525 “F), and quenched in caustic. Forgings were heater in a continuous belt-type furnace and individually dump quenched in agitated caustic. Forgings weighed 9 to 11 kg (20 to 24 lb) each; maxi mum section, 38 mm (1 l/2 in.). (e) As-quenched forged 1046 steel shown in (d), tempered at 510 “C (950 “F) for 1 h. (9 As-quenched forget 1046 steel shown in (d), tempered at 525 “C (975 “F) for 1 h. Average hardness data for all but (c) obtained by calculating average of higt and low extremes of hardness specification range for each batch.

Carbon

Steels (1 000, 1 100,1200,

and 1500 Series) / 127

1062: Heat-to-Heat Variations in Depth of Hardness. Heat-to-

heat variations in depth of hardness among three heats. Hubs were flame hardened on the inside diameter to a minimum of 59 HRC at 1.9 mm (0.075 in.) below the surface. Parts were heated 12 s and quenched in oil. Hardness was measured on cross sections of heated area.

1052 and 1062: Flame hardening hubs. Distribution of dimensional change as a result of flame hardening. (a) Change in pitch diameterof converter gear hubs made of 1052 steel. Gear teeth on inside diameter were heated for a total of 9.5 s. before being quenched in oil to provide a depth of hardness of 0.9 mm (0.035 in.) above the root. (b) Close-in of inside diameters of converter hubs made of 1062 steel. Inside diameter was heated for a total of 12 s and then oil quenched to harden to 59 HRC min at a depth of 1.9 mm (0.075 in.) below the surface. Inside diameter was finish ground after hardening.

128 / Heat Treater’s

Guide

1018 and 1024: Gas carburizing.

Effect of tempering 4.5 h, then oil quenched and tempered.

on hardness of 1018 and 1024 steel. Parts were carburized

at 925 “C (1700 “F) for

Carbon

Effect of time and temperature on case depth of liquid carburized steels

Steels (1000, 1 1 00,1200,

and 1500 Series) / 129

130 / Heat Treater’s

Nitriding

Guide

Carbon Steels. Effect of carbon content in cation

steels on the nitrogen gradient obtained in aerated bath nitriding

Typical Steels

Normalizing

Temperatures

for Standard

Carbon

Ikmperatore(a) Grade Plain carbon steels lOIS I020 1022 102.5 I030 1035 IO-IO IW5 IO50 1060 1080 1090

IWS 1117 1137 II-II II-U

“C

OF

915 915 915 900 900 885 860 860 860 830 830 830 835 900 885 860 860

167.5 1675 I675 1650 1650 1625 1575 1575 1575 lS25 1525

1575 1550 1650 1625 1575 1575

(a) Based on production experience. normalizing temperature may vary from as much as 27 “C (50 “F) beloa. to as much as 55 “C ( IO0 “F) above. indicated temperature. The steel should be cooled in still air from indicated temperature.

Properties AM grade(a) 1015

1020

I022

1030

IWO

IOSO

1060

I080

1095

III7

III8

1137

of Selected

Carbon Steels in the Hot-Rolled,

Condition ortreatment As-rolled Normalized at 9’S “C ( I700 T) Annealed at 870°C ( 1600 “Fj As-rolled Normalizedat 87O”C( 1600°F) Annealed at 870 “C ( I600 “FJ As-rolled Normalized at 925 “C ( I700 OF) Annealed at 870 “C ( I600 “f? As-rolled Normalized at 9’S & “C ( I700 “F) Annealed at &t5 “C ( I S50 “F) As-rolled Normalizedat9OO”Ct 1650°F) Annealed at 790 “C ( 1150°F) AS-ldkd Normalized at 900 “C ( 1650 “F, Annealed at 790 “C ( I -ISO “R As-rolled Normalized at 900 “C t I650 “F) Annealed at 790 “C ( 1150 “F) As-rolled Normalizedat 900°C (165O”F1 Annealed at 790 “C ( 1450 “F)

As-rolled Normalized Annealed at As-rolled Normalized Annealed at As-rolled Normalized Annealed at As-rolled Normalized Annealed at

at 900 “C ( I650 “F) 790 “C ( 1450 “F) at 900 “C ( 1650 “FJ 860 “C ( IS75 “F) at 925 “C ( 1700°F) 790 “C ( I150 OF) at 900 “C (1650°F) 790 “C ( l-l.50 “FJ

Tensile strengtb ksi MPa 420 -125 385 150 UO 395 SOS 185 450 5.50 525 160 620 995 520 725 750 635 815 775 625 964 1015 615 965 lOIS 655 190 -170 130 525 -175 150 625 670 985

61 62 56 65 64 57 73 70 65 80 76 67 90 86 7s 10s 109 92 II8 II3 91 I-IO 117 89 I10 117 95 71 68 62 76 69 65 91 97 as

Normalized,

Keld strength k5i MPa 315 325 285 330 31s 29.5 360 360 31s 315 345 3-15 -l15 370 350 415 130 365 385 3’0 370 585 s2s 380 570 so5 380 SOS 305 28.5 315 315 285 380 -loo 34s

46 -I7 JI -I8 50 43 52 52 46 SO SO SO 60 5-l 51 60 62 53 70 61 4-l 8S 76 59 83 73 55 4-t 4-l -II -WA -I6 -II 55 58 50

and Annealed

Conditions q ardness,

Elongation(b),

Reduction in area, 9%

HB

Imd impact strength ft. Ibf J

61 70 70 59 68 66 67 68 6-l 57 61 58 SO 5.5 57 10 39 -IO 3-l 37 38 17 21 -IS I8 I-l 21 63 s-1 58 70 66 67 61 -19 s-l

I36 121 III l-13 I31 III 149 I13 I37 179 l-I9 I26 201 170 lJ9 229 217 I87 Yl 229 179 293 293 171 293 293 I92 143 137 121 119 I13 I31 192 197 17-l

III I15 II5 87 II8 I23 81 117 121 75 94 69 49 65 35 31 27 I8 18 I-l II 7 7 7 3 5 3 81 85 94 lo9 103 107 83 63 SO

39.0 37.0 37.0 36.0 35.8 36.5 35.0 B-I.0 35.0 32.0 32 0 312 2s 0 28.0 30.2 20.0 23.7 17.0 I8.O 22.5 17.0 I I.0 23.7 9.0 95 13.0 33 0 33.5 32.8 32.0 33.5 31.5 28.0 22.5 26.8

4%

82 85 85 64 87 91 60 87 89 55 69 51 36 48 33 23 20 I3 13 IO 8 5 5 5 3 ‘I 2 60 63 69 80 76 79 61 17 37

Carbon

Properties AlSl grade(a) 1141

114-l

of Selected

Carbon Steels in the Hot-Rolled,

Condition or treatment

field strength ksi MPa

Tensile strength MPa ksi

As-rolled Normalized at 900 “C ( 1650 “Fj Annealedat81S°C(ISOO”F) As-rolled Normalized at 900 “C ( 16.50 “F) Anneakd at 790 “C ( I-150 “R

675 710 600 705 670 585

Normalized,

98 103 87 102 97 89

360 40s 3.55 420 ml 31.5

Steels (1000, 1 1 00,1200,

and 1500 Series) / 131

and Annealed

Conditions

Elongation(b),

Reduction in area, %

Hardness. RB

38 56 19 -II 40 JI

192 201 163 212 197 167

52 59 51 61 58 50

?O

22.0 22.7 25.5 21.0 21.0 24.8

(continued) Imd impact strength B Ibf J II 53 34 53 43 65

8 39 25 39 32 18

(a) All grades PIE tine grained except for those in the I 100 series. m hich are coarse grained. (h) In SO mm or 2 in.

Effect of Mass on Hardness Alloy Steels

Grade

Normalizing temperature “F “C

Carbon steels, carburizing lOIS I020 1022 III7 III8

92s 92s 92s 900 925

92s 900 900 900 900 900 900 900 900

Critical

Temperatures

5w.a

I26 I31 1.43 I43 IS6

IZI I31 I13 137 I13

II6 I26 137 I37 137

II6 I21 I31 I26 131

l5b 183 223 229 293 302 201 207 201

l-+9 170 217 229 293 293 197 201 197

137 167 212 223 285 ‘69 197 XI I92

137 167 201 223 269 ‘55 192 201 I91

heats

Carbon Steels

Steel

Critical temperatures on beating at 28 “C/h (50 OF/h) ACI ACJ OF T OF T

1010 I020 I030 I040 1050 1060 1070 1080

72s 725 72s 725 72s 72s 725 730

I335 1335 133s 1335 133s 1335 1335 I315

875 845 815 795 770 745 730 735

1w4

grades

1700 1650 l6SO 1650 1650 1650 1650 1650 1650

for Selected

231)

13(‘4

grades

Note: AU data are based on male

Approximate

Carbon and

Hardness, HB, for bar with diameter, mm (in.), of

1700 1700 1700 1650 I700

Carbon steels, direct-hardening 1030 1040 1050 1060 lo80 1095 1137 I I-II II-U

of Normalized

1610 ISSS I-195 I460 111s I375 I390 13%

Critical temperatws h-3 OF OC 850 815 790 75s 740 72s 710 700

I560 I SO0 I -Is0 139s I365 I%+0 1310 1290

on cooling at 28 OC/b (SOOF/b) h “C OF 680 680 675 670 680 685 690 695

1260 1260 I250 I240 1260 I 265 I275 I280

132 / Heat Treater’s

Recommended

Guide

Temperatures

and Cooling

Cycles for Full Annealing

of Small Carbon Steel Forgings

Data are for forgings up to 75 mm (3 in.) in section thickness. Time at temperature thick; l/2 h is added for each additional 25 mm (1 in.) of thickness.

usually is a minimum of 1 h for sections up to 25 mm (1 in.)

Cooling cycle(a) Annealing temperature T OF

Steel

ass-900 aswoo aswoo ass-900 84s.88s 845-8x5 790.870 790-870 790-870 790-84s 790-84s 790-84s 790.830 790-830

lo18 I ox IO22 lo25 1030 1035 IO4O IONS 1050 lO6O I070 I 080

(a) Fumasecoolingar

OF

T

1575-1650 lS7S-1650 lS7S-1650 ls75-1650 1550-162.5 ISSO- I625 IJSO-IhOO 1X50- I600 l-150-I600 l-150- I550 IGO- 1550 1150-1550 1150-1525 11so-IS25

From

To

From

ass ass 855 85s 845 84s 790 790 790 790 790 790 790 790

70s 700 700 700 6.50 650 650 650 650 6SO 650 650 6SO 655

IS75 IS75 IS75 IS75 IS50 ISSO 1150 l-150 1150 1150 l-Pi0 I450 14.50 1450

To

Eardness range, FIB 111-119 Ill-149 111-119 Ill-187 126-197 137-207 137-207 156.217 156-217 156-217 167-229 167-229 167.229 167-219

28”C/h(5O”F/h)

Approximate Grossmann Quenching Severity Factor of Various Media in the Pearlite Temperature Range Circulation or agitation

Brine

None Mild hlodersre GOOd Strong Violent

Grossmann

Numbers

2 -7-7-.- 7

hater

and Film Coefficients

32

90

55

130

F&I oi I

60

I10

2%

13

II0

polp\ rn) I py-rolidone

Conventional hlancmpering Air

oil oil

69 I so 77

09-1.0 1.0.I.1 1.2-I.? I-l-l.5 I 6-2.0 -I

5

Quenchant temperature “F T

Quenchant

Grossmann quench seberityfactor, Water Oil and salt

150 300 80

for Selected

0.25-o 30 0.30-0.3s 0.35-O 10 0.40 5 0 S-O.8 o.a-I.1

Air 0.01

Quenchants

Quenchant belocih ft/min m/s 0.00 0.25 0.51 0.76 0.00 0.25 03 I 0.76 0.00 0.3 0.5 I 0.76 0.00 0.25 0.5 I 0.76 0.51 0.5 I 0.00 2 s-l 5 ox

H

0 50 loo IS0 0 SO IO0 I50 0 50 loo IS0 0 50 loo I so loo loo 0 500 I ooo

Grossmann number, (H=h/2k)

I.1 21 1.7 2.8 0.2 0.6 I5 2.-l 0.s I .o I.1 I.5 0.8 1.3 I .s 1.8 0.7 I.2 0.05 0.06 0.08

Effectke fdm coefficient w/m2 K Btu/ft’ h OF so00 9ow

880

I’OMI 12OOO IO00 2500 6500 IO5oo xoo -1500 sooo 6500 3.500 6GOO 6500 7500 3ooo sooo 200 250 350

2100 2100 la0 440 Iloo 1x50 350 790 880 I200 620

II00 1100 I300 530 880 3s 44 62

Carbon

Comparison of the Cooling Power of Commercially Magnetic Quenchometer Test Results

Oil sample

Types of quenching oil Conventional

Fcljt

Martempering.

without speed improvers

Martempering.

with speed irnprobers

(a) SW

Saybolt universal

Comparison to Magnetic

Typical

Grade

Viscosity at 40 T (1~W SUS(a)

Quenching

105 107 so 9-t 107 II0 I20 329 719 ‘550 337 713 2450

“C

OF

190 19.5 I 70 l-t.5 170 190 ias 190 23s 245 300 230 2-15 300

37s 380 340 290 33s 37s 370 375 45s 475 575 150 475 570

and 1500 Series) / 133

Oils According

to

Quenching duration from 885 T (1625 “I9 to 355% (t i70°F),s At 27OC (80 OF) At 120°C ( 2soT) Chromized Chromized Ni-ball Ni-ball Ni-ball Ni-ball 12.5

‘7.2 27.9 24.8 (a) IS.0 17.0 19.6 17.8 27.6 19.0 32.0 fbl 179 17.0

17 a 16.0 7.0 9.0 lo.8 12.7 13.3 19.2 26.9 31.0 IS.3 16.-l 19.7

la.4 25. I 31.7 12.8 IA.0 IS.1

2’. I 30.4 32.8 (hJ IS.6 IS.4

seconds. fb) Not a\uilahlc

of the Ranges of Cooling Power of Commercially Available Quenchometer Test Results using Pure Nickel Balls

Hardnesses

of Various

Quenching

Quenchingduration from885T At 120 ‘T (250 OF)

At 65 T (15OT) Id.22 7-l-t 18-3-l I420

L+ithout speed imprmers with speed improvers

Carbon content, %

and Mat-tempering

Flash point

IO?.

I 2 3 3 5 6 7 8 9 IO II I’ 1; II

‘@pe of quenching oil Conventional Ftisl Martempering, Martempeting.

Available

Steels (1000, 1100,1200,

(1625T)

and Martempering to355”C At 175°C

Oils According

(670 “F), s At 23oT

(350 “F)

(450 “F)

21-38 16-27

47 =33

I-t-22 7-14

ix-34 13.18

Carbon Steels after Tempering Hardness, ARC. after tempering for 2 h at

205 “C

260 T

315-x

370 “C

425T

48oT

595 T

650 OC

(400°F)

(500°F)

(6OOW

(7OO’T)

@OO°F~

(900°F)

(MOOoF)

540-T

(1100°F)

(12OO’=F)

Heat treatment

Normalized at 900 “C ( I650 “Ft. water quenched From 830-845 “C t 1525 I SSO “FL averuae de\s point. I6 “C (60 “F)

Carbon steels, water hardening I030

0.30

50

15

43

39

?I

28

25

22

9Sta)

I040 1050 1060

0.40 0.50 0.60

51 S? 56

48 50 SS

46 16 so

11 4-l 42

37 10 38

30 37 37

27 31 SS

22 29 33

943, 22

I 080 109s II37

0.80 0.95 O.-lo

S7 58 4-l

55 57 12

so 52 -IO

13 -17 37

-II 43 33

10 12 30

39 -II 27

38 10 ‘I

3’ ;; 91111)

II-II 11-l-l

0.40 0.40

19 5s

46 50

43 -17

-II 45

38 39

31 32

28 ‘9

23 25

94at 97ta1

Data uere obtained on 25 mm r I in.) buts adequately

quenched to drielop

full hurdnrss. ISI Hardness. HRB

26

Normalized ut 885 “C I 1625 “Ft. water qucnchrd from 800-S IS ‘T ( 1175. lSOO°Ft; aberage dea potnt. 7 “C (-IS “F)

Nomtalizcd at9OO‘C t 1650°F). \raterqucnched from 830-855 ‘T t I S?S- I575 “FL average dew point 13Tt.55 “F)

134 / Heat Treater’s

Guide

Carbon Steels: Typical

Austempering

Applications

Parts listed in order of increasing section thickness

Part

Maximum seclion thickness l22Ul in.

Steel

Parts per unit weight lb kg

Salt temperature OC OF

Immersion time, mia

Eardness, ERC

Plaii carbon steel parts Clevis Follower arm Sp-ing PhUe Cam lever Plate -bPc~ Tabulator stop Lever Chain link Shoe-last link Shoe-toe cap Lawn mower blade Lever Fastener Stabilizer bar Boron steel bolt

IO50 IO50 1080 1060 1065 1050 106s 106s IOSO 1050 1065 I070 1065

3.18 6.35 I9 6.35

107.5 1060 1090 IOBZO

Typical Operating Section size mm in.

0.75 0.75 0.79 0.81 I .o I .o I .o I .I?:! I .2s I .s I .s I.5 3.18

Conditions

Material

0.030 0.030 0.03 I 0.032 0.040 0.010 0.040 0.048 0.050 0.060 0.060 0.060 0 12s

77olkg 412/kg 22Olkg 88/Q

0.125 0.250 0.750 0.250

wkg IlO/kg 22 kg lOOIkE

for Through

Frequency(a), Ez

Power(b), kW

3SO/lb I87Iib lOO/lb

4011b

62Jh

28Ilb ‘A lb 6-Vlb

0.5 kg 14lnig -uokg

2oonb

s73lkg 86Aig l8nig 1.5 kg

Hardening

39nb 8/lb ?, lb llnb

SO/lb IO lb

Jsnb

360 35s 330 330 370 360 370 360 34s 34s 290 31s 31s

680 675 625 630 700 675 700 680 650 650 550 600 600

IS IS I5 6 IS I5 IS IS IS IS 30 60 IS

42 42 48 45-W 42 42 42 4s 45-50 45 52 so so

385 310 370 420

725 590 700 790

5 25 6-9 5

30-3s 50 40-45 3843

Carbon Steel Parts by Induction

Process

Total beating time, s

Scao time s/cm Sri.

68.4 28.8 98.8 -14.2 11-l 51

0.71 0.71 I .02 I .03 I.18 I.18

I.8 I.8 2.6 2.6 3.0 3.0

7s 620 70 620 7s 620

I65 II50 160 II50 I65 II50

620 955 620 95s 620 955

II50 I750 II50 I750 II50 17.50

II3 II3 I41 I41 IS3 I53

250 250 311 311 338 338

0.085 0.054 0.057 0.053 0.050

II.3 IS 28 5 26.3 36.0

0.59 0.79 I SO 1.38 1.89

I .s 2.0 3.8 3.5 1.8

20 20 20 20 20

70 70 70 70 70

870 870 870 870 870

1600 1600 1600 I600 1600

lU9 IS76 1609 IS95 1678

3194 3474 3548 3517 3701

0.361 0.319 0.206 0.225 0.208

2.33 2.06 I .33 I.45 I .34

0.94

2.4

20

70

885

162.5

2211

4875

0.040

0.26

Work temperature Entering coil Leaving coil OC ‘=F “C “F

Production rate lb/h kslb

Inductor input(c) kW/cmz kW/i&

Rounds I9

‘4

1035 mod

25

I

lo-11

29

I ‘Ix

1041

I80 9600

%? 34 ‘4 I I ‘/8

1038 1038 1043 1036 1036

3000 3000 3000

300 332 336 304 311

3OQO

580

28.5 20.6 33 19.5 36 19.1

Flats I6 I9 12 25 29

Irregular

shapes

17.5-33

“/16-1Vlb

1037 mod

25-l

Ia) NOW use ofdual frequencies for round secuons. (b) Po\rer transmitted by the inductorat the operaung frequency mput IO the machine. because of losses within the machine. (c) AI the operating frequency of the inductor

indicated.

This poner is approximarely

2%

less than the power

Carbon

Operating

and Production

Section size in. mm

Material

Data for Progressive

Frequency, Ez

Power(a), kH

Induction

Total beating time, s

Steels (1000, 1 1 00,1200,

and 1500 Series) / 135

Tempering

Scan time s/cm Sri.

Work temperature EnbXillg Leaving coil coil T OF “C “F

0.71 I .02 I.18

I.8 2.6 3.0

so so SO

I’0 I20 I20

510 565 565

0.59 0.79 I SO I.22 1.57

I .s 2.0 3.8 3.1 4.0

40 40 40 -lo 40

IlKI 100 IO IO0 100

290 315 ‘90 290 290

0.94 0.67

2.-l 1.7

65 65

I50 IS0

550 -125

Production rate lblh kP

Inductor input(b) kW/cm2 kW/ii.’

Rounds I9 2s 29

% I I Vs

1035 mod 1041 1041

9600 9600 9600

12.7 18.7 20.6

% % ‘4 I I ‘/x

1038 I038 1043 IoJ3 1043

60 60 60 60 60

88 100 98 85 90

1037 mod 1037 mod

9600 9600

I92 IS-l

30.6 44.2 51

950 IO50 1050

II3 I41 IS3

30 311 338

0.050 0.054 0.053

0.32 0.35 0.34

I449 IS76 I609 I365 l-183

3194 3171 3548 3009 3269

0.014 0.013 0.008 0.011 0.009

0.089 0.08 I 0.050 0.068 0.060

2211 2276

-1875 SO19

0.043 0.040

0.28 0.26

Flats I6 I9 22 25 29

123 16-l 312 25-l 328

SW 600 990 SSO 550

Irregular shapes 17.5-33 17.529

)‘/)e-15/)b )&-I l/x

64.8 46

(a) Power transmitted by the inductor ar the operating frequency indicated. For convened because of losses within the machine. (b) AI the operating frequency of the inductor

1062: Preliminary

Spot Flame Hardening

of a Free-Wheel

this power is approximately

254

less than the power inpur to the machine,

Cam Hardness and pattern aim

operation

Turn on water. air, oxygen. power. and pmpane. Line pressures: water. 205 kPa (30 psi); air, 550 kPa (80 psi): oxygen. 82S kPa ( I20 psi): propane. 205 kPa (30 psi ). Ignite piloa.

Loading and positioning Mounr cam on flame head. Cam positioned on locating plaw and MO wear pads. and against three locating pins lhar are imegral pans of flame head. Disurnce from flame head to cam surface. appmximalely 7.9 mm &)r, in.)

Cycle start and heating cycle Propane and oxygen solenoid valves open (oxygen flow delayed slightly). Mixture of propane and oxygen ignited a1 flame heads hy pilots. Check pmpane and oxygen pressures, Adjust flame by regulating pmpane. Heating cycle controlled by timer. lime predetermined toobtain specilied hardening depth. Propane and oxygen solenoid valves close (propane flow delayed slightly). Ejector plate (air operated) advances and suips cam horn flame head. Propane regulaled pressure. I25 kPa ( I8 psi); oxygen regulated pressure, 585 kPa (89 psi ): oxygen upsu-eam pressure. 425 kPa (62 psi); oxygen dounstream pressure. I IO kPa ( 16 psi). Flame velocity (approximate). I35 m/s (-150 ft/s). Gas consumption (approximate): pmpane. 0.01 m3 (0.4 ft3) per piece: oxygen. 0.04 m3 ( I .3 ft3) per piece. Total heating time. I I s Flame pm design: nine ports per row; eight mws; port size. No. 69 (0.74 mm. or 0.0292in.).whhNo.S6(1.2 mm.orO.O-%Sin.)counterbore

Quench cycle Cam drops into quench oil. is removed from tank by conveyor. S.6”C( l30f 10°F). Tie inoil (approximate), 30s

frequencies.

I020 800

Oil lemperarure.

S-1f

Hardness. 60 HRC minimum ar surface and 59 HRC minimum al adepth of I .3 mm (0.050 in.) below surface. for\sidrh of 8.8 mm (0.345 in.) on cam rollersurface. Dimemions below gven in inches

136 / Heat Treater’s

Guide Gas Carburizing:

Flame Hardening

Response

of Carbon Steels

Material

‘Qpical hardness, ERC, as affected by quenchant Air(a) Water(b) OW)

Steel

Carburized

SO-60 55-62

Q-S8 58-62 58-62

-15-55 so-55

52.S7lC) SS-60

33-50 55-60 60-63 62-65 IS-55 55-62 58-6-l

1010 1018 1019 1020 1021 IO’.! 152-l IS17

62-65 62-65

Resulfurized

grades of plain carbon steels(d)

1010-1020 1108-1120

Steel Compositions Composition, % Ni Cr

C

Mn

0.08-0.13 0.15-O 70 0. IS-O.20 0.1X-0.23 0.18-0.23 0.18-0.23 0 19-O 25 0’1-029

0.30-0.60 0.60-0.90 0.70-I .OO 0.30-0.60 0.60-0.90 0.70-1.00 1.3.31-1.65 1.20-1.50

MO

Other

:::

la).(b) (a).(b) (a). lb) (a). fb) W.(b) (a). fb) (a,.(b)

Carbon steels

Plain carbon steels 102S- 103s IcU@lost~ 10.55-1075 1080-1095 11~5-1137 1138-114-l II46llfil

Carburizing

5X-61

50-b0 SO-60

60-63

III7

:::

.._

_..

(a).(b)

steels 0.140’0

100-l

30

0.08-o. I3 S

tat Toobtain the hardness results indicated. those areas not dtrestly heated must be kept relatively cool during the heating process. tbl Thin sections are susceptible to cracking when quenched utth oil or water. tc) Hardness is slightly lower for material heated h) spinningorcombination progressike-spinning methods than it is for material heated by progresstbe or stationq methods. (di Hardness values of carburized cases containing 0.9oto I.IOQC

Effect of Cyaniding

Temperaturesand

Time on Case Depth and Carbon and Nitrogen

Contents

Material thickness, 2.03 mm (0.080 in.); cyanide content of bath, 20 to 30% Case depth after cjaniding steel

Anal)& after 100 min at temperature(a) Carbon, % Nitrogen, %

for:

15 min

100 min

mm

in.

mm

in.

0.038 0.038 0.05 I

0.0015 0.001s 0.0020

0.152 0.151 0.203

O.OOb 0.006 0008

068 0.70 cl.7L

0.5 I 0.50 051

0.076 0.076 0.089

0.0030 0.0030 0.0035

0.203 0.203 0.3-l

0.008 0.008 0.010

0.75 0.77 0.79

0.26 0.28 0.27

Cyanided at 76O’C (1400 “F) 1008 IOltl 1022

Qanided 1008 I010 IO’2

at 845 OC (1550 OF)

tat Carbon and nitrogen contents were determined

from analysis of the outermost

0.07b mm 10.003 in. J of cytnidsd

cases.

Carbon

Liquid Carburizing Typical application

Carbon Steels in Cyanide

of carbon steel and resulfurized Weight

Part

Steels (1000, 1100,1200,

and 1500 Series) / 137

Baths

steel Depth of case mm in.

Temperature T OF

kg

lb

Steel

0.9 0.5 0.7 3.5 I.1 I .-I 0.03 0.09 09 1.75 0.05 0.007 0.007 0.7 0.15 7.7 0.05

2 I.1 1.5 7.7 2.5 3 0.06 0.’ 2 10,s 0.12 0.015 0.015 I .b I 17 0. I

CR 1020 CR IO20 CR I020 1020 ION CR 1020 1020 1018 1010 CR IO20 CR IO22

I .o I.5 I.5 1.3 1.3 I.3 0.1-0.5 I .s I .o 1.3 0. I3-0.25 0.13-0.2s 0.25-0.-l I.5 I .s 1,s 0.02-0.0.5

0.040 0.060 O.ObO 0.050 0.050 0.090 0.0 I s-o.020 0.060 0.040 0.0.50 0.005-0.010 0.00.5-0.010 0.010-0.015 0.060 0.060 0.060 0.00 I-O.002

940 940 910 940 910 910 81.5 940 910 940 8-15 845 81S 940 940 910 900

I720 I720 1720 I720 I720 I720 ISSQ I720 I720 I720 IS50 1550 1550 I770 17’0 17’0 1650

0.0-l 3.6 0.0009 3.6 02 0.0-l O.W3 0.007 0.31 0.0 I 0003 0.08 0.009 0.9 0.007 0.02 O.-IS 0.007

0.09 8 0.00~ 8 0.5 0.09 0.007 0.015 0.75 0.03 0.007 0.18 0.02 2 0.015 0.05 I 0.015

III8 III7 III8 III7 III7 III3 III9 III3 III3 III8 Ill.7 III8 III8 III7 III8 III7 III7 IIIX

03-0.4 I.1 0. I3-0.25 I.1 0.7.s 0. I3-0.25 0 I3-0.25 0.0750. I3 O.I.w.25 0.x-0.1 0.075-0. I3 0.25-0.-l 0.x-o -I I.1 0.13~0.2s I.3 I.1 0.3-0.-l

0.0 I o-0.0 IS 0.045 0.005-0.010 0 015 0.030 0.005-0.010 O.WS-0.010 O.W3-0.005 o.ws-0.010 0010-0015 O.W3-0.005 0.0 I o-o.0 IS 0.010-0015 0.045 0.005-0.010 0.050 0.0-1s 0.010-0.015

8-15 915 845 91s 91.5 845 815 I345 81.5 8-15 845 8-lS 8-15 925 Y-IS 91s 91s 845

I550 1675 I SSO 1675 lb75 I SSO IS50 ISSO I550 I550 I SSO IS.50 I SSO I7W ISSO 1675 I675 ISSO

Time, h

Quench

Subsequent treatment

Eardness, ERC

Carbon steel Adapter Arbor, tapered Bushing Die block Disk Flange Gage rings. knurled Hold-down block fnsen.tapered Lever Link Plate Plllg Plug gage Radius-cutout roll Torsion-barcap

-I 6.5 6.5 5 5 5 1 b.5 -I 5 I I 7 65 6.5 6.5 0.1’

AC 4C AC AC AC

62-63 62-63 62-63 62-63 59-6 I 56-57 55 mm(d) 62-63 62-63 62-63 (e)

(b) Oil AC AC and slightly low compared with the grades of carbon steel used for most carburizing applications. Excellent forgeability reasonabll good cold formability and excellent weldabilit>. Machinablhty is relativeI> poor compared with the II00 and I200 grades Forging.

Heat to I290 “C (2355 “F). Do not forge below 93 “C ( 1695 “F)

Recommended Normalizing.

Heat Treating

Heat to 93

“C t 1695 “F). Air cool

Annealing. Heat to 885 “C (1625 cooler or by furnace cooling Hardening.

Practice

‘F). Cool

slowly,

preferably

in a

hln\ be case hardened b! carburiring. (See procedure for 1020.) hlore often.-it is subjected to light case hardening by a&o&riding or casing in a liquid bath. (See procedure for 1008 steel.) Flame hardening is an alternative process. In man! instances. forgings of this grade are used m serwce either as forged or as k~rgsd and normalized

Nonresulfurized

Carbon

Steels / 145

1017 Chemical Composition. AISI 0.60 Mn. 0.040 P max. 0.050 S mnx Similar

and UNS:

0. IS IO 0.X

c. 0.30

to

Steels (U.S. and/or Foreign). UNS Glol70: ASTAl A 108, ASIO. ASl3, AS 19, A544. A549. x575. A576. A659: hllL SPEC MIL-S-ll3lO(CS 1017);SAE5303.5412.5-113;Ger.)DIN I.I14I;(Fr.) AFNORXC lS,XC l&tJap.)JISS 1SC.S 17C.S liCK:(Swrd.)SS,; I370

Characteristics. Escellrnt forgeahility. reasonably good cold forrnability and excellent \~eldabilit>. As carbon content increases. strength also increases. accompanied b> ;1 small decrease in cold formability. Machinnbilit> IS relativeI> poor comparsd with the II00 and I200 grades Forging.

Heat to 1275 “C (2329 ;F). Do not forge below 910 “C (I670 “F)

146 / Heat Treater’s

Recommended Normalizing.

Guide

Heat Treating

Heat to 885 “C (I625

Annealing. Heat to 885 “C (I625 cooler or by furnace cooling Hardening.

Practice

1017 Hardness erage

OF). Air cool “F). Cool

slowly,

preferably

m a

May be cnse hardened hy carburizing. (See procedure for 1020.) More often, it is subjected to light case hardening by carbonitriding or casing in a liquid bath. (See procedure for 1008 steel.) Flame hardening is an alternative process. In many instances. forgings of this grade are used in service either as forged or as forged and normalized

based

vs Tempering

on a fully quenched

Temperature. structure

Represents an av(no case hardening)

146 / Heat Treater’s

Guide

1018 Chemical Composition. AISI and UNS: 0.15 to 0.20 C. 0.60 to 0.90 hln. 0.040 P max. 0.050 S max

Recommended

Similar

Normalizing.

Steels (U.S. and/or Foreign).

UNS

Gl0180;

AMS

5069; ASTM A 108. A5 IO. A5 13. AS 19, AS-U. A535. AS-N. A519. A576. A659: MILSPEC MIL-S-11310 (CSlOl8); SAE J103. J-II?. J-II-l

Characteristics. Excellent forgeability. reasonahly good cold formability, and excellent vveldability. As carbon content increases. strength also increases, accompanied by a small decrease in cold formability. Machinability is relatively poor compared with the I100 and 1200 grades. The slightly higher manganese (compared with 1017) provides a slight increase in strength in the nomralized or annealed condition. Higher manganese also provides for a mild increase of hardenability for case hardened parts Forging.

Heat to 1275 “C (7375 “F). Do not forge below 910 “C (1670 OFJ

Heat Treating

Practice

Heat to 925 “C (I 695 “F). Air cool

Annealing. Heat to 885 “C (I675 cooler or by furnace cooling

“F). Cool

slowly,

preferably

in a

Hardening. May be case hardened by liquid or gas carburizing, or by flame hardening. (See procedure for 1020.) Quenchants include aqueous polymers. hlore often. it is subjected to light case hardening by carbonitriding or casing in a liquid bath. (See procedure for 1008 steel.) In many instances. forgings of this grade are used in service either as forged or as forged and normalized. Grade 1018 is used to a considerable extent for carburizing to deep case depths 1018: Carburized, Oil Quenched, and Tempered. 12.7-mm (0.5in.) diam bar, carburized at 925 “C (1695 “F) for 4 l/2 h. oil quenched, and tempered at indicated temperatures

Nonresulfurized

1018: Carburizing Temperature vs Depth of Case. Treated 3 h at temperature. Endothermic gas atmosphere, enriched with natural gas. Carbon potential automatically controlled by dew point method, producing 0.90 to 0.95% surface carbon.

Carburizing Symbol

“F

%pera%!

,3.

1950

1065

0.. A

1900 1850 1800

1040 1010 980

8: : : : : : : :c%

E L

Dew point

-7 to -5 -2 to 0 +2 to +14 +6 to +9 +14 +11 to +15 +13

-22 -19 -17 -14

“C to to to to

Steels / 147

1018: Hardness vs Tempering Temperature. Decrease of surface hardness with increasing tempering temperature. Rockwell C converted from Rockwell 30-N. Carbonitrided 2 l/2 h

Symbol ‘.:I, ......................... .......................... t .......................... A...........................145

NH,. ‘2 .1550 ..155 0 .1450 0

845 845 790 790

1; 1:

-21 -18 -10 -13

-10 -12 to -10 -9

1018: Carbon, Nitrogen, and Hardness Gradients. Carbonitrided verted from Tukon

Carbon

at 845 “C (1555 “F), 4 h. Oil quenched at 55 “C (130 “F). Hardness con-

148 / Heat Treater’s

Guide

1018: Effect of Tempering Temperature on Hardness Gradients. Tempered 1 h at temperature.

Rockwell C hardness converted from dickers. (a) Carbonitrided at 790 “C (1455 “F) ,2 l/2 h; 5% NH,. (b) Carbonitrided at 790 “C (1450 “F), 2 l/2 h; 10% NH,. (c) Carbonitrided at 845 “C (1555 “F), 2 l/2 h; 5% NH,. (d) Carbonitrided at 845 “C (1555 “F), 2 l/2 h; 10% NH,

1018: EfFect of Ammonia in Carbonitriding

Gas on Hardness Gradient. (a) Carbonitrided

at 845 “C (1555 “F), 2 l/2 h. Hardness converted from Vickers

at 790 “C (1450 OF), 2 l/2 h. (b) Carbonitrided

Nonresulfurized

Carbon

Steels / 149

1018: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure (no case hardening)

1018: Microstructures. (a) 1% nital, 500x. Carburized 8 h. Surface carbon content, 0.60 to 0.70%. Ferrite (light areas), outlining prior austenite grain boundaries, and pearlite (dark areas). (b) 1% nital, 500x. Carburized 4 h. Surface carbon, 0.70 to 0.80%; wholly pearlitic. Below surface, dark areas are pearlite. Areas of ferrite outline prior austenite grain boundaries. (c) 1% nital. 500x. Carburized 6 h. Surface carbon, 0.90 to 1 .OO%. Thin film of carbide outlines pnor austenite grain boundaries in matrix of pearlite. (d) 1% nital. 500x. Carburized 16 h. Surfacecarbon, 1 .OOto 1 .lO%. Surface layer, carbide. Below surface, thin film of carbide outlines prioraustenite grain boundaries in pearlite matrix. (e) 1% nital. 500x. Carburized 18 h in continuous furnace. Cooled under atmosphere in furnace vestibule. Partly separated layer of carbide (approximately 0.90% carbon) covers pearlite matrix. (f) 1% nital, 500x. Carburized 12 h. Surface carbon. approximately 1 .lO%. Carbide surface layer. Film of carbide outlines prior austenite grain boundaries in pearlite matrix

(continued)

150 / Heat Treater’s

Guide

1018: Microstructures (continued). (g) 1% nital. 500x. Gas carburized, 5 h; 925 “C (1700 “F), pit-type furnace with air leak. Furnace cooled to 540 “C (1000 “F) in 2 h 10 min. Air cooled to room temperature. Thin decarburized layer (ferrite), caused by furnace leak, covers surface. Matrix is pearlite, with carbide at prior austenite grain boundaries. (h) 1% nital, 500x. Gas carburized, furnace cooled, and cooled to room temperature under same conditions as (g), except furnace leak was more severe. Decarburized layer (ferrite) caused by leak is thicker and covers matrix of pearlite. Carbon has diffused from grain boundaries. (j) 3% nital, 200x. Carbonitrided, 4h; 845 “C (1555 “F) in 3% ammonia. Propane, 6%; remainder, endothermic gas. Oil quenched. Cooled to -74 “C (-100 “F). Tempered 1 l/2 h at 150 “C (300 “F). Tempered martensite: some bainite. (k) Nital, 100x. Carbonitrided 4 h; 845 “C (1555 “F). Oil quenched; not tempered. Stabilized by subzero temperature. Normal case structure for carbon steel. Contains martensite, carbide particles, and small amount of retained austenite. (m) Picral, 200x. Annealed by austenitizing at 885 “C (1625 “F), 2 h. Cooled in furnace. Fully annealed structure consists of patches of pearlite (dark areas) in matrix of ferrite (light areas)

150 / Heat Treater’s

Guide

1019 Chemical

Composition. AISI I .OO Mn. 0.040 P max. 0.050 S max

Similar

Steels (U.S. and/or

and UN%

Foreign).

0.15 to 0.20 C. 0.70 to UNS

Gl0190:

ASTM

Recommended Normalizing.

Heat Treating

Practice

Heat to 935 “C i 1695 “F). Air cool

A510.A513.A519.A545.A548.A576:SAE5103.5412.5311

Characteristics.

Annealing. Heat to 885 “C (I625 cooler or by furnace cooling

Forging.

Hardening. May be case hardened by gas carburizing. (See procedure for 1020.) More often, it is subjected to light case hardening by carbonitriding or casing in a liquid bath. (See procedure for 1008 steel.) Flame hardening is an alternative process. In many instances. forgings of this grade are used in service either as forged or as forged and normalized

Excellent forgeability. reasonably good cold fomlability. and excellent weldability. As carbon content increases, strength also increases, accompanied by a small decrease in cold formability. Machinability is relatively poor compared with the I 100 and I200 grades. The slightly higher manganese (compared with IO1 8j provides a slight increase in strength and hardenability Heat to 1275 “C (2325 “F). Do not forge below 910 “C (I670 ‘F)

“F). Cool

slowly,

preferably

in a

Nonresulfurized

1019: Isothermal Transformation Diagram. Containing 0.17 C, 0.92 Mn. Austenitized at 1315 “C (2400 “F). Grain size, 0 to 2. Martensite temperatures estimated

Carbon

Steels / 151

1019: End-Quench Hardenability. 12.7 mm (0.5in.) diam bar. 0.17 C, 0.92 Mn. Grain size, 0 to 2. Austenitized at 1315 “C (2400 “F). Quenched from 870 “C (1600 “F)

1019: Hardness vs Tempering Temperature. Represents an average based on a fully quenched

structure (no case hardening)

Nonresulfurized

Carbon

Steels / 151

1020

Chemical Composition. AISI and UNS: 0.18 to 0.23 C. 0.30 to 0.60 Mn. 0.040 P max. 0.050 S max Similar

Steels (U.S. and/or

Foreign).

UNSGIOXO:

AMS ~032.

5045; ASTM ASlO. A519, A54-I. A575. A576. A659; MU SPEC MU-S11310(CS1020);SAEJ403.J412,J411:(Ger.)DIN l.O402:(Fr.)AFNOR CC 20: (Ital.) UNI C 20; (Swed.) SS1-t I-150: (U.K.) B.S. 040 A 20.070 M

20 Characteristics. Most widely used of several similar grades containing about 0.20% carbon. Available in a variety of product forms. Excellent forgeability and weldability. Even with a maximum carbon content of 0.23%. no preheating or postheating required for the vast majority of welded structures. When most of the fabricating operations consist of some form of machining. this grade is not recommended because machinability is notably poor. Widely used as a carburizing steel Forging.

Heat to 1260 “C (2300 “F). Do not forge below 900 T

( 1650

“F)

Recommended Normalizing. Annealing. Hardening.

Heat Treating

Practice

Heat to 925 “C ( I695 “F). Air cool Heat to 870 “C (1600 “F). Cool slowly,

preferably

in furnace

Can be case hardened by any one of several processes. which range from light case hardening, such as carbonitriding and the others described for grade 1008. to deeper case carburizing in gas. solid. or

liquid media. Most carburiring IS done m a gaseous mixture of methane combined with one of several carrier gases. using the temperature range of 870 to 955 “C ( 1600 to 17.50 “F). Carburize for destred case depth with a 0.90carbon potential. Case depth achieved is always a function of time and temperature. For most furnaces. a temperature of 955 “C (I 750 “F) approaches the practical maximum u ithout causing excessive deterioration in the furnace. With the advent of vacuum carburizing, temperatures up to 1095 “C (200.5 T) can be used to develop a given case depth in about one half the time required at the more conventional temperature of 925 “C (I695 “F). Alternative processes are flame hardening, boriding, liquid nitriding. and plasma (ion) carburizing

Hardening

After Carburizing

is usually

achieved

using

one of

three procedures: I. Quench directly into water or brine horn the carburizing temperature 2. After the desired carburizing cycle has been completed, decrease the furnace temperature or use lower temperature zone of a continuous furnace to 845 “C (I 5.55 “F) for a diffusion cycle. Quench in water or brine 3. Cool slowly to room temperature after carburizing. Reheat to 815 “C ( I500 OF). Quench in water or brine For rounds usually can also provide also achieve

not over 6.35 to 9.53 mm (0.35 to 0.375 in.) diam. full hardness be obtained by oil quenching. In carbonitriding, oil quenching will full hardness. The liquid carburizing method using molten salt may relatively deep cases on 1020 and similar grades of carbon steel

152 / Heat Treater’s

Guide

Tempering.

Although many carburized and hardened parts are placed in sen ice b ithout tempering, it is considered good practice to temper at I SO “C (MO “F) or somewhat higher for I h if some sacrifice in hardness can be tolerated

Recommended

Processing

1020: Influence Case Depth

l l l l l l l l

Cyanide

25.4 mm (1 in.) diam bars, cyanided

Sequence

Forge Normalize (omit for parts machined from bar stock) Rough machine and/or rough grmd Semifmish machine and grind Carburize Lower temperature for diffusion cycle Quench Temper Finish grind (removing no more than IO ?, of the effective

Concentration

case per side)

1020: Normalizing. Effect of mass and section size on cooling curves obtained in still-air at 23 “C (73 “F). 152.4 mm (6 in.) diam. Approximately 64 kg (142 lb)

30 min at 815 “C (1500 “F)

Fo

91.3 76.0 SO8 13.0 30.2 20.8 IS.1 IO.8 52

1020: Effect of Cyaniding Depth of Case

in.

mm

0.0060 0.0070 O.OMll 0.0060 0.0060 0.0055 o.wso 0.0040 0.0020

0.1574 0. I778 0.1524 0.1524 0.152-l 0. I397 0. I’70 0.1016 0.0508

Temperature

mm

ill. Produced

by immersion

0 ow25 0.00 I35 OWl75 o.w.120 Produced

by immersion

Produced

by immersion

T

I300 I400 ISW 1600

705 760 815 870

I300 I400 IS00 1600

705 760 81s 870

I 300 I-MI 1500 1600

705 760 815 870

for 30 min 0.01270 0.06350 0.10160 0.12192

O.OOIOO 0.W37.5 o.wsw 0.00600

OF

for 15 min 0 w63s 0.03129 o.ou-ls 0.08 I28

O.WO50 0.00250 mo-un 0.00480

and Time on Cyaniding temperahwe

Depth of case

1020: Gas Carburizing. Catburized

on

Depth ofcase NaCN,

l

of Sodium

for 15 min 0.03-10 0.G952.5 0. I2700 0. I5240

for 4 h in batch furnace

1020:

Effect of Cyaniding

Steel cyanided Diameter tn. IS-min

0.25 0.50 0.75 I .w 2.00 3.00

at 815 “C (1500 “F) Case depth

of specimen mm

in.

mm

6.350 I3.7Go 19.050 25.400 50.800 76.200

0.0015 0.0035 0.0030 0.0027 0.0025 0 W23

O.ll43 0.0889 0.0762 0.0686 0.0635

6.350 12.700 19.050 3.4x) SO.800 76.200

0.0045 0.0035 0.0030 0.0027 o.wx 0.0023

0. I I-13 0.0889 0.0762 0.0686 0.0635 0.0584

immersion

0.30 0 500 0 750 I .ooo 2.ooo 3 .ow 30-min

Mass on Depth of Case

0.0584

immersion

Nonresulfurized

1020: Oil Quenching. Effect of mass and section size on cooling curves in oil quenching. Oil at 37 “C (99 “F). 152.4 mm (6 in.) diam. Approximately 64 kg (142 lb)

Carbon

Steels / 153

1020: Liquid Carburizing. Effect of carburizing temperature and time at temperature on case depth and case hardness gradient. Specimens 19.05 mm (0.75 in.) diam by 50.8 mm (2 in.). Liquid carburized, air cooled, reheated in neutral salt at 845 “C (1555 “F), and quenched in salt at 180 “C (355 “F). (a) Carburized at 870 “C (1600”F).(b)900”C(1650”F).(c)925”C(1695”F)

1020: Gas Carburizing.

Variations of carbon content, 0.25 mm (0.010 in.) below the surface. Three similar batch furnaces (a, b, c) used. Twenty-five tests in each

1020: Liquid Carburizing.

Comparison of case depth and case hardness of 27 specimens, 11 .1125 mm (0.4375 in.) diam by 6.35 mm (0.25 in.). Liquid carburized, 2 h, at 855 “C (1570 “F). Brine quenched and tempered, 150 “C (300 “F)

154 / Heat Treater’s Guide

1020: Liquid Carburizing. Carbon gradients produced in low- and high-temperature shown, at (a) 845 “C (1550 “F); (b) 870 “C (1800 “F); (c) 955 “C (1750 “F)

baths. 25.4 mm (1 in.) diam bar catburized,

for time

1020: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure (no case hardening)

Nonresulfurized

1020: Liquid Carburizing. case depth. (a) 25.4 Specimen carburized 11.1125 mm (0.4375 carburized at 855 “C 150 “C (300 “F)

Effect of time and temperature on mm (1 in.) outside diam by 152.4 mm (6 in.). at temperature indicated. Oil quenched. (b) in.) diam by 6.35 mm (0.25 in.). Specimen (1570 “F), brine quenched, and tempered at

Carbon

Steels / 155

1020: Liquid Carburizing of Typical Parts. Selective carburizing by partial immersion. Only that portion to be carburfzed (shaded area) is immersed in bath. (a) Compression rod. Depth of case, 0.508 to 0.635 mm (0.020 to 0.025 in.). Hardness, 55 to 60 HRC. (b) Control linkage. Depth of case, 0.127 to 0.254 mm (0.005 to 0.010 in.). Hardness, 55 to 60 HRC. (c) Ball connecting rod. Depth of case, 0.254 to 0.381 mm (0.010 to 0.015 in.). Hardness, 55 to 60 HRC

1020: Water Quenching. Effect of mass and section size on cooling curves in water quenching. Water at 46 “C (115 “F). No agitation. 152.4 mm (6 in.) diam. Approximately 64 kg (142 lb)

1020: Liquid Carburizing. Case hardness gradients, obtained in ten tests, showing scatter from normal variations

156 / Heat Treater’s

Guide

1020: Gas Carbonitriding. Effects of ammonia concentration and inlet-gas dew point on carbon and nitrogen gradients. Carbonitrided at 845 “C (1555 “F), 4 h. Inlet gas: 5% methane; remainder, carrier gas. Air cooled. (a) 5% NH,. Dew point, -26 “C (-15 “F). (b) 5% NH,. Dew point, 0 “C (+32 “F). (c) 5% NH,. Dew point, +24 “C (+74 “F). (d) 1% NH,. Dew point, -29 “C (-20 “F). (e) 1% NH,. Dew point, 0 “C (+32 “F). (f) ) 1% NH,. Dew point, +22 “C (+72 “F)

Nonresulfurized

1020: End-Quench Hardenability: Carbonitriding and Carburizing. As-quenched hardenability measured along surface.

Carbon

Steels / 157

1020: Gas Carbonitriding. of carbonitriding

Effects of temperature and duration on depth of case. Total furnace time indicated

Inlet carbonitriding atmosphere was 5% ammonia, 5% methane, and the remainder, carrier gas. Solid line: carbonitrided 4 h at 900 “C (1650 “F). Dotted line: carburized 3 h at 925 “C (1695 “F)

1020: Plasma (Ion) Carburizing. Carbon concentration profiles in AISI 1020 steel after ion carburizing for 10, 20, 30, 60. and 120 min at 900 “C (1650 “F). Carbon profile after atmosphere carburizing for 240 min at 900 “C (1650 “F) shown for comparison

1020: Plasma (Ion) Carburizing. Carbon concentration profile in AlSl 1020 steel after ion carburizing for 10 min at 1050 “C (1920 “F) followed by vacuum diffusing for an additional 30 min at 1000 “C (1630 “F). A similar carbon concentration profile is obtained by atmosphere carburizing for 6 h at 918 “C (1685 “F)

158 / Heat Treater’s

Guide

1020: Plasma (Ion) Carburizing. Carbon concentration and hardness profiles in AISI 1020 steel after ion carburizing for 10 min at 1050 “C (1920 “F) followed by additional vacuum diffusing for 30 min at 1000 “C (1830 “F). Effective case depth is indicated by dotted line

Nonresulfurized

Carbon

Steels / 159

1020: Plasma (Ion) Carburizing. Carbon concentration and hardness profiles through cases on AISI 1020 steel after ion carburizing in methane, natural gas, and in 8:l nitrogen/propane combination. Data are based on a boost-diffuse cycle of ion carburizing for 10 min at 1050 “C (1920 “F) followed by 30 min of diffusion at 1000 “C (1830 “F)

160 / Heat Treater’s

Guide

1020: Microstructures. (a) Nital, 500x. Carbonitrided and oil quenched, showing effect of too high a carbon potential. Outer white cementite; followed by interlaced martensite needles in retained austenite. Martensite matrix on right. (b) 2% nital. 550x. Cyanided bath. 845 “C (1555 “F), for 1 h. Water quenched. As-quenched condition shows coarse martensite with some carbide particles. Free rite. (c) 2% nital 100x. Same as (b), but lower magnification; showing case, transition, and core structures. Dark impressions are Tukon microhardness indentations, 0.0762 mm (0.003 in.) apart. Equivalent hardness, 61 HRC in case and 25.5 in core

layer, in salt of fer500-g

160 / Heat Treater’s

Guide

1021 Chemical

Composition.

AK1 and UNS: 0. I8 to 0.23 C. 0.60

to

0.90 hin. 0.040 P max. 0.050 S max

Similar

Steels (U.S. and/or Foreign).

ASlO. ASl9.

l!NS Gl0210: ASThl

AS-IS. AS-W AS76. A659: SAE 1403. J-II,.

J-Ill

Tempering.

Characteristics.

Excellent forgeability and weldahilitj. Even u ith a maximum carbon content of 0.234. no preheating or postheatIng is required for the vast majority of welded structures. hlachinability is notably poor. The slightly higher manganese content pro\ ides minor increases in strength and hardenahility compared itith 1020

Forging.

Heat to 1260 “C (2300 “FL Do not forge hrlow

900 “C t 1650

“F)

some sacrifice

Heat Treating

l l l

l

Practice

l l

Heat to 925 “C (I695 “FL Air cool

l

Annealing.

Heat to 870 “C t I600 “FL Cool slam ly. preferably

in furnace

Optional. Temper at IS0 ‘C (300 “F) for I h, or higher if of hardness can be tolerated

Recommended

l

Recommended Normalizing.

Hardening. Can be case hardened by any one of several processes, which range from light case hardening (by carbonitriding and salt bath nitriding described for grade 1008) to deeper case carburizing in gas. solid. or liquid media. (See carhuriring process described for grade 109-O)

l

Processing

Sequence

Forge Normalize Rough machine Semifinish machine and grind Carburize Diffusion cycle Quench Temper Finish grind

1021: Isothermal

Transformation

Grain size, 8 to 9. Austenitized temperatures. estimated

Diagram.

0.20 C, 0.81 Mn.

at 925 “C (1695

“F). Martensite

Nonresulfurized

1021: End-Quench Hardenability. 12.7 mm (0.5 in.) diam bar. 0.17 C, 0.92 Mn. Grain size, 0 to 2. Austenitized at 1315 “C (2400 “F). Quenched from 870 “C (1600 “F)

Carbon

Steels / 161

1021: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure (no case hardening)

Nonresulfurized

Carbon

Steels / 161

1022 Recommended

Chemical

Composition. AISI and UN.9 0.18 IO 0.23 C, 0.70 to I .OOMn, 0.040 P max. 0.050 S max

AMS G10220; Similar Steels (U.S. and/or Foreign). UNS 5070; ASTM AS IO. A5 19, AS44 AS45. AS-IX. AS76: hlfL SPEC MLS11310 (CSIOZO): SAE 5403. J-117. JAI-I: (Ger.) DfN 1.1133; (Ital.) l!NI GE hln 3; (Jap.) JIS ShlnC 2 I

Characteristics. Excellent forgeabilicy and weldability. Even mith a maximum carbon content of 0.23%. no preheating or postheating is required for the vast majority of welded structures. hlachinability is notably poor. High manganese content results in increased hardenability. thus permitting achievement of full hardness by oil quenching of somewhat thicker sections than 103-O.Quenching can be less severe because ofFeater hardenability Forging.

l l l l l l l l l

Processing

Sequence

Forge Normalize Rough machine Semifinish machine and grind Carburize Diffusion cycle Quench Temper Finish grind

Heat to 1260 “C (2300 “F). Do not forge belo\{ 900 “C i 1650 “F)

Recommended Normalizing. Annealing.

Heat Treating

Practice

1022: Hardness average

Heat to 925 “C (I 69s “F). Air cool Heat to 870 “C ( I600 ‘F). Cool slow 14. prefsmbly

in furnace

Hardening. Can be case hardened by an) one of several processes. uhich range from light case hardening (by carbonitriding and salt bath nitriding described for grade 1008) to deeper case carburizing in gas. solid. or liquid media. (See carbunzinp process described for grade 1020.) Plasma (ion) carburizing is an alternative process for shallow cases. Quenchants include aqueous polymers Tempering. some sacrifice

Optional. Temper at IS0 ‘C (300 “Fj for I h. or higher if of hardness can be tolerated

based

vs Tempering on a fully quenched

Temperature. structure

Represents an (no case hardening)

162 / Heat Treater’s

1022: Gas Carburizing.

Guide

Catburized

at 920 “C (1690 “F) in 20% CO, 40% H, gas, with 1.6 and 3.6% CH, added

1022: Gas Carburizing. Carburized at 920 “C (1690 “F) with 20% CO, 40% H, gas. Contains enough H,O to produce carbon potentials indicated: (a) 0.50%; (b) 0.75%; (c) 1.10%

Nonresulfurized

Carbon

Steels / 163

1022: Cyaniding. Effect of cyaniding bath temperature on carbon and nitrogen contents and on case hardness. Specimens heat treated 1 h in 30% NaCN bath at temperatures indicated. Composition specrmens air cooled; hardness specimens, water quenched. Cyanate concentrations: 0: 4.67% at 815 “C (1500 “F); 0: 3.37% at 845 “C (1555 “F); A: 2.71% at 870 “C (1600 “F). Note: Rockwell C measurements unreliable. Thin, brittle case incapable of supporting Rockwell C load. Dip in surface hardness on Rockwell 15-N scale (0 and 0) indicative of effect of retained austenite

164 / Heat Treater’s

Guide

1022: Liquid Carburizing. Effect of time and temperature on case depth. Bars: 25.4 mm (1 in.) square by 177.8 mm (7 in.) long. Carburized at 925 “C (1695 “F). Water quenched

164 / Heat Treater’s

Guide

1023 Chemical Composition. AISI and UNS: 0.20 to 0.25 C. 0.30 to 0.60 hln. 0.040 P max. 0.050 S max Similar

Steels (U.S. and/or Foreign). l!NS G10130; ASTM AS IO. AS7S. AS76. A659 SAE J-103. J-l I?. J-l 1-I: (Grr.) DIN I I IS I ; (Fr.)

AFNOR

XC I8 S. XC 25; (Jup.) JIS S ‘0 C. S 22 C. S 20 CK

Characteristics. Quite \~rldablz. Hov,rtwr. \\ hen carbon content is in the upper end of the allouahls range. it hecomes borderline In tern15 of requiring preheating and postheating. I+ ha conlplcx structures are being welded. hlachinabilit) IS poor. Forgeahilitg IS excellent Forging.

Tempering. soms sacrifice

Normalizing.

Heat Treating

Practice

Heat to 925 ‘C t I695 “FL AU cool Heat to 870 “C (I600 tempering

Recommended l l l

Forging.

Heat to I ?-IS “C (2275 “FL Do not forge below 870 “C t I600 “F)

l l

Recommended Normalizing.

Practice

l

Heat to 9 IS “C ( I680 “F). Cool in air

l

Heat Treating

1037: Hardness vs Tempering Temperature. average

based

on a fully quenched

structure

l

Represents

an

Processing

45 HRC.

Sequence

Forge Normalize Anneal (if necessary for machining) Rough machine Austenitize Quench Temper Finish machine

1037: Water-Quenched Part. Cross section of a water-quenched SAE/AISI 1037 steel track shoe with 0.25 mm (0.010 in.) distortion caused by lightening groove. Redesigning of the shoe to remove the grooves improved uniformity of the section and reduced the distortion to a maximum of 0.08 mm (0.003 in.)

172 / Heat Treater’s

Guide

1038,1038H Chemical

Composition. 1038. AISI and UNS: 0.35 to 0.41. C. 0.60 to 0.90 Mn. 0.040 P mttx, 0.050 S max. 1038H. UNS H10380 and SAE/AISI 1038H: 0.34 to 0.43 C. 0.50 to 1.00 Mn. 0.15 to 35 Si

Similar

Steels (U.S. and/or

Foreign).

1038.

CJNS

G 10380:

ASThl ASIO. AS-U. AS-IS. A.546. AS76: SAE J403. J-II?. J-II-I; (Ger.) DIN I.1 176: (Fr.) AFNOR XC 38TS. 1038H. l!NS Hl0380; SAE Jl268: (Ger.) DIN I I 176: (Fr.) AFNOR XC 38 TS

Characteristics.

One of the most widely used carbon steels ha\ ing ;1 medium-carbon content. Most widely used for producing forgings to he used in the heat treated condition. Also available as an H steel. Welded only with the precautions used for welding of any medium-c&on steel: przheating, postheating, and control of interpass temperature

Forging.

Annealing. Heat to 855 “C ( Is70 ‘F). Furnace cool to 650 “C ( 1100 9% at a rate not to exceed 28 “C (SO “F) per h Hardening. Heat to 855 “C (IS70 “F). Carbonitriding is a suitable surface hardening process. Quench in water or brine. Rounds under 6.35 mm (0.15 in.) diam ma! bs oil quenched for titll hardness

Recommended l l l l

Heat to I215 “C (7275 OF). Do not forge below 870 ‘C t I600 “F)

Practice

l

Heat to 900 “C (,I650 “FL Cool in air

l

Recommended Normalizing.

l

Heat Treating

l

Processing

Forge Normalize Anneal (if necessary for machiningj Rough machine Austenitize Quench Temper Finish machine

Sequence

Nonresulfurized

1038H: End-Quench Hardenability. Normalized at 870 “C (1600 “F). Austenitized Distance frum quenched surface ‘/l6h mm I

1.s 2 2.5 3 3.5 -I 1.5 5 5.5

1.58

2.37 3.16 3.95 4.74 5.58 6.32 7.11 7.90 8.69

Eardness, ARC max miu 58 56 55 53 49 13 37 33 30 29

51 i2 31 29 26 24 23 21 22 21

Distance From quenched surface ‘/I,5m. mm 6 65 7 7.5 8 9 IO I2 1-l 16

9.48 IO.27 Il.06 I I X5 12.64 l-l.22 IS.80 18.96 22.12 25.x3

Carbon

Steels / 173

at 845 “C (1550 “F)

Hardness. ERC max miu 28 27 27 26 26 2s 25 2-l 23 21

?I 20 :::

‘1: .., .,.

1038: Cooling Curve. 0.38 C. 0.70 Mn, 0.015 P, 0.030 S 0.25 Si, 0.063 Al, 0.003 N. Austenitized 1095 “C (2005 “F). Grain size, ASTM 5. Solid coolina curves are for bars of indicated diameters. M, is 225 “C (435 “F); M, is 400 “C (750 “F);Ac, is 710 “C (1310 “F); AC, is 760 “C (1400°F) ”

1

174 / Heat Treater’s

Guide

1038: Cooling Curve. Austenitized at 870 “C (1600 “F). Grain size, ASTM 8. Solid cooling curves are for bars of indicated diameters. numbers are hardness, HV. Bold face numbers, ASTM grain size

italic

1038: Hardness vs Tempering Temperature. Quenched specimen, 3.175 to 6.35 mm (0.125 to 0.25 in.). Tempered

1038: Microstructures.

1h

(a) 2% nital, 50x. Longitudinal section, as forged. Secondary pipe from original bar stock (black areas). Pearlite (gray). Ferrite (white). (b) 2% nital. 100x. Transverse section, as forged. Severely overheated, showing first stage of burning. Ferrite (white) outlines prior coarse austenite grains. Matrix of ferrite (white) and pearfite (black). (c) 2% nital, 550x. Same as (b), at higher magnification. Massive ferrite outlines coarse austenite grains. Contains particles of oxide (black dots). Matrix of ferrite (white) and pearlite (black)

Nonresulfurized

1038H: Hardenability Curves. Heat-treating (1600 “F). Austenitize:

Hardness Purposes I distance, mm 1.5 3 5 7 9 II 13 I5 !O 15 3s

845 “C (1550 “F)

Limits for Specification Eardncss,EIRC Minimum Maximum S8 56 49 33 29 27 26 25 24 22

51 37 25 22 20

Hardness Limits for Specification Purposes I distance, /I6 in. I 1.5 !.5 i.5 1.5 i.5 5.5 1.5

Aardoess. EIRC Minimum Maximum 58 56 55 53 39 43 37 33 30 29 28 27 27 26 26 ‘5 ‘5 24 23 21

51 42 3-l 29 26 24 23 ‘2 22 71 21 20

temperatures

recommended

Carbon

by SAE. Normalize (for forged or rolled specimens

Steels / 175

only): 870 “C

176 / Heat Treater’s

Guide

1039 Chemical

Composition.

AISI and UNS: 0.37 to 0.44 C. 0.70 to

I .OO hln. OWO P max. 0.050 S max

Similar

Steels (U.S. and/or

Foreign).

UNS

G 10390;

ASTM

ASIO. 4516. AS76; SAE J103. J-II?. J-II-I: (Ger.) DIN I.1 157: (Fr.) AFNOR 35 M 5; (U.K.) B.S. 120 h,l36. IS0 M 36. CDS lOS/lO6

Characteristics. hledium-carbon steel. Widzl~ used for forgings that will be heat treated. Machinability is onl! fair. Since ueldability is poor, the best preheating and postheating practice is required when welding is in~olvcd. The slightly higher manganese cont2nt off2rs thz possibility of slightly increased hardenability. compared hith IO-IO Forging.

Heat to I I-15 YY (2175 ‘F). Do not forg2 b2lou 900 “C ( 1650 “F)

Recommended Normalizing.

Heat Treating

Practice

Hrat to 900 “C (I 650 “F). Cool in au

Annealing.

Tempering

After Hardening. As-quenched hardness mateI) 5?. HRC. Hardness can be reduced by tempering

Tempering After Normalizing. For large sections, normalize by comentional practice. Resuhs in a structure of fine pearlite. A tempering treatment up to about 510 “C (I000 “FJ is then applied. Mechanical properties not equal to those achie\,ed by quenching and tempering. Resulting strength is far higher than that of annealed structure. Normalizing and tcmpcring oftsn applied to hea\> forgings

Recommended

Processing

Sequence

Forgings l l l

Heat to 8-0 “C (I 55s “F). Furnace cool to 650 “C ( I200 “F). at a rate not to exceed 3 “C (50 “F) per hour

l

Hardening.

l

Heat to 815 &C t IS55 “F). Carbonitriding is a suitablz stufacc trzating process. Quench in eater or brin2. Rounds less than 6.35 mm to.75 in.) diam may be oil quenched to full hardness

of approxi-

l

l l

Forge Normalize Anneal (ifnecessarj Rough machine Awtenitize Quench Tempzr Finish machine

J or

telllper

(optional)

1039: Hardness vs Tempering Temperature. erage based on a fully quenched structure

Represents

an av-

1039: Microstructures. (a) 1% nital, 750x. Gas carburized roller for use in contact fatigue tests. Inclusions and “butterfly” alterations at center, about 0.127 mm (0.005 in.) from contact surface. Alterations believed to be work-hardened ferrite, caused by breakdown of martensite. (b) 2% picral, 1950x. Same as (a), but enlarged in electron micrograph of two-stage, carbon-chromium-shadowed replica. Lighter etching than (a). “Butterfly” alterations, formed at inclusions are believed to be oriented in direction of principal stress

Nonresulfurized

Carbon

Steels / 177

1040 Chemical

Composition.

AI.9 and UNS: 0.37 to 0.44 C, 0.60 LO

0.90 Mn. 0.040 P max. 0.050 S rnxx

Similar

Steels (U.S. and/or Foreign). ASTM ~5 IO. A5 19. AS16, A576, A681; MILSPEC MLL-S-I~~~~(CS~O-~~J; SAEJ103. J-II?. J-tl4; fCier.1 DfN 1.1186; (Jap.) JIS S 4OC; (U.K.) B.S. 080 A-IO.? S. 93 Characteristics.

Medium-carbon steel. Widely used for forgings that will be heat treated. Machinability is only fair. Since weldability is poor. the hest preheating and postheating practice is requtred when nelding is involved

Forging.

Heat to 1235 “C (2275 OF). Do not forge below 870 “C ( 1600 OF)

Recommended Normalizing.

Heat Treating

Heat to 900 “C ( I650 OF). Cool in air

After Normalizing. For large sections. normalize by comentional practice. This results in a structure of line pearlite. A tempering treatment up IO about 510 ‘C ( IO00 “F) is then applied. Mechanical properties not equal to those achieved b> quenching and tempering. Resulting strength is far higher than that of annealed structure. Normalizing and tempering often applied to heavy forgings

Recommended

l

Hardening. Heat to 845 ‘C ( IS55 “F). Flame hardening carbonitriding. and liquid carburizinp are suitable surface hardening processes. Quench in water or brine. Rounds less than 6.35 mm (I/-l in.) diam may he oil quenched for full hardness 0.39%

C - 0.72%

Mn - 0.23%

S. Grain size: 7-8

Processing

l l l l l l

Forge Normalize Anneal tif necessa@ Rough machine Austenitize Quench Temper Finish machine

Sequence

Si - 0.010%

P -

or temper (optional)

1040: Hardness Specimen, 63.5 thick. Quenched

vs Tempering to 92.075 Tempwng

2”” I

1040: Hardness vs Tempering Temperature. Specimen, to 6.35 mm (0.125 to 0.25 in.) thick. Quenched.

of approxi-

Tempering

l

Heat to 835 “C ( IS55 JF). Furnace cool to 650 “C ( I X0 “F). at a rate not to exceed 78 “C (SO “F) per h

1040: CCT Diagram. Composition:

After Hardening. As-quenched hardness mately 52 HRC. Hardness can be reduced hy tempering

Forgings

Practice

Annealing.

0.018%

Tempering

3.175

Legend: 0: 10

Temperature.

mm (2.50

remwrarure 400 I

to 3.62

in.)

C 500 I

1040: Hardness vs Tempering Temperature.

600 I

Normalized

at

870 “C (1600 “F). Oil quenched from 845 “C (1555 “F). Tempered at 56 “C (100 “F) intervals,

13.716

mm (0.54 in.) rounds.

12.827 mm (0.505 in.) rounds. Source: Republic Steel

Tested

in

178 / Heat Treater’s

Guide

1040: Normalizing. (a) Specimen, 177.8 mm (7 in.) diam. Approximately 105 kg (230 lb). Still air at 22 “C (72 “F). (b) Specimen, 209.55 mm (8.25 in.) diam. Approximately 185 kg (410 lb). Air at 35 to 24 “C (94 to 74 “F). (c) Specimen, 266.7 mm (10.50 in.) diam. Approximately 335 kg (735 lb). Air at 22 “C (72 “F)

1040: Oil Quenching.

(a) Specimen, 177.8 mm (7 in.) diam. Approximately 105 kg (230 lb). Oil at 31 “C (88°F). (b) Specimen, 209.55 mm (8.25 in.) diam. Approximately 185 kg (410 lb). Oil at 50 “C (120 “F). (c) Specimen, 266.7 mm (10.50 in.) diam. Approximately 335 kg (735 lb). Oil at 30 “C (85 “F)

Nonresulfurized

1040: Estimating Jominy Equivalent Hardenabilii. Method forestimating Jominy equivalent cooling rates (J,) in gears of specific size and configuration. Gears made from shallow hardening (1040) steel. Hardened in production. Hardness measured at various depths below surface at pitch line and mot locations. Compared with hardnesses at various (J,) distances on end-quenched bar made from same 1040 bar and quenched from same austenitizing conditions

Carbon Steels / 179

1040: Flame Hardening of Wear Blocks. Clean blocks of scale and rust, preferably by sand or shot blasting. Load blocks on conveyor. Flame head has two rows of number 54 drill size 1.397 mm (0.055 in.) flame holes. 24 of 49 holes are plugged. 152.4 mm (6 in.) between centers of end holes. Head also contains single row of water-quench holes. Head set at 15.875 mm (0.625 in.) total gap. Cone point clearance of flame. 4.763 mm (0.19 in.). Gas pressure: acetylene, 82.738 kPa (12 psi); oxygen, 151.686 kPa (22 psi). Conveyor speed, 148.08 mm (5.83 in.). Total flame hardening time, 1.5 min per pad. Hardness, 53 to 58 HRC. Total depth of hardening to core, 3.97 mm (0.16 in.)

1040: Water Quenching. (a) Specimen, 177.8 mm (7 in.) diam. Approximately 105 kg (230 lb). Water at 57 “C (135 “F). No agitation. (b) Specimen, 209.55 mm (8.25 in.) diam. Approximately 185 kg (410 lb). Water at 55 “C (130 “F). No agitation. (c) Specimen, 266.7 mm (10.50 in.)diam. Approximately 335 kg (735 lb). Water at 50 “C (120 “F). No agitation

180 / Heat Treater’s

Guide

1040: Hardness vs Tempering. Effect of mass: when normalized at 870 “C (1600 “F); oil quenched from 845 “C (1555 “F); tempered at 540 “C (1000 “F). Tested in 12.827 mm (0.505 in.) rounds. Test from 38.1 mm (1.5 in.) diam bars and over, at half-radius position. Source: Republic Steel

1040: Microstructures.

1040: Hardness vs Tempering. Effect of mass: when normalized at 870 “C (1600 “F); oil quenched from 845 “C (1555 “F); tempered at 650 “C (1200 “F). Tested in 12.827 mm (0.505 in.) rounds. Test from 38.1 mm (1.5 in.) diam bars and over, at half-radius position. Source: Republic Steel

(a) Nital 200x. 25.4 mm (1 in.) diam bar. Austenitized at 915 “C (1680 OF), 30 min. Cooled slowly in furnace. Ferrite (white areas) and pearlite (dark). (b) Nital. 500x. Same as (a), at higher magnification. Pearlite and ferrite grains more clearly resolved. Wide difference in grain size in (a) and (b). (c) Picral, 1000x. Austenitized at 800 “C (1475 “F), 40 mm. Held at 705 “C (1300 “F), 6 h, for isothemal transformation. Structure is spheroidized carbide in ferrite matrix. (d) Nital, 500x. 25.4 mm (1 in.) diam bar. Austenitized at 915 “C (1680 “F). Quenched 30 min in salt bath at 420 “C (785 “F). Air cooled. Abnormal amount of ferrite (white) indicates partial decarburization at surface (top). (e) Nital. 500x. Same as (d). Interior of bar. White areas are ferrite, outlining prioraustenite grains. Black and gray are pearlite. (9 Nital, 500x. 25.4 mm (1 in.) diam bar. Austenitized at 915 “C (1680 “F). 30 min. Oil quenched. Tempered at 205 “C (400 “F). Tempered martensite (gray); ferrite (white)

Nonresulfurized

Carbon

Steels / 181

1040: Microstructure. rite-pearlite 500x

Effect Of prior microstructure on spheroidking 1040: MiCrOStrUCtUreS. microstructure (as-quenched). (b) Starting from a ferrite-pearlite 1000x

SitiC

a 1040

steel

microstructure

A fully annealed 1040 steel showing a fermicrostructure. Etched in 4% picral plus 2% nital.

at 700 “C (1290 “F) for 21 h. (a) Starting from a marten(fully annealed). Etched in 4% picral plus 2% nital.

Nonresulfurized

Carbon

Steels / 181

1042 Chemical COInpOSitiOn. AK1 0.90 hln. 0.040 P max. 0.050 S max

and UNS:

0.40 to 0.17 C. 0.60 to

Similar

~273. AS IO. Steels (U.S. and/or Foreign). ASTM A576;FEDQQ-S-635tC1042).SAE5403.5312. J-iI-t:tGer.)DIN I.1 191: (Fr.) AFNOR XC 42. XC -!2 TS. XC -IS. XC 38; (Jap.) JIS S -15 C. S 48 C; tSwed.) SS1.t 1672

Characteristics. Machinability is only fair. Weldahilitj is poor. The best preheating and postheating practice is required when welding is involved. As-quenched hardness can be slightI> higher than 1040 Forging.

Heat to 1%

Recommended Normalizing.

“C (2275 “F). Do not forge below 870 “C t 1600 ‘F)

Heat Treating

Practice

Heat to 900 ‘C t 1650 “F). Cool in air

Annealing. Heat to 815 “C t IS55 “F). Furnace cool to 650°C t 1200°F). at a rate not to exceed 28 “C (SO “F) per h Hardening. Heat to 845 “C t IS55 “F). Flame hardening. induction hardening. horiding. and carhonitriding are suitable surface hardening processes. Quench in water or brine. Rounds less than 6.35 mm (0.25 in.) diam ma) be oil quenched for full hardness Tempering

After Hardening.

As-quenched

hardness

can be re-

duced as desired b) tempenng

Tempering

After Normalizing. For large sections. normalize by conventional practice. This results in a structure of fine pearlite. A tempermg treatment up IO about S-IO ‘C t 1000 “F) is applied. Mechanical properties not equal to those achieved ly quenching and tempering. Resulting

182 / Heat Treater’s

Guide

strength is far higher than that of annealed tempering often applied to heavy forgings

Recommended

Processing

Forgings

structure.

Sequence

Normalizing

and

l l l l l l

l

Forge

1042: Change in AC, Temperature

l

Normalize Anneal (if necessary) Rough machine Austenitize Quench Temper Finish machine

or temper (optional)

1042: Hardness vs Tempering Temperature. Tempered at 205 to 705 “C (400 to 1300 “F), 10 min to 24 h. Quenched specimen, 3.175 to 6.35 mm (0.125 to 0.25 in.). Legend: 0: 10 min; 0: 1 h; A: 4h:&24h

1042: Induction Process. Effect of prior structure and rate of heating on AC, transformation

temperature

of 1042 steel

182 / Heat Treater’s Guide

1043 Chemical Composition.

AISI and UNS: 0.40 to 0.47 C. 0.70 to

I .OO Mn, 0.040 P max. 0.050 S max

Similar Steels (U.S. and/or Foreign). UNS GlO430: ASTM A510. A576; SAJZ J403, J412.5414; (Ger.) DIN 1.0503; (Fr.) AFNOR CC 45: (Ital.) UNI C 45; (Swed.) SSt4 1650: (U.K.) B.S. 060 A-17.080 H 46. 080 M 40,080 M 46

Characteristics. Machinability is only fair. Weldability is poor. The best preheating and postheating practice is required when welding is involved. Added manganese provides increased hardenability. compared with 10-E Forging.

Heat to I245 “C (2275 “F). Do not forge below 870 “C ( 1600 “F’)

Nonresulfurized Recommended Heat Treating Practice Normalizing. Heat to 900 “C ( 1650 “F). Cool in air Annealing. Heat to 845 “C (1555 “F). Furnace cool to

ties not equal to those achieved by quenching and tempering. Resulting strength is far higher than that of annealed StrucNre. Normalizing and tempering often applied to heavy forgings 650 “C (I 200 “F).

at a rate not to exceed 28 “C (50 “F) per h

Hardening. Heat to 845 “C (I 555 “F). Flame hardening, boriding. and carbonitriding are suitable surface hardening processes. Quench in water, brine, or aqueous polymers. Rounds less than 6.35 mm (0.25 in.) diam may be oil quenched for full hardness Tempering After Hardening.

As-quenched

hardness

can be re-

duced by tempering

Tempering After Normalizing.

Carbon Steals / 183

For large sections, normalize by of tine pearlite. A temperconventional practice. This results in a SullCNre ing treatment up to about 540 “C (I 000 “F) is applied. Mechanical proper-

Recommended

Processing

Sequence

Forgings l

Forge

l

Normalize

l

Anneal (if necessary) Rough machine Austenitize Quench Temper Finish machine

l l l l l

or temper (optional)

1043: Hardness vs Tempering Temperature. average based on a fully quenched

structure

Represents

an

Nonresulfurized

Carbon Steels / 183

1044 Chemical Composition. AISI and UNS: 0.43 to 0.50 C. 0.30 to 0.60 Mn. 0.040 P max. 0.050 S max Similar Steels (U.S. and/or Foreign). A510, A575. A576;SAE

UNS

~104.40;

ASTM

J403. J412.J414

achieved by quenching and tempering. Resulting strength is far higher than that of annealed structure. Nomralizing and tempering often applied to heavy forgings

Recommended

Processing

Sequence

Characteristics.

Low-manganese version of widely used mediumcarbon 1045. Often selected in preference to 1045 for surface hardening by flame or induction, because lower manganese decreases hardenability and susceptibility to quench cracking. Excellent forgeability. Fair machinability. Responds readily to heat treatment. As-quenched hardness of at least 55 HRC. Slightly higher, when carbon is near high side of the allowable range. Used extensively for parts that will be furnace heated or heated by induction prior to quenching

Forging.

Heat to 1245 “C (2275 “F). Do not forge below 870 “C (1600 “F)

l l

l

l l l l l

Recommended Normalizing. Heat Annealing. Heat to

Heat Treating

Practice

to 900 “C ( I650 “F). Cool in air

845 “C ( 1555 “F). Furnace cool to 650 “C (I 200 “F), at a rate not to exceed 28 “C (50 “F) per h

Hardening. Austenitize at 845 “C (I 555 “E). Flame hardening, induction hardening, and carbonitriding are suitable surface hardening processes. Quench in water or brine. Rounds less than 6.35 mm (0.25 in.) diam may be oil quenched for full hardness Tempering After Hardening. erly austenitized

and quenched.

Hardness of at least 55 HRC if propHardness can be adjusted by tempering

Tempering After Normalizing.

Forge or machine (bars) Normalize (if forged. Not required for parts machined from hot rolled or cold drawn bars) Anneal (if necessary. Bar stock usually received in condition for best machining) Rough machine (forgings) Austenitize (parts from bars or forgings) Quench Temper Finish machine

Often normalized and tempered, as for 1040. For large sections, normalize by conventional practice. This results in a structure of tine pearlite. A tempering treatment up to about 540 “C (1000 “F) is then applied. Mechanical properties not equal to those

1044: Hardness vs Tempering Temperature. average based on a fully quenched structure

Represents

an

184 / Heat Treater’s

Guide

1045,1045H Chemical Composition. 1045. AK1 and UNS: 0.13 to 0.50 C. 0.60 to 0.90 hln. O.O-lO P max. 0.050 S max. 1045H. UNS H10-150 and SAE/AISI 104-W: 0.42 to 0.5 I C. 0.50 to 1.00 Mn. 0. I5 to 0.35 Si Similar

Steels (U.S. and/or

Foreign).

1045.

UNS

GlO4SO;

ASTM ASIO. ASl9. AS76. A682: FED QQ-S-635 (ClO-!5). QQ-S-700 (ClO-l5):SAEJ~03.J1I2.J-lII:~Ger.)DIN 1.119l;(Fr.)AFNORXC-l7. XC -12 TS. XC -IS, XC 48; (Jap.) JIS S 35 C. S -I8 C; (Stved.) SSt4 1672. 1045H. UNS HIO-ISO: SAE Jl268; (Ger.) DIN 1.1191: (Fr.) AFNOR XC -12. XC-lI!TS,XC-% XC18:(Jap.)JIS S15C.S18C:(S\ved,jSS14 I673

Characteristics. Most often specified medium-c&on steel. Also available as special quality grades ofproprietary steel compositions. Available in a barieb of product forms. mainly as stock for forging. Excellent forgeability. Fair machinabilit). Responds readily to heat treatment. Available as an H grade. As-quenched hardness of at least 55 HRC. Sli8htl> hipher. when carbon is near high side of the allowable range. llsed extensively for parts to he furnace heated or heated by induction prior to quenching Forging.

Heat to 17-15 “C (1375 “F). Do not forge beIon 870 “C ( 1600 “F,

Recommended Normalizing.

Heat Treating

Practice

Heat to 900 “C ( 1650 “FL Cool in air

Annealing.

Heat to 8-15 “C ( I555 ‘F). Furnace cool to 650 ‘C (I ZOO “F), at a rate not to exceed 38 “C (50 “Fj per h

Hardening. Austenitize at 845 “C t IS55 “F). Flame hardening. mduction hardening. liquid nitriding. carbonitidine, martempering. and electron beam hardening are suitable surface hardening processes. Quench in eater or brine. Rounds under 6.35 mm (0.7S in.) diam may be oil quenched for full hardness. Other quenchants include aqueous polymers

for 630 to 860 hlPa (90 to 125 ksi); -I?_5 “C (795 ‘Fj for 860 to 1035 MPa (125 to I50 ksi)

Tempering

After Normalizing. Normalize and temper as for IO-IO. For large sections, normalize b> conventional practice. This results in a structure of fine pearlite. A tempering treatment up to about 540 “C (1000 “F) is then applied. Mechanical properties not equal to those achieved hy quenching and tempering. Resulting strength is far higher than that of annealed structure. Normalizing and tempering often applied to heavy forgmgs

Recommended l l

l

l l l l l

Processing

Sequence

Forge or machine (bars) Normalize (if forged. Not required for parts machined from hot rolled or cold drawn bars) Anneal (if necessary. Bar stock usualI> received in condition for best machining) Rough machine (forgings) Austenitize (parts from bars or forgings) Quench Temper Finish machine

1045: Mass and Section Size vs Cooling Rate in Oil. Specimen: 101.6 mm (4 in.) diam; at 35 “C (94 “F)

approx.

20 kg (43 lb). Oil quenched

Tempering

After Hardening. Hardness of at least SS HRC. ifproperly austenitized and quenched. Hardness can be adjusted by tempering. IVhen quenching in water. parts may be tempered at a range of temperatures to get specific ranges in tensile strength: 565 “C (I050 “F) for 670 to 860 hlPa (90 to I25 ksi); -I80 ‘C (895 OF) for 860 to 1035 hlPa (I 75 to IS0 ksi): 370 “C (700 ‘Fj for 1035 to II75 MPa (150 to 170 ksi). when quenching in oil or polymer. parts may be tempered at: 510 “C ( 1000 “F) 1045: Cooling Rates in Quenching. ums on cooling rates. mm (4 in.). Quenched centers of specimens

Effect of quenching mediCylinders, 25.4 mm (1 in.) diam by 101.6 in salt, water, and oil. Thermocouples at

1045: Induction Hardening. Effect of heating time on depth of hardening. Tendency toward cracking of machined and ground spectmens. Specimens, 25.4 mm (1 in.) diam, with a 50 kw, 450 000 cycle generator. Water quenched. Hardness, 61 to 63 HRC

Nonresulfurized

1045: Isothermal Transformation

Diagram. Composition:

Carbon

Steels / 185

0.45 C, 0.67 Mn, 0.26 Si, 0.06 Ni, 0.009 Mn, 0.009 P, 0.012 S

1045: Mass and Section Size vs Cooling Rate in Water. Speci-

1045: Hardness vs Tempering Temperature, Specimen, 3.175

men: 101.6 mm (4 in.) diam; approximately quenching at 46 “C (115 “F). No agitation

to 6.35 mm (0.125 to 0.25 in.) thick. Quenched. min; 0: 1 h; A: 4 h; A: 24 h

20 kg (43 lb). Water

Legend: 0: 10

188 / Heat Treater’s

Guide

1045: Cooling Rates in Martempering.

Effects of section size and agitation of quench bath on time required for centers of steel bars to reach martempering temperature. Quenching bath is a neutral chloride bath at 845 “C (1550 “F), into anhydrous nitrate - nitrate martempering salt at: (a) ; 205 “C (400 “F); (b) 260 “C (500 “F); (c) 315 “C (600 “F). Length of each bar, 3x diam

1045: Hardness Distribution

in Water-Quenched Bars

1045: Variations in Hardness After Production

Tempering.

Plate sections, 19.05 to 22.23 mm (0.75 to 0.875 in.) thick. Water quenched to hardness range of 534 to 653 HB. Tempered at 475 “C (890 “F) for 1 h in continuous roller hearth furnaces. Data represent two-month production period

Nonresulfurized

1045: Hardness Distribution

in Oil-Quenched

Bars

Carbon

Steels / 187

1045: Induction Hardening. Efficiency of energy transfer at several frequencies. Bars of various sizes heated to 1095 “C (2005 “F). Inside diam of inductors, 28.575 mm (1.125 in.) larger than outside diam of bars

1045: Hardness vs Tempering Temperature. Effect of time at tempering temperature on Brinell hardness of four handgun frame forgings, 101.6 mm (4 in.) by 152.4 mm (6 in.) by 19.05 mm (3/d in.). Heated at 845 “C (1555 “F) in pusher conveyor furnace. Oil quenched. Tempered at 545 “C (1000 “F) in muffle furnace. Both furnaces gas fired, without temperature control. Hardness measured after removal of 0.635 mm (0.025 in.) of material by grinding. 20 heats

1045: Hardness vs Tempering Temperature. Specimen, 38.1 to 63.5 mm (1.5 to 2.5 in.) thick. Quenched

1045: Variations in Hardness After Production

Tempering.

Forged woodworking cutting tools. Section of cutting lip hardened locally by gas burners that heated steel to 815 “C (1500 “F). Oil quenched and tempered at 305 to 325 “C (585 to 615 “F), 10 min, in electrically heated, recirculating-air furnace to desired hardness, 42 to 48 HRC. Data recorded for g-month period and represent forgings from 12 mill heats

188 / Heat Treater’s

Guide

1045: Laser Hardening of Steel Gear

1045H: End-Quench Hardenability Distauce fmm quenched surface ‘/lb in. mm

Eardness, ERC max min

I

IS8

I .s 2

2.31 3.16

62 61 59

55 52 -I2

2.5 3

3.95 4.71 5.53 6.32

56 52 46 38

31 31 29 28

7.1 I 7.90 8.69 9.18 10.27

3-l 33 32 32 31

27 26 26 2s 25

3.5

1 4.5 5

5.5 6 6.5

Distance 6-um quenched surface L/lain. mm 7 7.5 8

Eardness. ERC max mill

II.06 11.85 12.61

31 30 30

9 IO I2 I-l

13.22 15.80 18.96 22.12

29 29 28 27

I6 18 20 22 7-l

X.28 28.4-I 31.60 34.76 37.92

26 25 23 22 21

Nonresulfurized

1045H: Hardenability

Curves. Heat-treating

870 “C (1600 “F). Austenitize:

Hardness Purposes I distance, nm 1.5 5 3 II I.7 IS !O !5 IO

iardness Purposes I distance, /If, in. .5 !.5 1.5 1.5

is i.5

‘3 1

0 2 -I 6 8 10 !2 ‘!-I

temperatures 845 “C (1550 “F)

Limits for Specification Hardness, ERC hlinimum Maximum 62 60 53 36 32 31 30 29 28 27

55 15 31 27 25 24 23 22 20

Limits for Specification Eardoess, HRC hlinimum Maximum 62 61 59 56 52 46 38 3-l 33 32 32 31 31 30 30 29 29 28 27 26 25 23 21 21

55 52 32 34 31 29 28 27 26 26 2s 25 25 2-l 24 23 2’ 21 ‘0

recommended

Carbon

by SAE. Normalize (for forged or rolled specimens

Steels / 189

only):

190 / Heat Treater’s

Guide

1045 : Microstructures.

(a) 2% nital, 500x. 25.4 mm (1 in.) bar stock. Normalized by austenitizing at 845 “C (1555 “F). Air cooled. Tempered at 480 “C (895 “F), 2 h. Fine lamellar pearlite (dark) and ferrite (white). (b) Picral, 500x. Sheet, 3.175 mm (l/8 in.) thick. Normalized by austenitizing at 1095 “C (2005 “F). Cooled in air. Structure is peariite (dark gray) and ferrite (light). (c) Picral, 500x. Same as (b), except bar specimen used. Grain size much larger. Pearlite (gray) with network of grain-boundary ferrite (white) and a few side plates of ferrite. (d) Picral, 330x. Forging air cooled from forging temperature of 1205 “C (2200 “F). The structure consists of envelopes of proeutectoid ferrite at prior austenite grain boundaries, with emerging spines of ferrite, in matrix of pearlite. (e) 4% picral, 500x. 50.8 mm (2 in.) bar stock, austenitized at 845 “C (1555 “F), 2 h. Oil quenched, 15 sec. Air cooled, 5 min. Quenched to room temperature. Ferrite at prior austenite grain boundaries. Acicular structure probably upper bainite. Pearlite matrix (dark). (f) 2% nital, 100x. Forging austenitized at 900 “C (1650 “F), 3 h. Air cooled. Tempered at 205 “C (400 “F) for 2 h. At top is layer of chromium plate. Below, layer of martensite, due to overheating during abrasive cutoff. Remainder, ferrite and pearlite. (g) Picral. 500x. Austenitized at 1205 “C (2200 “F), 10 min. Held at 340 “C (640 “F) for 10 min, for partial isothermal transfonation. Cooled in air to room temperature. Lower bainite (dark) in matrix of martensite (white). (h) 2% nital, 500x. 50.8 mm (2 in.) bar stock. Austenitized 2 h at 845 “C (1555 “F). Oil quenched, 15 sec. Air cooled, 3 min. Water quenched to room temperature. Specimen from 3.175 mm (l/8 in.) below surface. Dark stripes at prior austenite grain boundaries are probably upper bainite. Matrix is martensite. (j) 4% picral, 500x. 50.8 mm (2 in.) bar stock. Austenitized 2 l/2 h at 845 “C (1555 “F). Water quenched, 4 sec. Air cooled, 3 min. Water quenched to room temperature. Specimen from 3.175 mm (l/8 in.) below surface. Dark, acicular structure probably lower bainite. Light matrix of martensite. (k) 4% picral, 500x. Same as (j), except somewhat different structure. Gray aggregate probably upper bainite. Fine, acicular dispersion probably lower bainite. Martensite matrix

Nonresulfurized

Carbon

Steels / 191

1046 Chemical Composition. AISI and UNS: 0.43 to 0.50 C, 0.70 to 1.OOMn, 0.040 P max, 0.050 S max Similar Steels (U.S. and/or Foreign). A510, A576; SAE J403,5412,5414

UNS G10460; ASTM

Characteristics. Higher manganese version of 1045 provides for slightly higher hardenability. As-quenched hardnessof at least 55 HRC. Slightly higher when carbon is near high side of the allowable range. Used extensively for parts to be furnace heated or heatedby induction prior to quenching. Excellent forgeability. Fair machinability

Recommended l l

l

l l l

Forging.

Heatto 1245“C (2275 “F). Do not forge below 870 “C (1600 “F’)

Recommended Normalizing.

Heat Treating

Practice

Heat to 900 “C (1650 OF).Cool in air

Annealing. Heat to 845 “C (1555 “F). Furnacecool to 650 “C (1200 “F), at a rate not to exceed28 “C (50 OF)per h

l l

Processing

Sequence

Forge or machine (bars) Normalize (if forged. Not required for parts machined from hot rolled or cold drawn bars) Anneal (if necessary.Bar stock usually received in condition for best machining) Rough machine (forgings) Austenitize (parts from bars or forgings) Quench Temper Finish machine 1046: Quenchina Specimen. 22.225 mm (0.875 in.) diam by 76.2 mm (3 in.). Quenched from 815 “C (1506 “F)

Hardening. Austenitize at 845 “C (1555 “F). Flame hardening, induction hardening, and carbonitriding are suitable surface hardening processes.Quench in water or brine. Rounds under 6.35 mm (0.25 in.) diam may be oil quenched for full hardness Tempering After Hardening. Hardnessof at least 55 HRC if properly austenitized and quenched.Hardnesscan be adjustedby tempering Tempering After Normalizing. Normalize and temperas for 1040. For large sections, normalize by conventional practice. This results in a structure of line pearlite. A tempering treatmentup to about 540 “C (1000 OF)is then applied. Mechanical properties not equal to those achieved by quenching and tempering. Resulting strength is far higher than that of annealed structure. Normalizing and tempering often applied to heavy forgings

1046: Variations in Hardness After Tempering. Forged specimen heated to 830 “C (1525 “F). Quenched in caustic. Tempered 1 h to range of hardness, 285 to 321 HB. Forgings heated in continuous belt-type furnace and individually dump quenched in agitated caustic. Forgings, 44 to 53 kg (95 to 115 lb) each. Maximum section was 38.1 mm (1.50 in.)

1046: Hardness vs Tempering Temperature. Specimen, 57.15 to 63.5 mm (2.25 to 2.50 in.) thick. Quenched

192 / Heat Treater’s

Guide

1049 Chemical Composition. AISI 0.90 Mn. 0.040 P max. 0.050 S max

and UNS: 0.16 to 0.53 C. 0.60 to

Similar

Steels (U.S. and/or Foreign). UNS G 104YO; ASTM AS IO. AS76: SAE J-103.531 7.53 I-t: (Ger.) DIN I I301 : (Fr.) AFNOR XC 48 TS; (Jap.) JIS S SO C: (Swed.) SS1.t 1660

Hardening. Heat to 830 “C ( 1525 “Ft. Flame hardentng and carbonitridinp are suitable surface hardening processes. Quench in water or brine. Rounds less than 6.35 mm (0.75 in.) diam may be fully hardened by oil quenching. Normalize and temper as for IO-IO Tempering. downward

Characteristics. As-quenched hardness of at least 57 HRC. e\en with carbon on the lo\\ side of the allowable range. As-quenched hardness will usually approach 60 HRC. when the carbon is near the maximum. 0.53. Excellent forgeability. Fairly good machinability. \!‘eldability is poor Forging.

Heat to I230 “C (2250 “F). Do not forge belou 8-U “C t IS55 “F)

Recommended

Normalizing.

Heat Treating

Heat to 900 “C (I650

Practice

l

l l

“F). Cool in air

l l

Annealing.

Heat to 830 “C (I 525 “FL Furnace cool to 650 “C ( I ZOO “FL at a rate not to exceed 28 “C (SO “F) per h

1049: Hardness

vs Tempering

Temperature.

to 6.35 mm (0.125 to 0.25 in.) thick. Quenched.

Specimen, Tempered

3.175 1h

Processing

Sequence

Forgings l

Recommended

As-quenched hardness of 57 to 60 HRC can be adjusted by proper tempering temperature

l l

Forge Normalize Anneal Rough machine Austenitire Quench Temper Finish machine

1049:

Hardness

34.925

to 79.375

vs

Tempering

mm (1.375

Temperature. Specimen, to 3.125 in.) thick. Quenched

192 / Heat Treater’s

Guide

1050 Chemical

COIIIpOSitiOn.

MS1

and

UNS:

0.48

to 0.55 C. 0.60 to

0.90 Mn. 0.040 P max. 0.050 S max

AhlS Steels (U.S. and/or Foreign). GINS G~osoo; 5085; ASTM A5 IO. A5 19. AS76. A683: FED QQ-S-635 (C 1050). QQ-S700(C1050):~i~SPECMIL-S-1697~:SAEJ-103.5117.J-II-I:(Ger.)DIN I. I2 IO; (Jap.) JIS S 53 C. S 55 C Similar

Characteristics.

Carbon content as high as 0.55. Borderline between I medium carbon and a high-carbon grade. Used extensively for producing small to medium size forgings. Often selected for parts to be induction hardened. Fully quenched hardness of at least 58 to 60 HRC, especially when carbon is on the high side of the range. Excellent forgeabilib. Fair11 good machinability. Weldability is poor. Not available as an H grade

Forging.

Heat to I230 “C (2250°F).

Recommended Normalizing. Annealing.

Do not forge below 845 “C (IS55 “F)

Heat Treating

Practice

Tempering.

Recommended Forgings l

Forge Normalize

l

Anneal

l

Rough machine Austenitize Quench Temper Finish machine

l

l

t I200 OF).

hardening, induchardening are suitbrine. Rounds less by oil quenching.

As-quenched hardness of 58 to 60 HRC can be reduced by the proper tempering temperature

l

Heat to 900 “C (I650 “F). Cool in air

Heat to 830°C (I 525 “F). Furnace cool to 650°C at a rate not to exceed 18 “C (SO “F) per h

Hardening. Austenitize at 830 “C t, IS25 W. Flame tion hardening. carbonitridinp. austempering. and laser able surfrlce hardening processes. Quench in water or than 6.35 mm (0.15 in.) diam may be fully hardened Normalize and temper as for IWO

l l

Processing

Sequence

Nonresulfurized

1050:

As-Quenched

Hardness

(Oil)

round

in.

mm

Surface

Eardness, ERC ‘/r radius

Center

‘/2 I 2 4

12.7 25.-l SO.8 101.6

57 33 27 98 HRB

37 30 25 95 HRB

34 26 21 91 HRB

Source: Bethlehem

Steels / 193

1050: Isothermal Transformation

to 0.55 C, 0.80 to 0.90 Mn, 0.090 P max, 0.050 S max; grain Grade:.0.48 size 5 to 7 Si

Carbon

C, 0.91 Mn. Austenitized Martensite temperatures

Diagram. Composition: 0.50 at 910 “C (1670 “F). Grain size, 7 to 8. estimated

Steel

1050: Effect of Carbon and Manganese on End-Quench Hardenability. Modified 1050. 0: 0.51 C, 1.29 Mn, 0.06 residual Cr; 0: 0.52 C, 1.27 Mn, 0.06 residual Cr; LO.48 C, 1.07 Mn. 0.06 residual Cr; kO.51 C, 1.04 Mn, 0.08 residual Cr

1050: Flame Hardening

1050:

As-Quenched

Hardness

(Water)

Grade: 0.48 to 0.55 C, 0.60 to 0.90 Mn. 0.040 P max, 0.050 S max; grain size 5 to 7 Si

round

in.

mm

‘/:

II.7 25.1 SO.8 101.6

I 2 4 Source: Bethlehem

Steel

Surface 6-t 60 SO 33

Eardness. HRC ‘/z radius 59 35 32 27

Center 57 33 16 20

1050: Hardness vs Tempering Temperature and Chemical Composition

194 / Heat Treater’s

Guide

1050: End-Quench

1050: Hardness vs Tempering Temperature. Specimen, 3.175

Mn. Austenitized

Hardenability. Composition: 0.46 C, 0.99 at 845 “C (1555 “F). Grain size, 7

to 6.35 mm (0.125 to 0.25 in.) thick. Quenched.

1050: Furnace vs Induction

Tempered 1 h

Hardening. Brine quenched from

855 “C (1570 “F)

1050: Tempering. Effect of tempering temperature on room-temperature mechanical properties of 1050 steel. Properties summarized are for one heat of 1050 steel that was forged to 38 mm (1.50 in.) in diameter, then water quenched and tempered at various temperatures. Composition of heat: 0.52% C. 0.93% Mn

Nonresulfurized

1050: Induction Heating. Variations of room-temperature hardness with tempering temperature for furnace and induction heating

Carbon

Steels / 195

1050: Austempering. Variation in pitch length of 2 mm (0.080 in.) thick link plates after austempering and after oil quenching and tempering. All link plates were austenitized at 855 “C (1570 “F) for 11 min; austempered link plates were held in salt at 340 “C (650 “F) for approximately 1 h, a time dictated by convenience in processing but not required to attain complete transformation

1050: Microstructures. (a) Nital, 825X. Austenitized at 870 “C (1600 “F). l/2 h. Oil quenched. Slow quenching permitted formation of some grain-boundary ferrite and bainite (feathery areas). Matrix is martensite (white). (b) Austenitized at 870 “C (1600 “F); 1 h. Water quenched. (c) Nital, Tempered at 260 “C (500 “F), 1 h. Structure is fine-tempered martensite. No free ferrite visible, indicating quench was effective. 825x. Same as(b) except tempered at 370 “C (700 “F), 1 h. Tempered martensite. (d) Nital, 825x. Same as (b), except tempered at 480 “C (895 “F), 1 h. Tempered martensite. Ferrite and carbide barely resolved. (e) Nital, 825x. Same as (b), except tempered at 595 “C (1105 “F). Tempered martensite. Ferrite and carbide better resolved. (f) Nital. 913x. Same as (d). Replica electron micrograph. Typical of a thoroughly quenched structure

Nonresulfurized

Carbon

Steels / 195

1053 Chemical

Composition.

AISI and UNS: 0.18 to 0.55 C, 0.70 to

I .OO Mn. 0.040 P max. 0.050 S max

Similar

Steels (U.S. and/or

ASIO. AS76: SAE J-103. J-II?. J-II-I

Foreign).

UNS

Gios30;

ASTM

196 / Heat Treater’s Guide Characteristics. Similar IO 1050. except a higher manganese content which slightly increases hardenability. In some application. higher hardenability is useful. Ln induction hardening. higher hardenability ma) cause quench cracking. Excellent forgeability. Fairly good machinabilit>. Weldability is poor Forging.

Heat IO I230 “C t2250 “F). Do not forge below MS “C t IS55 “F)

Recommended Normalizing.

Heat Treating

Annealing.

Heat to 830 “C t IS25 ‘Ft. Furnace cool to 650 ‘C t 1200°F). at a rate not to exceed 28 “C (SO “F) per hour

Hardening. Heat to 830 “C t 1525 ‘FL Carbonitriding and induction hardening are suitable processes. Quench in Water or brine. Rounds less than 6.35 mm tO.3 in.) diam may be oil quenched for full hardness. Normalize and temper. as for 1040 Tempering.

As-quenched hardness of 58 to 60 HRC can be reduced bj proper tempermg temperature

Forgings l l

Forge Normalize

Processing

l l l l l

Anneal Rough machine Austenitize Quench Temper Finish machine

Practice

Heat 10 900 “C t I650 “FL Cool in air

Recommended

l

Sequence

1053: Hardness vs Tempering Temperature. Represents average based on a fully quenched

structure

196 / Heat Treater’s

Guide

1055 Chemical

Composition.

AISI and UN% 0.50 10 0.60 C. 0.60 to

0.90 hln. O.WO P max. 0.050 S max

Similar

l

Steels (U.S. and/or Foreign).

ASIO. AS76. A682 FEDQQ-S-7OO(ClOSS): DIN I.1209

LINS G 10550: ASTM SAE J403. J-112. J-l I-l: (Ger.)

Characteristics. Generally considered a high-carbon steel. When carbon approaches 0.60 a near saturated martensite is formed after austemtiring and severe quenching. As-quenched hardness of 60 to 6-I HRC is ohtained. depending on carbon content. A shallou hardening or low-hardenabilib steel. Good forgeability. Poor machinabilit). Not recommended for welding Forging.

Heat to I205 “C (2200 “F). Do not forge below 8 IS “C ( I SO0 ‘F)

Recommended Normalizing.

Heat Treating

Practice

Heat to YOO “C ( 1650 “FL Cool in au

Annealing.

Heat to 830°C ( IS25 “F). Furnace cool to 650 “C ( 1200°F). at a rate not to exceed 28 “C (SO “F) per h

Hardening. Heat to 830 ‘C (I 525 “F). Flame hardening and carbonitriding are suitable surface hardening processes. Quench in inter or brine. Rounds less than 6.35 mm (l/-l in.) diam may be oil quenched for full hardness. Nomlalize and temper as for I040 Tempering.

As-quenched hardness of 60 to 6-l HRC can be reduced b! proper tempering temperature

Recommended Forgings l l l l

Forge Normalize Anneal Rough machine

Processing

Austrnitize Quench @ Temper l Finish machine l

Sequence

1055: Isothermal Transformation C, 0.46 Mn. Austenitized Martensite temperatures

Diagram. Composition: 0.54 at 910 “C (1670 “F). Grain size, 7 to 8. estimated

Nonresulfurized

Carbon

Steels / 197

1055: End-Quench

1055: Hardness vs Tempering Temperature. Represents

Mn. Austenitized

average based on a fully quenched

Hardenability. Composition: 0.47 C, 0.57 at 845 “C (1555 “F). Grain size, 6 to 7

an

structure

1055: Microstructures. (a) Picral, 1000x. 6.35 mm (0.25 in.) diam rod, patented by austenitizing 2 l/3 min at 930 “C (1705 “F). Quenched 35 set in lead bath at 550 “C (1020 “F). Air cooled. Unresolved pearlite (dark). Ferrite (white), at prior austenite grain boundaries. (b) Picral, 1000x. 3.353 mm (0.132 in.) diam wire. Air patented by austenitizing 1 112 min at 1032 “C (1890 “F). Air cooled in strand form. Line lamellar peadite with discontinuous precipitation of ferrite at prior austenite grain boundaries

Nonresulfurized

Carbon

Steels / 197

i 059 Chemical COIIIpOSitiOn. AISI and UNS: 0.55 to 0.65 C. 0.50 to 0.80 Mn, 0.040 P max. 0.050 S max (standard steel grade for wire rod and wire only)

Recommended Hardening. hardening

Heat Treating

Flame hardening processes

Practice

and carbonitriding

are suitable

surface

Nonresulfurized

Carbon Steels / 197

1060 Chemical Composition. AI!31 and UNS: 0.90 Mn. 0.040 P max. 0.050 S max

0%

to 0.65 C. 0.60 IO

AMS Similar Steels (U.S. and/or Foreign). LINS G IOhoo; 7230; ASTM ASIO. AS76, A682 MLL SPEC MlL-S-16973: SAE J-103. J-113. J-II-I: (Ger.) DIN 1.0601: (Fr.) AFNOR CC 55: (Ital.) LINI C 60: (U.K.) B.S. 060 A 63

Characteristics.

Versatile high-carbon grade. Product forms include \ erious thicknesses of flat stock for fabricating parts to be spring tempered. Good forgeability. Not recommended for welding. As-quenched hardness of near65 HRC. This is near maximum Rockwell hardness. When properly quenched. consists of 3 carbon-rich martensite structure with essentially no free carbide

198 / Heat Treater’s Guide Forging.

Heat to I205 “C (2200 “FJ. Do not forge below 8 IS “C ( IS00 OF)

Recommended Heat Treating Practice Normalizing. Heat lo 885 “C (I625 “FJ. Cool in air Annealing. Heat to 830 “C (IS25 ‘VI. Furnace cool to 650

1060: Isothermal Transformation C, 0.87 Mn. Austenitized Mattensite temperatures

Diagram. Composition: 0.63 at 815 “C (1500 “F). Grain size, 5 to 6. estimated

“C ( I200 “F),

at a rate not fo exceed 28 “C (SO “F) per h

Hardening. austempering,

Heat to 8 IS “C (1500 “F). Flame hardening, carbonitriding, and martempering are suitable surface hardening processes.

Quench in water or brine. Rounds under 6.35 mm (0.25 in.) diam may be oil quenched for full hardness

Tempering.

As-quenched hardness from 62 to 65 HRC. This maximum hardness can be reduced by proper tempering temperature

Austempering.

Thin sections (typically springs) are austempered. Re-

sults in a bainitic structure and hardness of approximately 46 to 52 HRC. Austenitize at 8 IS “C ( IS00 “F). Quench in molten salt bath at 3 IS “C (600

“F). Hold at temperature for at least I h. Air cool. No tempering required

Recommended Forgings

Processing

Sequence

Forge

l l

Normalize

l

Anneal Rough machine

l

l

Austenitize Quench Temper

l

Finish machine

l l

1060:

1060: Hardness vs Tempering Time. Machine tool component forging, 114.3 mm (4.5 in.) long. Rectangular cross section, 15.875 by 22.225 mm (0.625 by 0.875 in.). Heated at 815 “C (1500 “F) in pusher conveyor furnace. Oil quenched. Tempered at 480 “C (895 “F) in muffle furnace. Both furnaces gas fired. No atmosphere control. Hardness measured on polished flash line. 20 heats

As-Quenched Hardness (Oil)

Grade: 0.55 to 0.65 C, 0.60 to 0.90 Mn, 0.040 P max, 0.050 S max: grain size 5 to 7 (90%); 1 to 3 (10%)

In.

Size round IlUll

Surface

Eardness, ERC ‘/r radius

Center

‘/2

12.7 25.1 SO.8 IOl.6

59 3-l 30.5 29

37 32 27.5 26

35 30 25 2-l

I 2 -I Source: Bethlehem

Steel

1060: End-Quench

1060: Hardness vs Tempering Temperature. 4.673 to 104.775

Mn. Austenitized

mm (0.19 to 4.125 in.) thick. Quenched

Hardenability. Composition: 0.63 C, 0.87 at 815 “C (1500 “F). Grain size, 5 to 6

Nonresulfurized

Carbon Steels / 199

Equipment Requirements for Austenitizing, Austempering, and Corrosion Protection of Parts Made of 1035 and 1060 Steels Equipment comprises a manually operated monorail heat-treating

line

Production requirements Pall Steel Section Ihickness. mm fin., Weight of part. kg (lb) Load weight (gross). kgflb) Number of pieces per h Preheating, “C (“Fk min Austenitizing, “C(“F); min Austempering, “C (OF); min

Equipment requirements Preheting furnace Amount ofchloride sah. kg (lb) Austenitizing furnace Amount ofchloridesalt. kg(lb) Ausrempering furnace Amount of nitrate-niuite salt, kg (lb) Heat input. kJ (Btu) per h Agitation Two washing and rinsing tanks Capacity. each tank Heat input. each tank, kJ (Btu, per h Tank for corrosion protection, m fin.)

Fabricated

disk

12.5 (0.492, I.1 (2.5)

Recuwgular tube 1060 I.4 fO.055, 0.2 (0.425)

163 (360) 332 705 ( 1300); 10 815-870 ( I SSO-1600); 10 425 (800); IO

35.7(78 75) 720 705 ( 1300): 5 83Ot 1525): IO 345 (650): 6

1035

Rectangular pkue 1060

0.8 (0.032) 0.01 (0.024 7.3 ( 16) 3!900 70.5( 1300); 5 83Ofl525);

IO

330 (630); 6

Immersed-electrode sah bruh. 0.45 hy 0.6 bj I .6 m ( I8 by 2-l hy 62 in.) 590(1300) Immersed-electrode salt bath. 0.45 by 0.6 hp I .6 m ( I8 by 3-l hy 61 in. 1 59Ofl300) Gas-fwd salt halh. 0.6 by I.2 hy I .8 m 121 hy 18 by 72 in. I

2270 (SOOO, 7-lO.000 (7OO.000) IXvo 150mmf6in.~impellers Gas-tired, hot water: each 0.5 by 0.9 hy I 1 m (20 b! 36 hy 18 in.) 57oLfl5ogal~ 316.000~300.COO, 0.5 by 0.9 hy I.2 m (20 by 36 by 18 in.)

1060: Miichrres. (a) Picral, 1000x. 6.35 mm (0.25 in.) diam rod. Cooled from hot rolling in single strand by high-velocity air blast. Mostly unresolved peartiie. Some diinctly lamellar pearliie. Few scattered white areas are ferrite, partly outlining ptioraustenite grains. (b) Picral, 1000x. 6.747 mm (0.266 in.) dim rod, patented by austenitizing at St.5 “C (1730 “F), 2.50 min. Quenched in lead bath at 530 “C (WI “F), 55 sec. Aircooled. Peariiie (dark areas) and ferrite (wbiie) at prior austenite grain boundaries. (c) Picral, 1000x. 7.137 mm (0.281 in.) diam win?. Air patented by austenitizing at 1055 “C (1930 OF),3 min. Air cooled in strand form. Partly resolved peadiie (dark). Ferrite (white) at prior austenltizing grain boundaries. (d) Piiral, lOOOx. 2.515 mm (0.099 in.) diam wire. Air patented by austenitizing at 1015 “C (1860 “F), 1 min. Air cooled in strand form. Fine pearfiie (dark), mostly unresolved. Some ferrite at prior austenite grain boundaries. (e) Picral, 100x. Decarburized. Heated to 1205 “C (2200 “F), 1 h before rolling to size. Thin layer of scale at surface(topofmicrograpb). Decarburizedwhiielayerneartop. Unresolvedpeartiie,fenfte. (9 Picral, 500x. Decatburfzed. Heatedto870to925”C(1600 to 1695 “F), 12 min. Air cooled. Scale at top of micrograph Partly decarburfzed layer, below scale. Pearfiie (dark). Some grain-boundary ferrite

200 / Heat Treater’s

Guide

1064 Chemical COIIIpOSitiOrl. AISl 0.80 hln. 0.040 P max. O.OSO S max

and LJNS: 0.60 to 0.70 C. 0.50 to

Recommended Hardening. Flame hardenmg processes

1064: Microstructure. 1064 cold-rolled steel strip, heated to 745 “C (1370 “F), furnace cooled to 650 “C (1200 “F), and air cooled to room temperature. Structure is fine spheroidal cementite in a matrix of ferrite. This structure is preferred for subsequent heat treatment. Picral. 500x

Heat Treating hardening

Practice

and carhonitiding

are suitable

surface

1064: Microstructure. 1064 cold-rolled steel strip, austenitized at 815 “C (1500 “F), quenched to 315 “C (600 “F) and held tocomplete isothermal transformation, air cooled, and tempered at 370 “C (700 “F). The structure is a mixture of bainite and tempered martensrte. Picral. 500x

200 / Heat Treater’s

Chemical

Guide

Composition.

AISI and UN% 0.60 to 0.70 C. 0.60 to

Recommended

Heat Treating

Practice

0.90 hln. 0.040 P max. 0.050 S niax

Hardening. ma-tempering

Flame hardening. carhonitriding. are suitahle processes

austempering,

and

1065: Microstructure. 1065 steel wire, 3.4 mm (0.14 in.) in diameter, patented by austenitizing 1.5 min at 930 “C (1705 “F), quenching 30 s in a lead bath at 545 “C (1015 “F), and air cooling. The structure is mostly unresolved pearlite with some grainboundary ferrite. Picral. 500x

Nonresulfurized

Carbon

Steels / 201

1069 Chemical

Composition.

AK1 and IJNS: 0.65 to 0.75 C. 0.40 to

Recommended

Heat Treating

Practice

0.70 Mn. 0.040 P max. 0.050 S max

Hardening. hardening

Flame hardening processes

and carbonitriding

are suitable

surface

Nonresulfurized

Carbon

Steels / 201

1070 Chemical

0.90Mn,

Composition.

AISI and UN% 0.65 to 0.75 C. 0.60 to

0.040 P max. 0.050 S max

Steels (U.S. and/or Foreign). UNS Gl0700; AMS 51 IS; ASTM A510. A576, A682; MLSPEC MIL-S-11713 (2):SAEJ303, J4 12. J4 14: (Ger.) DIN I. I23 I ; (I?.) AFNOR XC 68; (Swed.) SS~J 1770. 1778 Similar

Characteristics.

Low hardenability. Widely used in hardened and tempered (notably, spring tempered) condition. Good forgeability and shallow hardening. Used extensively for making hand tools. such as hammers and woodcutting saws. Fully hardened microstructure is carbon-rich martensite with some small undissolved carbides. Carbides not present in 1060. due to lower carbon content. Although same hardness as 1060 (65 HRC). existence of some free carbide gives 1070 greater resistance to abrasive wear. Not recommended for welding

Forging.

Heat to I I90 “C (2 I75 “F). Do not forge below 8 I5 “C ( I500 “F)

Recommended Normalizing.

Heat Treating

Practice

Heat to 885 “C ( I625 “F). Cool in air

Annealing.

Heat to 830 “C (I525 “F). Furnace cool to 650 “C (I 200 “F). at a rate not to exceed 28 “C (50 “F) per h

austempering, and martempering are suitable surface hardening processes. Quench in water or brine. Rounds under 6.35 mm (0.25 in.) diam may be oil quenched for full hardness

Tempering.

As-quenched hardness approximately can be reduced by proper tempering

Austempering.

Thin sections (typically, springs) are austempered. Results in a bainitic structure and hardness of approximately 46 to 52 HRC. Austenitize at 8 I5 “C (I 500 “F). Quench in molten salt bath at 3 IS “C (600 “F). Hold at temperature for at least I h. Air cool. No tempering required

Martempering. I75 “C(3-kS

hardening,

Heat to 815 “C (1500 “F). Flame hardening, induction carbonitriding. laser hardening. electron beam hardening,

1070: Isothermal Transformation Diagram. Composition: 0.75 C, 0.70 Mn, 0.017 P, 0.016 S, 0.33 Si, 0.20 Ni, 0.17 Cr. Austenitized at 600 “C (1470 “F). Grain size, 5 to 6. Time held in constant temperature bath from start of quench

Austenitize

at 8-U “C ( IS55 “F). Martemper

“F)

Recommended

Processing

Sequence

Forgings l l l l l l

Hardening.

65 HRC. Hardness

l l

Forge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine

1070: Temperature

vs Depth of Case

in oil at

202 / Heat Treater’s

Guide

1070: Hardness vs Depth of Case

1070: Hardness vs Tempering Temperature. Represents average based on a fully quenched

an

structure

1070: Microstructures. (a) 2% nital, 100x. Hard drawn steel valve-spring wire, Longitudinal section. Tensile strength, 1689 MPa (245 ksi, obtained by 80% reduction. Deformed pearlite. Prior structure, fine lamellar pearlite. (b) 2% nital, 1000x. Valve-spring wire. Quenched and tempered. Austenitized at 870 “C (1600 “F). Oil quenched. Tempered at 455 “C (850 “F). Mainly tempered martensite. Some free ferrite (white)

202 / Heat Treater’s Guide

1075 Chemical Composition. AISI 0.70 Mn, 0.040 P max. 0.050 S max

and UNS:

0.70 to 0.80 C. 0.40 to

Recommended

Heat Treating

Hardening. Flame suitable processes

hardening,

Practice

carbonitriding.

and austempering

are

202 / Heat Treater’s

Guide

1078 Chemical Composition. AISI 0.60 Mn. 0.040 P max. 0.050 S max Similar

Steels (U.S. and/or

A510.A576;SAEJ4O3,Jdl2.Jll-k(Ger.)DIN 75: (Swed.) Ss1.1 1774

Characteristics.

and UNS:

Foreign).

0.72 to 0.85 C. 0.30 to UNS G10780; ASTM l.l218:(Fr.)AFNORXC

High carbon allov+s more free carbide particles in quenched microstructure. Because lower manganese decreases hardenabil-

ity. 1078 is often induction hardened. As-quenched hardness of 64 to 66 HRC. if properly austenitized and quenched. Forgeability is good. Never recommended for welding

Forging.

Heat to I I75 “C (2lSO”FL

Recommended Normalizing.

Do not forge below 815 “C (IS50 “F)

Heat Treating

Practice

Heat to 870 “C ( I600 OF). Cool in au

Nonresulfurized Annealing.

Heat to 8 IS “C ( I SO0 “F). Furnace cool to 650 “C ( I200 “F). at a rate not to exceed 28 “C (SO “F) per h

315 “C (600 “F). tempering required

Hardening. Heat to 815 “C ( 1500 “F). Carbonitriding, laser surface hardening, and induction hardening are suitable processes. Quench in water or brine. Rounds under 6.35 mm (0.25 in.) diam may be oil quenched for full hardness

Recommended

Tempering.

Asquenched hardness of approximately ness can be reduced by proper tempering temperature

65 HRC.

Hard-

at temperature

Processing

Steels / 203

for at least I h. Air cool.

No

Sequence

Forgings l l l l

Austempering. Because of low hardenability, thin sections only are austempered, as for 1060. Thin sections (typically springs) are austempered. Results in a bainitic structure and hardness of approximately 46 to 52 HRC. Austenitize at 815 “C (1500 “F). Quench in molten salt bath at

Hold

Carbon

l l l l

Forge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine

1078: Isothermal Transformation Diagram. Composition: 0.75 C, 0.50 Mn, 0.007 P, 0.020 S, 0.27 Si. Horizontal lines: formation of martensite on cooling. Curved lines: formation of bainite on isothermal holding. Dotted lines: beginning of isothermal transfomation of holding below M,

1078: Hardness vs Tempering Temperature. Represents average based on a fully quenched structure

an

204 / Heat Treater’s

Guide

1078: Laser Surface Hardening. Laser surface transformation

hardening of SAE 1078 using optical integrator with 1.27 x 1.27 cm (0.5 x

0.5 in.) laser spot

1078: Microstructure. Picral, 550x. Hot rolled bar. Air cooled from rolling temperature. Predominantly pearlite. Large amount of partly resolved lamellar pearlite. Some grain-boundary ferrite

204 / Heat Treater’s

Guide

1080 Chemical COIIIpOSitiOn. AISI 0.90 hln. 0.040 P max. 0.050 S mux Similar

and UNS:

Steels (U.S. and/or Foreign).

5110: ASTM hIIL-S-16974;

0.75 to 0.88 C. 0.60 to

UNS Gl0800; ASIO. AS76. A68’: FED QQ-S-635 (CIOSO,: hlfL SAE 5403. J-II?. 141-J

AMS SPEC

Characteristics. Higher manganese content of 1080 can provide greater hardenabilit> than 1078. particulruly if manganese is near the high side of the range. 0.90. As-quenched hardness near 65 HRC. As carbon content increases. there is a gradual increase in amount of free carbide. This enhances abrasion resistance and decreases ductility. Forgeability is good. Weldabilitj is poor

Nonresulfurized

Forging.

Heat to I I75 OC (2 I50 OF’). Do not forge below 815 “C (I 500 “F)

Recommended Normalizing.

Heat Treating

Heat

to 870 “C (1600

Practice

“F).

Cool

Recommended

l

Annealing.

Heat to 815 “C (I 500 “F). Furnace cool to 650 “C (I 200 OF), at a rate not to exceed 28 “C (SO “F) per h

Hardening.

Heat to 8 I5 “C (I 500 “0. Induction hardening, carbonitriding, and austempering are suitable processes. Quench in water or brine. Rounds under 6.35 mm (0.25 in.) diam may be oil quenched for full hardness

l l l l l l l

As-quenched hardness of approximately ness can be reduced by proper tempering

65 HRC.

As-Quenched

Hardness

Sequence

Forge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine

Hard-

Austempering. Because of low hardenability, thin sections are austempered, as for 1060. Thin sections (typically springs) are austempered. Results in a bainitic structure and hardness of approximately 46 to 52 HRC. Austenitize at 815 “C (IS00 “F). Quench in molten salt bath at 315 “C (600 “F). Hold at temperature for at least I h. Air cool. No tempering required

1080:

Steels / 205

Forgings

in air

Tempering.

Processing

Carbon

1080: Isothermal Transformation Diagram. Composition: 0.79 C, 0.76 Mn. Austenitized at 900 “C (1650 “F). Grain size, 6. Martensite temperatures estimated

(Oil)

Grade: 0.75 to 0.88 C, 0.60 to 0.90 Mn, 0.040 P max, 0.050 S max; grain size 80%, 5 to 7; 20%, 1 to 4 Size round in.

mm

‘/z I 2 .I

12.7 25.1 50.8 101.6

Source: Bethlehem

Surface 60 -I5 43 39

Eardness, ERC t/z radius 43 42 40 37

Center -IO 39 37 32

1080: Hardness vs Tempering Temperature. Specimen, 3.175 to 6.36 mm (0.125 to 0.25 in.) thick. Quenched.

Tempered 1 h

Steel

1080: End-Quench Hardenability. 12.7 mm (0.5 in.) diam bar. Composition: 0.79 C, 0.76 Mn. Austenitized at 900 “C (1650 “F). Grain size, 6

1080: P&s

Equipment austenitized

Production

for Austempering

requirements

Weight ofeach piece. kg (lb) Production per hour Equipment

Requirements

at 925 “C (1695 “F)

I. I to I .8 (2.-l to 3.9) I SO0 pieces

requirements

Austempering furnace Size of furnace. m3 (ft 3) Nitrae-write salt. kg (Ih, Tempenturr. “C (“FI Agitauon Cooling

Submerged fuel-fired salt pot 6.6(233) I I 340 (29 000) 34%360(65@675) Pump. directed at delivery chute Forced ar through humer tube

206 / Heat Treater’s

Guide

1060: TIT Diagram. Time-temperature austempering.

transformation diagram for 1080 steel, showing difference When applied to wire, the modification shown is known as patenting

1080: Induction Heating. Effect of heating rate on AC, and AC, temperatures

for annealed

1080 steel

between

conventional

and modified

Nonresulfurized

Carbon

Steels / 207

1080: Microstructures. (a) Picral. 2000x. Hot rolled bar, austenitized at 1050 “C (1920 “F), l/2 h. Furnace cooled to room temperature at 28 “C (50 “F) per h. Mostly pearlite. Some spheroidal cementite particles. (b) Thin-foil specimen, 2000x. Same as (a), except cooling rate increased to 56 “C (100 “F) per h. Thin-foil transmission electron micrograph. Fine lamellar pearlite. (c) As polished. Not etched. 250x. Inclusions in flat spring. 0.20 mm (0.008 in.) thick. Longitudinal section. Thickness shown as height in micrograph. Black spots are iron aluminide. Thin gray stringers near center are sulfide

Nonresulfurized

Carbon Steels / 207

1084 Chemical Composition.

AISI and UNS: 0.80

to

0.93 C, 0.60 to

0.90 Mn. 0.040 P max. 0.050 S max LINS ~10810; ASTM (C108-1); SAE 5303. J412. J-II-I: (Ger.) DIN

Heat to II75 “C (2lSO”Fl

Forge Normalize l Anneal l Rough machine l Austenitize 9 Quench l Temper l Finish machine l

Do not forgebelow

815 “C (l5OO’F)

1084: Hardness

Recommended Normalizing.

Heat Treating

Practice

average

Heat to 870 “C (1600 “F). Cool in air

Annealing. Heat to 8 I5 “C ( I500 “F). Furnace cool to 650 “C ( I 200 “F). at a rate not to exceed 28 “C (SO “F) per h Hardening. Heat to 8 IS “C ( I500 “F). Carbonitriding and austemperinp are suitable surface hardening processes. Quench in water or brine. Rounds under 6.35 mm (0.25 in.) diam may be oil quenched for full hardness Tempering.

Asquenched hardness of approximately ness can be reduced by proper tempering

Austempering.

Sequence

l

Characteristics. Composition nearly identical to that of 1080. Asquenched hardness near 65 HRC. As carbon content increases. there is a padual increase in amount of free carbides. This enhances abrasion resistance and decreases ductility. Forgeability is good. Weldabilitj is very poor Forging.

Processing

Forgings

Similar Steels (U.S. and/or Foreign). A510, A576; FED QQ-S-700 I .0647

Recommended

65 HRC.

Hard-

Very thin sections, because of relatively low hardenability can be austempered. using the technique for 1060. Thin sections (typically springs) are austempered. Results in a bainitic structure and hardness of approximately 46 to 52 HRC. Austenitize at 8 I5 “C ( IS00 “F). Quench in molten salt bath at 3 I5 “C (600 “F). Hold at temperature for at least I h. Air cool. No tempenng required

based

vs Tempering on a fully quenched

Temperature. structure

Represents

an

208 / Heat Treater’s

Guide

1085 Chemical

Composition. AISI and CJNS: 0.80 to 0.93 C. 0.70 to I .OOMn. O.@IOP max. 0.050 S max

Recommended Hardening.

Heat Treating

CarbonitridinS is a suitable surface hardening process

1085: Effects of Quenching on Hardness and Dimensions. Hardness values and changes in dimensions test specimen after quenching in water, fast oil, and conventional oil

Quenching medium

Maximum

Water . . . . . . . . . . . . . . . . . . . . . . . . . . 67.0 Fast oil . . . . . . . . . . . . . . . . . . . . . . . . 66.0 Conventional oil . . . . . . . . . . . . . . . . 65.5 Gap A mm Water . . . . . . . . . . . 0.3404 Fast oil . . . . . . . . . 0.0533 Conventional oil . 0.0559

in. 0.0134 0.0021 0.0022

Hardness, H RC Minimum

Variation

63.0 63.0 43.0 Dimensional Diameter 6

mm 0.2591 0.0813 0.0965

Practice

in. 0.0102 0.0032 0.0038

4.0 3.0 22.5 change Diameter mm 0.2946 0.0610 0.0965

C in. 0.0116 0.0024 0.0038

of a 1085 plain carbon steel

208 / Heat Treater’s Guide

1086 Chemical Composition.

Recommended

0.50 hln. 0.040 P nk. wire only)

Hardening.

AISI and CJNS: 0.80 to 0.93 C. 0.30 to 0.050 S max: (standard steel grade for uue rod and

Heat Treating

Carbonitriding

Practice

and austempering

are suitable processes

208 / Heat Treater’s

Guide

1090 Chemical

Composition.

AISI and LINS: 0.85 IO 0.98 C. 0.60

IO

0.90 h*ln. 0.040 P max. 0.050 S max

Similar Sll2:ASTM

Steels (U.S. and/or Foreign). A510. A576: SAEJ403.J-Il2.

LINS J-tl4:Ger.j

MIS GlO200; DIN I.1273

Characteristics. CommonJy referred to as a commercial grade of carbon tool steel. Essentially same composition as WI tool steel, hut not

made hy tool steel practice and not expected IO meet quality level of W 1 tool steel. Easily forged. Blanking (coldj from strip or thin plate is common method of fabrication. Available in a variety of product forms. As hard as 66 HRC, fully quenched. Microstructure of carbon-rich martensite and considerable amount of free carbide. assuming normal austenitizing temperature used

Forging.

Heat to I I50 ‘C (3 IO0 “Fj. Do not forge below 815 “C ( 1500 “Fj

Nonresulfurized

Recommended Normalizing.

Heat Treating

Recommended

Practice

Heat to 855 “C (1570 OF). Cool in air

Processing

Carbon

Steels / 209

Sequence

Forgings

Annealing.

As is generally true for all high carbon steels, bar stock supplied by mills in spheroid&d condition. Annerded with structure of fine spheroidal carbides in ferrite matrix. When parts are machined from bars in this condition, no normalizing or annealing required. Forgings should always be normalized. Anneal by heating to 800 “C (1475 “F). Furnace cool to 650 “C (1200 “F). at a rate not to exceed 28 “C (50 “F) per h. From 800 “C (I475 “F’) to ambient temperature, cooling rate is not critical. This relatively simple annealing process will provide predominantly spheroidized structure, desired for subsequent heat treating or machining

Hardening. Heat to 800 “C (1375 “F). Carbonitriding and austempering are suitable processes. Quench in water or brine. Rounds under 6.35 rnrn (0.25 in.) diam may be oil quenched for full hardness Tempering.

Asquenched hardness of as high as 66 HRC. Hardness can be reduced by proper tempering

Austempering.

Responds well to austempering (bainitic hardening). Austenitize at 800 “C ( 1475 “F). Quench in agitated molten salt bath at 3 I5 “C (600 “F). Hold for 2 h. Cool in air

l l l l l l l l

Forge Normalize Anneal Rough machine Semitinish machine Austenitize Quench Temper

1090: Hardness vs Section Thickness. Specimen, 20.828 mm (0.820 in.) diam. Austenitized at 885 “C (1625 “F). Quenched in salt at 370 “C (700 “F), 7 min. Rockwell hardness C, converted from microhardness readings taken with 100 g (4 oz) load. Low values of surface hardness result from decatburization

I

1090: llT Curves. Transformation characteristics of a hypereutectoid steel after mattempering. Austenitized at 885 “C (1825 “F). Grain size, 4 to 5

1090: Properties Sway Bars

Tensile suer@, hlPa (ksi) Yield strength. hPa (ksi) Elongation. 4. Reduction ofarea % Hardness. HB Fatigueqcles(d) (a) Alerage in diameter 95.220

of Austempered

and Oil-Quenched

Austempered at 400 “C (750 W(b)

Quenched sod tempered(c)

l-115 (205) 1020(148) II.5 30 115 105.OOChel

1380 (200) 895 (130) 6.0 10.2 388 58.6W f,

values (b) Six I~SIS. tc)lko tests cd) Fatigue specimens2 I mrn(O.812 in.) (et Seven tests: range, 69 050 to I37 000. (fj Eight tests; range, 13,120 to

1090: Hardness vs Section Thickness. Specimen,

1090: Hardness vs Tempering Temperature. average based on a fully quenched structure

Represents

an

17.272 mm (0.680 in.) diam. Austenitized at 885 “C (1625 “F). Quenched in salt at 370 “C (700 “F), 7 min. Hardness, HRC, converted from microhardness readings taken with 100 g (4 oz) load. Low values of surface hardness result from decarburization

210 / Heat Treater’s

Guide

1090: Microstructures. (a) Picral, 2000x. Hot rolled bar, 25.4 mm (1 in.). As cooled from finish-rolling temperature of 870 to 900 “C (1800 to 1850 “F). Replica electron micrograph. Entirely lamellar pearlite. (b) Picral, 1000x. 8.712 mm (0.343 in.) diam rod. Patented by austenitizing at 955 “C (1750 “F), 4 l/2 min. Quenched in lead bath at 505 “C (940 “F), 70 sec. Air cooled. Mostly unresolved pearlite with bainite. (c) Picral, 8000x. Strip, cold reduced 80% after hot rolling. Rolling direction vertical in this replica electron micrograph. Deformed lamellar pearlite. (d) 2% nital, 100x. Modified steel music wire. 0.38 Mn. Cold drawn to 1813 MPa ( 283 ksi) tensile strength by 75% reduction. Deformed pearlite. Prior structure, fine pearlite. (e) 2% nital, 500x. Same as (d), but higher magnification. Drawing direction is horizontal. Prior structure produced by lead patenting

210 / Heat Treater’s Guide

1095 Chemical COmpOSitiOn. AK1 0.50 Mn. 0.010 P max. 0.050 S max

and UNS:

0.90 to 1.03 C. 0.30

to

AMS Gl0200; UNS 5121. 5122. 5132. 7304; ASTM A510. A576. A682; FED QQ-S-700 (ClO95); MfL SPEC MB-S-16788 (CSlO95): SAE J303, JJIZ. J4l-k (Ger.) DIN I. 1274; (Jap.) JIS SUP 3: ISwed.) SS1.t 1870; (U.K.) B.S. 060 A96.EN44B

Characteristics. Easily forged. Blanking (cold) from strip or thin plate also a common method of fabrication. Available in a variety of product forms. As hard as 66 HRC, fully quenched. Microstructure of carbon-rich martensite and considerable amount of Free carbide. assuming normal austenitizing temperature is used. Carbon range slightly higher and manganese content lower than for 1090. This results in the possibility of more undissolved carbide in the microstructure and slightly lower hardenability Heat to I I50 “C (2 100 “F). Do not forge below 8 I5 “C ( 1500 ‘F)

Recommended Normalizing.

Heat Treating

practice.

parts are normalized

at 900 “C ( 1650 “F)

Annealing.

Similar Steels (U.S. and/or Foreign).

Forging.

In aerospace

Practice

Heat to 855 “C (1570 “F). Cool in au

As is generally true for all high-carbon steels, bar stock supplied by mills in spheroidized condition. Annealed with structure of fine spheroidal carbides in ferrite matrix. When parts are machined from bars in this condition. no normalizing or annealing required. Forgings should always be normalized. Anneal by heating to 800 “C (1475 OF). Soak thoroughly. Furnace cool to 650 “C ( I200 “F), at a rate not to exceed 28 “C (50 “F) per h. From 650 “C ( I200 “F) to ambient temperature, cooling rate is not critical. This relatively simple annealing process will provide predominantly spheroidized structure, desired for subsequent heat treating or machining. ln aerospace practice. parts are annealed allowed to cool to below 510 “C (I000 “F)

at 815 “C (1500 “F) and

Hardening. Heat to 800 “C (l-l75 “FL Carbonitriding and austempering are suitable processes. Quench in water. brine. or aqueous polymers. Oil quench rounds under A.7 mm (0. I9 in.) for full hardening. Responds well to austempering (same procedure as for 1090). In aerospace practice, parts are austenitized at 800 “C (1475 “F). and quenched in oil or polymers

Nonresulfurized Tempering.

As-quenched hardness as high as 66 HRC. Hardness can be reduced by proper tempering. When quenching with oils or polymers, parts may be tempered at a number of different temperatures to get specitic ranges of tensile strengths as follows: 675 “C (I 245 OF) for 620 to 860 MPa ( 90 to 125 ksi); 620 “C (I I50 “F) for 860 to 1035 MPa ( I25 to I50 ksi); 540 “C ( 1000 “F) for 1035 to I I70 MPa ( I50 to I70 ksi): 480 “C (895 “F) for 1170 to I240 MPa ( I70 to I85 ksi); 425 “C (795 “F) for 1240 to I380 MPa (185 to 200 ksi); 370 “C (700 “F) for I380 to I520 hiPa ( 200 IO 220 ksi)

Recommended

Responds well to austempering (bainitic hardening). Austenitize at 800 “C (1475 “F). Quench in agitated molten salt bath at 3 I5 “C (600 “F). Hold for 2 h. Cool in air

Steels / 211

Sequence

Forgings l l l l l l

Austempering.

