ESAB welding

Cu Ch Tab Con

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

BASIC WELDING FILLER METAL TECHNOLOGY

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A Correspondence Course

Lesson 5 Welding Filler Metals for Stainless Steels

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

LESSON I THE BASICS OF ARC WELDING !

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

An Introduction to Metals ! Electricity for Welding

Se Ch (Fa Dow

ESAB

ESAB Welding & Cutting Products

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals ©COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Doc (Sl Dow

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Lesson 1 The Basics of Arc Welding

TABLE OF CONTENTS LESSON I THE BASICS OF ARC WELDING

Lesson 2 Common Electric Arc Welding Processes

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

PART A. Section Nr.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

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AN INTRODUCTION TO METALS Section Title

Page

1.1

Source and Manufacturing.............................................................

1

1.1.1

Rimmed Steel ...................................................................................

2

1.1.2

Capped Steel ....................................................................................

2

1.1.3

Killed Steel ........................................................................................

3

1.1.4

Semi-Killed Steel...............................................................................

3

1.1.5

Vacuum Deoxidized Steel .................................................................

3

1.2

Classification of Steels...................................................................

3

1.2.1

Carbon Steel .....................................................................................

3

1.2.2

Low Alloy Steel..................................................................................

3

1.2.3

High Alloy Steel .................................................................................

4

1.3

Specifications .................................................................................

5

1.4

Crystalline Structure of Metals ......................................................

6

1.4.1

Grains and Grain Boundaries ...........................................................

7

1.5

Heat Treatment ................................................................................

8

1.5.1

Preheat .............................................................................................

8

1.5.2

Stress Relieving ................................................................................

9

1.5.3

Hardening .........................................................................................

9

1.5.4

Tempering .........................................................................................

9

1.5.5

Annealing ..........................................................................................

9

1.5.6

Normalizing .......................................................................................

10

1.5.7

Heat Treatment Trade-Off .................................................................

10

1.6

Properties of Metals........................................................................

10

1.6.1

Tensile Strength ................................................................................

10

1.6.2

Yield Strength....................................................................................

11

1.6.3

Ultimate Tensile Strength ..................................................................

11

1.6.4

Percentage of Elongation .................................................................

11

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

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Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

TABLE OF CONTENTS LESSON I - Con't. Section Nr.

Lesson 10 Reliability of Welding Filler Metals

Section Title

Page

1.6.5

Reduction of Area .............................................................................

1.6.6

Charpy Impacts .................................................................................

11

1.6.7

Fatigue Strength ...............................................................................

12

1.6.8

Creep Strength..................................................................................

13

1.6.9

Oxidation Resistance ........................................................................

13

1.6.10

Hardness Test ...................................................................................

13

1.6.11

Coefficient of Expansion ...................................................................

14

1.6.12

Thermal Conductivity ........................................................................

14

11

1.7

Effects of Alloying Elements ..........................................................

14

1.7.1

Carbon ..............................................................................................

14

1.7.2

Sulphur .............................................................................................

14

1.7.3

Manganese .......................................................................................

15

1.7.4

Chromium .........................................................................................

15

1.7.5

Nickel ................................................................................................

15

1.7.6

Molybdenum .....................................................................................

15

1.7.7

Silicon ...............................................................................................

15

1.7.8

Phosphorus.......................................................................................

15

1.7.9

Aluminum ..........................................................................................

15

1.7.10

Copper ..............................................................................................

15

1.7.11

Columbium........................................................................................

16

1.7.12

Tungsten ...........................................................................................

16

1.7.13

Vanadium ..........................................................................................

16

1.7.14

Nitrogen ............................................................................................

16

1.7.15

Alloying Elements summary .............................................................

16

PART B.

ELECTRICITY FOR WELDING

Section Nr.

Lesson 9 Estimating & Comparing Weld Metal Costs

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Section Title

Page

1.8

Electricity for Welding .......................................................................

17

1.8.1

Principles of Electricity ......................................................................

17

1.8.2

Ohm’s Law ........................................................................................

18

1.8.3

Electrical Power ................................................................................

19

1.8.4

Power Generation .............................................................................

20

© COPYRIGHT 1998 THE ESAB GROUP, INC.

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Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Cu Ch Tab Con

TABLE OF CONTENTS LESSON I - Con't. Section Nr.

Section Title

Page

1.8.5

Transformers ....................................................................................

22

1.8.6

Power Requirements ........................................................................

24

1.8.7

Rectifying AC to DC ..........................................................................

25

1.9

Constant Current or Constant Voltage ..............................................

26

1.9.1

Constant Current Characteristics ......................................................

26

1.9.2

Constant Voltage Characteristics ......................................................

26

1.9.3

Types of Welding Power Sources .....................................................

27

1.9.4

Power Source Controls .....................................................................

28

Appendix A

Glossary of Terms .............................................................................

29

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Lesson 5 Welding Filler Metals for Stainless Steels

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

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Lesson 8 Hardsurfacing Electrodes

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(Sl Dow

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON I, PART A

AN INTRODUCTION TO METALS Lesson 2 Common Electric Arc Welding Processes

1.1

SOURCE AND MANUFACTURING

Metals come from natural deposits of ore in the earth’s crust. Most ores are contaminated with impurities that must be removed by mechanical and chemical means. Metal extracted

Lesson 3 Covered Electrodes for Welding Mild Steels

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from the purified ore is known as primary or virgin metal, and metal that comes from scrap is called secondary metal. Most mining of metal bearing ores is done by either open pit or

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underground methods. The two methods of mining employed are known as “selective” in which small veins or beds of high grade ore are worked, and “bulk” in which large quantities

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

of low grade ore are mined to extract a high grade portion. 1.1.0.1

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There are two types of ores, ferrous and nonferrous. The term ferrous comes

from the Latin word “ferrum” meaning iron, and a ferrous metal is one that has a high iron content. Nonferrous metals, such as copper and aluminum, are those that contain little or

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

no iron. There is approximately 20 times the tonnage of iron in the earth’s crust compared to all other nonferrous products combined; therefore, it is the most important and widely used metal. 1.1.0.2

deposit formed at or near the earth’s surface. Some of the chemical processes that occur during steel making are repeated

during the welding operation and an understanding of welding metallurgy can be gained by imagining the welding arc as a miniature steel mill. 1.1.0.4

The largest percentage of commercially produced iron comes from the blast

furnace process. A typical blast furnace is a circular shaft approximately 90 to 100 feet in

Lesson 8 Hardsurfacing Electrodes

height with an internal diameter of approximately 28 feet. The steel shell of the furnace is

The iron blast furnace utilizes the chemical reaction between a solid fuel charge

and the resulting rising column of gas in the furnace. The three different materials used for the charge are ore, flux and coke. The ore consists of iron oxide about four inches in diameter. The flux is limestone that decomposes into calcium oxide and carbon dioxide. The lime reacts with impurities in the ore and floats them to the surface in the form of a slag. Coke, which is primarily carbon, is the ideal fuel for blast furnaces because it

Lesson 10 Reliability of Welding Filler Metals

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lined with a refractory material, usually a hard, dense clay firebrick. 1.1.0.5

Lesson 9 Estimating & Comparing Weld Metal Costs

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next most widely used metal. Commercial aluminum ore, known as bauxite, is a residual

1.1.0.3

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Aluminum, because of its attractive appearance, light weight and strength, is the

produces carbon monoxide gas, the main agent for reducing iron ore into iron metal.

© COPYRIGHT 1999 THE ESAB GROUP, INC.

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Lesson 1 The Basics of Arc Welding

LESSON I, PART A

1.1.0.6

The basic operation of the blast furnace is to reduce iron oxide to iron metal and

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to remove impurities from the metal. Reduced elements pass into the iron and oxidized

Lesson 2 Common Electric Arc Welding Processes

elements dissolve into the slag. The metal that comes from the blast furnace is called pig iron and is used as a starting material for further purification processes. 1.1.0.7

Pig iron contains excessive amounts of elements that must be reduced before

steel can be produced. Different types of furnaces, most notably the open hearth, electric

Lesson 3 Covered Electrodes for Welding Mild Steels

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and basic oxygen, are used to continue this refining process. Each furnace performs the task of removing or reducing elements such as carbon, silicon, phosphorus, sulfur and

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nitrogen by saturating the molten metal with oxygen and slag forming ingredients. The oxygen reduces elements by forming gases that are blown away and the slag attracts

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

impurities as it separates from the molten metal. 1.1.0.8

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Depending upon the type of slag that is used, refining furnaces are classed as

either acid or basic. Large amounts of lime are contained in basic slags and high quantities of silica are present in acid slags. This differential between acid and basic slags is also

Lesson 5 Welding Filler Metals for Stainless Steels

present in welding electrodes for much of the same refining process occurs in the welding operation. 1.1.0.9

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

After passing through the refining furnace, the metal is poured into cast iron ingot

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molds. The ingot produced is a rather large square column of steel. At this point, the metal is saturated with oxygen. To avoid the formation of large gas pockets in the cast metal, a substantial portion of the oxygen must be removed. This process is known as deoxidation, and it is accomplished through additives that tie up the oxygen either through gases or in slag. There are various degrees of oxidation, and the common ingots resulting from each

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

are as follows: 1.1.1

Rimmed Steel - The making of rimmed steels involves the least deoxidation. As

the ingots solidify, a layer of nearly pure iron is formed on the walls and bottom of the mold, and practically all the carbon, phosphorus, and sulfur segregate to the central core. The

Lesson 8 Hardsurfacing Electrodes

oxygen forms carbon monoxide gas and it is trapped in the solidifying metal as blow holes that disappear in the hot rolling process. The chief advantage of rimmed steel is the excellent defect-free surface that can be produced with the aide of the pure iron skin. Most rimmed steels are low carbon steels containing less than .1% carbon.

Lesson 9 Estimating & Comparing Weld Metal Costs

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1.1.2

Capped Steel - Capped steel regulates the amount of oxygen in the molten

metal through the use of a heavy cap that is locked on top of the mold after the metal is allowed to reach a slight level of rimming. Capped steels contain a more uniform core composition than the rimmed steels. Capped steels are, therefore, used in applications

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1999 THE ESAB GROUP, INC.

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Lesson 1 The Basics of Arc Welding

LESSON I, PART A

that require excellent surfaces, a more homogenous composition, and better mechanical

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properties than rimmed steel.

Lesson 2 Common Electric Arc Welding Processes

1.1.3

Killed Steel - Unlike rimmed or capped steel, killed steel is made by completely

removing or tying up the oxygen before the ingot solidifies to prevent the rimming action. This removal is accomplished by adding a ferro-silicon alloy that combines with oxygen to

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form a slag, leaving a dense and homogenous metal.

Lesson 3 Covered Electrodes for Welding Mild Steels

1.1.4

Semi-killed Steel - Semi-killed steel is a compromise between rimmed and killed

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steel. A small amount of deoxidizing agent, generally ferro-silicon or aluminum, is added. The amount is just sufficient to kill any rimming action, leaving some dissolved oxygen.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

1.1.5

Vacuum Deoxidized Steel - The object of vacuum deoxidation is to remove

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oxygen from the molten steel without adding an element that forms nonmetallic inclusions. This is done by increasing the carbon content of the steel and then subjecting the molten metal to vacuum pouring or steam degassing. The carbon reacts with the oxygen to form

Lesson 5 Welding Filler Metals for Stainless Steels

carbon monoxide, and as a result, the carbon and oxygen levels fall within specified limits. Because no deoxidizing elements that form solid oxides are used, the steel produced by this process is quite clean.

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

1.2

CLASSIFICATIONS OF STEEL

The three commonly used classifications for steel are: carbon, low alloy, and high alloy. These are referred to as the “type” of steel. 1.2.1

Carbon Steel - Steel is basically an alloy of iron and carbon, and it attains its

strength and hardness levels primarily through the addition of carbon. Carbon steels are classed into four groups, depending on their carbon levels. Low Carbon Mild Carbon Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Up to 0.15% carbon .15% to 0.29% carbon

Medium Carbon Steels .30% to 0.59% carbon High Carbon Steels 1.2.1.1

.60% to 1.70% carbon

The largest tonnage of steel produced falls into the low and mild carbon steel

groups. They are popular because of their relative strength and ease with which they can be welded. 1.2.2

Lesson 10 Reliability of Welding Filler Metals

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Low Alloy Steel - Low alloy steel, as the name implies, contains small amounts

of alloying elements that produce remarkable improvements in their properties. Alloying

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Lesson 1 The Basics of Arc Welding

LESSON I, PART A

elements are added to improve strength and toughness, to decrease or increase the

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response to heat treatment, and to retard rusting and corrosion. Low alloy steel is gener-

Lesson 2 Common Electric Arc Welding Processes

ally defined as having a 1.5% to 5% total alloy content. Common alloying elements are manganese, silicon, chromium, nickel, molybdenum, and vanadium. Low alloy steels may contain as many as four or five of these alloys in varying amounts. 1.2.2.1

Lesson 3 Covered Electrodes for Welding Mild Steels

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structural steel. Since they have high strength-to-weight ratios, they reduce dead weight in

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railroad cars, truck frames, heavy equipment, etc. 1.2.2.2

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Low alloy steels have higher tensile and yield strengths than mild steel or carbon

Ordinary carbon steels, that exhibit brittleness at low temperatures, are unreliable

in critical applications. Therefore, low alloy steels with nickel additions are often used for

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low temperature situations. 1.2.2.3

Steels lose much of their strength at high temperatures. To provide for this loss

of strength at elevated temperatures, small amounts of chromium or molybdenum are

Lesson 5 Welding Filler Metals for Stainless Steels

added. 1.2.3

High Alloy Steel - This group of expensive and specialized steels contain alloy

levels in excess of 10%, giving them outstanding properties.

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1.2.3.1

give it two exceptional qualities, the ability to harden while undergoing cold work and great toughness. The term austenitic refers to the crystalline structure of these steels. 1.2.3.2

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Austenitic manganese steel contains high carbon and manganese levels, that

Stainless steels are high alloy steels that have the ability to resist corrosion. This

characteristic is mainly due to the high chromium content, i.e., 10% or greater. Nickel is also used in substantial quantities in some stainless steels. 1.2.3.3

Tool steels are used for cutting and forming operations. They are high quality

steels used in making tools, punches, forming dies, extruding dies, forgings and so forth.

Lesson 8 Hardsurfacing Electrodes

Depending upon their properties and usage, they are sometimes referred to as water hardening, shock resisting, oil hardening, air hardening, and hot work tool steel. 1.2.3.4

Lesson 9 Estimating & Comparing Weld Metal Costs

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Because of the high levels of alloying elements, special care and practices are

required when welding high alloy steels.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1999 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

LESSON I, PART A

1.3

SPECIFICATIONS

Many steel producers have developed steels that they market under a trade name such as Cor-Ten, HY-80, T-1, NA-XTRA, or SS-100, but usually a type of steel is referred to by its specification. A variety of technical, governmental and industrial associations issue specifications for the purpose of classifying materials by their chemical composition, properties or usage. The specification agencies most closely related to the steel industry

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

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are the American Iron and Steel Institute (AISI), Society of Automotive Engineers (SAE),

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American Society for Testing and Materials (ASTM), and the American Society of Mechanical Engineers (ASME). 1.3.0.1

The American Iron and Steel Institute (AISI) and the Society of Automobile

Engineers (SAE) have collaborated in providing identical numerical designations for their

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specifications. The first two digits of a four digit index number refer to a series of steels classified by their composition or alloy combination. While the last two digits, which can change within the same series, give an approximate average of the carbon range. For

Lesson 5 Welding Filler Metals for Stainless Steels

example, the first two digits of a type 1010 or 1020 steel indicate a “10” series that has carbon as its main alloy. The last two digits indicate an approximate average content of .10% or .20% carbon, respectively. Likewise, the “41” of a 4130 type steel refers to a group that has chromium and molybdenum as their main alloy combination with approximately

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

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.30% carbon content. 1.3.0.2

The AISI classifications for certain alloys, such as stainless steel, are somewhat

different. They follow a three digit classification with the first digit designating the main alloy composition or series. The last two digits will change within a series, but are of an

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

arbitrary nature being agreed upon by industry as a designation for certain compositions within the series. For example, the “3” in a 300 series of stainless steel indicates chromium and nickel as the main alloys, but a 308 stainless has a different overall composition than a 347 type. The “4” of a 400 series indicates the main alloy as chromium, but there are

Lesson 8 Hardsurfacing Electrodes

different types such as 410, 420, 430, and so forth within the series. 1.3.0.3

The American Society for Testing and Materials (ASTM) is the largest

organization of its kind in the world. It has compiled some 48 volumes of standards for materials, specifications, testing methods and recommended practices for a variety of

Lesson 9 Estimating & Comparing Weld Metal Costs

materials ranging from textiles and plastics to concrete and metals. 1.3.0.4

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Two ASTM designated steels commonly specified for construction are A36-77

and A242-79. The prefix letter indicates the class of a material. In this case, the letter “A” indicates a ferrous metal, the class of widest interest in welding. The numbers 36 and 242

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Lesson 1 The Basics of Arc Welding

LESSON I, PART A are index numbers. The 77 and 79 refer to the year that the standards for these steels

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were originally adopted or the date of their latest revision.

Lesson 2 Common Electric Arc Welding Processes

1.3.0.5

The ASTM designation may be further subdivided into Grades or Classes. Since

many standards for ferrous metals are written to cover forms of steel (i.e., sheet, bar, plate, etc.) or particular products fabricated from steel (i.e., steel rail, pipe, chain, etc.), the user may select from a number of different types of steel under the same classification. The

Lesson 3 Covered Electrodes for Welding Mild Steels

differences in such things as chemistries, properties, heat treatment, etc. An example of a

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full designation is A285-78 Grade A or A485-79 Class 70. 1.3.0.6

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different types are than placed under grades or classes as a way of indicating the

The American Society of Mechanical Engineers (ASME) maintains a widely used

ASME Boiler and Pressure Vessel Code. The material specification as adopted by the

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ASME is identified with a prefix letter “S”, while the remainder is identical with ASTM with the exception that the date of adoption or revision by ASTM is not shown. Therefore, a common example of an ASME classification is SA 387 Grade 11, Class 1.

Lesson 5 Welding Filler Metals for Stainless Steels

1.4

CRYSTALLINE STRUCTURE OF METALS

When a liquid metal is cooled, its atoms will assemble into a regular crystal pattern and we

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

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say the liquid has solidified or crystallized. All metals solidify as a crystalline material. In a crystal the atoms or molecules are held in a fixed position and are not free to move about as are the molecules of a liquid or gas. This fixed position is called a crystal lattice. As the temperature of a crystal is raised, more thermal energy is absorbed by the atoms or molecules and their movement increases. As the distance

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

between the atoms increases, the lattice breaks down and

4000

the crystal melts. If a lattice contains only one type of atom, LIQUID 3000

throughout the lattice, and the crystal melts at a single 2795°F

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

as in pure iron, the conditions are the same at all points temperature (see Figure 1).

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2000

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1000

SOLID TIME SOLID-LIQUID TRANSFORMATION, PURE IRON

Lesson 10 Reliability of Welding Filler Metals

FIGURE 1

© COPYRIGHT 1999 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON I, PART A

1.4.0.1

However, if the lattice contains two

or more types of atoms, as in any alloy-steel,

Lesson 2 Common Electric Arc Welding Processes

Liquid

it may start to melt at one temperature but not Liquid and Solid

be completely molten until it has been heated to a higher temperature (See Figure 2). This creates a situation where there is a

Lesson 3 Covered Electrodes for Welding Mild Steels

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combination of liquids and solids within a range of temperatures.

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Solid

1.4.0.2

Each metal has a characteristic

crystal structure that forms during

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

solidification and often remains the permanent

TIME

form of the material as long as it remains at

Solid-Liquid Transformation, Alloy Metal

room temperature. However, some metals

FIGURE 2

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may undergo an alteration in the crystalline

Lesson 5 Welding Filler Metals for Stainless Steels

form as the temperature is changed. This is known as phase transformation. For example, pure iron solidifies at 2795°F, the delta structure transforms into a structure referred to as gamma iron. Gamma iron is commonly known as austenite and is a nonmagnetic structure. At a temperature of 1670°F., the pure iron structure transforms back to the delta iron form, but at this temperature, the metal is known as alpha iron. These two phases are

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

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given different names to differentiate between the high temperature phase (delta) and the low temperature phase (alpha). The capability of the atoms of a material to transform into two or more crystalline structures at different temperatures is defined as allotropic. Steels and iron are allotropic metals.

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

1.4.1

Grains and Grain Boundaries - As the metal is cooled to its freezing point, a

small group of atoms begin to assemble into crystalline form (refer to Figure 3). These small crystals scattered throughout the body of the liquid are oriented in all directions and as solidification continues, more crystals are formed from the surrounding liquid. Often,

Lesson 8 Hardsurfacing Electrodes

they take the form of dendrites, or a treelike structure. As crystallization continues, the crystals begin to touch one another, their free growth hampered, and the remaining liquid freezes to the adjacent crystals until solidification is complete. The solid is now composed of individual crystals that usually meet at different orientations. Where these crystals meet

Lesson 9 Estimating & Comparing Weld Metal Costs

is called a grain boundary. 1.4.1.2

A number of conditions influence the initial grain size. It is important to know that

cooling rate and temperature has an important influence on the newly solidified grain structure and grain size. To illustrate differences in grain formation, let's look at the cooling

Lesson 10 Reliability of Welding Filler Metals

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phases in a weld.

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LESSON I, PART A

Lesson 1 The Basics of Arc Welding

GRAIN BOUNDARIES

Lesson 2 Common Electric Arc Welding Processes

BASE METAL DENDRITE FORMATION

Lesson 3 Covered Electrodes for Welding Mild Steels

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INITIAL CRYSTAL FORMATION

COMPLETE SOLIDIFICATION

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FIGURE 3

1.4.1.3

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Initial crystal formation begins at the coolest spot in the weld. That spot is at the

point where the molten metal and the unmelted base metal meet. As the metal continues

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

to solidify, you will note that the grains in the center are smaller and finer in texture than the

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grains at the outer boundaries of the weld deposit. This is explained by the fact that as the weld metal cools, the heat from the center of the weld deposit will dissipate into the base metal through the outer grains that solidified first. Consequently, the grains that solidified first were at high temperatures for a longer time while in the solid state and this is a situation that encourages grain growth. Grain size can have an effect on the soundness of the weld. The smaller grains are stronger and more ductile than the larger grains. If a crack occurs, the tendency is for it to start in the area where the grains are largest.

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1.4.1.4

To summarize this section, it should be understood that all metals are composed

of crystals of grains. The shape and characteristics of crystals are determined by the arrangement of their atoms. The atomic pattern of a single element can change its arrangement at different temperatures, and that this atomic pattern or microstructure

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

determines the properties of the metals.

1.5

HEAT TREATMENT

The temperature that metal is heated, the length of time it is held at that temperature, and

Lesson 8 Hardsurfacing Electrodes

the rate that it is cooled, all have an effect on a metal's crystalline structure. This crystalline structure, commonly referred to as "microstructure," determines the specific properties of metals. There are various ways of manipulating the microstructure, either at the steel mill or in the welding procedure. Some of the more common ways are as follows:

Lesson 9 Estimating & Comparing Weld Metal Costs

1.5.1

Preheat - Most metals are rather good conductors of heat. As a result, the heat

in the weld area is rapidly dispersed through the whole weldment to all surfaces where it is radiated to the atmosphere causing comparatively rapid cooling. In some metals, this rapid cooling may contribute to the formation of microstructures in the weld zone that are detri-

Lesson 10 Reliability of Welding Filler Metals

Se Ch (Fa Dow

mental. Preheating the weldment before it is welded is a method of slowing the cooling

© COPYRIGHT 1999 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON I, PART A

rate of the metal. The preheat temperature may vary from 150°F to 1000°F, but more

Cu Ch Tab Con

commonly it is held in the 300°F to 400°F range. The thicker the weld metal, the more

Lesson 2 Common Electric Arc Welding Processes

likely will it be necessary to preheat, because the heat will be conducted away from the weld zone more rapidly as the mass increases. 1.5.2

Stress Relieving - Metals expand when heated and contract when cooled. The

amount of expansion is directly proportional to the amount of heat applied. In a weldment,

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

the metal closest to the weld is subjected to the highest temperature, and as the distance from the weld zone increases, the maximum temperature reached decreases. This nonuni-

P

form heating causes nonuniform expansion and contraction and can cause distortion and internal stresses within the weldment. Depending on its composition and usage, the metal

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

may not be able to resist these stresses and cracking or early failure of the part may occur.

Lesson 5 Welding Filler Metals for Stainless Steels

1.5.3

after it has been welded. The metal is heated to temperatures just below the point where a microstructure change would occur and then it is cooled at a slow rate. Hardening - The hardness of steel may be increased by heating it to 50°F to

100°F above the temperature that a microstructure change occurs, and then placing the metal in a liquid solution that rapidly cools it. This rapid cooling, known as "quenching," locks in place microstructures known as "martensite" that contribute to a metal's hardness

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Glo

One way to minimize these stresses or to relieve them is by uniformly heating the structure

Turn

characteristic. The quenching solutions used in this process are rated according to the speed that they cool the metal, i.e., Oil (fast), Water (faster), Salt Brine (fastest). 1.5.4

Tempering - After a metal is quenches, it is then usually tempered. Tempering is

a process where the metal is reheated to somewhere below 1335°F, held at that tempera-

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

ture for a length of time, and then cooled to room temperature. Tempering reduces the brittleness that is characteristic in hardened steels, thereby producing a good balance between high strength and toughness. The term toughness, as it applies to metals, usually refers to resistance to brittle fracture or notch toughness under certain environmental conditions. More information on these properties will be covered later in this lesson and in

Lesson 8 Hardsurfacing Electrodes

subsequent lessons. Steels that respond to this type of treatment are known as "quenched and tempered steels." 1.5.5

Lesson 9 Estimating & Comparing Weld Metal Costs

Se Ch (Fa Dow

Annealing - A metal that is annealed is heated to a temperature 50°to 100°

above where a microstructure change occurs, held at that temperature for a sufficient time for a uniform change to take place, and then cooled at a very slow rate, usually in a furnace. The principal reason for annealing is to soften steel and create a uniform fine grain structure. Welded parts are seldom annealed for the high temperatures would cause distortion.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1999 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON I, PART A

1.5.6

Normalizing - The main difference between normalizing and annealing is the

Cu Ch Tab Con

method of cooling. Normalized steel is heated to a temperature approximately 100°above

Lesson 2 Common Electric Arc Welding Processes

where the microstructure transforms and then cooled in still air rather than in a furnace. 1.5.7

Heat Treatment Trade-Off - It must be noted that these various ways of control-

ling the heating and cooling of metals can produce a desired property, but sometimes at the

Go T

expense of another desirable property. An example of this trade-off is evident in the fact

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

that certain heat treatments can increase the strength or hardness of metal, but the same treatments will also make the metal less ductile or more brittle, and therefore, susceptible

P

to welding problems.

1.6

PROPERTIES OF METALS

Glo

The usefulness of a particular metal is determined by the climate and conditions in which it will be used. A metal that is stamped into an automobile fender must be softer and more pliable than armor plate that must withstand an explosive force, or the material used for an

Lesson 5 Welding Filler Metals for Stainless Steels

oil rig on the Alaska North Slope must perform in a quite different climate than a steam boiler. It becomes obvious that before a material is recommended for a specific use, the physical and mechanical properties of that metal and the weld metal designed to join it

Turn

must be evaluated. Some of the more important properties of metals and the means of

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

evaluation are as follows: 1.6.1

Tensile Strength - Tensile strength is one of the most important determining

factors in selecting a metal, especially if it is to be a structural member, part of a machine, or part of a pressure vessel. 1.6.1.1

The tensile test is performed as shown in Figure 4. The test specimen is

machined to exact standard dimensions and clamped into the testing apparatus at both ends. The specimen is then RECORDING DIAL

pulled to the point of fracture

Lesson 8 Hardsurfacing Electrodes

TEST SPECIMEN

and the data recorded.

1.6.1.2

Se Doc (Sl Dow

The tensile strength

test gives us 4 primary pieces

Lesson 9 Estimating & Comparing Weld Metal Costs

of information: (1) Yield Strength, (2) Ultimate Tensile

Lesson 10 Reliability of Welding Filler Metals

FORCE

Strength, (3) Elongation, and (4) Reduction in Area.

Se Ch (Fa Dow

TENSILE TESTING APPARATUS

FIGURE 4

© COPYRIGHT 1999 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON I, PART A

1.6.2

Yield Strength - When a metal is placed in tension, it acts somewhat like a

Cu Ch Tab Con

rubberband. When a load of limited magnitude is applied, the metal stretches, and when

Lesson 2 Common Electric Arc Welding Processes

the load is released, the metal returns to its original shape. This is the elastic characteristic of metal and is represented by letter A in Figure 5. As a greater load is applied, the metal will reach a point where it will no longer return to its original shape but will continue to stretch. Yield strength is the point where the metal reaches the limit of its elastic character-

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

istic and will no longer return to its original shape. 1.6.3

Ultimate Tensile Strength - Once a metal has exceeded its yield point, it will

P

continue to stretch or deform, and if the load is suddenly released, the metal will not return to its original shape, but will remain in its elongated form. This is called the plastic region of

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

the metal and is represented by the letter B in Figure 5. As this plastic deformation inagainst further elongation, and Ultimate Strength Reduction of Area

Elongation

Lesson 5 Welding Filler Metals for Stainless Steels

Yield Strength

Fracture

an increased load must be applied to stretch the metal. As the load is increased, the metal will finally reach a point where it

A

B

STRAIN - INCHES

C

NOMINAL STRESS - STRAIN CURVE

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Glo

creases, the metal strains

FIGURE 5

no longer resists and any further load applied will rapidly

Turn

cause the metal to break. That point at which the metal has

withstood or resisted the maximum applied load is its ultimate tensile strength. This information is usually recorded in pounds per square inch (psi).

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

1.6.4

Percentage of Elongation - Before a tensile specimen is placed in the tensile

tester, two marks at a measured distance are placed on the opposing ends of the circular shaft. After the specimen is fractured, the distance between the marks is measured and recorded as a percentage of the original distance. See Figure 5. This is the percentage of

Lesson 8 Hardsurfacing Electrodes

elongation and it gives an indication of the ductility of the metal at room temperature. 1.6.5

Reduction of Area - A tensile specimen is machined to exact dimensions. The

area of its midpoint cross-section is a known figure. As the specimen is loaded to the point

Lesson 9 Estimating & Comparing Weld Metal Costs

of fracture, the area where it breaks is reduced in size. See Figure 5. This reduced area is calculated and recorded as a percentage of the original cross-sectional area. This information reflects the relative ductility or brittleness of the metal. 1.6.6

Se Ch (Fa Dow

Charpy Impacts - Metal that is normally strong and ductile at room temperature

may become very brittle at much lower temperatures, and thus, is susceptible to fracture if

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1999 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON I, PART A a sharp abrupt load is applied to it. An impact tester measures the degree of susceptibility

Cu Ch Tab Con

to what is called brittle fracture.

Lesson 2 Common Electric Arc Welding Processes

1.6.6.1

The impact specimen is machined to exact dimensions (Figure 6) and then

notched on one side. Quite often, the notch is in the form of a "V" and the test in this case is referred to as a Charpy V-Notch Impact Test. The specimen is cooled to a predetermined temperature and then placed in a stationary clamp at the base of the testing

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

machine. The specimen is in the direct path of a weighted hammer attached to a

P

pendulum (Figure 6).

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Glo ENERGY IN FT/LBS

FRACTURES

Lesson 5 Welding Filler Metals for Stainless Steels

CRACKS

DEFORMS

CHARPY V-NOTCH SPECIMEN

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

CHARPY IMPACT TEST MACHINE

CHARPY V-NOTCH IMPACT TEST

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

FIGURE 6

1.6.6.2

The hammer is released from a fixed height and the energy required to fracture

the specimen is recorded in ft-lbs. A specimen that is cooled to -60°F and absorbs 40 ft-lbs of energy is more ductile, and therefore, more suitable for low temperature service than a specimen that withstands only 10 ft-lbs at the same temperature. The specimen that

Lesson 8 Hardsurfacing Electrodes

withstood 40 ft-lbs energy is said to have better toughness or notch toughness.

1.6.7

Fatigue Strength - A metal will withstand a load less than its ultimate tensile

strength but may break if that load is removed and then reapplied several times. For ex-

Lesson 9 Estimating & Comparing Weld Metal Costs

ample, if a thin wire is bent once, but if it is bent back and forth repeatedly, it will eventually fracture and it is said to have exceeded its fatigue strength. A common test for this strength is to place a specimen in a machine that repeatedly applies the same load first in tension and then in compression. The fatigue strength is calculated from the number of cycles the metal withstands before the point of failure is reached.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1999 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON I, PART A

1.6.8

Creep Strength - If a load below a metal's tensile strength is applied at room

Cu Ch Tab Con

temperature (72°F), it will cause some initial elongation, but there will be no further measur-

Lesson 2 Common Electric Arc Welding Processes

able elongation if the load is kept at a constant level. If that same load were applied to a metal heated to a high temperature, the situation would change. Although the load is held at a constant level, the metal will gradually continue to elongate. This characteristic is called creep. Eventually, the material may rupture depending on the temperature of the

Lesson 3 Covered Electrodes for Welding Mild Steels

metal, the degree of load applied and the length of time that it is applied. All three of these

Go T

factors determine a metal's ability to resist creep, and therefore, its creep strength.

P 1.6.9

Oxidation Resistance - The atoms of metal have a tendency to unite with oxy-

gen in the air to form oxide compounds, the most visible being rust and scale. In some

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

metals, these oxides will adhere very tightly to the skin of the metal and effectively seal it

Glo

from further oxidation as is evident in stainless steel. These materials have high oxidation resistance. In other metals, the bond is very loose, creating a situation where the oxides will flake off, and the metal gradually deteriorates as the time of exposure is extended.

Lesson 5 Welding Filler Metals for Stainless Steels

1.6.10

Hardness Test - The resistance of a metal to indentation is a measure of its

hardness and an indication of the materials's strength. To test for hardness, a fixed load forces an indenter into the test material (Figure 7). The depth of the penetration or the size of the impression is measured. The measurement is converted into a hardness number

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Vickers, Knoop and Rockwell. The Rockwell is further divided into different scales, and

HARDNESS TEST

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

SHAPE OF INDENTER

A C D B

} }

Diamond Cone 1/16 in. Diameter Steel Sphere 1/8 in. Diameter Steel Sphere

E

10 mm Sphere of Steel or Tungsten Carbide

BRINNELL

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals

INDENTER DESCRIPTION

ROCKWELL

F G

Lesson 8 Hardsurfacing Electrodes

Turn

through the use of a variety of established tables. The most common tables are the Brinell,

VICKERS

Diamond Pyramid

KNOOP

Diamond Pyramid

Types of Indenters - Hardness Tests FIGURE 7

© COPYRIGHT 1999 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON I, PART A

depending on the material being tested, the shape of the indenter and the load applied, the

Cu Ch Tab Con

conversion tables may differ. For example, a material listed as having a hardness of Rb or

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels

Rc means its hardness has been determined from the Rockwell "B" scale or the Rockwell "C" scale. 1.6.11

Coefficient of Expansion - All metals expand when heated and contract when

cooled. This dimensional change is related to the crystalline structure and will vary with

Go T

different materials. The different expansion and contraction rates are expressed numerically by a coefficient of thermal expansion. When two different metals are heated to the

P

same temperature and cooled at the same rate, the one with the higher numerical coefficient will expand and contract more than the one with the lesser coefficient.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

1.6.12

Thermal Conductivity - Some metals will absorb and transmit heat more readily

Glo

than others. They are categorized as having high thermal conductivity. This characteristic contributes to the fact that some metals will melt or undergo transformations at much lower temperatures than others.

Lesson 5 Welding Filler Metals for Stainless Steels

1.7

EFFECTS OF THE ALLOYING ELEMENTS

Alloying is the process of adding a metal or a nonmetal to pure metals such as copper,

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Turn

aluminum or iron. From the time it was discovered that the properties of pure metals could be improved by adding other elements, alloy steel has increased by popularity. In fact, metals that are welded are rarely in their pure state. The major properties that can be improved by adding small amounts of alloying elements are hardness, tensile strength,

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

ductility and corrosion resistance. Common alloying elements and their effect on the properties of metals are as follows: 1.7.1

Carbon - Carbon is the most effective, most widely used and lowest in cost

alloying element available for increasing the hardness and strength of metal. An alloy

Lesson 8 Hardsurfacing Electrodes

containing up to 1.7% carbon in combination with iron is known as steel, whereas the combination above 1.7% carbon is known as cast iron. Although carbon is a desirable alloying element, high levels of it can cause problems; therefore, special care is required when welding high carbon steels and cast iron.

Lesson 9 Estimating & Comparing Weld Metal Costs

Se Ch (Fa Dow

1.7.2

Sulphur - Sulphur is normally an undesirable element in steel because it causes

brittleness. It may be deliberately added to improve the machinability of the steel. The sulphur causes the machine chips to break rather than form long curls and clog the machine. Normally, every effort is made to reduce the sulphur content to the lowest possible level because it can

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1999 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON I, PART A

create welding difficulties.

Lesson 2 Common Electric Arc Welding Processes

1.7.3

Lesson 3 Covered Electrodes for Welding Mild Steels

1.7.4

Cu Ch Tab Con

Manganese - Manganese in contents up to 1% is usually present in all low alloy

steels as a deoxidizer and desulphurizer. That is to say, it readily combines with oxygen and sulphur to help negate the undesirable effect these elements have when in their natural state. Manganese also increases the tensile strength and hardenability of steel.

Go T Chromium - Chromium, in combination with carbon, is a powerful hardening

alloying element. In addition to its hardening properties, chromium increases corrosion

P

resistance and the strength of steel at high temperatures. Chromium is the primary alloying element in stainless steel.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

1.7.5

Nickel - The greatest single property of steel that is improved by the presence of

Glo

nickel is its ductility or notch toughness. In this respect, it is the most effective of all alloying elements in improving a steel's resistance to impact at low temperatures. Electrodes with high nickel content are used to weld cast iron materials. Nickel is also used in combi-

Lesson 5 Welding Filler Metals for Stainless Steels

nation with chromium to form a group known as austenitic stainless steel. 1.7.6

Molybdenum - Molybdenum strongly increases the depth of the hardening

characteristic of steel. It is quite often used in combination with chromium to improve the strength of the steel at high temperatures. This group of steels is usually referred to as

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Turn

chrome-moly steels. 1.7.7

Silicon - Silicon is usually contained in steel as a deoxidizer. Silicon will add

strength to steel but excessive amounts can reduce the ductility. Additional amounts of

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

silicon are sometimes added to welding electrodes to increase the fluid flow of weld metal. 1.7.8

Phosphorus - Phosphorus is considered a harmful residual element in steel

because it greatly reduces ductility and toughness. Efforts are made to reduce it to its very lowest levels; however, phosphorus is added in very small amounts to some steels to

Lesson 8 Hardsurfacing Electrodes

increase strength. 1.7.9

Aluminum - Aluminum is primarily used as a deoxidizer in steel. It may also be

used in very small amounts to control the size of the grains.

Lesson 9 Estimating & Comparing Weld Metal Costs

1.7.10

Se Ch (Fa Dow

Copper - Copper contributes greatly to the corrosion resistance of carbon steel

by retarding the rate of rusting at room temperature, but high levels of copper can cause welding difficulties.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1999 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON I, PART A

1.7.11

Columbium - Columbium is used in austenitic stainless steel to act as a stabi-

Cu Ch Tab Con

lizer. Since the carbon in the stainless steel decreases the corrosion resistance, a means

Lesson 2 Common Electric Arc Welding Processes

of making carbon ineffective must be found. Columbium has a greater affinity for carbon than chromium, leaving the chromium free for corrosion protection. 1.7.12

Tungsten - Tungsten is used in steel to given strength at high temperatures.

Tungsten also joins with carbon to form carbides that are exceptionally hard, and therefore

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

have exceptional resistance to wear. 1.7.13

Vanadium - Vanadium helps keep steel in the desirable fine grain condition after

P

heat treatment. It also helps increase the depth of hardening and resists softening of the

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

steel during tempering treatments.

Glo 1.7.14

Nitrogen - Usually, efforts are made to eliminate hydrogen, oxygen and nitrogen

from steel because their presence can cause brittleness. Nitrogen has the ability to form austenitic structures; therefore, it is sometimes added to austenitic stainless steel to reduce

Lesson 5 Welding Filler Metals for Stainless Steels

the amount of nickel needed, and therefore, the production costs of that steel. 1.7.15

Alloying Elements Summary - It should be understood that the addition of

elements to a pure metal may influence the crystalline form of the resultant alloy. If a pure metal has allotropic characteristics (the ability of a metal to change its crystal structure) at a

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Turn

specific temperature, then that characteristic will occur over a range of temperatures with the alloyed metal. The range in which the change takes place may be wide or narrow, depending on the alloys and the quantities in which they are added. The alloying element may also effect the crystalline changes by either suppressing the appearance of certain

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

crystalline forms or even by creating entirely new forms. All these transformations induced by alloying elements are dependent on heat input and cooling rates. These factors are closely controlled at the steel mill, but since the welding operation involves a nonuniform heating and cooling of metal, special care is often needed in the welding of low and high alloy steel.

Lesson 8 Hardsurfacing Electrodes

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1999 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

LESSON I, PART B

1.8

ELECTRICITY FOR WELDING

1.8.1

Principles of Electricity - Arc welding is a method of joining metals accom-

plished by applying sufficient electrical pressure to an electrode to maintain a current path (arc) between the electrode and the work piece. In this process, electrical energy is changed into heat energy, bringing the metals to a molten state; whereby they are joined. The electrode (conductor) is either melted and added to the base metal or remains in its

Lesson 3 Covered Electrodes for Welding Mild Steels

Cu Ch Tab Con

Go T

solid state. All arc welding utilizes the transfer of electrical energy to heat energy, and to understand this principle, a basic knowledge of electricity and welding power sources is

P

necessary. 1.8.1.1

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

The three basis principles of static electricity are as follows: 1. There are two kinds of electrical charges in existence - negative and positive.

Glo

2. Unlike charges attract and like charges repel. 3. Charges can be transferred from one place to another.

Lesson 5 Welding Filler Metals for Stainless Steels

1.8.1.2

Science has established that all matter is made up of atoms and each atom

contains fundamental particles. One of these particles is the electron, which has the ability to move from one place to another. The electron is classified as a negative electrical charge. Another particle, about 1800 times as heavy as the electron, is the proton and

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Turn

under normal conditions the proton will remain stationary. 1.8.1.3

Material is said to be in an electrically uncharged state when its atoms contain an

equal number of positive charges (protons) and negative charges (electrons). This balance is upset when pressure forces the electrons to move from atom to atom. This pressure,

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

sometimes referred to as electromotive force, is commonly known as voltage. It should be noted that voltage that does not move through a conductor, but without voltage, there would be no current flow. For our purposes, it is easiest to think of voltage as the electrical pressure that forces the electrons to move.

Lesson 8 Hardsurfacing Electrodes

1.8.1.4

Since we know that like charges repel and unlike charges attract, the tendency is

for the electrons to move from a position of over-supply (negative charge) to an atom that lacks electrons (positive charge). This tendency becomes reality when a suitable path is provided for the movement of the electrons. The transfer of electrons from a negative to a

Lesson 9 Estimating & Comparing Weld Metal Costs

positive charge throughout the length of a conductor constitutes an electrical current. The rate that current flows through a conductor is measured in amperes and the word ampere is often used synonymously with the term current. To give an idea of the quantities of electrons that flow through a circuit, it has been theoretically established that one ampere equals 6.3 quintillion (6,300,000,000,000,000,000) electrons flowing past a fixed point in a

Lesson 10 Reliability of Welding Filler Metals

Se Ch (Fa Dow

conductor every second.

© COPYRIGHT 1999 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON I, PART B

1.8.1.5

Different materials vary in their ability to transfer electrons. Substances, such as

Cu Ch Tab Con

wood and rubber, have what is called a tight electron bond and their atoms greatly resist

Lesson 2 Common Electric Arc Welding Processes

the free movement of electrons. Such materials are considered poor electrical conductors. Metals, on the other hand, have large amounts of electrons that transfer freely. Their comparatively low electrical resistance classifies them as good electrical conductors. 1.8.1.6

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

Electrical resistance is primarily due to the reluctance of atoms to give up their

electron particles. It may also be thought of as the resistance to current flow.