Processing

Carbon

l l

Forge Normalize Anneal Rough machine Senlitinish machine Austenitize Quench Temper

1095: Effect of Prior Microstructure on Hardness After Tempering. Steel tempered at 565 “C (1050 “F) 1095: isothermal Transformation C, 0.29 Mn. Austenitized

Diagram. Composition: 0.89 at 885 “C (1625 “F). Grain size, 4 to 5

1095: End-Quench 1095: Isothermal Transformation

Diagram. Modified.

sition: 1.13 C, 0.30 Mn. Austenitized size, 7 to 8. Martensite temperatures

at 910 “C (1670 estimated

Compo“F). Grain

Mn. Austenitized

Hardenability. Composition: 0.89 at 885 “C (1625 “F). Grain size, 5

C, 0.34

212 / Heat Treater’s

1095:

As-Quenched

Guide

Hardness

(Water)

0.90 to 1.03 C, 0.30 to 0.40 Mn. 0.040 P max, 0.050 S max; grain Grade:,srze 50%, 5 to 7; 500/b, 1 to 4 Size round in.

mm

I .’ ,

12.7 3.1 SO.8

I2

-I

gas quenching

(forced air), and nor-

Center

55 Ib

48 4-l

63

43

-IO

63

38

30

b5 6-l

I0l.b

Source: Rcpuldic

Hardness, HRC % radius

Surface

1095: As-Quenched Hardness. Forged steel disks, 101.6 mm (4 in.) thick, after oil quenching, malizing (cooling in still air)

Steel

1095: Hardness vs Tempering Temperature. average based on a fully quenched

Represents

an

structure

1095: Cooling Curves. Center cooling curves showing the effect of scale on the cooling curves of 1095 steels quenched without agitation In fast oil at 51 “C (125 “F). Specimens were 13 mm (0.50 in.) diam by 64 mm (2.50 in.) long

1095: End-Quench Hardenability. C, 0.28 Mn. Austenitized

Modified. Composition: 1.17 at 925 “C (1695 “F). Grain size, 7 to 8

1095: Quenching. Differences in Brinell hardness of forged 1095 steel disks, 100 mm (4 in.) thick, after oil quenching, gas quenching (forced air), and cooling in still air (normalizing)

1095: Mechanical Properties Treated by Two Methods Specimen number I 2 3 4

Beat treatment Water quench and temper Waterquench and temper hlartrmpcr and temper Matemper and temper

(13) In 25 nun or I in.

of 1095 Steel Heat

Hardness, ARC 53.0 52.5 53.0 sz.l3

Impact energ J 16 I9 38 33

ft

Ibf I2 I-l 28 2-l

ElongaIion( %, 0 0 0 0

Nonresulfurized

1095: Microstructures.

Carbon Steels / 213

(a) Picral, 1000x. Bar, normalized by austenitizing at 870 “C (1800 “F). Cooled in air. Partly unresolved pearlite (black); partly lamellar peariite. (b) Nital, 1000x. Hot rolled bar, 31.75 mm (1.25 in.) diam. Spheroidized by holding at 875 “C (1245 “F), 15 h. Air cooled. Spheroidal cementite particles in ferrite matrix. (c) 2% nital, 500x. Wire, austenitized at 940 “C (1725 “F). Oil quenched. Mixture of fine pearlite and lower bainite (dark areas). Untempered martensite (light areas). Structure resulted from slack quenching. (d) Picral, 1000x. Austenitized at 870 “C (1800 “F); austenitized at 815 “C (1500 “F). Water quenched. Fine, untempered martensite. caused by more severe quench. Some spheroidal cementite. (e) Picral, 1000x. Same as (d), except tempered at 150 “C (300 “F) after quench. Tempered martensite. darker than (d). Some spheroidal cementite particles. (f) 2% nital, 550x. Wire. Austenitized at 885 “C (1625 “F), l/2 h. Quenched to 625 “C (330 “F). Held 5 min. Oil quenched. Lower bainite (dark). Untempered martensite (light). (g) 2% nital, 550x. Same as (f), except held for 20 min in 329 “C (625 “F) quench. Air cooled. Lower bainite (dark). Untempered marlensite (light). (h) 2% nital, 550x. Same as (f), except held 1 h in 445 “C (850 “F). Air cooled (austempered). Mainly upper bainite. (j) Nital, 500 x. Die steel induction hardened to 2.54 mm (0.10 in.). Shown are transition-zone constituents from some fine martensite (top) to prior structure of spheroidal cementite in ferrite matrix (bottom). (k) Nital, 500x. Same as (j), except area shown is nearer surface of steel. Fine martensite (gray) and fine unresolved pearlite (black). Small white particles are spheroids of cementite from prior structure. (n) Nital, 1000x. Same as (m), except higher magnification

214 / Heat Treater’s Guide

1095: Tempering. Effect of prior microstructure on room-temperature hardness after tempering. (a) 1095 steel tempered at 565 “C (1050 “F) for various periods of time. (b) Room-temperature hardness before and after tempering, as well as amount of martensite present before tempering in 4320 steel end-quenched hardenability specimens tempered 2h

Resulfurized (1100

Carbon

Steels

Series)

1108 Chemical

0.80Mn,

Composition.

AISI and UNS: 0.08 to 0.13 C, 0.50 to

Recommended

Heat Treating

Practice

0.040 P max. 0.08 to 0. I3 S

Hardening. hardening

Flame hardening processes

and carbonitriding

are suitable

surface

1110 Chemical Composition. AISI and UNS: 0.60Mn. 0.040 P max. 0.08 to 0.13 S Similar Steels (U.S. and/or Foreign).

0.08 to 0.13 C. 0.30 to

UNS Gi I 100; ASTM A 107; FED QQ-S-637 (C I I 10): SAE J-%03,J-l I?; (Ger.) DfN I .0702; (Jap.) JIS SUM II, SUM I2

Characteristics.

Available principally in bar form. Costs more than low-carbon steels of the 1000 series. because it has been resulfurized to improve machinability. Sulfur addition impairs some mechanical properties. mainly impact and ductility in the transverse direction. Also. adversely affects forgeability, cold formability, and weldability. Use of this steel

should be confined principally fabricating operation

Recommended Hardening. Large

to applications

Heat Treating

where machining

is the main

Practice

portion of parts are used as machined. Can be surface hardened by carbonitriding. salt bath nitriding, or flame hardening

Normalizing and Annealing. or hot roiled and cold drawn normalized or annealed

Generally furnished in the hot rolled condition for best machinability. Rarely

1113: Case Hardening Gradients. Case-hardness gradients scatter from normal variations in noncyanide liquid carburizing

1113 Chemical Composition.

AISI and UNS: 0. I3

C max.0.70 to l.OOMn.0.07

to0.12 P.O.14 too.33

S

Recommended Heat Treating Practice Hardening. Liquid carburizing is a suitable surface hardening process

of 1113 steel showing

216 / Heat Treater’s Guide

1117 Chemical Composition.

AISI and UNS: I.30 hln. 0.040 P max. 0.08 to 0. I3 S

Similar Steels (U.S. and/or Foreign). A107. Al08; FED QQ-S-637 (Clll7r; J-103.J-III. J-II-t

hlfL

0. I-4 to 0.20 C. 1.00 to

GINS

Gl I 170:

SPEC ML-S-IMII;

ASThl

SAE

Characteristics. Morecostly than the 1020 or IO2 I grades. because tt has heen resulfurized for improved machinability. This impairs certain mechanical properties. forgeability. and cold formability. Manganese content is substantially higher than that of 1020 and I02 I. Hardenahility is not significantly higher. because a portion of the manganese combines viith the

higher sulfur to form manganese sulfide stringers. These promote chip breakage and excellent machinability. Available only in bar stock for machining directly into parts. most often tn automatic machines

Recommended Case Hardening.

Heat Treating

Practice

Almost always used as machined or case hardened. (See process for 1020). Flame hardening. carbonitriding, liquid carbutizmg, gas carhuriring. austempering. and mat-tempering are suitable processes

Normalizing and Annealing. normalizing

teGtperature

Rarely required by fabricator. is 900 Y-( I hS0 “F) -

1117: Gas Carburizing. Effect of normal variations burizing on hardness gradients. 10 tests

Qpical _.

in gas car-

1117: Gas Carbonitriding. Carbonitrided at 815 “C (1500 “F), 1 l/2 h. Oil quenched. Required minimum hardness of 630 Knoop (500 g load) at 0.001 in. below surface was met by reducing percentage and flow rate of ammonia or by adding a diffusion period after carbonitriding, as indicated. Atmosphere consisted of: endothermic carrier gas, dew point of -1 “C (+30 “F), at 4.245 m3 (150 ft3) per h; natural gas at 0.170 m3 (6 W) per h; and ammonia in amounts indicated.0 : 3% NH, at 5 fWh. 0: 11% NH, at 20 ff/h and diffused last 15 min. A: 11% NH, at 20 ff/h

Resulfurized

1117: Liquid Carburizing. Comparative case depth and case hardness. Specimen, 15.875 mm (0.625 in.) diam. Carburized at 900 “C (1650 “F), 2 h. Brine quenched. 22 tests

1117:

As-Quenched

Hardness

52 I 2 -I

12.7 25.4 SO.8 101.6

Source: Bethlehem

Surface,

(Water)

‘/z radius

ERC

HRB

12 37 33 32

96 90 83

Center

HRC

HRB

3S.J

::

HRC ‘9.5

93 86 81

Steel

1117: Hardness vsTempering

Steels / 217

1117: Gas Carburizing. Effect of time and temperature on case depth. (a) Bars, 177.8 mm (7 in.) long. Carburized at 900°C (1650 “F). Water quenched. (b) Bars, 177.8 mm (7 in.) long. Carburized at 925 “C (1695 “F). Water quenched. (c) 12.7 mm (0.5 in.) round bars. Carburized at 900 “C (1650 “F). Quenched in 10% brine

Effect of mass on as-quenched hardness of steel bars, quenched in water; contents: 0.19 C, 1 .lO Mn, 0.015 P, 0.084 S. 0.11 Si; grain size: 2 to 4 Size round tn. mm

Carbon

Temperature. Represents an av-

erage based on a fully quenched structure

L

218 / Heat Treater’s Guide

1117: Selective Carburizing. Typical part selectively in the bath. Area to be carburized is shaded

1117: Microstructures.

carburfzed by partial immersion. Only the portion that is to be carbutized

is immersed

(a) Picral. 200x. Steel bar normalized by austenitizing at 900 “C (1650 “F), 2 h. Cooled in still air. Blocky ferrite (light). Traces of Widmanstatten ferrite. Fine pearlite (dark). Round particles of manganese sulfide. (b) 3% nital, 200x. Carbonitrided 4 h at 845 “C (1555 “F) in 3% ammonia, 6% propane, and remainder, endothermic gas. Oil quenched. Tempered 1 l/2 h at 150 “C (300 “F). Retained austenite (white) and globules of manganese sulfide (dark) in matrix of tempered martensite. (c) Nital, 200x. Carbonitrided and oil quenched. Surface layer of decarburized ferrite, superimposed on a normal case structure of martensite (left side of micrograph). Core material (right) shows patches of ferrite (white)

Resulfurized

Carbon Steels / 219

1117: Case Hardness Gradients. Case hardness gradients for two carbon steels and four low alloy steels, showing effects of carburizing temperature and time. Specimens measuring 19 by 51 mm (0.75 by 2 in.) diam were carburized, air cooled, reheated in neutral salt at 845 “C (1555 “F), and quenched in nitrate/nitrite salt at 180 “C (355 “F)

Resulfurized

Carbon Steels / 219

1118 Chemical COmpOSitiOn.

AK1 and UNS: 0.14 I .60 Mn, 0.040 P max. 0.08 to 0.13 S

Similar Steels (U.S. and/or Foreign). Al07,

Al08;

FED QQ-S-637

Characteristics.

to

0.20

C.

UNS G1 I 180; (Cl 118); SAE 5403, J412. J414

1.30

to

ASTM

More costly than the I020 or IO2 I grades, because it has been resulfurized for improved machinability. This impairs certain mechanical properties, forgeability, and cold formability, While a portion of the manganese (relatively high) combines with sulfirr, there is still a

sufftcient amount left over to result in higher hardenability 1020or 1021

Recommended

Heat Treating

compared

with

Practice

Case Hardening. Almost always used as machined or case hardened, as described for 1020. Greater hardenability. compared with 1020, allows the section thickness of carburized I I I8 to be extended at least to 12.7 mm (0.5 in.). Fully hardened by oil quenching. Flame hardening. carbonitriding, liquid carburizing. and martempering are suitable processes

220 / Heat Treater’s

Guide

1118: Liquid Carburizing.

Carburized

at 955 “C (1750 “F).

Slowly cooled

1118: Hardness vs Tempering Temperature. Represents an average based on a fully quenched

1118:

As-Quenched

Hardness

(Water) of steel bars, quenched in 0.08 S, 0.09 SI; grain size:

Size round in. mm ‘!I, I‘ 2 1 Source

Surface, ERC

IZ 7 25.-l SO.8 101.6 Brrhlcheni

Srrrl

43 36 34 32

‘,$ radius HRC 36 ___ _..

Center HRB

ERC

ClRB

33 9s, 91 8-i

96.5 87.0 82.0

structure

220 / Heat Treater’s

Guide

1137 Chemical

Composition. AISI and UNS: I .6S Mn. 0.040 P mari. 0.08 to 0. I3 S

Similar C: ASTM J-111

Steels (U.S. and/or Foreign). Al07,

AlO9. A3ll;

FEDQQ-S-637

0.31 to 0.39 C. 1.35 IO LINS G10200: AhlS 502-t (Cll37): SAE J-tO3. Jll2.

In aerospace practice. parts are normalized allowed to cool below S-10 ‘C t 1000 “F)

at 785 “C (1350 “F) and

Hardening.

Characteristics.

Essentially a high-manganese version of 1037. which has been resulfurized for improved machinabilib. Higher manganese content provides higher hardenability. although not as much as indicated by the manganese content t I .3S to I .65). Some of this manganese combines with increased sulfur to foml manganese sulfide stringers. Available only as hot rolled or hot rolled and cold drawn bars. for producing parts by machining processes. Too high m carbon for good weldability. Sulfur content can cause hot shortness. Should not be used L+hen welding is imolved

Recommended

Annealing. Heat IO 885 “C t 1625 OF). Furnace cool to 650 “C (1300 “F) at a rate not to exceed 38 ‘C (SO “F) per h to 650 “C ( 1200 “F).

Heat Treating

Practice

Normalizing. Not usually required If necessary, heat to 900 “C (I650 “FL Cool in air. In aerospace practice, parts are normalized at 900 “C (I650 “F)

Heat to 845 “C t I SSS “F). Flame hardening and carbonitridinp are suitable surface hardening processes. Quench in water. brine. or aqueous polymers. In aerospace practice. parts are austenitized at 845 “C (IS55 “F) and quenched in oil. \+ater. or polymer. For full hardness, oil quench sections not esceeding 9.535 mm (0.375 in.) thick

Tempering.

As-quenched hardness of approximately 45 HRC. Hardness can be reduced bq tempering In quenching with oils or polymers. parts ma> be tempered at several different temperatures to get specitic ranges of tensile strengths: 380 “C (895 “F) for 620 to 860 MPa (90 to 12.5 ksi); 329 “C (625 “F) for 860 to 1035 MPa (I 25 to I50 ksi). In quenching with water. more options are available. as follows: S-IO ‘C (I000 “F) for 620 to 860 hlPa t90 to I25 ksi); 480°C (895 “F) for 860 to 1035 MPa ( I25 to IS0 ksi): 125 ‘C (795 “FJ for 1035 to II70 hlPa t IS0 to 170 ksi): 370 “C (700 “F)

Resulfurized

for ll75to 1240MPa(l60to MPa(l80to2OOksi)

Strengthening

180ksij;3lS”C(6OO”F)for

12-lOto 1380

Recommended l

by Cold Drawing

and Stress Relieving.

l l

1137

1137

As-Quenched

Hardness

(Water)

Effect of mass on as-quenched hardness of steel bars, quenched in water: contents: 0.37 C, 1.40 Mn, 0.015 P, 0.08 S, 0.17 SI; grain size: 1 to4 Size round in.

mm

‘92

11.7 15.1 SO.8 101.6

I 2 -l Source: Bethlehem

Steel

Surface

Hardness, HRC ‘12radius

l

Sequence

As-Quenched

Hardness

(Oil)

Effect of mass on as-quenched hardness of steel bars, quenched in pdlicontents: 0.37 C, 1.40 Mn. 0.015 P, 0.08 S, 0.17 Si; gram size: 1

Surface

Etardness, ERC ‘/z radius

48 31 28 21

13 ‘8 22 IX

Size round Center

Steels / 221

Rough machine Austenitize Quench Temper Finish machine

Grade I I37 bars and other medium-carbon resulfurized steels are frequently strengthened to desirable levels without quench hardening. Increase the draft during cold drawing by IO to 35% above normal. Stress relieve by heating at approximately 3 I5 “C (600 “F). Produces yield strengths of up to 690 MPa (100 ksi) or higher in bars up to about 19.05 mm (0.75 in.) diam. Machinability is very good

l

Processing

Carbon

in. 1.II

I2 -I Source: Bethlehem

mm 12.7 3.4 50.8 I0l.h

Center 42 73 I8 I6

Steel

1137: Hardness vs Tempering Temperature. erage based on a fully quenched structure

Represents

an av-

Resulfurized

Carbon

Steels / 221

1139 Chemical

Composition.

AISI

and UNS:

0.35 to 0.43 C. 1.35 to

1.65Mn.0.040Pmax.0.13to0.20S

Similar

Steels (U.S. and/or

Foreign).

LINS GI 1390; FED QQ-

S-637 (Cl 139); SAE 5103

Characteristics.

Characteristics neat+ parallel with I 137. Carbon and sulfur contents slightly higher. These differences result in slight11 higher as-quenched hardness tas high as -I7 HRC). slightly lower hardenabilit) t because of higher sulfur content), and even better machinability than I 137. Never recommended for welding or forging

Recommended Normalizing.

Heat Treating

Not usually

required.

Practice

If necessary, heat to 900 “C t 1650

“FJ. Cool in air

Hardening. Heat to 8-tS ‘C t IS55 “FL Flame hardening and carbomtridmg are suitable surface hardening processes. Quench in water or brine. For full hardness. oil quench sections not exceeding 9.525 mm (0.375 m.) thick Tempering.

As-quenched hardness of approximately ness can be reduced bq tempering

Strengthening

Heat to 885 “C t I675 “FL Furnace cool to 650 ‘C t 17-00 “FL at a rate not to exceed 28 “C (SO ‘Fj per h

Hard-

and Stress Relieving.

Grade II39 bars and other medium-carbon resulfurired steels are frequentl) strengthened to desirable Ie~els \\ithout quench hardening. Increase the draft during cold drawing by IO to 35% above normal. Stress relirbe b> hsatntg at approsunatel) 315 “C (600 “F). Produces yield strengths of up to 690 hlPa (,I00 ksit or higher in bars up to about 19.05 mm to.75 In.) dinm. hlachinability is ~2t-y good

Recommended l l l

Annealing.

by Cold Drawing

47 HRC.

l l

Rough machine r\ustsnitize Quench Temper Finish machine

Processing

Sequence

222 / Heat Treater’s

Guide

1139: Hardness vs Tempering Temperature. Represents an average based on a fully quenched

structure

222 / Heat Treater’s

Guide

1140 Chemical

Composition.

AISI and UNS: 0.37 to 0.44 C, 0.70

to

I .OOMn, 0.040 P max. 0.08 to 0. I3 S

Similar

Steels (U.S. and/or

S-637(Cl 140); SAE 5403. J412. 35 MF 4; (Swed.) SSt4 1957

Foreign). UNS G11400; FED QQJ-113; (Ger.) DIN 1.0726; (Fr.) AFNOR

Hardening. Heat to 835 ‘C ( IS55 “FL Flame hardening and carbonitriding are suitable surface hardening processes. Quench in water or brine. For full hardness, oil quench sections not exceeding9.525 mm (0.375 in.) thick Tempering.

As-quenched hardness of approximately ness can be reduced by tempering

50 HRC.

Hard-

Strengthening

Characteristics.

Slightly higher carbon range, compared with I 139. of no practical significance. Hardenability is lower because of lower manganese content. Otherwise, same characteristics as I I37 and I 139, including response to abnormal drafts in cold drauing and a subsequent stress relief. Not used where forging or welding is involved. Machinability is excellent

Recommended Normalizing.

Heat Treating

Not usually

required.

Practice

If necessary. heat to 900 “C ( 1650

“F). Cool in air

by Cold Drawing and Stress Relieving. Grade 1140 bars and other medium-carbon resulfurized steels are frequently strengthened to desirable levels without quench hardening. Increase the draft during cold drawing by IO to 358 above normal. Stress relieve by heating at approximately 3 IS “C (600 “F). Produces yield strengths of up to 690 MPa (100 ksi) or higher in bars up to about 19.05 mm (0.75 in.) diarn. Machinability is very good

Recommended l l l

Annealing.

Heat to 885 “C ( I625 “F). Furnace cool to 650 “C ( 1200 “F). at a rate not to exceed 28 “C (50 “F) per h

l l

Processing

Sequence

Rough machine Austenitize Quench Temper Finish machine

1140: Hardness vs Tempering Temperature. erage based on a fully quenched structure

Represents

an av-

222 / Heat Treater’s

Guide

1141 Chemical

Composition.

AISI and UNS: 0.37 to 0.45 C, 1.35 to

I .65 Mn. 0.040 P max. 0.08 to 0. I3 S

Similar

Steels (U.S. and/or Foreign).

A107.A108,A311;FEDQQ-S-637;SAE5403.5412,5411

UNS

GI 1410:

ASTM

Characteristics.

Most widely used medium-carbon resulfurized steel. As-quenched full hardness of approximately 52 HRC, when carbon is near high side of the range. Slightly lower hardness for middle or lower end of the range. High manganese content imparts higher hardenability compared with I I-IO, but almost the same as I 139. Available in pretreated condition.

Resulfurized Subjected to abnormally heavy drafts followed by stress relieving. grade I 137.) Never recommended for forging or welding

Recommended Normalizing.

Heat Treating

Not usually

required.

(See

Practice

If necessary. heat to 885 “C (I 615

1141

As-Quenched

Hardness

Carbon

Steels / 223

(Oil)

Effect of mass on as-quenched hardness of steel bars, quenched in oil; contents: 0.39 C, 1.58 Mn, 0.02 P, 0.08 S, 0.19 Si; grain size: 90%, 2 to 4; 1 O%, 5

“FJ. Cool in air

Annealing.

llsually purchased by fabricator in condition for machining. If required. may be annealed by heating to 835 “C ( I555 “F). Furnace cool to 650 “C ( IXIO “F) at a rate not to exceed 28 “C (50 “F) per h

Size round in.

mm

‘/: 1 2 4

12.7 ‘5.4 SO.8 101.6

Hardening. Austenitize at 830 “C (IS?5 “F). Flame hardening. carbonitriding, and martempering are suitable processes. Quench in water or brine. For full hardness. oil quench sections under 9.525 mm (0.375 in.) thick Tempering.

Depending upon precise carbon content. as-quenched hardness is usually 48 to 52 HRC. Hardness can be reduced by tempering

Recommended l l l l l

Rough machine Austenitize Quench Temper Finish machine

Processing

Sequence

Source: Bethlehem

Surface 52 18 36 27

Eat-does, ERC ‘4 radius 49 43 28 22

based

46 38 22 18

Steel

1141: Hardness vs Tempering Temperature. Represents erage

Center

on a fully quenched

structure

an av-

Resulfurized

Carbon

Steels / 223

1144 Chemical

Composition. AISI and IJNS: 0.10 to 0.38 C. I.35 to I .65 Mn. 0.040 P max. 0.2-I to 0.33 S

brim. For full hardness, 10.375 in.) thick

Similar

Tempering.

Steels (U.S. and/or Foreign).

UNS

GI 14.40;

ASTM

A108.A311:FEDQQ-S-637(CII~?);SAEJ403.J41?.J413

Characteristics. Special-purpose grade. Very high sulfur content. equal to free-machining 1213. permits extremely fast machining with heavy cuts. Machined fmishes unusually good. High sulfur content reduces transverse impact and ductility. Can be drawn by heavy drafts at elevated temperature, 370 “C (700 “F). which results in relatively high strength and high hardness. up to 35 HRC. Machinability is excellent. Widely used for producing machined parts put in service without heat treatment. Can be purchased in cold drawn condition and heat treated. Depending upon precise carbon content, as-quenched and fully hardened I I44 should be approximately 52 to 55 HRC. Never used I$ here forging or welding is involved

Recommended Normalizing.

Heat Treating

Seldom required.

Annealing.

Seldom necessary. May be annealed by heating to 845 “C ( I555 “F). Furnace cool to 650 “C ( I200 “F), at a rate not to exceed 28 “C (SO “F) per h

Hardening.

sections

less than 9.525

mm

Depending upon precise carbon content, as-quenched hardness of usually 52 to 55 HRC. Hardness can be reduced by tempering

Recommended l l l l l

Processing

Sequence

Rough machine Austenitize Quench Temper Finish machine

1144:

As-Quenched

Hardness

(Oil)

Effect of mass on as- uenched hardness of steel bars quenched in oil. contents: 0.46 C, ? .37 Mn, 0.019 P, 0.24 S. 0.05 hi; grain size: 75+/o, 1 to 4; 25%, 5 to 6

Practice

If necessary. heat to 885 “C ( I625 “FL

Cool in air

carbonitriding

oil quench

Austenitize at 830 “C (I 525 “F). Flame hardening and are suitable surface hardening processes. Quench in water or

Size round

ill.

mm

Surface

‘/J

12.7 25.4 50.8 101.6

39 36 30 27

I 2 1

Source: Bethlehem Stzcl

Hardness, ERC ‘/r radius 32 29 27 .._

1:: 98

Center 28 23 22 __

1:: 97

224 / Heat Treater’s

Guide

1144: Hardness vsTempering Temperature. Represents an average based on a fully quenched

structure

224 / Heat Treater’s

Guide

1146 Chemical

Composition.

AISI and UNS: 0.X

to

0.49 c. 0.70 to

I .OO Mn. O.O-tO P max. 0.08 to 0. I3 S

Similar

(U.S. and/or Foreign).

Steels

UNS GI 1460; FED QQ-

S-637 (Cl 136): SAE J-103, J-tl?. J-II-t; tGer.) DIN 35 MF 1; (Swed.) SSt4 1973

1.0727; (Fr.) AFNOR

Annealing.

Seldom required by the fabricator. If necessary, heat to S-0 “C ( I SSS “F). Furnace cool to 650 ‘C ( 1200 “F) at a rate not to exceed 28 “C (SO ‘F) per h

Hardening. Austenitire at 830 “C ( IS25 “FL Flame hardening, carbonitriding, austemperinp. and mar-tempering are suitable processes. Quench in water or brine. For full hardness. oil quench sections less than 9.525 mm (0.375 in.) thick

Characteristics. An I I-IO with higher carbon. Excellent machinability and relatively low hardenability. Amenable to strengthening by heavy drafts and stress relieving. Higher carbon, lower manganese. and lower hardenability make it popular for induction hardening. Never use uhen forging or welding is involved. Can be quenched and tempered. Asquenched hardness of 55 HRC or slightly higher. depending on carbon content

Tempering.

Recommended

l

Heat Treating

Practice

nrss is usually recommended

Martempering.

Cool in air

Seldom required.

If necessary. heat to 885 “C ( l62S “F).

Austenitize

at 815 “C ( IS00 “F). Martemper

in oil at

I75 “C (345 “F)

Recommended l l

Normalizing.

Depending upon prectse carbon content. as-quenched hardSS HRC. Hardness can be reduced by tempering. under practice

l l

Processing

Sequence

Rough machine Austenitize Quench Temper Finish machine

1146: Hardness vs Tempering Temperature. Represents an average based on a fully quenched

structure

Resulfurized

Carbon

Steels / 225

1151 Composition.

Chemical

AISI and UNS: 0.48 to 0.55 C, 0.70 10

I .OO Mn, 0.040 P max. 0.08 to 0. I3 S

Similar

Steels (U.S. and/or Foreign).

Al07. Al08. A3ll; FEDQQ-S-637tCllSl): SAEJ403. J4l2, J-II-I

UNS Cl IS IO; ASThl hlILSPEC hlIL-S-30137A;

Characteristics. Resulfurized version of 1050. Carhon ranges the same. Although rhe I I5 I manganese comenl is slightly higher. some of this manganese combines \\iith the high sulfur, so that the hardenabihty is almost the same as 1050. As-quenched hardnesses of 1050 and I I51 are essentially the same. SS HRC or slightly higher. I IS I also used for induction hardening. 1050 used for parts to be forged. I IS I used for parts 10 be machined from bars

Recommended Normalizing. Cool in air

Seldom

Heat Treating used. If necessary,

Practice heat to 870 “C ( 1600 “F).

Annealing. Heat IO 870 “C ( 1600 “F). Furnace 81 a rate not to exceed 28 “C (50 “F) per h

cool

IO

650 “C ( 1200 “F)

Hardening. Austenitize 31 830 “C ( 1525 “F). Flame hardening, induction. and carbonitriding are suitahle surface hardening processes. Quench in nater or brine. Oil quench sections under 6.35 mm (0.25 in.) thick Tempering erly austenitizcd

After Hardening. and quenched.

Recommended l l l l l

Hardness of at least 55 HRC. if propHardness can be adjusted by tempering

Processing

Sequence

Rough machine Austenilize Quench Temper Finish machine

1151: Hardness vs Tempering Temperature. erage based on a fully quenched structure

Represents

an av-

1151: Microstructure. 2% nital, 500x. Manganese sulfide stringers (black) in steel bar. Remainder is dispersion of spheroidized carbide in ferrite matrix. Micrograph is cross section, taken perpendicular to rolling direction

1211 Chemical Composition.

UNS GlZllOand

AlSI/SAE

1211: 0.13 C

max. 0.60 to 0.90 Mn. 0.07 to 0.12 R 0. IO to 0. IS S

Similar Steels (U.S. and/or Foreign).

ms

G I?. I IO;

ASTM

AlO7.Al07(BIIII),Al08.Al08(BIIII);FEDQQ-S-637(Cl2ll);S~ 5403

Characteristics.

Machinery steel that has been resulfurized and rephosphorized has better machinability than that of grade I I IO. Furnished in hot rolled or hot rolled and cold drawn condition. The latter condition is

the better for machinability. Intended for fabrication recommended for forging. cold forming, or welding

Recommended

Heat Treating

Normalizing and Annealing. Light Case Hardening. bath nitriding

process described

by machining.

Never

Practice

Seldom required

hlay be desired. See carbonitriding for 1008

and salt

1212 Chemical

COIIIpOSitiOn. UNS and SAE/AISI: 1.00 Mn, 0.07 to 0.12 P. 0. I6 to 0.23 S

Similar

0.13 C max. 0.70 to

Steels (U.S. and/or

D; ASTM A107. Al07 (Cl212);SAEJ403;(Ger.)

Foreign). LJNS G 12 120; AMS 5010 (81212). A108. Al08 (Bl212); FED QQ-S-637 DIN I.071 I:(ltal.) LINI IOS ZO;(Jap.)JISSLJM

21

Characteristics. Similar tents are higher. Machinability

to 121 I, except sulfur and manganese conbetter than that of I2 I I. Adverse effects of

sulfur and phosphorus greater

Recommended Normalizing

on mechanical

Heat Treating

and Annealing.

Light Case Hardening. bath nitriding

and fabrication

process described

properties

are slightly

Practice

Seldom required

May he desired. See carbonitriding for 1008

and salt

1213 Chemical

COtnpOSitiOn. UNS and SAE/AISI: I.00 Mn, 0.07 to 0.12 P. 0.2-t to 0.33 S

0.13 C max. 0.70 to

Similar

Steels (U.S. and/or Foreign). UNS G 12 I 30: ASME Al07,Al07(BlIl3j,Al08.AIO8(BIll3);FEDQQ-S-637(Cl9l3);SAE J403; (Ger.) DIN I .0715; (Ital.) UNI 9 SMn 23: (Jap.) JIS SUM 22: (U.K.) B.S. 220 M 07 Characteristics. Nearly identical sulfur further enhances machinability fabrication properties

to those of I2 12. Greater content of at the sacrifice of mechanical and

Recommended Normalizing

Heat Treating

and Annealing.

Light Case Hardening. bath nitriding

process described

Practice

Seldom required

May be desired. See carbonitriding for 1008

and salt

Rephosphorized

and Resulfurized

(1200 Series) / 227

12l.14 Chemical Composition.

UNS and SAE/AISI: 0. I5 C max. 0.85 to I. I5 Mn. 0.04 to 0.09 P. 0.26 to 0.35 S. 0. I5 to 0.35 Pb

Similar Steels (U.S. and/or Foreign). UNS Gl214-k A107, Al08; SAE 5403, J412, J414; (Ger.) DIN 1.0718; (Ital.) SMnPb 23; (Jap.) JIS SUM 22 L. SUM 24 L; (Swed.) SS)4 1913 Characteristics.

ASTM UNI 9

Contains a lead addition of 0. I5 to 0.35% indicated by L in designation. Represents the ultimate in free-machining characteristics. but an even further sacrifice of mechanical and fabricating properties. such as forgeability. cold formability, and weldability. Addition of

lead further enhances machinability in terms of high speeds with heavy cuts and provides excellent finishes on machined surfaces. Sometimes saves an extra machining operation

Recommended

Heat Treating

Normalizing and Annealing. Light

Case

bath nitriding

Hardening. process described

Practice

Seldom required

May be desired. See carbonitriding for I008

and salt

Rephosphorized

and Resulfurized

(1200 Series) / 227

1215 Chemical

COIIIpOSitiOn. UNS and SAE/AISI: I.05 Mn. 0.04 to 0.09 P. 0.26 to 0.35 S

Similar

Steels (U.S. and/or Foreign).

0.09 C max. 0.75 to

UNS Gl~lso;

FED QQ-

S-637: SAE J4 12

Characteristics.

Compared with I?. 13. with minor adjustments in carbon, manganese, phosphorus. and sulfur contents. No major effects on mechanical or fabricating properties. Represents another free-machining

steel. Commonly used for parts completed in automatic multispindle machine tools

Recommended Normalizing

Heat Treating

and Annealing.

Practice

Seldom required

Light Case Hardening. May be desired. See carbonitriding and salt bath nitriding process described for 1008

1215: Microstructures. (a) As polished (not etched), 1000x. Cold drawn steel tube. Longitudinal view. Segmented polished (not etched), 1000x. Cold drawn steel tube, at lower magnification. Sulfide inclusions shown

sulfide inclusion. (b) As

High

Manganese

Carbon

(1500

Steels

Series)

1513 Chemical

Composition. MS1 I .-IO Mn. 0.040 P max. 0.050 S max

Similar

Steels (U.S. and/or

and UNS:

Foreign).

0.10 to 0.16 C. I. IO

UNS G

to

IS 130; SAE J-103.

J-II2

Characteristics.

Essentially the high-manganese version of 1012. However. the higher manganese content provides slightly greater strength in the normalized or annealed condition and some\< hat better core properties when case hardened. Excellent forgeability and weldabili?. Rsasonably good cold formability, only slightly less than IO1 2. hlachmability is very poor when compared with the II00 and 1200 grades. Generally avarlable in wrious product forms. includinp flat stock. bars. and forging stock

Forging. Heat to approximately 1290 “C (2355 “F). Finish forging fore temperature drops bclou 925 “C t 1695 “F)

Recommended Normalizing.

Heat Treating

Heat to 885 T

be-

Practice

t 1625 “F). Cool in still air

Annealing.

For clean surfaces. heat to approxmlately 885 “C (163-S “F) in lean exothermic atmosphere. Cool in cooler section of continuous furnace

Case Hardening. Carbonitride at 760 to 870 “C (1400 to 1600 “F) in an enriched sndothemtic carrier gas. plus ahout 10% anhydrous ammonia. Case depths from 0.076 to 0.26 mm (0.003 IO 0.01 in.). Oil quench directly from carbonitriding temperature. Pro\ ides maximum surface hardness. Salt baths can produce similar results

1582lH, Chemical

15821RH

COWpOSitiOn.

15BZlH.

UNS H15211 and SAE/AISI:

0.17 to 0.74 C. 0.70 to 1.10 hln. 0. IS to 0.35 Si. t0.0005 to 0.003 B can be expected). SAE 15B21RH: 0.17 to022 C.O.80 to 1.10 hln.0.15 too.35 Si (0.0005 to 0.003 B can be expected)

Similar

Steels (U.S. and/or

SAEJl168.51868:

Foreign).

15BZlH.

UNS H IS2 I I :

(Ger.) DIN 1.5513: ASTh1Yl-l

Characteristics. Nonfree machining steel. Can be cold formed to some degree. Readily weldable. When carbon IS on the high side and with the higher manganese and addition of boron. a combination can exist where some preheating prior to welding is necessary to avoid weld crackng. Combination of higher manganese and boron provides whstantial increase in hardenabilit), compared with 1020

Annealing.

Excellent forgeahilitj. below 925 “C ( 16% “F)

Heat to I260 “C (1300 ‘F). Do not forge

Heat Treating

Tempering. some sacrifice

l

l

l l

Normalizing.

Heat to 925 “C ( 1695 “FL Air cool

in the

Optional. Temper at ISO “C (300 “F) for I h or higher if of hardness can be tolerated

Recommended l

l

Practice

preferably

Can he case hardened bj an! one of several processes. from light case hardening h) carhonitridinp and salt bath nitriding described for grade IO08 to deeper case carhuriring in gas. solid. or liquid media. Because of higher hardenahility. oil quench thicker sections for full hardness. Carburize and quench as for 1020

l

Recommended

“F). Cool slo~lp.

Hardening.

l

Forging.

Heat to 870 cIe Quench Temper Finish grind

Sequence

High Manganese

15B21H: Hardenability Curves. Heat-treating “C (1700 “F). Austenitize: 925 “C (1700 “F)

Hardness purposes J distance, mm

Hardness purposes J distance, ‘/,6 ill. 1 1,s ? 3 3 3s 4 4.5 i.s 5 55 7 7.5 3 9

limits for specification Hardness, hlaximum

HRC hlinimum

limits for specification Hardness, Masimum

HRC hlinimum 41 -II -IO SY 38 36 30 13 20

temperatures

recommended

Carbon

Steels (1500 Series) / 229

by SAE. Normalize (for forged or rolled specimens

only): 925

1

230 / Heat Treater’s

Guide

15621RH: Hardenability “C (1700 “F). Austenitize-

Hardness purposes J distance, %a in. I 2 3 4 5 6 7 8 9 IO II 12 13 I4 IS 16 I8 20 22 24 26 28 30 32

Hardness purposes J distance. mm I.5 3 5 7 9 II 13 IS 10 15 30 35 lo 1s

Curves. Heat-treating 925 “C (1700 “F)

limits for specification Hardness, Maximum

ARC Minimum

47 46 44 43 37 30 24 22 20

42 II 39 33 24 20

limits for specification Hardness, Maximum 41 46 44 40 32 24 22 20

HRC Minimum 42 II 38 29 21

temperatures

recommended

by SAE. Normalize for forged or rolled specimens

only: 92:

High Manganese

Carbon

Steels (1500 Series) / 231

15821 H: Hardness vs Tempering Temperature. average based on a fully quenched structure

15B21H: End-Quench Dktance frum quenched surface &in. mm

I I .s 2 2.5 3 3.5 4 4.5 5

I.58

2.37 3.16 3.95 4.1-l 5.53 6.32 1.11

7.90

Hardenability

Hardness, HRC min max

18 48 -1-l 4-l -I6 -Is 4-l 42 40

-II 41 -IO 39 38 36 30 23 20

Distance from quenched surface mm ‘/,a in.

6 6.5 1 1.5 8 9 IO I2 I-1

Eardness, HRC max

9.48 10.27

35 32

II.06 II.85 12.64 l-l.22 IS.80 18.96 22.12

27 22 20

Represents

an

High Manganese Carbon Steels (1500 Series) / 231

1522,1522H Chemical Composition.

1522. AI.9 and UNS: 0.18 to 0.21 C. I. IO to 1.40 h4n. 0.040 P max. 0.050 S max. 1522H. UNS H15220 and SAE/AISI 1522H: 0.17 to 0.25 C. I .OO to I SO Mn. 0. IS to 0.35 Si

Recommended

Similar Steels (U.S. and/or Foreign). 1522. UNS G 15220:

Annealing.

J403, J412. 15228. UNS HI5220; SAE Jl268: UNI G 22 Mn 3; (Jap.) JIS SMnC 21

furnace

(Ger.) DIN

SAE 1.1133: (Ital.)

Normalizing.

Heat Treating

Practice

Heat to 92s “C t 1695 “F). Air cool Heat to 870 “C t 1600 “F). Cool slowly,

preferably

in the

Hardening.

Characteristics.

Represents the principal carburizing grade of the I SO0 series. Characteristics similar to I SB2 I H. Nominal manganese content is higher which increases hardenability to a considerable extent. However. contains no boron. As a result, hardenability bands are not .greatl! different for steels ISBZIH and lS22H. Weldability and forgeability are good

Forging. Heat to I260 “C (2300 “F). Do not forge below 925 “C t 1695 “F). For lS22H. drop forge from 900 to I250 “C (I650 to 2380 OF)

Can be case hardened b) any one of several processes. from light case hardening by carbonitriding and salt bath nitriding described for grade 1008 to deeper case carburizing in gas. solid. or liquid media. See carhurizing process described for grade 1020. For lS22H. use carburizing temperature of 900 to I250 “C t I650 to 2280 “F). Use oil for cooling medium. Because of higher hnrdenabilib. thicker sections can be oil quenched for full hardness

Tempering. some sacrifice

Optional. Temper at IS0 “C (300 “F) for I h or higher if of hardness can be tolerated

232 / Heat Treater’s

Recommended l l l l l l l l l

Guide

Processing

Sequence

1522, 1522H: Hardness vs Tempering Temperature. sents an average based on a fully quenched structure

Forge Nomlalize Rough machine Semifinish machine and grind Cxburize Diffwion cycle Quench Temper Finish grind

1522H: End-Quench Distance from quenched surface l/j6 in. mm I 1.5 2 2.5 3 3.5 -I 4.S 5 5.5

I.58 2.37 3.16 3.95 4.7.l s.s3 6.32 7.1 I 7.90 8.69

Hardenability Eardness, HRC max min

so -18

JI 41

17 46 1.5 -12 39 37 3-l 32

32 27 22 21 70 .,.

Distance from quenched surface ‘ii6 h. mm 6 6.5 7 7.5 8 9 IO 12 I-I I6

9.48 IO.27 I I.06 II58 126-l l-1.22 IS.80 18.96 Z’.II ‘5 ‘Y __.-

Hat-dries. HRC max 30 28 27 __. 25 23 22 20

Repre-

High Manganese Carbon Steels (1500 Series) / 233

1522H: Hardenability Curves. Heat-treating temperatures (1700 “F). Austenitize:

925 “C (1700 “F)

Hardness limits for specification purposes J distance, mm

Eardness, Maximum

ARC hlinimum

Hardness limits for specification purposes I distance, ‘/,6 in. I I.5 3 !.5 3 3.5 + 4,s

i.5 5 i.S

Hardness, Maximum SO 48 17 16 -IS 12 39 37 3-l 32 30 28 27

HRC hlinimum

recommended

by SAE. Normalize (for forged or rolled specimens

only): 925 “C

1

234 / Heat Treater’s

1522: Continuous

Guide

Cooling Transformation

Diagram. A British steel with a chemical composition roughly equivalent to 1522: 0.19 C, 1.20

Mn, 0.020 P, 0.020 S, 0.20 Si. Hot rolled and austenitized

at 870 “C (1600 “F)

234 / Heat Treater’s

Guide

1524,1524H Chemical

Composition. 1524. AISI and UNS: 0.19 to 0.25 C. I.35 to 1.65 Mn, 0.040 P max. 0.050 S max. 15248. UNS H15240 and SAE/AISI 1524H: 0.18 to 0.26 C, I .2S to I .7S Mn. 0. I5 to 0.35 Si: 152-I was formerly

Similar

designated

Foreign).

1524:

UNS

G15240:

ASTM A510, AS13 (1023). A519. AS-45: SAEJ403.J312,J414:(W. DfN I. I 160. 1524H. UNS H 15210: SAE J 1268; (Ger.) DfN I. I I60

Ger.)

Characteristics.

Essentially a higher manganese version of 1023. Has higher hardenability. Grade lS24H is now available with a guaranteed hardenability band. Considered a borderline grade because it can be case hardened by carburizing or carbonitriding. Popular for this purpose because of relatively high core hardness. This permits use of thinner cases, which conserve thermal energy and decrease processing cost. I524H also used in the hardened and tempered condition where moderate strength is needed. As-quenched hardness of43 HRC or slightly higher can be expected. Even though the carbon content is only 0.26 max. welding must be done with care. because the high manganese may raise the carbon equivalent to a dangerous degree unless preheating and postheating practices are used. Forgeability is excellent. Grade lS21H may be obtained in various product forms

Practice

Direct Hardening. brine. Quenchant

Tempering. by tempering.

Heat to 1215 ‘C (2275 “F). Do not forge below 900 “C ( 1650 “F). For lS24H. drop forge between 900 to I250 “C ( I650 to 2280 “F)

Austenitize at 885 “C (1625 “F). Quench in oil or depends on section thickness

As-quenched as required

hardness of 43 HRC or higher can be reduced

Case Hardening. Can be case hardened by any one of several processes. from light case hardening by carbonitriding and salt bath nitriding described for grade 1008 to deeper case carburizing in gas. solid, or liquid media. Plasma (ion) carburizing is an alternative process. (See carburizing process described for grade 1020). For 1524H. use carburizing temperature of 900 to 925 “C ( I650 to I695 “F). Use oil for cooling medium

Recommended l l l l l

Forging.

Heat Treating

Heat to 925 “C ( I695 “FL Cool in air

Annealing. Heat to 900 “C ( I650 “FL Furnace cool to 675 “C ( I245 “F) at a rate not to exceed 28 “C (SO “F) per h

as IOXX grade

Steels (U.S. and/or

Recommended Normalizing.

l l

Normalize Anneal Rough machine Austenitize Quench Temper Finish machine

Processing

Sequence

High Manganese

1524: Continuous Cooling Transformation

at 870 “C (1600 “F)

1524H: End-Quench Hardenability from

quenched s&ace 916 in. mm

Distance El~dlleSS.

ERC max

min

ti-om

quenched surface ‘/,6 in. mm

Elardness. ERC max

I 1.5

I.58 2.37

51 49

42 42

6 6.5

918 10.27

32 30

2 2.5

3.16 3.95

18 41

38 3-l

7 7.5

II.06 I I.58

29 28

3 3.5 4 4.5 5 5.5

1.74 5.53 6.32 7.1 I 1.90 8.69

15 43 39 38 35 34

29 35 ‘2 20

12.6-I 14.71 IS.80 18.96 22. I? 25.28

27 26 25 23 22 20

8 9 IO I? I-l I6

Steels (1500 Series) / 235

Diagram. A British steel with a chemical composition roughly equivalent to 1524: 0.19 C, 1.50

Mn, 0.020 P, 0.020 S, 0.20 Si. Hot rolled and austenitized

Distance

Carbon

236 / Heat Treater’s

Guide

1524, 1524H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure

1524: Microstructure.

Picral and mtal, 500x. Sheet, 3.175 mm (0.125 in.) thick. Austenitized at 1095 “C (2005 “F). Cooled in air. Dark areas are fine pearlite with some bainite. Light areas are envelopes of ferrite at prior austenite grain boundaries and Widmanstatten platelets of ferrite within grains

1524: Plasma (Ion) Carburizing. Carbon concentration profiles in AISI 1524 steel after ion carburizing for 15 min at 1050 “C (1920 “F) in atmospheres and with flow conditions indicated

High Manganese

1524H: Hardenability

Curves. Heat-treating

(1650 “F). Austenitize:

870 “C (1600 “F)

iardness wrposes I distance, urn .5 / 1 , I I 3 5 10 15

iardness w-poses distance.

‘16io. .s .s ._5 .5 ._5 5

limits for specification Eardness, Maximum

HRC Minimum

51 19 4-l 38 3-l 30 ‘7 2s 13

42 39 26 21

limits for specification Eardness. Maximum 51 49 48 47 45 43 39 38 3s 34 32 30 29 28 27 26 25 23 22 20

HRC hlinimum 42 42 38 34 29 25 22 20

temperatures

recommended

Carbon

Steels (1500 Series) / 237

by SAE. Normalize (for forged or rolled specimens

only): 900 “C

238 / Heat Treater’s Guide

1526,1526H Chemical Composition.

1526. ALSI and UNS: 0.22 to 0.29 C. I. IO

to I .-IO Mn, 0.040 P max. 0.050 S max. 15268. UNS H15260, SAE/AISI 15268: 0.21 to 0.30 C, 1.00 to I.50 Mn. 0. I5 to 0.35 Si

Similar Steels (U.S. and/or Foreign). 1526:

UNS GlS260; ASTM A5 IO; SAE J403. J-l 12: (Ger.) DfN I. I I6 I ; 15268. UNS H 15260:

SAE Jl268 Considered a borderline grade because it can be case hardened by carburizing or carbonitriding. Popular for this purpose because of relatively high core hardness. This permits use of thinner cases, which conserve thermal energy and decrease processing cost. I526H also used in the hardened and tempered condition where moderate strength is needed. As-quenched hardness of 43 HRC or slightly higher can be expected. Even though the carbon content is onlv 0.26 max. welding must be done with care, because the higher manganese may raise the carbon equivalent to a dangerous degree. unless preheating and postheating practices are used. Forgeability is excellent. Grade l526H may be obtained in various product forms

Forging.

Heat to I235 “C (2275 “F). Do not forge below 900 “C ( I650 “F). For I526H. drop forge between I205 to 850 ‘C (2200 to 1560 “F)

Normalizing.

Heat Treating

Heat to 925 “C (I695

1526: Continuous

Direct Hardening. brine or oil. Quenchant hardness

Tempering.

Characteristics.

Recommended

Annealing. Heat to 900 “C ( I650 “F). Furnace cool to 675 “C ( 1245 OF) at a rate not to exceed 28 “C (SO “F) per h

Cooling

Practice

“F). Air cool

Transformation

Mn, 0.020 P, 0.020 S, 0.20 Si. Hot rolled

by tempering,

Diagram.

As-quenched as required

hardness of 43 HRC or higher can be reduced

Case Hardening. Can be case hardened by any one of several processes. from light case hardening by carbonitriding and salt bath nitriding described for grade 1008 to deeper case carburizing in gas. solid. or liquid media. See carburizing process described for grade 1020. For 15268, use carburizing temperature of 900 to 925 “C ( I650 to 1695 “F). Use oil for cooling medium Recommended l

Processing

Anned

l

Rough machine Austenitize (or case harden) Quench Temper Finish grind

l l l

Sequence

Normalize

l

l

and austenitized

Austenitize at 885 “C (I625 “F). Quench in water, will depend on section thickness and required

A British steel with a chemical at 870 “C (1600 “F)

composition

roughly

equivalent

to 1526: 0.28 C, 1.20

High Manganese

1526H: Hardenability Curves. Heat-treating (1650 “F). Austenitize:

Hardness purposes I distance, mm

1.5 3 5 7 1 11 13 15 20

iardness wrposes distance, 46 in.

.5 !.5 1.5 1.5 i.5 i i.5 1.5 1

0 .2 i4

16 18

870 “C (1600 “F)

limits for specification Hardness, Maximum

ARC hlinimum

53 50 44 37 32 28 25 24 .

44 39 24 20 . . . .

limits for specification Hardness, Maximum

53 50 49 47 46 42 39 37 33 31 30 28 27 26 26 24 24 23 22 21 20

ERC

hfinimum 44 42 38 33 26 25 21 20

.

..

.

temperatures

recommended

Carbon

Steels (1500 Series) / 239

by SAE. Normalize (for forged or rolled specimens

only): 900 “C

240 / Heat Treater’s

Guide

1526, 1526H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure

1526H: End-Quench Hardenability Distance from quenched surface ‘46in. mm I I.5 z 2,s 3 3.5 -I 4.5 5 5.5 6

1.58 2.37 3.16 3.95 1.7-l 5.58 6.37 7.1 I 7.90 8.69 9.48

Hardness, HRC mia may 53 so 49 17 46 -12 39 37 33 31 30

4-t 11 38 33 26 25 21 20

Distance from quenched surface 1,,,6 in. mm 6.5 7 7.5 8 Y 10 12 II 16 18

IO.27 I I.06 I I .8S 12.6-I l-l.22 IS.80 lg.96 22.12 2s 18 28.44

Hardness. HRC mar 28 ‘7 xi 26 2-l 21 23 22 21 20

240 / Heat Treater’s

Guide

1527 Chemical

Composition. AISI and UNS: 0.32 to 0.29 C. 1.20 to I SO hln. 0.040 P max. 0.050 S max. UNS Cl5270 and AISI/SAE 1527: Standard composrtion range for manpanese IS I.20 to I.55 hln: uas formerly designated as I OXX grade Similar

Steels (U.S. and/or Foreign).

A510.A513(1027);SAE5403.J-!12:(Ger.)DIN

UNS ~15270: I.1161

Kr-hl

Characteristics.

Considered a borderline grade because tt can be case hardened bq carburizing orcarbonittiding. Popular for this purpose because of relatively high core hardness. This pemtits use of thinner cases. u hich consene thermal energy and decrease processing cost. IS27 also used in the hardened and tempered condition IShere moderate strength is needed. As-quenched hardness of-13 HRC or slightly higher can be expected. Even though the carbon content IS onJ> 0.29 mas. itelding must be done with care. because the higher manganese may raise the carbon equivalent to a dangerous degree. unless preheating and postheating practices are used. Forgeability is excellent. Grade IS37 ma> be obtained in various product forms

Forging.

Heat to IX5

C (2275 “Ft. Do not forge beIon about 900 “C

(16S0°F,

Annealing. Heat to 900 “C ( I650 “F). Furnace cool to 675 ‘C ( I235 “F) at a rate not to escsed 28 “C (SO ‘F) per h Hardening. Can be case hardened b! any one of several processes. from light case hardening by carbonitriding and salt bath nitriding described for grade 1008 to deeper case carburizinp in pas. solid. or liquid media. (See carburizinp process described for pads 1020). For lS22H. use carburizing temperature of 900 to 925 “C (I650 to I695 “F). Use oil for cooling medium Direct Hardening. Austenitize at 885 “C t 1625 “F). Quench in oil. Uater or brine. Quenchant will depend on section thickness and required hardness Tempering. by tempering

Recommended

Heat Treating

Practice

Normalize

l

XMGll

l

Rough machine Austenitize (or case harden) Quench Temper Finish machine

l l

Normalizing.

Heat to 925 “C (I695

“F). Cool in air

Processing

l

l

Recommended

As-quenched hardness of 43 HRC or higher can be reduced as required (see tune)

l

Sequence

High Manganese

Carbon

Steels (1500 Series) / 241

1527: Hardness vs Tempering Temperature. Represents average based on a fully quenched

structure

an

High Manganese

Carbon

Steels (1500 Series) / 241

15B28H Chemical

Composition.

025 to0.31C. expected)

Similar

15BZSH. UNS H15281 and SAE B28H: l.OOto 1.50Mn.0.15 to0.3.5Si.~O.OOOS to0.003 Bcnn be

Hardening.

Steels (U.S. and/or Foreign).

Curves. Heat-treating

“C (1650 “F). Austenitize:

870 “C (1600 “F)

I distance, nm 5

II 3 5 !O !5 !O i5 Lo IS i0

Heat Treating Practice

Clubonitriding

is a suitrlbk surface hardening process

WE 51X8; AST~I ~304

15828H: Hardenability iardness wrposes

Recommended

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 900

limits for specification Hardness, HRC hlanimum hlinimum 53 53 53 5’ 51 50 18 15 35 29 26 2s 21 23 20

(continued)

242 / Heat Treater’s Guide

15B28H: Hardenability

Curves (continued).

mens only): 900 “C (1650 “F). Austenitize:

Hardness limits for specification purposes J distance, ‘/la in. 1

2 3 4 5 6 7 8 9 10 11

12 13 14 15

16 18 20 22 24 26 28 30 32

-

Earduess, BRC Maximum Minimum 53 53 52 51 51

50 49 48 46 43 40 31 34 31 30 29 27 25 25 24 23 22 21 20

41 41 46

45 42 32 25 21 20

.. . .. ... . .. . . ... .. ...

. ... ... . . ...

Heat-treating 670 “C (1600 “F)

temperatures

recommended

by SAE. Normalize

(for forged or rolled speci-

242 / Heat Treater’s

Guide

15B30H Chemical

Composition.

0.35C.0.70to

Similar

UNS H15301 and SAE 15B30H: 0.27 to l.ZOMn.0.15 to0.35Si~0.0005to0.003Bcanbeexpected)

Steels (U.S. and/or Foreign).

SAE J 1268; ASTM ~30-4

Recommended Hardening.

Heat Treating

Practice

Carbonitriding is a suitable surface hardening process

High Manganese

15B30H: Hardenability

Curves. Heat-treating

“C (1650 “F). Austenitize:

Hardness purposes J distance, mm 1.5 3 5 7 9 11 13 15 20 25 30 35

iardness wrposes I distance, 46in.

L 1

I 0 1 2 3 4 5 6 8 !O

870 “C (1600 “F)

limits for specification Hardness, ARC Maximum Minimum 55 54 53 52 49 45 38 31 26 23 20

48 47 45 38 25 20

. . ... ...

limits for specification Hardness, ARC hlinimum blaximum 55 53 52 51 50 48 43 38 33 29 21 26 25 24 23 22 20

48 47 46 44 32 22 20 . . . .. .. . ... .. . . .. .. .

temperatures

recommended

Carbon

Steels (1500 Series) / 243

by SAE. Normalize (for forged or rolled specimens

only): 900

244 / Heat Treater’s

15B35H,

Guide

15B35RH

Chemical Composition. CJNS HI5351 and SAE/AISI 158358: 0.31 toO.39C.0.70to 1.20hln.0.15 to0.3SSi,~0.000Sto0.003Bcanhs expected). SAE 15B35RH: 0.33 to 0.38 C. 0.80 to I.10 Mn. 0.15 to 0.25 Si’(O.OOOS to 0.003 B can he expected) Similar

Steels (U.S. and/or

WE Jl268.Jl868: ASThl J 1868; ASThl A9 I-l

A914.

Foreign). lSB35RH.

15B35H. LJNS H IS35 I ; l!NS HlS3Sl; SAE 51268.

Characteristics.

Excellent forgability. Special qualit) grades for cold heading. cold forging. and cold estnwion. Can he welded. Because of c&on content. preheating and posthenting are required and interpass temperature must be controlled. Machinability on14 fair. Wide range of mechanical properties can be attained by quenching and tempering. Similar to 1035. Higher manganese content and horon addition increase hardenahility

Annealing. Heat to 870 “C ( I600 “‘F). Furnace cool to 650 “C ( I200 “F) at a rate not to esceed 18 “C (50 “F) per h Hardening. Austenitize a1855 “‘C I I575 “F). Cllrbonitriding surface hardking process. Depending on section thicknine& usually oil quenched Tempering.

Heat IO IX5

“C (2275 “F). Do not forge bslo\v 870 “C t I600

“F)

Recommended l l

l l

Recommended Normalizing. 15835H:

Heat Treating

l

Heat to 915 “C i I680 ‘FL Cool in air

End-Quench

Distance from quenched surface ‘/lb in. mm

l

Practice

of approximntsl~

-15 HRC can be reduced

hy

tempering

l

Forging.

Hardness

is a suitable this steel is

l

Forge Nomlalize Anneal (if nccessar) Rough machine Austenitize Quench Temper Finish machine

Processing

Sequence

for machining)

Hardenability Distance from quenched surface 1. ‘16 in. mm

Hardness. HRC mas

I 7 ;

I .5X

13

20.5-l

1.74 S.lb

15 l-l

22. 23.70I?

2b

4 s 6 7 8 Y

6.32 7.90 9 43 I I a6 I2.b-l 11.22

I6 I8 xl 22 2-l 16

25.28 28 44 31 60 31.7b 37 92 11.08

3

IO II I2

IS 80 17.38 18.96

28 30 32

u.2-l

‘0

47.40 SO.56

:.:

ii ‘2

15B35H: Hardness vs Tempering Temperature. average based on a fully quenched structure

Represents

an

High Manganese

Carbon

Steels (1500 Series) / 245

15835H: Microstructures. Microstructures of 15835 steel. (a) In the as-received hot-rolled condition, microstructure is blocky pearlite. Hardness is 87 to 88 HRB. (b) In the partially spheroidized condition following annealing in a continuous furnace. Hardness is 81 to 82 HRB. (c) In the nearly fully spheroidized condition following annealing in a bell furnace. Hardness is 77 to 78 HRB

246 / Heat Treater’s

Guide

15835H: Hardenability

Curves. Heat-treating

“C (1600 “F). Austenitize:

845 “C (1550 “F)

Hardness purposes 1 distance, mm

limits for specification Hardness, ARC Minimum hlaximum 58 51 56 5-l 52 41 39 32 27 25 2-l 23 22 20

iardness wrposes I distance, 116io.

51 50 39 -IS 32 2-l II 20

limits for specification Hardness, HRC hGnimum Maximum 58 56 5s 5-l 53 51 37 II

48 18 39 ‘8 2-l 22

30

30

51 so

I

0 1 2 3 -I S 6 8 10 12 !I :6 :8 80

27 26 2s 24 22 ‘0

temperatures

recommended

by SAE. Normalize

(for forged or rolled specimens

only): 870

High Manganese

Carbon

Steels (1500 Series) / 247

1536 Chemical

Composition.

UNS G15360, SAE/AISI:

I.20 to I.50 Mn. 0.040 P max. 0.050 S max: was formerly grade

0.30 to 0.37 C, designated

IOXX

Recommended Hardening.

Heat Treating

Carbonitriding

Practice

is a suitable surface hardening

process

High Manganese Carbon Steels (1500 Series) / 247

15B37H Chemical Composition.

UNS15371 and SAE/AISI

to 0.39 C, 1.00 to 1.50 Mn, 0.15 to 0.35 Si (0.0005 expected)

Similar Steels (U.S. and/or Foreign).

15B37H: 0.30

to 0.003 B can be

UNS H IS37 I ; SAE J I168

Characteristics. Same characteristics. exceot treater hardenabilitv , than 15B35H because of higher manganese content. Maximum hardness about the same. 15B37H is an oil hardening grade because hardenability equals that of some alloy grades. Excellent forgeability. Fair machinability .

Forging.

Hardening. Austenitize at 855 “C ( I575 “F). Carbonitriding surface hardening process. Quench in oil Tempering.

As-quenched reduced by tempering

Recommended l l l

Normalizing.

Heat Treating

35 HRC can be

L

Heat to I245 “C (2275 “F). Do not forge below 870 “C ( 1600 OF’)

Recommended

hardness of approximately

is a suitable

Practice

l l

Heat to 915 “C (1680 “F). Cool in air

l

Annealing.

Heat to 870 “C ( I600 “F). Furnace cool to 650 ‘C ( IXU “F) at a rate not to exceed 28 “C (50 “F) per h

l l

Processing

Sequence

Forge Normalize Anneal (if necessary for machining) Rough machine Austenitize Quench Temper Finish machine

15837H: End-Quench Hardenability Distance from quenched surface ‘/,ain. mm

Eardness, FIRC max min

Distance from quenched surface 916 in. mm

I

I S8

x3

SO

13

2o.s-I

2 3

3.16 4.74 6.32 7.90 9.48 II.06 12.64 11.22

56 ss S-l 53 52 51 so

SO 49 38 13 37 33 26

l-l IS 16 I8 20 22 2-l 26

22 I2 23.70 ‘5.28 ‘8.44 31.60 31.76 37.92 11.08

IO

IS.80

4s

ii

II

17.38 IS.96

40

21

28 30 32

4-t 26 17.10 SO56

3

S 6 7

8 9

I2

Hardness, ERC max min .., 33 .,, 29

20

27

.._

.._

2s 23

1:: 21

15B37H: Hardness vs Tempering Temperature. Represents average

based

on a fully quenched

structure

an

248 / Heat Treater’s

Guide

15637H: Hardenability

Curves. Heat-treating

“C (1600 “F). Austenitize:

845 “C (1550 “F)

temperatures

recommended

Hardness limits for specification wrposes I distance, nm

Hardness, HRC Maximum hlinimum

.5

58 57 56 54 53 51 50 47 38 30 28 26 25 23 .

1 3 5 !O !5 10 I5 10 15 i0

iardness wrposes I distance, /I6 in.

0 1 2 3 4 5 6 8 !O :2 14 :6 :8 ‘0 ‘2

50 50 49 46 39 31 26 23 20

limits for spe cification Hardness, HRC hlav

imum 58 56 55 54 53 52 51 50

50 50 49 48 43 37 33 26

45 . 40

22

33

20

21

29 27 25

. 23 21

hlinimum

by SAE. Normalize (for forged or rolled specimens

only): 870

1

High Manganese

Carbon

Steels (1500 Series) / 249

1541,154lH Chemical

COITIpOSitiOrL 1541. AK1 and UNS: 0.36 to 0.41 C, I .3s to I .65 Mn. 0.040 P max. 0.050 S max. 1541H. UNS 15410 and SAE/AISI 1541H: 0.35 to 0.45 C. I.25 to I .75 Mn. 0. IS to 0.35 Si; IS-l I was fotmerl)

designated as IOXX grade: Composition range and limits for 1JNS G IS-I IO and AISVSAE IS-II: 0.36 to 0.45 C. 1.30 to I.65 Mn

Similar Steels (U.S. and/or Foreign). 1541. UNS Gls110: ASTM AS IO, AS 19. A53.5. AS-l6: SAE J-103. J-II?. J-II-l; tGer.j DIN I.1 Ihl:(Fr.) AFNOR-IOMS:(Jap.) JISSMn 2 H,SMn2,SCMn3: (Swed.) SSll 2120. 1541H. LINS HISJIO: SAE 51268; (Ger.) DIN 1.167; (Fr.) AFNOR 40 M 5; (Jap.) JIS Shin 2 H. SMn 2, SChln 3; (Swed.) SS 1-12 I20 Characteristics. Essentially a 1030 with a higher manganese content. This greatly increases its hardenahility. As-quenched hardness about 52 HRC or slightly greater. L+hen fully hardened. However. IS-11 H is relatively deep hardening. so that oil quenching can he used for considerably heavier sections when compared with IWO. Grade IS-11 H is available in various product forms. Forgeability is good. Machinabilit] is fair. Can be welded. using practice recommended for other high-hardenabilit) steels

Hardening. Heat to 845 jC (ISSS “F). Carbonitriding is a suitable surface hardening process. Except for very heavy sections. oil quench from austenitizing temperature. as u ith alloq steels. Water of brine quenching may cause quench cracking. Full precautions should be taken when parts made from I S-l I H are induction hardened. Overly severe quenching may also result in quench cracking Tempering matel)

Normalizing.

Recommended l

l l

Practice

Heat to 900 “C ( I650 “FL Cool in air

l

Heat Treating

Annealing.

Heat to 830 “C ( IS25 “F). Furnace cool to 650 “C ( I200 ‘IF) at a rate not to exceed 28 “C (SO “F) per h

1541: Continuous

Cooling Transformation

“C(1320”F).Ac,at790”C(1455”F)

Diagram. Composition:

of approxi-

After Normalizing. Normalize large sections by conventional practice. u hich results in a structure of fine pearlite. Temper to about 530 “C (I000 “F). hlechanical properties not equal to those achieved b> quenching and tempering. Resulting strength is far higher than annealed structure. Normalize and temper heavy forgings

l

Recommended

hardness

Tempering

l

Forging. Heat to IZ-IS “C (177S “F). Do not forge below 870 “C (I600 “F). For 1511 H, drop forge from I205 to 850 “C (2200 to I560 “F)

After Hardening. As-quenched 57 HRC can be reduced by tempering

l

l

Processing

Sequence

Forge Normalize Anneal c’if necessary) or temper (optional) Rough machine Austenitizc Quench Temper Finish machine

0.39 C. 1.56 Mn. 0.010

P, 0.024

S, 0.21 Si. Grain

size, 8. AC, at 715

250 / Heat Treater’s

Guide

3

1541 H: End-Quench Hardenability

I I.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5

1.58 2.31 3.16 3.95 4.74 5.58 6.32 7.1 I 7.90 8.69 9.18 10.27

60 59 59 58 57 56 55 53 52 SO 48 46

53 52 50 47 4-l 41 38 35 32 29 27 26

7 7.5 8 9 IO I’ l-4

I6 18 20 22 2-t

II.06 I I .85 12.64 13.22 15.80 I8.% 22.12 25.28 28.U 31.60 34.76 37.92

44 II 39 35 33 32 31 30 30 29 28 26

25 24 23 23 22 21 20

1541: Hardenability of Oil-Quenched Bolts. Curves represent average as-quenched hardnesses of 15 bolts 19 mm (0.75 in.) from one heat. C is center of bolt; 0.5R is mid-radius; S is sur-

1541: Isothermal Transformation Diagram. Composition: 0.43 C, 1.57 Mn, 0.011 P, 0.029 S, 0.23 Si, 0.20 Ni, 0.12 Cr, 0.07 MO. Austenitized at 900 “C (1650 “F)

1541, 1541H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure

High Manganese

1541 H: Hardenability Curves. Heat-treating (1600 “F). Austenitize:

Hardness purposes J distance, mm 1.5 3 5 7 9 II 13 IS 20 25 30

845 “C (1550 “F)

limits for specification Hardness, ARC Minimum Maximum 60 59 57 53 49 4-l 38 35 32 30

53 50 4.3 36 29 25 23 ‘2 20

Hardness limits for specification 3urposes I distance,

VI/la in. I.5 , !.S 1.5 1.5 i.5

is ‘S I

0 2 4 6 8 10 12 !I

Hardness, EIRC hlaximum hlinimum 60 59 59 58 57 56 55 53 52 50 48 46 44 41 39 3s 33 32 31 30 30 29 28 26

53 52 SO 47 4-l 41 38 35 31 29 27 26 25 2-l 23 23 22 21 20

temperatures

recommended

Carbon

Steels (1500 Series) / 251

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

252 / Heat Treater’s

Guide

1541: Microstructures. (a) Nital, 330x. Forged at 1205 “C (2200 “F). Cooled in air blast. Widmanstatten platelets of ferrite at prior austenite grain boundaries and within grains. Martensite matrix. (b) Nital, 550x. Forged at 1205 “C (2200 “F), but cooled in milder air blast. Slower cooling rate resulted in upper bainite formation (dark areas). Martensite matrix. (c) Nital, 2850x. Forging and cooling same as (b). Replica electron micrograph. Etched areas are upper bainite, consisting of carbide particles in ferrite. Smooth, featureless areas are martensite. (d) 2% nital, 110x. Hot rolled steel bar. 23.82 mm (0.94 in.) in diam. Transverse section. Top surface shows 0.254 mm (0.010 in.) deep seam and partial decarburization (white areas). Ferrite core (white) outlining prior austenite grains in pearlite matrix (dark). (e) 1% nital, 100x. Forging lap of steel austenitized at 870 “C (1600 “F) for 2 h. Water quenched. Tempered at 650 “C (1200 “F) for 2 h. Iron oxide (dark); ferrite (light); tempered martensite. Core is ferrite and tempered martensite. (f) 1% nital, 100x. Elongated forging flap in steel that was austenitized. Water quenched. Tempered to hardness, 25 to 30 HRC. Iron oxide (dark). White area surrounding flap is caused by decarburization. Hemainder is tempered martensite

252 / Heat Treater’s

Guide

15B41H Chemical Composition. UNS H15411 and SAE/AISI: 0.35 IO 0.45 C. I.75 to I .75 hln. 0. I.5 to 0.35 Si (0.0005 to 0.003 B can be expected) Similar

Steels (U.S. and/or

Foreign).

LINS

HI s-11 I;

SAE

J 1268: (Ger.) DIN I .5X7

Characteristics. A boron treated IS-II H. Significant increase in hardenability caused b) boron addition. Forgeability is good. hlachinabilit) is fair. Weldability IS poor Forging.

Heat to IX5

Recommended Normalizing.

“C (2775 “FL Do not forge below 870 “C I 1600 “F)

Heat Treating

Practice

Heat to 900 “C ( I650 “F). Cool in air

Annealing. Heat to 830 “c ( IS15 “F). Furnace cool to 650 “C t I ZOO “FJ at a rate not to exceed 28 “C (SO “F) per h

Hardening.

Heat to 8-15 “C t IS_55 “F).Carbonitriding is a suitahle surface hardening process. Should he regarded as an alloy steel in quenching from austenitiring temperature. Usually quenched in oil. except for very hea\! sections. L\‘ater or brine quenching likely to result in quench cracking. Full precautions should be taken when parts are induction hardened. Overly severe quenching can also cause quench cracking

Tempering

After Hardening.

Hardness

of nppmximntely

52 HRC

can be reduced b! tempenng

Tempering After Normalizing. For large sections, normalize by cowentional practice. Results in structure of tine pearlite. Temper up to about S-10 “C (I000 “F). hlechanical properties not equal to those achieved h) quenching and tempering Resulting strength far higher than that of annealed structure. Normalize and temper heavy forgings

High Manganese

Recommended l l l l l l l l

Processing

For&e Normalize Anneal (if necessxy) Rough machine Austenitize Quench Temper Finish machine

I

1 3 .I 5 6 7 8 9 IO II 1 I2

I.33 3.16 4.74 6.3’ 7.90 9.18 II 06 12.6-i

11.22 IS.80 17.38 18.96

15841 H: Hardness average

or temper (optional)

15B41H: End-Quench Distance from auenched

Sequence

Hardenability Distance from auenched

Hardness.

60 59 59 58 5x 57 s7 56 55 55 s-l 53

53 51 s2 51 51 50 49 -18 44 37 32 28

I3 II 15

I6 I8 20 22

24 26 28 30 32

Hardness,

20 5-l ‘2.12 23.70 25.28

52 91 50 49

26 25 25 2-l

xu 31.60 31.76 37.92 41.08 44.2-l 17.40 50 Sh

16 12 39 36 3-l 33 31 31

3 22 II 21 20

based

Carbon

vs Tempering

on a fully quenched

Steels (1500 Series) / 253

Temperature. structure

Represents

an

254 / Heat Treater’s

Guide

15841 H: Hardenability

Curves. Heat-treating

“C (1600 “F). Austenitize:

845 “C (1550 “F)

Hardness purposes J distance, mm 1.5 3

5 I 9

11 13 15 20 25 30 35

40 45 50

Hardness purposes I distance, ‘/,fj in.

limits for specification Eardoess, ARC Maximum Minimum 60 60 59 58 58 51 56 55 53

50 45 39 35 32 31

limits for specification Eardness, q RC Maximum hlinimum

1

60

2 3

59 59 58 58 51 51 56 55 55 54 53 52 51 50 49

4 5 6

I 8 9

10 11 12 13 14 15 16 18 20 22 24 26 28 30 32

53 52 52 51 50 49 47 41 26 24 23 21 20

46 42 39 36 34 33 31 31

53 52 52 51 51 50 49 48 44 37 32 28 26 25 25 24 23 22 21 21 20 ...

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870

High Manganese

15B41H: Continuous Cooling Transformation Diagram. Composition: ASTM 7 to 8. AC, at 725 “C (1335 “F). AC, at 780 “C (1435 “F)

Carbon

Steels (1500 Series) / 255

0.42 C, 1.61 Mn, 0.006 P, 0.019 S. 0.29 Si, 0.004 B. Grain size.

High Manganese Carbon Steels (1500 Series) / 255

1548 Chemical

COInpOSitiOn. AISI and UNS: 0.35 to 0.56 C. 0.85 to I. I5 Mn, 0.040 P max. 0.050 S max. UNS Cl5480 and AISl/SAE 15-W Standard composition ranges and limits: 0.42 to 0.43 C. I .OS to I .-IO Mn; was formerly designated as IOXX grade

Similar Steels (U.S. and/or Foreign). A510; SAEJ403.

Wl2,

IJNS

GlS180;

ASTM

J-II-I: (Ger.) DIN I.1226

Characteristics.

High-manganese version of 1045. Slight difference in composition provides for higher hardenability. As-quenched hardness of at least 55 HRC or slightly higher. when carbon is near the high side of the allowable range. Used extensively for parts to be furnace heated or heated by induction prior to quenching. Excellent forgeability. Fair machinability

Forging.

Heat to I245 “C (2275 “R. Do not forge below 870 “C ( 1600 “F)

Recommended Heat Treating Practice Normalizing. Heat to 900 “C (1650 “F). Cool in air

Tempering After Hardening. erly austemtized

Hardness of at least 55 HRC. if propHardness can be adjusted by tempering

Tempering After Normalizing. For large sections. normalize by conventional practice. This results in a structure of fine pearlite. A tempering treatment up to approximately 540 “C (I000 “F) is then applied. Mechanical properties not equal to those achieved by quenching and tempering. Resulting strength is far higher than that of annealed structure. Normalizing and tempering often applied to heavy forgings Recommended l l

l

Annealing. Heat to 84 “C (I555 “F). Furnace cool to 650 “C ( 1200 “F) at a rate not to exceed 28 “C (SO “F) per h

l

Hardening.

l

Austenitize at 815 “C (1555 “Fj. Carbonitriding is a suitable surface hardening process. Because of high hardenability, a less severe quench may be desired for a given section thickness

and quenched.

l

l l

Processing

Sequence

Forge or machine (from bars) Normalize (if forged. Not required for parts machined from hot rolled or cold drawn bars) Anneal (if necessary. Bar stock usually received in condition for best machining) Rough machine (forgings) Austenitize (parts from bars or forgings) Quench Temper Finish machine

256 / Heat Treater’s

Guide

1548: Hardness vs Tempering Temperature. average based on a fully quenched

structure

Represents

an

256 / Heat Treater’s

Guide

15B48H Chemical

Composition.

to0.53 expected)

C. 1.00 to I.50 hln. 0.15 to 0.35 Si (0.0005 to 0.003 B can be

0.13

UNS HI5481

and SAE/AISI

ISBJSH:

Tempering

After Hardening.

As-quenched

hardness

of 55 HRC

can be reduced hy tempering

Characteristics. Composition similar to 15-18 with boron added. Characteristics, other than hardenahility. are the same. Forgeability is excellent. Machinability is fair

Tempering After Normalizing. For large sections. nomlalize hy conventional practice. This results in a structure of fine pearlite. A tempering treatment up to approximately S-IO YY (1000 “F) is then applied. hlrchanical properties not equal to those achieved by quenching and tsmperin~. Resulting strength is far higher than that of annealed structure. Normnhrmg and tempering often applied to heavy forgings

Forging.

Recommended

Similar

Steels (U.S. and/or

Foreign).

1JNS H Is181 : WE

J 1268

Heat to ILIS “C (2275 OF-,. Do not forge below 870 “C ( 1600 ‘F)

Recommended Normalizing.

Heat Treating

l

Practice

l

Heat to 900 C. i I650 “F). Cool in air l

Annealing.

Heat to 815 “C ( IS55 “FL Furnace cool to 650 “C t I200 “F) at a rate not IO exceed 28 “C (SO “F) per h

l l

Hardening.

Austenitize at MS “C I ISSS “F). Carbonitriding surface hardening process. Quench in oil except for thicker induction hardened, use extreme care when \\ater quenching

is a suitable sections. If

from

I 1 3 4 5 6 7 8 9 IO II I2

from quenched

Distance Eardness, HRC mar min

I.98

63

56

1.7-l 3.16 6.32 1.90 948 II.06 I2.64 1122 IS.80 17.38 18.96

62 61 60 59 58 57 56 s.5 53 51

56 55 s-l 43 52 -12 3-l 31 30 29 28

Aardness,

surface &in.

I3 I-l IS I6 I8 30 22 2-l 26 28 30 31

ARC mm

20.51 22. I2 23.70 25.23 28.U 3 I ho 34.76 37.92 41.08 u.21 47 -IO 50.56

l l

15848H: End-Quench Hardenability Distance

l

max

min

48 -Is II 3x 31 32 31 30 19 29 28 ‘8

27 37 26 26 IS 2-l 73 22 21 20

Processing

Sequence

Forge or machine t from bars) Normalize tif forged. Not required for parts machined from hot rolled or cold dran n bars) Anneal tif necessary. Bar stock is usually received in condition for best machining) Rough machine (forgings) .Austenitize Quench Temper Finish machine

High Manganese

15848H: Hardenability

Curves. Heat-treating

“C (1600 “F). Austenitize:

Hardness purposes J distance, mm

1.5 3 5 7 9 11 13 15 20 25 30 35 40 45 50

Hardness purposes J distance, ‘/,,jin.

1 2 3 1 5 5 7 3 2 IO I1 12 13 14 I5 I6 18 !O !2 !4 !6 !8 10 12

845 “C (1550 “F)

limits for specification Eardness, Maximum

ERC hlinimum

63 63 62 61 60 59 57 56 49 39 33 31 30 29 28

56 55 55 54 53 45 33 30 27 25 24 23 22 . ...

limits for specification Eardoess, Maximum

63 62 62 61 60 59 58 57 56 55 53 51 48 45 41 38 34 32 31 30 29 29 28 28

HRC hlinimum

56 56 55 54 53 52 42 34 31 30 29 28 27 27 26 26 25 24 23 22 21 20

temperatures

recommended

by SAE. Normalize

Carbon

Steels (1500 Series) / 257

(for forged or rolled specimens

only): 870

258 / Heat Treater’s

Guide

15848H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched

structure

258 / Heat Treater’s

Chemical

Guide

Composition.

AISI and UNS: 0.45 to 0.56 C. 0.85 to

I .I5 Mn. 0.040 P max. 0.050 S max

Similar

Steels (U.S. and/or

Foreign).

UNS Gl5510;

ASTM

ASIO; SAEJ403. J413, J414

Characteristics. Carbon content as high as 0.56. Borderline grade hetween medium carbon and high carbon. Available in various product forms. Used extensively for producing small to medium size forgings. Often selected for parts to be induction hardened. Excellent forgeability. Fairly good machinability. Weldability is poor. Similar to 1050. Higher manganese content increases hardenability Forging.

Heat to 1230 “C (2250 “F). Do not forge below 845 “C ( IS55

Hardening. Heat to 830 “C ( I525 “F). Carbonitriding and induction hardening are suitable surface hardening processes. Quench in water or hrine. For full hardening, oil quench rounds less than 6.4 mm (‘/J in.) thick. High hardenability must be considered in quenching. Normalize and temper as for I54 I. if desired Tempering.

Recommended l l

“F)

l

Recommended Normalizing. Annealing.

Heat Treating

Practice

l l

Heat to 900 “C ( 1650 “Ft. Cool in air

Heat to 830 “C (I 525 “F). Furnace cool to 650 “C t I200 “F) at a rate not to exceed 28 “C (SO “F) per h

As-quenched

hardness of 58 to 60 HRC can be reduced by

tempering

l l l

Processing

Sequence

Foge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine

1551: Hardness vs Tempering average

based

on a fully quenched

Temperature. structure

Represents

an

High Manganese

Chemical

Composition. AISI and UNS: 0.47 to 0.55 C. 1.20 to I .50 Mn. 0.040 P max. 0.050 S max. UNS Cl5520 and AISI/SAE 1552:

Composition limits formerly designated

Similar

and ranges: 0.46 to 0.55 C. 1.20 to I.55 Mn: uas as I OXX grade

Steels (U.S. and/or Foreign).

A510: SAEJ403.

J412.5414;

UNS

G 15520;

ASTM

(Ger.) DIN I.1226

Characteristics. Carbon content as high as 0.55. Borderline grade between medium carbon and high carbon. Available in various product forms. Used extensively for producing small to medium size forgings. Often selected for parts to be induction hardened. Excellent forgeability. Fairly good machinability. Weldability is poor. Similar to 1050. Higher manganese content increases hardenability Heat to I230 “C (2250 “F). Do not forge below 815 “C ( I555

“F3

Heat to 830 “C ( IS25 “FL Furnace cool to 650 “C ( I200 “F) at a rate not to exceed 28 “C (SO “F) per h

Hardening. Heat to 830 “C ( 1525 “F). Carbonitriding and induction hardening are suitable surface hardening processes. Because of higher hardenability. oil quench heavier sections for full hardness. When induction hardening, use the least severe quench that \rill produce full hardness. This minimizes the possibility of quench cracking Tempering.

Recommended l

l

l

Heat Treating

Practice

l l

Normalizing.

Heat to 900 “C ( 1650 “F). Cool in air

As-quenched

hardness of 58 to 60 HRC can be reduced by

tempering

l

Recommended

Steels (1500 Series) / 259

Annealing.

l

Forging.

Carbon

l

Processing

Sequence

Forge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine

1552: Hardness average

based

vs Tempering on a fully quenched

Temperature. structure

Represents

an

High Manganese

Carbon

Steels (1500 Series) / 259

1561 Chemical

COI?IpOSitiOn. AK1 and UNS: I .OS Mn. 0.040 P max. 0.050 S ma-x

Similar

Steels (U.S. and/or Foreign).

0.55 to 0.65 C. 0.75 to LINS

G 15610;

ASTM

Tempering.

A510: SAE J403. J112

Characteristics. Versatile high-carbon grade. Available in a variety of product forms. including various thicknesses of flat stock used for fahricating parts to be spring tempered. Good forgeahility. Not recommended for welding. As-quenched hardness of near 65 HRC can be expected. When properly quenched. consists of a carbon-rich martensite structure with essentially no free carbide. Similar to 1060. with slightly higher hardenability and manganese content Forging.

Hardening. Heat to 815 ‘C. t IS00 “F). Carbonitriding surface hardening process. Hardenability must be considered Oil quench sections thicker than for 1060

Heat to 1205 “C (2200 “F). Do not forge below 815 “C ( IS00

“F)

Austempering.

Thin sections ttypically springs) usually austempered. Results in hainitic structure. Hardness of approximately 46 to 52 HRC. Austenitire at 8 IS “C t I500 “F). Quench in molten salt bath at 3 IS “C (600 “F). Hold at temperature for I h. Air cool. No tempering required

Recommended l

l

Normalizing. Annealing.

Heat Treating

Practice

Heat to 885 “C ( I625 “F). Cool in air

Heat to 830 ‘C t I535 “FL Furnace cool to 650 “C t I200 “F) at a rate not to exceed 28 “C (50 “F) per h

hardness near 65 HRC can be reduced by tem-

pering

l

Recommended

Maximum

is a suitable in quenching.

l l l l l

Forge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine

Processing

Sequence

260 / Heat Treater’s

Guide

1561: Hardness vs Tempering Temperature. average based on a fully quenched

structure

Represents

an

260 / Heat Treater’s

Guide

15B62H Chemical COfIIpOSitiOfI. CJNS HlS621 and SAE/AISI lSB62H: 0.5-f to 0.67 C. I .OO IO I SO hln. O.-IO to 0.60 Si (0.0005 to 0.003 B can be expected) Similar

Steels (U.S. and/or

Foreign).

IINS H 1562 I : SAE J I 368

Austempering. Thin sections (typically springs) commonly austempsred. resulting in bainitic structure and hardness of approximately 45 to 52 HRC. Austenitizr at 8 IS ‘C t I SO0 “Ft. Quench in molten salt bath at 3 IS “C (600 “Ft. Hold at this temperature for I h. Air cool. No tempering required

Characteristics.Similx

to 1060. Good forgeability. Poor uvldability. Maximum as-quenched hardness of 65 HRC. Higher manpanese content. boron addition, and higher silicon content all contribute to its relatively high hardenability. Extensively used in the spring temper hardness range. generally 35 IO 52 HRC. for springs having relatively thick sections

Forging.

Heat to 1205 “C t7200 “FL Do not forge below 8 IS “C I I SO0 “F)

Tempering.

As-quenched hardness from 63 IO 65 HRC. This maximum hardness can be reduced by tempering

Recommended l

Recommended Normalizing.

Heat Treating

Practice

l l

Heat to 885 “C (1625 “FL Cool in au

l

Annealing.

Heat IO 830 “C t IS25 “FL Furnace cool to 650 “C t I200 “FJ at a rate not to exceed 28 “C (SO “FJ per h

Hardening. Austenitizc at 8 IS ‘C t 1SO0 ‘:‘F). Carbonitriding surface hardening process. Quench in oil 15662H: End-Quench Hardenability Distance from quenched surface

&in.

mm

Hardness. ERC max min

I -3 3 -l 5 6 7 8 9 I0 II I?

1.5x 3.16 47-i 6.32 7 90 9 18 Il.06 116-I l-t.22 IS.80 17.38 IX.96

60 60 60 60 59 58 57 52 43 39 37 s5

I

& 65 6-t 6-l 6-1 63 63 63

Distance from quenched surface I,/16in. mm 13 I-l IS I6 I8 20 22 2-I 26 28 SO 32

30.54 22.12 23.70 3.28 3 4-l 3 1.60 34.76 37 92 11.08 44.2-I 47.40 SO.56

is a suitable

l l l l

Forge Nomlalizs .Anneal Rough machine Austenitize Quench Temper Finish machine

Processing

Sequence

High Manganese

15B62H: Hardenabilitv

Curves. Heat-treating

“C (1600 “F). Austenitiie:

Hardness purposes J distance, mm 1.5 3 5 7 9

11 13

15 20 25 30 35 40 45 50

temperatures

recommended

by SAE. Normalize

Carbon

Steels (1500 Series) /

(for forged or rolled specimens

only): 87C

845 “C (1550 “F)

limits for spec ification Hardness, Maximum

ARC Minimum

60 60 60

.. 65 65 65 65 64 64 63 60 56 48 42 37 34

59 58 56 50 42 34 32 31 30 29 27 26

I

Hardness purposes J distance, ‘&j in.

limits for specification Hardness, Maximum

1 2 3 4 5 6 7 8 9

10 11 12 13 14 15 16 18 20 22 24 26 28 30 32

. 65 65 64 64 64 63 63 63 62 62 61 60 58 54 48 43 40 31 35 34

H RC Minimum 60 60 60 60 59 58 57 52 43 39 31 35 35 34 33 33 32 31 30 30 29 28 21 26

262 // Heat Heat Treater’s Treater’s 262

Guide Guide

15662H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched

structure

262 / Heat Treater’s

Guide

1566 Chemical

Composition.

AISI and UN% 0.60 to 0.71 C. 0.85 to

I. I5 Mn, 0.040 P max. 0.050 S max

Similar

Steels (U.S. and/or

Foreign).

UNS

G15660;

ASThl

AS IO; SAE 5403. J4 12; (Ger.) DIN I. I260

Characteristics. High-manganese version of 1070. Widely used in the hardened and tempered (notably spring tempered) condition. ?iood forgeability and shallow hardening. Extensively used for making hand tools such as hammers and woodcutting saws. Not recommended for welding Forging.

Heat to I 190 “C (2 175 “F). Do not forge below 8 IS “C ( I500 “F)

Recommended Normalizing.

Heat Treating

Practice

Heat to 885 “C ( I625 “F). Cool in air

Austempering. Thin sections (typically springs) are commonly austempered. resulting in bainitic structure and a hardness range of approximitely 46 to 53~HRC. Austenitize 91 815 “C (I500 “F’). Guench in molten salt bath at 3 IS “C (600 “F). Hold a1 temperature for I h. Air cool. No tempering required Tempering.

Recommended l l l

Annealing.

Heat to 830 “C ( IS25 “F). Furnace cool to 650 “C ( I200 “F) at a rate not to exceed 28 “C (50 “F) per h

Hardening. Heat to 815 “C (IS00 “F). Carbonitriding is a suitable surface hardening process. Lessen severity of quench to avoid cracking compared with quenching of 1070

Maximum

hardness near 65 HRC can be reduced by tem-

pering

l l l l l

Processing

Sequence

Forge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine

1566: Isothermal Transformation Diagram. Contains 0.64 C and 1 .13 Mn. Grain size 7. Austenitized at 910 “C (1670 “F). Martensite temperatures estimated

High Manganese

Carbon

Steels (1500 Series) / 263

1566: End-Quench Hardenability. Contains 0.68 C and 1 .OOMn. Grain size, 6 to 7. Austenitized at 845 “C (1555 “F)

1566: Hardness vs Tempering Temperature. average based on a fully quenched structure

Represents

an

(1300

Alloy

Steels

through

9700

The alloy steels discussed in this section. as \vell as their subsequent heat treatment. are those listed in the latest issue of the 41SI Steel Products hlanual on alloy steel bars. They include both ths standard alloy steels and the standard H and RH steels. H hich have modified hardenability limits. They also have sliphtly different carbon ranges. generally broader than the standard alloy steels. These steels are similar to standard grades in other respects. including thek general characteristics and recommended heat treating practice. There are fourteen separate families of alloy steels that rve considered standard. In numericnl sequence. these steels begin with the I300 manpanese steels and conclude with 9160 manganese-silicon steels. Boron-modified allo! steels generalI) contain 0.0005 to O.O03r(~ boron. There are five families of boron-modified allo) steels bepmnlng with

Series)

SOB00 chromium steels and concluding u ith the WBOO nickel-chromiummolybdenum steels. Because of the very small amounts of boron used, boron is not considered as an alloy. These steels. which are denoted by the USP of the letter “B” bet\\een the second and third digits of their designations. are instead commonI> referred to as boron-treated steels. Boron is used for the purpose of increasmg hardenability. When the endquench data for an! specific boron steel are compared with its counterpart not containing boron. the effect of boron hecomes evident. The use of boron steels has provided an economic advantage because It offers high bardenability in IOU-allo! steels. significantly louer in cost than the higher allo) grades that would be necessary to provide the hardenability required u ithout the boron.

1330,133OH Chemical Composition.

1330. AISI and ZJNS: 0.18 to 0.23 C. I .60 to I .90 hln. 0.035 P milx. 0.040 S max. 0. IS IO 0.30 Si. UNS H13300 and SAE/AlSI 1330H: 0.27 IO 0.33 C. I .-iS to 2.05 hln. 0. IS to 0.35 Si.

Similar Steels (U.S. and/or Foreign).

l!NS G 13300: 1330. ASTM A304. A322. 44331. 4519: hllL SPEC hlR--S-16974; SAE J4o-I. J-ii?. 5770; (Ger.) DIN I.1 165: tJap.j JIS Shln I H. SChln 2. 1330H. LINS Hl3300: ASThI A3O-k SAE JlZ68: tGer.) DIN I.1 165: tJap.) JIS Shin I H, SChln 2

Characteristics. A medium-carbon iteel of the manganese allo! steel series. While the manganese content of I330H can overlap \\ nh the manganese content of the high-manganese carbon steels. the nominal manganese content IS considerably higher for 1330H. givmg the steel higher hardenability. Thus. with a carbon content in thr middle of the range. as-quenched hardness can be expected to approach SO HCR. This steel is usually oil quenched. although large sections may have IO be irater quenched to develop maximum hardness. H’ater quenching of l330H is hazardous because high-manganese steels are susceptible to quench cracbing. This applies especialI) to induction or name hardenmg. M’hen these processes are used. the quenching phase of the process must be extremeI> \rell controlled. l33OH can be welded only when close,l>, controlled preheating and postheattng practices are follo\ good. but machinabilit) is only fair

Recommended Heat Treating Practice Normalizing. Heat to 900 jC t l6SO “F). Cool in air Annealing. For a predominately pearlitic structure. heat

to 855 “C (I 570 “F). and cool IO 620 ‘C t I IS0 “F) at a rate not to esceed I I “C (30 “F) per h: or cool fairly rapidlq IO 620 “C ( I I SO “F) and hold for 4 t/z h after which cooling rate is not critical. To obtain a structure predominately composed of femte and spheroidired carbide. heat IO 750 “C (I 380 OF). cool fairly rapidly to 730 “C t I350 “Fj. Then cool to 6-lO “C ( I I85 “F) at a rate not to exceed 6 C t IO “F) per h and hold for IO h. after which cooling rate is no longer critical

Hardening. Austenitize at 860 “C t IS80 “F). and quench in oil. Use water or brine for hea\> secttons. Carbomtriding. austempering. and niartsnipcring are suitable processes. Tempering.

Recommended Processing see 1335 and 1335H) l l l l l l

Forging.

Heal to I230 ‘C i224S “F). Do not forge after temperature belo\v approsimately 870 “C ( I600 “F)

drops

Temper to desired hardness

l l

Rough machine Slress relic\ e Finish machine Preheat Auslrnilize Quench Temper Final grind to size

Sequence

(if forged,

266 / Heat Treater’s Guide

1330H: End-Quench Hardenablllty Distance from quenched surface 916 in. mm

Ehrdoess, ERC max min

Distance from quenched surtkce ‘/la in. mm

Eardlless, ERC max min

I 2 3

1.58 3.16 4.74

56 56 55

49 47 44

13 I4 I5

20.54 22.12 23.10

38 31 36

4 5 6 7 8 9 IO II 12

6.32 1.90 9.48 Il.06 12.64 14.22 15.80 17.38 18.96

53 52 50 48 45 43 42 40 39

40 35 31 28 26 25 23 22 21

I6 18 20 22 24 26 28 30 32

25.28 38.44 31.60 3-1.76 37.92 41.08 44.24 47.40 50.56

35 3-l 33 32 31 31 31 30 30

Source: Metals Handbook.

20 ___

9th ed.. Vol I. American Socier) for Metals. 1978

1330: Effect of Hot Working and Location of Test Bars on End-Quench Hardenability. diam. (c) 203 mm (8 in.) diam. (d) 152 mm (6 in.) diam.

(a) 305 mm (12 in.) diam. (b) 254 mm (10 in.)

Alloy Steels (1300 through

1330H: Hardenability

Curves. Heat-treating temperatures

(1650 OF). Austenitize:

870 “C (1600 “F)

Hardness Purposes J distance, mm 1.5 3 5 7 9 II 13 15 20 25 30 35 40 45 SO

Hardness Purposes J distance, ‘46in. I 2 3 1 5 5 1

3 2 IO II 12 13 I4 IS 16 I8 !O !2

!4 !6 !8 IO i2

Limits for Specification Eardness, ERC Minimum Maximum 56 56 55 53 51 48 45 43 39 35 33 32 31 31 30

49 41 44 38 32 28 25 24 20

.

Limits for Specification Eardoess, EIRC Minimum Maximum 56 56 55 53 52 50 48 45 43 42 40 39 38 37 36 35 34 33 32 31 31 31 30 30

49 47 4-l 40 35 31 28 26 2s 23 22 21 20

recommended

9700 Series) / 267

by SAE. Normalize (for forged or rolled specimens

only): 900 “C

266 / Heat Treater’s

Guide

1330: Continuous Cooling Transformation (1580 “F). Previous treatment, rolled

Diagram.

Composition:

0.30 C. 1.80 Mn, 0.020 P, 0.020 S. 0.15 Si. Austenitized

at 860 “C

268 / Heat Treater’s

Guide

1335,1335H Chemical Composition. 1335. MS1 and UN.9 0.33 LO 0.38 c. I .60 to I .YO hln. 0.035 P max. 0.040 S max. 0.15 LD0.30 Si. UNS H13350 and SAE/AISI 13358: 0.32 IO 0.38 C. I .-IS m 2.05 hln. 0. IS to 0.35 SI

SAE J-107; (Ckr.1 DIN I. 1167; tFr.) AFNOR Shln 2. SChln 3: ~S\rsd.) S.514 2120:

Characteristics.

Similar

Steels (U.S. and/or

Foreign).

1335. ClNS GI 3350: ASTh,l ,432. A3.31. A5lY. A547: hllL SPEC hlK-S-16974: S.L\E J-10-l. J-II?. 5770: (Ger.) DIN I.1 167; tFr.) .L\FNOR 40 hl S: ~Jap.) JIS Shln ? H. Shln 2, SCh4n 3; tSutd.) S.SIJ 2120. 13358. UNS Hl.1350; XSThl.-\304:

-IO hl 5: (Jnp.) JIS Shln 2 H.

The general chzuxkrisric~ me warI> the sane ;LS those pilen for I73OH. Expected ns-quenched h:udnrs for l33SH is sliphtlb hiphsr than that for 133OH. appro\inwl4> 52 HRC. Hwdenubilitl pnltttm, ;ue i1lw knilur. Thib stesl is uzuull> oil quenched. although larg? wctionb nxq hn\s ICYbs \\~er qwnchsd 10 develop marimuni hxdnsss.

Alloy

Steels (1300 through

9700 Series) / 269

LVater quenching high-manganese steels is hazardous because of their susceptibility to quench cracking. This applies especially to induction or flame hardening. When these processes are used. the quenching phase of the process must be extremely well controlled. l33SH can be welded. but only when closely controlled preheating and postheating practices are followed. Forgeability is very good, hut machinability is only fair

exceed 6 “C I IO “F) per h and hold for IO h. after which cooling longer critical

Forging.

Tempering.

drops helou

Heat to 1230 “C (3345 “F). Do not forge atier temperature approxtmately 870 “C i I600 “F)

Recommended Normalizing.

Heat Treating

Heat to 900 “C (I650

l

“Ft. Cool in air

l

Annealing.

For a predominately pearlittc structure, heat to 855 “C ( IS70 “F). and cool to 610 “C ( I I SO OF) at a rate not to exceed I I “C i30 “F) per h: or cool fairly rapidly to 620 “C (I I SO “F). and hold for-t vz h. after u hich cooling rate is not critical. To obtain a structure predommately composed of ferrite and spheroidized carbide. heat to 750 “C ( I385 “F). cool fairly rapidly to 730 ‘C ( I350 OF). Then cool to 640 “C ( I I85 “F) at a rate not to

1335: Isothermal Transformation

Diagram. Composition:

1335: End-Quench Hardenability Hardness, ARC max min

-I ; 4

I S8

98

1.74 3.16 6 32

s7 56 5s

51 -19 47 4-l

1, 7 8 9 IO II I2

9.48 7 90 I Ia6 I’64 13.12 15.80 17.38 18.96

92 5-I so 18 46 4-l 12 41

38 34 31 29 ‘7 26 25 21

I

Distance from quenched surface ‘/16 in. mm

I3 II IS I6 I8 ‘cl 22 2-l 26 2x SO 32

20. s-l 22 II ‘3.70 25.28 28.44 3 I .hO 31.76 37 92 4l.08 4-l 2-l 47.30 SO.56

Temper to desired hardness

Eardness, HRC max min

10 39 38 37 3s 34 33 32 31 31 30 30

l l l l l l

‘3 2’ ‘2 21 20

.._

Processing

Sequence

Forge Nomralize Anneal Rough machine Austenittze Quench Temper Finish machine

0.35 C. 1.85 Mn. Austenitized

No. 2

Distance from quenched surface ‘116 in. mm

Hardening. Austenitize at 855 ‘C (IS70 “F). and quench in oil. Use water or hrine for heal y sections. Carhonitriding and mattempering are suitable surface hardening processes

Recommended

Practice

rate is no

at 845 “C (1555 “F). Grain size: 70% No. 7,30%

270 / Heat Treater’s Guide

1335H: Hardenability (1600 “F). Austenitize:

Curves. Heat-treating 845 “C (1550 “F)

Hardness Limits for Specification Purposes I disiance, nm 1.5 3 5 7 9 11 13 15 !O !5 IO 15 lo 15 i0

Eklrdness, ERC MaximlUU 58 58 51 55 53 50 47 45 41 37 35 33 32 31 30

MillilIlUUl 51 49 46 42 36 31 28 21 23 21 . .

Hardness Limits for Specification Purposes I distance, h6 in. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32

Eardness, Maximum 58 57 56 55 54 52 50 48 46 44 42 41 40 39 38 37 35 34 33 32 31 31 30 30

ERC Millhull 51 49 41 44 38 34 31 29 27 26 25 24 23 22 22 21 20 ... ... ... . .. ..

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

Alloy Steels (1300 through

1335, 1335H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure

9700 Series) / 271

1335: IlT Curve. Composition: Fe, 0.35 C, 1.85 Mn. Grain size: 70% No. 7,30% No. 2. Austenitized at 843 “C (1550 “F)

Alloy Steels (1300 through 9700 Series) / 271

1340,134OH Chemical Composition. 1340. AI.9 and UNS: 0.38 to 0.43 C. I .60 to 1.90 Mn, 0.035 P max. 0.040 S max, 0. I5 to 0.30 Si. UNS 813400 and SAE/AISI 134OH: 0.37 to 0.44 C, I.45 to 2.05 Mn, 0. I5 to 0.35 Si

Hardening. Austenitize at 830 “C (IS25 “F). and quench in oil. Use water or brine for heavy sections. Electron beam, carbonitriding. and austempeting are suitable processes

Similar Steels (U.S. and/or Foreign). 1340.

Tempering.

ASTM A322, A331. A519, A547: J412.5770. 13408. UNS Hl3400: I SO69

UNS G13400; MfL SPEC MLS-16974; SAE J404. ASTM A304; SAE J407; (Ger.) DIN

Recommended l

Characteristics.

Comparable to those outlined for I330H and I335H. As carbon content is increased, a higher as-quenched hardness can be expected (about 54 HRC for I340H. depending on precise carbon content). The hardenability pattern is also quite similar to those shown for grades l330H and 1335H. As is true for all of the I300 grades, hardenahility band is relatively wide, caused primarily by the broad range in manganese content

Temper immediately

l l l l l l l

after quenching

Processing

to desired hardness

Sequence

Forge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine

Forging.

Heat to 1230 “C (2245 “F). Do not forge after temperature drops below 870 “C ( 1600 “F)

Recommended Normalizing. Annealing.

Heat Treating

Practice

1340: Specimens

As-Quenched quenched

Hardness

in oil from 830 “C (1525 “F)

Heat to 870 “C (1600 “F). Cool in air

For a predominately pearlitic structure, heat to 830 “C ( I525 “F). and cool from 730 “C (1350 “F) to 610 “C (I 130 “F) at a rate not to exceed I I “C (20 “F) per h; or cool rapidly from 730 “C (I350 “F) to 620 “C (I IS0 “F). and hold for 4.5 h. For a predominately ferritic and spheroid&d structure, heat to 750 “C (1380 “F), and cool from 730 “C ( 1350 “F) to 610 “C ( I I30 “F) at a rate not to exceed 6 “C ( IO “F) per h; or cool fairly rapidly from 750 “C (1380 “F) to 640 “C ( I I85 “F). and hold for 8h

In.

Size rouad mm

Surface

Eardness, ERC ‘/z radius

Center

‘/2

13 15 51 IO:!

58 57 39 32

51 56 34 30

57 50 32 26

I 7 4

Source: Bethlehem Steel

272 / Heat Treater’s

Guide

1340: Isothermal Transformation

Diagram. Composition:

0.43 C. 1.58 Mn. Austenitized

at 885 “C (1625 “F). Grain size: 8 to 9

1340H: End-Quench Hardenability Distance from quenched surface 1/16in. mm

Distance From Hardness, HRC max min

quenched

surface 916 in. mm

Hardness, ARC max min

I

1.58

2

3.16

60 60

53 52

13 II

20.5-l 22.12

46 44

26 3

3 -I 5 6 7 9

1.7-l 6.32 7.90 9.1x I I.06 12.64 11.23

59 58 57 56 55 5-l 51

51 49 46 10 35 33 31

I5 I6 18 ‘0 22 24 26

23 70 15.28 ‘8.U 3 I .60 34.76 37 92 41 08

-II -II 39 38 37 36 35

29 2-l 23 23 22 22 21

IO II I?

I S.80 17.38 18.96

51 50 -I8

29 18 27

33 30 32

Al.24 47.40 50.56

35 34 3-l

21 20 20

8

hwx

Mrrc~ls Mudbook. %h ed.. Vol I, imericm

Socirr)

ior hlrmls.

1978

1340: IlT Diagram. Composition: size: 8-9. Austenitlzed

Fe, 0.43 C, 1.58 Mn. Grain at 885 “C (1625 “F)

Alloy S teels (1300 through

1340H: Hardenability Curves. Heat-treating (1800 “F). Austenitize:

iardness ‘urposes distance, trn 1.5 3

5 7 9

1 3

5 0 5

0 5

0 5

0

845 “C (1555 “F)

Limits for Specification Hardness, HRC Maximum Minimum 60 60 59 58 57 56 54 52 41 41 39 37 36 35 34

53 52 50 48 42 36 32 30 26 24 23 22 21 20 20

hardness Limits for Specification ‘urposes distance,

1 2 3 4 5 6

7 8 9

0 1 2 3 4 5 6

8 0 2 4 6 8

0 2

Hardness, HRC Maximum Minimum 60 60 59 58 51 56 55 54 52 51 50 48 46

44 42 41 39 38 37 36 36 35 34 34

53 52 51 49 46 40 35 33 31 29 28 27 26 25 25 24 23 23 22 22 21 21 20 20

temperatures

recommended

9700 Series) / 273

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

274 / Heat Treater’s Guide

1340: Hardness vs Tempering Temperature. Normalized at 870 “C (1800 “F). Quenched from 845 “C (1555 “F) in oil and tempered at 58 “C (100 “F) intervals in 13.718 mm (0.540 in.) rounds. Tested in 12.827 mm (0.505 in.) rounds. (Source: Republic Steel)

274 / Heat Treater’s Guide

1345,1345H Chemical Composition. 1345. AISI and UNS: 0.43 to 0.48 C, 1.60 to 1.90 Mn, 0.035 P max. 0.040 S max. 0. I5 to 0.30 Si. UNS H13J50 and SAE/AlSI 13458: 0.42 to 0.49 C. I .45 to 2.05 Mn, 0. I5 to 0.35 Si Similar Steels (U.S. and/or

UNS G 13450; Foreign). 1345. ASTM A322, A331. A519; SAE J404. J412, 5770; (Ger.) DIN 1.0912; (U.K.) B.S. 2 S 516. 2 S 517. 13458. UNS Hl3450; ASTM A304; SAE J407; (Ger.) DIN 1.0912: (U.K.) B.S. 2 S 516.2 S 517

Characteristics. The general characteristics of 1345H closely parallel those given for other medium-carbon 1300 series steels (see details for 133OH). There are exceptions. As-quenched hardness is higher. Fully hardened l345H should provide a minimum hardness of approximately 56 HRC, slightly higher if the carbon content is at the high end of the allowable range. Weldability is further decreased. Susceptibility to quench cracking is intensified as the carbon content is increased. The hardenability pattern for 1345H is very similar to that of 1340H. but adjusted upward because of the higher carbon content of I345H Forging.

Heat to 1230 “C (2245 “F). Do not forge after temperature drops below 870 “C ( I600 “F)

Recommended Normalizing.

Heat Treating

Practice

Heat to 870 “C (1600 “F). Cool in air

Annealing.

For a predominately pearlitic structure, heat to 830 “C (I525 “F). and cool from 730 “C ( I350 “F) to 6 IO “C ( I I30 “F) at a rate not to exceed I I “C (20 “F) per h: or cool rapidly from 730 “C (I 350 “F) to 620 “C (I I50 “F). and hold for 1.5 h. For a predominately ferritic and spheroidized structure, heat to 750 “C (1380 “F), and cool from 730 “C (1350”F)to610”C(1130”F)ataratenottoexceed6”C(10”F)perh:or cool fairly rapidly from 750 “C ( I380 “F) to 640 “C ( I I85 “F). and hold for 8h

Hardening. Austenitize at 830 “C (I525 “F). and quench in oil. Use water or brine for heavy sections. Flame hardening and carbonitriding are suitable processes Tempering.

Temper immediately

Recommended l

Forge NormaJize

l

Anned

l

Rough machine Austenitize Quench Temper Finish machine

l

l l l l

after quenching

Processing

to desired hardness

Sequence

Alloy Steels (1300 through 9700 Series) / 275

1345: Continuous Cooling Transformation Diagram. Composition: 0.46 C, 1.60 Mn, 0.020 P, 0.015 S, 0.25 Si. Austenitized (1560°F)

1345H:End-Quench Hardenability Distance from quenched surface

/16h. I 2 3 4 5 6 7 8 9 IO II I2

mm I .58 3.16 4.74 6.32 7.90 9.48 II.06 12.64 14.22 IS.80 17.38 I8.%

Eardness. ElRC max mlu 63 63 62 61 61 60 60 59 58 57 56 55

56 56 55 54 51 4-t 38 35 33 32 31 30

Distance from quenched surface

‘&jh.

mm

13 14 1s 16 18 20 22 24 26 28 30 32

20.54 22.12 23.70 25.28 28.4-l 31.60 34.76 37.92 41.08 44.24 47.40 50.56

Eardness, ERC min max 54 53 52 51 49 47 45 4-l 47 46 45 45

29 29 28 28 ‘7 27 26 26 25 25 24 24

at 850 “C

1

276 / Heat Treater’s

1345H: Hardenability (1600 “F). Austenitize:

Guide

Curves. Heat-treating 845 “C (1555 “F)

iardness Limits for Specification Durposes I distance,

urn 1.5

) 1 3 5 !O !5 LO 15 Kl I5 i0

iardness ‘urposes distance,

‘16io.

0

1 2 3 4 5 6 8 0 2 4 6 8 0 2

Hardness, HRC Maximum Minimum 63 63 63 62 61 60 59 58 55 51 48 47 46 45 45

56 56 54 52 46 38 35 31 29 27 26 25 24 24 24

Limits for Specification Hardness. HRC Maximum hlinimum 63 63 62 61 61 60 60 59 58 57 56 55 54 53 52 51 49 48 41 46 45 45 45 45

56 56 55 54 51 44 38 35 33 32 31 30 29 29 28 28 21 21 26 26 25 25 24 24

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

1

Alloy Steels (1300 through 9700 Series) / 277

1345, 1345l-l: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure

Alloy Steels (1300 through

9700 Series) / 277

3310RH Chemical

COIIIpOSitiOn.

133ORH. AISI and UNS: 0.08 to 0.13 C,

Characteristics.

Applications include carburized bearing and gears

0.40 to 0.60 Mn, 0.15 to 0.35 Si, 3.25 to 3.75 Ni, 1.40 to 1.75 Cr

Recommended Similar

Steels (U.S. and/or

Foreign).

SAE 3310RH. Has been added to SAE 51868 and ASTM A914. There is no existing standard H-grade

3310RH: Hardenability Curves. Heat-treating “C (1700 “F). Austenitize: 845 “C (1555 “F)

temperatures

Heat Treating

Practice

Hardening. Suitable processes include gas carburizing, liquid nitriding, gas nitriding, carbonitriding, and flame hardening

recommended

by SAE. Normalize

(for forged or rolled specimens

only): 925

(continued)

278 / Heat Treater’s

Guide

3310RH: Hardenability Curves (continued)Heat-treating only): 925 “C (1700 “F). Austenitize: 845 “C (1555 “F) iardness Qrposes I distance, om 1.5 3 5 I

9 II I3 :5 !O !S LO 15 lo 15

i0

Limits for Specification Hardness, HRC Maximum Minimum 42 42 42 41 41 40 40 39 38 37 36 35 35 34 34

37 37 37 36 3.5 34 33 32 30 29 28 27 27 26 26

temperatures recommended by SAE. Normalize (for forged or rolled specimens

278 / Heat Treater’s Guide

4023 Chemical 0.9OMn.O.15

COIIIpOSitiOn. to0.30Si.0.035

AISI and UNS: 0.20 to 0.25 C. 0.70 Pmax.0.040S max.0.20 too.30 MO

Similar Steels (U.S. and/or Foreign).

UNS

G40230;

to

ASTM

l

Characteristics.

One of the two straight molybdenum steels, used almost exclusively for making parts that will be case hardened by carburizing or carbon&riding. When fully quenched, surface hardness is in the range of 40 to 45 HRC. While its hardenability is higher than that of a plain carbon steel of like carbon conte.nt, 4023 is not considered a high-hardenability grade This steel does not have an H counterpart. Grade 4023 is readily forgeable and weldable. Before welding, the carbon equivalent should be checked to determine the need for preheating and postbeating

Forging. Heat to 1245 “C (2275 “F) maximum. Do not forge after the temperature of the forging stock drops below approximately 900 “C ( 1650 “F)

Heat Treating

Normalizing. Heat to Annealing. Annealing

Case Hardening. procedures

l l l l

Processing

4023: Approximate Specimens Reheat temperature OF T

925 “C ( I695 “F). Cool in air

See recommended carburizing. described for 4 I I8H

carbonitriding,

and

Sequence

Forge Normalize Anneal (optional) Rough and semitinish machine Austenitize Case harden Temper Finish machine (carburized parts only)

Practice

is not usually required for this grade. Structures that are well suited to machining are generally obtained by normalizing or by isothermal annealing after rolling or forging. Isothermal annealing may be accomplished by heating to 700 “C ( I290 “F) and holding for 8 h tempering

l l

A322. A33 I. A5 19, A534; SAE 5404. J4 12.5770

Recommended

Recommended l

1125 1125 1575 1700(a) (a) Pseudocarburized

775 775 855 925

Core Hardness of Heat Treated Eardoess, EB O.Wiu. l-in. (25.4mm)

285 293 321 331

223 229 218 155

for 8 hand quenched. Source. Republic

(13.7-mm) rounds

rOU0d.S

Steel

Alloy Steels (1300 through

9700 Series) / 279

4023: Hardness vs Tempering Temperature. average based on a fully quenched

4023:

Approximate

Critical

Points Temperature

lhmsformatioo point

AC, AC, w &I Source: Republic Steel

OC 1350 1540 I-l40 1250

750 840 780 670

structure

Represents

an

Alloy Steels (1300 through 9700 Series) / 279

4024 Chemical Composition.

Similar Steels (U.S. and/or Foreign).

UNS

G40240;

ASTM

A322. A33 I, A5 19; SAE J404. J4 12, J770

Characteristics. One of the two straight molybdenum steels. used almost exclusively for making parts that will be case hardened by carburizing or carbonitriding. When fully quenched, surface hardness is in the range of 40 to 45 HRC. While its hardenability is higher than that of a plain carbon steel of like carbon content. 4024 is not considered a high-hardenability grade. This steel does not have an H counterpart. Grade 4024 is readily forgeable and weldable. Before welding, the carbon equivalent should be checked to determine the need for preheating and postheating. With the exception of a slightly higher allowable sulfur content. grades 4023 and 4024 are identical. This difference in sulfur content provides a slight improvement in machinability, but is not sufficient to significantly impair forgeability or weldability Forging. temperature “F)

Recommended

AI!31 aod UNS: 0.20 to 0.25 C. 0.70 10

0.90 Mn, 0.15 to 0.30 Si. 0.035 Pmax, 0.035 to 0.050 S. 0.20 fo 0.30 MO

Heat to 1245 “C (2275 “F) maximum. Do not forge after of the forging stock drops below approximately 900 “C (I 650

4024: End-Quench Hardenability. Composition: 0.24 C, 0.88 Mn, 0.33 Si. 0.23 MO. Quenched from 925 “C (1695 “F)

Heat Treating

Normalizing. Heat to Annealing. Annealing

Practice

925 “C (1695 “F). Cool in air

is not usually required for this grade. Structures that are well suited to machining are generally obtained by normalizing or by isothermal annealing after rolling or forging. Isothermal annealing may be accomplished by heating to 700 “C ( I290 “F) and holding for 8 h

Case Hardening. tempering process

procedures

Recommended l l l l l l

See recommended carburizing, carbonitriding, and described for4 I l8H. Martempering is also a suitable

Processing

Sequence

Forge Normalize Rough and semifinish machine Case harden Temper Finish machine (carburized parts only)

4024: Hardness vs Tempering Temperature. average based on a fully quenched structure

Represents

an

280 / Heat Treater’s

Guide

4024: Cooling Transformation

Diagram. Composition: 0.24 C, 0.88 Mn, 0.33 Si, 0.23 MO. Austenitized AC,, 825 “C (1520 “F); AC,, 750 “C (1380 “F). A: austenite, F: ferrite, P: pearlite, B: bainite, M: martensite

at 925 “C (1695 “F). Grain size: 8.

280 / Heat Treater’s

4027,4027H,

Guide

4027RH

Chemical Composition. 4027. AK1 and UN.% 0.25 to 0.30 c. 0.70 to 0.90 Mn. 0.15 to 0.30 Si. 0.035 P ma\. 0.040 S max. 0.20 to 0.30 hlo. Uh'S A10270 and SAE/AISI1027H:0.24 to0.30C.0.60to 1.00Mn.0.15 to0.35Si.0.~0to0.30Mo.SAEJ027RH:0.2Sto0.30C,0.70to0.90~ln. 0.15 to 0.35 Si. 0.20 to 0.30 MO Similar ASTM ASTM

Steels (U.S. and/or Foreign). 4027. G40~70; LINS A322. A33 I. AS 19; SAE J-IO-L J-II?. J770.4027H. UNS H-10270; A304 A9 I-l; SAE J 126X. J I868

Characteristics. Often considered horderline between a carhuriring grade and a direct-hardening grade. Commonly used for either cnse-hardening or direct-hardening applications. The hardenability of 4037H is somewhat higher than a carbon steel of equivalent carbon content. although not as high as a I300 grade having the same c&on content. As-quenched hardness (no carburizingj is generally -IS to 48 HRC. Has excellent forgeability, but only fair machinability. Can be welded using alloy steel practice. Preheating and postheating are required because of the relati\el> high carbon equivalent

Forging. forging

Heat to IUS “C (2275 “FL Do not forge after temperature stock drops below approsimatelj 870 “C (1600 OF)

Recommended Normalizing.

Heat Treating

of

Practice

Heat to 900 “C t I650 “FL Cool in air

Annealing. For a predominately psarlitic structure, heat to 855 “C (1570 “F). and cool rapid11 to 750 “C ( I380 “FL then to 610 “C ( I I85 “F) at a rate not to exceed I I “C (20 I-‘F) per h: or heat to 870 “C ( 1600 “F). cool rapidly to 660 “C i I210 “FL and hold for 5 h. For a predominately spheroidized structure, heat to 775 “C ( 1125 “FL cool from 745 “C ( I370 JF) to 640 “C ( I I85 “F) at a rate not to exceed 6 “C ( IO “F) per h: or heat to 775 “C (I 425 “F). cool rapid11 to 660 ;C. ( I?20 “F) and hold for 8 h Direct Hardening. As-quenched

Tempering.

Heat to 855 “C ( IS70 “F). hardness. 12 to 48 HRC. Gas carburizing Reheat to obtain desired hardness

Case Hardening. tempering

and quench in oil. is a suitable process

procedures

See recommended cmhutizing. described for 4 I I8H

carhonitriding.

and

Alloy

Recommended l l l l l l l l

Processing

4027:

Sequence

4027: Isothermal

Transformation

quenched

0.565 l.ccMl 2.ooo -i.ooo

at 925 “C (1695 “F) and fin-

Diagram.

Composition:

9700

Series) / 281

in water

Size round in.

Sourx

4027: Gas Carburizing. Carburized ished at 845 “C (1555 “F)

(1300 through

As-Quenched Hardness

Specimens

Forge Normalize Anneal Rough machine Austenitize or case harden Quench Temper Finish machine

Steels

Bshlrhrm

mm

I-i.35 I ‘5 400 SO.YOO 101.600

Surface

50 HRC 50 HRC 47 HRC X3 HRB

Badness, HRC ‘12 radius

Center

SOHRC 47 HRC 27 HRC 77 HRB

50 HRC 44HRC 27 HRC 7SHRB

Steel

4027: Hardness vs Tempering Temperature. Tempered at indicated temperatures showing effect of time at temperature

0.26 C. 0.87 Mn, 0.26 MO. Austenitized

at 855 “C (1570 “F). Grain size: 7

282 / Heat Treater’s

Guide

4027H, 4028H: Hardenability 900 “C (1650 “F). Austenitize:

hardness Purposes I distance. um 1.5 3 5 7 3 I1 13 I5 20 25 30 35

iardness ‘urposes di!aallce, ‘16 in.

0 1

2 3 4 5 6 8 D 2

Curves. Heat-treating 870 “C (1600 “F)

Limits for Specification Eardness, ERC MXlXiUllUll MillhllUU 52 51 45 40 32 29 26 25 23 22 21

45 41 32 23 20

. .. ..

Limits for Specification Eardness, ERC Maximum Minimum 52 50 46 40 34 30 28 26 25 25 24 23 23 22 22 21 21 20

45 40 31 25 22 20

...

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens only):

Alloy Steels (1300 through

9700 Series) / 283

4027H: End-Quench Hardenability Distance fkom quenched surfsee ‘/,a in. mm

E=-d=s ERC min max

Distance from quenched surface ‘/la in. mm

Badness, ERC max

I

1.58

52

45

I3

20.54

23

2 3 4

3.16 4.74 6.32

50 46 40

40 31 25

I4 I5 16

22.12 23.70 25.28

22 22 21

5

7.90

34

22

I8

28.44

21

6 7 8

9.48 II.06 12.64

30 28 26

20

20 22 24

31.60 34.76 37.92

20 .., . .

9 IO II I2

14.22 15.80 17.38 18.%

25 25 24 23

26 28 30 32

41.08 44.24 47.40 50.56

.__

4027: Gas Carburizing.

Results of 50 tests that represent variation in cation concentration for continuous carburizing. Results were obtained over a 3 to 4 year period of operation using an automatic dew point controller

4927: Cooling Curve. Half cooling timeSource:

Datasheet

l-91, Climax Molybdenum

Company

284 / Heat Treater’s

Guide

4027RH: Hardenabilitv Austenitize:

Hardness Purposes J distance, 916 in.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 1.5 16 18 20 22 24 26 28 30 32

Hardness Purposes J distance. mm

1.5 3 5 I 9 11 13 15 20 25 30 35 40 45 50

Curves. Heat-treating

870 “C (16bO “F)

Limits for Specification Eardness, hleximum

HRC hlinimum

51 48 43 31 32 28 26 24 23 22 22 21 21 20 .

46 42 34 28 24 22 20 ... .

... ... ... ... ...

... ... ... ... ...

.

.

“.. . Limits for Specification Hardness, ARC Maximum hlinimum

51 48 42 35 29 26 24 23 21

.

46

42 33 26 23 20

.

recommedned

by SAE. Normalized

(for forged or rolled specimens

only: 900 “C (1650 “F).

1

Alloy Steels (1300 through

alloy steel. Chemical composition: 0.28 C, 0.25 Si, 0.86 Mn, 0.020 P, 0.028 S, 0.062 Cr, 0.026 Ni,,0.23 heat; bar stock austenitized at 870 “C (1600 “F) 20 min

4027: CCT Diagram. Constructional MO, 0 .11 Cu. Acommercial

9700 Series) / 285

Alloy Steels (1300 through

9700 Series) / 285

4028,4028H Chemical

Composition. 4028. AISI and UNS: 0.3 to 0.30 C. 0.70 too.90 hZn.0.15 to0.30Si.0.035 Pmax.0.035 toO.OSOS.0.20 too.30 Mo. UNS H10280 and SAE/AISI 4028H: 0.24 to 0.30 C. 0.60 to I .OO Mn. 0.035 to 0.050 S. 0.15 to 0.35 Si. 0.X to 0.30 hlo Similar ASTM ASTM

1JNS G-tO280: Steels (U.S. and/or Foreign). 4028. A333. A33 I. AS 19: SAE J-IO-I. 1113. J770.1028H. LINS H-10280: A304 SAE J-t07

Direct Hardening. quenched hardness, suitable process

Tempering.

Heat tn I245 “C (2275 “F). Do not forge after temperature forging stock drops belo\\ approxtmately 870 ‘C ( 1600 “F)

Recommended

Heat Treating

of

Practice

Heat to 900 “C (l6SO “F). Cool in air

tempering

l l

Annealing.

For a predominately pearlitic structure. heat to 855 “C t IS70 “F). cool rapidI) to 750 “C (I 380 “F). then to 870 “C ( 1600 “F) at a rate not to exceed I I “C (20 “F) per h: or heat to 870 “C ( 1600 “F). cool rapidly to 660 “C (I 220 “F), and hold for 5 h. For a predominateI> spheroidized structure. heat to 775 “C ( I-415 “FL cool from 7-U “C (I 370 “F) to 640 “C

procedures

Recommended l

l l l l l

Heat to 85s “C ( IS70 “F) and quench in oil. ASappro\imatelq 12 to 48 HRC. Mat-tempering is a

Reheat to obtain the desired hardness

Case Hardening.

Forging.

Normalizing.

t I I85 ‘F) at a rate not to exceed 6 “C t IO “F) per h: or heat to 775 “C (1425 “F). cool rapidly to 660 “C t I220 “F). and hold for 8 h

See recommended carbutizing. described for -I I I8H

Processing

Forge Normalize Anneal Rough machine Austenitize or case harden Quench Temper Finish machine

Sequence

carbonitriding.

and

288 / Heat Treater’s

1 2 3 4 5 6 7 8 9 10 II 12

1.58 3.16 4.74 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38 l8.%

Guide

52 SO 46 40 34 30 28 26 2s 2s 24 23

45 40 31 25 22 20 __.

_._ .

13 14 IS I6 I8 20 22 24 26 28 30 32

20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 41.40 50.56

23 22 22 21 21 20 . .

4028: Liquid Carburizing. 1'l/32 in. outside diameter by 6 3/4in. Oil quenched. Carburized at the temperatures indicated

4028, 4028H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure

288 / Heat Treater’s Guide

4032,4032H Chemical Composition.

4032. AISI: 0.30 to 0.35 c, 0.70 to 0.90

Mn.0.20to0.35Si,0.035Pmax,0.040Smax,0.20to0.30hlo.UNS:0.30 to0.35C. 0.70to0.90Mn.0.035 Pmax.0.040S max.0.15 to0.30Si.0.20 to 0.30 MO. UNS H40320 and SAE/AISI 40328: Nominal. 0.29 to 0.35 C. 0.60 to 1.00 Mn. 0.15 to 0.35 Si. 0.20 to 0.30 Mo

Similar Steels (U.S. and/or Foreign). 4032. ASTM A322; FED QQ-S-00629 (FS4032); UNS H40320: ASTM A304; SAE J I268

UNS G40320; SAE J404,J412. J770.4032H.

tions carbonitriding is excellent

has been applied

to 4032H. Forgeability

of this grade

Forging. forging

Heat to 1235 “C (2275 “F). Do not forge after temperature stock drops below approximately 870 “C (1600 “F)

Recommended Normalizing.

Heat Treating

Practice

Heat to 900 “C (I 650 “F). Cool in air

Annealing.

Characteristics. With a carbon content that slightly overlaps 4027H and with an otherwise identical composition, the general characteristics of 4032H and 4027H are the same. The hardenability pattern for 4032H resembles that of4027H. although the curves for 4032H are moved slightly upward compared with those for 4027H because of a higher nominal carbon content. Fully hardened 4032H wiU provide a surface hardness of approximately 48 HRC or slightly higher. Grade 4032H is less weldable and has a slightly lower machinability than 4027H because of a higher nominal carbon content. Direct hardening rather than case hardening is used for 4032H. although for special applica-

of

For a predominately pearlitic structure. heat to 855 “C (1570 “F). cool rapidly to 750 “C (I 380 “F), then to 640 “C (I I85 “F) at a rate not to exceed I I “C (20 “F) per h; or heat to 870 “C (I 600 OF), cool rapidly to 660 “C (1220 “F), and hold for 5 h. For a predominately spheroidized structure, heat to 775 “C (1425 “F). cool from 745 “C ( 1370 “F) to 640 “C (I I85 “F) at a rate not to exceed 6 “C (IO “F) per h; or heat to 775 “C (1425 “F’), cool rapidly to 660 “C ( I220 “F), and hold for 8 h

Hardening. Heat to 855 “C (I 570 OF). and quench in oil. Carbonitriding is a suitable process Tempering.

Reheat to obtain the desired hardness

Alloy Steels (1300 through 9700 Series) / 287

Recommended Forge l Normalize . t%‘uE.d l Rough machine l Austenitize l Quench l Temper l Finish machine l

Processing

Sequence

4032, 4032H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure

4032: Continuous Cooling Transformation Diagram. Composition: 0.32 C, 0.80 Mn, 0.025 P, 0.020 S, 0.30 Si, 0.28 MO. Austenitized at

1

288 / Heat Treater’s

4032H: Hardenability (1650 “F). Austenitize:

Hardness Purposes I distance,

mm 1.5 3 i

7 2 I1 13 I.5 !O 15 $0 15 ul 15 50

Hardness Purposes I distance, V,6 in.

5 5 > IO

I1 I2 I3 I4 15 I6 18 !O !2 !4 !6 !8 10

Guide

Curves. Heat-treating 870 “C (1600 “F)

Limits for Specification Hardness,

Maximum

HRC

Minimum

51 55 51 44 36 32 29 21 24 23 23 22 21 20

50 46 34 21 24 22 20

. .

Limits for Specification Hardness, HRC Maximum Minimum 57 54 51 46 39 34 31 29 28 26 26 25 24 24 23 23 23 22 22 21 21 20

50 45 36 29 25 23 22 21 20

.

. ..” . . .

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 900 “C

1

Alloy Steels (1300 through 9700 Series) / 289

4032H: End-Quench Distance from quenched surface

916in. I 2 3 -I 5 6

1 8 9 IO II I3

Hardenability Distance from quenched surface

Hardness, ERC

Hardness,

mm

max

min

!$6 in.

mm

HRC mas

1.58 3.16

57 5-l

SO 1s 36 19 15 23 22 21 20

13 I-1 IS I6 I8 20 22

20.51 22.11 23.10 25.28 28.44 31.60

21 2-l 23 23 '3 2

31.16

22

1-l

31.9). 1108 44.21

21 21 20

1.11

51

6.37

46 39 31 31 29 28 26 26 25

1.90 9-18 Il.06 12.64 11.22 IS.80 1138 I8.%

::'

26 28 30

11.40

32

50.56

Alloy Steels (1300 through

9700 Series) / 289

4037,4037H Chemical Composition. 4037. AISI and UNS: 0.35 10 0.40 C. 0.70 to 0.90 Mn. 0.15 to 0.30 Si. 0.035 P max. 0.040 S max. 0.20 to 0.30 hlo. UNS H40370 and SAE/AISI 4037H: 0.34 to O.-l I C. 0.60 to I .OO hln. 0. IS to 0.35 Si. 0.70 to 0.30 hlo

Hardening. Heat to 845 “C ( IS55 “F). and quench in oil. Carbonitriding is a hardening process. In aerospace practice. parts are austenitized at 815 “C t IS55 “F). and quenched in oil or hater

Similar

Tempering.

Steels (U.S. and/or

Foreign).

ASTM A322. A33 I. AS 19, AS-+7: WE H40370: ASTM A30-I: SAE J 1368

UNS G-10370: 4037. J-KM. J-Ill. 5770. 1037H. UNS

Characteristics.

A medium-carbon. IOU-alloy steel that can be hardened to approximately SO HRC or slightly higher, provided it is properl! quenched. and the carbon is on the high side of the allouable range. The hardenabilib pattern is similar to that of other carbon-molybdenum steels (4077H and 103ZH) except that the curves move up\\ard hecause of the higher carbon content. Has excellent forgeability, but neldahility (princepall? m terms of susceptibility to weld cracking) decreases as carbon content mcrcasrs

Rehsat to the temperature hardness. See table

Recommended l l l l l l l

Forging. forging

Heat to I?30 “C ( X-IS “FL Do not forge after temperature stock drops beIon approrimately 85.5 “C ( IS70 OF)

Recommended

Heat Treating

of

Practice

Normalizing.

Heat to 870 “C (1600 ‘FL Cool in air. In aerospace practice, parts &arenormalized at 900 “C ( 1650 “F)

Annealing. For a predominately pearlitic structure, heat to 845 “C ( IS55 “F). cool rapidly to 745 “C ( I370 “FJ. then to 630 ‘C ( I I70 “F) at a mte not to exceed I I “C (20 “F) per h; or heat to 845 “C ( IS55 “F), cool rapidI> to 660 “C ( IX0 “F). and hold for 5 h. For a predominately spheroidired structure. heat to 760 “C ( I100 “F). cool from 7X “C ( 1370 “F) to 630 “C t I I70 “F) at a rate not to esceed 6 “C ( IO “F) per h: or heat to 760 “C ( I400 “F). cool rapidly to 660 “C (I 220 “F). and hold for 8 h. ln aerospace practice. pans are annealed at 815 “C ( IS55 OF). Pans are cooled to below -WI ‘% (750 “F) at a rate not to exceed I IO “C i200 OF) per h

l

Processing

required

to provide

the desired

Sequence

Forge Normalize Annsal Rough machine Austenitize Quench Temper Finish machine

4037: Suggested practice)

Tempering

Temperatures

(Aerospace

Tensile Strength Ranges 86010 1035 to 1175 to 1240 to 1035 MPa 1175 MPa 1240 hlPa 1380 blPa 620 to 860 MPa (90to 125ksi) (125to 15Ok.G) (150to 17Ok.G) (170 to 180 ksi) (180 to200 ksi) 595 ‘Cl II I IIOO”F, 65O”Cfh) (1200°F)

s-lo ‘C (lCMXI’;FI 595 ‘C IIIOO”Fl

(a) Quench m oil or pol!nw

195 ‘C r92S ‘:‘F) 5-u) “C I IOW’F,

440 “C (825 “I=) -170“C (875 “F)

Ib) @ench in ~awr. Source: AMS 275911

370 “C 1700°F) 3x5 “C (725 “FJ

290 / Heat Treater’s

Guide

4037H: End-Quench Hardenability Distance hm quenched

Diktancefrom

ERC

surface

v,l/lain. I

2 3 4 5 6 7 8 9 10 II I2

mm

I .58 3.16 4.74 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38 18.%

max

Earducss,

quenched

Bardn-9

ERC

surface min

‘/la

in.

mm

max

59

52

13

20.54

26

57 54 51 45 38 34 32 30 29 28 27

49 42 35 30 26 23 22 21 20

14 15 I6 18 20 22 24 26 28 30 32

22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 4.2-l 47.40 50.56

26 26 35 25 25 2.5 24 24 24 23 23

4037: Cooling Curve. Source: Datasheet

l-21 6. Climax Molybdenum

Company

Alloy Steels (1300 through

4037: Isothermal Transformation

Diagram. Composition:

0.35 C, 0.80 Mn, 0.25 MO. Austenitized

4037: Hardness vs Tempering Temperature. Normalized at 870 “C (1600 “F). Quenched from 845 “C (1555 “F) and tempered in 56 “C (100 “F) intervals in 13.716 mm (0.540 in.) rounds. Tested in 12.827 mm (0.505 in.)

9700 Series) / 291

at 855 “C (1570 “F). Grain size: 7

4037: Hardness vs Tempering Time and Tempering Temperature. Tempered at temperatures indicated

292 / Heat Treater’s

4037H: Hardenability (1800 “F). Austenitiz&

Hardness Purposes I distance, nm

1.5 3 5 7 9 11 13 15 20 25 30 35 40 45 50

rlardness Purposes I distance, 46in.

1 3 > 10

I1 12 13 14 15 16 18 ,O 12 24 16 23 30 32

Guide

Curves. Heat-treating temperatures 845 “C (1555 “F) -

Limits for Specification Hardness, HRC hlaximum hliuimum

59 57 54 49 41 35 32 30 21 26 25 25 25 24 23

52 50 42 32 27 24 21 20

.

Limits for Specification Eardness, HRC Maximum hlinimum

59 51 54 51 45 38 34 32 30 29 28 21 26 26 26 25 25 25 25 24 24 24 23 23

52 49 42 35 30 26 23 22 21 20

. ..

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

Alloy

Steels (1300 through

9700 Series) / 293

4037: CCT Diagram. Constructional alloy steel composition: 0.41 C, 0.74 Mn, 0.008 P, 0.032 S, 0.28 Si, 0.014 Ni, 0.034 Cr, 0.21 MO, 0.065 Cu. Acommercial heat; barstock steel was austenitized for20 min at 845 “C (1555 “F). Source: Datasheet l-21 6. Climax Molybdenum Company

Alloy

Steels (1300 through

9700 Series) / 293

4042,4042H Chemical

Composition. 1042. AISI: 0.40 to 0.15 C. 0.70 to 0.90 Mn.0.20 too.35 Si.O.040 Pmax.0.040S max.0.20 too.30 hlo. UNS: 0.40 to0.3.S C. 0.70 to 0.90 hln. 0.035 Pmax. 0.010 S max. 0. IS too.30 Si. 0.30 to 0.30 MO. UNS H40420 and SAE/AISI JOJZH: 0.39 to 0.46 C. 0.60 to 1.00 Mn. 0.15 to 0.3s Si. 0.20 to 0.30 hlo Similar ASTM ASTM

Steels (U.S. and/or Foreign). 1042. A322, A33 I, A5 19: SAE J-10-1. J312.J770.1042H. A3O-l; SAE J I368

UNS G-10-110: LINS H-tO-tX

Characteristics. Has characteristics that closeI) parallel those of the other medium-carbon. molybdenum-alloy steels (see -1027H and -1037H). As the carbon content increases. the as-quenched hardrwss mcreases. Depending to some extent upon the precise carhon content. fully hardened -1012H has a surface hardness of approsimatel> 55 HRC. Forgeobilit> of this grade is escellent. but welding is difficult bscause of the difticult) in producing crack-free welds Forging.

Heat to 1230 ‘-‘C (2245 “FL Do not forge after temperature forging stock drops helow approximately 855 “C (IS70 “F)

Recommended

Heat Treating

Practice

of

Annealing.

For a predominately pwlitic structure. heat to 845 “C (1555 “FL cool rapidI\ to 745 “C (I 370 “F). then to 630 “C (I 170 “F) at a rate not to exceed I I ‘C t 20 “F) per h: or hcu to 8-15 “C ( I555 “F), cool rapidly to 660 ‘C. (I220 OF). and hold for S h. For a predominately spheroidized structure. heat to 760 “C I 1400 “F). cool from 735 “C ( I370 “F) to 630 “C (I 170 “F) at a r;ltc not to eucred 6 “C (IO “F) per h; or heat to 760 “C (I400 “F), cool rapidI> to 660 “C ( I220 “F). and hold for 8 h

Hardening. Heat to 845 “C ( I555 OF), and quench in oil. Carbonitriding is a suitable process Tempering.

Recommended l l l l l l l

Normalizing.

Heat to 870 “C I 1600 “F). Cool in air

Reheat to the temperature

required

to provide

h,udrwss

l

Forge Nomlalizc Anneal Rough machine Austrnitirz Quench Tsmpcr Finish machins

Processing

Sequence

the desired

294 / Heat Treater’s

4042: Continuous

Guide

Cooling Transformation

Diagram. Composition:

0.40 C, 0.80 Mn, 0.025 P, 0.020 S, 0.30 Si, 0.26 MO. Austenitized

at

810 “C (1490 “F)

4042: Isothermal Transformation

Diagram. Composition:

0.42 C, 0.20 Mn, 0.21 MO. Austenitized

at 870 “C (1600 OF). Grain size: 5 to 6

Alloy Steels (1300 through

I 2 3 4 5 6 7 8 9 IO II I2

I .58 3.16 4.14 6.32 7.90 9.48 II.06 12.64 14.22 15.80 17.38 l8.%

62 60 58 55 50 45 39 36 34 33 32 31

5.5 52 48 40 33 29 27 26 25 24 24 23

I3 I4 I5 I6 I8 20 22 24 26 28 30 32

20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40 50.56

30 30 29 29 28 28 28 27 27 27 26 26

9700 Series) / 295

23 23 22 22 22 21 20 20

4042: Hardness vs Tempering Temperature. Normalized at 870 “C (1600 “F). Quenched from 845 “C (1555 “F) in oil and tempered in 56 “C (100 “F) intervals in 13.716 mm (0.540 in.) rounds. Tested in 12.827 mm (0.505 in.) rounds. Source: Republic Steel

296 / Heat Treater’s

4042H: Hardenability (1600 “F). Austenitize:

Hardness Purposes I distance, mm

1.5 3 5 7 9 11

13 15 20 25 30 35 40 45 50

Hardness Purposes I distance, V,6 in.

i 3 IO

11 12 13 14 15 I6 18 !O !2 !4 !6 !8 10 $2

Guide

Curves. Heat-treating 845 “C (1555 “F)

Limits for Specification Eardness, Maximum

HRC hlinimum

55 53 47 36 30 27 25 24 23 22 21 20

62 61 58 54 48 40 36 33 31 29 28 28 27 27 26

Limits for Specification Hardness, HRC Maximum hlinimum

62 60 58 55 50 45 39 36 34 33 32 31 30 30 29 29 28 28 28 27 27 27 26 26

55 52 48 40 33 29 27 26 25 24 24 23 23 23 22 22 22 21 20 20 .

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

Alloy

Steels (1300 through

9700 Series) / 297

4047,4047H Chemical Composition. 4047. AISI and UN% O.-IS to 0.50 C. 0.70 to 0.90 Mn, 0.15 to 0.30 Si, 0.035 P max. O.O-iO S max. 0.20 to 0.30 Mo. UNSH40470and SAE/AISI4047H:0.1-1toO.S1 C.O.60to l.OOMn.O.lS to 0.35 Si. 0.20 lo 0.30 MO Similar ASThl ASTM

Steels (U.S. and/or

Foreign).

4047.

A322. A33 I. AS 19: SAE J-W. JA II. J770.4047H. A30-k SAE J I268

UNS G10-170; UNS H-lO-I70:

Characteristics.

W7H. which ma) have a carbon content of up to 0.51. borders on u hat may be considered high-carbon steel and is sometimes used in applications that require spring grades. The hardenability of 11U7H exhibits a pattern veq similar to the lower or medium-carbon grades of the -lOXX series. although both the minimum and masimum tunes are shifted further upward on the hardenability chart because of the higher carbon content of -IO-L7H. As-quenched hardness of fully hardened -W7H should be near S5 HRC or slightI) higher. depending upon the precise carbon content. Readily forged. but not r&omm;nded fir \;*elding. In addition to direct hardening and tempering. 10-17H is well adapted to heat treating bq the nustempering process

Annealing.

For a predominately pearlitic structure, heat to 830 “C (IS25 “F). cool fairlq rapidlv to 730 “C ( 1350 “Fj. then to 630 “C ( I I70 “F) at a rate not to exceed I I ;C (20 “F) per h: or cool fairly rapidly from 830 “C (IS25 “Fj to 660 “C ( I220 “F). and hold for 5 h. For a predominately spheroidized structure, heat to 760 “C ( 1400 “F). cool fairly rapidly to 730 “C t I350 “F), then to 630 “C ( I I70 “F). at a rate not to exceed 6 “C (IO “F) per h; or heat to 760 “C ( 1100 “F). cool Fairly rapidly to 650 “C ( I200 “F). and hold for 9 h

Hardening. Austenitize at 830 “C ( I525 OF). and quench in oil. Austempering and cwbonitridinp are suitable processes Tempering.

forging

Heat to I220 “C (2325 “F). Do not forge after temperature stock drops belo\+ approsimntel) 8-lS YI ( 1555 “F)

of

Heat Treating

Practice

Recommended l

l l

l l

Normalizing.

Heat to 870 “C (1600 “FL Cool in air

4047: Isothermal Transformation

Diagram. Composition:

to provide

the desired

Austenitize at 845 “C (I555 OF), quench in agitated molten salt at 315 “C (655 “F). hold for 2 h and cool in air. Resulting hardness should be 15 to SO HRC. No tempermg is required

l

Recommended

required

Austempering.

l

Forging.

Reheat to the temperature

hardness

l

Processing

Sequence

Forge Normalize Anneal Rouph machine Austenitize (or austemper) Quench (or austemper) Temper (or austemper) Finish machine

0.48 C. 0.94 Mn. 0.25 MO. Austenitized

at 815 “C (1500 “F). Grain size: 6 to 7

298 / Heat Treater’s

4047: Continuous

Guide

Cooling Transformation

Diagram. Composition:

810 “C 11490 “Fb

4047H: End-Quench Hardenability Diitance from quenched surface i6 in. mm

Eardoess, RRC max min

Distance from quenched surface

‘/16h.

mm

Hardness, ERC max min

1 2 3 4 5 6 7 8 9 10 11

1.58 3.16 4.74 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38

64 62 60 58 55 52 47 43 40 38 37

51 55 50 42 35 32 30 28 28 27 26

13 14 15 16 18 20 22 24 26 28 30

20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40

34 33 33 32 31 30 30 30 30 29 29

2.5 25 25 25 24 24 23 23 22 22 21

12

18.96

35

26

32

50.56

29

21

0.48 C, 0.80 Mn, 0.025 P, 0.020 S, 0.25 Si, 0.26 MO. Austenitized

at

Alloy

Steels (1300 through

9700 Series) / 299

4047: Cooling Transformation

Diagram. Composition: 0.51 C, 0.81 Mn. 0.25 Si, 0.26 MO. Austenitized at 845 “C (1555 “F). Grain size: 8. AC,, 790 “C (1455 “F); AC,, 745 “C (1370 “F). A: austenite, G: ferrite. P: pearlite, B: bainite, M: martensite. Source: Bethlehem Steel

4047: Hardness vs Tempering Time and Tempering Tempsrature. Tempering temperatures indicated

300 / Heat Treater’s

Guide

4047: Variations in Depth of Hardening. Tempered 1 h at indicated temperatures. (a) 12.7 mm (l/2 in.) diam cylinders; (b) 25.4 mm (1 in.) diam cylinders: (c) 38.1 mm (1’12 in.) diam cylinders

4047: Microstructures. (a) 2% nital. 110x. Hot rolled steel bar. 28.6 mm (15s in.) diam with a mill defect (a sliver of metal) at the surface, folded over oxide (dark gray). Primarily ferrite, resulting from decarburization, with patches of fine pearlite (dark). (b) 2% nital. 550x. Cold drawn steel bar, 23 mm (29/32 in.), mill annealed; longitudinal section. Somewhat segregated ferrite (white) and fine pearlite (dark) caused difficulty in machining (drilling) (continued)

Alloy

Steels (1300 through

9700 Series) / 301

4047: Microstructures (continued). (c) 2% nital, 550x. Hot rolled steel 26.2 mm (1 l/32 in.) diam: longitudinal section taken at midradius. Acicular ferrite and upper bainite. resulting from rapid cooling from rolling temperature. Large dark areas are pearlite. (d) 2% nital, 550x. Steel forging, 12.7 mm (‘12 in.) thickness, air cooled from forging temperature of 1205 “C (2200 “F); longitudinal section. Plates of ferrite (white) and fine pearlite (dark). (e) 2% nital, 500x. Steel forging. Longitudinal section, 15.9 mm (5/8 in.). Austenitized at 830 “C (1525 “F), cooled to 665 “C (1230 “F) and held 6 h. furnace cooled to 540 “C (1000 “F). air cooled. Ferrite (white) and lamellar pearlite (dark)

4047: Cooling

Curve. Half cooling time. Source: Datasheet

l-21 9. Climax Molybdenum

Company

302 / Heat Treater’s

Guide

4047H: Hardenabilitv Curves. Heat-treatina temperatures recommended by SAE. Normalize (for forged or roiled specimens only): 870 “C (1600 “F). Austenitizk 845 “C (1555 “F) Hardness Purposes 1 distance.

mm 1.5 3 5 7 3 11 13 15 20 25 30 35 40 15 50

Hardness Purposes J distance, ‘$6 in. 1 2 3 1 5 5 7 3 3 10 11 12 13 14 15 16 18 20 !2 14 !6 !8 30 52

Limits for Specification Flardness, mc MilliDlUIU Maximum 64 63 60 57 53 48 43 39 34 33 31 30 30 29 29

57 55 49 39 33 30 28 21 25 24 24 23 23 22 21

Limits for Specification Eardnes, ERC Maximum Minimum 64 62 60 58 55 52 41 43 40 38 31 35 34 33 33 32 31 30 30 30 30 29 29 29

57 55 50 42 35 32 30 28 28 27 26 26 25 25 25 25 24 24 23 23 22 22 21 21

Alloy Steels (1300 through

4047: CCT Diagram. Constructional

9700 Series) / 303

alloy steel. Chemical composition: 0.48 C, 0.23 Si, 0.78 Mn, 0.005 P: 0.020 St 0.06 Cr, 0.012 Ni, 0.25 MO, 0.015 Cu. Bar stock from commercial heat was used in study. Steel was austenitized at 845 “C (1555 “F) 20 min. Source: Datasheet l-219, Climax Molybdenum Company

Alloy Steels (1300 through 9700 Series) / 303

4118,4118H, Chemical Composition.

4118RH 4118. AISI and UNS: 0. I8 to 0.23 C. 0.70

to 0.90 Mn. 0.15 to 0.30 Si. 0.035 P max. 0.040 S max. 0.40 to 0.6OCr. 0.08 to 0. I5 MO. UNS If41180 and SAE/AISI 4118H: 0. I7 to 0.23 C. 0.60 to 1.00 Mn, 0.15 to 0.35 Si. 0.30 to 0.70 Cr. 0.08 to 0.15 MO. SAE 4118RI-I: 0.18 to 0.23 C, 0.70 to 0.90 Mn. 0.15 to 0.35 Si. 0.10 to 0.60 Cr. 0.08 to 0.15 MO

Similar Steels (U.S. and/or Foreign). 4118.

UNS G-l I 180: SAE 5404. J412. J770. 4118H. UNS

ASTM A322, A33l. A505, ASl9; H-II 180: ASTM A304: SAE Jl268.51868;

Characteristics.

ASTM

A913

Low-ahoy steel which is used extensively for case hardening applications. conventional carhurizing as well as carhonitriding. As can be observed in the hardenability data for -II ISH, the hardenability differs little from that of a comparable 1000 series steel. The chromium addition in 41 ISH little more than offsets the decrease in molybdenum content. Depending somewhat upon the precise carbon content of 41 IgH. the as-quenched surface hardness will be approximately 38 HRC or slightly higher. Forgeahility is excellent, but machinability is only fair. 41 I8H can be readily welded. although before any welding is attempted the carbon

equivalent observed

should

Forging.

Heat to I?-!5 “C (2275 “F) maximum. Do not forge after of forging stock drops below approximately 870 “C (1600 “F)

temperature

be determined.

Recommended Normalizing.

and recommended

Heat Treating

Heat to 925 “‘C (I695

welding

practices

Practice

“F). Cool in air

Annealing. Not usually required for this grade. Structures that are well suited to machining are generally obtained by normalizing or by isothermal annealing after rolling or forging. Isothermal annealing may be accomplished hy heating to 700 “C ( 1290 “F) and holding for 8 h Direct Hardening. While applications for 41 l8H seldom require direct hardening. it can be accomplished by austenitizing at 900 “C (1650 “F) and quenching in oil. Ion nitriding, gas nitriding, carbonitriding. and gas or liquid salt bath carburizing are suitable processes Carburizing. II l8H responds readily to any gas or liquid salt bath carburizing processes. The most widely used gas carburizing procedure is described helow:

304 / Heat Treater’s Guide l

l

l l

Heat to 925 “C ( I695 “F) in a gaseous atmosphere with a carbon potential of approximately 0.90%, for the required time. About 4 h at temperature is required to attain a case depth of 1.37 mm (0.050 in.) Decrease temperature to 845 “C ( 1555 “F). decrease carbon potential slightly, and hold for a I h diffusion cycle Quench in oil Temper at I SO to I75 “C (300 to 335 “F). Higher tempering temperatures may be used if some case hardness can be sacrificed

Other carburizing cycles may be used. One cycle consists of slo\r cooling from the carburizing temperature, then reheatmg to 845 “C ( IS55 “F) and oil quenching. However. this cycle is used less FrequentI) because it hastes energy and takes too much ttme. Double treatments Hhich Mere extensively used at one time are all but obsolete. Depth of carburized cases depends upon time and temperature. The rate of carburization can be increased exponentially by increasing the carburizing temperature from 925 “C (I695 “F) to 1040 “C t 1905 “F) or even higher. However, the economics must be considered. As a rule. the rate of deterioration of conventional carburizing furnaces becomes intolerable as temperatures exceed 925 “C (1695 “F). Using a vacuum furnace has proved to be the most practical answer to carburizing at temperatures as high as 1095 “C (2005 “F).

Carbonitriding.

3 I I8H is widely used in applications involt ing small hardware items where only a thin. file hard case is required. In carbonitriding. the parts &are heated in a carburiring atmosphere I$ ith an addition of approximately IO vol % anhydrous ammonia. Carbonitriding temperatures are most often within the range of 790 to 815 “C (I-155 to IS55 “F) A common carbonitriding cycle for lou-carbon alloy steels. such as 3 I I8H, is to carbonitride at 8 IS “C ( IS00 “F) for 45 nun and quench in oil. This results in a tile hard case approximately 0. I27 mm (0.005 in. j in depth. Somewhat deeper cases may be obtained by increasing the temperature. the

4118H: End-Quench

Distance from quenched surface 916 in. mm

I 1 3 -I 5 6 7 8 9 IO II I2

Hardenability

Aardoess, ERC max min

IS8

48

3.16 4.7-I 6.32 7.90 9.48 II.06 12.64 l-l.32 IS.80 17.38 I8.%

46 II 3s 31 28 27 26 2-t 13 22 21

II 36 27 2.3 10

Distance from quenched surface I&j in. mm I3 i-l I5 I6 I8 20 22 2-t 26 ‘8 30 32

Rardness HRC max

time. or both. Houever. this process is designed especially for developing thin cases on small parts which \vill not be subjected to such finishing operations as grinding. Tempering of carbonitrided parts is recommended ( IS0 to 260 “C, or 300 to 500 “F), because it decreases the tendency for brittleness, although the vast majority of carbonitrided parts are placed in service without tempering

Recommended l l l l l l l

Processing

Sequence

Forge Normalize AMC~ (optional) Rough and semilinish machine Case harden or direct harden Temper Finish machine tcarbunzed parts only)

4118: Diametral Dimensions of a Pinion Before and After Carburizing and Hardening. Carburlzed at 885 “C (1625 “F), oil quenched

from 830 “C (1525

“F), tempered

at 185 “C (365 “F).

Depth of case, 1.016 to 1.270 mm (0.040 to 0.050 in.). 60 HRC minimum. (a) Before treatment. (b) Aftertreatment. (c) Differential drive pinion gear

Alloy Steels (1300 through 9700 Series) / 305

4118, 4118H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure

4118H:

As-Quenched

Specimens

were quenched

Hardness in oil

Size round in.

mm

Surface

Aardness ‘12 radius

Center

33 HRC 12 HRC

33 HRC 20 HRC

33 HRC 20 HRC

87 88 HRB

87 88 HRB

85 87 HRB

4118H: Microstructures. (a) 4% nital, 250x. Steel bar, gas carburized for 8 h at 925 “C (1695 “F), quenched in oil, heated to 845 “C (1555 “F) and held for 15 min, quenched in oil, tempered for 1 h at 170 “C (340 “F). Completely decarburized surface layer (white). Structure identified in (b). (b) 4% nital, 500x. Same as (a), but a higher magnification. Shows surface oxidation (dark at top), decarburized surface layer (ferrite), transition zone consisting of ferrite plus low-carbon martensite. and matrix of tempered martensite and retained austenite. (c) 4% nital, 100x. Carburized, hardened, and tempered same as (a), but shows only partial decarburization near surface because specimen previously contained precipitated intergranular carbide particles. Case matrix same as (b). (d) 4% nital, 250x. Steel tubing, gas carburized 5 h at 925 “C (1695 “F) and oil quenched, then hardened and tempered same as (a). Specimen shows the effect of localized overheating (burning) of the carburized surface during grinding. See (e) and (f). (e) 4% nital. 100x. Same as (d), but with less severe grinding burn. As in (d), the light-etching surface layer is untempered martensite and retained austenite (not distinguishable here), and adjacent dark-etching zone is self-tempered martensite. See (f). (f) 4% nital, 500x. Same as (d) and (e), except grinding burn is extremely slight. White surface layer (untempered martensite) is barely perceptible, and the underlying layer of self-tempered martenslte is shallow. As in (d) and (e), matrix is tempered martensite

306 / Heat Treater’s

Guide

4118H: Hardenability

Curves. Heat-treating

(1700 “F). Austenitize:

925 “C (1700 “F)

iardness hrposes I distance, urn

iardness ‘urposes distance, $6 in.

Limits for Specification Eardness, ERC Maximum Minimum

Limits for Specification Eiardnes, ERC Maximum Minimum 48 46 41 35 31 28 21

0 I 2 3 4 5

2s 24 23 22 21 21 20

41 36 27 23 20

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 925 “C

Alloy Steels (1300 through 9700 Series) / 307 4118:

Carburizing, Single Heat Results

Specimens contained 0.21 C, 0.80 Mn, 0.008 P, 0.007 S, 0.27 Si, 0.16 Ni, 0.52 Cr, 0.08 MO; grain size was 6 to 8; critical points included AC,, 750°C (1380°F); Ac3, 825°C (1520°F); Ar,, 775°C (1430°F); Ar,, 680°C (1260 “F); 14.4-mm (0.565-in.) rounds were treated; 12.8-mm (0.505in.) rounds were tested

Recommended For maximum

practice

hsile ksi

streagtb MPa

61 62 62

0.063 o.tN7 0.047

1.600 1.19-l 1.19-l

177.5 I-13.0 126.0

1223.8 985.6 868.7

131.0 93.5 63.5

903.2 644.7 437.8

9.0 17.5 21.0

42.3 41.3 42.4

352 293 241

57 56 56

0.063 0.047 0.047

1.600 1.19-l 1.19-l

177.0 138.0 120.0

1220.4 961.5 827.4

130.0 89.5 63.0

8%.3 617.1 -13-t.4

13.0 17.5 22.0

48.0 41.9 48.9

341 277 229

Eardness, EIB

case hardness

Direct quench from pot(a) Single quench and temper(b) Double quench and temprk) For maximum

mm

Eardness, ERC

Yield strength 0.2 % offset bi hIPa

Core properties Elongation in2in. Reduction @mm), 9% ofarea, 5%

case properties Depth in.

core toughness

Direct quench from pot(d) Single quench and tempede) Double quench and temper(f)

(a) Carburized at 1700 “F(925 “C) for 8 h. quenched in agitated oil, tempered at 300 “F( IS0 “C). (b) Carhurized at I700 “F (925 “C) for 8 h, pot cooled reheated to 1525 “F (830 “0. quenched in agitated oil. tempered at 300 “F (150 “CJ. Good case and core properties. (c) Carburized at I700 “F (925 “C) for 8 h, pot cooled, reheated to IS25 “F (830°C). quenched in agitated oil. tempered at 300 “F ( I SO “C). Maximum refinement of case and core. (d) Carburized at I700 “F (925 “C) for 8 h. quenched in agitated oil, tempered at 450 “F(230”C).(e)Carburizedat 1700”F(925”C)for8h,potcooled,reheatedto lS2SoF(830”C).quenchedinagitatedoil,tempe~dat~S0”F(230”C).Goodcaseandcoreproperties. (f)Carburizedat 17OO”F(925 “0 for 8 h, pot cooled. reheated to I.525 “F(830”C). quenchedin agitatedoil. tempered iit lSO”F(230 “C). Maximum refinement ofcaseandcore. Source: Bethlehem Steel

Alloy Steels (1300 through 9700 Series) / 307

4120H,

4120RH

Chemical Composition. 4120H. AISI and UNS H41200: 0.18 IO 0.23 C. 0.90 to 1.20 Mn. 0.15 to 0.35 Si. O.-IO to 0.60 Cr. 0.13 to 0.20 MO. SAE4120~:0.18to0.23C.0.90to1.20Mn,0.15to0.35Si.0.~0to0.60 Cr. 0. I3 to 0.20 MO

Similar Steels (U.S. and/or Foreign). added to SAE J I268 and J I868 and to ASTM standard H-steel

Characteristics. its, but is carefully

8630

Both steels were recently A9l-I. There is no existing

The RH grade is made to narrower composition controlled to provide restricted hardenability.

steels are equivalent to 8620H and 862ORH in hardenability, but have higher manganese content. no nickel, slightly higher chromium, and slightly less molybdenum. Jn application. these steels are alternatives for

Recommended Hardening. Ion processes

limBoth

Heat Treating nitriding.

gas nitriding,

Practice and carbonitriding

are suitable

308 / Heat Treater’s

Guide

4120RH: Hardenability

Curves. Heat-treating

“C (1700 “F). Austenitiie:

Hardness Purposes .I distance, ‘/,#j in. 1 2 3 4 5 6 I 8 9 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32

Hardness Purposes 1 distance, mm 1.5 3 5 7 ? I1 13 15 10 ?5 30 35 to 15 $0

925 “C (1700 “F)

Limits for Specification Hardness, HRC Madmum Minimum 47 45 41 38 34 31 29 28 26 25 24 23 23 22 22 21 20

42 39 35 30 26 24 22 21 20

.. . .

..

.

. . Limits for Specification

Hardness, HRC Maximum Minimum 41 45 41 36 32 29 28 26 23 21

. .. .

42 39 34 28 25 22 21 20 .

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 925

Alloy Steels (1300 through

9700 Series) / 309

4130,413OH Chemical

Composition.

4130. AISI and UNS: 0.28 to 0.33 C. 0.40

toO.60~ln.0.lSto0.30Si.0.03SPn~a~.0.0~0Smax.0.80to

Recommended

to 0.25 MO. UNS HJ1300 and SAE/AISI J130H: 0.27 to 0.33 C. 0.30 to 0.70 hln. 0.035 P max. 0.010 S max. 0. I5 to 0.30 Si. 0.75 to I.20 Cr. 0. IS

Normalizing.

to 0.3

Annealing.

hlo

Similar Steels (U.S. and/or Foreign). 113O.l~NSG41300;AbIS 6350. 6356. 6360. 636 I. 636’. 6370. 637 I. 6373; ASTM A322. A33 I. A505. ASl3. ASl9, A6-lh: hlfL SPEC MLS-16971: SAE J-IO-I, J-112. 5770; (Ger.) DIN I .7118: (Fr.) AFNOR 25 CD -t(S); (Ital.) UNI 25 Crhlo 1.25 Crhlol KB: (Jap.) JIS SChl 2. SCCM I; (Swed.) SS)-) 3325; (U.K.) B.S. CDS I IO. 41308. UNS H-l 1300; ASThI A.304; SAE J-107: (Ger.) DIN I .72 18; (Fr.) AFNOR 25 CD -t(S); (Ital.) UNI 35 Crhlo -I. 25 Crhlo -I KB; (Jap.) JIS SCM 2. SCCrbl I; (Sned.) SSIJ 3335: (U.K.) B.S. CDS I IO

Heat to 900 “C ( I650 “FL Cool in air

For a predominateI> pearlitic structure. heat to 855 “C ( IS70 “F). cool fairly rapidly to 760 “C (I400 ‘F). then to 665 “C (1730 “F) at a rate not to exceed I8 “C (35 “F) per h; or heat to 85.5 “C ( I575 “F), cool rapidly to 675 “C ( I245 “F). and hold for -I h. For a predominately spheroidized structure. heat to 750 “C i I380 “F), cool from 750 “C (I 380 “F) to 665 “C (1230 “F) at a mte not to exceed 6 “C (IO “F) per h: cool ranidlv . - from 750 ‘C ( 1380 “F) to 675 “C ( I ?-I5 OF). and hold for 8 h

Hardening.

A medium-carbon alloy steel which can he oil quenched to attain a maximum as-quenched hardness of approximately 48 HRC. Its hardenahilitl is significantly higher than that of the carbon-molybdenum (40xX) grades. 3130H is produced in a number of product forms including tubing. -l I3OH has been used extensively for structures such as airframes that are fabricated from tubing. -1130H is ueldahlc. hut because of its fairlj high hardenahility. preheating and postheating must he used

l

Forging.

l

Austenittre

at 870 “C ( 1600 “FL and quench in oil

Reheat to the temperature

Recommended l l l l

Heat to 1230 “C (2245 OF) maximum. Do not forge after temperature of forging stock drops below approximateI) 870 “C (I 600 “F)

4130: Continuous Cooling Transformation

Practice

Tempering.

Characteristics.

tized at 850 “C (1560 “F)

Heat Treating

l.lOCr,O.lS

Diagram. Composition:

l

u hich itill

Processing

result in the required

hardness

Sequence

Forge Normalize Anneal Rough machine Austenitize and quench Temper Finish machine

0.30 C, 0.50 Mn. 0.020 P, 0.020 S, 0.25 Si, 1 .OOCr, 0.20 MO. Austeni-

310 / Heat Treater’s

Guide

4130: Isothermal Transformation

4130H:

Diagram. Composition:

0.33 C, 0.53 Mn, 0.90 Cr, 0.18 MO. Austenitized

End-Quench Hardenability

Dice from quenched surface ‘116 In. mm

Esrdness, ERC max min

Distance from queocbed surface ‘/la in. mm

Eardness, ERC max min

I 2 3

1.58 3.16 4.14

56 55 53

49 46 42

13 14 15

20.53 22.12 2370

34 34 33

24 23 23

4 5

6.32 7.90

51 49

38 34

16 18

25.28 28.44

33 32

23 22

6 7 8

9.48 11.06 12.64

41 44 42

31 29 27

20 22 24

31.60 34.76 31.92

32 32 31

21 20

9 IO

14.23 15.80

40 38

26 26

26 28

41.08 11.24

31 30

II 12

17.38 IS.%

36 35

25 25

30 32

47.40 SO.56

30 29

at 845 “C (1555 “F). Grain size:

Alloy

4130:

As-Quenched

Specimens

Hardness

mm

Surface

Eardnes, ARC l/r radius

Center

‘/z I 2 4

I3 25 51 I02

51 51 4-l 45.5

50 50 32 25

SO 44 31 24.5

round

Source: Bethlehem

9700 Series) / 311

4139: Cooling Curves. Steel tubing. 31.75 mm (1.25 in.) outside diameter by 1.651 mm (0.065 in.) wall

were quenched in water

in.

Si

Steels (1300 through

Steel

4130: Hardness vs Tempering Temperature. Normalized at 900

4130H: End-Quench Hardenability. 48 heats of 14835 contain-

“C (1650 “F). Quenched from 870 “C (1600 “F) in water and tempered at 56 “C (100 OF) intervals in 13.7 mm (0.540 in.) rounds. Source: Republic Steel

ing0.35to0.39C,0.65to1.10Mn,0.13Nimax,0.05Crmax,0.03 MO max and boron treated; compared with 4130H

312 / Heat Treater’s

Guide

Microstructures. (a) 2% nital. 500x. Normalized by austenitizing at 870 “C (1600 “F) and air cooling to room temperature. Ferrite (white areas) and lamellar pearlite (dark areas). Specimen shows slight banding. (b) 20/o nital. 750x. Hot rolled steel bar, 25.4 mm (1 in.) diam, annealed by austenitizing at 845 “C (1555 “F) and cooling slowly in the furnace. Coarse lamellar pearlite (dark areas) in a matrix of ferrite (white). (c) 2% nital, 750x. Hot rolled steel bar 25.4 mm (1 in.) diam. austenitized at 845 “C (1555 “F) for 1 h, cooled to 675 “C (1245 “F) and held for 2 h, and air cooled. Partly spheroidized pearlite (dark) in a matnx of ferrite (white). (d) 29b nital. 750x. Same as (c), except the time at 675 “C (1245 “F) was increased to 4 h. Structure essentially the same as (c), except the degree of spheroidization of the pearlite is greater. (e) 2% nital. 750x. Same as (c) and (d), except the time at 675 “C (1245 “F) was increased to 8 h. Structure is similar to those shown in (c) and (d), except the degree of spheroidization of the pearlite has increased further. (f) 2% nital, 750x. Same as (c), (d), and (e), except that the time at 675 “C (1245 “F) was increased to 16 h. The degree of spheroidization is greater than in (e). (g) 2% nital. 750x. Hot rolled steel bar, 25.4 mm (1 in.) diam, austenitized at 870 “C (1600 “F) for 1 h and water quenched. Untempered martensite. (h) 5% picric acid, 2 !/20/b HNO,, in ethanol; 11 000x. Same as (g), except an electron micrograph of a platinum-carbon-shadowed two-stage carbon replica. Untempered martensite. (j) Not polished, not etched: 8600x. Annealed. Replica electron fractograph. Note fatigue striations, resolved only at high magnification 4130:

Alloy Steels (1300 through

4130H: Hardenability Curves. Heat-treating (1650 “F). Austenitize:

870 “C (1600 “F)

iardness Limits for Specification Durposes distance, om .5

t 1 3 5 !O !5 IO I5 lo I5 i0

Hardness, HRC Maximum Minimum 56 55 53 51 48 44 41 39 34 33 33 32 31 31 30

49 46 40 36 32 28 26 25 24 23 22 20 .

iardness Limits for Specification Burposes 1distance,

46h.

IO 11 12 13 14 I5 16 18 !O !2 !4 !6 !8 10 52

Hardness. HRC hlaximum Minimum 56 55 53 51 49 47 44 42 40 38 36 35 34 34 33 33 32 32 32 31 31 30 30 29

49 46 42 38 34 31 29 27 26 26 25 25 24 24 23 23 22 21 20

temperatures

recommended

9700 Series) / 313

by SAE. Normalize (for forged or roiled specimens

only): 900 “C

314 / Heat Treater’s

Guide

4135,413SH Chemical

Composition.

Similar

In aerospace practice.

4135. AISI: 0.33 to 0.38 C. 0.70 to 0.90

Mn. 0.80 to 1.10 Cr. 0.035 P max. 0.040 S max. 0.15 to 0.25 MO. UNS: 0.33toO.38C.O.70too.90 Mn.0.035 Pmax.0.04OS max.0.15 to0.30Si. 0.80 to l.lOCr, 0.70 to 0.90 Mo.UNS H41350and SAE/AISI 41358: 0.32 to 0.38 C. 0.60 to 1.00 Mn. 0.15 to 0.35 Si, 0.75 to 1.20 Cr. 0. I5 to 0.25MO

Steels (U.S. and/or

Foreign). 4135. UNS ~41350; AMS ASTM A274. A355. A519; MlL SPEC MU-S-16974, MLS-18733; SAE J404.54 12.5770; (Ger.) DIN I .7220; (Fr.) AFNOR 35 CD 4.35 CD 4 TS; (Ital.) UNI 35 CrMo 4.35 CrMo 4 F, 34 CrMo 4 KB; (Jap.) JIS SCM I. SCCrM 3; (Swed.) SSla 2234; (U.K.) B.S. 708 A 37. 41358. UNSH41350; ASTM A304: SAE Jl268; (Ger.) DIN 1.7220; (Fr.) AFNOR 35 CD 4,35 CD 4 TS; (Ital.) UNI 35 CrMo 4. 35 CrMo 3 F, 34 CrMo 4 KB; (Jap.) JIS SCM I, SCCrM 3; (Swed.) SSld 2234; (U.K.) B.S. 708A 37

6365C. 6372C;

For a predominately pearlitic structure. heat to 855 “C (I 570 “F), cool fairly rapidly to 760 “C ( I300 “F). then to 665 “C ( I230 “F) at a rate not to exceed I9 “C (35 “F) per h: or heat to 855 “C (1570 “F). cool rapidly to 675 “C (I245 “F). and hold for 4 h. For a predominately spheroidized structure. heat to 750 “C ( I380 “F). cool from 750 “C (I 380 “F) to 665 “C (I 230 “F) at a rate not to exceed 6 “C ( IO OF) per h; or cool rapidly from 750 “C ( 1380 “F) to 675 “C ( 1245 “F), and hold for 8 h. Anneal at 845 “C (I 555 “F); cool to belou 540 “C ( IO00 “F) at a rate not to exceed I IO “C (200 “F) per h

Hardening. Austenitize at 870 “C (1600 “F), and quench in oil or polymer. Flame hardening, ion nitriding, gas niuiding, and carbonitriding are suitable processes. In aerospace practice. austenitize at 855 “C (1570 “F). Quench in oil or polymer Tempering.

Forging.

l

Forge Normalize

l

Armed

l

Rough machine Austenitize and quench Temper Finish machine

Heat to 1230 “C (2245 “F) maximum. Do not forge after of forging stock drops below approximately X70 “C ( I600 “F)

Recommended

Heat Treating

Practice

Reheat to the temperature which will result in the required hardness. ln aerospace practice. see table for suggested tempering temperatures per different tensile strengths. Quenchants include oil and polymers

Recommended l

l l

Normalizing.

Heat 10 900 “C ( I650 “F). Cool in air.

at 900 “C ( 1650 “F)

Annealing.

Characteristics. 4 l35H has generally the same characteristics as 4130H. except the higher mean carbon content results in a slightly higher as-quenched hardness, about 50 to 52 HRC for 4135H. ln addition. the higher mean manganese content of 3 I35H results in higher hardenahility. CornDare hardenabilitv data for 4130H with 4135H. Also, as the hardenability increases, the suitability for welding decreases. Forgeability of 4135H is very good temperature

normalize

l

Processing

Sequence

4135H: End-Quench Hardenability

Diitancefrom queocbed surface 916 in. mm

Eardness, ERC

max

min

Distance fern quenched surface ‘116in. mm

Ei3HllleSS,

ERC

max

min

I 2

1.58 3.16

58 58

51 50

13 1-I

20.54 22.1’

48 47

32 31

3 4 5 6 7 8 9 IO II II

4.74 6.32 7.90 9.48 II.06 12.64 14.22 15.80 17.38 18.%

57 56 56 55 54 53 52 51 SO 31

49 48 47 45 42 40 38 36 34 33

IS I6 I8 20 22 24 26 28 30 32

23.70 25.28 28.4-l 31.60 34.76 37.92 41.08 44.24 47.40 50.56

46 45 4-l 42 41 40 39 38 38 37

30 30 29 28 27 27 27 26 26 26

4135, 4135H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure

Alloy Steels (1300 through

4135H: Hardenability Curves. Heat-treating (1600 “F). Austenitize:

Hardness Purposes I distance, mm 1.5 3 5 7 ?

11 13 15 20 25 30 35 $0 15 50

Hardness Purposes I distaace, $6 in. 1 2 3 1 5 5 7 B 9

10 11 12 13 14 15 6 8 :0 12 !4 :6 :8 IO I2

845 “C (1555 “F)

Limits for Specification Eardoess, HRC Masimum Minimum 58 58 57 56 56 55 53 52 49 45 43 41 40 39 37

51 50 49 48 46 42 39 37 32 30 28 27 27 26 26

Limits for Specification Hardness, ERC

Maximum

Minimum

58 58 57 56 56 55 54 53 52 51 50 49 48 47 46 45 44 42 41 40 39 38 38 37

51 50 49 48 47 45 42 40 38 36 34 33 32 31 30 30 29 28 27 27 27 26 26 26

temperatures

recommended

9700 Series) / 315

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

316 / Heat Treater’s

4135: Suggested Practice)(a) 620-860 hlPa (W-125 ksi) 850 “C (1550°F)

Guide

Tempering

Temperatures

Tensile strength ranges 860-1035 hlPa 1035-1175 MPa 11751210 (IZS-1SOksi) (150-170hi) (170-180 675 “C (1250 “F)

(a) Quench in oil or polymer.

600 T (1125°F)

Source: AbfS 27.5911

(Aerospace

MPa ksi)

480 “C 1900 “F)

1240-1380 MPa (180-2OOksi) -I25 “C (800 “F)

4135: Suggested Tempering Temperatures Based on As-Quenched Hardness (Aerospace Practice) Tensile strength

range

860 IO 1035 hlPa I I25 to I50 ksl) 365 to I IO5 hlPa I I40 IO 160 ksl, 1035t01175hlPn (ISOto 170ksi) ll75tol3l0hlPa (170~~ 19Oksi) I240 to I380 hlPu (I80 to 200 ksi) Sourer: AhlS 2759/l

RC 47-49

As-Quenched Aardness RC 50-52

RC 53-55

550 “C (1025 “F) 5lO”C (950 ‘F) 170 ‘T 1875 OF) -12s ‘T t8OO”FI ml “C r750”F,

595 “C ~1100°F~ 550 “C (1025°F) SlO”C t9SO “F) 180 “C (900 “Fb 1.55 “C t85O”F)

650 “C t 12OOT) 595 “C (1100°F) 550 “C (1025 “F) -5’5 -_ “C (975 “F) 19s “C (925 “I=)

316 / Heat Treater’s

Guide

4137,4137H Chemical

Composition.

4137. AISI and UNS: 0.3s LO0.40 C. 0.70

to0.90Mn.0.15to0.30Si.0.80to1.10Cr.0.035Pmax.0.010Smax.0.15 to 0.25 MO. UNS H41370 and SAE/AISI J137I-I: 0.34 to 0.31 C. 0.60 to 1.00 Mn. 0. IS to 0.35 Si. 0.75 to 1.20 Cr. 0.15 to 0.25 MO

Similar

Steels (U.S. and/or Foreign). 5137. LINS G41370: ASTM A322, A33 I, AS05, A5 19. AS17; SAE J-IO4 Jll2, J770; (Ger.) DIN I .7225; (Fr.) AFNOR 40 CD 4.42 CD 4; (Id.) UNI G -IO CrMo 1.38 C&lo 4 KB. 40 CrMo 1; (Jap.) JIS SCM -I H. SChl3: (Swed.) SS1.t 2344; (U.K.) B.S. 708 A 32.708 M 10.709 M 10.1137H. LJNS H41370; ASTM ,430-I; SAEJI268;(Ger.)DfN 1.722S;(Fr.)AFNOR40CDJ.42CD-l;(Ital.)LJNl G 10 C&lo 4.40 CrMo 4. 38 CrMo 4 KB; fJap.) JIS SCM 4 H. SCM 4; (Swed.) SS1-t 2244; (U.K.) B.S. 708 A 42.708 A 40.709 A 10 Characteristics. A typical medium-carbon. moderately high hardenability steel. Often referred to as a shaft steel, -I I37H is frequently used for a variety of shaft applications in the quenched and tempered condition. Depending upon the precise carbon content. the as-quenched hardness of fully hardened 4137H is generally about 52 HRC or slightly higher. usualI> a little higher than 413SH. but not as high as for ll40H. The hardenability pattern is essentially the same for 3137H as shown for 3135H: the only difference is that the band is moved upward for 4137H because of the higher carbon content. Forgeability of1137H is very good, but machinability is only fair and welding. although possible. is seldom recommended Forging. Heat to 1230 “C (22-U “F). Do not forge after temperature forging stock drops below approximately 870 “C ( I600 “F)

Recommended Normalizing.

Heat Treating

Practice

Heat to 870 “C f I600 “Fj. Cool in air

For a predominately pearlitic structure. heat to 835 “C ( I555 “F). cool fairly rapidly to 755 “C ( I390 “Fj. then cool from 755 “C ( I390 “F) to 665 “C ( 1230 “F) at a rate not to exceed I1 “C (25 “F) per h; or heat to 845 “C (I 555 “F). cool rapidly to 675 “C ( IX5 “F). and hold for 5 h. For a predominately spheroidized structure. heat to 750 “C ( 1380 “F), cool to 665 “C (I230 “F) at a rate not to exceed 6 “C (IO “F) per h; or heat to 750 “C ( I380 “F), cool fairly rapidly to 675 “C ( I245 “F). and hold for 9 h

Hardening.

Austenitize at 855 “C (I570 “F), and quench in oil. Carbonisalt bath and gas nitriding, and ion nitriding are suitable processes

Tempering.

Recommended l l l l l l l l l

Processing

Sequence

Forge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine Nitride (optional)

of

Annealing.

triding.

Nitriding. If nitriding is considered. the steel must be treated (hardened and tempered), and nitriding must be done on finished parts because any finishing operation will remove the most useful portion of the case. First. use a typical processing cycle consisting of: rough machining, austenitizing at 845 “C I I555 “FI. oil quenching. tempering at 620 “C (I I50 “F). and finish machining. Then, nitride in ammonia gas at 525 “C (975 “F) for 21 h. using an ammonia dissociation of 30%: or nitride at 525 “C (975 “F) for 5 h with an ammonia dissociation of 25%. then at 565 “C ( 1050 “F) for 20 h nith an ammonia dissociation of 75 to 805. Certain proprietary salt bath nitriding processes are also applicable for surface hardening

Reheat after quenching to the temperature shown by the hardness-tempering temperature curve to obtain the required hardness for these specific steels

4137, 4137H: sents an average

Hardness based

vs Tempering

Temperature.

on a fully quenched

structure

Repre-

Alloy

Steels (1300 through

9700 Series) / 317

4137H: End-Quench Hardenability Distance from quenched surface ‘&jin. mm I 2 3 -I 5 6 7 8 9 IO II I’

1.58 3.16

Eardness, ERC mar min

6.31 7.90 9.4 II.06 12.64

59 59 58 58 57 57 56 55

14.22

55

I5 80 17.38 18.96

54 53 52

1.71

52 51 SO 49 49 18 -Is 1.3 -IO 39 37 36

Distance from quenched surface ‘&in. mm 13 I-1 IS 16 18 10 x! 2-l 26 28 30 32

4137: Continuous Cooling Transformation tized at 860 “C (1580 “F)

20.5-i 22.12 23.70 2528 28.4-I 31 60 31.76 37.92 -I I Ax3 44.24 47.40 SO.56

Rardness. ARC mas min 51 50 49 48 46 45 44 43 4’ -I1 41 II

35 34 31 31 3’ 31 30 30 30 29 ‘9 29

Diagram. Composition:

0.36 C, 0.80 Mn, 0.020 P, 0.020 S, 0.25 Si. 1 .OOCr, 0.20 MO. Austeni-

318 / Heat Treater’s

4137H:

Hardenability

(1600 “F). Austenitize:

Hardness Purposes J distance, mm 1.5 3 5 7 3 I1 13 15 20 25 30 35 $0 15 50

Hardness Purposes I distance, 1/16in. I 2 3 1 5 5 7 3 3 IO I1 12 13 14 I5 16 I8 20 !2 !4 !6 !8 !O 52

Guide

Curves. Heat-treating 845 “C (1555 “F)

Limits for Specification Eardness, ERC MaximlUll Minimum 59 59 58 58 57 56 55 55 52 48 46 44 43 42 41

52 51 50 49 48 45 42 39 35 33 31 30 29 29 29

Limits for Specification Eardoess. ARC Maximum Minimum 59 59 58 58 57 57 56 55 55 54 53 52 51 50 49 48 46 45 44 43 42 42 41 41

52 51 50 49 49 48 45 43 40 39 37 36 35 34 33 33 32 31 30 30 30 29 29 29

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

Alloy Steel / 319

4140,414OH Chemical Composition. 4140. AISI and UNS: 0.38 to 0.43 C, 0.75 to1.00Mn,0.035Pmax,0.040Smax,0.15to0.30Si,0.80to1.10Cr,0.15 to 0.25 MO. 414OH.AISIandUNS: 0.37 to 0.44 C, 0.65 to l.lOMn, 0.035 Pmax.0.040 S max,0.15 too.30 Si.O.75 to 1.2OCr,O.15to 0.25 MO Similar Steels (U.S. and/or Foreign). 4140. UNS ~41400;

AMS

6381.6382,6390,6395; ASTM A322, A331, A505, A519, A547, A646; MlL SPEC M&S-16974; SAE J404, J412.5770; (Ger.) DIN 1.7225; f,Fr.) AFNOR 40 CD 4.42 CD 4; (Ital.) UN1 40 CrMo 4, G 40 CrMo 4,38 CrMo 4 KB; (Jap.)JIS SCM 4 H, SCM 4; (Swed.) SSt4 2244; (U.K.) B.S. 708 A 42,708 M 40,709 M 40.4140H. UNS H41400; ASTM A304; SAE 5407; (Ger.)DIN 1.7225;(Fr.) AFNOR 40 CD 4,42 CD 4; (Ital.) UN1 G 40 CrMo 4,40 CrMo 4,38 CrMo 4 KB; (Jap.) JIS SCM 4 H, SCM 4; (Swed.) SS14 2244; (U.K.) B.S. 708 A 42,708 M 40,709 M 40

Characteristics.

Among the most widely used medium-carbon alloy steels.Relatively inexpensive considering the relatively high hardenability 4140H offers. Fully hardened 4140H ranges from about 54 to 59 HRC, depending upon the exact carbon content. Forgeability is very good, but machinability is only fair and weldability is poor, becauseof susceptibility to weld cracking

Tempering. Reheatafter quenching to obtain the required hardness Nitriding. 4140H respondsto the ammonia gasnitriding process,resulting in a thin, file hard case, the outer portion of which is composedof epsilon nitride. This constituent not only provides an abrasion-resistant surface,but also increasesfatigue strength of componentssuch as shaftsby as much as 30%. However, if nitriding is considered, the steel must be pretreated(hardenedand tempered),and nitriding must be done on finished parts becauseany finishing operation will remove the most useful portion of the case.A typical processingcycle that includes nitridmg is: l l l l l l

Rough machine Austenitize at 845 “C (1555 “F) Oil quench Temper at 620 “C (1150 “F) Finish machine Nitride at 525 “C (975 “F) for 24 h, using an ammonia dissociation of 30%; or nitride at 525 “C (975 “F) for 5 h with an ammoniadissociation of 25%. then at 565 “C (1050 “F) for 20 h with an ammoniadissociation of 75 to 80%

Forging. Heat to 1230 “C (2250 “F). Do not forge after temperatureof forging stock drops below approximately 870 “C (1600 “F)

Certainproprietarysalt bath nitriding processesarealso applicablefor surface hardeningof414OH

Recommended

Recommended

Heat Treating

Practice

Normalizing. Heat to 870 “C (1600 “F). Cool in air Annealing. For a predominately pearlitic structure, heatto 845 “C (1555 “F), cool fairly rapidly to 755 “C (1390 “F), then cool from 755 “C (1390 “F) to 665 “C (1230 “F), at a rate not to exceed 14 ‘C (25 “F) per h; or heat to 845 “C (1555 “F), cool rapidly to 675 “C (1245 “F), and hold for 5 h. For a predominately spheroidized structure, heat to 750 “C (1380 “F), cool to 665 “C (1230 “F) at a rate not to exceed 6 “C (10 “F) per h; or heat to 750 “C (1380 “F), cool fairly rapidly to 675 “C (1245 “F), and hold for 9 h

l l l l l l l l l

Processing

Sequence

Forge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine Nitride (optional)

Hardening. Austenitize at 855 “C (1570 “F), and quench in oil 1140: Isothermal Transformation 7 to 8

Diagram. Composition:

0.37 C, 0.77 Mn, 0.98 Cr, 0.21 MO. Austenitized

at 845 “C (1555 “F) Grain size:

320 / Heat Treater’s

Guide

4140H: End-Quench Hardenability Distance from quenched surface

&jh. 1 2 3 4 5 6 7 8 9 10 11 12

mm 1.58 3.16 4.14 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38 18.96

Hardness, ARC max min 60 60 60 59 59 58 58 57 57 56 56 55

53 53 52 51 51 50 48 41 44 42 40 39

4140: Cooling Transformation

Distance from quenched surface

‘/x6h

mm

13 14 15 16 18 20 22 24 26 28 30 32

20.54 22.12 23.10 25.28 28.44 31.60 34.16 31.92 41.08 44.24 41.40 50.56

Hardness, ARC max min 55 54 54 53 52 51 49 48 41 46 45 44

38 37 36 35 34 33 33 32 32 31 31 30

Diagram. Composition: 0.44 C, 1.04 Mn, 0.29 Si, 1 .13 Cr, 0.15 MO. Austenitized size: 9. AC,, 795 “C (1460 “F); AC,, 750 “C (1380 “F). A: austenite, F: ferrite, P: pearlite, B: bainite, M: martensite.

at 845 “C (1555 “F). Grain Source: Bethlehem Steel

Alloy Steel / 321

4140:

Effect of Microstructure

on Tool Life

Feed was 0.010 in./rev (0.25 mm/rev) for all specimens;

depth of cut was 0.100 in. (2.5 mm). Microstructure

Steel condition

Hardness, HB

Pearlite

Ferrite

192 180 300

90 65

10 35

Normalized Annealed Quenched tempered

4140:

As-Quenched

Specimens

‘h 1 2 4

Tempered martensite

Hardness

13 25 51 102

ft/miu

mm/s

300 360 300

1520 1830 1520

4140: Hardness vs Tempering Temperature. Normalized at 870

quenched in oil

mm

cutting speed

100

Size round in.

constituent, %

“C (1600 “F). Quenched from 845 “C (1555 “F) in oil and tempered in 56 “C (100 “F) intervals in 13.716 mm (0.540 in.) rounds. Tested in 12.827 mm (0.505 in.) rounds. Source: Republic Steel

Surface

Hardness, HRC t/z radius

Center

57 55 49 36

56 55 43 34.5

55 50 38 34

Source: Bethlehem Steel

4140: Effect of Mass. Composition: 0.38 to 0.43 C, 0.75 to 1 .OO Mn, 0.040 P max, 0.040 S max, 0.20 to 0.35 Si, 0.80 to 1.10 Cr, 0.15 to 0.25 MO. Approximate critical points: AC,, 730 “C (1350 “F); AC,, 805°C (1480°F); Ar,, 745 “C (1370°F); Ar,, 680 “C (1255 “F). Recommended thermal treatment: forge at 1205 “C (2200 “F) maximum, anneal at 815 to 870 “C (1500 to 1600 “F) for a maximum hardness of 197 HB, normalize at 845 to 900 “C (1555 to 1650 “F) for an approximate hardness of 311 HB; quench from 830 to 855 “C (1525 to 1570 “F) in oil. Test specimens were normalized at 870 “C (1600 “F) in over-sized rounds, quenched from 845 “C (1555 “F) in oil in sizes shown, tempered at 540 “C (1000 “F), tested on 12.827 mm (0.505 in.) rounds. Tests from 38.1 mm (1.5 in.) diam bars and over are taken at half radius position. Source: Republic Steel

4140: Gas Nitriding. Oil quenched from 845 “C (1555 “F), tempered at 595 “C (1105 “F), and nitrided at 550 “C (1020 “F) I I

4140: Depth of Hardness.

31.75 mm (1.25 in.) diam bars,

through hardened by induction

0

20 Duration

40 of nitriding,

60 hr

60

322 / Heat Treater’s

Guide

4140: Effect of Mass. Composition: 0.38 to 0.43 C, 0.75 to 1 .OO Mn, 0.040 P max, 0.040 S max, 0.20 to 0.35 Si, 0.80 to 1.10 Cr, 0.15 to 0.25 MO. Approximate critical points: AC,, 730 “C (1350 “F); AC,, 805 “C (1480°F); Ar,, 745 “C (1370 “F); Ar,, 680 “C (1255 “F). Recommended thermal treatment: forge at 1205 “C (2200 “F) maximum, anneal at 815 to 870 “C (1500 to 1600 “F) for a maximum hardness of 197 HB, normalize at 845 to 900 “C (1555 to 1650 “F) for an approximate hardness of 311 HB; quench from 830 to 855 “C (1525 to 1570 “F) in oil. Test specimens were normalized at 870 “C (1600 “F) in over-sized rounds, quenched from 845 “C (1555 “F) in sizes shown, tempered at 650 “C (1200 “F), tested on 12.827 mm (0.505 in.) rounds. Tests from 38.1 mm (1.5 in.) diam bars and over are taken at half radius position. Source: Republic Steel

4140: Variations in Hardness after Production Tempering. (a) 76.2 mm (3 in.) diam valve bonnets. Steel from one mill heat. Parts heated at 870 “C (1600 “F), oil quenched, and tempered at 605 “C (1125 “F) to a hardness of 255 to 302 HB. (b) Valve segments, 12.7 to 25.4 mm (0.5 to 1 in.) section thickness. Steel from one mill heat. Parts heated at 870 “C (1600 “F), oil quenched, and tempered at 580 “C (1075 “F) to a hardness of 321 to 363 HB

4140: Depth of Case vs Duration of Nitriding. Double stage nibided at 525 “C (975 “F). Numbers indicate hours of nitriding at 15 to 25% dissociation. Remainder of cycle at 83 to 85% dissociation

4140: Effect of Microstructure

on Tool Life

Heat Treater’s

Guide: Practices

and Procedures

for Irons and Steels

Copyright@ ASM International@ 1995

Alloy Steel I323

4140: Gas Nitriding. (a) 7 h, 2 suppliers, 20 to 30% dissociation; dissociation; (d) 40 h, 5 heats, 25 to 30% dissociation; to 30% dissociation; (h) 50 h, 20 to 30% dissociation. core hardness

(b) 9 h, 2 heats, 25 to 30% dissociation; (c) 24 h, 2 suppliers, 20 to 30% (e) 90 h, 9 heats, 25 to 35% dissociation; (f) 25 h, 20 to 30% dissociation; (g) 35 h, 20 For (f), (g), (h), 1: 21 to 23 HRC; 2: 26 to 28 HRC; 3: 33 to 35 HRC; 4: 36 to 37 HRC

324 / Heat Treater’s

4140: Microstructures.

Guide

(a) 2% nital, 825x. Resulfurized forging normalized by austenitizing at 900 “C (1650 “F) Ii2 h. air cooling; annealed by heating at 815 “C (1500 “F) 1 h. furnace cooling to 540 “C (1000 “F), air cooling. Blocky ferrite and fine-to-coarse lamellar pearlite. Black dots are sulfide. (b) Nital, 500x. 25.4 mm (1 in.) diam. austenitized at 845 “C (1555 “F) 1 h. cooled to 650 “C (1200 “F). and held 1 h for isothermal transformation, then aircooled to room temperature. White areas, ferrite; gray and black areas, pearlite with fine and coarse lamellar spacing. (c) 2% nital, 500x. Hot rolled steel round bar. 25.4 mm (1 in.) diam, austenitized at 845 “C (1555 “F) for 1 h and water quenched. Fine, homogeneous. untempered martensite. Tempering at 150 “C (300 “F) would result in a darker etching structure. (d) 2% nital, 500x. Same as (c), except the steel was quenched in oil rather than water, resulting in the presence of bainite (black constituent) along with the martensite (light). (e) 2% nital, 750x. Steel bar austenitized at 845 “C (1555 “F). oil quenched to 66 “C (150 “F), and tempered 2 h at 620 “C (1150 “F). Martensite-ferrite-carbide aggregate. (f) As polished (not etched), 200x. Oxide Inclusions (stringers) in a steel bar, 25.4 mm (1 in.) diam. Stringers parallel to the direction of rolling on the as-polished surface of the bar. (g) Not polished, not etched, 8600x. Replica electron fractograph showing the dimpled structure typical of the overstress mode of failure. (h) 2% nital, 400x. Oil quenched from 845 “C (1555 “F), tempered for 2 h at 620 “C (1150 “F), surface activated in manganese phosphate, gas nitrided for 24 h at 525 “C (975 “F), 20 to 30% dissociation. 0.0050 to 0.0076 mm (0.0002 to 0.0003 in.) white surface layer Fe,N, iron nitride, and tempered martensite. (j) 2% nital. 400x. Same steel and prenitriding conditions as (h). except double stage gas nitrided: 5 h at 525 “C (975 “F), 20 to 30% dissociation: 20 h at 565 “C (1050 “F), 75 to 80% dissociation. High second-stage dissociation caused absence of white layer. Diffused nitride layer and a matnx of tempered martensite

Alloy Steel I325

4140H: Hardenability

Curves. Heat-treating temperatures 845 “C (1555 “F) -

(1600 “F). Austenitizk

Hardness purposes

I

limits for specification

I

I distsnce, mm

I

1.5

1 4 ; !

a

I1 13 II.5 2!O : !.5 )O )5 L10 L15 I I

io

z

I I

Hardness purposes I distance, II,l(i”.

. I

I 2 3 1 5 f5 7 I3 ,3 10 11 12 13 14 15 16 18 !O ,2 24 26 i ‘8 30 32

Hardness, HRC hlaximum hfiuimum 60 60 60 59 59 58 51 51 5.5 53 51 49 48 46 45

53 52 52 51 50 48 46 43 38 35 33 32 32 31 30

limits for specification Hardness, HRC Maximum hfinimum

60 60 60 59 59 58 58 51 57 56 56 55 55 54 54 53 52 51 49 48 47 46 45 44

53 53 52 51 51 50 48 47 44 42 40 39 38 37 36 35 34 33 33 32 32 31 31 30

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

1

326 / Heat Treater’s

Guide

4142,4142H Chemical Composition. 4142. AISI and UN.% 0.40 to 0.45 C, 0.75 to1.00Mn,0.035Pmax,0.040Smax.0.15to0.30Si.0.80to1.10Cr.0.15 to 0.25 MO. UNS 841420 and SAE/AISI 4142H: 0.39 to 0.46 C, 0.65 to I. IO Mn. 0. I5 to 0.35 Si, 0.75 to 1.20 Cr. 0.15 to 0.35 MO

Tempering. required

Reheat after quenching hardness

to the temperature

to obtain

the

Steels (U.S. and/or Foreign). 4142. UNS G41420; ASTM A322. A33 I. A505. A5 19, A 547; SAE 5404.5412. J770.41428.

Nitriding. If nitriding is considered. the steel must be pretreated (hardened and tempered), and nitriding must be done on finished parts because any finishing operation will remove the most useful portion of the case. A typical processing cycle that includes nitriding is

UNS H41420; ASTM CrMo 4

l

Similar

A304; SAE J 1268: (Ger.) DfN I .7223; (Ital.) UNI 38

Characteristics. A slightly higher carbon version of 4140H. Characteristics are essentially the same as those described for 4140H. Depending on the precise carbon content within the allowable range, as-quenched hardness of fully hardened 4142H should be at least 54 HRC and may be as high as 60 HRC. 4142H is also a high hardenability steel. Can be readily forged, but as carbon increases, the susceptibility to cracking in heat treating or welding also increases, while machinability decreases Forging.

Heat to 1230 “C (2250 “F). Do not forge after temperature forging stock drops below approximately 870 “C (I600 “F)

Recommended Normalizing.

Heat Treating

l l l l l

of

Practice

Heat to 870 “C (1600 “F). Cool in air

Certain proprietaty hardening

For a predominately pearlitic structure. heat to 845 “C ( 1555 “F), cool fairly rapidly to 755 “C ( I390 “F). then cool from 755 “C ( I390 “F) to 665 “C ( I230 “F) at a rate not to exceed I4 “C (25 “F) per h; or heat to 845 “C (I 555 “F). cool rapidly to 675 “C ( I245 “F). and hold for 5 h. For a predominately spheroidized structure, heat to 750 “C (I 380 “F), cool to 665 “C ( 1230 “F) at a rate not to exceed 6 “C (IO “F) per h; or heat to 750 “C (I380 “F’), cool fairly rapidly to 675 “C (I 245 “F), and hold for 9 h Austenitize at 855 “C (I570 OF). and quench in oil. Flame hardening, ion nitriding, gas nitriding, and carbonitriding are suitable processes

salt bath nitriding

Recommended l

Annealing.

Hardening.

Rough machine Austenitize at 845 “C (1555 “F) Oil quench Temper at 620 “C ( I I50 “F) Finish machine Nitride at 525 “C (975 “F) for 24 h. using an ammonia dissociation of 30% or nitride at 525 “C (975 “F) for 5 h with an ammonia dissociation of 25%. then at 565 “C (1050 “F) for 20 h with an ammonia dissociation of 75 to 80%

l l l l l l l l

processes are also applicable for surface

Processing

Sequence

Forge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine Nitride (optional)

4142: Increase in Lead Change with Depth of Nitrided Case. 13-tooth five-pitch helical pinion gear, hardened and tempered at 565 “C (1050 “F)and nitrided in two stages at 525 “C (975 “F) using ammonia dissociation rates of 15 to 25% for the first stage and 63 to 65% for the second stage

4142, 4142H: Hardness vs Tempering Temperature. sents an average based on a fully quenched structure

Repre-

Alloy Steel / 327

4142H: Continuous Austenitized

Cooling Transformation

Diagram. Composition:

0.42 C, 0.85 Mn, 0.020 P, 0.020 S, 0.25 Si, 1 .15 Cr, 0.20 MO.

at 880 “C (1580 “F)

4142H: End-Quench Hardenability Distance born quenched surface ‘/lb in. mm I -l ; -I 5 6 7 8 9 IO II I2

Eardness, ERC max min

I x3

62

5.5

4.73 3.16 6.32 7.90 9.18 Il.06 12.64 11.22 IS.80 17.38 18.96

62 61 61 61 60 60 60 59 59 58

!bl 55 53 53 52 51 50 49 47 46 4.4

4142: isothermal Transformation Distance from quenched surface &in. mm I3 I-l IS 16 18 20 22 24 26 28 30 32

20.51 22.12 23.70 25 28 28.-M 31.60 34.76 37.92 11.08 44.24 47.40 SO.S6

Diagram. Composition: 0.42 C. 0.89 Mn, 0.018 P, 0.028 S, 0.23 Si, 0.05 Ni, 0.94 Cr, 0.18 MO, 0.025 Al. 0: austenitized at 870 “C (1800 “F); 0: austenitized at 980 “C (1795 “F); A: austenitized at 1095 “C (2005 “F)

Eardoess. ERC min max 58 57 57 56 55 54 53 53 52 51 51 so

42 41 -+o 39 37 36 35 34 3-I 3-l 33 33

I

328 / Heat Treater’s

Guide

4142H: Hardenability (1600 “F). Austenitize:

Hardness purposes J distuuce, mm

Curves. Heat-treating 845 “C (1550 “F)

limits for specification Rardness, Maximum

ARC hlinimum

I .5 3 5 7 Y II I3 IS 20 2s

67 62 62 62 61 61 60 60 58 56

55 s-l s-l 53 52 51 -19 -la 13 BY

30 35

55 53

36 3s

40 15 so

52 51 SO

3-l 33 33

Hardness purposes I distauce, !/,6 in. I , 1 5 1 s ) IO II I2 13 I-1 IS 16 18 !O !2 !-I !6 !8 10 12

limits for specification Eat-does, Maximum 62 62 62 61 61 61 60 60 60 59 99 58 58 57 57 56 55 51 53 53 92 51 Sl 50

q RC Minimum 55 55 51 53 53 52 51 50 -19 -17 -I6 -l-l 12 -II 40 39 37 36 35 31 34 3-l 33 33

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

Alloy

4145,4145H,

Steel I329

4145RH

Chemical

Composition. 4145. AISI and CJNS: O.-l3 to 0.18 C. 0.75 to l.00hln.0.03SPmax.0.010Sniax.0.1Sto0.30Si.0.80toI.IOCr.0.lS to 0.3 MO. UNS H41450 and SAE/AISI 4145H: 0.42 to 0.49 C. 0.65 to I.10 Mn. 0.15 to 0.35 Si. 0.75 to I.20 Cr. 0.15 to 0.1-S hlo. SAEJIJSRH: O.-l3 to 0.48 C. 0.75 to 1.00 Mt. 0.80 to I. IO Cr. 0. I5 to 0.35 hlo Similar Steels (U.S. and/or Foreign). 41~5. 11~s G11150: ASThl A322 A33l. AS05. ASl9: hllL SPEC hIIL-S-16974; SAE J-104. J-112. J770.4145H. 1JNS H1I4SO; ASTM A3O-l. A9l-l: SAE 51’68. Jl868 Characteristics.

4145H. along with 1147H and -1lSOH. is commonly known tts a high-strength steel. All are capable ofbetn~g heat treated to high strengths. As-quenched -I l4SH M ill have hardness values ranging generally from approximately 55 to 62 HRC. In hardenability. 4l-tSH ranks as one of the highest of the AISI alloy steels. ForSeability is good. but because of high carbon content and high hnrdenahility. restricted cooling rate from the ftnish forging temperature is generally recommended. This can he accomplished hy cooling in a furnace or by co\ering with on insulating mnterial. Rapid cooling from the forginp temperature can result in cracking, especially for ForSings of complex contigurntton. hlachinahility is penerally regarded as poor. although 414SH is machined try all of the conventional processes. Strongly susceptible to \\eld cracking, and the entire \\elding process must be closely controlled. Often \selded usmg more sophisttcated processes such as plasma orc and electron beam. partly because of the applications for which it is most often used

Recommended Normalizing.

Heat to I220 “C (2225 “F). Do not forge after temperature of forging stock drops below approxmlately 870 ‘C t 1600 “Fj. Slow coolinp is recommended

Practice

Heat to 870 “C t 1600 “F). Cool in air

Annealing.

For a prsdominstely pcnrlitic structure. heat to 830 “C ( IS25 “Fj. cool fairly rapidly to 7-tS “C i 1370 “Fj. then to 670 “C ( I?-tO “Fj at a rate not to exceed 8 “C t IS W per h: or heat to 830 “C (IS25 “Pj. cool rapidly to 675 C t l2-lS “F). and hold for 6 h. For a predominately ferritic and spheroidired carhide structure. heat to 750 “C (I 380 ‘F’j. cool to 670 “C t 1240 “Fj at a rote not to esceed 6 ‘C t IO “Fj per h; or cool fairly rapidly from 750 “C t I380 “Fj to 660 “C t I230 OF). and hold for IO h

Hardening. Heat to 845 “C t IS55 “Fj, and quench in oil or polymer. Flame hardening. ion nitriding. gas nitridinp. and carbonitriding are suitable processes Tempering.

After quenching, reheat immediately to the tempering perature that will provide the required strength and/or hardness

Recommended l l l l

Forging.

Heat Treating

l l l

Processing

tem-

Sequence

Forge Normalize Anneal Rough machine Austenitire and quench Temper Finish mnchins

4145H: End-Quench Hardenability Distance from quenched surface &in. mm

Hardness, HRC mar min

Distance from quenched su tface l/l6 in. mm

Hardness, q RC max min

I

I..58

63

56

I?

‘0 5-I

59

-Lb

2 3 4 z

3.16 4.74 6.32 9.18 7.90

63 62 62 61 62

55 55 5-l 53

I-l IS I6 ‘018

22.12 23.70 3.18 3 I .60 28.4-I

59 58 S8 57

-I5 4.1 12 10 38

7 8

II 06 12.6-l

61 61

51 52

21 11

34.76 37.9’

Sh 55

37 36

9 IO

14.22

IS.80

60 h0

51 SO

26 28

-11.08

55 55

35

II I2

17.38 18.96

60 59

49 18

30 32

-17.10 50.56

5s 54

3-1 3-l

44.2-I

35

4145, 4145H: Hardness vs Tempering Temperature. sents an average

based

on a fully quenched

structure

Repre-

330 / Heat Treater’s

Guide

4145H: Hardenability (1600 “F). Austenitize:

Hardness purposes J distance, mm 1.5 3 5 7 ? 11 13 15 20 25 30 35 40 15 50

Hardness purposes I distance, Y,6 ill.

1 I , , I 1 I 0 1 2 3 4 5 6 8 10 12 14 16 18 i0 i2

Curves. Heat-treating 845 “C (1555 “F)

limits for specification Ehrdness, ERC llleximum Minimum 63 63 63 62 62 61 61 60 59 58 51 56 55 55 55

limits for

56 55 55 54 53 52 51 50 47 42 39 31 35 34 34

specification

Hardness, HRC Maximum Minimum 63 63 62 62 62 61 61 61 60 60 60 59 59 59 58 58 51 57 56 55 55 55 55 54

56 55 55 54 53 53 52 52 51 50 49 48 46 45 43 42 40 38 31 36 35 35 34 34

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

Alloy Steel / 331

4145RH: Hardenability Curves. Heat-treating “C (1600 “F). Austenitize: 845 “C (1555 “F)

Hardness purposes J distance, ‘/,6 in. I 2 3 4 5 6

1 8 9 IO II I? I3 I-l

IS 16 I8 20 22 24 26 28 30 32

Hardness purposes 1 distance,

mm IS 3 5

limits for specification Hardness, HRC hfaximum hfiuimum 62 62 61 61 60 60 59 59 58 58 58 57 51 56 56 55 54 53 52

57 51 56 56 55 55 5-l 53 52 52

51 SO 49 48 41 46 4-I 43 42

51

40

51 SO SO 49

40 39 38

31

limits for specification Eardness, HRC hlaximum Minimum

7 3 II I3

62 62 61 61 60 59 59

I5 10

58 51

Pi 30 ss lo 1s 50

55 5-I 52 Sl SO 49

51 51 56 56 55 s-i 53

52 19 -16 44 42 -IO 39

31

temperatures

recommended

by SAE. Normalize

(for forged or rolled specimens

only): 870

332 / Heat Treater’s

Guide

4147,4147H Chemical

COITIpOSitiOn. 4147. AISI and UNS: 0.45 to 0.50 C. 0.75 to 1.00 Mn.0.035 Pmax, O.O-lOS niax.0. I5 to 0.30 Si.O.80 to l.lOCr.0. IS to 0.25 MO. UNS H41470 and SAE/AISI 4147H: 0.U to 0.5 I C. 0.65 to I.10 Mn. 0.15 to 0.35 Si. 0.75 to 1.20 Cr. 0.15 to 0.25 Mo

Similar

Steels (U.S. and/or

Foreign).

4147.

UNS

~31470;

ASTM A322, A331, AS05. A519; WE J-W, Ul?, 5770: tGer.) DIN 1.7228; (Jap.) JIS SCM 5 H. SCM 5.4147H. UNS H11170: ASTM A30-I: SAE J 1268: (Ger.) DIN I .7228: (Jap.) JIS SCM 5 H. SCM 5

Characteristics.

The characteristics are much the same as those outlined for 111SH. Because of increased carbon content. the maximum as-quenched hardness is slightly higher. approximately 56 to 63 HRC. depending on the precise carbon content. Hardenability is high. and the band shows about the same pattern as that for 313SH. except for a shift slightly upward. Susceptibility to craching because of rapid cooling after forging. welding. or heat treating is greater than that for 111SH because of the higher carbon content

Annealing. For a predominately pearlitic structure. heat to 830 “C (I 52s OF). cool fairly rapidly to 745 “C ( I370 “FJ, then to 670 “C ( I240 “F) at a rate not to exceed 8 “C ( IS “F) per h: or heat to 830 “C ( IS25 “F), cool rapidly to 675 “C t 1245 “F). and hold for 6 h. For a predominately ferritic and spheroidized carbide structure, heat to 750 “C ( I380 “F), cool to 670 “C t 12-10 “F) at a rate not to exceed 6 “C ( IO “F) per h; or cool fairly rapidly from 750 “C ( I380 “F) to 660 ‘C t I220 “F). and hold for IO h Hardening. ing. ion &riding,

Tempering. perature that !iill

Heat to 1220 “C (2225 “F). Do not forge after temperature of forging stock drops below approsimately 870 “C t 1600 “F). Slow cooling is recommended

Recommended Normalizing.

Heat Treating

Forge Normalize

l

AL\nnlal

l

Rough machine Austenitize and quench Temper Finish machine

l

Heat to 870 “C t I600 “FL Cool in air

Processing

l

l

Practice

After quenching. reheat immediately to the tempering provide the required strength and/or hardness

Recommended l

Forging.

Heat to 8-U “C t 1555 “F). and quench in oil. Flame hardengas nitriding. and carbonitriding are suitable processes

l

Sequence

4147, 4147H: Hardness vs Tempering Temperature. sents an average based on a fully quenched structure

4147H: End-Quench Hardenability Distance from quenched surface l/16 in. mm I

Hardness, ARC max mia

Distance from quenched surface l/16 in. mm

Hardness, HRC max min

;7

I.58 4.71 3.16

64 64

57 56 57

IS I-l IS

'054 22.12 23.70

61 61 60

49 43 46

-I 5

6.32 7.90

64 63

56 55

16 18

25.28 28.4-I

60 59

4s 12

6 7 8

9.18 I I.06 12.64

63 63 63

55 5s 51

20 22 34

31.60 34.76 37.92

59 St? 57

40 39 38

9 IO

11.22 IS.80

63 62

s-l 53

26 28

-l I .08 44.24

57 57

37 Sl

II I2

17.38 18.96

62 62

52 51

30 32

47.40 SO.56

56 56

37 36

tem-

Repre-

Alloy Steel I333

4147H: Hardenability Curves. Heat-treating (1600 “F). Austenitize:

Hardness purposes I distance, mm 1.5 3 5 7 9 11 13 15 20 25 30 35 to 15 50

iardn ess wrposes I distance. 46in.

0 1 2 3 4 5 6 8 !O 12 !4 !6 18 IO I2

845 “C (1555 “F)

limits for specification Eardness,ERC Maximum hlinimum 64 64 64 64 63 63 63 63 62 60 59 58 57 57 56

57 57 56 55 55 55 54 53 50 45 42 39 37 36 36

limits for specification Eardness, Maximum 64 64 64 64 63 63 63 63 63 62 62 62 61 61 60 60 59 59 58 57 57 57 56 56

HRC hlinimum 57 57 56 56 55 55 55 54 54 53 52 51 49 48 46 45 42 40 39 38 37 37 37 36

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

334 / Heat Treater’s

Guide

4147: Isothermal Transformation

Diagram. Composition:

0.46 C, 0.77 Mn, 0.016 P, 0.025 S, 0.28 Si, 0.15 Ni. 1.06 Cr, 0.22 MO

334 / Heat Treater’s Guide

4150,415OH Chemical Composition.

4150. AISI and UNS: 0.18

to

0.53

c.

0.75

Recommended

to 1.00 Mn.0.035 Pmax, 0.04OS max. 0.15 100.30 Si.0.8010 I. IOCr.0.1.5 to 0.25 MO. UNS 641500 and SAE/AISI 4150A: 0.47 to 0.53 C. 0.65 to I.10 Mn. 0.15 to 0.35 Si, 0.75 to I.20 Cr. 0.15 to 0.25 MO

Normalizing.

Similar Steels (U.S. and/or Foreign). 4150.

Annealing.

UNS

G-~I~OO: ASTM A322. A331, ASOS. ASl9; MfL SPEC MLL-S-I I595 (ORD-IISO); SAE J404, J412, J770; (Ger.) DIN 1.7228: (Jap.) JJS SCM 5 H, SChl 5.

4150H. UNS H41500; ASTM A304; SAE Jl268; (Ger.) DIN I .7228; (Jap.) JIS SCM 5 H. SCM 5

Characteristics. High-hardenability steel. capable of being heat treated to high levels of strength. When the carbon content is on the higher side of the allowable range (0.53%). as-quenched hardness can approach 65 HRC. Characteristics are generally the same as those given for 314SH and 4147H. Minor differences because of higher carbon content include higher as-quenched hardness, an upward shift of the hardenability band. and an even greater tendency to cracking during heat processing Forging. Heat to 1220 “C (2275 “F). Do not forge after temperature of forging stock drops below approximately 870 “C (1600 “F). Slow cooling is recommended

Heat Treating

Practice

Heat to 870 “C ( I600 “F). Cool in air.

Jn aerospace practice.

normalize

at 870 “C (I 600 “F)

For a predominately pearlitic structure, heat to 830 “C (I 525 “F), cool fairly rapidly to 71.5 C (I370 “F). then to 670 “C (1240 “F’) at a rate not to exceed 8 “C ( I5 “F) per h; or heat to 830 “C ( I525 “F), cool rapidly to 675 YY ( I245 “F). and hold for 6 h. For a predominately ferritic and spheroidized carbide structure. heat to 750 “C (1380 “F). cool to 670 “C ( I210 “F) at a rate not to exceed 6 “C ( IO “F) per h: or cool fairly rapidly from 750 “C ( I380 “F) to 660 “C ( 1220 “FL and hold for IO h. In aerospace practice. anneal at 830 “C ( I525 “F). Cool below 540 “C ( 1000 “F) at a rate not to exceed I IO “C (200 “F) per h

Hardening. Heat to 8-15 “C ( IS55 “F). and quench in oil or polymer. Flame hardening, boriding, ion nitriding. gas nitriding. carbonitriding. austempering and martempering are candidate processes. In aerospace practice, parts are austenitized at 830 “C ( IS25 “F). and are quenched with oil or polymer Tempering.

After quenching, reheat immediately to the tempering temperature that will provide the required strength and/or hardness. See table

Alloy Steel / 335 Recommended l

Forge Normalize

l

Anneal

l

l l l l

Processing

Sequence

4150:

As-Quenched

Specimens

Hardness

quenched in oil

Size round

Rough machine Austenitize and quench Temper Finish machine

In.

‘/z I 2 4

mm 13 25 91 102

Surface

Eardness, ERC % radrus

Ceoler

64 62 58 47

64 62 57 43

63 62 56 42

Source: Bethlehem Steel

4150: Continuous Cooling Transformation

Diagram. Composition:

0.50 C, 0.85 Mn, 0.020 P. 0.020 S, 0.25 Si, 1 .OOCr, 0.22 MO. Austeni-

tized at 850 “C (1560 “F)

4150: End-Quench Hardenability.

Use of successively higher austenitizing temperatures. Composition: 0.55 C, 0.84 Mn. 0.30 Si, 0.13 Ni, 0.92 Cr, 0.21 MO

336 / Heat Treater’s

Guide

4150H: Hardenability

Curves. Heat-treating 845 “C (1555 “F)

(1600 “F). Austenitize:

Hardness purposes

limits for specification

J distance, mm

Hardness, HRC Maximum hlinimum

1.5 3 5 7 9 11 13 15 20 25 30 35 40 45 50

Hardness purposes J distance, I46 in. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32

65 65 65 65 65 65 65 64 63 62 61 60 59 58 58

limits

59 59 58 58 57 57 56 55 51 47 44 41 39 38 38

for specification Hardness, ARC Maximum hlinimum 65 65 65 65 65 65 65 64 64 64 64 63 63 62 62 62 61 60 59 59 58 58 58 58

59 59 59 58 58 57 57 56 56 55 54 53 51 50 48 47 45 43 41 40 39 38 38 38

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

Alloy Steel I337

4150H: End-Quench Hardenability Distance from quenched surface &in. mm

Hardness. HRC mah min

Distance from quenched surface

‘/16h.

mm

Hardness. HRC ma\: min

7I ;

I .S8

69

59

I?

10.5-l

63

51

1.74 3 lb

6S bS

59

15 I-1

23 70 21.1:

b2 62

18 50

.I s 6

6 32 I 90 9.48

65 65 6.5

58 S8 Sl

I6 I8 20

25.3 28.44 3 I .hO

b2 61

47 4s

bO

-I3

8 9 I0

1

II.06 12.6-l l-1.2’ IS.80

6S 6-I 61 64

57 S6

22 21 lb

31.16

Sb

37.9: 4l.08

59 59 58

-II 10 39 38

II I2

17.38 18.96

6-l 63

s-l 53

30 31

47.40

58

SO.Sb

SY

38 38

S5

28

44.2-l

58

4150, 4150H: Hardness vs Tempering Temperature. Repre-

4150: Hardness vs Tempering Temperature. Normalized at 870

sents an average based on a fully quenched structure

“C (1600 “F), quenched from 845 “C (1555 “F), and tempered in 56 “C (100 “F) intervals in 13.716 mm (0.540 in.) rounds. Tested in 12.827 mm (0.505 in.) rounds. Source: Republic Steel

4150: Suggested Tempering Temperatures (Aerospace Practice)(a) 860-1035 hlPa (125l50bi)

Tensile strength ranges 1035-1175 hlPa 1175-1240 MPa (150-170 ksi) (170-180 ksi)

650 “C (IXIO’F, ~a)Qurnch

59s “C (I lOO”F, ~iioilorpol~mrr.

53 “C (975 “F)

Source: .~hlS ?7S9/l

1240-1380 hlPa (180-200 hi) 41s “C lXOO”F,

Alloy Steel I337

4161,4161H, Chemical

4161RH

Composition.

4161. AISIand UNS: 0.56 to 0.64 C, 0.75 to 1.00 Mn, 0.035 P max, 0.040 S max. 0.15 to 0.30 Si, 0.70 to 0.90 Cr, 0.25 to 0.35 MO. UNS H41610 and SAE/AISI 4161H: 0.55 to 0.65 C, 0.65 to 1.10 Mn, 0.15 to 0.35 Si, 0.65 to 0.95 Cr. 0.25 to 0.35 M O. SAE 4161RI-I: 0.56 to 0.64 C, 0.75 to 1.00 Mn, 0.15 to 0.35 Si, 0.70 to 0.90 Cr, 0.25 to 0.35 MO

Similar Steels (U.S. and/or Foreign). 4161. UNS ASTM A322, A33 1; SAE J404,54 12,5770.4161H. UNS H4 1610; ASTM A304, A914; SAE 51268

Characteristics. A high-carbon steel, with a mean carbon content of 0.60%, has the highest carbon content of the 4100 steels. Chromium content is lower and the molybdenum content is higher than that of 4150H and other steels in the 4100 series. As a result. hardenability is higher. The band shows clearly that when all elements affecting hardenability are on the high side, the upper line of the band approaches that of an air-hardening steel, nearly a straight line. Depending on the precise carbon content, as-quenched hardness for 4161 H ranges From 60 to 65 HRC. Often used for various tool, die, and spring applications. Well suited for heat treating by

338 / Heat Treater’s

Guide

the austempcring process. MUSI he mated CiUCfully in all hcitt prowssing iIpplications lo avoid cracking

g;lS nilriding. austcmpcring.

Forging. ~~cat IO 120~ “C (2200 “t:). DO not I’ogc alicr tcmpcraturc of Ibr@ng stock drops hclow approximntcly X70 “C (IMX) “F). Forgings should Aways IX COOM SIOWIY IO itvoid critcking

Tempering.

Recommended Normalizing.

Heat Treating

iulslcmpcring, iilld c;whonilriding urc Slliliiblc quenching is in iI molten salt bath

proccsscs.

Bcforc parts rc;rh room tcmpcritturc. tcmpcr immcdiatcly. 38 10 SO “C (IO0 to I20 “F) is idcitl. ‘I’hc tcmpcring tcmpcraturc depends upon the dcsircd h;rrdncss or combination of’ propcrtics

Austempering. Austcnitize ai X30 “C ( IS25 “I:), quench into a wcllilpiti~tcd I~ICII SCIIIhilth ill 3 I5 ‘7’ (000 “F). hdtl Ibr 2 h, imd COOI in ;Gr. No tcmpcring is rcquirctl

Practice

Hcai IO X55 “C: (IS70 “I:). C:ool in air

Annealing.

For subscqucnt milchinine or opcmtinns involved in I;lhricw ing P;UIS. B prcdominatcly sphcroidizcd micmstmcturc is usually prcliirrcd. This cun hc uchievcd hy hwing IO 760 “C (IWO “F), cooling to 705 “C’ (IBOO ‘19 81 iI riitc not IO cxcccd 6 “C: ( IO “l;) per h; or by heating IO 760 “C‘ ( I4W “F). cooling f;iirly ntpidly to (,(A) “CT ( I220 “19, imd holding Ihr IO h

Hardening.

I lcilt to X30 “c’ ( IS25 “I’), itlId quench in oil. Thin sections may be I’ully hardcncd hy ;tir cooling liom XBO “C ( IS25 “F). Ion nitriding.

Recommended

Processing

l

IGgc Normali/.c

l

,\lllKxil

l

KOUgh

l

iId quench (or ;tustcmpcr) Tcmpcr (or ilustcmpcr) Finish m;rchinc (or illlStClllpCr)

l

l l

Sequence

lllilChillC

Au~~cl~i~izc

4161H: End-Quench Hardenability Distance frum quenched surface 916 in. mm

I 2 3 4 s 6 7 x 0 IO II 12

I.58 3.10 4.14 6.32 7.90 9.18 I I .ofl 12.64 14.22 IS.XO 17.38 I x.96

Hnrdness, HWC IIIPX min

0.5 OS 05 65 OS 6.5 h5 OS 65 65 65 6-l

60 bo ho 60 60 OfI h0 b0 SJ 59 59 so

Iktnncc liw~~~ quenched surface l/16 in. mm

13 I3 IS I0 IX 20 22 2-l 26 2x 30 32

20.5-I 22.12 23.70 2.5.28 2x.44 3 I .60 31.76 37.92 41.0x 4J.ZJ 17.40 5050

Iii

Hardness, HHC mnx min

04 64 03 61 6-t 03 (13 63 h3 03 0.3 0.3

5X 5x 57 so 5s 53 SO 3x 45 43 42 .II

4161, 4161H: Hardness vs Tempering Temperature. sents an average

based

on a fully quenched

structure

Repre-

Alloy Steel / 339

4161 H: Hardenability

Curves. Heat-treating temperatures

(1600 “F). Austenitize:

845 “C (1555 “F)

iardness wrposes distance, Im .5

1 3 5 0 5 0 5 0 5 0

lardness iurposes distance. 16h.

0 1 2 3 4 5 6 8 0 2 4 6 8 0 7

limits for specification Earduess, Maximum

ERC Minimum

65 65 65 65 65 65 65 65 65 64 63 63 63 63 63

60 60 60 60 60 60 60 60 58 56 53 50 46 43 41

limits for specification Eardness, Maximum 65 65 65 65 65 65 65 65 65 65 65 64 64 64 64 64 64 63 63 63 63 63 63 63

HRC hliuimum 60 60 60 60 60 60 60 60 59 59 59 59 58 58 57 56 55 53 50 48 45 43 42 41

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

340 / Heat T

reater’s

4161RH: Hardenability “C (1800 “F). Austenitize:

Hardness purposes J distance, %6 in. 1 2 3 4 5 5 7 B 3 10 11 12 13 14 15 16 18 20 22 z4 26 28 30 32

Hardness purposes J distance,

‘/I6in. 1.5 3 5 7 9 11 13 15 20 25 30 35 40 45 50

Guide

Curves. Heat-treating 845 “C (1555 “F)

limits for specification Eardness. Maximum

HRC Minimum 60 60 60 60 60 60 60 60 60 60 60 59 59 59 58 57 56 54 53 51 49 47 46 45

65 65 65 65 65 65 65 65 65 65 65 64 64 64 63 63 62 62 61 60 59 58 57 57

limits for specification Hardness, Maximum 65 65 65 65 65 65 65 65 64 63 62 61 59 58 57

HRC Minimum

60 60 60 60 60 60 60 60 59 51 55 53 50 4-l 45

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870

Alloy Steel / 341

4320,4320H,

4320RH

Chemical Composition. 4320. AISI and UNS: 0.17 to 0.11 C. O.-Is too.65 h~n.0.035Pmax.0.O-l0Smax.0.15to0.30Si. 1.65to7.00Ni.0.-10 to 0.60 Cr. 0.20 to 0.30 MO. IJNS H43200 and SAE/AISI 4320H: 0. I7 to 0.23 C. 0.10 to 0.70 Mn. 0.15 IO 0.35 Si, 1.55 to 2.00 Ni. 0.35 to 0.65 Cr. 0.20 to 0.30 MO. SAE 4320RH: 0. I7 to 0.21 C. O.-IS to 0.65 hln. 0.15 to 0.35 Si, 1.65 to 2.00 Ni, O.-l0 to 0.60 Cr. 0.20 to 0.30 hlo Similar Steels (U.S. and/or Foreign).

4320. UNS G~3200: ASThl A322. A33 I, A505, ASl9. A535; SAE J1O-k. J-II?. J770.43208. UNS H13200; ASTM A30-L A9l-l; SAE J 1268. J IX68

Annealing. Not usually annealed for a pearlitic structure because machinahility is better \i hen the predominate structure is spheroidal carbide. This is best obtained by heating after normalizing (following forging or rolling). to 775 “C ( IQ5 “Fj. cooling rapidly to 650 “C (I300 “F). then holding for 8 h Tempering. Tempering of carburized or carhonitrided parts made from 1320H is always recommended. Tempering temperature should be at least I SO “C (300 “F). Somen hat higher tempering temperatures may be used if some hardness can be traded off for increased toughness Case Hardening.

Characteristics.

Used almost exclusively for carhurizing applications, notably heavy-duty. heavy-section pears. pi-tions. and related machinery components. Can be directlq hardened to 10 HRC or higher through relativeI) thick sections hecause of hiph hardenability. Use of -l330H. hoiiever. is far less errtensiLe \h hen compared with most other allo> carburizing steels because it costs more. and hecause its properties (relating mainly to hardenability) are not required for a maJority of applications. Forgeable and ueldable. but has relatively poor machinahilir).

Carburizing procedures are the same as those given for 31 I XH. -13XH can be carbonitrided, although this process is infrequently applied. Parts made from 1320H are not. as a rule. well suited to the carbonitriding process. If used. see carbonitriding procedure described for grade -II l8H. Gas carhuriring. ion nitriding, austempering. and martemperin~ are altematke processes

Recommended l l

Forging.

Heat to 17-15 “C. (2275 “F) maxmium. Do not forge after temperature of forging stock drops below approsimately 870 “C ( 1600 OF)

l l l

Recommended

Heat Treating

Practice

l l

Normalizing. 4320:

Heat to 925 “C ( 1695 “FL Cool in air

Carburizing,

Processing

Sequence

Forge Normalize Anneal Rough and semifinish machine Carburizc and harden Temper Finish machine (usually grinding. removing total case per side from critical areas)

no more than IO% of the

Single Heat Results

Specimens contained 0.20 C. 0.59 Mn, 0.021 P, 0.018 S, 0.25 Si, 1.77 Ni, 0.47 Cr, 0.23 MO; grain size was 6 to 8; critical 1350 “F (730 “C); AC,, 1485 “F (805 “C); Ar,, 1330 “F (720 “C); Ar,, 840 “F (450 “C); 0.565-in. (14.4-mm) round treated, round tested Elongation

case

Recommended practice

Hardness, ERC

in.

mm

60.5 62.5 62

0.060 0.075 0.075

I.52 1.91 1.91

217 218.3 151.75

I-196 I505 lo46

159.S I78 97

I loo 12’7 669

5X 5 59 59

0.060 0.07S O.07S

I .s2 I.91 I.91

215.5 211,s 115.75

I186 I-158 IOOS

158.75 173 91.S

1095 1193 652

Depth

Tensile strength ksi MPa

Yield point ksi hiPa

in2in. (50mm),

points Included AC,, 0.505-in. (12.8-mm)

Reduction ofarea,

I&lldlll?SS,

*

EB

13.0 13.5 19.5

so. I 48.2 49.-l

429 429 302

12.5 l2.S 21.8

19.J so.9 56.3

415 115 293

Q

For maximum case hardness Direct quench from pot(a) Single quench and rempert bl Double quench and tempertc~

For maximum core toughness Direct quench from pot(d) Smplr quench and temper(e) Double quench and tempert fl

(a~ Carburizcd at 1700 “F t925 “C) for 8 h. quenched in agitated oil. tempered at 300 “F ( I SO ‘T I. I b, Carburircd at I700 “F t92S “C I for 8 h. pot cooled. reheated to I500 OF (8 I5 “CL quenched in agitated oil. tempered at 300 “F t I50 T). Good case and core properties. ic) Carbunred at I700 “F t92.i “C) for 8 h. pot cooled. reheated to IS00 “F (815 “C), quenched inagitatedoil, reheated to 142YFt77S “C).qucnchrd inagitatrdoil. tempered at 3tW)“Fl ISOTI hlavirnum refinement ofcaseandcore. td)Carburizedat 17OO”F(925 ‘T) for 8 h. quenched in agitated oil. tempered at 1SO “F (130 “C). tr) Carburirrd at I700 ‘F (925 “C, ior 8 h. pot cooled. reheated to IS00 “F 18lS “C). quenched in agitated oil. tcmperedat150°Ft23t)“C~. Good cujemd core properties of) Carbutized at 17OO”Ft925 “CT) for8 h. pot cooled. reheated to lSOWFt8lS “C). quenched inagitatedoil. reheated to 1425 “F(775 “Ckquenchrd in agttatrd oil. temperedat -lSO”Ftl30”C~. hlaximum refinement ofcaseandcore. tsourcc: Bethlehem Steel)

4320: Surface Carbon Content after Carburizing. 25.4 mm

(1 tn.) diam bar, 26 tests. Carburized at 925 “C (1695 “F)using a diffusion cycle, quenched from 815 “C (1500 “F) in oil at 60 “C (140 “F), tempered at 650 “C (1200 “F). Dew point, -1 “C (30 “F) at discharge end. Desired carbon concentration, 0.85 0.05%

342 / Heat Treater’s Guide

4320H: End-Quench Hardenability Diitmce from quenched surface ‘/,6 in.

Eardness, ERC

mm

man

min

Dice Prom quenched surface ‘/la in. mm

Eardoess, ERC maw

I 2

I .58 3.16

48 47

?I 38

13 I-1

20.54 22.12

28 27

3

4.74 6.32 7.90 9.48 II.06 12.64 14.22 15.80 17.38 I&%

45 13 41 38 36 34 33 31 30 29

35 32 29 27 25 23 22 21 20 20

IS I6 18 20 22 2-l 26 28 30 32

23.70 25.28 28.4-l 31.60 34.76 37.92 41.08 44.2-l -+7.40 SO.56

27 26 25 25 24 2-t 2-l 2-l 24 24

4

5 6 7 8 9 IO II I2

4320: Effect of Prior Microstructure on Hardness after Tempering. Specimens tempered 2 h

4320, 4320H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure

4320:

As-Quenched Hardness

Specimens

were quenched

in oil.

Size round in.

mm

‘/2

I3 25 51 102

I 2 4 Source: Bethlehem

Steel

Surface 44.5 39 35 25

Eardness, HRC L/zradius 44.5 37 30 2-l

Center 44.5 36 27 23

Alloy Steel / 343

4320H: Hardenability Curves. Heat-treating (1700 “F). Austenitize:

hardness wrposes I distance, nm .5

1 3 5 !O !5 LO 15 lo 15 in

925 “C (1700 “F)

limits for specification Earduess, ERC Maximum Minimum 48 47 45 42 39 36 34 32 28 26

41 39 35 30 21 25 23 22

. ..

25 25 24 24 24

. ... ..

hardness limits for specification wrposes distance.

‘16io.

Eardness, HRC Mxximum Minimum 48 41 45 43 41 38 36 34 33 31 30 29 28 21 21 26 25 25 24 24 24 24 24

41 38 35 32 29 21 25 23 22 21 20 20

. .. .. . .

...

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 925 “C

344 / Heat Treater’s Guide

4320: CCT Diagram. Carburizing composition: 0.20 C, 0.28 Si, 0.57 Mn, 0.0113P. 0.022 S, 0.50 Cr, 1.83 Ni. 0.26 MO. Alaboratory, induction air melted heat; ingot was forged to 12.7 mm (0.5 in.) square bar stock heated at 925 “C (1700 “F) for 1 h and air cooled. Steel was austenitized for 20 min at 925 “C (1700 “F). Source: Datasheet l-57. Climax Molybdenum Company

Alloy Steel / 345

4320: Cooling Curve. Half cooling time. Source: Datasheet

l-57. Climax Molybdenum

Company

346 / Heat Treater’s Guide

4320RH: Hardenability Curves. Heat-treating temperatures “C (1700 “F). Austenitize:

925 “C (1700 “F)

Hardness limits for specification purposes J distance, 916in. 1 2 3 4 5 6 7 8 9 10 II 12 13 14 IS 16 18 20 22 24 26 28 30 32

Ehrdoess, ERC Maximum Minimum 47 46 44 41 39 36 34 32 31 29 28 26 25 24 24 23 22 22 II 21 21 21 21 21

42 40 37 34 31 29 27 25 23 23 22 21 20

Hardness limits for specification purposes J distance, null 1.5 3 5 1 9 II I3 IS 20 25 30 35 -lo 35 SO

Hardness, ERC Maximum Minimum 41 46 44 40 31 34 31 30 25 23 22 21 21 21 II

42 40 31 33 30 21 25 23 20

recommended

by SAE. Normalize (for forged or rolled specimens

only): 925

Alloy Steel / 347

4330v Chemical

COIIIpOSitiOn:

AISI

4330V. 0.30 C. I.80 Ni. 0.80 Cr. 0.30

MO. 0.07 V steel

Austenitizing.

Characteristics.

An aerospace grade steel (AMS 2759/l)

Recommended Normalizing.

Annealing.

Heat Treating Practice

Heat to 900 ‘22 (1650 “F)

Heat to 855 “c ( I 575 OF)

Temperature is 870 “C (1600 “F). Hardening quenchants are oils or polymers

Alloy Steel I347

4335v Chemical

Composition.

AISI 433SV.0.35C. I .80Ni.

MO. 0.2 V steel

Characteristics.

An aerospace grade steel (AMS

Recommended Normalizing.

Heat Treating

Heat to 900 “C ( I 650 “F)

2759/l)

Practice

0.72 Cr. 0.35

Annealing.

Heat to 845 “C ( 1555 ‘W

Austenitizing. Temperature chants are oils or polymers

is 870 “C (1600

“F),

Hardening

quen-

Alloy Steel I347

4340,434OH Chemical Composition. 4340. AISI and UNS: to0.80Mn.0.035 Pmax,0.040Smax.0.15to0.30Si, to 0.90 Cr. 0.20 to 0.30 MO. 4340H. AISI and UN!? too.95 Mn.0.025 Pmax.0.025S max.0.15 too.35 Si. to 0.95 Cr. 0.20 to 0.30 MO

0.38 to 0.43 C. 0.60 1.65to2.00Ni.0.70 0.37 to 0.44 C. 0.60 I.55 to2.00Ni.0.65

Similar

Steels (U.S. and/or Foreign). 4340. UNSG43-100: AMS 533 I, 6359.6413.64lS; ASTM A322. A33 I. A505, A5 19, A5-t7. A646: MJLSPEC hUL-S-16971; SAEJIO-L J-412. J770;(Ger.) DIN 1.656S:(Jap.) JIS SNCM 8; (U.K.) B.S. 817 M 40.31 I I Type 6.2 S 119.3 S 95. UJOH: UNS H43100; ASTM A3M; SAE 5407; (Ger.) DIN 1.6565: (Jap.) JIS SNCM 8; (U.K.) B.S. 817 M GO.31 I I Type 6.2 S 119.3 S 95 Characteristics. A high-hardenability steel, higher in hardenability than any other standard AlSl grade. When the elements that contribute to hardenability are on the high side of their allowable ranges, the upper curve of the hardenability band is virtually a straight line. thus indicating that 4340H would be ah-hardening in thin sections. Depending on the precise carbon content, as-quenched hardness ranges from 54 to 59 HRC. Because of high hardenability. 4340H is not considered suitable for welding by conventional means. although it can be welded by sophisticated processes such as electron beam welding. 434OH can be forged \rithout difftculty, although its hot strength is considerably higher than that of carbon or loher alloy grades, requiring more powerful forging machines. Machinability is relatively poor

Annealing.

For a predominately pearlitic structure (not usuaUy preferred for this grade). heat to 830 “C ( I525 “F), cool rapidly to 705 “C (I 300 “F), then to 565 “C ( 1050 “F) at a rate not to exceed 8 “C ( 15 “F) per h: or heat to 830 “C ( I525 “F), cool rapidly to 650 “C ( I200 “F). and hold for 8 h. For a predominately spheroidized structure. heat to 750 “C (1380 “F). cool rapidly to 705 “C ( I300 “F) then cool to 565 “C ( I050 “F) at a rate not to exceed 3 “C (5 “F) per h: or heat to 750 “C (I 380 “F). cool rapidly to 650 “C ( I200 “F). and hold for 12 h. A spheroidized structure is usually preferred for both machining and heat treating

Hardening. Austenitize at 815 “C (1555 “F). and quench in oil. Thin sections may be fully hardened by air cooling Tempering.

In common with all susceptible to quench cracking. Before to 50 “C. 100 to 120 “F), they should Tempering temperature depends upon of mechanical properties

Nitriding. Can be nitrided to produce high surface hardness and for increased fatigue strength. See processing procedure given for 414OH

Recommended l

Forging.

Heat to I230 “C (2250 “F). Do not forge after temperature of forging stock drops below approximately 900 “C (1650 “F). Slow cooling from forging is recommended to prevent the possibility of cracking

Recommended Normalizing.

Heat Treating

Practice

Heat to 870 “C ( 1600 “F). Cool in air

high-hardenability steels, 4340H is parts reach ambient temperature (38 be placed in the tempering furnace. the desired hardness or combination

l l l l l l

Processing

Forge Normalize Anneal Rough machine Austenitize, quench. and temper Finish machine Nitride (optional)

Sequence

348 / Heat Treater’s

Guide

4340: Isothermal Transformation Grain size: 7 to 8

Diagram.

Composition:

0.42 C. 0.78 Mn, 1.79 Ni, 0.80 Cr. 0.33 MO. Austenitized

at 845 “C (1555 “F).

4340: Cooling Transformation Diagram. Composition: 0.41 C. 0.87 Mn, 0.28 Si, 1.83 Ni, 0.72 Cr, 0.20 MO. Austenitized at 845 “C (1555 “F). Grain size: 7. AC,, 755 “C (1390 “F); AC,, 720 “C (1330 “F). A: austenite, F: ferrite, 8: bainite, M: martensite. Source: Bethlehem Steel

Alloy

Steel / 349

4340 + Si: End-Quench

Hardenability. Composition: 0.42 C, 0.83 Mn, 1.5 Si, 1.85 Ni, 0.90 Cr, 0.41 MO. Quenched from 845 “C (1555 “F). Source: Bethlehem Steel

4340: Tempered Hardness Versus Austenitizing Temperature and Section Size Specimens

Austenitizing temperature “F(“C) 1500(815)

were quenched

Section Size

ill.

mm

%

12.7 31.8 54 12.7 31.8 54 12.7 31.8 54

1 L/4 21/s 1550(845)

% 1 vi.4 21/8

1600 (870)

‘h 1% 2%

in oil. Aardness, ARC Tempered for 2 h at 400°F 6OO’F 8OO’F 1000°F 1200°F (205OC) (315OC) (125’C) (S-lO°C) (65OOC) 53.5 53.5 51.0 53.5 53.0 52.0 53.5 53.5 52.5

50.0 50.0

49.0 49.5 50.0 48.0 50.0 50.0 48.5

44.5 45.5

44.0 44.0 45.0 43.0 45.0 45.5

44.0

39.0

40.0 37.5 39.0 39.5 38.0

40.0 39.5 39.0

29.5 28.5 28.0 29.0 27.0 27.5 29.5 29.0 28.0

4340 + Si: Cooling Transformation Diagram. Composition: 0.43 C, 0.83 Mn, 1.55 Si, 1.84 Ni, 0.91 Cr, 0.40 MO, 0.12 V, 0.083 Al. Austenitized at 845 “C (1555 “F). Grain size: 8. AC,, 805 “C (1480 “F); AC,, 760 “C (1400 “F). A: austenite, F: ferrite, B: bainite, M: martensite. Source: Bethlehem Steel

350 / Heat Treater’s

Guide

4340H: End-Quench Hardenability Distance from quenched surface &in. mm I

2 3 4 5 6 7 8 9 10 II I?

1.58 3.16 4.74 6.32 7.90 9.48 Ii.06 12.64 14.22 15.80 17.38 IS.96

Ehrdoess, ERC max min

60 60 60 60 60 60 60 60 60 60 59 59

53 53 53 53 53 53 53 52 52 52 51 51

4340: End-Quench Hardenability.

Distance from quenched surface ‘116in. mm

13 14 15 16 18 20 22 21 26 28 30 32

20.5-i 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40 SO.56

Hardness. ERC max min

59 58 58 58 58 57 57 57 57 56 56 56

SO 49 49 48 37 46 45 4-I 43 42 41 40

Influence of initial structure and time at 845 “C (1555 “F). HR: hot rolled, N: normalized, A: annealed, S: spheroidized. (a) 0 min; (b) 10 min; (c) 40 min; (d) 4 h

4340: Hardness vs Tempering Temperature. Normalized at 870 “C (1800 “F), quenched from 845 “C (1555 “F), and tempered in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel

Alloy Steel / 351

4340: Hardness vs Diameter. 0.38 to 0.43 C, 0.80 to 0.80 Mn, 0.040Pmax,0.040Smax,0.20to0.35Si, 1.65to2.00Ni,0.70to 0.90 Cr. 0.20 to 0.30 MO. Approximate critical points: AC,, 725 “C (1335 “F); AC,. 775 “C (1425 “F); Ar,, 710°C (1310 “F); Ar,, 655 “C (1210 “F). Forge at 1230 “C (2250 “F) maximum; anneal at 595 to 660 “C (1105 to 1220 “F) for a maximum hardness of 223 HB; normalize at 845 to 900 “C (1555 to 1650 “F) for an approximate hardness of 415 HB; quench in oil from 830 to 855 “C (1525 to 1570 “F). Test specimens normalized at 870 “C (1600 “F) in over-sized rounds, quenched from 845 “C (1555 “F) in oil, tempered at 540 “C (1000 “F). Tested in 12.8 mm (0.505 in.) rounds. Tests from 38 mm (1.5 in.) diam bars and over are taken at half radius position. Source: Republic Steel

4340: Nitriding. 20 to 30% dissociation.

(a) 7 h. (b) 24 h. (c) 48 h

4340 + Si: Tensile Strength, Yield Strength Elongation, and Reduction in Area. Composition: 0.43 C, 0.83 Mn, 1.55 Si, 1.84 Ni. 0.91 Cr, 0.40 MO, 0.12 V. 0.083 Al. Normalized at 900 “C (1650 “F), austenitized at 855 “C (1570 “F), quenched in agitated oil, tempered for 1 h. Source: Bethlehem Steel

352 / Heat Treater’s

Guide

4340: Gas Nitriding. Two tests. Nitrided at 550 “C (1020 “F) for 20 h, 20 to 509’0 dissociation

4340: Hardness vs Diameter. Composition:

0.38 to 0.43 C, 0.60 to0.80Mn,0.040Pmax,0.040Smax,0.20to0.35Si, 1.65t02.00 Ni, 0.70 to 0.90 Cr, 0.20 to 0.30 MO. Approximate critical points: Ac,,725”C(1335”F);Ac,,775”C(1425”F);Ar,,710”C(1310”F); Ar,, 655 “C (1210 “F). Recommended thermal treatment: forge at 1230 “C (2250 “F) maximum; anneal at 595 to 660 “C (1105 to 1220 “F) for a maximum hardness of 223 HB; normalize at 845 to 900 “C (1555 to 1650 “F) for an approximate hardness of 415 HB; quench in oil from 830 to 855 “C (1525 to 1570 “F). Test specimens normalized at 870 “C (1600 “F) in over-sized rounds, quenched from 845 “C (1555 “F) in oil, tempered at 650 “C (1200 “F). Tested in 12.8 mm (0.505 in.) rounds. Tests from 38 mm (1 l/z in.) diam bars and over are taken at half radius position. Source: Republic Steel

4340: Effect of Nitriding and Shot Peening on Fatigue Behavior. Comparison between fatigue limits of crankshafts (S-N bands) and fatigue limits for separate test bars, indicated by plotted points at right

4340: Microstructure.

2% nital, 500x. Quenched in oil from 845 “C (1555 “F) and tempered at 315 “C (600 “F). Tempered martensite

Alloy Steel / 353

E4340,

E4340H

Chemical Composition.

E-4340.AISI and ZJNS:0.38 to

O.-i3

c.

0.65 to 0.85 Mn. 0.025 P max. 0.025 S max. 0.15 to 0.30 Si. I.65 to ?.OO Ni,

0.70to 0.9OCr.O.20

100.30

MO.E434OH.AlSIaod UNS:0.37IOO.-U

C. 0.60 to 0.95 Mn. 0.025 Pmax. 0.035 S max. 0. IS to 0.30 Si. I.55 to X0 Ni. 0.65 to 0.95 Cr. 0.20 to 0.30 MO

Similar Steels (U.S. and/or Foreign). U340. ASThl A33l. A5OS. ASl9: MIL SPEC (Ger.) DIN I .6563: tJap.) JIS 40 NiCrMo Type 8. S 139. EXMOH.UNS H43406; DIN 1.6563: (Ital.) UNI 10 NiCrhlo 7,40

UNS

Gw06;

hlfL-S-5000; SAE J-W. 5770; 7. -tO NiCrMo 7 KB; (11.K.) B.S. ASThl 430-k SAE 5407: (Ger.) NiCrhlo 7 KB: (U.K.) B.S. Type

8. S 139

Characteristics. Basically a prenuum grade of 4330H. Prescribed composition carries lower maximums for hoth phosphorus and sulfur. Manganese range IS slightly higher. but this IS of little practical sipnificance. Hardennhility and other properties are the same as for conventtonal 4310H. Weldability and machinability are poor; forgeability is good. Asquenched hardness. 5-l to 59 HRC Forging.

Heat to 1230 “C t 1750 “FL Do not forge after temperature of forging stock drops helo\.r approximately 900 “C ( 1650 ‘F). Slou cooling from forging is recommended to prevent the possibility of crnching

“F). then to 565 “C t 1050 “F) at a rate not to exceed 8 “C (15 “F) per h; or heat to 830 “C ( I525 “F). cool rapidly to 650 “C ( 1300 “F), and hold for 8 h. For a predominately sphcroidized structure, heat to 7.50 “C (I 380 “F). cool rapidly to 705 ‘C (I300 “F), then to 565 “C (1050 “F) at a rate not to exceed 3 “C (5 “F) per h; or heat to 750 “C (I 380 “F), cool rapidly to 650 “C ( I200 ;F). and hold for I:! h. A spheroidized structure is usually preferred. for hoth machining and heat treating

Hardening. Austenitire at 835 “C ( IS55 “F), and quench in oil. Thin sections may be fully hardened hy air cooling Tempering.

These steels. in common with all high-hardenahility steels, are susceptible to quench crackin_e. Before parts reach ambient temperature (38 to 19 “C. or 100 to I20 OF). they should be placed in the tempering furnace. Tempering temperature depends upon the desired hardness or comhinatton of mechanical properties

Nitriding. Can he nitrided to produce high surface hardness and to increase fatigue strength. See processing procedure given for 1140H Recommended l l

Recommended Heat Treating Practice Normalizing. Heat to 870 “C (I600 “F). Cool in air Annealing. For a predominately pearlittc structure

(not usually preferred for this grade). heat to 830 “C t IS75 “F). cool rapidly to 705 “C ( I300

l l l l l

Processing

Sequence

Forge Normalize Anneal Rough machine Austenitize. quench. and temper Finish machine Nitride (optional)

E4340, E434OH: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure

354 / Heat Treater’s

Guide

E434OH: Hardenability

Curves. Heat-treating

870°C (1800 “F). Austenitize:

Hardness wrposes I distance,

nnl 1.5

i 3 II 13 15 !O !5 IO 15 lo IS i0

iardness wrposes I distance, 46h.

limits for specification Hardness, HRC MtlXhllUll Minimum 60 60 60 60 60 60 60 60 60 59 58 58 57 57 57

1 0 I 2 3 4 5 6 8 !O !2 !3 16 18 IO 2

53 53 53 53 53 53 53 53 52 51 SO 49 47 46 44

limits for specification Hardness, HRC Maximum Minimum 60 60

i

845 “C (1555 “F)

60 60 60 60 60 60 60 60 60 60 60 59 59 59 58 58 58 57 51 51 51 51

53 53 53 53 53 53 53 53 53 53 53 52 52 52 5’ i; 51 SO 49 18 47 46 4s 4-t

temperatures

recommended

by SAE. Normalize

(for forged or rolled specimens

only):

Alloy Steel I355

4615 Chemical Composition.

4615.AISI and UNS: 0. I 3 IO 0.18 c. 0.45

to0.65Mn.0.035Pmax.0.040Smax.0.15 to 0.30 MO

to0.30Si.

1.65 to2.00Ni.0.20

Similar Steels (U.S. and/or Foreign). 4142. UNS G16150; AMS 6290; ASTM A322, A331, A505: MIL SPEC MU-S-7493; SAE J404, 13 12, J770. This steel is no longer in SAE 5-W or J 4 12, but does appear in SAE J770. which is now J1397

Characteristics.

Used extensively for making parts that will be case hardened by carburizing or carbonitriding. Over a period of years, however, use has declined in favor of carburizing grades that have slightly higher carbon (for better core properties), lower nickel content. or both. Asquenched surface hardness (not carburized) can be expected to be approximately 35 to 40 HRC. and the hardenability band should be nearly the same general pattern as the one for 4620H. No AISI hardenability band for 4615. The slight difference in range of nickel content for 4615 and 4620H is not signiticant. Grade 4615 forges easily and is weldable. although alloy steel practice, in terms of preheating and postheating, should be used

Recommended Normalizing.

Heat to 1245 “C (2275 “F) maximum. Do not forge after temperature of forging stock drops below approximately 900 “C ( I650 “F)

4615: Carbon Gradients 4615 mod (cast), slight differences same carburizing

Produced

by Liquid Carburizing.

carburized at 925 “C (1695 “F) for 7 h. Indicates in gradients obtained in two furnaces using the conditions

4615: Hardness vs Tempering Temperature. average

based

on a fully quenched

structure

Heat to 925 “C (1695 OF). Cool in air

Case Hardening. See recommended carburizing, carbonitriding, and tempering procedures described for 4 I I8H. Flame hardening, liquid carburizing, austempering and martempering are alternative treatment processes

Recommended l l l l

l l

Processing

an

Sequence

Forge Normalize Anneal (optional) Rough and semifinish machine Case harden Temper Finish machine (carburized parts only)

4615: End-Quench

Hardenability.

Mn, 1.90 Ni, 0.24 MO. Austenitized

4615: Liquid Carburizing. Represents

Practice

Annealing. Not usually required for this grade. Structures that are well suited to machining are generally obtained by normalizing or by isothermal annealing after rolling or forging. Isothermal annealing may be accomplished by heating to 700 “C ( 1290 “F) and holding for 8 h

l

Forging.

Heat Treating

tests

Composition: 0.15 C, 0.63 at 925 “C (1695 “F). Grain size: 6

Case

hardness

gradients

after

10

356 / Heat Treater’s

Guide

4615: Carbon Gradients After Carburizing. (a) Carburized for 4 h at 870 “C (1600 “F); (b) Carburized for 4 h at 925 “C (1695 “F)

4615: Depth of Case vs Time and Temperature. 25 mm (1 in.) round bars, carburized at 925 “C (1695 “F), oil quenched

4615: isothermal Transformation Diagram. Composition: 0.15 C. 0.63 Mn. 1.90 Ni, 0.24 MO. Austenitized at 925 “C (1695 “F). Grain size: 8

356 / Heat Treater’s

Guide

4620,4620H,

4620RH

Chemical COIIIpOSitiOn. 1620. AIS1 and UN% 0.17 to 0.22 C. 0.15 too.65 Mn.0.035 Pmax.0.040Smax,0.15 ro0.30Si. 1.65 to3.00Ni.0.20 to 0.30 Mo. UNS A46200 and SAE/AISI 4620H: 0.17 to 0.23 C. 0.35 to 0.75 Mn. 0.15 to 0.35 Si, I.55 to 2.00 Ni. 0.20 to 0.30 hlo. SAE 4620RH: 0.17 to 0.22 C. 0.45 to 0.65 hln. 0. IS to 0.35 Si, I.65 to 2.00 Ni. 0.20 to 0.30 MO Similar

Steels (U.S. and/or

Foreign).

294; ASTM A322, A33 I, ASOS, AS35; hlfLSPEC J4 12. J770.4620H.

UNS H46200; ASTM

A304

4620. UNS G46WO; AhlS MU-S-7493; SAEJ10-I. A9 I-l; SAE J 1268. J I868

Characteristics. lrsed eswnsivel) for carburiring. Because of relativelj high nickel content. it has hern replaced in some areas with lower nickel alloys that have been developed and have hardenability and other properties equal to those of 462OH. Depending on the precise carbon content within the allouabls range. as-quenched hardness without carburizinp ranges betueen approsimately 40 to 35 HFX. Has a reasonably high hardenabilit!. Because of the relatwely high nickel content. 4620H is srronglq susceptible to retention of austenite. While retained auslenite is usually considered as an undesirahls constituent. some specific applications exist 1%here retained austenire has proved to be an advantage

Alloy Steel / 357 Forging. forging

Heat to 1245 “C (X75 “F). Do not forge after temperature stock drops helow approximateI> 815 “C (IS55 “F)

Recommended Normalizing.

Heat Treating

of

tempering procedures described pering are alternative processes

Recommended

Practice

l

Heat to 915 “C ( 1695 “F). Cool in air

l

Annealing.

Structures with best machinabilib are de\elopsd by normalizing or by isothermal transformation after rolling or forginp. Commonly used isothermal practice consists of heating to 775 ‘C (1415 “F). cooling rapidly to 650 ‘C ( I300 “F). and holding for 6 h

l

Hardening.

l

Seldom subjected to hardening treatments except carburizing and carbonitriding. See recommended carburizing. carboniu-iding. and

4620:

Carburizing,

l l l

for 41 l8H. Flame hardening

Processing

and martem-

Sequence

Forge Nomlalize Anneal (optional) Rough and semifinish machine Case harden Temper Finish machine (carburized parts only)

Single Heat Results

Specimens contained 0.17 C, 0.52 Mn, 0.017 P, 0.016 S, 0.26 Si, 1.81 Ni, 0.10 Cr, 0.21 MO; grain size 6 to 8; critical points included AC,, 1300 “F (705 “C); AC,, 1490 “F (810 “C); Ar,, 1335 “F (725 “C); Ar,, 1220 “F (660 “C); 0.565-in. (14.4-mm) round treated, 0.505-in. (12.8-mm) round tested Core properties Case Recommended practice

Elongation

Depth

Tensile strength ksi hlPa

Ill.

6’ S 62

0.07.5 0.060

.91 52

119.25 I22

822.2 811

83.5 77.25

576 532.6

19.5 72.0

59.1 55.7

277 248

58 5 59 59

0.060 0.065 0 MO

57 .6S .65

147.5 I IS.5 I IS.25

1017 796.3 794.63

I IS.75 80.75 77

798.07 556.8 531

16.8 70.5 22.5

57.9 63.6 62.1

302 318 235

mm

b’ield point ksi hIPa

Reduction Ofare& (SOmm), % 5%

Hardness, HRC

in2in.

Hardness, EIB

For maximum case hardness Direct ouench from rot(u)

Single &ench and &per(b) Double quench and temper(c)

For maximum core toughness Direct quench fmm pot(d) Single quench and temper(r) Double quench and temper(f)

(a) Carburizzd at 1700°F (925 TI for 8 h, quenched in agitated oil, tempered at 300 “F I I SO “C) 1.b) Carburized at 1700 “F (925 “C I for 8 h pot cooled. reheated to IS00 “F (815 “CJ. quenched in agitated oil, tempered at 300 “F ( 150 “CL Good case and core properties. tc) Carburizcd at I700 ‘,F 1925 “C) for 8 h. pal cooled, reheated IO IS25 “F (830 “C). quenchrdinagitatedoil.rehestedto 1175”Fi800”C).quenchcdinagiraredoil. temperedat “Ft 150°C) hlsaimumrefinemcntofcclseandcore.(d)Carburizcdat 17OO”F(925 “C). quenched in agitatedoil. tempered at -IS0 “Ft230”C) Ir) Carburircdat 1700 “Ft925 “C). pot cooled. reheated to IS00 “F18lS ‘CL quenched in agitatedoil, temperedatJS0 “F(23O”C). Goodcasesndcore propenies. (fl Carburircd at 1700 “Fi92S “C) for 8 h. pot cooled, reheated to IS25 “Ft830 “CL quenched in agitatedoil, reheated to 1175 “F(800 T). quenched in agitated oil. tempered at -IS0 “F (230 “C ). (Source: Bethlehem Steel 1

4620H: End-Quench Hardenability Distance loom quenched surface ‘/,b in. mm

Hardness, HRC min max

Distance from quenched surface &in. mm

Hardness, HRC may

I

I.58

48

-II

I3

20.54

12

1 -I 5 6 7

3.16 4.74 6.32 7.90 9.48 ll.c6

J5 -II 39 3-I 31 29

3s 27 2-l 21

I4 IS I6 I8 20 2’

21.12 23.70 ‘5 ‘8 5s:; 3160 31.76

22 22 ‘I 21 20

8 9 IO II I2

12.6-I I-l.22 15.80 17.38 18.96

27 26 2s 2-l 23

24 26 33 30 32

37.92 41 08 44.21 47.40 SO.56

3

358 / Heat Treater’s

Guide

4620H: Effects of Carburizing 63 HRC

and Quenching

Methods

on Dimensions.

Gears, carburized

0.762 to 1.02 mm (0.030 to 0.040 in.), 58 to

Specimens 19 mm 4620: Liquid Carburizing. (.75 in.) diam by 51 mm (2 in.), carburized, air cooled, reheated in neutral salt at 845 “C (1555 “F), quenched in salt at 180 “C (360 “F). (a) Carburized at 870 “C (1600 “F); (b) Carburized at 900 “C (1650 “F); (c) Carburized at 925 “C (1695 “F)

4620: Range of Surface Carbon vs Position in Furnace. Bearing races, carburized in a pit furnace 762 mm (30 in.) in diameter by 914 mm (36 in.) deep. Open load of races was carburized for 7 h in natural gas atmosphere; 3 92 h diffusion cycle followed. Surface carbon aim was 1 .OO%. Each bar represents 14 heats of steel

Alloy

4630:

As-Quenched

Specimens

Hardness

4620, 4620H: Hardness vs Tempering Temperature. sents an average based on a fully quenched structure

quenched in oil

Repre-

HWdIlt?SS

Size round in.

mm

Surface

‘/* radius

Center

‘/:

13 25 Sl 102

40 HRC 21 HRC 23 HRC % HRB

32 HRC 99 HRB 91 HRB 91 HRB

31 HRC 97 HRB 9ZHRB 88 HRB

I 2 -l

Steel / 359

Source: Bethlehem Steel

4620: CCT Diagram. Chemical composition: 0.20 C, 0.49 Mn, 0.016 P. 0.022 S, 0.23 Si, 1.76 Ni. 0.25 MO, 0.076 Al. A laboratory induction air melted heat. Specimens 4 mm (0.16 in.) in diameter were through-carburtzed to various carbon levels by holding in a carburizing atmosphere at 1150 “C (2100 “F) for 16 to 20 h. Machined dilatometer specimens [3 mm (0.116 in. )] in diameter were austenitized and cooled at three different rates to define the partial CCT diagram at each carbon level. Cooling rates ranged from 357 to 3280 “C (675 to 5900 “F) per min. The cooling curves used to define the diagrams are not shown. Instead, the cooling curves shown were measured on impact-fracture specimens (gear tooth simulation) at locations corresponding to the surface and the case-core interface during quenching in warm oil [66 “C (150 “F)] or in hot oil [170 “C (340 “F). Specimens were austenitized at 900 “C (1650 “F) for 20 min. The objectives of the study were to obtain partial kinetic data on continuous-cooling transformation at various carbon levels in the carburized case. Hardness values (in circles on the diagram) were exhibited by specimens of each carbon level subjected to the fastest cooling rate used to define each CCT diagram. Source: Datasheet l-262, Climax Molybdenum Company

360 / Heat Treater’s

Guide

4620: Microstructures. (a) Nital, 1000x. Gas carburized at 1.000/b carbon potential for 8 h at 940 “C (1725 “F), oil quenched, heated to 820 “C (1510 “F), oil quenched, tempered 1 h at 180 “C (355 “F), retempered 2 h at 260 “C (500 “F). Composition: 0.95 C. Retained austenite (by x-ray), tempered martensite, lower bainite. carbide. (b) Nital, 1000x. Gas carburized and heat treated before tempering under same conditions as (a), but tempered 1 h at 180 “C (355 “F) and retempered 2 h at 230 “C (450 “F). 10% retained austenite (by x-ray), tempered martensite, lower bainite. dispersed carbide particles. (c) Nital, 1000x. Gas carburized and heat treated before tempering under same conditions as (a) and (b), but tempered 1 h at 180 “C (355 “F) and retempered 2 h at 220 “C (425 “F). Composition: 0.95 C. 20% retained austenite (by x-ray), tempered martensite, lower bainite, carbide. (d) Nital, 1000x. Gas carburized at 1 .OO% carbon potential for 4 h at 940 “C (1725 “F), oil quenched, and tempered for 1 h at 180 “C (355 “F). Composition: 0.90 C. 35% retained austenite (by x-ray), and tempered martensite. (e) Nital, 1000x. Gas carburized at 1.00% carbon potential for 8 h at 940 “C (1725 “F), oil quenched, heated to 820 “C (1510 “F) for 30 min. oil quenched, tempered 20 min at 94 “C (200 “F). Composition: 0.95 C. 40% retained austenite (by x-ray), and tempered martensite. (f) Nital, 1000x. Gas carburized at 1.00% carbon potential for 8 h at 940 “C (1725 “F), oil quenched, and tempered for 1 h at 180 “C (355 “F). Composition: 0.95 C. 45% retained austenite (by x-ray), and tempered martensite.

Alloy Steel / 361

4620H: Hardenability

Curves. Heat-treating

(1700 “F). Austenitize:

925 “C (1700 “F)

iardness w-poses I distance, nm

1.5 3 5 7 1 11 13 15 20 25 30 35

Hardness purposes I distance, V,6 ill.

1 2 3 4 5 6 I 8 9 10 11 12 13 14 15 16 18 20 22

limits for specification Hardness,

hlanimum

HRC hlinimum

48 46 42 37 33 30 27 26 23 22 21

41 31 28 23 . .. ..

limits for specification Hardness, MaGmum

48 45 42 39 34 31 29 27 26 25 24 23 22 22 22 21 21 20

ARC hlinimum

41 35 27 24 21

... . . .

temperatures

recommended

by SAE. Normalize (for forged or roiled specimens

only): 925 “C

1

362 / Heat Treater’s

Guide

4626,4626H Chemical COIIIpOSitiOn. 4626. AISI and UN!%: 0.2-l to 0.29 C. 0.45 to0.65Mn,0.035Pmax,0.040Smax,0.15to0.30Si,0.70to l.00Ni.0.15 to0.25Mo.4626E.AISIaodUNS:0.23to0.29C,0.40to0.70Mn,0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.65 to I .05 Ni. 0.15 to 0.25 MO G46260; UNS Steels (U.S. and/or Foreign). 4626. ASTM A322. A33 I; SAE 5404.5412. J770.46268. UNS H-16260; ASTM A304 This steel is no longer in SAE 5404 or J3 12. but does appear in SAE 5770. which is now J I397

Annealing.

Best structures for machining are obtained either by normalizing or by isothermal treatment after rolling or forging. Isothermal treatment is accomplished by heating to 815 “C (1500 “F). cooling rapidly to 675 “C ( I235 “F). and holding for 8 h

Similar

Characteristics.

Usually used for carburizing or carbonitriding applications, although because of the as-quenched hardness of approximately 43 to 48 HRC that can be developed, it is sometimes used for parts that require strength and toughness without case hardening. To save energy. 4626H is sometimes used rather than lower carbon steels for carburizing. because the harder cores provided by 4626H often permit thinner cases. decreasing the required carburizing time. The hardenability of 4626H is slightly lower than shown for 4620H. because of the lower alloy content of 4626H. Can be welded, but alloy steel practice must be used

Direct Hardening. Tempering.

Temper to at least 205 “C (100 OF) and preferably some loss of hardness can be tolerated

Case Hardening. tempering

Forging.

Heat to 1230 “C (2250 “F) maximum. Do not forge after of forging stock drops below approximately 870 “C ( 1600 “F)

Recommended Normalizing.

Heat Treating

l

I 2 3 4 5 6 7 8 9 IO II I2

I S8 3.16 4.74 6.32 7.90 9.48 II.06 12.6-I I-t.22 15.80 Il.38

18.96

l

See recommended carburizing, described for 41 l8H

Processing

higher if

carbonitriding.

Sequence

Forge Normalize Anneal (optional) Rough and semifinish machine Case harden or direct harden Temper Finish machine (carburized parts only)

Hardenability

Distance from quenched surface &III. mm

l

l

Heat to 900 “C (1650 “F). Cool in air

4626H: End-Quench

l

l

Practice

procedures

Recommended l

temperature

Heat to 870 “C (1600 “F) and quench in oil. Caris a suitable hardening process

bonitriding

Eardness, ERC min max 51 38 41 33 29 27 25 24 23 22 22 21

4s 36 29 24 II

Distance from quenched surface ‘/,a in. mm I3 IJ IS I6 I8 20 22 ‘4 26

20.5-l

22.12 23.10 25.28 28.44 31.60 3-1.16 31.92 AI.08

Ehl-dlleSS,

HRC max 21 20 .._ .._

4626, 4626H: sents an average

Hardness based

vs Tempering

Temperature.

on a fully quenched

structure

Repre-

and

Alloy

4626H: Hardenability

Curves. Heat-treating

(1700 “F). Austenitize:

925 “C (1700 “F)

iardness wrposes I distance, om ._5 /

, I b I 3 5 !O !5

iardness wrposes I distance, 116i”. I , I I i i

I I ) IO II 12 13 l-1 IS

limits for specification Eardness, ERC Maximum Minimum 51

45

48 38 31 27 25 2-l 23 21

36 29 23 20

limits for specification Aardness, ERC Maximum Minimum 51 48 41 33 29 27 ‘5 24 23 22 22 21 21 20

4s 36 29 24 21

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

Steel I363

only): 925 “C

364 / Heat Treater’s

Guide

4718H Chemical COI?IpOSitiOn. UNS H47180 and SAE/AISI 47188: 0. IS to 0.21 C. 0.60 to 0.95 MN, 0.15 to 0.35 Si. 0.85 to 1.25 Ni. 0.30 to 0.60 Cr. 0.30 to 0.40 Mo

4718H: Hardenability

Curves. Heat-treating 925 “C (1700 “F)

(1700 “F). Austenitize:

temperatures

Similar

Steels (U.S. and/or

Foreign).

to SAE J I268 and will appear in ASTM

recommended

This steel has heen added

A301

by SAE. Normalize (for forged or rolled specimens

only): 925 “C

Hardness limits for specification 3urposes I distance, q m

.5

Hardness, HRC hlinlmum Maximum 47 47 46 43 39 36

34 32 29 27 26 26 2s 25 24

40 40 38 31 28 25 23 22 21 20

(continued)

Alloy Steel I365

4718H: Hardenability

Curves. (continued) Heat-treating

only): 925 “C (1700 “F). Austenitize:

Hardness purposes J distance, %6 ill. I 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 18 20 22 24 26 28 30 32

925 “C (1700 “F)

limits for specification Hardness, HRC Maximum blinimum 47 47 45 43 40 37 35 33 32 31 30 29 29 28 27 27 27 26 26 25 25 24 24 24

40 40

38 33 29 27 25 24 23 22 22 21 21 21 20 20

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

366 / Heat Treater’s Guide

4720,472OH Chemical Composition.

4720.

AI!31

and UNS: 0.17 IO 0.22 C. 0.50

to0.70Mn.0.035Pmax.0.040Smax.0.15to0.30Si.0.90to l.10Ni.0.35 to 0.55 Cr. 0.15 to 0.25 MO. UNS 847200 and SAE/AISI 47208: 0. I7 to 0.23 C. 0.45 to 0.75 Mn. 0.15 to 0.35 Si. 0.85 to 1.25 Ni. 0.30 to 0.60 Cr, 0.15 too.25 MO

Similar Steels (U.S. and/or Foreign). 4720.

UNS

ASTM A274. A322. A331. A5 19, A535; SAE J404, J412,5770. UNS H47200; ASTM A304; SAE J I268

G472OO; 4720H.

Characteristics. Essentially the same as those for 4620H. The lesser nickel content of 4720H is compensated for by a chromium addition. As a result, hardenability for the two steels is nearly the same. As-quenched hardness of approximately 40 to 45 HRC is also the same. Because of the lower nickel content and the chromium addition, the tendency of 4720H to retain austenite in carburized cases is less than for 4620H. In many instances, 4720H has replaced 4620H as a carburizing steel

Recommended Normalizing.

Heat to 1230 “C (2250 “F) maximum. Do not forge after temperature of forging stock drops below approximately 845 “C ( I555 “F)

Practice

Heat to 925 “C ( 1695 “F). Cool in air

Annealing.

Best structures for machining are obtained either by normalizing or by isothermal treatment consisting of heating to 815 “C (1500 “F), cooling rapidly to 650 “C ( I300 “F). and holding for 8 h

Case Hardening. tempering

procedures

Recommended l l l l l

Forging.

Heat Treating

l l

See recommended carburizing, described for 4 I I8H

Processing

carbonitriding,

Sequence

Forge Normalize Anneal (optional) Rough and semifinish machine Case harden Temper Finish machine (carburized parts only)

4720H: End-Quench Hardenability Diicefrom quenched surface l/,/16in. mm I

2 3 4 5 6 7 8

9 IO II I2

I .58 3.16 4.14 6.32 7.90 9.48 II.06 12.6-l 14.22 IS.80 17.38 18.96

Flardoess, ERC max min 48 41 33 39 35 33 29 28 27 26 25 24

41 39 31 37 23 21

:::

Distance from quenched surface ‘/,a in. mm 13 I-l IS I6 18 20 22 2-l 26 28 30 32

20.54 22.12 23.70 25.28 28.44 31.60 33.76 31.92 41.08 44.24 47.40 SO.S6

Eardness, ARC max 2-l 23 23 22 21 21 21 20

4720, 4720H: Hardness vs Tempering Temperature. Represents an average

based

on a fully quenched

structure

and

Alloy Steel / 367

4720H: Hardenability

Curves. Heat-treating

(1700 “F). Austenitize:

925 “C (1700 “F)

Hardness wrposes I distance, nm 1.5

limits for specification Aardness, HRC Maximum Minimum 48 47 43 38 33 30 28 27 2-l 23 22 21 20

41 39 32 75 22 20

..

Hardness limits for specification xuposes I distance, 116in.

I 3 IQ II I2 13 1-I IS 16 18 !O !? !1 !6

Elardness, ERC Maximum Minimum 48 4-I 43 39 35 32 29 28 27 26 25 2-l 2-I 23 23 22 21 ‘I ?-I 20

41 39 31

27 23 21

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 925 “C

1

366 / Heat Treater’s

Guide

4815,4815H Chemical

Composition.

4815. AIM and UNS: 0. I3 to 0. I8 C. 0.40

Annealing.

to0.60Mn,0.03SPmax.0.~0Smax.0.lSto0.30Si.3.35to3.7SNi.0.20 to 0.30 MO. UNS H-t8150 and SAE/AISI 4815H: 0. I2 to 0. I8 C. 0.30 to 0.70 hln. 0.15 to 0.35 Si. 3.20 to 3.80 Ni. 0.20 to 0.30 MO

After normalizing, heat to 650 ‘C (1200 “F), hold for I h per inch of section thickness. Cooling rate from this temperature is not critical. hlay also be isothermally annealed by heating to 745 “C (1370 “Fj. cooling rapidly to 605 “C (I I25 “F), and holding for 8 h

Similar

Tempering.

ASThl ASThl

Steels (U.S. and/or

Foreign).

4815.

A322. A33 I. ASOS: SAE J-IO-I. J-t I2.J770.4815I-l. A304 SAE J 1268

G48 I SO; UNS UNS H-18 I SO:

Characteristics. Represents a relatively high alloy carburizing grade intended for use where sections are thick and relatively hard. and tough cores are mandatory. Depending on the precise carbon content. asquenched hardness should be approximately: 35 to 42 HRC. Hardenability is relatively high. As is true for other htgh-nickel carburizing steels. austenite may be retained in the carburized case. Amenable to welding. but alloy steel practice of preheating and postheating must be used Forging. forging

Heat to 1245 “C 12275 “Ft. Do not forge after temperature stock drops below approxtmately 815 “C (15% “Ft

Recommended

Heat Treating

Practice

of

All parts made from this grade should he tempered at I50 “C (300 “F) or higher if some loss of hardness can be tolerated. Tempering ~bill help in transforming retained austenite

case Hardening. See carburizing process described for 31 l8H. This grade is rarely subjected to carbonmiding. Liquid carburizing. gas carburizing, and martempering are suitable processes

Recommended l l

Anneal

l

Rough and semifinish machine Case harden Temper Finish machine ccarburized parts only)

l

Heat to 925 “C (I695 “Fj. Cool in air

l

Sequence

Forge Normalize

l

l

Normalizing.