P 1.8.1.7

To better understand the electrical terms discussed above, we might compare

the closed water system with the electrical diagram shown in Figure 8. You can see that as

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

the pump is running, the water will move in the direction of the arrows. It moves because

Glo

pressure has been produced and that pressure can be likened to voltage in an electrical circuit. The pump can be compared to a battery or a DC generator. The water flows VALVE SWITCH

Lesson 5 Welding Filler Metals for Stainless Steels

RESISTOR 10 OHM LARGE PIPE

SMALL PIPE PUMP

Turn BATTERY 12 VOLT

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

CLOSED WATER SYSTEM

ELECTRICAL DIAGRAM

FIGURE 8

through the system at a certain rate. This flow rate in an electrical circuit is a unit of

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

measure known as the ampere. The small pipe in the fluid circuit restricts the flow rate and can be likened to a resistor. This unit resistance is known as the ohm. If we close the valve in the fluid circuit, we stop the flow, and this can be compared to opening a switch in an electrical circuit.

Lesson 8 Hardsurfacing Electrodes

1.8.2

Ohm's Law - Resistance is basic to electrical theory and to understand this

principle, we must know the Ohm's Law, which is stated as follows: In any electrical circuit, the current flow in amperes is directly proportional to the circuit voltage applied and inversely proportional to the circuit resistance. Directly proportional means that even though

Lesson 9 Estimating & Comparing Weld Metal Costs

the voltage and amperage may change, the ratio of their relationship will not. For example, if we have a circuit of one volt and three amps, we say the ratio is one to three. Now if we increase the volts to three, our amperage will increase proportionately to nine amps. As can be seen, even though the voltage and amperage changed in numerical value, their

Lesson 10 Reliability of Welding Filler Metals

Se Ch (Fa Dow

ratio did not. The term "inversely proportional" simply means that if the resistance is

© COPYRIGHT 1999 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON I, PART B

doubled, the current will be reduced to one-half. Ohm's Law can be stated mathematically

Cu Ch Tab Con

with this equation:

Lesson 2 Common Electric Arc Welding Processes

I=E÷R

1)

or

R=E÷I

The equation is easy to use as seen in the following problems:

Go T

A 12 volt battery has a built-in resistance of 10 ohms. What is the amperage?

P

12 ÷ 10 = 1.2 amps 2)

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

E=I×R

(E = Volts, I = Amperes, R = Resistance (Ohms))

1.8.2.1

Lesson 3 Covered Electrodes for Welding Mild Steels

or

What voltage is required to pass 15 amps through a resistor of 5 ohms?

Glo

15 × 5 = 75 volts 3)

When the voltage is 80 and the circuit is limited to 250 amps, what is the value of the resistor? 80 ÷ 250 = .32 ohms

Lesson 5 Welding Filler Metals for Stainless Steels

1.8.2.2

The theory of electrical resistance is of great importance in the arc welding

process for it is this resistance in the air space between the electrode and the base metal

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

that contributes to the transfer of electrical energy to heat energy. As voltage forces the electrons to move faster, the energy they generate is partially used to overcome the resistance created by the arc gap. This energy becomes evident as heat. In the welding process, the temperature increases to the point where it brings metals to a molten state. 1.8.3

Electrical Power - The word

"watt" is another term frequently encountered in

electrical terminology. When we pay our electrical bills, we are actually paying for the power to run our electrical appliances, and the watt is a unit of power. It is defined as the amount of power required to maintain a current of one ampere at a pressure of one volt. The circuit voltage that comes into your home is a constant factor, but the amperage drawn

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

from the utility company depends on the number of watts required to run the electrical

Se Ch (Fa Dow

appliance. The watt is figured as a product of volts times amperes and is stated mathematically with the following equation: W =E × I

E

=W ÷I

I

Se Doc (Sl Dow

=W ÷E

(W = Watts, E = Volts, I = Amperes) 1.8.3.1

The amperage used by an electrical device can be calculated by dividing the

watts rating of the device by the primary voltage for which it is designed.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1999 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON I, PART B

1.8.3.2

For example, if an appliance is designed for the common household primary

Cu Ch Tab Con

voltage of 115 and the wattage stamped on the appliance faceplate is 5, then the

Lesson 2 Common Electric Arc Welding Processes

amperage drawn by the appliance when in operation is determined as shown: 5 ÷ 115 = .04 amperes 1.8.3.3

Lesson 3 Covered Electrodes for Welding Mild Steels

Kilowatt is another term common in electrical usage. The preface "kilo" is a

Go T

metric designation that means 1,000 units of something; therefore, one kilowatt is 1,000 watts of power. 1.8.4

P

Power Generation - Electrical energy is supplied either as direct current (DC) or

alternating current (AC). With direct current, the electron movement within the conductor is

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

in one direction only. With alternating current, the electron flow reverses periodically. Although some types of electrical generators will produce current directly (such as batteries, dry cells, or DC generators), most direct current is developed from alternating current. 1.8.4.1

Through experimentation, it was discovered that when a wire is moved through a

magnetic field, an electrical current is induced into the wire, and the current is at its maximum when the motion of the conductor is at right angles to the magnetic lines of force. The sketch

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Glo

GALVANOMETER

Turn

in Figure 9 will help to illustrate this principle. 1.8.4.2

If the conductor is moved upwards in

the magnetic field between the N and S poles, the galvanometer needle will deflect plus (+).

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Likewise, if the conductor is moved downwards the needle will deflect minus (-). With this principle of converting mechanical energy into electrical energy understood, we can apply it to

ELECTRO-MAGNETIC INDUCTION

the workings of an AC generator.

Lesson 8 Hardsurfacing Electrodes

1.8.4.3

Figure 10 is a simplified sketch of an AC

FIGURE 9

generator. Starting at 0°rotation, the coil wire is moving parallel to the magnetic lines of force and cutting none of them. Therefore, no current is

Lesson 9 Estimating & Comparing Weld Metal Costs

being induced into the winding. 1.8.4.4

Se Ch (Fa Dow

From 0°to 90°rotation, the coil wire cuts an increasing number of magnetic lines

of force and reaches the maximum number at 90°rotation. The current increases to the maximum because the wire is now at right angles to the lines of force.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1999 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Cu Ch Tab Con

LESSON I, PART B ROTATING COIL OR ARMATURE

0°

N

Lesson 2 Common Electric Arc Welding Processes

90°

S

N

S

N 180°

N

S

Lesson 3 Covered Electrodes for Welding Mild Steels

270°

S

N

Go T

S

P PERMANENT MAGNETS OR FIELD COILS

CONTACTS

BASIC AC POWER GENERATION

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Glo FIGURE 10

1.8.4.5

From 90°to 180°rotation, the coil wire cuts a diminishing number of lines of

force and at 180°again reaches zero.

Lesson 5 Welding Filler Metals for Stainless Steels

1.8.4.6

because now the wire is in closer proximity to the opposite pole. 1.8.4.7

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

From 180°to 270°, the current begins to rise again but in the opposite direction

Turn

One cycle is completed as the coil wire moves from 270°to 0°and the current

again drops to zero. 1.8.4.8

With the aid of a graph, we can visualize the rate at which the lines of force are

cut throughout the cycle. If we plot the current versus degree of rotation, we get the familiar sine wave as seen in Figure 11.

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

1.8.4.9

With this sine wave, we can

see that one complete cycle of

(+)

MAXIMUM (+)

alternating current comprises one positive and one negative wave

Lesson 8 Hardsurfacing Electrodes

0

(negative and positive meaning

0

0

electron flow in opposing directions). The frequency of alternating current is the number of such complete cycles

Lesson 9 Estimating & Comparing Weld Metal Costs

Se Ch (Fa Dow

per second. For most power applications, 60 cycles per second (60 Hertz) is the standard frequency in

MAXIMUM (–) (–)

0° START

90° 1/4 TURN

180° 1/2 TURN

270° 3/4 TURN

360° FULL TURN

ONE CYCLE - ALTERNATING CURRENT

North America. FIGURE 11

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1999 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON I, PART B

1.8.4.10

Some welders use a three-phase AC supply. Three-phase is simply three

Cu Ch Tab Con

sources of AC power as identical voltages brought in by three wires, the three voltages or

Lesson 2 Common Electric Arc Welding Processes

phases being separated by 120 electrical degrees. If

line, they will appear as shown in Figure 12. 1.8.4.11

Lesson 3 Covered Electrodes for Welding Mild Steels

120°

0°

Go T

This illustrates that three-phase power is

smoother than single-phase because the overlapping

1 CYCLE

three phases prevent the current and voltage from

THREE PHASE AC

1.8.4.12

FIGURE 12

Glo

Since all shops do not have three-phase power, welding machines for both

single-phase and three-phase power are available. 1.8.5

Lesson 5 Welding Filler Metals for Stainless Steels

Transformers - The function of a transformer is to increase or decrease voltage

to a safe value as the conditions demand. Common household voltage is usually 115 or 230 volts, whereas industrial power requirements may be 208, 230, 380, or 460 volts. Transmitting such relatively low voltages over long distances would require a conductor of enormous and impractical size. Therefore, power transmitted from a power plant must be

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

P

falling to zero 120 times a second, thereby producing a smoother welding arc.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

240°

the sine wave for the three phases are plotted on one

Turn

stepped up for long distance transmission and then stepped down for final use 1.8.5.1

As can be seen in Figure 13, the voltage is generated at the power plant at

13,800 volts. It is increased, transmitted over long distances, and then reduced in steps for the end user. If power supplied to a transformer circuit is held steady, then secondary

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

current (amperes) decreases as the primary voltage increases, and conversely, secondary current increases as primary voltage decreases. Since the current flow (amperes) determines the wire or conductor size, the high voltage line may be of a relatively small

Se Ch (Fa Dow

diameter.

Lesson 8 Hardsurfacing Electrodes

4,600 V

HIGH VOLTAGE 34,000 V 13,800 V POWER

Lesson 9 Estimating & Comparing Weld Metal Costs

PLANT

132,000 V

287,000 V STEP UP

STEP DOWN

208V 230V 460V FINAL USE

300 MILES POWER TRANSMISSION

FIGURE 13

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1999 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON I, PART B 1.8.5.2

The transformer in a welding machine performs much the same as a large power

Cu Ch Tab Con

plant transformer. The primary voltage coming into the machine is too high for safe

Lesson 2 Common Electric Arc Welding Processes

welding. Therefore, it is stepped down to a useable voltage. This is best illustrated with an explanation of how a single transformer works. 1.8.5.3

In the preceding paragraphs, we have found than an electrical current can be

Go T

induced into a conductor when that conductor is moved through a magnetic field to

Lesson 3 Covered Electrodes for Welding Mild Steels

produce alternating current. If this alternating current is passed through a conductor, a

P

pulsating magnetic field will surround the exterior of that conductor, that is the magnetic field will build in intensity through the first 90 electrical degrees, or the first cycle. From that point, the magnetic field will decay during the next quarter cycle until the voltage or current

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

reaches zero at 180 electrical degrees. Immediately, the current direction reverses and the

Lesson 5 Welding Filler Metals for Stainless Steels

1.8.5.4

in the cycle. From that point the current and the magnetic field again begin to decay until they reach zero at 360 electrical degrees, where the cycle begins again. If that conductor is wound around a material with high magnetic permeability

(magnetic permeability is the ability to accept large amounts of magnetic lines of force) such as steel, the magnetic field permeates that core. See STEEL CORE

Figure 14. This conductor is called the primary coil, and if

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

voltage is applied to one of its terminals and the circuit is completed, current will flow. When a second coil is wound

PRIMARY COIL

Turn SECONDARY COIL

460 V

80 V

around that same steel core, the energy that is stored in this fluctuating magnetic field in the core is induced into

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Glo

magnetic field will begin to build again until it reaches a maximum at 270 electrical degrees

80 TURNS

460 TURNS

this secondary coil. BASIC TRANSFORMER

1.8.5.5

It is the build-up and collapse of this magnetic

field that excite the electrons in the secondary coil of the

FIGURE 14

transformer. This causes an electrical current of the same frequency as the primary coil to

Lesson 8 Hardsurfacing Electrodes

flow when the secondary circuit is completed by striking the welding arc. Remember that all transformers operate only on alternating current. 1.8.5.6

A simplified version of a welding transformer is schematically shown in Figure 15.

This welder would operate on 230 volts input power and the primary winding has 230 turns

Lesson 9 Estimating & Comparing Weld Metal Costs

Se Ch (Fa Dow

of wire on the core. We need 80 volts for initiating the arc in the secondary or welding circuit, thus we have 80 turns of wire in the secondary winding of the core. Before the arc is struck, the voltage between the electrode and the work piece is 80 volts. Remember that no current (amperage) flows until the welding circuit is completed by striking the arc.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1999 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON I, PART B

1.8.5.7

Since the 80 volts

9600 WATTS

9600 WATTS

Cu Ch Tab Con

necessary for initiating the arc

Lesson 2 Common Electric Arc Welding Processes

230 TURNS

is too high for practical welding, some means must be

41.74 AMPS

230 VOLTS

PRIMARY

80 TURNS

used to lower this voltage to a suitable level. Theoretically, a

Lesson 3 Covered Electrodes for Welding Mild Steels

32 VOLTS 300 AMPS

80 SECONDARY OCV

OUTPUT CONTROL

variable resistor of the proper value could be used as an

Go T

SIMPLIFIED WELDING TRANSFORMER

output control since voltage is

P

FIGURE 15

inversely proportional to resistance as we saw when studying Ohm's Law. Ohm's Law also stated that the

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

amperage is directly proportional to the voltage. This being so, you can see that adjusting the output control will also adjust the amperage or welding current. 1.8.5.8

Lesson 5 Welding Filler Metals for Stainless Steels

After the arc is initiated and current begins to flow through the secondary or

welding circuit, the voltage in that circuit will be 32 volts because it is then being controlled by the output control. 1.8.6

Power Requirements - We can make another calculation by looking back at

Figure 15, and that is power consumption. Earlier, we explained that the watt was the unit

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Watts = Volts × Amperes From Figure 15, we can see that the instantaneous power in the secondary

circuit is: Watts = 32 × 300 Watts = 9600 Watts 1.8.6.2

Lesson 8 Hardsurfacing Electrodes

The primary side of our transformer must be capable of supplying 9600 watts

also (disregarding losses due to heating, power factor, etc.), so by rearranging the formula,

Se Ch (Fa Dow

we can calculate the required supply line current or amperage: Amperage = Watts ÷ Volts A = 9600 ÷ 230 = 41.74 Amps

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

of electrical power and can be calculated by the formula:

1.8.6.1

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Glo

1.8.6.3

This information establishes the approximate power requirements for the welder,

and helps to determine the input cable and fuse size necessary.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1999 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON I, PART B 1.8.7

Rectifying AC to DC - Although much welding is accomplished with AC welding

Cu Ch Tab Con

power sources, the majority of industrial welding is done with machines that produce a

Lesson 2 Common Electric Arc Welding Processes

direct current arc. The commercially produced AC power that operates the welding machine must then be changed (rectified) to direct current for the DC arc. This is accom-

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

plished with a device called a rectifier. Two types of rectifiers have been used

P

extensively in welding machines, the old selenium rectifiers and the more

SILICON RECTIFIER

modern silicon rectifiers, often referred

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

SELENIUM RECTIFIER FIGURE 16

Glo

to as diodes. See Figure 16. 1.8.7.1

The function of a rectifier in the

circuit can best be shown by the use of the

Lesson 5 Welding Filler Metals for Stainless Steels

AC sine wave. With one diode in the circuit, half-wave rectification takes place as shown in Figure 17. 1.8.7.2

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

The negative half-wave is simply cut off and a pulsating DC is produced. During

second. By using four rectifiers connected in a

certain manner, a bridge rectifier is created, producing full wave rectification. The bridge rectifier results in 120 positive half-cycles per second, producing a SINGLE PHASE FULL WAVE RECTIFICATION FIGURE 18

rectification. See Figure 18. 1.8.7.4

Three-phase AC can be rectified to

Se Doc (Sl Dow

AC. Since three-phase AC power produces three times as many half-cycles per second as singlephase power, a relatively smooth DC voltage results as shown in Figure 19.

Se Ch (Fa Dow

1 CYCLE

produce an even smoother DC than single-phase

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

half-cycle, the current is blocked. This produces a DC composed of 60 positive pulses per

considerably smoother direct current than half-wave

Lesson 8 Hardsurfacing Electrodes

FIGURE 17

the positive half-cycle, current is allowed to flow through the rectifier. During the negative

1.8.7.3

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

SINGLE PHASE HALF WAVE RECTIFICATION

3 PHASE FULL WAVE RECTIFICATION FIGURE 19

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1999 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

LESSON I, PART B

1.9

CONSTANT CURRENT OR CONSTANT VOLTAGE

Welding power sources are designed in many sizes and shapes. They may supply either AC or DC, or both, and they may have various means of controlling their voltage and amperage output. The reasons for this is that the power source must be capable of producing the proper arc characteristics for the welding process being used. A power

Go T

source that produces a satisfactory arc when welding with coated electrodes will be less

Lesson 3 Covered Electrodes for Welding Mild Steels

Cu Ch Tab Con

than satisfactory for welding with solid and flux cored wires. 1.9.1

P

Constant Current Characteristics - Constant current power sources are used

primarily with coated electrodes. This type of power source has a relatively small change in

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

amperage and arc power for a corresponding relatively large change in arc voltage or arc illustrated by observing a graph that plots the voltampere curve. As can be seen in Figure 20, the

80

VOLT / AMPERE CURVE CONSTANT CURRENT

curve of a constant current machine drops down-

Lesson 5 Welding Filler Metals for Stainless Steels

V

In welding with coated electrodes, the

output current or amperage is set by the operator while the voltage is designed into the unit. The

O L T S

50

34V - 290 A

40

30

20

increasing or decreasing the arc length. A slight voltage and a slight decrease in amperage. A slight decrease in arc length will cause a decrease in arc voltage and a slight increase in amperage.

10

100

200

300

AMPERES CONSTANT CURRENT VOLT / AMPERE CURVE

FIGURE 20

Constant Voltage Characteristics - Constant voltage power sources, also

known as constant potential, are used in welding with solid and flux cored electrodes, and source, the voltage is set at the machine and amperage is determined by the speed that

Decreasing the wire feed speed decreases the amperage. 1.9.2.1

Arc length plays an important part in welding with solid and flux cored electrodes,

just as it does in welding with a coated electrode. However, when using a constant voltage power source and a wire feeder that delivers the wire at a constant speed, arc length

Lesson 10 Reliability of Welding Filler Metals

Se Ch (Fa Dow

as the name implies, the voltage output remains relatively constant. On this type of power the wire is fed to the welding gun. Increasing the wire feed speed increases the amperage.

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

32V - 300 A

30V - 308 A

operator can vary the arc voltage somewhat by

1.9.2

Lesson 8 Hardsurfacing Electrodes

60

machine is often called a "drooper."

increase in arc length will cause an increase in arc

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

70

ward rather sharply and for this reason, this type of

1.9.1.1

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Glo

length, thus the name constant current. The characteristics of this power source are best

caused by operator error, plate irregularities, and puddle movement are automatically

© COPYRIGHT 1999 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON I, PART B

compensated for by the characteristics of this process. To understand this, keep in mind

Cu Ch Tab Con

that with the proper voltage setting, amperage setting, and arc length, the rate that the wire

Lesson 2 Common Electric Arc Welding Processes

melts is dependent upon the amperage. If the amperage decreases, this melt-off rate decreases and if the amperage increases, so does the melt-off rate. 1.9.2.2

In Figure 21, we see that condition #2 produces the desired arc length, voltage,

Go T

and amperage. If the arc length is increased as in #1, the voltage increases slightly; the

Lesson 3 Covered Electrodes for Welding Mild Steels

amperage decreases considerably, and therefore, the melt-off rate of the wire decreases. The wire is now feeding faster than it is melting

1

2

3

P

off. This condition will advance the end of the wire towards the work piece until the proper arc

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

length is reached where again, the melt-off rate

Glo

equals the feeding rate. If the arc length is decreased as in #3, the voltage drops off slightly, the amperage is increased

Lesson 5 Welding Filler Metals for Stainless Steels

40

considerably, and the melt-off rate of the wire increases. Since the wire is now melting off faster than it is being fed, it melts back to the

30 V O L T S

20

10

proper arc length where the melt-off rate equals the feeding rate. This is often referred

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

to as a self-adjusting arc. These automatic corrections take place in fractions of a second,

Turn 100

200 300 AMPERES

400

VOLT / AMPERE CURVE - CONSTANT VOLTAGE FIGURE 21

and usually without the operator being aware of them.

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

1.9.2.3

There are a variety of different welding machines, each with its own unique

internal design. Our purpose is not to detail the function of each part of the machine, but to emphasize that their main difference is in the way they control the voltage and amperage output.

Lesson 8 Hardsurfacing Electrodes

1.9.3

Types of Welding Power Sources - A great variety of welding power sources

are being built today for electric arc welding and we shall mention some of the major types briefly. Welding power sources can be divided into two main categories: static types and

Lesson 9 Estimating & Comparing Weld Metal Costs

Se Ch (Fa Dow

rotating types. 1.9.3.1

Static Types - Static type power sources are all of those that use commercially

generated electrical power to energize a transformer that, in turn, steps the line voltage down to useable welding voltages. The two major categories of static power sources are the transformer type and the rectifier type.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1999 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON I, PART B

1.9.3.1.1 The transformer type produce only alternating current. They are commonly

Cu Ch Tab Con

called "Welding Transformers." All AC types utilize single-phase primary power and are of

Lesson 2 Common Electric Arc Welding Processes

the constant current type. 1.9.3.1.2 The rectifier types are commonly called "Welding Rectifiers" and produce DC or, AC and DC welding current. They may utilize either single phase or three phase input

Go T

power. They contain a transformer, but rectify the AC or DC by the use of selenium

Lesson 3 Covered Electrodes for Welding Mild Steels

rectifiers, silicon diodes or silicon controlled rectifiers. Available in either the constant current or the constant voltage type, some manufacturers offer units that are a combination

P

of both and can be used for coated electrode welding, non-consumable electrode welding and for welding with solid or flux cored wires.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

1.9.3.2

Rotating Types - Rotating type power sources may be divided into two classifi-

Glo

cations: 1.

Motor-Generators

2.

Engine Driven

1.9.3.2.1 Motor-generator types consist of an electric motor coupled to a generator or alternator that produces the desired welding power. These machines produced excellent welds, but due to the moving parts, required considerable maintenance. Few, if any, are

Turn

being built today.

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

1.9.3.2.2 Engine driven types consist of a gasoline or diesel engine coupled to a generator or alternator that produces the desired welding power. They are used extensively on jobs beyond commercial power lines and also as mobile repair units. Both rotating types can deliver either AC or DC welding power, or a combination of both. Both types are available as constant current or constant voltage models. 1.9.4

Power Source Controls - Welding power sources differ also in the method of

controlling the output current or voltage. Output may be controlled mechanically as in machines having a tapped reactor, a moveable shunt or diverter, or a moveable coil. Elec-

Lesson 8 Hardsurfacing Electrodes

trical types of controls, such as magnetic amplifiers or saturable reactors, are also utilized and the most modern types, containing silicon controlled rectifiers, give precise electronic control.

Lesson 9 Estimating & Comparing Weld Metal Costs

1.9.4.1

A detailed discussion of the many types of welding power sources on the market

today is much too lengthy a subject for this course, although additional information on the type of power sources for the various welding processes will be covered in Lesson II. 1.9.4.2

Lesson 10 Reliability of Welding Filler Metals

Se Ch (Fa Dow

Excellent literature is available from power source manufacturers, however, and

should be consulted for further reference.

© COPYRIGHT 1999 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON I, GLOSSARY

APPENDIX A

Cu Ch Tab Con

LESSON I - GLOSSARY OF TERMS

Lesson 2 Common Electric Arc Welding Processes AISI

—

American Iron and Steel Institute

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

Allotropic

Lesson 5 Welding Filler Metals for Stainless Steels

A material in which the atoms are capable of transforming into two

P

or more crystalline structures at different temperatures.

Alternating

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

—

—

An electrical current which alternately travels in either direction in a conductor. In 60 cycles per second (60 Hz) AC, the frequency

Current

Glo

used in the U.S.A., the current direction reverses 120 times every second.

Ampere

—

Unit of electrical rate of flow. Amperage is commonly referred to as the “current” in an electrical circuit.

ASME

—

American Society of Mechanical Engineers

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

ASTM

—

American Society for Testing and Materials

Atom

—

The smallest particle of an element that posses all of the characteristics of that element. It consists of protons, neutrons,

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

and electrons.

Carbon Steel

—

(Sometimes referred to as mild steel.) An alloy of iron and carbon. Carbon content is usually below 0.3%.

Lesson 8 Hardsurfacing Electrodes

Conductor

—

A material which has a relatively large number of loosely bonded electrons which may move freely when voltage (electrical pressure) is applied. Metals are good conductors.

Lesson 9 Estimating & Comparing Weld Metal Costs

Se Ch (Fa Dow

Constant Current —

(As applied to welding machines.) A welding power source which will produce a relatively small change in amperage despite changes in voltage caused by a varying arc length. Used mostly for welding with coated electrodes.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1999 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON I, GLOSSARY Constant Voltage —

(As applied to welding machines.) A welding power source which

Cu Ch Tab Con

will produce a relatively small change in voltage when the

Lesson 2 Common Electric Arc Welding Processes

amperage is changed substantially. Used mostly for welding with solid or flux cored electrodes.

Direct Current

—

conductor. Direction of current is dependent upon the electrical

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

all DC devices are usually marked (+) or (-). Reversing the leads

P

will reverse the direction of current flow.

Electron

—

Negatively charged particles that revolve around the positively

Glo

charged nucleus in an atom.

—

Containing iron. Example: carbon steel, low alloy steels, stainless steel.

Hertz

—

Hertz (Hz) is the symbol which has replaced the term “cycles per second.” Today, rather than saying 60 cycles per second or simply

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Go T

connections to the battery or other DC power source. Terminals on

Ferrous

Lesson 5 Welding Filler Metals for Stainless Steels

An electrical current which flows in only one direction in a

Turn

60 cycles, we say 60 Hertz or 60 Hz.

High Alloy Steels

—

Steels containing in excess of 10% alloy content. Stainless steel is considered a high alloy because it contains in excess of 10% chromium.

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Induced Current or Induction

—

The phenomena of causing an electrical current to flow through a conductor when that conductor is subjected to a varying magnetic

Lesson 8 Hardsurfacing Electrodes

field.

Ingot

—

Casting of steel (weighing up to 200 tons) formed at mill from melt of ore, scrap limestone, coke, etc.

Lesson 9 Estimating & Comparing Weld Metal Costs

Insulator

—

Se Ch (Fa Dow

A material which has a tight electron bond, that is, relatively few electrons which will move when voltage (electrical pressure) is applied. Wood, glass, ceramics and most plastics are good insulators.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1999 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

LESSON I, GLOSSARY

Kilowatt

—

1,000 watts

Low Alloy Steels

—

Steels containing small amounts of alloying elements (usually 1½% to 5% total alloy content) which drastically improves their properties.

Non-Ferrous

—

Containing no iron. Example: Aluminum, copper, copper alloys.

Go T

P Ohm

—

Unit of electrical resistance to current flow.

Glo

Phase Transformation

—

The changes in the crystalline structure of metals caused by temperature and time.

Proton

—

Positively charged particles which are part of the nucleus of atoms.

Rectifier

—

An electrical device used to change alternating current to direct current.

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Cu Ch Tab Con

Turn

SAE

—

Society of Automotive Engineers

Transformer

—

An electrical device used to raise or lower the voltage and inversely change the amperage.

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Volt

—

Unit of electromotive force, or electrical pressure which causes

Se Ch (Fa Dow

current to flow in an electrical circuit.

Watt

—

A unit of electrical power. Watts = Volts x Amperes

Se Doc (Sl Dow

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1999 THE ESAB GROUP, INC.

Cu Ch Tab Con

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

BASIC WELDING FILLER METAL TECHNOLOGY

Go T

P

Glo

A Correspondence Course

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

LESSON II COMMON ELECTRIC ARC WELDING PROCESSES

Se Ch (Fa Dow

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Turn

Se Doc (Sl Dow

ESAB

ESAB Welding & Cutting Products

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals ©COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

TABLE OF CONTENTS LESSON II COMMON ELECTRIC ARC WELDING PROCESSES

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Cu Ch Tab Con

Section Nr.

Section Title

Page

Go T

P 2.1

INTRODUCTION ..............................................................................

1

2.2

SHIELDED METAL ARC WELDING ...............................................

1

2.2.1

Equipment & Operation .....................................................................

2

2.2.2

Welding Power Sources ....................................................................

2

2.2.3

Electrode Holder................................................................................

4

2.2.4

Ground Clamp ...................................................................................

4

2.2.5

Welding Cables .................................................................................

4

2.2.6

Coated Electrodes ............................................................................

4

2.3

GAS-TUNGSTEN ARC WELDING ..................................................

5

2.3.1

Equipment & Operation .....................................................................

6

2.3.2

Power Sources ..................................................................................

7

2.3.3

Torches..............................................................................................

10

2.3.4

Shielding Gases ................................................................................

11

2.3.5

Electrodes .........................................................................................

12

2.3.6

Summary ...........................................................................................

13

2.4

GAS METAL ARC WELDING ..........................................................

13

2.4.1

Current Density ..................................................................................

14

2.4.2

Metal Transfer Modes ........................................................................

15

2.4.3

Equipment and Operation ..................................................................

17

2.4.4

Power Source....................................................................................

18

2.4.5

Wire Feeder ......................................................................................

19

2.4.6

Welding Gun ......................................................................................

20

2.4.7

Shielding Gases ................................................................................

21

2.4.7.1

Short Circuiting Transfer ....................................................

22

2.4.7.2

Spray Arc Transfer ............................................................

23

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Glo

Turn

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

Cu Ch Tab Con

TABLE OF CONTENTS LESSON II - Con't. Section Nr.

Section Title

Page

Go T Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

2.4.7.3

Pulse Spray Transfer .........................................................

23

2.4.8

Electrodes .........................................................................................

23

2.5

FLUX CORED ARC WELDING .......................................................

24

2.5.1

Self-Shielded Process .......................................................................

24

2.5.2

Gas Shielded Process.......................................................................

25

2.5.3

Current Density ..................................................................................

26

2.5.4

Equipment .........................................................................................

26

2.5.5

Power Source....................................................................................

26

2.5.6

Wire Feeder ......................................................................................

26

2.5.7

Welding Guns ....................................................................................

26

2.5.8

Shielding Gases ................................................................................

27

2.6

SUBMERGED ARC WELDING .......................................................

27

2.6.1

Submerged Arc Flux ..........................................................................

28

2.6.2

The Welding Gun ...............................................................................

28

2.6.3

Power Sources ..................................................................................

28

2.6.4

Equipment .........................................................................................

28

2.6.5

Electrodes .........................................................................................

29

2.6.6

Summary ...........................................................................................

29

2.7

ELECTROSLAG AND ELECTROGAS WELDING ..........................

30

2.7.1

Electroslag Welding...........................................................................

30

2.7.2

Flux ...................................................................................................

30

2.7.3

Process .............................................................................................

30

2.7.4

Equipment.........................................................................................

31

2.7.5

Summary ..........................................................................................

31

Appendix A - GLOSSARY OF TERMS .................................................................

32

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

P

Glo

Turn

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II

Cu Ch Tab Con

COMMON ELECTRIC ARC WELDING PROCESSES Lesson 2 Common Electric Arc Welding Processes

2.1

INTRODUCTION

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

After much experimentation by others in the early 1800's, an Englishman named Wilde obtained the first electric welding patent in 1865. He successfully joined two small pieces of

P

iron by passing an electric current through both pieces producing a fusion weld. Approximately twenty years later, Bernado, a Russian, was granted a patent for an electric arc welding

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

process in which he maintained an arc between a carbon electrode and the pieces to be joined, fusing the metals together as the arc was manually passed over the joint to be welded. 2.1.0.1

Glo

During the 1890's, arc welding was accomplished with bare metal electrodes that

were consumed in the molten puddle and became part of the weld metal. The welds were of

Lesson 5 Welding Filler Metals for Stainless Steels

poor quality due to the nitrogen and oxygen in the atmosphere forming harmful oxides and nitrides in the weld metal. Early in the Twentieth Century, the importance of shielding the arc from the atmosphere was realized. Covering the electrode with a material that decomposed in the heat of the arc to form a gaseous shield appeared to be the best method to accomplish

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

were tried. These efforts culminated in the extruded coated electrode in the mid-1920's, greatly improving the quality of the weld metal and providing what many consider the most significant advance in electric arc welding. 2.1.0.2

Since welding with coated electrodes is a rather slow procedure, more rapid

welding processes were developed. This lesson will cover the more commonly used electric arc welding processes in use today.

2.2

SHIELDED METAL ARC WELDING

Shielded Metal Arc Welding* , also known as manual metal arc welding, stick welding, or electric arc welding, is the most widely used of the various arc welding processes. Welding is performed with the heat of an electric arc that is maintained between the end of a coated metal

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

this end. As a result, various methods of covering electrodes, such as wrapping and dipping,

electrode and the work piece (See Figure 1). The heat produced by the arc melts the base metal, the electrode core rod, and the coating. As the molten metal droplets are transferred across the arc and into the molten weld puddle, they are shielded from the atmosphere by the gases produced from the decomposition of the flux coating. The molten slag floats to the top of the weld puddle where it protects the weld metal from the atmosphere during solidification.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II Other functions of the coating are to provide arc stability and control bead shape. More

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels

COATING

information on coating functions will be CORE ROD

covered in subsequent lessons. *

Shielded Metal Arc Welding (SMAW) is the terminology approved by the American Welding Society.

SHIELDING GASES

Equipment & Operation - One

2.2.1

reason for the wide acceptance of the SMAW

P

WORK PIECE SHIELDED METAL ARC WELDING FIGURE 1

Glo

The equipment consists of the following items. (See Figure 2)

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

1.

Welding power source

2.

Electrode holder

3.

Ground clamp

4.

Welding cables and connectors

5.

Accessory equipment (chipping hammer, wire brush)

6. 2.2.2

AC OR DC POWER SOURCE ELECTRODE CABLE ELECTRODE HOLDER ELECTRODE GROUND WORK

Protective equipment (helmet, gloves, etc.)

FIGURE 2

Welding Power Sources - Shielded metal arc welding may utilize either

alternating current (AC) or direct current (DC), but in either case, the power source selected must be of the constant current type. This type of power source will deliver a relatively constant amperage or welding current regardless of arc length variations by the operator (See Lesson I,

2.2.2.1

Whether to use an AC, DC, or AC/DC power source depends on the type of welding

to be done and the electrodes used. The following factors should be considered:

of electrode types. While most of the electrodes are designed to be used on AC or DC, some will work properly only on DC. 2. Metal Thickness - DC power sources may be used for welding both heavy sections and light gauge work. Sheet metal is more easily welded with DC

Lesson 10 Reliability of Welding Filler Metals

Se Ch (Fa Dow

Section 1.9). The amperage determines the amount of heat at the arc and since it will remain

1. Electrode Selection - Using a DC power source allows the use of a greater range

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

CABLE SHIELDED METAL ARC WELDING CIRCUIT

relatively constant, the weld beads produced will be uniform in size and shape.

Lesson 8 Hardsurfacing Electrodes

Go T

WELD METAL

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

SOLIDIFIED SLAG

MOLTEN POOL

process is the simplicity of the necessary equipment.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Cu Ch Tab Con

because it is easier to strike and maintain the DC arc at low currents.

© COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II

3. Distance from Work - If the distance from the work to the power source is great,

Cu Ch Tab Con

AC is the best choice since the voltage drop through the cables is lower than with

Lesson 2 Common Electric Arc Welding Processes

DC. Even though welding cables are made of copper or aluminum (both good conductors), the resistance in the cables becomes greater as the cable length increases. In other words, a voltage reading taken between the electrode and the work will be somewhat lower than a reading taken at the output terminals of the

Go T

power source. This is known as voltage drop.

Lesson 3 Covered Electrodes for Welding Mild Steels

4. Welding Position (See Appendix A - Glossary of Terms) - Because DC may be operated at lower welding currents, it is more suitable for overhead and vertical

P

welding than AC. AC can successfully be used for out-of-position work if proper electrodes are selected.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Glo

5. Arc Blow - When welding with DC, magnetic fields are set up throughout the weldment. In weldments that have varying thickness and protrusions, this magnetic field can affect the arc by making it stray or fluctuate in direction. This condition is especially troublesome when welding in corners. AC seldom causes this problem

Lesson 5 Welding Filler Metals for Stainless Steels

because of the rapidly reversing magnetic field produced. 2.2.2.2

Combination power sources that produce both AC and DC are available and

provide the versatility necessary to select the proper welding current for the application.

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

2.2.2.3

Turn

When using a DC power source, the question of whether to use electrode negative

or positive polarity arises. Some electrodes operate on both DC straight and reverse polarity, and others on DC negative or DC positive polarity only. Direct current flows in one direction in an electrical circuit and the direction of current flow and the composition of the electrode

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Se Ch (Fa Dow

coating will have a definite effect on the welding arc and weld bead. Figure 3 shows the connections and effects of straight and reverse polarity. 2.2.2.4

Electrode negative (-) produces welds with shallow penetration; however, the

electrode melt-off rate is high. The weld bead is rather wide and shallow as shown at "A" in

Lesson 8 Hardsurfacing Electrodes

Figure 3. Electrode positive (+) produces welds with deep penetration

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals

and a narrower weld

DC POWER SOURCE

A

B

HIGHER BURN-OFF RATE, LESS PENETRATION

DC POWER SOURCE

DEEP PENETRATION, LOW BURN-OFF RATE

ELECTRODE

ELECTRODE

bead as shown at "B" in Figure 3. WORK PIECE STRAIGHT POLARITY

WORK PIECE REVERSE POLARITY

FIGURE 3

© COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II 2.2.2.5

While polarity affects the penetration and burn-off rate, the electrode coating also

Cu Ch Tab Con

has a strong influence on arc characteristics. Performance of individual electrodes will be

Lesson 2 Common Electric Arc Welding Processes

discussed in succeeding lessons.

2.2.3

Electrode Holder - The electrode holder connects to the welding cable and con-

ducts the welding current to the electrode. The insulated handle is used to guide the electrode

Go T

over the weld joint and feed the electrode over the weld joint and feed the electrode into the

Lesson 3 Covered Electrodes for Welding Mild Steels

weld puddle as it is consumed. Electrode holders are available in different sizes and are rated

2.2.4 Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Ground Clamp - The ground clamp is used to connect the ground cable to the work

piece. It may be connected directly to the work or to the table or fixture upon which the work is

Glo

positioned. Being a part of the welding circuit, the ground clamp must be capable of carrying the welding current without overheating due to electrical resistance.

2.2.5 Lesson 5 Welding Filler Metals for Stainless Steels

P

on their current carrying capacity.

Welding Cables - The electrode cable and the ground cable are important parts of

the welding circuit. They must be very flexible and have a tough heat-resistant insulation. Connections at the electrode holder, the ground clamp, and at the power source lugs must be soldered or well crimped to assure low electrical resistance. The cross-sectional area of the cable must be sufficient size to carry the welding current with a minimum of voltage drop.

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Turn

Increasing the cable length necessitates increasing the cable diameter to lessen resistance and voltage drop. The table in Figure 4 lists the suggested American Wire Gauge (AWG) cable size to be used for various welding currents and cable lengths.

Welding Service Range (Amperes)

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

20 to 180 30 to 250 60 to 375 80 to 500 100 to 600

Lesson 8 Hardsurfacing Electrodes

Total Cable Length (Ground Lead Plus Electrode Lead) Up to 50 ft. Cable Voltage Size Drop #3 #2 #0 #00 #00

1.8 1.8 1.7 1.8 2.0

Up to 100 ft. Cable Voltage Size Drop

Up to 250 ft. Cable Voltage Size Drop

Up to 500 ft. Cable Voltage Size Drop

#2 #1 #0 #000 #0000

#1 #0 #00 #0000 ...

#0 #0 #000 #0000 ...

2.9 2.5 3.0 2.5 2.5

5.7 5.0 5.9 5.0 ...

9.1 9.9 9.3 9.9

Voltage Drop Figured At 180 200 300 400 500

Amps Amps Amps Amps Amps

Voltage drops indicated do not include any drop caused by poor connection, electrode holder, or work metal FIGURE 4

Lesson 9 Estimating & Comparing Weld Metal Costs

2.2.6

Coated Electrodes - Various types of coated electrodes are used in shielded

metal arc welding. Electrodes used for welding mild or carbon steels are quite different than those used for welding the low alloys and stainless steels. Details on the specific types will be covered in subsequent lessons.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

LESSON II

2.3

GAS TUNGSTEN ARC WELDING

Gas Tungsten Arc Welding* is a welding process performed using the heat of an arc established between a nonconsumable tungsten electrode and the work piece. See Figure 5. The electrode, the arc, and the area surrounding the molten weld puddle are protected from the atmosphere by an inert gas shield. The electrode is not consumed in the weld puddle as in

Go T

shielded metal arc welding. If a filler metal is

Lesson 3 Covered Electrodes for Welding Mild Steels

necessary, it is added to the leading the molten puddle as shown in 2.3.0.1

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

TORCH

Gas tungsten arc welding

produces exceptionally clean welds

Glo

no slag is produced, the chance TUNGSTEN ELECTRODE

inclusions in the weld metal is and the finished weld requires

SHIELDING GAS NOZZLE

ARC

and Helium, the primary shielding gases employed, are inert gases. Inert gases do not chemically combine

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

P

TRAVEL DIRECTION

virtually no cleaning. Argon

Lesson 5 Welding Filler Metals for Stainless Steels

with other elements and

INERT GAS SHIELD FILLER METAL

therefore, are used to exclude

GAS TUNGSTEN ARC WELDING

the reactive gases, such as oxygen and nitrogen, from forming compounds that could

FIGURE 5

be detrimental to the weld metal. 2.3.0.2

Gas tungsten arc welding may be used for welding almost all metals — mild steel,

low alloys, stainless steel, copper and copper alloys, aluminum and aluminum alloys, nickel

most extensively used for welding aluminum and stainless steel alloys where weld integrity is of the utmost importance. Another use is for the root pass (initial pass) in pipe welding, which requires a weld of the highest quality. Full penetration without an excessively high inside bead is important in the root pass, and due to the ease of current control of this process, it lends

Lesson 9 Estimating & Comparing Weld Metal Costs

itself to control of back-bead size. For high quality welds, it is usually necessary to provide an inert shielding gas inside the pipe to prevent oxidation of the inside weld bead.

*

Lesson 10 Reliability of Welding Filler Metals

Turn

WORK PIECE

and nickel alloys, magnesium and magnesium alloys, titanium, and others. This process is

Lesson 8 Hardsurfacing Electrodes

Cu Ch Tab Con

Gas Tungsten Arc Welding (GTAW ) is the current terminology approved by the American Welding Society, formerly known as "TIG" (Tungsten Inert Gas) welding.

© COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II 2.3.0.3

Gas tungsten arc welding lends itself to both manual and automatic operation. In

Cu Ch Tab Con

manual operation, the welder holds the torch in one hand and directs the arc into the weld joint.

Lesson 2 Common Electric Arc Welding Processes

The filler metal is fed manually into the leading edge of the puddle. In automatic applications, the torch may be automatically moved over a stationary work piece or the torch may be stationary with the work moved or rotated in relation to the torch. Filler metal, if required, is also fed automatically.

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

2.3.1

EQUIPMENT AND OPERATION - Gas tungsten arc welding may be accomplished

P

with relatively simple equipment, or it may require some highly sophisticated components. Choice of equipment depends upon the type of metal being joined, the position of the weld being made, and the quality of the weld metal necessary for the application. The basic equip-

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

ment consists of the following:

Glo

1.

The power source

2.

Electrode holder (torch)

3.

Shielding gas

4.

Tungsten electrode

5.

Water supply when necessary

6.

Ground cable

7.

Protective equipment

Turn

Figure 6 shows a basic gas tungsten arc welding schematic.

REGULATOR FLOW METER

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Se Ch (Fa Dow

GAS HOSE (WATER COOLED ONLY) TORCH

GAS COOLED ONLY * COMPOSITE CABLE WELDING CABLE WATER COOLER

Lesson 8 Hardsurfacing Electrodes

WORK

POWER SOURCE

Lesson 9 Estimating & Comparing Weld Metal Costs

* COMPOSITE CABLE GAS COOLED TORCH. CURRENT IN & GAS IN.