Processing

4815: Continuous Cooling Curves. Composition: 0.14 C. 0.45 Mn, 0.22 Si, 3.42 Ni, 0.21 MO. Austenitized at 925 “C (1695 “F). Grain size: 9. AC,, 800 “C (1475 “F); AC,, 730 “C (1350 “F). A: austenite, F: ferrite, B: bainite, M: martensite. Source: Bethlehem Steel

4815: Liquid Carburizing. Pinion liquid carburized at 900 “C (1650 “F) for 2.5 h. quenched in still oil, tempered at 205 “C (400 “F) for 0.5 h. Hardness, 58 to 60 HRC. 12 tests done to measure runout

Alloy Steel I369

4815: ZOIllZ

Carbon Gradients Temperature “F OC

4815: Isothermal Transformation

Atmosphere

Tiiein zone, h

Carbon potential, %,C

Cycle l(a) 1 2 3

1690 1690 1670

920 920 910

Methane Methane Carrier gas, air

8 14 13

1.25 1.25 0.80(b), 0.55(c)

Cycle 2(d) 1 2 3

1690 1690 1670

920 920 910

Methane Methane Carrier gas. air

6 10 9

1.25 1.25 0.80(b), 0.60(c)

Cycle 3(e) 1 2 3

1690 1690 1670

920 920 910

Methane Methane Carrier gas, air

4 7 6

1.25 1.25 0.80(b), 0.75(c)

Diagram. Carburized, 1 .O% carbon. Composition: 0.97 C, 0.52 Mn, 3.36 Ni, 0.19 MO. Austenitized at 980 “C (1795 “F). Grain size: 7

(a) Target, 0.1 IO-in. (2.79-mm) case at 0.25% C. (b) At center of fone. (c) At discharge. (d) Target, 0.~in. (2.29-mm) at 0.25% C. (e) Target. 0.070-m. (1.78-mm) case at 0.25% C

4815: Carbon Gradients. From three-zone

continuous pushertype carburizing furnace. Carbon potential was controlled manually. A: Cycle 1, 35 h; 0: Cycle 2, 25 h; 0: Cycle 3, 17 h

4815: End-Quench

Hardenability.

Mn, 3.36 Ni. 0.19 MO. Austenitized 8 to 9

Composition: 0.16 C, 0.52 at 900 “C (1650 “F). Grain size:

4815: End-Quench

Hardenability. Carburized, 1 .O% carbon. Composition: 0.97 C, 0.52 Mn, 3.36 Ni, 0.19 MO. Austenitized at 980 “C (1795 “F). Grain size: 7

4815, 4815H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure

370 / Heat Treater’s

I 2 3 4 5 6 7 8 9 IO II I2

I .xX 3.16 4.74 6.32 7.90 9.48 I I .06 12.64 14.22 15.80 17.38 18.%

Guide

45 4-l 44 42 41 39 37 35 33 31 30 29

38 37 31 30 27 24 22 21 20

I3 l-l IS I6 I8 20 22 24 26 28 30 32

20.54 22.12 23.70 25.28 28.44 31.60 34.76 31.92 41.08 44.2-l 47.40 50.56

28 28 27 27 26 25 24 24 2-l 23 23 23

4815: Depth of Case vs lime and Temperature. 13 mm (0.5 in.) round bars, carburized at 900 “C (1650 “F), and oil quenched

4815: Variation in Carbon Concentration. Steel rock bit cutters carburized at 925 “C (1695 “F). Pit-type furnace, 314 mm (36 in.) in diameter by 1829 mm (72 in.) deep, used a carburizing-diffusion cycle. Dew point controlled at the generator only. Each test represents one load of 1361 kg (3000 lb). (a) 40 tests. Carbon at 1.8 mm (0.070 in.) below surface; (b) 50 tests. Carbon at 2.42 mm (0.095 in.) below surface

4815: Isothermal Transformation Diagram. Composition: 0.16 C, 0.52 Mn. 3.36 Ni, 0.19 MO. Austenitized at 900 “C (1650 “F). Grain size: 8 to 9

4815: Variation of Surface Carbon Content. 50 tests of rock bit cutters carburized in two pit-type furnaces to an aim of 0.75% C. Furnaces were operated simultaneously, using the same gas generator. Each furnace was 914 mm (36 in.) in diameter by 1829 mm (72 in.) deep and contained a load of about 1361 kg (3000 lb). A carburize-diffuse cycle was used. An automatic dew point controller was employed on the generator, but not on the furnace

Alloy Steel / 371

4815H: CCT Diagram. Composition

for commercial SAE 4815 carburizing steel: 0.16 C, 0.63 Mn, 0.010 P, 0.012 S, 0.24 Si, 3.35 Ni, 0.21 Cr, 0.24 MO. 0.19 Cu. In this study, slabs from commercial billet 76 mm (3 in.) square were normalized at 925 “C (1695 “F) for 1 h. Specimens were austenitized at 870 “C (1600 “F) for 20 min. The purpose of the study was to characterize a standard grade of carburizing steel for comparison with recently developed grades. Source: Datasheet l-257. Climax Molybdenum Company

372 / Heat Treater’s

Guide

4815H: Hardenability (1700 “F). Austenitize:

Hardness purposes J distance, IUDI 1.5

II 13 .5 !O Y IO i5 lo 15 ;0

Curves. Heat-treating 845 “C (1555 “F)

limits for specification Eardness, HRC Maximum Minimum 45 45 44 42 40 31 35 32 29 27 26 25 24 24 23

38 36 33 28 25 22 20

.

. .. .

iardness wrposes

limits for specification

I distance, 116in.

Eardnes, Maximum

I

, 1

IO I1 12 13 14 15 I6 8 !O !2 !4 !6 !8 IO I2

45 44 44 42 41 39 37 35 33 31 30 29 28 28 21 27 26 25 24 24 24 23 23 23

ARC hlinimum 38 31 34 30 27 24 22 21 20 ..”

.

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 925 “C

Alloy Steel / 373

4817,4817H Chemical

Composition.

4817. AISI and UNS: 0. IS to 0.20 C. 0.40

Annealing.

to0.60hln.0.03SPmax.0.~0Smax.0.lSto0.30Si.3.1Sto3.7SNi.0.20 to 0.30 MO. UNS A18170 and SAE/AISI 4817H: 0. II to 0.20 C. 0.30 to 0.70 hln. 0.1s to 0.35 Si. 3.20 to 3.80 Ni. 0.20 to 0.30 hlo

After normnlizinp. heat IO 650 “C (I100 “F), hold for I h per inch of section thickness. Cooling rnte from this temperature is not critical. hIa> also be isothermall> annealed b> heating to 715 “C (I 370 “F), cooling rapidly to 605 “C ( I I25 “F). and holding for 8 h

Similar

Tempering.

ASTM ASTM

Steels (U.S. and/or A3X. A304

Foreign).

4817.

A33 I. AS 19; SAE J-104. J-l I?. 5770.4817H. SAE Jl368

UNS G-18170: UNS H-I8 170:

Characteristics. U’ith the exception of a slightly higher carbon content, steels 18lSH and 1817H we identical. and thiir characteristics me essentially identical. As-quenched hardness (core hardness) should be slightI> higher for 1817H (approximately 36 to 43 HRC). Hardcnahilit!, patterns are nearly identical. Welding is possible. but preheating and postheating must be used Forging.

Heat to 12-15 “C (2175 OF) mnsimum. Do not forge after temperature of forging stock drops belo\{ approxunatel> 8-U “C ( IS55 “F)

Recommended Normalizing.

Case Hardening. See cttrhurizinp process described grade is rareI> subjected to carhonitriding

Recommended l l l l

Practice

l

“FL Cool in air

l

Heat Treating

Heat to 925 “C (16%

All pans made from this grade should he tempered at IS0 “C (300 “F) or higher if some loss of hrudness GUI be talented. Tempering \\ill help in transtormma retnmed wstenite

l

Processing

for 41 l8H. This

Sequence

Forge Normalize Anneal Rough md semifinish machine Case harden Temper Finish machine (cluburized parts only)

4817H: End-Quench Hardenability Distance from quenched surface I/lb in. mm

Hardness, HRC min max

Distance from quenched surface ‘lib in. mm

Hardness, HRC mas

I 7

I 58

46

39

13

20.5-i

30

; -I 5 6 7 8 9 10 II I2

-1.7-l 3.16 6.32 7.90 9.18 I I.06 I2.M I-I.72 IS.80 17.38 18.96

45 46 44 12 -II 39 37 35 33 3’ Iii

3x 35 32. ‘9 27 1.5 23 22 21 20 ‘0

I-l 15 16 18 70 22 24 ‘6 ‘8 30 32

22.12 13.70 25.x3 ‘8.44 31.60 34.76 37.91 41.08 44.2-l 47.40 SO.56

‘9 ‘8 78 17 26 3 25 25 2.5 2-l 21

4817, 4817H: Hardness vs Tempering Temperature. Represents an average

based

on a fully quenched

structure

374 / Heat Treater’s

Guide

4817: Carburizing

and Hardening vs Diametral Dimensions. Bevel drive pinion gear (a), carburized at 925 “C (1695 “F), tempered at 160 “C (320 “F). Depth of case, 1.27 to 1.65 mm (0.050 to 0.065 in.). Major spline diameter of twenty-five 4 kg (8 lb) gears (b) before treatment, (c) after treatment

4817: Cooling Curve. Half cooling time. Source: Datasheet

I-50. Climax Molybdenum

Company

Alloy Steel / 375

4817: CCT Diagram. Chemical composition:

0.17 C, 0.54 Mn, 0.015 P, 0.025 S, 0.33 Si, 0.087 Al. Alaboratory induction air melted heat. Specimens 4 mm (0.16 in.) in diameter were through-catburized to various carbon levels by holding in a carburizing atmosphere at 1150 “C (2100 “F) for 16 to 20 h. Machined dilatometer specimens 3 mm ((0.118 in.) in diameter were austenitized and cooled at three different rates to define the partial CCT diagram at each carbon level. The cooling rates ranged from 375 to 3280 “C (675 to 5900 “F) per min. The cooling curves used to define the diagrams are not shown. Instead, the cooling curves shown were measured on impact-fracture specimens (gear tooth simulation) at locations corresponding to the surface and the case-core interface during quenching in warm oil 66 “C (150 “F) or in hot oil 170 “C (340 “F). Specimens were austenitized at 900 “C (1650 “F) for 20 min. The objectives of the study were to obtain partial kinetic data on continuous-cooling transformation at various carbon levels in the carburized case. Hardness values (in circles on the diagram) were exhibited by specimens of each carbon level subjected to the fastest cooling rate used to define each CCT diagram. Source: Datasheet 1279. Climax Molybdenum Company

(continued)

376 / Heat Treater’s

Guide

4617: CCT Diagram. (continued)

Alloy Steel / 377

4817H: Hardenability

Curves. Heat-treating

(1700 “F). Austenitize:

845 “C (1555 “F)

iardness wrposes I distance, nm 1.5

3 I1 13 I5 !O 5 30 3.5 lo 15 50

iardness wrposes distance, :I6 in. I 2 3 1 5 5 7 9 1 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32

limits for specification Eardness, Maximum

HRC hlinimum 39 38 35 31 28 25 23 21

46 46 45 44 42 39 37 34 31 28 21 26 25 25 25

... .

limits for specification Hardness, Maximum 46 46 45 44 42 41 39 37 35 33 32 31 30 29 28 28 27 26 25 25 25 25 24 24

HRC hfinimum 39 38 35 32 29 27 25 23 22 21 20 20

. . .

. .

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 925 “C

378 / Heat Treater’s

Guide

4820,4820H,

4820RH

Chemical COIIIpOSitiOn. 4820. AISI and UNS: 0.18 to 0.23 C. 0.50 to0.70Mn.0.035Pmax.0.040Smax.0.15to0.30Si,3.25to3.75Ni.0.20 to 0.30 MO. UNS H48200 and SAE/AISI 48208: 0. I7 to 0.23 C. 0.40 to 0.80 Mn. 0.15 to 0.35 Si, 3.20 to 3.80 Ni. 0.20 to 0.30 MO. SAE IZORH: 0.18 to 0.23 C, 0.50 to 0.70 Mn. 0.15 to 0.35 Si. 3.25 to 3.75 Ni, 0.20 to

Recommended Normalizing.

Heat Treating

Practice

Heat to 925 “C (I 695 “F). Cool in air

Annealing.

0.30 MO

After normalizing, heat to 650 “C (I 200 “F). hold for I h per inch of section thickness. Cooling rate from this temperature is not critical. hlay also be isothermally annealed by heating to 745 “C ( I370 “F). cooling rapidly to 605 “C ( I I25 “F), and holding for 8 h

Similar

Tempering.

Characteristics.

Case Hardening. See carburizing process described grade is rarely subjected to carbonitriding. Austempering process

G-18200; Steels (U.S. and/or Foreign). 4820. UNS ASTM A322, A33 1, A505. AS 19, A535; SAE JW. 5412. J770. 4820H. UNS H48200; ASTM A304, A9 14; SAE J I 268. J8668

In general. the characteristics of 4820H are similar to those described for 48 I SH and 48 17H. Because of higher carbon content. as-quenched hardness of 4820H ranges from approximately 40 to 45 HRC. The hardenability band is shifted upward when compared with the bands for 4815H and 4817H. As is true for other high-nickel carburizing steels. there is a strong tendency for retention of austenite in the carburized cases of 4820 and 4820H. Amenable to welding, but alloy steel practice of preheating and postheating must be used

Forging. temperature

Heat to 1245 “C (2275 “Fj maximum. Do not forge after of forging stock drops below approximately 845 “C (I 555 “F)

Carburizing,

4820:

All parts made from this grade should be tempered at 150 “C (300 “F) or higher if some loss of hardness can be tolerated. Tempering will help in transforming retained austenite

Recommended

Processing

for 4118H. This is an alternative

Sequence

Forge Normalize . Anneal l Rough and semifinish machine l Case harden l Temper l Finish machine (carburized parts only) l l

Single Heat Results

Specimens contained 0.21 C, 0.51 Mn, 0.021 P, 0.018 S, 0.21 Si, 3.49 Ni, 0.18 Cr. 0.24 MO; critical points 1440 “F (780 “C); Ar,, 1215 “F (855 “C); Ar,, 780 “F (415 “C); grain size was 6 to 8; 0.565-in. (14.4-mm) round tested Yield strength 0.2% offset ksi hU’a

Ctl.92 Recommended practice

Eardness, ARC

Depth in.

mm

..,

For maximum case hardness Direct quench 6om pot(a) Single quench and temper(h) Double quench and temper(c)

60 61 60

0.039 0.047 0.047

For maximum core toughness Direct quench from pot(d) Single quench and temper(e) Double quench and tempertf)

56 57.5 56.5

0.039 0.047 0.047

included AC,, 1310 “F (710 “C); AC,, round treated. 0.505-in. (12.8-mm)

Tensile strength hIPa ksi

Elongation Reduction in2ill. Ofare& (50mm), % %

Hardness, EB

205 2075 204.5

l-11) 1431 1110

165.5 167 I65 5

II-II II51 II-11

13.3 I38 13.8

53.3 52.2 52.4

41.5 415 415

200.5 205 196.5

I382 1113 I355

170 184.5 171.5

II72 1272 I I82

12.8 13.0 13.0

53.0 53.3 53.4

4QI 41s 401

(a)Carburized at 1700 “F(92S “C) for 8 h, quenched in agitated oil. tempered at 3OO”F( IS0 “C, (h) Catknzed at 17OO”Ft925 “CI for 8 h. pot cooled. reheated to 1475 “F(800 “C). quenched in agitated oil. tempered at 300 “F (IS0 “C). Good case and core properties. (5) Carburized at I700 “F t92S “C) for 8 h. pot cooled. reheated to IS00 “F (815 “C). quenched inagitatedoil. reheated to IJSO”F(79O”C). quenched inagitatedoil. temperedat 3OO”F(lSO”C). For maximum refinement ofcaseandcore. (d)Carburizedat 1700°F (925”C)forS h.quenched inagitatedoil, temperedat450”F(230°C). te)Carhurizedat 1700”F(92S°C) for8 h. potcooled. reheated to lJ7S”F(800°C).quenched inagitatedoil. tempered at 450”F(230”C). Goodcaseandcore properties. (nCarburizedat 17OO”F(925 “0 for8 h. pot cooled. reheated IO 1500°F~81S “C).quenched in agitatedoil. reheated to 1~50”F~7’H)“C~,quenchedinagitatedoil.temperedat~50”F~230”C).(Source: BethlehemSteel)

4820:

As-Quenched

Hardness

(Oil)

4820: Hardness vs Tempering Temperature.

Grade: 0.18 to 0.23 C, 0.50 to 0.70 Mn. 0.20 to 0.35 Si, 3.25 to 3.75 Ni.0.20to0.30Mo;ladle:0.20C,0.61 Mn,0.027P,0.016S,0.29Si, 3.47 Ni, 0.07 Cr, 0.22 MO; grain size: 6 to 8 Si

round

in.

mm

Surface

Rardness, HRC ‘12radius

Cenler

‘/I

I3 15 51 102

45 4s 36 27

4.5 39 31 21

4-l 37 27 24

I 2 4

Source: Bethlehem Steel

average

based

on a fully quenched

structure

Represents

an

Alloy Steel I379

4820: Variation of Surface Carbon Content after Carburizing. Surface carbon concentration [first 0.076 mm (0.003 in.) depth of cut] in nineteen 25.4 mm (1 in.) diam bars carburized with production parts in a two-row continuous furnace. Desired carbon content, 0.75 to 0.80%. Specimens were carburized at 925 “C (1695 “F) using a diffusion cycle, quenched from 815 “C (1500 “F) in oil at 60 “C (140 “F), tempered in lead at 620 “C (1150 “F) for 5 min, wire brushed, and liquid-abrasive cleaned. Atmosphere at the charge end of the furnace was automatically controlled at a dew point of -15 “C (5 “F) and at the discharge end at 3 “C (35 “F). Endothermic gas enriched with straight natural gas was used as the carbunking medium; air was added at the discharge end

4820H: End-Quench Hardenability Distance from quenched surface ‘/,b in. mm

Eardness, ERC max min

Distance 6om quenched surface

‘46in.

,IM,l

2 3

1.58

3.16 4.74

48 48 47

41 40 39

13 I4 1s

-I 5 6 7

6.32 7.90 9.48 I I.06

46 45 43 32

38 3-l 31 ‘9

16 18 20 22

20.54 22.12 23.70 2S.28 28.44 31.60 34.76

8 9 IO II I2

12.64 14.22 IS.80 17.38 18.96

-IO 39 37 36 35

27 26 25 2-l 23

24 26 28 30 32

37.92 41.08 44.24 47.40 50.56

I

Rardoess, ERC max min 34 33 32 31 29 28 28 27 27 26 26 25

22 22 ?I ‘I 20 20 ..,

.._ .._ .__

380 / Heat Treater’s

4820: Continuous Austenitized

Guide

Cooling Transformation

0.18 C, 0.47 Mn, 0.009 P, 0.010 S, 0.27 Si, 3.33 Ni, 0.18 Cr, 0.23 MO. at 900 to 920 “C (1650 to 1690 “F) for 4 h

Diagram. Composition:

at 780 “C (1435 “F). Blank carburized

Alloy Steel I381

4820H: Hardenability

Curves. Heat-treating

(1700 “F). Austenitize:

845 “C (1555 “F)

Hardness purposes J distance, mm 1.5 3 5 I 9 11 13 15 20 25 30 35 40 4.5 50

Hardness purposes I distance, k,b in. 1 2 3 1 5 5 7 B 9 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32

limits for specification Hardness, hlaximum

HRC hlinimum 41 40 39 36 32 29 27 25 22 21 20 .

48 48 48 46 45 43 40 39 3.5 32 29 28 21 26 26

limits for specification Hardness, hlarimum 48 48 41 46 45 43 42 40 39 37 36 35 34 33 32 31 29 28 28 21 21 26 26 25

HRC hlinimum 41 40 39 38 34 31 29 21 26 25 24 23 22 22 21 21 20 20

. . ..

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 925 “C

1

382 / Heat Treater’s

Guide

4820RH: Hardenability “C (1700 “F). Austenitize:

Hardness purposes J distance, ‘46io.

I 2 3 4 5 6 7 B

9 IO II 12 13 II IS I6 I8 ?O 12 2-l 16 18 30 32

Hardness purposes J distance,

mm I .5 3 s 7

9 II 13 IS 20 !5 30 35 40 85 SO

Curves. Heat-treating 845 “C (1555 “F)

limits for specification Eardoes, Maximum

ARC Minimum

17 47 46 45 33 41 40 38 36 35 34 33 32 31 30 29 28 27 26 25 25 25 24 23

42 32 -II xl 36 33 32 30 28 27 26 25 24 24 23 33 22 22 21 20 20

limits for specification Hardness, HRC Minimum Maximum 37 47 46 44 42 40 38 3.5 32 29 27 26 25 24 23

12 42 31 38 3-l 32 30 27 2-l 23 22 21 20

temperatures

recommended

by SAE. Normalize

(for forged or rolled specimens

only): 925

1

Alloy Steel / 383

50940,50940H,

50940RH

Chemical Composition. 5OB40. AISI: 0.38 to 0.43 C, 0.75 to I .oo Mn, 0.035 P max. 0.040 S max. 0.40 to 0.60 Cr. 0.0005 B min. UNS: 0.38 to 0.42 C, 0.75 to I .OO Mn, 0.035 P max. 0.040 S max. 0. I5 to 0.30 Si. 0.10 to 0.60 Cr. 0.0005 B min. UNS A50401 and SAE/AISI 50B40H: 0.37 to 0.1WC.0.65to1.10Mn.0.15to0.35Si.0.30to0.70Cr.B(c~beexpected to be 0.0005 to 0.003 percent). SAE SOB4ORH: 0.38 to 0.43 C. 0.75 to I .OO Mn. 0.15 to 0.35 Si, 0.40 to 0.60 Cr. B (can be expected to be 0.0005 to 0.003 percent) Similar Steels (U.S. and/or Foreign).

50B40. UNS G5w01; ASTM A5 19; SAEJ404.5412, J770; (Ger.) DIN 1.7007; (Ital.) UN1 38 CrB I KB. 50B40H. UNS H50401; ASTM A304, A914: SAE Jl268. Jl868; (Ger.) DW I .7007: (Ital.) UN1 38 CrB I KB

Characteristics. A medium-carbon gade with an as-quenched surface hardness in the range of approximately 52 to 58 HRC. depending on whether the carbon is low or high on the allowable range. The hardenability band for SOB-IOH is nearly equal to that of 8630H. a higher alloy and more expensive steel. Is easily foged and responds readily to heat treatments that are used for other low-alloy steels of similar carbon content

Annealing.

For a predominately pearlitic structure, heat to 830 “C (1525 “F), cool rapidly to 740 “C ( I365 “F), then to 670 “C ( 1240 “F) at a rate not to exceed I I “C (20 “F) per h: or heat to 830 “C (I 525 “F). cool rapidly to 675 “C (1245 “R. and hold for 6 h. For a predominately spheroidized structure. heat to 760 “C (I 300 “F), cool to 665 “C ( I230 “F) at a rate not to exceed 6 “C ( IO “F) per h; or heat to 760 “C ( 1400 “F), cool rapidly to 665 “C (1230 “F). and hold for 8 h. For most subsequent operations such as machining and hardening, a predominately spheroidized structure is preferred

Hardening. Tempering.

Heat to 1230 “C (3250 “FI maximum. Do not forge after temperature of forging stock drops below approximately 925 “C ( I695 “F)

Recommended l l l

Recommended

Heat Treating

Practice

l l

Normalizing.

Heat to 870 “C ( I600 “F). Cool in air

5084OH: End-Quench Distance from quenched surface l/16 in. mm I 2 3 4 5 6 7 8 9 IO II I?

I .58 3.16 1.7-l 6.32 790 9.48 I I.06 12.64 14.22 15.80 17.38 18.96

Eardness, ARC mar min 60 60 59 59 58 58 57 57 56 55 53 51

l

Hardenability

53 53 52 51 50 48 4-l 39 31 31 29 28

Distance from quenched surface ‘/la in. mm 13 1-l 15 I6 ia 20 22 2-l 26 28 30 32

20.51 22.12 23.70 25.28 28.4-I 31.60 31.76 31.92 41.08 44.2-l 47.40 50.56

Aardness. HRC min max 19 47 4-l 31 38 36 35 34 33 32 30 29

27 26 25 25 23 II

at 845 “C (1555 “F). and quench in oil

Parts made from SOB-tOH should be tempered immediately after they have been uniformly quenched to near ambient temperature. Best practice is to place workpieces into the tempering furnace just before they have reached room temperature. ideally when they are in the range of 38 to 50 “C (100 to I20 “F). Tempering temperature must be selected based upon the tinal desired hardness

l

Forging.

Austenitize

Processing

Sequence

Forge Normalize Anneal Rough and semifinish machine Austenitize and quench in oil Temper Finish machine

50840,50B40H:

Hardness

sents an average

based

vs Tempering

on a fully quenched

Temperature. structure

Repre-

384 / Heat Treater’s

Guide

50940H: Hardenability

Curves. Heat-treating

“C (1600 “F). Austenitize:

845 “C (1555 “F)

Hardness purposes J distance, mm 1.5 3 5 7 9 11 13 15 20 25 30 35 40 45 50

Hardness purposes J distance, ‘/,6 in. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32

limits for specification Eardness, Maximum

ARC Minimum

60 60 60 59 59 58 57 56 50 43 37 35 34 32 30

53 53 52 51 49 44 38 33 27 24 22

limits for specification Eardness, Maximum 60 60 59 59 58 58 57 57 56 55 53 51 49 47 44 41 38 36 35 34 33 32 30 29

RRC blinimum 53 53 52 51 50 48 44 39 34 31 29 28 27 26 25 25 23 21

temperatures

recommended

by SAE. Normalize

(for forged or rolled specimens

only): 870

Alloy Steel / 385

50B40RH: Hardenability Curves. Heat-treating temperatures “C (1600 “F). Austenitize:

845 “C (1555 “F)

iardness limits for specification wrposes I distance, /lfJ in.

0

Hardness, ARC Maximum Minimum 59 59 58 58 57 56 55 5-l 52. so -t9 47 -is 4.4 -II 38 36 3-t 33 37 31 30

5-l 5-I S? S3 52 SO -17 13 38 35 33 3’ ii 30 ‘9 28 26 2-l 23 21 21 20

19 28

iardness limits for specification wrposes distance, mm

.s

Rardness, EIRC hlinimum Maximum S-l 5-l 53 s3

3

59 59 58 98 56 55 5-l

5

51

0

46

5 5

39 35 33

36 31 ‘8 3 23

0

31

?I

5

29 28

20

I

(I

0

51 47 42

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870

386 / Heat Treater’s Guide

50844,50B44H Chemical Composition.

5OB44. AIM: 0.43 to O.-i8 C. 0.75 to 1.OO

Mn. 0.035 P max. 0.040 S max. 0. I5 to 0.30 Si, 0.40 to 0.60 Cr. 0.0005 to 0.003 B. IJNS: 0.43 to 0.48 C. 0.75 to 1.00 Mn, 0.035 Pmax. 0.040 S max, 0.15 to 0.30 Si. 0.40 to 0.60 Cr. 0.0005 B min. UNS ES0441 and SAE/AISI 50B44H: 0.42 to 0.49 C. 0.65 to I. IO Mn. 0. I5 to 0.35 Si. 0.30 to 0.70 Cr. B (can be expected to be 0.0005 to 0.003 percent)

Similar Steels (U.S. and/or Foreign). SoB44. ASTM A5 19; SAE 5404, 5412. 5770. 50B44H. A304; SAE J I268

UNS Gs04-1 I ; UNS H50441; ASTM

Characteristics. Has the same general characteristics as 50B40H. Because of slightly higher carbon content, the as-quenched hardness of SOB44H will be higher. although the carbon ranges of the two steels overlap. The asquenched hardness will range from approximately 54 to 60 HRC. Hardenability bands for the two grades are similar. the band for SOB44H shifted slightly upward. Is easily forged and responds readily to heat treatments that are used for other low-alloy steels of similar carbon content

Annealing.

For a predominately pearlitic structure, heat to 830 “C (I 525 “F), cool rapidly to 740 “C (I 365 OF). then to 670 “C ( 1240 “F) at a rate not to exceed I I “C (20 “F) per h: or heat to 830 “C (I 525 “F), cool rapidly to 675 “C (I235 “F). and hold for 6 h. For a predominately spheroidized structure. heat to 760 ‘C ( 1300 “F), cool to 665 “C ( I230 OF) at a rate not to exceed 6 “C (IO “F) per h: or heat to 760 “C (1400 “F), cool rapidly to 665 “C ( 1230 “F). and hold for 8 h. For most subsequent operations such as machining and hardening, a predominately spheroidized structure is preferred

Hardening. Tempering.

Heat to 1230 “C (2250 “F) maximum. Do not forge after temperature of forging stock drops below approximately 925 “C (1695 “F)

Recommended

Heat Treating

Practice

Recommended l

Anneal

Rough and semifinish machine Austenitire and quench in oil Temper Finish machine

l

Sequence

Forge Normalize

l l

Heat to 870 “C (1600 “Fj. Cool in air

Processing

l

l

Normalizing.

at 845 “C (IS55 “F), and quench in oil

Parts made from SOB34H should be tempered immediately after they have been uniformly quenched to near ambient temperature. Best practice IS to place workpieces into the tempering furnace just before they have reached room temperature, ideally when they are in the range of 38 to 50 “C ( IO0 to I20 “F). Tempering temperature must be selected based upon the final desired hardness

l

Forging.

Austenitize

50844,50844H:

Hardness vs Tempering Temperature. Repre-

sents an average based on a fully quenched structure

50844H: End-Quench Hardenability Distancefrom Eardoess, ERC min max I 2 3 4 5 6 7 8 Y IO II 12

I.58 3.16 4.74 6.32 7.90 9.48 Il.06 12.64 I-I.22 IS.80 17.38 I a.96

63 63 62 62 61 61 60 60 59 58 57 56

56 56 55 55 54 52 48 43 38 34 31 30

Distance from quenched surface Vi6 in. mm I3 I-2 IS I6 IX 20 ‘2 24 26 28 30 32

20.54 22. I2 23.70 25.28 28.4-I 31.60 34.76 37.92 11.08 44.2-l 47.-Kl 50.56

EZUdlleSS,

ERC max

min

5-l 52 SO 48 44 -lo 38 37 36 35 3-l 33

29 29 28 27 26 2-l 23 21 20

Alloy Steel / 387

50844H: Hardenability

Curves. Heat-treating

“C (1600 “F). Austenitiie:

845 “C (1555 “F)

iardness wrposes I distance. qm

1.5 3 5 7 ?

I1 13 15 20 25 30 35 10 15 50

iardness wrposes distance,

‘16in.

1 3 IO I1 12 13 I4 I5 I6 I8 !O !2 !4 !6 !8 SO i2

limits for specification Hardness, ERC Maximum Minimum 63 63 63 62 61 61 60 59 55 49 42 38 31 35 34

56 56 55 54 52 49 42 36 30 21 25 23 21

.

limits for specification Eardness, HRC Maximum Minimum 63 63 62 62 61 61 60 60 59 58 51 56 54 52 50 48 44 40 38 37 36 35 34 33

56 56 55 55 54 52 48 43 38 34 31 30 29 29 28 27 26 24 23 21 20

.

temperatures

recommended

by SAE. Normalize

(for forged or rolled specimens

only): 870

1

388 / Heat Treater’s Guide

5046,5046H Chemical Composition.

Annealing. For a predominately pearlitic structure, heat to 830 “C (1525

Similar Steels (U.S.

OF), cool rapidly to 755 “C (1390 “F), then cool from 755 “C (1390 “F) to 655 “C (1220 “P) at a rate not to exceed 11 “C (20 “F) per h; or heat to 830 “C (1525 “F), cool rapidly to 665 “C (1230 OF), and hold for 4 qz h. For a predominately spheroidized structure, heat to 760 “C (1400 OF),cool to 665 “C (1230 “F) at a rate not to exceed 6 “C (10 “F) per h; or heat to 760 “C (1400 “F), cool rapidly to 660 “C (1220 “F), and hold for 8 h

5046. AISI: 0.43 to 0.50 C, 0.75 to 1.00 Mn,0.040Pmax,O.O40S max.0.20to0.35 Si,O.20 too.35 Cr. UNS: 0.43 to0.50C,0.75to1.00Mn,0.035Pmax,0.040Smax,0.15to0.30Si,0.20 to 0.35 Cr. UNS I-I50460and SAE/AISI 5046lk0.43 to 0.5OC,O.65 to 1.10 Mn, 0.15 to 0.35 Si, 0.13 to 0.43 Cr and/Or

Foreign). 5046.

ASTM A519; SAE J404,J412,J770.5046H. SAE J 1268

UNS G50460; UNS H50460; ASTM A304:

Characteristics.

A typical medium-carbon, very low-alloy steel. When both manganese and chromium are on the high side of their allowable ranges, 5046H has sufficient hardenability so that full hardness can be obtained in thin sections by oil quenching. As-quenched hardness typically ranges from approximately 53 to 58 HRC, depending on whether the carbon is on the low or the high side of the range

Hardening. Austenitize at 845 “C (1555 “F), and quench in oil for thin sections. Thicker sections wih require a water or brine quench for full hardness Tempering. After quenching, reheat to the temperature required to achieve the final desired hardness

Recommended

Processing

Sequence

Forge l Normalize l Anneal (preferably spheroidize) l Rough machine l Harden Q Temper l Finish machine l

Forging. Heat to 1230 “C (2250 “F) maximum. Do not forge after temperature of forging stock drops below approximately 870 “C (1600 “F)

Recommended

Heat Treating

Practice

Normalizing. Heat to 870 “C (1600 “F). Cool in air

5046: Hardness vs Tempering Temperature. Normalized at 870

5046H: End-Quench Hardenability

“C (1600 “F), quenched from 845 “C (1555 “F), tempered in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source:.Republic.Steel

Distance from quenched surface

&h.

mm

1

1.58 3.16 4.15 6.32 7.90 9.48 1.06 12.64 14.22 15.80 17.38 18.96

2 3 4 5 6 I 8 9 10 11 12

Hardness, HRC max min 63 62 60 56 52 46 39 35 34 33 33 32

56 55 45 32 28 27 26 25 24 24 23 23

Distance from quenched surface

?,&h.

mm

13 14 15 16 18 20 22 24 26 28 30 32

20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40 50.56

Hardness, HRC max min 32 31 31 30 29 28 27 26 25 24 23 23

22 22 21 21 20

Alloy

5046H: Hardenability (1600 “F). Austenitize:

Hardness purposes J distance. mm 1.5

3 5 7 9 11

13 15

20 25 30 35 40 45

Hardness purposes I distance, %6 in.

0 1

2 3 4 5 6 8 0 2 4 6 8 0

Curves. Heat-treating 845 “C (1555 “F)

limits for specification flardness, HRC Maximum hIinimum 63 62 59 54 48 39 35 34 32 30 29 27 26 24

56 54 40 30 27 26 25 25 22 20 .

limits for specification Hardness, HRC Maximum hlinimum 63 62 60 56 52 46 39 35 34 33 33 32 32 31 31 30 29 28 21 26 25 24 23

56 55 45 32 28 21 26 25 24 24 23 23 22 22 21 21 20 ..” ...

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

Steel / 389

only): 870 “C

390 / Heat Treater’s Guide

50B46,50B46H Chemical Composition.

SOB46. AISI: 0.44 to 0.49 C, 0.75 to 1.OO Mn, 0.035 P max. 0.040 S max. 0. I5 to 0.30 Si, 0.20 to 0.35 Cr. 0.0005 to 0.003 B. UNS: 0.44 to 0.49 C, 0.75 to 1.00 Mn. 0.035 Pmax. 0.040 S max. 0.15 to 0.30 Si. 0.20 to 0.35 Cr. 0.0005 B min. UNS II50461 and SAE/AISI SOB46H: 0.43 to 0.50 C. 0.65 to I. 10 Mn, 0.15 to 0.35 Si. 0.13 to 0.43 Cr. B (can be expected to be 0.0005 to 0.003 percent)

Similar Steels (U.S. and/or Foreign).

SOB46. IJNS G5046I ; ASTM ASTM A519; SAE J404. 5412, J770. 50B46H. UNS H5046I: A304; SAE J I268

Characteristics. Boron influences 50B36H much the same as it affects 50B4OH and 50B44H. 50B46H has a lower chromium content. When the chromium is low. approaching 0.13. the hardenability without the boron would be little more than that of a plain carbon steel. Hardenability is lower when compared with 50BUH. As-quenched surface hardness for 50B46H can be expected to be about the same as for 50B44H. 54 to 60 HRC Forging. temperature

Annealing.

For a predominately pearlitic structure. heat to 830 “C (1525 “F), cool rapidly to 740 “C ( I365 OF). then cool to 670 “C (1240 “F) at a rate not to exceed I I “C (20 “F) per h; or heat to 830 “C (I 525 “F), cool rapidly to 675 “C (I 245 “F), and hold for 6 h. For a predominately spheroidized structure, heat to 760 “C ( 1400 “F’), cool to 665 “C ( 1230 “F) at a rate not to exceed 6 “C (IO “F) per h: or heat to 760 “C ( 1400 “F), cool rapidly to 665 “C (I230 “F), and hold for 8 h

Hardening. Tempering.

Recommended l l l

Recommended

Heat Treating

Practice

l l

Normalizing.

Heat to 870 “C (1600 “F). Cool in air

50646: Hardness vs Tempering Temperature. Normalized

l

at

870 “C (1600 “F), quenched from 845 “C (1555 “F) in oil and tempered in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds.

Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel

at 845 “C (I 555 “F), and quench in oil

Parts made from 50B44H should be tempered immediately after they have been uniformly quenched to near ambient temperature. Best practice is to place workpieces into the tempering furnace just before they have reached room temperature. ideally when they are in the range of 38 to 50 “C ( 100 to I20 “F). Tempering temperature must be selected based upon the final desired hardness

l

Heat to 1230 “C (2250 “F) maximum. Do not forge after of forging stock drops below approximately 925 “C (1695 “F)

Austenitize

Processing

Sequence

Forge Normalize Anneal Rough and semifinish machine Austenitize and quench in oil Temper Finish machine

50846H: End-Quench Hardenability Distance from quenched surface V,6 in. mm I 2 3 .I 5 6 7 8 9 IO II I2

1.58 3.16 1.74 6.32 7.90 9.48 II.06 12.6-l 14.21 15.80 17.38 18.96

Hardness. BRC min may 63 62 61 60 59 58 57 56 54 51 17 13

56 5-l 52 so -II 32 31 30 29 28 27 26

Distance from quenched surface 916in. mm 13 I-I IS 16 I8 ‘0 22 2-l 26 28 30 32

20.54 22.12 23.70 25.28 28.4-I 31.60 34.76 37.92 II .08 44.2-l 47.40 50.56

Eardoess, ERC msx min 40 38 37 36 35 34 33 32 31 30 29 28

26 25 25 23 23 22 21 20

_..

Alloy Steel / 391

50B46H: Hardenability Curves. Heat-treating temperatures recommended by SAE. Normalize (for forged or rolled specimens only): 870°C (1600 “F). Austenitize: 845 “C (1555 “F)

Hardness limits for specification wrposes I distance, nm

Eardness, ERC luaximum Minimum 63 62 61

56

60

47

59 58 56 53 12 37 35

35 31 29 ‘8 76

34

55 53

24 22 21

32 31 29

iardness limits for specification wrposes I distance,

46i”.

, I ,

I I 0 I 2 3 4

5 6 8

II ‘2 4 6 8

‘0 ‘2

Eardoess, ERC Maximum Minimum 63 62 61

60 59 58 51 56 54

51 47 43

40 38 31 36 35 34 33 32 31 30 29 28

56 54

52 50 41 32 31

30 29 28

27 26 26

25 25 2-l 23 22

II 20

392 / Heat Treater’s

Guide

50B50,50B50H Chemical

COIIIpOSitiOn. 50B50.AISI: 0.48 to 0.53 C. 0.75 to 1.00 Mn. 0.035 P max. O.MO S max. 0. IS to 0.30 Si, O.-IO to 0.60 Cr. 0.0005 to 0.003 B. UNS: 0.18 to 0.53 C. 0.75 to I .OO Mn. 0.035 P max. O.O-lO S max. 0.15 to 0.30 Si. 0.40 to 0.60 Cr. O.OOOS B min. UNS H50501 and SAE/AISI 50B50H: 0.47 to 0.5-l C. 0.65 to I. IO Mn. 0. IS to 0.35 Si, 0.30 to 0.70 Cr. B (can be expected to be 0.0005 to 0.003 percent)

Similar

Steels (U.S. and/or

Annealing. For a predominately spheroidized structure. heat to 750 “C t I380 “F). cool rapidI> to 705 “C ( I300 “F). then cool to 650 “C ( I200 “F). at a rate not to exceed 6 “C I IO “F) per h: or heat to 750 “C ( I380 OF). cool rapidly to 675 “C ( I Z-IS ‘W. and hold for I2 h Hardening.

SOBSO. LINS G50501; ASTM AS 19; SAE J-IO-I. 5412.5770; t&r.) DIN I .7 138; (Jap.) JIS SUP I I. 50B50H. UNS HSOSOI; ASThl ,430-k SAE Jll68; (Ger.) DIN 1.7138; (lap.) JIS SUP I I

Characteristics.

Borders between what is usually considered as a medium-carbon and a high-carbon steel. depending on the precise carbon content. n hich also controls the as-quenched surface hardness. A range of approximately 56 to 62 HRC can be expected. The 0.30 to 0.70% chromium and the boron treatment produce a relativeI> high hardenability. Lksd for a variety of applications. u here its hardenability is ad\ antageous. such as heavy-duty springs

Forging.

Heat to 1230 “C (2250 “F) maximum. Do not forge after of foging stock drops below approximateI> 925 “C (I 695 “F)

Parts made from SOBSOH should be tempered immediately after they have been uniformly quenched to near ambient temperature. Best practice is to place uorkpieces into the tempering furnace just before they have reached room temperature. ideally when the) are in the range of 38 to 50 “C (I 00 to I20 ‘Fj. Tempering temperature must be selected based upon the final desired hardness

Recommended l

Normalizing.

I 2 3 1 5 6 7 8 Y IO II I:!

I.% 3.16 1.74 6.32 7.90 9.48 Il.06 12.6-t I-i.12 15.80 17.38 I8.%

l l

Heat to 870 “C ( 1600 “FI. Cool in air

l

Heat Treating

5085OH: End-Quench Distance from quenched surface 916in. mm

l

Practice

Recommended

65 65 6-t 6-l 63 63 62 62 61 60 60 59

l

Hardenability

Bardness, HRC min max 59 59 58 57 56 55 52 41 -I2 37 3s 33

at 845 ‘C ( 1555 “F), and quench in oil

Tempering.

l

temperature

Austsnitize

Foreign).

Distance from quenched surface 916 in. mm 13 I-l 15 I6 18 20 22 3-l 26 28 30 31

20.S-l ‘1.12 23.70 25.28 28.4-t 31.60 31.76 37.92 -Il.08 44.2-i -17.40 SO.56

Aardness, BRC max 58 57 56 5-l 50 -17 4-l II 39 38 37 36

21 20

Processing

Sequence

Forge Normalize AMY Rough and semifinish machine Austcnitire and quench in oil Temper Finish machine

50950,50950H:

Hardness

sents an average

based

vs Tempering

on a fully quenched

Temperature. structure

Repre-

Alloy Steel I393

50B50H: Hardenability “C (1600 “F). Austenitize:

iardness >urposes I distance, q m

1.s 3 5 7 9 11 13 15 20 25 30 35 40 45 50

Hardness purposes I distance, I,/,fj in. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32

Curves. Heat-treating 845 “C (1555 “F)

limits for specification Hardness, HRC Maximum Minimum 6.5 65 65 64 63 63 62 62 59 54 49 44 40 38 37

59 59 59 51 55 52 46 39 32 29 27 26 24 22 20

limits for specification Hardness, HRC hlavimum Minimum 65 65 64 64 63 63 62 62 61 60 60 59 58 51 56 54 50 47 44 41 39 38 31 36

59 59 58 57 56 55 52 41 42 37 35 33 32 31 30 29 28 27 26 25 24 22 21 20

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870

394 / Heat Treater’s

Guide

50860,50B60H Recommended

Chemical

COIIIpOSitiOn. 50860. AIM: 0.56 to 0.64 C. 0.75 to I .OO Mn. 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.40 to 0.60 Cr. 0.0005 to 0.003 B. UNS: 0.56 to 0.64 C. 0.75 10 1.00 Mn. 0.035 Pmax. 0.040 S max. 0.15 to 0.30 Si. 0.40 to 0.60 Cr. 0.0005 B min. UNS I-I50601 and SAE/AISI 50B6OH: 0.55 10 0.65 C. 0.65 to I. IO Mn. 0.15 to 0.35 Si. 0.30 to 0.70 Cr. B (can be expected to be 0.0005 to 0.003 percent)

Similar

Steels (U.S. and/or Foreign). 5OB60. UNS GS0601; ASTM A5 19; SAE 5404. J412, J770. 50B6OR. UNS H50601; ASTM A304; SAE Jl268

Characteristics. Has the same general characteristics as other boroncontaining steels. With the higher carbon content, an as-quenched hardness in the range of approximately 58 to 63 HRC can be expected. The hardenability of this grade is quite high. Both the top and the bottom boundaries of the hardenability band are straight lines for significant distances from the quenched end. Used for parts lhat demand high hardenability. especially where economy is a factor. This steel. similar to other boron-containing steels. represents a cost-effective way of achieving high hardenability Forging.

Heat LO I205 “C (2200 “F) maximum. Do not forge after temperature of forging stock drops below approximately 925 “C ( I695 “F). Because of high hardenability, forgings. especially complex shapes. should be cooled slowly from the forging operation to minimize the possibility of cracking. Forgings may be slow cooled by either placing them in a furnace or burying them in an insulating compound

50B60l-l: End-Quench Distance from quenched surface l/16 in. mm I 2 3 1 5 6 7 8 9 IO II I?-

1.58 3.16 4.75 6.32 7.90 9.48 11.06 12.6-I 14.22 IS.80 17.38 I a.96

Hardenability

Eardness, ERC max min 60 __.

65 6.5 64 64 64

60 60 60 60 59 57 53 47 42 39 37

Distance from quenched surface ‘&j in. mm I3 II 15 I6 I8 20 22 2-l 26 28 30 32

20.54 22.12 23.70 25.28 28.4-t 31.60 34.76 37.92 41.08 44.24 47.40 50.56

Eardlless. ARC miw min 63 63 63 62 60 58 55 53 51 49 -17 44

36 35 3-l 41 33 31 30 29 28 21 26 25

Normalizing.

Heat Treating

Practice

Heal LO870 “C ( 1600 “F). Cool in air

Annealing.

For a predominately spheroidized structure. which is usually favored for this grade, heat to 750 “C (I 380 “F), cool rapidly to 700 “C ( I290 “F). then cool to 655 “C ( I2 IO “F). at a rate not to exceed 6 “C (IO “F) per h: or heat 10 750 “C (I 380 “F). cool rapidly to 650 “C ( 1200 “F), and hold for I2 h

Hardening.

Austenitize

at 845 “C (I 555 “F). and quench in oil

Tempering.

Selection of tempering temperature depends on the fmal properties desired. To prevent cracking, make sure parts have reached a uniform temperature throughout each section, and then place them in a tempering furnace before ambient temperature is reached. 38 to 50 “C (100 to I20 “F) is considered ideal

Recommended l l l l l l l

Processing

Sequence

Forge Normalize Anneal Rough and semitinish machine Austenitize and quench Temper Finish machine

50860: Hardness vs Tempering Temperature. Normalized at 870 “C (1600 “F), quenched from 845 “C (1555 “F) in oil, tempered in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel

Alloy Steel / 395

50B60H: Hardenability Curves. Heat-treating “C (1600 “F). Austenitize: 845 “C (1555 “F)

Hardness purposes I distance, nm

limits for specification Eardness, HRC Maximum Minimum

.s

I 3 5 !O !S 10 15 10 IS i0

iardness wrposes distance.

‘16b.

65 65 65 62 59 56 52 18 1.5

60 60 60 60 59 57 Sl 44 36 34 32 30 78 27 25

limits for specification Aardness, ARC Maximum Miuimum

65 65 6-l 6-l 6-l 63 63 63 62 60 58 55 53 51 49 37 44

60 60 60 60 60 59 57 53 17 12 39 37 36 35 34 34 33 31 30 29 28 37 26 2s

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870

396 / Heat Treater’s

Guide

5117 Chemical

Composition.

5117. AISI and UNS: 0.15 100.20 C. 0.70

to 0.90 hln. 0.035 P max. 0.040 S max. 0. IS to 0.30 Si. 0.70 to 0.90 Cr

Similar

Steels (U.S. and/or Foreign).

UNS

Gs I I 70

Characteristics. A slightly modified version of 5 IX. The carbon range is lower, hut the ranges for the two steels overlap. Although there is no H version of 5 I 17. hardenability is expected to he very close to that of S I2OH. As-quenched hardness for 51 I7 (no case) usually ranges from 36 to -II HRC.’ Readily forgeable and weldable with alloy steel welding practice. Definitely a case hardening grade and is used for parts that require kther carburizing or carbonitriding~ For further details see 5 l20H Forging. temperature

Heat to 12-15 “C (2275 “F) maulmum. Do not forge after of forging stock drops beIon approximately 870 “C t 1600 “F)

Recommended Normalizing.

Heat Treating

Practice

Heat to 935 “C t 1695 “FL Cool in air

Annealing.

Not usually requtred for this grade. Structures that are well suited to machining are generally ohtained hy normalizing or hy isothermal annealing after rolling or forgins. Isothermal annealing is accomplished by heating to 700 “C t 12570 “FJ, and holding for 8 h

Case Hardening. See recommended carhurizing, carhonitriding. and tempering procedures described for 4 I I SH. Ion nitriding and gas nitriding are alternative processes

Recommended l l l l l l l

Forge Normalize Anneal (optional) Rough and senitinijh Case harden Temper Finish machine

Processing

Sequence

machine

5117: Hardness vs Tempering Temperature. erage based on a fully quenched structure

Represents

an av-

396 / Heat Treater’s

Guide

5120,512OH Chemical

Composition.

5120. AISI and UNS: 0. I7 to 0.22 C. 0.70

to 0.90 hln, 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.70 to 0.90 Cr. IJNS H512OOand SAE/AISI 5120H: 0.17 to 0.23 C. 0.60 to I .OOhln. 0. IS to 0.35 Si. 0.60 to 1.00 Cr

Similar Steels (U.S. and/or

Foreign).

5120.

ASTM A322. A33l. ASl9: SAE J-101. 5770: (Ger.) .AFNOR 20 MC 5.5120H. UNS HS 1200: ASThf A304 DIN I .7147; (Fr.) AFNOR 20 hfC 5

UNS GS 1200: DIN 1.7147: (Fr.) SAE J 1268: (Ger.)

Characteristics. A low-alloy carburizing grade. An as-quenched hardness of approximately 38 to 4-I HRC can normally be expected. This range represents the core hardness of carhurized 5 I20H. Would not be considered it high hardenability steel. but it is similar to II IXH in hardenahility Forging.

Heat to I245 “C (2275 ‘F) maximum. Do not forge after temperature of forging stock drops below approximately 870 ‘C I I600 “F)

Recommended Normalizing.

Heat Treating

Practice

Heat to 925 “C t I695 “F). Cool in air

Annealing. Best machining structures lue obtained hy hesting to 800 “C t 1475 “FL cooling rnpidly to 675 Y f 1215 “F). and holding for IO h Tempering. tempered tolerated

PHIIS that hove been crtrburized or carbonitrided should be at 150 ‘C (300 “FL or higher if some loss of h‘ardness can be

Case Hardening. tempering process

procedures

Recommended l

Forge Normalize

.

AnIlZd

l

See recommended carhurizing. carbonitriding, and described for -! I I8H. Ion mtriding IS an alternative

Processing

Sequence

Rough and semitinish machine Carhurize. diffuse and quench. or carhonitride . Temper l Finish muchine if required l

l

and quench

Alloy Steel 1397

5120, 5120H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure

5120H: End-Quench Hardenability Distance from Hardness, HRC min max I 2 3 1 5 6 7 8 9 I0 II I?

I.58 3.16 4.7-l b.32 7.90 9.18 I I .M Ix4 l-l.22 IS.80 17.38 18.96

48 46 -II 36 33 30 18 '7 25 2-l 23 '2

-IQ 34 28 23 20

Distance frum quenched surface ‘&in. mm I3 l-l I5 I6 18 20 22 2-l 26 18 30 31

20.54 '2.12 23.70 '5.28 78.4-l 31.60 34.76 37.91 41.08 4-4.2-I 17.40 50.56

Hardness. HRC ma\ 21 'I 20

398 / Heat Treater’s

Guide

5120H: Hardenability (1700 “F). Austenitize:

Curves. Heat-treating 925 “C (1700 “F)

iardness wrposes

limits for specification

I distance, lull

Eardnes, Maximum

I.5 I i I I 1 3 5 !O !S

iardness wrposes I distance,

116in. 1 I

i i , I I ) 10 I ,2 3 -I 5 6

ERC Minimum

48 46 -II 3-l 31 29 27 25 22

40 3-l 27 22 20

limits for specification Eardnesr, BRC Minimum Maximum 48 46 II 36 33 30 28 27 25 2-l 23 22 21 21 20

40 31 28 23 20

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 925 “C

Alloy Steel / 399

5130,5130H,

5130RH

CheITIiCSl COIIIpOSitiOn. 5130. AISI and UNS: 0.28 to 0.33 C. 0.70 to 0.90 Mn. 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.80 to 1.10 Cr. UNS H51300 and SAE/AlSI 5130H: 0.27 to 0.33 C, 0.60 to I .OO Mn, 0. I5 to 0.35 Si. 0.75 to I .20 Cr. SAE5130RH: 0.28 to 0.33 C, 0.70 to 0.90 Mn, 0. IS to 0.35 Si. 0.80 to I. IO Cr

Similar Steels (U.S. and/or Foreign). 5130. UNS G5 1300: SAE 5304. J412. 1770; (Ger.) DIN 1.7030; (U.K.) B.S. 530 A 30. 530 H 30. 513OH.llNS H51300; ASTM A304,A914;SAEJl268. Jl868;(Ger.) DIN 1.7033: (Fr.) AFNOR 32 C 3: (Ital.) UN1 31 Cr 4 KB: (Jap.) JIS SCr 2 H. SCr 2; (U.K.) B.S. 530 A 32.530 H 32 Characteristics. A medium-carbon alloy steel. Chromium is the sole alloying element; manganese in the range of 5 l30H is not considered an alloy. Hardenability is considered fairly high. Depending on the specific carbon content. as-quenched hardness in the range of approximately 16 to 53 HRC can be expected. Can be welded. but alloy steel welding practice is mandatory

Annealing. For a predominately pearlitic structure, heat to 845 “C (1555 “F), cool rapidly to 755 “C ( 1390 “F), then cool to 670 “C ( 1240 OF). at a rate not to exceed I I “C (20 “F) per h; or heat to 845 “C (1555 “F). cool rapidly IO 675 “C (1245 “F), and hold for 6 h. For a largely spheroidized structure, heat to 790 “C (1155 “F). cool rapidly to 690 “C (I275 “F), and hold for 8 h Hardening. Austenitize at 855 “C (IS70 “F), and quench in oil. Ion nitriding, gas nitriding. liquid carburizing. and gas carburizing are suitable processes Tempering.

Reheat after quenching the desired hardness

Recommended l l

Forging. temperature

Heat to 1230 “C (2250 “F) maximum. Do not forge after of forging stock drops beIon! approximately 870 “C ( I600 “F)

Recommended Normalizing.

Heat Treating Heat to 900 “C (I650

Practice “FL Cool in air

l l l l l

Processing

to the temperature

that will result in

Sequence

Forge Normalize Anneal (preferably spheroidize) Rough machine Austenitize and quench Temper Finish machine

5130: Hardness vs Tempering Temperature. Normalized at 900 “C (1650 “F), quenched

from 870 “C (1600 “F) in water.

tempered

in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel

400 / Heat Treater’s

Guide

5130H: End-Quench Hardenability Distance from quenched surface !j6iu. mm

Eardnes. ERC min max

Distance from quenched surface Qhin. mm

Hardness. HRC man min

5130: Depth of Case vs Time and Temperature. 57.2 mm (2.25 in.) outside diameter by 165 mm (6.5 in.), oil quenched. ized at temperatures indicated

Carbur-

Alloy Steel / 401

5130H: Hardenability (1650 “F). Austenitize:

Hardness purposes I distance, nm I .5

iardness 3urposes I distance, /ifI in.

0 I 7 ; -I s 6 8 !O 12 !-I !6 !8 0 P

Curves. Heat-treating 870 “C (1600 “F)

limits for specification Elardness, HRC Maximum Minimum 56 55 s3 51 48 45 -I’ 39 35 33 31 30 28 26 2-l

49 46 12 37 33 30 21 2.5 21

limits for specification Hardness, HRC Maximum Minimum 56 ss 53 51 49 17 IS -12 40 38 37 36 3s 34 34 33 32 31 30 29 27 26 2s 2-l

49 46 43 39 35 32 30 18 26 2s 23 ‘2 21 20

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 900 “C

402 / Heat Treater’s

Guide

5130RH: Hardenability

Curves. Heat-treating

“C (1650 “F). Austenitiie:

870 “C (1600 “F)

Hardness purposes

limits for specification

I distance.

Elardness, Maximum

‘/,6 in. I 2 3 1 5 5 7 B 3 10 II II 13 I4 IS 16 I8 20 22 2-l 26 28 30 32

Hardness purposes J distance, mm I.5 3 5 7 9 II I3 I5 20 IS 30 35 40 xi 50

EIRC Minimum 50 47 44 41 37 35 33 31 29 27 1-6 25 24 23 32 21 20

55 53 51 49 46 44 42 39 31 35 34 33 32 31 30 29 28 27 26 2s 24 23 22 ‘I

limits for specification Elardoess, Maximum 55 53 51 48 45 42 39 36 32 29 28 26 74 23 21

BRC Minimum 50 47 4-l 39 36 33 31 28 2-I 21 ‘0

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 900

Alloy Steel / 403

5132,5132H Chemical

Composition. 5132. AISI and UNS: 0.30 to 0.35 C. 0.60 IO 0.80 Mn. 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.75 to 1.00 Cr. UNS A51320 and SAE/AISI 51328: 0.7-9to 0.35 C. 0.50 to 0.90 hln. 0. IS to 0.35 Si. 0.65 to I. IO Cr Similar

Steels (U.S. and/or Foreign).

5132.

UNS

GS 1320;

ASTM A322, A331, A505, ASl9: SAE J404. J-412, 5770; (Ger.) DIN I .7033; (Fr.) AFNOR 32 C 4; (Ital.) UN1 34 Cr 4 KB; (Jap.) JIS SCr 2 H. SCr 2: (U.K.) B.S. 530 A 32, 530 H 32. 51328. LINS HSl320: ASTM A304: SAE J1268; (Ger.) DfN 1.7034: (Fr.) AFNOR 38 C 4; (Ital.) 1lNI 38 Cr -I KB; (Jap.) JIS SCr 3 H; (U.K.) B.S. 530 A 36.530 H 36, Type 3

Characteristics.

Varies only slightly in composition from Sl30H. General characteristics are essentially the same as those for 5130H. The slightly higher carbon range of 5 l32H raises the maximum as-quenched hardness to approximately 48 to 55 HRC. although the hardenability of 5 l32H can be slightly less than that of 5 I30H because of the possibility of a lower chromium content. This grade can be welded. but alloy steel welding practice is mandatory

rate not to exceed I I “C (20 “F) per h: or heat to 845 “C (1555 “F), cool rapidly to 675 “C (I245 “F), and hold for 6 h. For a largely spheroidized structure. heat to 790 “C ( 1455 “F). cool rapidly to 690 “C (I 275 “F), and

hold for 8 h

Hardening. nitriding

Austenitize and gas nitriding

at 855 “C (IS70 “F), and quench are suitable processes

Tempering.

Reheat after quenching the desired hardness

Recommended l l l l l l l

Processing

to the temperature

in oil. Ion

that will result in

Sequence

Forge Normalize Anneal (preferably spheroidize) Rough machine Austenitize and quench Temper Finish machine

Forging.

Heat to 1230 “C (2250 “F) maximum. Do not forge after temperature of forging stock drops below approximately 870 “C (I600 “F)

Recommended Normalizing. Annealing. ‘F). cool rapidly

Heat Treating

Practice 5132: Microstructure.

Heat to 900 “C ( I650 “F). Cool in air For a predominately pearlitic structure. heat to 815 “C (I 555 to 755 “C ( I390 “F), then cool to 670 “C ( I230 “F), at a

5132, 5132H: Hardness vs Tempering Temperature.

Repre-

sents an average based on a fully quenched structure

5132H: End-Quench Hardenability Distance from quenched surface V~6in. mm I 7 i 4

5 6 7 8 9 10 II I2

I.58 3.16 4.74 6.32 7.90 9.48 Il.06 12.64 14.22 IS.80 17.38 18.96

Eardoess, HRC max mia 57 56 5-l 52 SO -la 1s 42 40 38 37 36

SO -17 -I3 40 35 32 29 27 25 24 ‘3 22

Distance from quenched surface ‘116in. mm I3 II I5 I6 I8 20 ‘2 21 26 ‘8 30 32

20 s-t 72.11 23 70 25.28 28.44 31.60 34.76 37.92 -Il.08 44.2-l -17.10 50.56

Hardness, HRC max min 35 3-1 31 33 32 31 30 29 38 27 26 25

21 20

.._

.._

.

Nital, 1650x. Steel forging, austenitized at 645 “C (1555 “F) and water quenched. Some blocky ferrite (light areas) and bainite (dark, feathery constituent) in a matrix of marlensite

404 / Heat Treater’s

Guide

5132H: Hardenability (1650 “F). Austenitize:

Curves. Heat-treating 845 “C (1555 “F)

Hardness limits for specification wrposes I distance. nm

Hardness, HRC hlinimum Maximum

I.5

57

50

II 13 IS !O !5 10 15 U) 15 i0

56 51 5’ 49 45 4’ 39 35 33 .-1’ 31 29 27 25

47 43 38 33 29 ‘6 35 II

iardness wrposes I distance, 116io.

0 I 7 ; -I 5 6 8 !O I2 I4 16 18 10 i?

limits for specification Eardness, HRC hlinimum Maximum 51 56 s-1 52 50 48 46 42 40 38 37 36 3s 3-I 3-1 33 32 31 30 29 28 27 26 ‘S

50 -17 43 -IO 3s 32. 29 27 3 2-l 23 22 21 20

temperatures

recommended

by SAE. Normalize (forforged

or rolled specimens

only): 900 “C

Alloy Steel / 405

5135,5135H Chemical Composition. 5135. AISI and UNS: 0.33 IO 0.38 C. 0.60 10 0.80 Mn. 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.80 to I.05 Cr. UNSH513SOand SAE/AISI513SH:0.32 to0.3XC.0.50to0.90Mn.0.15 to 0.35 Si. 0.70 to I. I5 Cr Similar Steels (U.S. and/or Foreign).

5135. l!NS GS 1350; ASThI .43X. A33l. ASIY: SAE J4O-l. 5412.1770; Ger.) DIN I.7034 (Fr.) AFNOR 38 C 1: (Ital.) LlNl 38 Cr 4 KB: (Jap.~ JIS SCr 3 H: (U.K.) B.S. 530 A 36.530 H 3.51358. LlNS HS 1350; ASTM A30-k SAE J 1268; (Ger.) DIN 1.7035; (Fr.j AFNOR -I2 C -1: (Ital.) UN1 -II Cr -I KB, 40 Cr -I: (Jap.~

JIS SCr -1 H; (U.K.) B.S. 530 A 10,530 H -IO. 530 hl10.2

S I I7

Characteristics.

A low-allo) version of the carbon steels 1035 and 1038H. Because of the chromium addition. hardenahility of 513SH is considerably greater than for 1038H. When fully quenched. an as-quenched hardness of approsimatelq SO to 56 HRC can he expected. Can he welded. hut is susceptible to Lteld cracliing

Annealing.

For a predominately pearlitic structure, heat to 830 “C (I525 “F). cool rapidly to 740 “C ( 136s “F). then cool to 670 “C ( I140 “F), at a rate not to exceed I I “C (20 “F) per h: or heat to 830 “C ( I525 “F), cool rapidly to 675 “C ( IX “F). and hold for 6 h. For a predominately spheroidized structure. heat to 750 “C (I380 “F). cool rapidly to 690 “C (1275 OF). and hold for 8 h

Hardening. nitriding

Tempering.

Forging.

Heat to 1230 “C (3750 “FI maximum. Do not forge after of forging stock drops helow approximateI) 870 ‘C ( 1600 “F)

Recommended l l

l l l

Recommended Heat Treating Practice Normalizing. Heat to 870 “C ( I600 “F). Cool in air

After

at 815 “C (I555 “F). and quench are suitable processes

quenching.

reheat to the temperarure

in oil. Ion required

obtaining the desired hardness

l

temperature

Austenitize and gas nitridinp

l

Processing

Sequence

Forge Normalize Anneal (,preferahly spheroidize, Rough machine Austenitize and quench Temper Finish machine

5135, 5135H: Hardness vs Tempering Temperature. Represents an average

5135H: End-Quench Hardenability Distance from ‘/16in.

mm

Hardness, HRC min ma\

I

1.58 3.16 4.14 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38 18.96

57 56 55 54 52 50 47 45 43 41 40

quenched surface

2 3 4 5 6 7 8 9 10 11 12

58

51 -VI 47 43 38 35 32 30 28 27 25 24

Distance from quenched surface l/16 in. mm

13 14 15 16 18 20 22 24 26 28 30 32

20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40 50.56

Hardness,

HRC max

min

39 38 37 37 36 35 3-l 33

23 22 21 21 20

32

32 31 30

based

on a fully quenched

structure

for

406 / Heat Treater’s Guide

5135H: Hardenability Curves. Heat-treating temperatures (1800 OF). Austenitize:

845 “C (1555 “F)

Hardness limits for specification purposes J distance, mm 1.5 3 5 I 9 11 13 1.5 20 25 30 35 40 45 50

Eardness. ERC Maximum Minimum 58 58 56 54 53 50 47 44 40 37 35 3-l 33 32 31

51 19 46

41 36 32 30 27 2.3 21

Hardness limits for specification purposes I distance, I116in.

I

1

3 IO

I1 12 13 14 15 16 I8 !O !2 !4 !6 !8 IO 12

Eardnes.

MZIXhWfl 58 57 56 55 54 52 50 47 45 43 41 40 39 38 37 37 36 35 34 33 32 32 31 30

EIRC

Minimum 51

49 47 -I3 38 3s 32 30 ‘8 27 25 24 23 22 21 21 20

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

Alloy Steel / 407

5140,5140H, Chemical

5140RH

Composition.

5140. AISI and UNS: 0.38 to 0.43 C, 0.70

to 0.90 Mn, 0.035 P max. 0.040 S max. 0. I5 to 0.30 Si. 0.70 to 0.90 Cr. UNS H51400 and SAE/AISI 5140H: 0.37 to 0.44 C. 0.60 to I .OO Mn. 0. I5 to 0.35 Si, 0.60 to 1.00 Cr. SAE 514ORH: 0.38 to 0.43 C. 0.70 to 0.90 Mn. 0. I5 to 0.35 Si. 0.70 to 0.90 Cr

Similar

Steels (U.S. and/or Foreign). 5140. UNS ~51400; ASTM A322. A33 I, A505. A5 19; SAE J404, J-il2. J770; (Ger.) DIN I .7035; (Fr.) AFNOR 42 C 4; (Ital.) UNI 40 Cr 3. II Cr 4 KB; (Jap.) JIS SCr-1H;(U.K.)B.S.530A40.530H~,530M40,2Sll7.51~0R.UNS H5 1400; ASTM A304. A914; SAE J 1268, J 1868; (Ger.) DIN I .7006; (Fr.) AFNOR42C2.45CZ Characteristics. The characteristics described for 5 I35H generally apply for 5140H. Because the carbon range is higher, slightly higher as-quenched hardness of approximately 5 I to 57 HRC can be expected. The possibility of a slightly lower chromium content for 5lJOH makes no significant difference in hardenability. This grade can be welded. but is susceptible to weld cracking Forging. temperature

Heat to 1230 “C (2250 “F) maximum. Do not forge after of forging stock drops below approximately 870 “C (I 600 “F)

Recommended Normalizing.

Heat Treating

Practice

Annealing.

For a predominately pearlitic structure, heat to 830 “C (1525 “F), cool rapidly to 740 “C ( I365 “F). then cool to 670 “C ( I240 “F), at a rate not to exceed I I “C (20 OF) per h; or heat to 830 “C (I 525 “F). cool rapidly to 675 “C (I 245 “F), and hold for 6 h. For a spheroidized structure. heat to 750 “C (I 380 “F), cool rapidly to 690 “C (I 275 “F). and hold for 8 h

Hardening. Austenitize at 8-0 “C (1555 “F), and quench in oil. Ion nitriding, gas nitriding, carbonitriding, austempering and mat-tempering are alternative processes Tempering. obtaining

After quenching, the desired hardness

Recommended l l l l l l l

reheat to the temperature

Processing

required

for

Sequence

Forge Normalize Anneal (preferably spheroidize) Rough machine Austenitize and quench Temper Finish machine

Heat to 870 “C ( I600 “F). Cool in air

5140: Isothermal Transformation C. 0.68 Mn, 0.93 Cr. Austenitized 6 to 7

Diagram. Composition: 0.42 at 845 “C (1555 “F). Grain size:

5140: Hardness vs Tempering Temperature. Normalized at 870 “C (1600 “F), quenched from 845 “C (1555 “F) in oil, tempered in 56 “C (100 “F) intervals in 13.8 mm (0.545 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel

408 / Heat Treater’s

1 2 3 4 5 6 7 8 9 IO II 12

I .58 3.16 4.74 6.32 7.90 9.48 II.06 12.64 11.22 15.80 17.38 18.96

60 59 58 57 56 5-l 52 SO 48 -16 45 43

Guide

53 52 50 48 -I3 38 35 33 31 30 29 28

I3 II I5 I6 I8 20 22 ‘4 26 28 30 32

20.5-I 22.12 23.70 25.28 28.U 31.60 31.76 37.92 -11.08 44.24 -17.-w 50.56

32 40 39 38 37 36 35 3-l 3-l 33 33 32

27 ‘7 35 25 24 23 21 20

5140: End-Quench Hardenability. Composition: 0.43 C, 0.80 Mn, 0.010 P 0.050 S, 0.26 Si, 0.02 Ni, 0.84 Cr, 0.02 MO. Grain size: 7 to 8. Austenitized

5140:

at 955 “C (1750 “F) as in production and austenitized

As-Quenched

Hardness

at 845 “C (1555 “F) in accordance

(Oil)

Single heat results; grade: 0.38 to 0.43 C, 0.70 to 0.90 Mn, 0.20 to 0.35 Si, 0.70 to 0.90 Cr; ladle: 0.43 C, 0.78 Mn, 0.020 P, 0.033 S, 0.22 Si, 0.06 Ni. 0.74 Cr, 0.01 MO; grain size 6 to 8

Surface

Eurdness, ERC ‘/2 radius

57 53 46 35

57 48 38 29

Size round in. f.4

i 2 .I

mm I3 ‘5 51 102

Source: Bethlehem Steel

Center 56 -15 35 20

with hardenability

specifications

Alloy

5140: Continuous

Cooling Curves. Composition: 0.42 C, 0.87 Mn. 0.25 Si, 0.89 Cr. Austenitized at 845 “C (1555 “F). Grain size: 8. AC,, 805 “C (1480 “F); AC,, 750 “C (1380 “F). A: austenite, F: ferrite, P: pearlite, B: bainite, M: martensite. Source: Bethlehem Steel

Steel / 409

5140: Tempering Temperature vs Furnace Cooling and Water Quenching. Tempered at 620 “C (1150 “F) for2 h. Source: Climax Molybdenum

5140: Distribution

of Case Depth after Carbonitriding. Carbonitrided at 775 “C (1425 OF) for 8 h and quenched in oil at 77 “C (170 “F). 25 tests on a steel pinion shaft

410 / Heat Treater’s

Guide

5140H: Hardenability (1800 “F). Austenitize:

Hardness purposes J distance, mm

limits for specification q ardness, ERC Maximum Minimum

1.5

60

3 5 7 9 II 13 I5 20 ‘5 30 35 -lo 45 50

59 58 51 55 53 50 47 42 39 36 35 34 33 32

Hardness purposes J distance, 916in. I 1 s i 5 5 7 3 3 IO

II II 13 I4 15 I6 18 !O !2 !-I !6 !8 lo 12

Curves. Heat-treating 845 “C (1555 “F)

53 52 50 35 40 35 32 30 28 25 23 21

limits for specification Eardness, ARC Maximum Minimum 60 59 58 57 56 5-l 52 50 48 46 45 43 42 40 39 38 37 36 35 31 34 33 33 32

53 52 SO 48 43 38 35 33 31 30 29 28 27 27 26 25 2-l 23 ‘I ‘0

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

Alloy Steel / 411

5140RH: Hardenability

Curves. Heat-treating

“C (1600 “F). Austenitize:

Hardness purposes I distance, ‘/,6 in. I

5 1 3 2 IO II I?

I3 I4 I5 lb I8 10 22 14 16 18 30 32

Hardness purposes J distance, mm I.5 3 5 7 9 II 13 I5 20 25 30 3s 40 -Is 50

845 “C (1555 “F)

limits for specification Eardness, EIRC Maximum

Minimum

59 58 57 55 53 51 18 -I6 4-l 13 II 40 39 37 36 35 34 33 32 31 30 30 29 29

54 53 51 49 45 ?I 38 36 34 33 32 31 30 29 28 27 26 25 34 23 22 21 20

limits for specification Eardness, BRC Minimum Mximum 59 58 57 55 52 18 46 4-l 39 35 33 32 31 30 29

5-l 53 51 -I7 42 38 36 3-l 30 27 3 2-l 22 21 20

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870

412 / Heat Treater’s

Guide

5147H Chemical to 0.57

Similar SAE

UN.3 HSlJ70and

COIIIpOSitiOn. C. 0.60 to I .05 Mn.

J-W

0. IS IO 0.35

Steels (U.S. and/or or J-l 13. but does appeu

.SAE/AISI 5147H: 0.4.5

Si. 0.80

Foreign). in SAE

5770.

to 1.3

This steel is no longer which is nou J I397

5147H: Hardenability

Curves. Heat-treating

(1600 “F). Austenitize:

845 “C (1555 “F)

Hardness purposes J distaace. mm I.S 3 5 1

9 II 13 1s 20 3 30 35 +o -Is 50

Recommended

Heat Treating

Practice

Cr

temperatures

in

Hardening.

recommended

Gas niukiing

and ion nitriding

are suitable

by SAE. Normalize (for forged or rolled specimens

processes

only): 870 “C

limits for specification Eardoess,

Maximum 61 61 64 63 62 61 60 60 58 57 ss 53 52 SO 19

H RC Minimum 57 56 55 53 5’ i; u 39 33 31 29 27 25 23 21

(continued)

Alloy Steel / 413

5147H: Hardenability

Curves. (continued) Heat-treating

only): 870 “C (1600 “F). Austenitize:

Hardness purposes J distance, 1.. . /16m.

1 2 3 4 5 6 I 8 9 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32

845 “C (1555 OF)

limits for specification Hardness, HRC Maximum Minimum

64 64 63 62 62 61 61 60 60 59 59 58 58 57 51 56 55 54 53 52 51 50 49 48

57 56 55 54 53 52 49 45 40 37 35 34 33 32 32 31 30 29 21 26 25 24 22 21

temperatures

recommended

by SAE. Normalize

(for forged or rolled specimens

414 / Heat Treater’s

Guide

5150,515OH Chemical

Composition.

5150. AISI and UN% 0.4 IO 0.53 C. 0.70

to 0.90 Mn. 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.70 to 0.90 Cr. UNS EI515OOand SAE/AISI 515OH: 0.47 to 0.54 C. 0.60 to I .OO Mn. 0. I5 to 0.35 Si. 0.60 to 1.00 Cr

Similar

Steels (U.S. and/or

ASTM A322. A33l. I .7006: (Fr.) AFNOR

Foreign). 5150. UNS G5 1500; A505, ASl9; SAE J-W, JJl2. 5770: (Ger.) DIN 42 C 2,45 C 2.5150H. UNS H5 1500: ASTM A30-k

SAE Jl268

Annealing.

For a predominately pearlitic structure, heat to 830 “C (I 525 “F). cool rapidly to 705 “C ( I300 “F). then cool to 650 “C (I 200 “F), at a rate not to exceed I I “C (20 “F) per h; or heat to 830 “C ( IS25 “F). cool rapidly to 675 “C ( 1245 “F). and hold for 6 h. For a predominately spheroidized structure, heat to 750 ‘C (I380 “F), cool rapidly to 705 “C ( I300 “F). then cool to 650 “C ( I200 “F). at a rate not to exceed 6 “C (IO “F) per h: or heat to 750 “C ( 1380 “F). cool rapidly to 675 “C ( I245 “F), and hold for IO h

Hardening.

Characteristics.

Has a borderline carbon content. between a mediumcarbon and a high-carbon steel. When fully hardened, an as-quenched hardness of approximately 55 to 60 HRC is normal, slightly higher when the carbon is near the maximum of the allowable range. Hardenability is also considered as relatively high. Because of the high carbon content and the high hardenability, does not have good weldability

nitriding,

Tempering.

After quenching. vide the desired hardness

Recommended l

Forging. temperature

Heat to 1220 “C (2225 “F) maximum. Do not forge after of forging stock drops below approximately 870 “C ( 1600 “F)

l l l

Recommended

Heat Treating

Practice

l l

Normalizing.

Heat to 870 “C (1600 “F). Cool in air

Austenitize at 830 “C (IS25 “F), and quench in oil. Gas fluidized bed nhriding. and ion nitriding are suitable processes

l

reheat to the temperature

Processing

required

to pro-

Sequence

Forge Normalize Anneal (preferably spheroidire) Rough machine Austenitize and quench Temper Finish machine

5150: Isothermal Transformation Diagram. Composition: 0.48 C, 0.86 Mn, 0.023 P, 0.021 S, 0.25 Si, 0.18 Ni, 0.98 Cr, 0.04 MO. 0.09 Cu. Austenitized at 860 “C (1580 “F). Grain size 5 to 6

5150, 5150H: Hardness vs Tempering Temperature. sents an average based on a fully quenched structure

Repre-

Alloy Steel / 415

5150: Hardness vs Tempering Temperature. Normalized at 870 “C (1800 “F), quenched from 845 “C (1555 “F), tempered in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel

5150H: End-Quench Hardenability Distance from

Distance from quenched surface ‘&jin. mm

Hardness, ERC max min 1.58 3.16 -4.71 6.32 7.90 9.18 I I.06 12.64 IA.22 IS.80 17.38 18.96

2 3 .I 5 h 7 8 9 IO II 12

65 65 64 63 62 61 60 59 58 56 55 53

5150: As-Quenched

59 S8 57 56 53 49 42 38 36 31 33 33

13 I-l 1s 16 I8 20 22 21 26 28 30 32

Hardness

20.54 22.12 23.70 25.28 28.4-l 31.60 31.76 37.92 11.08 44.21 47.40 50.56

Eardoess, ERC min max 51 SO 48 -17 15 13 42 -II 40 39 39 38

31 31 30 30 29 28 27 26 2s 24 23 22

(Oil)

Single heat results; grade: 0.48 to 0.53 C, 0.70 to 0.90 Mn, 0.20 to 0.35Si,0.70to0.90Cr,ladle:0.49C,0.75Mn,0.018P,0.018S,0.25 Si, 0.11 Ni, 0.80 Cr, 0.05 MO; grain size 7 to 8

in.

Size round mm

Surface

Hardness, HRC ‘/: radius

Center

‘/> I 2 4

I3 25 51 I02

60 59 55 37

60 52 -l-l 31

59 50 40 29

Source: Bethlehem Steel

416 / Heat Treater’s

Guide

5150H: Hardenability

Curves. Heat-treating 845 “C (1555 “F)

(1600 “F). Austenitize:

iardness wrposes

limits for specification

I distance,

Rardnes, Maximum

q m

1.5 1

3 II

13 15 !O !5 10 I5 lo 15 i0

iardness wrposes I distance, 46 in.

1 8 9 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32

RRC Minimum

65 65 64 63 62 60 58 51 52 47 44 42 40 39 38

59 58 57 54 50 43 37 35 31 29 28 27 26 24 22

limits for specification Eardness, ARC hlioimum Maximum 65 65 64 63 62 61 60 59 58 56 55 53 51 50 48 47 45 43 42 41 40 39 39 38

59 58 57 56 53 49 42 38 36 34 33 32 31 31 30 30 29 28 27 26 25 24 23 22

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

Alloy Steel I417

5155,5155H Chemical

Composition.

5155. AISI and UNS: 0.5 1 to 0.59 C, 0.70 0.040 S max. 0.1s to 0.30 Si. 0.70 to 0.90 Cr. UNS H51550and SAE/AISI 51558: 0.50 to 0.6OC. 0.60 to I .OO Mn. 0. IS

to 0.90 Mn. 0.035 P

max.

to 0.30 Si. 0.60 to I .OO Cr

Similar

Steels (U.S. and/or Foreign). 5155. UNS GSISSO: ASTM A322, A33 I. AS 19: SAE J4O-l. J-II 2. J770; (Ger.) DUV I .7 176: (Fr.) AFNOR SS C 3. 51558. UNS HS 1550; ASThl A30-l: SAE J 1268; (Ger.) DIN I .7 176: (Fr.) AFNOR 55 C 3 Characteristics.

In general. the characteristics of 5 ISSH are the same as those discussed for 5 ISOH. However. the slightI> higher carbon range of SISSH makes a higher as-quenched hardness possible. 57 to 63 HRC is normal for fully quenched 5 I SSH. Although the hardenability patterns of 5 ISOH and 5 ISSH are similar. the entire band is slightI> higher for 5 ISSH. Because of the high carbon content and the high hardenabilitj, this grade does not have good weldability

Forging.

Heat to I 220 “C (2% “F) maximum. Do not forge after temperature of forging stock drops bslok+ approximateI> 870 “C t I600 “F)

Annealing.

For a predominately pearlitic structure, heat to 830 “C (I 525 “F). cool rapidly to 705 “C ( I300 “FL then cool to 650 “C ( 1200 “F). at a rate not to exceed I I “C (20 “F) per h; or heat to 830 “C (IS25 “F), cool rapidly to 675 “C t I315 “F), and hold for 6 h. For a predominately spheroidized structure. heat to 750 “C ( I380 “F), cool rapidly to 705 “C i I300 “F). then cool to 650 “C ( I200 “F), at a rate not to exceed 6 “C (IO “F) per h: or heat to 750 “C ( I380 “F). cool rapidly to 675 “C (I 245 “F). and hold for IO h

Hardening. nitriding

Heat Treating

Practice

After quenching. vide the desired hardness

Recommended l l l

l l

Normalizing.

Heat to 870 “C i 1600 “F). Cool in air

at 830 “C (IS25 “F), and quench in oil. Gas are suitable processes

Tempering.

l

Recommended

Austenitire and ion nitriding

l

Processing

5155, 5155H: Hardness

Dicmnce from quenched surface ‘/,6 in. mm I

Hardness. ARC max min

Distance from quenched surface %6 in. mm

Hardness, ARC min max

1.58 4.74 3.16

64 65

h0 58 59

13 I-l IS

20.54 22. II 23.70

1

6.32

6-l

57

16

25.28

31

5

7.90 9.48 II.06 12.6-I l-I.31 1580 17.38 18.96

63 63 62 62 61 60 59 57

55 52 -17 II 37 36 35 3-l

18 20 22 7-I 16 28 30 32

28.4-l 3 I .6O 31.76 37.92 41 08 44.2-l 17.10 50.56

31 31 30 29 28 27 xl 25

7 x 9

IO II

ss 51 52

3-l 33

;-3

h

II

Hardenability

required to pro-

Sequence

Forge Normalize Anneal (preferably spheroidire) Rough machine Austenitize and quench Temper Finish machine

sents an average

5155H: End-Quench

reheat to the temperature

based

vs Tempering

Temperature.

on a fully quenched

structure

Repre-

418 / Heat Treater’s

Guide

5155H: Hardenability

Curves. Heat-treating temperatures 845 “C (1555 “F) -

(1600 “F). Austenik

Hardness purposes J distance, mm 1.5 3 5 7 9 11 13 15 20 25 30 35 40 45 50

Hardness purposes J distance, %6in.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32

limits for specification Eardness, EIRC Maximum MillhllUll

.. 65 65 64 64 63 61 60 56 50 46 44 43 42 41

60 60 59 56 53 48 40 37 34 32 30 29 28 27 25

limits for specification Hardness, ARC MSlXimlUU Minimum

.

60

65 64 64 63 63 62 62 61 60 59 51 55 52 51 49 47 45 44 43 42 41 41 40

59 58 51 55 52 47 41 31 36 35 34 34 33 33 32 31 31 30 29 28 27 26 25

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

1

Alloy Steel / 419

5160,5160H,

5160RH

Chemical

Composition. 5160. AISI and UNS: 0.56 to 0.63 C. 0.75 to I .OOMn, 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.70 to 0.90 Cr. UNS H51600 and SAE/AISI 516OH: 0.55 to 0.65 C. 0.65 to I .OO Mn, 0. I5 to 0.35 Si, 0.60 to I.00 Cr. SAE 516ORH: 0.56 to 0.6-t C, 0.75 to I .OO Mn.

0. IS to 0.35 Si, 0.70 to 0.90 Cr

Similar

Steels (U.S. and/or

Foreign).

ASTM A322 A33l. A505. ASl9; SAE J-W H51600:ASThlA30&A914:SAE51268,J1868

5160.

UNS G51600; 5412. 5770. 5160H. UNS

Characteristics.

Detinitely considered a high-carbon alloy steel. Asquenched hardness of 58 to 63 HRC is considered normal. Sometimes values higher than this range are obtained, depending on the precise carbon content. Hardenability is slightly higher than that of 5lSSH. Used for a variety of spring- applications. notably flat springs. Often uses austempering .. as a method of heat treating

Forging. temperature

Heat to 1205 “C t2300 “F) maximum. Do not forge after of forging stock drops below approximately 870 “C (1600 “F)

rapidly to 675 “C (I215 “F). and hold for 6 h. For a predominately spheroidized structure, heat to 750 “C (I 380 “F). cool rapidly to 705 “C (1300 “F). then cool to 650 “C (I 200 “F). at a rate not to exceed 6 “C (IO “F) per h: or heat to 750 “C ( I380 “F). cool rapidly to 675 “C (1245 “F), and hold for IO h

Hardening. polymer.

Tempering.

After quenching, vide the desired hardness

Recommended Annealing.

Heat Treating

Practice

Heat to 870 “C ( I600 “F). Cool in air

For a predominately pearlitic structure. heat to 830 “C ( I525 “F). cool rapidly to 705 “C ( I300 “F). then cool to 650 “C ( 1200 “F). at a rate not to exceed I I “C (20 “F) per h; or heat to 830 “C ( IS25 “F). cool

reheat to the temperature

in oil or

required to pro-

Austempering.

Austenitize at 845 “C (I 555 “F), quench in molten salt at 315 “C (600 “F), and hold for I h. Parts are cooled in air from 315 “C (600 “F) and need no tempering. A spring temper hardness within the range of approximately 16 to 52 HRC is obtained

Recommended l

Normalizing.

Austenitize at 830 “C (IS25 “F), and quench Gas nitriding and ion nitriding are suitable processes

l l l l l l

Processing

Sequence

Forge Normalize Anneal (preferably spheroidize) Rough machine Austenitize and quench (or austemper) Temper (or austemper) Finish machine

5160: Isothermal Transformation

Diagram. Composition:

C, 0.94 Mn, 0.88 Cr, 0.22 MO. Austenitized Grain size 7

0.61 at 845 “C (1555 “F).

420 / Heat Treater’s

Guide

5160: Correlation of Annealing Practice with Surface Finish andTool Life in Subsequent Machining. (a) Annealed (pearlitic) microstructure, 241 HB, and surface finish of flange after machining eight pieces. (b) Partially spheroidized microstructure, 180 HB, and surface finish of flange after machining 123 pieces

5160: Hardness vs Tempering Temperature. Normalized at 870 “C (1600 “F), quenched from 845 “C (1555 “F) in oil, tempered in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel

5160:

As-Quenched

Hardness

(Oil)

Single heat results; grade: 0.56 to 0.64 C. 0.75 to 1 .OO Mn, 0.20 to 0.30Si,0.70to0.90Cr;ladle:0.62C.0.84Mn,0.010P,0.034S,0.24 Si, 0.04 Ni. 0.74 Cr, 0.01 MO; grain size: 6 to 8 Size round in.

mm

Surface 63 62 53 40

Aardness, ERC ‘/z radius 62 61 46 32

Center 62 60 43 29

Alloy Steel / 421

5160H: End-Quench Hardenability Distance from quenched surface &in. mm

Hardness, ERC max min

Distance from quenched surface ‘/lb in. mm

Hardness, ERC mas min

I ;')

I.58 4.74 3.16

.::

60 60

I3 IS I-I

20.51 23.70 22.11

58 5-l 56

3s 3-l 35

-I 5 6

6.5 65 6-l 61 63 62 61 60

99 58 56 5' 37 -I-' 39 37

16 I8 20 2' 2-l 30 26 28

2.5 28 18.U 3 I .60 34.76 37.91 4-4.2-l 47.40 -I I .0x

52 48 47 46 -IS -I? u -43

34 33 32

8 III90

6.31 7.90 9.48 Il.06 12.6-l l-l I7 IS 3x 80 22

;Lj

I2

I896

59

36

32

SO26

-I2

27

7

5160: Continuous

Cooling Curves. Composition: 0.63 C, 0.86 Mn, 0.23 Si, 0.83 Cr. Austenitized at 845 “C (1555 “F). Grain size: 7 ‘Is. AC,, 780 “C (1435 “F); AC,, 755 “C (1390 “F). A: austenite, F: ferrite, P: pearlite, B: bainite, M: martensite. Source: Bethlehem Steel

5160:

Section

Thickness

vs

Austempered

Hardness.

Quenched in agitated salt containing some water. Rockwell C hardness values converted from microhardness readings taken with a 100 g (3.53 oz) load. Low values of surface hardness result from decarburization. (a) 24.6 mm (0.967 in.) diam. Austenitized at 900 “C (1650 “F) and quenched in salt at 300 “C (570 “F) for 15 min. High hardness at center because of segregation. (b) 26.29 mm (1.035 in.) diam. Austenitized at 940 “C (1725 “F) and quenched in salt at 315 “C (600 “F) for 15 min

422 / Heat Treater’s

5160: Microstructures.

Guide

(a) 4% picral with 0.05% HCI. 500x. Hot rolled coil-spring steel, austenitized at 870 “C (1600 “F) for 30 min and oil quenched. Untempered martensite (dark, needlelike constituent) and retained austenite (light constituent). (b) 4% nital. 4% picral, mixed 1 to 1: 1000x. Same steel and heat treatment as (a), except at a higher magnification. Untempered martensite (dark gray constituent) and the retained austenite (light constituent are now more clearly resolved). (c) 4% nital. 4% picral, mixed 1 to 1; 1000x. Same steel as (a), except tempered at 205 “C (400 “F) after austenitizing and quenching. Predominantly tempered martensite (dark), with small particles of ferrite (white). (d) 2% nital. 11Ox. Spring steel, 16.1 mm (0.632 in.) diam, austenitized at 870 “C (1600 “F) for 5 min, hot coiled, oil quenched at 60 “C (140 “F), tempered at 425 “C (795 “F) for 40 min. Note tempered martensite and decarburization. (e) 2% nital, 275x. Same steel and treatment as(d). except at a higher magnification. Surface decarburization (white area near top of micrograph) occurred in the bar mill, while the steel was at about 1150 “C (2100 “F). ( f) 4% nital, 4% picral, mixed 1 to 1; 1000x. Hot rolled steel. austenitized at 870 “C (1600 “F) for 30 min, oil quenched, tempered at 540 “C (1000 “F) for 1 h. Predominantly tempered martensite (dark). with some ferrite (white)

Alloy Steel I423

516OH: Hardenability Curves. Heat-treating temperatures recommended by SAE. Normalize (for forged or rolled specimens only): 870 “C (1800 “F). Austenitize: 845 “C (1555 “F) iardness wposes I distance,

lull

limits for specification Earducss, ERC Maximum Minimum

3

. I 3 5 0 s 0 5 0 5 0

iardness wrposes distance,

$6io.

1 0 I 2 3 4 5 6 8 0 2 4 6 8 0 2

65 64 64 62 58 53 49 46 44 42 41

60 60 60 59 57 52 46 40 36 34 32 30 28 27 27

limits for specification Hardness, ERC Maximum Minimum

65 65 64 64 63 62 61 60 59 58 56 54 52 48 47 46 45 44 33 43 42

60 60 60 59 58 56 s2 47 42 39 37 36 35 35 34 34 33 32 31 30 29 28 28 27

424 / Heat Treater’s

Guide

5160RH: Hardenability

Curves. Heat-treating

“C (1600 “F). Austenitize:

845 “C (1555 “F)

Hardness purposes J distance. !I,6in.

limits for specification Eardness, Maximum

I 2 3 4 5 6 7 8 9 IO II I2

65 6.5 6.i, 65 6-l 63 6Z 60 58 S6 55 s3

I3

51

I-l

SO

IS

?2

18 17 4-l -13 -II

?-I

II

16 18 30 32

40

I6 I8 10

Hardness purposes J distance, mm I .s

3 5

7 Y II I3 IS 20 75

30 3s

60 60 60 59 58 57 5-l SO 4s 32 40 39 38 37 36 36 3s 3-I 33 32 31 30 29 T!9

39 39 38

limits for specification Eardoess, Maximum 65 6.c 65 65 63 62 60 57 52 17 -I3 II

-lo

40

IS

39 38

so

BRC Minimum

ARC Minimum MI 60 60 59 57 5-t -I9 13 38 36 31 32 31 30 ‘9

temperatures

recommended

by SAE. Normalize

(for forged or rolled specimens

only): 870

Alloy Steel / 425

51 B60,51 Chemical

B60H

Composition.

51~60. AM: 0.56 to 0.6-1C. 0.75 to 1.00

hln. 0.035 P max. O.MO S mas. 0. IS to 0.30 Si. 0.70 to O.YO Cr. 0.0005 to 0.003 B. UNS: 0.56 too.64 C, 0.75 to 1.00 hln, 0.035 Pmax, O.O-lO S max. 0.15 to 0.30 Si, 0.70 to 0.90 Cr. 0.0005 B min. UNS H51601 and SAE/AISl51B60H: 0.55 to O.hS C. 0.65 to I. IO hln. 0. IS to 0.35 Si. 0.60 to I .OO Cr. B (can he expected to be 0.0005 to 0.003 percent)

Similar

Steels (U.S. and/or

Foreign).

51B60. UNS GSI 601:

.+,STILl ASl9: SAE J3O-i. 5112. 5770. 51B60H. A3o-t: SAE J I268

UNS HSl601:

ASTM

Characteristics.

With the exception of a slightly higher chromium content. 5 I B6OH has practicalI! the same characteristics as SOB60H. .bquenched hardness of 58 to 63 HRC can he expected. Hardenability of 51 BhOH is slightl) higher. because of the increase in chromrum

Forging. Heat to IlOS ‘C I 2300 “F) maximum. Do not forge after temperature of forging stock drops below approximutel! 925 “C (1695 “FL Because of high hardenability, forgmgs. especialI>; comples shapes. should he cooled slow I> from ths forging operation to mminize the possihilit} of crackinp. Forgings ma! he slob cooled by either placing them in a furnace or huqing them in an Insulating compound

For a prsdoninatel) spheroidized structure which is usually favored for this grade of steel. heat to 750 “C ( 1380 “F). cool rapidly to 700 ‘C ( 1190 “F). then cool to 655 “C ( I2 IO “F). at a rate not to exceed 6 “C t IO “F, per h: or heat to 750 ;‘C I 13X0 “F). cool rapidI) to 650 “C ( 1200 OF), and hold for 12 h

Hardening. nitridinp

Selection of tempering temperarure depends on the final properties desired. To prevent cracking, make sure parts have reached a uniform temperature throughout each section. and then place them in I tempering furnace hefore nmhient temperature is reached. 38 to SO “C (100 to I20 “F, is considered ideal

Recommended l l l l l

Heat to 870 “C I 1600 ‘FL Cool in air

l

Heat Treating

Austenitize at 815 “C ( IS55 “FL and quench in oil. Gas and ion niuidinp are suitnhle processes

Tempering.

Practice

Recommended Normalizing.

Annealing.

l

Processing

Sequence

Forge Normalize Anneal Rough and semitinish machine Austenitize and quench Temper Finish machine

51 B60: Isothermal

Transformation

0.64 C. 0.88 Mn, 0.83 Cr. 0.0006 “F). Grain size 6 to 7

51 B60: End-Quench Hardenability. Mn, 0.83 Cr. 0.0006 6 to 7

B. Austenitized

Diagram. Composition:

B. Austenitized

at 845 “C (1555

Composition: 0.64 C, 0.88 at 845 “C (1555°F). Grain size

426 / Heat Treater’s

Guide

51 B60: Hardness vs Tempering Temperature. Normalized at 870 “C (1600 “F), quenched from 845 “C (1555 “F) in oil, tempered in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel

51 B60H: End-Quench Distance from quenched surface

&h. 1 2 3 4 5 6 7 8 9 10 11 12

mm 1.58 3.16 4.75 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38 18.96

Hardenability

Hardness, ARC max min _..

.__ . . _.. 65

60 60 60 60 60 59 58 57 54 50 44 41

Distance from quenched surface

l/h5in.

mm

13 14 15 16 18 20 22 24 26 28 30 32

20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40 50.56

Hardness, HRC max min 65 64 64 63 61 59 57 55 53 51 49 47

40 39 38 37

28 27 25

51860: Microstructures. (a) Picral. 1000x. Hot rolled steel bar, 31.8 mm (1 l/4 in.) diam, austenitized at 870 “C (1600 “F), air cooled (normalized); austenitized at 815 “C (1500 “F), water quenched. Untempered martensite, some retained austenite (white), fine spheroidal carbide. (b) Nital, 1000x. Hot rolled steel bar, 13.8 mm (1 l/4 in.) diam, austenitized and quenched to obtain a martensitic structure, then heated to 675 “C (1245 “F) for 15 h. Spheroidal carbide particles in a matrix of ferrite

Alloy Steel / 427

51 B6OH: Hardenability Curves. Heat-treating “C (1600 “F). Austenitize: 845 “C (1555 “F)

Hardness purposes I distance. am

limits for specification Eardness, HRC Minimum Maximum

I .s

60

1 3 II 13 IS !O !S 10 1s lo IS 50

60 60 60 59 58 55 51 -IO 37 35 32 30 28 25

Hardness purposes I distance, &$in.

65 63 61 57 s-l 51 -17

limits for specification Eat-does, ERC Minimum hlaximum

3 ) IO II I2 I3 I-t I5 I6 18 31 !2 !-I ?6 !8 10 12

65 65 6-l 64 63 61 59 57 55 53 51 49 47

60 60 60 60 60 59 58 57 5-l 50 4-l II 40 39 38 37 36 31 33 31 30 28 27 'S

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870

428 / Heat Treater’s

Guide

E51100 Chemical Composition. AISI and UNS: 0.98 to 1.10 C. 0.25 to 0.45 hln. 0.025 P max. 0.025 S max. 0. IS to 0.30 Si. 0.90 to I .I5 Cr Similar Steels (U.S. and/or Foreign). 1lNS Gs 1986; AhlS 6443. 6446.6449: ASTM A295 A322, A505. A519:SAEJ4045412.J770: (Ger.) DIN I.3503

Characteristics. One of only two alloy steels listed bj NISI \\hich contain carbon of near 1.0% or higher. The E prefix in the designation indicates that it is manufactured only by the electric furnace process. which is further indicated by the IO\V contents of phosphorus and sulfur. This gade and its companion. E52 100, are sometimes called tool steels because their composition is nearly identical with L2 grade of tool steel. However. neither ES II00 or ES2 100 is made by what is commonly considered as tool steel practice; they are both made in relativelq large quantities. Although ES I 100 does sene many commercial applications. it is used most extensively as a material for ball and ball race rolling element bearings. for which extremely high hardness is needed. There is no H version of this steel because the end-quench test is not often used to evaluate hardenabilitj of the VS~ high-carbon grades. It is. ho\rever. generally considered an oil-hardemng steel. so that its hardenability is considered as fairly high. As-quenched hardness generally ranges from 62 to 66 HRC. depending on the cooling power of the quenchant Forging. temperature

Heat to II50 “C (2100 “F) masimum. of forging stock drops below approximately

Annealing. For a predominantl! spheroidized structure. which is generally desired for machining as \\ell as heat treating. heat to 795 “C (1460°F). cool rapid11 to 750 “C t I380 “F). then cool to 675 “C. ( I345 “FL at a rate not to exceed 6 “C (IO “F) per h: or heat to 795 “C (I460 “Fj. cool rapidly to 690 “C ( I175 “F), and hold for I6 h Hardening. Austenitize at 845 “C ( 15% “F) in a neutral salt bath or in a gaseous atmosphere I\ ith a carbon potential of near I .08. and quench in oil Tempering.

After quenching, parts should be tempered as soon as they have uniformly reached near ambient temperature. 38 to 50 “C ( 100 to I20 “F) is ideal. Because of the high carbon content, parts must be tempered to at least I20 “C (250 “F) to convert the tetragonal martensite to cubic martensite. Most commercial practice calls for tempering at IS0 “C (300 “F). H hich does not reduce the as-quenched hardness to any significant amount. Li’hen a reduction in hardness from the as-quenched value of approximatcl) two points HRC can be tolerated. a tempering temperature of I75 “C (3-15 “F) is recommended. Sometimes subjected to higher tempering temperatures. 1%ith an accompan) ing loss of hardness

Recommended l l

Do not forge after

l

915 “C t 1695 “F)

l l

Recommended Normalizing.

Heat Treating

Practice

l l

Heat to 885 “C (1625 “FL Cool in air

Processing

Sequence

Forge Normalize Anneal t spheroidize 1 hlachine. including rouph grinding Austenitize and quench Temper Finish grind

E51100: Hardness vs Tempering Temperature. Represents average

lsased on a fully quenched

structure

an

428 / Heat Treater’s

Guide

E52100 Chemical Composition. AM: 0.98 to 1.10 C. 0.25 to O.-IS Mn. 0.025 P max. 0.025 S max. 0.15 to 0.30 Si. I .30 to 1.60 Cr. UNS: 0.98 to I.10 C. 0.15 to 0.X Mn. 0.015 P max. 0.025 S max. 0.70 to 0.30 Si. 1.30 to I .60 Cr Similar 6-W. SPEC (Ger.) 53-t A

Steels (U.S. and/or Foreign). UNS GS2986: 6U7; ASTM A27-l. A322. A331. A505. ASl9. A535. MlL-S-980. MJL-S-7120. hllL-S-Zl-t I; SAE J-IO-I. DIN 1.3505; (Fr.) AFNOR IOOC 6: (Ital.) UN1 lOOCr6: 99.535 A 99

AMS 6-WO. 44636: MUJ-II’. 5770: (U.K.) B.S.

Characteristics. Because E52 100 has the same composition as 5 I IO escept for a modest Increase m chromtum. the characteristics and commercoal applications are similar. The as-quenched hardnesses for the tmo steels can be the same (62 to 66 HRCJ. depending mainly on section thickness. Because of higher chromium content. the hardenability of ES2100 is someLt hat higher. Sometimes an attempt is made to evaluate hardness by the end-quench method. ES2100 is selected when greater section sizes and the increased hardenability are needed Forging. temperature

Heat to I IS0 “C (1100 “FJ maximum. Do not forge after of ForSinS stoch drops below approxtmately 915 “C (I 695 “F)

Alloy

Recommended

Heat Treating

Tempering.

Practice

Normalizing. Heat to 885 “C (1625 “FL Cool practice this alloy is nomtalized at 900 “C ( 1650 “F)

in air

Steel / 429

In aerospace

Annealing. For a predominantly spheroidired structure which is generally desired for machining as dell as heat treating. heat to 795 “C t l-160 “F). cool rapidly to 750 “C ( I380 “F). then cool to 675 “C ( 12-15 “Ft. at a rate not to exceed 6 “C I IO “F) per h; or heat to 795 “C ( I460 “FL cool rapidly to 690 “C ( I275 “F). and hold for I6 h. Parts are annealed at 775 “C ( 1125 “F) for 20 min. cooled to 740 “C (I 365 “F) at a rate not to exceed IO “C (20 “F) per h. and air cooled to ambient temperature Hardening. iwstenitize at 845 “C (IS55 “Ft in a neutral salt bath or in a gaseous atmosphere with a carbon potential of near I .OCr. and quench in oil. In aerospace practice, this alloy is austenitized at S-15 “C (IS55 “Ft. Ho\+ever. 815 “C (1500 “F) is pemissible for parts requiring distortion control. Parts are hardened from the spheroidize annealed condition or normalized condition. Parts are quenched in oil or polymer. Immediately after quenching, parts are refrigerated at -70 “C (-95 “F) or lomet-. held for I h minimum. then air barnled to room temperature. If parts have high propensity for cracking during refrigeratton. a snap temper IS recommended

After quenching. parts should be tempered as soon as they have uniformly reached near ambient temperature, 38 to 50 “C (100 to I20 ‘FJ is ideal. Because of the high carbon content, parts must be tempered to at least 120 “C (250 “F) to convert the tetragonal martensite to cubic martensite. Most commercial practice calls for tempering at 150 “C (300 “F). which does not reduce the as-quenched hardness to any significant amount. When a reduction in hardness from the asquenched value of approsimately two points HRC can be tolerated, a tempering temperature of I75 “C (3-0 “F) is recommended. Sometimes subjected to higher tempering temperatures. u ith an accompanying loss of hardness. In aerospace practice. at least t\ lo\\er clvbon range of 61 l8H. the as-qusnchcd hardness is likely to be lower. spproxmiatel! 36 to 42 HRC. The chromium contents of these tbo steels are nearly the same. and their hardennbilitj hands are nearly the same. The small amount of vanadium contained in 61 l8H acts as a grain refiner and does not increase hardenahility. Is rendilj forgeable and weldable (using allo) steel practice). hlachines reasonaLA> ttell Heat to I245 T (217s “F) maslmum. Do not fwgs after of forging stock drops Mow approximately 900 ‘C ( 1650 ‘F)

6118H: End-Quench Distance from quenched su t-face I‘16 in. mm

Practice

“F). Cool in air

Annealing. Structures ha\ ine best machinability are normally obtained hy normalizing orb! isothermal treatment which consists of heating to 885 “C ( 1625 “FL cooling rapid11 to 690 “C ( 1775 “F). and holding for 4 h tempering process

See recommended carhurizing. carbonitriding. and described for -II l8H. Ion nitriding is an alternative

procedures

Recommended l l l l l

Forging.

Heat to 925 “C (I695

Case Hardening.

Characteristics.

temperature

Heat Treating

l l

Processing

Forge Normalize Anneal (optional) Rough and semifinish Case harden Temper Finish machine

Sequence

machine

Hardenability Hardness, ARC may min

I ;7

I 58 4.71 3 16

46 u38

39 28 36

-I 5 6 7 8 Y I0 II 12

6.32 7.90 Y.-l8 Il.06 12.6-I l-l.11 15.80 17.38 18.96

33 30 28 27 16 26 2s 2s 2-I

2-l 22 ‘0

Distance from quenched surface I‘16 in. mm

Hardness, ERC mas

10.5-l 12.12 23 70 3.28 33 u 31 60 3-l 76 37 92 41.08 4-l 74 -+7.40 50.56

6118, 6118H: Hardness sents an average

based

vs Tempering

Temperature.

on a fully quenched

structure

Repre-

434 / Heat Treater’s

Guide

6150,615OH Chemical

Composition.

6150.AlSIandUNS:0.48to0.53C.0.70

to0.90Mn,0.035Pmax,0.030Sma~.0.15to0.30Si,0.80to1.10Cr.0.15 V min. 6150H.AISland UN& 0.47 to 0.54 C.O.60 to 1.00 Mn.0.035 max. 0.040 S max. 0.15 to 0.30 Si. 0.75 to I.20 Cr. 0. IS V min.

Annealing.

For a predominantly pearlitic structure. heat to 830 “C (I 515 “FJ. cool rapidly to 760 “C ( 1100 “F), then cool to 675 “C (I 235 “F). at a rate not to exceed 8 “C (IS “Fj per h: or heat to 830 “C (1515 “F). cool rapidly to 675 “C (1% “FL and hold for 6 h. For a predominantly spheroidized structure, heat to 760 “C t I100 “F), and cool to 675 “C ( I245 “F) at a rate not to exceed 6 “C (IO “F) per h; or heat to 760 “C (1300 “F), cool rapidly to 650 “C ( I200 “F). and hold for IO h

P

Similar Steels (U.S. and/or Foreign). 6150. UNS G61500; AhlS 6448. 6450, 6455: ASTM A322. A33l: MIL SPEC hlIL-S-8503; SAE J4O-l. J4lL 5770; CrV -I: (Jap.) JIS 47. 6150H. UNS (Fr.) AFNOR 50 SSIJ 2230; (U.K.)

(Ger.) DIN 1.8159; (Fr.) AFNOR 50CV-1: (Ital.) UNI SO SUP IO: (Shed.) SSIJ 2230: (U.K.) B.S. 735 A SO. En. H61500: ASThl A30-I; SAE 5407; (Ger.) DlN I .8159: CV -I; (Ital.) UNI 50 CrV 3; (Jap.) JIS SUP IO: (Swed.) B.S. 735 A SO. En. 37

Characteristics. A medium high-carbon chromium-vanadium allo) steel which has been used for numerous applications including premium quality springs. Its as-quenched hardness is generally 55 to 60 HRC. depending on the precise carbon content. Hardenahilit) is relativeI) high. approximately the same as for -IllOH. The chromium content is main11 responsible for the hardenability. The vanadium serves as a grain refiner and has no significant effect on hardenability. Is forgeable. but is not recommended for helding

Hardening. Tempering.

Reheat immediately after quenching [preferably before the temperature of the parts drops below the range of 38 to 50 “C (100 to I20 “F)] to the temperature required to obtain the desire combination of mechanical properties

Austempering.

For many spring applications. this steel is austempered bq austenitizing at 870 “C t 1600 “F), quenching in an agitated molten salt bath at 3 IS “C (600 “F). holding for I h. and air cooling No tempering is required. Hardness after this treatment generally ranges from approximatslq 16 to 5 I HRC

Recommended l

Forging. temperature

Heat to 1230 “C (2X0 “F) maximum. Do not forge after of forging stock drops below approximately 900 YI. ( 1650 “F)

l l l

Recommended

Heat Treating

Practice

l l

Normalizing.

Heat to 900 “C (I650 “F). Cool in air

6150: Isothermal Transformation C, 0.67 Mn, 0.93 Cr, 0.18 Grain size: 9

Diagram. Composition:

V. Austenitized

at 845 “C (1555

l

0.53

“F).

Heat to 870 “C (1600 OF). and quench in oil

Processing

Sequence

Forge Normalize Anneal Rough machine Austenitize and quench (or austemper) Temper (or austemperj Finish machine

6150: gears

Equipment

requirements

Production requirements H’eight of eclch piece Pieces per furnace load Producuon per hourcaj: Number of pieces Net work load Gross furnace losdr b ) Equipment requirements hlanempering furnace Size of salt pot Capxit) of salt pal -r)peofsdr Quenching sapacrty of ball pot Operating rcmpenture Agitation

for salt mat-tempering

0.9kp(llb, 32 128 116kg(256lb) 152kgt336lb) tmmrnion-heated salt pot(c) 6lOb) 381 by838nun1Xbq lSby33in.) 272kgl6OOlb) Nitrate-nitrite(X acueradded) I81 kg/ht-IGOIb/h) 205 ‘T (400 “R Air-operated stirrer

la1 Clsle ume. IS min. Ib) Work and fikwrrs. Each IYkturz welghed 9.1 kg (20 lb) rmpr) and clzs. 220 c’) used forcooling b> dri\ingroom-rempratureairbewren \rall of pot and exterior shell of furnace

Alloy Steel / 435

6150: Hardness vs Tempering Temperature. Normalized at 900 “C (1650 “F), quenched from 870 “C (1600 “F) in oil, tempered in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel

6150H: End-Quench Hardenability Distance frum quenched surface 916in. mm 1 2 3 4 5 6 I 8 9 10 11 12

6150:

As-Quenched

Hardness

(Oil)

Single heat results; grade: 0.48 to 0.53 C. 0.70 to 0.90 Mn, 0.20 to 0.35 Si, 0.80 to 1.10 Cr, 0.15 V minimum; ladle: 0.51 C, 0.80 Mn, 0.014P,0.015S.0.35Si,0.11Ni.0.95Cr.0.01Mo,0.18V;grainsize: 5 to 6 for 70%, 2 to 4 for 30% Size round in.

mm

Surface

Hardness, HRC ?(zradius

Center

‘h

13 25 51 102

61 60 54 42

60 58 47 36

60 57 44 35

1 2 4

Source: Bethlehem Steel

1.58 3.16 4.74 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38 18.96

Hardness, HRC max min 6.5 65 64 64 63 63 62 61 61 60 59 58

59 58 51 56 55 53 50 41 43 41 39 38

Distance &urn quenched surface 916in. mm 13 14 15 16 18 20 22 24 26 28 30 32

20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40 50.56

HaIdIlesS, HRC max min 51 55 54 52 50 48 47 46 45 44 43 42

31 36 35 35 34 32 31 30 29 27 26 25

436 / Heat Treater’s

6150: Microstructures.

Guide

(a) 2% nital, 550x. Steel wire, austenitized at 900 “C (1650 “F) for 20 mm and slack quenched in oil to room temperature. Lower bainite (dark) and untempered martensite (light). (b) Picral, 550x. Austenitized at 880 “C (1620 “F) for l/z h, cooled to 730 “C (1350 “F) held 5 h, cooled to 650 “C (1200 “F) at 28 “C (50 “F) per h, held 1 h, air cooled. Pearlite and ferrite. (c) 4% nital, 500x. Steel wire, austenitized at 885 “C (1625 “F) for 20 min, quenched to 675 “C (1245 “F) for 20 min, oil quenched to room temperature. Structure mainly pearlite. (d) 4% nital, 5000x. Steel wire, austenitized at 845 “C (1555 “F) for r/p h, oil quenched, tempered at 150 “C (300 “F). An electron micrograph of a replica rotary-shadowed with chromium. Tempered martensite and some spheroidal carbide particles. (e) 4% nital, 10,000x. Steel wire, austenitized at 870 “C (1600 “F), held for 2 h, quenched in lead to 650 “C (1200 “F), held for 2 h, water quenched. An electron micrograph of a replica rotary-shadowed with chromium. Partly spheroidized carbide in a ferrite matrix. (f) 4% nital, 10,000x. Steel wire, austenitized at 870 “C (1600 “F) for 2 h, quenched in lead to 720 “C (1330 “F), held 2 h, water quenched. An electron micrograph of a replica rotary-shadowed with chromium. Partly spheroidized and partly lamellar pearlite in ferrite. (g) Nital, 535x. Steel rod, 13 mm (l/2 in.) diam, austenitized at 845 “C (1555 “F) for 1 h, quenched to 315 “C (600 “F), held 16 min, air cooled. Mostly bainite, probably lower bainite. (h) Nital, 1000x. Same steel, rod diameter, and heat treatment as (g), except at higher magnification. Austempering was the heat treatment used

Alloy Steel / 437

81 B45,81

B45H

Chemical

Composition. N&15. AISI: 0.43 IO (J.-U C, 0.75 to I .OO hln.0.035 Pmax.O.O-!OSmax.O.lS to0.30Si.0.20to0.10Ni.0.351o0.55 Cr. 0.08 to 0. IS MO. 0.0005 to 0.003 B. UNS: 0.43 to O.-l8 C. 0.75 to 1.00 hIn.0.035 Pmax.O.WOS max.0.15 to0.30Si.0.20 toO.-lONi.0.35 100.55 81BGH: Cr. 0.08 to 0.15 Mo. 0.0005 B min. UNS HSlJSl and SAE/AISI O.-P to 0.19 C. 0.70 to 1.05 Mn. 0.15 to 0.35 Si. 0.15 to O.-IS Ni. 0.30 to 0.60 Cr. 0.08 to 0. IS hlo. B (can be expected to he 0.0005 to 0.003 percent) Similar

Steels (U.S. and/or

ASThl ASl9: SAE J-W. A3O-k SAE J 1268

Foreign).

JAI?. 1770. 81BJ5H.

MB35 UNS

LINS G8l-lS I : H813Sl: ASTM

Annealing.

Forapredominantl\ pearlitic structure. heat to 830°C (IS25 “FJ. cool rapidI) IO 725 “C ( I33S-‘F). then cool to 6-10 “C (I I85 “F). at a rate not to exceed I I ‘C (20 “F) per h; or heat to 830 “C (IS25 “F), cool rapidly to 660 “C t 1220 ‘F). and hold for 7 h. For a predominantly spheroidizsd structure. heat to 750 “C t I380 OF). and cool rapidly to 725 “C t I.335 “F). then continue cooling to 610 “C t I I85 “F) at a rate not to csceed 6 “C (IO “F); or heat to 750 “C ( I380 “F). cool rapidly to 660 “C t I230 “F). and hold for IO h

Hardening. Tempering.

Characteristics.

A slightI> modified version of 86B-iSH. Ni. Cr. and MO are slightly louer. The as-quenched hardnesses of the IWO steels are essentially the same, approaunatel> S-l to 60 HRC. Hardenabilitb of the t\to grades is nearly the same

After quenching. parts should be tempered immediately. Selection of tempering temperature depends upon the desired mechanical propertizs

Recommended l

Forging. temperature

Heat to 1230 ‘C (2250 “F) maxmium. Do not forge after of forging stock drops below approximately 925 “C ( 1695 “F)

l l l

Recommended

Heat Treating

Practice

l l

Normalizing.

Heat to 815 “C t IS55 “F), and quench in oil

Heat to 870 “C t 1600 “FL Cool in mr

81845: Hardness vs Tempering Temperature. Normalized at 870 “C (1600 “F), quenched from 845 “C (1555 “F) in oil, tempered in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel

l

Processing

Sequence

Forge Normalize Anneal Rough and ssmifmish machine Austenitizs and quench Temper Finish machine

81 B45H: End-Quench Hardenability Distance from quenched surface !&in. mm I 2 3 -I 3 6 7 8 9 I0 II I2

I 58 3.16 4.7-l 6.32 7.90 9.48 I I 06 12.6-l I-I.22 IS.80 17.33 I X.96

Hardness, HRC Olin nlax 63 63 63 63 63 63 62 62 61 60 60 59

56 56 56 56 s5 5-l 53 51 1s 44 II 39

Distance l’rom quenched surface 916 in. mm 13 I-I IS I6 18 20 22 2-I ‘6 18 30 3’

20.5-l 22.12 23.70 3.28 x3.44 31.60 31.76 37.91 41.08 44.2-l 47.40 50.56

Hardness, ElRC max min 58 57 57 56 55 53 52 50 49 -17 45 43

38 37 36 35 34 32 31 30 29 28 28 17

438 / Heat Treater’s

Guide

8615 Chemical

Composition.

8615. AISI and UNS: 0.13 KI 0. I8 C. 0.70

to0.90Mn,0.035Pmrut.0.~0Smax.0.15to0.30Si,0.30to0.70Ni,0.~0 to 0.60 Cr. 0. I5 to 0.25 MO

Similar Steels (U.S. and/or Foreign). LINS G86150; 5333; ASTM A322; ML SPEC MIL-S-866; SAE J4O-%,J770

Tempering. AMS

Characteristics. Similar to 8617H and 8620H. except with a lower carbon range. Extensively used for parts processed by carburizing and carbonitriding. Although there is no published AISI hardenability band for 8615. the hardenability pattern for 8615 should be very similar to that for 8617H. adjusted down slightly because 8615 has a lower carbon range. As-quenched surface hardness for 86 I5 usually ranges from 35 to 30 HRC. Fogeable and weldable: machinability is fairly good Forging. temperature

OF). then holding for 4 h. Another technique is to heat to 790 “C (1455 “F). cool rapidly to 660 “C ( 1220 ‘F). and hold for 8 h

Heat to 1245 “C (2275 “F) maximum. Do not forge after of forging stock drops below approximately 900 “C (1650 “F)

Temper all carburized or carbonitrided parts at I50 “C (300 “F). and no case hardness will be lost as a result. If some decrease in hardness can be tolerated. toughness can be increased by tempering at somewhat higher temperatures, up to 260 “C (500 “F)

Case Hardening. scribed for 8620H. processes

Recommended l l l l

Recommended Normalizing.

Heat Treating Practice

Heat to 935 “C ( I695 OF). Cool in air

Annealing.

Structures nith best machinability malizing or by heating to 885 “C ( 1625 “F). cooling

are developed by norrapidly to 660 “C ( I220

8615: Case Depth of Liquid Carburized Steel vs Time and Temperature. 19 mm (0.75 in.) outside diam by 121 mm (4.75 in.), oil quenched.

l

Carburized

at indicated

temperatures

l l

See carburizing flame hardening

Processing

and carbonitriding and ion nitriding

practices deare alternative

Sequence

Forge Normalize AMY (if required) Rough machine Semitinish machine allowing only grinding stock. no more than IO% of the case depth per side for cart&red parts. In most instances. carboniuided parts are completely finished in this step Carburize or cmbonitride and quench Temper

8615: Liquid

Carburizing. Specimens 19 mm (0.75 in.) by 121 mm (4.75 in.), carburized at 925 “C (1695 “F) for 15 h, air cooled, reheated in neutral salt at 845 o C (1555 “F), quenched in salt at 180 ’ C (355 “F)

8615: Hardness vs Tempering Temperature. average

based

on a fully quenched

structure

Represents

an

Alloy Steel I439

8617,8617H Chemical

Composition. 8617. AISI and UNS: 0. IS to 0.10 C, 0.70 too.90 Mn. 0.035 Pmax. 0.04OS max. 0. I5 too.30 Si.O.10 to0.70Ni.0.40 to 0.60 Cr. 0. IS to 0.25 Mo. UNS H86170 and SAE/AISI 86178: 0. II to 0.20 C, 0.60 to 0.95 Mn. 0. IS to 0.35 Si, 0.35 to 0.75 Ni. 0.35 to 0.65 Cr. 0.15 too.25

Mo

Similar

Steels (U.S. and/or Foreign). 6617. UNS G86170; AMS SAE J-IO-I. 5770; (Ger.) DIN I .6523; (Fr.) AFNOR 20 NCD 2.22 NCD 3: (Ital.) UNI 20 NiCrMo 2; (Jap.j JIS SNCM 21 H. SNCM 21: (U.K.) B.S. 805 H 20.805 M 20.8617H. l[NS H86 170; ASIXI A304 SAE J 1268; (Ger.) DIN 1.6523; (Fr.) AFNOR 20 NCD 3, 22 NCD 2; (Ital.) UN1 20 NiCrhlo 3: (Jap.) JIS SNCM 21 H. SNCM 21; (U.K.) B.S. 805 H 20.805 M 20 6272:

Characteristics.

A carburizing prade of the multiple alloy series. NiCr-Mo. Not as widely used for case hardening as 8620H and 8622H. An as-quenched hardness of approximately 35 to 40 HRC can be expected without carhurizinp. Hardenability is reasonahl) high. Has excellent forgeahility. can he welded using allo) steel practice, and has fair11 good machinability

Forging.

Heat to 1245 “C (2375 “F) malimum. Do not forge after temperature of forging stock drops below approsimately 900 “C ( 1650 “F)

Recommended Normalizing.

Heat Treating

can he tolerated, toughness can he increased higher temperatures. up to 260 “C (SO0 “F)

Heat to 925 “C ( 1695 “F). Cool in air

Annealing.

Structures with hest machinability are developed hj normalizing or hq heating to 885 “C ( I625 “FL cooling rapidly to 660 “C ( I320 “FL and holding for 1 h: or heat to 790 ‘C (l-IS.5 “F). cool rapid11 to 660 “C (I 220 “F), and hold for 8 h.

Tempering.

Temper all carhurized or carbonitrided parts at I SO “C (300 OF) and no loss of case hardness will result. If some dscrease in hardness

at somewhat

Case Hardening. See carburizing and carbonitriding practices described for 8620H. Flame hardemng. ion nitriding. gas nitriding. gas carhurizing, austempering and martempering are alternative processes

Recommended l l l l l

l l

Processing

Sequence

Forge Normalize Anneal (if required) Rough machine Semifinish machine allowinp only 8rinding stock. no more than 10% of the case depth per side for carhunzed parts. Ln most instances. carhonitrided parts are completely finished in this step Carburize or carhonitride and quench Temper

8617: Equipment carburized parts

requirements

Production requirements Weight of load Weight ofeach prece Number of pieces treated per hour

Practice

hy tempering

Equipment

for oil mat-tempering

1S3.6kg(lOOOlbnet) I .S kg f 3.3 lb) 75

requirements

Capacib of quench tank Type of oil

7511 L(2oGOgal) hIineraloil\rithaddjti~est~iscosi~,~SOSUS)

lkmpenturr

I SO “C ( 300 “F) Direct tlow(a,

of oil

Agitation

(a) Agitation pro\ idrd bj I\GO S-hp motors drivmg 457.mm (IS-in.) ‘pm. causing lhc oil to flow at a rate of911 mm/set (36 in./sec)

propellers at 370

8617, 8617H: Hardness vs Tempering Temperature. Represents an average

8617H: End-Quench Hardenability Distance from quenched swtface l/16 in. mm

Hardness, HRC min max

I

I.58

46

2

3.16

4-l

39 33

3

1.11

-II

17

-l

6.32 7.90 9.18

38 3-l 31 28

24 20

5

6 7

Il.06

8

1264 l-l.22 IS.80 17.38 IS.96

9 IO II I2

___

27

26 2s 2-l 23

1::

Distance from quenched surface ‘/lb in. mm I3 I-I IS

I6 I8

20 21 21 26

2o.s-l 22.1’

23.70 25.18 28.4-l 31.60 34.76 37 92

28

41.08 5-1.2-l

30 32

17.40 50.56

Hardness.

HRC max

23 22

‘2 21 II

20

..:

based

on a fully quenched

structure

440 / Heat Treater’s

Guide

8617H: Hardenability

Curves. Heat-treating 925 “C (1700 “F)

(1700 “F). Austenitize:

Hardness purposes I distance, nm 1.5

i ) Ll 13 I5 ‘0 !5 10 $5

limits for specification Hardness, HRC Maximum Minimum 46 44 42 37 32 29 27 25 23 22 20

39 33 27 23 20

.

Hardness limits for specification wrposes I distance, /16mm

, 1;

1

IO I1 12 13 I4 I5 I6 I8 !O !2

Hardness, HRC Maximum Minimum 46 44 41 38 34 31 28 27 26 25 24 23 23 22 22 21 21 20

39 33 27 24 20

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 925 “C

Alloy Steel / 441

8617: Microstructures.

(a) 1% nital, 500x. 8617H, gas carburized for 3 74 h at 925 “C (1695 “F), cooled in the furnace to 540 “C (1000 “F), air cooled, heated to 840 “C (1545 “F), quenched in oil, tempered for 2 h at 150 “C (300 “F), quenched in oil, tempered for 2 h at 150 “C (300 “F). Numerous microcracks (small black streaks), are present both at the boundaries and across martensite plates. (b) 39/onital. 200x. 8617, carbonitrtded 4 h at 845 “C (1555 “F) in 8% ammonia, 8% propane, remainder endothermic gas, oil quenched, tempered 1 !‘z h at 150 “C (300 “F). Tempered martensite (dark) and retained austenite. (c) 3?L nital, 200x. 8617 steel bar, carbonitrided and tempered same as (b), except held at -73 “C (-100 “F) for 2 h between quenching and tempering to transform most of the retained austenite. Scattered carbide and small amounts of retained austenite in a matrix of tempered martensite. (d) Picral, 200x. 8617 steel bar, annealed by being austenitized at 870 “C (1600 “F) for 2 h, furnace cooled. Fine pearlite (dark) in ferrite matrix (light). Magnification too low for good resolution of structure

Alloy Steel / 441

8620,862OH Chemical

Composition.

8620. AK3 and UNS: Nominal. 0.18

too.23 CO.70 to0.90Mn,0.035 Pmax,O.O40S to 0.70 Ni, 0.40 to 0.60 Cr, 0.15 to 0.25 MO. Nominal. 0.17 to 0.23 C, 0.60 to 0.95 Mn, 0.035 to 0.30 Si, 0.35 to 0.75 Ni, 0.35 to 0.65 Cr, 0.15

max,0.15 toO.3OSi,O.40 862038. AISI and UNS: P max, 0.040 S max, 0.15 to 0.25 MO

Similar Steels (U.S. and/or Foreign). 8620. UNS G86200, AMS 6274,6276,6277; ASTM A322, A33 1, A513, A914; MIL SPEC MIL-S16974; SAE 5126851868; (W. Ger.) DIN 1.6523; (Fr.) AFNOR 20 NCD 2,22 NCD 2; (Ital.) UN1 20 NiCrMo 2; (Jap.) JIS SNCM 21 H, SNCM 21; (U.K.) B.S. 805 H 20,805 M 20.8620H. UNS H86200; ASTM A304; SAE 5407; (W. Ger.) DIN 1.6523; (Fr.) AFNOR 20 NCD 2, 22 NCD 2; (Ital.) UN1 20 NiCrMo 2; (Jap.) JIS SNCM 21 H, SNCM 21; (U.K.) B.S. 805 H 20,805 M 20 Characteristics. Used extensively as a case hardening steel for both carburizing and carbonitriding. As-quenched surface hardness usually ranges from approximately 37 to 43 HRC. Reasonably high hardenability. Excellent forgeability and weldability, although alloy steel practice should be used in welding to minimize susceptibility to weld cracking. Machinability is fairly good. Because 8620H and 8620 are high-tonnage steels, some mills produce them with lead additions. This significantly improves machinability without sacrificing heat treating response

Forging. Heat to 1245 “C (2275 “F) maximum, and do not forge after the temperature of the forging stock has dropped below approximately 900 “C (1650 “F)

Recommended Normalizing.

Heat Treating

Practice

Heat to 925 “C (1700 OF) and cool in air

Annealing.

Structures with best machinability are developed by normalizing or by heating to 885 “C (1625 “F), cooling rapidly to 660 “C (1225 OF), and holding for 4 h. Another technique is to heat to 790 “C (1450 “F), cool rapidly to 660 “C (1225 “F), and hold for 8 h

Carburizing. In general, carburizing practice for 86208 (and 8620) is the same as for other low-carbon, plain carbon, and alloy steels. Because of its inefficiency, the pack method is used only for highly specialized applications. Carburizing by immersion is often used, although mainly for developing relatively thin cases. Any one of a number of proprietary molten salt baths can be used, usually within the temperature range of 870 to 925 “C (1600 to 1700 “F). As a rule, workpieces are quenched directly from the carburizing temperature. 8620H and other carbon and alloy steels are most frequently gas carburized, a far more efficient method that is easier to control

442 / Heat Treater’s

Guide

Gas Carburizing. effectively extensively: l

l

l l

Although a number of different cycles can be used for 8620 and 8620H. the one listed below is a cycle used

Carburize at 925 Y? ( I700 ‘F) in a prepared carbonaceous atmosphere u ith the dewed carbon potential (commonly about 0.90 carbon) for-l h Reduce temperature to g-15 “C ( IS55 “F). reduce carbon potential to near eutectoid. and diffuse for I h Quench in oil Temper for I h at I SC)“C (300 ‘F)

This cycle will result in a total case of approximatslj I.3 mm (0.050 in.). Deeper cases can be obtained with longer cycles. but this is a matter of diminishing returns. Obtaining greater case depths by increasing time cycles IS costly in terms of energy consumption. Case depth can be increased exponsntiallly by increasing the carburizing temperature. but this approach becomes a matter ofeconomlcs as wAl, because the rate ofdeterioration on furnace alloys and refmctories above ahwt 925 “C ( 1700 ‘F) may become intolerable because of the high cost of hmace maintenance. The most economical approach for deep-case carbwizing LSthe use of the vacuum Furnace, which operates as high as 1095 ‘C (2000 “F)

Carbonitriding. For thin, file-hard cases, parts made of 8620 or 8620H are often carbonitrided at g-15 “C ( ISSO ‘F) in a carbonaceous atmosphere with an addition of 10% anhydrous ammonia. Temperatures of 790 to 900 “C ( I-150 to I650 “F) have been used, but 84.5 “C t IS55 “F) seems to be the

most common. Parrs are oil quenched directly from the carbonitriding temperature. Just as is true for carburizing. the case depth increases hith time at temperature. Using a carbonitriding temperature of 845 “C (1555 ‘F). it is possible to obtain a case depth of approximately 0.305 mm (0.012 in.) in about 45 min

Other PrOCeSSeS. ion nitriding, carburiring

Flame hardening. austempering. martempering, gas nitriding ion carburizing. vacuum carburizing. liquid

Tempering.

Temper all carburized or carbonitrided parts at IS0 “C (300 “F) and virtually no loss of case hardness results. If some decrease in hardness can be tolerated, toughness can be increased by tempering at somewhat higher temperatures, up to 260 ‘C (SO0 “F)

Recommended l l l l l

l l

Processing

Sequence

Forge Normalize Anneal (if required) Rough machine Semitinish machine. allowing onl? grinding stock, no more than 10% of the case depth per side for carbunzed parts. In most instances, carbonitridcd parts are completeI> tinished in this step Carburize or carbonitride and quench Temper

8820: Continuous

Cooling Curves. Composition: 0.17 C, 0.82 Mn, 0.31 Si, 0.52 Ni, 0.50 Cr, 0.20 MO. Austenitized at 925 “C (1700 “F). Grain size: 9. AC,, 825 “C (1520 “F); AC,, 745 “C (1370 “F). A: austenite, F: ferrite, B: bainite, M: martensite

Alloy Steel / 443

8620: Isothermal Transformation

Diagram. Composition: 0.18 C, 0.79 Mn, 0.52 Ni, 0.56 Cr. 0.19 MO. Austenitized at 900 “C (1650 “F). Grain size: 9 to 10

8620: End-Quench

8620: Austenitizing

8620: Cooling Time vs Depth of Hardness. Time to cool from

Temperature vs Depth of Hardness. Cast

Hardenability. Composition: 0.18 C, 0.79 Mn, 0.52 Ni, 0.56 Cr. 0.19 MO. Austenitized at 900 “C (1650 “F). Grain size: 9 to 10

RL7911. Heat treatment: A: 900 “C (1650 “F), 15 min. lpsen Furnace; B: 1000 “C (1830 “F), 15 min, lpsen Furnace; C: 1100 “C (2010 “F), 15 min, Muffle and Ipsen. Depth below surface: 1: 0.3 mm (0.012 in.); 2: 2.5 mm (0.1 in.)

730 “C (1350 “F) to temperatures of 540 to 260 “C (1000 to 500 “F), quenched from 845 “C (1555 “F)

8620: Gas Carburizing. Carburized

8620: Liquid Carburizing,

in a recirculating pit furnace. 7.5 h at temperature. 12% CH,. Core: 0.2296 C. 0: 925 “C (1700 “F); 0: 900 “C (1650 “F); A: 870 “C (1600 “F)

Case Hardness Gradients.

tests. Scatter resulting from normal variations

Nine

444 / Heat Treater’s

6620H:

End-Quench Hardenability

Distance from qurnched surface I.‘,6 in. mm I ? 1 4 5 h 7 Y 9 I II II I2

Guide

Hardness. HRC mas min

I .5x 3 Ih 4.7-l h.32 7 90 Y.-IS Il.ufl 12.64 II 12 I5 80 17.38 IX.%

-lx 17 4-l -II 37 34 22 30 ‘9 2x 27 26

6620: End-Quench with theoretical

-II 37 31 27 23 21

_:

Hardenability.

Jominy

results compared

curve (constant H)

6620: Depth of Case vs 0.40% C and 59 HRC. Test specimens 25-mm (l-in.) diam were processed with production gears in a two-row continuous gas carburizing furnace using a diffusion cycle and an atmosphere of endothermic gas enriched with natural gas: air was added to the discharge end. Effective case depth to 50 HRC was measured on a microhardness traverse taken midway between the ends of a cross section of the gear tooth at the junction of the involute profile and root fillet. (a) Depth of case to 0.40% C, 48 tests. 25-mm (l-in.) diam bar tempered in lead at 650 “C (1200 “F). (b) Depth of case to 50 HRC. 47 tests. Gears tempered at 160 “C (325 “F)

6620: Carbon Gradients Produced by Liquid Carburizing. mm (0.75-in.) diam by 51 mm (2 in.), carburized “F) for 8 h

19at 910 “C (1675

6620, 6620H: Hardness vs Tempering Temperature. sents an average based on a fully quenched structure

Repre-

Alloy Steel / 445

8620: Carbon, Nitrogen, and Hardness Gradients. 8620 and 1018 carbonitrided at 845 “C (1555 “F) for 4 h in a batch radianttube furnace. Test data were obtained in a construction-equipment manufacturing plant under normal production conditions, using a standard carbonitriding cycle. Test specimens were carbonitrided in production loads containing 23 kg (50 lb) of gears and shafts. The carbonitriding atmosphere, which was controlled by an infrared control unit, consisted of endothermic gas at 14.1 ma/h (500 fP/h), ammonia at 0.71 m3/h (25 ftVh), propane at 0.01 to 0.02 m3/h (0.25 to 0.75 Wh), and 0.32 to 0.34% CO,. Dew point of the atmosphere was maintained at -7 to - 6 “C (19 to 21 “F) throughout the carbonitridinq cycle. All specimens were quenched from the carbonitriding temperature (845 “C or 1555 “F) in warm (54 “C or 130 “F) oil. (a) Carbon; (b) Nitrogen; (c) Hardness. Quenched in oil at 54 “C (130 “F). Hardness converted from Tukon

8620H: Carbonitriding.

Load: gears, 342 kg (753 lb) net, 459 kg (1011 lb) gross. Batch-type furnace with brick-lined heating chamber, heated by radiant tubes; vestibule-enclosed quench. Dimensions of furnace chamber: 1422 mm wade, 1676 mm long, 1092 mm high (56 by 66 by 43 in.). Garner gas: endothermic gas at 21.2 mVh (750 ft Vh), including 63 min at temperature. Enriching gas: additions of propane at 0.1 m3/h (5 fWh), and of ammonra at 1 .l m3/h (38 ff/h), started after 33 mm at temperature. Generator dew point: -15 to -14 “C (5 to 7 “F) throughout carbonitriding process cycle. Heating chamber pressure: 1.5 to 2.0 mm (0.06 to 0.08 in.) H,O. Carbonitriding temperature: 815 “C (1500 “F). Quenching temperature: 815 “C (1500 “F). (a) Temperature and dew-point variations. (b) resulting carbon gradient

Analysis

of Atmosphere

Near End of Cycle Amount furnace,

Conbtituent

8620:

Approximate

Critical

in 5

Amount \es,tibule,

in B

Points Temperature

Critical

point

OF

T

446 / Heat Treater’s

Guide

8820: Depth of Case After Gas Carburizing.