WATER TO TORCH

WATER FROM TORCH

WATER COOLED TORCH. CURRENT IN & WATER OUT

GROUND CABLE SHIELDING GAS SUPPLY

GAS TUNGSTEN ARC WELDING CONNECTION SCHEMATIC FIGURE 6

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II Power Sources - Both AC and DC power sources are used in gas tungsten arc

2.3.2

Cu Ch Tab Con

welding. They are the constant current type with a drooping volt-ampere curve. This type of

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels

power source produces very slight changes in the arc current when the arc length (voltage) is varied. Refer to Lesson I, Section 1.9. 2.3.2.1

The choice between an AC or DC welder depends on the type and thickness of the

Go T

metal to be welded. Distinct differences exist between AC and DC arc characteristics, and if DC is chosen, the polarity also becomes an important factor. The effects of polarity in GTAW

P

are directly opposite the effects of polarity in SMAW as described in paragraphs 2.2.2.3 through 2.2.2.5. In SMAW, the distribution of heat between the electrode and work, which determines the penetration and weld bead width, is controlled mainly by the ingredients in the

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

flux coating on the electrode. In GTAW where no flux coating exists, heat distribution between

Glo

the electrode and the work is controlled solely by the polarity. The choice of the proper welding current will be better understood by analyzing each type separately. The chart in Figure 7 lists current recommendations.

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

WELDING CURRENT Material & Thickness

DCEN

Aluminum Under 1/8" Over 1/8"

2 2&3

Magnesium Under 1/16" Over 1/16"

DCEP

2

SHIELDING GAS

AC High Freq.

Argon

Helium

Ar/He

1 1

1 1

2 3

2

1 1

1 1

2

Carbon Steel Under 1/8" Over 1/8"

1 1

1 1

Stainless Steel Under 1/8" Over 1/8"

1 1

1

Copper Under 1/8" Over 1/8"

1 1

Nickel Alloys Under 1/8" Over 1/8"

1 1

1

1

1

Titanium Under 1/8" Over 1/8"

Turn

2

3

1

2 2 1

1

1. 2. 3.

3 2

2 1

2

2 1

Preferred Choice - Manual Welding Preferred Choice - Automatic Welding Second Choice - Automatic Welding

CURRENT/SHIELDING GAS SELECTION, TUNGSTEN GAS ARC WELDING FIGURE 7

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II Direct current electrode negative (DCEN) is produced when the electrode is

2.3.2.2

Cu Ch Tab Con

connected to the negative terminal of the power source. Since the electrons flow from the

Lesson 2 Common Electric Arc Welding Processes

electrode to the plate, approximately 70% of the heat of the arc is concentrated at the work, and approximately 30% at the electrode end. This allows the use of smaller tungsten electrodes that produce a relatively narrow concentrated arc. The weld shape has deep penetration and is quite narrow. See Figure 8. Direct current electrode negative is suitable for weld-

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

ing most metals. Magnesium and aluminum have a refractory oxide coating on the surface that must be physically removed immediately prior to welding if DCSP is to be used.

P Direct current electrode positive (DCEP) is produced when the electrode is

2.3.2.3

connected to the positive terminal of the welding power source. In this condition, the electrons

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

flow from the work to the electrode tip, concentrating approximately 70% of the heat of the arc

Glo

at the electrode and 30% at the work. This higher heat at the electrode necessitates using larger diameter tungsten to prevent it from melting and contaminating the weld metal. Since the electrode diameter is larger and the heat is less concentrated at the work, the resultant

Lesson 5 Welding Filler Metals for Stainless Steels

weld bead is relatively wide and shallow. See Figure 8.

Electrode Polarity _

GAS IONS

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

ELECTRON FLOW

+

Direct Current Straight Polarity Electrode Negative

Penetration Deep Penetration Narrow Bead

Medium Penetration Alternating Current + _

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

+

_

Direct Current Reverse Polarity Electrode Positive

Medium Width Bead

Shallow Penetration

Oxide Cleaning

Heat Concentration

None

At Work

Good Cleans Oxide on Each Half

Cycle Alternates Between Electrode and Work

Maximum

Wide Bead

At Electrode

EFFECTS OF CURRENT TYPE - GAS TUNGSTEN ARC WELDING

Lesson 8 Hardsurfacing Electrodes

FIGURE 8

2.3.2.4

Aluminum and magnesium are two metals that have a heavy oxide coating that acts

as an insulator and must be removed before successful welding can take place. Welding with

Lesson 9 Estimating & Comparing Weld Metal Costs

electrode positive provides a good oxide cleaning action in the arc. If we were to study the physics of the welding arc, we find that the electric current causes the shielding gas atoms to lose some of their electrons. Since electrons are negatively charged, these gas atoms now are unbalanced and have an excessive positive charge. As we learned in Lesson I, unlike

Lesson 10 Reliability of Welding Filler Metals

charges attract. These positively charged atoms (or positive ions as they are known in

© COPYRIGHT 1998 THE ESAB GROUP, INC.

Turn

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II

chemical terminology) are attracted to the negative pole, in this case the work, at high velocity.

Cu Ch Tab Con

Upon striking the work surface, they dislodge the oxide coating permitting good electrical

Lesson 2 Common Electric Arc Welding Processes

conductivity for the maintenance of the arc, and eliminate the impurities in the weld metal that could be caused by these oxides. 2.3.2.5

Direct current electrode positive is rarely used in gas-tungsten arc welding. Despite

the excellent oxide cleaning action, the lower heat input in the weld area makes it a slow

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Go T

process, and in metals having higher thermal conductivity, the heat is rapidly conducted away from the weld zone. When used, DCEP is restricted to welding thin sections (under 1/8") of

P

magnesium and aluminum. 2.3.2.6

Alternating current is actually a combination of DCEN and DCEP and is widely

used for welding aluminum. In a sense, the advantages of both DC processes are combined,

Glo

and the weld bead produced is a compromise of the two. Remember that when welding with 60 Hz current, the electron flow from the electrode tip to the work reverses direction 120 times every second. Thereby, the intense heat alternates from electrode to work piece, allowing the

Lesson 5 Welding Filler Metals for Stainless Steels

use of an intermediate size electrode. The weld bead is a compromise having medium penetration and bead width. The gas ions blast the oxides from the surface of aluminum and magnesium during the positive half cycle. Figure 8 illustrates the effects of the different types

Turn

of current used in gas-tungsten arc welding.

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

2.3.2.7

DC constant current power sources - Constant current power sources, used for

shielded metal arc welding, may also be used for gas-tungsten arc welding. In applications where weld integrity is not of utmost importance, these power sources will suffice. With machines of this type, the arc must be initiated by touching the tungsten electrode to the work

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

and quickly withdrawing it to maintain the proper arc length. This starting method contaminates the electrode and blunts the point which has been grounded on the electrode end. These conditions can cause weld metal inclusions and poor arc direction. Using a power source designed for gas tungsten arc welding with a high frequency stabilizer will

Lesson 8 Hardsurfacing Electrodes

eliminate this problem. The electrode need not be touched to the work for arc initiation. Instead, the high frequency voltage, at very low current, is superimposed onto the welding current. When the electrode is brought to within approximately 1/8 inch of the base metal, the high frequency ionizes the gas path, making it conductive and a welding arc is established.

Lesson 9 Estimating & Comparing Weld Metal Costs

The high frequency is automatically turned off immediately after arc initiation when using direct current. 2.3.2.8

AC Constant Current Power Source - Designed for gas tungsten arc welding,

always incorporates high frequency, and it is turned on throughout the weld cycle to maintain a stable arc. When welding with AC, the current passes through 0 twice in every cycle and the

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II

arc must be reestablished each time it does so. The oxide coating on metals, such as

Cu Ch Tab Con

aluminum and magnesium, can act much like a rectifier as discussed in Lesson I. The positive

Lesson 2 Common Electric Arc Welding Processes

half-cycle will be eliminated if the arc does not reignite, causing an unstable condition. Continuous high frequency maintains an ionized path for the welding arc, and assures arc reignition each time the current changes direction. AC is extensively used for welding aluminum and magnesium.

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

2.3.2.9

AC/DC Constant Current Power Sources - Designed for gas tungsten arc

welding, are available, and can be used for welding practically all metals. The gas tungsten

P

arc welding process is usually chosen because of the high quality welds it can produce. The metals that are commonly welded with this process, such as stainless steel, aluminum and

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

some of the more exotic metals, cost many times the price of mild steel; and therefore, the welds. Among these are: 1.

Lesson 5 Welding Filler Metals for Stainless Steels

Remote current control, which allows the operator to control welding amperage with a hand control on the torch, or a foot control at the welding station.

2.

Automatic soft-start, which prevents a high current surge when the arc is initiated.

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

3.

Turn

Shielding gas and cooling water solenoid valves, which automatically control flow before, during and for an adjustable length of time after the weld is completed.

4.

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Spot-weld timers, which automatically control all elements during each spot-weld cycle.

Se Ch (Fa Dow

Other options and accessories are also available. 2.3.2.10

Power sources for automatic welding with complete programmable output are also

available. Such units are used extensively for the automatic welding of pipe in position. The

Lesson 8 Hardsurfacing Electrodes

welding current is automatically varied as the torch travels around the pipe. Some units provide a pulsed welding current where the amperage is automatically varied between a low and high several times per second. This produces welds with good penetration and improved weld bead shape.

Lesson 9 Estimating & Comparing Weld Metal Costs

Glo

power sources designed for this process have many desirable features to insure high quality

2.3.3

Torches - The torch is actually an electrode holder that supplies welding current to

the tungsten electrode, and an inert gas shield to the arc zone. The electrode is held in a collet-like clamping device that allows adjustment so that the proper length of electrode protrudes beyond the shielding gas cup. Manual torches are designed to accept electrodes of 3

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II inch or 7 inch lengths. Torches may be either air or water-cooled. The air-cooled types actu-

Cu Ch Tab Con

ally are cooled to a degree by the shielding gas that is fed to the torch head through a compos-

Lesson 2 Common Electric Arc Welding Processes

ite cable. The gas actually surrounds the copper welding cable, affording some degree of cooling. Water-cooled torches are usually used for applications where the welding current exceeds 200 amperes. The water inlet hose is connected to the torch head. Circulating around the torch head, the water leaves the torch via the current-in hose and cable assembly.

Lesson 3 Covered Electrodes for Welding Mild Steels

Cooling the welding cable in this manner allows the use of a smaller diameter cable that is

Go T

more flexible and lighter in weight.

P 2.3.3.1

The gas nozzles are made of ceramic materials and are available in various sizes

and shapes. In some heavy duty, high current applications, metal water-cooled nozzles are

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

used. 2.3.3.2

Glo A switch on the torch is used to energize the electrode with welding current and start

the shielding gas flow. High frequency current and water flow are also initiated by this switch if the power source is so equipped. In many installations, these functions are initiated by a foot

Lesson 5 Welding Filler Metals for Stainless Steels

control that also is capable of controlling the welding current. This method gives the operator full control of the arc. The usual welding method is to start the arc at a low current, gradually increase the current until a molten pool is achieved, and welding begins. At the end of the weld, current is slowly decreases and the arc extinguished, preventing the crater that forms at

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

2.3.4

Shielding Gases - Argon and helium are the major shielding gases used in gas

tungsten arc welding. In some applications, mixtures of the two gases prove advantageous. To a lesser extent, hydrogen is mixed with argon or helium for special applications.

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

2.3.4.1

Argon and helium are colorless, odorless, tasteless and nontoxic gases. Both are

inert gases, which means that they do not readily combine with other elements. They will not burn nor support combustion. Commercial grades used for welding are 99.99% pure. Argon is .38% heavier than air and about 10 times heavier than helium. Both gases ionize when

Lesson 8 Hardsurfacing Electrodes

present in an electric arc. This means that the gas atoms lose some of their electrons that have a negative charge. These unbalanced gas atoms, properly called positive ions, now have a positive charge and are attracted to the negative pole in the arc. When the arc is positive and the work is negative, these positive ions impinge upon the work and remove

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

the end of the weld when the arc is broken abruptly.

surface oxides or scale in the weld area. 2.3.4.2

Argon is most commonly used of the shielding gases. Excellent arc starting and

ease of use make it most desirable for manual welding. Argon produces a better cleaning action when welding aluminum and magnesium with alternating current. The arc produced is

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II relatively narrow. Argon is more suitable for welding thinner material. At equal amperage,

Cu Ch Tab Con

helium produces a higher arc voltage than argon. Since welding heat is the product of volts

Lesson 2 Common Electric Arc Welding Processes

times amperes, helium produces more available heat at the arc. This makes it more suitable for welding heavy sections of metal that have high heat conductivity, or for automatic welding operations where higher welding speeds are required. 2.3.4.3

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Argon-helium gas mixtures are used in applications where higher heat input and the

Go T

desirable characteristics of argon are required. Argon, being a relatively heavy gas, blankets the weld area at lower flow rates. Argon is preferred for many applications because it costs

P

less than helium. 2.3.4.4

Helium, being approximately 10 times lighter than argon, requires flow rates of 2 to

Glo

3 times that of argon to satisfactorily shield the arc. 2.3.5

Electrodes - Electrodes for gas tungsten arc welding are available in diameters

from .010" to 1/4" in diameter and standard lengths range from 3" to 24". The most commonly

Lesson 5 Welding Filler Metals for Stainless Steels

used sizes, however, are the .040", 1/16", 3/32", and 1/8" diameters. 2.3.5.1

The shape of the tip of the electrode is an important factor in gas tungsten arc

welding. When welding with DCEN, the tip must be ground to a point. The included angle at which the tip is ground varies with the application, the electrode diameter, and the welding

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Turn

current. Narrow joints require a relatively small included angle. When welding very thin material at low currents, a needlelike point ground onto the smallest available electrode may be necessary to stabilize the arc. Properly ground electrodes will assure easy arc starting, good arc stability, and proper bead width.

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

2.3.5.2

When welding with AC, grinding the electrode tip is not necessary. When proper

welding current is used, the electrode will form a hemispherical end. If the proper welding current is exceeded, the end will become bulbous in shape and possibly melt off to contaminate the weld metal.

Lesson 8 Hardsurfacing Electrodes

2.3.5.3

The American Welding Society has published Specification AWS A5.12-80 for

tungsten arc welding electrodes that classifies the electrodes on the basis of their chemical composition, size and finish. Briefly, the types specified are listed below:

Lesson 9 Estimating & Comparing Weld Metal Costs

1) Pure Tungsten (AWS EWP) Color Code: Green Used for less critical applications. The cost is low and they give good results at relatively low currents on a variety of metals. Most stable arc when used on AC, either balanced wave or continuous high frequency.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II 2) 1% Thoriated Tungsten (AWS EWTh-1) Color Code: Yellow

Cu Ch Tab Con

Good current carrying capacity, easy arc starting and provide a stable arc. Less

Lesson 2 Common Electric Arc Welding Processes

susceptible to contamination. Designed for DC applications of nonferrous materials. 3) 2% Thoriated Tungsten (AWS EWTh-2) Color Code: Red Longer life than 1% Thoriated electrodes. Maintain the pointed end longer, used for light gauge critical welds in aircraft work. Like 1%, designed for DC applications for

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

nonferrous materials.

P 4) .5% Thoriated Tungsten (AWS EWTh-3) Color Code: Blue Sometimes called "striped" electrode because it has 1.0-2.0% Thoria inserted in a wedge-shaped groove throughout its length. Combines the good properties of pure

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Glo

and thoriated electrodes. Can be used on either AC or DC applications. 5) Zirconia Tungsten (AWS EWZr) Color Code: Brown Longer life than pure tungsten. Better performance when welding with AC. Melts more

Lesson 5 Welding Filler Metals for Stainless Steels

easily than thoriam-tungsten when forming rounded or tapered tungsten end. Ideal for applications where tungsten contamination must be minimized.

2.3.6

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Summary - Gas Tungsten Arc Welding is one of the major welding processes

Turn

today. The quality of the welds produced and the ability to weld very thin metals are the major features. The weld metal quality is high since no flux is used, eliminating the problem of slag inclusions in the weld metal. It is used extensively in the aircraft and aerospace industry, where high quality welds are necessary and also for welding the more expensive metals where the

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

weld defects become very costly. Metals as thin as .005" can be welded due to the ease of controlling the current. 2.3.6.1

The major disadvantages of the process are that it is slower than welding with

consumable electrodes and is little used on thicknesses over 1/4" for this reason. Shielding

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

gas and tungsten electrode costs make the process relatively expensive.

2.4

Gas Metal Arc Welding* is an arc welding process that uses the heat of an electric arc established between a consumable metal electrode and the work to be welded. The electrode is a bare metal wire that is transferred across the arc and into the molten weld puddle. The *

Lesson 10 Reliability of Welding Filler Metals

GAS METAL ARC WELDING

Gas Metal Arc Welding (GMAW) is the current technology approved by the American Welding Society. Formerly known as "MIG" (Metal Inert Gas) Welding.

© COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II wire, the weld puddle, and the area in the arc zone are protected from the atmosphere by a

Cu Ch Tab Con

gaseous shield. Inert gases, reactive gases, and gas mixtures are used for shielding. The

Lesson 2 Common Electric Arc Welding Processes

metal transfer mode is dependent on shielding gas choice and welding current level. Figure 9 is a sketch of the process showing the basic features. TRAVEL DIRECTION

WELDING WIRE WELDING CABLE

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

SHIELDING GAS

SOLID WIRE ELECTRODE

P GAS NOZZLE

GAS SHIELD

CONTACT TIP

ARC

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Glo

WELD METAL WORK PIECE

MOLTEN POOL GAS METAL ARC WELDING

Lesson 5 Welding Filler Metals for Stainless Steels

FIGURE 9

2.4.0.1

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Gas metal arc welding is a versatile process that may be used to weld a wide

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variety of metals including carbon steels, low alloy steels, stainless steels, aluminum alloys, magnesium, copper and copper alloys, and nickel alloys. It can be used to weld sheet metal or relatively heavy sections. Welds may be made in all positions, and the process may be used for semiautomatic welding or automatic welding. In semiautomatic welding, the wire feed

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

speed, voltage, amperage, and gas flow are all preset on the control equipment. The operator needs merely to guide the welding gun along the joint at a uniform speed and hold a relatively constant arc length. In automatic welding, the gun is mounted on a travel carriage that moves along the joint, or the gun may be stationary with the work moving or revolving beneath it. 2.4.0.2

Practically all GMAW is done using DCEP (Electrode positive). This polarity

provides deep penetration, a stable arc and low spatter levels. A small amount of GMAW welding is done with DCEN and although the melting rate of the electrode is high, the arc is erratic. Alternating current is not used for gas metal arc welding.

Lesson 9 Estimating & Comparing Weld Metal Costs

2.4.1

Current Density - To understand why gas metal arc welding can deposit weld

metal at a rapid rate, it is necessary that the term "current density" be understood. Figure 10 shows a 1/4" coated electrode and a 1/16" solid wire drawn to scale. Both are capable of carrying 400 amperes. Notice that the area of the 1/16" wire is only 1/16 that of the core wire

Lesson 10 Reliability of Welding Filler Metals

of the coated electrode. We can say that the current density of the 1/16" wire is 16 times

© COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II AREA = .049 SQ. IN.

greater than the current density

Cu Ch Tab Con

of the 1/4" wire at equal welding

Lesson 2 Common Electric Arc Welding Processes

currents. The resultant melt-off

CORE WIRE

rate of the solid wire is very high.

A A × 16

If we were to increase the current

1/16"

through the 1/4" coated

Lesson 3 Covered Electrodes for Welding Mild Steels

AREA = .0031 SQ. IN.

electrode to increase the current

Lesson 5 Welding Filler Metals for Stainless Steels

SOLID WIRE

density, the resistance heating

1/4"

through the 14" electrode length would be

P

COATED ELECTRODE

.049 ÷ .0031 = 16

excessive, and the rod would become so hot that the coating would crack, rendering

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Go T

FLUX COATING

RELATIVE SIZE OF ELECTRODES FOR WELDING AT 400 AMPS

Glo

it useless. The 1/16" wire carries the high FIGURE 10

current a distance of less than 3/4", the approximate distance from the end of the contact tip to the arc. 2.4.2

Metal Transfer Modes

2.4.2.1

Spray transfer is a high current density process that rapidly deposits weld metal in

droplets smaller than the electrode diameter. They are propelled in a straight line from the center of the electrode. A shielding gas mixture of Argon with 1% to 2% Oxygen is used for

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

welding mild and low alloy steel, and pure Argon or Argon-Helium mixtures are used for welding aluminum, magnesium, copper, and nickel alloys. Welding current at which spray transfer

Se Ch (Fa Dow

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

SPRAY TRANSFER

GLOBULAR TRANSFER

PULSE TRANSFER

1 2 3 SHORT CIRCUITING ARC METAL TRANSFER

MODES OF METAL TRANSFER FIGURE 11

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

takes place is relatively high and will vary with the metal being welded, electrode diameter, and the shielding gas being used. Deposition rates are high and welding is usually limited to the flat or horizontal fillet position. See Figure 11.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II

2.4.2.2

Globular transfer takes place at lower welding currents than spray transfer. There

Cu Ch Tab Con

is a transition current where the transfer changes to globular even when shielding gases using

Lesson 2 Common Electric Arc Welding Processes

a high percentage of argon are used. When carbon dioxide (CO ) is used as a shielding gas, 2

the transfer is always globular. In globular transfer, a molten drop larger than the electrode diameter forms on the end of the electrode, moves to the outer edge of the electrode and falls into the molten puddle. Occasionally, a large drop will "short circuit" across the arc, causing

Lesson 3 Covered Electrodes for Welding Mild Steels

the arc to extinguish momentarily, and then instantaneously reignite. As a result, the arc is somewhat erratic, spatter level is high, and penetration shallow. Globular transfer is not

P

suitable for out-of-position welding. See Figure 11. 2.4.2.3

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Go T

Short circuiting transfer is a much used method in gas metal arc welding. It is

produced by using the lowest current-voltage settings and the smaller wires, usually .030",

Glo

.035", and .045" diameters. The low heat input makes this process ideal for sheet metal, outof-position work, and poor fit-up applications. Often called "short arc welding" because metal transfer is achieved each time the wire actually short circuits (makes contact) with the weld

Lesson 5 Welding Filler Metals for Stainless Steels

puddle. This happens very rapidly. It is feasible for the short circuit frequency to be 20-200 times a second, but in practice, it occurs from 90-100 times a second. Each time the electrode touches the puddle, the arc is extinguished. It happens so rapidly that it is visible only on high speed films.

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

2.4.2.4

Pulse transfer is a mode of metal transfer somewhat between spray and short

circuiting. The specific power source has built into it two output levels: a steady background level, and a high output (peak) level. The later permits the transfer of metal across the arc. This peak output is controllable between high and low values up to several hundred cycles per

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

second. The result of such a peak output produces a spray arc below the typical transition current. 2.4.2.4.1 Figure 11 shows the transfer method. The arc is initiated by touching the wire to the work. Upon initial contact, a bit of the wire melts off to form a molten puddle. The wire feeds

Lesson 8 Hardsurfacing Electrodes

forward until it actually contacts the work again, as at 1 in Figure 11, and the arc is extinguished. The short circuiting current causes the wire to neck down, as shown in 1, until it melts off, as shown at 2. As soon as the wire is free of the puddle, the arc is reignited and a molten ball forms at the end of the electrode, as at 3. The wire continues to move forward until

Lesson 9 Estimating & Comparing Weld Metal Costs

it makes contact with the puddle, and the cycle is repeated. 2.4.2.5

Gas metal arc spot welding is a variation of the process that allows spot welding

of thinner gauge metals, or of a thin gauge metal to a heavier section. The gun is placed directly against the work and is equipped with a special nozzle to allow escape of the shielding gas. When the trigger switch is actuated, the following sequence takes place. The shielding

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II gas flows for a short interval before wire feeding starts; wire feeding starts; the arc is initiated

Cu Ch Tab Con

and continues for a preset time (usually a few seconds). The welding current and wire feeding

Lesson 2 Common Electric Arc Welding Processes

stops, and the shielding gas flows for a short interval before it automatically stops. The process is also useful for tacking welding pieces in position prior to running the final weld bead.

2.4.3 Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

EQUIPMENT AND OPERATION - The equipment used for gas metal arc welding

Go T

is more complicated than that required for shielded metal arc welding. Initial cost is relatively high, but the cost is rapidly amortized due to the savings in labor and overhead achieved by

P

the rapid weld metal deposition. 2.4.3.1

The equipment necessary for gas metal arc welding is listed below:

Glo 1) Power source 2) Wire feeder 3) Welding gun

Lesson 5 Welding Filler Metals for Stainless Steels

4) Shielding gas supply 5) Solid electrode wire 6) Protective equipment

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

2.4.3.2

Turn

The basic equipment necessary for semiautomatic gas metal arc welding is shown

in Figure 12.

GAS HOSE FLOWMETER REGULATOR TRIGGER CONTROL LEAD FEED ROLLS

WIRE SPOOL WIRE FEEDER

Se Doc (Sl Dow

VALVE

Lesson 8 Hardsurfacing Electrodes MAGNETIC

Lesson 9 Estimating & Comparing Weld Metal Costs

WELD CABLE 115V

WELDING GUN

SHIELDING GAS

CONTACTOR _ +

POWER SOURCE

GROUND CABLE WORK SCHEMATIC DIAGRAM SEMI-AUTOMATIC GMAW EQUIPMENT

Lesson 10 Reliability of Welding Filler Metals

Se Ch (Fa Dow

FIGURE 12

© COPYRIGHT 1998 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON II 2.4.4

Lesson 2 Common Electric Arc Welding Processes

Power Source - A direct current, constant voltage power source is recommended

for gas metal arc welding. It may be a transformer-rectifier or a rotary type unit. The lower open circuit voltage and self-correcting arc length feature, as described in Lesson I, makes it most suitable. Constant voltage power sources used for spray transfer welding and for flux cored electrode welding (to be covered later) are the same. However, if the unit is to be used for short-circuiting arc

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

welding, it must have "slope" or slope control.

high short-circuit current that is characteristic of this type welder. Figure

OPERATING POINT V O L T S

20

CONSTANT VOLTAGE V/A CURVE

Glo

15 10

13 shows the effect of slope on the short-

Lesson 5 Welding Filler Metals for Stainless Steels

P

25

Slope control is a means of limiting the

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

SHORT CIRCUITING CURRENT NO SLOPE

5

SHORT CIRCUITING CURRENT WITH SLOPE

circuiting current. 200

2.4.4.1

If we were

400

600

800

1000

1200

1400

EFFECT OF SLOPE ON SHORT CIRCUITING CURRENT

short-arc welding at

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

approximately 150 amperes

Turn

FIGURE 13

and 18 volts, as shown in Figure 13, and had no slope components in the power source, the current at short-circuit or when the wire touches the work, would be over 1400 amperes. At this high current, a good length of the wire would literally explode off the end, cause much spatter, and the arc would be erratic. With the

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

slope components in the circuit, the short-circuiting current is in the neighborhood of 400 amperes, and the molten ball is sort of pinched off the end of the wire more gently. For those with an electrical background, it might be added that in some machines, slope is achieved by adding a reactor in the AC secondary of the power source. In others, a slope resistor is added

Lesson 8 Hardsurfacing Electrodes

in the DC output portion of the circuit. Slope may be adjustable for varying wire diameters or it may be fixed, giving a good average value for .035" and .045" diameter wires, the two most popular sizes. 2.4.4.2

Lesson 9 Estimating & Comparing Weld Metal Costs

Cu Ch Tab Con

Another factor influencing the arc in short-circuiting welding is the rate that the

amperage reaches the short-circuiting current level. Using the example in Figure 13, we know that the current goes from 150 amperes to 400 amperes during each shorting period. If we were to plot the current rise on a graph, as in Figure 14, we would see that the current rise if very rapid, as shown by the broken line.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II This rapid current rise can be

Cu Ch Tab Con

by using a device called an

Lesson 2 Common Electric Arc Welding Processes

(sometimes called a stabilizer) output circuit of the welder. An 400 AMPS WITHOUT INDUCTANCE

merely an iron core wound turns of heavy wire. It does current flow, but it acts

Lesson 3 Covered Electrodes for Welding Mild Steels

WITH INDUCTANCE

Go T

somewhat like a fly wheel or damper by retarding the rate of

P

rise as shown by the solid line. By preventing the

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

150 AMPS

rapid current rise, the arc

TIME - MILLISECONDS EFFECT OF INDUCTANCE ON CURRENT RISE FIGURE 14

Lesson 5 Welding Filler Metals for Stainless Steels

becomes smoother, spatter is reduced, and bead shape and appearance are

improved. Because the inductor influences the time function, its design determines arc on-off time, and short-circuit frequency. Some power sources have a selector that can switch in several different inductance values to finely tune the arc.

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Glo

2.4.4.4

Turn

Welding power sources designed for gas metal arc welding have a 115 volt outlet to

provide power to operate the wire feeder. They also have a receptacle to receive the electrical power required to close the main contactor in the power source, which turns on the welding power to the welding gun when the gun trigger is actuated.

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

2.4.4.5

Additional advancements in equipment technology have introduced many new

models. Inverters, as well as microprocessor controls, have created the greatest attention. In addition, multipurpose machines have provided the user with greater flexibility with a variety of capabilities.

Lesson 8 Hardsurfacing Electrodes

2.4.4.6

Global competition will continue to have a profound influence on future

advancements in arc welding equipment. As energy prices rise, greater demands for more efficient equipment will follow.

Lesson 9 Estimating & Comparing Weld Metal Costs

2.4.5

Wire Feeder - When welding with a constant voltage power source, as is the case

in most gas metal arc welding applications, the prime function of the wire feeder is to deliver the welding wire to the arc at a very constant speed. Since the wire feed speed determines the amperage, and the amperage determines the amount of heat at the arc, inconsistent wire

Lesson 10 Reliability of Welding Filler Metals

feed speed will produce welds of varying penetration and bead width. Advanced electronics

© COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II technology makes it possible to design motor speed controls that will produce the same

Cu Ch Tab Con

speed, even though the load on the motor varies or the input voltage to the motor may fluctuate.

Lesson 2 Common Electric Arc Welding Processes

2.4.5.1

A limited amount of gas metal arc welding is performed with constant current type

power sources. In this case, the motor speed automatically varies to increase or decrease the wire feed speed as the arc length varies to maintain a constant voltage.

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

2.4.5.2

reasons. This assures that the welding wire will only be energized when the switch on the welding gun is depressed. 2.4.5.3

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

The wire feeder also controls the main contactor in the power source for safety

P

The flow of shielding gas is controlled by a solenoid valve (magnetic valve) in the

wire feeder to turn the shielding gas on and off when the gun switch is actuated. Most feeders

Glo

utilize a dynamic breaking circuit to quickly stop the motor at the end of a weld to prevent a long length of wire protruding from the gun when the weld is terminated. Most feeders have a burn-back circuit that allows the welding current to stay on for a short period of time after wire

Lesson 5 Welding Filler Metals for Stainless Steels

feeding has stopped, to allow the wire to burn back exactly the right amount for the next arc initiation. 2.4.5.4

The feed rolls, sometimes called drive rolls, pull the wire off the spool or reel, and

push it through a feed cable or conduit to the welding gun. These rolls must usually be

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

changed to accommodate each different wire diameter, although some rolls are designed to feed a combination of sizes.

2.4.6

Welding Gun - The function of the welding gun, sometimes referred to as a torch, is

to deliver the welding wire, welding current, and shielding gas to the welding arc. Guns are available for semi-automatic operation and for automatic operation, where they are fixed in the automatic welding head. 2.4.6.1

Guns for GMAW have several characteristics in common. All have a copper alloy

shielding gas nozzle, that delivers the gas to the arc area in a nonturbulent, angular pattern to

Lesson 8 Hardsurfacing Electrodes

prevent aspiration of air. The nozzle may be water cooled for semiautomatic welding at high amperage and for automatic welding where the arc time is of long duration. Welding current is transferred to the welding wire as the wire travels through the contact tip or contact tube located inside the gas nozzle (Refer to Figure 9). The hole in the contact tip through which the

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

wire passes is only a few thousandths of an inch larger than the wire diameter. A worn contact tip will result in an erratic arc due to poor current transfer. Figure 15 shows a few different semiautomatic gun configurations that are commonly used for GMAW.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II

Lesson 2 Common Electric Arc Welding Processes

CURVED NECK

Cu Ch Tab Con

PISTOL TYPE

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

SELF CONTAINED PULL TYPE

P

SEMI-AUTOMATIC GMAW GUN TYPES

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Glo

FIGURE 15

2.4.6.2

The curved neck or "goose neck" type is probably the most commonly used. It

allows the best access to a variety of weld joints. The wire is pushed to this type of gun by the

Lesson 5 Welding Filler Metals for Stainless Steels

feed rolls in the wire feeder through a feed cable or conduit that usually is 10 or 12 feet in length. The shielding gas hose, welding current cable, and trigger switch leads are supplied with the welding gun. 2.4.6.3

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

metal arc spot welding applications. 2.4.6.4

The self contained type has an electric motor in the handle and feed rolls that pull the

wire from a 1 or 2 pound spool mounted on the gun. The need for a long wire feed cable is eliminated, and wire feed speed may be controlled by the gun. Guns of this type are often used for aluminum wire up to .045" diameter, although they may also be used for feeding steel or other hard wires. The pull type gun has either an electric motor or an air motor mounted in the handle

that is coupled to a feeding mechanism in the gun. The spool of wire is located in the control cabinet that may be located as far as fifty feet from the gun. When feeding such long distances, a set of "push" rolls located in the control cabinet assist in feeding the wire. This

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

difficult to reach joints. The pistol type is also a "push" type gun and is more suitable for gas

2.4.6.5

Lesson 8 Hardsurfacing Electrodes

The pistol type gun is similar to the curved neck type, but is less adaptable for

then becomes known as a push-pull feed system and is especially useful in feeding the softer wires such as aluminum.

2.4.7

SHIELDING GASES - In gas metal arc welding, there are a variety of shielding

gases that can be used, either alone or in combinations of varying degrees. The choice is dependent on the type of metal transfer employed, the type and thickness of metal, the bead

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II profile (See Figure 16), penetration, and speed of welding. In our discussion, we will deal with

Cu Ch Tab Con

the more common choices used for the various transfer processes.

Lesson 2 Common Electric Arc Welding Processes

FERROUS METALS

NON-FERROUS METALS

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

CO2

ARGON + CO2

ARGON + O2

ARGON

HELIUM

P BEAD PROFILE FIGURE 16

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

2.4.7.1

Short Circuiting Transfer - Straight carbon dioxide (CO ) is often used for short

Glo

2

circuiting arc welding because of its low cost. The deep penetration usually associated with CO is minimized because of the low amperage and voltage settings used with this process. 2

Compared to other gas mixes, CO will produce a harsher arc and therefore, greater spatter 2

Lesson 5 Welding Filler Metals for Stainless Steels

levels. Usually, this is minimized by maintaining a short arc length and by careful adjustment of the power supply inductance. The temperatures reached in welding will cause carbon dioxide to decompose into carbon monoxide and oxygen. To reduce the possibility of porosity caused by entrapped oxygen in the weld metal, it is wise to use electrodes that contain deoxidizing

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Turn

elements, such as silicon and manganese. If the current is increased above the short circuiting range, the use of carbon dioxide tends to produce a globular transfer. 2.4.7.1.1 Mixing argon in proportions of 50-75% with carbon dioxide will produce a smoother arc and reduce spatter levels. It will also widen the bead profile, reduce penetration, and

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

encourage "wetting". Wetting, i.e., a uniform fusion, along with joining edges of the base metal and the weld metal, minimizes the weld imperfection known as undercutting (See Figure 17).

UNDERCUT

Se Doc (Sl Dow

WETTING FIGURE 17

2.4.7.1.2 The 75% Argon/25 CO mixture is often chosen for short circuit welding of thin 2

sections, whereas the 50-50 combination works well on thicker sections. 2.4.7.1.3 It should be noted that shielding gases can affect the metallurgy of the weld metal. As an example, a combination of argon and carbon dioxide may be used for welding stainless

Lesson 10 Reliability of Welding Filler Metals

Se Ch (Fa Dow

steel, but as the carbon dioxide breaks down, excessive carbon may be transferred into the

© COPYRIGHT 1998 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON II weld metal. Corrosion resistance in stainless steel is reduced as the carbon content

Cu Ch Tab Con

increases. To counteract this possibility, a less reactive mixture of 90% helium - 7-1/2% argon

Lesson 2 Common Electric Arc Welding Processes

- 2-1/2% CO is sometimes chosen. This combination, known as a trimix, provides good arc 2

stability and wetting. 2.4.7.2

Spray Arc Transfer - Pure argon produces a deep constricted penetration at the

center of the bead with much shallower penetration at the edges (Figure 16). Argon performs

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

well on nonferrous metals, but when used on ferrous metals, the transfer is somewhat erratic with the tendency for the weld metal to move away from the center line. To make argon suit-

P

able for spray transfer on ferrous metals, small additions of 1 to 5% oxygen have proven to provide remarkable improvements. The arc stabilizes, becomes less spattery, and the weld

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

metal wets out nicely. If the percentage of argon falls below 80%, it is impossible to achieve

Glo

true spray transfer. 2.4.7.2.1 Pure helium or combinations of helium and argon are used for welding nonferrous metals. The bead profile will broaden as the concentration of helium increases.

Lesson 5 Welding Filler Metals for Stainless Steels

2.4.7.3

Pulse Spray Transfer - The selection of shielding gas must be adequate enough to

support a spray transfer. Material type, thickness, and welding position are essential variables in selecting a particular shielding gas. The following is a list of recommended gases:

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels 2.4.8 Lesson 8 Hardsurfacing Electrodes

Turn

Carbon Steel

Argon/CO /O /He (He less than 50%)

Alloy Steel

Argon/CO /O /He (He less than 50%)

Stainless

Argon/O /CO (CO max. 2%)

Copper, Nickel, & Cu-Ni Alloys

Argon/Helium

Aluminum

Argon/Helium

2

2

2

2

2

2

2

Se Ch (Fa Dow

Electrodes - The solid electrodes used in GMAW are of high purity when they come

from the mill. Their chemistry must be closely controlled and some types purposely contain high levels of deoxidizers for use with CO shielding. 2

2.4.8.1

The electrode manufacturer draws down the electrode to a finished diameter that,

with GMAW, is usually quite small. Diameters from .030" thru 1/16" are common.

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals

2.4.8.2

Most steel GMAW electrodes are copper plated as a means of protecting the

surface. The copper inhibits rusting, provides smooth feeding, and helps electrical conductivity. 2.4.8.3

Information on types and classifications will be covered in a future lesson.

© COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

LESSON II

2.5

FLUX CORED ARC WELDING

Flux Cored Arc Welding (FCAW) is quite similar to GMAW as far as operation and equipment are concerned. The major difference is that FCAW utilizes an electrode that is very different from the solid electrode used in GMAW. The flux cored electrode is a fabricated electrode and as the name implies, flux material is deposited into its core. The flux cored

Go T

electrode begins as a flat metal strip that is formed first into a "U" shape. Flux and alloying

Lesson 3 Covered Electrodes for Welding Mild Steels

elements are deposited into the "U" and then the shape is closed into a tubular configuration by a series of forming rolls. 2.5.0.1

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Cu Ch Tab Con

P

The flux cored electrode is a continuous electrode that is fed into the arc where it is

melted and transferred into the molten puddle. As in GMAW, the flux cored process depends

Glo

on a gas shield to protect the weld zone from detrimental atmospheric contamination. With FCAW, there are two primary ways this is accomplished (See Figure 18). The gas is either applied externally, in which case the electrode is referred to as a gas shielded flux cored electrode, or it is generated from the decomposition of gas forming ingredients contained in

Lesson 5 Welding Filler Metals for Stainless Steels

the electrode's core. In this instance, the electrode is known as a self-shielding flux cored electrode. In addition to the gas shield, the flux cored electrode produces a slag covering for

CONTACT TIP

CONTACT TIP

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

GAS CUP

INSULATED GUIDE TUBE

GAS SHIELD

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

FLUX CORE

FLUX CORE

Lesson 8 Hardsurfacing Electrodes

SELF SHIELDED

GAS SHIELDED FLUX-CORED ARC WELDING

FIGURE 18

Lesson 9 Estimating & Comparing Weld Metal Costs

further protection of the weld metal as it cools. The slag is manually removed with a wire brush or chipping hammer. 2.5.1

Lesson 10 Reliability of Welding Filler Metals

Turn

Self Shielded Process - The main advantage of the self shielding method is that

its operation is somewhat simplified because of the absence of external shielding equipment.

© COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II Although self shielding electrodes have been developed for welding low alloy and stainless

Cu Ch Tab Con

steels, they are most widely used on mild steels. The self shielding method generally uses a

Lesson 2 Common Electric Arc Welding Processes

long electrical stick-out (distance between the contact tube and the end of the unmelted electrode) commonly from one to four inches. Electrical resistance is increased with the long extension, preheating the electrode before it is fed into the arc. This enables the electrode to burn off at a faster rate and increases deposition. The preheating also decreases the heat

Lesson 3 Covered Electrodes for Welding Mild Steels

available for melting the base metal, resulting in a more shallow penetration than the gas

Go T

shielded process.

P 2.5.1.1

A major drawback of the self shielded process is the metallurgical quality of the

deposited weld metal. In addition to gaining its shielding ability from gas forming ingredients

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

in the core, the self shielded electrode contains a high level of deoxidizing and denitrifying

Glo

alloys, primarily aluminum, in its core. Although the aluminum performs well in neutralizing the affects of oxygen and nitrogen in the arc zone, its presence in the weld metal will reduce ductility and impact strength at low temperatures. For this reason, the self shielding method is

Lesson 5 Welding Filler Metals for Stainless Steels

usually restricted to less critical applications. 2.5.1.2

The self shielding electrodes are more suitable for welding in drafty locations than

the gas shielded types. Since the molten filler metal is on the outside of the flux, the gases

Turn

formed by the decomposing flux are not totally relied upon to shield the arc from the

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

atmosphere. The deoxidizing and denitrifying elements in the flux further help to neutralize the affects of nitrogen and oxygen present in the weld zone. 2.5.2

The Gas Shielded Process - A major advantage with the shielded flux cored

electrode is the protective envelope formed by the auxiliary gas shield around the molten

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

puddle. This envelope effectively excludes the natural gases in the atmosphere without the need for core ingredients such as aluminum. Because of this more thorough shielding, the weld metallurgy is cleaner which makes this process suitable for welding not only mild steels, but also low alloy steels in a wide range of strength and impact levels.

Lesson 8 Hardsurfacing Electrodes

2.5.2.1

The gas shielded method uses a shorter electrical stickout than the self shielded

process. Extensions from 1/2" to 3/4" are common on all diameters, and 3/4" to 1-1/2" on larger diameters. Higher welding currents are also used with this process, enabling high deposition rates to be reached. The auxiliary shielding helps to reduce the arc energy into a

Lesson 9 Estimating & Comparing Weld Metal Costs

columnar pattern. The combination of high currents and the action of the shielding gas contributes to the deep penetration inherent with this process. Both spray and globular transfer are utilized with the gas shielded process.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II

2.5.3

Current Density - Flux cored arc welding utilizes the same principles of current

Cu Ch Tab Con

density, as explained in section 2.4.1, but there is one significant difference between the flux

Lesson 2 Common Electric Arc Welding Processes

cored electrode and the solid electrode. With the flux cored electrode, the granular core ingredients are poor electrical conductors and therefore, the current is carried primarily through the outer metal sheathing. When an equal diameter cross section of the two are compared (See Figure

Lesson 3 Covered Electrodes for Welding Mild Steels

CURRENT PATH

19), it is seen that the flux cored electrode has

Go T

a smaller current carrying area than the solid

P

electrode. This greater concentration of current in a smaller area increases the burnoff rate.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Glo 2.5.3.1

When all other factors are equal,

the deposition rate of the flux cored electrode is somewhat higher than the

Lesson 5 Welding Filler Metals for Stainless Steels

1/16" FLUX-CORED ELECTRODE

solid electrode. 2.5.4

1/16" SOLID ELECTRODE FIGURE 19

EQUIPMENT - The equipment used for flux cored arc welding is the same as

shown previously in Section 2.3.2.2, Figure 12, with the exception that the self shielded

Turn

method does not need the external gas apparatus.

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

2.5.4.1

Flux cored arc welding is done with direct current. All of the gas shielded electrodes

are designed for DCEP operation. The self shielded electrodes are either designed specifically for DCEN or DCEP. 2.5.5

Power Source - The recommended power source is the direct current constant

voltage type. The constant current type can be used but with less satisfactory results. 2.5.6

Wire Feeder - The function of the wire feeder in FCAW is the same as discussed in

the section on GMAW. Since the flux cored electrode is tubular in construction, precautions

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

must be taken not to flatten the electrode. To facilitate feeding by means other than pressure alone, specially designed feed rolls with knurled or grooved surfaces are used. Some feeders use four feed rolls rather than two to minimize unit pressure on the electrode. 2.5.7

The Welding Gun - As compared to GMAW, the main difference in FCAW welding

guns is in those used with the self shielding process. The gun is somewhat more compact due to the absence of an external gas shielding nozzle. Since the self shielding process normally requires a longer electrode extension, the self shielding gun may have an insulated guide tube (Refer back to Figure 18) to give stability to the electrode. Water cooled guns are available for

Lesson 10 Reliability of Welding Filler Metals

high duty semi-automatic welding and for automatic welding.

© COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II 2.5.7.1

Flux cored welding generates fumes, that for environmental reasons, must be

Cu Ch Tab Con

removed from the welding area. This is usually done with an external exhaust system, but

Lesson 2 Common Electric Arc Welding Processes

welding guns with internal fume extractors have been developed. They are heavier than the regular gun and must be properly maintained so that the extracting mechanism does not disturb the shielding gas.

2.5.8 Lesson 3 Covered Electrodes for Welding Mild Steels

Lesson 5 Welding Filler Metals for Stainless Steels

P

and 25% CO . 2

A carbon dioxide shield produces deep penetration and the transfer is globular. As

previously discussed, CO will dissociate in the heat of the arc. To counteract this 2

Glo

characteristic, deoxidizing elements are added to the core ingredients of the electrode. The deoxidizers react to form solid oxide compounds that float to the surface as part of the slag covering. 2.5.8.2

The addition of Argon to CO will increase the wetting action, produce a smooth arc 2

arc, and reduce spatter. The transfer is spray-like, and the penetration is somewhat less than with the straight carbon dioxide. 2.5.8.3

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Go T

shielding of the flux cored electrode. The other commonly used gas is a mixture of 75% Argon

2.5.8.1

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

SHIELDING GASES - Carbon dioxide is the most widely used gas for auxiliary

Turn

While some flux cored electrodes are designed to operate well on both the 100%

CO or the 75/25 mixture, others are formulated specifically for the CO shield or the Argon/ 2

2

CO mixture. If the recommended gas is not used with these electrodes, the weld chemistry 2

may be affected. The reason for this is that inert gas, such as Argon, does not react with the other elements; therefore, allowing them to be transferred across the arc into the weld metal.

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Se Ch (Fa Dow

An electrode designed for CO shielding contains deoxidizing elements, such as silicon and 2

manganese. If a high percentage of Argon is used in the shielding medium, a large portion of these elements may pass into the weld metal causing the weld metallurgy to be less ductile than intended.

Lesson 8 Hardsurfacing Electrodes

2.5.8.3

The opposite happens with electrodes formulated for a 75/25 mixture. These

electrodes are usually designed for high yield and tensile strength. If a high percentage of CO

2

is used with them, the CO may react with the elements needed to attain these strength levels, 2

thereby preventing them from passing into the weld metal.

Lesson 9 Estimating & Comparing Weld Metal Costs

2.6

SUBMERGED ARC WELDING

Submerged Arc Welding (SAW) is different from the previously explained arc welding processes in that the arc is not visible. The arc is submerged beneath loose granular flux. A

Lesson 10 Reliability of Welding Filler Metals

continuous electrode is fed by automatic drive rolls through an electrode holder where current

© COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II

is picked up at the contact tube. The electrode moves into the loose flux and the arc is

Cu Ch Tab Con

initiated. The flux is deposited from a separate container that moves at the same pace as the

Lesson 2 Common Electric Arc Welding Processes

electrode assuring complete coverage (See Figure 20). 2.6.1

Submerged Arc Flux - The flux helps form the molten puddle, slows the cooling

rate, and acts as a protective shield. The flux, which is in close contact with the arc, is fused into a slag cover and that which is not fused is collected for reuse. The flux can contain alloying

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

elements that, when molten, will pass into the weld metal affecting the metallurgy. Some fluxes are specifically prepared for their alloy altering capabilities while others, known as neutral

P

fluxes, are chosen when a minimal alloy change is desired. Although these latter fluxes are called "neutral", they still have the ability to slightly alter the weld chemistry.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Glo FLUX HOPPER

Lesson 5 Welding Filler Metals for Stainless Steels

LOOSE GRANULAR FLUX

ELECTRODE

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

BASE METAL

MOLTEN PUDDLE FUSED SLAG COVER SOLIDIFIED WELD METAL SUBMERGED ARC WELDING FIGURE 20

2.6.2

The Welding Gun - Although there are hand-held welding guns for the submerged

arc process, the majority of SAW is done with fully automatic equipment. The basic compo-

Lesson 8 Hardsurfacing Electrodes

nents include a wire feeder, a power source, a flux delivery system, and in some instances, an automatic flux recovery system. 2.6.3

Lesson 9 Estimating & Comparing Weld Metal Costs

may be a DC rectifier or generator of either the constant current or constant voltage variety. The power source must be rated for high current output. When current requirements exceed the value of a single machine, two or more of the same type may be connected in parallel. 2.6.4

Lesson 10 Reliability of Welding Filler Metals

Power Sources - The power source can be a constant current AC transformer, or it

Equipment - Most submerged arc welding is done with DCEP because it provides

easy arc starting, deep penetration and excellent bead shape. DCEN provides the highest

© COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II deposition rates but minimum penetration. Alternating current is often used as a trailing arc in

Cu Ch Tab Con

tandem arc applications. In this type of application, the leading DCEP arc provides deep

Lesson 2 Common Electric Arc Welding Processes

penetration, and the closely trailing AC arc provides high deposition with a minimum of arc blow. 2.6.5

Electrodes - A variety of ferrous and nonferrous electrodes are used in submerged

arc welding. They are usually solid electrodes refined with the appropriate alloys at the steel

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

mill, and then shipped to electrode manufacturers where they are drawn down to a specific diameter and packaged. There is another type of sub arc electrode known as a composite

P

electrode, that is fabricated in the same manner as a flux cored electrode. A chief advantage of this type is that the alloying elements can be added to the core of the electrode more

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

cheaply than a steel mill can produce those same alloys in a solid form. The electrodes for widely used. 2.6.6

Lesson 5 Welding Filler Metals for Stainless Steels

Summary - Submerged arc welding has some advantages over other welding

processes. Since the radiance of the arc is blanketed by the loose flux, there is no need for a protective welding hood (although safety glasses are recommended), there is no spatter and only a very minimal amount of fumes escape from under the blanket. High welding currents, quite commonly in the 300 to 1600 ampere range, are used. These high currents, combined

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

applications that require a series of repetitious welds. Some setups allow two or more electrodes to be fed simultaneously into the joint, further increasing the deposition rate and speed. Although SAW has these advantages, it does have some limitations. The flux must

be deposited and collected for every welding pass. This requires additional equipment and handling. Also because of the loose flux, the process is limited to the flat and horizontal positions. The equipment for SAW is commonly quite bulky which limits its mobility, and although the process works well on thick materials, it usually is not satisfactory for thin gauge

Lesson 8 Hardsurfacing Electrodes

Turn

with fast travel speeds, make SAW a high deposition process that is especially suitable for

2.6.6.1

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Glo

SAW vary in diameter from 1/16 inch to 1/4 inch with the larger diameters being the most

material. The process requires care in the operation. The amperages commonly used may cause excessive heat buildup in the base metal, that may result in distortion or brittleness.

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels

LESSON II

2.7

ELECTROSLAG AND ELECTROGAS WELDING

Cu Ch Tab Con

Electroslag Welding (ESW) and Electrogas Welding (EGW) comprise only a minor portion of all welding done in the country, but they are uniquely adapted to certain applications, primarily the joining of very thick materials. The joining of a 12 inch material along a 40 foot line is not an uncommon application for the Electroslag process. Electroslag Welding (See Figure 21) is technically not an arc welding process,

2.7.1

although it utilizes a current carrying consumable electrode. The only time there is an arc

Go T

P

between the electrode and the work piece is when current is initially charged through the electrode. This initial charge heats a layer of loose flux that becomes molten and extinguishes

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

the arc.

Glo WATER INLET/OUTLET ELECTRODE COPPER SHOE

Lesson 5 Welding Filler Metals for Stainless Steels

GUIDE TUBE (CONSUMABLE GUIDE METHOD) BASE METAL

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

MOLTEN FLUX

WELD POOL

SOLIDIFIED METAL

ELECTROSLAG WELDING

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Se Ch (Fa Dow

FIGURE 21

2.7.2

Flux - The flux used in ESW is high in electrical resistance. As current is applied,

enough heat is generated from this resistance to keep the flux, base metal, and electrode in a

Lesson 8 Hardsurfacing Electrodes

molten state. This axis of the weld joint is on a vertical plane. The two pieces of metal, usually of the same thickness, are positioned so that there is an opening between them. One or more electrodes are fed into the opening through a welding bead that travels vertically as the joint is filled. To contain the molten puddle, water cooled copper shoes or dams are placed on the

Lesson 9 Estimating & Comparing Weld Metal Costs

sides of the vertical cavity. As the weld joint solidifies, the dams move vertically so as to always remain in contact with the molten puddle. 2.7.3

Process - A variation of ESW is the consumable guide method. The process is the

same with this method except that the guide tube that feeds the electrode to the molten pool is

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II also consumed. The chief advantage with this method is the elimination of the electrode

Cu Ch Tab Con

holder which must move vertically with the weld pool. Also since the guide tube is consumed,

Lesson 2 Common Electric Arc Welding Processes

the deposition rate is slightly increased with this method. 2.7.4

Equipment - The equipment used in ESW is all automatic and of special design.

The power source may use either AC or DC current. The electrode may be either solid or flux cored, although if the flux cored is used, it must be specially formulated so as not to contain its

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

normal amount of slag forming ingredients. 2.7.5

Summary - Electrogas Welding is similar to ESW as far as the mechanical as-

P

pects are concerned. The equipment is automatic, the welding head travels vertically, and the

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

molten puddle is retained by shoes on the sides of the joint. The difference is that Electrogas Welding utilizes an arc and it is externally gas shielded. The power source is also limited to

Glo

DC operation. The electrodes used in EGW can be either solid or flux cored.

Lesson 5 Welding Filler Metals for Stainless Steels

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Se Ch (Fa Dow

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Se Doc (Sl Dow

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON II

APPENDIX A

Lesson 2 Common Electric Arc Welding Processes

LESSON II - GLOSSARY OF TERMS

Arc Blow

Lesson 3 Covered Electrodes for Welding Mild Steels

Lesson 5 Welding Filler Metals for Stainless Steels

- Deviation of the direction of the welding arc caused by magnetic fields in the

Go T

work piece when welding with direct current.

P Straight Polarity

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Cu Ch Tab Con

- Welding condition when the electrode is connected to the negative terminal and the work is connected to the positive terminal of the welding power source.

Glo Reverse Polarity

- Welding condition when the electrode is connected to the positive terminal and the work is connected to the negative terminal of the welding power source.

Slag

- The brittle mass that forms over the weld bead on welds made with coated electrodes, flux cored electrodes, submerged arc welding and other slag producing welding processes. Welds made with the gas metal arc and the

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

gas tungsten arc welding processes are slag free.

Manual Arc Welding

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Semi-Automatic Welding

- Welding with a coated electrode where the operator's hand controls travel speed and the rate the electrode is fed into the arc.

- Welding with a continuous solid wire or flux cored electrode where the wire feed speed, shielding gas flow rate, and voltage are preset on the equipment, and the operator guides the hand held welding gun along the joint to be

Lesson 8 Hardsurfacing Electrodes

welded.

Slag

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

Inclusion

Root Pass

- A weld defect where slag is entrapped in the weld metal before it can float to the surface. - The initial pass in a multi-pass weld, usually requiring 100% penetration.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II Gas Ions

- Shielding gas atoms that, in the presence of an electrical current, lose one or

Cu Ch Tab Con

more electrons and therefore, carry a positive electrical charge. The provide

Lesson 2 Common Electric Arc Welding Processes

a more electrically conductive path for the arc between the electrode and the work piece. High Frequency

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

- (as applied to gas-tungsten arc welding) An alternating current consisting of over 50,000 cycles per second at high

P

voltage, low amperage that is superimposed on the welding circuit in GTAW power sources. It ionizes a path for non-touch arc starting and stabilizes the

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

arc when welding with alternating current.

Glo Inert Gases

- Gases that are chemically inactive. They do not readily combine with other elements.

Flux

Lesson 5 Welding Filler Metals for Stainless Steels

- In arc welding, fluxes are formulations that, when subjected to the arc, act as a cleaning agent by dissolving oxides, releasing trapped gases and slag and generally cleaning the weld metal by floating the impurities to the surface where they solidify in the slag covering. The flux also serves to reduce spatter and contributes to weld bead shape. The flux may be the coating on the

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Turn

electrode, inside the electrode as in flux cored types, or in a granular form as used in submerged arc welding. Current

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Density

- The amperes per square inch of cross-sectional area of an electrode. High current density results in high electrode melt-off rate and a concentrated, deep penetrating arc.

Slope or Slope

Lesson 8 Hardsurfacing Electrodes

Control

welding. Slope Control reduces the short circuiting current each time the electrode touches the weld puddle (See Section 2.5.3). Inductance

Lesson 9 Estimating & Comparing Weld Metal Costs

- A necessary feature in welding power sources used for short circuiting arc

- (as applies to short circuiting arc welding) A feature in welding power sources designed for short circuiting arc welding to retard the rate of current rise each time the electrode touches the weld puddle.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II

Contact Tip

Cu Ch Tab Con

- That part of a gas metal arc welding gun or flux cored arc welding gun that transfers the welding current to the welding wire immediately before the wire

Lesson 2 Common Electric Arc Welding Processes

enters the arc.

Spray

Lesson 3 Covered Electrodes for Welding Mild Steels

Transfer

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Globular

- Mode of metal transfer across the arc where the molten metal droplets are smaller than the electrode diameter and are axially directed to the weld puddle.

Go T

Requires high voltage and amperage settings and a shielding gas of at least

P

80% argon.

Transfer

- Mode of metal transfer across the arc where a molten ball larger than the

Glo

electrode diameter forms at the tip of the electrode. On detachment, it takes on an irregular shape and tumbles towards the weld puddle sometimes shorting between the electrode and work at irregular intervals. Occurs when using shielding gases other than those consisting of at least 80% argon and

Lesson 5 Welding Filler Metals for Stainless Steels

at medium current settings.

Pulse

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Transfer

- Mode of metal transfer somewhat between spray and short circuiting. The

Turn

specific power source has built into it two output levels: a steady background level, and a high output (peak) level. The later permits the transfer of metal across the arc. This peak output is controllable between high and low values up to several hundred cycles per second. The result of such a peak output

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

produces a spray arc below the typical transition current.

Shortcircuiting Transfer

Lesson 8 Hardsurfacing Electrodes

Transfer takes place each time the electrode touches or short-circuits to the weld puddle, extinguishing the arc. The short-circuiting current causes the electrode to neck down, melt off, and then repeats the cycle.

Trimix or

Lesson 9 Estimating & Comparing Weld Metal Costs

- Mode of metal transfer in gas metal arc welding at low voltage and amperage.

Triple Mix

- A shielding gas consisting of approximately 90% helium, 7-1/2% argon, and 2-1/2% carbon dioxide used primarily for short-circuiting arc welding of stainless steels. Maintains corrosion resistance of the stainless steel and produces good wetting and excellent weld bead shape.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON II

Electrical

Lesson 2 Common Electric Arc Welding Processes

Cu Ch Tab Con

- In any welding process using a solid or flux cored wire, the electrical stick-out is the distance from the contact tip to the unmelted electrode end. Sometimes

Stick-Out

called the "amount of wire in resistance". This distance influences melt-off rate, penetration, and weld bead shape.

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

Out-of-Position

Weld

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

- Welds made in positions other than flat or horizontal fillets.

Welds

P

-

Glo

Positions FLAT

HORIZONTAL FILLET

Lesson 5 Welding Filler Metals for Stainless Steels

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

VERTICAL

OVERHEAD

Se Ch (Fa Dow

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

HORIZONTAL BUTT

Se Doc (Sl Dow

POSITIONED FILLET (FLAT)

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Cu Ch Tab Con

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

BASIC WELDING FILLER METAL TECHNOLOGY A Correspondence Course

LESSON III COVERED ELECTRODES FOR WELDING MILD STEELS An Introduction to Mild Steel Covered Electrodes

Go T

P

Glo

Turn

Se Ch (Fa Dow

Se Doc (Sl Dow

ESAB

ESAB Welding & Cutting Products

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals ©COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

Cu Ch Tab Con

TABLE OF CONTENTS LESSON III COVERED ELECTRODES FOR WELDING MILD STEELS

Lesson 2 Common Electric Arc Welding Processes

Go T Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Section Nr.

Lesson 9 Estimating & Comparing Weld Metal Costs

Page

3.1

DEVELOPMENT OF COVERED ELECTRODES.............................

1

3.2

MANUFACTURING COVERED EELCTRODES ..............................

1

3.2.1

Functions of Electrode Coatings .......................................................

3

3.2.2

Classification of Coating Ingredients ................................................

4

3.3

AWS SPECIFICATION A5.1-91 ........................................................

6

3.3.1

Chemical Composition of Weld Metal ...............................................

7

3.3.2

Mechanical Properties (AWS A5.1-91) .............................................

7

3.3.3

Individual Electrode Characteristics ..................................................

8

3.4

SELECTING THE PROPER MILD STEEL ELECTRODE ................

11

3.4.1

Typical Electrode Use by Welding Classification ..............................

12

3.4.2

Electrode Deposition.........................................................................

14

3.5

ACID AND BASIC SLAG SYSTEMS ................................................

15

3.6

ADVANTAGES AND DISADVANTAGES OF MILD STEEL COVERED ELECTRODES...............................................................

3.7

Lesson 8 Hardsurfacing Electrodes

Section Title

15

ESAB SUREWELD MILD STEEL COVERED ELECTRODES FEATURES & DATA..........................................................................

16

3.7.1

SUREWELD 10P (AWS E6010) .......................................................

16

3.7.2

SUREWELD 710P (AWS E7010-P1) ...............................................

17

3.7.3

SUREWELD 810P (AWS E8010-P1) ...............................................

18

3.7.4

SUREWELD SW14 (AWS E6011)....................................................

19

3.7.5

SUREWELD SW612 (AWS E6012) .................................................

20

3.7.6

SUREWELD SW15 (AWS E6013) ....................................................

21

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

P

Glo

Turn

Se Ch (Fa Dow

Se Doc (Sl Dow

Cu Ch Tab Con

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

TABLE OF CONTENTS LESSON III - Con't

Go T Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Section Nr.

Section Title

Page

3.7.7

6013LV (AWS E6013) .......................................................................

21

3.7.8

SUREWELD SW15-IP (AWS E7014) ................................................

22

3.7.9

SUREWELD 70LA-2 (AWS E7016) .................................................

23

3.7.10

ATOM ARC 7018 (AWS E7018) ........................................................

24

3.7.11

ATOM ARC 7018AC (AWS E7018)...................................................

25

3.7.12

SUREWELD 7024 (AWS E7024) Conforms to 7024-1 .....................

26

Appendix A

GLOSSARY OF TERMS...................................................................

27

P

Glo

Turn

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Se Ch (Fa Dow

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Se Doc (Sl Dow

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Cu Ch Tab Con

LESSON III

3.1

Development of Covered Electrodes

During the 1890's, arc welding was accomplished with bare metal electrodes. The welds produced were porous and brittle because the molten weld puddle absorbed larg quantities of oxygen and nitrogen from the atmosphere. Operators noticed that a rusty rod produced a better weld than a shiny clean rod. Observations also showed than an improved weld could be made by wrapping the rod in newspaper or by welding adjacent to a pine board placed close to and parallel with the weld being made. In these cases, some degree of shielding the arc form the atmosphere was being accomplished. These early observations led to the development of the coated electrode.

Go T

P 3.1.0.1 Around 1920, the A.O. Smith Corporation developed an electrode spirally wrapped with paper, soaked in sodium silicate, and then baked. This was the first of the cellulosic type electrodes. It produced an effective gas shield in the area and greatly improved the ductility of the weld metal.

Glo

3.1.0.2 Because of the method used to manufacture these paper covered electrodes, it was difficult to effectively add other ingredients to the coating. In 1924, the A.O. Smith Corporation began work on coatings that could be extruded over the core wire. This method allowed the addition of other flux ingredients to furhter improve or modify the weld metal and by 1927, these electrodes were being produced commercially. 3.1.0.3 Since 1927, many improvements have been made and many different types of electrodes have been developed and produced. Through variations in the formulations of the covering and the amount of covering on the mild steel core wire, many different classifications of electrodes are produced today.

3.2

Turn

Manufacturing Covered Electrodes

Mild steel covered electrodes, also commonly called coated electrodes, consist of only two major elements; the core wire or rod and the flux covering. The core wire is usually low carbon steel. It must contain only small amounts of aluminum and copper, and the sulfur and phosphorous levels must be kept very low since they can cause undesirable brittleness in the weld metal. The raw material for the core wire is hot-rolled rod (commonly called "hot rod"). It is

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

Cu Ch Tab Con

LESSON III received in large coils, cleaned, drawn down to the proper electrode diameter, straightened, and cut to the proper electrode length.

Lesson 2 Common Electric Arc Welding Processes

3.2.0.1

The coating ingredients, from which there are literally hundreds to choose, are

carefully weighed, blended in a dry state, wet mixed, and compacted into a large cylinder that fits into the extrusion press. The coating is extruded over the cut core wires which are fed

Go T

through the extrusion press at a rapid rate. The coating material is removed from the end of

Lesson 3 Covered Electrodes for Welding Mild Steels

the electrode that is clamped into the electrode holder to assure electrical contact, and also

3.2.0.2

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

P

from the welding end of the electrode to assure easy arc initiation. The electrodes are then stamped with the type number for easy identification before

entering the ovens, where they go through a controlled bake cycle to insure the proper mois-

Glo

ture content before packaging. 3.2.0.3

Of the many quality control checks made during the manufacturing process, one of

the most important is the procedure that insures that the coating thickness is uniform. In

Lesson 5 Welding Filler Metals for Stainless Steels

shielded metal arc welding, the coating crater, or the cup-like formation of the coating, that extends beyond the melting core wire, performs the function of concentrating and directing the arc. See Figure 1. A

Turn

B

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

CONCENTRIC COATING

NON-CONCENTRIC COATING

GOOD ARC DIRECTION

POOR ARC DIRECTION

CONCENTRATED ARCEFFECT OF COATING CONCENTRICITY

FIGURE 1

3.2.0.4

Concentration and direction of the arc stream is attained by having a coating crater,

somewhat similar to the nozzle on a water hoze, directing the flow of weld metal. When the coating is not concentric to the core wire, it can cause the condition shown at B in Figure 1. The poor arc direction causes inconsistent weld beads, poor shielding, and lack of penetration. The electrode burns off unevenly, leaving a projection on the side where the coating is the

Lesson 10 Reliability of Welding Filler Metals

heaviest. This condition is often referred to as "fingernailing."

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON III 3.2.1

Functions of Electrode Coatings - The ingredients that are commonly used in

Cu Ch Tab Con

coatings can be classified physically in a broad manner as liquids and solids. The liquids are

Lesson 2 Common Electric Arc Welding Processes

generally sodium silicate or potassium silicate. The solids are powdered or granulated materials that may be found free in nature, and need only concentration and grinding to the proper particle size. Other solid materials used are produced as a result of chemical reactions, such as alloys or other complex synthetic compounds.

Lesson 3 Covered Electrodes for Welding Mild Steels

3.2.1.1

The particle size of the solid material is an important factor. Particle size may be as

P

coarse as fine sand, or as minute as sub-sieve size. 3.2.1.2

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Go T

The physical structure of the coating ingredients may be classified as crystalline,

fibrous or amorphous (non-crystalline). Crystalline materials such as rutile, quartz and mica are commonly used. Rutile is the naturally occurring form of the mineral titanium dioxide and

Glo

is widely used in electrode coatings. Fibrous materials such as wood fibers, and non-crystalline materials such as glasses and other organic compounds are also common coating ingredients.

Lesson 5 Welding Filler Metals for Stainless Steels

3.2.1.3

The functions of the coating on covered electrodes are as follows: a)

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Shielding of the Weld Metal - The most important function of a coating is to

shield the weld metal from the oxygen and nitrogen of the air as it is being transferred across

Turn

the arc, and while it is in the molten state. This shielding is necessary to ensure the weld metal will be sound, free of gas pockets, and have the right strength and ductility. At the high temperatures of the arc, nitrogen and oxygen combine readily with iron to form iron nitrides and iron oxides that, if present in the weld metal above certain minimum amounts, will cause brittle-

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

ness and porosity. Nitrogen is the primary concern since it is difficult to control its effect once it has entered the deposit. Oxygen can be counteracted by the use of suitable deoxidizers. In order to avoid contamination from the air, the stream of molten metal must be protected or shielded by gases that exclude the surrounding atmosphere from the arc and the molten weld metal. This is accomplished by using gas-forming materials in the coating that break down

Lesson 8 Hardsurfacing Electrodes

during the welding operation and produce the gaseous shield. b)

Stabilization of the Arc - A stabilized arc is one that starts easily, burns

smoothly even at low amperages, and can be maintained using either a long or a short arc

Lesson 9 Estimating & Comparing Weld Metal Costs

length. c) Alloying Additions to Weld Metal - A variety of elements such as chromium, nickel, molybdenum, vanadium and copper can be added to the weld metal by including them in the coating composition. It is often necessary to add alloys to the coating to balance the

Lesson 10 Reliability of Welding Filler Metals

expected loss of alloys of the core wire during the welding operation, due to volatization and

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON III

chemical reaction. Mild steel electrodes require small amounts of carbon, manganese and

Cu Ch Tab Con

silicon in the deposit to give sound welds of the desired strength level. A portion of the carbon

Lesson 2 Common Electric Arc Welding Processes

and manganese is derived from the core wire, but it is necessary to supplement it with ferromanganese and in some cases ferrosilicon additions in the coating. d) Concentration of the Arc Stream - Concentration or direction of the arc stream is attained by having a coating crater form at the tip of the electrodes as discussed

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

earlier. Use of the proper binders assures a good hard coating that will maintain a crater and

P

give added penetration and better direction to the arc stream. e) Furnish Slag for Fluxing - The function of the slag is (1) to provide additional

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

protection against atmospheric contamination, (2) to act as a cleaner and absorb impurities that are floated off and trapped by the slag, (3) to slow the cooling rate of the molten metal to allow the escape of gases. The slag also controls the contour, uniformity and general appearance of the weld. This is particularly true in fillet welds. f)

Characteristics for Welding Position - It is the addition of certain ingredients,

primarily titanium compounds, in the coating that makes it possible to weld out-of-position , vertically, and overhead. Slag characteristics, primarily surface tension and freezing point, determine to a large degree the ability of an electrode to be used for out-of-position work.

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Glo

Turn

g) Control of Weld Metal Soundness - Porosity or gas pockets in weld metal can be controlled to a large extent by the coating composition. It is the balance of certain ingredients in the coating that have a marked effect on the presence of gas pockets in the weld metal. The proper balance of these is critical to the soundness that can be produced.

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Ferromanganese is probably the most common ingredient used to attain the correctly balanced formula. h) Specific Mechanical Properties to the Weld Metal - Specific mechanical properties can be incorporated into the weld metal by means of the coating. High impact

Lesson 8 Hardsurfacing Electrodes

values at low temperature, high ductility, and increases in yield and tensile properties can be attained by alloy additions to the coating. i)

Lesson 9 Estimating & Comparing Weld Metal Costs

Insulation of the Core Wire - The coating acts as an insulator so that the core

wire will not short-circuit when welding in deep grooves or narrow openings; coatings also serve as a protection to the operator when changing electrodes. 3.2.2

Classification of Coating Ingredients - Coating materials can be classified into

the following 6 major groups:

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON III

a) Alloying Elements - Alloying elements such as molybdenum, chromium, nickel,

Cu Ch Tab Con

manganese and others impart specific mechanical properties to the weld metal.

Lesson 2 Common Electric Arc Welding Processes

b) Binders - Soluble silicates such as sodium and potassium silicates, are used in the electrode coating as binders. Functions of binders are to form a plastic mass of coating material capable of being extruded and baked. The final baked coating should be hard so that it will maintain a crater and have sufficient strength so that it will not spall, crack or chip. Bind-

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

ers are also used to make coating non-flammable and avoid premature decomposition.

P c) Gas Formers - Common gas forming materials used are the carbohydrates, hydrates, and carbonates. Examples would be cellulose (such as wood flock), the carbonates

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

of calcium and magnesium, and chemically combined water as is found in clay and mica. These materials evolve carbon dioxide (CO ), carbon monoxide (CO), and water vapor (H O) 2

Glo

2

at the high temperature of the welding arc. Free moisture is another gas-forming ingredient that is found particularly in cellulosic type electrodes and is a part of the formulation in amounts of 2%-3%. It has a marked influence on the arc and is a necessary ingredient in the E6010

Lesson 5 Welding Filler Metals for Stainless Steels

type electrode. d) Arc Stabilizers - Air is not sufficiently conductive to maintain a stable arc, so it becomes necessary to add coating ingredients that will provide a conductive path for the flow

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Turn

of current. This is particularly true when welding with alternating current. Stabilizing materials are titanium compounds, potassium compounds, and calcium compounds. e) Fluxes and Slag Formers - These ingredients are used primarily to give body to the slag and impart such properties as slag viscosity, surface tension, and melting point.

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Silica and magnetite are materials of this type. f)

Plasticizers - Coatings are often very granular or sandy, and in order to suc-

cessfully extrude these coatings, it is necessary to add lubricating materials, plasticizers, to make the coating flow smoothly under pressure. Sodium and potassium carbonates are often

Lesson 8 Hardsurfacing Electrodes

used. 3.2.2.1

The chart in Figure 2 shows typical coating constituents and their functions for two

types of mild steel electrodes. Note that the moisture content in the cellulosic E6010 is much

Lesson 9 Estimating & Comparing Weld Metal Costs

higher than in the low hydrogen E7018 type. The moisture in the E6010 coating is necessary to produce the driving arc characteristic and is not harmful when welding the lower strength steels. Hydrogen can cause problems when welding the higher strength steels and will be discussed in detail in Lesson IV.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON III Class

Lesson 2 Common Electric Arc Welding Processes

E6010

Composition Cellulose (C6H10 O5)

35%

Gas Former

40% H2

15%

Slag Former - Arc Stabilizer

40% CO + CO2

Deoxidizer - Alloying

20% H2O

Ferromanganese

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

5%

Talc

15%

Slag Former

Sodium Silicate

25%

Binder - Fluxing Agent

Go T

5%

Calcium Carbonate

30%

Gas Former - Fluxing Agent

Fluorspar (CaF2)

20%

Slag Former - Fluxing Agent

Ferromanganese E7018

Shielding

Rutile (TiO2)

Moisture

Lesson 3 Covered Electrodes for Welding Mild Steels

Function

P

Deoxidizer - Alloying

80% CO

Potassium Silicate

15%

Binder - Arc Stabilizer

20% CO2

Iron Powder

30%

Deposition Stabilizer

Moisture

5%

Cu Ch Tab Con

Glo

0.1%

COMPOSITION AND FUNCTION OF ELECTRODE COATING CONSTITUENTS

Lesson 5 Welding Filler Metals for Stainless Steels

FIGURE 2

3.3

AWS SPECIFICATION A5.1-91

This American Welding Society (AWS) specification has been developed over the years by a

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

ESAB, users from the welding industry, and independent members from colleges, universities and independent laboratories. This balanced membership is required to prevent prejudice from entering into the specifications. 3.3.0.1

Individual Mild Steel electrodes are classified by the manufacturer according to the

above specification on the basis of the mechanical properties (also called physical properties) of the weld metal, the type of covering, the welding position of the electrode, and the type of current (AC or DC). The classification system is designed to give certain information about

Lesson 8 Hardsurfacing Electrodes

the electrode and the weld metal produced from it. The significance of the AWS designations are shown in tabular form in Figure 3. 3.3.0.2

These classifications, with the AWS Specification A5.1-91, are assigned by the

manufacturer of the electrodes according to the results of his own tests. The American Weld-

Lesson 9 Estimating & Comparing Weld Metal Costs

ing Society does not approve or disapprove electrodes. 3.3.0.3

The American Society of Mechanical Engineers (ASME) uses the AWS Electrode

Specifications word for word by adding the letters SF before the specification number. Thus, AWS Specification A5.1-91 becomes ASME Specification SFA5.1. The classification and

Lesson 10 Reliability of Welding Filler Metals

Turn

filler metals committee, composed of members who represent electrode producers, such as

requirements are the same.

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON III MILD STEEL COVERED ELECTRODES EXAMPLE:

Lesson 2 Common Electric Arc Welding Processes

1. 2.

E (1)

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

EXX10 EXXX1 EXXX2 EXXX3 EXXX4 EXXX5 EXXX6 EXXX8 EXX20 EXX22 EXX24 EXX27 EXX28 EXX48

3.

0 (3)

(4)

Current DCEP AC or DCEP AC or DCEN AC or DCEN AC or DCEN DCEP AC or DCEP AC or DCEP AC or DCEN AC or DCEN AC or DCEN AC or DCEN AC or DCEP AC or DCEP

or DCEP or DCEP

or DCEP or DCEP or DCEP

Third digit refers to welding position. 4. EXX1X All position (flat, horizontal, vertical, overhead). EXX2X Horizontal and flat only. EXX3X Flat position only. EXX4X Flat, overhead, horizontal, vertical down. Arc

Penetration

Digging Digging Medium Soft Soft Medium Medium Medium Medium Medium Soft Medium Medium Medium

Deep Deep Medium Light Light Medium Medium Medium Medium Medium Light Medium Medium Medium

DCEP — Direct Current Electrode Positive DCEN — Direct Current Electrode Negative

Lesson 5 Welding Filler Metals for Stainless Steels

Last digit indicates usability of the electrode, i.e. type of current and the type of covering. In some cases, both the third and fourth digits are significant.

Covering & Slag

Iron Powder

Cellulose - sodium Cellulose - potassium Titania - sodium Titania - potassium Titania - iron powder Low hyd. - sodium Low hyd. - potassium Low hyd. - iron powder Iron oxide - sodium Iron oxide - sodium Titania - iron powder Iron oxide- iron powder Low hyd. - iron powder Low hyd. - iron powder

0- 10% 0 0-10% 0- 10% 25-40% 0 0 25-40% 0 0 50% 50% 50% 25-40%

Glo

Note: Iron powder percentage based on weight of the covering.

Chemical Composition of Weld Metal (AWS A5.1-91) - Chemical requirements

Turn

are as follows: a)

Classifications E6010, E6011, E6012, E6013, E6020, E6022 and E6027 have no requirements.

b)

Classification E7018 and E7027 must have no more than 1.60% Manganese, 0.75% Silicon, 0.30% Nickel, 0.20% Chromium, 0.30% Molybdenum, and 0.08% Vanadium.

Lesson 8 Hardsurfacing Electrodes

have no more than 1.25% Manganese, 0.90% Silicon, 0.30% Nickel, 0.20% Chromium, 0.30% Molybdenum, and 0.08% Vanadium. 3.3.2

Se Ch (Fa Dow

Se Doc (Sl Dow

c) Classifications E7014, E7015, E7016, E7024, E7028 and E7048 must

Mechanical Properties (AWS A5.1-91) - Physical tests are performed on all

specimens in the "as-welded" condition. This means that the weldment or weld metal is not subjected to any type of heat treatment. Tensile test specimens for all electrode classifications other than the low hydrogen types (E7015, E7016, E7018, E7028 and E7048) are aged at 200°F to 220°F for forty-eight (48) hours prior to being subjected to the tensile test. This is not considered heat treatment. It simply accelerates the diffusion of hydrogen from the weld metal

Lesson 10 Reliability of Welding Filler Metals

P

FIGURE 3

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 9 Estimating & Comparing Weld Metal Costs

Go T

ELECTRODE CLASSIFICATION

3.3.1

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

1

E — Stands for electrode. Two digits indicate tensile strength x 1000 PSI.

Classification

Lesson 3 Covered Electrodes for Welding Mild Steels

60 (2)

Cu Ch Tab Con

welded with the cellulosic or titania type of electrodes.

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON III 3.3.2.1

Classifications E6010, E6011 and E6027 weld metals are required to have more

Cu Ch Tab Con

than 62,000 psi tensile strength, 50,000 psi yield strength, 22% elongation in two inch gauge,

Lesson 2 Common Electric Arc Welding Processes

and 20 ft-lb at -20°F Charpy V-notch impact. 3.3.2.2

Classification E6020 weld metals are required to have more than 62,000 psi

tensile strength, 50,000 psi yield strength, 22% elongation in two inch gauge, and no Charpy

Go T

V-notch impact requirements.

Lesson 3 Covered Electrodes for Welding Mild Steels

3.3.2.3

Classifications E6012 and E6013 weld metals are required to have more than

P

67,000 psi tensile strength, 55,000 psi yield strength, 17% elongation in two inch gauge, and no Charpy V-notch impact requirements.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

3.3.2.4

Classifications E7014 and E7024 weld metals are required to have more than

72,000 psi tensile strength, 60,000 psi yield strength, 17% elongation in two inch gauge, and no Charpy V-notch impact requirements. 3.3.2.6

Classifications E7015, E7016, E7018, D7027 and E7048 are required to have

more than 72,000 psi tensile strength, 60,000 psi yield strength, 22% elongation in two inch

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

3.3.2.7

Classification E7028 is required to have more than 72,000 psi tensile strength,

60,000 psi yield strength, 22% elongation in two inch gauge, and 20 ft-lb at 0°F Charpy V-

3.3.3

Individual Electrode Characteristics a)

E6010 electrodes were originally developed to provide improved welding operation and weld metal. The coating is mostly wood pulp or flour modified

Lesson 8 Hardsurfacing Electrodes

with mineral silicates, deoxidizers, and sodium silicate. The amount of coating on the electrode is low, about 10-12% by weight. Because the wood pulp burns away during welding, the slag is minimal and is usually easily removed. The arc has deep penetration and with proper manipulation of the arc, good

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

gauge, and 20 ft-lb at -20°F Charpy V-notch impacts.

notch impacts.

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Glo

tensile strength, no requirement for yield strength and no Charpy V-notch requirements. 3.3.2.5

Lesson 5 Welding Filler Metals for Stainless Steels

Classification E6022 weld metals are required to have more than 67,000 psi

welds can be deposited in all positions. Most of the ships built in the United States during World War II were welded with this classification of electrode. Special formulations of this classification are used to weld line pipe joints in the vertical-down position. Reasonably sound welds can be deposited in open root butt joints (see Appendix A - Glossary) with this electrode.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON III b)

E6011 electrodes are similar to E6010 except that sufficient potassium com-

Cu Ch Tab Con

pounds have been added to the coating to stabilize the arc stream and allow

Lesson 2 Common Electric Arc Welding Processes

the electrode to be used on alternating current. Penetration is slightly less than that of the E6010 type. c)

E6012 electrodes have several common names. In Europe, they are called rutile (see Glossary) electrodes. Many welders call them cold rods. The

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

coating contains large percentages of the mineral rutile (titanium dioxide), i.e., the titania referred to in the classification. The arc has low penetration, and

P

with proper manipulation wide gaps can be bridged. Although the specification calls for operation on either AC or DC, the arc is smoother and spatter

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

level lower when direct current is used. d)

Glo

E6013 electrodes also contain a large percentage of titanium dioxide in their coating. They are designed to have a low penetrating arc allowing thin sheet metal to be welded without burn-through. The coating contains sufficient

Lesson 5 Welding Filler Metals for Stainless Steels

potassium compounds to stabilize the arc sufficiently for welding with alternating current. e)

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

E7014 electrodes are related to 6013 electrodes except that iron powder has

Turn

been added and a heavier coating is applied to the core wire. This results in higher deposition rates with the E7014 electrode than with the E6013. f)

E7015 electrodes were the first of the low hydrogen electrodes. They were developed in the 1940's to weld hardenable steels such as armor plate. All of

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

the previously discussed electrodes have appreciable amounts of hydrogen in their coatings in the form of water or chemically combined hydrogen in chemical compounds. When hardenable steel is welded with any of those electrodes containing considerable hydrogen, "underbead cracking" commonly occurs. These cracks appear in the base metal usually just below, and parallel

Lesson 8 Hardsurfacing Electrodes

to, the weld bead. Limestone and other ingredients that are low in moisture are used in the coating, eliminating this hydrogen induced cracking. The coating is a low hydrogen, sodium type that limits these electrodes to be used only with direct current, reverse polarity. E7015 electrodes are not generally

Lesson 9 Estimating & Comparing Weld Metal Costs

available today having been replaced by the E7016 and E7018 type. g)

E7016 electrodes are very similar to the E7015 type except that the use of potassium in the coating allows these electrodes to be used with alternating current as well as direct current, reverse polarity.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON III h)

E7018 electrodes are the more modern version of the low hydrogen electrode.

Cu Ch Tab Con

The addition of considerable amounts of iron powder to the covering results in

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

a smoother arc with less spatter. This modern balance of covering ingredients results in a great improvement in arc stability, arc direction and ease of handling in all welding positions. i)

E6020 electrodes have a coating that consists mainly of iron oxide, manga-

Go T

nese compounds and silica. They have a spray-type arc and produce a heavy slag that provides protection of the molten weld metal. The molten weld metal

P

is very fluid, limiting the use to flat or horizontal fillet welds. j)

E6022 electrodes are for high speed, high current single pass welding of sheet metal. They are not generally available today.

k)

Glo

E7024 electrodes have a coating similar to the E6012 and E6013 types, but have a very heavy coating that contains 50% iron powder by weight. Run at relatively higher currents, the deposition rate is high. Welds are limited to the

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

flat and horizontal fillet positions. Penetration is relatively low. AC or DC, either polarity may be used. m)

E6027 electrodes are also a high iron powder type, the coating consisting of

Turn

50% iron powder by weight. Current may be AC or DC, either polarity. The penetration is medium and the weld beads are slightly concave with good side wall fusion. As with all high iron powder electrodes, deposition rate is high. n)

E7028 electrodes are much like the E7018 electrodes except that the coating is heavier and contains 50% iron powder by weight. Unlike the E7018 electrode, they are suitable for flat and horizontal fillet welding only. Deposition rate

Se Ch (Fa Dow

is very high. o)

E7048 electrodes are much like the E7018 electrodes except they are designed for exceptionally good vertical-down welding.

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

LESSON III

3.4

SELECTING THE PROPER MILD STEEL COVERED ELECTRODE

Many factors must be considered when selecting the proper electrode for a given application. Some items to be considered are: a) Type of Base Metal - Welding mild steels or low carbon steels (carbon content

Lesson 3 Covered Electrodes for Welding Mild Steels

Cu Ch Tab Con

Go T

below 0.30%) with mild steel coated electrodes presents no problems as far as tensile strength is concerned since the tensile strength of the weld metal usually exceeds the tensile

P

strength of the base metal. However, chemistry of the base metal is important. Welds made on free machining steels that have a relatively high sulfur content, will be porous unless welded

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

with a low hydrogen type electrode such as E7018. Sometimes off analysis steels or mild steels of doubtful analysis are encountered. In this case, one of the low hydrogen types would

Glo

be the best choice. b) Position of the Weld - Weld position will determine whether an all-position

Lesson 5 Welding Filler Metals for Stainless Steels

electrode or a flat and horizontal type electrode should be used. Higher welding currents, and therefore, higher deposition rates are possible when welding flat or horizontally. Whenever possible, the work should be positioned both for ease of welding and to attain the highest welding speed.

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Turn

c) Available Equipment - Electrode choice will depend on whether AC or DC welding machines are available. If both currents are available, consider these general facts. 1. For deepest penetration, use DC reverse polarity (Electrode Positive).

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

2. For lower penetration and higher deposition rate, use DC straight polarity (Electrode Negative). 3. For freedom of arc blow, use AC. d) Plate Thickness - When welding sheet metal, low penetration electrodes

Lesson 8 Hardsurfacing Electrodes

should be chosen. Heavier plate may demand an electrode with deep penetration. Very heavy plate may require a deep penetrating electrode for the initial or root pass, and a higher deposition type for succeeding passes. e) Fit-Up - Some electrodes are more suitable than others for bridging gaps

Lesson 9 Estimating & Comparing Weld Metal Costs

between the members to be welded. This is termed "poor fit-up" and some electrode manufacturers produce electrodes that are specially formulated for this purpose. f)

Welding Costs - The major factors that affect welding costs are labor and

overhead, deposition rate, efficiency of the electrode being used and the cost of the elec-

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON III trodes. The cost of electrical power is also a factor to a lesser degree. By far, the largest

Cu Ch Tab Con

factor is labor and overhead.