Depth of case to 0.40% C. 0: Furnace A. 762 by 1219 by 457 mm (30 by 48 by 18 in.). Atmosphere control dew cell with manual reset. Rated gross load, 680 kg (1500 lb). 0: Furnace B, same as Furnace A. A: Furnace C. 914 by 1829 by 610 mm (36 by 72 by 24 in.). Atmosphere control infrared analyzer controlling carbon dioxide, automatic reset. Rated gross load, 1588 kg (3500 lb) (a) 25-mm (1 -in.) rounds carburized at 925 “C (1700 “F) for 1.75 h. Quenched in oil from 845 “C (1555 “F). Diffusion cycle used. Dew points of -15 “C (5 “F) for first part of 925 “C (1700 “F) cycle, -12 “C (10 “F) for diffusion cycle at 925 “C (1700 “F), and -3 “C (27 OF) for time at 845 “C (1555 “F) before quenching. Endothermic plus straight natural gas as enriching gas. Tempered in lead at 650 “C (1200 “F), wire brushed, and liquid abrasive cleaned. (b) 25-mm (l-in.) diam bar. Endothermic with straight natural gas as enriching gas. Carburized at 925 “C (1700 “F), using diffusion cycle. Dew point of -15 “C (5 “F) for 3 h at 925 “C (1700 “F), a dew point of -12 “C (10 “F) for the difl usion portion, and -3 “C (27 “F) for 1 h at 845 “C (1555 “F). (c) 25-mm (1 -in.) diam bar. Total cycle at 925 “C (1700 “F) was 10.5 h, 5 h with a -15 “C (5 “F) dew point, and 5.5 h with a -12 “C (10 OF) dew point. Equalizing time at 845 “C (1555 “F) was 1 h, with a dew point of -3 “C (27 “F). (d) 25-mm (1 -in.) diam bar. Diffusion time with a -12 “C (10 “F) dew point was 6 h. (e) Gears, carburized at 925 “C (1700 “F) in a continuous furnace. (f) 25-mm (1 -in.) diam by 38 mm (1.5 in.), batch-type carburizing

8620H: Gas Carburizing.

Shafts, 171 kg (376 lb), 440 kg (969 lb) gross. Vestibule, enclosed-quench, brick-lined heating chamber, radiant-tube heated. Carrier gas: 21.8 ma/h (770 ff/h) endothermic gas for 5 h 53 min at temperature. Enriching gas: 0.28 m3/h (10 fP/h) propane, 3 h 59 min at temperature (66% of cycle). Generator dew point: 1 to 4 “C (33 to 39 “F). Heating chamber pressure: 2.5 to 3.6 mm (0.10 to 0.14 in.) water column. Carburized at 925 “C (1700 “F) and quenched from 845 “C (1555 “F). (a) Furnace temperature and atmosphere conditions for carburizing. (b) Resulting carbon gradient

Alloy Steel / 447

8620H: Gas Carburizing.

Load: ring gears, 231 kg (510 lb) net, 390 kg (860 lb) gross. Metallic-retort pit furnace, electrically heated. 0.34 m3/h (100 ff/h) endothermic gas throughout the cycle, including 5 h 59 min at temperature. Enriching gas: 0.34 m3/h (12 W/h) natural gas for 2.5 h at temperature (42% of at-temperature cycle). Generator dew point: -6 to -4 “C (22 to 25 “F). Heating chamber pressure: 5.1 to 7.9 mm (0.20 to 0.31 in.), water column. Carburizing temperature: 925 “C (1700 “F). Slow cooled from 925 “C (1700 “F) in cooling pit. Atmosphere at the end of cycle: 20.8% CO, 0.496 CO,, 34.0% H,, 0% O,, 0.8% CH,. (a) Furnace temperature and atmosphere conditions for carburizing. (b) Resulting carbon gradient

8620H: Gas Carburizing.

Ring gears, 231 kg (510 lb) net, 390 kg (860 lb) gross. Metallic-retort pit furnace, electrically heated. 2.83 m3/h (100 fP/h) endothermic gas for 5 h 15 min at temperature, carrier gas. Enriching gas: 0.34 ma/h (12 ftYh) started at temperature and shut off after 3 h (57% of cycle). Generator dew point: -4 to -3 “C (24 to 26 “F). Heating chamber pressure: 8.6 to 11 mm (0.34 to 0.44 in.) water column. Carburized at 925 “C (1700 “F) and slow cooled in cooling pit. (a) Furnace temperature and atmosphere conditions for carburizing. (b) Resulting carbon gradient

8620: Depth of Case vs Time and Temperature. 12-mm (0.5-in.) diam by 6.4 mm (0.25 in.). Carburized at 855 “C (1575 “F), oil quenched, tempered at 150 “C (300 “F), treated at 49 “C (120 “F)

448 / Heat Treater’s

Guide

8620H: Gas Carburizing. Shafts, 145 kg (320 lb) net, 258 kg (569 lb) gross. Metallic-retort pit furnace, electrically heated. Carrier gas: 2.83 mVh (100 fP/h) endothermic gas for 5 h 5 min at temperature. Enriching gas: 0.3 m3/h (9 ff/h) natural gas, for 2 h 50 min from start of cycle (56% of cycle). Generator dew point: 4 to -3 “C (24 to27 “F). Heating chamber pressure: 9.9 to 12 mm (0.39 to 0.49 in.) water column. Carburized at 925 “C (1700 “F) and quenched from 845 “C (1555 “F). (a) Furnace temperature and atmosphere conditions for carburizing. (b) Resulting carbon gradient

8620: Microstructures.

8620: Effect of Carburizing

Time and Temperature. Specimens 19-mm (0.75-in.) diam by 51 mm (2 in.), carburized, air cooled, reheated in neutral salt at 845 “C (1555 “F), quenched in salt at 180 “C (360 “F). (a) Carburized at 870 “C (1600 “F); (b) carburized at 900 “C (1650 “F); (c) carburized at 925 “C (1700 “F)

(a) Picral, 200x. Steel bar normalized by being austenitized at 900 “C (1650 “F) for2 h and cooled in still air. Mixture of ferrite and carbide. Cooling too rapid to produce an annealed structure. (b) Nital, 100x. Steel bar carbonitrided for 4 h at 845 “C (1555 “F), oil quenched, not tempered. and stabilized by subzero treatment. Conventional case structure with martensite, carbide particles, and a small amount of retained austenite. (c) Picral, 1000x. Coarse grain steel, gas carburized 11 h at 925 “C (1700 “F), furnace cooled at 845 “C (1555 “F), oil quenched, tempered 2 h at 195 “C (380 “F). Tempered martensite and retained austenite. A large martensite plate contains several microcracks

Alloy

Steel

/ 449

8820: Microstructures (continued). (d) Picral, 1000x. Same steel, carburizing and heat treatments, and structure as (c), but specimen was subjected to maximum compressive stress of 4137 MPa (600 ksi) for 11.4 million cycles in a contact fatigue test. Butterfly structural alterations developed at microcracks. (e) 4% picral, 500x. Steel gas carburized for 18 h at 925 “C (1700 “F), reheated to 830 “C (1540 “F) and held 40 min, oil quenched, tempered 1 hat 175 “C (350 “F). Nearsurface are grain-boundary oxides and, less visible because of dark etching, bainite and peariite. Remaining structure is carbide particles and retained austenite in a matrix of tempered martensite. (f) Not polished, not etched; 23x. Steel tubing, gas carburized 8 h at 925 “C (1700 “F), hardened, and tempered. Scanning electron micrograph of fractured carburized case. See (g). (g) Not polished, not etched, 1100x. Same as (f), but a higher magnification. Fractured carburized case consists of carbide, retained austenite, and tempered martensite. (h) Not polished, not etched; 23x. Same as (f), except a scanning electron mrcrograph of fractured uncarburized core material (low-carbon martensite). Fracture surface is fibrous. (j) Not polished, not etched; 1100x. Same as (h), but at higher magnification, showing that fractured uncarburized core material has elongated dimples formed dunng transgranular rupture

Alloy Steel / 449

8622,8622H,

862

2RH

Chemical

Composition. 8622. AISI and UNS: 0.20 to 0.25 C, 0.70 to 0.90 Mn, 0.035 Pmax, 0.040 S max, 0.15 to 0.30 Si, 0.40 to 0.70 Ni, 0.40 to 0.60 Cr, 0.15 to 0.25 MO. UNS H86220 and SAE/AISI 8622H: 0.19 to 0.25 C, 0.60 to 0.95 Mn, 0.15 to 0.35 Si, 0.35 to 0.75 Ni, 0.35 to 0.65 Cr, 0.15 to 0.25 MO. SAE 8622RH: 0.20 to 0.25 C, 0.70 to 0.90 Mn, 0.15 to 0.35 Si, 0.40 to 0.70 Ni, 0.40 to 0.60 Cr, 0.15 to 0.25 MO

Recommended

Tempering.

Characteristics.

Case Hardening.

Steels (U.S. and/Or

Foreign).

Except for a slightly higher carbon range, 8622H has an identical composition to 8620H, and the characteristics for 86228 are approximately the same as those for 8620H. Because of the higher carbon range, as-quenched surface hardness is slightly higher for 8622H, approximately 39 to 45 HRC. The hardenability band for 8622H, is adjusted upward just slightly when compared with 8620H. In some carburizing applications, steels that are higher in carbon content have been used to attain a higher core hardness which permits thinner cases. These steels use shorter carburizing cycles and save energy

Forging. Heat to 1245 “C (2275 OF) maximum. Do not forge after temperature of forging stock drops below approximately 900 “C (1650 “F)

Practice

malizing; or by heating to 885 “C (1625 “F), cooling rapidly to 660 “C (1220 “F), and holding for 4 h; or by heating to 790 “C (1455 “F), cooling rapidly to 660 “C (1220 “F), and holding for 8 h

8622. UNS G86220; SAE 5404.5770; (Ger.) DIN 1.6543; (U.K.) B.S. 805 A 20.8622I-I. UNS H86220; ASTM A304; SAE 5407; (Ger.) DIN 1.6543; (U.K.) B.S. 805 A 20

Similar

Heat Treating

Normalizing. Heat to 925 “C (1695 “F). Cool in air Annealing. Structures having best machinability are developed by nor-

Temper all carburtzed or carbonitrided parts at 150 “C (300 “F), and virtually no loss of case hardness will result. If some decrease in hardness can be tolerated, toughness can be increased by tempering at somewhat higher temperatures, up to 260 “C (500 “F) See carburizing and carbonitriding practices described for 8620H. Gas nitriding and ion nitriding are alternative processes

Recommended l l l l l

l l

Processing

Sequence

Forge Normalize Anneal (if required) Rough machine Semifinish machine, allowing only grinding stock, no more than 10% or the case depth per side for carburized parts. In most instances, carbonitrided parts are completely finished in this step Carburize or carbonitride and quench Temper

450 / Heat Treaters

Guide

8822H: Hardenability

Curves. Heat-treating 925 “C (1700 “F)

(1700 “F). Austenitize:

Hardness purposes J distance, mm 1.5 3 5 7 ? I1 13 15 ZO !5 30 35 $0 $5 50

Hardness purposes I distance, VI6in.

,

$ 3 IO I1 12 13 14 15 16 18 20 22 24 26 28 30 32

limits for specification Hardness, HRC Minimum Maximum 50 50 47 43 39 35 32 31 28 26 25 24 24 24 24

43 39 34 28 25 22 20

...

limits for specification Hardness, HRC Minimum Maximum 50 49 47 44 40 37 34 32 31 30 29 28 27 26 26 25 25 24 24 24 24 24 24 24

43 39 34 30 26 24 22 20

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 925 “C

Alloy Steel / 451

8822RH: Hardenability “C (1700 “F). Austenitize:

Hardness purposes J distance, ‘/,6 in. I -l 3 1 5 b 7 B 9 IQ II 12 IS I-l IS 16 I8 10 12 !-I 16 18 10 32

Hardness purposes I distance, mm I.5

> II

13 I5 !O !S SO $5 u) 15 i0

Curves. Heat-treating 925 “C (1700 “F).

limits for specification Eardness, ARC Maximum Minimum 49 -17 45 II 38 35 32 30 29 28 17 26 25 21 21 23 ‘3 22 22 2’ 22 22 22 21

4-t II 37 32 29 27 2-l 22 21 20

limits for specification Eardness, HRC hlinimum Maximum 49 17 4-l -lo 36 32 30 28 25 23 22 22 22 22 22

4-I -II

36 31

28 2-l 22 20

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 925

452 / Heat Treaters

Guide

8822, 8622H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure

8622H: End-Quench Hardenability Distance from quenched surface '/,6 in. mm

I 7 ; -1 5 6 7

8 Y I0 II 12

Hardness, HRC max min

Distance from quenched surface l/l6 in. mm

Hardness,

HRC man

I.58

SO

13

I3

20.54

27

1.71 3.16 6.32 7 90 9.48 I I.06 126-l I-1.22 15.80 17.38 18.96

17 49 4-l 10 37 3-l 32 31 30 29 ‘8

3-l 39 30 26 21 21 20

I5 II I6 I8 20 22 24 26 28 30 31

x.12 23 70 25 28 284-I 31.60 31.76 37.92 -I I .08 J-l.21 47.4) 50.56

26 25 25 2-l 2-l 2-l 2-l 2-l 2-l ‘-I

452 / Heat Treaters

Guide

8625,8625H Chemical

COIIIpOSitiOn. 8625. AISI and UNS: 0.23 to 0.33 C. 0.70 toO.90 hln. 0.035 Pmas. O.O-!OS max.0.1.5 toO.3OSi. 0.30 too.70 Ni.O.10 to 0.40 Cr. 0. IS to 0.3 hfo. UNS H86250 and SAE/AISI 86258: 0.22 to 0.28 C. 0 60 to 0.95 hln. 0.15 to 0.35 Si. 0.35 to 0.7s Ni. 0.3s to 0.65 Cr. 0. IS to 0.3 hlo

Similar

Steels (U.S. and/or Foreign).

SPEC hllL-S-16974: A304 SAE J I’68

SAE 1104. 1770. 86258.

8625.llNS 686250: hill 1rNS H842SO: ASTM

Characteristics.

Identical to 86ZOH swept for higher carbon range. Hhich results in a higher as-quenched hardness (approsimately -IO to 46 HRC). and some\\ hat higher hardenabilitl. Case hardening by carburizinp or carbonitriding are the heat treatments most often used. Has come into more extensive use to sa\e energy in carburirinp. Weldable. but alloy steel welding practice must be used

Annealing.

Structures ha\ ing best machinability are developed by normalizing; or bl heating- to 885 “C ( 1625 “F). cooling rapidly to 660 “C ( I220 “FL and holding tor -I h: or by heating to 790 “C ( 1455 “F). cooling rapidly to 660 jC t 1220 “F). and holding for 8 h

Tempering.

Temper all carburized or carbonitrided parts at IS0 “C (300 “F). and virtualI) no loss of case hardness will result. If some decrease in hardness can be tolerated, toughness can be increased by tempering at someu hat higher temperatures. up to 260 “C (SO0 OF)

Case Hardening. See carburizing and carbonitriding practices described for 862OH. Ion nttridinp and gas mtriding are alternative processes

Recommended l l l

Forging.

Heat to 1315 “C (2775 “F) maslmum. Do not forge after temperature of forging stock drops belot+ appro\imatel> 900 “C ( 1650 “F)

Recommended

Heat Treating

l l

Practice l

Normalizing.

Heat to 915 ‘C ( IhYS ;F). Cool in air

l

Processing

Sequence

Forge Normalize Anneal (ifrequired) Rough machine Ssmkinish machine. allo\\ing. only grinding stock. no more than IO% of the case depth per side for carbuhzed parts. In most instances. carbonitrided p‘artutswe completely finished in this step Carbunze or carbonitride and quench Temper

Alloy Steel / 453

8625: Hardenability

Curves. Heat-treating

(1650 “F). Austenitize:

iardness w-poses distance, qm

.5

1 3 5 :0 :5 IO I5 Kl 15 i0

iardness wrposes distance,

‘16in.

.O 1 2 3 4 5 6 8 !O !2 !4 !6 !8 IO 12

870 “C (1600 “F)

limits for specification Badness, HRC Maximum Minimum 52 51 48 45 41 38 35 33 29 28 21 26 26 26 25

45 40 35 31 28 25 23 21

limits for specification Hardness, HRC hlahum hlinimum 52 51 48 46 43 40 31 35 33 32 31 30 29 28 28 27 27 26 26 26 26 25 25 25

45 41 36 32 29 21 25 23 22 21 20

.

temperatures

recommended

by SAE. Normalize

(for forged or rolled specimens

only): 900 “C

454 / Heat Treaters

Guide

8625, 8625H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure

8625H: End-Quench Hardenability Distance From quenched surface ‘/,6 in. mm I

Hardness, ERC min maw

Distance from quenched surface ‘/,6 in. mm

HidlleSS,

HRC max

IO

1.58 3.16 J.74 6.32 7.90 9.48 Il.06 12.64 14.22 15.80

52 51 18 46 43 10 37 3s 33 32

45 -II 36 37 29 27 2s 23 22 21

IS I3 IS lb 18 20 22 2-l 26 28

20.5-I 22.12 13 70 3.18 28.4-I 31.60 31.76 37.92 4108 44.2-I

29 38 28 27 27 26 26 26 26 2s

II I2

17.38 18.96

31 30

20

30 32

47.10 50.56

2s 75

2 3 -I 5 6 7 8 9

454 / Heat Treaters Guide

8627,8627H Chemical

COIIIpOSitiOn. 8627. AISI and UNS: 0.25 to 0.30 c. 0.70 to0.90Mn.0.03SPmax.0.030Smax,0.lSto0.30Si,0.~0to0.70Ni.0.~0 to 0.60 Cr. 0. I5 to 0.25 Mo. UNS A86270 and SAE/AISI 86278: 0.24 to 0.30 C. 0.60 to 0.95 Mn. 0.15 to 0.35 Si, 0.35 to 0.75 Ni. 0.35 to 0.65 Cr. 0. IS to 0.25 MO

‘F) per h; or heat to 760 “C ( l-t00 “F). cool rapidly and hold for 8 h

Direct Hardening. Tempering.

Austenitize

to 665 “C (I 230 “F),

at 870 “C (1600 “F), and quench in oil

After direct hardening. After quenching. to provide the desired hardness

reheat to the tem-

Similar Steels (U.S. and/or Foreign). 8627.llNS G86270; ShE

perature required

J-IO-L J770.86278.

and carbonitriding practice deCase Hardening. See carburizing scribed for 8620H. Ion nitriding and gas nitriding are suitable processes

LINS H86270:

ASTM

A3O-t; SAE J I268

Characteristics. Has a borderline composition. with a carbon content near the maximum used for case hardening. but at ahout the minimum suitable for direct hardening. Used for both as demanded. however. Asquenched surface hardness of approximately 12 to 38 HRC can be expected. Hardenability band for 8627H is slightly higher than for 862SH Forging. Heat to 1230 “C (2250 “F) maximum. Do not forge after temperature of forging stocb drops below approximately 900 “C ( I650 “F). For direct hardening, see tempering curve

Tempering.

After case hardening. Temper all carburized or carbonitridsd parts at I SO “C (300 “F). and Gtually no loss of case hardness will result. If some decrease in hardness can be tolerated, toughness can be increased hy tempering at somen hat higher temperatures. up to 260 “C (500 “F). For direct hardening, see tempering curve

Recommended l

Recommended Heat Treating Practice Normalizing. Heat to 900 “C (I650 “FL Cool in air Annealing. For a predominantly pearlitic structure. heat

to 8-0 “C (I 555 “F). cool rapidly to 730 “C ( I350 “F), then cool to 6-10 “C ( I I85 “F). at a rate not to exceed I I “C (20 “F) per h: or heat to 815 “C (15% “F). cool rapidly to 665 “C (I230 “F). and hold for 6 h. For a predominantly spheroidized structure, heat to 760 “C ( l-t00 “F). cool rapidly to 730 “C I I350 “Fj, then cool to 650 “C ( I200 “F). at a rate not to exceed 6 “C ( IO

l l l l

l l l

Processing

Sequence

Forge Nomralize Anneal (if required) Rough machine Semitinish machine. allo~iing only grinding stock, no more than 10% of the case depth per side for carburized parts. In most instances, carbonitrided parts are completely tinished in this step Case harden or direct harden Quench Temper

Alloy Steel / 455

8627H: Hardenability (1650 “F). Austenitize:

Hardness purposes J distance, mm 1.5

2

I1 13 15 20 25 30 35 40 45 50

Hardness purposes I distance, !iSill.

i 4 ) 10 II

12 13 14 15 16 18 20 !2 24 26 28 30 32

Curves. Heat-treating 870 “C (1600 “F)

limits for specification Aardness, Maximum

ARC hbimum

47 43 38 34 31 21 25 24 21 20

54 53 50 41 44 41 38 35 32 30 28 27 27 27 27

limits for specification Hardness, Maximum

54 52 50 48 45 43 40 38 36 34 33 32 31 30 30 29 28 28 28 21 27 27 21 21

q RC hGtknum 47 43 38 35 32 29 27 26 24 24 23 22 21 21 20 20

. .

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 900 “C

456 / Heat Treaters

Guide

8627, 8627H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure

8627H: End-Quench Hardenability Distance From quenched ‘surface I 16in. mm

Hardness. HRC mm min

Distance From quenched iut-race ‘.&ill. mm

Hardness. HRC nlas min

456 / Heat Treaters

Guide

8630,863OH Chemical Composition. 8630. MS1 and UNS: 0.28 to 0.33 C. 0.70 IO (J.90 hln. 0.035 P mxs. 0.010 S ma\. 0. IS to 0.30 Si. 0.10 to 0.70 Ni. 0.40 to 0.60 Cr. 0. IS to 0.15 hlo UNS H86.300 and SAE/AISI 86308: 0.27 to 0.33 C. 0.60 to 0.95 hln. 0.15 to 0.35 Si. 0.3.i to 0.75 Ni. 0.35 to 0.65 Cr. 0. IS to 0.25

Similar

hlo

Steels (U.S. and/or Foreign).

863O.llNS G86300: AhlS

6280. 6% I. 635s. 6530. 6550: ASThl ,432 A?? I : MlL SPEC hlIL-S1697-l; SAE J-IO-t. J-II?. 5770: tGsr.) DIN l.hS-lS: tltnl.) UNI 30 NiCrhlo 2 KB. 8630H. 1lNS H86300: ASThl A.301: S.4EJ 1268; tGer.) DIN I.6S-lS. tltal.) 1lNl 30 NiCrhlo 2 KE3

Characteristics.

A medium-carbon steel. Responds rendil> to direct hardening. As-quenched surfxe hardness usunlly ranges from npproximateI, -t6 to S2 HRC Its hardennhilit> band is s~milur IO other 86XXH steels. Seldom used tor case hardening h> curburirinq or carbomtridinp hecause of its carbon content. Genernll~ a\ ailahle in various product forms mcluding seamless tubing used in productne \\elded structures. Forges ensil! rmd can he melded hy virtually an\ of the \rell-knwn techniques. Because of its relattvel~ high hardenahtltt~. allo) steel practtce must he used in welding

Forging. temperature

Hent to 1230 “C t22SO “F) maximum. Do not forge after of forging stock drops MOM approximateI> 900 “‘C i I650 “F)

Recommended Normalizing.

Heat Treating

Practice

Heat to 900 “C t IhSO ‘F). Cool in air. In aerospace practice. parts are normalized 3: 000 ‘C I I650 “F)

Annealing. For a prsdonunantl~ psxlitic structure. heat to 835 “C t IS55 “FI. cool rapidly to 730 “C t I3SO “F). then cool to 610 “C t I I80 “F). at a rate not to exceed I I “C t 20 “F) per h: or heat to X-0 “C f IS55 “F). cool rupidl> to 66s ‘C t I230 “FI. and hold for 6 h. For a predominantly spheroidtzed \tructure. heat to 760 ‘C t l-IO0 ‘F). cool rapidly to 730 “C I I350 “F). then cool to 650 “C t I200 “F). at a rate not to exceed 6 “C t IO “FJ per h: or heat to 760 “C t l-IO0 “F). cool rapidly to 665 ‘C I I230 “F). and hold for 8 h In aerwpuce pmcoce. parts are unnsalsd at 84S jC t IS55 “F). then cooled to below S-IO“C I I(NHI “F) at ~1mte not to exceed 95 ‘C (205 “F) per h Hardening. Austenitire at 870 “‘C I 1600 “F). and quench in oil. Flame hardeninp. _eas nitridinp. ion nitriding. carhonitriding. and martemperinp are alternattve processes. Qusnchunts include \\uter and polymers. In aerospace practice. austsmtize at XSS ‘YY t IS70 “F). and quench in oil or poll mer Tempering. providing

*After quenchtng. reheat to the temperature required the desired hardness or other mechanical properties

Recommended

Processing

Forge Nomlalize >\MtXll

Rough and semifinish machine Austenitize and quench Temper Finish machine

Sequence

for

Alloy Steel / 457

8630H: End-Quench Hardenability Distance from quenched surface ‘/lb in. mm I 7 ; -I s 6 7 8 9 I0 II II

8630:

I..58

Distance from quenched surface l/16 in. mm

Eardness. HRC may min

Hardness. HRC min mas

43 71 16

S6 55 54

-19 46 -1.3

IS I-l 15

20.5-l 22.12 23.70

33 33 3’

23 2). 77

6.31 7.90 9.48 II.06 12.64 I-l 22 15.80 17.38 18.96

52 50 47 4-l II 39 37 3s 31

39 ss 32 29 28 17 26 ‘9 2-l

16 18 20 ‘2 ‘-I ‘6 28 SO 32

25.28 2X.44 31 60 34.76 37 92 11.08 J-l.24 47 40 SO.56

;; 30 30 29 29 29 29 29 3

I; 21 20 20

Approximate

Critical

Points

8630: End-Quench

Temperature Critical point

“C

OF

735 795 71s 660

I?SS 1460 1370 I220

Hardenability. Composition: 0.30 C, 0.80 Mn, 0.54 Ni. 0.55 Cr, 0.21 MO. Austenitized at 870 “C (1600 “F). Grain size: 9

8630: Isothermal Transformation

Diagram. Composition: 0.30 C, 0.80 Mn, 0.54 Ni. 0.55 Cr. 0.21 MO. Austenitized at 870 “C (1600 “F). Grain size: 9

458 / Heat Treaters

Guide

8630: Continuous Cooling Transformation Austenitized

8630:

Diagram. Composition:

0.30 C, 0.80 Mn, 0.020 P, 0.020 S, 0.25 Si, 0.55 Ni, 0.50 Cr, 0.20 MO.

at 850 “C (1560 “F)

Effect of Heat Treatment

Hent treatment

H’ater quenched from 84.i ‘C I IS55 “FL rempered ~~180°C (900 “FI \\aslerquenchrd from 84S ,‘C I ISSS FL kmpered at 5-M) “C I IO(w) ‘FI \Varer quenched from 845 ’ C I I SSS “FL wmperedat 5% “Cc I IOO’F,

‘/z in. (13 mm)

8630: Suggested Practice)

on Hardness Size round measured in 2in. I In. Jill. (2Smm) (51 mm) (IO2 mm)

201 302

IS6 I87 3.1

I87 269

I87 235

2Yi

269

23.5

217

269

211

227

I97

620-860 hlPa (!JO-125ksi) I I ) 650 C I l~(N)‘l=~ 1216fiO’C ~12iO”F1 I

ca~HeatrdwWS”C~ 1555‘~F~.iuma~ecoolsda~ I I “C~2O”F~p~rhour1062S “CI I ICS ,F). cooled in ar. fb) Hrnred to 870 “C ( I600 “FL cooled in air. Source: Rrpuhtic Sttxl

I ,Qusnsh

Tempering

Temperatures

(Aerospace

Tensile strength range 865-1035 hlPa 1035-1175 MPa 1175-1210 MPa IWO-1380 MPa (12515Oksi) (1%17Oksi) (17048Oksi) (MI-200 ksi) sso ,‘C I 103 ‘F, 5.50 “C I 1025 “FI

In ml orpol!mrr.

185 “C (905 “F1 510°C 1950 -FI

-l-lo (825 -l-lo (825

“C “FJ “C “FJ

121 C)uench in skater Source: AhlS 2759/l

370 “C (700°F) 370 “C (700 “Fj

Alloy Steel / 459

8630H: Hardenability Curves. Heat-treatinq (1650 “F). Austenitize:

iardness wrposes I distance, nm 1.5

)

I1 13 15 !O !5 !O I5 K.l 6 i0

iardness wrposes distance,

‘16io.

0 1

2 3 4 5 6 8 0 2 4 6 8 0 2

870 “C (1600 “F)

limits for specification Hardness, Maximum

HRC Minimum

49 46 42 38 33 29 27 26 23 21 20 .

56 55 54 51 48 44 41 38 34 31 30 29 29 29 29

limits for specification Hardness, HRC hlaximum

56 55 54 52 50 47 44 41 39 37 35 34 33 33 32 31 30 30 29 29 29 29 29 29

Minimum

49 46 43 39 35 32 29 28 21 26 25 24 23 22 22 21 21 20 20

temperatures -

recommended

by SAE. Normalize (for forged or rolled specimens

only): 900 “C

460 / Heat Treaters

Guide

8830: Hardness vs Tempering Temperature. Composition: 0.28 to 0.33 C, 0.70 to 0.90 Mn. 0.20 to 0.35 Si, 0.40 to 0.70 Ni, 0.40 to 60 Cr. 0.15 to 0.25 MO. Forged at 1230 “C (2250 “F). Normalized at 900 “C (1650 “F). Furnace cooled from 815 to 870 “C (1500 to 1600 “F). Tempered 2 h. Maximum annealed hardness, 179 HB. Hardness normalized in test size, 225 HB. Source: Republic Steel

460 / Heat Treaters

Guide

86B30H Chemical

Composition.

SAE/AISI 86B30H:o27 KI 0.33 c.O.60

to0 95 hln.0.035 Pmas.O.040S ma\.O.lS to0.30Si.O.3S too.75 Ni.0.35 to 0.65 Cr. 0.1.5 to 0.5 MO. O.OOOS to 0.003 B. UNS H86301 and SAE/AISE 86B30H: 0.27 to 0.33 C. 0.60 to 0.95 hln. 0. IS to 0.3s Si. 0.35 to 0.75 Ni. 0.35 too.65 Cr.0.15 to025 hlo. B (can beexpected to heO.OOOS to 0.003 percent 1

Similar

Steels (U.S. and/or Foreign).

UNS

G863OI:

ASThl

.A?W; S,-IE J 1268

Annealing.

For a predominantly pearlitic structure, heat to 8-15 “C (I 555 “F). cool &a I! to 730 “C t 1350°F~ then cool to 610 “C (I I85 “F). at a rate not to exceed I I ‘C (20 ‘F) per h; or heat to 8-U “C (IS55 “F), cool rapid11 to 66s “C t I230 “F). and hold for 7 h. For a predominantly sph?roidized structure. heat to 760 “C t 1100 “F). cool rapidly to 730 “C t I?0 “F). then cool to 650 ‘C ( I200 jF). at ;L rate not to exceed 6 “C ( IO “‘FJ per h; or heat to 760 ‘C I 1400 ‘F). cool rapidly to 665 “C (I 230 “F), and hold for IO h

Hardening.

Characteristics. Identical in composition to 8630H \\ ith boron added. The applications of 86830H are also 5inilx to those for 8630H. 86B?OH ib selected for ik+ increased hurdsnnbilit!. 1%hich IS a result of the horon addition. As-quenched surfxe hardnecs of86B3OH generally ranges from 46 to S1_ HRC. about the same as for 8630H. Forging and heat trenting prwedure3 for 86B30H are essential11 the same a\ those used for X630H

hardening. processes

Tempering. the tempemture

Forging.

Heat to I230 “C (2250 “FI maximum. Do not forge after of forging stock drops below approximateI> 92s ‘C t I695 “F,

l l l

Recommended

Heat Treating

Practice

l l

Normalizing.

Heat to 900 “C t 16.50 “‘FL Cool in uir

l

at 870 “‘C t 1600 “F). and quench in oil. Flame cxbonitriding. and ion nitriding anz suitable

Parts should be tempered immediateI) after quenching which u ill pro\ ids the requued hardness

Recommended l

tcmpersturc

Austenitire pas nitridinp.

Processing

Sequence

Forge Normalize ,kineal Rough and semifinish machine Austenitizr and quench Temper Finish machine

86B30H: Hardness vs Tempering Temperature. average based on a fully quenched structure

Represents

an

at

Alloy Steel / 461

88630H: Hardenability

Curves. Heat-treating

“C (1650 “F). Austenitiie:

870 “C (1600 “F)

iardness wrposes I distance, nm 1.5 \ i 1 9 I1 13 15 20 z5 30 35 40 15 50

limits for specification Eardness, HRC hlaximum hliuimum 56 56 55 55 54 54 53 53 52 50 48 46 43 41 40

49 49 48 48 48 47 46 44 39 35 33 30 28 27 25

iardness limits for specification Burposes distance, \6 in.

0 1 2 3 4 5 6 8 .O :2 !4 16 !8 IO I2

Hardness. ERC Maximum hlinimum 56 55 55 55 54 54 53 53 52 52 52 51 51 50 50 49 48 41 45 44 43 41 40 39

49 49 48 48 48 48 48 47 46 44 42 40 39 38 36 35 34 32 31 29 28 21 26 25

temperatures

recommended

by SAE. Normalize

(for forged or rolled specimens

only): 900

462 / Heat Treaters

Guide

86B30H: End-Quench Hardenability Distance from quenched surface 146h. mm 1

1.58

2 3 4 5 6

3.16 4.14 6.32 7.90 9.48

7

11.06

8 9

12.64 14.22 15.80

10 11 12

17.38 18.96

Hardness, HRC max min 56 55 55 55 54 54 53 53 52 52 52 51

49 49 48 48 48 48 48 41

46 44 42 40

Distance from quenched surface ‘/lb in. mm 13 14 15 16 18 20 22 24 26 28 30 32

20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40 50.56

Hardness, HRC mar min 51 50 50 49 48 41 45

44 43 41

40 39

39 38 36 35 34 32 31 29 28 27 26 25

8637,8637H Chemical COrTIpOSitiOn. 8637. AISI and UNS: 0.35 to 0.40 C, 0.75 to 1.00 Mn. 0.035 Pmax. 0.040 S max. 0.15 to 0.30 Si, 0.40 to 0.70 Ni, 0.40 to 0.60 Cr. 0.15 to 0.25 MO. IJNS II86370 and SAE/AISI 8637I-I: 0.34 to 0.41 C, 0.70 to 1.05 Mn, 0.15 to 0.35 Si, 0.35 to 0.75 Ni, 0.35 to 0.65 Cr, 0.15 to 0.25 MO Similar

Steels (U.S. and/or

J404,J412.J770.8637H.

Foreign). 8637. UNS G86370; SAE UNS H86370; ASTM A304; SAE 51268

Characteristics. A medium-carbon, low-alloy steel, which is widely used for a variety of machinery components because of its ability to be heat treated for high strength and toughness. Used for shafts requiring high fatigue strength. Amenable to nitriding for resistance to surface wear and for greater fatigue strength. As-quenched surface hardness ranges from 50 to 55 HRC. Its hardenability is considered fairly high. Is readily forged

“F) per h; or heat to 750 “C (1380 “F), cool rapidly to 665 “C (1230 “F), and hold for 8 h

Direct Hardening. Tempering.

After quenching, reheat immediately to the tempering temperature that will provide the desired combination of mechanical properties

Nitriding. Responds well to ammonia gas nitriding as well as to nitriding in any one of several proprietary molten salt baths. The following is a commonly used cycle for ammonia gas nitriding: l

l l

Forging.

Heat to 1230 “C (2250 “F) maximum. Do not forge after temperature of forging stock drops below approximately 900 “C (1650 “F)

Recommended Normalizing.

Heat Treating

Practice

Heat to 870 “C (1600 OF). Cool in air

For a predominantly pearlitic structure, heat to 830 “C (1525 “F), cool rapidly to 725 “C (1335 “F), then cool to 640 “C (1185 “F), at a rate not to exceed 11 “C (20 “F) per h; or heat to 830 “C (1525 “F), cool rapidly to 665 “C (1230 OF), and hold for 6 h. For a predominantly spheroidized structure, heat to 750 “C (1380 “F), cool rapidly to 725 “C (1335 “F), then cool to 640 “C (1185 “F), at a rate not to exceed 6 “C (10

Parts are austenitized, quenched, and tempered at 540 “C (1000 “F) or higher. (Tempering temperature must always be higher than the nitriding temperature) Finish machine Nitride in ammonia gas for 10 to 12 h with an ammonia gas dissociation of 25 to 30%

See processing data for 4140H for other nitriding cycles

Recommended l l

Annealing.

Austenitize at 855 “C (1570 OF), and quench in oil

l l l l l l

Processing

Sequence

Forge Normalize Anneal Rough and semilinish machine Austenitize and quench Temper Finish machine (grind if required) Nitride (optional) 8637, 8637H: Hardness vs Tempering Temperature. sents an average based on a fully quenched structure

Repre-

Alloy Steel / 463

8637H: Hardenability

Curves. Heat-treating temperatures 845 “C (1555 “F)

(1600 “F). Austenitize:

iardness wrposes I distance, nm .5 ! i 1

a 1 3 5 !O !5 10 15 10 15 i0

Hardness purposes J distance, %ain. I 2 3 4 5 5 7 5 J IO I1 12 3 14 .5 ‘6 .8 !O !2 ,4 !6 !8 50 12

limits for specification Hardness, HRC Minimum Maximum 59 59 58 57 55 54 52 50 45 41 38 36 35 35 35

52 51 49 47 43 39 36 33 29 21 25 24 24 23 23

limits for specification Hardness, HRC Minimum Maximum 59 58 58 51 56 55 54 53 51 49 47 46 44 43 41 40 39 37 36 36 35 35 35 35

52 51 50 48 45 42 39 36 34 32 31 30 29 28 21 26 25 25 24 24 24 24 23 23

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

464 / Heat Treaters

Guide

8637H: End-Quench Hardenability Distance from Hardness, HRC max min 1 2 3 4 S 6 7 8 9 10 11 12

1.58 3.16 4.74 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38 18.96

59 58 58 57 56 55 54 53 51 49 47 46

52 51 50 48 45 42 39 36 34 32 31 30

Distance from quenched surface mm 516 in. 13 14 15 16 18 20 22 24 26 28 30 32

20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40 SO.56

Hardness, HRC max min 44 43 41 40 39 37 36 36 35 35 35 35

29 28 27 26 25 25 24 24 24 24 23 23

464 / Heat Treaters

Guide

8640,864OH Chemical Composition. 8640. MS1 and UN.9 0.38 to I .OO hln. 0.035 Pmw.. O.(J-lOS max. 0. IS to 0.30 Si. 0.40 to 0 60 Cr. 0. IS to 0.25 hlo. 86JOH. MS1 and LJNS: 0.37 IO I.05 hln.0.0.35 Pmw O.O-!OS max.O.lS to0.3OSi.0.35 to 0.65 Cr. 0. IS to 0.25 hlo Similar

Steels (U.S. and/or Foreign).

to 0.43 C. 0.75 to 0.70 Ni.O.41 to 0.4-I C. 0.70 toO.7S Ni.0.35

l

l l

1lNS G864OO: ASThl A3O-l. A32 hllL SPEC hllL-S-l6974 SAE 140-I. J412. 5770: t&r., DIN 1.6546; (Ital.) LINI 40 NiCrhlo 2 KB: tL1.K.) B.S. Type 7. g&OH. 1lNS H86-W: 4SThl MO-k SAE J-107: tGer. ) DIN I .6546; t Ital. I LINI 40 NiCrMo 2 KB: tL1.K.) B.S. Type 7 8640.

Characteristics. Probably the most u idsI! used medium-c&on. IOH allo) steel. A~ailnhls tn various product fomls. Can be heat treated to high values of strength and toughness and. if desired. can btt nitrided to achie\ e wrfxe.; that help to resist abrasion and furtha increase fatigue strength. Depending on the precise carbon content. an as-quenched surface hardwss of approximately 52 to 57 HRC can be expected. Hardrnnbilitj is rslati\4> high. Can he forged by an! one of thz various forging methods

of

2s

to 3oc

SW processuy

data for 4 I-IOH for other nitriding qcles

Recommended l l l l l l l l

Forging.

Parts xs austenitired. qwnched. and tsmpered at S-IO “C (1000 “F) or higher. (Tempering temperature must nl~aqs be higher than tht nitriding tsmpsraturs t Finish machine Nitride in ammonia gas for IO to 12 h u ith an ammonia gas dissociation

Processing

Sequence

Forge Normalize Anneal Rough and senitinish machine Auhtrnitiz? and qurnch Ttmpcr Finish machine cgnnd if rzqulred) Nitride (optional)

Heat to 1230 “C cYS(J “F) m;Ixm~um. Do not forge after temperature of forging stozh drops MOM sppro\imatsl> 900 “C ( I hS(J “F,

Recommended Normalizing.

Heat Treating

Practice

Hzat to 870 “C t 1600 “FL Cool in air

Annealing. Far a predominantI! psnrlitlc struuctur~. heat to 830 “C t IS25 “FL cool rapidI) to 725 ‘C t I335 “FL then cool to 640 “C t I I85 ‘F). at a rate not to exceed I I ‘C (20 “F) per h: or heat to 830 “C ( IS25 *FJ. cool rapidly to 665 “C (I230 “FL and hold for 6 h. For a predominantI> spheroidixd structure. hat to 750 “C t 1380 “‘FI. cool rapid11 to 725 “C t 133.5 “FL then cool to 640 YI ( I I85 “FL at a rate not to csceed 6 “C t IO ‘F) per h: or htat to 750 “C t 1380 ‘FL cool rapid11 to 665 “C I 1230 “F). and hold for 8 h Hardening.

Austenitlzc

at MS “C t IS70 ‘FL and quench in oil

Tempering. pcrrltun

After quenchinp. reheat imnwdiatcl~ to th? tempenng trmthat will provide the deswd combination o~mschanicnl properttss

Nitriding. Responds HA to ammonia gas nitridinp as well as to nitriding in any one of szvcral proprietary molten salt baths. Ths following is a commonI) used cycle for ammonia gas nitriding:

8640: Hardness vs Diameter. Composition: 0.38 to 0.43 C, 0.75 to1.00Mn,0.040Pmax.0.040Smax,0.20to0.35Si,0.40to0.70 Ni. 0.40 to 0.60 Cr, 0.15 to 0.25 MO. Test specimens were normalized at 870 “C (1600 “F) in over-sized rounds, quenched from 845 “C (1555 “F) in oil in sizes shown, tempered at 540 “C (1000 “F). Tested in 12.8 mm (0.505 in.) rounds. Tested from bars 38 mm (1.50 in.) diam taken at half radius position. Source: Republic Steel

Alloy Steel / 465

8840: Continuous

C oling Curves. Composition: 0.37 C, 0.67 Mn, 0.25 Si, 0.56 Ni, 0.44 Cr, 0.18 MO. Austenitized at 845 “C (1555 “F). Grain size: 7. AC,, 795 “C (1460 “F); AC,, 745 “C (1370 “F). A: austenite, F: ferrite, P: pearlite, B: bainite, M: martensite

8640H: End-Quench Hardena bility Distance from quenched surface ‘&, in. mm 1 2 3 4 5 6 7 8 9 10 11 12

1.58 3.16 4.74 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38 18.96

Hardness, HRC max mio 60 60 60 59 59 58 57 55 54 52 50 49

53 53 52 51 49 46 42 39 36 34 32 31

Distance from quenched su t-face 916 in. mm 13 14 15 16 18 20 22 24 26 28 30 32

20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40 50.56

Hardness. HRC ma\ mill 47 45 44 42 41 39 38 38 37 37 37 37

30 29 28 28 26 26 25 25 24 24 24 24

8640: Hardness Gradients. Nitrided to 20 to 30°0 dissociation.

(a) Nitrided for 7 h: (b) nitrided for 24 h; (c) nitrided for 48 h

466 / Heat Treaters

Guide

8840H: Hardenability (1600 “F). Austenitize:

Hardness purposes I distance,

mm

I1 3 .5 !O !5 10 \5 lo 15 i0

Curves. Heat-treating 845 “C (1555 “F)

limits for specification Hardness. HRC Minimum hlatimum 60 60 60 60 58 57 55 54 48 43 40 39 38 37 31

53 53 52 50 47 42 38 36 31 21 26 25 24 24 24

Hardness limits for specification wrposes I distance, /I6 in.

J IO 11 12 13 14 5 6 8 !O !2 !4 !6 !8 10 12

Hardness, HRC hlinimum Maximum 60 60 60 59 59 58 51 55 54 52 50 49 41 45 44 42 41 39 38 38 37 37 31 31

53 53 52 51 49 46 42 39 36 34 32 31 30 29 28 28 26 26 25 25 24 24 24 24

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

Alloy Steel / 467 8640:

Approximate

Critical

Points

8640H: Variation of Brine11 Hardness Measurements.

Critical

point

Tests

done on annealed plain carbon and low-alloy steels

Temperature T

AC, AC, Ar, Ar,

Source: Republic

Svrl

8640: Cooling Curves. Composition: (using interrupted Jominy method)

0.37 C. 0.87 Mn, 0.25 Si, 0.56 Ni. 0.44 Cr, 0.18 MO. Grain size: 7. Austenitized

at 845 “C (1555 GF)

Alloy Steel / 467

8642,8642H Chemical Composition. 8642. AISI and UNS: 0.40 to 0.45 C. 0.75 to I .OO Mn, 0.035 Pmas. 0.040 S ma. 0. IS too.30 Si. 0.30 to 0.70 Ni. 0.40 to 0.60 Cr. 0. I5 to 0.3 hlo. Uh’S HS6420 and SAE/AISI 8642H: 0.39 to 0.46 C, 0.70 to 1.05 Mn. 0. IS to 0.35 Si, 0.35 to 0.75 Ni. 0.35 to 0.65 Cr. 0.15 to0.25 Mo

temperature

Similar

Recommended

Steels (U.S. and/or Foreign).

J4O-l. 1412.5770.8642H.

8642. UNS G86420: SAE UNS H86.420: ASThl A304 SAE Jl268

Characteristics. Change in composition from 864OH is slight. Has essentiall) the same characteristics as described for 864OH. As-quenched surface hardness for 8642H. because the c&on content is slightly higher. is approximately 53 to 59 HRC. Hurdenabilib band is shifted upirard

slightlq for 8647H. methods

Forging.

by any one of the various

forging

Heat to 1230 ‘C (2250 “F) maximum. Do not forge after of forging stock drops brlo~r approximately 900 “C (I 650 W

Normalizing. Annealing.

Can be forged

Heat Treating

Practice

Heat to 870 “C t I600 “FL Cool in air

For a predominantly pearlitic structure, heat IO 830 “C ( IS35 “F). cool rapidl! to 775 “C t 1335 “F). then cool to 610 ‘C (I I85 “F). at a rate not to esceed I I “C t 20 “F) per h: or heat to 830 “C (I 525 “F), cool rapidI!, to 665 “C (I230 “Fj. and hold for 6 h. For B predominantly

468 / Heat Treaters

Guide

spheroidized structure, heat to 750 “C (1380 “F), cool rapidly to 725 “C (I 335 OF),then cool to 640 “C (118.5“F), at a rate not to exceed 6 “C (I 0 “F) per h; or heat to 750 “C (1380 “F), cool rapidly to 665 “C (1230 “F), and hold for 8 h Direct Hardening.

l l

Tempering. After quenching, reheat immediately to the tempering temperaturethat will provide the desiredcombination of mechanicalproperties

Austenitize at 855 “C (1570 “F), and quench in oil

Nitriding. Respondswell to ammoniagas nitriding as well asto ni~ding in any one of several proprietary mohen salt baths. The following is a commonly used cycle for ammonia gas nitriding: l

Seeprocessingdatafor 414OHfor other ni~ding cycles.Flamehardeningand ion nitriding arealternativeprocesses

Parts are austenitized, quenched, and temperedat 540 “C (1000 “F) or higher. (Temperingtemperaturemust always be higher than the nitriding temperature) Finish machine Nitride in ammoniagas for 10 to 12 h with an ammoniagas dissociation of 25 to 30%

Recommended

Processing

Sequence

Forge * Normalize l Anneal l Rough and semifinish machine l Austenitize and quench l Temper l Finish machine (grind if reauired) l Nitride (optionaiy 1 l

8642, 8642H: Hardness vs Tempering Temperature. sents an average based on a fully quenched structure

8642H: End-Quench Distance from quenched surface /16in. mm 1

2 3 4 5 6 7 8 9 10 11 12

1.58 3.16 4.74 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38 18.96

Hardenability

Herdness. ERC max min

62 62 62 61 61 60 59 58 57 55 54 52

55 54 53 52 50 48 45 42 39 37 34 33

Distance from quenched surface l/16 in. mm

13 14 15 16 18 20 22 24 26 28 30 32

20.54 22.12 23.10 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40 50.56

Hardness, HRC

39

26

Repre-

Alloy Steel / 469

8642H: Hardenability Curves. Heat-treating (1600 “F). Austenitize:

Hardness purposes I distance, nm 1.s \

iardness wrposes ; distance, 16 in.

845 “C (1555 “F)

limits for specification Hardness, Maximum

HRC illioimum

62 67 62 61 60 59 58 56 52 47 +I -II -lo 39 39

limits for specification Hardness, Maximum 67 62 62 61 61 60 59 58 57 55 5-l 52 so -19 -18 46 44 4’ -II 40 -IO 39 39 39

HRC biinimum

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

470 / Heat Treaters

Guide

8645,8645H Chemical Composition. 8655. AK1 and LNS: 0.43 to 0.48 C. 0.75 to I .OO Xln. 0.035 Pmax. O.O-lOS max. 0. I5 to0.30Si.0.40 too.70 Ni.0.40 to 0.60 Cr. 0. I5 IO 0.25 Ma IJNS H86450 and SAE/AISI 8645H: 0.Q to 0.49 C. 0.70 to 1.05 hln. 0.035 P max. 0.40 S mlt\. 0. IS to 0.30 Si. 0.35 to 0.75 Xi. 0.35 to 0.65 Cr. 0.15 10 0.25 Mo Similar

Steels (U.S. and/or Foreign).

86-15.l-33 G86-ljO: hlIL

SPEC MLL-S- 16973; SAE J-W. J-l 12.5770.8645H. A30-1: SAE Jl268

LX

H86450: AST\1

Hardening.

Characteristics.

A slightI> louer carbon version of 8650H. Asquenched hardness generally ranges from approximovly 5-l to 60 HRC. depending on the precise carbon content N ithin the allowable range. Considered a relaii\ely hiph-hardenahility steel. Used extensiveI! for a variety of machinery parts where hiph strength is required for riporous senice. including hiphly stressed shafts and springs. Can he forged. although just as is nue for other hipher carbon. high-hardenabilitj steels. forgings of complex shape should he cooled slowI> from the forging temperature 10 minimize the possibility of cracking

Forging. Heat IO 1230 “C (2250 ‘F) maximum. Do not forge after lemperature of forging stock drops helow approximateI! 925 “C (I695 “FL Cool slo\r Iy from rhe forging temperature

Recommended

Heat Treating

Annealing. For a predominantly pearlitic structure. heat to 830 “C ( I525 “F). cool slowly IO 7 IO “C ( I3 IO -‘FL then cool IO 650 “C ( I200 “F), at a rate not to exceed 8 “C (IS “F) per h: or heal to 830 “C (1525 “F), cool rapidI> to 650 ‘C (I200 “FL and hold for 8 h. For a predominantly spheroidized structure. heat to 750 “C (I380 “F). cool rapidly to 715 “C (1320 ‘Fj. then cool to 650 “C ( I200 “Fj. a1 a rate not to exceed 6 “C (IO ‘F) per h: or heat to 750 “C ( I380 “F). cool rapidl) to 650 “C (I 200 “F), and hold for IO h

Practice

hardening. processes

After quenching. pans should be tempered immediately. preferably when they are still warm to the touch. at 150 “C (300 “F) or hipher. For mosl purposes. higher tempering temperatures are used. Selection of tempering temperature is hased on the desired combination of mechanical properties

Recommended

Processing

l

Forge Normalize

l

Anneal

l

Rough and semifinish machine Austenitize and quench Temper Finish machine

l

l

Heat to 870 ‘C ( 1600 ‘FL Cool in air

at 845 ‘C ( IS55 “F), and quench in oil. Flame ion nitridinp. and carbonitiding are suitable

Tempering.

l

Normalizing.

Austenitize gas nitridinp.

l

Sequence

8645, 8645H: Hardness vs Tempering Temperature. Represents an average

8645H: End-Quench Hardenability Distance from quenched surface ‘/&in. mm 1

2 3 4 5 6 7 8 9 10 11 12

1.58 3.16 4.14 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38 18.96

Hardness, EIRC max min

63 63 63 63 62 61 61 60 59 58 56 55

56 56 55 54 52 50 48 45 41 39 37 35

Distance from quenched surface ‘46 in. mm

13 14 15 16 18 20 22 24 26 28 30 32

20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 41.40 50.56

Eardness. ARC

41

27

based

on a fully quenched

structure

Alloy Steel / 471

8545: Microstructures. (a) 2% nital. 825x. Hot rolled steel bar, 25 mm (1 in.) diam, austenitized at 815 “C (1500 “F) for 1 h and furnace cooled, resulting in a fully annealed structure. Dark areas lamellar pearlite. white areas ferrite. (b) 2?L nital. 750x. Same steel and bar size as (a). Austenitized at 815 “C (1500 “F) for 1 h, cooled to 675 “C (1245 “F), and held for 8 h (for spheroidizing). Dark areas, partly spheroidized pearlite, white areas ferrite. See (c). (c) 5% picric acid, 2 1Q ?& HNO,, in ethanol: 5000x. Same bar size as (a) and (b), same heat treatment as (b). Replica electron micrograph shows a structure that consists of partly spheroidized pearlite. (d) 2% nital, 1000x. Same bar size as (a), (b), and (c). Austenitized at 845 “C (1555 “F). water quenched, tempered at 260 “C (500 “F) for 1 h. Tempered martensite. See (e). (e) 29/o nital. 1000x. Same bar size as (a), (b), (c) and (d). Heat treatment same as (d). except tempered at 370 “C (700 “F). Tempered martensite. See (f). (f) 59’0picric acid, 2 1,/2?0HNO,, in ethanol: 10 000x. Same bar size and heat treatment as (e). Electron micrograph of platinum-carbon-shadowed two-stage carbon replica, showing carbide particles that precipitated from the martensite matrix. (g) 2% nital, 1000x. Same bar size as (f), austenitized at 845 “C (1555 “F) for 1 h. water quenched, tempered at 480 “C (895 “F) for 1 h. Compare with (d) and (e); increasing tempenng temperature has little effect on the appearance of the tempered martensite. (h) 5% picric acid, 2 1/2% HNO,, in ethanol; 10 000x. Same bar size and heat treatment as (g). Electron micrograph. made using a platinum-carbon-shadowed two-stage carbon replica, shows particles of carbide that have precipitated from the matrix of tempered martensite

472 / Heat Treaters

Guide

8645H: Hardenability (1600 “F). Austenitize:

Hardness purposes I distance, mm 1.5

Hardness purposes I dislance. %6 in.

IO

I1 12 13 14 15 16 18 !O !2 !4 !6 !8 i0 !2

Curves. H at-treating 845 “C (1555 “F)

limits for specification Hardness, Maximum

HRC Minimum

63 63 63 63 62 61 59 58 54 49 46 43 42 42 41

56 56 55 53 51

48 45 41 34 31 29 28 27 27 27

limits for specification Hardness. 3latimum

63 63 63 63 62 61 61 60 59 58 56 55 54 52 51 49 47 45 43 42 42 41 41 41

HRC \linimum

56 56 55 54 52 50 48 45 41 39 37 35 34 33 32 31 30 29 28 28 27 27 27 27

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

1

only): 870 “C

Alloy Steel / 473

86645,86645H Chemical

Composition.

86845. AISI: 0.43 IO 0.48 C. 0.75 to I .Oo

~ln.O.O3SPmax.0.~0Smax.0.20to0.3SSi.0.~0to0.70Ni.0.~0to0.60 Cr. 0. IS to 0.75 MO. 0.0005 B min. Uh?k 0.13 to 0.48 C. 0.75 to 1.00 \ln. 0.035 Pmax. O.MO S max.0.1. too.30 Si. O.-IO too.70 Ni. 0.10 toO.hOCr. O.lS to 0.25 MO. 0.0005 B min. LXS H&451 and SAE/AISI 86845H: 0.12 to 0.49 C. 0.70 to I.05 Sin. 0.15 to 0.35 Si. 0.35 to O.iS Si. 0.35 to O.hS Cr. 0. IS to 0.X MO. B (can be expected to be 0.0005 to 0.003 percent)

Similar

Steels (U.S. and/or Foreign).

ASTXl

ASl9: SAE J-IO-I. J-II?. ,430-t: SAE J I268

86BG.

5770. 86B45H.

LKS

LNS H&IS

G86JSl. I: ASTY

Characteristics.

LVith the exception of the boron addition. 86B-ISH is identical in composition to 8tiSH. Commercial applications for these ttvo steels are similar. 86BlSH is chosen \vhen more hardenabilitj is needed than can be provided b> 86-lSH. 86B-lSH is significantI> higher in hardenahility. As-quenched surface hardness is the same for the t\io steels. usually ranging from 51 to 60 HRC. Compares fa\orablj uith 86-lSH in forgeability and response to heat treatment

Forging.

Heat to I??0 ‘?I (Z’S0 ‘F) masmium. Do not forge after temperature of forging stock drops helow npprosmiatel> 9X “C ( I695 ‘FI

Recommended Normalizing.

Hardening. .\ustenitize at X-IS ‘C t ISSS ‘F). and quench in oil. Flame hardening. pas nitriding eon nitridinp. carhonitridinp, and fluidized bed nitriding are suitable processes Tempering.

.\fter quenching. parts should be tempered immediateI>. Selection of tcmperinp temperature depends on the desired mechanical properties

Recommended l l l l

Practice

l

Heat to 870 ‘C t I600 ‘FJ. Cool in air

l

86645: Isothermal

Heat Treating

Annealing. For a predominantI> pearlitic structure. heat to 830°C (IXS “F). cool rapidly to 73S ‘C t 1335 ‘FL then cool to 6-10 “C (I I85 “F). at a rate not to exceed I I ‘C (20 “F) per h: or heat to 830 ‘C ( IS25 “F). cool rapidly to 665 ‘C ( I230 “FL and hold for 7 h. For a predominantI> spheroidized structure. heat to 7SO ‘C t 1380 “F). cool rapidly to 72.5 “C ( I.335 ‘F). then cool to 640 ‘C (I I85 ‘F). at a rate not to exceed 6 “C i IO “F) per h: or heat to 750 ‘C i 1380 “FL cool rapidly to 665 “C (I230 “F). and hold for IO h

Transformation

l

Diagram. Composition:

0.45 C. 0.89 Mn, 0.59 Ni. 0.66 Cr, 0.12 MO, 0.0015 at 845 “C (1555 “F). Grain size: 6 to 7

Processing

Sequence

Forge Norninlize Xnneai Rough and semifinish machine Austenitize and quench Temper Finish machine

86B45H: End-Quench Hardenability

B. Austenitized Distance From quenched surface 1,SIbin. mm

Hardness. HRC max miu

Distance frum quenched surface !I16 in. mm

I.1 I-I IS I6 I8 20 22 2-t 26 28 30 32

20.51 ‘2.12

Eardness. ERC max min

59

19

23 70

59 58

48 46

3.X x-u 3 I.60

58 58 5X

4s 12 39

31.76 37.9’ 4 I .08 44.24 47 10 50.56

ST s7 57 57 5b 56

37 35 3-l 32 32 31

474 / Heat Treaters

Guide

86845H: Hardenability Curves. Heat-treating “C (1600 “F). Austenitize: 845 “C (1555 “F)

Hardness purposes I distance, nm

limits for specification Eardoess, Maximum

1.5

63 63 63 62 62 61 61 60 59 58 58 57 57 56 56

s

I1

13 I5 !O !5 50 15 lo

I5

io

iardness wrposes I distance. 4,j in.

0

1 2 3 4 5 6 8 10

!2 !4 !6 !8 IO

I2

temperatures

limits fo

56 56 55 54 53 52 51 51 49 45 40 36 33 32 31

r specification

Hardness. hlasimum

63 63 62 62 62 61 61 60 60 60 59 59 59 59 58 58 58 58 57 57 57 57 56 56

HRC Minimum

ARC Minimum

56 56 55 54 54 53 52 52 51 51 50 50 49 48 48 45 42 39 37 3.5 34 32 32 31

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870

Alloy

86B45: Hardness vs Diameter. Composition: 0.43 to 0.48 C, 0.75 to 1 .OO Mn, 0.040 P max, 0.040 S max, 0.20 to 0.35 Si, 0.40 to 0.70 Ni. 0.40 to 0.60 Cr, 0.15 to 0.25 MO, 0.0005 B min. Approximate critical points: AC,, 720 “C (1330 “F). AC,, 770 “C (1420 “F); Ar,, 695 “C (1280 “F); Ar,, 650 “C (1200 “F). Recommended thermal treatment: forge at 1205 “C (2200 “F) maximum, anneal at 790 to 845 “C (1455 to 1555 “F) for a maximum hardness of 207 HB. normalize at 845 to 900 “C (1555 to 1650 “F) for an approximate hardness of 277 HB, quench from 830 to 855 “C (1525 to 1570 “F) in oil. Test specimens were normalized at 870 “C (1600 “F) in over-sized rounds, quenched from 845 “C (1555 “F) in oil, tempered at 540 “C (1000 “F), and tested in 12.8 mm (0.505 in.) rounds. Tests from bars 38 mm (1.50 in.) and over are taken at half radius position. Source: Republic Steel

Steel

/ 475

86845: Hardness vs Diameter. Composition: 0.43 to 0.48 C, 0.75 to 1 .OO Mn. 0.040 P max, 0.040 S max. 0.20 to 0.35 Si, 0.40 to 0.70 Ni, 0.40 to 0.60 Cr. 0.15 to 0.25 MO, 0.0005 6 min. Approximate critical points: AC,, 720 “C (1330 “F). AC,, 770 “C (1420 “F); Ar,, 695 “C (1280 “F); Ar,, 650 “C (1200 “F). Recommended thermal treatment: forge at 1205 “C (2200 “F) maximum, anneal at 790 to 845 “C (1455 to 1555 “F) for a maximum hardness of 207 HB, normalize at 845 to 900 “C (1555 to 1650 “F) for an approximate hardness of 277 HB, quench from 830 to 855 “C (1525 to 1570 “F) in oil. Test specimens were normalized at 870 “C (1600 “F) in over-sized rounds, quenched from 845 “C (1555 “F) in oil, tempered at 650 “C (1200 “F), and tested in 12.8 mm (0.505 in.) rounds. Tests from specimens 38 mm (1 l/z in.) and over were taken at half radius position. Source: Republic Steel

Alloy Steel / 475

8650,865OH Chemical

Composition. 8650. AISI: 0.48 to 0.53 c, 1~75 to 1.00 Mn.0.~0Pn~lut.0.~0Sn~ax.0.30to0.35Si.0.~0to0.70Ni.0.10to0.60 Cr. 0.15 to 0.35 hlo. UNS: 0.48 to 0.53 C. 0.75 to 1.00 hln. 0.035 P max. 0.0-10 S max. 0.15 to 0.30 Si. O.-t0 to 0.70 Ni. 0.40 to 0.60 Cr. 0. IS to 0.X Mo. UNS H86500 and SAE/AISI 86508: 0.47 to 0.5-I C. 0.70 to I .OS hln. 0.15 to 0.35 Si. 0.35 to 0.75 Ni, 0.35 to 0.65 Cr. 0. IS to 0.35 hlo Similar

Steels (U.S. and/or Foreign). 8650. UNS G86500: ASTM A322. A5 19: SAE J-KM. J-l I?. J770.86508. UNS H86500: ASThl A304: SAE J I368

spheroidired structure. heat to 750 “C t 1380 “F), cool rapidly to 715 “C I 1320 “F). then cool to 650 ‘C t IX) “F). at a rate not to exceed 6 “C t IO “F) per h; or heat to 750 “C ( I380 “F). cool rapidly to 650 “C (I X0 “F). and hold for IO h

Hardening. Austenitize at 845 “C I 1555 “F). and quench in oil. Flame hardening. gas nitriding. ion nitriding. and carbonitriding are suitable processes Tempering.

After quenching. parts should be tempered immediately (preferahly ashen they are still ~iarrn to the touch) at IS0 “C (300 “F) or higher. For most purposes. higher tempering temperatures are used. Selection of temperins temperature is based on the desired combination of mechanical properties

Characteristics. Borderline between I$ hat is usually considered a medium-carbon grade and a high-carbon grade alloy steel. When the carbon is on the lower side of the allowable range. oil-quenched hardness of approxtmately 56 HRC can he expected. When the carbon content is near 0.5-L an as-quenched hardness of approximately 61 HRC can be expected. Hardenability is relatively high. Used extenskely for a variety of machiner) parts where high strength is required for rigorous service. notahly for highly stressed shafts and springs. Can be forged. although as is true for other higher carbon. high-hatdenability steels. forgings of complex shape should he cooled slo~+ly from the forging temperature to minimize the possibilit) of cracking

l

Forging.

l

Recommended l l l l l

Heat to 1130 “C (3%) “F) maximum. Do not forge after temperature of forging stock drops below approximately 925 “C t I695 “F J Cool slowly from the forging temperature

Recommended Normalizing. Annealing.

Heat Treating

Processing

Sequence

Forge Nomralire Anneal Rough and semifinish machine Austenitire and quench Temper Finish machine

8850:

Approximate

Critical

Points

Practice

Heat to 870 “C (I 600 “FL Cool in air

For a predominantly prarlitic structure. heat to 830 “C t IS25 OF), cool slowly to 7 IO “C ( I3 IO “F). then cool to 650 “C t I ZOO “F). at a rate not to exceed 8 “C t IS “F) per h: or heat to 830 “C ( IS35 OF). cool rapidly to 650 “C (IZOO “F), and hold for 8 h. For a predomjnantly

Temperature Critical As, Acq Ari Ar.

point

T

OF

730 770 700 655

1350 I420 I295 1210

476 / Heat Treaters

Guide

8650: Continuous Cooling Transformation Austenitized

Diagram. Composition:

0.48 C. 0.75 Mn, 0.020 P, 0.010 S. 0.34 Si. 0.60 Ni, 0.58 Cr, 0.20 MO.

at 850 “C (1560 “F)

8650: Hardness vs Tempering Temperature. Composition: 0.48 to 0.53 0.75 to 1.00 0.20 to 0.35 0.40 to 0.70 0.40 to 0.60 Cr, 0.15 to 0.25 MO. Forged at 1175 “C (2150 “F) maximum and annealed by furnace cooling from 815 to 925 “C (1500 to 1695 “F). Maximum annealed hardness, 212 HB. Normalized at 870 “C (1600 “F) with a hardness of 355 HB for test size. Quenched in oil at 845 “C (1555 “F) and tempered for 2 h. Source: Republic Steel

Alloy

8650H: Hardenability (1600 “F). Austenitize:

Hardness purposes I distance,

mm I.:’

Hardness purposes I distance. ‘!,,6 in.

Curves. Heat-treating 845 “C (1555 “F)

limits for specification Hardness,

Maximum

HRC Minimum 59 SY 98 56 sj 53 50 16 38 3-f 32 31 30 29 29

6.5 65 65 65 64 63 62 61 59 57 51 52 19 -17 46

limits for specification Hardness.

hlasimum h5 cl.5 65 b-l M h3 63 h2 61 60 60 59 58 58 47 Sb 5s 53 52 SO 19 37 .lb 45

HRC hlinimum 59 58 51 57 5h 51 53 SO -1-l 4-l -II 39 37 36 35 3-1 33 32 ?I 31 30 30 2’) 29

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

Steel / 477

only): 870 “C

478 / Heat Treaters

Guide

885OH: End-Quench Hardenability Distance from quenched surface !.‘16in. mm I 2 3 4 5 6 7 8 9 10 II

I..58 3 16 17-l 6.3’ 7.90 9.48 II 06 1264 11.12 IS 80 17.38

Hardness, HRC max min 65 65 6S 64 64 b3 63 62 61 60 60

99 58 57 57 56 S-l 53 so 47 4-I II

8650: Microstructure. Distance from quenched surface !/IS in. mm 13 I4 IS lb I8 20 ‘2 7-l ‘6 28

20.5-l x.1?. 23.70 25 28 ‘8 4-l 31.60 34.76 37.92 -I I .oa 44.2-l

Hardness, HRC max min 58 S8 57 56 5s 5.3 51 so 49 -17

37 36 3s 3-I 33 32 31 31 30 30

2% nital, 500x. Hot rolled steel bar, 7.936 mm (0.31 in.) hexagonal, austenitized at 750 “C (1380 “F) 3 h, furnace cooled to 665 “C (1230 “F) and held 6 h, air cooled, cold drawn, reheated to 665 “C (1230 “F) for 10 h, furnace cooled. Spheroidized cementite and lamellar peariite in ferrite

478 / Heat Treaters

Guide

8655,8655H Chemical Composition. 8655. AISI and UN% 0.5 I to 0.59 C. 0.75 to I .OO hln.0.035 Pmax. 0.03OS max. 0.15 too.30 Si. 0.10 too.70 Ni.O.-lO IO0.60Cr. 0.15to 0.35 hlo. UNSHS6550and SAE/AIS18655H:O.SOto 0.60C.0.70to 1.05 hln.0.15 to035 Si.O.35 too.75 Ni.O.lS 100.25 MO Similar

Steels (U.S. and/or

ASTM A322 AW;SAEJI268

A33l:

Foreign).

SAE J-IO-L J-II’.

8655.

5770. %%H.

G86sso: UNS UNS H86Y5050:A!ST&l

Characteristics.

A high-carbon sted. A spnnp sled. although it is used IO fabricate a variety of machinery parts not related to sprinps. .As-quenched hardness after quenching tn oil usually ranges from 57 to 62 HRC. depending on exact carbon content. A high-hardenability steel. although the hand is generally wide. Is forgeable. but not recommended for iteldinp because of its high carbon content rend high hardenability

Forging. Heat to 1200 “C (2190 “F) masimum. Do not forge after temperature of forging stock drops below approximately 925 “C ( 1695 ‘F). Forgings of this grade should he cooled slo\vly from the forging operntion. especially if they have complex shapes. Bury them in an insulating compound or place them in a furnace

Recommended Normalizing.

Heat Treating

Practice

Heat to 870 “C ( I600 “F). Cool in air

Annealing.

For a predominantly spheroidized structure. which is preferred for machining and heat treakng 86SSH. heat to 750 “C (I380 “F), cool rnpidly to 700 “C ( I290 “F). then cool to 655 “C (I 2 IO “F). at a rate not to exceed 6 “C t IO “F) per h: or heat IO 750 “C ( I380 “F), cool rapidly to 650 “C ( I200 “FJ. and hold for IO h

Direct Hardening. Flame hardening. able processes

.Austenitizs ttt 830 “C ( lS2S “F), and quench in oil. gas nitridinp. ion nitriding. and carbonitriding are suit-

Tempering.

After quenching to nelu ambient temperature. temper immediately at I SO “C (300 “F) or higher. The selection of tempering temperature depends on the required hardness or mechanical properties. 86SSH is sensitke to quench cracking. and 1001 steel practice should be obsemed in tempering. Parts should not be allowed to become too cold after quenching before they are placed in the tempering furnace. A uniform temperature of approximately 38 to SO “C t 100 to I20 “F) is preferred

Austempering.

\\‘hen used for applications such as heavy-duty springs. 865SH is sustempered in a procedure such as the one that follows:

Alloy

Auslenitize at 830 “C (1525 “F) Quench in an agitated molten salt hnth held at 315 “C (655 “F) . Hold at 345 “C (655 “F) for I h l Air cool to room temperature l \Vash in hot natrr

Recommended

l l

l l l l

No tempering is required. Hardness for pxts should range from approximarsl) 47 10 57 HRC

l l l

8855, 8655H:

Distance from quenched surface 916 in. mm 1 2 3 4 5 6 7 8 9 10

1.58 3.16 4.14 6.32 7.90 9.48 11.06 12.64 14.22 15.80

11 12

17.38 18.96

Hardenability

Hardness, HRC max min

Distance from quenched surface l/l6 in. mm

Hardness, HRC min max

65

60 59 59 58 57 56 55 54 52 49

13 14 15 16 18 20 22 24 26 28

20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24

64 63 63 62 61 60 59 58 57 56

41 40 39 38 31 35 34 34 33 33

65 64

46 43

30 32

47.40 50.56

55 53

32 32

I479

Sequence

Forge Normalize Anneal Rough md semifinish machine Austenitize and quench (or nuskmper) Temper (or austrmper) Finish machine CUSUAI~ grinding)

sents an average

8655H: End-Quench

Processing

Steel

Hardness based

vs Tempering

Temperature.

on a fully quenched

structure

Repre-

480 / Heat Treaters

Guide

8655H: Hardenability

Curves. Heat-treating 845 “C (1555 “F)

(1600 “F). Austenitize:

Hardness purposes J distance. mm

limits for specification Hardness, hladmum

HRC Minimum 60 60 59 57 56 55 53 51 42 39 3h 34 34 33 32

65 h5 6-l 62 60 58 56 5-l

Hardness purposes J distance. 1/1b io-

0 1 2 3 4 5 6 8 :0 !2 !4 :6 :s 80 12

limits for specification Hardness, hlatimum

65 65 64 64 63 63 62 61 60 59 58 57 56 55 53

HRC hfinimum 60 59 59 58 57 56 55 54 52 49 46 43 41 40 39 38 31 35 34 34 33 33 32 32

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

Alloy Steel / 481

8660,866OH Chemical

Composition. 8660. AISI: 0.55 to 0.65 C. 0.75 to 1.00 hln.0.0-10Pmax,0.0~OSmax.O.2Oto0.3SSi.O.10to0.70Ni.0.-10to0.60 Cr. 0. IS to 0.X MO. UNS: 0.55 to 0.65 C. 0.75 to I.00 hln. 0.035 P max. 0 040 S max. 0.15 to 0.30 Si. O.JO to 0.70 Ni. O.-IO to 0.60 Cr. 0. IS to 0.25 hlo. UNS HS6600 and SAE/AISI 86608: 0.55 LO0.65 C. 0.70 to I .OS Mn. 0. IS to 0.35 Si. 0.35 to 0.75 Ni. 0.35 to 0.65 Cr. 0. IS to 0.35 MO Similar

Steels (U.S. and/or Foreign).

ASThl A27-L A33Z. A333. ASl9: H86600: ASThl A3O-l: SAE J I?68

SAE J-W.

UNS ~86600; 8660. J-ll2.1770. 86608. GINS

Characteristics. A spring stssl used for a uide \ariety of machinsq parts where high strength and high h,ardcnabilit) are important. Also used for a variet) of metal working tools including cold \\orl; dies. When the carbon is on the IOU side of the allo~~ablz range. the as-quenched hardness for an oil-quenched part ma) hz no higher than about 59 HRC. but when the carbon approaches the upper limit. the as-quenched hardnesb can he as high as 65 HRC. The hardenahilit) hand is relativeI! wide. hut the hardenahility can he \eq high. actually approaching that of an au-hardening Steel Forging. Heat to 1200 ‘C rZl9O “FI ma\irnum. Do not forge atier temperature of forging stock drops belo\{ approsimatelj 925 YI ( 169.i “F). Forgings of this grade should be cooled slou I! from the forging operation. especially if they have complex ,hapcs. Buq them in an insulatmg compound or place them in a furnace

Tempering.

.After quenching to near ambient temperature, temper immediateI> al I SO “C 1300 “F) or higher. The selection oftempering temperature depends on the required hardness or mechanical properties. 866OH is sensiti\c to quench cracking. and tool steel practice should be observed in tempertng. Parts should not be allowed to become too cold after quenching before they are placed in the tempering furnace. A uniform temperature of approximateI> 38 to SO ‘C t IO0 to I20 “F) is preferred

Austempering.

H’hen used for applications such as heavy-duty sprmgs. 86SSH is austempered in a procedure such as the one that follows: l l l l l

No trmpenng 47 to 52 HRC

l l l l

l

Normalizing.

Heat Treating

Practice

15

requued. Hardness for parts should range from approximately

Recommended

l

Recommended

Austenitize at 830 “C t IS25 “FI Quench in an agitated molten salt bath held at 3-lS “C (655 “F) Hold at 3-0 “C 1655 “F) for I h Air cool lo room temperature L\‘abh in hot \bater

l

Processing

Sequence

Forge Normalize .Anneal Rough and semifinibh ~nnchins jrulrtsnitize and quench (or austsmper) Temper Ior austempcr) Finish machine ~usuallg grinding)

Heat to 870 ‘C t I600 “F). Cool in air

Annealing.

For a przdormnantly spheroidized structure. uhich is usually preferred for machining as well as heat treating. heat to 7S0 “C t 1380 “FJ. cool rapidI> to 700 “C ( I?90 ‘F). then cool to 6SS “C ( I2 IO “Ft. at a rate not to esceed 6 “C ( IO “F) per h: or heat to 750 ‘C I I380 “F). cool rapidly to 650 “C I I200 “F). and hold for IO h

8660:

Approximate

Critical

Points Temperature

Critical point

Direct Hardening. Flame hardening.

Austenitire at 830 “C I IS2 “FL and quench in oil. gas nitriding. and ion nitridinp. are altematite procebses

8660: Isothermal

Transformation

C. 0.89 Mn, 0.53 Ni. 0.64 (1555 “F). Gram size: 8

Cr, 0.22

Diagram.

Composition: 0.59 MO. Austenitized at 845 “C

482 / Heat Treaters

Guide

8660: Hardness vs Tempering Temperature. Composition: 0.55 to 0.65 C, 0.75 to 1.00 Mn, 0.20 to 0.35 Si, 0.40 to 0.70 Ni, 0.40 to 0.60 Cr, 0.15 to 0.25 MO. Forge at 1175 “C (2150 “F), anneal from 815 to 925 “C (1500 to 1695 “F) for a maximum hardness of 229 HB. Hardness after normalizing in test size, 321 HB. Normalized at 870 “C (1600 “F), quenched in oil from 845 “C (1555 “F), tempered 2 h. Source: Republic Steel

8660: End-Quench

Hardenability. Composition: 0.59 C, 0.89 Mn, 0.53 Ni, 0.64 Cr, 0.22 MO. Austenitized at 845 “C (1555 “F). Grain size 8

8660H: End-Quench Hardenability Distance from quenched surface I.,16in. mm I 3 ;

Hardness. HRC min max

158

60 60 60

1.71 3.16 6 32 7.90 9.48

.:: .:’

II.06 12.6-l 11.22 IS.80 I7 38 I896

:” .:

Distance from quenched surface

“16h. I? I-l

mm

Hardness, HRC max min

X~..i-l 22.12 73 70

:

45 4-l -I!

60 60 59

3.28 28.U 31.641

6i 6-l 6-I

42 40 39

58 57

34.76 37.92

63 62

38 37

5s 53 50 47

1 I .08 1-1.2-t 47.40 50.56

62 61 60 60

36 36 36 3s

Alloy Steel / 483

8860H: Hardenability Curves. Heat-treating (1600 “F). Austenitize:

iardness wrposes distance, om

845 “C (1555 “F)

limits for specification Hardness, HRC Maximum hliuimum

.5

1 3 5 .O :5 ‘0 ‘5 0 .5 10

iardness wrposes distance, $6 in.

.

. 65 64 62 61 60

limits for specification Hardness, HRC Maximum hlinimum

.

0

1 2 3 4 5 6 8 0 2 4 6 8 0 2

60 60 60 60 59 58 56 53 46 42 39 38 37 36 35

. 65 64 64 63 62 62 61 60 60

60 60 60 60 60 59 58 57 55 53 50 41 45 44 43 42 40 39 38 37 36 36 35 35

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

1

484 / Heat Treaters Guide

8720,8720H,

8720RH

Chemical Composition. 8720. AISI and UNS: 0.18 to 0.23 C, 0.70 to0.90Mn,0.035 Pmax,0.040Smax,0.15 to0.30Si,0.40to0.70Ni,0.40 to 0.60 Cr. 0.20 to 0.30 MO. UNS II87200 and SAE/AISI 8720H: 0.17 to 0.23 C, 0.60 to 0.95 Mn, 0.15 to 0.35 Si, 0.35 to 0.75 Ni, 0.35 to 0.65 Cr, 0.20to0.30Mo.8720RH:0.18to0.23C,0.70to0.90Mn,0.15to0.35Si, 0.40 to 0.70 Ni, 0.40 to 0.60 Cr. 0.20 to 0.30 MO Similar Steels (U.S. and/or Foreign). 8720.

UNS G87200; ASTM A322; SAE J404,5770; (Ger.) DIN 1.6543; (U.K.) B.S. 805 A 20. 8720I-I. UNS H87200; ASTM A304, A914; SAE J1268, J 1868; (Ger.) DIN 1.6543: (U.K.) B.S. 805 A 20

Characteristics.

With the exception of a minor increase in the molybdenum content (0.20 to 0.30% as opposed to 0.15 to 0.25%), the composition of 8720H is identical with that of 8620H, and the characteristics are nearly identical. The only difference is that the hardenability of 87208 is slightly higher. Used for carburizing and carbonitriding where just a bit more hardenability is needed than can be provided by 82608. Has excellent forgeability and is readily weldable, although alloy steel practice should be used in welding to minimize susceptibility to weld cracking. Machinability is fairly good

Forging. Heat to 1245 “C (2275 OF) maximum. Do not forge after

(1220 OF), and holding for 4 h; or heat to 790 “C (1450 “F), cool rapidly to 660 “C (1220 “F), and hold for 8 h

Tempering. Temper all carburized or carbonitrided parts at 150 “C (300 “F), and virtually no loss of case hardness results. If some decrease in hardness can be tolerated, toughness can be increased by tempering at somewhat higher temperatures, up to 260 “C (500 “F)

Case Hardening. See recommended carburizing and carbonitriding procedures described for 86208. Ion nitriding and martempering are alternative processes. Quenchants include polymers Recommended l l l l l

l l

Processing

Sequence

Forge Normalize Anneal (if required) Rough machine Semifinish machine allowing only grinding stock, no more than 10% of the case depth per side for carburized parts. In most instances, carbonitrided parts are completely finished in this step Carburize or carbonitride and quench Temper

temperature of forging stock drops below approximately 900 “C (1650 OF)

Recommended Heat Treating Practice Normalizing. Heat to 925 “C (1695 OF). Cool in air Annealing. Structures having best machinability are developed by normalizing; or by heating to 885 “C (1625 “F), cooling rapidly to 660 “C

8720, 8720H: Hardness vs Tempering Temperature. sents an average based on a fully quenched structure

8720H: End-Quench

Repre-

Hardenability

~

I 2 3 4 ; 7 8 9 IO II 12

I.58 3.16 4.7-l 6.32 7.90 9.1x I I ah 12.6-I 14.22 IS.80 17.38 IX.96

-18 -17 4s 12 28 35 33 !I 30 29 2x 27

-II 38 3s 30 ‘6 2-l 2’ 21 20

13 II I5 I6 18 20 22 21 26 2!3 30 32

10.5-l 22. I2 23.70 25.28 25-L-l 31.60 34.76 37.92 -I I .08 u.2-l 17.40 SO.56

26 26 3 ‘5 2-l 21 73 23 23 23 1’ 22

8720: Tempering Temperature vs Case Hardness. Carburized to a depth of 1.27 mm (0.050 in.). Rock bit journals 13 mm (0.50 in.) to 44.5 mm (1.75 in.) in cross section were carburized at 925 “C (1695 “F), air cooled from 845 “C (1555 “F), heated to 870 “C (1600 “F), oil quenched, tempered at 650 “C (1200 “F), reheated to 775 “C (1425 “F), oil quenched. and tempered at indicated temperatures

Alloy Steel / 485 8720H: Hardenability Curves. Heat-treating temperatures (1700 “F). Austenitize:

925 “C (1700 “F)

Hardness limits for specification purposes J distance. mm

Aardness. Maximum

4x -I7 45 II 37 33 31 29 ‘7 25 2-l 23 23 23 22

HRC hlinimum

-II 39 35 29 25 22 21

Hardness limits for specification purposes J distance, 1.‘16 in.

I ? 3 -I s 6 7 8 9 IO II IZ I3 IJ IS

I6 18 ‘0 ‘2 21 26 28 3CJ 32

Hardness, hlavimum

HRC hlinimum

recommended

by SAE. Normalize (for forged or rolled specimens

only): 925 “C

488 / Heat Treaters

Guide

8720RH: Hardenability “C (1700 “F). Austenitize:

Hardness purposes J distance, 1, 4i”. I 7 ; -I 5

6 7 8 9 I0 II I:! I3 I-l IS I6 IX

20 22

Hardness. hlaximum

HRC hlinimum

47 -2.5 13 .I0 36 33

-I2 39 37 32 28 26 2-l 23 72

31

29 28 27 26 2s 2s 2-l 2-l 23 23 22 22

2-l

21

20

J distance, mm

925 “C (1700 “F)

limits for specification

26 2x 30 32

Hardness purposes

Curves. Heat-treating

21

20

limits for specification Hardness, Maximum

HRC Minimum

temperatures

recommended

by SAE. Normalize

(for forged or rolled specimens

only): 925

Alloy Steel / 487

8720: Microstructures. Note: All microstructures for 8720 were hot rolled specimens treated uniformly before described heat treatments: gas carburized for 9 h at 925 “C (1695 “F) at 1.35% carbon potential and diffused for 2 h at the same temperature at 0.90% carbon potential. The center of the field in the micrographs ranges from 0.127 to 0.254 mm (0.005 to 0.010 in.) beneath the carburized surface. (a) 5% nital, 1000x. Slowly cooled in the furnace from the carburizing temperature. Light carbide network in a matrix of lamellar pearfite. (b) 5% nital, 1000x. Austenitized at 0.90% carbon potential for 1 h at 815 “C (1500 “F), oil quenched, tempered for 1 h at 190 “C (375 “F). Relatively lowcarbon tempered martensite. (c) 5% nital, 1000x. Same austenitizing and tempering treatments as (b). Globular carbide, retained austenite in tempered martensite of highercarbon content than (b). (d)5?” nital. 1000x. Austenitized at 0.65% carbon potential for 1 h at 815 “C (1500 “F), oil quenched. tempered for 1 h at 190 “C (375 “F). Retained austenite (white constituent) in a matrix of tempered martensite. (e) 5% nital, 1000x. Austenitized at 1.35% carbon potential for 1 h at 815 “C (1500 “F), oil quenched, tempered 1 h at 190 “C (375 “F). Carbide (light network, globular particles) in a matrix of tempered martensite. retained austenite not visible. (f) 5% nital, 1000x. Austenitized at 0.90% carbon potential for 1 h at 815 “C (1500 “F), quenched in oil, tempered for 1 h at 260 “C (500 “F). Small amount of retained austenite (white areas) visible in a matrix of over-tempered martensite. (g) 5% nital, 1000x. Austenitized at 0.90% carbon potential for 1 h at 815 “C (1500 “F), quenched in oil, tempered for 1 hat 120 “C (250 “F). Tempered martensite. showing effects of undertempering. (h) 5% nital, 1000x. Austenitized at 0.90% carbon potential for 1 h at 815 “C (1500 “F), rapidly air cooled, tempered for 1 h at 190 “C (375 “F). Fine pearlite (dark constituent) in a matrix of bainite. (j) 5% nital, 1000x. Same as (h), except oil quenched. Surface was improperly ground, being heated above the critical temperature and then rapidly cooled. Retained austenite (white) and untempered martensite result

L

(b)

Alloy Steel / 487

8740,874OH Chemical

Composition.

to l.OOMn.0.035

Pmax.O.WOS

8740. AISI and UNS: 0.38 to 0.43 C. 0.7s max.0.15 ~o0.30Si.0.40to0.70Ni.0.40

to0.60 Cr. 0.30to0.30 Mo. UNSH87JOO and SAE/AISI874OH:0.3710 0.14 C. 0.70 to I.05 hln. 0.15 to 0.35 Si. 0.3.5 to 0.75 Ni. 0.35 to O.hS Cr. 0.30 10 0.30 MO

Similar Steels (U.S. and/or Foreign). 8740. UNS G87400; AhlS 6332. 6313. 633. 6327. 6358: ASThl A313. A331: ML SPEC MIL-S6019; SAE J-W. J-II?. 5770: tGsr., DIN 1.6546: (I~al.) UNI 10 NiCrhlo 2 KB;(U.K.b B S.T!,pr7.874OH. 1lNS HX7100: ASTMA3M:SAEJl168: (Grr.) DIN 1.6546: (Ital.1 LlNl 10 NiCrhlo 2 KB: (U.K.) B.S. Type 7

488 / Heat Treaters

Guide

NearI) identical in composition to 8640H. The onl) Characteristics. difference is a sli_rhtl> higher molybdenum range. 0.20 to 0.303 for 8710H as opposed to 0. IS IO 0.2‘-5 for 8640H. This minor difference does not change the as-quenched hardness. but does offer a light increase In bardrnahilib. If desired. can he nitrided to achis\r surfaces Ihal help 10 resist abrasion and further Increase fatigue strenpth. An ns-quenched surface hardness of approsimatel) 52 IO S7 HRC can he expected. depending on the precise carbon content. Can he forged h! an> one of the wious forging method\

Nitriding. Responds nell to ammoniagas nitridins as well as II) nitriding in any one of several proprietary molten sah baths. The following is a cycle used with ammonia &as mtriding: l

l

l

Forging. wmperature

Heat 10 1230 ‘C t22SO “F) maximum. Do not forge after of iorging stock drops hslou appronnnatel~ 900 ‘xY ( l6SO “F)

Parts are austenitirsd. quenched, and tempered al 540 “C (I000 “F) or higher. (Tempering temperature must aLays he higher [ban the &riding temperarure) Finish machine (must he done hefore nitriding. because of resulting thin case 1 Nilrids In ammonia gas for IO to I? h I\ ith an ammonia gas dissociation of 2s to 305

See procrssmg data for 1 I-LOH for other nilriding

Recommended Normalizing.

Heat Treating

Practice

Tempering.

.Aftcr quenching. reheat immediately to the tempering temperature that M ill provide the desired combination of mecharucal properties

Heal to 870 ‘C ( I600 “FJ. Cool in air.

In aerospace pracke.

parts are normalized

at 900 “C ( 1650 “F)

Annealing.

For a predominanU> penrlitic wuuc‘rure. heat to 830 ‘C ( IS3 “FL cool rapidly to 73 ‘C ( I335 “FL then cool to 640 ‘C ( I I85 “‘F), a~ a ra[e not IO exceed I I “C (10 “F) per h: or heat to X30 “C ( IS3 ‘F). ~‘001 rapidly to 665 “C ( I230 “F). and hold for 6 h. For a pr?dominantl> sphrroidized wucture. heat to 750 “C I 1380 “F). cool rapid11 to 73 “C I I335 “FL then cool to 640 “C ( I I85 “FL at a rate nor to exceed 6 “C ( IO “FB per h; or heat to 750 YI ( 13X0 ‘FJ. cool rapid11 to 665 “C ( 1230 “FJ. and hold for 8 h In aerospace practice. parts are annealed at 845 “C I ISSS “F). cooled IO helo\\ S-IO “C ( 1000 “F) at a rate not IO exceed 95 “‘C 1200 “F) per h

Other Processes. Ion nitriding. austempering and martempering are altemath e processes. In aerospace practice. parts WC austenitized at 8-15 “C I IS55 “F). then quenched in oil or polymers

Recommended l l l l l l l

Hardening.

Direct

.Austenirizs

at XSS :‘C (’ IS70 “FL and quench in oil

l

Processing

Specimens

quenched

Hardness

in.

mm

Surface

on Hardness Hardness, HB Size round

in oil

Size round

Sequence

Forge Normalize .Annsal Rouph and semifinish machine Austsnitize and quench Temper Finish machine (grind if required) Nitride (optional)

8740: Effect of Heat Treating 8740: As-Quenched

cycles

Hardness, HRC ‘A_ radius

Condition

‘iin. (13mm)

1 in. (2.5 mm)

2ill. (51 mm)

4in. (102 mm)

201 169 352 302 285

261 331 ‘71 25.5

755 277 X8 ‘29

Center r\nnrakdiar Nomlalircd~ b) 011 qusnchrdli, Oil quenchrdld,

311

011qucnshedlr)

3s

‘69

352

(al Haled m IWO “F 11115‘CL furnace cwlcd 20 ‘IF f I I “C) to I IO0 “F (595 “C). cooled intir. lb) Healed to IhOO“Ft870 “CL cooled in air. (cl Fmm IS15 “F(830”C). lemprrzd II 1001)“F (5-10 ‘Cl. Id) From I525 “F (8.10 “CJ. tempered at I IO0 “F (59.5 ‘CL 151From IS3 “Ft830’C~. temperedat INJ”FI~SO”C). Source: RepublicSteel

8740, 8740H: sents an average

Hardness vs Tempering Temperature. Reprebased

on a fully quenched

structure

Alloy Steel / 489

3740H: Hardenability Curves. Heat-treating :1600 “F). Austenitize:

lardness lurposes distance, ,m .5

1 3 5 0 5 0 5 0 5 0

iardness wrposes distance, ‘16in.

845 “C (1555 “F)

limits for specification Hardness, HRC Minimum Maximum

60 60 60 60 59 58 56 54 50 45 43 41 40 39 38

limits for specification Hardness, HRC Maximum Minimum

60 60 60

0 1 2 3 4 5 6 8 0 2 4 6 8 0 2

53 52 51 49 46 43 39 36 31 29 28 27 27 26 26

60 59 58 57 56 55 53 52 50 49 48 46 45 43 42 41 40 39 39 38 38

53 53 52 51 49 46 43 40 31 35 34 32 31 31 30 29 28 28 21 21 27 27 26 26

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 870 “C

1

490 / Heat Treaters Guide 8740: Suggested Tempering Temperatures (Aerospace Practice)* 620460 MPa (90-125 bi)

860-1035 hlPa (125-150 ksi)

690 “C I I275 “FJ

635 ‘T 11175°F)

Tensile Strength Range 1175-1210 MPa 1035-1175 hlPa (170480 ksi) (150-17Oksi)

1240-1380 hlPa (180-200 ksi)

1380-1520 MPa (200-220 ksi)

455 “C (850°F)

385 “C (735 “FJ

925 “C (975 “F)

580 “C (1075 “FJ

* Quench m oil or poljmrr. Source: AhlS 27S9/1

8740:

Suggested Tempering Temperatures Based on As-Quenched Hardness (Aerospace Practice)

Tensile strength range

RC 47-19

RC 50-52

RC 53-55

RC -56-58

620 - IO35 MPa (90-1.50 ksi) 965-l 105 MPa (140-160 ksl) 1035-l 175 MPa (ISO-17Oksij I I OS-I230 MPa (160-180 ksl) 1175.1310MPa (170-190 ksl) 1210-1380 MPa (180-200 ksi) 1380-1515 MPa (200-220 kji)

595 “C (IIOO”FI 525 “C 197.5“FI 470 “C 187S’F)

620 ‘T (1150°F) 550 “C (IO2S “F, 510°C (950 “F) 480 “C (900 “F) 4lO”C (775 ‘F) 385 “C (725 OF)

(650 ‘T) I 1200°F) 595 “C (IIOO”FI 550 “C (IO15 “R 52s “C (975 “F) 470 “C (R75 “F) -130 @C (825 OF) 110 T (775 “F)

675 “C ( 1250 “F) 635 “C (1175°F) 595 “C (1100°F~ 565 “C (lOSO”F) 510°C (950 “F) 500 “C (925 “F) 470 “C (875 OF)

Source: AhlS 2759/l

490 / Heat Treaters

8822,8822H,

Guide

8822RH

Chemical Composition. 8822. AISI and UNS: 0.20 to 0.25 C. 0.75 to I .OO Mn.0.035 Pmas. 0.040 S max. 0. IS toO.3OSi. 0.40 too.70 Ni.O.40 to 0.60 Cr. 0.30 to 0.10 hlo. LJNS 888220 and SAE/AISI 88228: 0. I9 to 0.15 C. 0.70 to 1.05 Mn. 0.1s to 0.35 Si. 0.35 to 0.75 Ni. 0.35 to 0.65 Cr. 0.30 to 0.40 MO. SAE 8822RH: 0.20 to 0.25 C. 0.75 to I.00 Mn. 0.15 to 0.35 Si. 0.40 to 0.70 Ni, 0.40 to 0.60 Cr. 0.30 to 0.40 hlo Similar Steels (U.S. and/or Foreign). 8822. UNS G88220; SAE J-W. J770: (Ger.) DlN I .6543: (U.K.) B.S. XOS A 20.8822H. IJNS H8822O: ASThl A304 SAE 5407; t&r.) D[N 1.6543; iL1.K.) B.S. 805 A 20 Characteristics. A modification of 862OH. with a higher carbon range (same as 8632H) and a substantialI> higher mol!hdenum content to.30 to O.-W? as opposed to 0. IS to O.YG for 8620 and 8622H). This increase in molybdenum content results in a significant increase in hardenabilit). As-quenched hardness usuallq ranges from approximateI> -II to 47 HRC. Can be processed by carbonitriding. but usualI> is not used for producing parts that will be carbonitrided because most carbonitrided pans are relatively, small, and the higher hardenabilitj of 8822H is not required. Used princtpall) for producing parts L+ith heavy sections for which grades 8620H and 8622H do not have sufficient hardenability. such as heavy-duty gears and pinions. Such parts are subjected to carburiring treatments. Forges easil). and forging is often used to produce gear blanks and similar parts. Is readily heldable. although alloy steel practice should be used in welding to minimize susceptibility to weld cracking. Machinability is considered fairly good Forging. temperature

Heat to 1245 “C (2275 ‘F, maximum. Do not forge after of forging stock drops beIoN approximately 900 “C t IhSO “F)

Recommended Normalizing.

Heat Treating

Practice

Heat to 925 “C ( 16% “F). Cool in air

Annealing.

Structures ha\ ing best machinability are developed by normalizing: or by heating to 885 “C (I625 “F). cooling rapidly to 665 “C t I230 “F). and holding for -I h: or heat to 790 “C (l-i55 “F). cool rapidly to 665 “C t I230 “F). and hold for 8 h

Tempering.

Parts made from 50B14H should be tempered immediately after the) ha\ e been uniformI) quenched to near ambient temperature. Best practice is to place workpieces into the tempering furnace just before they ha\ e reached room temperature. ideall) u hen they are in the range of 38 to SO “C t 100 to 170 “F). Tempering temperature must be selected based upon the tinal desired hardness. After quenching to near ambient temperature. temper immediately at I SO “C (300 “F) or higher. The selection of tempering temperature depends on the required hardness or mechanical properties. 86SSH is sensitive to quench cracking. and tool steel practice should be observed In tempering. Parts should not be alloued to become too cold after quenching before they are placed in the tempering furnace. A uniform temperature of approximately 38 to SO “C ( 100 to I20 “F) is preferred. Temper all carburized or carbonitrided parts at IS0 “C (300 “F). and virtually no loss of case hardness results. If some decrease in hardness can be tolerated, toughness can be increased by tempering at somewhat higher temperatures; such as up to 7-60 “C (SO0 “F)

Case Hardening. scribed for 862OH

See carburizing

and carbonitriding

practices

de-

Alloy Steel / 491

Recommended l l l l l

Processing

Sequence

l

Forge Normalize Anneal (if required) Rough machine Semifinish machine allowing only grinding stoch. no more than IO? of the case depth per side for carburized parts. In most instances, carbonilrided parts are completely tinished in this skp

8822:

Approximate

Critical

point

OF

As, XCJ Ar, Ar, Sour~c: Republic

Carburize or carhonitride and quench Temper

8822:

Approximate

Core Hardness

Normalized at 1700 “F (925 “C) in 1.25-in. (31.8-mm) rounds; machined to 1-in. (25mm) or 0.540-in. (13.7-mm) rounds; pseudocarburized at 1700 “F (925 “C) for 8 h; box cooled to room temperature, reheated and oil quenched: tempered at 300 “F (150 “C); tested 0.505-in. (12.8-mm) rounds

Points Temperature

Critical

l

1330 I510 IUS II95 Steel

Reheat temperature “F T 1-m 1510 I590 17ool(1l ca)Qurnched

775 820 865 9251a1

Hardness, HB Heat treated in rounds 1 in. 0.540 in. (25 mm) (13.7 mm) 352 363 38X 388

from 17lXYF (925 ,;C, oficr psrudocmburiring

3s2 415 429 429 for8 h

8822, 8822H: Hardness vs Tempering Temperature. sents an average based on a fully quenched structure

8822: Cooling

Curve. Half cooling time. Source: Datasheet

l-60. Climax Molybdenum

Company

Repre-

492 / Heat Treaters

Guide

8822H: End-Quench Hardenability Distance from quenched surface ‘.~bin. mm

Hardness. HRC ma\ min

Distance from quenched surface I ‘16in. mm

Rardness. HRC may min

I 1

I su

so

13

13

20.5-l

31

;

4.74 3 16 6 32 7.90 9.-M

49 -18 -lb -13 40 37

42 39

IS I-l I6 18 70 ‘2

3s

2-l

2-l

23.70 22 I?. 3.28 28.44 3 I 60 34.76 37.92

30 30

33 29 27 75

4 5 h 7 x 9

I I.06 I’.hl

19 3 28

‘7 27

l-l.12

3-l

7-l

3

11.08

l5YO

33

23

28

U.‘-l

27

II

17.38

32

23

I2

IS96

31

22

30 32

47.m 50.56

27 27

IO

27

8822: CCT Diagram. Composition for AISI, constructional

alloy steel: 0.24 C, 0.95 Mn, 0.28 Si, 0.019 P, 0.025 S. 0.44 Ni, 0.31 MO. Steel was from commercial heat, and was austenitized at 850 “C (1560 “F) for 12 min. Determining heavy section hardenability was objective of study. Source: Datasheet I-60. Climax Molydbenum Company

Alloy

8822H: Hardenability

Curves. Heat-treating

(1700 OF). Austenitize:

925 “C (1700 “F)

Hardness wrposes I distance, nm I.5

limits for specification Eardness. Maximum

ERC hlinimum

SO 19 17 -IS II 38 3s 33 31 29 29 28 ‘7 17 27

Hardness limits for specification wrposes I distance, k,6i”.

3 I0 II IZ I3 I-l 15 I6 I8 !O 12 t-1 !6 !8 NJ

Hardness, hlauimum 50 49 -a 46 13 40 37 3s 31 33 31 31 31 30 30 29 29 23 27 27 17 27 27 27

HRC hlinimum

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

Steel / 493

only): 925 “C

1

494 / Heat Treaters

Guide

8822RH: Hardenability “C (1700 “F). Austenitize:

Hardness purposes J distance,

‘46io.

Curves. Heat-treating 925 “C (1700 “F)

limits for specification Hardness. Maximum

RRC Minimum

I

-19

-I4

4

I3

13 -IO 37 35 33 32 31 30 30 '9

I-1

28

IS 16 IX

28 27 27

35 31 29 27 26 2.5 2s 2-l ‘3 23 '3 22 22

20

26

22 2-l 26 28 30 32

26 26 26 25 25 25

5 h 7 8 9 I0 II

I2

Hardness purposes J distunce. mm

21

20

limits for specification Hardness, Maximum

HRC Minimum

I .5

49

4-l

3

5 7 9

18 -16 12 38

II

3.5

I3

33 32 29 27 27 26 36 L-5 ‘5

-I3 39 33 30 27 26 2s 23 22

IS

20 25 30 35

40 4s so

71

20

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 925

Alloy Steel / 495

9260,926OH Chemical

Composition. 9260. MS1 and UNS: 0.56 to (X6-1C. 0.75 to I.00 Mn. 0.035 P max. 0.040 S max. I.80 to 2.30 Si. UNS H92600 and SAE/AISI926OH: 03.5 to 0.65 C.O.65 to 1.10 hln. 1.70 to 2.20 Si Similar

Steels (U.S. and/or Foreign). 9260. UNS G9?600: ASTM AZ9. AS9. AX?. A33 I ; SAE J-404, J4l2.5770: (Ger.) DfN I .0909: (Fr.) AFNOR 60 S 7,6l SC 7; (U.K.) B.S. 250 AS8.92608. UNS H92600: ASThl A304 SAE Jl268; (Ger.) DIN 1.0909; (Fr.) AFNOR 60s 7.61 SC 7: (U.K.) B.S. 30 A 58 Characteristics.

A special composition the only steel in the present AISI list where the silicon content il.7 to 2.2%) is high enough to he considered an alloy. Principal use is for heavy-duty springs. notably coil springs that are hot wound. Is nearly identtcal in composition to S-t. shock-resisting tool steel. 9160H is used for tooling as ~rell as nontooling applications. such as coining dies. L\ here impact resistance is important. As-quenched hardness can be expected to fall within the range of approximately 58 to 63 HRC. Hardenahility is considered fairly high

Forging. temperature

Annealing.

For a predominantly spheroidized structure (usually preferred). heat to 760 “C ( 1400 “F). then cool to 705 “C ( I300 “F). 31 a rate not to exceed 6 ‘C (IO “F) per h; or heat to 760 “C ( 1100 “F). cool rapidly to 665 “C ( I30 “F). and hold for IO h

Direct Hardening. hlartemperinp

Tempering.

After parts have been unifomtiy quenched to near ambient temperature. they should be placed in a tempering furnace immediately, preferably when their temperature is within the range of 38 to 50 “C (100 to I70 “F). The tempertng tempernture must be at least IS0 “C (300 “F). Higher tempering temperatures are usually used to develop maximum toughness in this steel

Recommended l l

Heat to 1205 “C (X00 “F) maximum. Do not forge after of forging stock drops below approximately 93 ‘C (I695 “F)

Normalizing.

l l

Practice

l

Heat to 900 “C ( 1650 “F). Cool in air

l

Recommended

Heat Treating

Austenitize at 870 “C ( 1600 “F). and quench in oil. is an nltemati\e process. Quenchants Include polymers

l

Processing

Sequence

Forge. or hot wind if producing springs Normalize Anneal Rough and semifinish machine (if applicable) .Austenitire and quench Temper Finish machine

9260: Isothermal Transformation

Diagram. Composition:

C. 0.82 Mn, 2.01 Si. 0.07 Cr. Austenitized Grain size: 6 to 7

at 870 “C (1600

0.62 “F).

496 / Heat Treaters

Guide

9260: Hardness vs Tempering Temperature. Composition: 0.55 to 0.65 C, 0.70 to 1 .OOMn. 1.80 to 2.20 Si. Forged at 1205 “C (2200 “F) maximum, furnace cooled from 815 to 925 “C (1500 to 1695 “F). Maximum annealed hardness, 229 HB. Hardness when normalized in test size, 302 HB. Normalized at 900 “C (1650 “F), quenched in oil from 870 “C (1600 “F), tempered for 2 h. Source: Republic Steel

9260H: End-Quench Hardenability Dktance from quenched surface ‘&in. mm 1 2 3 4 5 6

1.58 3.16 4.74 6.32 7.90 9.48

7 8 9 10 11 12

Hardness, HRC mas min

Distance from quenched surface &in. mm

Hardness, HRC may min

65 64 63 62

60 60 57 53 46 41

13 14 15 16 18 20

20.54 22.12 23.70 25.28 28.44 31.60

4.5 43 42 40 38 37

33 33 32 32 31 31

11.06 12.64 14.22

60 58 55

38 36 36

22 24 26

34.76 37.92 41.08

36 36 35

30 30 29

15.80 17.38 18.96

52 49 47

35 34 34

28 30 32

44.24 47.40 50.56

35 35 34

29 28 28

9260: End-Quench

Hardenability.

Mn, 2.01 Si. 0.07 Cr. Austenitized 6to7

Composition: 0.62 C, 0.82 at 870 “C (1600 “F). Grain size:

Alloy Steel / 497

9260H: Hardenability

Curves. Heat-treating

(1650 “F). Austenitize:

870 “C (1600 “F)

iardness wrposes I dbtancc. nm

limits for specification Hardness, Maximum

HRC Minimum

.:,

60 60 SY SO 42 38 36 35 33 32 31 30 29 28 28

6.5 63 62 60 5x 54 47 40 38 37 36 3.i 35

iardness wrposes I distance. 46 in.

0 I 2 3 4 5 6 8 :o 12 !4 I6 8 IO I2

limits for specification Hardness, Maximum

65 64 63 62 60 X3 5s 52 49 47 45 43 42 40 38 37 36 36 35 35 3s 34

HRC lllinimum 60 60 57 53 46 41 38 36 36 35 31 3-1 33 33 32 32 31 31 30 30 29 29 28 2x

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 900 “C

498 / Heat Treaters

9260: CCT Diagram. method)

Guide

Composition:

0.57 C, 0.91 Mn, 1.95 Si. Grain size: 7. Austenitized

at 870 “C (1600 “F) (using interrupted

Jominy

498 / Heat Treaters Guide

931 OH, 931 ORH Chemical

COf’IIpOSitiOn.

UNS H93100 and SAE/AISI 9310H: 0.07

to013 C. 0.40 to0.70 Mn.0.15 to030 Si. 2.95 to 3.55 Ni. 1.00 to I.-IS Cr. 0.08 to 0. IS hlo. SAE 9310RH: 0.08 to 0. I3 C. 0.45 to 0.65 hln. 0. IS to 0.35 Si. 3.00 to 3.50 Ni. I .OO to I .-IO Cr. 0.08 to 0.15 MO

Similar Steels (U.S. and/or Foreign).

UNS

G93 100:

ASTM

.A3(H: SAE Jl26X

Characteristics. A relati\elq high-allo!. high-qualit). and high-hardenability case hardening steel. Uwally carburired. Because of its relatimely low carbon content, as-quenched hardness is not usually higher than approximately 32 to 38 HRC. depending on whether the carbon is near the lo\\ side or the high side of the allowable range. Hardenabilit~. ho\bever. is high. Used for such applications as premium quality gears. such as aircraft engines and pinions for which high hardenability and an unusualI) high degree of toughness are mandator). Relatively expensive and has a high nickel content. b hich can be a scarce allo>. The use of 93 IOH has gradualI) dsclined in favor of higher carbon. lower allo) grades of carburizing steels. Can be case hardened by carbonitriding. but economics usually exclude the use of 93 IOH for parts that would require carbonitriding

Annealing.

Because of the sluggish transformation characteristics of this steel. con\ entional annealing is not usually practical. A better means of obtaining a spheroidized structure in 93 IOH is bj tempering for approximately I8 h at a subcritical temperature. usually 600 “C ( I I IO “F)

Tempering.

Temper all carburizrd parts at IS0 “C (300 “FL and virtualI> no loss of case hardness results. If some decrease in hardness can be tolerated. toughness can be increased b) tempering at somewhat higher temperatures. up to 260 ‘C (SO0 “F)

Case Hardening. uum carburizing. able processes

Recommended l l l

Forging.

Heat to 1260 “C (2300 “F) maximum. Do not forge after temperature of forging stock drops below approximateI) 925 “C (16% ‘Fr

Recommended Heat Treating Practice Normalizing. Heat to 92s “C ( I695 “FL Cool in air

l l

l l

See carburizing practice described for 8620H. Vacion nitriding. austempenng. and martempering are suit-

Processing

Sequence

Forge Normalize Anneal (if required) Rough machine Semifinish machine. allowing only grinding the case depth per side for carburizcd parts Carburize and quench Temper

stock. no more than 10% of

Alloy Steel I499

9310H: Hardness vs Tempering Temperature. average based on a fully quenched structure

9310H: End-Quench Distance frum quenched surface 1/l~in. mm

1 2 3 4 5 6

Hardenability

Elardness, ARC max min

1.58 3.16

4.74 6.32

1.90 9.48

I

11.06

8 9

12.64 14.22

10 11

15.80 17.38

12

18.96

43 43 43 42 42 42 42 41 40 40 39 38

Diagram.

36 35 35 34 32 31 30 29 28 27 21 26

Austenitized

Distance From quenched surface 916 in. mm 13 14 15 16 18 20 22 24 26 28 30 32

20.54 22.12 23.10 25.28 28.44 31.60 34.16 37.92 41.08 44.24 47.40 50.56

Hardness, HRC mar min 31 36 36 35 35 35 34 34 34 34 33 33

26 26 26 26 26 25 25 25 25 25 24 24

20 min at 829 “C (1525 “F). Source: Climax Molybdenum

Company

Represents

an

500 / Heat Treaters

Guide

9310: Microstructures. Note: For (a to g), specimens were gas carburized at 925 to 940 “C (1695 to 1725 “F) for 4 h in a pit-type furnace, furnace cooled, austenitized at 815 to 830 “C (1500 to 1525 “F), oil quenched, and tempered at 150 “C (300 “F) for4 h. Case carbon contents vary because of variations in the carbon potential of the carburizing atmosphere. (a) 2% nital, 500x. Gas carburized to a maximum case carbon content of 0.60% (lean). (b) 296 nital, 500x. Gas carburized to a maximum case carbon content of 0.85%. (c) 2% nital, 500x. Gas carburized to a maximum case carbon content of 0.95?& (optimum). (d) 2% nital, 500x. Gas carburized to a maxrmum case carbon content of 1.05%. (e) 2% nital, 500x. Gas carburized to a maximum case carbon content of 1.1046. (f) 2% nital, 500x. Gas carburized to a maximum case carbon content of 1.20%. (g) Picral. 200x. Normalized by austenitizing 2 h at 885 “C (1625 “F) and cooling in still air. Scattered carbide particles and unresolved pearlite in a matrix of ferrite (light constituent). (h) 396 nital, 500x. Annealed by austenitizing 2 h at 885 “C (1625 “F) and cooling slowly in a furnace. Scattered carbide particles (dark constituent) in a matrix of ferrite (light constituent)

Alloy Steel / 501

9310H: Hardenability

Curves. Heat-treating

(1700 “F). Austenitize:

845 “C (1555 “F)

iardness wrposes distance. qm

5

,l 13 15 !O !5 30 15 to $5 $0

iardness wrposes distance.

&ill.

0 1 2 3 14 15 16 18 !O !2 !4 !6 18 $0 2

limits for specification Hardness, HRC hlavimum Minimum 43 43 43 43 43 42 41 40 38 36 35 35 34 34 33

36 35 34 33 31 30 28 27 26 25 25 25 25 24 24

limits for specification Hardness. HRC Maximum hlinimum 43 43 43 42 42 42 42 41 40 40 39 38 31 36 36 35 35 35 34 34 34 34 33 33

36 35 35 34 32 31 30 29 28 27 27 26 26 26 26 26 26 25 25 25 25 25 24 24

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 925 “C

502 / Heat Treaters

Guide

9310RH: Hardenability Curves. Heat-treating “C (1700 “F). Austenitiie: 845 “C (1555 “F) Hardness purposes

limits

J distance. I,16iIl.

for specification Eardness, Maximum

HRC Minimum

-IT! 42 42 II -II 40 4) 39 38 37 37 36 3s 34 31 33 33 3’ ;:! 32 32 32 31 31

Hardness purposes J distance. mm I .s 1

limits

37 36 36 3s 34 33 32 31 30 29 29 18 28 2x 28 17 27 26 -76 26 26 26 2s 25

for specification Hardness, Maximum -I? -I? 42 -II -IO -IO 39 37 35 33 32 32 3’ ;I 31

HRC Minimum 37 36 36 3s 33 3’ 3; ‘9 28 27 xl 76 26 25 3

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 925

1

Alloy Steel / 503

94Bl5,94Bl5H Chemical

Composition.

9JB15. AM:

0.13

to

Recommended

0.18 C. 0.75 to I .OO

Heat Treating

Practice

hln. 0.035 P mas. O.O-tO S max. 0.30 to 0.60 Ni. 0.30 to 0.50 Cr. 0.08 to 0. IS MO. 0.0005 B min. UTVS: 0. I? to 0. I8 C. 0.75 to I.00 hln. 0.035 P ma~.0.0-10Smax.0.15to0.30Si.0.30to0.60Ni.0.30to0.50Cr.0.08to 0. IS MO. 0.0005 B min. IJNS H94151 and SAE/AISI 9JBlSH: 0. I? to 0.18 C. 0.70 to I.05 Mn. 0.15 to 0.35 Si. 0.35 to 0.65 Ni. 0.25 to 0.55 Cr. 0.08 to 0. I5 MO. B (can be expected to he 0.0005 to 0.003 percent)

For a predominantly pearlitic structure. heat to 900 “C ( 1650 “F). cool rapidly to 665 “C ( I230 “F) and hold for 5 h. For a predominantly spheroidized structure. heat to 800 “C ( 1175 “F), cool rapidly to 665 “C t 1330 “F). and hold for IO h

Similar

Tempering.

AMS

Steels (U.S. and/or

6375

ASTM

A;

ASTM

4519:

Foreign).

SAE

94B15. l!NS W-I IS I: J-KJ-L 1770. 94B15H. 1rNS H9-tlSl:

A304: SAE J I268

Characteristics. One of the tuo principal boron-containing _erades used for case hardening, either carburizing or carbonitriding. Dependmg on the precise carbon content within the allowable range. as-quenched hardness (without case) usually ranges from 35 to 40 HRC. However. because of the boron addition. the hardenability of this grade is higher than that 01 an X6OOH grade of similar carbon content. although the ranges of Ni. Cr. and MO are lower for 94B I5H. Used for carburized parts ibhich have heavy sections and need the higher hardenability. Cost is generally less than that of a higher alloy grade not containing boron Nhich would be required to provide the same hardenahility Forging. temperature

Heat to 1245 “C (27-75 “F) maximum. Do not forge after of forging stock drops helo\{ approximately 900 “C t 1650 “F)

Normalizing.

Hsat

to 93.5 “C t 1695 “F). Cool

in air

Annealing.

Temper all carburized or carbonitrided parts at I SO “C (300 “F), and virtually no loss of case hardness results. If some decrease in hardness can be tolerated. toughness can he increased by tempering at somewhat higher temperatures. up to 260 ‘C (SO0 “F)

Case Hardening.

See carburizing

and carbonitriding

Processing

Sequence

Recommended l

Distance &om quenched surface 1,‘,6 in. mm

Hardenability

Bardness. q RC min max

Distance From quenched surface ‘116 in. mm

Bardness, BRC mltY

7 3 4 5 6

I

I.58 3.16 4.7-l 6.32 7.90 9.18

IS 1s 4-l 44 13 12

38 38 37 36 32 28

13 II IS I6 18 70

20 s-l 12.12 13.70 15.28 28 +I 31.60

30 29 28 27 ‘6

7 8 9

I I.06 12.64 14.7-7

10 38 36

2s 13 II

2’ 2-l 26

34 76 37.92 11.08

24 23 23

IO

IS.80

3-l

20

28

44.2-l

22

II I?

17.38 I&%

33 31

30 3’

47.40 SO.56

27 22

I5

de-

l l l l l

l

Forge Normalize Anneal (if required) Rough machine Carburize or carhonitride and quench Semifinish machine. allowing only grinding smck, no more than IO4 of the case depth per side for carbuhzed parts. In most instances. carbonitrided parts~are’completely finished in this step Temper

94815,94615H: HardnessvsTemparingTemperature. sents an average based on a fully quenched structure

94B15H: End-Quench

processes

scribed for 8630H

Repre-

504 / Heat Treaters

Guide

94615H: Hardenability

Curves. Heat-treating

“C (1700 “F). Austenitize:

925 “C (1700 “F)

Hardness purposes I distance, nm 1.5

Hardness wrposes I distance. j/16in.

1

limits for specification Hardness. HRC Maximum Minimum 45 45 45 44 42 40 38 36 31 28 26 24 23 22 22

limits for specification Hardness, HRC hlinimum hlasimum 45 45 44 44 43 42 40

IO II 12 13 14 1s 16 18 20 22 24 26 28 30 32

38 38 37 34 30 26 22 20

38 36 34 33 31 30 29 28 27 26 25 24 23 23 22 22 22

38 38 37 36 32 28 25 23 21 20

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 925

Alloy Steel / 505

94Bl7,94Bl7H Chemical

Composition.

94B17. AISI: 0.1s 100.10 C. 0.75 to I .OO

hln.0.035 Pmax.0.010Smax.0.15 to0.30Si.0.30to0.60Ni.0.3Oto0.SC) C-r, 0.08 to 0.15 MO, 0.0005 to 0.003 8. UNS: 0.15 to 0.20 C. 0.75 IO 1.00 hln,0.03SPmax.0.0~0Smax,O.lSto0.30Si,0.30to0.60Ni.0.30to0.S0 Cr. 0.08 to 0. IS MO. O.CHJOSB min. UNS A94171 and SAE/AISI 9JB17H: 0.1-l to 0.20 C, 0.70 to I.05 hln. 0.15 IO 0.35 Si. O.?S to 0.6s Ni. O.ZS to 0.55 Cr. 0.08 to 0. IS MO. B (can be expected to be 0.0005 IO 0.003 percent)

Similar

Steels (U.S. and/or

AMS 6375: ASTM ASl9: ASTM A30-l: SAE J I268

Foreign).

9JB17. LINS G9-l I7 I :

SAE J-IO-I. 5770. 94B17H.

UNS

H49-ll71:

Annealing.

For a predominantly pearlitic structure, heat to 900 “C ( 1650 “F). cool rapidly to 665 “C ( I230 “F). and hold for -1 h. For a predominantly sphsroidized structure, heat to 800 “C (l-l75 “F). cool rapidly to 665 “C ( I?30 “F). and hold for IO h

Tempering.

Temper all carburized or carbonitrided parts at I50 “C (300 “F). and virtually no loss of case hardness results. If some decrease in hardness can be tolerated. toughness can be increased by tempering at somewhat higher temperatures, up to 260 “C (500 “F)

Case Hardening.

Characteristics.

The compositions of 91B I7H and 9AB ISH are identical, escept for a slightly higher carbon range from 9dB l7H. The characteristics of these two pades are essentially the same. Because of the higher carbon range, as-quenched hardness range without case is slightlq higher for 9-lB l7H. approximate11 37 to -lZ HRC. The hardenabilit) pattern for 9-1Bl7H is the same as for 91BlSH. except the entire band for 9-+Bl7H is shifted upward because of the higher carbon content. Grade 91Bl7H is often used instead of 91B I SH I\ hen a higher core hardness is needed for carburized parts

Recommended l l l l l

Forging.

Heat to IX5 “C (‘775 ‘F) mzsimum. Do not forge atier temperature of forging stock drops belo\\ approximately 900 “C I 1650 ‘F) l

Recommended Normalizing.

Heat Treating

Heat to 97-S “C (I695

Practice

See carburizing

and carbonitriding

processes

de-

scribed for 8610H

l

Processing

Sequence

Forge Normalize .Anncal (if required) Rough machine Semifinish machine. alloying only grinding stock. no more than IOQ of the case depth per side for carburized parts. In most instances, carbonitrided parts are completely finished in this step Carburize or carbonitride and quench Temper

“F). Cool in air

94617: Isothermal

Transformation

Diagram. Composition:

O.l9C, 0.77 Mn, 0.42 Ni, 0.4OCr, 0.12 MO, 0.0018B. at 925 “C (1695 “F). Grain stze: 7 to 8

Austenitized

94817,94617H:

Hardness vs Tempering Temperature. Repre-

sents an average

based

on a fully quenched

structure

506 / Heat Treaters

Guide

94B17H: Hardenability

Curves. Heat-treating

“C (1700 “F). Austenitize:

Hardness surposes I distance, nm

I .5 1

925 “C (1700 “F)

limits for specification Hardness, HRC hlinimum hlaximum 46 46

39 39 38 36 31 26 24 22

46 45 44 43 41 39 34 30 28 26 25 24

hardness wrposes I distance, /I6 in.

.

limits for specification Hardness,

hladmum 46

IO II 12 13 14 I5 I6 I8 TO 12 !4 !6 !8 IO )2

46 45 45 44 43 42 41 40 38 36 34 33 32 31 30 28 21 26 25 24 24 23 23

HRC hlinimum 39 39 38 37 34 29 26 24 23 21 20

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 925

Alloy Steel / 507

94817H: End-Quench Hardenability Distance from quenched surface l/16 in. mm

Hardness, HRC max min

-l 5 6 7

I S8 3.16 4.7-l 6.33 7.90 9.18 Il.06

46 16 35 1s J-4 43 -I?

39 39 38 37 3-l 29 26

8 9 I0 II I2

I2.6-l I-l.22 IS.80 17 38 I8.%

II 40 38 36 3-l

7-l 23 21 20

I ? 3

Distance from quenched surface 1, mm 46 in. I3 I-l IS I6 I8 20

Hardness, HRC max

22

10.51 2.12 23.70 2.5 33 28.4-l 31.60 31.76

3.1 32 31 30 28 27 26

21 26 7-8 30 32

37.92 41.08 -u.Ll 17.40 SO.56

2.5 L-l 2-i 23 23

94817: End-Quench Hardenability.

Composition: 0.19 C, 0.77 Mn, 0.42 Ni, 0.40 Cr, 0.12 MO, 0.0018 B. Austenitized at 925 “C (1695 “F). Grain size: 7 to 8

Alloy Steel / 507

94B30,94B30H Chemical

Composition.

93B30. AISI: 0.28

to

0.33 C. 0.75

to

I .OO

Mn.0.03SPn~ax,0.~0Sn~~~.0.lSto0.30Si.0.?0to0.60Ni.0.3OtoO.S0 Cr. 0.08 to 0. IS Mo. 0.0005 to 0.003 B. UNS: 0.28 to 0.33 C. 0.75 to 1.00 hln.0.03SPn~ax.0.~0Sn~~~.0.lSto0.3OSi.O.?Oto0.60Ni.0.30to0.S0 Cr. 0.08 to 0. IS MO. 0.0005 B min. UNS H9-1301 and SAE/AISI 91B30H: 0.27 to 0.33 C. 0.70 to I.05 Mn, 0.15 to 0.35 Si. 0.25 to 0.65 Ni. 0.25 to 0.55 Cr. 0.08 to 0. IS MO. B (can be expected to be 0.0005 to 0.003 percent)

Similar

Steels (U.S. and/or Foreign).

ASTM ASl9: SAE 1104, JJl2. A304 SAE J I268

93B30. LlNS G9-1301; 1JNS H94301; ASTM

J770. 9JB30H.

Characteristics. Clearly demonstrates the effects of boron upon hardenability. 91B30H is nearly identical with 86B?OH. although the alloy ranges (Ni. Cr. Mo) are slightly lower for 91B30H. The hardenability because of the boron addition is nearly as high for 86B?OH. As-quenched hardness, which is controlled mainly by carbon content. is the same for 94B30H as for 86B30H. approximately 46 to 52 HRC

Forging. temperature

Heat to 1230 ‘C (2250 “F) maximum. Do not forge after of forging stock drops below approximately 925 “C (I695 “F)

Recommended Normalizing.

Heat Treating

Practice

Heat to 900 “C t 1650 “F). Cool in ait

Annealing.

For a predominantly pearlitic structure. heat to 845 “C ( IS55 “F). cool slowly to 730 “C t I ?SOW~F). then cool to 640 “C (I I85 “F). at a rate not to esceed I I “C (20 “F) per h: or heat to 845 “C ( IS55 “F), cool rapidly. to 665 “C (I230 “FL and hold for 7 h. For a predominantly spherotdired structure. heat to 760 “C (1300 “F), cool rapidly to 730 “C t I350 “FL then cool to 650 “C t I200 “F), at a rate not to exceed 6 “C ( IO “F) per h: or heat to 760 “C ( 1100 “F). cool rapidly to 665 “C ( I230 “F). and hold for IO h

Hardening.

Austsnitire

Tempering.

Parts should be tempered immediately after quenching \c hich will pro\ ide the required hardness

the temperature

at 870 “C ( 1600 “FL and quench in oil at

508 / Heat Treaters

Guide

Processing

Recommended

Sequence

l l

l l l

Forge Normalize r\nneal

l l

Rough and semifinish machine Austenitize and wench Temper Finish machine

94830: Hardness vs Tempering Temperature. Composition: 0.28 to 0.33 C. 0.75 to 1 .OO Mn, 0.040 P max, 0.040 S max, 0.20 to0.35Si,0.30to0.60Ni,0.30to0.50Cr,0.08to0.15Mo,0.0005 B min. Approximate critical points: AC,, 720 “C (1330 “F); AC,, 805 “C (1480”F);Ar,, 750°C (1380”F);Ar,, 655°C (1210°F). Recommended themal treatment: forge at 1230 “C (2250 “F), anneal at 815 to 870 “C (1500 to 1600 “F) for a maximum hardness of 174 HB, normalize at 870 to 925 “C (1600 to 1695 “F) for an approximate hardness of 217 HB. quench from 855 to 885 “C (1570 to 1625 “F) in oil. Test specimens were normalized at 900 “C (1650 “F), quenched from 870 “C (1600 “F) in oil, tempered at 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel

94B30H: End-Quench Distance from quenched W-fNe

‘[bin.

mm

Hardenability

Hardness, HRC min ma\:

Distance from quenched surface ’ 16 in. mm

Hardness. HRC min may

I 2

I SY 3 16

Sh 56

19 1Y

I! I-I

20.54 22.12

SO 19

30 2Y

3 4 s 6 7

1.7-t 6 32 7.90 9.33 I I.06 12.64 I-I.22

ss ss 51 51 5.; 53 s?.

48 48 -I7 46 u 42 39

IS I6 I8 20 22 2-l 26

‘3.70 15.28 ‘8.44 31 60 31.76 37.92 -II 0s

4x 46 4.4 12 40 38 37

28 ‘7 2s 24 23 23 22

I0

IS.XrJ

52

II I2

I7 38 I X.96

51 Sl

37 31 32

28 30 32

44.21 47.10 so 56

3s 3-1 3-t

21 21 20

x

9

Alloy Steel / 509

94B30H: Hardenability “C (1650 “F). Austenitize:

Hardness wrposes I distance. nm ..5

3 11

13 15 !O !5 SO $5 lo 15 50

I distance, !& in.

2 3 Q 5 6

7 8 9 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32

Curves. Heat-treating 870 “C (1600 “F)

limits for specification Hardness, hlaximum

HRC Minimum

56

49

56 56 55 55 54 53 53 51 47 43 40 31 36 34

49 48 47 46 44 41 38 31 26 24 23 22 21 20

Hardness, hlaximum

56 56 55 55 54 54 53 53 52 52 51 51 50 49 48 46 44 42 40 38 37 35 34 34

HRC hlinimum 49

49 48 48 47 46 44 42 39 37 34 32 30 29 28 21 25 24 23 23 22 21 21 20

temperatures

recommended

by SAE. Normalize (for forged or rolled specimens

only): 900

510 / Heat Treaters

Guide

No. 5317 0.50 C. 0.50 Mn. 0.25 Si. I.75 Ni. I .OO Cr

Hardening.

A cold melt. grain controlled. electric furnace steel heat treatable to combination of hardness and toughness for machine parts in t\\o classes:

Tempering.

Chemical

Composition.

Characteristics.

Hard tempering group. for gears and other hard parts. hardened and tempered between 105 to 345 “C WJO to 655 “F) 2. Tough tempering group for parts such as shafts. hardened and tempered between 370 to 595 “C (700 to I IO5 “F)

Heat to 790 to 8 IS “C f I.455 to 1500 “F). and quench in oil

Temperature used depends on service conditions. Lower temperatures (see table beloa ) are used when greater surface hardness and strength are required. Higher temperatures are used for greater toughness

I

Steel has no special tendencies to decarburize. Machinabilit) is 65 to 75 percent of I percent carbon. Mater hardening tool steel. or about SO percent that of BIII’

Forging.

Heat to I I SO “C i2 100 “F) maximum. Air cool in dQ place. Do not forge after temperature of forging stock drops belo\i approximate11 8 I5 “Ctl5OO”F)

Recommended Normalizing.

Heat Treating

Practice

Heat to 815 to 900 “C ( 1555 to 1650 “FJ. Cool in air

Annealing. Pack steel in container. usmg neutral packing compound. or treat in controlled atmosphere furnace. Heat parts to 760 “C ( 1400 “F). cool slowly in furnace at a rate not to exceed I I “C (20 “F) per h until furnace is black. and may then be turned off and allowed to cool naturally. Parts have maximum hardness of 201 HB

No. 5-317:

Effect of Tempering

Tempering temperature OF T As quenched 300 350 -u?o 150 500 540

600 700 800 900 loo0 1100 3 mm ( I in. I. seaion.

As quenched 149

177 20-i 232 260 288 316 371 4’7 J82 538 593 oil quenched From 790 “C I 1450 “Fb

Ruckwell ‘C” 56 56 55 54 53 53 52 SO 46 -l-t 40 35 31

510 / Heat Treaters

Guide

CRB-7 MO. I .OOV. 0.25 Cb

soak forging at this temperature until temperature of forging is uniform. then shut off heat. let forging cool in furnace. Annealing follows

Characteristics.

Recommended

Chemical

Composition.

I.10 C. 0.10 hln. 0.30 Si. I-I.00 Cr. 2.00

A corrosion resistant. \rear resistant. and secondq hardening. high temperature bearing steel. which has high heat treated hardness that is maintained at elevated temperatures

Forging.

Preheat slou ly to 815 to 870 “C ( IS00 to 1600 “Ft. then increase furnace temperature to full heat of I095 to I I?0 YI (2005 to 2050 “F). Do not forge after temperature of forging stock drops below approsimatell 980 “C ( I795 “F). Can be reheated as often as necessary. Slow cool forgings IO room temperature m dq ash. vemticulite. or in a furnace \\ hen forging cooling. First set furnace at about 760 to 790 “C t l-t00 to 1455 “Ft.

CRB-7:

Effect of Tempering

Rnckwell T

r\s quenched + reirigrratrd 300 l-l9 100 mo hfxl 700 800 900 loofl I lcil

Annealing.

Practice

Not recommended Tno methods are available:

I Pack parts in container. using clean. cast iron borings 1. hned in a controlled atmosphere furnace with a dew point of I .S to 8 “C (35 to IS “FJ. Heat unifomtl~ to 870 to 900 ‘C (I600 to 1650 “F), cool slowly in furnace to about 595 “C t I IO5 “F) at a rate not to exceed 6 “C (20 “F) per h. air cool to room temperature.

Temperatures

Tempering temperature OF

Normalizing.

Heat Treating

‘0-l 160 316 371 427 3x2 S38 SY3

CRB-7:

C

Elevated

Hardness 63.5 61.0 59.5 58.0 5X.0 58.0 605 62 0 53 s

Rockwell Eardnes

260 316 371 127 482 538

62.5 59.0 58.5 58.0 57.0 56.0 51.0

Room temperature 500 600 700 800 900 1000

“FL and

Hardness

DC

Test temperature OF

64.0

Parts were oil quenched from I I SO “C (2 IO0 ‘FL refrigwatrd BI -7S ‘C f-105 tempered I h a~ temperature. Source. Carpenter Technolog? Corporation

Temperature

C

Hardnesses uere measured on specimrw heat treated as follows: salt quenched from I ISOYZ t Z IO0 “F) to Ml ‘C t 1000°F~ equaltzcd, then aircooled toroom temperature, streisrelievedat ISO”C(3Ot”Fb I h,refrigcratedat-7S”C(-105”F).douhletempered 2 + 2 hat 525 “C (975 “F). Source: CarpznterTechnolo~ Corporation

Alloy Steel / 511

Average hardness of parts will be 2-I I HB

Hardening. Parts are treated in neutral salt baths or in controlled atmosphere furnaces. For the latter, a dew point of - I7 “C (+ IO “F) is suggested. For the furnace procedure. oarts are preheated to 800 to 830 “C t 1375 to IS3 “F). then transferred to a superheating furnace maintained at I I-IO to I IS5 “C (2085 to 21 IO “F). Small parts may be oil quenched to room temperature. Preferred practice is to harden by quenching in molten salt at

a temperature of S-IO to 595 “C ( 1000 to I 100 “F). followed by air cooling to room temperature. Parts are then stress relief tempered at -ISO “C (3% “F) for I h. For higher hardness and dimensional stability, parts are allowed to return to room temperature before tempering

Tempering.

Double tempering is recommended for maximum hardness and dimensional stability. Parts are allowed to return to room temperature before tempering

Tool Steels Introduction Tool steels represent a small, but mlportant segment of the total production of steel. These steels are made and processed IO meet extremeI> high standards of qualiy control and are used principally for tools, dies. and components of mechamcal de\ ices that demand steels with special properties. Well over IO0 different kinds of tool steels are produced at the present time. and if all the trade names Mere added together. the total \\ould far exceed 100. Tool steels vary in composition from plain carbon steels containing carbon with no significant amounts of alloying iron and up to 1.X elements. to veq highly alloyed grades. in which the total allo) content approaches 50% Many tool steels are identical in composition to carbon and alloy steels that are produced in large tonnages. The ditierences lie in the small amount produced and the high level ofqualitj control in\ol\ed. Classification of Tool Steels. Tool steels do not lend themselves to the type of classification used by the Societ) of Automotive Engineers (SAE) and the American Iron and Steel Institute (AISI) for low-alloy steels. because in these systems an entire series of steels is defined numerically, based upon a variation of carbon content alone. \\Iile some carbon tool steels and low-alloy tool steels are made in a u ide range of carbon contents. most of the higher alloyed tool steels have a compamlively narrow carbon range makmg such a classiticatlon meaningless. Instead a mixed classification system is used uith tool steels. in M hich some steels are grouped hy use. others by composition or bq certain mechanical properties. and still others by the method of heat treatment (precIseI) hy the quenching technique). High-speed steels are grouped together because the) have certain common properties, the water-hardening steels because the) are hardened in a common manner. the hot \\ork steels because they have certain common properties, and the high-carbon. high-chromium steels because they have similar compositions and similar applications. The American Iron and Steel Institute System. The table at the end of this introduction includes compositions for most of the proprietary tool steels-Unified Numbering System (UNS) specifications are also given. Elements are listed in nominal amounts which ma) vary someis hat for different tool steel producers. U’hen heat treating shops receive tools for heat treatment that are identified only by proprictq name. the AISI identiticatton should heobtained before attempting to perform an! heat treating operation. A number of grades ha\e heen deleted from the AISI list because thsj were no longer manufactured in signiticant quantities. and the steels listed in the table cover every conceivable tooling requirement. Statistics show that over S(Y? of the total tonnage of tool steels produced is confined to no more than about I? or I5 of the compositions included in the Table. The grouping of tool steels published bq AISI has proved MoorlaMe. and the nine main groups and their corresponding sjmhols are giLen as follows~ Identifying symbol

Name IVater-hardening

1001 SltXlj

M

Shock-resisting tool steels Oil-hardrmngsold work tool ~IZZIZ Air-hardening. medium-alloy cold \rorh tool SIeelb High-carbon, high-chromium cold \rorli 1o4 steels

S 0 .A D

hlold steels

P H

Hot #ark tool steels. chromium, tungsvn. and mol)bdcnum Tungsten high-speed rool su&

T

hlol) bdenum high-speed tool seeIs

hl

Water-Hardening Tool Steels. The grades listed in the Table under the symbol IV are essentially c,arbon steels and are among the least expensive of tool steels. They must he water quenched to attain the necessary hardness, and except in veq small sizes, will harden with a hard case and a soft core. These steels ma) be used for a wide variety of tools. but the) do have limitations. H’ steels are available in a range of carbon contents. and the selcctlon of carbon content is based upon whether maximum toughness or mrt\imum wear resistance is the more important. A lower carbon content pro\ ides maximum toughness. Although all W steels have rslntivel~ low hardenabilitl. these grades are usually available as shallow. medium. or deep hardening. and this property is controlled by the manufacturer. Of the three compositions listed. WI is the most extensively used. Shock-Resisting Tool Steels. Steels are listed under the symhol S. As ma) be noted in the Table. the alloy content in these steels varies uidelj, resulting in a \yidc variation in hardenability among the grades. However. all S steels are intended for applications that require extreme chisels. toughness including punches, shear knives. and air-operated Grades Sl (tungsten bearing), and SS (high silicon) are most widely used. Oil-Hardening, Cold Work Tool Steels. These grades are listed in the table under the symbol 0. As agroup, the hardenability ofthese steels is much higher than that of the W grades: therefore, they can be hardened hq quenching in oil. Grade 01 is by far the most popular of this group. A portion of the carbon in 06 is in the form ofgraphite. which allows helter machinability, a factor HI making intricate dies. In addition. the graphite particles in its microstructure provide a built-in lubricant, giving these steels a better die life for deep dra\b ing operations. 07 is sometimes used for certain dies where it is essential to retain keen cutting edges hecause these steels have a higher carbon and the tungsten addition. Air-Hardening,

Medium-Alloy

Cold Work Tool Steels.