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels

g) Welder Appeal- Welder appeal is definitely important, although this factor must not be allowed to subordinate other more significant criteria. 3.4.1

Typical Electrode Use by Welding Classification

3.4.1.1

The E6010 and E6011 classification electrodes would most likely be used for

Go T

welding a mild steel joint in the vertical position with an open root. If there are only AC power

P

sources available, the choice between these two must be the E6011 type. Many times arc blow is encountered when welding with direct current. The use of E6011 electrodes on alter-

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Glo

nating current eliminates the arc blow. 3.4.1.2

The E6012 classification electrodes are largely used today in repair and welding of

less critical structures. Carbon steels with some rust present can be welded with this type of electrode. It can be used to bridge or weld across wide gaps. The use of this electrode,

Lesson 5 Welding Filler Metals for Stainless Steels

however, has diminished greatly in the past few years. Before the advent of the low hydrogen electrodes and other welding processes, the E6012 electrode made up 60% of the total production of electrodes. Today, it represents about 6% of the total production in the United

Turn

States.

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

3.4.1.3

The E6013 classification of covered mild steel electrodes was originally designed

to have low arc penetration and flat smooth weld beads. These features allowed the electrode to weld sheet metal. Today, many 6013 electrodes are used instead of 6012 electrodes because of the smoother arc, less spatter and more uniform weld bead surface. 3.4.1.4

The E7014 classification of covered mild steel electrodes, as indicated earlier, have

iron powder added to the coating formulation of the E6013 electrodes. This addition allows the electrode to be welded at higher currents, resulting in higher deposition rates and deposi-

Lesson 8 Hardsurfacing Electrodes

tion efficiencies. Applications for the E7014 are similar to those of the E6013 electrodes. 3.4.1.5

The E7016 covered mild steel electrodes are, as indicated earlier, low hydrogen

with a basic slag system. This combination of attributes allows the electrode to be used to weld some of the higher carbon steels and some low alloy steels. This electrode has dimin-

Lesson 9 Estimating & Comparing Weld Metal Costs

ished in usage because of its lower deposition rate and lower deposition efficiency than the more modern E7018 electrode. 3.4.1.6

The E7018 classification is the low hydrogen iron powder electrode. The appre-

ciable amount of iron powder in the coating and the somewhat heavier amount of coating on

Lesson 10 Reliability of Welding Filler Metals

the core wire allow the electrodes to be used at higher currents than those used with the

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON III E7016. The smooth arc and easy welding with the E7018 electrode make it a welder's favor-

Cu Ch Tab Con

ite. The relatively high welding currents and the addition of the iron powder melting into the

Lesson 2 Common Electric Arc Welding Processes

weld metal result in higher deposition rates and higher deposition efficiencies. The E7018 covered mild steel electrode deposits the highest quality weld metal available from manual arc welding. The only major disadvantage of the E7018 is the need to be kept dry. Electrodes that have picked up moisture by exposure to the atmosphere or other sources deposit porous

Lesson 3 Covered Electrodes for Welding Mild Steels

weld metal. Also E7018 electrodes cannot be used to weld the root pass in an open butt joint

Go T

without excess porosity. When E7018 electrodes are to be used in butt welds, the root should be closed by a backing bar, ceramic back-up tape, or consumable insert. If a backing bar is

P

used, it must be removed after the joint is welded by the gas metal arc or the gas tungsten arc process and successive passes applied with E7018 for a high quality weld metal deposit.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Glo 3.4.1.7

The E7024 classification of covered mild steel electrodes is the result of heavy

additions of iron powder to the E6012 formulation and large increases in the amount of coating on the core wire. About 50% of the coating is iron powder. Very high deposition rates and deposition efficiencies result from this combination of more coating and iron powder. The electrode is limited to welding horizontal fillets and flat positions. The quality of the weld metal is not as high as that from E7018 electrodes since the ductility of E7024 weld metal is lower.

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

7

DEPOSITION RATE 5/ 32" DIA. COVERED ELECTRODES

6

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Se Ch (Fa Dow

5

4

Se Doc (Sl Dow

3

2

150

200

250

WELDING AMPERES DEPOSITION RATE, 5/32" DIAMETER COVERED ELECTRODES FIGURE 4

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON III 3.4.2

Electrode Deposition - The deposition rate of a given electrode influences the

Cu Ch Tab Con

total cost of depositing weld metal substantially. The deposition rate is the weight of weld

Lesson 2 Common Electric Arc Welding Processes

metal deposited in a unit of time. Deposition rate increases as the welding current increases within the limits of a given electrode. As can be seen in Figure 4, a 5/32" diameter E7024 electrode can deposit weld metal more than twice as fast as a 5/32" diameter E6010 electrode. It is apparent that a substantial saving in labor and overhead can be achieved if one of

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

the higher deposition electrodes can be used. 3.4.2.1

The deposition efficiency of a given electrode also has an effect on welding costs.

P

The deposition efficiency is the weight of the weld metal deposited compared to the weight of the electrode consumed, expressed as a percentage.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Average Class Efficiency* E6010 63.8% E6011 68.5% E6012 66.9% E6013 66.8% E7014 64.6% E7016 62.8% E7018 69.5% E6020 65.2% E7024 66.8% E7027 68.6% * Includes 2" Stub Loss

Glo

Stub Loss ** Stub Length

5/32" 6010 % Deposit

% Loss 14" Electrode

2"

63.8%

36.2%

3"

58.5%

41.5%

4"

53.2%

46.8%

5"

47.9%

52.1%

6"

42.6%

57.4%

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** E6010 is 71.57% efficient. Loss due to slag, spatter, and smoke Weight of Weld Metal EFFICIENCY = Weight of Electrode Used

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

ELECTRODE EFFICIENCY AND STUB LOSS

FIGURE 5

3.4.2.2

Lesson 8 Hardsurfacing Electrodes

Se Ch (Fa Dow

When welding with coated electrodes, some of the electrode weight is lost as slag,

spatter, fumes, gases, and stubs. If an electrode is 65% efficient, it means that for every 100 pounds of electrodes consumed, 65 pounds of weld metal will be produced. Stub loss, the part of the electrode that is thrown away, is not considered in the deposition efficiency, since the stub length will vary with the operator or the application. Figure 5 illustrates how stub loss

Lesson 9 Estimating & Comparing Weld Metal Costs

affects efficiency. An 6010 electrode has an actual average efficiency of 71.5% before the allowance for stub loss. A 2" stub results in the efficiency dropping to 63.8%. If 6" stubs are thrown away, 100 pounds of electrodes will produce only 42.6 pounds of weld metal. Methods of calculating total weld costs will be covered in a subsequent lesson.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

LESSON III

3.5

ACID AND BASIC SLAG SYSTEMS

The type of slag produced from covered electrodes has a definite effect on the quality of the weld metal. The E6010, 6011, 6012, 6013, 7014, 7024 and other cellulosic and rutile electrodes, produce slags that are predominantly silicon dioxide (sand) and have an acidic behavior. Acid slag systems do no refining of the weld metal. In contrast, the slag from the E7016, E7018 and other low hydrogen electrodes is made up mostly of lime and fluorspar,two items

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

that are basic in chemical behavior. Basic slags do some refining of the weld metal, resulting in lower nonmetallic inclusion content.

3.6 Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Cu Ch Tab Con

P

ADVANTAGES AND DISADVANTAGES OF MILD

Glo

STEEL COVERED ELECTRODES Of all the welding done in the United States, approximately half of it is done with covered electrodes via the shielded metal arc welding (SMAW) process. Every imaginable shape and

Lesson 5 Welding Filler Metals for Stainless Steels

structure made of medium or low carbon steel has been welded with mild steel covered electrodes. The welding advantages of this process are several. It is the simplest welding process available. All that is needed is a constant current power source, two electrical leads and the electrode. It is the most flexible welding process in that it can be used in any position on

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Turn

almost any thickness of carbon steel in any location. The disadvantages are that the covered mild steel welding has lower deposition rates than other processes, thus making it less efficient. Also, the use of covered mild steel electrodes requires more welder training than the semi-automatic and automatic welding processes.

Se Ch (Fa Dow

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Se Doc (Sl Dow

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

LESSON III

3.7

ESAB SUREWELD MILD STEEL COATED

ELECTRODES FEATURES AND DATA SUREWELD 10P (AWS E6010) - This is an all-position cellulosic (wood flour)

3.7.1

electrode that is especially suited for pipe welding but also functions as an excellent general purpose 6010 wire. As a pipe welding electrode, it produces the consistent, deep penetration

Lesson 3 Covered Electrodes for Welding Mild Steels

Cu Ch Tab Con

Go T

required to maintain a proper keyhole when welding in open root pipe joints. Recommended for API grades A25, A, B, and X42 grade pipe and for general structural, ship, barge, and

P

storage tank fabrication. Typical mechanical properties are:

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Glo

Yield Strength - 67,100 psi Tensile Strength - 79,800 psi Elongation (2" Gauge) - 29% Charpy V-Notch Impact Resistance

Lesson 5 Welding Filler Metals for Stainless Steels

-

27 ft-lbs @ 0°F 22 ft-lbs @ -20°F

The typical chemical composition of the weld metal is:

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Carbon

0.12%

Phosphorus

0.009%

Manganese

0.28%

Sulfur

0.017%

Silicon

0.18%

DEPOSITION RATE DATA:

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Electrode Diameter

SUREWELD 10P*

Amperage

Efficiency, %

Deposition (Lbs/Hr .)

3/32"

70 100

72.0% 65.0%

1.5 1.7

1/8"

100 130

76.34 68.81

2.12 2.31

5/32"

140 170

73.57 64.14

2.8 2.93

3/16"

160 190

74.9 69.7

3.3 3.52

Se Ch (Fa Dow

Se Doc (Sl Dow

*Note: Efficiencies do not include stub loss

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON III

SUREWELD 710P (AWS E7010-P1) - An all-position cellulosic electrode espe-

3.7.2

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels

Cu Ch Tab Con

cially suited for welding high strength pipe. It produces the consistent, deep penetration required to maintain a proper keyhole when vertical-down welding in open root pipe joints. Xray quality welds can be produced using flat, horizontal, overhead, vertical-up, and verticaldown procedures. Recommended for X46, X52, and X56 grade pipe, it may also be used for

Go T

welding root passes in higher grade pipe in some circumstances. Typical mechanical properties are:

P

Yield Strength - 69,800 psi Tensile Strength - 81,200 psi

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Glo

Elongation (2" Gauge) - 22% Charpy V-Notch Impact Resistance

-

29 ft-lbs @ -20°F 26 ft-lbs @ -50°F

The typical chemical composition of the weld metal is:

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Carbon

0.10%

Sulfur

0.016%

Manganese

0.31%

Nickel

0.53%

Silicon

0.18%

Molybdenum

0.24%

Phosphorus

0.008%

DEPOSITION RATE DATA: Electrode Diameter 3/32"

1/8"

Turn

SUREWELD 710P*

Amperage 70 100

Efficiency, % 72.0% 65.0%

Deposition (Lbs/Hr .) 1.5 1.7

100 130

76.34 68.81

2.12 2.31

5/32"

140 170

73.57 64.14

2.8 2.93

3/16"

160 190

74.9 69.7

3.3 3.52

Se Ch (Fa Dow

Se Doc (Sl Dow

*Note: Efficiencies do not include stub loss

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON III SUREWELD 810P (AWS E8010-P1) - An all-position cellulosic electrode espe-

3.7.3

Cu Ch Tab Con

cially suited for welding high strength pipe. It produces the consistent, deep penetration

Lesson 2 Common Electric Arc Welding Processes

required to maintain a proper keyhole when vertical-down welding in open root pipe joints. Xray quality welds can be produced using flat, horizontal, overhead, vertical-up, and verticaldown procedures. Recommended for X60, X65, and X70 grade pipe.

Go T

Typical mechanical properties are:

Lesson 3 Covered Electrodes for Welding Mild Steels

Yield Strength - 72,700 psi

P

Tensile Strength - 88,300 psi Elongation (2" Gauge) - 24%

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Charpy V-Notch Impact Resistance

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

31 ft-lbs @ -20°F

Glo

25 ft-lbs @ -50°F The typical chemical composition of the weld metal is:

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

-

Carbon

0.10%

Sulfur

0.014%

Manganese

0.48%

Nickel

0.98%

Silicon

0.24%

Molybdenum

0.11%

Phosphorus

0.008%

DEPOSITION RATE DATA: Electrode Diameter 3/32"

Turn

SUREWELD 810P*

Amperage 70 100

Efficiency, % 72.0% 65.0%

Deposition (Lbs/Hr .) 1.5 1.7

1/8"

100 130

76.34 68.81

2.12 2.31

5/32"

140 170

73.57 64.14

2.8 2.93

3/16"

160 190

74.9 69.7

3.3 3.52

Se Ch (Fa Dow

Se Doc (Sl Dow

*Note: Efficiencies do not include stub loss

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON III 3.7.4

SUREWELD SW14 (AWS E6011) - This is also a cellulosic all-position electrode

Cu Ch Tab Con

that has the arc stabilized to weld with alternating current. It produces an easily controlled

Lesson 2 Common Electric Arc Welding Processes

forceful arc with a deep penetration and high quality weld metal that meets specification requirements for soundness. Typical applications include welding of bridges and buildings, piping, ships, pressure vessels and tanks.

Go T

Typical mechanical properties of the weld metal are:

Lesson 3 Covered Electrodes for Welding Mild Steels

Yield Point - 66,800 psi

P

Tensile Strength - 76,100 psi Elongation (2" Gauge) - 22%

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Reduction of Area - 56% Charpy V-Notch Impact Resistance

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

31 ft-lbs @ -20°F

Carbon

0.10%

Phosphorus

0.012%

Manganese

0.36%

Sulfur

0.016%

Silicon

0.15%

DEPOSITION RATE DATA:

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

-

The typical chemical composition of the weld metal is:

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Glo

Turn

SW14*

Electrode Diameter

Deposition Amperage

Efficiency, %

(Lbs/Hr.)

1/8"

120

70.7

2.3

5/32"

150

77.0

3.7

3/16"

180

73.4

4.1

7/32"

210

74.2

5.0

1/4"

250

71.9

5.0

Se Ch (Fa Dow

Se Doc (Sl Dow

*Note: Efficiencies do not include stub loss

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON III SUREWELD SW612 (AWS E6012) - This is a multiple purpose rutile electrode that

3.7.5

Cu Ch Tab Con

is useful for poor fitup welding. It deposits convex weld beads that have great resistance to

Lesson 2 Common Electric Arc Welding Processes

cracking. It withstands the high amperage of production welding without coating breakdown. The weld deposit has excellent mechanical properties for the classification. The SW612 electrode is used to weld truck bodies, trailers, tanks, farm machinery and auto parts.

Go T

Typical mechanical properties are:

Lesson 3 Covered Electrodes for Welding Mild Steels

Yield Point - 62,300 psi

P

Tensile Strength - 69,400 psi Elongation (2" Gauge) - 21%

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Reduction of Area - 54% The typical chemical composition of the weld metal is: Carbon

0.05%

Phosphorus

0.008%

Manganese

0.31%

Sulfur

0.016%

Silicon

0.12%

DEPOSITION RATE DATA:

SW612*

Electrode Diameter

Deposition Amperage

Efficiency, %

130

81.8

2.9

5/32"

165

78.8

3.2

200

69.0

3.4

220

77.0

4.0

250

74.5

4.2

320

69.8

5.6

3/16"

7/32"

Turn

(Lbs/Hr .)

1/8"

1/4"

Lesson 9 Estimating & Comparing Weld Metal Costs

Glo

320

70.0

5.6

360

67.7

6.6

380

66.0

7.1

Se Ch (Fa Dow

Se Doc (Sl Dow

*Note: Efficiencies do not include stub loss

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON III SUREWELD SW15 (AWS E6013) - This is a fine high production electrode that

3.7.6

Cu Ch Tab Con

can weld thicknesses from light gauge sheet to heavy plate. High welding currents and travel

Lesson 2 Common Electric Arc Welding Processes

speeds can be used without undercut. The slag is self-cleaning. SW15 may be used to weld metal fixtures, road equipment, farm machinery, building structures, storage tanks, and iron work. Typical mechanical properties of the weld metal are:

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

Yield Point - 63,000 psi

P

Tensile Strength - 71,000 psi Elongation (2" Gauge) - 24% Reduction of Area - 49%

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

5/32"

3/16"

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Carbon

0.06%

Phosphorus

0.012%

Manganese

0.32%

Sulfur

0.013%

Silicon

0.23%

DEPOSITION RATE DATA: Electrode Diameter

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Glo

The typical chemical composition of the weld metal is:

7/32"

1/4"

SW15*

Amperage

Efficiency, %

Deposition (Lbs/Hr .)

140

75.6

2.60

160

74.1

3.02

180

71.2

3.48

180

73.9

3.20

200

71.1

3.80

220

72.9

4.09

250

71.3

5.30

270

73.0

5.70

290

72.7

6.08

290

75.0

6.20

310

73.5

6.50

330

72.1

7.10

Se Ch (Fa Dow

Se Doc (Sl Dow

*Note: Efficiencies do not include stub loss

Lesson 9 Estimating & Comparing Weld Metal Costs

3.7.7

6013LV (AWS E6013) - The arc characteristics, weld metal properties and in-

tended applications are similar to SW-15 (E6013) electrodes. This electrode is intended for use on AC power sources where there is less than 50 open circuit volts. These lower open circuit voltage machines make the arc initiation and restrike difficult with a conventional E6013

Lesson 10 Reliability of Welding Filler Metals

Turn

electrode. The 6013LV is a suitable replacement for SW-15.

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON III SUREWELD SW15-IP (AWS E7014) - This electrode has iron powder added to

3.7.8

Cu Ch Tab Con

the coating, permiting use of higher welding currents. The deposition rate is increased by the

Lesson 2 Common Electric Arc Welding Processes

use of higher welding currents while the iron powder content of the covering increases the deposition efficiency. Both of these increases make the welding operation more efficient. The high currents and high welding speeds can be used without undercut. The slag removal is easy and complete. Typical applications include construction equipment, metal fixtures, auto-

Lesson 3 Covered Electrodes for Welding Mild Steels

Yield Point - 61,000 psi Tensile Strength - 71,300 psi

The typical chemical composition of the weld metal is: Carbon

0.04%

Phosphorus

0.015%

Manganese

0.31%

Sulfur

0.019%

Silicon

0.14%

DEPOSITION RATE DATA:

Lesson 9 Estimating & Comparing Weld Metal Costs

SW15-IP*

Turn

Electrode Diameter 1/8"

5/32"

3/16"

Lesson 8 Hardsurfacing Electrodes

Glo

Elongation (2" Gauge) - 28%

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

P

Typical mechanical properties of SW15-IP weld metal are:

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Go T

motive parts, barges and farm machinery.

7/32"

1/4"

Deposition Amperage

Efficiency, %

(Lbs/Hr .)

120

63.9

2.45

150

61.1

3.10

160

71.9

3.04

200

67.0

3.69

230

70.9

4.50

270

73.2

5.50

290

67.2

5.82

330

70.3

7.12

350

68.7

7.08

400

69.9

8.70

Se Ch (Fa Dow

Se Doc (Sl Dow

*Note: Efficiencies do not include stub loss

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON III SUREWELD 70LA-2 (AWS E7016) - This low hydrogen electrode has a special

3.7.9

Cu Ch Tab Con

lime covering that allows the electrode to deposit trouble-free welds on difficult to weld steels,

Lesson 2 Common Electric Arc Welding Processes

such as high carbon, low alloy, sulfur bearing free machining, and cold rolled steels. It is usable with high amperages with corresponding high deposition rates making it more economical than conventional electrodes on heavy work. The electrodes must be kept dry, and welding should be performed using as short an arc as possible.

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

Typical mechanical properties of the weld metal are:

Tensile Strength - 79,000 psi Elongation (2" Gauge) - 28%

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

The typical chemical composition of the weld metal is: Carbon

0.07%

Manganese

0.09%

Silicon

0.50%

DEPOSITION RATE DATA:

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

70LA-2*

Turn

Electrode Diameter 5/32"

3/16"

Lesson 8 Hardsurfacing Electrodes 1/4"

Lesson 9 Estimating & Comparing Weld Metal Costs

Glo

Reduction of Area - 75%

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

P

Yield Point - 69,500 psi

Deposition Amperage

Efficiency, %

(Lbs/Hr .)

140

70.5

3.01

160

69.1

3.24

190

66.0

3.61

175

71.0

3.79

200

71.0

4.23

225

70.0

4.40

250

65.8

4.77

250

74.5

5.93

275

74.1

6.42

300

73.2

6.78

350

71.5

7.58

Se Ch (Fa Dow

Se Doc (Sl Dow

*Note: Efficiencies do not include stub loss

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON III ATOM ARC 7018 (AWS E7018) - This electrode was the original iron powder low

3.7.10

Cu Ch Tab Con

hydrogen electrode in the United States and continues to be the standard of comparison

Lesson 2 Common Electric Arc Welding Processes

against all others. Outstanding economy and mechanical properties are achieved when Atom Arc 7018 electrodes are used to weld carbon steels, high sulfur steels, enameling steels, and low alloy high tensile steels in all thicknesses. In addition, Atom Arc 7018 electrodes today are manufactured with a moisture resistant coating. Preheat levels may be reduced when welding

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

many hardenable steels with Atom Arc 7018 electrodes. Applications for Atom Arc 7018 electrodes include practically every structure that is welded

P

today. It has been especially useful in welding large oil storage tanks, nuclear plant parts, and in many critical weldments that require the highest possible quality and reliability.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Glo

Typical mechanical properties of Atom Arc 7018 weld metal are: Yield Point - 68,000 psi Tensile Strength - 78,000 psi Elongation (2" Gauge) - 30%

Lesson 5 Welding Filler Metals for Stainless Steels

Reduction of Area - 75.5% Charpy V-Notch Impact Resistance

-

125 ft-lbs @ 72°F

Turn 70 ft-lbs @ -20°F

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

The typical chemical composition of Atom Arc 7018 weld metal is: Carbon

0.045%

Phosphorus

0.015%

Manganese

1.10%

Sulfur

0.014%

Silicon

0.4%

DEPOSITION RATE DATA:

Se Ch (Fa Dow

Atom Arc 7018*

Electrode Diameter

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

1/8"

5/32"

Deposition Amperage

Efficiency, %

(Lbs/Hr .)

120

71.6

2.58

140

70.9

2.74

160

68.1

2.99

140

75.0

3.11

170

73.5

3.78

200

73.0

4.31

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

LESSON III 3/16"

7/32"

1/4"

200

76.4

4.85

250

74.6

5.36

300

70.3

5.61

250

75.0

6.5

300

74.0

7.2

350

73.0

7.4

300

78.0

7.72

350

77.0

8.67

400

74.0

9.04

Cu Ch Tab Con

Go T

P

Glo *Note: Efficiencies do not include stub loss

Lesson 5 Welding Filler Metals for Stainless Steels

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

3.7.11

ATOM ARC 7018AC (AWS E7018) - This iron powder low hydrogen electrode was

specifically designed for optimum performance on AC power sources. This electrode features

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

easier arc starting, improved restrike, and smoother metal transfer than a standard E7018 electrode on AC. Typically, this electrode is used as a tacking electrode.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON III SUREWELD 7024 (AWS E7024) Conforms to 7024-1 - The Sureweld 7024

3.7.12

Cu Ch Tab Con

electrode is approved by the American Bureau of Shipping. It is a high speed electrode using

Lesson 2 Common Electric Arc Welding Processes

heavy concentrations of iron powder in the coating. Used with high welding currents, it produces high deposition rates in horizontal fillet and flat welding positions. The electrode has excellent operator appeal and produces equal leg 45°fillets that eliminate overwelding. The welds have excellent appearance and a self-cleaning slag. The 7024 electrode is ideal for

Lesson 3 Covered Electrodes for Welding Mild Steels

making high speed horizontal fillets and lap welds on mild steel and some low alloy steels in

Go T

weldments such as earth moving and construction equipment, truck bodies, ships, barges and

P

railcars. Typical mechanical properties of 7024 weld metal are:

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Yield Point - 71,000 psi

Glo

Tensile Strength - 81,000 psi Elongation (2" Gauge) - 26% Reduction of Area - 63%

Lesson 5 Welding Filler Metals for Stainless Steels

Charpy V-Notch Impact Value - 25 ft-lbs @ 0°F The typical chemical composition of 7024 weld metal is: Carbon

0.06%

Phosphorus

0.010%

Manganese

0.80%

Sulfur

0.018%

Silicon

0.27%

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

DEPOSITION RATE DATA: Electrode Diameter 1/8"

Efficiency, %

Deposition (Lbs/Hr.)

140

69

3.57

66

5.1

180

67

4.48

200

70

5.23

240

67

6.67

250

69

7.34

290

68

9.15

7/32"

320

69

9.43

1/4"

400

70

12.58

Lesson 8 Hardsurfacing Electrodes 3/16"

Lesson 10 Reliability of Welding Filler Metals

Amperage 180

5/32"

Lesson 9 Estimating & Comparing Weld Metal Costs

7024*

Se Ch (Fa Dow

Se Doc (Sl Dow

*Note: Efficiencies do not include stub loss

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels

LESSON III

APPENDIX A LESSON III - GLOSSARY OF TERMS Electrode Core Wire

Electrode

- The mixture of chemicals, minerals and metallic alloys applied to the core wire. The coating controls the welding current, the welding position, and

Glo

the welding slag that absorbs impurities from the weld metal. It also helps shape the weld bead and becomes an insulating blanket over the weld bead. Mild Steel

Lesson 5 Welding Filler Metals for Stainless Steels

- An alloy of mostly iron with low content of alloying elements such as carbon and manganese.

Low Alloy Steel Hardenable Steel

- An alloy of iron with alloy additions, usually in the range of 1½ to 5%.

- The weight of weld metal deposited compared to the time of welding. It is

Deposition

- The relationship of the electrode used to the amount of the weld metal de-

Lesson 8 Hardsurfacing Electrodes

usually expressed in pounds per hour.

posited, expressed in percent, i.e.; DE = Weight of Weld Metal ÷ Weight of Electrode Used

Arc Blow

- Welding with direct current may set up a magnetic field in the steel plate being welded. This magnetic field causes the arc to flutter and blow, creating difficulty in controlling the arc.

Cellulose

Turn

- An alloy of iron that is subject to hardening when rapidly cooled.

Deposition Rate

Efficiency

Lesson 9 Estimating & Comparing Weld Metal Costs

Go T

determined by the diameter of the core wire.

provides a shielding atmosphere, deoxidizers to clean the weld metal, and

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

- The steel wire about which the coating is applied. The electrode size is

P Coating

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Cu Ch Tab Con

- A chemical of carbon, hydrogen and oxygen. As used in mild steel electrode coatings, it consists of wood pulp or flour.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

LESSON III Rutile

- The natural form of the mineral titanium dioxide (TiO ).

Titania

- The synthetic form of titanium dioxide (TiO ). In this text the terms rutile and

2

2

titania have the same significance.

Root Pass

- The initial weld bead deposited in a multi-pass weld requiring high weld integrity.

Lesson 3 Covered Electrodes for Welding Mild Steels

Cu Ch Tab Con

Go T

Root Opening - The intentional gap between members to be joined to assure 100% penetra-

P

tion in groove type welds.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Glo

Lesson 5 Welding Filler Metals for Stainless Steels

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Se Ch (Fa Dow

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Se Doc (Sl Dow

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Cu Ch Tab Con

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

BASIC WELDING FILLER METAL TECHNOLOGY

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

P

Glo

A Correspondence Course

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Go T

LESSON IV COVERED ELECTRODES FOR WELDING LOW ALLOY STEELS AN INTRODUCTION TO LOW ALLOY COVERED ELECTRODES

Turn

Se Ch (Fa Dow

Se Doc (Sl Dow

ESAB

ESAB Welding & Cutting Products

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals ©COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

TABLE OF CONTENTS LESSON IV COVERED ELECTRODES FOR WELDING LOW ALLOY STEELS

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Cu Ch Tab Con

Section Nr.

Section Title

Page

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P 4.1

LOW ALLOY STEELS ......................................................................

1

4.2

Consequence of Hydrogen in Low Alloy Steel ..................................

1

4.2.1

Preheat .............................................................................................

3

4.3

MANUFACTURING LOW HYDROGEN ELECTRODES ..................

3

4.3.1

Storage and Reconditioning..............................................................

4

4.3.2

Moisture Resistant Coating ...............................................................

4

4.4

AWS SPECIFICATION FOR LOW ALLOY ELECTRODES..............

5

4.4.1

Effect of Alloying Elements ...............................................................

6

4.4.2

Mechanical Properties (AWS A5.5-96) .............................................

7

4.4.3

Impact Properties..............................................................................

8

4.5

SELECTING THE PROPER LOW ALLOY ELECTRODE ................

8

4.5.1

Service Conditions ............................................................................

8

4.5.2

Joint Design ......................................................................................

9

4.5.3

Equipment.........................................................................................

10

4.6

LOW HYDROGEN IRON POWDER ELECTRODES .......................

11

4.6.1

Atom Arc 7018 (AWS E7018) ...........................................................

11

4.6.2

Atom Arc 7018 Mo (AWS E7018-A1)................................................

11

4.6.3

Atom Arc 8018N (AWS E8018-C2) ...................................................

12

4.6.4

Atom Arc 8018CM (AWS E8018-B2) ................................................

13

4.6.5

Atom Arc 8018W (AWS E8018-G)....................................................

13

4.6.6

Atom Arc 9018CM (AWS E9018-B3) ................................................

14

4.6.7

Atom Arc 9018-B3L (AWS E9018-B3L) ............................................

14

4.6.8

Atom Arc 10018 (AWS E10018-M) ...................................................

15

4.6.9

Atom Arc 10018MM (AWS E10018-D2) ...........................................

15

4.6.10

Atom Arc 12018 (AWS E12018-M)....................................................

16

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 1998 THE ESAB GROUP, INC.

Glo

Turn

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Cu Ch Tab Con

TABLE OF CONTENTS LESSON IV- Con't Section Nr.

Section Title

Page

4.6.11

Atom Arc "T" (AWS E11018-M) .........................................................

16

4.6.12

Atom Arc 9018HT (AWS E9018G) ....................................................

17

4.6.13

Atom Arc 4130 (No AWS Classification) ............................................

17

4.6.14

Atom Arc 4130 LN (No AWS Classification) ......................................

17

Appendix A

Stick Electrode Data Charts - Atom Arc Electrodes ..........................

19

Appendix B

Glossary of Terms .............................................................................

Go T

P

Glo

20

Lesson 5 Welding Filler Metals for Stainless Steels

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Se Ch (Fa Dow

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Se Doc (Sl Dow

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

LESSON IV

COVERED ELECTRODES FOR WELDING

Cu Ch Tab Con

LOW ALLOY STEELS

4.1 LOW ALLOY STEELS

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

Low alloy steels, as discussed in Lesson I, are those steels to that have small amounts of alloying elements added for specific purposes; i.e., to increase strength, toughness, corrosion

P

and rust resistance, or to alter the response to heat treatment. Nearly every steel manufacturer makes a family of low alloy steels that are usually sold under trade names such as Maynari R,

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Cor-ten, Man-ten, and many others. Many of the steels are designed to develop their specific

Glo

properties such as high strength or toughness in the hot rolled and controlled cooling condition, rather than by subsequent heat treatment. Other compositions of low alloy steels are designed to develop specific properties following heat treatments. Examples of these types are U.S. Steel T-1, Armco Steel SS-100, Great Lakes Steel NA XTRA 100, all of which are quenched

Lesson 5 Welding Filler Metals for Stainless Steels

and tempered to reach high strength with good toughness. Covered low alloy welding electrodes are designed, in most cases, to match the properties of the low alloy steels rather than to match the exact chemical composition of the steel. Exceptions to this are the chromium molybdenum electrodes that need to contain about the same amounts of the alloy ingredients

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

as the steel in order to match the properties of the steel.

4.2 CONSEQUENCE OF HYDROGEN IN LOW ALLOY STEEL One of the reasons that low alloy steels are becoming more popular is because of the extensive research that was conducted in the development of electrodes for welding them. Although special precautions and care are required in welding the low alloy steels, they can now be joined with a high degree of reliability. But that was not always so. During World War II when there was a dramatic increase in the use of high strength low alloy steel, there was also a

Lesson 8 Hardsurfacing Electrodes

corresponding increase in weld defects. It was quickly realized that hardenable steels could not be welded in the same manner and with the same electrodes as were then commonly used for welding the lower strength mild steels. Through extensive research, it was found that entrapped hydrogen was the culprit in causing weld defects, and the term "hydrogen

Lesson 9 Estimating & Comparing Weld Metal Costs

embrittlement" became synonymous with red flags warning of impending disaster. 4.2.0.1

When hydrogen bearing compounds such as water, minerals, or chemicals are

present in the electrode coating, as is common with mild steel electrodes, the chemically combined hydrogen is dissociated into atomic hydrogen by the heat of the welding arc. The

Lesson 10 Reliability of Welding Filler Metals

Turn

molten weld metal has the capacity to dissolve the atomic hydrogen. However, as soon as the

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IV weld metal solidifies, it loses the ability to hold the hydrogen in solution and the hydrogen is

Cu Ch Tab Con

either expelled into the atmosphere or moves throughout the weld zone. Steel and weld metal

Lesson 2 Common Electric Arc Welding Processes

are not as solid as they appear to the naked eye, being filled with tiny submicroscopic pores. The hydrogen atoms are smaller than the crystalline structure of the steel or the weld metal, and the hydrogen can move about somewhat freely in the steel, just as air can move through a filter. The hydrogen atoms move out of the weld metal into the heat affected zone. The heat

Lesson 3 Covered Electrodes for Welding Mild Steels

affected zone (HAZ) is an area of critical importance in welding, especially in welding high

Go T

strength steels.

P 4.2.0.2

The heat affected zone (See Figure 1) is that area of the weld joint that did not

become molten in the welding process, but underwent a microstructure change as a result of

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

the heat induced by the arc. This the normally very strong joint. SOLIDIFIED WELD METAL

First of all, the grain struc-

Lesson 5 Welding Filler Metals for Stainless Steels

Glo

zone can become a weak link in

ture of the HAZ is less HEAT AFFECTED ZONE

refined and therefore, weaker than the surrounding unaffected

UNAFFECTED BASE METAL

Turn

base metal or the once

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

molten weld metal. And secondly, if the HAZ is permitted to cool too rapidly in certain steels,

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

a hard brittle crystalline structure, known as Marsenite, is locked in place. The relatively large pores of

HEAT AFFECTED ZONE FIGURE 1

the heat affected zone are a natural collecting place for atomic hydrogen. When two hydrogen atoms meet, they immediately unite to

Lesson 8 Hardsurfacing Electrodes

form molecular hydrogen. The resulting molecules are larger than the crystalline structure of the metal and can no longer move about freely. As more and more hydrogen atoms come into the pores, form molecules, and are trapped, tremendous pressure can develop. Mild steel and lower strength steels are sufficiently plastic to move a little with the hydrogen pressure and not

Lesson 9 Estimating & Comparing Weld Metal Costs

cause the steel to crack. Steels that have high hardness and high strength do not have sufficient plasticity to move with the pressure, and if enough hydrogen is present, cracking of the steel occurs.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IV 4.2.0.3

This hydrogen caused defect, known as underbead cracking (See Figure 2), begins

Cu Ch Tab Con

in the HAZ making it particularly sinister since the crack is not immediately apparent to the

Lesson 2 Common Electric Arc Welding Processes

eye. It occurs after the metal has cooled from about 400°F to room temperature, and it is sometimes referred to as may occur immediately after

Lesson 3 Covered Electrodes for Welding Mild Steels

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days, or even months before

P

it happens. Preheat - Steels

that are highly hardenable by

HYDROGEN INDUCED CRACKS

Glo

a rapid cooling in the heat affected zone require preheat and interpass temperature control.

Lesson 5 Welding Filler Metals for Stainless Steels

HEAT AFFECTED ZONE

BASE METAL

cooling, or it may take hours,

4.2.1

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

WELD METAL

"cold cracking". The defect

UNDERBEAD CRACKING FIGURE 2

As preheat is applied to the steel, the cooling rate of the steel from higher temperatures is slowed. Maintaining a constant temperature between each welding pass also helps to control this cooling. Slower cooling rates prevent the steel from being excessively hardened and thus, minimizes the chance of underbead cracking. When this technique is combined with the use of low hydrogen electrodes, a high

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

degree of reliability can be expected from the welds.

4.3 MANUFACTURING LOW HYDROGEN ELECTRODES The discovery of hydrogen related weld defects initiated the development of low hydrogen electrodes. The functions of the coating with low hydrogen electrodes (i.e., shielding, arc stabilizers, alloy additions, etc.) are much the same as those listed in Lesson III for Mild Steel Covered Electrodes, but the coating is formulated with ingredients that lack hydrogen in their chemical composition. This is primarily accomplished by eliminating organic and chemical

Lesson 8 Hardsurfacing Electrodes

compounds high in moisture content. In fact, control of the moisture levels in the coating is critical in the manufacture and use of low hydrogen electrodes. 4.3.0.1

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

In addition to eliminating hydrogen in the coating formula, the manufacturing process

entails a high temperature bake cycle. After the coating is extruded onto the core in the same manner as a mild steel coated electrode, the low hydrogen electrodes are given an initial low temperature bake (300-400°F), and then rebaked in a separate high temperature oven (800900°F) for a specified period of time. This procedure practically eliminates all moisture, and to guard against the reabsorbing of moisture that is naturally present in the atmosphere, the

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IV

electrodes are immediately packaged in hermetically sealed metal containers following the

Cu Ch Tab Con

high temperature bake.

Lesson 2 Common Electric Arc Welding Processes

4.3.1

Storage and Reconditioning - All low hydrogen electrodes will absorb some

moisture from the air after the electrode container is opened. Therefore, those electrodes that are not intended for use within a given period of time must be stored in a vented oven and

Lesson 3 Covered Electrodes for Welding Mild Steels

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maintained at a constant temperature. 4.3.1.1

Various structural and military codes allow only specified times of exposure. These

P

may be anywhere from 30 minutes to 8 hours depending on the electrode alloy, the relative humidity in the work area, and the critical nature of the application. If the low hydrogen elec-

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

trodes are exposed to the atmosphere beyond these time limits, they must be scrapped or

Glo

reconditioned by rebaking in a vented oven for a specified time at a specific temperature. 4.3.1.2

The recommended storage and rebake temperatures for Atom Arc low hydrogen

electrodes are follows:

Lesson 5 Welding Filler Metals for Stainless Steels 4.3.2

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

STORAGE

RECONDITIONED

225-300°F

1 hr. @700°F

Moisture Resistant Coating - Moisture absorption is of special concern to end-

have a high level of relative humidity. As the temperature and relative humidity increase, the chance of absorbing moisture in the low hydrogen coating is greatly increased. To combat this possibility, major electrode manufacturers have in recent years developed low hydrogen electrodes with moisture resistant coatings. These coatings low the rate of moisture absorp-

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

tion in electrodes that have been exposed to the air for extended periods, thus adding an extra degree of reliability to low hydrogen electrodes. 4.3.2.1

The following graphs (figure 3) give an idea of the effectiveness of a moisture

resistant coating. The tests were conducted on Atom Arc 7018 electrodes. The method of

Lesson 8 Hardsurfacing Electrodes

moisture testing chosen by ESAB is that described in Section 25 of the AWS A5.5-96 Specification. This method was chosen because it satisfies the AWS specifications and is sensitive only to water, making it one of the most accurate and reliable methods of moisture determination currently in use.

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

users such as shipbuilders and oil rig fabricators who are situated in areas of the world that

4.3.2.2

The AWS structural code and military specifications allow a maximum of 0.40% and

0.20% moisture content, respectively, for E70XX low hydrogen electrodes. As shown on the preceding graphs, the Atom Arc 7018 electrode satisfied this low moisture requirement for exposure times beyond those normally allowed in field use.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IV

Cu Ch Tab Con

.40

Lesson 2 Common Electric Arc Welding Processes

70°F - 70% Relative Humidity .30 .20 .10

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Go T

0 1

2

4

8

12

24

36 48

96

Exposure Time (hours)

Moisture at Zero Hours .09

P

.40

Glo .30

80°F - 80% Relative Humidity .20 .10

Lesson 5 Welding Filler Metals for Stainless Steels

01 Moisture at Zero Hours .08

2

4

8

12

24

36 48

96

Exposure Time (hours)

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

.40 .30

90°F - 90% Relative Humidity .20

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

0 1

2

Moisture at Zero Hours .10

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Se Ch (Fa Dow

.10

4

8

12

24

Exposure Time (hours)

EFFECTIVENESS OF MOISTURE RESISTANT COATING - ATOM ARC 7018 ELECTRODES FIGURE 3

4.4

AWS SPECIFICATION FOR LOW ALLOY

ELECTRODES A5.5-96 With very few exceptions, low alloy electrodes are made by adding the appropriate alloying elements to the electrode coating rather than having a core wire that matches the low alloy steel. Low alloy covered electrodes are classified according to the American Welding Society filler metal specification A5.5-96. This specification contains the mechanical property require-

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IV ments and stress relieved condition, the chemical requirements, and the weld metal sound-

Cu Ch Tab Con

ness requirements. Electrodes are classified under this specification according to the me-

Lesson 2 Common Electric Arc Welding Processes

chanical properties and chemical composition of the weld metal, the type of covering, and the welding position of the electrode. The classification of the electrode is designated by the manufacturer according to the results of his own tests. The manufacturer, thereby, guarantees his electrode to meet the requirements of the AWS specification.

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

4.4.0.1

The letter-number designations for low alloy electrode classifications mean much

the same as with mild steel electrodes, except that the major alloy composition is indicated by

P

a letter-number suffix. For example, E7018-A1 indicates an electrode (letter E); with a minimum of 70,000 psi tensile strength (70); is weldable in all positions (1); is iron powder low

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

hydrogen (8); and contains nominally 1/2% molybdenum (A1). The full list of nominal alloy

TABLE 1. Nominal Alloy Designations for AWS A5.5 Specification

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

A1

1/2% Molybdenum

B1

1/2% Chromium, 1/2% Molybdenum

B2

1-1/4% Chromium, 1/2% Molybdenum

B2L

Low Carbon version of B2 type. Carbon content is 0.05% or less

B3

2-1/4% Chromium, 1% Molybdenum

B3L

Low Carbon version of B3 type. Carbon content is 0.05% or less

Turn

B4L

2% Chromium, 1/2% Molybdenum, low carbon (0.05% or less)

B5

1/2% Chromium, 1.1% Molybdenum

C3

1% Nickel

C1

2% Nickel

C2

3% Nickel

D1

1-1/2% Manganese, 1/3% Molybdenum

D2

1-3/4% Manganese, 1/3% Molybdenum

M

Conforms to compositions covered by Military specifications.

G

Needs only a minimum of one of the elements listed in the AWS A5.5 Table

Se Ch (Fa Dow

for Chemical Requirements.

4.4.1

Effect of Alloying Elements

4.4.1.1

Molybdenum - When mild steel weld metal is stress relieved, the yield point is

lowered 3,000 psi or more and the tensile strength is also lowered 3,000 psi or more. When 1/2% of molybdenum is added to the weld, both the yield point and the tensile strength remain constant from the as-welded to the stress relieved condition. The presence of molybdenum

Lesson 10 Reliability of Welding Filler Metals

Glo

compositions for this specification is contained in Table 1.

also increases the tensile strength of the weld metal.

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IV 4.4.1.2

Chromium - When chromium is added to the weld metal, the corrosion and high

Cu Ch Tab Con

temperature scaling resistance are increased. The combination of chromium and molybde-

Lesson 2 Common Electric Arc Welding Processes

num allows the weld metal to retain high strength levels at medium high temperatures. 4.4.1.3

Nickel - Mild steel weld metal usually becomes brittle at temperatures below -20°F.

The addition of 1-3% nickel to the weld metal enables the weld metal to remain tough at considerably lower temperatures. The presence of the nickel also makes the weld metal more

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

resistant to cracking at room temperature.

P 4.4.1.4

Manganese - The presence of 1-1/2% to 2% manganese in weld metal increases

the tensile strength and when 1/3% molybdenum is added in combination, the high strength

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

weld metal is crack resistant.

Glo 4.4.1.5

It should be noted that the A5.5-96 specification covers not only the low alloy low

hydrogen electrodes, but also low alloy versions of the cellulosic, titania, and iron oxide type electrodes. A full list of all the electrodes covered by this specification is presented in Table 2.

Lesson 5 Welding Filler Metals for Stainless Steels

TABLE 2. Electrode Classifications of AWS A5.5 Specification

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

E8018-B2

E9015-B3L

E11018-M

E7011-A1

E8018-B2L

E9016-B3

E12018-M

E7015-A1

E8015-B4L

E9018-B3

E7016-A1

E8016-B5

E9018-B3L

EXX10-G

E7018-A1

E8016-C1

E9015-D1

EXX11-G

E7020-A1

E8018-C1

E9018-D1

EXX13-G

E7027-A1

E8016-C2

E9018-M

EXX15-G

E8018-C2 E8016-C3

E10015-D2

EXX18-G

E8018-B1

E8018-C3

E10016-D2

E7020-G

E9015-B3

E10018-M

E8016-B2

4.4.2

Turn

Se Ch (Fa Dow

EXX16-G

E8016-B1

E8015-B2L

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

E7010-A1

Se Doc (Sl Dow

E10018-D2

Mechanical Properties (AWS A5.5-96) - Since many low alloy steels require

some post-weld heat treatment to relieve the internal stresses generated from the welding process, physical testing on the weld metal of most low alloy electrodes is required to be performed after the specimen has been stress-relieved. Only the E8016-C3, E8018-C3, E9018-M, E11018-M, and E12018-M types are permitted to be tested in the as-welded condi-

Lesson 10 Reliability of Welding Filler Metals

tion for classification purposes.

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON IV

4.4.3

Lesson 2 Common Electric Arc Welding Processes

Cu Ch Tab Con

Impact Properties - Since many low alloy steels are developed for low tempera-

tures service, impact properties of the weld metal designed to join these steels are very important. Except for those types already mentioned, all impact testing is performed on specimens after they have been stress-relieved. Table 3 lists the minimum charpy v-notch impacts required in the A5.5 specification.

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

TABLE 3.

Impact Requirements for AWS A5.5 Specification

P AS WELDED

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

MINIMUM REQUIREMENT

E8016-C3

)-------

E8018-C3

)

20 ft.-lbs. @-40°F.

E9018-M

)

(

E9015-D1

E10018-M

)

(

E9018-D1

E11018-M

)-------

(

E10015-D2

E12018-M

)

(

E10016-D2

(

E10018-D2

Glo

20 ft.-lbs. @-60°F. --------

Lesson 5 Welding Filler Metals for Stainless Steels 20 ft.-lbs. @-75°F. --------

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

STRESS-RELIEVED

20 ft.-lbs. @-100°F.-------

(

E8016-C1

(

E8018-C1

(

E8016-C2

(

E8018-C2

Impact values for all other classifications are not required.

4.5

SELECTING THE PROPER LOW ALLOY ELECTRODE

As stated earlier, low alloy electrodes are often selected to match the properties of the steel to be welded rather than matching the exact chemical composition of the steel. These properties (i.e., strength, toughness, creep, and corrosion resistance) reflect the type of service for which

Lesson 8 Hardsurfacing Electrodes

the steel is intended. The letter-number suffix of the electrode classification gives an indication of that service. Whenever possible, the electrode should be selected on the basis of the appropriate strength levels and the intended service of the weldment. 4.5.1

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

Service Conditions - The large family of "proprietary" steels that are sold in the as

rolled, controlled, cooled condition have a 50,000 psi minimum yield point and 70,000 psi minimum tensile strength. Electrodes that deposit low hydrogen weld metal of those strength levels are used to weld them.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IV 4.5.1.1

Some of the low alloy high strength steels are intended for use at subzero tempera-

Cu Ch Tab Con

tures. Nickel bearing low hydrogen electrodes (C1, C2, C3 types) are available for such low

Lesson 2 Common Electric Arc Welding Processes

temperature applications. 4.5.1.2

Chromium molybdenum low alloy steels are used for moderately high temperature

service. Piping, tubing, boilers, etc., that are used extensively in power generating plants, are

Go T

fabricated from these steels. Chrome-moly low hydrogen electrodes (B1, B2, B3, etc.) are

Lesson 3 Covered Electrodes for Welding Mild Steels

produced to weld these steels.

P 4.5.1.3

Many bridges and outdoor structures are constructed from "weathering" grade

steels. These are low alloy steels that, on exposure to the atmosphere, develop a thin, tightly

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

adhering layer of rust that prevents further rusting and eliminates the need for painting. Low

Glo

alloy electrodes with additions of chromium and copper are available for welding these steels. 4.5.1.4

Quenched and tempered low alloy steels usually develop high strength with good

toughness. These types are used where substantial savings in the weight of the structure is

Lesson 5 Welding Filler Metals for Stainless Steels

important. Quite often, but not exclusively, these steels are used by the military. One of the more exotic applications for quenched and tempered low alloy steels is in the fabrication of the pressure hulls for nuclear submarines. The "M" series of high tensile low hydrogen electrodes is intended to weld these steels.

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

4.5.1.5

Turn

High tensile line pipe for the transmission of oil and gas is being used with greater

frequency today. Low alloy cellulosic electrodes of the 7010 and 8010 variety are used for field welding.

4.5.2

Joint Design - In fillet welding of high strength quenched and tempered steels, toe

cracking alongside the welds (see Figure 4) is frequently a problem. The toe cracking is caused by the high strength weld metal having a higher yield point and tensile strength than the steel. 4.5.2.1

When the weld area shrinks on

cooling from the welding temperature, something

BASE METAL

CRACK AT TOE OF WELD

must give, and because the yield and strength levels of the steel are lower than those of the

Lesson 9 Estimating & Comparing Weld Metal Costs

weld metal, cracking occurs in the heat affected zone of the steel. The solution to this problem is

HEAT AFFECTED ZONE

WELD METAL

to use a lower strength weld metal and increase the fillet size to meet the weld joint strength requirements.

TOE CRACKING FIGURE 4

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IV With a somewhat lower strength weld metal as the filler, the yield point of the weld metal is

Cu Ch Tab Con

reached during the shrinkage on cooling. The weld metal stretches without overloading in the

Lesson 2 Common Electric Arc Welding Processes

heat affected zone of the steel and there is no cracking.

4.5.3

Equipment - The electrode selected will operate only on the appropriate power

source. Table 4 lists the type of current for which each class of electrode is designed.

Go T Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

TABLE 4. Current Requirements for AWS Electrode Classes Electrode Class

Current

EXX10-X*

DCRP

EXX11-X

AC or DCEP

EXX13-X

AC or DC either polarity

EXX15-X

DCEP

EXX16-X

AC or DCEP

EXX18-X

AC or DCEP

EXX20-X

P

Glo

AC or DCEN (horizontal fillet) AC or DC either polarity (flat)

EXX27-X

AC or DCEN (horizontal fillet) AC or DC either polarity (flat)

Turn

* "X" indicates a variable in the classification.

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Se Ch (Fa Dow

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Se Doc (Sl Dow

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

LESSON IV

4.6 ESAB ATOM ARC LOW HYDROGEN IRON POWDER ELECTRODES - FEATURES AND DATA Atom Arc 7018 (AWS E7018) - Although this electrodes is really of the mild steel

4.6.1

category and classification, the mechanical properties of the weld metal are sufficient to meet

Lesson 3 Covered Electrodes for Welding Mild Steels

Cu Ch Tab Con

Go T

the similar properties of the 50,000 psi yield and 70,000 psi tensile strength steels. Usually, preheat and interpass temperature control of those steels is not necessary when welding with

P

Atom Arc 7018, although heavier thicknesses of steel may require some preheat. Common applications include: welding carbon steels, high sulfur steels, enameling steels, and some

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

low alloy, high tensile steels.

Glo

Typical Mechanical Properties of Weld Metal As Welded

Lesson 5 Welding Filler Metals for Stainless Steels

Yield Point, psi

68,500

62,000

Tensile Strength, psi

75,000

72,000

% Elongation (2")

31

% Reduction

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

77

@72°F.

125 ft.-lbs.

130 ft.-lbs.

@-20°F.

70 ft.-lbs.

75 ft.-lbs.

C

Mn

Silicon

0.06%

1.10%

0.50%

Se Ch (Fa Dow

Atom Arc 7018 Mo (AWS E7018-A1) - This electrode, which deposits 1/2%

molybdenum weld metal, is useful in welding power piping and pressure vessels of molybdenum bearing steels designed for use at elevated temperatures. Typical applications include: welding of low carbon and carbon-moly tubes and piping, forged alloy steel pipe flanges, fittings and valves for high temperature service, carbon-moly steel boiler and

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

Typical Chemical Composition of Weld Metal

4.6.2

Lesson 8 Hardsurfacing Electrodes

32

75.5

Charpy V-Notch Impact

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Stress-Relieved

superheater tubes, manganese-moly and manganese-moly-nickel pressure vessel plates, high strength structural steel and steel castings for highway service.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IV Typical Mechanical Properties of Weld Metal As Welded *

Lesson 2 Common Electric Arc Welding Processes

73,500

71,000

Tensile Strength, psi

84,000

81,000

30

Charpy V-Notch Impact

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Stress-Relieved*

Yield Point, psi

% Elongation (2")

30

@72°F.

95 ft.-lbs.

95 ft.-lbs.

@-10°F.

85 ft.-lbs.

85 ft.-lbs.

@-40°F.

70 ft.-lbs.

70 ft.-lbs.

Typical Chemical Composition of Weld Metal C

Mn

Ni

0.04%

1.06%

2.37%

Glo

Atom Arc 8018N (AWS E8018-C2) - 8018N electrodes with 3% nickel are usually

4.6.3

used to weld 3% nickel steels for low temperature service. It has solved many weld cracking problems by its weld crack resistance, as well as remaining tough at temperatures as low as -

Turn

low alloy steel forgings and ferritic steel castings for high pressures at low temperatures, high strength steel castings for structural purposes, carbon steel forgings for railroad use and concrete reinforcement bars.

Typical Mechanical Properties of Weld Metal

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

As Welded 83,000

80,500

Tensile Strength, psi

94,000

90,500

25

% Reduction of Area

Lesson 8 Hardsurfacing Electrodes

Stress-Relieved

Yield Point, psi

% Elongation (2")

Lesson 9 Estimating & Comparing Weld Metal Costs

Go T

P

100°F. Typical applications include: welding of piping for low temperature service, carbon and

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Cu Ch Tab Con

Charpy V-Notch Impacts

55 @72°F.

110 ft.-lbs.

28 74 112 ft.-lbs.

@0°F.

91 ft.-lbs.

93 ft.-lbs.

@-40°F.

73 ft.-lbs.

63 ft.-lbs.

35 ft-lbs.

30 ft.-lbs.

@-100°F.

Typical Chemical Composition of Weld Metal C

Mn

Si

Ni

0.5%

0.84%

0.37%

3.30%

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IV Atom Arc 8018CM (AWS E8018-B2) - This 1-1/4% chrome, 1/2% moly electrode

4.6.4

Cu Ch Tab Con

deposits weld metal that retains high strength at temperatures up to 600°F. The 8018CM

Lesson 2 Common Electric Arc Welding Processes

electrodes are used to weld the 1/2% chrome-1/2% moly, 1% chrome-1/2% moly steels, as well as the 1-1/4% chrome-1/2% moly power piping, boiler tubing, plates and castings. Many of the fossil fired steam boilers in electric generating plants in the United States have been welded with this electrode and its relative 9018CM.

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

Typical Mechanical Properties of Weld Metal Stress-Relieved 8

hrs. @1150°F.

Yield Point, psi

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Tensile Strength, psi

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

8

82,400

63,800 78,300

23

% Reduction of Area @30°F.

60.7

79.1

64 ft.-lbs.

127 ft-lbs.

Typical Chemical Composition of Weld Metal C

Mn

Si

Ni

Mo

0.06%

1.10%

0.40%

1.00%

0.50%

Turn

Atom Arc 8018W (AWS E8018-G) - The balanced alloy combination of chromium,

4.6.5

nickel and copper of this electrode causes the weld metal to "weather" similarly to the

appearance and weld integrity is important.

Stress-Relieved As Welded

Lesson 8 Hardsurfacing Electrodes

1

hr. @1025°F.

Yield Point, psi

84,600

79,100

Tensile Strength, psi

94,400

90,100

% Elongation (2")

Lesson 10 Reliability of Welding Filler Metals

Se Ch (Fa Dow

metal with the weathered steel makes these electrodes the ideal choice when architectural

Typical Mechanical Properties of Weld Metal

Lesson 9 Estimating & Comparing Weld Metal Costs

Glo

32

weathering grade steels when exposed to the atmosphere. The inform color blend of this weld

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

P

hrs. @1350°F.

100,000

% Elongation (2")

Charpy V-Notch Impacts

Lesson 5 Welding Filler Metals for Stainless Steels

Stress-Relieved

27

28

68.8

72.3

63 ft-lbs.

44 ft.-lbs.

% Reduction of Area Charpy V-Notch Impacts

@-60°F.

Typical Chemical Composition of Weld Metal C

Mn

Si

Ni

Mo

0.05%

1.11%

0.32%

1.70%

0.28%

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IV Atom Arc 9018CM (AWS E9018-B3) - These 2-1/4% chrome - 1% moly electrodes

4.6.6

Cu Ch Tab Con

are used to weld and match the composition of the 2-1/4% chrome - 1% moly steels in

Lesson 2 Common Electric Arc Welding Processes

pressure piping and power boilers. The chromium-molybdenum content of the weld metal helps retain appreciable strength at temperatures up to 800°F. Typical Mechanical Properties of Weld Metal Stress-Relieved

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

1

hr. @1275°F.

Yield Point, psi Tensile Strength, psi

Stress-Relieved 2

hrs. @1350°F.

87,000

75,000

102,000

91,000

% Elongation (2")

23

27

% Reduction of Area

67

70

C

Mn

Si

Ni

Mo

0.05%

0.75%

0.60%

2.20%

1.05%

Glo

Turn

Atom Arc 9018-B3L (AWS E9018-B3L) - The low carbon content of this 2-1/4%

4.6.7

chrome - 1% moly electrode makes the weld metal more crack resistant in heavy sections and allows lower preheat and interpass temperatures to be used. Typical applications include: high temperature power piping, boilers, heat-exchanger and condenser tubes, pressure vessel

Typical Mechanical Properties of Weld Metal Stress-Relieved 8

hrs. @1150°F.

Yield Point, psi

Lesson 8 Hardsurfacing Electrodes

Tensile Strength, psi

8

hrs. @1350°F.

86,900

69,800 86,400

% Elongation (2")

Charpy V-Notch Impact @30°F.

Stress-Relieved

103,800 21

24

67.6

73

60 ft.-lbs.

79 ft.-lbs.

% Reduction of Area

Lesson 9 Estimating & Comparing Weld Metal Costs

P

Typical Chemical Composition of Weld Metal

plates and steel castings for high temperature pressure service.

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Go T

Typical Chemical Composition of Weld Metal C

Mn

Si

Ni

Mo

0.02%

0.74%

0.61%

2.47%

1.10%

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IV Atom Arc 10018 (AWS E10018-M) - The manganese-nickel-molybdenum

4 .6.8

Cu Ch Tab Con

composition of Atom Arc 10018 is used mostly on thinner sections of quenched and tempered

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels

low alloy steels where 100,000 psi tensile strength, along with good ductility and toughness at temperatures as low as -60°F, are required. This product is used primarily for military applications. Typical Mechanical Properties of Weld Metal

Stress-Relieved As Welded

Yield Point, psi Tensile Strength, psi

96,000

103,000

104,000

24

24

63.5

67

33 ft.-lbs.

22 ft.-lbs.

% Reduction of Area Charpy V-Notch Impact @-60°F.

1 hr. @1025°F.

96,000

% Elongation (2")

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Go T

P

Glo

Typical Chemical Composition of Weld Metal

Lesson 5 Welding Filler Metals for Stainless Steels

C

Mn

Si

Ni

Mo

0.05%

1.58%

0.40%

1.50%

0.30%

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Atom Arc 10018MM (AWS E10018-D2) - This electrode, with its combination of

4 .6.9

manganese and molybdenum, was originally developed during World War II to repair and fabricate manganese-molybdenum castings and armor plate. It is used to weld similar composition low alloy steels, as well as heat treatable steels comparable to hardenable steels. Typical Mechanical Properties of Weld Metal Stress-Relieved As Welded

Lesson 8 Hardsurfacing Electrodes

Yield Point, psi

101,000

91,500

Tensile Strength, psi

106,000

104,000

% Elongation (2")

22

% Reduction of Area Charpy V-Notch Impacts

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals

2 hrs. @1100°F.

26

51

68

@72°F.

83 ft.-lbs.

73 ft.-lbs.

@0°F.

55 ft.-lbs.

50 ft.-lbs.

@-40°F.

38 ft.-lbs.

34 ft.-lbs.

Typical Chemical Composition of Weld Metal C

Mn

Si

Mo

0.09%

1.77%

0.68%

0.35%

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IV Atom Arc 12018 (AWS E12018-M) - This electrode deposits high strength weld

4 .6.10

Cu Ch Tab Con

metal in both the as welded and stress-relieved conditions, which is required for welding many

Lesson 2 Common Electric Arc Welding Processes

of the high strength quenched and tempered steels. It is used to weld steels with 120,000 psi tensile strength in applications, such as welding carbon and high strength alloy steel forgings for railroad equipment, high strength steel castings for structural work, and steel castings for highway bridges.

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

Typical Mechanical Properties of Weld Metal

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Stress-Relieved As Welded

1

hr. @1025°F.

Yield Point, psi

120,000

119,000

Tensile Strength, psi

132,000

129,000

% Elongation (2")

20

22

% Reduction of Area

56

60

Charpy V-Notch Impacts

@72°F.

52 ft.-lbs.

54 ft.-lbs.

@-60°F.

32 ft.-lbs.

31 ft.-lbs.

C

Mn

Si

Cr

Ni

Mo

0.05%

1.90%

0.25%

0.85%

2.00%

0.50%

4 .6.11

Turn

Atom Arc "T" (AWS E11018-M) - Atom Arc "T" electrodes were developed for

Se Ch (Fa Dow

has since been used to weld all of the quenched and tempered steels, including HY-80, the steel used for the pressure hulls of nuclear submarines. Typical Mechanical Properties of Weld Metal

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals

Glo

Typical Chemical Composition of Weld Metal

welding U.S. Steels T-1 steel, which is quenched and tempered to high strength and ductility. It

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

P

Stress-Relieved As Welded

1

hr. @1025°F.

Yield Point, psi

103,000

102,000

Tensile Strength, psi

115,000

116,000

% Elongation (2")

22

% Reduction of Area Charpy V-Notch Impacts

@72°F.

24

62

63

80 ft.-lbs.

73 ft.-lbs.

@0°F.

55 ft.-lbs.

50 ft.-lbs.

@-40°F.

48 ft.-lbs.

42 ft.-lbs.

@-60°F.

41 ft.-lbs.

26 ft.-lbs.

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

LESSON IV Typical Chemical Composition of Weld Metal C

Mn

Si

Cr

Ni

Mo

0.06%

1.53%

0.27%

0.31%

1.88%

0.43%

Atom Arc 9018HT (AWS E9018G) - As the HT indicates, this electrode is intended

4.6.12

Lesson 3 Covered Electrodes for Welding Mild Steels

molybdenum steel castings and is also useful in the repair and rebuilding of hot forging dies.

P Typical Mechanical Properties of Weld Metal Quenched @1700°F.

Quenched @1600°F.

Tempered @1275°F.

Tempered @900°F.

Yield Point, psi

78,000

133,000

Tensile Strength, psi

98,000

180,000

% Elongation (2")

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Go T

for heat treated applications. It deposits weld metal with properties that match chromium-

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

% Reduction of Area

20

12.5

57.5

27

C

Mn

Si

Cr

Mo

0.14%

0.80%

0.65%

2.30%

1.00%

Turn

Atom Arc 4130 (No AWS Classification) - This composition was developed to

4.6.13

Se Ch (Fa Dow

the heat treatment. Typical Mechanical Properties of Weld Metal Quenched @1600°F. Tempered @1150°F.

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Glo

Typical Chemical Composition of Weld Metal

weld heat treatable steels such as SAE4130, providing a weld metal that responds similarly to

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Cu Ch Tab Con

Quenched @1600°F. Tempered @950°F.

Yield Point, psi

121,000

152,000

Tensile Strength, psi

138,000

163,000

% Elongation (2")

18

15

% Reduction of Area

32

36

Typical Chemical Composition of Weld Metal C

Mn

Si

Cr

Ni

Mo

0.18%

1.25%

0.40%

2.50%

1.28%

0.20%

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IV Atom Arc 4130 LN (No AWS Classification) - This alloy combination has less

4.6.14

Cu Ch Tab Con

than 1% nickel so that it may be used safely to weld oil field equipment that handles "sour"

Lesson 2 Common Electric Arc Welding Processes

(high sulfur) crude oil. The weld metal is hardenable by quenching and tempering similar to SAE4130 steel. Typical Mechanical Properties of Weld Metal

Lesson 3 Covered Electrodes for Welding Mild Steels

Quenched @1600°F.

Quenched @1600°F.

Tempered @1200°F.

Tempered @900°F.

Yield Point, psi

109,000

151,500

Tensile Strength, psi

125,000

167,000

% Elongation (2")

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

% Reduction of Area

21

14

58.6

44.6

Go T

P

Glo

Typical Chemical Composition of Weld Metal C

Mn

Si

Cr

Ni

Mo

0.26%

1.25%

0.47%

0.49%

0.80%

0.16%

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

4.6.15

Additional information on Atom Arc Low Hydrogen, Low Alloy electrodes is

contained in the Atom Arc product catalog and the Atom Arc handbook for welding low alloy high tensile steels, published by ESAB.

Se Ch (Fa Dow

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Se Doc (Sl Dow

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON IV

APPENDIX A

Cu Ch Tab Con

STICK ELECTRODE DATA CHARTS

Lesson 2 Common Electric Arc Welding Processes

ATOM ARC ELECTRODES

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

DEPOSITION EFFICIENCY DATA-LOW ALLOY, IRON POWDER ELECTRODES

P

TYPES E7018, E8018, E9018, E10018, E11018, AND E12018 ELECTRODE DIAMETER

AMPS

3/32

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

1/8

Lesson 5 Welding Filler Metals for Stainless Steels

5/32

DEPOSITION EFFICIENCYELECTRODE RATE lbs/hr % DIAMETER

70

1.37

70.50

90

1.65

66.30

110

1.73

64.40

120

2.58

71.60

140

2.74

160

2.99

140

3.11

75.00

170

3.78

200

4.31

3/16

AMPS

DEPOSITION EFFICIENCY RATE lbs/hr %

200

4.85

76.40

250

5.36

74.60

300

5.61

70.30

250

6.50

75.00

70.90

300

7.20

74.00

68.10

350

7.40

73.00

300

7.72

78.00

73.50

350

8.67

77.00

73.00

400

9.04

74.00

7/32

1/4

Glo

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

CHART TO CONVERT ENGLISH ELECTRODE DIMENSIONS TO METRIC EQUIVALENTS

STUB"LOSS CORRECTION TABLE FOR COATED ELECTRODE EFFICIENCY INCLUDING STUB LOSS ELEC.

DEPOSITION

2"

3"

4"

5"

LENGTH

EFFICIENCY

STUB

STUB

STUB

STUB

60%

50.0%

45.0%

40.0%

35.0%

65%

54.2%

48.7%

43.3%

37.9%

70%

58.3%

52.5%

46.6%

40.8%

75%

62.5%

56.2%

50.0%

43.7%

80%

66.6%

60.0%

53.3%

46.6%

60%

51.4%

47.1%

42.8%

38.5%

65%

55.7%

51.1%

46.4%

41.8%

70%

60.0%

55.0%

50.0%

45.0%

75%

64.3%

58.9%

53.6%

48.2%

80%

68.5%

62.8%

57.1%

51.4%

60%

53.3%

50.0%

46.6%

43.3%

65%

57.7%

54.2%

50.5%

46.9%

70%

62.2%

58.3%

54.4%

50.5%

75%

66.6%

62.5%

58.3%

54.2%

80%

71.1%

66.6%

62.2%

57.7%

12"

14"

18"

DIAMETER

LENGTH

Inches

mm

Inches

mm

3/32 1/8 5/32 3/16 7/32 1/4 5/16

2.4 3.2 4.0 4.8 5.6 6.4 8.0

12 14 14 14/18 18 18 18

300 350 350 350/450 450 450 450

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

LESSON IV

APPENDIX B LESSON IV - GLOSSARY OF TERMS Quench

-

The rapid cooling of steel from a temperature above the transformation temperature. This results in hardening of the steel.

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals

Cu Ch Tab Con

Temper

-

Reheating of steel to a temperature below the transformation temperature

Go T

following the quenching of steel. This usually lowers the hardness and

P

strength and increases the toughness of the steel. Stress Relieved

-

The reheating of a weldment to a temperature below the transformation temperature and holding it for a specified period of time. A frequently used

Glo

temperature and time is 1150°F. for 1 hr. per inch of thickness. This reheating removes most of the residual stresses put in the weldment by the heating and cooling during welding. Transformation

-

Temperature

The temperature at which the crystal structure of the steel changes, usually about 1600°F.

Heat Affected

-

Zone

process, but did undergo a microstructure change as a result of the heat

The area of the base metal that did not become molten in the welding

Turn

induced into that area. If the HAZ in hardenable steels is cooled rapidly, the area becomes excessively brittle. Underbead

-

Cracking

excessive molecular hydrogen trapped in that region. It is sometimes

A weld defect that starts in the heat affected zone and is caused by

referred to as cold cracking, since it occurs after the weld metal has cooled. Low Hydrogen

-

Electrodes

hydrogen content. The low hydrogen level is achieved primarily by keeping

Stick electrodes that have coating ingredients that are very low in

the moisture content of the coating to a bare minimum. Weathering

-

Steel

layer of rust. This initial layer prevents further rusting and thus, the need to

Low alloy steel that is specially formulated to form a thin tightly adhering

paint the steel is eliminated. The main alloys in this steel are copper and chromium. Toe

-

Cracking

occurs when the weld metal does not stretch with the base metal because

A weld defect that occurs at the toe of the weld metal. The cracking

the yield and tensile strength of the weld metal is greater than the steel.

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Cu Ch Tab Con

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

BASIC WELDING FILLER METAL TECHNOLOGY

Go T

P

Glo

A Correspondence Course

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

LESSON V WELDING FILLER METALS FOR STAINLESS STEELS

Se Ch (Fa Dow

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Turn

Se Doc (Sl Dow

ESAB

ESAB Welding & Cutting Products

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals ©COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON V

TABLE OF CONTENTS LESSON V WELDING FILLER METALS FOR STAINLESS STEELS

Lesson 2 Common Electric Arc Welding Processes Section Nr.

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Section Title

Page

5.1

INTRODUCTION TO STAINLESS STEEL ......................................

1

5.2

DIFFERENCES IN STAINLESS AND CARBON STEELS ..............

3

5.3

STAINLESS STEEL TYPES ............................................................

5

5.4

AUSTENITIC STAINLESS STEELS ................................................

6

5.4.1

Carbide Precipitation ........................................................................

6

5.4.2

Ferrite in Austenitic Stainless Steels ..................................................

7

5.5

CALCULATION OF FERRITE CONTENT IN STAINLESS STEEL .

8

5.6

SPECIAL FERRITE REQUIREMENT IN STAINLESS STEEL ELECTRODES .................................................................................

10

5.7

MARTENSITIC STAINLESS STEELS .............................................

10

5.8

FERRITIC STAINLESS STEELS .....................................................

11

5.9

DUPLEX STAINLESS STEELS ......................................................

12

5.10

ELECTRODE SELECTION .............................................................

12

5.11

WELDING DISSIMILAR STEELS ....................................................

13

5.12

STAINLESS STEEL ELECTRODES AND FILLER METALS .........

16

5.12.1

Covered Stainless Electrodes............................................................

16

5.12.2

Arcaloy Lime Coated Electrodes .......................................................

17

5.12.3

Arcaloy AC-DC Titania Coated Electrodes ........................................

17

5.12.4

Arcaloy Plus Electrodes .....................................................................

17

5.13

ARCALOY COVERED ELECTRODE PROPERTIES AND APPLICATIONS .......................................................................

18

5.13.1

Arcaloy 308L and 308L Plus ..............................................................

18

5.13.2

Arcaloy 309L and 309L Plus ..............................................................

18

5.13.3

Arcaloy 309 Cb..................................................................................

18

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Cu Ch Tab Con

Go T

P

Glo

Turn

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

LESSON V

TABLE OF CONTENTS LESSON V - Con't. Section Nr.

Lesson 10 Reliability of Welding Filler Metals

Page

5.13.4

Arcaloy 309MoL ................................................................................

5.13.5

Arcaloy 310 .......................................................................................

19

5.13.6

Arcaloy 310 Cb..................................................................................

19

5.13.7

Arcaloy 310Mo ..................................................................................

19

5.13.8

Arcaloy 312 .......................................................................................

19

5.13.9

Arcaloy 316L and 316L Plus ..............................................................

19

5.13.10

Arcaloy 316LF5 .................................................................................

20

5.13.11

Arcaloy 317L and 317L Plus ..............................................................

20

5.13.12

Arcaloy 318 .......................................................................................

20

5.13.13

Arcaloy 320 and 320LR .....................................................................

20

5.13.14

Arcaloy 347 and 347 Plus ..................................................................

21

5.13.15

Arcaloy 410 .......................................................................................

21

5.14

ARCALOY BARE STAINLESS STEEL ELECTRODES .................

21

5.15

APPLICATIONS AND COMPOSITIONS OF ARCALOY BARE STAINLESS ELECTRODES ................................................

19

5.15.2

Arcaloy ER308LSi .............................................................................

22

5.15.3

Arcaloy ER309L ................................................................................

22

5.15.4

Arcaloy ER310 ..................................................................................

22

5.15.5

Arcaloy ER312 ..................................................................................

23

5.15.6

Arcaloy ER316L ................................................................................

23

5.15.7

Arcaloy ER316LSi .............................................................................

23

5.15.8

Arcaloy ER347 ..................................................................................

23

CORE-BRIGHT STAINLESS STEEL FLUX CORED ELECTRODES .................................................................................

P

Glo

Turn

Arcaloy ER308L ................................................................................

5.16

Go T

22 22

5.15.1

5.17

Lesson 9 Estimating & Comparing Weld Metal Costs

Section Title

Cu Ch Tab Con

23

CORE-BRIGHT STAINLESS STEEL FLUX CORED ELECTRODE APPLICATIONS AND PROPERTIES .......................

24

5.17.1

Core-Bright 307.................................................................................

24

5.17.2

Core-Bright 308 Mo ...........................................................................

24

5.17.3

Core-Bright 308LTo ...........................................................................

24

5.17.4

Core-Bright 309L ...............................................................................

25

5.17.5

Core-Bright 316L ...............................................................................

25

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

LESSON V

TABLE OF CONTENTS LESSON V - Con't. Section Nr.

Section Title

Cu Ch Tab Con

Page

5.17.6

Core-Bright 347.................................................................................

25

Lesson 3 Covered Electrodes for Welding Mild Steels

5.18

FERRITE CONTENT OF CORE-BRIGHT WELD METALS ............

25

5.19

SHIELD-BRIGHT & SHIELD-BRIGHT X-TRA

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

5.20

Go T

Lesson 5 Welding Filler Metals for Stainless Steels

STAINLESS STEEL FLUX CORED ELECTRODES ......................

P 26

SHIELD-BRIGHT & SHIELD-BRIGHT X-TRA STAINLESS STEEL

Glo

FLUX CORED ELECTRODE APPLICATIONS & PROPERTIES ...

26

5.20.1

Shield-Bright 308L .............................................................................

26

5.20.2

Shield-Bright 309L .............................................................................

27

5.20.3

Shield-Bright 309LMo ........................................................................

27

5.20.4

Shield-Bright 316L .............................................................................

27

5.20.5

Shield-Bright 317L .............................................................................

28

5.20.6

Shield-Bright 347...............................................................................

28

5.21

ARCALOY NICKEL ALLOY COVERED WELDING ELECTRODES FEATURES AND DATA ....................................................................

29

5.21.1

Arcaloy 9N10 Nickel-Copper .............................................................

29

5.21.2

Arcaloy 8N12 Nickel-Chromium-Iron ..................................................

29

5.21.3

Arcaloy Ni-9 .......................................................................................

30

5.21.4

Arcaloy Ni-12 .....................................................................................

31

5.22

ELECTRODES FOR WELDING CAST IRON ..................................

32

5.22.1

Nickel-Arc 55 .....................................................................................

32

5.22.2

Nickel-Arc 550...................................................................................

33

5.22.3

Nickel-Arc 99 .....................................................................................

33

5.22.4

Nicore 55 ..........................................................................................

33

5.22.5

Cupro Nickel Electrodes ....................................................................

34

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Appendix A - GLOSSARY OF TERMS ..................................................................

35

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V

Cu Ch Tab Con

WELDING FILLER METALS FOR Lesson 2 Common Electric Arc Welding Processes

STAINLESS STEELS 5.1

INTRODUCTION TO STAINLESS STEEL

Go T Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Stainless steel, introduced commercially during the early 1930's, presented industry with a new "wonder metal" with its shiny surface and ability to resist rust and corrosion. This new steel alloy also presented welding problems that had not been previously encountered. It took many

P

years of research and experimentation to develop successful welding filler metals and welding procedures for this "rustless iron" as it was then called.

Glo 5.1.0.1

Most of us think of stainless as an attractive metal used for trim on our stoves and

automobiles, or as bright, easy-to-clean cooking utensils and cutlery. Besides being used for its corrosion resisting properties, however, stainless steel is used for low temperature applica-

Lesson 5 Welding Filler Metals for Stainless Steels

tions, and for applications where its resistance to scaling at high temperatures is important. 5.1.0.2

Stainless steel is basically an alloy of iron and chromium. As the amount of chro-

mium added to a steel alloy is increased, the corrosion resistance increases until the amount of chromium reaches 11% to 12%, at which point it is considered a stainless steel. The graph

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

in Figure 1 shows how the amount of chromium affects the rate of corrosion in a semi-rural, outdoor air environment. Corrosion rate will vary with the corrosive media to which the stainless steel is exposed and with the type of stainless employed.

.001

Se Ch (Fa Dow

MILD STEEL

.0008

Se Doc (Sl Dow

.0006

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

.0004

STAINLESS STEEL

.0002

2

4

6

8

10

12

14

PERCENT CHROMIUM CORROSION RATE VERSUS PERCENT CHROMIUM OUTDOOR ATMOSPHERE, SEMI-RURAL ENVIRONMENT FIGURE 1

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON V 5.1.0.3

The mechanism by which chromium imparts corrosion resistance to steel has been

Cu Ch Tab Con

well established. Essentially, the chromium combines with oxygen of the atmosphere to form a

Lesson 2 Common Electric Arc Welding Processes

stable non-metallic oxide film on the surface of the steel. This film protects the steel by acting as a protective coating. As the chromium content of the steel increases, the tenacity, impermeability and strength of this film increases, imparting greater and greater corrosion resistance. This film is too thin to be seen. What we do see is the shiny, unoxidized steel just below

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

this film. 5.1.0.4

P

In Lesson I we learned that the application of heat to metals can change the micro-

structure and thereby, the properties of that metal. The fabricator of ordinary carbon steel understands that successful welds depend upon how that material behaves under the heat of

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

the arc. With that information as a guide, welds can be produced that satisfy the mechanical vation of corrosion resistance and heat resistance must also be considered. 5.1.0.5

Lesson 5 Welding Filler Metals for Stainless Steels

Glo

requirements of the welded joint. With stainless steel, however, other aspects such as preser-

Stainless steel may be welded by most of the common arc welding processes.

Shielded metal-arc welding with coated electrodes is still probably the most widely used process. Other commonly used processes are flux cored arc welding, gas metal-arc welding, gas tungsten-arc welding and submerged arc welding as discussed in Lesson II.

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

5.1.0.6

The cost of stainless steel is approximately six times that of mild steel. For this

reason, it is important that the proper electrodes or filler metals are selected and the proper welding procedures are followed to minimize rework or scrap losses due to faulty welds. An understanding of the peculiarities of the four types of stainless steel, and how they compare to mild or carbon steels, will help to avoid costly mistakes.

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

5.1.0.7

There are four primary grades of stainless steel: austenitic, martensitic, ferritic, and

duplex. The names are metallurgical terms derived from the crystal structure of the steel at room temperature and will be covered in more detail later in this lesson. Figure 2 shows the basic differences and the composition of the four types.

Lesson 8 Hardsurfacing Electrodes

TYPE

AUSTENITIC MARTENSITIC FERRITIC DUPLEX

Se Doc (Sl Dow

RANGE OF ALLOYING ELEMENTS CHROMIUM

Lesson 9 Estimating & Comparing Weld Metal Costs

Se Ch (Fa Dow

16 11 11 18

-

30% 18% 30% 28%

NICKEL 8 - 40% 0 - 5% 0 - 4% 4 - 8%

MAJOR STAINLESS STEEL ALLOYING ELEMENTS FIGURE 2

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON V 5.1.0.8

That group of stainless steels that contain both chromium and nickel (austenitic

Cu Ch Tab Con

grade) is more readily and satisfactorily welded than those that contain less than 5% nickel

Lesson 2 Common Electric Arc Welding Processes

(martensitic and ferritic grades). Weld joints produced in austenitic stainless steels are strong, ductile and tough in their as-welded condition. They do not normally require preheat or post weld heat treatment. On the other hand, the martensitic and ferritic stainless steels are characterized by hardness or brittleness after welding, and preheat and post-heating is necessary to

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Go T

improve their properties. 5.1.0.9

Austenitic stainless is commonly referred to as the "chrome-nickel" type and the

P

martensitic and ferritic steels are commonly called the "straight chrome" types.

5.2 DIFFERENCES IN STAINLESS AND CARBON STEELS

Glo

The behavior of stainless steel in the heat of the arc differs from that of mild steel. Figure 3

Lesson 5 Welding Filler Metals for Stainless Steels

shows that the rate of expansion of the chromium-nickel types is about 50% greater than that of carbon steel. This means that distortion from warping must be compensated for to a greater extent.

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

CARBON STEEL CHROMIUMNICKEL TYPES

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Se Ch (Fa Dow

STRAIGHT CHROMIUM TYPES .020

Lesson 8 Hardsurfacing Electrodes

.040 .060 .080 .100 INCHES EXPANSION PER FOOT 1000°F TEMPERATURE RISE

.120

RATE OF EXPANSION FIGURE 3

Lesson 9 Estimating & Comparing Weld Metal Costs

5.2.0.1

When welding an austenitic stainless steel to a carbon steel, the different rates of

expansion can cause cracking due to internal stresses unless the proper electrode and welding procedure is used. The expansion of the straight chromium types is about the same as or slightly less than that of carbon steels.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V 5.2.0.2

The melting temperature of all stainless steels are lower than that of carbon steel as

Cu Ch Tab Con

shown in Figure 5, and both chrome-nickel and straight chrome types are much more fluid in

Lesson 2 Common Electric Arc Welding Processes

the melted state. Therefore, less heat (welding current) is required to weld stainless steels compared to carbon steels.

CARBON

Go T

STEEL

Lesson 3 Covered Electrodes for Welding Mild Steels

CHROMIUM-

P

NICKEL TYPES STRAIGHT

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Glo

CHROMIUM TYPES 2000

2250

2500

2750

3000

DEGREES FAHRENHEIT MELTING TEMPERATURES

Lesson 5 Welding Filler Metals for Stainless Steels

FIGURE 4

5.2.0.3

The electrical resistance of both the chrome-nickel and the straight chrome types is

considerably higher than that of the plain carbon steels as shown in Figure 5. This higher

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Turn

resistance creates more resistance heating in the stainless steel electrode and in the base plate. Lower welding current or amperage is required to avoid overheating the electrode. The

CARBON

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Se Ch (Fa Dow

STEEL CHROMIUMNICKEL TYPES

Se Doc (Sl Dow

STRAIGHT

Lesson 8 Hardsurfacing Electrodes

CHROMIUM TYPES MICROHMS/SQ CM/CM AT 20° C.

10

20

30

40

50

60

70

80

ELECTRICAL RESISTANCE

Lesson 9 Estimating & Comparing Weld Metal Costs

FIGURE 5

electrical resistance of the chrome-nickel alloys is about six times that of carbon steel and may be substantially higher if the stainless is cold-worked. The straight chrome types have electri-

Lesson 10 Reliability of Welding Filler Metals

cal resistances varying from three to six times that of carbon steel.

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON V 5.2.0.4

The chrome-nickel stainless alloys conduct heat only 40% to 50% as fast as carbon

Cu Ch Tab Con

steel and in the straight chrome types, heat conductivity is 50% to 65% that of carbon steel as

Lesson 2 Common Electric Arc Welding Processes

shown in Figure 6. This means that the heat remains in the vicinity of the arc for a longer period of time instead of being dispersed throughout the weldment rapidly, as it does when welding materials of high thermal conductivity. This is another reason that lower amperages are required to weld these steels.

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

P CARBON STEEL

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Glo

CHROMIUMNICKEL TYPES STRAIGHT CHROMIUM

Lesson 5 Welding Filler Metals for Stainless Steels

TYPES AT 20° - 100° C CAL/SEC/SQ CM

.020

.040

.060

.080

.100

.120

Turn

THERMAL CONDUCTIVITY

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

FIGURE 6

5.3 STAINLESS STEEL TYPES As already mentioned, there are three principal categories of stainless steels: austenitic, martensitic, and ferritic. The names are derived from the crystalline structure of the steel normally found at room temperature. When low carbon steel is heated above 1550°F, the atoms of the steel are rearranged from the structure called ferrite at room temperatures to the crystal structure called austenite. On cooling, the low carbon steel atoms return to their original

Lesson 8 Hardsurfacing Electrodes

structure — ferrite. The high temperature structure, austenite, is non-magnetic, plastic and has lower strength and greater ductility than the room temperature form of ferrite. 5.3.0.1

Lesson 9 Estimating & Comparing Weld Metal Costs

When more than 17% chromium and 7% nickel are added to the steel, the high

temperature crystalline structure of the steel — austenite, is stabilized so that it persists at all temperatures from the very lowest to almost melting. This alloy combination is the basis for the austenitic category of stainless steels . Many alloy additions are made to that base as modifications for different service requirements.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V 5.3.0.2

When certain alloy steels are cooled rapidly from above the transformation tempera-

Cu Ch Tab Con

ture, a very hard brittle phase occurs. This phase is called martensite. Steels that contain 5-

Lesson 2 Common Electric Arc Welding Processes

15% chromium have this special characteristic. Unless special care is used in welding such steels, they become crack sensitive. These are the martensitic stainless steel alloys. 5.3.0.3

When more than 16% chromium is added to the steel, the room temperature crystal-

line structure, ferrite, is stabilized and the steel remains in the ferritic condition at all tempera-

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

tures. Hence the name, ferritic stainless steel is applied to this alloy base.

P

5.4 AUSTENITIC STAINLESS STEELS Austenitic Stainless Steels are designated by a series of 300 numbers according to the Ameri-

are shown in Figure 7. About 80% of the stainless steel welded is of the austenitic type.

AISI No. 301 302 304 309 310 316 317 347

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Chromium % Nickel % 17 18 19 23 25 17 19 18

7 9 10 13 20 12 13 11

Molybdenum % Columbium %

Turn

2.5 3.5 1

MOST COMMON TYPES OF AUSTENITIC STAINLESS STEELS FIGURE 7

5.4.1

Carbide Precipitation - Many of the austenitic stainless steels are subject to the

phenomenon of carbide precipitation. At elevated temperatures in the range of 800-1600°F, the carbon content in excess of 0.02% migrates to the grain boundaries of the austenitic structure where it reacts with chromium to form chromium carbide. If the chromium is tied up with the carbon, it is not available for corrosion resistance. Thus, when the steel with carbide

Lesson 8 Hardsurfacing Electrodes

precipitation is exposed to a corrosive environment, intergranular corrosion results, allowing the grain boundaries to be eaten away. Figure 8 shows how intergranular corrosion may take place in a tank holding a corrosive liquid. Notice that the corrosion takes place only in the heat affected zone on the inside where the corrosive media is located, and there is no evidence of

Lesson 9 Estimating & Comparing Weld Metal Costs

failure on the outside. 5.4.1.1

Carbide precipitation has no other effect on the steel, however, other than loss of

corrosion resistance in the heat affected zone. During welding, the heat-affected zones along the sides of the weld in austenitic stainless steel are exposed to the temperatures that cause

Lesson 10 Reliability of Welding Filler Metals

Glo

can Iron & Steel Institute (AISI). Nominal compositions of some of the more important types

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Go T

carbide precipitation.

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V

HEAT AFFECTED ZONES

INSIDE OF TANK

Lesson 2 Common Electric Arc Welding Processes

WELD METAL

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

INTERGRANULAR CORROSION FIGURE 8

5.4.1.2

Cu Ch Tab Con

P

If the weldment is to be used in corrosive service, the carbide precipitation and

resultant intergranular corrosion must be eliminated. Three dependable methods of controlling

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

this problem are defined below:

Glo

a. Carbide precipitation is a function of the carbon content. Keeping the carbon content as low as possible in the steel (0.04% maximum) and welding it with low carbon electrodes is one solution.