The cold work tool steels listed under the symbol A cover a wide range of carbon and alloy contents, but all habe high hardenability andexhibit a high degree of dimensional stahilit) in heat treatment. The low-carbon types, A8 and A9. offer greater shock resistance than the other steels in this group, but are lo\rer in their wear resistance. Type .A7, which has high carbon and vanadium contents. exhibits maximum abrasion resistance, but should be restricted to applications where toughness is not a prime consideration. As ma) be noted in the Table, A IO is also a graphitic steel, and it has properties similar IO 06 except that A IO is higher in hardenability. Of the grades listed in this group. A). is the most wideI> used.

High-Carbon,

High-Chromium

Cold Work Tool Steels.

The cold work steels listed under the symbol D are all characterized by a high carbon content t I .S to 2% ) and a nominal 12.08 chromium content. T> pes containing mol> bdenum can he air hardened. All grades of this group have extremely high resistance to abrasive wear, which increases as the carbon and vanadium increase. Grade D7 is one of the most abrasion-resistrng steels knon n. and it is often used for such rigorous applications as brick molds. Ho\\e\er. the characteristics uhich provide its abrasion resistance make it \ery difficult to machine or grind. Grade D5, because of its cobalt addition. can he used for hot fomting or shearing operations at tempemtures up to 480 “C (895 “F). Of the five grades listed in this group, D2 is the most \I idsI> used. Low-Alloy, Special-Purpose Tool Steels. The tool steels listed under the symbol L cover a wide range of alloy content and mechanical properties. They are wideI> used for die components and machinery parts. Both L6 and the lo\rcr carbon versions of L? are often used for

514 / Heat Treaters

Guide

Classification

and approximate

AISI

UNS No.

Water-hardening WI W2 W5

C

Oil-hardening,

Air-hardening, A2 A3 Al A6 A7 A8 A9 AlO

High-carbon, D? D3 M DS D7

Identifying elements, 70 v If

hlo

co

Ni

025

2 so

1.50 0.80 I.10

I In 2.00 2.25

0 w, 0.40 0.40 I.40

I.50 3.25

cold work tool steels 0.90 0.90 I .-IS I.20

medium-alloy

I .tMl 1.60 0.80

0.50

0.90

0.75

1.75

I.00

0 25

cold Hark tool steels I .OO I.25 1.00 0.70 2.25 0.55 0.50 1.35

T-30102 T30103 T3Olo-1 T30106 T30 IO7 T30108 no109 T30110

bighchromium

5.00 5.00 I.00 lo0 _ _ 3 .2 > 5.00 S.00

2 00 2.00

1.80

I SKI

-1:;5

I OO(Cl I .29

I Ml

I.25

I On I .OO I.00 I.25 I .OO I.25 I .-lu I .SO

I50 1.80

cold work steels 11.00 l-7.00 1200 I2.00 I’.00

1.50 2.3 2.3 I so 2.35

special-purpose

L6

Cr

o.;o

0.50 0.50 0.55 0.45 0.50

T30402 l-30403 T3o-Io-1 T3040.5 T30407

Low-alloy, I2

types of tool steels

tool steels

T3lSOl T3 1502 T31506 l-3 I so7

01 02 06(b) 07

Si

0.60-I .-m(S) 0.60-1.10(a) I.10

T-II901 T-l I902 T4 I905 T-II906 T4 I907

SI S2 S5 S6 Sl

hln

of principal

tool steels T72301 l-7230’ l-72305

Shock-resisting

compositions

I00

I Ml

-1.00

1.00 I SKI I.00

3.00

tool steels

T6 I202 T61206

O.SO-l.IO(ar 0.70

I 00 0 75

TS I602 T5 1603 TSl6O-l T5 160s TSl606 TSl620 TSl621

0.07 0.10 0.07 0.10 0.10 0.35 0.30

2 00 060 5 00 ‘5 -’ -_ I SO I .70

0.20 O.GiCl

I .so

0.20

0.50 1.2.5

Mold steels P2 P3 P-l PS P6 P20 El

Chromium

0.75 3.50 O.-l0 itlo

I.lO~Al)

hot work tool steels T?0810 T208ll I’20812 l-20813 l-208 I J T20819

HI0 HII HI2 HI3 HI1 HI9

0.40 0.3S 0.35 0.35 0.40 0.40

3.15 S.00 s.00 S.00 5 00 l.2.s

0.35 0.35 0.30 0.45 0.25 0.50

0.60

0.40 040 O-IO 1.00

I .so

2.00

;:im 4.25

3.50 2.00 12.00 3.00 4.00 4.00

I:&

9.00 II.00 I2.00 I S.00 IS.00 18.00

1.00

200

6.00

2 50 I .SO I so I so 1.25

Tungsten hot work tool steels T-2081 I I20822 l-20823 TzO82-l l-20825 r-0826

HZI H22 H23 HZ-l H?S H26

hlolybdenum H-U

lbgsten TI IT!

(81 A\ailsble

hot work tool steel T208-l’

high-speed tool steels TllOOl Tl2002

with different

-1.00 1.00 Ironllnu~dI

0.751a1 0.80

carbon conlen&.

I b, Contains graphw.

(L‘J Opional

I .Ou 2.00

18.00 18.00

5.00

Tool Steels / 515

Classification

and approximate

AISI

UNS No.

Tl2OOS Tl2006

TX TIS

TlNQ8 T170lS

hfolybdeoum hll hl2 h13. class I M3. class 2 hll h16 h17 hfl0 hl30 hl33 h13-I h135 M36

Ultrahard h1-l I

M1? hl-13 MU

hi&speed

of principal

types of tool steels Identifying

C

Rmgsleo high-speed tool steels Tl2004 l-4 TS T6

compositions hln

Si

Cr

elements, % v w

-1.00 -I.00 -I.50 -I.00 1.00

1.00 2.00 1.50 2.00 5.00

4.00 4.00 1.00 -I.00 4.00 -I.00 4.00 1.00 -l.oCJ -loo 4.00 3.75-1.50 4.oCJ

1.00 2.00 2.10 3.00 4.00 200 2.00 2.00 I.25 I.15 2.00 1.75-1.20 2.00

4.3 3.75 3.75 1.25 1.00 3.75 3.50.4.00 3 75-1 so 3 504.30 3 50-400

2.00 I.15 I.60 2.00 3.20 I.25 2.75-3.x 0.80-I .3 I .65-2.2.5 I .80-2.00

0.75 0.80 0.80 0.75

I.50

(continued) hlo

18.00

co

Ni

5.00 8.00

18.00 ‘0.00 14.00 I ?.(JO

12.00 5.ocl 5.00

.

tool steels

Tll301 Tll30’ Tll313 TI 1323 Tll301 Tll306 TI 1307 Tll3lO Tll3.30

Tll333

0.8Ois) 0.85-1.00(a) I.05 1.20 1.30 0.80 I .OO 0.85-l w(a) 0.80

0.90

TI 13.33 TI I.335 TI 1336

high-speed bol steels Tll311 Tll3-U TI 1313

hl-16 M47 hl-48 hlS0

Tll3-U Tll34.6 Tll347 TI 13-18 TI I350

hlS2 h162

TI 1352 TI 1362

0.90 0.X2-0.88 0 80

0. I s:o.10

0.20-0.4s

I.10 I.10 1.20

I.15 I J.5 I IO I .-l1- I .52

0.15-0.40

0 78-0.8X 0.85-0.95 1.25-1.3s

0 IS-O.45 0. IS-O.-IS 0.15-0.40

0.15-010 0.20-0.60 0.20-0.60 0. I s-o.40

I.50 6.00 6.00 6.00 5.50 -1.00 I .75

1.00 I so 2.00 9.50-6.75 6.00

6.75 I .so 2.75 5.25 2.00 I.50 9 50. IO.50 0.75-I so 5.75-6.50

8.00 5.00 5.00 s.ocl -1.50 5.00 8.75 x.00 8.00 9.50 8.w 5.00

3.75 9.50 8.00 6.25 8.25 9.50 0 IS -0.40 3.90-4.7s 4.00-4.90 lO.W- I I .oo

12.00

5.00 8.00 8.00 1.50-5.50 8.00

0.30 max

5.00 8.ocl 8.25 12.00 8.2s 5.00 8.00-10.00

0.30“’ rllax 0.30 max 0.30 max 0.30 max

~a) Available with different cabon sontents. (b) Contains graphite. tc) Optional

applications tools.

requiring

extreme

toughness

including

punches and heading

Mold %%!I% Tool steels listed under the symbol P are generalI> intended for mold applications. Types P2 and P6 are low in carbon content and are usually supplied at low hardness to facilitate cold hubbing of the impressions. They are then carburized to develop the required surface properties for injection and compression molds for plastics. Types P20 and P2l are usually supplied in the pre-hardened condition. to allow the cavity to be machined and the mold to be placed directly in service. These grades may be used for plastic molds. zinc die casting dies. and holder blocks. Hot Work Steels. Hot work steels are divided into three groups: chromium. tungsten, and molybdenum. Of the grades of chromium hot work steels listed in the Table. grades HI I and H I3 are the most widelq used. Both of them are also used for nontooling applications, notably in the aerospace industry. Principal tooling applications include forging dies and die inserts. blades for hot shearing, and dies for die casting of aluminum alloys. Grades HI1 and HI9 are sometimes used for applications where greater heat resistance IS required. Including dies for die casting brass. The tungsten types are intended for hot work applications bhcre resistance to the softening effect of elevated temperature is of greatest importance. and a lesser degree of toughness can be tolerated. Of the grades listed in the Table, H2 I and H26 are most often used. Die casting dies for the copper-base alloys and hot extrusion tools are typical examples of their applications.

The molybdenum types are low-carbon modifications of molybdenum high-speed steels. They offer excellent resistance to the softening effect of elevated temperature. but similar to the tungsten types. should be restricted to those applications where less ductility is acceptable. These steels are not readily available except on a mill delivery basis. High-Speed Steels. The high-speed steels are divided into three groups: (a) those bearing the symbol T where tungsten is the major alloying element; (b) those bearing the symbol M indicating that molybdenum is the principal alloying element: (c) a group of more highly alloyed steels that are capable of attaining unusually high hardness values. TI was one of the original high-speed steels. although all tungsten grades are used to a limited extent because of the cost and questionable availability of tungsten. Of the T steels, general purpose TI and high-vanadium-cobalt Tl5 are most commonly used. Tl5 is used forcutting tools that are exposed to extremely rigorous heat or abrasion in service. The hl tool steels generally are considered to have molybdenum as the principal alloying element. although several contain an equal or a slightly greater amount of such elements as tungsten or cobalt. Types with higher carbon and vanadium contents offer improved abrasion resistance. but machinability and grindability may be adversely affected. The series beginning with M-l I is characterized by the capabilib of attaining exceptionally high hardness in heat treatment. reaching hardnesses as high as Rockwell C. In addition to being used for cutting tools. some of the M high-speed steels are successfull>. used for such cold work applications as cold header die inserts. thread rollmg dies, and blanking dies. For such applications, the high-speed steels are hardened from a lower temperature than that used for cutting tools to increase toughness.

Water-Hardening

Tool Steels

(W Series) Introduction The v,ater-hardening tool steels considered here (W I. H’2. and WS) are essentially carbon steels and are among the least expensive tool steels As a class, these steels are relatively low in hardenabilitj. although they arc arbitrarily classified and available as shallo\\-hardening. medium-hardening. and deep-hardening types. Except in very small sizes. LV steels u’ill harden with a hard case and a soft core. Their IOU hardenabilitl is frequently an advantage. because it allows tough core properties in combination with high surface hardness. They are available in a range of carbon content. allowing for maximum tou@u~ess with loser carbon content or maximum wear resistance with higher carbon content, depending on planned use. Water-hardening tool steels are most commonly hardened by qusnching in water or brine. However. thin sections may be hardened suitably bj oil quenching with less distortion and danger of cracking than if the sections were quenched in water or brine. In general, these steels are not normalized except after forging or before reheating treatment. for refining the grain and producing a more uniform structure. Parts should be protected against decarbunzation during au cooling. These steels are received from the supplier in the annealed condition. and further annealing is generally not required. Stress relieving prior to

Water-Hardening mum Hardness.

Tool Steels: Oil quenched

Section to 60 HRC

Thickness

vs Mini-

hardening is sometimes emplqcd to minimize distortion and cracking, particularly when tools are cornpIe\ or have been severely cold marked Similarly, prrheatinp prior to austenitizinp is unusual except for very large tools or those with intricate crosb sections. To produce maximum depth of hardness in Nater-hardening tool steels. it is essential that the) be quenched as rapidly as possible. In most instances. iiater or a brins solution consisting of IO wt C NaCl in water is used. For an Eden fa>ter quench. an Iced brine solution may be used. These steels should be tempered immediately atier hardening, preferably before the? feach room temperature. Salt bnthh. oil baths, and air furnaces are all satlstactoc; for tempenng. However. working temperatures for both oil and salt are lirmted: the minimum for salt is approximately I65 “C (330 “F), and the maximum for oil is approximately 205 “C (100 “F). Tools should be placed in a \\arm furnace of Y-l to I20 “C (200 to 250 “F) and then brought to the tempering temperature I$ ith the furnace. The resistance to fracture by impact initially increases u ith tempering temperature to approximately I80 ‘C i35S “F) but falls off rapidly to a minimum at approximately 260 “C (500 “F). Double tempering may be requued to temper any martensite that may have formed from retained nustenite dunng cooling in the first tempering c~cls.

Nater-Hardening sracking

Tool Steels:

Fracture

Grain Size vs Quench

Tool Steels / 517

Water-Hardening Tool Steels: Hardness vs Tempering Temperature. Specimens held for 1 h at the tempering temperature in a recirculating-air furnace. Cooled in air to room temperature. Data represent twenty 25 mm (1 in.) diam specimens for each steel. Each quenched from temperatures indicated. (a) Shallow hardening: 0.90 to 1 .OOC, 0.18 to 0.22 Mn, 0.20 to 0.22 Si, 0.18 to 0.22 V. (b) Medium hardening: 0.90 to 1 .OO C, 0.25 Mn, 0.25 Si. no alloying elements. (c) Deep hardening; 0.90 to 1 .OOC, 0.30 to 0.35 Mn, 0.20 to 0.25 Si. 0.23 to 0.27 Cr

Water-Hardening Tool Steels: Hardness vs Tempering Temperature. 1% C. Size: 25 mm (1 in.) round by 51 mm (2 in.) long. Valid fortempering times from l/2 to 2 h. Quench temperature: 790 “C (1455 “F) in water. First stage: The decomposition of martensite into low-carbon martensite (about 0.25 C) and epsilon carbide (Fe,&). Epsilon carbide precipitates in the form of film at subgrains, 4 to 8 l.rin. in diam in the martensite. In steels containing more than 0.8 C, the early part of the first stage reaction results in a slight increase in hardness: however, the later portion of this stage is accompanied by a gradual decrease of hardness. Specific volume decreases during this stage. Second stage: Decomposition of retained austenite to bainite takes place over the temperature range from approximately 205 to 315 “C (400 to 600 “F). Hardness continues to decrease during this stage, while specific volume increases. Third stage: Epsilon carbide and low-carbon martensite (0.25 C) react to form ferrite (body-centered cubic) plus cementite. This process is accompanied by softening. Even after the complete disappearance of epsilon carbide, cementite continues to precipitate, depleting the ferritic matrix of carbon and resulting in further softening. Coalescence of cementite particles also contributes to this softening.

518 / Heat Treaters

Guide

Water-Hardening Tool Steels: Manganese Plus Silicon Content vs Penetration of Hardness. 19 mm (3/4 in.) round bars con-

Water-Hardening Tool Steels: Alloy Content vs Hardenability. Effect of total manganese, silicon, chromium, and nickel contents on the hardenability of 1 C steels quenched in brine from 790 “C (1455 “F) for 1 h at temperature. Hardenability expressed as depth of penetration in inches for 25 mm (1 in.) round bars

Water-Hardening Tool Steels: Effect of 1% Additions Alloying Elements on Hardenability

of

Relative hardenability factors for alloy additions to 1% carbon tool steel, austenitized at normal temperatures with incomplete carbide solution. Treatment: 40 min at 870 “C (1600 “F) oil quench; 12 min at 790 “C (1450 “F), agitated brine quench (H = 5.0)

Steel I% carbon (base ) I% silicon IQ manganese I9 tungsten I%~chromium I90 molybdenum I Sr, niche1

Penetration in I%-in. round, ‘/aJ in. 5 1/2 I8 I6 4 ‘/: I6 22 IO

Multiplying

factor Corresponding D,

forl%

addition

Fracture grain size 9

0.67 I.16 1.09 0.62

1.30 2.17 0.93

9 8v~ 9%

1.09 I .-Cl 0.89

I .63 2.16 I .33

IO 93/, 9v,

taining 1 to 1.10 C, 0.02 to 0.04 Ni, 0.010 to 0.015 S, 0.012 to 3.016 P. Quenched in brine from 790 “C (1455 “F). Source: Teledyne VASCO

Water-Hardening Tool Steels: Composition Calculated Hardenability

vs Critical diameter for brine quench,

iIl.(E =-SO) Heat No. lb 7 i -I 5 6 7 8 9 IQ II I2

C

hln

1.02 1.03 I .07 I II7 I .oo I.09 104 I.00 0.97 0.99 0.98 0.9-l

009 0’8 0.15 0.3-l 0.2-l 0.26 0.29 031 0.46 0.36 o.so 0.45

13) 0.03pi vanadium

Composition, ?c Si Cr 0.03 0.1s 0.09 0.22 0.17 0.26 0.16 0.28 0.29 0.31 0.37 0.36

0.0s 0.0-l 0.05 0.10 0.09 0. I7 0.15 0 13 0 I7 0.15 0.23 0.2 I

Ni 0.02 0.02

0.10 0.03 0 07 0.20 0.1-l 0.07 0.05 0. I 7 0.12 0.16

MO

0.03 nil nil nil 0.0 I nil 0.03 0.03 nil 0.03 0.03 nil

Calculated 0.1s 0.35 0.20 0.15 0.15 O.-IS 0.50 0.60 0.80 0.75 0.90 I .o

Observed wpmx mimmum dtmcnslon of hea\ iest section of part or nested load of parts. ISnunforevc~ I:! Smm(OSin )orincrementofl2.5mmtO.Sin )over ICI I h.SmtnplusSnlinfore~eq II 5mmtO.Sin.)orincrementof 12.5 75 mm t 3 in ). Source: .AhlS 27591-l

732 / Heat Treaters

Guide

303Se Chemical Composition. AISI~~MS (~3032.3): 0.1s C. 2.00 htn. 0.200 P.O.06OS min. l.OOSi. 8.Oto 10.0 Ni. 17.0 to 19.0Cr. 0.15 Se Similar Steels (U.S. and/or Foreign). AhlS 5610 (Type 2). 5641. 5738: ASME WI94 SA320: ASTAI A 19-t. .A314. .A3?0. .4-!73. AS8 I. ,458’: hlIL SPEC MlL-S-86’: SAE J4OS (30303 Se, Characteristics. Selenium addition promotes mochinahility. Lrsed to minimize seizing or galling. hlust be annealed after \belding. Suitable for use in automatic scre\v machines. Less resistant to corrosion than other 300 steels, Shows good resistance to oxidation up to 925 “C I I695 “FF, Forging.

Start forgmg at I IS0 to 1290 “C t2100 to 1355 “Ft. Finish forS,ing at 935 to 955 ‘C t I695 to I750 9). Cool to black color in less than 3 mm. using liquid quench if necessary

Recommended Normalizing. Annealing.

Heat Treating

Practice

Do not normalize

Anneal at 1010 to I I20 “C t 1850 to 2050 OF). To guard against distortion of thin. delicate parts. leave ample room for expansion between parts. Stainless grades expand ahout twice as much as cnrhon and

lou-nlloy steels. AIIou enough time for through heattngafterthermocouple has reached temperature. Stainless grades hove approximately half the themral conducti\ ity of carbon and lou-alloy steels. Choice of atmosphere depends on finish desired and whether surface stock will be removed. For bright annealing. use 1 acuum or an atmosphere of hydrogen or dissociated ammonia at deu point of -62 to -7-t “C t-80 to -100 m. Parts must be thoroughly clean and dry. Inert gases argon and helium (although expenstvet and nitrogen. with dew points of less than -5-t “C f-65 %). can bc used. They lack the reducing effect of hydrogen. so slight discoloration in the form of chrome okids can result. Salt. exothermic. or endothermic atmospheres are satisfactory for nonbright annealing. Salt is difficult to remo\e. and rinse quenching at 595 ‘C (1 IO5 ?j is not recommended. because interrupted quench at ekated temperature cannot be tolerated. E\othemlis and endothemtic atmospheres must be carefully controlled at equivalent carhon potential to avoid cnrhunzation. which will seriously lo\rer corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present. scale will form. Difficult to remove in subsequent descaling operations. Cool rapidI! from annealing temperature; no more than 3 mm to black color. Section size detemlines quenching medium: water for heavy sections. air blast for intemrsdiate sizes. and still air for thin sections. Carbides

Austenitic

can precipitate at grain houndaries when parts are cooled too slo\rly betueen -US to 900 “C (795 to I650 “n. In aerospace practice, parts are annealed at a set temperature of 1065 ‘C. (I950 “F) and quenched in water with one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineering organization is required for annealing material in a strain-hardened condition. such as t/I hard: for stress relieving,; or for dimensional stabilization. Heat treating or slow cooling unstabilized grades between -I70 to 815 ‘C (875 to I SO0 %) is prohibited. except for 3ML and 3 16L stress RelieVing. Parts can he relieved after quenching to achieve dimensional stability. by heating to 730 to -KM “C (4-15 to 750 ‘%) for up to several hours. depending on section size and without change in metallographic structure. In aerospace practice. parts are stress relic\ ed at 900 ‘C ( 1650 9). and quenched in water. As an alternative. parts may be stress relieved at annealing, temperatures. Sections under 2.5 mm (0. IO in.) thick may be au cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as t/z hard. shall not be stress relieved without permission of the cognizant engincerinp authority. When stress relieving after welding. hold for 30 min minimum at the stress relieving temperature. Heat treating or SIOH cooling of unstabilized grades between 170 to 815 “C (875 to 1500 v) is prohibited. except for 3O-tL and 316L. See table for soaking times

Nitriding.

Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I17 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided. parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers should be replaced u ith radii of not less than I .S9 mm (0.06 in.). Film of primarily chromium oxide, that protects stainless alloys from oxidation and corrosion. must he removed prior to nitriding. Accomplished by wet blasting. pickling, chemical reduction in reducing atmosphere. submersion in molten salt, or by one of several proprietary processes. If doubt exists that complete and unifoml depassivation has occurred, further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen

Stainless

Steels / 733

atmosphere or suitable proprietary agent. After depassivation, avoid contamination of surface hv tinger or hand marking. Single-stage nitriding adequate at 525 to 550 “C (975 to 107-O “n for 20 to -18 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 3Spi. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case extending to 0. I27 mm (0.005 in.) with approximately 800 to IO00 HK. Case Lvill rapidly drop to X0 HK core hardness. at approximately 0. I65 mm (0.0065 in.)

Recommended l l l l l l

Processing

Cold work Anneal and quench Remove surface contamination Stress relieve Depassivate tif nitriding) Nitride iifrequircd)

303Se:

Soaking

Sequence

tif required)

Times (Aerospace

Diameter or thickness(a) of masbnum section mm (in.) inclusive up to 2 so10 loo) okc2.50 roh.3 ~O.100 to0 Xl) over 6.25 10 Il.50 [O.?SO IO 0.500) over II 50 to 25.00 10.500 to 1.00) 0~rr~S.00t037.50~1 0010 1.50) oter 37.5O1050.001 LSO IO 2.&J) o\ er 50.00 to 630 I 2.00 IO 30) o~er62SOto7500~250to300~ o~er75OOtZ.00~

Practice)

Miuimum Atmosphere furnace miu 20 IS 45 60 75 90 IO5 I20 ib,

soaking

time Salt batb miu 17 18 35 JO 4.5 50 55 60 (Cl

I 31 Tlushnec~ 15 minimum dimension of hcu\ iest reslion ofpar~ or nested load of parts 1b,2.?Shplus 15miniorc\q 12.5mn~~0.5in.)orincrrmentof13nun(0.5in.)o~rr 75mmlZin.l ICI I h..inlinpluj5mln~~rl\cr) 12.~~i~,~0.5in.~orincrenicnrofI2.S (0 5 rn ,o\er75 mm I3 in.) Source .AhlS 275911

Austenitic

Stainless

Steels I733

304 Chemical Composition. AISI/LlNS (S30400): 0.08 C. 2.00 hln. 0.0-E P. 0.030 S. 1.00 Si. 8.0 to IO.5 Ni, 18.0 to 20.0 Cr Similar

Steels (U.S. and/or

Foreign).

AhlS 5501, 55 13, ~60.

S56S.SS66.5567,5639.S697; AShlE S.4 182. SA 191 i8r. S.42 13. S.4210, SA249. SA312, SA320 tB8i. S.4358. S.4376. S.4-tO.I. SA?OY, S.4-130. S.4179. S.4688; ASThl .4 167. A 182, A 193, .4 19-I. A2 13. .4X0. .4249, 44369. A270. A27 I. A276. .43 12. A3 13. A3 I-1. A320. A368. ,437h. .UO9. A-IX). A173. AA7X. A-179. A-t’)‘. .4193. A5 I I. ASS-+. AS8O. A632. A65 I. 84666. 84688: FED QQ-W-423. Q763. QQ-S-766. STD-66; hllL SPEC MlL-F-30138. MJL-S-86’. MIL-S-5059. hlIL-S-33195. hlIL-S-23 lY6. IkIlL-T-68-tS. MIL-T-8504. hllL-T-8506; WE J-t05 t3030-t~: tGer.t DIN l.-I301; (Fr.) AFNOR Zh CN 18.09; (Ital.) UNI X 5 CrNi I8 IO; c’Jap.1 JIS SW 30-t: 6wed.j SSIJ 2332; (U.K.) B.S. 30-t S IS. 302 S 17. 30-t S 16. 30-l S 18.30-t S 25.3W S -10. En. 58 E

Characteristics.

Corrosion resistance higher than type 302. Nonmnpnetic n hen annealed. Slightly magnetic n hen cold marked. Less susceptible to precipitation ofcarhides during ueldinp

Forging. Start forging at I I SO to I260 ‘C 12 100 to 2300°F)). Do not forge after iorging stock drops helo\s 925 ‘C (I 695 ‘F). Cool to Hack color in less than 3 mm. using liquid quench if necessary

Recommended Normalizing.

Heat Treating

Practice

Do not nonnahzs

Annealing. .Anneul at 1010 to I I20 “C ( I850 to ?OSO’%). For maximum ductility and softness. use a minimum annealinp temperature of IO30 ‘C i 1905 ‘%). To guard against distortion of thin. delicate parts, leave ample room for espansion between parts. Stainless grades expand ahout twice as much as carbon and low-alloy steels. .Allow enough time for through heating after thcrmocouplr has reached temperature. Stainless grades have approximately half the thermal conducti\ ity ofc‘arbon and low-alloy steels. Choice of atmosphere depends on finish desired and whether surface stock will he removed. For bright annealing. use vacuum or an atmosphere of hydra en or dissociated ammonia at dew point of -62 to -7-t ‘C t-80 to -IO0 4 r. Parts must be thoroughly clean and dry. Inert gases argon and helium talthough eupsnsivet and nitrogen. \vith dew points of less than -54 “C t-65 ‘Ft. can be used. They lack the reducing effect of hydrogen. so slight discoloration in the fomt of chrome oxide can result. Salt, exothernit. or cndothemic atmospheres are satisfactory for nonbright annealing. Salt is difficult to remove. and rinse quenching at 595 ‘C (I IO5 “F) is not recommended. hecause interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothrmtic atmospheres must be carefully controlled at equi\ alent carbon potential to avoid carhurization. which will

734 / Heat Treaters

Guide

seriously lower corrosion resistance. Same problem with atmosphere annealing If oxidizing conditions are present, scale will form. Difficult to remove in subsequent descaling operations. Cool rapidly from annealing temperature; no more than 3 min to black color. Section size determines quenching medium: water for heavy sections. air blast for intermediate sizes, and still air for thin sections. Carbides can precipitate at grain boundaries when parts are cooled too slowly between 425 to 900 “C (795 to I650 ‘%). In aerospace practice. parts are annealed at a set temperature of 1065 “C (1950 “F, and q uenched in water with one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineering organization is required for annealing material in a strain-hardened condition, such as t/J hard; for stress relieving; or for dimensional stabilization. Heat treating or slow cooling unstabilized grades between 470 to 8 IS ‘C (875 to IS00 “F, is prohibited. except for 304L and 3 l6L Stress RelieVing. Parts can be relieved after quenching to achieve dimensional stability, by heating to 230 to 300 “C (445 to 750 “F, for up to several hours, depending on section size and without change in metallographic structure. In aerospace practice, parts are stress relieved at 900 “C ( 1650 ?). and quenched in water. As an alternative, parts may be stress relieved at annealing temperatures. Sections under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition, such as t/2 hard, shall not be stress relieved without permission of the cognizant engineering authority. When stress relieving after welding, hold for 30 mitt minimum at the stress relieving temperature. Heat treating or slow cooling of unstabilized grades between 470 to 8 IS ‘C (875 to 1500 %) is prohibited, except for 304L and 3 I6L. See table for soaking times

304: Microstructures.

Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0.127 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nittided, parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers should be replaced with radii of not less than I .59 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion, must be removed prior to nitriding. Accomplished by wet blasting. pickling, chemical reduction in reducing atmosphere. submersion in molten salt. or hy one of several proprietary processes. If doubt exists that complete and uniform depassivation has occurred, further reduction of the oxide may he accomplished in furnace by means of reducing hydrogen atmosphere or suitahle proprietary agent. After depassivation, avoid contamination of surface by finger or hand marking. Single-stage nitriding adequate at 525 to 550 ‘C (975 to 1020 “n for 20 to 48 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case extending to 0.127 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness, at approximately 0. I65 mm (0.0065 in.)

Recommended l l l l l l

Processing

Cold work AMeal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride (if required)

Sequence

(if required)

(a) HNO,-acetic-HCI-glycerol, 250x. Strip. Annealed 5 min at 1065 “C (1950 “F). Cooled in air. Equiaxed austenite grains and annealing twins. (b) Electrolytic: 10% oxalic acid, 100x. Forging. Annealed at 1065 “C (1950 OF), 1 h. Quenched in water. Irregular austenite grains. Etch pits at dispersed carbide particles. (c) Electrolytic: HNO,-acetic, then 10% oxalic acid, 100x. Strip. Annealed 2 min at 1065 “C (1950 OF). Air cooled. Equiaxed austenite grains (ASTM No. 8) annealing twins, small stringer inclusions. (d) Electrolytic: 10% oxalic acid, 500x. Strip. Annealed at 1040 “C (1905 “F). Sensitized by reheating at 650 “C (1200 OF), 1 h. Carbide precipitation at grain boundaties and at twin boundaries. (e) Boiling Murakami’s reagent, 500x. Plate with 0.062 carbon content. Annealed for carbide agglomeration by being held at 1065 “C (1950 “F), 1 h. Sensitized by cooling to 600 “C (1475 “F) and held at temperature, 100 h. Water quenched. Precipitation of chromium carbide at austenite grain boundaries

Austenitic 304:

Soaking

Times (Aerospace

Diameter or thickness(a) of maximum section mm (in.) inclusive

upt02.50~0.100~ over 2.50 to 6 25 (0. IOU to 0.2S01 o\er 6.15 to 12.50 (0.250 to 0.500) o\er 12.50 to 25.00 (O.SOO to I .OO) over 3.00 to 37.50 I I.00 to I.SO) orer 37.50 to 50.00 ( I .so to 2.00, merS0.00 to62.SOC?.OO to 250) over62.50 to 75.00(2.50 to 3.00) o~er75.00(3.00)

Practice)

304: Precipitation

Minimum soaking time Atmosphere furnace Salt bath min min 20 2s -Is 60 75 90 10s 120 tb)

17 18 3s 10 4s SO 5.5 60 Ic)

(a) Thte);nejs is minimum dimension of heaviest section of part or nested load of par& (b)225hplus ISminforevery 12.5mm(O.Sin.)orincrementof 12.SmmtO.Sin.)o~er 75 mmI3in.).(c) I h.SminplusS min foretery I2 5 mm(0.S in.)ormcrementof 12.5 to.5 in.bover75 mm(3 in.). Source: AhlS 2759/A

Stainless

Steels / 735

Diagram. Composition: 0.05 C. 1.73 Mn, 0.60 Si. 0.026 P. 0.012 S, 9.0 Ni, 18.7 Cr, 0.026 N. Solution treated at 1050 “C (1920 “F) for 30 min, water quenched, aged at 600 to 800 “C (1110 to 1470 “F) for up to 50,000 h

Austenitic

Stainless Steels / 735

304H Chemical Composition.

~rsr/uNS

(S30.409): 0.03 10 0. I 0 C. LOO

Mn. 0.035 P, 0.03 S. 1.00 Si. 8.0 to IO.5 Ni. 18.0 IO 20.0 Cr

Recommended Heat Treating Annealing. ln aerospace practice, parts

Practice

are annealed at a set temperature of 1065 ‘C (1950 OF) and quenched in water with one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineering organization is required for annealing material in a strain-hardened condition. such as ‘1~ hard; for stress relieving: or for dimensional stabilization. Heat treating or slow cooling unstabilized grades between 470 to 8 IS “C (875 to IS00 “n is prohibited, except for 30-&L and 316L Stress RdieVing. In aerospace practice, parts are stress relieved at 900 “C ( 1650 %). and quenched in water. As an alternative, parts may be stress relieved at annealing temperatures. Sections under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition, such as l/r, hard. shall not be stress relieved without permission of the cognizant engineering authority. When stress relieving after welding, hold for 30 min minimum at the stress relieving temperature. Heat treating or slow cooling of unstabilized grades between

470 to 815 ‘C (875 to 1500 “F) is prohibited. See table for soaking times

304H:

except for 304L and 316L.

Soaking Times (Aerospace Practice)

Diameter or thickness(a) of maximum section mm (in.) inclusive “pl02.50~0.100) o~er2.~0to6.2~~O.I~X)to0.250~ over 6.25 IO lr!.SO (0.30 IO 0 500) ow 12.50 to 25.00 10.500 w I.001 o\erl500to37.SOtl.00to 1.50, over 37.50 to 50.00 ( I.50 to 2.00’ o\~erSO.W to62 SO 12.00 to 2.50) o~er67.SOto7S.(X)(‘.50103.(H), 0ver7.5.00~3.00~

Minimum Atmosphere furnace min 20 25 15 60 7s 90 IO.5 110 rbj

soaking

time Salt batb min 17 18 35 40 35 SO 55 60 (C)

(3) Thickness is minimum dimension of heat iest section of part or nested load of parts. ib,2.15 hplus 15minforckery 12.SmmtO.Sin.~orincrementof 12.5mm(O.Sio.)over 75 mm 13 in.). IC‘) I h. SmmplusS minforetery 12.5 mtn(O.5 in.)orincrementof 12.5 (0 5 m.)over75 mm 13 in.1 Source: 4hlS 27591-l

Austenitic

Stainless Steels / 735

304L Chemical Composition.

AISI/UN.S (S30403):0.03 C, 2.00 hln.

0.045 P. 0.030 S. I .OO Si. 8.0 to 12.0 Ni. 18.0 to 20.0 Cr

Similar Steels (U.S. and/or Foreign). SA 182, SA2 13, SA240. SA239. A 167. A 182, A2 13. A2-lO. A249. A379, A5 I I, A554, A580. A632 SPEC MB/S-862, MlL-S-23195. fGer.) DIN I .4306; (Ital.) LINI X

AMS 5s I I, 5647: ASME SA3 12, SA403, SA479. SA688; ASThl A276. A3 12, A3 14. A403. A473. A478. A688: FED QQ-S-763. QQ-S-766; hlIL MlL-S-23196; SAE 5405 (3030-t L): 2 CrNi I8 I I. X 3 CrNi I8 I I. X 2 CrNi

18 I I KG. X 2 CrNi 18 1 I KW: (Jap.) JIS SLIS 30-t L. SCS 19; (Swed.) SSt.r2352;(U.K.)B.S.30-tS I2.3O-tS I-t.304S22.S536

Characteristics. Extra low-carbon version of type 304 for restriction of carbide precipitation during melding. Ranks between stabilized and unstabilized grades. because of tendency IO precipitate chromium carbides, Used extensively for welding applications, particularly on parts which cannot be subsequently annealed. Parts are limited to service up to 425 ‘C (795 %). Hardenable by cold mark only. Heat treating limited to: annealing to restore maximum corrosion resistance, softness. and ductility after cold

736 / Heat Treaters Guide \iorking: stress rslieb ing mhen required for stresses occurring from irater quench. when this rapid quench is necessar!,: and on rare occasion. nitriding to imparl thin. hear-resistant surfac?

Forging. after forging

Srart forging at I 1SO to I260 “C t2 IO0 to 3300 “F). Do nor forge stock drops helow 93 “C t 1695 “F,

Recommended Heat Treating Normalizing. Do not normalize Annealing. Anneal at IO IO to I IX “C

Practice

I I850 to 2050 “F). For m&ximum duclility. use a minimum annealinp temperature of 1040°C ( I905 9). Parts can be air cooled from annealing temperature. M’ater quenching not necess;LT\. At 8 IS to -13 “C ( 1500 to 795 V). slo\r cooling can occur for up to 2 h without subsequent danger of suscsptihilit> to intergranular corrosion in natural atmosphenc em ironmsnts. Houe\er. for some applications in the chemical indush, intergranular corrosion uould result from this treatment In aerospace practice. parts are annealed at a bet temperature of 1065 ‘C ( 1950 9) and quenched in water u ith one exception: parts under 2.5 mm (0. IO in.) thick ma! be air cooled or polj mer quenched to minimize distortion. See table for soakin! times. Note: approval of the cognizant engineering organization is required for annealing material in a strain-hardened condition. such as t/j hard; for stress rrlking: or for dimensional stabilization. Heat treating or slow cooling unstabilized grade\ bet\iesn 170 to 8 IS “C (875 to IS00 “F) is prohibited. except for 304L and 3 IhL

Stress

Relieving. Parts can be relieved after quenching to achieve dmiensional stahilitj, by heating IL) 230 to 100 “C (US to 750 %) for up to several hours, depending on section >ix and without change in metnllographic structure. In aerospace practice. part> are stress relieved at 900 ‘C t 1650 ‘?). and quenched in water. As an altematiie. p&arts ma> be stress relked at annealing temperatures. Sectlons under 2.5 mm (0. IO in.) thick may be ;ilr cooled to minimize distortion. Parts fabricated from steel in the strain-hard-

encd condition. such as I!‘? hard, shall not he stress relieved without permission of the cognizant engineering authority. When stress relieving after ! impairs corrosion resistance in most media. Case seldom more than 0.127 mm (0.005 in.) deep. Only used in specialized applications where material mubt be nonmagnetic and have wear-resistant surface. If nitrided. parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers should be replaced m ith radii of not less than I .SY mm (0.06 in.). Film of pnmtily chromium oxide. that protects stainless allo! s from oxidation and corrosion. must be removed prior to nitriding. Accomplished by \\et blasting, pickling. chemical reduction in reducing atmosphere. submersion in molten salt. or by one of several proprietar) processes. If doubt exists that complete and uniform depassivation has occurred. further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietar) agent. After depassivation. avoid contamination of surface bv finger or hand marking. Single-stage nitriding adequate at 575 to 550 “C (975 to 1010 ‘%) for 20 to 18 h (depending on case depth required,. Dissociation rates for single-stage c>;cle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surtace. 18-h cycle produces case extending to 0. I27 mm to.005 in. t with approximatel) 800

S30430:

Recommended

Processing

Cold work Anneal and quench Remove surface contamination Stress relieve Depassi\ate (if nitriding) Nitride iif required)

Soaking

Sequence

(if required)

Times (Aerospace

Diameter or thickness(a) nfmatimum section mm (in.) inclusive

mer 2.50 ~~6.3 ~0.100 toU.Xb over 6 25 lo 12.50 (0.250 IO 0.5001 01s~ I I.50 to 25 00 (0.500 to I .OO) o\er ?5.(JO10 37.50( I .OOto 1.5Oj o\er 3750 to 5O.OOt I SO102 001 o\cr5000~o62.SOr2.0(1to2.~0) o\er6~.50to71i.00t2.SOto 3 00, o\er7s OOf3 00,

Practice)

hlinimum Atmosphere furnace min 20 ‘5 -15

60 75 90 IO5 I10 ib,

soaking

time Salt bath min

17 I8 35 10 4s so 55 60 (Cb

~a) Thickness 15minimum dlmrnsion of hea! lest section of part or nested load of parts. tbj2.35 hplus ISmin forever) Il.5 mm(O.5 in.,orincrementof 12.Snun(O.S in.)over 7.5mm13 in j.(c) I h. 5 minplus5 min foretey I2 5 nunt0.S in.)orincremrntof 12.5 t0.S in 1over 75 mm I3 in.) Source, 4hlS 27S9U

Austenitis

Steels / 737

304LN Chemical

Composition.

AISI/UNS

(S30453):

O.O? C.

X0

hln.

0.045 P, 0.03 S. I .OO Si. 8.0 to 17.0 Ni. 18.0 to X.1) Cr. 0. IO to 0.16 N

Recommended Annealing.

Heat Treating

Practice

parts are annealed at a set temperature of 1065 “C (19.50 “F) and quenched in water u,ith one exception: Parts under 7.S mm (0.10 in.) thick ma) he air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineering organization is required for annealing material in a strain-hardened condition. such as bj hard: fbr stress rclkvinp: or for dimensional stabilization. Heat treating or slou cooling unstahilizcd grades between 370 to 8 IS “C (875 to IS00 “F) is prohibited. except for M-IL and 316L In aerospace

-170 to 8 I5 ‘C 1875 to I500 “F) is prohihitcd, Se2 table for sonKing times

304LN:

Soaking

Times (Aerospace

except for 304L and 3 l6L.

Practice)

practice.

StrSSS Relieving. Ln aerospace practice. parts are stress relked at 900 “C (1650 9). and quenched in eater. As an ahematite. parts ma\ he stress relieved at annealing temperatures. Sections under 2.5 mm (0. Idin.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as % hard. shall not he stress relieved without permission of the cognizant e@ineeting authority. When stress relieving after welding. hold for 30 min minimum at the stress relies ing temperature. Heat treating or slow cooling of unstabilized -grades het\\een

Diameter or thickness(a) of maximum section mm (in.) inclusive up to 2 solo.loo, o\~r2..5Oto6.‘5ttJ.l001oO2ri01 oter 6.25 to 12.50 (0.250 to 0.500) over 1250 to 25.00 10.500 to I .OO) 01 er 25 00 to 37 SO I I 00 to I .5(J) o\er 37.50 to SO OOt I SO to 2 00, o\ cr 50.00 to 6, 50 t2.00 IO 2.50, o\cr6~.50to7tr.(X)1~..‘10to 3 00) o\rr75OOt?OO1

Minimum Atmosphere furnace min 20 25 45 60 75 90 IO5 I70 tb,

soaking

time Salt bath min 17 18 35 10 1s so 55 60 (21

I~I Thickncs IS minimum dimcnGon of hru\ irst sxtion of part or nested load of parts tbrZ.3hplusl5mmiore\q I3mmt0..‘,in.~orinsrementof13nmi10..5in.)over 7Smmt!m.L~s~Ih.Sminplus5niinforr~e~ 1~.5mmt0.5in.~orincrementof17.5 10.5 tn 1o\rr75 mm,3 in I Source. AhlS 2759/-l

304N Chemical

Composition.

AlSl/UNS

(S30451):

0.08

C nl;Lx.

2.00

hln max, 0.045 P max. 0.030 S max. I .OO Si max. 8.00 to 1050 Ni. 18.00 1o20.OOCr.O.IOto0.l6N

Similar Steels (U.S. and/or Foreign). ASME SA 182. SA2 13. SA2-40, SA249, SA312. SA358. SA376. SA130. SA479: ASTM Al82 A2 13. AXO. A249. A3 I’. A358. A376. A-tO3. A-130. A479 Characteristics.

Contains added nitrogen to increase strength with minimum effect on ductility and corrosion resistance. Type 304N is nonmagnetic when annealed. More resistant to increased magnetic pemteability on cold working than type 30-l

Forging. Start forging at I IS0 to 126O’C (2 100 to 23000Fj. Do not forge after forging stock drops below 925 “C ( 1695 %). Cool to black color %I less than 3 min. using liquid quench if necessary

Recommended Normalizing.

Heat Treating

Practice

Do not normalize

Annealing. Anneal at IO IO IO I I20 “C ( I850 to 2050 ‘vj. For maximum ductility and softness. use minimum annealing temperature of 1040 ‘C (I905 ‘%). To guard against distortion of thin, delicate parts, leave ample room for expansion between parts. Stninless grades expand about twice as much as carbon and low-alloy steels. Allow enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conductivity of carbon and low-alloy steels. Choice of atmosphere depends on finish desired and whether surface stock will be removed. For bright annealing. use vacuum or an atmosphere of hydra en or dissociated ammonia at dew point of -62 to -7-l “C (-80 to -100 4 j. Parts must be thoroughly clean and dry. inert gases argon and helium (although expensive) and nitrogen. with dew points of less than -5-l “C (-65 9). can be used. They lack the reducing effect of hydrogen. so slight discoloration in the foml of chrome oxide can result. Sah, exothermic. or endothemuc atmospheres are satisfactory for nonbright annealing. Salt is difftcult to remove. and rinse quenching at 595 ‘C ( I IO5 “n is not recommended. because interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothemuc atmospheres must be carefully controlled at equivalent carbon potential to avoid carburizatton. which will seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present. scale will fomt. Difftcult to remove in subsequent descaling operations. Cool rapidly from annealing temperature: no more than 3 min IO black color. Section size detemines quenching medium: water for heavy sections. air blast for intermediate sizes, and still air for thin sections. Carbides can precipitate at grain boundaries u hen parts are cooled too slowly between 125 to 900 “C (795 IO 1650 TJ. In aerospace practice. parts are annealed at a set temperature of 1065 “C t 1950 “Fj and quenched in water with one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineering organization is required for annealing material in a strain-hardened condition. such as !$ hard: for stress relieving: or for dimensional stabilization. Heat treating or slow cooling unstabilized grades between 170 to 8 IS ‘C (875 to IS00 “Fj is prohibncd. except for 304L and 3 l6L Stress Relieving. Parts can be relieved after quenching to achieve dimensional stability. by heating to 230 to 400 “C (US to 7SO % for up to several hours. depending on section stze and without change m mettalloprnphic structure. In aerospace practice. parts are stress relieved at 900 “C ( I650 @F). and quenched in water. As an alternative. parts may be stress relieved at

annealing temperatures. Sections under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as I/;, hard. shall not be sttess relieved without permission of the cognizant engineering authority. When stress relieving after welding. hold for 30 mitt minimum at the stress relieving temperature. Heat treating or slow cooling of unstabilized grades between 470 IO 815 “C (875 to IS00 %j is prohibited. except for 304L and 3 I6L. See table for soaking times

Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided, parts must be in annealed condition to prevent flaking or blistering of nitrided case. AU sharpcomers should be replaced with radii of not less than I.59 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion. must be removed prior to nitriding. Accomplished by wet blastmg, pickling. chemical reduction in reducing atmosphere. submersion in molten salt. or by one of several proprietary processes. If doubt exists that complete and uniform depassivation has occurred. further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation, avoid contamination of surface bv finger or hand marking. Single-stage nitriding adequate at 52.5 IO 550 *C (975 to 1020 ?j for 20 to 18 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case extending to 0. I27 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness. at approximately 0. I65 mm (0.0065 in. j

Recommended

Processing

Cold work AMeal and quench Remove surface contamination Stress relieve Depasstvate (if nitridingj Nitride (if required,

304N:

Soaking

50roh.3tO

colo62.so~2

l00l00.301

0010

Practice)

Minimum Atmosphere furnace mio

over 6.25 IO 12.50 (0.250 to 0.500) over 12.50 IO 25.00 (0.500 LO 1.001 o\er 2s.00 IO 37.90 ( I al IO I.50, o~rr37.5010 jO.OOt I .5010XO~ over50

(if required)

Times (Aerospace

Diameter or thickness(a) of masimum section mm (in.) inclusive

o\er2

Sequence

2.50)

o\erh?.SO IO 75.00 I 2 SO IO 3.00, "\rr7s.oo~3.ool

20 25 -Is 60 7s 90 I OS I20 (b)

soaking

time Salt batb mio I7 18 35 40 45 SO 5s 60 CC)

tajThicl\ness is minilnumdimcnsionofhra\ic~tsestionofp~ornested toadofparts. Ibj? 15 hplus l~nunfore~cry l~.SrnmtO.Zin jorincremenrof 12.5mm(0.5in.)ober 75 nun (3 in I. (sr I h , 5 min plus 5 min for e\er) I2.S mm (0.5 in.)or increment to.5 in Joker 75 mm (3 In.). Source. .AhlS 2759/J

of 11.5

Austenitic

Stainless

Steels I739

305 Chemical Mnmax.0.045 to 19.00 Cr

Composition.

AISI/UNS (S30500): 0.12 C max. 2.00

Pmax.0.030Smax.

l.OOSi max. 10.50 to 13.OONi. 17.00

Similar

Steels (U.S. and/or Foreign). AMS 5s 11, 5685. 5686: ASME SA 193. SAl94. SA240; ASTM A 167. A240. A2-19. A276. A3 13. A314, A368. A-l73. A478. A493, A51 I, A554 A580; FED QQ-S-763. QQ-W-423; SAE J-MIS (30305); (Ger.) DIN 1.4303; (Ital.) UNI X 8 CrNi I9 IO: (Jap.) JIS SUS 305. SDS Jl Characteristics. This austenitic chromium-nickel steel has lower rate of work hardening than types 302 and 304. Less change of magnetic permeability. Used for spinning, special drawing, and cold heading applications Forging. Start forging at I I50 to I260 “C (2 100 to 2300 9). Do not forge after forging stock drops below 925 ‘C ( 1695 “n. Cool to black color in less than 3 mm. using liquid quench if necessary

Recommended Normalizing.

Heat Treating

Practice

Do not normalize

Annealing.

AMed at 1010 to I I20 “C ( I850 to 2050 OF). For maximum ductili and softness. use a minimum annealing temperature of 1010 ‘C (1905 % To guard against distortion of thin, delicate parts, leave ample room for expansion between parts. Stainless grades expand about twice as much as carbon and low-alloy steels. Allow enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conductivity of carbon and low-alloy steels. Choice of atmosphere depends on finish desired and whether surface stock will be removed. For bright annealing. use vacuum or an atmosphere of hydro en or dissociated ammoma at dew point of -62 to -74 ‘C (-80 to -100 %R Parts must be thoroughly clean and dry. Inert gases argon and helium (although expensive) and nitrogen. with dew points of less than -54 ‘C (-65 ‘%). can be used. They lack the reducing effect of hydrogen. so slight discoloration in the form of chrome oxide can result. Salt. exothermic. or endothermic atmospheres are satisfactory for nonbright annealing. Salt is difficult to remove. and rinse quenching at 595 “C (I I05 %) is not recommended, because interrupted quench at elevated temperature cannot be tolerated. Exotherrnic and endothermic atmospheres must be carefully controlled at equivalent carbon potential to avoid carburization. which will seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present. scale will form Difftcult to remove in subsequent descaling operations. Cool rapidly from annealing temperature: no more than 3 mm to black color. Section size determines quenching medium: water for heavy sections. air blast for intermediate sizes. and still air for thin sections. Carbides can precipitate at grain boundaries when parts are cooled too slowly between 425 to 900 ‘C (795 to 1650 %). In aerospace practice, parts are annealed at a set temperature of 1065 “C ( 1950 ?r) and quenched in water with one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineering organization is required for annealing material in a strain-hardened condition, such as t/d hard: for stress relieving; or for dimensional stabilization. Heat treating or slow cooling unstabilized grades between 470 to 8 I5 “C (875 to 1500 “F, is prohibited. except for 304L and 3 I6L

Stress Relk?ViIlg. Parts can be relieved after quenching to achieve dimensional stability, by heating to 230 to -400 ‘C (US to 750 ‘%>F)for up to severaJ hours, depending on section size and without change in metallographic StrucNre.

In aerospace practice. parts are stress relieved at 900 ‘C (1650 %). and quenched in water. As an alternative. parts may be stress relieved at annealing temperatures. Sections under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as t/z hard. shall not be stress relieved without pemlission of the cognizant engineering authority. When stress relieving after welding. hold for 30 min mtninumi at the stress relieving temperaNre. Heat treating or slow cooling of unstabilized grades between 470 to 8 I5 “C (875 to IS00 OF) is prohibited. except for 301L and 316L. See table for soaking limes

Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided, parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers should be replaced with radii of not less than I .59 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion. must be removed prior to nitriding. Accomplished by wet blasting. pickling. chemical reduction in reducing atmosphere, submersion in molten salt. or by one of several proprietary processes. If doubt exists that complete and umform depassb ation has occurred. further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation. avoid contamination of surface b2 finger or hand marking. Single-stage nitriding adequate at 525 to 550 C (975 to 1020 9) for 20 to 48 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case extending to 0. I37 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 200 HR core hardness. at approximately 0. I65 mm (0.0065 in.)

Recommended

Processing

Cold work Anneal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride (if required)

305:

Soaking

Sequence

(if required)

Times (Aerospace

Diameter or thickness(a) of maximum section mm (in.) inclusive up to 2.SOtO 100) over2.50t06.lS(0.100to02501 over 6.25 to 11.50 (0.250 to O.SOO] over 12.50 to 25.00 tO.SOO to 1.00) over 2S.00 to 37.SO t 1.OO to 1.I%J over 37.SO to SO.00 t l .SO 10 2.001 over SO.00 to61.SOi2.00 to I! 501 o\er61.50 to 7S.OOt2 SO to 3.OOt ovcr75.00t3.00~

Practice)

Minimum soaking time Atmosphere furnace Salt bath min min IO 15 15 60 7s 90 105 120 (b)

17 18 3s 40 45 SO 55 60 ICj

(a) Thickness is mimmum dimension of hca\;iest section of part or nested load of parts. tbi 2 2S h pIus IS min forebey 12.5 mm (0.5 in )or increment of 12.5 mm(0.S in.)over 7Stnmt3 in.). ICI I h. 5 minplus5 mm foretery 12.5 mmt0.5 in.)orincrementof 12.5 10.5 in.)o\er 75 mm (3 in.). Source: AhIS 275914

740 / Heat Treaters

Guide

305: Microstructure. Electrolytic: 50% phosphoric acid, 1000x. Creep-rupture specimen. Annealed at 1120 “C (2050 OF), 92 h. Tested at 650 “C (1200 “F), 371 h. Carbon migration and precipitation of chromium carbide (Cr&) at austenite grain boundaries.

740 / Heat Treaters

Guide

308 Chemical

Composition.

0.045 P.O.03OS.

Similar

l.OOSi.

AIsI/UNS (S30800): 0.08 C. 2.00 hln.

lO.Oto

Steels (U.S. and/or

I?.ONi.

19.00to~1.00Cr

Foreign).

A314 A473. AS80: SAJZ JWS (30308~: Ger.) CrNi 19 IO: IJap.) JIS SLlS 305. SllS 305 J I

ASTM ~167. ~276. DlN 1.4303: (TtaJ.) CrNl X 8

Characteristics.

Corrosion and heat resistance superior to t!pe 30-l. lked for welding hire. Nonmagnetic when annealed. Slightly magnetic when cold worked

Forging. Start forging at I IS0 to 1260°C (2 100 to 2300°F~. Do not forge after forging stock drops below 975 “C t 1695 ‘?). Cool to black color in less than 3 min. using liquid quench if necess?

Recommended Normalizing.

Heat Treating

Practice

Do not normalize

Annealing. Anneal at 1010 to I I20 “C t I850 to 2050 ?). For maximum ductilitb and softness. use a minimum annealing temperature of IWO “C (190s %). To guard agamst distortion of thin, delicate parts. lea\e ample room for expansion between parts. Stainless grades espand about twice as much as carbon and low-alloy steels. Alloy enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conductivit> of carbon and low-allo> steels. Choice of atmosphere depends on finish desired and whether surface stock will be removed. For bright annealing. use vacuum or an atmosphere of hydra en or dissociated ammonia at de\\ point of -62 to -74 “C t-80 to -100 4 ). Parts must be thoroughI> clean and dq. Inert gases argon and helium (although expensive) and nitrogen. u ith dew points of less than -5-l “C t-65 ?F). can be used. The) lack. the reducing effect of hydrogen. so slight discoloration m the form of chrome oxide can result. Salt. exothsrnlic. or endothermic atmospheres are satisfactory for nonbright annealing. Salt is diflicult to remove. and rinse quenching at 595 ‘C ( I IO5 9) ih not recommended. because interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothermic atmospheres must be carefull) controlled at equivalent carbon potential to avoid carburizatlon. which nil1 seriously lower corrosion resistance. Same problem u ith atmosphere annealing. If oxidizing conditions are present. scale will form. Difficult to remove in subsequent descaling operations. Cool rapidI> from annealing temperature: no more than 3 min to black color. Section size detemlines quenching medium: water for heav! sec-

tions. air blast for intermediate sizes. and still air for thin sections. Carbides can precipitate at grain boundaries &hen parts are cooled too slowly between 425 to 900LoC (795 to 1650 “F). In aerospace practice, parts are annealed at a set temperature of 1065 “C t 1950 ‘>FJ and quenched in Uater with one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineering organization is required for annealing material in a strain-hardened condition. such as I/, hard: for stress relieving; or for dimensional stabilization. Heat treating or slow cooling unstabilized grades between 470 to 8 IS ‘C 1875 to I SO0 9) is prohibited. except for 304L and 3 l6L Stress RelieVing. Parts can be relieved after quenching to achieve dimensional stability. b> heating to 230 to 400 “C (US to 750 ‘%) for up to several hours. depending on section size and without change in metallographic structure. In aerospace practice, parts are stress relic\ ed at 900 “C ( I6SO %), and quenched in Water. As an alternative, parts may be stress relieved at annealing temperatures. Sections under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as t/z hard. shall not be stress relieved without permission of the cognizant engineering authority. When stress relieving after welding, hold for 30 min minimum at the stress relieving temperature. Heat treating or slo\\ cooling of unstabilized grades between 170 to 815 “C (875 to IS00 ?) is prohibited. escept for 304L and 316L. See table for soaking times

Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications H here material must be nonmagnetic and ha\e wear-resistant surface. If nitrided. parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers should be replaced n ith radii of not less than I .S9 mm (0.06 in.). Film of primaril) chromium oside. that protects stainless alloys from oxidation and corrosion. must be removed prior to nitridinp. Accomplished by wet blasting. pickling. chemical reduction in reducing atmosphere. submersion in molten salt. or b! -one of several proprietary processes. If doubt exists that complete and umk~rm depassi\ation has occurred. further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable propriety agent. After depassivation. avoid contamination of 3urface bj finger or hand marking. Single-stage nitriding adequate at 525 to 550 “C 1975 to 1020 OF) for 10 to -48 h (depending on

Austenitic

case depth required). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 18-h cycle produces case extending to 0. I27 mm (0.005 in. t with approstmatel! 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness. at approximately 0. I65 mm tO.0065 in.)

Recommended

Processing

Cold hark Anneal and quench Remove surface contamination Stress relieve Depassibate (if nitriding) Nitride (if required)

Sequence

t if required)

308:

Soaking

Times (Aerospace

Diameter or thickness(a) of maximum section mm (in.) inclusive up tll2.50t0.1001 o\er2.S0to6’StO.lM3to(J.75[1) over 6.25 to 12.50 (0.250 to 0.5001 over I2 50 to 25.00 10 500 to I.001 ovrr7S.00 to 37.SOt I CO to 1.50’1 o~~r37.50to50.00t1.50t~~.~i 1~ er SO.00 to 62 SO I 2.00 to 2.SO) 0~er6~.90to75.00t2.9(1t03.00) o\er7S.tMt?.OO)

Stainless

Steels / 741

Practice)

Minimum soaking time Atmosphere furnace Salt bath min min ‘0 25 -1s 60 7S 90 IO5 120 tb)

17 18 35 -IO 15 50 55 60 (c)

(a) Thickness is minimum dimension of hea\ iest section ofpart or nested load of parts. lb) 2.3 hplus IS min foreveq 12.5 mm to.5 in.~orincrementof 12.5 mm(0.S in.)over 75 mm t3 in.). (5) I h. 5 mm plus 5 min forever! I33 mm (0.5 in.)orincrement of 12.5 10.5 in.) o\er 75 mm t 3 in.). Source. AhlS 2759/-l

Austenitic

Stainless

Steels / 741

309 Chemical Composition. AISIjUNS (S3OWO): 0.20 C. XXI 0.045 P. 0.030 S. 1.00 Si max. 13.0 to IS.0 Ni. 2.0 10 Z-l.0 Cr

hln.

Similar

Steels (U.S. and/or Foreign). AWE .%X9. SA3 12. SA358. SAA03. SA-IO9; ASThl A167, A319. A776. 4312, A31-1. A358. A-lO3. AJ09. AA73. AS I I. ASS-I, AS80: FED QQ-S-763. QQ-S-766: MfL SPEC MfL-S-867: SAE J-IO5 (30309); (Ger.) DIN 1.4828; (Ital.) IJNI X I6 CrNi 23 I-l Characteristics.

High heal resisting

qualities.

Used for welding

wire

applications

Forging.

Start forging at I IS0 to I230 “C (2 100 to 32-15 OF). Finish forging at 980 LO 1010 ‘C ( I795 to I850 ‘T). Cool to black color in less than 3 min. using liquid quench if necess+

Recommended Normalizing.

Heat Treating

Practice

Do not normalize

Annealing. AMeti at 1030 to I I20 ‘C ( 1905 to 2050 %). To guard against distortion of thin. delicate parts. Iea\e ample room for expansion between parts. Stainless grades expand about IW ice as much as carbon and low-alloy steels. Allow enough time for through heating afterthermocouple has reached temperature Stainless grades have appro\imnrel) half the thermal conductivity of carbon and low-alloy steels. Choice of amiosphere depends on finish desired and whether surf&e stock will be remoled. For bright annealing use vacuum or an atmosphere of hydrogen or dissociated ammonia at dew point of -62 to -7-l “C i-80 to -100 %I. Parts must be thoroughly clean and dry. Inert gases argon and helium (although expensive) and nitrogen. with dew points of less than -53 “C C-65 @F). can be used. They lack the reducing effect of hydrogen. so slight discoloration in the form of chrome oxide can result. Salt. exothermic. or endothemtic atmospheres are satisfactory for nonbright annealing. Salt IS difficult to remobe, and rinse quenching at 595 “C (I IO5 c”F) is not recommended. because interrupted quench at elevated temperature cannot be tolerated. Exolhermic and endothermic atmospheres must be carefully controlled at equivalent carbon potential to avoid carburizarion. which will seriously lower corrosion resistance. Same problem with amiosphere annealing. If oxidizing conditions are present. scale will form. Difficult to remove in subsequent descaling operations. Cool rapidly from annealing temperature: no more than 3 min to black color. Section size determines quenching medium: enter for heavy sections. air blast for intermediate sizes. and still air for thin sections. Carbides

can precipitate a~ grain boundaries when parts are cooled too slowly between 25 to 900 ‘C (795 to I650 9). In aerospace practice. parts are annealed at a se1 temperature of 1065 “C ( 19.50 % and quenched in \\ater \< ith one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineenng organization is required for annealing material in a strain-hardened condition. such as ‘14 hard: for stress relieving; or for dimensional stabilization. Heat treating or slow cooling unstabilized grades between 470 IO 815 ‘C (875 IO IS00 %‘I is prohibited. except for 303Land 316L Stress RelieVing. Parts can be relieved after quenching 10 achieve dimensional stability, bb heating IO 230 to -IO0 ‘C (US 10 750 %) for up to several hours. depending on section size and without change in metallographic structure. In aerospace practice. parts are stress relicvsd at 900 ‘C ( 1650?). and quenched in Mater. As an alternative. parts may be stress relieved at annealing temperatures. Sections under 1.5 mm (0. IO in.) thick may be air cooled to mininlize distortion. Parts fabricated from steel in the strain-hardened condition. such as !/2 hard. shall not be stress relieved without permission of the cognizant engineering authority. When stress relieving after welding. hold for 30 min minimum al the stress relieving temperature. Hear treating or slow coolin! of unstabilized grades between 470 to 815 ‘C (875 IO 1500 OF) is prohiblted. ehcepr for JO-IL and 316L. See table for soakins times

Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. OnI! used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided. parts must be in annealed condition 10 prevent flaking or blistenng of nitrided case. All sharp comers should be replaced with radii of not less than I .59 mm (0.06 in.). Film of prim‘arily chromium oside. that protscl\ slainless alloys from oxidation and corrosion. must be removed prior 10 nitriding. Accomplished by wet blasting. pickling. chemical reduction in reducing atmosphere. submersion in mohen salt. or bt one of heveral proprietary processes. If doubt exists that complete and umform depassi\ ation has occurred. further reduction of the oxide ma] be accomplished in furnace by means of reducing hydrogen atmosphere or suitable propriclnq agent. After depassivalion. avoid cont,anination of surface by finger or hand marking. Single-stage niuiding adequate at 525 IO 550 “C (975 IO 107-O ?=) for 30 to -IX h (depending on case depth required,. Dis\ocistion rates for single-s&e cycle are from 20 to 3.55. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle

742 / Heat Treaters

Guide

produces case extending to 0.127 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness. at approximately 0. I65 mm (0.0065 in.)

Recommended l l l l l l

Processing

Cold work Anneal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride (if required)

Sequence

(if required)

309:

Soaking

Times (Aerospace

Diameter or thickness(a) of maximum 5ection mm (in.) inclusive upt02.50(0.100) oter 2.SOto6.2S~0.lOOto0.25Oj over 6.25 to 12.50 (0.150 to 0.500) 015r 12 50 to 25 00 IO.500 ~0 I.001 owr 25.00 to 37.50 ( I.00 to I SO) ow 37.50 to 50.00 ( I .SO to 2.00) over 50.00 to 62.50 (2.00 to 250) over62.50to75.00(2.50to3.00) over 75.00(3.00) (a) Thickness (b)2.2Shplus 75 mrn(3 in.) (0.5 in.)over

Practice)

Minimum soaking time Atmosphere furnace Salt bath min min 20 25 15 60 75 90 105 130 (b)

17 18 35 40 45 50 55 60 (d

is minimum dimension of hea\ iest section of part or nested load of parts. ISminfore\ery 12.5mm(0.5in.)orincrementof 12.5mm(O.Sin.)over (5) I h, 5 min plus5 min forevery 12.S rnm(O.5 in.)orincrementof 12.5 75 mm (3 in.) Source: AhlS 275914

742 / Heat Treaters

Guide

309s Chemical COmpOSitiOn. AISIjUNS (S30908): 0.08 C. X0 0.045 P. 0.030 S. 1.00 Si. 12.00 to 15.00 Ni. 22.00 to 24.00 Cr

Mn.

Similar

Steels (U.S. and/or Foreign). AMS 5523. 5573. 5650: ASME SA240; ASTM A 167. A240. A276, A3 I-1. A51 I, A554. A580; SAE J405 (30309 S); (Ger.) DfN 1.4833; (Fr.) AFNOR Z IS CN 21.13; (Ital.) UNI X 6 CrNi 23 I4 Characteristics.

High heat resisting

qualities.

Used for welding

wire

applications

Forging. Start forging at I I20 to 1230 ‘C (2050 to 2245 ‘%). Finish forging at 980 to 1010 ‘C ( 1795 to I850 ‘%). Cool to black color in less than 3 min. using liquid quench if necessary

Recommended Normalizing.

Heat Treating

Practice

DOnot normalize

Annealing. Anneal at 1040 to I I20 “C ( 1905 to 2050 @F). To guard against distortion of thin. delicate parts. leave ample room for expansion between parts. Stainless grades expand about twice as much as carbon and low-alloy steels. Allow enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conductivity of carbon and low-alloy steels. Choice of atmosphere depends on finish desired and whether surface stock will be removed. For bright annealing, use vacuum or an atmosphere of hydrogen or dissociated ammonia at dew point of -62 to -74 ‘C (-80 to -100 OF). Parts must be thoroughly clean and dry. Lnert gases argon and helium (although expensive) and nitrogen. with dew points of less than -5-l ‘C (-65 OF). can be used. They lack the reducing effect of hydrogen. so slight discoloration in the form of chrome oxide can result. Salt. exothermic. or endothermic atmospheres are satisfactory for nonbright annealing. Salt is difticult to remove. and rinse quenching at 595 ‘C (I I05 OF) is not recommended. because interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothermic atmospheres must be carefully controlled at equivalent carbon potential to avoid carburization, which will seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present. scale will form. Difficult to remove in subsequent descaling operations. Cool rapidly from annealing temperature: no more than 3 min to blach color. Section size determines quenching medium: water for heavy sections. air blast for intermediate sizes. and still air for thin secttons. Carbides

can precipitate at grain boundaries when parts are cooled too slowly between -125 to 900 “C (795 to I650 9). In aerospace practice, parts are annealed at a set temperature of 1065 “C (1950 ‘%) and quenched in water w,ith one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineering organization is required for annealing material in a straitt-hardened condition. such as ‘4 hard; for stress relieving; or for dimensional stabilization. Heat treating or slow cooling unstabilized grades between -170 to 8 I5 ‘C (875 to IS00 ‘%) is prohibited. except for 304L and 3 l6L

Stress Relieving. Parts can be relieved after uenchin to achieve dimensional stability. by heating to 230 to 400 “C (34 5 to 7 s 0 “F) for UP to several hours. depending on section size and without change in metallographic structure. In aerospace practice. parts are stress relieved at 900 ‘C (1650 %). and quenched in water. As an alternative, parts may be stress relieved at annealing temperatures. Sections under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition, such as t/z hard. shall not be stress relieved without permission of the cognizant engineering authority. When stress relieving after welding. hold for 30 min minimum at the stress relieving temperature. Heat treating or slow cooling of unstabilized grades between 470 to 815 “C 187.5 to 1500 9) is prohibited. except for 304L and 316L. See table for soaking times Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. if nitrided, parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers should be replaced with radii of not less than I.59 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion, must be removed prior to nitriding. Accomplished by wet blasting, pickling. chemical reduction in reducing atmosphere. submersion in molten salt. or by one of several proprietary processes. If doubt exists that complete and uniform depassivation has occurred. further reduction of the oxide may be accomplished in Furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation, avoid contamination of surface bv finger or hand marking. Single-stage nitriding adequate at 525 to 550 ‘C (975 to 1020 ?) for 20 to 48 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle

produces case extending to 0. I27 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness. at approsimately 0. I65 mm (0.0065 in.)

Recommended l l l l l l

Processing

Cold work Anneal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride (if required)

Sequence

309s:

Soaking

Austenitic

Stainless

Times (Aerospace

Practice)

Diameter or thickness(a) of maximum section mm (in.) inclusive upro3010.100)

(if required)

over 2.50 10 6 25 (0. IO0 to 0.250) o\er 6.25 to 17.50 (0.150 to 0,500) o\er 12 50 to 25.00 (0.500 t0 I .00) 0\er~5.00t037..50~1.0010 1.50) over 3750 to 50.00 I I .50 to xlo, over50.00to62.5Ot~.00to7.50) o\~r62.SOto75.00(7.SOt03.OO) “\er75.00t3.00)

Steels / 743

Minimum soaking time Atmosphere furnace Salt bath min mln ‘0 15 15 60 7s 90 10s 170 (b)

17 I8 35 40 45 50 55 60 W

131 Tbckness ib minimum dimension of hea\ iest secuon of part or nested load of pans. tb) 2 25 h plus IS min forevq II 5 mm(0.S in )orincrementof 12.5 mm(0.S in.)over 75 mm (3 in ). tc) I h. 5 min pluj 5 min for eveq 12.5 mm (0.5 in.)or incremem of 11.5 10.5 in.) over 7S mm t 3 in.). Source: AAIS 2759/-I

Austenitic

Stainless Steels / 743

310 Chemical Composition.

AIsIjUNs

(s31000): 0.25 C. 2.00 Mn.

0.045 P, 0.030 S. I.50 Si. 19.00 to 22.00 Ni. 21.00 to 26.00 Cr

Similar Steels (U.S. and/or Foreign). AhlS 5694. 5695;

ASME SAl82. SA213. SA239. SA312. SA358. SA-103. SA109: ASThl 44167. A 182. AZ-IO. A213. A339. A276. A3 12. A31-1. A358. AA03. A-lO9. A173. AS I I, A632; FED QQ-S-763. QQ-S-766. QQ-W-423, STD-66; MU- SPEC MIL-S-862; SAE 1105 (30310): (Ger.) DIN I.-WI: (Fr., AFNOR Z I2 CNS 25.20; (Ital.) UNI X I6 CrNiSi 25 20. X 22 CrNi 25 20; (Jap.) JIS SUS Y 310: (U.K.) B.S. 310 S 2-l

Characteristics. sion and oxidatton

High heat resistant qualities. plus resistant to corroat high temperatures. Very ductile. Easily irelded

Forging.

Start forging at 1095 to 1130 ‘C (2005 to 22-lS v). Finish forging at 980 to 1010 ‘C ( I795 to I850 OF). Cool to black color in less than 3 min. using liquid quench if neccssq

Recommended Normalizing. Annealing.

Heat Treating

Practice

Do not normalize

Anneal at IO-IO to I I50 “C ( 1905 to 2 100 9) and hold at least t/z h. To guard against distortion of thin. delicate parts, leave ample room for expansion between parts. Stainless grades expand about t\i ice as much as carbon and low-alloy steels. 4110~ enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conductivity ofcarbon and lou-alloy steels. Choice of atmosphere depends on finish desired and I+ hether surface stock uill be removed. For bright annealing. use vacuum or an atmosphere of hydra en or dissociated ammonia at dew point of -62 to -71 “C t-80 to -100 %R Parts must be thoroughly clean and dry. Inert gases argon and helium (although expensive) and nitrogen. with dew points of less than -5-l “C (-65 w, can be used. They lack the reducing effect of hydrogen. so slight discoloration in the form of chrome oxide can result. Salt. exothermic. or endothemuc atmospheres are satisfactory for nonbright annealing Salt is difficult to remove. and rinse quenching at 595 “C (I IO5 9) is not recommended. because interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothermic atmospheres must be carefully controlled at equivalent carbon potential to avoid carbutization. which will seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present, scale will form. Difficult to remove in subsequent descaling operations.

Cool rapidI\ from annealing temperature: no more than 3 min to black color. Section size determines quenching medium: water for heavy sections. air blast for intermediate sizes. and still air for thin sections. Carbides can precipitate at grain boundaries when parts are cooled too slowly betueen -I25 to 900 “C i79S to l6SO %. In aerospace practice. parts are annealed at a set temperature of 1065 “C (I950 ‘%, and quenched in Hater with one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soahing times. Note: approval of the cognizant engineering organization is required for annealing material in a suain-hardened condition. such as ‘15 hard; for stress relieving; or for dimensional stabilization. Heat treating or slow cooling unstabilized grades between -170 to 8 IS ‘C (875 IO IS00 ‘>FJ is prohibited. except for 3OAL and 3 l6L Stress RelieVing. Parts can be relieved after quenching to achieve dimensional stabiliQ. b! heating to 230 to -IO0 “C (-WI to 750 ?) for up to several hours. depending on section size and without change in metallographic structure. In aerospace practice. parts are stress relieved at 900 “C ( I650 ‘%). and quenched in water. As an alternative. parts may be stress relieved at annealing temperatures. Sections under 3.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as % hard. shall not be stress relieved without permission of the cognizan; cneineering authority. When stress relieving after \+elding. hold for 30 min n;inimum at the stress relieving temperature. Heat treating or slo\\ cooling of unstabilized grades between 470 to 8 I5 ‘C (875 to IS00 OFI is prohibited. except for ?ML and 316L. See table for soaking times

Nitriding. Not recommended Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications \h here material must be nonmagnetic and ha\e wear-resistant surface. If nitrided. parts must be in annealed condition to prevent flaking or blistering of nitrided case. ,411sharp comers should be replaced u ith radii of not less than I.59 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion. must be removed prior to nitriding. Accomplished by bet blasting, pickling. chemical reduction in reducing atmosphere, submersion in molten salt. or by-one of several proprietary processes. If doubt exists that complete and umtorm depassivation has occurred. further reduction of the oxide ma! be accomplished in furnace b> means of reducing hydrogen atmosphere or suitable proprietaq agent. After depassivation. avoid contamination of surface b!, Finger or hand marking. Single-stage nitriding

744 / Heat Treaters Guide adequate at 525 IO 550 ‘C (975 to 1020 %F) for 10 IO 48 h (depending on case depth required). Dissociation rates for single-stage cyzls are from 20 to 355. Hardness is as high as 1000 to I350 HK on surface. 43-h cqcls produces case extending to 0. I27 nun tO.005 in.) with approximateI> 800 to 1000 HK. Case uill rapidly drop to 200 HK core hardness. at approximateI> 0. I65 nun t0.006.5 in.)

310:

Recommended

o\rlr2.iOto62StO.l00toO350, wer 6.15 to 12.50 (0.250 to 0.5001 over I1 50 to 25.00 (0 500 to I.001 over 25.00 to 37.50 t I .W to I 50) o\er 37.50 to 5O.Wt I 50 to 2.OOI o\er 50.W to630 12.00 to 2 5Ot otrr62 SO to 75 0012 511to 3.W) o\rr75.Wt3.W)

l l l l l l

Processing

Cold lrork Anneal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride lif rcqutred)

Sequence

(if required)

Soaking Times (Aerospace Practice)

Diameteror thickness(a) of maximum section mm (in.) inclusive upro2.50ff~ 100)

~a) Thiilaesj

hlioimum soaking time Atmosphere furnace Salt batb mitt mia ‘0 25 15 60 75 90 IO5 1x tbr

17 18 35 -lo -Is SO 55 60 (Cl

ISminimutn dimension of heavwtt sectinn of part or nested load of parts. fbrl.25hplui 1Sntinforevr~ I~..immtO5in.~orincrrmmtof12.Snun(O.Sin.~o~er 75mm13in.l.t~) I h..‘,nljnplus5minforr\~~ 13.Smmt0.5in.)orincrementof 12.5 10.5 in joker 75 mm 13 in.). Source. AhlS 275CN-1

744 / Heat Treaters

Guide

310s Chemical

Composition.

~1sIjUNs (S31008): 0.08 c. X0

MI.

0.045 F! 0.030 S. 1.50 Si. 19.00 to 32.00 Ni. 24.00 to 26.00 Cr

Similar Steels (U.S. and/or Foreign). MS WI, 5577. 5577. 5651: ASME SA2-10. SA-179; ASThl Al67. A240. ,X76. Ml-l. A473. A479. A51 I. AM-4

Characteristics.

AS80; SAEJ405

t303lOSj

High heat resistant qualities. plus resistant to corroat high temperatures. C’eq ductile. Easil! welded

sion and oxidation

Forging.

Start forging at 1095 to 1230 ‘:‘C (2005 to 2115 “F). Finish forg,ing at 980 to 1010 “C ( I795 to I850 “FI. Cool to hlnck color in less than 3 nun. using liquid quench if necessag

Recommended Normalizing. Annealing.

Heat Treating

Practice

Do not normalize

Anneal at lo-10 to I I SO “C (’ I905 to 2 IO0 ‘“F) and hold al least !I! h. To guard against distortion of thin. delicate parts. 1eat.e ample room for expansion hetbbeen parts. Statnless grades expand ahout III ice as much as carbon and lo\%-allo, steels. Allow enough time for through heating after thermocouple has reached temperature. Stainless grades hats approximately half the thermal conducti\ ity of carbon and low-allo! steels. Choice of atmosphere depends on finish desired and \chether surface stock will he removed. For bright annealinp. use vacuum or an atmosphere of hydrogen or dissociated ammonia at den point of 42 to -74 “C t-80 to -100 “F). Parts must be thoroughI) clean and dc. Inert gases argon ad helium (although expensive) and nitrogen. with dew points of less than -5-l “C f-65 “F). can he used. The) lack the reducing effect of hydrogen. so slight discoloration in the form of chrome oxide can result. Sah. ewthermic. or endothermic atmospheres are sat&facto9 for nonbright annealing. Salt is difficult IO remove. and rinse quenching a~ 595 “C ( I IO5 “F) is not recommended. because interrupted quench a~ eknted temperature cannot he tolerated. Exothemuc and endothermic atmospheres must he carsfull> controlled a~ equivalent carbon potential to avoid carhuriration. \\ hich will seriousI! lower corrosion resistance. Same prohlem with atmosphere annealing. If oxidizing conditions are present. scale will form. Difficult IO remove in subsequent descalinp operations. Cool rapidly from annealing temperature: no more than 3 tin to blnch color. Section size deremlines quenching medium: iiater for heavy sections. air blast for intermediate sizes. and still air for thin sections. Carhides can precipitate at grain houndaries I\ hen parts are cooled too slowI> between 425 IO 900 “C (795 to I650 “F).

In aerospace practice. parts are annealed at a set temperature of 1065 ‘C (I950 “F) and quenched in \tater \rith one exception: parts under 3.5 mm (0 IO in.) thick may he air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognkant engineerin_e organization is required for annealing material in a strain-hardened condition. such as !‘j hnrd: for stress relieving; or for dimensionti stahilizatton. Heat treating or slow cooling unstabilized grades between 470 to YIS “C (875 to IS00 ‘F) is prohihited. escept for BO4Lsnd 316L Stress l?eh?Ving. Parts can he relieved after quenching to achieve dimensional stability. by heating to 230 to JO0 “C (435 to 750 “F) for up IO se\eral hours. depending on section size. and without change in metallographic structure.

Ln aerospace practice. parts are stress relieved at 900 “C ( I650 “Fj. and quenched in water. As an altsmative. parts may he suess relieved at anrlealing temperatures. Sections under 2.5 mm (0. IO in.) thick may he air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as t/S bard. shall not be stress relieved uithout permission of the cognizant engineering authority. When stress relieving after welding. hold for 30 min minimum at the stress relieving temperature. Heat treating or slow cooling of unstahilired grades between 470 to 815 “C (875 to IS00 “FJ is prohihitsd. except for 304L and 316L. See table for soaking times

Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0.127 mm (0.005 in.) deep. OnI) used in specialized applications where material must he nonmagnetic and have \rrx-resistant surface. If nitrided, parts must be in annealed condition to prevent Flaking or blistering of nitrided cilse. All sharp comers should be replaced u ith radii of not less than I .59 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion, must he removed prior to nitriding. Accomplished by wet blasting. pickling. chemical reduction in reducing atmosphere. suhmersion in molten salt. or hy one of several proprietar) processes. If doubt exists that complete and uniform depassivation has occurred. further reduction of the oxide ma> be accomplished in furnace by means of reducing hydrogen atmosphere or suitable propriety agent. After depassivation. avoid contamination of surface hy finger or hand marking Single-stage nitriding adequate at 525 to 550 “C (975 to 1020 “F) for 20 to 18 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 3%. Hardness is as high as 1000 to 1350 HK on surface. 18-h cycle produces case extending to 0. I37 mm (0 005 in.) with approximately 800

to 1000 HK. Case will rapidly drop to 200 HK core hardness. at approximately 0. I65 mm (0.0065 in.)

Recommended l l l l l l

Processing

Cold work Anneal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride (if required)

Sequence

c’if required)

310s:

Soaking

Austenitic

Stainless

Times (Aerospace

Practice)

Minimum Atmosphere furnace min

Diameter or thickness(a) of ma&mu section mm (in.) inclusive

“\rr’.solo6.2.ilo.l00toO~5o, ok~rfi.3 over

IO 12.50

130~0.30

to 25 00 (0.500

"\er2s.ooto37.s0f

1.00l0

IO

0.500)

to 1.00, 1.50,

0~37.SOto50001 I.SOro2 001 o\er SO.00 1062.50f’OO to 2 501 o~rr67.501o75.00t~.SOto 3.00) 0\er75.00t3.00~

soaking

Steels / 745

time Salt bath min 17 18 3S 40 45 so 5.5 60 ICI

ta) Thisknejs 1s mimmum dimenston of hea\ iest section of part or nested load of parts. tb)2.2Shplui ISminiore\ery 12.Smm10.Sin.1orincrementof I2 Smm(0.5in.)o\er 75 mmt3 in ).tc) I h.5 minplusS mtn fore\ery 12 9 mmtO.S in )orincrementof 12.5 to.5 in.)o\er7S mmt3in.1. Source: .AhlS275W

Austenitic

Stainless

Steels / 745

314 Chemical

Composition. AISI/tJNS (S31400): 0.25 C. 7.00 Mn. I.50 to 3.00 Si, 23.0 to 26.00 Cr. 19.00 to 22.00 Ni. 0.0-45 P. 0.030 S

Similar

Steels (U.S. and/or Foreign). AM W1, 5652: ASThl A276. A3l-l. A173. AS80; SAE J-t05 (3031-t); tGer.) DM 1.4841: tFr.) AFNOR Z I2 CNS 25.20: (Ital.) CINI X 16CrNiSi 25 20. X 22 CrNi 3-S 20; tJap.) JIS SUS Y 310: (U.K.) B.S. 310s 2-l

Characteristics. Highest heat resistance properties of all the chromium-nickel steels. Essentially nonmagnettc. Subject to embtittlement u hen exposed for long periods of time to temperatures of 650 to 8 I5 ‘C t I200 to I SO0 “F). Brittleness only evident at room temperature and can be eliminated by holding steel at 980 to IO-IO “C t 1795 to 1905 “F). I to 2 h Forging.

Start forging at IO-IO to I I20 ‘C t 1905 to 2050 “F). Do not forge after forging stock drops below 925 “C t 1695 “F). Cool to black color in less than 3 min. using liquid quench if necessary

Recommended Normalizing. Annealing.

Heat Treating Practice

Do not normalize

Anneal at I IS0 “C (2 IO0 “F). To guard agamst distortion of thin, delicate parts. leave ample room for expansion between parts. Stainless grades expand about twice as much as carbon and low-alloy steels. Allou enough time for through heating after themlocouple has reached temperature. Stainless grades have approximateI>; half the thermal conductivity of carbon and low-alloy steels. Choice of atmosphere depends on fmish desired and whether surface stock will be removed. For bright annealing. use vacuum or an atmosphere of hydrogen or dissociated ammonia at dew point of-62 to -74 “C t-80 to -I 00 “F). Parts must be thoroughly clean and dry. Inert gases argon and helium t,althouph expensive) and nitrogen. with deu points of less than -S-l ‘C t-65 “F). can be used. The) lack the reducing effect of hydrogen. so slight discoloration in the fomm of chrome oxide can result. Salt. exothermic. or endothermic atmospheres are satisfactory for nonbright annealing. Salt is difftcult to remove. and rinse quenching at 595 “C t I IO5 “F) is not recommended. because interrupted quench at elevated temperature cannot be tolerated. Exothcrmic and endothermic atmospheres must be carefully controlled at equivalent carbon potential to avoid carburiration. u hich will seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present. scale I&ill form. Difficult to remove in subsequent descaling operations.

Cool rapidI> from annealing temperature: no more than 3 mm to black color. Section stze determines quenching medium: water for heavy sections. air blast for intemtediats sizes. and still au for thin sections. Carbides can precipitate at grain boundaries H hen parts are cooled too slowly between 125 to 900 ‘C (795 to I650 “F). In aerospace practice. parts are annealed at a set temperature of 1095 “C (2005 “F) and quenched in water with one exception: parts under 2.5 nun (0. IO in.) thick may be air cooled or pal) mer quenched to minimize distortton. Parts fabricated from steel in a strain-hardened condition. such as \> hard. shall not be annealed. stress relieved. or dimensionally stabilized I$ ithout permtssion of the cognizant engineering authority. Also, heat treating or slow cooling unstabilized grades between -I70 to Xl5 “C (875 to IS00 “F) IS prohibited. c\cept for 3O-lL and 3 I6L. See table for soakinp limes StreSS k?k?Ving. Parts can be relir\ed atier quenching to achieve dimensional stabilib. b> heating to 230 to 400 “C (4-U to 750 OF) for up to several houri. depending on section size and without change in metallographic structure. In aerospace practice. parts are stress relieved at 900 “C ( I650 “F). and quenched in Uater. As an altsmattve. parts may be stress relieved at annealing temperatures. Secttons under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as ‘s’, hard. shall not be stress relieved without pemission of the cognizan~sngineering authority. When stress relieving after v~elding. hold for 30 mtn minimum at the stress relieving temperature. Heat treating or slo\\ cooljnp of unstabilized grades between 470 to 8 IS “C (875 to IS00 “F) is prohtbned. except for 304L and 3lhL. See table for soaking times

Nitriding. Not recommended. Case seriousI> impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. OnI) used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nittided. parts must be m annealed condition to prevent Flaking or blistering of nitrided case. All sharp comers should be replaced \v ith radii of not less than I .S9 mm (0.06 in.). Film of pnmarily chrommm oxide. that protects stainless alloys from oxidation and corrosion. must be removed prior to nitriding. Accomplished by wet blasting. pickling chemical reduction in reducing atmosphere. submersion in molten salt, or b:\ one of several propriet+ processes. If doubt exists that complete and umfoml depassivation has occurred. further reduction of the oxide ma) be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation, avoid con-

746 / Heat Treaters

Guide

tamination of surface by finger or hand marking. Single-stage nitriding adequate at 525 to 550 “C (975 to 1020 “F) for 20 to 38 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 IO 35%. Hardness is as high as IO00 to 1350 HK on surface. 48-h cycle produces case extending to 0. I27 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness, at approximately 0. I65 mm (0.0065 in.)

Recommended

Processing

Cold work Anneal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride (if required)

Sequence

(if required)

314:

Soaking

Times (Aerospace

Diameteror thickness(a) of maximum section mm (in.) inclusive

Practice)

Mnimum Soaking time Atmosphere furnace tilt bath min min

upto’.so(o.lcoJ

20

o~er?.501o6.~5~0.1001o0.150) 0w 6.25 IO 12.50 (0.250 to 0.500) over I2.50to X.00 (0.500 IO I.001 o~rlr7-5.00t037.50~I.~X)t0 1.50,

35 15 60 7s

17 18 35 40 35

over 37.50 to SO.00t I .SOto 2.OOt o\er SO.00to62.50t2.00 to 7.50) over61.50to75.00(2.50to3.00) over 75.00 t ?.OOt

90 10s 120 ih)

so 55 60 CC)

~a) Thickness is minimum dimension of heaviest section of part or nested load of parts. tb) 2.25 hplus IS mm foretery 12.5 mmi0.S intorincrementof 12.Smm(O.S in.)over 75 mmt3 in.).(c) I h.5 nlinplus5 min forever) 12.5 mm(0.5 in.)orincrementof 12.5 10.5 intoner 75 mm (3 in.). Source: AhlS 27591-t

746 / Heat Treaters

Guide

316 Chemical

Composition. AISI/UNS (S31600): 0.08 C. 2.00 Mn, l.OOSi, 16.OOto 18.OOCr. lO.OOto l-l.00 Ni.O.045 P.O.03OS. 2.00 to3.00 MO

Similar Steels (U.S. and/or Foreign). AMS ss2d. ~~73. ~6-18. 5690. 5691; ASME SAl83, SAl93. SAl9-1. SA313. S.4’10. SA2-19. SA3 12. SA320, SA358. SA376. SA303. SA309. SA-430. SA-179. SA688; ASTM A167.A182,.A193.A19-I.A213.A1~0.A2~9.A269,A276,4312. A313. A3l-I. A320. A358. A368. A376. A403.4109. A130. A473.4478. A479: FED QQ-S-763. QQ-S-766. QQ-W-323; MIL SPEC hllL-S-862. MIL-S-5059; SAE J-IO5 (303 16): t Ger.) DfN I.440 I : (Fr.) AFNOR Z 6 CND 17.1 I: (1tal.j UNI X 5 CrNiMo I7 I?: (Jap.) JIS SUS 316. SUH 309. S1lSY316:(Swed.)SSt~2347;(U.K.)B.S.316S 16.316s 18.316S25. 316S26.316S30.316S40.316S4I.En.58H Characteristics.

Superior corrosion resistance vs other chroniumnickel steels. when exposed to man) types of chemical corrodents as well as marine atmospheres. Superior creep strength at ele\atsd temperatures. Very resistant to corrosion hq sulfuric acid

Forging. Start forging at I IS0 to 1260 “C (2100 to 3300 “F). Do not forge after forging stock drops helow 925 “C t I695 OF). Cool to black color in less than 3 min. using liquid quench if necess+

Recommended Normalizing. Annealing.

Heat Treating

Practice

Do not normalize

Anneal at 1010 to I I20 “C (1905 to 2050 “F). Within this range, lower temperatures are sufficient for sheet and strip. but higher temperatures should he used for plates and bars. To guard against distortion of thin. delicate parts. leave ample room for expansion between parts. Stainless grades expand about twice as much as carbon and low-allo! steels. Allow enough time for through heating after thermocouple has reached temperature. Stainless grades have approximatelq half the thermal conductivity of carbon and lou-alloy steels. Choice of atmosphere depends on finish desired and u hether surface stock nilI be removed. For bright annealing, use vacuum or an atmosphere of hydrogen ordissociated ammonia at dewpointof-62 to-71°C t-80 to-IOO’F). Parts must he thoroughI) clean and dry. Inert gases argon and helium (although expensive) and nitrogen. with dew points of less than -5-I “C (-65 “F), can he used. They lack the reducing effect of hydrogen. so slight discoloration in the form of chrome oxide can result. Salt. exothermic. or endothermic atmospheres are satisvdctory for nonbright annealing. Salt is difticult to remove. and rinse

quenching at 595 “C (I IO5 “F) is not recommended, because interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothermic atmospheres must be carefully controlled at equivalent carbon which will seriously lower corrosion potential to avoid carburization. resistance. Same pro&m with atmosphere annealing. If oxidizing conditions are present. scale will form. Difficult to remove in subsequent descaling operations. Cool rapidly from annealing temperature; no more than 3 min to black color. Section size determines quenching medium: water for heavy sections. air blast for intermediate sizes. and still air for thin sections. Carbides can precipitate at grain houndaries when parts are cooled too slowly between 425 to 900 “C (79.5 to 1650 “F). In aerospace practice, parts are annealed at a set temperature of 1095 “C (2005 OF) and quenched in water Hith one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. Parts fabricated from steel in a strain-hardened condition. such as l/z hard, shall not be annealed. stress relieved, or dimensionally stabilized without permission of the cognizant engineering authority. Also, heat treating or slow cooling unstabilized grades between 470 to 815 “C (875 to IS00 “F) is prohibited. except for 303L and 316L. See table for soaking times StreSS RelieVing. Parts can be relieved after quenching to achieve dimensional stability. hy heating to 230 to 400 “C (445 to 750 OF) for up to several hours. depending on section size and without change in metallographic structure.

In aerospace practics. parts are stress relieved at 900 “C ( 1650 “F). and quenched in \\ater. As an altemnti\e, parts may he stress relieved at annealing temperatures. Sections under 2.5 mm (0.10 in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as t/2 hard. shall not he stress relieved without permission of the cognizant engineering authority. When stress relieving after uelding. hold for 30 tin minimum at the stress relieving temperature. Heat treating or slo\\ cooling of unstabilized grades between 370 to 815 “C (875 to IS00 “Fb is prohibited. except for 301L and 316L. See table for soaking times

Nitriding. Not recommended. Case seriously Impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have Hear-resistant surface. If nitrided. parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers

Austenitic should be replaced with radii of not less than I.59 mm (0.06 in.). Film of primarily chromium oxide, that protects stainless alloys from oxidation and corrosion, must be removed prior to nitriding. Accomplished by wet blasting. pickling, chemical reduction in reducing atmosphere. submersion in molten salt. or by one of several proprietary processes. If doubt exists that complete and uniform depassivation has occurred, further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation. avoid contamination of surface by tinger or hand marking. Single-stage nitriding adequate at 525 to 550 “C (975 to 1020 “F) for 20 to 38 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case extending to 0. I27 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 300 HK core hardness. at approximately 0. I65 mm (0.0065 in.)

Recommended l l l l

Processing

Cold work Anneal and quench Remove surface contamination Stress relieve

Sequence

(if required)

l l

Stainless

Steels / 747

Depassilate (if nitriding) Nitride (if required)

316:

Soaking

Times (Aerospace

Diameter or thickness(a) of maximum section mm (in.) inclusive ober 2.50 to6.25 tO.IO0toO.ZiO) wcr 6.25 to I2.50 (0.250 to 0.500) i)\cr 12.50 to 25 00 (0.500 to I .OO) o\ er 25.00 to 37.50 I I.00 10 I SO) ober 37.50 toSO.OOt I .SO to 2.00) over 50.00 to62.50 t7.00 to 2.50) over6250 to 75.0012.SO to 3.00) o\er75.0013.00)

Practice)

Minimum soaking time Atmosphere furnace Salt bath min min 20 ‘5 15 60 75 90 10s 120 tb)

17 18 3s 40 15 SO 55 60 (Cl

(a) Thickness is minimum dimension of heaviest section of part or nested load of parts. (b) 2.29 h plus IS min for every 12.5 mm t0.S in.) or increment of 12.5 mm (0.S in.) over 75 mm(3 in.).(c) I h. Smmplus.i, mm lorevery 12.5 mm(O.Sin.)orincrementof 12.5 (0.5 in.)over 75 mm (3in.j Source: AMS 27591-t

Austenitic

Stainless Steels / 747

316F Chemical Composition.

AIWUNS (S31620):0.08 C. 2.00 Mn,

l.OOSi. 16.OOto 18.OOCr. lO.OOto 14.00Ni,0.200P.0.100Smin, 2.50 MO

Similar Steels (U.S. and/or Foreign). Characteristics. to improve machining ic screw machines

I.75 to

AMS 5649

Similar to type 3 16. except elements have been added and nonseizing characteristics. Suitable for automat-

Forging. Start forging at 1205 “C (2200 “F). Do not forge after forging stock drops below 925 “C (1695 “F). Cool to black color in less than 3 min. using liquid quench if necessary Recommended Normalizing. Annealing.

Heat Treating

Practice

Do not normalize

Anneal at 1095 “C (2005 “Fj. To guard against distortion of thin. delicate parts. leave ample room for expansion between parts. Stainless grades expand about twice as much as carbon and low-alloy steels. Allow enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conductivity of carbon and low-alloy steels. Choice of atmosphere depends on finish desired and whether surface stock will be removed. For bright annealing. use vacuum or an atmosphere of hydrogen or dissociated ammoma at dew point of -62 to -74 “C (-80 to - IO0 OF). Parts must be thoroughly clean and dry. Inert gases argon and helium (although expensive) and nitrogen. with dew points of less than -5-t “C (-65 OF). can be used. They lack the reducing effect of hydrogen, so slight discoloration in the fomm of chrome oxide can result. Salt. exothermic, or endothermic atmospheres are satisfactory for nonbright annealing. Salt is difftcult to remove. and rinse quenching at 595 “C (I I05 “F) is not recommended, because interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothermic atmospheres must be carefully controlled at equivalent carbon potential to avoid carburization. which will seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present. scale will form. Difftcult to remove in subsequent descaling operations.

Cool rapidly from annealing temperature; no more than 3 min to black color. Section stze determines quenching medium: water for heavy sections. air blast for intermediate sizes, and still air for thin sections. Carbides can precipitate at grain boundaries when parts are cooled too slowly between 425 to 900 “C (79s to I650 “F). In aerospace practice, parts are annealed at a set temperature of 1095 “C (2005 “F) and quenched in water with one exception: parts under 2.5 mm (0.10 in.) thick may be air cooled or polymer quenched to minimize distortion. Parts fabricated from steel in a strain-hardened condition, such as l/r, hard. shall not be annealed. stress relieved, or dimensionally stabilized without permission of the cognizant engineering authority. Also. heat treating or slow cooling unstabilized grades between 470 to 815 “C (875 to IS00 “F) is prohibited. except for 304L and 316L. See table for soaking times Rehhlg. Parts can be relieved after quenching to achieve StreSS dimensional stability. by heating to 230 to 100 “C (445 to 750 “F) for up to several hours. depending on section size and without change in metallographic structure. In aerospace practice. parts are stress relieved at 900 “C (1650 “F), and quenched in water. As an alternative. parts may be stress relieved at annealing temperatures. Sections under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as ‘/2 hard. shall not be stress relieved without permission of the cognizant engineering authority. When stress relieving after welding, hold for 30 min minimum at the stress relieving temperature. Heat treating or slow cooling of unstabilized grades between 470 to 815 “C (87s to 1500 “F) is prohibited, except for 304L and 316L. See table for soaking times

Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided, parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers should be replaced with radii of not less than I .59 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion. must be removed prior to nitriding. Accomplished by wet blasting, pickling. chemical reduction in reducing atmosphere. submersion in

748 / Heat Treaters Guide molten salt. or bj one of several propriety processes. If doubt ssists that complete and uniform depassivation has occurred. further reduction of the elide may be accomplished In furnace b> means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation. avoid contamination of wrface by finger or hand marking. Single-stage nitridinp adequate at 57-S to 550 “C (c)75 to 10X “F) for 20 to 48 h tdcpending on case depth required). Dissociation rates for single-stage cycle are from 20 to 3S00. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case estending to 0. I27 mm t0.005 in.) u ith approximatel) 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness. at approximately 0. I65 mm (0.0065 in.)

Recommended

Processing

Cold work Anneal and quench Remove surface contamination Stress relieve Dcpassivate (if nitriding) Nitride (if required)

Sequence

(if required)

316F:

Soaking Times (Aerospace Practice)

Diameteror thickness(a) of maaimum section mm (in.) inclusive upl0~.5010

1001

o~er~501o675~0.1001o0.2.50~ over 6.25 to 12.50 102.50 to 0.500~ over 12.50 10 25.00 (0.500 10 1.00) oler ~S.OOro 37.50( I 00 to 1.50, o\er 37.SOio5O OO( I 5Oto 2.00) o\er50.001o62501’.001o2.S0, over 62.50 to 75 00 I I.SO to 3.00) o\er 75.001300~

Minimum soaking Atmosphere furnace min 10 45 6s 80 95 I10 125 I40 IC)

time(b) Salt bath min 37

38 55 60 65 70 7S 80 (d)

(il) Thickness ii nummum dimenGon of hra\ lest section of pan or nested load of parts. (hi Parts should he held forsufticient time toensure that centerofmost mmsibesection has reached temperamre and necessary transformation and diffusion hare taken place. (c)Z h.3Sminplus 15minfore\ew l2.5n~~~O.SOin.)orincrementof l?SOmm(O.50 in ) o\er 75.0 mm 13 in.). td) I h. 25 min plus 5 ntin for ebery 12.50 mm (0.50 in.) or incrementof 12.5 mm 10 SOin.1o~er7S.On~,(3 in.). Source: AMS1_759/4

748 / Heat Treaters

Guide

316H Chemical Si. 16.00

Composition.

to 18.00

Cr. 10.00

Recommended

AISIpJNS: to l-1.00

Heat Treating

I .OO S. 2.00 to .1.00 klo

0.0-l to 0. IO C. 2.00 hln.

Ni. 0.045

P. 0.035

Practice

Annealing. In aerospace practice. parts are amWaled at a set temperature of 1095 “C tXOS “F) and quenched in irater with one exception: parts under 7.5 mm (0. IO in.) thick ma! be air cooled or pol>mcr quenched to minimize distortlon. Parts fabricated from steel in a strain-hardened condition. such as t/r, hard. shall not be annealed. stress relieved. or dimensionall! stabilized without permisslon of the copmzant engineering authontj. Also. heat treating or SIOU cooling unstabilized grades between 470 to 8 IS ‘T (875 to IS00 JF) is prohibited. except for 304L and 316L. See table for soaking times SW?SS k?hhg. In aerospace practice. parts are stress relked at 900 “C t 1650 “F). and quenched in ~aater. As an alternative, parts may be stress relieved at annealing temperatures. Sections under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain hardened condition. such as !s? hard. shall not be stress relieved without permission of the cognizant engineering authority. When stress relking after welding. hold for 30 min minimum at the stress relieving temperature. Heat treating or slog cooling of unstabilized grades bet\\een 470 to 8 IS “C i875 to I SO0 “F) is prohibited. except for 304L and 3 IhL. See table for soaking times

316H:

Soaking

Times (Aerospace

Diameteror thickness(a) of mrsimum section mm (in.) inclusive “plo2.solo IWJ o\rr2.soto6Y-IO

looraO’5oJ

,vcr h 2S to II!.SO 10 150 10 0.5001 0i-x 12.50 lo 25.00 IO.500 I0 I.001 o\er2S.tX)to37.50(1.00to I.501 o~rr37.S0roSO~t1.SOto2.tX)~ o~erS0.OOro61 SO~2.00~0?!0~ o\er62.501o7S W~2.SO1o3.00~ o\rr7SOO13001

Practice)

hlinimum soaking lime(b) Atmosphere furnace Salt bath min min 40 -IS 65 80 9s II0 I25 I40 ICJ

37 38 5.5 60 65 70 7s 80 W

18) Thichness is minimum dimsnsion of hen\ IC~Isection of part or nested load of pllrts. I b I Parts should be held for rufticient time IOensure that center of most massive section has reached wmperarure and necessq trans.formstion and diffusion have taken place. (c)1 h. 35 minplus IS nunfore\cw 12.Smm~O.SOin.)orincrementof 12.5Omm(O.50 in.) o\er 75 0 null 13 in.). id) I h. !S rmn plus 5 min for ewy 12.90 mm (0.50 in.) or increment of IZ S mm tO.SOin.lo\er7S.Omm (3 in.). Source: AMS 2759/J

748 / Heat Treaters

Guide

316L (S31603): 0.030 C. 2.00 hln. l.OOSi. 16.00 to 18.OOCr. 10.0010 l-l.00Ni.0.015 P.0.030S.2.00to3.00 hlo

hllL SPEC hIIL-S-862: SAE J-IOS (30316 L,: (Ger.) DrN 1.4404; (Fr.) AFNOR Z 2 CND 17.11: (Ital.) UN1 X 2 CrNihlo I7 12; (Jap.) JIS SUS 316L.SL~H310:(S\~ed.,SSt~2318:tI~.K.)B.S.316S 12.316s 14.316 S~2.316S2~.316S29.316S30.316S31,316S37.316S82.S.537

Similar Steels (U.S. and/or Foreign). AhlS 5507.5653; AShiE SA 182. SA2 13. SA240. SA2-19. SA3 I?. SA403. SA-179. SA688: ASThl 4167. Al8’. A213,AXO. A24Y.A26Y. A?76.A312,A314.A403.A473. A178. A47Y. A5 I I. AS54 A580. A632. X688: FED QQ-S-763. QQ-S-766:

Characteristics. Similar to type 316. except more resistant to interpranular corrosion after welding or stress relieving. Recommended for parts which are fabricated by \\elding and cannot be subsequently anwaled GeneralI> limited IO WIT ice temperatures up to 125 “C (800 “F)

Chemical

COIIIpOSitiOn.

AISljUNs

Austenitic Forging.

Start forging at I IS0 to 1260 “C i2 IO0 to 2300 “F). Do not forge after forging stock drops below 925 ‘C (I695 “F)

Recommended Normalizing.

Heat Treating

Practice

Do not normalize

Annealing.

Anneal at 1010 to I I05 “C ( I905 to 7025 “Fj. Use I040 “C ( I905 “F) minimum for maximum ductility. Parts can be air cooled from annealing temperature. Water quenching not necessary. Slow cooling can occur through the 815 to 375 “C (IS00 to 795 “F) range for up to 3 h, without subsequent danger of susceptibility to intrrgranular corrosion in natural atmospheric environments. In aerospace practice, parts are annealed at a set temperature of I095 “C (ZOOS “F) and quenched in water with one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched lo minimize distortion. Parts fabricated from steel in a strain-hardened condition. such as ‘12 hard. shall not be annealed. stress relieved. or dimensionall> stabilized without permission of the cognizant engineering authority. Also, heat treating or slow cooling unstabilized grades between -170 to 815 “C (875 to 1500 “F) is prohibited, except for 30-&L and 3 l6L. See table for soaking times

Stabilizing. Becauss type 3 l6L contains mol> bdenum. it is susceptible to sigma-phase formation as a result of long exposure 31 650 to 870 “C (IX0 to 1600 “F). Corrosion resistance improved b> employing a slabilizing treatment (ASTM ,436X). consisting of holding at 885 “C t 1615 “F) for 2. h prior IO stress relies ing at 675 “C ( I215 “F) Nitriding. Rare. Not recommended. Case serious11 impatrs corrosron resistance in most media. Case seldom more than 0. I37 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided. parts must be m annealed condition IO pre\ent flaking or blistering of nitrided case. All

Steels / 749

sharp comers should bs replaced with radii of not less than I .SY mm (0.06 in.). Film of ptimaril~ chromium oxide. that protects stainless alloys from oxidation and corrosion. must be removed prior to nitridinp. Accomplished bk wet blasting. pickling. chemical reduction in reducing atmosphere. submersion in molten salt. or b) one of several proprietary processes. If doubt exists that complete and uniform dcpassivalion has occurred. further reduction of the oxide ma) be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation. avoid contaminaGon of surface by finger or hand marking. Singlestage nitriding adequate at 525 IO 550 “C (975 to 1020 “F) for 10 to 48 h (depending on case depth requiredj. Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 Lo 1350 HK on surface. 48-h cycle produces case extending IO 0.127 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 300 HK core hardness. a1 approximatel) 0. I65 mm (0.0065 in.)

Recommended l l l l

Relieving. In aerospace practice. parts are stress relieved at Stress 900 “C (I650 “F). and quenched in water. As an alternative. parts ma! be stress relieved at annealing temperatures. Sections under 2.5 mm (0. IO in. I thick may be air cooled to minirmze distortion. Parts fabricated from steel in the strain-hardened condition. such as !‘z hard. shall not be stress relie\cd Hithout permission of the cognizant engineering authorit). When stress relieving after welding, hold for 30 min minimum at the stress reliel ing temperature. Heat treating or slon cooling of unstabilized grades between 470 to 815 “C (875 to 1500 “F) is prohibited. except for 3O-lL and 316L See table for soaking times

Stainless

l

Processing

Cold work Anneal and cool Stabilize and stress relie\c Depassivate tifnitriding) Nitride (if required)

316L:

Soaking

Sequence

(if necessary)

Times (Aerospace

Diameter or thickness(a) of maximum section mm (in.) in&site "plo~.5oro.lool 01 er 2.50 to 6.25 to. loo to 0.250) o\cr 6.25 IO 12.50 (0.150 to 0.500) O\C~ 12.50 to 25.00 (0.500 to 1.00) 01 er 25.00 to 37 50 t I Ml to I .SO) mcr 37.501050 00 ( I .so to 2.001 o\cr50.00 to67.50(‘00 to 2.50) o\er62.50to7S.OOt2.5Oto3.0(Jt o\sr75.OOt3.001

Practice)

Minimum Atmosphere furnace min 20 25 45 60 75 90 I05 IN IL-J)

soaking

time Salt bath min I7 I8 3.5 JO 45 SO 55 60 (c,

(81 Thisknnrss 15 minimum dimrnslon of heaviest secuon of part or nested load of parts. th1725hpluilSmtnior~~rr) I~.5nm110.5tn.~or1ncrementofl2.Smm~0.Sin.)orer 7S mm (3 in.). (rrt I h. 5 minplus 5 mtn t’orc\rp 12.5 mm(0.S in.)orincwmentof 12.5 (0.5 in.ro\rr75 mm13 in.). Source: .AhlS 2759/-l

Austenitic

Stainless

Steels / 749

316N Chemical

Composition. AISI/UNS (S31651): 0.08 c. 2.00 hln. 1.00 Si. 16.00 to 18.00 Cr. 10.00 to I-1.00 Ni. O.O-IS P. 0.03 S. 2.00 to 3.00 MO. 0. IO to 0. I6 N

Similar

Steels (U.S. and/or Foreign). AShlE SA I 82. S.42 I 3. SAXO. SA249. SA312. SA358. S.4376. SA103. SA130. SA-179: ASThl A 182. A2 13. AZ-IO. AX9. A276. .43 12. A35X. A376. A-103. A130. A179

Characteristics. affecting

ductility

Has added nitrogen. which increases strength M ithout and corrosion resistance

Forging.

Start forging at I IS0 to I260 “C (?I00 to 2300 “F). Do not forge after forging stock drops belo\r 92.5 “C t I695 “F). Cool to black color in less than 3 min. using liquid quench if nscess;u)

Recommended Normalizing.

Heat Treating

Do not normalize

Practice

Annealing. Anneal at 1010 to I I20 “C (1850 to 2050 “F). To guard against drstortion of thin. delicate parts. leave ample room for expansion between parts. Stainless grades clpand about twice as much as carbon and IOU -allo> steels. Allow enough time for through heatmg after thermocouple has reached temperature. Stamless Fades have approsimatel> half the thsrmal conducti\ it! of c‘arbon and low-alloy steels. Choice of atmosphere depends on finish desired and whether surfacs stock will be removed. For bright annealing. use vacuum or an atmosphere of hydrogen or dissociated ammonia at de\\ point of -62 to -74 C (-80 to -100 “F). Parts must be thoroughly clean and drl. Inert gases argon and helium (although expensi\ e) and nitrogen. with dew points of less than -51 “C (-65 “F), can be used. The! lack the reducmp effect of hydrogen, so slight discoloration in the form of chrome oxide can result. Salt. sxothermic. or endothermic atmospheres are satisfactor) for nonbright annealing. Salt is difficult to remove. and rinse quenching at 595 ,‘C’ I I105 “F) is not recommended. because inwrruptrd quench at elevated temperature cannot be tolerated. Exothermic and endothermic atmospheres must be arcfully controlled at

750 / Heat Treaters

Guide

equivalent carbon potential to avoid carburiration. which will seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present, scale will form. Dificult to remove in subsequent descaling operations. Cool rapidly from annealing temperature: no more than 3 min to black color. Section size determines quenching medium: water for heavy sections, air blast for intermediate sizes, and still air for thin sections. Carbides can precipitate at gram boundaries when parts are cooled too slowly between 425 IO 900 “C (795 to 1650 “F). In aerospace practice, parts are annealed at a set temperature of 1095 “C (2000 “FJ and quenched in air. oil. polymer, or water. Sections over 6.25 mm (0.25 in.) thick should be water quenched to minimize distortion. Parts fabricated horn steel in a strain-hardened condition should not be annealed. stress relieved, or dimensionally stabilized without permission of the cognizant engineering authority. Heat treating or slow cooling of unstabilized grades between 470 to 815 “C (875 to IS00 “F) is prohibited, except for 304L and 3 I6L. See table for soaking times

adequate at 525 to 550 “C (975 to 1020 ‘T) for 20 to 48 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case extending to 0.127 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness, at approximately 0. I65 mm (0.0065 in.)

Recommended l l l l l l

Processing

Cold work Anneal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride (if required)

316N:

Soaking

(if required)

Times (Aerospace

%%?SS Rl?ikViflg. Parts can be relieved after quenching to achieve dimensional stability, by heating to 230 to 400 “C (US to 750 T) for up to several hours. depending on section size and without change in metallographic structure

Diameter or thickness(a) of maximum section mm (in.) inclusive

Nitriding.

“pt02.50~0.100) over 2.50 to6 25 (0. IO0 to0.250,

Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided. parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers should be replaced with radii of not less than I .59 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion, must be removed prior to nitriding. Accomplished by wet blasting, pickling, chemical reduction in reducing atmosphere, submersion in molten salt. or by one of several proprietary processes, If doubt exists that complete and uniform depassivation has occurred, further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation, avoid contamination of surface by finger or hand marking. Single-stage nitriding

Sequence

o\er 6 !S to I1 50 (0 Xl to 0.500) 3\5r I2 50 co 15.00 10.500 to 1.00) over 25.00 to 37.50 (I 00 to 1.50) over 37.50 to 50.00 ( I..50 to 2.00) over SO.00 to 62.50 (2.00 to 2.50) over6250 to 75.00 12.50 to 3 00) over 75.00(3.00)

Practice)

Minimum soaking time(b) Atmosphere furnace Salt bath min min 40 1s

37

65 80 9.5 II0 I25 l-l0 (c)

55 60 65 70 75 80 (d)

38

(q) Thickness is minimum dimension of heaviest section of part or nested loadofpans. (h) Parts should be held for sufficient time to ensure that center of most massive section has reached tetI$WaN~ and necessary transformation and diffusion have taken place. (c)lh,35minplus 15minforevery 1~.5mm(0.50in.)orincrementof12.50mm(0.50 in.) over 75.0 mm (3 in.). (d) I h. 2S min plus 5 min for every 12.50 mm (0.50 in.) or increment of 12.5 nun (0.50 in.) over 75.0 mm (3 in.). Source: AMS 2759/4

750 / Heat Treaters

Guide

316LN Chemical

COmpOSitiOn. AISI/UNS: 0.03 C, 2.00 Mn, 1.00 Si. 16.00 to 18.00 Cr. 10.00 to 11.00 Ni. 0.015 P. 0.035 S. 3.00 to 3.00 MO. O.lOto0.l6N

Recommended

Heat Treating

Practice

Annealing.

In aerospace practice, parts are annealed at a set temperature of 1095 “C (2005 “F) and quenched in water uith one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. Parts fabricated from steel in a strain-hardened condition. such as t/z hard. shall not be annealed. stress relieved. or dimensionally stabilized without permission of the cognizant engineering authority. Also, heat treating or slow cooling unstabilized grades between 370 to 815 “C (875 to I500 “F) is prohibited, except for 3ML and 3 I6L. See table for soaking times Stress Rehhlg. In aerospace practice. parts are stress relieved at 900 “C (1650 “F), and quenched in water. As an alternative. parts may be stress relieved at annealing temperatures. Sections under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as h hard, shall not be stress relieved without permission of the cognizant engineering authority. When stress relieving after welding, hold for 30 min minimum at the stress relieving temperature. Heat treating or slow cooling of unstabilized grades between

470 to 815 “C (875 to 1500 “F) is prohibited, See table for soaking times

316LN:

Soaking

Times (Aerospace

Diameter or thickness(a) of maximum 5ection mm (in.) inclusive over ‘.SO to6.3 rO.100 to0.250) o\cr 6 75 to 12.50 (0.250 to 0300) o\er I2 50 to 25.00 (0.500 to I .OO)

o\er 25.00 to 37.50 ( I .w to I .SO) over 37.50 to SO.00I I .SOto 2.00) overSO.Wto62.SOt2.Wto2.SO) over 62.SO to 75.00 (2 50 to 3 00) over 7SWt3 00)

except for 304L and 316L.

Practice)

hlinimum soaking time@) Atmosphere furnace Salt bath min min 40 45 65 80 9s I IO 13 I-20 (C)

37 38 55 60 6S 70 75 80 W

(a) Thickness is minimum dimenston of heaviest section of part or nested load of parts. I ht Parts should be held for sufficient time to ensure that center of most massive section has reached temperatute and necessary transformation and diffusion have taken place. (c)2 h. 35 min plus I5 mm forevery 12.5 mmtO.SOin.)orinctementof 12.SOtnm(O.S0 in.) over 75.0 mm t3 in.). (d) I h. 25 nun plus 5 mm for every 12.50 mm (0.50 in.) or incrcmentof 12.SmmtO.SOin.)o~er7S.Ommt3in.).Soutce: AMS275914

Austenitic

Stainless

Steels / 751

317 Chemical

Composition.

AlSI/UNS

I .OO Si. 18.00 to 20.00 Cr. Il.00

(S31700): 0.08 c. 2.00 hln. to 15.00 Ni. 0.0-15 P. 0.03 S, 3.00 to 1.00

MO

Similar Steels (U.S. and/or Foreign). ASME sA2-10. sA2-W. SA312. SAd03. SAaOY; ASTM A167. A2-W. A269. A276. A312. A3 I-l, A103. A309, A473. AJ78, AS I I. A5S-l. ASgO. A632; FED QQ-S-763; MIL SPEC MLS-862; SAE 5305; Ger.) DIN I.-U-l9; (Ital.) UNI X 5 CrNihlo I8 15: (lap.) JIS SUS 317 Characteristics. plications.

especially

Exhibits excellent corrosion resistance where pitting corrosion is a problem

in special ap-

Forging.

Start forging at I IS0 to 1260 “C (2100 to 2300 “FL Do not forge after forging stock drops helow 925 “C t 1695 “F). Cool to black color in less than 3 min. using liquid quench if necessary

Recommended Normalizing. Annealing.

Heat Treating

Practice

Do not nomtalize

Anneal at 1010 to I I20 “C (I850 to 2050 “FL To guard against distortion of thin. delicate parts. leave ample room for expansion hetueen parts. Stainless grades expand about twice as much as carbon and low-alloy steels. Allow enough time for through heating after themrocouple has reached temperature. Stainless grades have approximately half the thermal conductivity of carbon and low-alloy steels. Choice of atmosphere depends on ftnish desired and whether surface stock will be removed. For bright annealing. use vacuum or an atmosphere of hydrogen or dissociated ammonia at dew point of -62 to -7-l “C t-80 to -100 “F). Parts must be thoroughly clean and dry. Inert gases argon and helium (although expensive) and nitrogen. with dew points of less than -5-l “C (-65 “F). can be used. They lack the reducing effect of hydrogen. so slight discoloration m the form of chrome oxide can result. Salt. exothermic. or endothermic atmospheres are satisfactory for nonbright annealing. Salt is difftcult to remove, and rinse quenching at 595 “C i I105 “F) is not recommended. because interrupted quench at elevated temperature cannot be tolerated Exothermic and endothermic atmospheres must be carefully controlled at equivalent carbon potential to avoid carburization. which will seriously lower corrosion resistance. Same problem uith atmosphere annealing. If oxidizing conditions are present. scale aill form. Diflicult to remove in suhsequent descaling operations.

Cool rapidly from annealing temperature: no more than 3 min to black color. Section size determines quenching medium: water for heavy sections. air blast for intermediate sizes. and still air for thin sections. Carbides can precipitate at grain houndaries u hen parts are cooled too slowly between -I25 to 900 “C (795 to 1650 “F) Stress RekVing. Parts can he relieved aher quenching to achieve dimensional stability, by heating to 230 to -IO0 “C (US to 750 “F) for up to several hours. depending on sectton size and without change in metallographic structure

Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0.127 mm tO.005 in.) deep. Only used in specialized applieattons u here material must be nonmagnetic and hate Hear-resistant surface. If nittided. parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers should be replaced H ith radii of not less than I .59 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion. must he removed prior to nitriding. Accomplished by wet blasting. pickling. chemical reduction in reducing atmosphere. submersion in molten salt. or by one of several proprietary processes. If doubt exists that complete and uniform dcpasstvation has occurred. further reduction of the oside may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable propnetary agent. After depassivatton. avoid contamination of surface by linger or hand marking. Single-stage nitriding adequate at 525 to 550 ‘C (975 to 1020 “F) for 20 to G3 h (depending on case depth requtred). Dissoctation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to I350 HK on surface. 48-h cycle produces case extending to 0. I27 mm tO.005 in.) with approximately 800 to 1000 HK. Case v+ill rapidly drop to 200 HK core hardness. at approximately 0. I65 mm (0.006.5 in. )

Recommended l l l l l l

Processing

Cold viork Anneal and quench Remo\ e surface contamination Stress relic\ e Drpassivate (if nitriding) Nitride (if required)

Sequence

t if requued)

Austenitic

Stainless

Steels / 751

317L Chemical

Composition.

1.00 Si. 18.00 to 20.00 Cr. II.00 h40

Similar

AIsI/UNS (S31703): 0.03 C. 2.00 hln. to 15.00 Ni. 0.045 P. 0.03 S. 3.00 to 1.00

Steels (U.S. and/or Foreign).

AWE

Al67.A24O;(Ger.)DIN l.-l43X:(Fr.)AFNOR22CND 2367: (U.K.) B.S. 317 S I2

SA240:

ASThl

19.S;(Swed.)SS1.4

Characteristics.

Similar to type 3 17. except more resistant to intergranular corrosion after belding or stress relieving. Recommended for parts which are fabricated by welding and cannot be subsequently annealed. Generally limited to service temperatures up to 425 “C (795 “F)

Forging. Start forging at 1230 “C (2245 “F). Do not forge after forging stock drops below 925 “C ( I695 “F)

Recommended Normalizing.

Heat Treating

Do not nomlalizc

Practice

Annealing.

Anneal at IO-10 to I IO5 ‘T I 1905 to 3025 OF). Use IO-IO “C (I905 ‘F) minimum for maximum ductility. Parrs can be air cooled from annealing temperature. IValer quenching not necessary. Slow cooling can occur through the 8 IS IO 12.5 “C ( I SO0 to 795 “F) range for up to 2 h. without subsequent danger of susceptibility IO mtergranular corrosion in natural atmospheric environmems

Stabilizing. Because type 3 I7L contains molybdenum. it is susceptible to sigma-phase formation as a resulr of long exposure at 650 to 870 “C ( 1200 to 1600 “F). Corrosion resistance improved by employing a stabilizing treatmen (ASThl A262C). consisting of holding at 885 “C ( 1625 “F) for 2 h prior to stress relieving a~ 675 “C ( I XS “F) Nitriding. Rare. Not recommended. Case seriously impairs corrosion resistance in mosl media. Case seldom more than 0.127 mm (O.OOS in.) deep. Only used in specialized applications where material must be nonmapnelic and have itear-resistant surface. If nitrided. parts must be in annealed condition to prevent flakinp or blistering of nitrided case. All sharp comers should he replaced \i ith radii of not less than I .S9 mm (0.06

752 / Heat Treaters

Guide

in. J. Film of pnmarily chromium oxide. that prorects stainless alloys from osidatron and corrosion. must be removed prior to nitriding Accomplished by met blasting. pickling. chemical reduction in reducing atmosphere. submersion in molten sah, or by one of several proprietary processes. If doubt elists that complete and unifomi depassivation has occurred. funher reduction of Ihe oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation. avoid contamination of surface by finger or hand marking. Sinplcstage nitriding adequate at 575 to 550 “C (975 to 1020 “Fr for 20 IO 48 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 3%. Hardness is as high as 1000 10 1350 HK on

surface. 48-h cycle produces case extending to 0. I27 mm (0.005 in.) with approximately 800 10 1000 HK. Case mill rapidly drop to 200 HK core hardness. at approsimately 0. I65 mm (0.0065 in.)

Recommended l l l l l

Processing

Cold work Anneal and cool Stabilize and stres5 relieve Dcpassivate (if niniding) Nitride (if required,

(if necessary)

Sequence

752 / Heat Treaters Guide

321 Chemical Composition. l.OOSi. 17.00to

AISI/UNS (S32100): 0.08 C. 2.00 hin. 19.00Cr. 9.0010 12.00 Ni. 0.015 P 0.03 S, 5 x Ci-CTi min

Similar Steels (U.S. and/or Foreign). AhlS 55 IO,

%t?SS Relieving. In aerospace practice. parts are stress relieved at 900 “C I 1650 “F). then quenched in air. polymer. or water. When stress relieving after irclding. parts are held 30 n-tin minimum at the annealing temperature. or 2 h minimum at the stress relieving temperature (see table for soaking times). Sections over 6.25 mm (0.25 in.) thick should be water quenched to minimtze carhide precipitation. Heat treating or slou cooling of unstabilized grades between -I70 to 8 I.5 “C (875 to I500 “F) is prohihited. ewept for 3O-lL and 3 I6L

5557. 5559.

5570. SS76.564S. 5689: ASME SA 182. SA 193. SA 19.4. SA2 13. SA2-w. SA2-l’). SA? 12. SA320. SA358, SA376. SA-tO3. SA-109. SA-l?O. SA-179: ASThl Al67. Al83.Al93. AI’)-&. A213. A240. A249. A269. A27l. A276. r\3 12. A3 14. A320. A358. A376. A103. A409. .A430. A473. A-179. A-193. AS I I: FED QQ-S-763. QQ-S-766. QQ-b’-123: hlIL SPEC MIL-S-86’: SAEU05(3132l);(Ger.)DfN l.-lS-Il;(Fr.)AFNORZ6CNTl8.lO:(Ital.) UNlX6CrNiTi I8 Il.X6CrNiTi I8 II KGXhCrNiTi I8 II KH’.Xb CrNiTi I8 I I KT. ICL 472 T: (Jap.) JIS SDS 321; (S~sd.) SStq 2337; (l!.K.,B.S.CDS-20.321 S 12.321 S 18.321 S22.321 S27.321 S-10.321 S49.321 SSO.321 SS9.371 S87.En.58C

Characteristics.

Stabilized hl the addition of titanium. this grade is near11 immune to intergranular precipitation of chromium carhide and its adverse effect on corrosion resistance. Recommended for parts which u ill he fabrtcated b> uelding and cannot be subsequsntl~ annealed. Rscommended for use between 125 to 900 “C (795 to I650 “F). Not recommended for decorative use. Hardenable by cold uork onI!. To impart maxmum corrosion resistance. use a stabilizing anneal in addition to annealing and stress relieving

Forging.

Start forging at I I.50 to I260 “C (2 IO0 to 2300 “FI. Do not forge after forging stoch drops belo\\ 925 “C ( I695 “F)

Recommended Normalizing. Annealing.

Heat Treating

Practice

Do not nomlalize

Anneal at 955 to I I20 “C I 1750 to 2050 “F) to relieve stresses. increase softness and ductility. or to pro\ ide additional stabiliration. See comments on protecttvc atmospheres for nnneality for bpe 201. Does not require water quenching To ensure maximum retention of austenite. oil or eater quench sections thicker than 6.-t mm (0.25 in.). In aerospace practice. parts are annealed at 980 “C i I795 “FJ and quenched in air. oil. polymer or mater. Sections over 6.25 mm (02.5 in.) thick should he water quenched to minimize distortion. Parts fabricated from steel in a strain-hardened condition. such as ‘,+ hard, shall not be annealed. stress relieved. or dimensionally stahilized without pemtission of the cognizant rngineerinp authority. See table for soaking times

Stabilizing. For maximum corrosion resistance. use corrective stabihzmp anneal by holding at 815 to 900 “C ( IS55 to 1650 “F) up to 5 h. depending on section thickness. Process applied hefore or during fabncation. hla) be followed hy stress relic\ ing at 705 “C (1300 “F) for a short time without harmful carhide precipitation Nitriding. Qptional. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. OnI) used in specialized applications where materiaJ must be nonmagnetic and have itear-resistant surface. If nittided, parts must be in annealed condition to pre\ent flaking or blistering of nitrided case. All sharp comers should be replaced with radii of not less than I S9 mm (0.06 In.). Film ofprimaril) chromium aside. that protects stainless alloys from oxidation and corroston. must he removed prior to nitriding. Accomplished hy wet blasting, pickling. chemical reduction in reducing atmosphere. submersion in molten salt. or hy one of several proprietary processes. If do&t exists that complete and uniform depasstvation has occurred. further reduction of the wide ma! be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassiv ation. avoid contammation of surface by finger or hand marking. Singlestage nitridinp adequate at S25 to 550 “C (975 to 1020 “F) for 20 to 48 h (depending on case depth required). Dissociation rates for smgle-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case extending to 0.127 mm (0.005 in.) with approximate11 800 to 1000 HK. Case vvill rapidly drop to 200 HK core hardness. at approximately 0. I65 mm (0.0065 in.) Recommended l l l l l

Processing

Cold moork Anneal and cool Stabilize and stress relieve Depassivate (if nitriding) Nitride (if necessag)

(optional)

Sequence

Austenitic 321:

Soaking Times (Aerospace Practice)

Diameter or thickness(a) of maximum section mm (in.) inclusive up to 2 50 (0.100) o\er?.SO to63 (0.100 to 0.30) oivr 6.25 to 12.50 (0.150 to 0.500) Ok’lx 12 50 to 25.00 10.500 to 1.00) o\er 25.00 to 37.50( 1.00 to 1.50) over 37.50 10 so.00 ( 150 10 2.00, o\erSO.OO to62.SO(XO to X0) over62SOto7SOO~2.SO1o3.00~ 0ver75.00(3.00)

Minimum soaking time(b) Atmosphere furnace Salt bath min mill 37 38 55 60 65 70 7s 80 (d)

(a) Thickness is minimum dimension of heaviest section of part or nested load of part, (h I Pxtnj should be held for suftkient ttme IO ensure thar center of most massi\ e section has reached tcntpertture and necessary transformation and diffitsion hn\e taken place. (c)2h.3Srntnplus ISminforeben 12.5mm(0.50in.)ormcrcmentof12.50nmm~0.S0 in.) over 75.0 mm (3 in.). (d) I h. ?S min plus 5 min for e\ew I?..50 mm 10.50 in.) or increment of 12.5 mm (0.50 in.) over 75.0 mm 13 in. I. Source ‘AhlS 2759/-l

Stainless Steels / 753

Austenitic

Stainless

Times (Aerospace

Practice)

Steels / 753

321 H Chemical l.OOSi.

Composition.

17.OOto

19.00Cr.9.OOto

Recommended

UNS 632109): 12.00Ni.0.045

Heat Treating

0.04

to 0.10

c.

7.00

P.O.03 S.S x GCTi

hln.

min

Practice

Annealing. In aerospace practice. parts are annealed at 980 “C I I795 “F) and quenched in air. oil, polymer. or uatcr. Sections over 6.3-S mm (0.25 in.) thick should he water quenched to minimize carhide precipitation. In stress relieving after welding. parts are held 30 min minimum at the annealing temperature, or 2 h minimum at the stress relieving temperature (see table for holding times). Parts fabricated from steel in a strain-hardened condition. such as I./? hard. shall not be annealed. stress relieved. or dimensionally stabilized uithout permission of the cognizant engineering authority Stress Relieving. In aerospace practice. parts are stress relieved at 900 “C (I650 “F). and quenched in air. polymer. or water. When stress relies mg after welding, hold for 30 min minimum at the annealing temperature or 7 h minimum at the wess relieving temperature (see table for soaking times). Sections over 6.25 mm iO.25 in.) thick should he water quenched to minimize carbide precipitation. Heat treating or slog cooling of unstabilized grades between 470 to 8 IS “C (875 to IS00 “F) $ prohibited. except for 304L and 3 l6L.

321 H:

Soaking

Diameter or thickness(a) of ma.simum section mm (in.) ioclusi\e

o\cr 2.SO106.25 (0.100 to0 250) o\er 6.15 IO 12.50 (0.250 IO 0.500) “\‘TT I?. 50 IO 25 00 10.500 to I 001 o\er 2.S 00 to 37 SO 1 I .oO 10 1.50, 0, er 37 SO to SO.00 I I SO 10 2.00) o\er5000to62.S0(2.00to2501 o\er62.SOro75 00~2.SO103.00~ o\er 7S.oO~3.OO~

Minimum soaking Atmosphere furnace min -lo -Is 65 80 95 II0 l2.i I-10 (c‘)

time@) Salt bath min 37 38 9s 60 6S 70 7S 80 Id)

la I Thickness is minimum dimensmn of hea\ irst wction of pun or nested load of pats. I bl Par& Jhould be held for sutiicient time mensure tharcrnvrofmosr massivesection has reached wmpsrature and nrcrssq rransformarion and diffusion hu\e taken place 1c1~h.3SrmnpluilSn~infor~~~n 12.5n~~O50in.~orincr~men~of1~.50mm~0.50 In.) wer 7S 0 mm t3 in.). I~I I h ?S nun plui 5 min for r\ery 12.SOmm (0.50 in.) or insremenr of I1 5 mm (0 SO m. I o\ er 75.0 mm (3 in. 1. Source. Ah% 275911

Austenitic

Chemical Composition.

AISl/UNS (S32900): 0. IO C. X0 hln. I .OO Si. 25.00 to 30.00 Cr. 3.00 to 6.00 Ni. 0.045 P, 0.03 S. I.00 to 2.00 hlo

Similar Steels (U.S. and/or Foreign).

AWE

SAX&

ASThl

A268. AS I I

Characteristics. Similar to tjpz 316. except exhibits superior rsGstance to stress corrosion cracking. Capable of agz hardening. but becomrs brittle if hardened and should be restricted to compressive forces in this condition. This is an austenitic-ferritic (duplex) stainless steel

Stainless Steels / 753

Forging. Start forging at 1095 ‘C tXO5 “FJ. Do not forge after forging stoch drops below 915 “C I I695 ‘FL Cool to black color in less than 3 min. using liquid quench if nssrss;lr) Recommended Normalizing. Do Annealing.

Heat Treating

Practice

not nomlulire

.Annal at 925 to 955 YY ! 1695 to I750 “FL Harden at 730 “C I I350 “FL Hold I7 h and cool rlo\r I> in air or furnace. To guard against distortion of thin, delicate pcxtb. leave ample room for expansion between part\ Stainless grxles expand about t\r ice as much as carbon and low-alloy

754 / Heat Treaters Guide steels. Allow enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conductivity ofcarbon and low-alloy steels. Choice of atmosphere depends on finish desired and whether surface stock will be removed. For bright annealing. use vacuum or an atmosphere of hydrogen or dissociated ammonia at dew point of-62 to-74 “C (-80 to-100 “F). Parts must be thoroughly clean and dry. Inert gases argon and helium (although expensive) and nitrogen. with dew points of less than -54 “C (-65 “F), can be used. They lack the reducing effect of hydrogen, so slight discoloration in the form of chrome oxide can result. Salt. exothemtic, or endothermic atmospheres are satisfactory for nonbright annealing. Salt is difficult to remove. and rinse quenching at 595 “C (I I05 “F) is not recommended, because interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothemtic atmospheres must be carefully controlled at equivalent carbon potential to avoid carburization. which will seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present, scale will form. Difficult to remove in subsequent descafing operations. Cool rapidly from annealing temperature; no more than 3 nun to black color. Section size determines quenching medium: water for heavy sections, air blast for intermediate sizes, and still air for thin sections. Carbides can precipitate at grain boundaries when parts are cooled too slowly between 425 to 900 “C (795 to 1650 “F)

Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0.127 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided. parts must be in annealed condition to prevent flaking or blistering of nitrided case. AU sharp comers should be replaced with radii of not less than I.59 mm (0.06 in.). Film of primarily chromium oxide, that protects stainless alloys from oxidation and corrosion. must be removed prior to nitriding. Accomplished by wet blasting, pickling, chemical reduction in reducing atmosphere, submersion in molten salt. or by one of several proprietary processes. If doubt exists that complete and uniform depassivation has occurred, further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation. avoid contamination of surface by finger or hand marking. Single-stage nitriding adequate at 525 to 550 “C (975 to I020 “F) for 20 to 48 h (depending on case depth required). Dissoctation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case extending to 0. I27 mm (O.OOS in.) with approximately 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness, at approximately 0. I65 mm (0.0065 in.)

Recommended l l

Stress RelieVing. Parts can be relieved after quenching to achieve dimensional stability. by heating to 230 to 300 “C (-l-IS to 750 “F) for up to several hours. depending on section size and without change in metallographic structure

l l l l

Processing

Cold work Anneal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride (if required)

Sequence

(if required)

754 / Heat Treaters

Guide

COmpOSitiOn. AISI/UNS (NO8330):0.08 C. 2.00 Mn.

Chemical

0.75 to I .50 Si. 17.00 to 20.00 Cr. 3-t.00 to 37.00 Ni, 0.040 l? 0.030 S

Similar

Steels (U.S. and/or

H31.3 I. H31.30: ASTM (30330). 5312 (30330)

Foreign).

B5 I I, BS 12. B535,

Characteristics. Has good resistance thermal shock. Magnetic in all conditions

MS B536.

5592, 57 16; ANSI B-516; SAE J-W.5

to carburization

and to heat and

Forging. Start forging at I I50 to I I75 “C (2 100 to 3 I SO “F). Do not forge after forging stock drops below 925 “C ( 1695 “F). Cool to black color in less than 3 min. using liquid quench if necessary

Recommended Normalizing.