Lesson 5 Welding Filler Metals for Stainless Steels

b. If the carbon of the steel and weld metal are tied up by an element that has a stronger affinity for carbon than does chromium, carbide precipitation cannot occur. Columbium and titanium are alloys that have a stronger affinity for carbon. Steels with columbium or

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

c. Another method, although not as practical, is to heat the finished weldment to at least 1850°F allowing all of the precipitated carbides to go back into solution. The weldment is then rapidly cooled and quenched so that it passes through the critical temperature

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

(1200°F) very quickly, allowing little or no carbides to reform. However, stainless steel weldments heated to such high temperatures would be subject to warping, sagging and other loss of dimension as well as being covered with heavy scale. 5.4.2

Lesson 8 Hardsurfacing Electrodes

Ferrite in Austenitic Stainless Steel - Stainless weld metal that is fully austenitic is

non-magnetic and has a relatively large grain structure. This results in the weld being cracksensitive. By controlling the balance of the alloying elements in the electrode, small amounts of another phase, ferrite, can be introduced in the weld metal. The ferrite phase causes the austenitic grains to be much finer and the weld becomes more crack-resistant.

Lesson 9 Estimating & Comparing Weld Metal Costs

5.4.2.1

Certain alloying elements used in stainless steels and weld metals behave as

austenite stabilizers and others as ferrite stabilizers. Among the austenite stabilizers are nickel, carbon, manganese and nitrogen. The ferrite stabilizers are chromium, silicon, molybdenum and columbium. It is the balance between the two types of alloying elements that

Lesson 10 Reliability of Welding Filler Metals

Turn

titanium, and covered electrodes with columbium present, are made for this purpose.

controls the quantity of ferrite in the weld metal.

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V 5.4.2.2

The amount of ferrite in austenitic stainless steel weld metal may be measured by

Cu Ch Tab Con

magnetic devices because the ferrite is magnetic. A small amount of ferrite in austenitic

Lesson 2 Common Electric Arc Welding Processes

stainless weld metal is good, because it prevents weld cracking. If the weldment is to be in very low temperature service, however, large amounts of ferrite should be avoided because ferrite is not tough at low temperatures. Also, if the weldment is to be used in high temperature (higher than 1000°F) service, the ferrite should be maintained at low levels because the ferrite

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Go T

becomes brittle at those temperatures.

P

5.5 CALCULATION OF FERRITE CONTENT IN STAINLESS STEEL Several simple, yet accurate, methods have been developed for determining the balance

Glo

between the austenite and ferrite forming elements in iron. When the chemical composition of the weld metal is known, the Schaeffler or WRC-1992 diagrams can be used. See Figures 9 and 10.

Lesson 5 Welding Filler Metals for Stainless Steels

5.5.0.1

The purpose of these diagrams is to calculate the nickel and chromium equivalent of

the weld metal in question and plot the point on the appropriate diagram. The nickel equivalent is the sum of the nickel content and all other austenite formers, multiplied by coefficients representing their austenite forming effect as compared to that of nickel. The chromium

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Turn

equivalent is calculated in the same manner. In both diagrams, the nickel equivalent is the vertical axis, and the chromium equivalent is the horizontal axis. The WRC-1992 diagram has an advantage since it also takes the nitrogen content into consideration. Nitrogen is a powerful austenite forming element. If the nitrogen content is not known, we assume 0.06% for

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

GTAW and SMAW electrodes and, 0.08% for GMAW and FCAW filler metals. 5.5.0.2

When chemical composition is not available, two common instruments can also be

used to determine ferrite content. Since ferrite at room temperature is magnetic and austenite is not, a relationship between magnetic response and ferrite content can be established. The

Lesson 8 Hardsurfacing Electrodes

more magnetic response to the instrument, the more ferrite present in the metal. The two commercially available instruments that use this principal to measure ferrite content are the Magne gage and the Severn gage. The Magne gage is a laboratory instrument, while the Severn gage is a pocket-size instrument designed for on-site readings.

Lesson 9 Estimating & Comparing Weld Metal Costs

5.5.0.3

In the past, ferrite was expressed as a volume percent of the metal. However,

because of non-standard calibration, conflicting and inaccurate results often occurred. To eliminate this problem, the ferrite volume percent was changed to a standardized expression known as the ferrite number (FN) and has been adopted by the Welding Research Council

Lesson 10 Reliability of Welding Filler Metals

(WRC), the American Welding Society (AWS), and other agencies. Ferrite numbers (FN) are

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V

Cu Ch Tab Con

Lesson 2 Common Electric Arc Welding Processes

Go T Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

P

Glo SHAEFFLER CONSTITUTION DIAGRAM FOR STAINLESS STEEL WELD METAL FIGURE 9

Lesson 5 Welding Filler Metals for Stainless Steels

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Se Ch (Fa Dow

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels WRC-1992 DIAGRAM FOR STAINLESS STEEL WELD DATA

Lesson 8 Hardsurfacing Electrodes

FIGURE 10

the same as the volume percent numbers in the range of 0-7%. At higher contents, FN values

Lesson 9 Estimating & Comparing Weld Metal Costs

become increasingly higher than the previous percent ferrite values. The DeLong diagram shows this comparison.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

LESSON V

5.6 SPECIAL FERRITE REQUIREMENT IN STAINLESS STEEL ELECTRODE In order to meet the AWS classification of a stainless steel electrode, a specific chemical range must be followed by the electrode manufacturers. Since ferrite content is mainly controlled by chemical composition, the ferrite content will also fall into certain ranges depending

Go T

on the particular electrode in question. However, some users of stainless steel require the

Lesson 3 Covered Electrodes for Welding Mild Steels

Cu Ch Tab Con

ferrite content be above or below the normal ranges as found in typical chemical analyses. An

P

example of this is the SMAW 316 electrode. Normally, a 316 stick electrode has a FN in the 02 range, but a specially formulated 316 stick electrode could have a minimum of 5 FN, if needed. Since these electrodes require special chemical formulations, they must be ordered

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

on a special request basis from most manufacturers.

Glo

5.7 MARTENSITIC STAINLESS STEEL Martensitic stainless steels fall into the 400 number series according to the American Iron and

Lesson 5 Welding Filler Metals for Stainless Steels

Steel Institute. They are magnetic and contain from 11.5% to 18% chromium. As previously noted, they get the name martensite because of the crystalline structure of the steel at room temperature. With a lower alloy content than the austenitic steels, they are lower in cost than

Turn

the austenitic types. They have adequate corrosion resistance in many environments because

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

they form the characteristic chromium oxide surface film. They also have a high hardenability characteristic. 5.7.0.1

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Other chromium bearing heat resistant steels that have only 4% to 10% chromium

(not a true stainless steel by the 11.5% minimum chrome requirement) have similar

Se Ch (Fa Dow

hardenability characteristics. These steels are designated by the 500 series numbers according to the American Iron and Steel Institute and from a welding standpoint, may be considered in the same grouping as the martensitic stainless steels. Nominal compositions of these types are shown in Figure 11.

Lesson 8 Hardsurfacing Electrodes

5.7.0.2

These steels are frequently in a hard-

ened state meaning they have low ductility. If heat is applied suddenly, as in arc welding, to a

Lesson 9 Estimating & Comparing Weld Metal Costs

localized area and it then is allowed to cool suddenly, cracking may occur. The heated area contracts on cooling and the lack of ductility in the parent metal prevents it from following along.

AISI No. 403 410 501 502

Carbon

Chromium

%* 0.15 0.15 0.10 min 0.10

%* 11.5 - 13 11.5 - 13.5 4-6 4-6

Molybdenum %*

Se Doc (Sl Dow

0.40 - 0.65 0.40 - 0.65

* Maximum unless otherwise noted. NOMINAL COMPOSITION-MARTENSITIC STAINLESS STEELS AND CHROMIUM HEAT RESISTANT STEELS FIGURE 11

This type of cracking can be prevented by pre-

Lesson 10 Reliability of Welding Filler Metals

heating the steel, since preheating lowers the thermal difference between the weld area and

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON V the base metal. This allows the weld area to cool more slowly and as a result, the steel in the

Cu Ch Tab Con

heat affected zone will not be hardened as severely.

Lesson 2 Common Electric Arc Welding Processes

5.7.0.3

The preheating temperature used is in the range of 350°F to 500°F and should be

maintained during the entire welding operation. Upon completion of welding, the weldment should be cooled slowly, preferably furnace cooled, allowing gradual temperature change.

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

5.7.0.4

The mechanical properties of martensitic stainless steels are affected by welding

since they harden intensely, even on relatively slow cooling from high temperatures. The weld

P

deposit and the steel that surrounds the weld deposit is hard and brittle. Heat treatment of the weldment is necessary to improve these physical properties.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

5.7.0.5

Glo

If preheating or postweld heat treatment is not practical, it may be necessary to use

a higher alloy austenitic stainless steel electrode (such as 309) that deposits tough, ductile weld metal without cracking. This solution would depend on the required properties of the weldment and is not recommended in all cases. Martensitic stainless steels make up about

Lesson 5 Welding Filler Metals for Stainless Steels

15% of the stainless steels that are welded.

5.8 FERRITIC STAINLESS STEELS

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Ferritic stainless steels are straight chrome alloys in the AISI 400 series. They are magnetic and have varying ranges of chromium content as shown in Figure 12. 5.8.0.1

All ferritic stainless steels have the room temperature crystal structure of ferrite

stabilized to all temperatures. The higher chromium content provides good resistance to high

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

ing containers, jigs, and fixtures. 5.8.0.2

Welding the ferritic high chromium

stainless steels, however, is difficult. The steels

Lesson 8 Hardsurfacing Electrodes

AISI No. Carbon %* Chromium %*

Other %*

have rapid rates of grain growth at temperatures

405

0.08

11.5 - 14.5

over 1700°F. The large grains absorb the

430

0.12

16.0 - 18.0

--

446

0.20

23.0 - 27.0

Nitrogen 0.25

smaller grains and grow larger. The resultant coarse grain structures are very crack sensitive.

Lesson 9 Estimating & Comparing Weld Metal Costs

Se Ch (Fa Dow

temperature scaling. For this reason, the ferritic stainless steels are used to make heat treat-

Aluminum 0.10 - 0.30

Se Doc (Sl Dow

* Maximum unless otherwise noted. NOMINAL COMPOSITION-FERRITIC STAINLESS STEELS

Grain growth is a time and temperature function. To keep the time of high welding temperature as

FIGURE 12

short as possible, these steels should be mildly preheated to about 300°F, welded with small diameter electrodes and with the lowest possible welding current, thereby limiting the heat input. About 5% of the stainless steels welded are of the ferritic category.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

LESSON V

5.9 DUPLEX STAINLESS STEELS

Cu Ch Tab Con

Duplex means "two". Duplex stainless steels consist of the two "building stones" (microstructure phases) ferrite and austenite and are often termed ferritic-austenitic stainless steels. Typically, duplex stainless steels have a microstructure consisting of approximately 50% ferrite and 50% austenite.

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

5.9.0.1

to stress corrosion cracking, the austenite provides good toughness, and the two phases in

P

combination give the duplex steels their attractive corrosion resistance. 5.9.0.2

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

In simple terms, the ferrite could be said to give high strength and some resistance

The most important alloying elements of duplex stainless steels are Cr, Ni, Mo and

N. These elements largely govern the properties of the steels. Some grades also contain

Glo

additions of copper (Cu) or tungsten (W). 5.9.0.3

A wide range of different versions of duplex stainless steel is currently available

on the market. At present, the 22% chromium (Cr), 5% nickel (Ni), 3% molybdenum (Mo),

Lesson 5 Welding Filler Metals for Stainless Steels

0.15% nitrogen (N) grade (commonly called 2205) is the most common type of duplex stainless steel and is used in a wide range of applications. Higher alloyed duplex steels, the socalled super duplex stainless steels, have also been introduced into the market. The 25% chromium (Cr), 7% nickel (Ni), 4% molybdenum (Mo), 0.25% nitrogen (N) grade (commonly

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

called 2507) is one example of a modern high alloy super duplex stainless steel. These steels are designed for use in demanding applications where even greater corrosion resistance or higher strength is required.

5.10 ELECTRODE SELECTION There are a great many AISI grades of stainless steel, and in many cases there is a matching electrode for the AISI type. For instance, if both members of a weldment are AISI type 316, the electrode to be used would be 316 also. It is not necessary to have a matching electrode for

Lesson 8 Hardsurfacing Electrodes

every type of stainless steel, however, because some electrodes produce satisfactory welds even though the chemical analysis of the steel may be slightly different. 5.10.0.1

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

Type 308 stainless steel electrodes may be used for welding AISI 201 and 202 that

have a lower nickel content and a high manganese content. Type 308 electrodes may also be used to weld types 301, 302, 304, 305 and of course, 308 itself. Even though their chromiumnickel contents vary slightly, all of these steel types may be considered as one family of alloys. The chart in Figure 13 shows the proper Arcaloy electrode to be used for the various types of AISI steels.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Cu Ch Tab Con

LESSON V

Arcaloy Electrodes to Weld AISI Steels Chemical Analyses of Stainless Steels, percent* AISI** Type Number

Carbon

Manganese

Silicon

Chromium

Other Elements

Nickel

Weld with Arcaloy Type

Go T

Austenitic 201 202 301 302 302B 303 303Se 304 304L 305 308 309 309S 310 310S 314 316 316L 317 321 347 348

0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.08 0.03 0.12 0.08 0.2 0.08 0.25 0.08 0.25 0.08 0.03 0.08 0.08 0.08 0.08

5.5/7.5 7.5/10.0 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00

1.00 1.00 1.00 1.00 2.00/3.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.50 1.50 1.50/3.00 1.00 1.00 1.00 1.00 1.00 1.00

16.00/18.00 17.00/19.00 16.00/18.00 17.00/19.00 17.00/19.00 17.00/19.00 17.00/19.00 18.00/20.00 18.00/20.00 17.00/19.00 19.00/21.00 22.00/24.00 22.00/24.00 24.00/26.00 24.00/26.00 23.00/26.00 16.00/18.00 16.00/18.00 18.00/20.00 17.00/19.00 17.00/19.00 17.00/19.00

3.50/5.50 3.50/5.50 6.00/8.00 8.00/10.00 8.00/10.00 8.00/10.00 8.00/10.00 8.00/12.00 8.00/12.00 10.00/13.00 10.00/12.00 12.00/15.00 12.00/15.00 19.00/22.00 19.00/22.00 19.00/22.00 10.00/14.00 10.00/14.00 11.00/15.00 9.00/12.00 9.00/13.00 9.00/13.00

N 0.25 Max. N 0.25 Max. ------S 0.15 Min.*** Se 0.15 Min. ------------------Mo 2.00/3.00 Mo 2.00/3.00 Mo 3.00/4.00 Ti 5 x C Min. Cb + Ta 10 x C Min. Cb + Ta 10 x C Min. Ta 0.10 Max. Cb + Ta 8 x C min. 1.00% Max.

308/308 ELC 308/308 ELC 308/308 ELC 308/308 ELC 308/308 ELC 312 312 308/308 ELC 308 ELC 308/308 ELC 308/308 ELC 309 309 310 310 310/312 316/316 ELC 316 ELC 317/317 ELC 308 ELC/347 308 ELC/347 308 ELC/347

20Cb-3

0.06

2.00

1.00

19.00/21.00

32.50/35.00

1.00 1.00 1.00 1.25 1.25 1.00 1.00 1.00

0.50 1.00 1.00 1.00 1.00 1.00 1.00 1.00

11.50/13.00 11.50/13.50 11.50/13.50 12.00/14.00 12.00/14.00 12.00/14.00 15.00/17.00 11.50/14.00

----1.25/2.50 ------1.25/2.50 3.5/4.5

------S 0.15 Min.*** Se 0.15 Min. ----Mo 0.4-1.0

309 309 309/410 312/410 312/410 309/410 309/430 410NiMo

1.00 1.00 1.25 1.25 1.00 1.50

1.00 1.00 1.00 1.00 1.00 1.00

11.50/14.50 14.00/18.00 14.00/18.00 14.00/18.00 18.00/23.00 23.00/27.00

---

Al 0.10/0.30 --S 0.15 Min.*** Se 0.15 Min. --N 0.25 Max.

309/410 309/430 312/430 312/430 309/310 309/310

320LR

P

Glo

Turn

320LR

Martensitic

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals

403 410 414 416 416Se 420 431 CA6NM

0.15 0.15 0.15 0.15 0.15 Over 0.15 0.2 0.06

Ferritic 405 430 430F 430Se 442 446

0.08 0.12 0.12 0.12 0.2 0.2

* Single Values are Maximums Except as Noted. ** According to AISI Steel Products Manual, Stainless and Heat Resisting Steels. *** Molybdenum Content of up to 0.60% Permissible and is optional with the Producer.

-----------

If service allows Not regarded as weldable

STAINLESS STEEL SELECTION CHART

FIGURE 13

© COPYRIGHT 2000 THE ESAB GROUP, INC.

/410 Se /410Ch

(Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

LESSON V

5.11 WELDING DISSIMILAR STEELS Stainless steels are expensive and the higher the alloy content of the steel, the higher the cost. The most efficient design of a structure calls for the use of the higher alloy steels only where they are needed. Such a design may call for several different steels to be used. As mentioned above, there is no problem of electrode selection when welding stainless steels or any steel to

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

type of steel to another (called a transition weld) is made, care must be given to the selection

P

of the electrode used. 5.11.0.1

There are two general conditions and rules for electrode selection to weld dissimilar

Glo

steels. When the steels are similar metallurgically but dissimilar chemically, match the

electrode to the lower chemical composition or less expensive steel. For example, type 310 steel (25% chromium, 20% nickel) is sometimes welded to type 304 steel (19% chromium, 10% nickel). Both types are austenitic. Type 304 steel, which is welded with 308 electrodes, is less expensive, so that weld would be made with type 308 electrodes rather than type 310

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Go T

a steel of the same type. Simply match the electrode to the steels. When a change from one

a.

Lesson 5 Welding Filler Metals for Stainless Steels

Cu Ch Tab Con

Turn

electrodes. b.

When the steels to be jointed are different metallurgically and chemically, the

electrode is selected to provide a tough, crack resistant weld between the two steels. For

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

example, 304 stainless steel is frequently welded to mild structural steel. Corrosion resistance cannot be part of the problem because mild steel is on one side of the joint with practically no corrosion resistance compared to the stainless steel. If this weld is made with mild steel electrodes to match the mild steel side of joint, the weld metal would be enriched by the wash-

Lesson 8 Hardsurfacing Electrodes

in of chromium and nickel from the stainless side. This intermediate chrome-nickel is usually hard and crack sensitive. If the weld is made with type 308 electrodes to match the stainless steel side of the joint, the chromium and nickel contents of the weldment are diluted by the mild steel side of the joint to an intermediate level that would again probably be hard and crack

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals

sensitive. When welding mild steel to stainless steel, a proportion of 18% chromium and 8% nickel is desirable in the weld deposit to produce sound welds, with 17% chromium and 7% nickel being the minimum allowable amounts. 5.11.0.2

The following examples in Figure 14 show the results of making a transition weld of

mild steel to 304 stainless steel with three different electrodes.

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V

ELECTRODE

60%

Lesson 2 Common Electric Arc Welding Processes

Cu Ch Tab Con

20%

20%

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

304

MILD

P

STEEL 308 ELECTRODE ELECTRODE X 60%

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

CHROMIUM NICKEL

19.5 9.5

11.7 5.7

304 X 20% 18.0 8.0

3.6 1.6

MILD STEEL X 20% 0 0

0 0

WELD METAL 15.3 7.3

The composition of 15.3% chromium and 7.3% nickel does not meet the minimum 17-7% proportion. The weld metal will be mostly martensitic with a very small amount of ferrite. This structure is quite brittle. 310 ELECTRODE

Lesson 5 Welding Filler Metals for Stainless Steels

ELECTRODE X 60% CHROMIUM NICKEL

26.0 21.0

15.6 12.6

304 X 20% 18.0 8.0

3.6 1.6

MILD STEEL X 20% 0 0

0 0

WELD METAL 19.2 14.2

Turn

The composition of 19.2% chromium and 14.2% nickel is not near the 18/8 proportion. The weld metal would be fully austenitic and crack sensitive.

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

309 ELECTRODE ELECTRODE X 60% CHROMIUM NICKEL

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

23.0 13.0

13.8 7.8

304 X 20% 18.0 8.0

3.6 1.6

MILD STEEL X 20% 0 0

0 0

WELD METAL 17.4 9.4

The composition of 17.4% chromium and 9.4% nickel is close to the 18/8 proportion. The weld metal will be austenitic with some ferrite and a small amount of martensite to keep the weld metal from being tough and crack resistant. 309 is the best choice. ELECTRODE SELECTION - 304 STAINLESS TO MILD STEEL

Lesson 8 Hardsurfacing Electrodes

Glo

FIGURE 14

5.11.0.3

Normally the most severe dilution of the weld metal by the base metal is 40%. Thus,

Se Ch (Fa Dow

Se Doc (Sl Dow

the weld metal in the joint is comprised of 60% from the electrode and 40% from the base

Lesson 9 Estimating & Comparing Weld Metal Costs

metal as shown in Figure 14. In the case of butt joints between dissimilar steels, half of the dilution comes from each side of the joint, or 20% from each base metal. 5.11.0.4

Many times, type 310 and 312 electrodes are used erroneously for welding stain-

less to mild or low alloy steel. In many cases, not only can more dependable welds be made with 309 electrodes, but appreciable savings can be achieved because of their lower cost.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON V 5.11.0.5

Another common use of stainless steel filler metals is the overlaying or cladding of

Cu Ch Tab Con

less expensive steels with a layer of stainless. Mild steel tanks designed to hold corrosive

Lesson 2 Common Electric Arc Welding Processes

liquids may be lined with stainless steel in this manner. Usually, continuous bare or flux cored electrodes are used with an automated welding setup. Current and penetration must be controlled closely to limit dilution with the base metal. Sometimes it is necessary to deposit more than one layer to assure the correct analysis of the deposit.

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

5.11.0.6

The welding of stainless clad plate (produced by some steel mills) should also be

mentioned. Thicker sections may be welded with both mild steel and stainless electrodes, and

P

thinner sections may be welded only with stainless electrodes. Joint preparation, welding procedure and electrode selection will vary with the thickness and type of clad plate being

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

welded. Welding of clad plate is a specialized area of dissimilar metal welding and beyond

Glo

the scope of this course.

5.12 STAINLESS STEEL ELECTRODES AND FILLER METALS There are several different forms of stainless steel electrodes: covered, continuous solid bare, continuous flux cored and cut length bare welding rods.

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

5.12.1

Covered Stainless Electrodes - Arcaloy covered stainless steel electrodes are

classified according to the American Welding Society Filler Metal Specification A-5.4-92. As defined by that specification, the electrodes are classified by weld metal composition and type of welding current. For example, the AWS designation E308-15 means electrode (E), AISI

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

type 308 steel (20% chrome, 10% nickel) and direct current electrode positive (-15). If the classification reference were E308-16, it would indicate an electrode (E), AISI type 308 steel (308) and AC-DC electrode positive operation (-16 & -17). Arcaloy lime coated electrodes have the DC suffix -15, Arcaloy AC-DC electrodes have the suffix -16, and Arcaloy Plus electrodes use the -17 suffix.

Lesson 8 Hardsurfacing Electrodes

5.12.1.1

Arcaloy high alloy stainless steel covered electrodes are produced by extruding

carefully formulated and mixed coating material on a stainless steel core wire, thus ensuring constant weld metal properties and composition.

Lesson 9 Estimating & Comparing Weld Metal Costs

5.12.1.2

Arcaloy stainless steel electrodes have been among the leaders in the stainless

electrode industry for many years. The strict purchase specifications for the core wire and the covering materials, and the rigid quality control under which the Arcaloy electrodes are manufactured, have resulted in this position of leadership.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V

5.12.2

Arcaloy lime coated electrodes were among the earliest stainless steel elec-

Cu Ch Tab Con

trodes developed in the United States. Designed for welding with direct current, reverse

Lesson 2 Common Electric Arc Welding Processes

polarity only, the coating contains considerable amounts of limestone and fluorspar producing a fast freezing slag that facilitates welding in the vertical and overhead positions. The weld bead is slightly convex and moderately rippled. (See Figure 15). 5.12.2.1

Lesson 3 Covered Electrodes for Welding Mild Steels

Characterized by a strong globular arc, a moderate amount of spatter and slag

Go T

removal that is somewhat difficult, the lime type is not the most popular with the welding operators. However, it is the easiest to use stainless electrode for out-of-position welding. Also, the

P

convex bead can provide the necessary margin of safety in highly stressed joints in many cases.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

5.12.3

Arcaloy AC-DC Titania coated electrodes were the first such electrodes to

Glo

receive wide acceptance in this country. Designed to operate on alternating current as well as direct current, the coating contains dominant amounts of rutile (titania), medium amounts of limestone, and limited amounts of fluorspar. By far, the AC/DC type is the most popular of the

Lesson 5 Welding Filler Metals for Stainless Steels

coated stainless electrodes. Welders like to use it because of the smoother arc action, low amount of fine spatter and easy slag removal. Also, the bead is relatively flat, finely rippled and has good side-wall fusion (See Figure 15). Although used in all positions, vertical and overhead welding requires slightly more operator skill than with the lime types because the slag

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

5.12.4

Arcaloy "Plus" electrodes display characteristics not found in the conventional

lime and AC-DC Titania coatings. Designed to operate on DCEP or AC, this coating is specially formulated to operate on a broad range of current settings, and most significantly,

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

these electrodes perform their best at high heat inputs where conventional AC-DC electrodes tend to break down. 5.12.4.1

When operating at high currents, Arcaloy Plus electrodes deposit weld metal at

exceptional speeds with a smooth spray transfer. The bead profile is finely rippled, concave,

Lesson 8 Hardsurfacing Electrodes

and evenly feathered (See Figure 15). Spatter is minimal. The molten slag does not edge into the weld puddle, thereby assuring easy visibility of the arc transfer. 5.12.4.2

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

does not freeze as quickly.

Arcaloy Plus electrodes were developed for applications on dairy and food pro-

cessing equipment and chemical containers, to name a few, where the weld radius must be smooth and concave to prevent particle entrapment. When welding in the flat and horizontal fillet positions, the concave deposit and absence of surface irregularities make it ideal for applications where cosmetic appearance, speed, and final finishing are factors.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V

Lesson 2 Common Electric Arc Welding Processes

(-15) LIME CONVEX MODERATE RIPPLE

Lesson 3 Covered Electrodes for Welding Mild Steels

(-16) AC-DC FLAT LOW RIPPLE

(-17) PLUS CONCAVE MININUM RIPPLE

P FIGURE 15

5.12.4.3

Lesson 5 Welding Filler Metals for Stainless Steels

5.13 ARCALOY COVERED ELECTRODE PROPERTIES AND APPLICATIONS

The weld metal properties are similar for each of the three coating types: lime, AC-

Arcaloy 308L (AWS E308/308L-15 & -16), Arcaloy 308L Plus (AWS E308/308L-

Turn

17) - This extra low carbon composition is intended to weld Type 304L steels to prevent carbide participation. It can also be used to weld Types 321 and 347 steels. Typical chemical composition of weld metal is:

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels 5.13.2

Carbon

0.03%

Chromium

Nickel

9.7%

Manganese

19.1% 1.6%

Silicon

0.4%

Ferrite No.

8

Arcaloy 309L (AWS E309L-15 & -16), Arcaloy 309L Plus (AWS E309/309L-17)

- The low carbon content of Arcaloy 309 L weld metal makes it useful to weld low carbon overlay on carbon or low alloy steel to control carbide precipitation in the overlay. The chemical composition of the weld metal is the same as that of Arcaloy 309 except that the carbon content is 0.04% and the typical ferrite no. is 8.

Lesson 9 Estimating & Comparing Weld Metal Costs

Glo

DC and AC-DC Plus.

5.13.1

Lesson 8 Hardsurfacing Electrodes

Go T

WELD BEAD SHAPE ARCALOY COATED ELECTRODES

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Cu Ch Tab Con

5.13.3

Arcaloy 309 Cb (AWS 309Cb-15 & -16) - The addition of columbium to Type 309

weld metal improves its high temperature performance. It is also useful in welding Types 321 and 347 clad steels. The weld metal composition is the same as Type 309, except that 0.80% columbium is added and the ferrite no. is 8.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V 5.13.4

Arcaloy 309MoL (AWS E309Mo/309MoL-15 & -16) - The addition of 2¼% molyb-

Cu Ch Tab Con

denum to Type 309 weld metal makes the electrode useful for welding Type 316 clad steel. The

Lesson 2 Common Electric Arc Welding Processes

weld metal composition is the same as Type 309 except for the addition of 2.2% molybdenum and the ferrite no. is 8. 5.13.5

Lesson 3 Covered Electrodes for Welding Mild Steels

Arcaloy 310 (AWS 310-15 & -16) - The 25% chromium and 20% nickel content of

Arcaloy 310 has made it widely used for welding difficult-to-weld steels, especially where preheat cannot be used. Type 310 steel is used for high temperature applications and Arcaloy 310 electrodes have similar properties for that service. Typical chemical composition of the Carbon

5.13.6

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

0.15%

Nickel

21.0%

Silicon

0.4%

Chromium

26.0%

Manganese

1.8%

Ferrite No.

0

Lesson 9 Estimating & Comparing Weld Metal Costs

310 makes the electrode suitable for welding types 321 and 347 clad steels. The chemical composition of the weld metal is similar to Arcaloy 310 weld metal except that 0.8% columbium is added. The ferrite number remains 0. 5.13.7

Arcaloy 310Mo (AWS E310Mo-15 & -16) - The molybdenum addition to type 310

Turn

makes Arcaloy 310Mo suitable for welding type 316 clad steels. It has also been used for welding liners in pulp digesters in the paper industry. The weld metal composition is the same as Arcaloy 310 except that 2.5% molybdenum is added. The ferrite number remains 0. 5.13.8

Arcaloy 312 (AWS E312-15 & -16) - The extreme crack resistance of the 29%

chromium, 9% nickel electrode has made it widely used for welding very difficult-to-weld steels, such as spring steel and abrasion resisting steel. It has the highest tensile strength of

makes it unsuitable for service at high and low temperatures. Typical weld metal composition is:

5.13.9

Carbon

0.12%

Chromium

Nickel

9.5%

Manganese

Silicon

0.5%

Ferrite No.

29.0% 1.7% 30

Arcaloy 316L (AWS E316L-15 & -16), Arcaloy 316L Plus (AWS E316/316L-17) -

The extra low carbon content allows the weld metal to have minimum carbide precipitation. It is widely used in the welding of chemical equipment. The weld metal composition is the same

Lesson 10 Reliability of Welding Filler Metals

Glo

Arcaloy 310 Cb (AWS E310Cb-15 & -16) - The addition of columbium to Arcaloy

all the chromium-nickel stainless steel weld metals. The very high ferrite content, however,

Lesson 8 Hardsurfacing Electrodes

P

weld metal is:

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Go T

as Arcaloy 316 except that the carbon content is .035%.

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V 5.13.10

Arcaloy 316LF5 (AWS E316/316L-15 & -16) - is similar to Arcaloy 316 L, except

Cu Ch Tab Con

that the weld metal composition is balanced to give a ferrite number of at least 5 to control

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

weld cracking.

Typical weld metal composition is:

Carbon

0.35%

Nickel

5.13.11

12.5%

Silicon

0.45%

Ferrite No.

5 minimum

Chromium

19.0%

Manganese

1.6%

Molybdenum

2.25%

Arcaloy 317L (AWS E317/317L-15 & -16), Arcaloy 317L Plus (AWS E317/317L-17)

Go T

P

- This weld metal with higher molybdenum content than Arcaloy 316 has greater resistance to pitting corrosion. The molybdenum content also greatly improves weld metal crack resistance allowing it to be used to weld hardenable steels. Typical chemical composition of the

Glo

weld metal is: Carbon

0.06%

Nickel

Lesson 5 Welding Filler Metals for Stainless Steels

12.7%

Silicon

0.45%

Ferrite No.

5

Chromium

19.0%

Manganese

1.6%

Molybdenum

3.25%

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

5.13.12

Arcaloy 318 (AWS E318-15 & -16) - This electrode might also be called 316Cb

because it has about 0.8% columbium added to the weld metal of type 316 composition. It is used to weld 316L and 318 steels where carbide precipitation and the resultant intergranular corrosion would be a problem. Carbon

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

5.13.13

Lesson 10 Reliability of Welding Filler Metals

0.06%

Nickel

12.5%

Silicon Columbium

Chromium

18.5%

Manganese

1.6%

0.6%

Molybdenum

2.25%

0.8%

Ferrite No.

5

Arcaloy 320 (AWS E320-15), Arcaloy 320LR (AWS E320LR-16) - The complex

composition of this electrode is designed especially for welding similar steels — Carpenter Stainless #20 CB-3 (Wrought) and Durimet 20 (Cast). These steels are intended to resist corrosion by sulfuric acid.

Lesson 9 Estimating & Comparing Weld Metal Costs

Typical weld metal composition is:

Carbon

Typical chemical composition of the weld metal is: 0.03%

Nickel

32.5%

Silicon

Chromium

20.0%

Manganese

0.6%

0.4%

Molybdenum

2.0%

Columbium

0.5%

Copper

3.0%

Ferrite No.

0

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V

5.13.14

Lesson 2 Common Electric Arc Welding Processes

Cu Ch Tab Con

Arcaloy 347 (AWS E347-15 & -16), Arcaloy 347 Plus (AWS E347-17) - This

columbium bearing electrode is used to weld types 321 and 347 steels to prevent carbide precipitation and the resultant intergranular corrosion. Arcaloy 347 electrodes are also used to impact high strength to the weld metal at elevated temperatures.

Typical chemical composi-

tion of the weld metal is:

Go T Carbon

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

5.13.15

0.06%

Chromium

19.5%

Nickel

9.5%

Manganese

1.8%

Silicon

0.6%

Columbium

0.8%

Ferrite No.

6

Arcaloy 410 (AWS E410-16) - This straight chromium electrode deposits a marten-

P

Glo

sitic weld metal that is used extensively for corrosion and oxidation resistance at temperatures up to 1200°F. When welding type 410 steel with Arcaloy 410 electrodes, preheat must be used to prevent excess hardening of the heat affected zone and consequent cracking. Typical

Lesson 5 Welding Filler Metals for Stainless Steels

chemical composition of the weld metal is: Carbon

0.06%

Chromium

Manganese

0.4%

Silicon

12.0% 0.6%

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

5.14 ARCALOY BARE STAINLESS STEEL ELECTRODES Arcaloy bare stainless steel electrodes in continuous spools or coils and in cut lengths are manufactured under a carefully administered quality control system. Rigid purchase specifica-

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

tions and receiving instructions, as well as in-process inspection and analyses, insure the final product to be of the highest possible quality. Modern equipment in a modern plant assures that every form of electrode has the characteristics needed for each applicable welding process. Temper, cast, helix, and surface finish are closely controlled. The uniformity of these properties is essential to the maximum efficiency of the Gas Metal Arc Welding (GMAW), Gas

Lesson 8 Hardsurfacing Electrodes

Tungsten Arc Welding (GTAW), and Submerged Arc Welding (SAW) processes. 5.14.0.1

Arcaloy bare stainless electrodes and welding rods meet the requirements of AWS

Filler Metals Specification A5.9-93. That specification classifies the electrodes on the basis of

Lesson 9 Estimating & Comparing Weld Metal Costs

composition, such as ERXXX where ER represents electrode or rod, and XXX represents the AISI three-digit number of the composition, such as 308, 410, or 502. The chemical composition requirements are based on the electrode rather than the weld metal.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V 5.14.0.2

Arcaloy bare continuous solid stainless electrodes for gas metal arc or automated

Cu Ch Tab Con

gas tungsten arc welding are smooth drawn to a bright finish. They are chemically cleaned,

Lesson 2 Common Electric Arc Welding Processes

layer-wound on plastic spools, sealed in plastic bags, and packed in individual boxes. 5.14.0.3

Arcaloy bare solid stainless steel continuous electrodes for Submerged Arc Weld-

ing are furnished in the fully annealed (soft) condition for smoother, easier feeding. The elec-

Go T

trodes are random wound on fiber rims into coils, packaged in plastic bags, and boxed.

Lesson 3 Covered Electrodes for Welding Mild Steels

5.14.0.4

Arcaloy bare solid stainless welding rods are furnished in 36" (914 mm) cut lengths

P

for manual gas tungsten arc and oxyacetylene welding. Cut length rods are available with either flags or ink printed identification.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Glo

5.15 APPLICATIONS AND COMPOSITIONS OF ARCALOY BARE SOLID STAINLESS STEEL ELECTRODES

Lesson 5 Welding Filler Metals for Stainless Steels

5.15.1

Arcaloy ER308L (AWS ER308/308L) - is used for welding types 304L, 308L, 321,

and 347 steels. The extra low carbon content prevents carbide precipitation in the weld metal.

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Turn

The chemical composition of the electrode is the same as that of ER 308, except that the carbon content is 0.02%.

5.15.2

Arcaloy ER308LSi (AWS ER308Si/308LSi) - The higher silicon content increases

the wetting action of the weld metal, resulting in smooth uniform welds of good appearance.

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

The chemical composition is the same as ER 308 L, except that the silicon content is 0.75%.

5.15.3

Arcaloy ER309L (AWS ER309/309L) - The extra low carbon content provides

freedom from carbide precipitation. The electrode is used for low carbon overlay work. The chemical composition of the electrode is the same as ER 309, except that the carbon content

Lesson 8 Hardsurfacing Electrodes

is 0.03%.

5.15.4

Arcaloy ER310 (AWS ER310) - Used for welding type 310 stainless steel.

It is

also used for welding stainless steel to mild steel, for welding 304 clad steels and for stainless steel overlay welding on carbon steel. Typical chemical composition of the electrode is:

Lesson 9 Estimating & Comparing Weld Metal Costs

Carbon

0.12%

Nickel

21.5%

Silicon

0.4%

Chromium Manganese

26.5% 1.75%

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V 5.15.5

Arcaloy ER312 (AWS ER312) - is used for welding difficult-to-weld steels and for

Cu Ch Tab Con

welding stainless steel to mild steel. Typical chemical composition of the electrode is:

Lesson 2 Common Electric Arc Welding Processes

Carbon

0.11%

Chromium

Nickel

8.75%

Manganese

Silicon

0.4%

30.0% 1.75%

Go T Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

5.15.6

Arcaloy ER316L (ER316/316L) - used for welding types 316L and 318 steels to

avoid carbide precipitation. Chemical composition of the electrode is the same as the ER 316, except that the carbon content is 0.02%. 5.15.7

Arcaloy ER316LSi (AWS ER316Si/316LSi) - The higher silicon content improves

the wetting characteristics of the weld metal producing a smoother, better looking weld. tent is 0.75%. 5.15.8

Arcaloy ER347 (AWS ER347) - is used to weld types 321 and 347 steel in appli-

cations that require good resistance to corrosion. It is also used to weld type 347 steel for high strength at elevated temperatures. Typical chemical composition of the electrode is:

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

0.06%

Chromium

20.0%

Nickel

9.75%

Manganese

1.75%

Silicon

0.4%

Columbium

0.80%

CORED ELECTRODES ate without an external shielding gas. The carefully formulated mixture of alloys and shielding agents in the electrode core produces weld deposits of excellent appearance, mechanical properties, and radiographic quality. The electrode has low weld penetration that is ideal for overlay and buildup applications. Self shielding, high deposition rates, and reduced cleaning

Lesson 9 Estimating & Comparing Weld Metal Costs

time are all built into Core-Bright electrodes, resulting in maximum economy and optimum efficiency in the welding operation. 5.16.0.1

Core-Bright electrodes meet the requirements of AWS filler metal Specification

A5.22-95 for flux cored corrosion resisting chromium and chromium nickel steel electrodes.

Lesson 10 Reliability of Welding Filler Metals

Turn

Se Ch (Fa Dow

5.16 CORE-BRIGHT STAINLESS STEEL FLUX

Core-Bright electrodes are flux cored, self-shielding, continuous electrodes designed to oper-

Lesson 8 Hardsurfacing Electrodes

Glo

Chemical composition of the electrode is the same as ER 316 L, except that the silicon con-

Carbon

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

P

The specification classifies electrodes on the basis of composition, type of electrode, and type

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V of gas shield, if any, such as EXXXTX-X. The E indicates that it is a current carrying elec-

Cu Ch Tab Con

trode, and the XXX represents the AISI number of the composition, such as 308L, 3092, or

Lesson 2 Common Electric Arc Welding Processes

316L (the L signifying a low carbon type). The "T" indicates tubular or flux cored construction. The number following this "T" indicates positional characteristics; "1" equals All Position, "0" equals flat and horizontal only. The last digit indicates the intended shielding gas. The number "1" equares to carbon dioxide (CO ) as a shielding gas, a number "3" indicates that no exter2

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

nal shielding gas is necessary, a number "4" is 75 - 80% Argon (Ar) and balance carbon dioxide, and a number "5" indicates 100% Argon.

P

5.17 CORE-BRIGHT STAINLESS STEEL FLUX CORED ELECTRODE APPLICATIONS AND PROPERTIES 5.17.1

Core-Bright 307 (AWS E307To-3) - Designed to weld hardenable steels, such as

Carbon

0.10%

Chromium

Nickel

9.8%

Manganese

19.5% 3.8%

Silicon

0.6%

Molybdenum

1.0%

Turn

(Meets Military Spec MIL-E-13080B)

5.17.2

Core-Bright 308 Mo (AWS E308MoTo-3) - Welds hardenable steels such as

armor plate, has excellent toughness and crack resistance, and has been used to weld type 316 steel where carbide precipitation is not a problem. Chemical composition of the weld metal is:

Lesson 8 Hardsurfacing Electrodes

Carbon

0.11%

Chromium

Nickel

9.9%

Manganese

19.9% 1.54%

Silicon

0.6%

Molybdenum

2.1%

(Meets Military Spec MIL-E-13080B)

Lesson 9 Estimating & Comparing Weld Metal Costs

Glo

armor plate. The weld metal has excellent toughness and crack resistance. Typical chemical composition of the weld metal is:

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Go T

5.17.3

Core-Bright 308LTo (AWS E308LTo-3) - Welds AISI Steel types 301, 302, 304,

304L, 308, 321, and 347. It is used for welding chemical plant equipment. The typical chemical composition of the weld metal is:

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V Carbon Nickel

Lesson 2 Common Electric Arc Welding Processes

Silicon 5.17.4

0.025% 10.1%

Chromium Manganese

21.0%

Cu Ch Tab Con

1.6%

0.75%

Core-Bright 309L (AWS E309LTo-3) - This was designed primarily for depositing

stainless steel overlay on carbon steel. Can also be used for welding dissimilar steels. Typi-

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Go T

cal chemical composition of the weld metal is: Carbon

5.17.5

0.023%

Nickel

12.8%

Silicon

0.6%

Chromium Manganese

24.0% 1.6%

Core-Bright 316L (AWS E316LTo-3) - is used to weld steel types 316, 316L and

P

Glo

318. The 2¼% molybdenum increases the resistance to pitting corrosion from sulfur and chloride acids. Used in the rayon, dye and paper industries. Typical chemical composition of the weld metal is:

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Carbon

5.17.6

0.025%

Nickel

12.5%

Silicon

0.6%

Chromium

19.7%

Manganese

1.3%

Molybdenum

2.2%

Core-Bright 347 (AWS E347LTo-3) - This electrode is used to weld types 347,

304L, and 321 stainless steels where the maximum corrosion resistance is required. It is also used for high temperature high strength welds. The typical chemical composition of the weld metal is:

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

Carbon

0.028%

Nickel

10.1%

Silicon

0.7%

Chromium

20.2%

Manganese

1.5%

Molybdenum

0.57%

5.18 FERRITE CONTENT OF CORE-BRIGHT WELD METALS The ferrite content of Core-Bright weld metal is variable depending upon the nitrogen content of the weld deposit. Nitrogen is a very strong austenite former, said to be 30 times as strong as nickel. Only a small increase in nitrogen causes a considerable decrease in ferrite content. When welding with Core-Bright electrodes, the arc length may be varied by the arc voltage. A

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V longer arc length, caused by higher arc voltage, allows more nitrogen from the atmosphere to

Cu Ch Tab Con

enter into the weld metal and the ferrite content decreases. Lower arc voltage produces a

Lesson 2 Common Electric Arc Welding Processes

shorter arc length, allowing less nitrogen to pass into the weld metal, resulting in an increase of ferrite.