Heat Treating

Practice

Do not normalize

remove, and rinse quenching at 595 “C (I IO.5 “F) is not recommended. because interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothermic atmospheres must be carefully controlked at equivalent carbon potential to avoid carburization, which will seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present. scale will form. Difftcult to remove in subsequent descaling operations. Cool rapidly from annealing temperature; no more than 3 mitt to black color. Section size determines quenching medium: water for heavy sections. air blast for intermediate sizes. and still air for thin sections. Carbides can precipitate at grain boundaries when parts are cooled too slowly between 425 to 900 “C (795 to 1650 “F) Stress Relieving. Parts can be relieved after quenching to achieve dimensional stability. by heating to 130 to 100 “C (44 to 750 “F) for up to several hours. depending on section size and without change in metallographic structure

Annealing.

Anneal at 1065 to I I75 “C (I950 to 2 I50 “F). To guard against distortion of thin. delicate parts. leave ample room for expansion between parts. Stainless grades rxpand about twice as much as carbon and low-ahoy steels. Allow enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conductivity of carbon and low-alloy steels. Choice of atmosphere depends on finish desired and whether surface stock will be removed. For bright annealing. use vacuum or an atmosphere of hydrogen or dissociated ammonia at dew point of -62 to -74 “C (-80 to -100 “F). Parts must be thoroughly clean and dry. Inert gases argon and helium (although expensive) and nitrogen. with dew points of less than -5-t “C (-65 “F). can be used. They lack the reducing effect of hydrogen. so slight discoloration in the form of chrome oxide can result. Salt, exothermic. or endothermic atmospheres are satisfactory for nonbright annealing. Salt is difficult to

Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I37 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided. parts must be in annealed condition to prevent flaking or blistering of nittided case. AU sharp comers should be replaced with radii of not less than I.59 mm (0.06 in.). Film of primarily chromium oxide, that protects stainless alloys from oxidation and corrosion, must be removed prior to nitriding. Accomplished by wet blasting, pickling, chemical reduction in reducing atmosphere. submersion in molten salt. or by one of several proprietary processes. If doubt exists that complete and umform depassivation has occurred, further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation. avoid con-

Austenitic tanlination of surface by finger or hand marking. Single-stage nitriding adequate at 5X to 550 “C (975 to 1020 “F) for 20 to -18 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case extending to 0. I77 mm (0.005 in.) with approximately 1300 to 1000 HK. Case will rapidly drop to 200 HK core hardness. at approximately 0. I65 mm (0.0065 in.)

Recommended l l l l l l

Processing

Cold work Anneal and quench Remove surface contamination Stress relieve Depasstvate (if nitridinp) Nitride (if required)

Stainless

Sequence

(if required)

Steels I755

Austenitic

Stainless

Steels / 755

347 Chemical

Composition.

lOOSi. 17.OOto 19.00Cr.9.00ro +Tamin

AISI/UNS (S3J700): 0.08 C. 2.00 Mn. 13.OONi.0.045 P,O.O3OS, IO X %CNh

Similar Steels (U.S. and/or Foreign). ~1s 5s I 2, 5556, 5558, 5571. 5575, 5@6. 5654. 5674. 5680: ASME SAl83. SA193, SAl9-I. SA213. SA240. SA719. SA3 12. S.43’0. SA?58. S.4376. SA-103. S/-\-W. SAJ30. SAJ79; ASTM A 167. A 182, .4 193. A 194. A2 13. A2-19. A269. A271. A276. A3 13. A3 I-L A320. A358, A376, A-lO3. A-109. A-130, A-173. Ad79. Aa93. A5 I I. A554. AS80.4633: FED QQ-S-763, QQ-S-766. QQW-423; MLL SPEC MfL-S-862. MLL-S-23195, MIL-S-23196; SAE J-IOS t30317j; (Ger.) DfN 1.-15.50: (Fr.) AFNOR 26CNNb 18.10: (Ital.) LlNl X 8 CrNiNb I8 I I; (lap.) JIS SLIS 347: (Swed.) SSIJ 2338: (U.K.1 B.S. 347 S 17, En. 58 F. En. 58 G. ANC 3 Grade B Characteristics. Stabilized by the addition of niobium plus tantalum. this grade is nearly immune to intergranular precipitation of chromium carbide and its adverse effects on corrosion resistance. Thin sections do not require waler quenching from annealing temperature. Stabilizing anneal at 870 “C (I600 “F) seldom required. Hardenable by cold work only Forging. Starr forging at II50 to 1260 “C (2100 to 2300 “F). Do not forge after forging stock drops belo\\ 925 “C (I695 “F)

Nitriding. Optional. Not recommendsd. Case seriously Impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided. parts must be in annealed condition to prevent flahing or blistering of nitrided case. AU sharp comers should be replaced with radii of not less than 1.59 mm (0.06 in.). Film of primaril) chromium oxide. that protects stainless alloys from oxidation and corrosion. must be removed prior 10 nitriding. Accomplished by wet blasting, pickling. chemical reduction in reducing atmosphere. submersion in molten salt. or b) one of several proprietary processes. If doubt exists that complete and uniform depassivalion has occurred. further reduction of the oxide may he accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivalion. avoid contamination of surface bq finger or hand marking. Singlestage nitriding adequate at 51-S to 550 “C (975 10 1020 “F) for 20 to 38 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. -18-h cycle produces case extending to 0. I27 mm (0.005 in.) with approximately 800 IO 1000 HK. Case will rapidly drop to 200 HK core hardness. at approximately 0. I65 mm (0.0065 in.)

Recommended l

Recommended Normalizing.

Heat Treating

Practice

Do not normalize

l l l

Processing

Sequence

Cold worh Anneal and cool Depassivate (if nitriding) Nitride (if necessary)

Annealing.

Anneal at 1010 to I I20 “C (I850 to 2050 “F). See recommended heat treating practice for type 201 for information on protective atmosphere for annealing. For thin sections. anneal to obtain maximum softness and ductility. Air cool. For sections over 6.25 mm (0.25 in. j. oil or water quench to ensure maximum retention of austenile. For titanium-stabilized type 32 I, a stabilizing anneal at approximately 870 “C ( 1600 “Fj is often used. Seldom used on niobium-stabilized grades. In aerospace practice. parts are annealed at IWO “C (I905 “F) then quenched in air. oil, polymer. or water. Seclions over 6.25 mm (0.25 in.) thick should be uater quenched to minimize carbide precipitation. Parts fabricated from steel in a strain-hardened condition. such as l/z hard. shall not be annealed. stress relieved. or dimensionally stabilized without permission of the cognizant engineering authority. See table for soaking times StrC?SS %?kViIlg. In aerospace practice. parts are suess relieved at 900 “C (1650 “F). As an alternative, this alloy may be stress relieved at annealing temperatures. Quenching is in air. polymer. or water. Sections over 6.25 mm (0.25 in.) thick should be water quenched to minimize carbide precipitation. Parts fabricated in the strain-hardened condition. such as ‘/z hard. shall not be suess relieved uithout permission of the cognizant engineering authority. See table for soaking times

347:

Soaking

Times (Aerospace

Diameter or thickness(a) of maximum section mm (in.) inclusive upro 2.SOtO 100) ovzr~.s0106.-?5~0.100100.2501 mer 6.25 to 12.50 f0 WI to 0.5001 over I30 IO 15 00 (0.500 to I .OOI over ~5.00 to 37 SO ( I .OO to I 501 over 37.50 to 50.M)’ I.50 to 2.ooJ o~erS0.00to6~.50~1lCIOto7-.SO~ o~er6250t07500t250to3.00t oser7S OO(3 001

Practice) hlinimum

Atmosphere furnace

soaking time(b) Salt bath

min

min

10 4s

37 38 5s 60 65 70 7s 80 w

65 80 9s II0 I’S IJO fCJ

raJ Th~kness 15 minimum dimension of hea\ iest section of part or nested load of parts. (ht Parts should be held for suflicient time to enwre that center of most massive section has reached temperature and nece>s+ transformatian and diffusion have taken place. tct2h.3SminolusISminfore\en I~.Stnm~0.50in.torincrementof12.50mm~0.50 in.) over 75 0 km 13 in.) (dr I h. ?S mm plus 5 min foreten 12.50 mm (0.50 ikor Increment of 12 5 mm (0.50 in.1 o\er 75.0 null t3 in.). Sourw’AMS 2759/J

756 / Heat Treaters

Guide

347H Chemical

Composition.

Mn. I .oO Si. 17.00 IO 19.00 min to I .OO max Nb

Recommended

AISI~I~NS (~4709): Cr. 9.00

to 13.00

Heat Treating

0.0-l

Ni. 0.045

to 0. IO C. xo

P. 0.030

S. 8 x 5C

Practice

347H:

Soaking

Times (Aerospace

Diameter or thickness(a) of maximum section mm (in.) inclusive

Annealing.

In aerospace practice. parts are annealed at 1040 “C ( I905 “F) then quenched in air. oil. pol!,rner. or Hater. Sections over 6.25 mm to.35 in.) thirk should he uater quenched to minimize carhide precipitation.. Parts fabricated from steel in a strain-hxdened condition. such as t+ hard. shall not be annealed. stress relieved. or dimensionall> stahilired without pemlisslon of the cognizant engmeering authorit>. See table for soaking times

Stress

f?etievirlg.

900 “C ( 1650 “F’L As annealing temperatures. o\er 6.75 mm tO.25 carbide precipitation. such as !+ hard. shall cognizant engineering

In aerospace practlcs. parts are stress relkrd at an altcmatke. this allo! may he stress relieved a~ Quenching IS in au. polymer. or uater. Sections in.) thick should be mater quenched to minimize Parts Fdbncntsd In the strain-hardened condition. not he stress relieved without pemussion of the authority. See table for soaking times

oker 2.501063 10 lOOro0.XJ~ over 6.3 to 12.50 10.150 to 0.5001 oker 12.50 10 25.00 (0.500 to 1.00) o\er 25 llOro 37.2Ot I 0010 1.5Ot o\er 37.5010 50.00~ lSO~ol.00~ o\er SO.00 to 62.50 I WQ to 2.50, over62 50ro75.OOt~.50to 3.001 o\sr75.OOl3001

Practice)

Minimum soaking Atmosphere furnace min 40 4s 65 80 95 I IQ I25 I-IO 15)

time(b) Salt bath min 37

38 55 Ml 65 70 75 80 Cd)

~a~l’hichness ii nlinimumdimcnsionofhea\icstsrclionofpanornestedloadofpans. I h) Pms should he held for sufticirnr time to ensure that center of most miLSs,ve section has reached temperarurr and necessary trunsformation and diffusion habe taken place. 1c,~h.3~minplu~ljnljnforr~r~ 12.~nim~i).50in.)orincremen~of12.50mm(0.50 in.) o\er 75.0 mm 13 in.,. Id) I h. 25 nun plus S nun forevery 12.50 mm (O.SO in.)or increment of 12.5 mm ~0.50 in.) oker 75.0 mm I 3 in.). Source. AMS 2759/4

756 / Heat Treaters

Guide

348 Chemical

Composition.

AISWNS

l.OOSi. 17.OOto lY.OflCr.S).(X)to ‘“rC min Nh. 0. IO Ta

(SMSOO): 0.08 c. XXI hln.

13.OONi.(J.015

P.O.03OS.O.2Co.

IOx

Similar Steels (U.S. and/or Foreign). AShlE SA 182. SARI 3. SAXO. S.4249, SA3 12. SA3SX. S.4376. S.4-!03. SA-IOY. SA-l7Y: hSThl .4167. Al82 A213. A2-lO. 44219. 4269. A’76. A.712 ,431-t. A358. A376. A403. A17Y. A580. A632; FED QQ-S-766: hllL SPEC hlJL-S-‘3195. ML-S-23196; SAE J3OS (30348): (Ger.) DIN l.Gl6: ~U.K.J B.S. 3-17 S 17. 3-l7 s 18. 317 s -to. 2 s. 130. s. 525. s. 527 Characteristics.

Similar

to gyps 3-17. exespt

tantahm~ content requanservice. Hardenable

stricted to 0. IO max and cobalt to 0.20 max. Used where restricted tity of these elements by cold work only

is required,

as in radioactive

Forging.

Start forging at I IS0 IO 1260 “C (2 100 IO 2300 “F). Do not forge after forgut@ stock drops below 925 “C i l6YS “F)

Recommended Normalizing. Annealing.

Heat Treating

Practice

Do not nomtnlire

Anneal al 1010 to I I20 ;C (I850 to 2050 ‘.Ft. See recommended heat treating practice for type 201 for information on protective atmosphere for annealing. For thin sections, anneal to obtain maximum softness and ductility. Air cool. For sections over 6.25 mm (0.25 in.). oil or mater quench to ensure maximum retention ofaustenits. For titanium-stabilized type 32 I. a stabilizing anneal at approximately 870 “C r 1600 “F) is often used. Seldom used on niobium-stabilized grades. In aerospace practice. parts are annealed at IO-IO ‘C ( 1905 “F) then quenched in air. oil. polymer. or water. Sections o\er 6.25 mm (0.25 in.) thick should be mater quenched to minimize carbide precipitation.. Parts fabricated from steel in a strain-hardened condition. such as ‘/: hard. shall not be annealed, stress relieved, or dimensionally stabilized without permission of the cognizant engineering authority. See table for soaking times

Stress RelieVing. In aerospace practice. parts are stress relieved at 900 “C (I650 “Ft. As an altematr\e. this ahoy may be stress relieved at annealing temperatures. Quenching is in air. polymer, or water. Sections o\er 6.25 mm (0.25 in.) thick should be water quenched to minimize carbide precipitation. Parts fabricated in the strain-hardened condition. such as t/2 hard. shall not be stress relieved uithout permission of the cognizant engineering authority. See table for soaking times

Nitriding. Optional. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and ha\e ear-resistant surface. If nitrided. parts must be in annealed condition to pre\cnt tlaking or blistering of nitrided case. All sharp comers should be replaced H ith radii of not less than I .S9 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion. must be removed prior to nitriding. Accomplished by \\et blasting. pickling. chemical reduction in reducing atmosphere. submersion in molten salt. or by one of several proprietary processes. If doubt exists that complete and uniform depassivation has occurred. further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable propnetary agent. After depassi\ ation. a\ oid contamination of surface by linger or hand marking. Singlestage nitriding adequate at S2S to 550 “C (975 to 1020 “F) for 20 to 48 h (dependin! on case depth required). Dissociation rates for single-stage cycle are Iron1 20 IO 35%. Hardness is as high as 1000 to 1350 HK on surface. 18-h cycle produces case extending to 0. I27 mm (0.005 in.) with approximately 800 to 1000 HK. Case \iill rapidly drop IO 200 HK core hardness. at approximately 0. I65 mm (0.0065 in.)

Recommended l l l l

Processing

Cold \soork Anneal and cool Depassb ate t if nitriding Nitride (if necessary)

r

Sequence

Austenitic

348:

Soaking Times (Aerospace

Diameteror thickness(a) of maximum section mm (in.) inclusive

o~erI.SOto6.~S(O.l00toO.?SO~ over 6.25 to 12.50 (0.250 to 0.500) over I I..50 to ‘5.00 (0.500 to I .OO) over 25.00 10 37.501 I Ml lo 1.50) over 37.50 to SO.00 ( I.50 to 2.00) over SO.00 IO 62.50 COO to 1.50) o~er62.SOto74.00(1.SOto3.TX)~ o\er75.00(3.00)

Practice)

i%linimum soaking Atmosphere furnace min -10 1s 6.5 80 95 II0 135 I10 (Cl

time(b) Salt bath min 37 38 55 60 65 70 75 80 (d)

la) Thickness is mmimum dimension of hen\. iest wction of pm or nesled load of parts I b) Parts should be held for suftkicnt time IO ensure (hat cenler of most massi\ e section has reached temperature and neceasq transformaCon and diffusion have taken place. (c)Z h.39 nin plus IS min foreven’ 12.5 nini~O.SOin.)orincremen~of 12.SOmm(O.S0 in.) over 750 mm (3 in.). id) I h. ?S nun plus 5 nun forrtery 12.50 mm (0.50 in.) or mcrement of 11.5 mm (0.50 in.)o\er 75 Omm (3 in.,. Sourw ALIS 1759/A

Stainless

Steels I757

Austenitic

Stainless

Times (Aerospace

Practice)

Steels I757

348H Chemical

Composition.

AISI~UNS (~34809): 0.04 to 0. IO c. xo

Mn. I .OO Si, 17.00 to 19.00 Cr. 9.00 to 13.00 Ni. 004.5 P, 0.030 S. 0.2 Co. 8 x CC min to I .OO max Nb. 0. IO Ta

Recommended

Heat Treating

Practice

348H:

Soaking

Diameter or thickness(a) of maximum section mm (in.) inclusive

Annealing.

tn aerospace practice. parts are annealed at 1040 ‘C ( 1905 “F) then quenched in air. oil, polymer. or &Cater. Sections over 6.3 mm to.25 in.) thick should be water quenched to minimize carbide precipitation.. Parts fabricated from steel in a strain-hardened condition. such as !+ hard. shall not be annealed. stress relie\cd. or dimensionall!, stabilized without permission of the cognizant engineering authority. See table for soaking times

Stress RelieVing. In aerospace practice. parts are stress relicLed at 900 “C (1650 “F). As an alternative. this allo) may be stress relieved at annealing temperatures. Quenching is in air. polymer. or mater. Sections over 6.3 mm (0.25 in.) thick should be water quenched to minimize carbide precipitation. Parts fabricated in the strain-hardened condition. such as ‘/2 hard. shall not be stress relieved without permission of the cognizant engineering authorit). See table for soaking times

o\rr2.SOto6.2St0.10C)to0.2S0) oter 6.25 IO 12.50 10.250 to 0.500’1 over 12.50 to IS 00 (0.500 to I .OO) o~rr~SWto37.S01I.~)Otol.S0~ over 37 so to so.00 ( I .so to 2.00~ over SO.00 toh3Ot~.OO to 2 501 okcr62 SOto75.00~2 SO IO 3.00) 0ver75.0013.001

(SJThi&;nr~f

Minimum soaking Atmosphere furnace min 40 -Is 65 X0 9s II0 125 I40 ICI

time(b) Salt batb min 37 38 5s 60 65 70 7s X0 IdJ

is minimum ilimen,ion of hen\ ieil wstion of part or nested load of parts. I h) Par~should he held forwfficirtnt time toenwre thatcrnterofmost massi\rsecdon ha reached temperature and newsal?. transformation and diffusion habe taken plscc tc~2h.3S minplus ISnunfore\en 12.5 mn110.SOin.,orinsrementof 12.50mm~0.50 tn.) over 7S.0 mm I 3 In ). td) I h. 15 mm plu> S nlin fur r\ery I250 mm (0.50 in.) or mcrrment of 12 S mm IO SO in bo\er 7S.0 mm (3 in 1. Sourw 4hlS 275914

Austenitic

Stainless

Steels I757

384 Chemical

Composition. AISI~NS (S38400): 0.08 C. 2.00 kin. 1.00 Si, IS.00 to 17.00 Cr. 17.00 to 19.00 Ni. 0.045 P. 0.030 S

Similar

Steels (U.S. and/or Foreign).

ASTM

~493;

SAE J405

(3038-l)

Characteristics.

Has a loher cold \+ork hardening rate than type 305. Used when severe cold heading or cold forming operations are required

Forging. Start forging at I IS0 to 11-30 ‘C 12100 to 224S “FL Do not forge after forging stock drops below 925 “C t 1695 “Fj. Cool to black color in less than 3 min. using liquid quench if nece\sq

Recommended Normalizing.

Heat Treating

Practice

Do not nomlalize

Annealing. .Annenl at IO-W to I I SO “C ( 190s to 2100 “F). To guard against distortion of thin. delicate parts. leave ample room for expansion hetueen parts. Stainless gades expand about tH ice as much as carbon and lo\\ -alloy steels. Allo\\ enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conducti\ ib of carbon and lo\r-allo) steels. Choice of atmosphere depends on linish desired and \i hether surface stock nilI he removed. For bright annealing use vacuum or an atmosphere of hydrogen or dissociated ammonia at de\{ point of -62 to -71 “C t-80 to -100 “F). Parts must he

758 / Heat Treaters

Guide

thoroughI> clean and dr). Inert gases ;trgon and helium (although s\pensi\e) and nitrogen. \bith dr\r points of less than -S-l “C c--6S “F). can bc used. The) lath the reducing &‘a~ of hydrogen. so slight discoloration in the form of chrome o\ids can result Salt. cxothrrmic. or sndothsmic atmospheres are satisfactor) for nonhright ;Inncnling. Salt is diffialt to remove. and rinse quenching at 5% “C I I IOS “F) is not recommended. hecausrt interrupted quench at clr~ated temperature cannot hr tolerated. E\othrrmic and endothermic atmospheres must he carefully contmlkd at equib alent carbon potential to avoid carhuriration. u hich u ill ssriousl~ Iwer corrosion resistance. Same prohlsm with atmosphere annealing. if oxidizing conditions are prebrnt. wale itill form. Difficult to remove in suhscquent dcscnling operations. Cool rapidly from annealing temperature: no more than 3 min IQ hlack color. Section SIX dstemunes quenching medium: water for hew! SWtions. air blast for intamediatr sires. and btill atr for thin bsctions. Cnrhidrs cm precipitate at grnrn houndark I\ hen parts are cooled too slou I> hstwssn 425 to Wo “C (7Y5 to I650 “FI Strt?.SS RdieVing. Parts ran he relkrd after qusnshing. to nchwc dimensionul Stabilit). h! hentmg to 2.30 to -IO0 :‘C (US to 750 ‘F) for up tv weral hours. depending WI section 4ze and \rithout chanffe in mrtallographic struucturs

Nitriding.

Not recommended. Case srriou4y impair5 corroston resistance in most media. Case seldom more than 0. I27 mm (0.005 In.) deep. OnI! uwd in ~pccialired application\ \\ here mutsrinl must he nonmnpnetlc and hats wctr-resistant wrface. If nittided. parts must he in ~nnsaled

condition to pre\ent Flaking or hli>terinp ofnitridrd case. All sharp comers should he replawd M ith radii of not Icsb than I .SY mm (0.06 in.). Film of primaril> chromium oxide. that protects jtainkss alloys from oxidation and corroGon. must he rsmo\cd prior to nitriding. Accomplished by wet blasting. pickling chemical reduction in reducing atmosphere. suhmersion in molten salt. or hv one of wa-al propriety processes. If doubt exists that complete and uniform depassi\ ntion has occurred. further reduction of the oxide may he accomplibhrd in furnace hy mean5 of reducing hydrogen atmosphere or suitable propriety ngcnt. After depassiwtion. avoid contamination of surface by finger or hand marking. Single-stage nitriding adequate at 52.5 IO MO “C 1975 to 1020 “F) for 20 to 18 h (depending on case depth requtrsd). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to I350 HK on surface. 1X-h cycle produces GIST extending to 0. I27 mm tO.005 in.) with approximatel) 800 to 1000 HK. Cast \\ill rapid11 drop to 200 HK core hardness. ;II approximately 0.165 mm (0.0065 in.)

Recommended

Processing

Cold work . .Annsal and quench l Remo\s surface contamin;ttion . Stress relk? l Dcpajsl\ate cif nitriding, l Nitride iif required)

Sequence

l

rif required)

Ferritic

Stainless

Steels

Introduction The ferritic stainless steels remain ferritic at all temperatures, theoretically. and thus they are not allotropic and cannot be hardened by heating and quenching. However, this is not always completely true. Some ferritic steels are borderline to the extent that if the chromium is on the low side and the carbon is on the high side some transformation to austenite can take place on heating. This. in turn. can transform to martensite upon cooling. The extent to which this takes place. however, is not usually of great practical significance. Therefore, the principal heat treatment applied to the fenitic grades is annealing, which is usually achieved by rapid cooling from elevated temperature. In their annealed condition. ferritic stainless steels develop maximum softness. ductility. and corrosion resistance. Annealing serves primarily to relieve stresses resulting from welding or cold working. Secondarily, it provides a more nearly homogeneous structure by eliminating patches of transformation product developed during welding or as a result of 475 “C (885 “F) embrittlement. Ferritic steels usually are annealed at temperatures abobe the range for 375 “C (885 “F) embrittlement and below temperatures at which austenitr might form. The table included in this section summarizes current annealing practices for the ferritic grades. Even ferritic grades can retain austenite or untempered martensite from partial transformation to austenite at high temperatures. Aluminum has been added to type 405 to eliminate or minimize austenite formation and decomposition during welding. When fusion welding heats this grade above 1095 “C (2000 “F). embrittlrment may still result. This is corrected by a subsequent heat treatment at 650 to 8 I5 “C ( I200 to IS00 “0. When type 430 is cooled rapidlq from above 925 “C ( I700 “F). it may become brittle from austenite transforming to as much as 30%, martensite. The austenite may be retained, if it is cooled rapidly from temperatures much above 1095 “C (2000 “F). This may be corrected by heating to 760 to81S°C(1400to 1500°F). A form of brittleness peculiar to the ferritic grades can develop from prolonged exposure to. or slow cooling within. the temperature range from about 400 to 525 “C (750 to 975 “F). with a maximum effect variousI) asserted as occurring at 470,475. or -I80 “C (875. 885. or 900 “F). Notch impact strength is most adversely affected. The brittleness is believed to be caused by precipitation of a high-chromium ferrite. Its effects increase rapidly with chromium content, reaching a maximum in type 446. Certain heat treatments. such as furnace cooling for maximum ductility, must be controlled to avoid embrittlement. The brittle condition can be eliminated by any of the treatments listed in the table. using temperatures clearly above the upper boundary of embrittlement. followed by rapid cooling to prevent a recurrence.

Annealing Treatments of Ferritic Stainless Steels Temperature(s) OF 405 4439 429 430 13OF 43OFSe 43-1 136 -I42 446

1350to I500 1625 to l-450 to I400 IO 125010 1250 to I-150 to I-150 to 1350 to l-150 to

1650 1550 I 500 1400 1300 1550 1550 I500 1600

“C

COOliflg method(b)

735 to815 885 IO 900 790 to 845 760 to815 615 to 760 675 to 760 790 10 815 790 to 815 73SlO815 790 to 870

AC or WQ AC AC or WQ AC or WQ AC or WQ AC or WQ AC or WQ AC or WQ AC or WQ AC or WQ

(a~ Time at lemprrature depends on section rhichncss. but is usually I LO2 h. ewepr for sheet which ma! be soaked 3 to 5 min per 2.5 mm (0. IO in J of tickness. (b) AC. air cool: H’Q. ua~erquench

Sigma phase is a crysrallographic constituent that forms slowly at elevated temperatures in straight-chromium steels containing more than about 164 Cr and in chromium-nickel steels containing more than about 18% Cr. Sigma phase increases hardness, which is sometimes useful, but it decreases ductility, notch toughness. and corrosion resistance. The lower temperature limit for its formation depends exponentially on exposure time. For practical purposes. it can be placed near 540 “C (1000 “F). The upper boundary varies with alloy content. Nitriding. In general. the ierritic grades are more easily nitrided than are the austenitic grades. Somen hat deeper cases can be formed on the ferritic grades. using the same practice as used for the austenitic steels described in this Volume. Just as it is true for the austenitic grades. nitriding also impairs corrosion resistance of the ferritic grades. so that applications for nitrided ferritic stainless steels are limited. Forging. For the most part. the allowable forging temperature range for these steels is fairly broad. restricted somewhat at high temperature because of grain growth and structural weakness. Type 305 is the only one of this group for which finishing temperature is closely restricted. This is because this specific grade develops grain boundary weakness caused by debelopmem of small amounts of austenite. Other ferritic grades are commonly finished at temperatures as low as 760 “C (1400 “0. For forging of type -146. the linal IOQ, reduction is preferably made below 870 “C (1600 “F) to achieve grain refinement and room temperature ductility. Forgings of ferritic steels should always be annealed.

760 / Heat Treaters

Guide

405 Chemical

Composition.

AISI~UNS

(~~0500): 0.08 C. 1.00 bJn.

I .OO Si. I 150 to 14.50 Cr. O.WO P. 0.030 S. 0. IO to 0.30 Al

Similar

without significant hardenmg. Not susceptible welding. Ductile. Easily machined

to hardening

cracks during

Steels (U.S. and/or Foreign). AShlE SAUO. SAz68. SM79: ASTM A 176. A2-10. A268.276. A3 I-l. A473. A-)79. AS I I. AS80: FED QQ-S-763: hlfL SPEC hlIL-S-862; SAE J-W iSl-105): (Ger.) DIN l.-tOO?; (Fr.) AFNOR Z 6 CA 13: (1tal.r 1iNl X 6 CrAl 13: (Jap.) JIS SDS -lOS: (U.K.) BS 405 S I7

Forging. Start forging at 1065 to I I20 “C (1950 to 2050 “F). Finish at 870 to 925 “C ( I600 to I695 “F,

Characteristics. Nonhardenahls grade fi here air-hardening tjpes such as 1 IO or -IO3 are objectionable. Can he cooled from elevated temperatures

Annealing. Low anneal remperatures to I SO0 “F). Air cool or water quench

Recommended

Heat Treating

Practice range from 735 to 8 I5 “C ( I355

760 / Heat Treaters

Guide

409 Chemical

COIIIpOSitiOn. AISI/UNS (SJO900): 0.08 C, 1.00 hln. 1.00 Si. 0.50 Ni. 0.045 F! 0.045 S. IO.50 UJ I I .7S Cr. 6 x W min. 0.75 Ti mnx

Similar

Steels (U.S. and/or Foreign).

Al76. A268. A6Sl: !3E.i40S 409: (U.K.) B.S. 409 S I7

(51409~

t&r.,

AShlE SA268: ,ASThl DfN 1.4512: (J~D.) I JIS SLlH

Characteristics. A general purpose construction steel. Intended for application5 u here appearance is secondary to mechamcal and corrosion resistance properties

Recommended Annealing.

Annealing I650 “F). Air cool

Heat Treating temperatures

Practice

range from 885 to 900 “C (I625 to

760 / Heat Treaters

Guide

429 Chemical

Composition. AISIfilNS (s42!300): I.00 Si, I-LOO 11) 16.00 Cr. 0.040 P. 0.030 S

Similar

Steels (U.S. and/or

Foreign).

SA?-68: ASThl .A 176. A 182. X40. A26X. X76. ASS4: FED QQ-S-763. QQ-S-766. QQ-M’-43; SAE J-105 (5 1129)

Characteristics. ueldnbilit~ than tjpr f~\ation equipment

0. I 2 c.

I .oo MO.

ASME SA I x2. SAUO. A3 I -I. A473, A-193. A5 I I. hlk SPEC hlLL-S-863:

This corrosion and heat resisting steel has better 430. Applications include nitric acid and nitrogen

Forging. Start forging at IO-10 to II?0 he as low as 760 T I I400 “F)

Recommended Annealing.

Heat Treating

Temperatures Air cool or water quench

“C ( 1905 to X.50 “F). Finish can

Practice

range from 790 fo 845 “C (1450 fo I550 “F).

760 / Heat Treaters

Guide

430 Chemical

Composition.

AISI/UNS

(S.UOOO): 0. I 2 C. I .OO tvln.

Characteristics.

Gsnsral purpose. nonhardenahle chromium-type and heat resistance properties are superior to 110

I.00 Si. 16.00 to 18.00 Cr. 0.04 P. 0.03 S

lo). Corrosion

Similar

Forging. Start forging at 1040 to I I20 “C (I905 760 10 8 I5 “C ( I400 to IS00 “F)

Steels (U.S. and/or Foreign).

AhIS 5503. 5627: ASME SA 182. SA’40. SA268. SA-179: ASTM A 176. .A 182. ?-\210. A768. A776. 431-I. A473. A479. A-193, ASI I, A55-1. AS80. A65 I: FED QQ-S-763, QQ-S-766. QQ-S-423. STD-66: hlIL SPEC hllL-S-862; SAE J-&OS tSl-l30):(Ger.1DW I.4Olh:(Fr.)AFNORZ8C 17;(Ital.) lJNlX8Cr 17; (Jap.) JIS SUS 130: (Swed.) SSIJ 2320: (U.K.) B.S. 430 S IS

Recommended Annealing. Xnnralinp

Heat Treating

al-

to 2050 “F). Finish at

Practice

Parts are annealed at 760 to 815 “C ( I-100 IO IS00 OF). should b? follo\\ed by Ltater quenching or very rapid cooling

Ferritic

Stainless

Steels / 761

430: Hardness vs Tempering Temperature. Composition: C,0.33Mn,0.020S.0.019P. l.OOSi. 16.96Cr.Barheated400h. Source: Allegheny Ludlum Industries

0.07

Ferritic

Stainless

Steels / 761

430F Chemical

Composition.

AISI/UNS

(S43020): 0. I7 C. I.15 hln.

Forging.

I .OO Si. 16.00 to 18.00 Cr. 0.06 P. 0.15 S nun. 0.6 hlo (optional)

St&art forging at IO65 to I I50 jC ( 1950 to 2 100 “F). Finish at 760to815”C(I400to 1500°F)

Similar

Recommended

Steels (U.S. and/or Foreign). ASTM A314 AS81. ASK?; MIL SPEC Ma-S-862 SAE 1405 (Sl330F): (Ger.) DIN 1.1104: (Fr.) AFNOR Z IO CF 17; (Ital.) CINI X IO CrS 17; tJap.) JIS SUS 130 F: (Swed.) SSt4 2383 Characteristics. Suitable

Free-machining variation for use on automatic screw machmes

of 430 for heavier

cuts.

Annealing. quench

Heat Treating

Practice

Anneal at 675 to 760 “C ( IUS to l-100 “F). Air cool or water

Ferritic

Stainless

Steels / 761

430FSe Chemical

Composition.

AlSI/UNs (S43023): 0.12 C. 1.25 hln.

I .OO Si. 16.00 to IX.00 Cr. 0.06 P. 0.06 S. 0. IS SC min

Similar

Steels (U.S. and/or

AS81. A%?:

MlL SPEC hlfL-S-862:

Foreign).

ASThl

.A? 14.

~473.

SAE J-105 (5 I430FSe)

Characteristics. Free-machining variation of 130 for lighter cuts. Suitable for use in automatic screw machines nttainsd by sclsnium additions

Forging. Start forging at 1065 to I IS0 “C (1950 to 2100 “F). Finish at 760to815”C~14IOto lSOO”F)

Recommended Annealing. u ;Iter quench

Heat Treating

Tempsmture

Practice

is 675 to 760 “C i 17-15 IO 1100 “F). Air cool or

Ferritic

Stainless

Steels / 761

434 1.00 Si. 16.00 to 18.00 Cr. O.-l P. 0.3 S. 0.75 to I.15 hlo

Forging. Start forging at 1040 to I I20 “C (I905 to 2050 “F). Finish can he xi IOU ;1~ 760 “‘C t I-100 “F,

Similar

Recommended

Chemical

Composition.

AI.Sl/UNS

(S43400): 0. I2 C. I .(I0 hln.

Steels (U.S. and/or Foreign). ASTM A65 I; SAE J-105 (51431); (Ger.) DIN I.41 13; (Fr.) AFNOR Z 8 CD 17.01; tltal.) l!NI X 8 Crhlo 17; (lap.) JIS SUS 33-l; (Sued.) SSIA 33; (U.K.) B.S. 13-l S I9 Characteristics. Designed for use as automotke sion because of \rmter road conditioning

trim to resist corro-

Annealing. quench

Heat Treating

Practice

Anneal at 790 to 845 “C t I.455 to IS55 “F). Air cool or water

762 / Heat Treaters

Guide

436 Chemical

Composition. AISI/UNS (S43600): 0.13 C. 1.00 hln. I .OO Si, 16.00 fo 18.00 Cr, 0.04 P, 0.03 S. 0.75 to I.25 MO. 5 X ‘XC min to 0.70 max Nb + Ta Similar

Steels (U.S. and/or

Characteristics. applications. Similar “ridging” is required

Foreign).

SAE J405 (51436)

Adaptable for general corrosion and heat resisting to types 430 and 43-l. Used where low “roping” or

Forging.

Start forging at 1065 to I I20 “C (1950 to 2050 “F). Finish can be as low as 870 to 925 “C ( I600 to I695 “F)

Recommended Annealing. water quench

Heat Treating

Temperature

Practice

is 790 to 835 “C (I455 to 1555 “F). Air cool or

762 / Heat Treaters

Guide

439 Composition. AISl/UNS (S43035):0.07 C. 1.00 Mn. 1.OO Si, 0.50 Ni, 17.00 to 19.00 Cr. 0.04 P, 0.03 S, 0.15 Al, 12 X o/X min

Chemical to l.lOTi

Characteristics.

Recommended Annealing. water quench

A low interstitial

grade

Annealing

Heat Treating

Practice

is at 870 to 925 “C (I600 to 1695 OF). Air cool or

762 / Heat Treaters

Guide

442 Chemical

Composition.

AISI/UNS

(S44200): 0.20 C. 1.00 hln.

I .OO Si. 18.00 to 33.00 Cr. 0.0-l l? 0.03 S

Similar

Steels (U.S. and/Or

Foreign).

ASTM

A 176; SAE J4Os

(51442)

Characteristics.

Used mainly for parts which must resist scaling at high temperatures. Maximum temperature resistance is 980 “C ( 1795 “F) or 1040 “C f 1905 “F) for intermirtent use

Forging. Start forging al 870 to I 150 “C (1600 to 2 100 OF). Fish he as low as 760 “C ( I400 “F)

Recommended Annealing. water quench

can

Heat Treating Practice

Temperature

is 735 to 8 I5 “C ( I355 to 1500 “F). Air cool or

762 / Heat Treaters Guide

446 Chemical Composition.

AISIjUNS

(S44600): Nominal. 0.20 C.

1.50 Mn. 1.00 Si. 23.00 to 27.00 Cr. 0.040 P 0.030 S. 0.25 N

tures. Withstands destructive scaling up to 1095 “C (2005 OF). Often used in sulfur-bearing atmospheres

Similar Steels (U.S. and/or Foreign).

Forging. Suut forging at 1065 to I I20 “C (I950 can be done as IOU as 760 “C ( 1400 “F)

Characteristics.

Recommended Heat Treating Practice Annealina. Anneal at 790 to 870 “C ( 1455 to 1600 “FL

ASME ~~268; ASTM A 176. A268, A276. A3 14, A173. A5 I I. A580; FED QQ-S-763. QQ-S-766: MfL SPEC MlL-S-862: SAE J-IO5 (5 1446)

Has the maximum amount of chromium of ferritic stainless steels. Used for parts which must resist scaling at high tempera-

quenching

to 2050 “F). Finishing

Air cool or water

-

446: Hardness vs Tempering Temperature. Bar heated 400 h. Source: Allegheny

Ludlum Industries

Martensitic

Stainless

Steels

Introduction The martensitic stainless steels represent one portion of the 400 Series of stainless steels. The remainder consists of the fenitic steels. which cannot be heat treated for hardening. The heat treating of the martensitic stainless steels is essentially the same as that for carbon and low-alloy steels. Their potential for developing maximum strength and hardness depends primarily on carbon content. The principal metallurgical difference is the high alloy content of the stainless grades. This causes the transformation to martensite to be sluggish and the hardenability to be high. For these reasons, maximum hardness is produced by air cooling in the center of sections approximately 305 mm (I 3 in.) thick. Chromium is the principal alloying element in these steels. The martensitic stainless steels are more sensitive to heat treating variables than are carbon and low-alloy steels. Therefore, rejection rates because of faults in heat treating are correspondingly high. Because of the initial high cost of these stainless steels and the cost of processing them into parts, there is no advantage in using them unless superior corrosion resistance is required. Consequently, the hardening procedures discussed in this section are limited to those that preserve corrosion resistance. To avoid contamination, all parts and heat treating fixtures must be cleaned completely before they are placed in the furnace. Racks and fixtures should be made of stainless steel or one of several nickel-base alloys containing appreciable amounts of chromium, such as the lnconel alloys. Proper cleaning is particularly important when the heat treatment is to be performed in a protective atmosphere. Martensitic stainless steels are normally hardened by being heated above the transformation range to temperatures of 935 to 1065 “C ( I695 to 1950 “F) and cooled in air. Because of the poor tbemlal conductivity of stainless steels. high thermal gradients and high stresses during rapid heating may cause warping or cracking in some parts. To avoid these problems, preheating is usually recommended before annealing or hardening, especially for thin-gage parts, parts with both thin and thick sections, parts with sharp comers and re-entrant angles. heavily ground parts, parts machined with deep cuts, parts that have been cold formed or straightened. and previously hardened parts that are being reheat treated. Preheating is normally accomplished at 760 to 790 “C ( 1400 to 1455 “F), and heating

need be continued only long enough to ensure that all portions of each part have reached the preheating temperature. Types 403.4 13. and 4 I6 require less preheating than the higher carbon stainless steels, such as 430 and 440. When maximum corrosion resistance and strength are desired. these steels should be austenitized at the high end of the temperature range. For alloys that are to be tempered above 565 “C (I050 “F), the low side of the austenitizing range is recommended. because it enhances ductility and impact properties. Soaking times represent a compromise between (a) achieving maximum solution of chromium-iron carbides for maximum strength and corrosion resistance and (b) avoiding decarburization. excessive grain growth. retained austenite. brittleness. and quench cracking. Because of their high hardenability. all martensitic stainless steels can be quenched in either oil or air. Oil quenching guarantees maximum corrosion resistance and ductility in all alloys. Air quenching may cause some decrease m ductility and corrosion resistance in types 4 14.420.43 I, and 440. These steels may precipitate carbides at grain boundaries. if heavy sections are cooled slowly through the temperature range of approximately 870 to 540 “C (I 600 to 1000 “F). The higher carbon steels, such as 44OC. and the higher nickel -131 are likely to retain large amounts of untransformed austenite in the as-quenched structure, frequently as much as 30% by volume. A portion of the retained austenite may be transformed by subzero cooling (stabilizing), followed by tempering. For Fully hardened steels. increasing degrees of recovery toward the annealed condition are given by (a) stress relieving. (h) tempering, (c) subcritical annealing, and (d) full annealing. The martensitic stainless steels are sometimes nitrided to increase surface hardness and wear resistance and to achieve a lower coefficient of friction. In aerospace practice. austenitizing in atmospheres containing hydrogen is limited to parts to be tempered above 540 “C (1000 “F). Annealing in hydrogen-containing atmospheres is permuted. Atmospheres containing nitrogen at 980 “C ( I800 “F) and higher are not permitted when parts have finished machined surfaces. Endothermic and carbon-containing, nitrogenbase atmospheres are prohibited in treating 13 I or any alloy to 1240 MPa (180 ksi) or higher.

403 Chemical Composition. AISIjUNS (!%0300):0.15 C, I .OObin, 0.50Si, I I .50 to 13.00 Cr. 0.04 P, 0.03 S Similar Steels (U.S. and/or Foreign).

AMS 561 I, 5612; ASTM A 176. A276. A3 14, A473. A479. A508, A5 I I ; FED QQ-S-763; MILSPEC MJL-S-862; SAE J-IO5 (51403); (Ger.) DIN 1.402-l: (Jap.) JIS SUS 303. SUS 416; (U.K.) B.S. 420 S 29, En. 56 B

Characteristics. Special quality grade used for turbine blades and similar applications. Otherwise comparable to type 410. May be quenched in oil or air. Can be martempered. Capable of hardening to 42 HRC or slightly higher. Can be tempered to provide a wide range of strength and impact resistance. Extremely deep hardening. Maximum hardness obtained

by air quenching sections up to approximately 305 mm (I2 in.) thick. Can be full. process, or cycle annealed. Good corrosion resistance. Susceptible to stress corrosion cracking in corrosive environments, when stress is above threshold level for that particular environment. Magnetic in all conditions. Fair machinability. Resists oxidation up to 8 I5 “C ( I500 “F)

Forging.

Start forging at 1095 to 1205 “C (2005 to 2200 “F). Do not forge after temperature of forging stock drops below 870 to 925 “C ( I600 to 1695 “F)

Recommended Normalizing.

Heat Treating

Do not normalize

Practice

764 / Heat Treaters

Annealing. l

l

l

Guide

Can be process. isothermal.

or full annealed:

Process c~nneal in subcritical temperature range of 650 to 760 “C ( I100 to I-KKI “F). Llse clean. rectified salt bath or an atmosphere that is compatible with this temperature range. Soaking time dependent on SIZZ of work. Air cool. Hardness. 86 IO 92 HRB Isorhermol nrrrwul by heating at 830 to 885 “C ( I525 to 1625 “F). Cool slowly to 705 “C (1300 “F). Hold for 6 h. Hardness, approximately 85 HRB FM// annrc~l at 8 IS to 900 “C ( 1500 to 1650 “F). Cool slowly to 595 “C (I I05 “F) at a rate not to exceed I7 to 22 “C (30 to -IO “F) per h. After this. cooling rate has no effect on hardness. Avoid carburization or decarburization. Can use atmospheric protectlon in the form of a \acuum, the inert gases argon or helium (both expsnsive). or nitrogen. All should have dew point belo\{ -5 I “C t-60 “F). Eriothermic- or endothermic-generated atmospheres can be used, providing carbon potential of the gas matches carbon content of the steel. Hardness. 75 to 85 HRB. Full annealing is expensive and time consuming. Should not be used. except as required for subsequent severe foming or difficult machining

In aerospace practice. parts are annealed at 845 ‘C (I555 “F) and austenitized at 980 “C ( 1795 “F). then quenched in oil or polymer. Cooling in air or other gases is permitted for parts less than 6.25 mm (0.250 in.) in maximum thickness proi’ided the) are not racked or densely packed. In annealing, parts are cooled to below 595 “C t I IO5 “F) at a rate not IO exceed 30 “C (55 “F) per h, Followed b) air cooling to ambient. An austenitizing temperature of 955 “C (I750 “Fj is permitted for thin sections to minimize warpage

Hardening.

Atmospheric protection rules for annealing appll to hardening. Parts must be completely clean and free of oil and shop contamination. Thermal conductivit) is significantly loueer than that of carbon and alloy steels. High thermal gradients and hlph stresses during rapid heating ma) cause warpage and cracking in delicate or intricate parts. Preheat at 760 to 790 “C (I 400 to l-155 “F). only long enough to equalize temperature in all sections. Extremely delicate or intricate parts \tould benefit from an additional prior preheat of S-10 “C (I000 “F). Austenitized at 925 IO 1010 “C ( 1695 to I850 “F). Llse upper end of range for larger sections or H hen maximum corrosion resistance and strength are required. If tempering temperature exceeds 565 “C (I050 “F), use IOU side of the austenitizmp

403: Isothermal Transformation

Diagram. Composition: 0.15 C max, 1 .OO Mn max, 0.040 P max, 0.030 S max, 0.05 Si max, 11.50 to 13.00 Cr. Austenitized at 980 “C (1795 “F). As-quenched hardness. 41 HRC

range. It enhances ductilit) and impact resistance. Soaking time of 30 to 60 min is adequate for sections up to I3 mm (0.50 in.). Allow an additional 30 min for each additional inch or fraction thereof. Double soaking time if parts have been full or isothermal annealed. Increase time by 50%. if process annealed for long periods above 705 “C ( I300 “F). Quench in oil or air. Oil quenching preferred. because it guarantees maximum corrosion resistance and ductility. hlartempering in hot oil or salt is practicable because of high hardenability. As-quenched hardness, approximately 375 10415 HB

Stabilizing. Optional. To transform essentially all retained austenite. use stabilizing or subzero treatment of -76 to -195 “C (-105 to -320 “F). Temper immediately to temper the new martensite to avoid cracking Tempering.

Temper at 205 to 760 “C (400 to I400 “F). Temper at 705 to 370 “C t-IO0 to 700 “F) for hardness approximately 38 to 45 HRC. Temper at 565 IO 605 “C ( 1050 to I I75 “F) for hardness approximately 25 to 3 I HRC. Tempering at 370 to 650 “C (700 to I200 “F) not recommended for parts requiring high toughness and optimum corrosion resistance. Causes a marked dip in impact resistance and lowered stress corrosion cracking resistance. Double tempering beneticial. Cool to room temperature between tempers

Nitriding. Can be nitrided to case depth of approximately in 18 h. See type -IlO for further information

Recommended l l l l l l l l l l l l

Processing

0.103 mm (0.008 in.)

Sequence

Forge Anneal Rough machine Stress relieve Finish machine Preheat Austenilize Quench Stabilize (optional) Temper Final grind to size Nitride (if required)

403: Hardness vs Tempering Temperature. Composition: 0.10 to0.115C,0.30to0.45Mn,0.014to0.018P,0.012Smax,0.28to 0.45 Si, 12.18 to 12.34 Cr, 0.34 to 0.63 Ni, 0.02 to 0.08 MO. Heat treated at 1010 “C (1850 “F), ‘;2 h. Oil quenched: 66 to 94 “C (150 to 200 “F). Double stress relieved at 175 “C (345 “F), 15 min. Water quenched. Tempered 2 h. Heat treated, 14 mm (0.550 in.) round. Tested, 12.8 mm (0.505 in.) round. Source: Republic Steel

Martensitic

403:

Soak Time for Annealing

and Austenititing

(Aerospace

mm

Up105 St0 I5 IStO

25 IO40 4Oto50 50 to 65 65 10 75 15 IO 90 9010 loo loot0 Il.5 1151011. 125 t07-00 Over 20

In.

b

Up IO0.250 -_ to 0.500 Over O.‘W OwrO.SOO to I .OOO O\er I .OOOto I .SOO Over I .SOO to 2.000 Over 2.OOO to 2.500 Over 2SOO to 3.000 Over 3.0 to 3.SOO O\er 3.500 to-LOW Ober 4.000 to -1.SM) Over 4.500 to S.000 Over 5 BOO to 8 000 Over 8 000

Minimum time(b)

min

hours

soak salt min I8 35 40 45 SO 55

25 -Is I I I I 2 2 2 2 3 ? (Cl

Steels / 765

Practice)

hlinimum soak time(b) air or atmosphere

Thickness(a)

Stainless

IS 30 -IS IS 30 -IS

I I I I

S IO IS

,O

I I

‘0 -IO

td)

(a)Thickness is the minimum dimension of the heaviest section of the part tb) Soaking shall commence N hen all control. indicating. and recording thermocouples reach the specitied set temperature, or if load thermocouples are used, uhsn the part temperature reaches the minimum of the furnace uniformity tolerance at the set temperature. Parts coated B ith copper plate or similar reflective coatings that tend to reflect radiant heat shall have their soaking time increased by at least SO0‘0, unless load thermocouples are used. When load thermocouples arc used. the soaking time shall be not less than 30 rnmutes. In all cases, the parts shall be held for sufticwnt time to ensure that the center of the most massive area has reached temperature and the necessary transformauon and diffusion have taken place. hlaximum soak time shall be nvw the minimum specified, except for subcritical .mnraling. Longer times may be necessary for parts wnh complex shapes or parts that \\on’t heat uniformly. (c)-l h plus 30 mm for s~cry 75 mm (3 in.), or portion thereofgreater than 200 mm (8 in.). (d) 2 h plus 20 mm for every 75 mm (3 in.). or portion thereof grealer than 200 mm (8 in.). Source: AMS 2759’5

403: Partial Isothermal Transformation

Diagram. Modified turbine grade. Composition: 0.074 C, 0.39 Mn, 0.034 P, 0.010 S, 0.27 Si, 0.30 Ni, 12.22 Cr, 0.52 MO, 0.039 N. Austenitized at 1065 “C (1950 “F). Grain size: 6 to 8

403: Hardness vs Tempering Temperature. Composition: 0.115 C, 0.45 Mn, 0.014 P, 0.012 S, 0.45 Si, 12.18Cr, 0.63 Ni, 0.08 MO. Heat treated at 925 “C (1695 “F), l/z h. Oil quenched: 66 to 94 “C (150 to 200 “F). Double stress relieved at 175 “C (345 “F), 15 mm. Water quenched. Tempered 1 h. Heat treated, 14 mm (0.550 in.) round. Tested, 12.8 mm (0.505 in.) round. Source: Republic Steel

Martensitic

Stainless

Steels / 765

410 Chemical

Composition.

~rsr/l!NS (!GlOOO):0. I5

C. I .OO hln.

I .OO Si, II .SO to 13.50 Cr. 0.W P, 0.03 S

Similar

Steels (U.S. and/or

Foreign).

ALIS 550-I. 5405. 5591.

5613. 5776, 5821; ASME S4194 (6). SAWO. SA268. SA-+79: ASThl A176.A193,A19~.A2-t0,A376.A?I-l,A173.A-179. MY?. A5ll.AS80; FED QQ-S-763. QQ-W-r23: hllL SPEC hIIL-S-862; WE J-IO.‘, (51-110). JJlZ~514lO):tGer.)DIN l.1006:(Fr.~AFNORZ IOC 13.Z IOC 1-l.Z I2 C 13;(Ital.)UNIX I?Cr 13.X IOCr 13,X IZCr I3 KG.X l2Cr 13KKH’: (Jap.) JIS SUS -IlO; (Sued.) SS.14 2302: (U.K.) B.S. -IlO S 21. En. 56 A. ANC I Grade A. 3 S. 61. S. I41

Characteristics.

General purpose. heat treatable stainless steel. Corrosion resistant and heat resistant. Capahls of hardening to 42 HRC or slightI!

higher. Can he tempered to \\ ids range of strength and impact resistance. Can be quenched in oil or air. Oil quenching guarantees maximum corrosion resistance. Hiph alloy content causes sluggish transfomration and high hardenability. For these reasons. maximum hardness is obtainable by air quencJ.krg in the center of sections up to approximately 305 mm (I 2 in.) thick. Can be martempered with ease. Can be titll. process. or isothermal annealed. Has good corrosion resistance. Susceptible to stress corrosion cracking in corrosive em ironment~. when stress is above threshold level for that particular environment. hlapttc in all conditions. Fair machinahilitj. Resists oxidation up to 8 I5 “C t IS00 “F)

Forging.

Snut forging at IO95 to 120s “C t2OOS to 2200 “F). Do not forge after tempernture of forging stock drops below 870 to 925 “C t 1600 to 1695 “F)

766 / Heat Treaters

Recommended Normalizing. Annealing. l

l

l

Guide

Heat Treating

Practice

Do not normalize Can be process, isothermal.

or full annealed:

Process onneal in subcritical temperature range of 650 to 760 “C t I200 to 1400 “F). Use clean. rectified salt bath or an atmosphere that IS compatible with this temperature range. Soaking time dependent on size of work. Air cool. Hardness, 86 to 92 HRB Isorhetmal anneul by heating at 830 to 885 “C (I 525 to I625 “F). Cool slowly to 705 “C (1300 “F). Hold for 6 h. Hardness, approximately 85 HRB Full cmwal at 830 to 885 “C ( I525 to I625 “F). Cool slowly to 595 “C (I IO5 “F) at a rate not to exceed I7 to 22 “C (30 to 10 “F) per h. After this. cooling rate has no effect on hardness. Avoid carburization or decarburization. Can use atmospheric protection in the form of a vacuum, the inert gases argon or helium (both expensive). or nitrogen. All should have dew point below -5 I “C (-60 “F). Exothermic- or endothermic-generated atmospheres can be used, providing carbon potential of the gas matches carbon content of the steel. Annealed hardness, 75 to 85 HRB. Full annealing is expensive and time consuming. Should not be used. except as required for subsequent severe forming

In aerospace practice. parts are annealed at 845 “C ( I555 OF’) and austenitized at 980 “C ( 1795 “F), then quenched in oil or polymer. Cooling in air or other gases is permitted for parts less than 6.25 mm (0.250 in.) in maximum thickness, provided they are not racked or densely packed. In annealing. parts are cooled to below 595 “C ( I IO5 “F) at a rate not to exceed 30 “C (55 “F) per h. followed by air cooling to ambient. An austenitizing temperature of 955 “C ( 1750 “F’) is permitted for thin sections to minimize watpage

Hardening. Atmospheric protection rules for annealing apply to hardening. Parts must be completely clean and free of oil and shop contamination. Thermal conductivity is significantly lower than that of carbon and alloy steels. High thermal gradients and high stresses during rapid heating may cause warpage and cracking m delicate or intricate parts. Preheat at 760 to 790 “C (I400 to 1455 ‘F). only long enough to equalize temperature in all sections. Extremely delicate or intricate parts would benefit from an additional pnor preheat of 540 “C (I000 “F). Austenitized at 925 to 1010 “C (I 695 to I850 ‘F). Use upper end of range for larger sections or when maximum corrosion resistance and strength are required. If tempering temperature exceeds 565 “C (1050 “F), use low side of the austenitizing range. It enhances ductility and impact resistance. Soaking time of 30 to 60 min is adequate for sections up to I3 mm (0.50 in.). Allo& an additional 30 mm for each additional inch or fraction thereof. Double soaking time if parts have been full or isothermal annealed. Increase time by 50%, if process annealed for long periods above 675 “C ( I245 “F). Quench in oil or air. Oil quenching preferred, because it guarantees maximum corrosion

resistance and ductility. Martempering in hot oil or salt is practicable because of high hardenability. As-quenched hardness, approximately 375 to 415 HB

Stabilizing. To transform essentially all retained austenite, use stabilizing or subzero treatment of -76 to -195 “C (-105 to -320 “F). Temper immediately to temper the new martensite to avoid cracking Tempering.

Temper at 205 to 705 “C (400 to I300 “F). Temper at 205 to 370 “C (400 to 700 “F) for hardness approximately 38 to 47 HRC. Temper at 565 to 605 “C ( 1050 to I I25 “F) for hardness approximately 25 to 3 I HRC. Tempering at 370 to 565 “C (700 to I050 “F) not recommended for parts requiring high toughness and optimum corrosion resistance. Causes a marked dip in impact resistance and lowered stress corrosion cracking resistance. Double tempering beneficial. Cool to room temperature between tempers

Nitriding. Not recommended for severe corrosive environment. Nihided case impairs resistance to corrosion in most media. Maximum case obtainable is about 0.203 mm (0.008 in.) in 48 h. Before nitriding. parts should be quenched and tempered. uith tempering at least I4 “C (25 “F) higher than the nitriding temperature. All sharp comers should be replaced with radii of not less than I.588 mm (0.06 in.). The ftlm of oxide that protects stainless alloys from oxidation and corrosion must be removed. This may be accomplished by wet blasting, pickling. chemical reduction in a reducing atmosphere. submersion in molten salts. or by one of several proprietary processes. If doubt exists that complete and uniform depassivation has occurred. further reduction of the oxide may be accomplished in a furnace by reducing hydrogen atmosphere or suitable proprietary agent. After depassivation. avoid contamination of surface by linger or hand marking. Single-stage nitriding usually adequate at 525 to 550 “C (975 to 1020 “F) for 20 to 48 h. depending on case depth required. Hardness above 1000 HK can be expected for several thousandths of an inch before hardness gradient blends into core

Recommended l l l l l l l l l l l l

Processing

Forge Anneal Rough machine Stress relieve Finish machine Preheat Austenitize Quench Stabilize (optional) Temper Final grind to size Nitride (if required)

410: End-Quench

Hardenability

Sequence

Martensitic

Stainless

Steels

/ 767

410: Isothermal Transformation Diagram. Composition: 0.11 C, 0.44 Mn, 0.37 Si. 0.16 Ni, 12.18 Cr. Austenitized at 980 “C (1795 “F). Grain size, 6 to 7

410: Isothermal Transformation Diagram. Modified 410. Composition: 0.22 C, 0.54 Mn. 0.64 Ni. 12.46 Cr, 0.99 MO. 0.29 V. Austenitized at 1010 “C (1850 “F). Grain size, 4 to 5

410: Hardness

vs Tempering

Temperature.

(a) Quenched from 925 “C (1695 “F). (b) Quenched from 1010 “C (1850 “F)

768 / Heat Treaters

Guide

410: Dilatometric Curve. Effects of cooling rates on transfonnation of a chromium stainless steel. Composition: 0.098 C, 0.41 Mn,0.023P.0.010S,0.62Si,0.30Ni.12.30Cr,0.03Mo,0.21Cu. Region of Ar, to Ar, transformation is for slowly cooled dilatometer tests. Ferrite and carbide formation occurs through this range, on slow cooling. Continuation of cooling curves through transfonnation of austenite to martensite, starling at M, point and finishing at M, point. Note the large amount of expansion typlcal of the martensite reaction. Source: Republic Steel

410:

Soak Time for Annealing

and Austenitizing

Thickness(a) tIltI’

in.

Up 10 5 St0 IS

up to 0.250 O\cr 0.250 to O.SOO O~erO.SOOto I OOO Oier l.OfXJto I SW Oicr I.SOOto1OOO O~er1.OOOtoI?.5OO Over 2.500 to 3.OOO O\er 3.ooOto 3.5OO O\er 3.500 to -l.ooO Over 1 COOto 1.500 O\er -1.SMl to S.OOO O~erS.OOOto8CMIO O\tr8OOU

151025 25 to Xl -IO to so 50 to 65 65 to 75 75 IO 90 9010

loo

IIS ll510l2. I2.i 102GO O\er 200 10010

(Aerospace

Practice)

Minimum soak Time (b.c,d,e,f) air or atmosphere I’ min

Minimum soak Tie (b,c,d,ef) salt h

25 -Is

I8 3s -lo 15 so 55

I5 30 -IS IS 30 -4s 30

min

I’ I I I I I

5 IO IS 20 -lo

(a) Thickness is the minimum dimension of the hea\ lest wction of the pan. (b I Soaking shall commence N hen all xmtrol. tndicattng. and recording thermocouples reach the specilied set temperature. or if load thermocouples are used. u hen the part temperature reaches the minimum of the furnace unifcwnity tolerance itt the set temperature. Parts coated with copper plate orsinlilarreflectt\e coatings that tend to rekct radiant heat shall hate their waking time increased b> al least SOq. unless load thermocouples are used. (c)When load thermocouples are used. the c&ing time shall be not less than 30 min. td I In all cases. the parts shall be held for suftisicnt time to ensure that the center of the most massike area has reached temperature and the necessary transformation and diffuston hs\c taken place. (CI hlalimum soah time shall be nrice the mintmum specitied. ekccpt for subcritical annealing tf~ Longer times ma) he necess~ for parts with complex shapes or parts thnr \son’t hrnt unit&ml). ~gt -I h hour plus 30 mtn for r\en 75 mm t 3 in.,. or portion thereofgreater thanXOmm~8 in.). (ht 2 hplus XJmtn forcleq 75 mm 13 in.).orportionthcreofgreatrtrthan 2OOmmtSin.t. Source: .~hlS 27SXS

Martensitic

Stainless

Steels

/ 769

410: Microstructures. (a) Kalling’s reagent, 100x. Stainless-steel in as-forged condition. Hot worked structure is banded delta ferrite (horizontal, light) in martensite matrix. (b) Vilella’s reagent, 100x. Stainless steel, as-forged. Hot worked structure consists of larger, more elongated banded delta ferrite than (a), in martensite matrix. (c) Vilella’s reagent, 100x. Forging. Hardened by: holding 1 h at 980 “C (1795 “F); air quenched: tempered 2 h at 565 “C (1050 “F); and air cooled. Tempered martensite and carbide. (d) Vilella’s reagent, 500x. Strip hardened by rapid air cooling from 980 “C (1795 “F) to room temperature. Tempered 4 h at 205 “C (400 “F). Martensite with precipitated carbide particles. Oblique illumination. (e) Vilella’s reagent, 500x. Strip annealed by holding at 815 “C (1500 “F). Furnace cool to 595 “C (1105 “F). Air cool to room temperature. Matrix of equiaxed ferrite grains with randomly dispersed particles of chromium carbide. (f) Electrolytic: HCImethanol, 500x. Strip in hardened condition: after annealing at 800 “C (1475 “F); holding for 30 min at 955 “C (1750 “F); and air cooled. Ferrite-free martensite. (g) Electrolytic: HCI-methanol, 500x. Same as (f), except less balanced composition. Causes martensite matrix to have islands of ferrite (white). (h)Super picral, 250x. Section through rolled thread on hardened fastener. Austenite reversion at surface, resulting from nitrogen pickup during heat treatment. (j) As-polished, not etched. 100x. Forging: hardened and tempered. Quench crack acquired oxide scale during air tempering.

(continued)

770 / Heat Treaters

Guide

410: Microstructures (continued).(k) Vilella’s reagent, 100x. Same as (j). After etching, the crack was accentuated and revealed tempered martensite and carbide. (m) Super picral, 500x. Hardened and tempered. Cross section shows as-machined surface, after electrochemical machining. Note complete absence of disturbed metal

770 / Heat Treaters

Guide

414 Chemical

COITIpOSitiOn. I .OO Si. 1.25 to 2.50 Ni, Il.50

AISl/UNS (SJ1400): 0.15 c. to 13.50 Cr. 0.04 l? 0.03 S

1.00 hln.

amount of nickel present m the particular ing not recommended

heat being annealed. Full anneal-

Forging. Start forging at Il.50 to 1205 “C i2 100 to 2200 OF). Do not forge after temperature of forging stock drops below 870 to 980 “C ( I600 to I795 “F). Cool slowly from finishing temperature. Anneal

Hardening. Can use atmospheric protection in the form of vacuum, inert gas. salt baths. endothermicor exothermic-generated gas. Parts must be completely clean and free of oil and shop contamination. Thermal conductivity is stgnificantly lower than that of carbon and ahoy steels. High thermal gradients and high stresses during rapid heating may cause warpage and cracking in delicate or intricate parts, Preheat at 760 to 790 “C ( I-100 to I-155 “F). only long enough to equalize temperature in all sections. Estremely delicate or mtricate parts uould benefit from an additional prior preheat of 510°C (lOOOY=). Austenitized at 925 to 1050°C (1695 to 1920 “FL Use upper end of range for larger sections or when maximum corrosion resistance and strength are required. If tempering temperature exceeds 565 “C (I050 “F), use low side of the austenitizing range. It enhances ductility and impact resistance. Soaking time of 30 to 60 min is adequate for sections up to I3 mm (0.50 in. j. Allow an additional 30 min for each additional inch or fraction thereof. Increase soaking time by at least 50% if process annealed for long periods above 675 “C (I 245 “F). Quench in oil or air. Oil quenching preferred. because it guarantees maximum corrosion resistance and ductility. Mutempering in hot oil or salt is suitable because of high hardenability. As-quenched hardness. approximately 388 to -I56 HB

Recommended

Stabilizing.

Similar

Steels (U.S. and/or

Foreign).

AhlS 561% ASTM A276.

A3I-t,A173.ASII.AS80;FEDQQ-S-763;SAEJ10S(SIll-tj

Characteristics. Similar to type -I IO. Nickel added to increase corrosion resistance and strength. Capable of hardening to approximately 15 HRC. Requires about 28 to 32 “C (55 to 75 OF) higher tempering temperature than type 110 to attain same final hardness. Can be quenched in oil or air. Can be martempered. Oil quenching guarantees maximum corrosion resistance. High alloy content causes sluggish transformation and high hardenability. For these reasons. maximum hardness is obtainable by air quenching in center of sections up to approximately 305 nun ( I2 in.) thick. Annealing restricted to process anneal. Good corrosion resistance. Susceptible to stress corrosion cracking in corrosive environments. when stress is above threshold level for that particular environment. Magnetic in all conditions. Fair machinability

Normalizing. Annealing.

Heat Treating

Practice

Do not nomlalize

For best machinability. heat to 955 ‘C ( 1750 “Fj. Temper from 650 to 730 “C ( 1300 to I350 “Fj. Annealed hardness, 99 HRB to 2-t HRC. When the steel is to be subsequently hardened and tempered. tempering at 650 to 730 “C ( I200 to I350 “Fj is sufficient for good machinability. When this treatment does not provide machinability necessary for high-speed tools. it may be advantageous to air cool steel from lo\{ temperature. 815 to 84.5 “C (IS00 to IS55 “Fj. with subsequent temper at 620 to 705 “C ( I I SO IO I300 “F). Exact temperature range go\ emed by actual

To transform essentially all retained austenite. use stabilizing or subzero treatment of -76 to -195 “C (-105 to -320 OF). Temper immediately to temper the new martensite to avoid cracking

Tempering.

Temper at 230 to 650 “C (4.45 to I200 “F). Temper at 230 to 370 “C (US to 700 “F) for hardness approximately 45 HRC. Temper at 595 to 650 “C ( I I OS to I200 “F) for hardness approximately 25 to 3 I HRC. Tempering at 370 to 59s “C (700 to I IO5 “F) not recommended for parts requiring high toughness and optimum corrosion resistance. Causes a marked dip in impact resistance and lowered stress corrosion cracking resistance. Double tempering beneficial. Cool to room temperature bet\\ een tempers

Martensitic

Nitriding. Can be nitrided to case depth of approximately (0.008 in.) in 48 h. See type 410 for further information

0.203 mm

l l l

Recommended l l l l

Processing

Sequence

Forge Anneal Rough machine Stress relieve

414: Hardness vs Tempering Temperature. Composition: 0.13 C,0.54Mn,0.021 P,O.O23S,O.34Si, 1.77Ni, 13.36Cr,O.l9Mo. Heat treated at 1040 “C (1905 “F), VZJh. Oil quenched at 66 to 94 “C (150 to 200 “F). Double stress relieved at 175 “C (345 “F), 15 min. Water quenched. Tempered 2 h. Heat treated, 14 mm (0.550 in.) round. Tested, 12.6 mm (0.505 in.) round. Source: Republic Steel

l l l l l

Stainless

Steels / 771

Finish machine Preheat Austenitize Quench Stabilize (optional) Temper Final grind to size Nitride (if required)

414: Hardness vs Tempering Temperature. Composition: 0.13 C, 0.54 Mn, 0.021 P, 0.023 S, 0.34 Si, 1.77 Ni, 13.36 Cr, 0.19 MO. Heat treated at 925 “C (1700 “F), l/2 h. Oil quenched at 66 to 94 “C (150 to 200 “F). Double stress relieved at 175 “C (345 “F), 15 min. Water quenched. Tempered 2 h. Source: Republic Steel

414: Dilatometric Curves. Composition: 0.104 C, 0.46 Mn, 0.019 P, 0.012 S, 0.32 Si, 1.86 Ni, 12.55 Cr, 0.08 MO. Transformation characteristics shown. Source: Republic Steel

772 / Heat Treaters

Guide

414: Isothermal Transformation Diagram. Composition: 0.10 C. 0.46 Mn. 0.018 P, 0.015 S, 0.33 Si, 1.86 Ni. 12.65 Cr, 0.05 MO. Austenitized at 1040 “C (1905 “F). Rockwell C hardness measured after 24 h at isotherm. Source: Republic Steel

414: Hardness vs Tempering Temperature. 1010 “C (1850 “F). Oil quenched. Tempered 2 h at temperature indicated

772 / Heat Treaters

Guide

416,416Se Chemical

Composition.

416. AISI/UNs

(S41600): 0. IS C. I.3

hln.

1.00 Si, 11.00 to 14.00 Cr. 0.06 P, 0.15 S nin, 0.6 hlo (optional). 416Se. AISI/UNS (S41623): 0. IS C. I .3 hln. I .OO Si. 12.00 to 11.00 Cr. 0.06 P. 0.06 S. 0. IS Se min

Similar

SAl9-k Steels (U.S. and/or Foreign). 416. AWE ASThl A IW. A3 I-!. A473. ASXI. AS82 FED QQ-W-43: hllL SPEC hllL-S-862: SAE J4OS (Sl-llh): (Ger., DIN 1.4005: tFr.j AFNOR Z I2 CF 13; (Ital.) LINI X 12 CrS 13; tSwed.) SSIJ 380: (U.K.1 B.S. 416 S 21. J16Se.4hlSS6l0:AS~~SAl9-1:ASThlAl91,A3I~.A172..L\SlI.A5Xl. AS82: hllLSPEC MU--S-862; SAE J-IO5 (51416 Se)

Characteristics. Another version of tj pe 4 IO, M here S (tl pr 4 I6 I or Se (t)pe 116Se) has been added to improve mashinabilitj. Popular selection for machining m screw machines or turret lathes. Capable of hardening to 42 HRC or slightly higher. Can be tempered to wide range of strength and impact resistance. Deep hardening. Oil quenching recommended. Can be martempered. Tempering in the 370 to S6S ‘C (700 to 1050 OF) range lowers impact resistance. Can be full. process, or isothermal annealed. Good nonseizing and nongalling properties. Good corrosion resistance. Susceptible to stress corrosion cracking in corrosive en\ ironments. u hen stress is aho\? threshold Ir\el for that particulluem ironmsnt. Magnetic in all conditions. Resists oxidation up to 760 ‘C ( 1-U) “F) Forging. Not recommended for forging operations requiring seterr deformation. Sulfur or selenium. added to enhance machinabilit\. tends to create hot shortness. When forged. start forging at I I SO to I260 ‘C (2 100 to 2300 “F). Do not forge after temperature d forging stock drops helou 870 to 980 “C f I600 to 179s “Fj

Recommended Normalizing. Annealing.

Heat Treating

Practice

Do not normalize Can be prows>.

isothermal.

or full annealed:

Procrss wrwtrl in subcritical tempsrature range of 650 to 760 “C (IZOO to IWO “Ft. Lke clean. rectified salt bath or an atmosphere that is compatible with this temperature range. Soaking and softening time dependent on size of work. Air cool. Hardness. 86 to 92 HRB /sor/wwrc~/ mtrtwl hy heating at 830 to 885 “C ( IS3 to I635 OF). Cool blo\s I> to 720 “C ( I330 “F). Hold for 2 h. Hardness. approximately 85 HRB Full mtteal at 830 to 885 “C (153 to 1625 OF). Cool slowly to 595 “C t I IO5 “F) at a rate not to exceed I7 to 12 “C (30 to 10 “F) per h. After this. cooling rate has no effect on hardness. Avoid carburization or decarburization. Can use atmospheric protection in the form of a vacuum. the inert gases argon or helium (both expensive), or nitrogen. All should ha\ e dew pomt belo\\ -5 I “C (-60 “F). Exothermic- or endothermic-generated atmospheres can he used, providing carbon potential of the gas matches carbon content of the steel. Hardness. 75 to 85 HRB. Full annealing is expenke and time consuming. Should not be used. swept as required for subsequent severe foming ln aerospace practice, parts are annealed at 870 “C (1600 “F) and austenitized at 1015 “C ( I875 “F). then quenched in oil or polymer. In annealing, parts are cooled to heIoN 595 “C ( I IO5 “F) at a rate not to exceed 30 “C (55 “F) per h, follo\red b> air cooling to ambient. An austenitizing temperature of 95 “C I I750 “F) is pemitted for thin sections to minimize warpage

Hardening. Atmospheric protection rules for annealing apply to hardening. Parts must be completely clean and free of oil and shop contamination. Thermal conductl\it) IS significantly lower than that of carbon and allo) steels. High thermal gradients and hph stresses during rapid heating ma) cause irarpage and cracking in delicate or intricate parts. Preheat at 760 to 790 “C ( I100 to 1455 ‘Fj. only long enough to equalize temperature in all sections. Extremely delicate or intricate parts would benefit from an additional prior preheat of S-IO “C ( 1000 OF). Austenitized at 925 to 1010 “C t 1695 to I850 “Fj. Llse upper end of range for larger sections or when masimum corrosion resistance and strength are required. lf tempering

Martensitic temperature exceeds 565 “C (IO50 “F), use low side of the austenitizinp range. It enhances ductility and impact resistance. Soaking time of 30 to 60 mitt is adequate for sections up to I3 mm (0.50 in.). Allow an additional 30 min for each additional inch or fraction thereof. Double soaking time if parts have been full or process annealed. Increase time by SO%, if process annealed above 675 “C (I245 “F). Oil quench. Martempering in hot oil or salt is suitable because of high hardenahility. As-quenched hardness, approximately 375 to 4 IS HB

Stabilizing.

To transform essentially all retained austenite, use stabilizing or subzero treatment of -76 to -195 “C (-105 to -320 “Fj. Temper immediately to temper the near martensite to avoid cracking

Temper at 205 to 760 “C (300 to l-IO0 “F). Temper at 205 to 370 “C (100 to 700 “F) for hardness approximately 35 to -IS HRC. Temper at 565 to 605 “C ( 1050 to I I25 “F) for hardness approximately 25 to 3 I HRC. Tempering at 370 to 565 “C (700 to 1050 “FJ not recommended for parts requiring high toughness and optimum corrosion resistance. Causes a marked dip in impact resistance and lowered stress corrosion cracking resistance. Double tempering beneficial. Cool to room temperature hetvveen tempers

416: Hardness vs Tempering Temperature. Composition:

0.11 C, 0.87 Mn, 0.018 P, 0.360 S, 0.42 Si, 0.33 Ni, 13.08 Cr, 0.09 MO. Heat treated at 980 “C (1795 “F), li2 h. Oil quenched at 66 to 94 “C (150 to 200 “F). Double stress relieved at 175 “C (345 “F). 15 min. Water quenched. Tempered 2 h. Heat treated 14 mm (0.550 in.) ?ound. Tested, 12.8 mm (0.505 in.) round. Source: Republic Steel

416: Microstructures.

Steels / 773

Nitriding. Can be nitrided to case depth of approximately 0.203 nun (0.008 in.) in approximately 38 h. See type 310 for further information

Recommended l l l l l l l l

Tempering.

Stainless

l l l l

Processing

Sequence

Forge Anneal Rough machine Stress relieve Finish machine Preheat Austenitize Quench Stabilize (optional) Temper Final grind to we Nitride (if required)

416: Partial Isothermal

Transformation Diagram. Free-machining steel. Composition: 0.12 C, 0.79 Mn. 0.017 P. 0.190 S, 0.74 Si. 0.25 Ni. 12.82 Cr, 0.05 MO. 0.037 N. 0.08 Zr. Austenitized at 980 “C (1795 “F). Grain size, 7 to 9

(a) Polished, not etched. 250x. Bar stock with 0.150 S max, to promote chip breakage and improve machinability. Longitudinal section. Cross section shows elongated, stnnger-type inclusions of manganese sulfide (horizontal dark streaks). (b) Vilella’s reagent, 500x. Bar, austenitized at 980 to 1010 “C (1795 to 1850 “F). Oil quenched. Tempered at 565 “C (1050 “F). Stringers of manganese sulfide (dark) and blocky ferrite (light, outlined). Matrix of tempered martensite. (c) 596 picric acid and 19,” hydrochloric acid, 750x. Bar in annealed condition. Longitudinal cross section. Delta ferrite (light etching) in matrix of tempered martensite. Stringers of manganese sulfide (dark, elongated)

774 / Heat Treaters

Guide

416: isothermal Transformation Diagram. Free-machining steel. Composition: 0.10 C, 0.94 Mn, 0.025 P. 0.350 S. 0.44 Si, 0.31 Ni, 12.40 Cr, 0.44 MO. Austenitized at 900 “C (1650 “F). Source: Republic Steel

416: Hardness vs Tempering Temperature. Composition:

0.11 C, 0.87 Mn, 0.018 P, 0.360 S, 0.42 Si, 0.33 Ni, 13.06 Cr, 0.09 MO. Heat treated at 925 “C (1695 “F), ‘12h. Oil quenched at 86 to 94 “C (150 to 200 “F). Double stress relieved at 175 “C (350 “F), 15 min. Water quenched. Tempered 2 h. Heat treated 14 mm (0.550 in.) round. Tested, 12.8 mm (0.505 in.) round. Source: Republic Steel

Martensitic

416:

Soak Time for Annealing

and Austenitizing

Tbicknfs(a)

mm

in.

up 10 5 510 IS 15 1025 2s to 30 JO to so SO IO 65 65 to 75 75 10 90 9oro loo lOOto 11s 11510 125 125 to200 Over 200

up to 0.250 Over 0.250 10 0.500 Over 0.500 10 I .OOO Over I .OOO10 I.500 Ober I.500 10 2.000 Over 2.000 10 2.500 O\er 2.SOO 10 3.000 Over 3.ooO to 3.900 Ober 3.SOO 10 1.000 0ver4.000~04.500 Over J.500 10 5.000 Over 5.000 10 8.GOO Oker 8.OOO

(Aerospace

Stainless

Steels / 775

Practice)

Minimum soak Tie (b,c,d,efi air or atmosphere II min

Minimum

Tie b

25 15

soak

(b,c,d,ef) salt min I8 35 40 4.5 SO 55

I5 30 45 I I

IS 30 4s

I

SO

I I Ih)

I

‘i IO IS 20 10

(a) Thickness is the minimum dimension of the heal iesI section of the pan. I b) Soaking shall commence u hen all control. indicating. and recording lhermocouples reach Ihe specitied set temperature. or if load thermocouples are used, when the pan temperature reaches rhe minimum of Ihe furnace uniformir) tolerance at the set rrmperature. Pans coated with copper plate or similar rekctive coaungs rhar rend IO reflecl radiant heal shall hate their soaking lime increased by a~ leas1 SOCr. unless load thermocouples are used. (c) When load thermocouplesare used. the soaking time shall be not less than 30min. (d) ln all czxs. the parts shall be held for sufficient time tornsure [hat the centerof the most massitearea has reached temperature and the necessary lmnsformation and diffusion have taken place. (e I hlaxlmum soak time shall be IN ILX the mimmum specified. except for subcritical anneallng. (0 Longer times mav be necessaq for pcins with complex shapes or par& that won’t heat uniformI>. (go 1 h hour plus 30 mm for cveq 75 mm (3 in. ). or ponion thereof greater than 200 mm (8 in.). (h) 5 h plus 20 mm for ever) 75 mm (3 in.), or portion thereof greater than 200 mm (8 in 1. Source: AI\lS 1759/S

Martensitic

Stainless

Steels / 775

420,420F Composition. 420. AlS1pJN.S(S42000):0.15 C min. I .OO Mn. 0.04 P. 0.03 S. 1.00 Si. 12.00 IO 14.00 Cr. J20F. (UNS S42020): 0.15Cmin. 1.2SMn. l.OOSi. 12.00to l-L00Cr.0.06P,O.lSSmin.0.6hlo (optional) Chemical

Similar

Steels (U.S. and/or Foreign). Ito. AhlS ASTM A276. A3 I-l. A-l73. AS80; FED QQ-S-763. QQ-S-766. hllL SPEC MIL-S-862: SAE J-IO5 (5l-l20); (Ger.) DIN AFNOR Z 20 CB; (Ital.) UNI X 20 Cr I3 X I; (Jap.) JIS (Sa,ed.)SSt~7303:(l!.K.) B.S.-l?OS 37.CDS-18. En. S6C. AMS 5620; SAE J-l05 (5 l-i70 F)

5506. 5621; QQ-W-133: 1.4071; (Fr.) SUS 470 II: 3s. 62.42OF.

Characteristics.

Deep hardening. Can be hardened to slightly over 500 HB. Quenched in oil or air. Can be readill mat-tempered. hlagnetic in all conditions. Optimum corrosion resistance in hardened and tempered condition. Can be full, process, or isothermal annealed. Used for cutler? and general use where strength. ductility. and corrosion resistance are desired. Type 420F is a free-machining version of -170. Sulfur added to -I20F to improve machining and nonseizing characteristics. Processing the same as for 410. except a higher initial forgmg temperature used to minimize hot short cracking

Forging. For type 420. start forging at 1065 to 1205 “C (I950 to 1200 “F). Do not forge after temperature of forging stock drops below 900 “‘C (1650 OF). For type 420F. forge at I I20 to I230 “C (2050 to ??-I5 “F). Cool very slowly from fmishing temperature. Anneal

Recommended Normalizing. Annealing. l

Heat Treating

Practice

Do not normalize Can be process. isothermal.

or full annealed:

Process unn& in subcritical temperature range of 675 to 760 “C ( I215 to I400 “F). Use clean. rectified salt bath or an atmosphere that is compatible uith this temperature range. Soaking and softening time dependent on size of work. Air cool. Hardness. 9-l to 97 HRB

lsorhrrrnal ~rr~ea/ by heating at 830 to 885 “C ( 1575 to 1625 “F). Cool slowl) to 705 “C ( I300 “FL Hold for 2 h. Hardness. approximately 95 HRB Full ur~rreu/ at 830 to 885 “C ( IS25 to I625 OF-,. Cool to 595 “C (I IO5 “FJ at a rate not to exceed I7 to 22. “C 130 to 40 “F) per h. After this. cooling rate has no effect on hardness. Avoid carburization or decarbunzation. Can use atmospheric protection m the form of a vacuum. the inert gases argon or helium (both expensive). or nttropen. All should have dew point below -5 I “C t-60 ‘F). Endothemtic-generated atmospheres can be used by holding deu point at 0.10 to 0.25 carbon for annealing temperature used. Annealed hardness. 86 to 95 HRB. Full annealing is expensive and time consuming. Should not be used, except as required for subsequent severe forming or specialized metal cutting operations In aerospace practice. 120 is annealed at 870 “C ( I600 “F). It is cooled to below 595 “C ( I IO5 ‘F) at a rate not to exceed 30 “C (55 OF) per h. followed by slow cooling to ambient. Parts ate austenitized at 1025 “C (I875 “F). and quenched in oil or polymer

Hardening. Atmospheric protection rules for annealing apply to hardening. Parts must be completely clean and free of oil and shop contamination. Thermal conducti\ ity is significantIT lower than that of carbon and allo! steels. High thermal gradients and high stresses during rapid heating ma) cause warpage and cracking in delicate or intricate parts. Preheat at 760 to 790 “C (l-100 to 1155 “F). onI> long enough to equalize tenlperaNre in all sections. Estremel~ delicate or intricate parts would beneFtt from an additional prior preheat of 510 “C ( 1000 ‘FL Austenitized at 980 to 1065 YY i I795 to 1950 “F). Use upper end of range for larger sections or when maximum corrosion resistance and strength are required. If tempering temperature exceeds 565 “C (1050 ‘FL use low side of the austenitizing range. It enhances ductility and impact resistance. Soaking time of 30 to 60 min is adequate for sections up to I3 mm (0.50 in.). Allow an additional 30 min for each additional inch or fraction thereof. Double soaking time if parts ha\e been full or isothermal annealed. Increase time by 50%. if process annealed for long; periods above 705 “C I I300 jF). Quench in oil or air. Oil quenching preterred. because it guarantees maximum corrosion

776 / Heat Treaters

Guide

resistance and ductility. hlartempering In hot oil or salt is suitable because of high hardrnabilib. As-quenched hardness. approximately-U8 to 56-l HB

Recommended l

Stabilizing. For minimum retained austwite and maximum dimcnsional stabilib. use subzero treatment at -74 “C (- IO0 + 20 “F). This should incorporate continuous cooling from austenitirinp temperature to ths cold transformation temperature

l l l l l

Tempering.

Temper at 205 to 370 “C (400 to 700 “F). Hardness of -18 to 56 HRC. Double tempertng beneficial. Cool to room tempzraturc betueen tempers

l l l l

Nitriding. Can bc nitrided to case depth of approxImateI> t0.008 in.) in -IX h. Set t>pr 110 for further information

0.203 mm

l l

Processing

Forge Anneal Rough machine Stress relieve Finish machine: Preheat Austenitize Quench Stabilize (not mandator\. Tsmpcr Final grind to size Nitride (if required)

Sequence

but beneficial)

420: Isothermal

Transformation Diagram. Composition: 0.35 C, 0.42 Mn, 0.016 P. 0.013 S, 0.45 Si, 0.31 Ni. 13.00 Cr, 0.10 MO. Austenitized at 980 “C (1795 “F). Rockwell C hardness measured after 24 h at isotherm. Source: Republic Steel

420: Hardness vs Tempering Temperature. Composition:

0.31 C, 0.43 Mn. 0.022 P. 0.011 S. 0.45 Si. 0.44 Ni, 13.12 Cr. Heat treated at 925 “C (1695 “F), !/2 h. Oil quenched from 66 to 94 “C (150 to 200 “F). Double stress relieved at 175 “C (345 “F), 15 min. Water quenched. Tempered 2 h. Heat treated, 14 mm (0.550 in.) round. Tested. 12.8 mm (0.505 in.) round. Source: Republic Steel

420: Hardness vs Tempering Temperature. Composition:

0.31 C, 0.43 Mn, 0.022 P, 0.011 S, 0.45 Si, 0.44 Ni, 13.12 Cr. Heat from 66 to 94 “C treated at 1025 “C (1875 “F), 1 h. Oil quenched (150 to 200 “F). Double stress relieved at 175 “C (345 “F), 15 min. Water quenched. Tempered 2 h. Heat treated, 14 mm (0.550 in.) round. Tested, 12.8 mm (0.505 in.) round. Source: Republic Steel

Martensitic

420,420F:

Soak Time for Annealing

Tie

Thickness(a) mm UptoS St0 1s 15 to3 ‘SlO-Kl

4otos0 501065 6S to 75 7s to 90 9oto 100 lOOto il.5 llfito 12s 12st0300 Over 200

and Austenitizing

in.

Over Over O\er Oker Ober Over Over Over Over Over Oker

up to 0.30 0.150 to 0.500 O.SOO to I BOO I .ooO to I .SOO I .SOO to 1.OfKl ~.OOClto XC0 2.500 to 3.OOO 3.00@ to 3.500 3.500 to -!.ooO 1.00@ to 4 SO0 4.500 to S.000 S.OGO to WOO O\er X.OCU

h

(Aerospace

‘8’

Steels / 777

Practice)

Minimum soak (b,c,d,e,tJ air or atmosphere min

hlinimum soak Tie (b,c,d,c,f) salt h

2s -1.5 I I I I 2 2 2 2 3 3

Stainless

I8 3s 40 -15 so ss

IS 30 -1.5 IS 30 15 30

min

I I I I I I th,

5 IO IS 20 40

ts)Thickness is the minimum dimension of the heaiest action ofthe part. t hl Soaking shall commence w hen all control. indiaating. and recording thermocouples reach the specified set temperature. or if load thermocouplss are used, when the part temperature reaches the minimum of the furnace uniformity tolerance at the set temperature. Parts coated with copper plate or similar reflective coatings that tend to retlect radiant heat shall ha\e thrtr soaking time increased by at lrasr SOG. unless load thermocouples are used (c)When load thermocouples are used. the soaking time shall be not less than 30 min. td) In all cases, the parts shall he held for suffkient time to ensure that the center of the most massive area has reached temperature and the necessary transfomlation and diffuston hate taken place. (et hlaximum soak time shall he twtce the mimmum spxified. except for subcritical annertlinp. ff) Longer times may be necessary for parts withcomplex shapesorparts that \ron’t heat uniformI>. tgr-4 h hour plus 30 min forr\ery 75 mm (3 in.Lor portion thereofgreater than 301nm (8 in.). th) 2 h plus 1Omin foresery 7S mm (3 in.). or portion thercofgreaterthan NOmm (8 in.). Source: .AhlS 27.59/S

Martensitic

Stainless

Steels / 777

422 Chemical

Composition. AISIjlJNS (S42200): 0.20 to 0.3 C. I .OO Mn. 0.04 P. 0.03 S. 0.75 Si. 0.5 to I.0 Ni, I I.50 to 13.50 Cr. 0.75 to I.25 hlo: 0. IS to 0.3 v; 0.75 to I.25 CI

Similar Steels (U.S. and/or Foreign). AhlS 5655: ASTM (616); SAE 5167; (Ger.) DIN 1.4935: (lap.) JIS SUH 616

AS65

Characteristics.

Designed for service temperatures up to 650 “C. (I200 “F) with a combination of high strength and toughness. Carbon content. 0.20 to 0.25. Carbide-forming elements. MO. V. and W added for high-temperature strength. Somewhat restricted use. pnmarily for turbtne blades and hioh-strength fasteners for corrostve environment application. Deep hardening. Hardened hy air cooling or oil quenching,. Process annealing, rather than full annealing. recommended. Magnetic m all conditions. hledium IO low machinahilit~

benefit from an additional prior preheat of 5-U) “C ( IO00 “F). Austenhized at IO-IO “C (I905 “F) for I II. Xir cool or uater quench. In aerospace practice. parts are austenitized at IO55 “C t 1930 “F). and quenched in oil. polymer. or salt. Salt temperature must he 190 IO 275 “C (375 to 525 “F): pnrts are held in salt IO to IS mitt; then removed and cooled in air to room temperature

Stabilizing.

For minimum retained austettite and maximum dimensional stabilit). USC a subzero treatment of -7-t ‘C (-100 + 20 “F). This should incorporate continuous cooling from the austenitizing temperature to the cold transformation temperature

Tempering. temperature HB.

Temper at 6.50 “C I I200 “F) or at least to maximum sewice for 2 h. Hardened and tempered hardness, approximately 320

Forging. Start forging at I IS0 “C i2 100 “‘F). Do not forge after tempemture of forging sock drops below 955 “C (I750 OF). Cool vrq slowI! from finishing temperature. Anneal

Nitriding. Can he nitrided to case depth of approximateI> (0.008 in.) in 48 h. See type -IlO for further information

Recommended

Recommended

Normalizing.

Heat Treating

Practice

l

Do not normalize

l

Annealing.

Processanneal at 730 to 790 “C ( I350 to l-155 In aerospace practice, parts are annealed at 870 “C ( I600 cooled to 705 “C (I 300 “FL held for 5 to 7 h. cooled IO below “F) at a rate not to exceed 30 “C 155 “F) per h. and air cooled Hardening.

‘;F). Air cool. “F). The! are S-IO “C ( IO00 to ambient

Parts must be completely clean and free of oil and shop contamination. Thermal conductkity is significantly lower than that of carbon and alloy steels. High thermal gradients and high stresses during rapid heating may cause warpape and cracking in delicate or intricate parts. Preheat at 760 to 790 “C (14lO to 1155 “F). onl) long enough IO equalize temperature in all sections. Extremely delicate or intricate parts would

l l l l l l l l l l

Processing

Forge Anneal Rough machine Stress relic\ e Finish machine Preheat Austcnitize Quench Stabilize (not mandntor~. Temper Final grind to size Nitride (if required)

but beneficial)

Sequence

0.203 mm

778 / Heat Treaters

422:

Guide

Soak Time for Annealing

and Austenitizing

Thickness(a) up to 5 510 IS I5 to25 25 to-t0 4otoso so IO 65 65 Ill 7s 75 to90 9oto1ocl looto11s 1lstol2s 115l0200 Over 200

Tie in.

mm Ober Ober Over Over O\er Over Oter Over Over Over Over

(Aerospace

up to 0.250 0.750 to 0.500 0.500 to I BOO I.000 to I SO0 I SO0 to 2.OCfl 2.000 to 2.500 2.500 to 3 000 3.000 to 3.SCO 3.500 to -I 000 JONI to 4.500 1.SOO to .S.OCO 5.000 to 8.OCO Over 8.000

Practice)

Minimum soak (b,c,d,Q air or atmosphere b min

Minimum soak Tie (b,c,d,e,f) salt h

25 45 I I I I 3

2 1 3 3 3 (g)

I8

35 40 45 50 55

I5

30 1s IS 30 -IS 30

mill

I I I I I I (h)

5 IO 15

20 40

(a) Thickness is the minimum dimension of the heaviest section of the part. tb) Soaking shall commence u hen all control. indicating, and recording thermocouples reach the specified set temperanne. or if load thermocouples are used. when the part temperature reaches the minimum of the furnace uniformity tolerance at the set temperature. Parts coated with copper plate or similar reflectike coatmgs that tend to reflect radiant heat shall have their soaking time increased by at least 50%. unless load thermocouples are used. (c) When load thermocouples are used the soaking time shall he not less than 30 min. (d) In all cases. the parts shall be held for sufficient time to ensure that the center of the most massive area has reached temperature and the necessaq transformation and diffusion have taken place. te) hlaximum soak time shall be twice the minimum specified. except for subcritical annealing. (II Longer times ma\ be necessq for parts with complex shapes or parts that won’t heat uniformI). (g) 4 h hour plus 30 min for ebery 75 mm (3 in.), or portion thereofgreater than NOmm (8 tn.). th)? hplus 20 min forevery 75 mm (3 tn.). or portion thereofgreaterthm XOmmt8 in.) Source: Ah% 275915

Martensitic

Stainless

Steels / 779

431 Chemical

Composition.

AISI/UNS

(S43100): 0.20 c. 1.00 Ia,

I .OO Si. I.25 to 2.50 Ni. 15.00 to 17.00 Cr. 0.0-l P. 0.03 S

Similar

Steels (U.S. and/or Foreign). AMS 5628; ASTM ~276. A3 14. A473. A493. A579 (63). AS80: MlL SPEC hUL.-S-862; SAE 1105 (51331); (Ger.) DIN 1.4057; (Ital.) UNI X 16CrNi 16; (Jap.) JIS SW 431; (Swed.) SS1.t 2321; (U.K.) B.S. 431 S. 29, 5 S 80 Characteristics. Designed for heat treating to high mechanical properties by higher additions of Cr and Ni. Also causes increased corrosion resistance over types 4 IO. 420.430. and 440. Quenched in oil or air. Can be mar-tempered. Tempering from 370 to 565 “C (700 to 1050 “‘F) not recommended. Generally benefits from subzero treatment after quench. Process anneal only. Annealed hardness. 22 to 30 HRC. Magnetic in all conditions. Low machinability Forging. Start forging at I I50 to I230 “C (2 100 to 2245 “F). Do not forge after temperature of forging stock drops below 925 “C ( I695 “F). Cool very slowly from finishing temperature. Anneal

Recommended Normalizing.

Heat Treating

Practice

Do not nomlalize

“F). Quench in oil or air. Oil quenching preferred. because it guarantees maximum corrosion resistance and ductility. Martempeting in hot oil or salt is suitable because of high hardenability. As-quenched hardness, approximately 401 to -t-t4 HB. Tendency to exhibit segregation or banding. Prevents uniform hardening and may seriously reduce mechanical properties. particularly in the transverse direction. For limited austenite segregation. heat slowly to 1205 “C (2200 “F). Hold for I h. Cool slowly to room temperature. Repeat the above heating, holding and cooling twice. for a total of three cycles. Heat to 8 I5 “C ( IS00 “F). Air cool. In aerospace practice, parts are austenitized at 1025 “C (I875 “F), and quenched in oil. polymer. or salt. Salt temperatures range from 190 to 275 “C (375 to 525 “F). Parts are held in salt for IO to I5 min. then removed and air cooled to room temperature. After the hardening quench. 43 I and 430C parts are cooled by immersing them in cold water to ambient temperature water. They are then refrigerated at -70 “C (-95 “F) or lower for not less than 2 h

Stabilizing. For minimum retained austenite and maximum dimensional stability, use subzero treatment at -74 “C (-100 + 20 “F). This should incorporate continuous cooling from austenitizing temperature to the cold transformation temperature Tempering.

Annealing.

Temper at 230 to 605 “C (445 to I I25 “F). Temper at 230 to 370 “C (44s to 700 “Fj for hardness approximately 10 to 47 HRC. Temper at 565 to 605 “C ( 1050 to I I25 “F) for hardness approximately 26 to 3-t HRC. Tempering at 370 to 565 “C (700 to I050 “F) not recommended for parts requiring high toughness and optimum corrosion resistance. Causes a marked dip in impact resistance and lowered stress corrosion cracking resistance. Double tempering beneticial. Cool to room temperature between tempers

Hardening.

Nitriding. Can be nitrided to case depth of approximately (0.008 in.) in 48 h. See type -II0 for further information

Full or isothermal annealing not recommended. Process anneal by holding at 620 to 705 “C ( I I50 to I300 “F) for sufftcient time to achieve desired ductility or machinability. 6 h minimum at temperature. A clean. rectitied molten salt bath can be used. Air cool parts from annealing temperature. In aerospace practice, parts are annealed at 870 “C (I 600 “F), then air cooled to ambient temperature followed by heating to 650 “C ( I200 “F) for IO to I2 h and air cooled For endothermic atmosphere. use dew point of IS to I8 “C (60 to 65 “F) for austenitizing temperature of 980 “C ( I795 “F). Parts must be completely clean and free of oil and shop contamination. Thermal conductivity is significantly lower than that ofcarbon and alloy steels. High thermal gradients and high stresses during rapid heating may cause warpage and cracking in delicate or intricate parts. Preheat at 760 to 790 “C ( 1400 to 1455 “F), only long enough to equalize temperature in all sections. Extremely delicate or intricate parts would benefit from an additional prior preheat of 540 “C (1000 “F). Austenitized at 980 to 1065 “C (1795 to 1950 “F). Use upper end of range for larger sections or when maximum corrosion resistance and strength are required. If tempering temperature exceeds 565 “C (1050 “F). use low side of the austenitizing range. It enhances ductility and impact resistance. Soaking time of 30 to 60 mitt is adequate for sections up to I3 mm (0.50 in.). Allow an additional 30 mm for each additional inch or fraction thereof. Double soaking time if parts have been full or isothermal annealed. Increase time by 50%. if process annealed at 675 “C ( I245

Recommended l l l l l l l l l l l l

Processing

Forge Anneal Rough machine Stress relieve Finish machine Preheat Austenitize Quench Stabilize (not mandatory, Temper Final grind to size Nitride (if required)

but beneficial)

Sequence

0.203 mm

780 / Heat Treaters

Guide

431: Hardness vs Tempering Temperature. Composition: 0.14 C,0.46Mn,0.014P,0.012S,0.44Si,2.18Ni, 16.40Cr,O.lOMo. Heat treated at 1040 “C (1905 “F), !4 h. Oil quenched from 66 to 94 “C (150 to 200 “F), 15 min. Water quenched. Tempered 2 h. Heat treated, 14 mm (0.550 in.) round. Tested, 12.8 mm (0.505 in.) round. Source: Republic Steel

431: Hardness vs Tempering Temperature. Composition: 0.14 C,0.46Mn,0.014P,0.012S,0.44Si,2.18Ni,16.40Cr,0.10Mo. Heat treated at 925 “C (1695 OF), ‘I2 h. Oil quenched from 66 to 94 “C (150 to 200 “F). Double stress relieved at 175 “C (345 “F), 15 min. Water quenched. Tempered 2 h. Heat treated, 14 mm (0.550 in.) round. Tested, 12.8 mm (0.505 in.) round. Source: Republic Steel

431: Isothermal Transformation Diagram. Composition: 0.16 C. 0.40 Mn. 0.018 P, 0.010 S. 0.43 Si. 2.44 Ni, 16.42 Cr. Austenitized at 1040 “C (1905 “F). Rockwell C hardness measured after 24 h at isotherm. Source: Republic Steel

431: Hardness vs Tempering Temperature. tempered 2 h at 980 “C (1795 “F)

Oil quenched

and

Martensitic

431:

Soak Time for Annealing

and Austenitizing

Thickness(a) mm uptos 510 I5 151025 xto40 -lo to 50 SO to 65 65 to 75

75 to90 9010 loo loot0 11s 11510125 12s 10’00 Over Xl

in. Over Over Over Over Over Oker Over Over Over Over OLer

up to 0.250 0.150 to OSCNI 0.500 to I .ooO I .OOOto I.500 I .SOO to 2.ooO 2.000 to 2.SOO 2.500 to 3.000 3.000 to 3.500 3.500 to 4.000 3.OGU to 4.500 3.500 to 5.000 S.ooO to 8.OOO Ober 8.000

(Aerospace

Stainless

Steels / 781

Practice)

Minimum soak Tie (b,c,d.e,f) air or atmosphere II min

Minimum soak Tie (b+,d,e,fj salt h

25 45

I8 35 40 15 50 55

I5 30 IS ii 30 -l5 30

min

! I I I I I th)

5 IO IS 20 40

(a) Thickness is the minimum dimension of the heaviest section of the part. I hl Soakmg ihall commence H hen all control, indicating. and recording thermocouples reach the specitied set temperature. or If load thermocouples are used. u hen the part temperature reaches the minimum of the furnace uniformity tolerance BI the set temperature. Pans coated with copper plate or similar rellectite coatings that tend IO reflect radiant heat shall haie their soaking time increased by at least 505, unless load thermocouples are used. (c I When load thermocouples are used. the soaking time shall be not less than 30 min. Cd) tn all cases. the parts shall be held for sufticient time to ensure that the center of the most massive area has reached temperature and the necessary transformation and diffusion have taken place. lei hlautmum soak nme shall be twice the minimum specified. except for subcritical annealing. (0 Longer times may be necessaq for parts with complea shapes or parts that u on’t heat uniforml). ~gr -1 h hour plus 30 nlin ior e\er) 75 mm I 3 in. ). or portion thereof greater thanXJOmm(8in.). (hj2 h plus2Omin foreveq 75 mm0 in.).orportion thereofgreater than2OOmm 18 In I. Source. AhlS ?759/5

Martensitic

Stainless

Steels / 781

440A Chemical

Composition.

AISl/UNS (WOO2): 0.65 to 0.75 C. I .OO

Mn. I .OO Si. 16.00 to 18.00 Cr. 0.01 P. 0.03 S, 0.75 MO

Similar

Steels (U.S. and/or Foreign).

A3 I-1. A373, AS I I, AS80; FED QQ-S-763; J4OS (5 I440 A)

~hls 563 I : ASTM ~276. hllL

SPEC MIL-S-86’:

SAE

Characteristics.

Greater hardenability than type 420. Greater touphness than -UOB or UOC, because of lower carbon. Good corrosion resistance, particularly in hardened and tempered condition. Quenched in oil or air. Can be martempered. Can he full. process. or isothermal annealed. Magnetic in all conditions. Low machinability. Used for cutlery. hearings. and surgical tools

Forging. Start forging at I040 to I205 “C t 1905 to 2200 “Fj. Do not forge after temperature of forging stock drops belo\\ 9SS “C t 1750 “Fj. Cool slowly from finishing temperature. Anneal

Recommended Normalizing. Annealing.

Heat Treating

Practice

Do not nomlalize Can he process, isothermal.

or full annealed:

Process ajuwal in subcritical temperature range of 675 to 760 “C t INS to 1400 “F) for hardness of 90 HRB to 27 HRC. LJse clean. rectified hath or an atmosphere that is compatible (such as bacuumj. Soaking and softening time dependent on size of work. Air cool /sor/1entu7/ unnecrl by heating at 815 to 900 “C ( 1555 to I650 “Fj. Cool slowly to 690 “C ( I275 “F). Hold for 1 h. Hardness. approximately 98 HRB Full untwal at 8-O to 900 'T ( 1.555 to 1650 “Fj. Cool to S9S ‘C t II05 ‘T) at a rate not to exceed I7 to 32 _ “C (30 to -IO “F) per h. After this. cooling rate has no effect on hardness. Avoid decarburization. Can use atmospheric protection in the foml of a vacuum. the inert gases argon or helium (both expensive), or nitrogen. All should have dew point helow -5 I “C (-60 “Fj. Endothermic-generated atmospheres can be used

hy holding de\{ point in the 0.60 to 0.75 carbon range. for the annealing temperature used. Annealed hardness. 9-t to 98 HRB. Full annealing is espenske and time consuming. Should not be used, except as required for subsequent severe forming or specialized metal-cutting operations

Hardening. Atmospheric protection rules for annealing apply to hardening. Parts must be completely clean and free of oil and shop contamination. Thermal conductivity is significantly lower than that of carbon and alloy steels, High thermal gradients and h&h stresses during rapid heating may cause ~arpage and cracking in delicate or intricate parts. Preheat at 760 to 790 ‘C t I-W to l-155 “Fj. only long enough to equalize temperature in all sections. Extremely delicate or intricate parts would benefit from an additional prior preheat of S-10 “C tIOO0 “Fj. Austenitize at 1010 to 1065 “C i I850 to 1950 “Fj. LJse upper end of range for larger sections or when maximum corrosion resistance and strength are required. Soaking time of 30 to 60 min is adequate for sections up to I3 mm tO.50 in.). Allow an additional 30 min for each additional inch or fraction thereof. Double soaking time if parts have heen full or tsothemwl annealed. Increase time hy SO? . if process annealed abo\ e 67S “C t I215 “F). Quench in oil or air. Oil quenching preferred. because it guarantees maximum corrosion resistance and ductility. hlartempering in hot oil or salt is suitable because of high hnrdenahility. As-quenched hardness. approximately 52 to S7 HRC Stabilizing. For minimum retained austenite and maximum dimensional stability. use suhzero treatment at -71 “C t-100 f 20 “F). This should incorporate continuous cooling from austenitiring temperature to the cold transformation temperature Tempering.

Temper at IS0 to 370 “C t300 to 700 “F) for hardness approxmlately -18 to 57 HRC. Double tempering beneficial. Cool to room temperature between tempers

Nitriding. Can he nitridcd to case depth of approximately tO.008 in.) in 18 h. See type 1 IO for further information

0.203 mm

782 / Heat Treaters

Recommended l l l l l l

Forge Anneal Rough machine Stress relieve

Finish machine Preheat

Guide

Processing

Sequence

l l l l l l

Austenitize Quench Stabilize (not mandatory. but beneficial) Temper Final grind to size Nitride (if required)

440A: Partial lsoth ermal Transformation .:--.

Diagram. Composi-

,?.rn n nrr ..’ LIUII: nU.DL b, nU.JU rwn, 0.17 Si, 16.59 Cr. Austenitized ,A . ..-.r.nr,

at 870 “C

(Iouu-rj

440A: Microstructures. (a) 5% pick acid and 3% HCI, in alcohol. 500x. Bar in annealed condition. Longitudinal cross section. Chromium carbide particles in ferrite matrix. (b) 1% pick acid and 5% HCI, in alcohol. 500x. Austenitized at 1010 “C (1850 “F), ‘4 h. Air cooled. Tempered at 595 “C (1105 “F), l/2 h. Partly spheroidized particles of chromium carbide in martensite matrix

782 / Heat Treaters Guide

440B Chemical Composition.

AISI/IJNS (~44003): 0.75 Mn. 1.00 Si. 16.00 to 18.00 Cr. 0.04 P. 0.03 S. 0.75 MO

Similar Steels (U.S. and/or Foreign).

ASTM A473. A580; FED QQ-S-763; MIL SPEC MIL-S-862; B); (Ger.) DIN I .4 I 12; (lap.) JIS SUS UO B

IO

0.95 c, I .oo

~3 II. A276, SAE J105 (51130

Characteristics. Greater hardenahility than type 320 and UOA. Greater toughness than 44OC. Good corrosion resistance, particularly in hardened and tempered condition. Quenched in oil or air. Can be martempered. Can be full, process. or isothermal annealed. Magnetic in all conditions. Low machinability. Used for cutlery, valve parts. and instrument bearings Forging. Start forging at 1040 to I I75 “C ( 1905 to 2150 “F). Do not forge after temperature of forging stock drops below 955 “C (I750 “F). Cool slowly from tinishing temperature. Anneal Recommended Heat Treating Normalizing. Do not normalize Annealing. Can be process. isothermal.

Practice or full annealed:

Process nr~enl in subcritical temperature range of 675 to 760 “C (1245 to 1400 “F) for hardness of 98 HRB to 23 HRC. Use clean, rectified salt bath or an atmosphere that is compatible with this temperature range. Soaking and softening time dependent on size of work. Air cool lsorhernlal arrnrul by heating at 845 to 900 “C ( I555 to 1650 “F). Cool slowly to 690 “C ( 1275 “F). Hold for 1 h. Hardness. approximately 20 HRC Full mnea/ at 845 to 900 “C ( 1555 to 1650 “F). Cool to 595 “C (I I05 “F) at a rate not to exceed I7 to 22 “C (30 to 40 “F) per h. After this. cooling rate has no effect on hardness. Avoid decarburization. Can use atmospheric protection in the form of a vacuum, the inert gases argon or helium (both expensive), or nitrogen. All should have dew point below -51 “C (40 “F). Endothermic-generated atmospheres can be used by holding dew point in the 0.75 to 0.95 carbon range for the annealing temperature used. Annealed hardness. 94 to 98 HRB. Full annealing is expensive and time consuming. Should not be used, except as required for subsequent forming or specialized metal cutting operations

Hardening. Atmospheric protection rules for annealing apply to hardening. Parts must he completely clean and free of oil and shop contarnina-

Martensitic Stainless Steels / 783 tion. Thermal conductivity is significantly lower than that of carbon and alloy steels. High thermal gradients and high stresses during rapid heating may cause warpage and cracking in delicate or intricate parts. Preheat at 760 to 790 “C ( 1400 to 1455 “F). only long enough to equalize temperature in all sections. Extremely delicate or intricate parts would benetit from an additional prior preheat of 540 “C (1000 “F). Austenitize at 1010 to 1065 “C ( I850 to 1950 “F). Use upper end of range for larger sections or when maximum corrosion resistance and strength are required. Soaking time of 30 to 60 min is adequate for sections up to I3 mm (0.50 in.). Allow an additional 30 mm for each additional inch or fraction thereof. Double soaking time if parts have been full or isothermal annealed. Lncreass time by 50% if process annealed above 705 “C (I 300 “F). Quench in oil or air. Oil quenching preferred. because it guarantees maximum corrosion resistance and ductility. Martempering in hot oil or salt is suitable because of high hardenability. As-quenched hardness. approximately 56 to 59 HRC

Stabilizing.

For minimum retained austenite and maximum dimensional stability, use subzero treatment at -7-t “C (-100 k20 “F). This should incorporate continuous cooling from austenitizing temperature to the cold transformation temperature

Tempering.

Temper at IS0 to 370 “C (300 to 700 “F) for hardness of 53 to 59 HRC. Double tempering beneficial. Cool to room temperature between tempers

Nitriding. Can be nitrided to case depth of approximately (0.008 in.) in 48 h. See type 4 IO for further information

Recommended l l l l l l l l l l l l

Processing

Forge Anneal Rough machine Stress relieve Finish machine Preheat Austenitize Quench Stabilize (not mandatory. Temper Final grind to size Nitride iif required)

0.203 mm

Sequence

but beneficial)

440B: Partial Isothermal Transformation

Diagram. Composition: 0.93 C, 0.49 Mn, 0.43 Si, 18.40 Cr, 0.55 MO. Austenitized at 870 “C (1600 “F)

Martensitic Stainless Steels / 783

44oc Chemical Composition.

AlsIjUNs

(S44004):0.95IO I 20 c. I .OO

hln. 1.00 Si. 16.00 to 18.00 Cr. 0.0-l P. 0.03 S. 0.75 Mo

Similar

Steels (U.S. and/Or Foreign). AhlS 561X. 5630: ASThI A376. A3 13. A-173. A-l93. AS80; FED QQ-S-763; MIL SPEC MlL-S-862: SAE JaO5 (5 I-MO C): (Ger.) D[N I .-I 125: (Jap.) JIS SUS -1-10 C

Characteristics. Highest hardness of hardenable stainless steels. Good corrosion resistance. particularly in hardened and tempered condition. Quenched in oil or au. Can be mat-tempered. Can he full. process. or isothermal annealed. hlagnetic in all conditions. Low machinahilitj. Used for bearings, nozzles. Lake parts. and wear parts of pumps Forging. Start forging at IO-IO to I I75 “C (I905 to 2150 “F). Do not forge after temperature of forging stock drops heIon 955 “C t 1750 “F). Cool slowly from finishing temperature. Anneal Recommended Normalizing. Annealing. l

Heat Treating

Practice

Do not normalize Can be process. isothermal.

or full annealed:

Process anneal in subcritical temperature range of 675 to 760 “C t 12-U to 1400 “Fj. Use clean, rectified salt bath or an atmosphere that is compatible with this temperature range. Soaking and softening time dependent on size of kork. Air cool. Hardness. 98 HRB to 23 HRC

/sorlrertnn/ cvvrc,ll/ by heating at 815 to 900 “C ( IS55 to 1650 “F). Cool slouly to 690 “C t I275 ‘F). Hold for 1 h. Hardness. approximately 25 HRC Fdl mrrtrt~a/ at 845 to 900 “C i IS55 to I650 “F). Cool to 595 “C (I IO5 “F) at a rate not to ehceed I7 to 22 “C (30 to 40 “F) per h. After this. cooling rate has no effect on hardness. Avoid decarburization. Can use atmospheric protection in the form of a vacuum. the inert gases argon or helium (both expensive). or nitrogen. All should have dew point beIon -51 “C t-60 ~FJ. Endothermic-generated atmospheres can be used b) holding dru point in the 0.95 to 1.20 carbon range for the annealing temperature used. Annealed hardness. 9X HRB to 25 HRC. Full annealing is expenstle and time consuming. Should not be used. escept as required for s&sequent fomling or difficult specialized metal cutting operation

ln aerospace practice. parts are annealed at 900 “C (I 650 “F), then cooled to below 59.5 “C t I IOS ‘F) at a rate not to esceed 30 “C (55 OF) per h, followed by au cooling to ambient

Hardening. Atmospheric protection rules for annealing apply to hardening. Parts must be completeI> clean and free of oil and shop contamination. Thermal conductivity is significantly loher than that of carbon and allo! steels. High stresses during rapid heating may cause warpage and cracking in delicate or intricate parts. Preheat at 760 to 790 “C ( 1400 to l-155 “F), onlj long enough to equalize temperature in all sections. Extremsll delicate or intricate parts uould benefit from an additional prior

784 / Heat Treaters Guide preheat of 510 “C ( 1000 “FJ. Austenitire at 1010 to 1065 “C ( IS50 to 1950 ‘:‘FL Use upper end of range for larger s&ons or when maximum corrosion resislnnce and strength are wquired. Sonhing time of 30 to 60 tin is adequate for section> up to I3 mm (0.50 in.). .Allou an additional 30 min for each additional inch or fraction thereof. Double soakinp time if pans hair been full or isothermal annealed. Increase time b) SO%,. if process annealed above 705 “C ( I300 “FL Quench 111oil or au. Oil quenchrng preferred. because it guarantees maximum corrosion resistance and ductility. hlartempering in hot oil or salt is suitable hecause of high hardensbilitj. As-quenched hardness. approximarelq 60 to 62 HRC minimum In aerospace practice. parts are nustsnitizrd aI 1055 “C I 1930 jF). then quenched in oil or pol>msr. .Atier rhe quench. parts are immersed in cold eater to ambient temperature irater. then refrigerated at -70 “C (-95 “F) or lower for not less than 2 h

Stabilizing.

For minimum retained austsnite and maximum dimensional stahilitj. use subzero treatment at -71 jC 1-100 +20”F). This should incorporate conGnuous cooling from nustenitizinp temperature

Tempering. Temper al I65 “C (330 ‘F) or higher. for minimum hardness of 60 HRC. Temper al 190 “C (37.5 “F) for 58 HRC minimum: at 230 “C

440C:

Soak Time for Annealing and Austenitizing

(445 “F) for 57 HRC minimum: and a1 357 “C (675 “F), for hardness approximateI> 52 to 56 HRC. Double tempering beneficial. Cool lo room temperature between tempers

Nitriding. Can be nitrided (0 case depth of 0.203 mm (0.008 in.) in 18 h. See type -I IO for further information

Recommended l

Forge

.

.4MCl1

Processing

l Rough machine . Stress relke l Finish machine l Preheat l Ausknitize l Quench l Stabilize (not mandator!, l Temper l Final grind to size l Nitride lif required)

but beneficial)

(Aerospace Practice) Minimum soali

Thicknesc(a)

Tie in.

mm Up to 5 s tll I5 15m25 3

Id 10

40 w so so to 65 65 IO 75 75 to 90 9om loo 10010 I I5 115tol2.5 I25 111xxi O\er 200

ia, ThlAn~ss is rhe nunimum

Over O\er Oler O\rr O\cr O\er O\er Oter Oker Over O\er

Up IO O.Xl 0 250 10 0.500 0.500 10 I.000 I.000 10 I 500 I.500 to 2.000 2.000 10 1500 2.500 10 ?.(Hx, 3.000 10 .l.500 3.500 10 1.000 1.000 10 -I 500 -1.500 h3 5.000 5.000 to 8.000 Ob er Y 000

Sequence

(b,c.d.e,fJ h

hlinimum

air or almosphere min

h

salt min

25

18

~j

35 10 15 SO 55

I I I I 2 2 2 7

IS 30 -15

; 3

30

(U

soak

Time (b,c.d,e$J

1’; 30 -Is I ! I I I I th)

5 IO I5 20 40

dimension of the hea\ lest seCtion of the p;ut. (b) Soaking shall comnwnse Mhen all control. indicaring. and recording rhemlocouplrs reach the specitied set temperature. or if load rhermocouplcs arc used, n hen the part temperamre reaches rhe minimum oilhrt iumscr uniformity tolerance ar Ihe set lempenture. Parts coated with iopperplale or similar rcHesC\e coatings that tend to retlect r&ant hea1 shall hate theirswting tinw increased b! At IeasSt504. unless load thermocouples me used.(c) When load ~hemlocouples ax usrd. the soaking ume shall be not less than 30 min. td, In all case\. rhe p;uts shall be held for suliicient lime to ensure that the cemrr of the most massive area has reached temperature and the nccessq transformation and diffusion hate taken place. (e) hlnximum soak time shall be tirice the minimum specified. except for subcritical annealing. I I‘, Longer times ma\ be necebrw for pluts R ith complex shapes or part> that won’t heat uniformly. I g) -I h hour plus 30 min for e\ery 75 mm (3 in.). or portion therenf greater Lhan XOmm (8 in.,. th) 2 h plus 20min forc\srl, 75 mm f3 in.). or portion thereofgreater than ?OO mm (8 in ). Source. AhlS 2759/S

Martensitic

Stainless Steels / 785

440C: Hardness vs Tempering

Temperature. Composition: 1.02C.0.48Mn,0.017F!0.011 S0.18Si.0.54Ni. 16.90Cr,0.64 MO. Heat treated at 1040 “C (1905 “F), 2 h. Oil quenched from 66 to94”C (150 to 200 “F). Double stress relieved at 175°C (345°F) 15 min. Water quenched. Tempered 2 h. Heat treated, 9.78 mm (0.385 in.) round. Tested, 9.53 mm (0.375 in.) round. At 260 to 540 “C (500 to 1000 “F). Also, heat treated, 14 mm (0.550 in.) round. Tested, 12.8 mm (0.505 in.) round. At295to760 “C (1100 to 1400 “F). Source: Republic Steel

440C: Microstructures.

(a) Vilella’s reagent, 500x. As forged. Large primary carbide particles. Heavy carbide precipitation at grain boundaries. Secondary carbide particles. Matrix predominantly retained austenite. (b) Vilella’s reagent, 500x. Forging annealed at 870 “C (1600 “F). Furnace cooled to 94 “C (200 “F) in 48 h. Air cooled. Large particles of primary and spheroidized particles of secondary carbide. Ferrite matrix. (c) Vilella’s reagent, 500x. Forging hardened by austenitizing at 1010 “C (1850 “F), 1 h. Air cooled. Tempered at 230 “C (445 “F), 2 h. Large primary and tempered secondary carbide particles. Martensite matrix. (d) Vilella’s reagent, 100x. Forging, hardened and tempered. Band of carbide segregation. Dispersed carbide particles. Tempered martensite matrix. Microhardness indentations (black). Shows relative hardness of carbide particles and matrix. (e) Super picral, 500x. Bar, preheated at 760 “C (1400 “F), !$ h. Air cooled to 66 “C (150 “F). Double tempered at 425 “C (795 “F), 2 h each. Primary and secondary carbides, light islands and particles. Tempered martensite matrix. (f) Vilella’s reagent, 200x. Ear, austenitized at 1010 to 1050 “C (1850 to 1920 “F). Oil quenched. Tempered at 190 “C (375 “F). Segregated stringers of primary carbide (light) and dispersed secondary carbide particles. Tempered mat-tensite matrix

Cast Stainless

Steels

Introduction The heat treatment of stainless steel castings follous closely in purpose and procedure the thermal processing of comparable wrought materials. However, the differences in detail warrant separate consideration. In work-hardenable ferritic alloys. machining and grinding stresses are relieved at temperatures from approximately 260 to 5-tO “C (500 to 1000 “F). Castings of the martensitic grades CA-IS and CA-JO do not require subcritical annealing to remove the effects of cold working, because they are not cold worked or cold formed. Casting stresses in other martensitic grades should be relieved by subcritical annealing, before further heat treatment. For hardened martensitic castings, the stress-relieving temperature must be kept below the final tempering or aging temperature. Homogenization. Alloy segregation and dendritic structures may occur in castings. They may be particularly pronounced in heavy sections. Also. mechanical reduction and soaking treatments are required in the mill processing of wrought alloys. Therefore. it is frequently necessary to homogenize some alloys at temperatures above 1095 “C (2005 “F). to promote uniformity of chemical composition and microstructure. Full annealing of martensitic castings results in recrystallization and maximum softness. but it is less effective than homogenization in eliminating segregation. Homogenization is a common procedure in the heat treatment of precipitation-hardening castings. Ferritic and Austenitic Grades. The fenitic. austenitic, and mixed ferritic-austenitic grades are not hardenable by heat treatment. They may be used in the as-cast condition. if maximum resistance to corrosion is not required. They can be annealed or stress relieved to improve their corrosion resistance and machining characteristics. The fenitic alloys CB-30 and CC-50 are annealed to relieve stresses and reduce hardness by being heated above 790 “C (1455 “R. as shown in the table included in this section. The austenitic grades achieve maximum resistance to intergranular corrosion by the high-temperature heating and quenching procedure known as solution annealing. As-cast structures or castings exposed to temperatures in the range from 425 to 870 “C (795 to I600 “F) may contain complex chromium carbides precipitated preferentially along gram boundaries in wholly austenitic grades. This microstructure is susceptible to intergranular corrosion, especially in oxidizing solutions. In partially ferritic grades. carbides tend to precipitate in the discontinuous ferrite pools. Thus, these grades are less susceptible to intergranular attack. The purpose of solution annealing is to ensure complete solution of carbides in the matrix and to retain these carbides in solid solution. Solution annealing procedures for all austenitic grades are similar. They consist of heating to a temperature of approximately 1095 “C (2005 “F). holding for a time sufficient to accomplish complete solution of carbides. and quenching at a rate fast enough to prevent reprecipitation of the carbides, particularly while cooling through the range from 870 to 540

“C (1600 to 1000 “F). Temperatures to which castings should be heated before quenching vary somewhat. depending on the alloy. As shown in the table included in this section, a two-step heat treating procedure may be applied to the niobium-containing CF-8C alloy. The fust treatment consists of solution annealing. This is followed by a stabilizing treatment at 870 to 925 “C ( I600 to 1695 “F), which precipitates niobium carbides, prevents formation of the damaging chromium carbides, and provides maximum resistance to intergranular attack. Because of their low carbon contents. CF-3 and CF-3M do not contain enough chromium carbides to cause selective intergranular attack and hence do not require solution annealing. Martensitic Grades. The hardening procedures for CA- IS castings are similar to those used for the comparable wrought alloy, type 410. Recommended practice for annealing. austenitizing, and tempering CA-15 are in the article on this alloy which follows. In addition, operating information on two other martensitic grades. CA-40 and CA-6NM. is presented in articles. CompositiOns. Alloy Casting Institute (ACI) compositions for corrosion resistant cast steels are in the adjoining table, along with information on comparable wrought, and ASTM grades, plus the most common end-use microstructure for each alloy. In addition. I5 articles on representative individual alloys are presented. They include: Ferritic and Austenitic grades CB-30 CC-SO CE-30 CF.3 CF-IC CF-BM blartensitic CA-IS CA-40 CA-6NM

CF-12M CF- I6F CF.20 CM-20 CK-20 CN-7M

grades

Applications and welding listed in adjoining tables.

conditions

for corrosion

resistant alloys are

Heat-Resisting Grades. Information on these casting alloys that follow include AC1 compositions; general corrosion characteristics and creep stress values: room temperature properties: short-term tensile properties at elevated temperatures: approximate rates of corrosion in air and flue gas; and corrosion resistance at 980 “C ( I800 “F) in various atmospheres.

Cast Stainless

ACI Type: Steels

Compositions wrought

ACltype

alloy type(a)

Chromium steels CA-IS 110 CA-I5M 320 CA-I.0 CA--lOF 431.4-E CB-30 cc-so 446

and Typical

ASTM specfications

A743.A217,A187 A 733 A 743 A 713 A 743

Microstructures

Most common end-use microstructure

of Alloy Casting

C

0.15

A 743

Martensite Martensite Martensite Martensite Ferrite and carbides Ferrite and carbides

0.15 0.10 0 ‘-0.1 0.30 0.30

A743 A 713. A187 A7.l3

Rlartensi te Martensite hlartensite

0.06 0.06 0.20-O 28

A747

hlartensite.

age hardenable

0.07

CB-7Cu-2

A747

Martensite.

age hardenable

CD-IMCu

A351,A743.A744. A 890 A 713 A351.A7-l3,A7U

Austrnitc in ferrite. age hardenable Femtr in austenitr Ferrite in austenite Ferrite in austenite Ferrite in austenite Ferrite in austenite Ferrite in austenite Ferrite in austcnite Ferrite in austenite Femte in austenite Femtr in austenitr Ferrite in austcnite Femtrt in austemte or austenite Austcoitr Austenite Ferrite in austenitc

Chromium-nickel CA-6N

I

(X-30 CF-3(e)

CF-3M(eb CF.3MN CF-8(e) CF-8C CF43hI CF-IO CF- IOM CF-IOMC CF-IOSMnN

312 304L 316L 30-l 317 316

CF-I2M

316

CF-16F CF-20 CC-6hlhfN

303 302

CG-8M CG-I2 CH-8 CH-IO CH-20 CK-3hlCuN

317

CK-20

310

Nickel-chromium

steel

CN-3M CN-7hl

CN-7MS CT-ISC

1.00 1.00 1.00 100 I .OO 1.00

Si

(ACI) Corrosion-Resistant Composition, Cr

Cast

S(b) Ni

Others(c)

I.0

O.SOMo(d)

I.0 I .o I .O 2.0 -I.0

0. IS-I.OOMo

I.90 065 I.50 I.50 I.50 1.50

I I.%l-l.0 11.5-11.0 11.5.IJ.0 II.S-14.0 18.0-72.0 26.0-30.0

I .OO I.00 I .OO

10.5-17 5 11.9-11.0 11.0-125

6.0-8.0

0.70

I .OO

15.5-17 7

3.6-1.6

0.07

0 70

loo

l-3.0-IS.5

1 s-s.5

0.04

I .(X1

I.00

25.0-26 5

4.75-6.0

I so I so I.50 I .so I.50 I.50 I so I 50 I.50 I so 7.00-9 00 I .50

2.00 ‘00 2.00 1.50 2.00 2.00 2.00 2.00 I.50 I 50 3.50-4.50 2.00

26.0-30.0 l7.0-‘I.0 17.0.‘I.0 17.0-z I .o 18.0-2 I .O 18.0-21 0 l80-Il.0 180-21.0 18.0-21.0 15.0-18.0 lhOl8 0 I8 O-21.0

8.0. I I .O 8.0-13.0 8.0-12.0 9.0- 13.0 8.0. I I .O 9.0-12.0 9.0- 12.0 80-11.0 9.0- I2 0 13.0-16.0 8.0-9.0 9.0-12.0

I.50 I.50 1.00-h 00

‘.oil 200 I .OO

18.0-21.0 18.0-2 I .O 20.5-23 5

‘).(I- 12.0 8.0-I I .O I 1.5-l 3.5

I .50 I 50 I.50 I.SO I.50 1.20

I.50 2.00 I .50 2.00 2.w I SM

IY.O-21.0 20.0-23 0 22.0-26.0 22.0-26 0 22.0-7-6.0 19.5-20.5

9.0- 13.0 l(J.O-I3 0 12.0-15.0 12.0-15.0 I2.0- IS.0 17519.5

2.00

2.00

23.0-27.0

19.0-22.0

20 O-12.0 19.0-X 0 I8 O-20.0 19.0-Z I .o

13.0-27.0 17.5-30.5 22 o-3.0 3 I .o-34.0

O.SMo(d)

steels

CA-6NM CA-28MWV CB-7Cu-

hltt

Institute

Steels / 787

A351.A743,A744 A 743 A351.A743,A711 A3Sl.A7-13.A744 A351,A743.A744 A351 A351 A351 A351.A743

A 743 A713 A35l.A743

A351.4743.A7U A 743 A351 A3Sl.A7-l3 A3Sl.A7-13.A7U

Ferrite in austenite Ferrite tnaustenite Ferrite in austenitc Ferrite in austrntte Austrnite Ferrite tn austenite

A 713

Austetute

A 7-13 A35l,A713.A7-U A 713. A 7-U A351

Austenite Austenite Austenite Austenitr

A3.51 309

0.30 0.03 0.03 0.03 0.08 0.08 0.08 0 04-O. IO 0.04-O. IO 0. IO 0.10 0. I 2 0.16 0.20 0.06

0.08 0.12 0.08 00-1-o IO 0.20 0.025 0.20

0.03 007 0.07 0.05-O. IS

0.50 loo O.SO- I .oO

XKJ I.50 I so 0.15-1.50

I.00 I..50 3.501,gr 0.m I .so

3.5-4.5 0.50-I 00

0.4-I .OMo ‘.. 0.9-I .25Mo: 0.9- I .25W: 0.2-0.3v 2.S-3.2Cu;0.20-0.3SNh: O.OSN max 2.S-3.3Cu:0.20-0.3SNb: 0.05N max I 752.2Shlo: 2.75.3.2SCu

2.0-3.OMo 2.0-3.OMo:

0. IO-EON

NMf) 2.0-3.Ohlo 2.0-3.OMo 1.75-2.25Mo 0.08-O. I8N 2.0.3.Ohlo I .SOhlo max: 0.20-0.3SSe I SO-3.OOhlo: 0. IO0.30Nb; 0. IO-30V; 0.20~-ION 3.01.0hlo

6.0-7.OV: 0. I8-0.24N: o.so- I OOCU

-155Shlo 2.0-3.OMo: 2.s-3.OMo: 0.5-l sv

3 03.OCu I .s-XCU

(a) ‘Qpe numbers of wrought alloys are listed only for nominal identification of corresponding wrought and cast grades. Composition ranges of cast alloys are not the same as for corresponding wrought alloys; cast alloy designations should be used for castings only. tb) hlaumum unless a range is given. The balance of all compositions is iron. (c)Sulfur content is 0.04% in all grades except: CG-6hlMN. 0.030% S (mast: CF-IOSh4nN. 0.035, S tmax): CT-ISC. O.O3c”c,S (ma\): CK-3hlCuN. O.OlOQ S (max): CN-3hl. 0.0306 S (m~):CA-6N.0.0206S(max):CA-28hlWV.0.03O~~S(m~):CA-U)F.0.20-O10~S:CB-7Cu-I and-2.0.03%S(ma~.). Phosphoruscontent isO.O4%~max~inallgradesexcept. CF-l6F. 0.176 P (max); CF-IOSMnN. 0.060%, P rmax): CT-ISC. 0.0304 P tmax): CK-3hlCuN. 0.045~ P tmax): CN-3hl. 0.03Oc1 P (mar): CA-6N. 0.0204 P tmax): CA28MWV. 0.030% P (max): CB-7Cu- I and -2.0.0354 P (mrlr;). td) Molbbdenutn not intrnoonall) added. or) CF-?A, CF-3MA. and CF-8A have the same composition ranges as CF-3, CF-3hl. and CF-8. respectively. but habe balanced compositions so that ferrite contents are at Ie\els that permit higher mechanical property specifications than those for relatedgrades.Theyareco~ered by ASTM A 351. [f) Nb. 8 x %,C min (l.O%, maxi: or Nb+Ta x QC t I. Iq, max). (g) For CN-7hlS. silicon ranges from 2.50 to 3.50%,

788 / Heat Treaters

Summary

Guide

of Applications

for Various

Corrosion-Resistant

Cast Steels Characteristics

AllO)

c4-I5 CA-40 CA-6Nhl CA-6N CB-30 CB-7Cu- I CB-7Cu-2 cc-so CD-4hlCu CE-30 CF-3. CF-8. CF-‘0. CF.3hl. CF-BM.

CF-YC.CF-I6F CG-Yhl CH-20 CK-20 CFu-7hl

Welding

H’idrly used in mildI! corrosilr en\ ironmrnts: hardcnahlc: good eroston resistance S~milartoCA-15at higherstrength Ic\el lmproied proper&> o\er CA IS. especialI) impro\rd resistance rocaitxion Ourjtanding combinations ofa=ngth. ~oughnesi. and #eldahiltv u ith moderateI! good corrosion resistance Improved performance m oxidizing eni ironmentb compared to CA- 15: excellent resistance to corrosion b! nitric acid. alkaline solutions. and many organic chemicals Hardrnahls H ith good corrorion resistance Suprnor combination of strength. toughness. and ucldabili~ 1%rth moderateI! good cormston re+ance Used in highl) owbring medtaihor HNO,. astd nunc \raterst Similar to CF.8 in corrosion resistawe. but higher svrngth. hardness. and stress-comosion cracking resistance: txrllent resistance to en\ ironments rn\ol\ ing abmston orerojion-coTToj1on: usefully employed in handling hoth oxidizing and reductng cormdents SimilmtoCC-50. but Ni imparts higher strength and roughness level>. Agmde a\ilahlc with controlled ferrire CF types: most wtdrly wed corroston-reststant alloys at ambient and cr)ogemc temperatures hl !anations: enhanced resistance to halogen ion and redwing acids C and F \ xiations: wed \t here application does not pemtit posnrcld heat treat .Agradessvailsble M ith controlled femte Greater resistance to pitting and corrosion in reducing media than CF-8hl: not suitahlr for nitric acids orothrrstrongl) ovidring environments Superior to CF.8 in specialized chemical and papsrnpplication~ in resistance IO hot HJSOI. org.+ acids. and dilure H+SO,. rhe high nickel and chromium contents also make thus alloy less susceptthle to tntergranular conosion after exposure to carhtde-precipitstng trmpcrarures improved corroston wsistance compared to CH-20 HighI) resistant to H,SO,. H xPO,. H&GO,. salts. and seawater. Good resistance to hot chloride -11 solutions. mtric acid. and many reducing chemicals

Conditions

ACI

for Corrosion-Resistant

Preheat

Pw of

designation CA-6Nhl CA-15 CA-40 CB-7Cu CB-30 cc-so CD-4hlCu CE-30 CF.3 CF.8 CF.YC CF-3hl CF-8hl CF-I2hl CF-IhF CF-20 CG-YM CH-20 CK-20 CN-7hl

electrodes used(a)

T

Same composition 410 -I IO or 120 Same compoiition or 308 442 446 Sdmc conipo>tllon 312 308L 308 347 316L 316 316 308 or 308L 308 317 309 310 320

100-150 XX-315 2(x)-3 I5

Note: hletal arc. inert-gas arc. and electroslng

Section thickness, mm (in.)

are recommended

Poshreld heat treatment 590-620 “C I I 100. I I .50 ‘n 610-760”CtII2S-IXX)‘~F1.lurc~~~l 610.760°C I II25-lUW’Fj,iurcool SO-590 ‘T I YOW I IOU “Fj. air cool 790 ‘T ( I-150 “FI. nun. atr cool ‘900°C I I6iO”Ft. arc001 Heat to 1120°C tIO5O”F). cool to ItUO”C ( IYOO ‘F). quench Quench from I OW I I20 “C i2OOO-20.50 “F) Llsuall~ unneccssag Quench from I t2-0 I I20 “C I I YOO-2050 “F)

Not requtred

Nor Not Not Not Not Not Not Not Not Not Not Not Not

requtred rrqwred required requtred required required required required required required required required required

700 \t elding methods can be used. Sugared

2.1t3h:l 3 2l’b) 1.01j.3~1 -1.8 13.,(4 6.4 I I., I elrctrodcj

OF

315-42s 20@7OO

Electrode diameter, mm (in.)

3.2-6.4 t ‘!+‘,i) 3.2-6.-l (!i-‘,il 3.1-6.4 I ‘&,) 6.4-I 3 I’s,-‘,;) ?13t’.!) t;11 Lime-27 0 28-32 19-23 24-28 24-28 13-17 13.0.17.0 17-21 10-l-t IS-19

4 ma\ 4-7 Y-II Y-12 II-11 14-18 18-22 19.0-22.0 lY.0.110 18-22 23-27 33-37 33-37 33.37 33 O-37.0 37-41 58-62 M-68

I .Oo 2.00 l?.ca 2.00 1.00 1.00 2.00 2.00 I .7s I .7s XKI 2.00 2.ocl 2.50 7.SfJ ?.S(J 2.50 ‘SO 2.50

A297.A3Sl.AS67.A608 A3SI A297.A608 A 297. A608 A297.A608

(a) ASTM deslgnatlons are the same as ACI desipattonl. th t Rem Fe in dl compositions. hlanpanesc content: O.R.‘, to 0.65 5 for HA. 15 for HC. I .Sq for HD. and 2% for the other alloys. Phosphorusandsulfurcontents: 0.04% tmax) forall hut HP-SOkVZ. hlolvhdenum is tntentionally addcdonl) to HA. u hish hat0.90 to I 70% hlo: maximum forotheralloys issrtatO.S% MO. HHalsocontainsO.2rL Ntmaxt tcjAIsocontains1to65 W:O.I to I.OQ~Zr.andOO35% Slma~land Ptmax,

General Corrosion Characteristics Indicated Temperatures

of Heat-Resistant

Cast Steels and Typical

Limiting

Creep Stress Values at

Creep test temperature Alloj

Corrosion characteriskzs

HA HC

Good oxidation resistance to 650 “C ( 1200 “F): w idrIb used in oil refining industq Good sulfur and oxidation resistance up to IOYS “C I 2OUO “F); minimal mechanical propertws: used in applications where stwngh is not a consideranon or for moderate load lwanng up to 6S0 “C t I200 “F, Ebcellrnt oxidation and sulfur resistance plus \\sldahili~ Higher temperature and sulfur resistant capabilities than HD Excellent general corrosion resistance to 8 IS “C i IS00 “FI H ith modcrate mechanical propcntes High suengh: oxidation resistant to I090 “C (2000 “F,: most \5 idcly used

HD HE HF HH(a) HI HK

HL HN HP HP-SOWZ HT

HU HU

HX

ts~Tlrogrades:

lmprotrd owiation resistance compared to HH Because of itzi high temperature strength. uldely used for strw.ed parts in sbuctural spphsatton> up to I IS0 “C (2 I(x) “F): offers good reslstance to sorrosion h) hot ga.w>. mcludmg wlfurbearing gases. in hoth oxtdizing and reducing conditions (although HC. HE. and HI are more resistant in oxidizing gasej): used in illr, ammonia. hydrogen. and molten neutral salt\: m Idell used for tubes and furnace parts Improved sulfur resistance compared to HK: cspeciall! useful \\ here ewrssi\e ,caline must br a\ aided Very high strength at high temperatures. resibtant tooxtdizing and reducing flue g&e\ Resistant to both oxidizing and carhuririnp atmospheres at high temperatures lmpro~edcrecpmpturcstrrngthat lO9C”Ct~000”F1andaho\ecomparcdtoHP H’idely used in thermal shocb applications: corrosion resistant in atr. okidizing and redwing flue gases. carburizing gases. salts. and molten metals: performs satisfactorily up to I I SO “C tZIOO”F, in ohidiling atmospheres and up to IO% “C (2000 “FI in reduang atmosphere>. provided that limiting creep stress \alurs are not exceeded Higher hot strength than HTand ohen selected for its superior corroston resIstawe High hot strength and clectrkal resisti\ Ity: performs satisfactotil) to I I70 “C I 20.50 ‘FI in strongly oudizing atmospheresand up to IWO “C I 1900 ‘FI inoxidizing or reducmg product, ofcombustion that do not contain sulfur: resistant to some 4ts and molten metal< Resistant to hot-gas corroilon under qcling conditions u hour cracking or \t arpmg: corroston resistant in air, carhurizing gases. combustion gases. flue gases. h)drogcn. molten qanide. molten lead. and molten neutral sahsat temperatures up to I ISO”C I 2 IOWFI type l~frmtr~naustemt~)nnd~)~~

Il~uholl!

austrnitickperASThlAU7

T

Limiting creep stress (0.ooo1 a/h) hi MPa

OF

650 870

I200 1600

21.5 S.15

3.1 0.75

981) 980 870 980

1800 I 80 16(x) IS00

0.9

9x0

I800

I .4 3.9 I.1 (typeI) ?.I (type II) I .9 I .1

IWO

I900

6.2 9.S 27 7.5 (type I) 11.5 (Iype II) I3 95

Y8tI

Id00

IS

2.1

IO.40 980 IWO 080

I YW I800 YJfx) I800

II 19 1.x l-l

I6 2.8 0.7 2.0

IS 9.5

2.2

II

1.6

980 980

Y~(J

IX00

I .-I

790 / Heat Treaters

Guide

Typical Room-Temperature

Properties

of ACI Heat-Resistant

Casting

Alloys

Tensile strength MOY HC

MPa

ksi

MPa

ksi

AS-C3St

760 790 585 655 620 635 690 585 595 550 635 SSO 620 515 58s 56.5 470 190 48.s 51s 485 SO5 470 580 450 SO5

110 11s

51s 550

75

85 95 90 92 100 85 86 80 92 80 90 75 85 82 68 71 70 75 70 73 68 8-l 65 73

330 310 380 310 3-E 31s 380 27s 310 310 -IS0 3-E 315 3bO 2bO 275 27s 310 27s 295 250

Aged(a) As-cast As-cast Aged(a) As-cast Aged(a) As-cast Aged(a) As-cast Aged(a) As-cast Aged(a) As-cast Aged(b) As-cast As-cast As-cast As-cast Agedib) As-cast Aged(c) As-cast Aged(d) As-casr Aged(c)

HD HE

HF

HH.t)pel HH. type Ii HI HK

HL HN HP HT HLI HH

w

Yield strength

Condition

tar Agingtreatment: 24hat 76O”Ct 1400°F). fumacecool.(b)Agingtrearment: treatment: 18 h at 980 “C ( I800 OF). furnace cool

Representative

Short-Term

Tensile

Properties

30s 24hat760GC(I-KW”F~,aircool.

223 90 200 270 165 190 I85 200 I80 200 I80 200 170 I90 I92 160 170 I80 200 170 I90 I85 205 176 I85

IO I9 13 II IQ 5 9 5 4 4 9 9

t~)Agingtreatment:

-l8 hatYgO”C(

at Elevated

Temperatures

Alloys

Eardll~ ml

19 18 I6 20 IO 38 25 ‘5 II 1s 8 I2 6 I7

80 -la 45 55 45 SO SO 55 40 4.5 35 65 SO 50 52 38 10 10 4s 30 13 36 5’ 36 4-l

360 250

of Cast Heat-Resistant

Elongation. %

18OO”F),aircool.(d)Aging

Property at indicated temperature (1JOO~F) Ultimate tensile Yield strength at strength 0.2 % offset Elongation, MPa ksi hfPa ksi 5% 760%

Alloy HA HD HF HHttjpeI)(c) HH (type IIMsI HI HK HL HN HP HT HlI HH’ Hx

4662(a) 248 262 228 258 262 258 345

6-h~

296 240 ‘75 220 310(d)

43 35 -lo 32 -lStd)

36 38 33 37.4 38 31.5 so

(31 In tlus instance. test temperature

220(b) ,_. 17’ 117 136

32t bj _._ 25 I7 19.8

I68

21.1

;; I6 I8 I6 6 I2

200 I80

29 26

IS IO

I58 138(d)

13 20(d)

was 5-lO”C I 1000°F)

8(d)

870 “C (1600 “F)

Ultimate tensile strength hIPa ksi I59 I15 I27 1-M 179 lb1 210 I40 179 130 I35 I31 I11

(b)Test tcmperxure

‘3 21 18.5 21.5 26 23 30.5 ‘0 26 I9 19.5 19 20.5 uas 590°C

!BoT

Yield strength at 0.2 5%o&t hiPa ksi ,:: 107 93 II0

Elongation, 8

IOI

,,_ IS.5 13.9 I6 ” I5

I8 I6 30 I8 I2 lb

100 I21 103

11.5 17.5 I5

37 27 2-l 20

103 I21

I5 17.5

I IO95 “F). (c~npe

Ultimate tensile strength

48 land Il perASTh1

hlPa

bi

ld; ___ 62 75 _.. 8.53 I29 83 loo

IS .., 9 IO.9 ,, 12.4 18.7 I2 I-l 5 II IO IO 10.7

76 69 69 7-1 AU7

(d)Trst

(MooT)

Yield strength at 0.2% of&et hlPa ksi ::: .,. 43 SO .,. 60 ,,. 66 76 55 43 55 17

Elongation, +

::: ___ 6.3 7.3 .., 8.7 ___ 9.6 II 8 6.2 8 6.9

tempennrrew~6650”C(1200°~

40 __. 45 31 42 .__ 51 46 28 28 40 30

Cast Stainless

Approximate

Rates of Corrosion

for ACI Heat-Resistant

Casting

Alloys

870 oc

HB HC HD HE

HK HL HN HP

HT HU HIV HX

6.25I .25 I .250.631.25+ 0.630.‘5+ 0.250.630.25+ 0.63 0.25+ 0.250.25O.‘S-

of Ferritic and Austenitic Minimum temperature OF YI

For full softness CB-30 cc-50

CF-SM.CF-I?M(e) CF- l6F, CF-20 CH-20 CK-20

CN-7M

12.5 I.25 I .250.882.5 I.25 0.880.880.88 I .25I.35 I.25 0.880.88 0.88-

Stainless

Quench(a)

I-IS0 1450

3.5+ 0.630.630.63I .25+

1040 I040 I040 I040 1095 1095 II20

1900 1900 1900 I900 2000 mlo 2050

W.0.A W.0.A W.O.4 W.0.A W.0.A W.0.A W.0.A

97 77 77 80 77 88

W.0.A

69

76

Oxidizing

12.5 0.63+ 0.630.63XC O.b3 0.630.630.630.630.630.630.630 630.63-

O.b30.630.630.630.630.630.63 0.630.63 0.63-

Tensile strength ksi(b) MPa(b)

95 97

Reducing

6.25 0.63 O.630.63l.25+ 0.63 0.630.630.63 0.63 0.63063 0.63I .250.63-

Reducing I2.5 0.630.630.636.25 0.630 630.630.630.63 0.632.5 0.63 6.25 0.63-

Corrosion Resistance of Heat-Resistant Cast Steels at 980 “C (1800 “F) in 100 h Tests in Various Atmospheres

Steel

FCtA(c, A

2.3 g/m’

0.12 g/m’

Oxidizing

Alloy 790 790

For maximum corrosion resistance 1095 2ooo CE-30 CF-3. CF-3M CF-8. CF-SC(d)

109OT

~2~ OF)

~~~“F)

0.630.25 0.25 O.l30. I30. I3O.l30.250.25+ 0.13 0.630.13O.l3O.l3O.l3-

HF HH HI

Annealing Castings

980 oc

(lm°F)

in Air and in Flue Gas Corrosion rate.mm/yT,at 980% (1WJ’F) in flue gas with sulfur content of:

Oxidation rate in air, mm/yr Alloy

Steels / 791

655 669

bb9 531 531 552 531 607 52-I 476

(a) FC, furnace cool; W. water. 0. oil: A. air. (b) Approximate. (c) Furnace cool to 5-tU “C (IOOO”F); then air cool. (d)CF-SC may be reheated to870 to925 “C (16OOto I700 “F): then air cooled for precipitation of niobium carbides. (e) CF.I2M should be quenched from a temperature above I095 “C (2000 OF).

HA HC HD HE HF HH HI HK HL HN HP HT HU HW’ HX

Corrosion rating(a) in indicated atmosphere Reducing Reducing flue flue gas gas cooled to Oxidizing Reducing Reducing (constant 15OT (3oo~F) Air flue gas(b) flue gas(b) flue gas(c) temperature)(d) every I2 h(d) U G G G S G G G G G G G G G G

u G G G G G G G G G G G G G G

11 G G G S G G G G G G G G G G

u s S

U G G

U S S U S U G U u U S

S G G

tat G. good (corrosion mte r < 1.27 mnuyr. or 50 mils/yr); S. satisfactory (r c 2.5-l mndyr. or 100 milslw): U. unsatisfacton tr > 2.54 mm/yr. or 100 mils/yr). (b) Contained 2gofsulfur/mr(S grinsS/ICO ft’j. (c)Contamed 120gS/mJ(300grainsS/IO0 ft’t td~Contained-10gISlnt~ilOO~~insS/lOO~~

792 / Heat Treaters

Guide

CA-6NM Chemical

Composition. AC1 CA-6Nhl: 3.5 to 4.5 Ni. I I.5 to l-1.0 Cr. 0.1 to I .O hlo

0.06 C. I .OOhln, I .OO Si.

Similar

UNS JY1540: ASTM ,471~.

Steels (U.S. and/or

Foreign).

CA-6NM: Influence of Tempering Temperature on Hardness. Source: ESCO Corporation

A-187

Characteristics.

Recommended

hlartensitr

is most common

Heat Treating

end-use microstructure

Practice

Annealing. For maximum softness. parts are annealed at 790 to 8 IS “C (l-155 to I SO0 OF). The typical ultimate tensile strength ohtaincd is approximately 550 hlPa (80 ksi) Austenitizing and Tempering. Follou inp austcnitizing. parts arc quenched in oil or air. In austcnitizing at YSS to 980 “C t 1750 to 1795 “F) and tempering at 595 to 610 “C (I IO5 to I IS0 “F). a typical ultimate tensile strengths of approximately 835 hlPa ( I10 ksi J is obtained

CA-6NM: Effect of Tempering Temperature on Mechanical Properties of Standard Keel Block. Source: ESCO Corporation

Cast Stainless

Steels / 793

CA-1 5 Chemical

Composition.

AC1 CA-15 0. IS C. I.00 Mn, I .SO Si. I .O

Ni, I I.5 lo 14.0 Cr. 0.50 MO (not intentionally

Similar

Steels (U.S. and/or Foreign).

type 3 IO stainless: ASTM

Characteristics.

Recommended

CA-15: Effect of Tempering Temperature on Typical Room Temperature Properties

added) LINS

J9llsO;

wrought

A713. Al 17. A187

Martensite is most common end-use microsuucture

Heat Treating Practice

Annealing.

For maximum softness, parts are annealed at 8.45 to 900 “C ( IS55 to I650 “F). The typical ultimate tensile strength obtamed is approxlmately 550 MPa (80 ksi)

Austenitizing and Tempering. Following austenitizinp. parts are quenched in oil or air. Tempering al 370 to 595 “C (700 to I IO5 “F) is not recommended because in this range impact ductil!? is low. For this alloy. pans are held at austenitizing temperature for a mnumum of 30 min. In austenitizing at 975 to 1010 “C (I695 10 I850 “F) and tempering at 370 “C max (700 “F) max. typical ultimate tensile strengths of npproximatelv 1380 MPa (200 ksi) are obtained. while in austenitizing at 95 to 1010 ‘C ( 1695 to I850 “F) and tempering at 595 to 760 ‘C ( I I OS to 1400 OF), typical ultimate tensile strengths of approximateI) 690 to 930 hlPa ( 100 to I35 ksi) are obtained

CA-15: Effects of Four Methods Specimens

of Heat Treatment

were taken from shell mold cast keel blocks;

Trzaunent I Homogenize: I hat IaU,~C~l9OO~F~.AC Solution anneal. ‘+ h at 955 “C I I 7SO‘FL OQ Ternper: 3 h aI 300 “C (575 “Ft. AC

1230 I xl

Treaimrnl 2 Anneal: I h aI 900°C ( 16%) “FL FC Solutionanneal: I ‘!‘ahat 1010cC(lS50”F~.0Q Temper: 3 h aI 370°C (700 “F). OQ Treatnwnt 3(b) Anneal: I h at 900 “C ( I650 “F). FC OQ

Treaunrn~ -UC) Anne& I hill 900 ‘C (16.50 “FJ. FC Solution zwnesl: I ‘/> h 8199s “C ( I825 “Fj. F.4C

Temper: 2 h aI 705 “C ( I300 “F). AC ta~Eacht~atment comprised threeprocesses~

?oom Temperature Jlts obtained

Ultimate tensile strength ksi MPa

Heat treatment(a)

Solution mneal: I ‘/J h 31 IOIO”C( 180°F). Temper: 2 hat 610°C I llS0”F~ AC

on Typic

data indicate

Properties

on four specimens

treated

by each method Reduction

i’ield strength hlPa

ksi

Elongation in SO mm (2 in.), %

in area, 92

1005

1-b

970 Y8S IO_‘0

IJI I43 I48

9.0 12.5 7.0 8.0

IIIS I 130

I62 16-l IS5 IS2

65 55 9.0 I’.0

9.5 16.0 23.0 -12.0

I.55 16s YC

13.0

127.5 1315

178 I81 I85 191

1260 1296 1340

183 I88 19-l

1380

200

795 810 830 860

11s II7 I’0 175

70 91 98 85

12.5

60.0 37.0 23.0 32.0

685 710 710

9’) 103 I03

76 79 79

21.0 20.5 I85

6S.0 56.0 61.5

7’0

10-a

80

20.5

60.0

listed: 4C.aircool:OQ.oilquench:

FC. iumscecool:

FAC. forced-tircool

Ibr AAlS S3il -B (5) hlL-S-16993

28.0 14.0 12.5

794 / Heat Treaters

Guide

CA-40 Chemical

COInpOSitiOn. AC1 CA-40: Ni. I I.5 to 14.0 Cr. 0.5 MO (not intentionally

Similar

Steels (U.S. and/or

type 410 stainless; ASTM

Characteristics.

Recommended

0.40 C. I.00 Mn. I SO Si. I .O added)

Foreign).

UNS

J9 I 153;

wrought

A743

Martensite

is most common end-use microstructure

Heat Treating

Practice

Annealing. For maximum softness. parts are annealed at 845 to 900 “C (IS55 to I650 “F). then slow furnace cooled from temperature. The typical ultimate tensile strength obtained is approximately 620 MPa (90 ksi)

Austenitizing and tempering. Following austenitizing, parts are quenched in oil or air. Tempering at 370 to 595 “C (700 to I I05 “F’) is not recommended because in this range impact ductility is low. ln austeni tizing at 980 to IO IO “C ( I795 to I850 “F) and tempering at 3 IS “C max (600 “F max). a typical ultimate tensile strength of approximately I5 I5 MPa (220 ksi) is obtained. At the same austenitizing temperature. typical ultimate tensile strength drops as tempering temperature is increased. At the 595 “C (I IO5 “F) level, the result is 1035 MPa (150 ksi); at the 650 “C (I 200 “F) level. the result is 965 MPa ( 140 ksi); at the 760 “C (I400 “F) level. the result is 760 hlPa (I IO ksi)

794 / Heat Treaters

Guide

CB-30 Chemical

Composition.

AC1CA-15 0.30C. I .OOMn.

I SO Si. 2.0

Ni. 18.0 to 21.0 Cr

Similar

Steels (U.S. and/or

type 312: ASTM

Characteristics. structure contains

Foreign).

UNS

J9 1803; type

33 I.

A733 A chromium grade. The most commonly ferrite and carbides

used micro-

Annealing.

The minimum “C ( 1455 “F). The quenching OF). then air cooling. The approximately 660 MPa (95

annealing temperature for full softness is 790 procedure is furnace cooling to 540 “C (1000 typical ultimate tensile strength obtained is ksi)

794 / Heat Treaters Guide

cc-50 Chemical

COIIIpOSitiOn. Ni. 36.0 to 30.0 Cr

AC1 CC-50:

0.30 C, I.00 hln. I SO Si. A.0

Similar Steels (U.S. and/or Foreign). ASTM

UNS

592615:

type

446:

A7-13

Characteristics. structure contains

A chromium grade. The most commonly ferrite and carbides

used micro-

Recommended Heat Treating Practice Annealing. The minimum annealing temperature

for full softness is790 “C (I455 “F). Parts are quenched in air. The typical ultimate tensile strength obtained is approximately 670 MPa (97 ksi)

794 / Heat Treaters

Guide

CE-30 Chemical

Composition.

AC1 CE-30: 0.30 C. I.50 Mn. 2.00 Si. 8.0

to I I .O Ni, 26.0 to 30.0 Cr

Similar ASTM

Steels (U.S. and/or Foreign).

UNS

J93423:

type

3 12;

743

Characteristics. most commonly

A chromium-nickel used microstructure

grade. Ferrite

in austenite

is the

Recommended

Heat Treating

Practice

Annealing. For maximum corrosion resistance, the minimum annealing temperature is 1095 “C (2005 ‘F). Quenching is in water, oil, or air. The typical ultimate tensile strength ohtained is approximately 670 MPa (97 ksi)

Cast Stainless

Steels / 795

CF-3 Chemical to l?.ONi.

Composition.

AC1 CF-3: 0.03 C. I SO hln. 2.00 Si. 8.0

17.0to21.0Cr

most commonly

Note: CF-3A. CF-3MA. and CF-8A have the same composition ranges as CF-3. CF-3M. and CF-8 respectively. but have balanced compositions so that ferrite contents are at levels that permit higher mechanical property specifications than those for related grades. They are covered by AsThl .

A751 .II.

Similar ASTM

Steels (U.S. and/or Foreign). A35 I, A713, A7-U

Characteristics.

1lNS J92700; type 304L;

A chromium-nickel used microstructure

Recommended Annealing.

Heat Treating

grade. Ferrite in austenite

is the

Practice

The minimum annealing temperature for maximum corrosion resistance is IO-10 “C (I905 “FL Quenching is in water. oil, or air. The typical ultimate tensile strength obtained is approximately 530 MPa (77 ksi)

Cast Stainless

Steels / 795

CF-8C Chemical

Composition.

AC1 CF-SC: 0.08 C. I.50 Mn. 2.00 Si. 9.0

to 12.0 Ni. IS.0 to 2 I .O Cr. Nh Note: Nb. 8 X ?/oC min (I .O 91 max); or Nb + Ta X ?K (I. I “6 max)

Similar ASTM

Steels (U.S. and/or Foreign).

UNS

592600:

type

30-i:

A35 I, A743. A744

Characteristics. most commonly

A chromium-nickel used microstructure

grade. Ferrite in austenite

is the

Recommended Annealing.

Heat Treating Practice

The minimum annealing temperature for maximum corrosion resistance is 1040 “C (I905 “F). Quenching is in water, oil. or air. The typtcal ultimate tensile strength ohtained is approximately 530 MPa (77 ksi). CF-SC may be reheated to 870 to 925 “C (1600 to 1695 “F). then air-cooled to precipitate niobium carbides

Cast Stainless

Steels / 795

CF-8M Chemical

Composition. AC1 CF-8M: to 12.0 Ni. 18.0 to 21 .O Cr. 2.0 to 3.0 Mo Similar ASTM

Steels (U.S. and/or Foreign).

0.08 C. I.50 hln. 2.00 Si 9.0

Annealing. UNS

~92900:

type

3 16;

A35 I, A743

Characteristics. most commonly

A chromium-nickel used microstructure

Recommended

grade. Ferrite in austenite

is the

Heat

Treatina - - ------a

Practice _ .--_---

The minimum ;annealing temperature for maximum corrosion resistance is IO-IO “C I I905 “F). Quenching is in water. oil, or air. The typical ultimate tensile strength obtained is approximately 550 MPa (80 1-c;,

Cast Stainless

Steels / 795

CF42M Chemical

Composition.

AC1 CF-12M:

0. I? C. 1SO Mn. 2.00 Si.

9.0 to 12.0 Ni, 18.0 to 21.0 Cr. 2.0 to 3.0 MO

Similar

Steels (U.S. and/or Foreign).

Recommended Annealing.

Type 3 I6

Characteristics. A chromium-nickel grade. Ferrite austenite alone is the most commonly used microstructure

in austenite

or

Heat Treating

Practice

The minimum annealinp temperature for maximum corrosion resistance is 1040 “C t 1905 “F). The alloy should be quenched from a temperature above 1095 “C (2005 V). Quenching is in water. oil. or air. The typical ultimate tensile strength obtained is approximately 550 MPa (80 ksi)

Cast Stainless Steels / 795

CF46F Chemical

COmpOSitiOn.

AC1 CF-16F: 0.16 C. I.50 Mn. XKI Si.

9.0 to I?.0 Ni. 18.0 to 21.0 Cr. 1.5 Mo ma.\. 0.25 to 0.35 Se

Similar Steels (U.S. and/or Foreign). ASThl

A713

UNS

~92701:

type

303:

796 / Heat Treaters Guide Characteristics.

4 chromium-nickel manly used microstructure

Recommended Annealing. The

Heat Treating

grade. Austenitc

is the most com-

Practice

minimum annealing temperature for maximum corrosion resistance is IWO “C I 1905 “FL Quenching is in water. oil. or air. The

typical ksi I

ultimate

tensile strength

obtained

is approximately

530 MPa (77

796 / Heat Treaters

Guide

CF-20 Chemical IO Il.ONi.

Similar ASTM

COmpOSitiOn. 18.0to2l.OCr

AC1CF-20: 0.20C. I .SOMn.

Steels (U.S. and/or

2.00 Si. X.0

Recommended Annealing.

Foreign).

UNS JW602: tjpe 302:

A743

Characteristics. A chromium-nickel monly used microstructure

grade. Austenite

is the most com-

Heat Treating

Practice

The minimum annealing temperature for maximum corrosion resistance is IO-10 “C ( 1905 “F). Quenching is in water, oil, or air. The typical ultimate tensile strength obtained is approximately 530 MPa (77 ksi)

796 / Heat Treaters

Guide

CH-20 Chemical

Composition.

AC1 CH-20: 0.20 C. I.50 Mn. 2.00 Si.

12.0 to IS.0 Ni. 32.0 to 26.0 Cr

Similar

Steels (U.S. and/or

Annealing. Foreign).

LINS 593-W;

type

309:

ASTM A35 I, Al-43

Characteristics. monlj

Recommended

A chromium-nickel used microstructure

grade. Austrnite

is the most com-

Heat Treating

Practice

The minimum annealing temperature for maximum corrosion resistance is 1095 “C (2005 “Fb. Quenching is in water, oil, or air. The typical ultimate tsnsilr strength ohtained is approximately 610 MPa (88 ksi)

796 / Heat Treaters

Guide

CK-20 Chemical Composition. AC1 CK-20: 0.20 C. 2.00 hln, 2.00 Si. 19.0IO 22.0 Ni. 23.0 to 27.0 Cr Similar ASThl

Steels (U.S. and/or

Foreign).

UNS

J94202:

tjpe

3 IO:

A743

Characteristics. A chromium-nickel monly used microstructure

grade. Austenite

IS the most com-

Recommended

Heat Treating

Practice

Annealing. The minimum annealing temperature for maximum corrosion resistance is 1095 “C (2005 “F). Quenching is in water. oil. or air. The typical ultimate tensile strength obtained is approximately 525 MPa (76 IrsiJ

796 / Heat Treaters

Guide

CN-7M Chemical

Composition. AC1 CN-7111: 0.07 C. I.50 Mn. I.50 Si. 27.5 to 30.5 Ni. 19.0 to 27.0 Cr. 3.0 to 3.0 MO. 3.0 to 4.0 Cu

Similar

Steels (U.S. and/or Foreign).

UNS

N08007:

ASTM

A35 I. A743. A744

Characteristics.

.L\chromium-nickel monly used microstructure

grade. Austsnite

is the most com-

Recommended

Heat Treating

Practice

Annealing. The minimum annealing temperature for maximum corrosion resistance is I I20 “C. (7050 “FL Quenching is in \cater. oil. or air. The typical ultimate lensile strength obtainsd is approximately 180 MPa (69 ksi)

PH Stainless Cast PH Stainless

Steels

Steels

Cast PH Steels. It is desuahle to subject precipitation-hardenable castings to a high-temperature homogenization treatment to reduce allo) segregation and to obtain more uniform response to subsequent heat treatment. Even investment castings that are cooled slowly from the pouring temperature exhibit more nearly uniform properties when they ha\e been homogenized. Homogenizing treatments for I74 PH (UNS S 17400) and AM-355 (UNS S35500)are given in Hea/ Pearing. Volume 4 of .4Sht Handbook (page 788). 17-4PH Castings. When 174PH (ASTM CB-7Cu-I and CB7Cu-2) is cast in plastic-bonded shell molds, the surface is carburized by decomposition of the binder. The added carbon prevents proper heat-treating. Response is obtained when surface carbon is removed prior to the homogenization treatment. In addition to homogenization. other heat-treating procedures for l74PH castings include solution annealing and precipitation hardening. Details of these procedures are given in an adjoinmg table. The preferred temperature range for precipitation hardening is 180 to 595 “C (900 to II00 “F). The mechanical properties obtained at different aging temperatures are given in AS21 Handbook. Volume 4 ipage 791).

The tendency of 17-4PH castings to overage IS reduced by the addition of approximate11 0.255, combined niobium plus tantalum to the alloy. The eff‘ects of time at aging temperature on the mechanical properties of niobium-free and niobium-containing I7-4PH investment castings are given in XM Handbook, Volume 3 (page 79 I). AM-350 and AM-355. Although investment castings made of these alloys do not necessarily require a homogenizing treatment. this treatment provides a more uniform response to subsequent heat treatment. Shell mold and sand castings made of AhIthat were extremely brittle without homogenization regained ductility after homogenizing at 1095 “C (2000 “F) for 2 h minimum. Heat-treating procedures and effects of tempering temperatures up to 650 “C ( I200 “F) on mechanical properties of AM355 shell mold castings are given m .-l.SM Handbook, Volume 1 (page 792). When Ahl-355 castings are welded, maxunum mechanical properties are obtained when the castings are fully heat treated after welding (see adjoining table). Heat treatments prior to welding have little effect on properties when a complete heat treatment follows welding.

1714PH Chemical

Composition.

AISILJNS

(S17400): 0.07 C. 1.00 Mn.

l.OOSi, 3.010 5.0 Ni, IS.50 to 17.SOCr.0.04 to 0.45 Nb

P. 0.03 S. 3.0to5.0Cu.0.15

Similar Steels (U.S. and/or Foreign). S3SS.S604.S622.S643,S82S; A70S; MIL SPEC MIL-C-XI

AMS 53-12, 5343. S3.U. ASME SAS64, SA70S; ASTM AS6-1. A693. I I, MIL-S-81506. ML-S-81591; SAE J-167

Martensitic type 174PH combines high strength and hardness with excellent corrosion resistance. Can be hardened by a single lam-temperature heat ueatment that virtually eliminates scaling and distortion. Similar Lo 15SPH. except has slightly higher chromnml content. Applications include gears. springs. curlerq. fasteners. aircraft parts. turbine parts Forge withm range of IO-IO to I I SO “C ( I905 to 2 IO0 “F)

Recommended

Heat Treating

Practice

For [his grade and for most other precipitation-hardening grades. the final properties can differ somew hat with variations in aping temperature. However. the following procedure is most commonly used: l l l l

Fiial beat treat condition(a) H9CUl

Characteristics.

Forging.

17-4PH: Heat Treating Procedures (Aerospace Practice)

Solution treat by heating at 1025 to I050 “C (I 875 to 1920 “F) Oil quench to room temperature Age at 480 “C (89s “F) for I h and air cool (known as condition H900) Following this heat treatment. a hardness ofapproximately 42 to 44 HRC can be expected

H H H H H H H H H

925 950 IOW 1025 1050 1075 II00 II50 I ISOhllh,

Solution heat treating. set temperature. “C (“F)(b) 104011900)

Solution heat treating, cooling(c)

Aging set temperature, “C (“F)(e)

air. 011. polymer LObelow 180 (900) 30 ‘T 190 “F) \s~ttun I hl,d) 49s (925) SlO(9SO) 510~1ooo) 550( 1025) 565 ( 1050) 580(1075, 595 ( 1100) 62O(llSO) (h)

Aging time, hour@,f,g) I (g.i) 4g.i) -I 4 J 4 4 -l -I lh)

I a) See table forspecitied mmimum tensile strength conversions to heat treat condition 1b1 See table for soak times. 15) 4ir means a1roratmosphere. (d) Artiticial means may he used 10 cool belo\\ ambient Iemperarure u hen necessary to gel below 30 “C (90 “F) orbelo\r lS”C160~‘F~.~e~~me.+l0.i)~ninfor30minages:+lS.-0minforIhagrs; t30 min. 4 nlin for I .S h ages: and +-lS. Xl for 3.1. and I6 h ages. (f) To gel a lower hardness for preresrcd material. a set temperalure of 5 “C ( IO “F) higher than specified ma) he used cgr An addilional I IO I .S h af the spcsitied temperature oran additional 5 to IO “C I IO to 20 “FI for an additional I IO I .S h after agmg may be used IO loner hardness or other engineering propenics. I h) H I I SOhl is ao imermediate soft condition lhar must be re-solution heat lrcarcd IO obtain a different final condition. To get H I ISOM. solution heal meat. then heat at 76O”Cl I-KK”F~airsool to 30”C(9O”Rfor? to2.S h plus62O’C I 1150°F) ior-l h. ,i) l74PH and IS-SPH castings. H 9OOand H 925 time shall lx I.5 h Source: AMS 27591.1

798 / Heat Treaters Guide 17-4PH: Soak Times for Solution Heat Treating (Aerospace Practice) Product

form

Minimum soak time, solution heat treating, min(a,b)

17-4PH: Required Hardness After Aging (Aerospace Practice) Product

form

All Sheet All except sneet

3plus I minpereach0.25mm(O.OIOin.) 30per25mm(I in.)

(a)l’ime.+lO.-Omin.(b) Inallcasespartsare heldforsuff~cienttimetoensurethatthc center of the most massive sectton has reached temperature and the necessary uansformation and diffusion have taken place. Source: AMS 27.59/3

Condition H900 H 925 H 950 HI000 H 1025 H IOSO H 1075 H 1100 H IISO H I ISOM

Elardneas,

EIRC

401047 38 to 45 371044 36 to 43 34 to 42 32 to 38 31 to38 30 to 37 28 to 37 24 to 30

Source: AMS 275913

174PH: Microstructures. (a) Electrolytic: HNO,-acetic, then 10% oxalic. 1000x. Solution treated by holding at 1040 “C (1905 “F), 30 min. Air cooled (condition A). Structure: ferrite stringers in martensite matrix. (b) Electrolytic: HNO,-acetic, then 10% oxalic. 1000x. Solution treated, as (a). Aged 1 h at 480 “C (895 “F). Air cooled (condition H900). Structure: ferrite stringers in martensite matrix. (c) Electrolytic: HNO,-acetic, then 10% oxalic. 1000x. Solution treated, as (a). Aged 4 h at 550 “C (1020 “F). Air cooled (condition H1025). Structure: small ferrite stringers in martensite matrix. (d) Vilella’s reagent, 50x. Bar, solution treated at 1025 to 1050 “C (1875 to 1920 “F): Air cooled. Aged at 575 to 585 “C (1065 to 1085 “F). Air cooled (condition H1075). Banding resulting from alloy segregation appears as dark streaks in a martensite matrix. (e) Vilella’s reagent, 200x. Same as (d), except structure shows the banding blending with matrix. (f) Marble’s reagent, 75x. Spot welded sheet. Shows void-type defect (black) in the weld zone. Defect the result of microcracking

Cast PH Stainless Steels / 799 17-4 PH: Tensile Strength Conversions (Aerospace Practice) Product

form

Bar. forging. Sheet. strip. casting Bar. forging, Sheet. strip. casting Wmught casting Bar, forging, Sheel strip, Bar. forging. Sheet. strip, Bar. forging, Sheet. strip, Casting Bar, forging, Sheet. strip,

tubing. billet plate tubing, billet plate

tubing. billet plate Nbing. billet plate tubing, billet plate tubing, billet plate

Source: AMS 275913

Tensile strength minimum, MPa (ksi) 1310(190~ 1310~190) 1140(180) lLlO(l80) ll75(170) 1175(170) ll10(165) 103.5~150) 1070(Iss) lo7o(lss, 1000(11.5~ 1000~14SJ %5(140) %5 ( I-10) 895 I 130) 930(135) 930( 135)

to Condition

Condition H9OO H9OU H9tXl H 925 H 925 H 925 H 950 HIOOO H 1025 H 1025 H 1075 H 1075 H II00 H II00 H II00 H II.50 H II50

Cast PH Stainless Steels / 799

1717PH Chemical Composition.

AlSI/UNS (S17700):O.O!JC. 1.00 Mn,

0.040 P.O.04OS. l.OOSi.6.50to7.75

Ni. 16.OOto 18.00Cr.0.75

to 1.5OAl

Similar Steels (U.S. and/or Foreign). AMS 5528. 5529. 5568, 5644.5673.5678.5824; ASME SA705: ASTM A3 13. A5 IO, A56-l. A579. A693, A705; MtL SPEC MIL-S-25a3. MlL-W--16078; SAE J-t67; (Get) DIN 1.4568

17-7PH: Required Hardness After Aging (Aerospace Practice) Product form All

Characteristics.

Semiaustenitic type I7-7PH combines high strength and hardness with excellent corrosion resistance. Spring wire can be produced by severe cold drawing, followed by hardening with a single lowtemperature heat treatment. Applications include springs. knives. and pressure vessels

Forging.

Forge within

Recommended

range of 1040 to I I50 “C ( 1905 to 2 100 “F)

Heat Treating

There can be variations in the treatment different heat treating procedures are:

Practice for this type. Details of two

Condition RH 950 RH loo0 RH 1050 RH IO75 RH I100 In 9.50 I-H IO(w) I-H IOSO TH 1075 TH II00 CH900

Aardness, ARC 42 to 49 411046

401045 38 IO 43 34to-lO 42 to 18 40 to 16 38to4-1 37 IO 42 33 1039 46min

Source: XklS 275913

Heat Treatment No. 1 l l l l

Mill anneal at 1065 “C (I950 “F). Fabricate Heat to 790 “C (I455 “F) for I .5 h Cool to room temperature within I h and hold for 0.5 h (condition T) Heat to 565 “C (1050 “F) for I.5 h and air cool (condition THl050). Hardness, 43 HRC

Heat Treatment No. 2 l l l l

Mill anneal at 1065 “C (1950 “F). Fabricate Heat to 955 “C ( 1750 “F) for IO min Cool to -74 “C (-100 “F) and hold for 8 h (condition R 100) Heat to 510 “C (950 OF) for I h and air cool (condition Hardness. 47 HRC

RH950).

17-7PH: Tensile Strength Conversions (Aerospace Practice)

to Condition

Product form

Tensile strength minimum, MPa (ksi)

Condition

Sheet. strip Plate Bar Sheer. strip. plate BZU Wrought Sheet. ship. plate, \\eldrd tubing Blu Sheet. strip

1.wl(210) 1380(200) 127S(l85) 12JOtl80) 1175~170) 1035(150) 12~0(180) 1180~170) (varies with Thickness)

RH950 RH950 RH 950 RH I050 RH IO.50 RHIIOO I-H 1050 TH 1050 CH 900

Source: AhlS 275913

800 / Heat Treaters Guide 17-7PH:

Heat Treating Procedures (Aerospace Practice)

Fiial heat treat condition(a)

RH950 RH loo(J RH I050 RH 1075 RH II00 TH 950 TH 1000 TH IO.50 TH 1075 TH II00

Solution heat treating, set temperatures, “C (OF)(b)

Solution heat treating, cooling(c)

1050r1925, 1050~19’51 lOSOtl925~ lO50( 1925) 1050119,5~ 1OSOt1975, IOWt 1925, 1050119~.51 I0501 IPi, lO50( IY25)

Air Au Air Air Air Air Air Air r\ir Au

Austenite conditioning and transformation, ‘C (°FN4c)

9% I 1750).(b), air LXXIIto anlhientrind\\ ithm I h cool to twlou -70 t-90). so& 8 IO9 h. 3nd3ir u 3rmto smhientresul&in condition R 7601IU)OIfor’H)mlntohzlllu IS Ih(JlFornot le>j th3n30 min-rrwlh insonditionT

Aging set temperature, ‘C (“F)(d)

SlO~9Sll, 54of loool 56s I 1050) 5801I0751 595 1I IOO, slo(9sOt 540~IOOO) 565 I I ON) 580( 1075) S9SfllOO)

Ash time, hour(d.e,f)

1 1 I I.S I.5 I.S I .5 I .s

tu) Seetable for specified minimum tensile >tren@hcomersions IObenttre3tconditmn (b I Seetable tor so3hrime\ (cl heating solution treated material. Condition A. to 5 IO to 620 “C (950 to I I50 “F) for 4 h. then air cooled. Heat treatments follow (all times are at temperature): l

l

l

l

Condition A (solution treated or annealedj: Heat at 9X “C ( 1695 “F) +8 “C (IS “F) (time is dependent on section size). Cool to bsloa I5 T (60 “F) to completely transform material to martenslte. Normal practice is to hold at temperature I h. Sections under 330 cm? (36 in.‘) can be quenched in a suitable liquid quenchant. Larger sections should be air cooled Condition RH950 (precipitation or age hardened): Solution treatsd mnterial is cold treated to -74 “C t-100 “F) for 2 h minimum. Parts are air warmed to room temperature-this must be done within 24 h after solution treatment. Cold treated material is heated to 5 IO “C (950 “F) for 4 h. then air cooled Condition H950. HIOOO. Hl050. HI ISO(precipitation or age hardened): Solution treated material is heated at specified temperature +6 “C (+I0 “F) for 1 h. then air cooled Condition HI ISOh (precipitation or age hardened): Solution treated material is heated at 760 “C t 1400 “Fj +6 “C (+I0 “F) for 2 h. Air cooled then treat at 630 “C ( I I SO “F) +6 T (+ IO “F) for 4 h then air cooled

He3t treating after overaging. ln the HI I SO and HI I SOM overaped condition. this alloy will not respond to furtheragingtreatmrnt. For forging, optimum cold heading, and machining. the material must be solution beated at 925 “C t 1695 “F) afteroveraginp and before subsequent aping. Also. hardness Cabot be used to distinguish between the HI I.50 and solution treated conditions because the HI IS0 hardness falls within the hardness range for the solution-treated condition

PH13-8Mo: Typical Cryogenic and Elevated Temperature Tensile Properties. Specimen was 19 mm (0.75 in.) round bar in Hl 000 condition.

Source:

Carpenter

Technology

Corporation

810 / Heat Treaters Guide PH 13-8 MO: Soak Times for Solution Heat Treating (Aerospace Practice)

PH 13-8 MO: Heat Treating Procedures (Aerospace Practice) Fiial beat treat condition(a) H 950 HIOOO H 1025 H 1050 H 1100 H II50 H I I50M(h)

Solution heat treating, set temperatures, OC wm 925 925 925 9’5 92s 925 925

Solution beat treating, cooling(c)

( 1700) Air. oil. or polymer I 1700) lOhel0~ lS”C(60 ( 1700) “F) within I h(g) ( 1700) ( I7001 ( l7CM.N I 1700)

Agingset temperature, OC (“F)(d) SlO(9SO) S40(1000) SSO(102S) 565 ( 1050) 595 (I 100) 62O(llSO) (h)

Product Aging time, bour(d.e,f)

;t 4 4 4 4 (h)

la) See table for specified minimum tensile strength conversions IO heat neared condition.(h~Seetableforsoaktimes.(c~Airmeansairora~osphere.(d)~me.+lO.-Omin for 30 min ages: + 15. -0 min for I h ages: +30 min. -0 min for I .S h ages: and +15 min for3.1.and I6 hages. (e)Toget louerhardness forpretes~edmarerial,aset remperature up IO 6 “C ( IO “F) higher man specitied may be used. (0 An additional I to I .S h at the specifiedremperamreoranadditional6 IO IO”Cil0 to 20 “F) foranadditional I to I.5 h after aging ma) be used to lower hardness or other engineering properties. (g) Artificial means may be used to cool below ambient [emperature when necessary 10 get below 3O”C(9O”F)orbelow 15”C(60°F).(h)H Il50Misaninrermediatesoftcondition that must be re-solution heat ueated to obtam a different tinal condition. To obtain H I ISOM. solution heat treat. then heat al 760 ‘C ( I-100 “F). air cool below 30 “C (85 “F) for 2 to 2.5 h, plus 620 “C ( I IS0 “F) for 4 h. Source: AhlS 27.5913

Minimum soak time, mh(rqb)

form

All

30 per 25 mm ( I in.)(a)

(alTime. +10.-O.(b) Inallcases.pansare held forsufficient timetoensuretharthecenter of the most massive section has reached temperawe and the necessary ttansformation and diffusion ha\ e taken place. Source: AMS 275913

PH 13-8 MO: Tensile Strength Conversions Condition (Aerospace Practice) IUhimum Tensile strength. MPa (ksi)

Form(a) B. B. B. B. B. B.

F.T. F. T. F. T, F. T. F.T. F. T,

Bi. Bi. Bi, Bi. Bi. Bi.

P P P P P P

to

Condition

lS20(220) 1415 (205) 1275 (185) 1210(17S) 1035(150~ 930(135J

H 950 HI00 H 1025 H 1050 H II00 H 1150

(a) B. bar: F. forging; T. tubing: Bi. billet: P, plate. Source: Ah4.S 2759/3

PH 13-8 MO: Required Hardness After Aging (Aerospace Practice) Product

form

All

Source: AhlS 275913

Condition H 950 HICOO H I025 H 1050 H II00 H IISO H I l50M

Ehrdocss.

ERC

45 to 49 43 to 47 41 to46 401046 34 to 42 30 IO 38 28 to 36

Heat Treating Chemical

Composition

Gray irons usually contain 2.5 to JCC carbon, I to 3% silicon, and additions of manganese (as low as 0. IO 9 in ferritic gray irons and as high as 1.2% in pearhtics). Sulfur and phosphorus are present in small amounts as residual impurities.

General

All strength properties,

Specific User properties wear reststance.

Flake graphite IS dispersed in a matrix ti ith a microstructure deterrnmed by composition and heat treatment. hlatrx structurrs resulting from heat treamlent can vary from ferritepearlite to t2mpend martensitc. Standard compositions ar2 pressnkd in adjoining tables.

Characteristics

ASTM A 48 classifies gray irons in temrs of tsnsils strength. but m many applications strength is not the critical property. Lou stmngth grades. for example. are superior performers whrre resistance to h2at checking is the prime property. According to the ASTM ratmgs, class 20. th2 Iovvest strength grade, has a minimum tensile strength of I-IO hlPa (20 ksij; vvhilr class 60. the highest strength gadr. has a tensik strength of -llO MPa (60 ksi). Generally it can be assumed that the following properties improve with increasing tensile strength: l

of Gray Iron

including

those at elevated

l l

hlodulus of elasticity Resistance to wzar Convrrsely.

l l l l

some properties

deteriorate

hlachinability Resistancz to thermal shock Damping capacity Castability-in temrs of ability

with decreasing

tensile strength:

to produce thin sections

temprratures

Characteristics of interest include

impact resistance,

machinability,

and

Impact resistance. Gray iron is not mcommendsd where high impact resistance is needed. Two methods of tcstinp for this property are given in ASTM A 327. Machinability. Most gray iron castmgs have better machinability than most other irons ofequivalent hardness, as well as that of I irtually all steel. ln addition. substantial gains m machmability are available through annealing (see heat treating sectton). Wear. Gray iron. in both the as-cast and hardened conditions. is used widely for machine components that must stnnd up to various types of wear. Hardening provides the most sipnikant Improvement m resistance to nomral wear. and is specified for maximum resistance to wear in severe wear applications. Dimensional Stability. The most demanding applications at elevated temperatures are those in which dimensional accuracy is important. Dimensional stability is degraded as temperature and exposure time increase. This property is affectrd by factors such as growth. scaling, and creep rate. Growth. Breakdown of pearlite to ferrite and graphite IS the cause. The remedy: additions of alloying elements such as coppzr. molybdenum. chromium, tin. vanadium, and manganrse. They stabilize the carbide structurr. Scaling. In a series of tests, temperature had a greatzr effect than time at temperature. For example. the extent of scaling at 350 “C (660 “F) over

a period of I I .S years was,-! mgkm’. while exposure of 64 weeks at 500 ‘C (930 “F) was I6 mE/cm-. In the sam2 study, it was found that differences in alloy contrnt had only minor 2ff2cts on scaling. Creep. This propsrty is improved with additions of chromium and molybdenum. When parts operate at temperatures undzr 480 “C (895 “F). two mom sources of dimensional accuracy must be considered: residual stresses and machining practice. Residual stresses. Residual strrsses a-2 present in all castings in the as-cast conditton. but only a small percentage are strrss relieved before machining-chiefly thosr requiring exceptional dimensional accuracy, or those with a combinatton of high or nonuniform stress associated with low section stilkss or an abrupt change m section size. Castings of class 40. 50. and 60 iron are more likely to contain high residual stresses. Machining practice. Because the surface of a casting is often the main sit2 of rzsidual str2sses, a large amount of stress is relieved by rough machining. If before tinal machining, th2 casting is relocated in the machine carefully and supported in cool fixtures, acceptable dimensional accuracy usually is obtained in the finished workpiece. Annealing. This is another way of improv ing machinability (discussed in th2 next section).

Recommended and Processing

Heat Treating Sequences

Practices

Annealing and strsss relizving are the two most common methods of heat treating gray iron castings. Annealing is the most frequently used.

Heat Treating Other suitable processes include normalizing, hardening and tempering. austempering, and martempering. Flame hardening and induction hardening are alternatives to electrically heated, gas. or oil-fued furnaces and salt bath processes. Both annealing and hardening have disadvantagrs: l

l

Ann~alirrg-this process improves machinability. but there is a price: properties are reduced approximately to the next lower grade of gray iron Hczrdfning-Hardening and quenching from elevated temperaturss strengthen castings, but the process ordinarily is not used for this purposr in commercial practicr. Th2 more economical rout2 to the desired result is to reduce silicon and total carbon, or by adding alloying el2ments. When gray iron is quenched and t2mpered. the common reason is to bzsf up resistance to wear and abrasion by mcrensing hardness with a structure consisting of graphite embedded in hard martensite

Annealing Practices. Gray iron nomlally treatments: ferritizing tizing annealing.

annealing.

medium

is subjected to on2 of these (or full) annealing. and graphi-

Ferritizing process. It generally is unnecessary IO heat unalloyrtd or low alloy gray iron to temperatures above the transition range when the sol2 purpose is to convert pearlitic carbide to ferrite and graphite for improved machinability. The recommendzd f2rritizing annsaling temperature for most gray irons lies between 700 to 760 “C ( 1290 to l-i00 ‘F). When stress relief is the objective. slow cooling to room temperature is recommendzd. A cooling rate rangmp from I IO “C (230 “F) per h to 290 “C (555 “F) per h is satisfactory for all but the most complrx castings. Medium (full) annealing. This treatment is the choice when a femtizmg anneal would be ineff2ctive because of high alloy content of a particular iron. Annealing usually is perfomred at tempsratures between 790 to 900 ‘C (1155 to 1650 “F). Holding times usually are comparabl2 to those for the ferritizing process. Howev2r. when temperatures are at the high end of the range. castings must be cooled slowly through the transformation rang2 from approximately 790 to 675 “C ( l-t55 to IX5 “FL Graphitizing annealing. To break down massive carbides to prarlite and graphite with reasonable speed, temperatures of at least 870 “C (,1600 “F) are required. With each additional 55 “C ( I30 “F) incrzment in holding temperature. the rate of carbide decomposition doubks. General practtce IS to use holding temperatures of 900 to 955 “C ( 1650 to I750 “F). Holding time at temperature can range from a few minutes to several hours. Cooling rate depends on end use. For maximum strength and w2ar resistance, castings should be air cooled from the annealing temperature to approximately 540 ‘YY (1000 “F) to promote the formation of a pearlitic structure. For maximum machinability. castings should be furnace cooled to 5-10 “C (1000 “F), and special care should be taken to ensure slow cooling through the transformation range. In treating for maximum strength and wear resistance and maximum machinability, cooling from 540 ‘C (1000 “F) to approximately 390 ‘C (555 “F) at a rate of not more than I IO “C (730 “F) per h is recommendsd to minimtze residual stresses. Gray iron m the as-cast condition contains residual stresses. Esception: much of the solidification stress is rrmoved when the iron is cooled in the mold. The stress relieving temperature usually is w2ll below the range for thr transformation of pearlite to austenite. For maximum stress relief with minimum carbide deposition in unalloyed irons. a temperature range of S-IO to 565 “C (1000 to 1050 “F) is desirable. When almost complete stress relief (>85%) is required in unalloyed iron, a minimum temperanus of 595 “C (I I05 “F) can be used. Rate of heating. For stress relief. the heating rate dzpends on ths sizs and shape of the castmg. However. the rate. except for the most complex shapes. is not especially critical. Rate of cooling. Slow cooling from the stress-relieving temperature. at least in the upper temperature rangs. is essential. The general recomm2ndation is furnace cooling to 3 IS “C (600 “F) or lower, before air cooling. When designs are intricate. it may be advisable to continus fumacs cooling until a temperature of approximately 95 “C (705 “F) is reached.

Iron Casting

and P/M Steels / 817

Normalizing Practices. Gray. iron is nomlalized by being heated to a temperanus above the transfomuttton range: held at this temperature for a period of npproxtmately I h per Inch of maximum section thickness: then cooled m still air to room temperature. Normalizmp senes a variety of functions. including the enhancement of mechanical properties. such as hardness and tensile strength: and the rrstoration of as-cast properties modified in other heating processss. such as prnphitizing annsnling or the prrhsnting and postheating associated with welding. The tempernrurr rang2 for normalizing is approximatsly 885 to 925 “C t 167-S to 1695 “FL Tensils strength and hardness dspend on combinsd carbon content. pearlite spacing tdistancc betw 22n c2mentite plates), and graphite morpholOP.“. Hardness can b2 partially controlled by allowing castings to cool in the furnacs to a tcmperaturz bslow the normalizing temperature.

Hardening

and Tempering

Practices

hkchanical properties. strength and wear rzsistance tn particular. are Improved by thes2 treatments. Hardened and tempered gray iron has approximately five times mars rssistnnct: to wear than pearlitic gray iron. Furnace or salt bath hardening have a much broader application rang2 than those of Flame and induction hardening. In the latt2r two processes. a relativeI\ high total carbon content IS weded because of the extremely short time available for the solution of carbon in aust2nue. By contrast. in furnace or salt bath hardsning. a casting can be held at a temperature above the transformation range for as long as necessary. An unalloyrd pray iron with a combined carbon content of 0.60%, has hiphsr hardcnability than a carbon steel with the same carbon content. Reason: the gray iron has a higher silicon contznt. The hardcnability of gray iron is increased via the addition of a variety of alloving elements: manganese. nisk2l. copper. and molybdenum. Also, chron&m~ contributes to carbidr stabilization. which is especially important in flam2 hardening. Chromium does not influence the hardenability of gray iron. Hardening cycle. In nustenitizing. castings are heated to a temperature high enough to promots thz formation of austeniv: held at that temperature until the desu2d amount of carbon has bern dissolved; then quenched at a suitabl2 rate. Heating temperaturr is drtzmrin2d by the transformation range of a given gray uon. A formula for determining the approximate At transfomration temperature of unalloyed iron is. “C~730+78.0~~ Sir-25.Ot%hlnt ‘-F. 131S+riO11’iS1)-3S.Ot~hln, Chromum~ raises the transformatton range of gray iron. Castings should b2 treated through th2 lowsr temperature rang2 slowly to avotd cracking. At t2mp2ratures in a rang2 of 595 to 650 “C (I I05 to I200 “F) abovc the stwss relirv tng range, heatmg may not be as rapid as dssirsd. Quenching. hlolten salt and oil are the most frequently used quenchants. Watzr prnsrally is not suitablt: for quenching furnace-heatrd gray iron: heat IS rxtractsd so rapidly that distortion and cracking In all castings are likzly except those simple in drsign. Ib’atcr-solublz polymer quenchants a-2 an option to provid2 cooling rates betwen those of water and oil and to minimize themral shock. Air is the least sever2 quenching medium. But both unalloyed and low alloy gray Iron can’t be air quenched because the cooling rate is not fast rnough to form martensitz. Air. hovvever. is frequently the most desirable cooling method for high alloy grades. Tempering practice. Castings usually are tempered after quenching at temp2raturzs well bclovv the transformation rang2 for approximately I h per inch of thichest wction. Hardness decreases with tempering. while. usually. strength and toughness rise.

818 / Heat Treaters

Guide

Austempering and Martempering Practices. The maximum hardness obtainable with austempering usually is less than that available in martempering. However. the difference may be largely offset during the tempering treatment usually required following martempering. But in comparison with conventional oil quenching, less distortion and growth are experienced in austempering and martempering. Austempering Process. In this treatment. gray iron is quenched from a temperature above the transformation range in a hot quenching bath, and is maintained in the bath at constant temperature until the austempering transformation is complete. Quenching usually is in salt, oil, or lead baths at temperatures in the range of 230 to 425 “C (445 to 795 “F). When high hardness and resistance to wear are specified, quenchant temperature usually is held between 230 to 290 “C (-l-IS to 555 “F). Holding time for maximum transformation is determined by quenching bath temperature and composition of the iron. The effect of the latter on holding time may be considerable. Alloy additions such as nickel. chromium, and molybdenum Increase the trme required for transformation. Martempering Process. In this instance. martensite is produced minus the high stresses that usually accompany its formation. Martempering is similar to conventional hardening, except that distortion is minimized. Also, martensite retains its characteristic brittleness. For this reason. martempered castings are almost always tempered. Castings are quenched from above the transformation range in salt, oil, or lead baths; held in the range at which martensite forms [?OO to 260 “C (390 to 500 “F) for unalloyed irons] only until the casting has reached the bath temperature; then it is cooled to room temperature. For a wholly martensitic structure. the casting must be held in the hot quenching bath only long enough for it to reach the temperature of the bath. If dimensional accuracy is important, allowance for growth must be made prior to heat treatment. Some distortion. in comparison with growth. occurs during mat-tempering. Conditions that may promote excessive distortion are: residual stresses from casting, machining, or rapid cooling during previous heat treatments; insufficient time for establishing equilibrium at the austenitizing temperature: and drafts during air cooling after castings have been removed from the quench tank. Flame Hardening Process. This is the surface hardening process most often applied to gray iron-both unalloyed and alloyed grades. As a rule. combined carbon content should be in the range of 0.50 to 0.70%, but irons with as little as O.-IO%, combined carbon can be flame hardened. Generally, the process is not mcommended for irons containing more than 0.80% carbon because they can crack. For maximum hardness, it is advisable to use an iron containing as little total carbon consistent with the production of sound castings free from any likelihood of cracking. Because silicon promotes the formation of graphite and of a low combined carbon content, a relatively low silicon content is advisable, i.e.. silicon content should not exceed 2%, and manganese content should be held in the range of 0.80 to I .OO~ to increase carbon solubility in austenite. Room-temperature hardness of gray iron after normalizing. Effect of temperature at start of aircooling on hardness on normalized gray iron rings 120 mm (4% in.) in outside diameter, 95 mm (3% in.) in inside diameter, and 38 mm (1% in.) in length

In addition, gray iron should be as free as possible from porosity and from foreign matter such as sand or slag. Porosity and even small inclusions can produce a rough surface or cause cracking after hardening. In general, alloyed gray irons are easier to flame harden than unalloyed grades, partly because alloys have greater hardenability. Maximum hardness of nonalloys is obtained with a composition of approximately 30’0 total carbon. I .7% silicon, 0.60-0.800/b manganese. Hardnesses range from 400 to 500 HB. Stress relieving. When practical or feasible economically, flame hardened castings are stress relieved at I50 to 200 “C (300 to 390 “F) in a furnace, in hot oil, or by passing a flame over the hardened surface. Benefits are minimized distortion or cracking and an increase in the toughness of the hardened layer. Hardness. The surface of a flame hardened casting is typically lower than that of the metal immediately below the surface. Surface hardness often can be raised by heating in the range of I95 to 250 “C (385 to 480 “Ft. Fatigue strength. This value is usually improved because the treatment induces compressive stresses at the surface. Quenching. Quenchants are selected on the basis of the flame hardening method used: l

l

Progressive mefhod: only nonflammable media are used, such as water, soluble oil mixtures, and water solutions of polymers. Conventional oil can’t be used because of the fiie hazard Spar tmrdtwing or spinning melhods: conventional quenching by immersion in hot oil is used. In these methods, the flame head is withdrawn from the part prior to quenching

For best results in using water. water temperatures should be around 30 “C(8S”F). To suppress cracking, lower quenching rates are obtained by using 5 to 15% soluble oil mixtures. compressed air. or compressed air and water at low pressures. Air quenching is especially suited for highly alloyed irons because of their susceptibility to cracking. Induction Hardening Process. Hardnesses obtained are influenced by carbon equivalent (G C + 1/36 Si) when this value is measured by conventional Rockwell tests. The amount of graphite in the microstructure can have a negative effect on surface hardness: the higher the volume of graphite, the lower the surface hardness. Induction hardening causes less distortion than that experienced in parts quenched after treatment in a furnace.

REFERENCES I. C.V. White, Gray hon. Vol I, ASM Handbook. p 12-32 2. B. Kovacs, Heat Treating of Gray Irons, Vol 4, ASM Handbook, I, 670-68 I

Effect of austenitizing time on room-temperature hardness of quenched gray iron specimens. Specimens were 32 mm (1% in.) in diameter by 19 mm (3/4 in.) in thickness

Heat Treating

Effect of annealing on tensile strength of class 30 gray iron. Specimens were arbitration bars from 31 heats. Bars were annealed at 925 “C (1695 OF)for 2 h plus 1 h per 25 mm (1 in.) of section over 25 mm (1 in.), and cooled from 925 to 565 “C (1695 to 1050 “F) at a rate not to exceed 160 “C (285 “F) per h. Cooling continued from that level to 200 “C (390 “F) at a rate not to exceed 130 “C (230 “F) per h; bars were then air cooled to room temperature

Iron Casting

and P/M Steels / 819

Effect of isothermal transformation temperature on hardness of austempered gray irons. Holding times were sufficient to complete transformation

COtWc?rSiOn of as-CaSt pearlitic structure of unalloyed gray iron to ferrite and graphite by annealing. (b) Annealed 1 h at 760 “C (1400 “F); 120 HB. Magnification, 500x

MiCrOStrUCtUrSS.

(a) As cast; 160 HB.

Distortion in gray iron cylinder liners after martempering and after conventional oil quenching. Before being measured, (390 “F)

liners were furnace tempered

for 2 h at 200 “C

820 / Heat Treaters

Guide

Effect of tempering temperature on gray iron. (a) to (c) Changes in mechanical properties of hardened low-silicon unalloyed gray iron. (d) Hardness of gray iron specimens quenched in oil from 870 “C (1600 “F) and tempered. Each point on this chart represents an average of five hardness readings

Typical hardness hardening

Types of graphite flakes in gray iron (AFS-ASTM). In the recommended of 100x. They have been reduced to one-third size for reproduction here

gradient

produced

in gray iron by flame

practice (ASTM A247), these charts are shown at a magnification

Heat Treating

Effect of stress-relieving cated temperatures

Stress-relieving

Iron Casting

and P/M Steels / 821

temperature on hardness of gray irons. Bar specimens 30 mm (1.2 in.) in diameter were held for 1 h at indi-

and then air cooled

time and temperature on degree of stress relief obtained in low-alloy gray irons. Table shows compositions

ligible effect of maximum stress-relieving

conditions on hardness

and neg-

822 / Heat Treaters

Microstructures.

Guide

Structure of class 35 iron, as-cast (left) and after annealing

Location and magnitude castings

Effect of Carbon Equivalent on Surface Induction-Hardened Gray Irons Composition, +(a) CllhOll C Si equivalent(b)

Hardness

of

Eardness ARC, converted from Rockwell As read 30-N hlicrohardness

Effect of Annealing 35 Gray Iron

on Hardness

Condition

hlPa

I.SO I .68 I .64 I .59 1.80

3.63 3.70 3.74 3.87 1.02

SO 49 48 47 46

50 50 SO 49 47

61 57 61 58 61

3.46 3.52

2.00 2.14

3.13 4.23

43 36

45 38

59 61

(a) Each iron also contained 0.50 IO 0.90 Mn. 0.35 IO0.55 Ni, 0.08 to 0. IS Cr. and 0. IS IO0.30 MO. (b) Carbon equivalent = ‘%C + I/,%, Si

and Strength

of Class

ksi

Eardness, ml

268 165

38.9 23.9

217 131

Tensile strength AS-GLSt

3.13 3.14 3.19 334 3.42

of residual stresses in two gray

Annealed

Compositionof iron: 3.30%. tomI C. 2.224 Si. 0.027%. P,O.l8% S,O.61% Mn. 0.03% Cr. 0.034 Ni, 0. I-!!% Cu. hlo nil. Annealing treamwnt consisted of I hat 775 “C (1425 “F), followed by cooling in the furnace to 540 “C ( 1000 “F)

Heat Treating

Hardenability

Data for Gray Irons Quenched

Iron Casting

and P/M Steels / 823

From 855 “C (1575 “F)

See adjoining Table for compositions. Distance fhm quenched end L/la mm increments 3.2 6.4 9.5 12.7 15.9 19.0 22.2 25.4 28.6 31.8 34.9 38.1 41.3 44.4 47.6 50.8 54.0 57.2 60.3 63.5 66.7

2 4 6 8 10 12 I4 I6 I8 20 22 24 26 28 30 32 34 36 38 40 42

Plain iron

MOW

54 53 50 43 37 31 26 26 25 23 22 22 ?I 20 I9 I7 I8 I8 I9 22 20

56 56 56 54 52 51 51 49 46 46 45 43 43 40 39 39 36 40 38 38 35

Elardness,ARC Ni-Mo MO(B) 53 5’ 52 51 50 49 46 45 45 4-l 43 4-l 4-i 41 40 40 41 40 37 36 35

5-l 51 53 53 52 52 52 52 52 51 17 17 47 15 15 -t5 4-i 45 45 -I? 31

Compositions

of Gray Irons Listed in Adjoining

Table

Iron

TC

CC(a)

Mn

Composition, % Si Cr

Plain WA) MO@) Ni-Mo Cr-Mo Cr-Ni-Mo

3.19 3.22 3.20 3.22 3.2 I 3.36

0.69 0.65 0.58 0.53 0.60 0.6 I

0.76 0.75 0.64 0.66 0.67 0.74

1.70 I .73 1.76 2.02 2.2-l I.96

(a) CC. combined carbon. (b) GC, graphirecarbon

2.50 2.57 2.62 2.69 2.61 2.75

0.03 0.03 0.005 0.02 0.50 0.35

Cr-Mo

Cr-Ni-Mo

56 55 56 5s 55 54 5-I 54 53 SO 50 49 47 47 44 -II 38 36 31 35 32

55 55 54 54 53 53 52 53 52 51 50 50 49 48 50 47 46 45 46 46 45

Ni

MO

P

s

Tl-Xe I.21 0.06 0.52

0.013 0.47 0.48 0.52 0.52 0.47

0.216 0.212 0. I87 0.114 0.ll-t 0.158

0.097 0.089 0.054 0.067 0.071 0.070

Heat Treating Chemical

Ductile

Composition

Standard compositions and general uses of ductile iron are listed in an accompanying table. Most compositions for standard grades are hased on properties. i.e., strength and/or hardness: composition IS loosely specified or made suhordinate to mechanical properties. Ductile iron is now accepted internationally as the name for these irons. It is also called nodular iron or spheroidal graphite ISG). The unique feature of this iron is the presence of graphite in the form of tin) spheres. (nodules). See accompany inp microstructures. Microstructures are grouped into [no hrond classes:

The ferrite structure usualI> is produced in annealing. normalizing, normalizing and tempering. or quenching and tempering. The austenitic structure is produced by austempering, an isothermal process resulting In a product known as austempered ductile iron (ADI). Stress relief annealing does not involve major microstructure transformations, while selective surface treatments. i.e., flame and induction hardening. do in selectively controlled areas of a casting. Similar Cast Irons (U.S. and/or Foreign). Accompanying tables provide information on: l

l

l

Those in which the major iron-hearing matrix phase is the thermodynamicallq stable, hody-centered cubic (ferrite) structure Those with a matrix phase that is a metastahle. face-centered. cubic (austenite) structure

General

l

l

Mechanical properties and typical applications of standard ductile irons (ASThl, ASME, SAE-AhlS specifications) Ductile iron property requirements of various national and international standards (ISO. ASTM. and SAE) Some tentative specifications for austempered ductile iron (U.S., Swiss, and Great Britain)

Characteristics

Basic differencss between ferritic and austenitic ductile iron are sxplained in an nccompan) ing continuous cooling transformation diagram (CCT), along with cooling curves for furnace cooling. air cooling. and quenching. Examples of the subsequent microstructures are shown in an accompanying figure. A second figure is an isothermal transformation (IT) diagram showing a processing sequence for austempering. The relatively high strength and toughness of ductile iron give it an advantage over gray iron and malleable iron in many structural applications. In addition. because ductility does not require heat treatment to produce graphite nodules. as does malleable uon to produce temper-carbon nodules. it can compete with malleable iron even though it does require a treatment and inoculation. Ductile iron has many applications requiring strength and toughness combined uith good machinability and low cost. Ductile iron has about the same machinability as gray iron of similar hardness. At tensile strengths up to approximately 550 hlPa (80 ksi) ductile iron has better machinability than that of cast mild steel. At higher hardnesses, differences are less pronounced. Special materials and techmques &areavailable to repair weld ductile tron or to join it to itself and to other materials such as steel. gray iron. or malleable iron. Special precautions are needed to get optimum properties in the ueld metal and in the heat affected zone. The main obJective is to avoid the formation of cementite in the matrix material. which makes the LieId zone brittle. Another must is to retain graphite in its nodular form. Martensite or tine pearlite can he removed hy tempering.

Recommended and Processing

Iron

Heat Treating Sequences

Practices

Ductile irons are heat treated prim‘arily to create matrix microstructures and associated mechanical properties not readily obtained in the as-cast condition. The most important heat treatments are:

Stress relieving-a low temperature treatment to reduce or relieve internal stresses remaining after casting Annealing-to improve ductility and toughness, to reduce hardness. and to remove carbides Normalizing-to improLe strength while retaining some ductility Hardening and tempering-to increase hardnesses or to improve strength and raise the proof stress ratio Austrmperinp-to produce a microstrw%re that provides high strength uith some ductility and good resistance to wear Surface hardening-to produce selective we;LT resistant surfaces with flame. mductlon. and laser processes. for example Stress Relieving Ductile Iron. IVhen not otherwise heat treated, complex enpineermg castings are stress relieved at 510 to 675 “C (950 to I145 “F). Temperatures at the lower end of the range are adequate in many applications. Those at the higher end eliminate virtually all residual stresses, hut at the cost of some reduction in hardness and tensile strength. Recommended stress-relies ing temperatures for different types of ductile iron are as follows: l Unalloyed: . Low alloys: l High alloys: l Austcnitic:

510 to 565 ‘C (950 to 1050 “F) 565 to 595 “C (1050 to I IO5 “F) 595 to 650 “C ( I I OS to I200 “F) 620 to 675 ‘C ( I I.50 to I245 “Fj

Cooling should he uniform to avoid the reintroduction of stresses. Practice is IO furnace cool to 190 “C (555 “F), then air cool, if desired. Austenitic iron can he uniform)! air cooled from the stress relieving temperature. Annealing Ductile Iron. Castings usually are given a full ferritizing anneal for good machinability when high strength is not required. The treatment produces ASThl grade 60--IO- 18. For good machinability, manganese. phosphorus, and molj bdenum should he as low as possihle. Recommended practice for castings n ith differing alloy contents and for castings with and ~tithout eutectic cnrhides follows:

Heat Treating Ftrll anneal for unalloyed ? to 34 Si irorl that does not contain etrtectic carbide: heat and hold at 870 to 900 “C (1600 to I650 “F) for I h per inch of section. Furnace cool to 345 “C (655 “FI at 55 “C (I 00 “F) per h; air cool Full anneal with cm-bide present: heat and hold at 900 to 925 “C i I650 to 1695 “F) for 2 h mimmum-longer for heavier sections. Furnace cool to 700 “C ( I290 “FI at I IO “C (200 “F) per h. Hold 2 h at 700 “C ( 1290 “F). Furnace cool to 315 “C (655 “F) at 55 “C (100 “F) per h. Air cool Subcritical ormeal to cornwt pearlite to ferrite: heat and hold at 705 to 720 “C (300 to I330 “F). I h per inch of section. Furnace cool to 345 “C (655 ‘F) at 55 “C (100 “F) per h. Air cool

Hardenability

of Ductile Iron. This is an important

parameter for detcmining the response of a given gray iron to normalizing. to quenching and tempering. or to austemperinp. Normally this value is determined bj the Jommy test: a standard bar [25.-l mm ( I in.) in diam bj 100. I6 mm (4 in.) in length] is austenitized and water quenched at one end. Normalizing Ductile Iron. In this treatment (austenitizing followed by air cooling). tensile strength is improved considerably: and the process may be used to produce ASTM type 100-70-03 iron. Normalizing temperatures usually range between 870 to 910 “C ( I600 to I725 “FJ. Standard time at temperature is I h per inch of section. or a minimum of I h. Longer times may be needed when alloys contain elements that retard carbon diffusion into austenite. Normalizing sometimes is follo\sed b) tempering to obtain a desired hardness and to relieve residual stresses that develop in air cooling m hen areas of a casting with different section sizes cool at different rates. Also, tempering after normalizing is a \\ay to obtain high toughness and resistance to impact Tempering usually conststs of reheating to 325 to 650 “C (795 to I200 “F) and holding at the desired temperature I h per mch of cross sectlon. Quenching and Tempering Ductile Iron. Prior to quenching and tempering. commercial castings normally are austenitized at 845 to 925 “C (IS55 to 1695 “F). To minimize stresses and quench cracking. oil is the preferred quenchant. Water or brine may be used H hen shapes are simple. Oil heated to 80 to IO0 “C ( I75 to 2 IO “F) is used to avoid cracks when castings are complicated. Castings should be tempered immediateI> after quenching to relieve quenching stTesses. Tempering in the range of 425 to 600 “C (795 to I I IO “F) reduces hardness. the amount depending on alloy content, initial hardness. and time. Austempering Ductile Iron. An austempered structure of austenite and ferrite provides optimum strength and ductility. The austempered matrix is responsible for a significantly better tensile strength-to-ductility ratio than is possible with any other grade of ductile iron. Production of these properties calls for careful attention to section size and to time/tsmperature exposure during austenitizing and austempering. As section size increases, the rate of temperature change between the austenitizing and austempering temperature decreases. Quenching and austempering techniques include. l l l l

Hot oil quenching (< 240 “C. or 465 “F. only) Nitrate/nitrite salt quenches Fluidized bed quenching (only for small, thin parts) Lead baths (for tool-type applications)

Austenitizing temperatures between 8-U to 925 “C (I 555 to I695 “Fj are normal: and times of about 2 h have been shown to recarburize the matrix fully. Properties obtained in austempering \ary with temperature and time. Effects of temperatures ranging from 240 to 440 “C (465 to 825 “F) on yield strength. tensile strength. and impact strength are shown in an accompanying figure. Reaching maximum ductility at a given temperature is a time sensitive function. After maximum ductility is attained. further austempering reduces ductility. In an accompanying figure. this relationship is shown at times of temperature ranging from 8 to approaimatel) 200 min. Tempera-

Iron Casting

and P/M Steels / 825

tures run from 357 to 400 ‘C (675 to 750 “Fj. Typical \ary from I to-l h.

Surface

Hardening

This iron readily l l l l

of Ductile

responds to a ~ariet!

austempering

times

Iron of surface hardenmg processes:

Flame hardening Induction hardening Nitriding-comentional. salt bath, and plasma processes Laser or plasma torch hardening

Pearlitic types of ductile iron. XSThi 80-60-03 and 100-70-03, are preferred for hardening applications because all of these treatments take place in seconds. Lrons that do not contain free femte in their microstructures respond almost instan!ly to name or induction heating and need little holding time at their austcnmzing temperatures to become fully hardened. Given proper technique and temperature control between 815 to 900 “C t IS55 to I650 ‘F), surface hnrdnesses that can be expected with different matrices are: l

l

l

l

Fully annealed t ferritic) iron. water quenched behind the tlame or induction coil. 35 to 45 HRC Predominantly ferritic ipanlj pearlitic) iron. stress relieved prior to heating. self-quenched. 40 to 15 HRC Predominantly ferritic (partI> pearlitic) iron, stress relieved prior to heating. Water quenched. SO to 5S HRC hlostly pearlitic iron. stress relieved before heating. water quenched. 58 to 62 HRC

Induction hardening. Response depends on the amount of pearlite in the matnx m the as-cast. normalized. and normalized and tempered conditmns Percentages of pearlite or ferrite required in each condition are: As-castcorlditiorl-minimum

of 50ci pearlite to get satisfactory hardening with heating cycles of 3.5 s and longer at hardening temperatures of 955 to 980 “C t, 1750 to 1795 “F). Castings can be hardened at higher temperatures M hen structures conrain less pearlite. but at the risk of damaging surfaces. \Vith pearlits aboLe 508,. hardening temperatures may be reduced m ithin the range of 900 to 925 “C ( I650 to I695 “F) Norma/i:ed rorrditiorl-for quenching cycles of 3.5 s and longer. temperatures of 945 to 980 “C t 1750 to 1795 “F). 508 pearlite in a prior structure is a minimum Qlrerrched orrd /enl~ert~d-the response is excellent over a wide range of microstructures containing up to 9% ferrite. Quenching and tempering. as a prior treatment. pemlits a lower prior hardness, but there is a risk of distortion and quench cracking

Nitriding Ductile Irons. Case hardening can be carried out with conventional plasma.

nitriding.

or in liquid

salt baths based on cyanide

salts. or in a

Conventional process. Nitrogen diffuses into surfaces at temperatures ranging approximately 550 to 600 “C ( 1020 to I I IO “F). Ammonia usually is the source of nitrogen. A surface layer. typically white and featureless in an etched nucrostructure. of approximately 0. I mm (0.00-I in.) deep is produced. Surface hardness is close to II00 HV. Additions of alloying elements can increase hardness, i.e., OS to 1% Al, Ni. or MO. Advantages of nitriding in addition to very hig,h hardnesses. are: better resistance to \\ear and scuffing, plus improved fatigue life and resistance to corrosion. Salt bath treatment. Temperatures are lower. but case depth is less than that obtained H ith the con\ entional process. Nitriding in plasma. A recent development. At this time, the need for special equipment and processing costs may be deterrents to usage. Laser/plasma torch processes. This technology makes it possible to produce tiny. remelted areas on selected surfaces of castings. The heated area rapidly solidities because of the self-quenching effect of the mass of the casting. The result is a white iron structure that is substantially free of graphite and has a combination of high hardness and resistance to wear.

826 / Heat Treaters

Guide

The area heated by a 2.5 kw laser is typically 1.5 mm (0.06 in.) in diameler by 0.5 IO 1 mm (0.02 to 0.08 in.) in depth. Hardness of approximately 900 HV is produced without cracking.

REFERENCES I. L.R. Jenkins and R. D. Forrest. Ductile Iron, Vol I, ASM Handbook 2. K.B. Rundman, Heat Trealing of Ductile Iron, Vol4. ASM Handbook

Microstructures. Microstructures of ductile iron. (a) As-cast ferritic. (b) As-cast pearlitic; hardness, 255 HB. (c) Fertitic, annealed 3 h at 700 “C (1290 “F). (d) Pearlitic ductile iron oil quenched and tempered to 255 HB. All etched in 2% nital. 100x

Heat Treating

ASTM Standard

A 897-90 and A 897M-90 Mechanical h4Pa

ksi

80

850

IO0

I50 700

125

175 850 . II00 . 1300

200 l4Cil 230 1600

I55 185

and P/M Steels / 827

Ductile

Iron

impact(a) J

IO IO 7 7 4 4 I I (b) (b)

550

1050 . 1200

of Austempered

Elongation, %

ksi

I25

125-80-10 850-550-10 150-100-7 IO50-70-7 175-125-4 I200-850-4 200-155-l I-u10-IlO@ 230-185 1600-1300

Requirements

Yield (min)

Tensile (min) MPa

Grade

Property

Iron Casting

Eardnes, ft

Ibf

WC) 269-32 I 269-32 I 302-363 302-363 34 I-444 341-444 388-477 388-477 444-555 444-555

75 100 60 80 45 60 ‘5 35 (b) (b)

(a) Unnotched Charpy bars tested at 72 = 7 “F(22 = 4 “C). The values in the table are a minimum for the average of the highest three test values of four tested samples. (b) Elongation andimpactrequirememsarenotspecitied. Althoughgmdes200-155-l. 1400-I 100-l. 230-185,1600-1300areprimarily used forgearand wearresistanceapplications,grades200I55- I and l40@ I IOO- I have applications where some sacritice in wear resistance is acceptable in order to provide a limited amount of ductility and toughness. (c) Hardness is not mandatory and is shown for information only

Compositions

and General Uses for Standard

Specification

Grade or class

No.

Grades of Ductile lj+al

lJNC

TCb)

Si

MO

Iron

composition, P

S

Description Ferritic;

60-30-18

F32800

3.OOmin

80-60-03

F34100

3.OOmin(c)

ASTM

60-40-18(d)

F32800

65-45-12(d)

F33100

80-55-06(d)

F33800

100-70-03(d)

F34800

120-90-02(d)

F36200

D4Ol8(e)

F32800

D4512(e)

F33100

Ferriticlpearlitic

D5506(e)

F33800

Ferritic/pearlitic

D7003(e)

F3-4800

Pearlitic

DQ&T(ei

F30000

Martensitic

ClassA

F33lOl

SAEJ434

SAEAMS5315C

0.08max

annealed

ASTM A 395; ASME SA395 ASTM A476; SAE AMs5316C A536

250max(b)

%

3.0max

0.08 max

0.05 max

As-cast

Ferritic: may be annealed Mostly ferritic; as-cast or annealed Ferriticlpearlitic: asc3st Mostly pearlitic: may be normalized

3.203.

IO

3.0 mm

1.80-3.00

2.50max(lI

0. IO-I .OO

0.015-O. IO 00050.035

0.08 max

Martensitic: oil quenched and tempered Ferritic

Ferritic:

annealed

General

uses

Pressure-containing parts for use at elevated temperatures Paper mill dryer rolls, at temperatures up to 230°C (4SO “F) Shock-resistant parts: lowtemperature service General service General service Best combination of strength and wear resistance and best response to surface hardening Highest strength and wear resistance hloderately stressed parts requiring good ductility and machinability Moderately stressed parts requiring moderate machinability Highly stressed parts requiring good toughness Highly stressed parts requiring very good wear resistance and good response to selective hardening Highly stressed parts requiring uniformity of microstructure and close control of properties Genera) shipboard service

Note: For mechanical properties and typical applications. see an adjoining table. (a) TC. total carbon, (b) The silicon limit may be increased by 0.08%. up to 2.75 Si. foreach 0.01% reduction in phosphorus content. (c) Carbon equivalent (CE). 3.84.5; CE = TC + 0.3 (Si + P). (d) Composition subordinate to mechanical properties: composition range for any element may be specified by agreement between supplier and purchaser. (e) General composition given under grade D4018 for reference only. Typically. foundries wilt produce to narrowerranges than those shown and will establish different median compositions for different grades. (f) For castings with sections I3 mm (r/z in.) and smaller, may have 2.75 Si max with 0.08 P max. or 3.00 Si max with 0.05 Pmax; for castings with section 50 mm (3 in.) and gteater, CE must not exceed 4.3

828 / Heat Treaters

Mechanical

Specitkation

Guide

Properties

and Typical

Grade or class

No.

Applications

Hardness, EWa)

for Standard

Grades of Ductile

Tensile strength, min(b) hlPa ksi

field strength, min(b) hiPa ksi

Iron Elongation in 50 mm (2 in.) (min), TO(b)

ASTMA39S;AShlESA395

60-40-18

l-13-187

111

60

276

40

I8

ASTM ASThl

80-60-03 60-W IX

201 min

552 41-l

80 60

41-I 176

60 10

3 I8

65-45-12

448

65

310

35

I2

80-55-06 loo-70-03

552 689

80 IO0

379 183

S5 70

6 3

8'7 .ll-t 448 55' -.689 (d) 11-l

I10 60 65 80 IO0 (d) 60

621 276 3I0 379 483 (d) 310

90 40 45 55 70 tdt -IS

2 I8 I2 6 3 k-9 15

A-t76tc);SAEAhISS316 AS36

IX-90-02 D4018 D-l512 D5506 D7003 DQ&T Class A

SAE J13-I

SAEAhlS53lSC

170m3x 156-217 187-155 ‘41-302 (CJ l90max

Qpical

applications

Valtesand fittings forsteamandchemicalplant equipment Paper mill dryerrolls Pressure-containing parts such as valw and pump bodies hlachine components subject to shock and f3tigue loads Crankshti, gezux. and rollers High-strenm gears and machine components Pinions, gem, rollers. and slides Steering knuckle5 Disk brake calipers Crankshaf& Gears Rocker arms Electric equipment engine blocks, pumps. housings. gears. valve bodies. clamps, and cl finders

Note: For composltions. descriptions. and uses see an adjoinmg table. la) hlcasurcd at a predetermined locanon on the casting tb] Dctermmed usmg a standard specimen taken from a separately cast test block, as set forth in the applicable specification (cr Range specified by murual agreement between producerand purchaser. (d) Value must becompatible with minimum hardness specified for production castings

Ductile Iron Property

Tensile strength MPa ksi

Grade Is0

Standard

800 70s 600 500 400 370 A 536 (United

60-40-18 6@42-IO 654% I? 70-50-05 80-55-06 80-60-03 loo-70-03 I20-90-02 SAE JC34 (United D4018 D-1512 DS506 D7OO3 DQ&T(c)

of Various

0.2 70 of&et yield strength hlPa ksi

National

and International Impact

Elongation (min) %

Standards energ

hfean(a) J

Indkidual ft. Ibf

J

ft

Ibf

Eardness,

EB

structure

1083 (International)

8002 loo-2 m-3 500-7 400-12 370-17 ASTM

Requirements

II6 I02 a7 73 58 54

480 420 370 320 150 230

70 61 51 46 36 33

2 ‘)

60 60 6.5 70 80 80 IO0 I70

276 290 310 345 379 111 483 621

10 42 4s 50 55 60 70 90

I8 IO I2

60 65 80 IO0 _..

276 310 379 483

10 1s 55 70

I8 I2 6 3

i 7 I2 I7

I3

9:s

;‘I

a.;

Z-18-352 229-302 197-269 I lO-Z-1 I ing figure. A satisfactory structure consists of temper carbon m a matrx of ferrite. Annealing. A two-stage cycle IS required. The fust stage comerts primary carbides to temper carbon: the second converts carbon dissolved in austenite at the fust stage annealing temperature to temper carbon and ferrite. After First stage annealing, castings are cooled as rapidI> as practical to 710 to 760 “C ( I365 to I-KKI “F) in preparation for second stage annealing. Fast cooling requires I to 6 h. depending on the equipment. Castings are then cooled slowly at a rate of approximately 3 to IO “C tS to 20 “F) per h. During cooling. carbon in the austenile is converted to graphite and deposited on particles of temper carbon. The result is a full) fenitic matrix. Hardness can be considered an approslmate indicator that the ferritizing anneal was complete. Hardness of ferritic malleable almost aluays ranges born I IO to I56 HB. and is influenced b> total carbon and silicon contents.

Mechanical

properties

Also of interest are resistance solderahility. Other properties:

to corrosion.

weldability.

brazeability,

and

Tensile properties.

Llsuall~ measured on unmachined test bars. See table for tensile properties. Fatigue limit. That of unnotched specimens is about 50 to 60% of tensile strength. Notch radius generally has little effect on fatigue strength, but fatigue strength drops with increasing notch depth. Modulus of elasticity. This value m tension is approximately 170 GPa 125 x IO6 si). In comparison. the ranges are I SO to 170 GPa (22 x IO6 to 25 x IO 6 PSI): the value in torsion ranges from 65 to 75 GPa (9.5 x IO6 to I I x IO6 psi). Fracture toughness. Notch tests such as the Charpy V-notch are conducted over a range of temperatures to establish toughness behavior and the temperature range of transition from ductile to brittle fraction. Brittle fractures are most likely to occur at high strain rates, at low temperatures, and with high restraint on metal deformation. Elevated temperature properties. Short term, high temperature tensile properties typicall) show no sign of change to 370 “C (700 “F). Corrosion resistance. This propertq in ferritic malleahle is improved by the addition of copper (usually about I %,j in certam applicalions. Welding and brazing. Welding of ferritic iron almost always produces brittle white iron in the weld zone and the heat-affected zone immediately adjacent to the Held zone. In some cases. welding with a cast iron electrode ma) produce a brittle. gray iron weld zone. accompanying

Welding usuaUy is not recommended unless castings are subsequently annealed to convert carbide to temper carbon and ferrite. However, ferritic can be fusion nelded 10 steel u ithout a requirement for subsequem annealing if a completely decarburized zone as deep as the normal heat affected zone is produced at the faying surface of the malleable iron part before welding. Ferritic iron can be silver brazed and silver-tin soldered.

The most important properties for design purposes are tensile strength. yield strength, modulus of elasticity, faligue strength, tmpact strength. fatigue Loughness. and elevated temperature properties.

Heat

Treating

Pearlitic

and Martensitic

Both grades can be produced to a wide range of mechanical properties, depending on heat treatment. alloying, and melting practice. Lower strength pearlitics often are produced b> air cooling castings after the fist stage anneal; while the higher strength pearlitic/martensitic grades are made by liquid quenching after Ihe fiist stage anneal. With suitable heat treating facilities. air cooling or liquid quenching after the first stage anneal generallq is the most economical ual of making pearlitic or martenstticlpearlitic irons. The alternative is to reheat ferritic produced in two-stage annealing to the austenitic temperature. then quenching. Also. lower strength pearlitics can be made by alloying and a two-stage annealing process.

Heat Treatment

of Pearlitic

Malleable

The fiust stage anneal is the same as that for ferritic iron. After this. the process is different. Some foundries slow cool castings to approsimately 870 “C (I600 “F). During cooling, combined carbon is reduced to approximatelq 0.75%. Castings are then air cooled. Air cooling is accelerated b> an air blast to alold the formation of ferrite emelopes around temper

Malleable

Iron

carbon particles and to produce a tine pearlitic matrix. Castings are then tempered to specifications, or they are reheated to reaustenitize at approximat+ 870 “C (1600 “F), oil quenched. and tempered to specifications. Large foundries usually skip the reaustcnitizing step, and quench castings in oil dircctlq from the fust-stage annealing furnace after stabilizing the temperature at 845 to 870 jC ( I555 to I600 “F).

Heat Treating Pearlitic-Martensitic

Irons

These high strength grades usually are produced by liquid quenching and tempenng. The most economical procedure is to direct quench after first stage annealing. Castings are cooled in the furnace to the quenching temperature of 8-E to 870 “C ( IS.55 to I600 “F) and held I5 to 30 min to homogemze the matns. Castings are then quenched in agitated oil to develop a matrix mtcrostructure of martensite, having a hardness of 415 to 601 HB. Finally, castings are tempered at an appropriate temperature betkieen 590 to 725 jC ( IO95 to I335 jF) to develop specific mechanical properties. Rehardened and tempered malleable iron can also be produced from fully annealed ferritic iron \\ith a slight v,ariation in the heat treatment used for

Heat Treating

arrested-annealed (air quenched) malleable. The matrix of full) annealed ferritic is essentially carbon free. but the iron can be recarbunzed by heating at 840 to 870 “C (IS-15 to 1600 “F) for I h. Tempering times of 2 h or more after air cooling or liquid quenching are needed for uniformity. Control of final hardness is precise. Processing limitations are about the same as those for the heat treatment of medium or high carbon steels. especially when specifications call for hardnesses of 241 to 321 HB. Control limits of kO.2 mm Brinnel diameter can be mamtained with ease. Mechanical properties of pearlitic and martensitic iron vary in a suhstantially linear relationship with brittle hardness. In the ION hardness range. properties of air quenched and tempered pearlitic are essentially the same as those of oil quenched and tempered martensitic malleable iron. At high hardnesses. oil quenched and tempered malleable has a higher yield strength and more elongation than air quenched and tempered malleable iron. Oil quenched and tempered pearlitic is produced commercially to hardnesses as high as 321 HB. while the maximum hardness of high production. air quenched and tempered pearlitic malleable is approximately 255 HB. Tensile properties ofpearlitic normally are measured on machined test bars. Compressive strength is seldom detemrined. because failure in compression is rare. Shear and torsional strength. Shear strength of ferritic malleable is approximately 805, of tensile strength; for pearlitic. it ranges 70 to 9Oq of tensile. Ultimate torsional strength of ferritic malleable is approsimately 90c? of ultimate tensile strength. Yield strength in torsion is 75 to gOP( of ulttmnte tensile strength. Torsional strengths of pearlitic grades are ahout equal to or slightly less than the tensile strength of the material. Yield strengths in torsion vary from 70 to 75% of tensile yield strength. Modulus ofelasticity of pearlitic in tension is I76 to 193 GPa (25.5 x IO6 to 28.0 X IO” psi). Properties at elevated temperatures: generally room temperature tensile strengths are related to hardness. while tensiles above approxtmately 450 “C (840 “F) exhibit asymptottc behavior. Unnotched fatigue limits of tempered pearlitic malleable (air cooled or oil quenched) are approximately 30 to 50% of tensile strength. Tempered martensitic malleable irons (oil quenched) have an unnotched fatigue limit of approximately 35 to 45% of tensile strength. Wear resistance: hoth pearlitic and martrnsitic grades have excellent wear resistance.

Iron Casting

and P/M Steels / 837

Welding: both are difticult to weld hecause temperatures generated in the process can cause the formation of a brittle layer of graphite-free hhite iron. Ho\sever. both types of iron can be welded if the surface to welded has ken heavily decarburized. Brazing: malleable iron can be brazed u ith various commercial processes. Damping capacity: malleable irons perform well in long term service where parts are highly stressed. Reason: hecause of a combination of good damping capacity and fatigue strength.

Bainitic

Heat Treatment

of Pearlitic

Malleable

Both upper and lower bainite can he formed in pearlitic with a marked increase in tensile strength and hnrdness-but there is a loss in ductility. A pearlitic with a composition of 2.6 C. I.1 Si. 0.5 Mn. 0.11 S. for esample. was treated in this manner: it was annealed at 930 “C (1705 “F) for I6 h. air quenched. and tempered at 680 “C ( I255 “F) for 4 h. Properties developed uere: an ultimate tensile strength of 650 MPa (94.2 ksi). a yield strength of -I60 hlPn (66.5 ksi). and a 3.4% elongation at 900 T (,I650 “F). The same non austenitized at 900 “C (1650 “F) in molten salt for I h. quenched in molten salt at 295 “C 1565 “F) for 3 h. and air cooled developed an ultimate strength of 995 hlPa ( l-l-t.2 ksi) and an elongation of IQ at 388 HB. Selective Surface Hardening. Pearlitic is surface hardened by inductton heating and quenching. or by flame heating and quenching to develop high hardness in the heat affected area. In general, little difficulty is encountered in obtaining hardncsses in the range of 55 to 60 HRC. Depth of penetration is controlled by the rate of heating and surface temperature of the \vorkpicce hta~irnum hardness in the matrix of a properly hardened pearlitic casting is 67 HRC. Generally. a casting with this hardness has an average hardness of approximately 62 HRC. as measured by a standard Rockwell tester.

REFERENCES I. Article on malleable iron. Vol I. ASAI Handbook 2. L.R. Jenkins. Heat Treating of hlalleable Iron, Vol 4. ASM Hatldbook

838 / Heat Treaters

Guide

Microstructure. Structure of as-cast malleable white iron showing a mixture of pearlite and eutectic carbides. 400x

Properties

of Malleable

Microstructure. Structure of annealed showing temper carbon in ferrite. 100x

ferritic malleable

Iron Castings Classor

Specillcatioo No.

grsde

Tensile strength MPa ksi

Yield strength MPa k.si

Eardness, Et3

Ferritic ASTMA47andA338.ANSIG48.I. ASTM

FEDQQ-1-666~

32510 3SO18

3-u 365 276

SO 53 40

221 241 207

32 3s 30

lS6max lS6max 15611~

40010 -IS008 45006 soQos 60004 70003 80002 90001

414 418 4-l-18 483 552 586 655 724

60 65 65 70 80 85 9s 10s

276 310 310 3-1s 41-l -183 551 621

40 -IS 45 so 60 70 80 90

149-197 156-197 I%-207 179-229 197-24 I 217-269 24 I-285 269.32 I

34s 448 517 517 621 724

so 65 7s 7s 90 10s

22-l

32 35 so 55 70 85

156max 163-217 187-241 187-24 I 229-269 269-302

A 197

Pearlitic

and martensitic

ASTMA220.ANSIG488.2.

MlL-I-IIWB

Automotive ASTMA602.SAEJlS8

(a) Minimum

iron

in SO mm (2 in.). (b) Annealed.

M32lO(h) MWM(c) MSOO3k) MSS03td) M7002(dj MSSOl(d)

(c) Air quenched and tempered. (d) Liquid quenched and tempered

310 34s 379 483 586

Elongation(a), %

Heat Treating

Grades of Malleable SpeciBed

Grade

Iron Specified

hardness,

According

EB

to Hardness

Beat treatment Annealed

Ferritic

M 4503 M 5003

163-2 I7 187-241

Air quenched and tempered Air quenched and tempered

Ferrite and tempered pea&e(a) Ferrite and tempered pearlite(aj

M 5503 M 7002 M 8501

187-24 I 229-269 269-302

Liquid quenched and tempered Liquid quenched and tempered Liquid quenched and tempered

Tempered martensire Tempered martensile Tempered manensite

applications

For Ion-stress parts requiring good machinability: steering-gear housings, carriers. and mounting brackets Compressor crankshafts and hubs For selective hardening: planet carriers. transmission gears, and differential cases For machinability and improved response to induction hardening For high-snmgth parts: connecting rods and universal-joint yokes For high strength plus good wear resistance: certain gears

for some applications

Iron Specified

According

No.

to Minimum

grade(a)

ASIll metric equivalent class(b)

32510 35018

22010 24018

Class or Specification

l)pical

Microstructure

156max

Grades of Malleable

and P/M Steels / 839

per ASTM A 602 and SAE J158

M 3210

(a) May be all tempered martensite

Iron Casting

Tensile Properties Microstructure

l)pical

applications

Ferritic A47(c),

ASTM

A 338

(d)

Temper carbon and ferrite

ASTM

A 197, ANSI G49. I

(e)

Free of primary graphite

Pearlitic ASTM

ANSIG48.1.

FEDQQ-I-666c

Temper carbon and fenite

ASTM

General engineering service at normal and elevated temperatures for good machinability and excellent shock resistance Flanges, pipe finings. and valve parts for railroad, marine. and other heavy-duty service to 345 “C (650°F) pipe fittings and valve parts for pressure service

and marteositic A220(c),ANSlG48.2,

MU/l-

I I444B

JOOIO 45008 4sOO6 sxKn 60004 70003 8ooO2 90001

280MlO 3lOM8 3lOM6 34OMS 4lOM4 480M3 56OM2 620M I

Temper carbon in necessary matrix without primary cementite or graphite

General engineering service at normal and elevated temperatures. Dimensional tolerance range for castings is stipulated

(a) The 61% three digits of the grade designation indicate the minimum yield strength (xl00 psi). and the last two digits indicate minimum elongation designatedbyfootnote(c)provideametricequivalentclass wherethefustlhreedigitsindcateminimumyieldstrengthinMPa.(c)Specificationswilhasuffix”M”utilizethemetric equivalent class designation. (d) Zinc-coated malleable iron specified per ASTM A 47. (e) Cupola ferritic malleable won

(Q). (b) ASTM

specifications

Short-term elevated-temperature tensile strengths of (a) partially spheroidized pearlitic malleable irons produced by air cooling after the temper cation anneal, (b) finely spheroidized pearlitic malleable irons produced by oil quenching after the temper carbon anneal, and (c) oil-quenched and tempered martensitic malleable irons. The two martensitic malleable irons with hardnesses of 228 HB were reheated (reaustenitized) after the temper carbon anneal [18 h soak at 950 “C (1740 “F)] and then oil quenched. The 263 HB iron was oil quenched from 840 “C (1545 “F) after an anneal of 9.5 h at 950 “C (1740 “F). After oil quenching, all three martensitic irons were tempered

840 / Heat Treaters

Microstructures.

Guide

Structure of air-cooled peatiitic malleable

iron. (a) Slowly air cooled. 400x. (b) Cooled in an air blast. 400x

Hardness vs depth for surface-hardened pearlitic malleable irons. Curves labeled “Matrix” show hardness of the matrix, converted from microhardness tests. 0, oil quenched and tempered to 207 HB before surface hardening; A, air cooled and tempered to 207 HB before surface hardening

Heat Treating

Microstructures. Structure of oil-quenched (d) 229 HB. 500x

Iron Casting

and P/M Steels

/ 841

and tempered martensitic malleable iron. (a) 163 HB. 500x. (b) 179 HB. 500x. (c) 207 HB. 500x

842 / Heat Treaters

Guide

Effects of austenitizing temperature and quenching medium on hardness of as-quenched malleable iron. The listed composition limits for ferritic and peatiitic malleable iron are general limits given in the iron Castings Handbook 1981. In practice, manganese content is 0.2 to 0.45% Mn for the ferritic class and less than 0.6% Mn for the pearlitic class

Influence of time and tempering temperature on room-temperature C, 1.45to 1.55%Si,0.03%P,0.06to0.15%S,0.38to0.50%Mn,andlessthan0.003%Cr

hardness of pearlitic malleable iron. Composition:

2.35 to 2.45%

Heat Treating

Iron Casting

and P/M Steels / 843

Effect of tempering temperature and time on the hardness of ferritic and pearlitic malleable irons in the as-received and reheatedand-quenched conditions

compmltka. Iron

I 2

M&&l

Standard (ferritic) grade 32510 Pearlitic malleable iron. grade 45007

iron.

%

Hadme=.

Atbying and prior haI treabnenf

HI

0.30

Unalloyed;

fully malleablized

I16

0.072

0.30

156

1.80

0.072

0.30

2.40

I.80

0.072

0.30

Unalloyed: air quenched from 925 ‘C (I 700 ‘F). tempered 8 h at 695 “C (1280°F) Unalloyed; oil quenched from 870 T (1600 “F). tempered 3 h at 650 T (1200 “F) Unalloyed; oil quenched from 870 “C (1600 “F). not tempered Alloyed (Mn): air quenched from 940 “C ( I720 “F). tempered 34 h at 715 “C (I320 “F) Alloyed (Mn and MO); air quenched from 940 “C (I720 “F), tempered I2 h at 620 “C (I I50 “F) Alloyed (Mn): air quenched from 925 T f 1700 “F). not tempered Alloyed (Mn); air quenched from 925 “C (I700 ‘F). not tempered Alloyed (Mn); oil quenched from 830 “C (I525 “F). not tempered Alloyed (Mn): oil quenched from 830 “C (I525 “FL not tempered Alloyed (Mn and MO); air quenched from 940 “C (I720 “F), nor tempered

TC

SI

S

Ma

2.40

1.80

0.072

2.40

1.80

2.40

3

Pearlitic malleable grade 60003

4

Oilquenched iron

5

Pearlitic malleable grade 450 IO

iron.

2.40

I.80

0.076

0.90

6

Pearlitic malleable grade 80002

iron.

2.40

1.80

0.072

0.90

7

Air-quenched alloyed malleable Iron

2.40

I.80

0.079

0.90

8

Air-quenched alloyed malleable iron

2.40

1.80

0.076

I.10

9

Oilquenched alloyed malleable iron

2.40

1.80

0.079

0.90

IO

Oilquenched alloyed malleable iron

2.40

I.80

0.076

I.10

II

Air-quenched alloyed malleable iron

2.40

1.80

0.072

0.90

malleable

MO

0.45

0.45

212

444

192

262

285

321

514

578

514

Heat Treating Chemical

P/M Tool Steels

Compositions

Commercial compositions of high speed 1001 steels. cold work die steels. and hot work die steels are presented in an accompanying table.

Characteristics Povvder metallurgy versions of high speed steel tools have significantly beuer toughness and grindability than their conventionally produced counterpts. Highly resulfurized grades offer improved machinability. Other grades difficult to produce convemionally are readily made Lviith the P/M process.

Heat Treating

P/M Tool Steels

Proper heat uealment of tool steels is essential for developing their properties. This is especially true of high-speed and high-alloy materials. Improper heat treatment of these sleels can result in a tool with greatly reduced properties or even one that is unusable. Ponder mernllurgy tool steels utilize the same basic heat treatments as their conventional counterparts. but they tend to respond more rapidly and with better predictability IO heat treatment because of their more unifomr nucrosu-ucture and finer carbide size. The basic heat treatments used include preheating, austenitizing. quenching, and tempering. Honever. optimum heal-treating temperatures may vary somewhat. even if chermcal compositions are identical. The following procedures are specific to ASP high-speed tool steels. bur are generally applicable LOall P/h4 high-speed tool steels. Deviations from these practices may be needed for some specific alloys and applications; in such cases, the recommendations by the manufacturer should he followed. The basic heat ueatment steps are: l

l

l

l

Heat to 850 to 900 “C ( IS60 IO 1650 “F). Slow cool to 700 “C (1290 “F) 31 IO “C (30 “F) per h. Typical annealed hardness values for ASP 33 are approximately 26 HRC max. 33 HRC for ASP 30. and 36 HRC for ASP 60 Stress relielittg (before hardtwitrg): Hold for approximately 3 h at 600 IO 700 “C (I I IO to 1290 “Fj. Slow cool to 500 “C (930 “F) in furnace Hardening: Preheat in IUO steps. fusl at 150 to 500 “C (840 to 930 “F) and then at 850 to 900 “C (IS60 to 1650 “FL Austenitize at 1050 IO II 80 “C (1930 10 ?I55 “F) and quench, preferahly in neutral sah baths. Cool to hand warmth 7ktnpering: Raise temperature to 560 “C ( 1040 “F) or higher. Repeat IWO or three times for at least I h at full temperature. Cool to room temperature between tempers

Annealing:

Sull other grades (superhigh speed steels such as CPM Rex 2Oj are available only as P/M grades. A distinguishing feature of PA1 tool steels IS the uniform distribution and small size of primary carbides. The same is uur of sulfide inclusions in resulfurized grades. hlicrostructures of P/M and conventionally produced high speed steel are compared in an accompanying figure.

The hardnesses of three Plhl high-speed tool steels after hardening and tempering are shot+ n in an adjoining Figure. Three types of distortion are experienced metallurgically during heat treatment: l l

l

Normal volume change due to phase transfomrations in the steel Variations in volume change in different parts of the tool due to the segregation in the steel Distortion due to residual stress caused hy machining or nonuniform heatmg and cooling durmg heal ueatment

Powder metallurgy grades. hovtcver. differ significantly from conventionally manufactured high-speed tool steels. Dimensional changes are more uniform in all directions. Because P/h1 high-speed tool steels are scgregauon free. variations in dimenslonal change are smaller. Therefore, Ihe dimensional change that occurs during hardening can be predicted more accurately. Conventionally processed high-speed tool steels go out-ofround in a four-cornered pattern. The extent of dislortion during heat treatment depends on the type and degree of segregalion. In P/M highspeed tool steels. anisotropy is smaller. and out-of-roundness occurs in a close. circular pattern.

REFERENCE I. K.E. Pinnou.

IV. Stusko. Phi

Tool Steels. Vol I. r\SM Handbook

Heat Treating

Commercial Trade

Iron Casting

and P/M Steels / 845

P/M Tool Steel Compositions AW designation

name

Constituent C

Cr

1.28 1.28 2.30 1.00 1.30 I .3s I .SS I .OO I.10 1.30 I.30 1.30 1.80 I .ss l.SS I.50 I.50 I.35 I .30 I.SO 1.00 2.00 0.95

4.20 4.20 -t.w -I. I s 1.00 l.3 -1.15 4.15 3.7s -lm -1.00 3.7s -1.00 -1.00 4.00 3.7s 3.7s 5.0 1.0 -1.0 -1.0 4.0 4.0

H

elements,

hlo

\

5.00 500 7.00 5.00 SO0 1.50 4.50 S.00 9 so 5.00 5.00 IO.SO 6 SO

5.3 5 ‘5 6.0 5.0 6.0 4.0 IO.0 6.0

3.10 3.10 6.SO 200 3.00 J.00 -I.00 2.00 1.1s 3.00 3.00 2.00 5.00 5.00 s.00 1.10 3 IO 3.8 3.0 1.0 70 -l.S 3.5

1.30 1.30 0.50 I so

9.00 9.7s 5 7s 1.00

I .3O 0.40 0.40

I .Oj 2.10 1.00

%

Eardoess,

co

s

Other

EIRC

High-speed tool steels(a) ASP23 ASP30 ASP60 CPhl Rex MlHCHS CPhl Rex M3HCHS CPhl Rex hl4 CPM Rex M-IHS CPhl Rex h13SHCHS CPhl Rex hl-12 CPM Rex 1.5 CPhl Rex 4SHS CPhl Rex 20 CPM Rek 25 CPhl RexTlS CPhl ReaTlSHS CPhl Rex 76 CPM Rex 76HS HAP IO HAP40 HAPS0 HAP60 HAP70 KHA 33N Cold-work

h13

hl’ 1113 h1-l hl4 h13S hll2

M62 h16 I TIS TIS 11148 hl-18

CPhl I OV CPhl4-W’ vmaclis -l Hot-work

65-67 66-68 67-69 fs4-66 65-67 6-l-66 64-66 65-67 66-68 66-68 66-68 66-68 67-69 65-67 65-67 67-69 67-69 6-t-66

8.5 IO.50

s.0 8.0 8.3 8 2S

so 5.0 9.00 9.00

0.27 0.17 0.06 0.22 0.27 ai3 0.22

0.06 0.22 0.06 0.2’

8.0 8.0 12.0 12.0 0.6ON

65-66

tool steels

CPhl9V

CPhlHI3 CPhl HI9 CPhl H19V

6.10 6.40 6.50 6.10 6.25 5 7s 5.75 6.00 I SO 6.25 6.25 6 25 1250 12.25 12.15 100 IO 0 3.0 6.0 X.0 10.0 12.0 6.0

All

I.78 2.45 2.15 150

5.25 5.25 17.90 8.00

0-m 0.40 0.80

5.00 4.3 4.25

0.03 0.07

53-5s 60-62 57.59 59-63

tool steels HI3 HI9

4.25 1.25

4.2s 4 2s

12-48 W-52 44.56

(a) HCHS. high carbon. high sulfur: HS. high wlfur

Microstructures. Microstructures of high-speed tool steels. Left: CPM T15. Right: Conventional T15. Carbide segregation and its detrimental effects are eliminated with the CPM process, regardless of the size of the products. Source: Crucible Materials Corporation

848 / Heat Treaters

Austenitizing

Temperatures

58 60 62 6-l 66

of ASP 23 Steel

Temperature

Eardness, ~Cb)

Guide

T

loo0 1050 1100 II40

1180

OF 1830 I925 2010 2085 2155

Salt bath(b) min/mm min/ii.

0.59 017 0.39 0.31 0.24

15 13 IO 8 6

Hardness of ASP steels after hardening and tempering a 25 mm (1 in.) diam specimen three times for 1 h. (a) ASP 23. (b)

Other furnace, min(c)

ASP 30. (c) ASP 60, cooled in salt bath. Hardening temperatures for the curves are: A, 1180 “C (2155 “F); 6,115O “C (2100 OF); C, 1100”C(2010”F);D,1050”C(1920”F)

30 25 20 IS IO

(a) After triple temper at 560 “C ( 1040 “F): hardness values may vary by f I ?I. (b) Total immersion time after preheating. (c) Holding time in minutes after tool has reached ti~ll temperature

Out-of-roundness measurements on test disks after hardening and tempering. Test disks machined from 102 mm (4 in.) diam bars. (a) AISI M2. (b) ASP 30

L

Heat Treating

Relative wear resistance, red (hot) hardness, and toughness of CPM and conventional terials Corporation

Iron Casting

high-speed

and P/M Steels / 847

tool steels. Source: Crucible Ma-

Heat Treating Chemical

P/M Stainless

Compositions

Properties and compositions of compacting ders are shown in a accompanymg table.

Characteristics

grade. stainless steel PO\+-

of P/M Stainless

Compositions are held to tighter tolerances than those for AlSl grade wrought stainless steels. Low carbon and high nickel content in austenitic grades of powder contribute to good compressibility. Austenitics are the most widely used grades. accounting for about one-third of total usage. Alloyed powders are characterized b) their irregular shape (see Figure). In comparison with low alloy. ferrous powders, stainless steel powders require higher compacting pressures in par&making, and their strength before sintering (green strength) is lower-about half that of P/M iron.

Sintering

of Stainless

Process

Green compacts usually are presintered in air or nitrogen at 425 to 540 “C (7% to 1000 “F) to volatilize and bum off pressing lubricant. If temperatures are higher. a protective atmosphere is required. Lubricant must be removed. because it can cause carburization of the alloy in sintering; carburization reduces the machinability and corrosion resistance of austenitic alloys. Martensitic alloys that contain carbon must be presintered in rutrogen.

Sintering

In commercial practice. compacting pressures range from 550 to 830 MPa (-10 to 60 tsi). Lubricants used In compactmg powders. such as steak acid, Increase green strength to some extent. and generally lower the compactability of powders. Powders are formed into parts (also called preforms at this stage) in dies. Carbide dies are used because highI> alloyed powders are inherently harder than pure metals such as iron or copper.

Powders

This is the most critical step in processing. Dunng smtenng, lubricants must be removed from parts and powder particles must be bonded together. to give parts the density and associated mechanical properties required in a given application. Average sintering temperatures range from I I20 to I IS0 “C (2050 to 2 100 “F). Temperatures are increased up to I3 IS “C (2100 “F) and higher when improvements m mechanical properties and corrosion resistance are needed. Equipment: up to operating temperatures of approximately I IS0 “C (2100 “F) continuous. mesh belt furnaces do the job. At higher temperatures, manual. automatic pusher, walking beam, or vacuum furnaces are used. Atmospheres used are dissociated ammonia, nitrogen-based atmospheres. and hydrogen. Vacuum furnaces are an alternative

Sintering

Steel

atmospheres

Dissociated ammonia is the most N idely used. A dew point of -IS to -SO “C (-SO to -60 “F) is required to prevent oxidation. However, dissociated ammonia is getting competition from nitrogenbased atmospheres that contain as little as 34 hydrogen. because of the rising price of dissociated ammonia. which contains 7ScC hydrogen. Hydrogen is seldom used commercially because of its high cost.

Use of vacuum is the principal alternative to both dissociated ammonia and mtrogen-based atmospheres. The process is described as partial pressure smtering. Conventional. cold wall vacuum furnaces are used. In vacuum furnace practice. chromium evaporates if furnace pressure falls below the elemental Lapor pressure. and resistance to corrosion is sipnificantlj reduced. Chromium content can be virtually depleted in a typical vacuum sinterinp cycle if the \ncuum lets1 is not properly controlled. Control is provided by backfilling the furnace with a sultable gas to a partial pressure abo\ e the vapor pressure of any of the elements in the alloy. A gas pressure of 27 to 67 Pa (200 to SO0 Hg) is t) pical for sintering at I3 IS “C (‘-100 “F). With argon as the backtill gas. mechanical properties are similar to those obtained ithen hydrogen IS used. With nitrogen. sintered properties are similar to those obtained with dissociated ammoma.

Sintering

Cycles

Tensile strength increases n ith sintering temperature and time. but yield strength drops. After surface oxides are reduced in the initial stage of sintering. powder particles bond together by solid state diffusion. A high degree of dimensional change (shrinkage) takes place when sintering IS at higher temperatures. especially in hydrogen. Longersintering times increase all tensile properties and shrinkage as well. Cooling Rates. Reg‘ardless of the sintenng atmosphere, cooling rate has a profound effect on the properties of sintered austenitic stainless. TypIcall) used rates of cooling pro\ ide the best combination of strength and ductility; and N hen dissociated ammonia is used, nitrogen is also present. N’ith extremely slow cooling precipitation occurs preferentially at grain boundaries. The result is a noticeable increase in strength and loss in ductility. even when precipitation is minimal.

Heat Treating

Carbide precipitation is detrimental to machinability. Precipitation at grain boundaries is reduced when cooling rates are normal. The result here is lower strength but higher ductility. Rapid cooling, i.e.. water quenching. suppresses the precipitation of carbides and nitrides, which produces maximum ductility. The cooling rate effect in vacuum sintering is largely controlled by the atmosphere in uhich parts are cooled. With a nitrogenbackfill, properties are similar to those obtained bv sinterine in dissociated ammonia. With argon. properties are similar to those obtained with hjdropen. ,

Iron Casting

Control of Carbon Content. Austenitic than 0.03%, carbon. Maintaining this level carbon pickup. ensures maximum corrosion machinability.

and P/M Steels / 849

grades are made with less after sintering. meaning no resistance. weldability. and

REFERENCE

LI

Effect of Sintering Temperature of Tensile and Yield Strengths g/cm3 and sintered for 30 min in various atmospheres

Effect of Sintering Temperature on Elongation and Dimensional 6.85 g/cm3 and sintered for 30 min in various atmospheres

I. R.W. Stevenson,

and Apparent

Change

Hardness

Plhl Stainless Steel. Vol 7. ASM Handbook

of Type 316L Stainless

During Sintering

Steel. Pressed to 6.85

of Type 316L Stainless

Steel. Pressed to

850 / Heat Treaters

Guide

Influence of Sintering Atmosphere on Mechanical Properties of Type 316L Pressed to 6.85 g/cm3

Microstructure.

Scanning electron micrograph of water-atomized type 304L stainless steel (-100 mesh). Magnification: 150x

Property Llltimarr tensile suengm, MPa (psi) Yield strength. hlPa (psi) Elongation in 25 mm r I in.). 5 Apparent hardness, HRB Note: Compacts

Compositions

and Properties 303L(a)

Chemical analysis, 5% ChKlmiUlll Nickel Molybdenum MaIlgalMX Silicon Carbon Iron

17.5 12.5 0.2 0.7 0.02 rem

of Stainless

Steel Compacting-Grade 304L

18.5 Il..5 0.3 0.8 0.02 rem

316L

Sintered in dissociated ammonia

Sitered in hydrogen

365.-l (53 000) 271.1(39 800) 7.0 67

288.2 (1 I 8001 I83 -I (26 600) IO.9 47

sinrered for 30 min at I I30 “C (2050 “F)

Powders 8mw

4lOL

434L

I65 13.5 2.1 0.2 0.7 0.02 (maxi rem

20.5 30.0 2.5 0.2 I.0 0.02 rem

12.0

17.0

0.5 0.8 0.0’ rem

I.0 0.2 0.8 0.02 rem

Physical properties Apparent density, g/cm3 flow rate. s/50 g Screen analysis,

3.1 ‘6

2.7 30

2.7 30

2.8 30

2.9 28

2.8 29

I 7 I3 24 55

I 12 20 25 42

I II 18 26 44

I Y I-l 27 39

I l-l 20 26 39

I II I7 27 4-l

9%

+lOOmesh -lOO+ 150mesh -lSO+ 200mesh -200 + 32.5 mesh -325 mesh

Note: Type 830 is used for the manufacture of P/M parts where superior corrosion resistance is of primary consideration. Parts made from type 830 rxhihit improved resistance to oxidizing media and sulfuric acid. This grade is not recommended forcondidons involving unstable chlorides. (a) 0.2% sulfur added for machinability. (b) 3.5% copper also present

Compactibility

of Stainless Steel Powders. (a) Type 316L austenitic stainless steel. (b) Type 41 OL martensitic stainless steel

Heat Treating

Tensile Properties of Standard Type 316L Stainless Steel Metal Powder Industries Federation Tensile Bars. Bars sintered in vacuum for 2 h using argon and nitrogen as backfilling gases. A partial pressure of 400 pm mercury was used to prevent vaporization of chromium

Properties

of Sintered

Type 41 OL Stainless

Processingtreatment As sintered and cooled in water-jacketed zone of furnace

Reheated in dissociated ammonia and oil quenched from 950 “C ( 1750 OF)

Reheated in hydrogen and oil quenched from 950 “C ( I750 OF)

(a) Sintered for 30 min at I 120 “C (2050 “F)

Graphite added, 90 8.10 0 0 10 0 0.10 o”.lO 0 0.10 8.10

Iron Casting

and P/M Steels / 851

Dimensional Changes for Qpe 304L Stainless Steel. Dimensional changes were determined on transverse-rupture bars sintered for 45 min in -40 “C (-40 “F) dew point dissociated ammonia and were calculated from die size

Steel Sinteriug atmosphere(a) Dissociated Dissociated Hydrogen Hydrogen Dissociated Dissociated Hydrogen Hydrogen Dissociated Dissociated Hydrogen Hydrogen

ammonia ammonia

ammonia ammonta

ammonia ammonia

Tempering temperature OC

Tensile strength OF

205

400

175 205 2’0 220

350 4xJ 130 430

105 205 2’0 205

2 -I30 -loo

Apparent bardnas, BRB

MPa

ksi

724 683 393 710 627 703 717 752

105 ZT 103 91 102 I04 I09

102 103 68 95 I06 I02 105 I06

731 745 641 800

106 108 II6 93

I04 104 101 95

Heat Treating Chemical

of P/M Steel

compositions

Tables accompanying this text provide compositions and applications of a variety of ferrous P/M materials, typical mechanical properties. and other

Characteristics

practical infomratron such as the green denshy of different and typical mechanical properties of forged P/M alloys.

Depth of hardening depends largely on porosity and alloy content. The latter must be determined precisely, because of its effect on the heat treatmg process. Additions of chromium and molybdenum. for instance. increase hardenability Response to hardening also depends on combined carbon content, not necessarily total carbon, and the amount of carbon that dissolves in the austenite. Sintering time and temperature are also importanr. If too little combined carbon (excessive graphite) IS present. the condition can be compensated for by using higher austenitizinp temperatures to dissobe most or all of the graphite. .4 caveal: loo much cementite can be formed. making parts excessively brittle after heat treatment Problems are encountered in testing for hardness because of the presence of porosity and free graphite. Indemation readings indicate loher than

Recommended

Heat

Treating

actual hardness \aIues. One reason is that free graphite does not indicate hardness u hen measured by the indentation method. Porosity is the primary cause of error. As porosity is reduced. differences between indicated and actual hardness become smaller.

Process

Combined C %

Temperature “C

OF

915 900 885 870 860

I680 I6.50 I63 I tm 1580

Recommended l l

l

practice is to:

Evaluate hardness of heat treated samples with microhardness testing Follou up with a suitable indentation method. such as Rockwell A. to establish an acceptable range of ohserved hardness After doing the ahovc. comentional hardness wsCng may be used as a quality control mol. hm continued monitoring with microhardness tesling is advised

Forging

P/M Steel Parts

Properties are upgraded significantly by reducing porosity u ith forging and repressmp processes. Both are discussed later in this article.

Practices

Generally. PIM compacts are less homogeneous than their rolled or forged counterparts. To get complete ausrenitization. higher temperatures or longer times at temperature are requtred. The follow inp nus~enniring temperatures are recommended:

0.15 0.35 0.15 0.55 0.65

iron powders

of P/M Parts

With some exceptions these materials are treated in much the same manner as theircast or forged counterparts. Exceptions stem primarily from the inherent porosity of P/M parts. Esamples Include:

Austenitizing

Parts

Ties usually run abotn 505% longer than those for treating wrought parts. When alloying elements are present. both temperature and time are slightly higher. A variety of batch and continuous type furnaces are used in austenitizing. Austenitizing atmospheres. In through hardening. parts nomrally are heated in a gaseous amrosphere. such as that provided hy an endothermic generator. Any nitrogen-based atmosphere may he used, as long as its carbon potential is controlled to match the carbon content of the workpiece.

V’acuum atmospheres are also used. Heating in molten sall is not recommended. even when parts have maximum densit\. Parts are difficult to wash after heating in molten salt. and any salts left-in pores cause m~msdia~s corrosion. Quenching austenitized parts. Parts have a greater tendency toward cracking than rhsir wrought counlerparts. Aqueous quenchants are used. but oil is preferred because it provides a less drastic quench. FM oils expedite quenching IO maximum hardness. Aqueous quenchants (uater and brine. waler and caustic, plain water. and polymer quenchants) are used to obtain full hardness in quenching plain carbon steel parts u ith secnons greater than approximately 5 mm (0.2 in.). In using these quenchants. however. parts can crack. and aqueous media can cause corrosion. Parts u ith thicker sections should contain sufficienl amounts of alloying elsmerns. such as nickel. manganese. and/or chrommm.

Tempering

P/M Parts

All austenitired and quenched parts should be tempered immediately after quenching. In tempering. forced air. convection-type furnaces are preferred. Use of sah or molten metal is not recommended. Tempering remperaurres should be at least IS0 “C (300 “F). Higher temperatures may he used. hut loss of some hardness is a tradeoff.

Heat Treating Iron Casting and P/M Steels / 853

Steam Treating Process This process is frequentlq used in conJunctIon wllh Iempering aS a protective atmosphere at temperatures up to approximately S-10 “C ( 1000 “F). Serendipitous henefits are hqproducts: an oxide coating (usually hluish) is developed on surfaces. u hich serves as a finish that improves resistance to wear and corrosion. and improves appearance as bell. Still another benefit is realized: in Ihe treatment. ferrous-ferritic oxide forms in pores and tends to close them. Entrq of contaminants into pores IS minimized or eliminated. and resistance to hydraulic pressures is improved. Little adjuncl equipment is needed to convert a forced air. rempering furnace for steam trealing. Recommended

processing

sequence

for steam treating:

Load depeased parts in a cold or nearly cold furnace in haskels, making sure parts are separated After closing furnace. set it at 370 “C (700 “F) lnlroduce steam at full pressure H hen furnace temperature rcache$ 345 “C (655 “F) Purge furnace chamber u ith steam for IS mm when temperature reaches 370 “C (700 “F) Adjust and maintain furnace pressure at a slightly positive pressure for an additional IS min Heat load to 510 “C ( IO00 “F) and hold I .S h u ith steam on Cool charge to 290 “C (555 “F) Remove parts from furnace after steam IS turned off When parts cool to 390 “C (555 “F) they can be quenched in mineral 011 to improve appearance and resistance to corrosion

Typically. the process. in comparison wilh gas carburizing. is carried out at a lower temperature, i.e., 55 “C (I 30 “F) lower and a shorter time. i.e.. a half hour or more. Nitrogen diffuses into steel surfaces simultaneously with the carbon. Applications. Carhonitriding is widely used in case hardening parts made of ferrous pobders. Sintered densities vary from approximately 6.5 g/cm’ up to approximately 7.9 g/cm3. Parts may be intiltrated with copper prior to carhonilriding. The process is exvemely effective in case hardening and is reasonably effective in ueating parts with 10 densities of 7.3. ,@m3. loner densities. Equipment. Batch-type. shaker hearth, and belt-type continuous fumacss are well-suited to the process.

Process. The processing, cycle, including gas composition, is critical. Ammonia conlent, usually 10%. increases hardenability and affects dimensional stability. often a critical economic consideration in evaluating the feasibility of making parts with Ihe P/M process. Of equal importance are control of temperature and Ihe quenching medium selected. Tempering. Generally. temperatures are higher than those used in tempering similar urought parts. If temperatures above 205 “C (300 “F) are required. parts should he cleaned u ith ultrasonic degreasing. Porescontaining oil can pose a fue hazard. hut at temperatures normally used, oil is removed in the tempering process. Hardness testing. Because cases are very thin. hardness can? he determined \+ith common indenlation methods. File tesling is the primary method for routine evaluation. hlicrohardness is used to detemline actual hardness.

Case Hardening

Nitrocarburizing

A clear case-core relationship can he ohtained only k%hen parts have a density of at least 7.2 g/cm3. VanOUS case hardening methods are used. but success with a given process tends 10 depend on the application. Processes discussed here are gas and pack carhurizmg. carboninidinp. nitrocarhurizing. and gas nitriding.

Salt bath and gaseous fenitic processes are abailable. The former, however. 1s not well suited to the P/M process. The gaseous process is a nitrogen and carbon system. like the carbonitriding process. The difference is that in gaseous nitrocarburizing, temperatures are completely within the ferrilic phase field. Carbonitriding is in the austenitic range. The temperature in nitrocarburizing is typically approxlmately 570 “C ( IO60 “F), which is slightly under thal for carhonitriding. The pnmaq ohjectlre In gaseous nitrocarhurizing is to produce a thin layer of iron carhonitride and nitrides (the white layer, or compound zone), and an under11 ing diffusion zone containing dissolved nitrogen and iron (or allo).) ninides. White layer provides resistance to galling. corrosion, and wear. The diffusion zone significantI> Improves faligue properties of carbon and low alloy P/hi parts. Process. Typically. sealed quench batch furnaces are used. and are of the same design as those for gas carburizing and carhonitriding. Furnace operating temperatures are low enough to maintain workpieces in the ferritic condition. .L\lmosphere composition can vary with the process. For example. in one process equal amounls of ammonia and endothermic gas are used, while in another. the atmosphere conslsls of 3SF ammonia and 65% refined exothcrmlc pas (+&A Type 301). which is nominally 97% nitrogen. and may he enriched b? a hydrocarbon gas such as methane or propane. Time cycles usually range from I to S h. hut cycles of no more than I h usuallv are recommended because deep penetration (into pores) can cause exc&ive embritdzment. Quenching. Optimum rcsuhs are ohlained with oil quenching from the plDCt?SSing temperature. Final word: because cases are extreme11 thin, usage of the process should he confined to fmished parts. No stock is removed after nitrocarburizing.

Carburizing Parts with combined carbon conlent around 0.10 10 0.20% and free of graphite can he carburized by the conventional gas or pack methods. Liquid carhrri:irrg is not recommended-it is difficult to remove salt from pores by washing. Pack c-urhtri:irlg is not economical in large volume production of small parts. and the method is seldom used. Gas rurbrrri:irrg is the more practical. though seldom used. process. Part density and composition are the importan considerations. Porosity in low density parts poses a prohlem: carhurizing gases penetrate pores. and it is nor possible LOget a distinct case. Carbon pene[ration may he so deep that thin sections of parts may be brittle. In addition. conventional gas carhurizinp does not increase hardenahility. meaning that plain carbon steels must he quenched in an aqueous medium. and cracking is possible. especially if carbon penetration is excessive. C~sr deph depends on rime and temperature. Results thal can he expetted with high densin pans are comparable to those in carburizing wrought parts.

Carbonitriding

Process

This process does not present the diffusion problem In carburizing thal is associated with porosity. In carhonitriding at 790 to 815 “C I 1-M 10 1555 . . “F) the problem is avoided. Lower rates ot dlttuslon allow closer control of case depth and adequate buildup of carbon in rhe case. File hard cases with a microhardness equal to 60 HRC and a predominately martensitic structure are consistendy oblained. Typical case depths range from 0.08 10 0.30 mm (0.003 10 0. I? in.). Case depths of copper-infilrrated parts approach those of wrought parts.

Process

Gas Nitriding Applications

of this process are extremely

limiled

for several reasons:

854 / Heat Treaters Guide

Repressing

As in gas carburizing, cycles are long and nitriding gas penetrates deeply into pores. The condition is difficult to control, and often results in excessive embrittlement l Carbon content should be maintained within 0.30 to 0.508 l Alloying elements that form hard, stable nitrides must be present. Both chromium and aluminum promote nitride formation Process. For optimum results, treatment should be initiated by austenitizing. quenching, and tempering parts. Success requires a microstructure of tempered martensite. Next, parts must be finished or thoroughly cleaned to produce the surface required for nitriding. l

Annealing

Repressing l l l

Parts

at room temperature

has a number of advantages:

Density and hardness are increased Mechanical and physical properties are improved Parts are held close to final dimensions-the amount of material deformation is greater than that possible with sizing because forces are greater

Forging

Process

Sintered

P/M Parts

Unsintered, presintered. and sintered parts are forged (or hot formed). The concept: a porous prefoml is densitied by hot forging with a single blow in a heated. totally enclosed die. Virtually no flash is produced. Sintered preforms can be forged directly from the sintering furnace: or stabilized at lower temperatures and forged; or cooled to room temperature. reheated. and forged. Heat treating practices are the same as those for conventionally processed materials similar in composition. Common heat treat treatments include carburizing and quenching and tempering.

This process is used to improve the machinability of forged P/M parts. Otherwise. its application is limited. Generally, forged parts are treated at temperatures appropriate for their combined carbon content, followed by cooling as rapidly as possible to approximately 705 “C ( I300 “F) for I/:! to 2 h. Optimum austenitizing temperatures for annealing plain carbon-iron compacts depend on combined carbon contents as follows: Temperature Combined C. %

T

0.20 0.30

900

OF

88.5 870 860

0.40 0.50

REFERENCES

1650 I625 1600 1580

I. H.E. Boyer. Secondary ASM

Operations

on P/M Parts and Products,

Vol 7,

Handbook

2. L.F. Pease 111. Mechanical Properties of P/M Materials, Vol 7, ASM Handbook: Ferrous Powder Metallurgy Materials, Vol I. ASM Handbook

3. ASM Metals Reference

Book. Third Edition. Edition,

ASM International

Relation of Carbon Content and Percentage Martensite to Rockwell C Hardness

Values of Case Depth Calculated by the Harris Equation 87OT (MoooF) Tie 2 4 8 I2 I6 20 24 30 36

(I), It

mm

itl.

0.6-l

0.025

0.89 I .27 I .55 I .80 2.01 2.18 2.46 2.74

0.035

o.oso 0.061 0.07 I 0.079 0.086 0.097 0. IO8

Case depth(a), after carburiziig 900°C (165OT) mm in. 0.76 I .07 I.52 I.85 2.13 2.39 2.62 2.95 3.20

0.030 0.042 0.060 0.073 0 084 0.09-l 0.103 0.1 I6 0. I26

at: 925°C (17OOT) mm 0.89 1.27 I.80 2.21 2.5-l 2.8-l 3.10 3.48 3.81

in. 0.035

0.050 0.07 I 0.087 0.100 O.ll2 0.122 0.137 0.150

(a) Case depth: mm = 0.635 &(case depth: in. = 0.025 6) for 925 “C (I700 “F); 0.533 \I;(O.O2 I Jr) for 900 “C ( 1650 “F); 0.157 \I;rO.Ol8 &) for 870 “C (1600 OF). For normal carburizing(~turatedaustenite at the steel surface while at temperature)

Heat Treating

Iron Casting

and P/M Steels / 855

Case Depth vs Time for Carbonitriding

P/M Parts

Typical Furnace for Gaseous Nitrocarburizing

Typical

Compositions

hlaterial PA4 iron P/M steel P/M copper iron P/M copper steel

P/M iron-copper PA4 iron-nickel PAI nickel steel P/M iron-nickel P/M nickel steel P/M iron-nickel P/h1 nickel steel P/M infiltrated steel

of Ferrous

hlPIF F-0900 F-OCKIS F-0008 FC-0200 FC-0205 FC-0308 FC-0505 FC-0508 FC-0808 FC- 1000 M-0200 M-0205 FN-0208 FN4400 FN-0405 FN-0408 FN-07cHIl M-0705 FN-0708 FX-1005 FX-1008 FX-2000 FX-2005 FX-2008

P/M Structural Desiguation(a) ASThl

B310,classA B3lO.classB B3lO.classC B 126, Fade I

Materials

SAE m. class I 853. class 2 853. class 3 864, grade I. class 3

B 426. grade 2 864. grade 2. class 3 864. grade 3. CI~LSS 3 B 426. grade 3 B 426. grade 4 864, grade 3. class 3 B 222: B 439. grade 3 862 B 181. grade I. class A B 184. grade I. class B B 484, grade I, class C B 484. grade 2, class A B 384. grade 2. class B B 484, grade 2, class C B 48.1.grade 3. class A B 48-t. grade 3. class B B 481. gnde 3. class C B 303. class A B 303. class B B 303. class C

870 872

C 0.3 tn3x 0.3-0.6 06 I .O 0.3 max 0.3-0.6 0 6- I .O 0.3-0.6 0.6-I .O 0.6-I .O 0.6-0.9 0.3 max 0.3 mar 0.3-0.6 0.6-0.9 0.3 max 0.3-O 6 0 6-0.9 0.3 max 0.3-0.6 0.6-0.9 0.3-0.6 0.6-I .O 0.3 max 0 3-0.6 0.6. I .O

hlPlFcomposition limits and ranges(b), % Ni CU

I .o-3.0 I .o-3.0 I .o-3.0 3.0-5.5 3.0-5.5 3.0-5.5 6.0-8.0 6.0-8.0 6.0-8.0

I s-3.9 1.5-3.9 1.5-3.9 4.0-6.0 4.0-6.0 6.0-I I.0 18.0-22.0 95IO.5 2.5 max 2.5 miix 2.5 max 2.0 max 2.0 max 2.0 max 2.0 max 2.0 mar 2.0 max 8.0-14.9 8.0-14.9 lS.O-25.0 15.0-25.0 IS.O-25.0

Fe 97.7-100 97499.7 97.099. I 93.8-98.5 93.5-98.2 93. I-97.9 91.4-95.7 91 .o-95.4 86.0-93.4 7S.l mm 87.2905 92.2-99.0 91.9-98.7 91.6-98.4 90.2-97.0 89.9-%.7 89.6-%.4 87.7-94.0 87.4-93.7 87. I-93.4 80.5-91.7 80.1-91.4 70.7-85.0 70.4-84.7 70.0-84.4

(a) Designations listed are nearest comparable designations: ranges and limits may vary slightly between comparable designations. (b) MPfF standards require that the total amount of all other elements be less than 2.O‘Z. except that the total amount of other elements must be less than 4.W in infiltrated steels

856 / Heat Treaters Guide Typical Mechanical Properties of Ferrous P/M Materials MPIF Designation F-0000

F-0005

density suffii(a) N P R s T N P R S

F-0008

N P R S

FC-0200

FC-0205

P R s P R S

FC-0208

N P R S

FC-0505

FC-0508

FC-0808 FC-1000 M-0200

FN-020.5

N P R N P R N N R S T R S T

FN-0208

R S T

M-cuoo

FN-0405

R S T R

Condition(b) AS AS AS AS AS AS AS AS HT AS HT AS HT AS HT AS HT AS HT AS AS AS AS AS HT AS HT AS HT AS HT AS HT AS HT AS AS AS AS AS HT AS AS AS AS AS AS AS HT ss HT ss HT AS HT AS HT AS HT AS AS AS AS HT

Tensile strength hCPa ksi

Yield strength MPa ksi

110

75 95 II0 1.50 I80 10s I-10 160 395 195 51s 170

II II I6 2’ 26 IS 20 23 47 28 75 25

205

30

250

36

275 625 I IS I-15 I60 235 260 560 310 655 20s

40 91 I7 21 23 3-1 38 81 45 95 30

280

II

330

18

399 655 20s 290 380 295 395 -180 480

57 95 30 42 55 43 57 70 70

I25 170 205 160 450 215 605 255 725 20s 650 280 880 31.5 IO70 I50 205 30 I80 650

I8 25 30 23 65 31 88 37 10s 30 91 II I28 so IS5 22 30 36 26 9-l

130 165 205 27s 125 170 220 415 295 550 200 290 Z-10 -loo 290 510 395 650 160 205 ‘55 27s 31s 585 -12.5 690 22.5 295 310 380 41s 550 550 690 240 315 455 330 115 180 51s 250 205 I95 260 310 3s 565 315 760 120 925 330 690 450 930 S-1.5 II05 250 340 430 310 770

I6 I9 2-l 30 10 I8 25 32 60 13 80 29 12 35 58 42 7-t 57 94 23 30 37 40 so 85 62 IO0 33 13 45 5s 60 80 80 IO0 35 SO 66 48 62 70 7s 36 30 28 38 45 37 82 so II0 61 13-I 18 100 65 I35 79 160 36 49 58 1s II2

tab For density range.(b) AS. zu sintrred; SS. sintered and sized: HT. heat treated. tprcall) Llnnotshed Chxpy test. (d) Estimated as 38’1 ol’tensile strength (e) X indicates inhltratrd

Elongation in25mm (I in.), 9E 2.0 2.5 5 9 I5 I.0 I.5 2.5 0.5 35 OS 0.5