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

5.19 SHIELD-BRIGHT & SHIELD-BRIGHT X-TRA STAINLESS STEEL FLUX CORED ELECTRODES

P

Shield-Bright & Shield-Bright X-tra, like the Core-Bright flux cored stainless wires, are continu-

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

ous feed electrodes. Their smooth, spray-like metal transfer make them ideally suited for a

Glo

variety of welding positions. The uniquely designed chemical permits the use of either 100% CO or Argon-CO shielding. The deposited weld metal and superior mechanical properties 2

2

make them suitable for replacing manual covered electrodes. The economics in both deposi-

Lesson 5 Welding Filler Metals for Stainless Steels

tion efficiency and the low post-weld clean-up times is excellent. 5.19.0.1

Shield-Bright, all-position, and Shield-Bright X-tra, flat and horizontal electrodes

meet the requirements of AWS Filler Metal Specification A5.22-80 for flux cored corrosion resisting chromium and chromium nickel steel electrodes. The specific classification for this

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

series of electrodes is EXXXT-1. The ending digit 1 indicates the preference to CO or Argon2

CO shielding gas. 2

5.19.0.2

The Shield-Bright and Shield-Bright X-tra electrodes come in a variety of diameters

including .035", .045", and 1/16". They are packaged in an assortment of standard packages, such as 10, 33, and 50 lb spools and coils.

Se Doc (Sl Dow

5.20 SHIELD-BRIGHT & SHIELD-BRIGHT X-TRA STAINLESS STEEL FLUX CORED ELECTRODE APPLICATIONS AND PROPERTIES 5.20.1

Se Ch (Fa Dow

Shield-Bright 308L (AWS (E308LT1-1/T1-4) - For welding types 301, 302, 304(L),

308(L) grades of stainless. May also be used to weld types 321 and 347 if service temperatures do not exceed 500°F (260°C). Low carbon content minimizes carbide precipitation.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON V

Lesson 2 Common Electric Arc Welding Processes

75/25

CO

Carbon

0.032

0.034

Manganese

1.20

1.17

Chromium

19.50

19.20

Nickel

9.98

9.85

5

5

Ferrite No.

Cu Ch Tab Con

2

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

5.20.2

Shield-Bright 309L (AWS E309LT1-1/T1-4) - Designed for welding type 309

wrought or cast forms, but used extensively for welding type 304 to mild or carbon steel. Also used for welding 304 clad sheets and for applying stainless steel linings to carbon steel.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

75/25

CO

Carbon

0.034

0.034

Manganese

1.32

1.25

Chromium

22.63

22.39

Nickel

12.60

12.52

15

15

Ferrite No. 5.20.3

Glo

2

Shield-Bright 309LMo (AWS E309LMoT1-1/T1-4) - Designed for welding type

316 clad steels on the first pass in cladding steels or for welding dissimilar metals, such as

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

plants. 75/25

CO

Carbon

0.038

0.039

Manganese

1.14

.94

Chromium

23.10

22.84

Nickel

12.80

13.26

Molybdenum

2.65

2.58

17

17

Ferrite No. 5.20.4

2

Se Ch (Fa Dow

Se Doc (Sl Dow

Shield-Bright 316L (AWS E316LT1-1/T1-4) - For welding type 316 stainless.

Contains molybdenum which increases creep resistance at high temperatures and resists

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

molybdenum-containing austenitic steels to carbon steels used in paper mills and in power

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

P

pitting corrosion induced by sulfuric and sulfurous acids, chlorides, and cellulose solutions. Used widely in the rayon, dye, and paper-making industries.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON V

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels

75/25

CO

Carbon

0.038

0.032

Manganese

1.32

1.25

Chromium

18.52

18.28

Nickel

12.29

12.30

Molybdenum

2.47

2.47

6

6

Ferrite No. 5.20.5

Cu Ch Tab Con

2

Go T

Shield-Bright 317L (AWS E317LT1-1/T1-4) - Recommended for welding type 317

P

stainless with a maximum of 0.04% carbon in the weld deposit. The higher molybdenum content, as compared to type 316L, further reduces susceptibility to pitting corrosion. Used in

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

the pulp and paper industry and in other severe corrosion applications involving sulfuric and sulfurous acids and their salts.

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Glo

75/25

CO

Carbon

0.035

0.032

Manganese

1.31

1.20

Chromium

18.70

18.40

Nickel

12.60

12.50

Molybdenum

3.40

3.40

8

8

Ferrite No. 5.20.6

2

Turn

Shield-Bright 347 (AWS E347T1-1/T1-4) - Developed to weld types 347, 304,

304L and 321 stainless where service temperatures are below 600°F. The addition of colum-

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Carbon Manganese

Lesson 8 Hardsurfacing Electrodes

Se Ch (Fa Dow

bium helps minimize chromium carbide precipitation.

Chromium

75/25

CO

0.032

0.027

1.2

1.0

2

19.6

18.5

Nickel

9.6

9.7

Columbium

0.5

0.4

Ferrite No.

9

8.5

Se Doc (Sl Dow

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON V

5.21 ARCALOY NICKEL ALLOY COVERED WELDING

Cu Ch Tab Con

ELECTRODES - FEATURES AND DATA

Lesson 2 Common Electric Arc Welding Processes

5.21.1

Arcaloy 9N10 Nickel-Copper (Monel) Electrodes (AWS A5.11), Class

ENi-Cu-7) - Arcaloy 9N10 electrodes deposit a high nickel-copper alloy known by the tradename "Monel". The usability and arc stability on DC reverse polarity are excellent in all weld-

Lesson 3 Covered Electrodes for Welding Mild Steels

Arcaloy 9N10 electrodes are used for the welding of Monel (Nickel 70 - Copper 30) to itself and Monel to other alloys. The quality of the weld deposit makes the electrode ideal for Monel

A. Typical Mechanical Properties of the Weld Metal

Glo

As Welded

Lesson 5 Welding Filler Metals for Stainless Steels

Yield Point, psi

51,000

Tensile Strength, psi

79,500

% Elongation (2")

33

B. Typical Chemical Composition of Weld Metal

Carbon

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Nickel

0.04% 65.0%

Silicon Copper 5.21.2

0.7%

Titanium

0.7%

Manganese

3.3%

Aluminum

0.25%

Turn

Remainder

Arcaloy 8N12 Nickel-Chromium-Iron (Inconel) Electrodes (AWS A5.11, Class

ENiCrFe-3) - Arcaloy 8N12 electrodes deposit a nickel-chromium-iron alloy that is known as Inconel. The electrode was developed to provide excellent usability on direct current reverse polarity in all welding positions. There is little spatter and the complete coverage of slag is easily removed. Water clear X-rays are characteristic of 8N12 weld metal. Arcaloy 8N12

Lesson 8 Hardsurfacing Electrodes

P

overlay applications.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Go T

ing positions. There is no spatter and the complete slag cover is easily removed.

electrodes are primarily intended for welding structures subjected to very low temperature. The electrodes are also used for welding Inconel alloys to themselves and to many dissimilar alloys. It is useful for welding cryogenic structures because of the toughness of the weld metal at very low temperatures (-320°F).

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V

A. Typical Mechanical Properties of the Weld Metal

Cu Ch Tab Con

As Welded

Lesson 2 Common Electric Arc Welding Processes

Yield Point, psi

62,000

Tensile Strength, psi

96,600

% Elongation (2")

44

Charpy V-Notch Impact @ -320°F

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Go T

B. Typical Chemical Composition of Weld Metal

5.21.3

Carbon

0.03%

Chromium

14.0%

Titanium

0.60%

Manganese

6.10%

Silicon

0.75%

Iron

7.0%

Columbium

1.40%

Nickel - Remainder

P

Glo

Arcaloy Ni-9 (AWS A5.11, Class ENiCrMo-6) - Arcaloy Ni-9 is a nickel-chromium-

molybdenum alloy designed for welding 5% and 9% nickel steels for low temperature service.

Lesson 5 Welding Filler Metals for Stainless Steels

The lime type covering on the 3/32", 1/8", and 5/32" sizes has excellent all-position welding characteristics on direct current reverse polarity. The weld metal has good crack resistance. The titania covering on the 3/16" size for AC/DC welding is outstanding in the horizontal and flat welding positions. The heavy covering, containing many of the alloying elements, further

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

5.21.3.1

The weld metal combines excellent notch toughness at temperatures as low as -

320°F with the thermal coefficient of expansion and tensile strength comparable to the cryogenic alloys usually welded with it. Arcaloy Ni-9 deposits good radiographic quality welds.

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

The good wetting action, smooth metal transfer, and low spatter level are all features of this electrode. 5.21.3.2

Arcaloy Ni-9 electrodes are primarily used to weld the 5% and 9% nickel steels in

structures intended for cryogenic service, such as storage vessels and tanks for Liquified

Lesson 8 Hardsurfacing Electrodes

Natural Gas (LNG) and Liquid Oxygen (LOX). They can also be used for welding Inconel and Inconel cladding to mild steel. A. Typical Mechanical Properties of the Weld Metal

Lesson 9 Estimating & Comparing Weld Metal Costs

As Welded Yield Point, psi

60,000

Tensile Strength, psi

96,500

% Elongation (2")

Lesson 10 Reliability of Welding Filler Metals

Turn

improves the arc direction and increases the deposition rate.

Charpy V-Notch Impact @ -320°F

38 50 ft-lbs

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V

B. Typical Chemical Composition of Weld Metal Carbon

Lesson 2 Common Electric Arc Welding Processes

Nickel

5.21.4

Chromium Manganese

14.9% 2.8%

Silicon

0.5%

Iron

6.1%

Columbium

1.40%

Tungsten

1.4%

Chromium

Lesson 3 Covered Electrodes for Welding Mild Steels

0.04% 65.0%

Cu Ch Tab Con

14.90%

Go T

Arcaloy Ni-12 (AWS A5.11, Class ENiCrFe-3)

P

Arcaloy Ni-12 is a nickel-chromium-iron alloy with a high conductivity nickel core wire that permits the use of higher welding currents for increased deposition rates and superior fusion.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

The lime type covering on the 3/32", 1/8", and the 5/32" sizes gives improved crack resistance and excellent welding in all positions on DC reverse polarity. The titania type covering

Glo

on the 3/16" size is designed for horizontal and flat position welding with AC/DC. The heavy covering, containing many of the alloying elements, further improves the arc direction and adds to the deposition rate.

Lesson 5 Welding Filler Metals for Stainless Steels

5.21.4.1

The weld metal of this cryogenic composition has excellent notch toughness @ -

320°F. It also has thermal expansion and tensile strength comparable to the alloy metals usually used in this service. The weld metal is water clear by X-ray.

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

5.21.4.2

Turn

Arcaloy Ni-12 is used for joining the nickel-chromium-iron alloys and metal combina-

tions where thermal shock is a problem. Typical applications include coke ovens and nuclear parts. A. Typical Mechanical Properties of the Weld Metal

Se Ch (Fa Dow

As Welded Yield Point, psi

53,500

Tensile Strength, psi

90,000

% Elongation (2")

41

% Reduction of Area

55

Charpy V-Notch Impact @ -320°F

63 ft-lbs

Se Doc (Sl Dow

B. Typical Chemical Composition of Weld Metal

Lesson 9 Estimating & Comparing Weld Metal Costs

Carbon Nickel

0.04% 70.35%

Silicon

0.4%

Columbium

1.77%

Chromium

15.2%

Manganese

6.1%

Iron

7.67%

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

LESSON V

5.22 ELECTRODES FOR WELDING CAST IRON INTRODUCTION TO CAST IRON

Cu Ch Tab Con

Cast iron is a high carbon alloy of iron, usually containing 3.5% carbon or more. There are several categories of cast iron. The most common is called gray iron because much of the carbon has separated from the iron and is scattered through the material in the form of small

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

flakes of free graphite. This graphite causes a broken surface to appear gray. 5.22.0.1

If gray iron is cooled rapidly from the molten condition, the carbon remains tied up

P

with the iron as a very hard iron carbide called cementite. The presence of the cementite makes the iron mass very hard and brittle. A broken surface appears white; hence, the name

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

"white iron". White iron is not weldable. 5.22.0.2

Glo

When the white iron is reheated to a high temperature, the iron carbide is taken in

solution. If the heated iron is cooled very slowly, the carbon stays in solution in the iron and the result is "malleable iron".

Lesson 5 Welding Filler Metals for Stainless Steels

5.22.0.3

When small amounts of certain elements, such as magnesium, are added to the

molten iron, the magnesium acts as nuclei for the carbon to form small spheres or nodules on cooling. This is called "nodular iron".

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

5.22.0.4

Turn

Gray iron is not ductile; white iron is very hard and brittle; malleable iron is reason-

ably soft and ductile; and nodular iron is ductile. 5.22.1

Nickel-Arc 55 (AWS A5.15 Class ENiFe-CI) - Nickel-Arc 55 electrodes have core

wire of 55% nickel and 45% iron. This combination has been developed especially to deposit crack free welds in cast iron. The electrodes have good usability on both alternating current and direct current. The high nickel weld metal has the ability to absorb the carbon that is washed in from the cast iron and still remain tough and ductile. The weld metal is easily machined.

Lesson 8 Hardsurfacing Electrodes

5.22.1.1

Sound, crack free repair and joining welds can be made in gray, malleable and

nodular iron with Nickel-Arc 55 electrodes. If the part to be welded is a used casting, the oil and grease should be burned out before welding in order to avoid porosity.

Lesson 9 Estimating & Comparing Weld Metal Costs

A. Typical Properties of Nickel-Arc Weld Metal: Tensile Strength (psi)58,500 Hardness across weld in gray iron Machinability

Lesson 10 Reliability of Welding Filler Metals

Color Match

90-100 Rb

Excellent Good

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V

5.22.2

Nickel-Arc 550 (AWS A5.15, Class ENiFe-CI-A) - Nickel-Arc 550 electrode is

Cu Ch Tab Con

made with 55% nickel and 45% iron core wire. The coating is specially designed to give

Lesson 2 Common Electric Arc Welding Processes

smooth, stable arcs on both direct and alternating current. Nickel-Arc 550 is also designed to provide superior resistance to overheating, allowing maximum deposition efficiency during the welding operation. A. Typical Properties of Nickel-Arc Weld Metal:

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

5.22.3

Tensile Strength (psi)

58,500

Hardness across weld in gray iron

90-100 Rb

Machinability

Excellent

Color Match

Good

Go T

P

Nickel-Arc 99 (AWS A5.15, Class ENi-CI) - Nickel-Arc 99 electrodes are made

Glo

with pure nickel core wire. The high nickel content of the deposited weld metal absorbs the carbon from the cast iron and remains tough and ductile. The electrode has good welding characteristics with smooth stable arc on both direct current and alternating current.

Lesson 5 Welding Filler Metals for Stainless Steels

Nickel-Arc 90 produces sound crack-free welds in gray, malleable and nodular iron. It is particularly valuable for welding or overlay of cast iron when high nickel deposits are required or when ease of machining the weld area is important. Preheat, interpass temperature, and cooling rate after welding depends on the type and design of the object to be welded. When

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Turn

welding cavities in cast iron, wide weaving and heavy weld beads should be used. Welding 10-20°uphill helps deposit thicker weld beads that better resist cracking. A. Typical Properties of Nickel-Arc Weld Metal: Tensile Strength (psi)69,900

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Hardness across weld in gray iron Machinability Color Match 5.22.4

Lesson 8 Hardsurfacing Electrodes

Se Ch (Fa Dow

90-100 Rb

Excellent Good

Nicore 55 (Meets chemistry requirements of AWS ENiFe-CI) - Nicore 55 is a

"wire within a wire" flux cored electrode with approximately 50.5% iron and 48% nickel, providing an excellent match for the coefficient of expansion exhibited by cast irons. The wire produces a light slag that is easily removed enhancing visual weld inspection.

Lesson 9 Estimating & Comparing Weld Metal Costs

5.22.4.1

Because of the continuous nature of this wire, operating factor, arc time, and depo-

sition efficiency are all improved over the conventional manual stick electrodes. This electrode is ideally suited for the repair and joining of various types of cast irons. The machinability characteristics are similar to that of the 55-grade covered electrodes. DC (electrode positive) is the recommended current.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V 5.22.4.2

The shielding gas should be 98% argon-2% oxygen. Welding heavier sections or

Cu Ch Tab Con

the application of cast iron to carbon steel requires the use of 400-600°F preheat.

Lesson 2 Common Electric Arc Welding Processes

5.22.4.3

standard packages ranging from 10 & 33 lb spools to 60 lb coils. 5.22.5

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Nicore 55 is available in a variety of sizes from .035" - 3/32" diameters and many

Cupro Nickel Electrodes (AWS A5.6, Class ECuNi) - This 70% copper, 30%

nickel electrode is designed to provide outstanding weld metal in welding 70-30 and 90-10 copper-nickel alloys with direct current reverse polarity. The electrode can be used in all welding positions. Slag removal is easy and complete from the smooth weld beads. Weld

Go T

P

deposits are sound by X-ray and have excellent strength and ductility. 5.22.5.1

The primary uses for copper-nickel alloys are in the fabrication of ship condensers,

Glo

distiller tubes, heat exchangers, and other items exposed to sea water corrosion. A. Typical Mechanical Properties of Weld Metal: As Welded

Lesson 5 Welding Filler Metals for Stainless Steels

Yield Point (psi)

Tensile Strength (psi)52,000 % Elongation (2")

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

35,500

Turn

40

B. Typical Chemical Composition of the Weld Metal: Carbon

0.3%

Manganese

1.3%

Silicon

0.7%

Iron

0.55%

Copper

68.0%

Nickel

30.0%

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON V

APPENDIX A

Lesson 2 Common Electric Arc Welding Processes

Cu Ch Tab Con

LESSON V - GLOSSARY OF TERMS

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

Austenite

-

High temperature crystal structure of carbon steel or the room temperature structure of chrome-nickel steel.

Martensite

-

P

The hard phase that develops on rapid cooling of carbon and low alloy steels.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Glo Ferrite

The normal crystal structure of low carbon steel at room temperature.

Transition Temperature

Lesson 5 Welding Filler Metals for Stainless Steels

-

-

The temperature at which the crystal structure of steel changes, usually in the range of 1500-1600°F.

Carbide Precipitation

-

The formation of chromium carbide in austenitic stainless steel that allows intergranular corrosion in corrosive service.

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Ferrite in Austenitic

-

Stainless Steel

Turn

The magnetic finely dispersed crystal structure in austenitic steels that causes the austenite grains to become smaller and crack resistant.

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Ferrite Number

-

Ferrite Numbers (FN) are the current industry accepted figures for specifying ferrite content in austenitic stainless steel weld metal, as approved by the Welding Research Council (WRC), American Welding Society (AWS) and other organizations. Adopted during the 1970's, "ferrite number" is not to be confused with "Per-

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

cent Ferrite" that is still used in some cases.

Metallurgically

-

Similar Steels Preheat

Multiple steel compositions that have essentially the same crystal structure, such as austenite or ferrite.

-

The heating of the parts of a structure to be welded before welding is started.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON V

Interpass Temperature

-

The lowest temperature at which the part being welded is held

Cu Ch Tab Con

during welding .

Lesson 2 Common Electric Arc Welding Processes

Temper of continuous welding electrodes

-

The sfiffness or strength of the electrode.

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

Cast of continuous

Helix of continuous

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

-

The diameter of the circle a length of the electrode assumes when

welding electrodes

-

The tendency of a length of the electrode to form a spiral when

welding electrodes

Cryogenic Temperatures

P

lying free on a smooth surface.

lying free on a smooth surface.

-

Glo

Extremely low temperatures usually associated with liquified gases in the range of -100°F to -400°F.

Lesson 5 Welding Filler Metals for Stainless Steels

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Se Ch (Fa Dow

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Se Doc (Sl Dow

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Cu Ch Tab Con

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

BASIC WELDING FILLER METAL TECHNOLOGY

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

P

Glo

A Correspondence Course

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Go T

LESSON IX ESTIMATING AND COMPARING WELD METAL COSTS

Turn

Se Ch (Fa Dow

Se Doc (Sl Dow

ESAB

ESAB Welding & Cutting Products

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals ©COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

Cu Ch Tab Con

TABLE OF CONTENTS LESSON IX ESTIMATING AND COMPARING WELD METAL COSTS

Lesson 2 Common Electric Arc Welding Processes

Go T Lesson 3 Covered Electrodes for Welding Mild Steels

Section Nr.

Section Title

Page

9.1

Introduction ..................................................................................................

1

9.2

Factors For Cost Formulas ......................................................................

2

9.2.1

Labor & Overhead .........................................................................................

2

9.2.2

Deposition Rate .............................................................................................

2

9.2.3

Operating Factor ............................................................................................

3

9.2.4

Deposition Efficiency ....................................................................................

4

9.2.5

Deposition Efficiency of Coated Electrodes ..............................................

4

9.2.6

Efficiency of Flux Cored Wires .....................................................................

6

9.2.7

Efficiency of Solid Wires for GMAW ............................................................

6

9.2.8

Efficiency of Solid Wires for SAW ...............................................................

7

9.2.9

Cost of Electrodes, Wires, Gases and Flux ................................................

7

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

9.2.10

Cost of Power ................................................................................................

7

9.3

Deposition Data Tables .............................................................................

8

9.4

Cost Calculations .......................................................................................

12

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

9.4.1

Calculating the Cost Per Pound of Deposited Weld Metal .......................

12

9.4.2

Calculating the Cost Per Foot Of Deposited Weld Metal .........................

14

9.5

Cost Calculations - Example 2 ................................................................

15

9.6

Comparing Weld Metal Costs ..................................................................

17

9.6.1

Example 3 .......................................................................................................

19

9.7

Other Useful Formulas ..............................................................................

20

9.8

Amortization of Equipment Costs ..........................................................

21

Appendix A Lesson IX Test Questions .........................................................................

22

Appendix B Problem 1 Worksheet ................................................................................

26

Appendix C Problem 2 Worksheet ................................................................................

27

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals

P

Glo

Turn

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels

LESSON IX

ESTIMATING AND COMPARING WELD METAL COSTS

Cu Ch Tab Con

9.1 INTRODUCTION Estimating the costs of depositing weld metal can be a difficult task because of the many

Go T

variables involved. Design engineers must specify the type and size of weld joint to withstand the loads that the weldment must bear. The welding engineer must select the welding process,

P

and type of filler metal that will provide the required welds at the least possible cost. With wages and the cost of operations rising, selection of the process that deposits weld metal

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

most expediently must be carefully considered. Labor and overhead account for approxi-

Glo

mately 85% of the total welding cost. 9.1.0.1

Welding costs may be divided into two categories; the “fixed” costs involved regard-

less of the filler metal or welding process selected, and those related to a specific welding

Lesson 5 Welding Filler Metals for Stainless Steels

process. Fixed costs entail material handling, joint preparation, fixturing, tacking, preheating, weld clean-up and inspection. Although some of these items will be affected by the process and filler metal chosen, they are a necessary part of practically all welding operations. Calculating these costs is best left to the manufacturer since they will depend upon his capabilities

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Turn

and equipment. The cost of actually depositing the weld metal however, will vary considerably with the filler metal and welding process selected. This cost element is influenced by the user’s labor and overhead rates, deposition rate and efficiency of the filler metal, operating factor, and cost of materials and power.

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

9.1.0.2

This lesson will cover cost estimating for steel weldments produced by the four most

common arc welding processes in use today: shielded metal-arc welding, gas metal-arc welding, flux cored arc welding and submerged arc welding. Gas tungsten arc welding will not be considered here because the variables, such as deposition rate and efficiency, are depen-

Lesson 8 Hardsurfacing Electrodes

dent on operator technique, stub use, etc. The GTAW process is a relatively costly method of depositing weld metal, and is usually chosen for weld quality or material thickness and composition limitations, rather than economy. 9.1.0.3

Lesson 9 Estimating & Comparing Weld Metal Costs

Large firms will frequently conduct their own deposition tests and time studies to

determine welding costs, but many smaller shops do not know the actual cost of depositing weld metal. 9.1.0.4

In estimating welding costs, all attempts should be made to work with accurate data,

which in some cases is difficult to secure. For this reason, this lesson contains charts, graphs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IX and tables that provide average values that you may use. Electrode manufacturers will usually

Cu Ch Tab Con

supply the deposition data you need through their Technical Services Department, if it is not

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels

already published in their literature.

Go T

9.2 FACTORS FOR COST FORMULAS 9.2.1

Labor and Overhead - Labor and overhead may be considered jointly in your

P

calculations. Labor is the welder’s hourly rate of pay including wages and benefits. Overhead includes allocated portions of plant operating and maintenance costs. Weld shops in manu-

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

facturing plants normally have established labor and overhead rates for each department. shows how labor and overhead may vary and suggests an average value to use in your calculations when the actual value is unknown.

Lesson 5 Welding Filler Metals for Stainless Steels

HOURLY WELDING LABOR & OVERHEAD RATES Small Shops Large Shops Average

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

$10.00 to $25.00/hr. $25.00 to $50.00/hr $30.00/hr.

Turn

APPROXIMATE LABOR AND OVERHEAD RATES FIGURE 1

9.2.2

Deposition Rate - The deposition rate is the rate that weld metal can be deposited

by a given electrode or welding wire, expressed in pounds per hour. It is based on continuous operation, not allowing time for stops and starts caused by inserting a new electrode, cleaning slag, termination of the weld or other reasons. The deposition rate will increase as the welding current is increased.

Lesson 8 Hardsurfacing Electrodes

9.2.2.1

When using solid or flux cored wires, deposition rate will increase as the electrical

stick-out is increased, and the same amperage is maintained. True deposition rates for each welding filler metal, whether it is a coated electrode or a solid or flux cored wire, can only be

Lesson 9 Estimating & Comparing Weld Metal Costs

Glo

Labor and overhead rates can vary greatly from plant to plant, and also with location. Figure 1

established by an actual test in which the weldment is weighed before welding and then again after welding, at the end of a measured period of time. The tables in Figures 8-11 contain average values for the deposition rate of various types of welding filler metals. These are based on welding laboratory tests and published data.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IX 9.2.3

Operating Factor - Operating factor is the percentage of a welder’s working day

Cu Ch Tab Con

that is actually spent welding. It is the arc time in hours divided by the total hours worked. A

Lesson 2 Common Electric Arc Welding Processes

45% (.45) operating factor means that only 45% of the welder’s day is actually spent welding. The balance of time is spent installing a new electrode or wire, cleaning slag, positioning the weldment, cleaning spatter from the welding gun, etc. 9.2.3.1

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

operating factor is not known, an average of 30% may be used for cost estimates when weld-

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

9.2.3.2

When welding with solid wires (GMAW) or metal cored welding (MCAW) using the

semi-automatic method, operating factors ranging from 45%-55% are easily attainable. Use

Glo

50% for cost estimating purposes. For welds produced by flux cored arc welding (FCAW) semi-automatic- ally, the

operating factor usually lies between 40%-50%. For cost estimating purposes, use a 45% operating factor. The estimated operating factor for FCAW is about 5% lower than that of GMAW to allow for slag removal time. In semi-automatic submerged arc welding, slag removal and loose flux handling

Turn

must be considered. A 40% operating factor is typical for this process. 9.2.3.5

Automatic welding using the GMAW, FCAW, and SAW processes, requires that

each application be studied individually. Operating factors ranging from 50% to values approaching 100% may be obtained depending on the degree of automation. 9.2.3.6

The chart in Figure 2 shows average operating factor values for the various welding

processes that may be used for cost estimating when the actual operating factor is not known.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

P

ing with the shielded metal arc welding process.

9.2.3.4

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Go T

15%-40% depending upon material handling, fixturing and operator dexterity. If the actual

9.2.3.3

Lesson 5 Welding Filler Metals for Stainless Steels

When using coated electrodes, (SMAW) the operating factor can range from

WELDING PROCESS SMAW

+ * GMAW

30%

50%

*FCAW 45%

*SAW 40%

*Semi-Automatic Only + Metal Cored Wires are Included APPROXIMATE OPERATING FACTOR FIGURE 2

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON IX 9.2.4

Deposition Efficiency - Deposition efficiency is the relationship of the weight of

Cu Ch Tab Con

the weld metal deposited to the weight of the electrode (or wire) consumed in making a weld.

Lesson 2 Common Electric Arc Welding Processes

It can be accurately determined only by making a timed test weld, and carefully weighing the weldment and the electrode or wire, before and after welding. The efficiency can then be calculated by the formula: Deposition efficiency

=

Weight of Weld Metal

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

÷

Weight of Electrode Used

Go T

(or) Deposition Rate (lbs/hr)

9.2.4.1

÷

Burn-off Rate (lbs/hr)

P

The deposition efficiency tells us how many pounds of weld metal can be expected

from a given weight of the electrode or welding wire purchased. As an example, 100 pounds

Glo

of a flux cored electrode with an efficiency of 85%, will produce approximately 85 pounds of weld metal, while 100 pounds of coated electrode with an efficiency of 65%, will produce approximately 65 pounds of weld metal, less the weight of the stubs discarded, as described

Lesson 5 Welding Filler Metals for Stainless Steels

below. 9.2.5

Coated Electrodes - The deposition efficiency of coated electrodes by AWS

definition, and in published data, does not consider the loss of the unused electrode stub that

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

application. Long continuous welds are usually conducive to short stubs while on short intermittent welds, stub length tends to be longer. Figure 3 illustrates how the stub loss influences the electrode efficiency when using coated electrodes. 9.2.5.1

In Figure 3, a 14” long by 5/32” diameter E7018 electrode at 140 amperes is con-

sidered. It is 75% efficient, and a two inch stub loss is assumed. The 75% efficiency applies

12" LENGTH OF ELECTRODE CONSUMED

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

2" STUB LENGTH

AMOUNT THAT BECOMES WELD METAL (LENGTH CONSUMED X EFFICIENCY)

LOST TO SLAG,SPATTER & FUMES

9" 14"

DEPOSITION EFFICIENCY = 75% actual efficiency, including stub loss = 9 ÷ 14 = 64.3%

Lesson 10 Reliability of Welding Filler Metals

Turn

is discarded. This is understandable since the stub length can vary with the operator and the

FIGURE 3 © COPYRIGHT 2000 THE ESAB GROUP, INC.

-4-

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IX only to the 12” of the electrode consumed in making the weld, and not to the two inch stub.

Cu Ch Tab Con

When the two inch stub loss and the 25% that is lost to slag, spatter and fumes are consid-

Lesson 2 Common Electric Arc Welding Processes

ered, the efficiency minus stub loss is lowered to 64.3%. This means that for each 100 pounds of electrodes purchased, you can expect an actual deposit of approximately 64.3 pounds of weld metal if all electrodes are used to a two inch stub length. 9.2.5.2

Lesson 3 Covered Electrodes for Welding Mild Steels

The formula for the efficiency including stub loss is important, and must always be

Go T

used when estimating the cost of depositing weld metal by the SMAW method. Figure 4 shows the formula used to establish the efficiency of coated electrodes including stub loss. It

P

is based on the electrode length, and is slightly inaccurate, i.e. it does not take into consideration that the electrode weight is not evenly distributed, due to the flux being removed from the

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

electrode holder end. (Indicated by the dotted lines in Figure 3.) Use of the formula will result

Glo

in a 1.5-2.3% error that will vary with electrode size, coating thickness and stub length. The formula however, is acceptable for estimating purposes. 9.2.5.3

Lesson 5 Welding Filler Metals for Stainless Steels

For the values given in Figure 3 the formula is:

EFFICIENCY = MINUS STUB LOSS

(ELECTRODE LENGTH — STUB LENGTH) X DEPOSITION EFFICIENCY ELECTRODE LENGTH

Turn

EFFICIENCY MINUS STUB LOSS

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

FIGURE 4

Efficiency - Stub Loss

=

(14-2) x .75 14

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

=

Se Ch (Fa Dow

12 x .75 14

=

9 14

Lesson 8 Hardsurfacing Electrodes

=

.6429 or 64.3%

In the above example, the electrode length is known, the stub loss must be estimated, and the efficiency taken from the tables in Figures 8 and 9. Use an average stub loss of three inches for coated electrodes if the actual shop practices concerning stub loss are not known.

Lesson 9 Estimating & Comparing Weld Metal Costs

9.2.5.4

The following stub loss correction table will assist in your determination of coated

electrode efficiencies. Figure 5 lists various efficiencies at a given stub loss.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IX

Lesson 2 Common Electric Arc Welding Processes

ELEC.

DEPOSITION

2"

3"

4"

5"

LENGTH

EFFICIENCY

STUB

STUB

STUB

STUB

60%

50.0%

45.0%

40.0%

35.0%

65%

54.2%

48.7%

43.3%

37.9%

70%

58.3%

52.5%

46.6%

40.8%

75%

62.5%

56.2%

50.0%

43.7%

80%

66.6%

60.0%

53.3%

46.6%

60%

51.4%

47.1%

42.8%

38.5%

65%

55.7%

51.1%

46.4%

41.8%

12"

STUB LOSS CORRECTION

Lesson 3 Covered Electrodes for Welding Mild Steels

TABLE FOR COATED ELECTRODES

14"

EFFICIENCY INCLUDING STUB LOSS FIGURE 5

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

18"

9.2.6

Lesson 5 Welding Filler Metals for Stainless Steels

70%

60.0%

55.0%

50.0%

45.0%

75%

64.3%

58.9%

53.6%

48.2%

80%

68.5%

62.8%

57.1%

51.4%

60%

53.3%

50.0%

46.6%

43.3%

65%

57.7%

54.2%

50.5%

46.9%

70%

62.2%

58.3%

54.4%

50.5%

75%

66.6%

62.5%

58.3%

54.2%

80%

71.1%

66.6%

62.2%

57.7%

Cu Ch Tab Con

Go T

P

Glo

Efficiency of Flux Cored Wires - Flux cored wires have a lower flux-to-metal ratio

than coated electrodes, and thereby, a higher deposition efficiency. Stub loss need not be considered since the wire is continuous. The gas shielded wires of the E70T-1 and E70T-2 types have efficiencies of 83%-88%. The gas shielded basic slag type (E70T-5) is 85%-90% efficient with CO2 as the shielding gas, and the efficiency can reach 92% when a 75% argon,

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

25% CO2 gas mixture is used. Use the efficiency figures in Figure 9 for your calculations if the actual values are not known. 9.2.6.1

The efficiency of the self-shielded types of flux cored wires has more variation

because of the large variety of available types that have been designed for specific applications. The high deposition general purpose type, such as E70T-4, is 81%-86%, depending on wire size and electrical stick-out. The chart in Figure 9 shows the optimum conditions for each wire size and may be used in your calculations. 9.2.7

Lesson 8 Hardsurfacing Electrodes

Efficiency of Solid Wires for GMAW - The efficiency of solid wires in GMAW is

very high and will vary with the shielding gas or gas mixture used. Using CO2 will produce the most spatter and the average efficiency will be about 93%. Using a 75% argon-25% CO2 gas mixture will result in somewhat less spatter, and an efficiency of approximately 96% can be expected. A 98% argon-2% oxygen mixture will produce even less spatter, and the average

Lesson 9 Estimating & Comparing Weld Metal Costs

Turn

efficiency will be about 98%. Stub loss need not be considered since the wire is continuous. Figure 6 shows the average efficiencies you may use in your calculations if the actual efficiency is not known.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

.045" - 1/16"

Lesson 1 GMAW The Basics of Arc Welding

LESSON IX 9.2.8

Efficiency of Solid Wires for SAW - In submerged arc welding there is no spatter

Cu Ch Tab Con

loss and an efficiency of 99% may be assumed. The only loss during welding is the short

Lesson 2 Common Electric Arc Welding Processes

piece the operator must clip off the end of the wire to remove the fused flux that forms at the termination of each weld. This is done to assure a good start on the succeeding weld.

Go T Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Shielding Gas

Efficiency Range

Average Efficiency

Pure CO2

88 - 95%

93%

94 - 98%

96%

97 - 98.5%

98%

98% Ar - 2% O2

P

Glo

DEPOSITION EFFICIENCIES - GAS METAL ARC WELDING CARBON AND LOW ALLOY STEELS FIGURE 6

9.2.9

Cost of Electrodes, Wires, Gases and Flux - You must secure the current cost

per pound of the electrode or welding wire, plus the cost of the shielding gas or flux if applicable, from the supplier. The shielding gas flow rate varies slightly with the type of gas used. The flow rates in Figure 7 are average values whether the shielding gas is an argon mixture or

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Turn

pure CO2. Use these in your calculations if the actual flow rate is not available. In the submerged arc process (SAW) the ratio of flux to wire consumed in the weld is approximately 1 to 1 by weight. When the losses due to flux handling and flux recovery systems are considered, the average ratio of flux to wire is approximately 1.4 pounds of flux for each pound

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

of wire consumed. If the actual flux-to-wire ratio is unknown, use the 1.4 for cost estimating.

FCAW/MCAW Wire Diameter

Lesson 8 Hardsurfacing Electrodes

CFH

.035" 30

35

.045"

1/16"

5/64" - 1/8"

35

40

45

APPROXIMATE SHIELDING GAS FLOW RATE - CUBIC FEET PER HOUR FIGURE 7

Lesson 9 Estimating & Comparing Weld Metal Costs

9.2.10

Cost of Power - Cost of electrical power is a very small part of the cost of deposit-

ing weld metal and in most cases is less than 1% of the total. It will be necessary for you to know the power cost expressed in dollars per kilowatt- hour ($/kWh) if required for a total cost estimate.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

LESSON IX

9.3

DEPOSITION DATA CHARTS

9.3.1

SHIELDED METAL ARC WELDING - Coated Electrodes.

E6010 DEPOSITION

EFFICIENCY

ELECTRODE

AMPS

RATE lbs/hr

%

DIAMETER

AMPS

RATE lbs/hr

%

3/32 1/8

75 100 130 140 170 160 190 190 230

1.5 2.1 2.3 2.8 2.9 3.3 3.5 4.5 5.1

72.0% 76.3% 68.8% 73.6% 64.1% 74.9% 69.7% 76.9% 73.1%

3/32 1/8 5/32

85 125 140 160 180 180 200 220 250 270 290

1.6 2.1 2.6 3 3.5 3.2 3.8 4.1 5.3 5.7 6.1

73.0% 73.0% 75.6% 74.1% 71.2% 73.9% 71.1% 72.9% 71.3% 73.0% 72.7%

5/32 3/16 7/32

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

DEPOSITION

7/32

EFFICIENCY

P

Glo

EFFICIENCY

DIAMETER

AMPS

RATE lbs/hr

%

3/32 1/8 5/32 3/16 7/32 1/4

75 120 150 180 210 250

1.3 2.3 3.7 4.1 5 5.6

61.0% 70.7% 77.0% 73.4% 74.2% 71.9%

ELECTRODE

RATE lbs/hr

%

1/8

120 150 160 200 230 270 290 330 350 400

2.4 3.1 3 3.7 4.5 5.5 5.8 7.1 7.1 8.7

63.9% 61.1% 71.9% 67.0% 70.9% 73.2% 67.2% 70.3% 68.7% 69.9%

EFFICIENCY

DIAMETER

AMPS

RATE lbs/hr

%

1/8 5/32

130 165 200 220 250 320

2.9 3.2 3.4 4 4.2 5.6

81.8% 78.8% 69.0% 77.0% 74.5% 69.8%

3/16

EFFICIENCY

AMPS

7/32

DEPOSITION

DEPOSITION

DIAMETER

5/32

E6012 ELECTRODE

Turn

E7014

3/16

7/32

Lesson 9 Estimating & Comparing Weld Metal Costs

3/16

DEPOSITION

E6011 ELECTRODE

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Go T

6013

DIAMETER

ELECTRODE

Cu Ch Tab Con

1/4

DEPOSITION DATA - SMAW - COATED ELECTRODES

FIGURE 8

NOTE: EFFICIENCY RATES DO NOT INCLUDE STUB LOSS

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IX

Cu Ch Tab Con

Lesson 2 Common Electric Arc Welding Processes

Go T

E7016

Lesson 3 Covered Electrodes for Welding Mild Steels

ELECTRODE DIAMETER

AMPS

1/8

100 130 140 160 190 175 200 225 250 250 275 300 350

5/32

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

DEPOSITION EFFICIENCY

3/16

1/4

RATE lbs/hr

1.7 2.3 3.0 3.2 3.6 3.8 4.2 4.4 4.8 5.9 6.4 6.8 7.6

%

P

63.9% 65.8% 70.5% 69.1% 66.0% 71.0% 71.0% 70.0% 65.8% 74.5% 74.1% 73.2% 71.5%

LOW ALLOY, IRON POWDER ELECTRODES TYPES E7018, E8018, E9018, E10018, E11018, AND E12018 ELECTRODE DIAMETER

3/32

1/8

5/32

3/16

E7024 ELECTRODE

DEPOSITION EFFICIENCY

DIAMETER

AMPS

1/8

140 180 180 210 240 245 270 290 320 360 400

5/32

3/16

7/32 1/4

RATE lbs/hr

4.2 5.1 5.3 6.3 7.2 7.5 8.3 9.1 9.4 11.6 12.6

%

7/32

71.8% 70.7% 71.3% 72.5% 69.4% 69.2% 70.5% 68.0% 72.4% 69.1% 71.7%

1/4

DEPOSITION EFFICIENCY AMPS

70 90 110 120 140 160 140 170 200 200 250 300 250 300 350 300 350 400

RATE lbs/hr

1.37 1.65 1.73 2.58 2.74 2.99 3.11 3.78 4.31 4.85 5.36 5.61 6.50 7.20 7.40 7.72 8.67 9.04

Glo

%

70.5% 66.3% 64.4% 71.6% 70.9% 68.1% 75.0% 73.5% 73.0% 76.4% 74.6% 70.3% 75.0% 74.0% 73.0% 78.0% 77.0% 74.0%

Turn

Se Ch (Fa Dow

Se Doc (Sl Dow

DEPOSITION DATA - SMAW - COATED ELECTRODES (Con't.) FIGURE 9

NOTE: EFFICIENCY RATES DO NOT INCLUDE STUB LOSS

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

0.045

Lesson 1 The Basics of Arc Welding

LESSON IX

FLUX CORED ARC WELDING/METAL CORED ARC WELDING - Deposition

9.3.2

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels

data for gas shielded FCAW on all low alloy wire types and MCAW on all alloy types.

FLUX CORED ARC WELDING (FCAW) GAS SHIELDED TYPES E70T-1, E71T-1, E70T-2, ELECTRODE DIAMETER

.035

.045

Lesson 5 Welding Filler Metals for Stainless Steels .052

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Lesson 8 Hardsurfacing Electrodes

1/16

5/64

3/32

Lesson 9 Estimating & Comparing Weld Metal Costs

Go T

E70T-5, & ALL LOW ALLOY TYPES

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Cu Ch Tab Con

AMPS

130 140 160 180 200 220 160 180 200 220 240 280 170 190 210 240 270 300 180 200 220 250 275 300 350 250 350 450 400 450 500

METAL CORED ARC WELDING (MCAW)

DEPOSITION EFFICIENCY RATE lbs/hr %

3.2 3.6 4.2 5.6 6.5 7.5 4.0 4.9 6.5 6.8 7.3 10.5 3.9 5.3 5.5 6.7 8.1 10.3 4.2 4.7 5.6 7.7 8.5 9.3 11.7 6.4 10.5 14.8 12.7 15.0 18.5

82% 82% 83% 83% 84% 85% 83% 87% 90% 84% 84% 89% 84% 87% 86% 85% 85% 87% 87% 85% 87% 86% 86% 86% 86% 85% 85% 85% 85% 86% 86%

P

E70T-1, E71T-1, AND ALL ALLOY TYPES ELECTRODE

DEPOSITION

EFFICIENCY

DIAMETER

AMPS

RATE lbs/hr

%

0.035

150 200 250 250 275 300 275 300 325 300 350 400 450 350 400 450 500 400 450 500 550

4.4 6.5 9.4 8 11.4 11.6 8 9.6 10.1 8.6 11.9 14.6 16.2 11.6 13.2 15.8 20.4 11.5 14.5 16.5 21

93% 92% 92% 91% 93% 95% 90% 93% 93% 89% 94% 93% 96% 94% 95% 97% 97% 95% 97% 97% 98%

0.052

1/16

5/64

3/32

NOTE: DATA REFLECTS USE OF 75% ARGON 25% CO2 GAS SHIELDING. DEPOSITION RATES AND EFFICIENCIES WILL INCREASE WITH THE USE OF HIGHER ARGON MIXTURES.

DEPOSITION DATA - FCAW/MCAW FIGURE 10

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Glo

Turn

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IX 9.3.3

Lesson 2 Common Electric Arc Welding Processes

GAS METAL ARC WELDING, AND SUBMERGED ARC WELDING - Deposition data for self-shielded FCAW, and solid wires using GMAW and SubArc.

Lesson 3 Covered Electrodes for Welding Mild Steels FLUX CORED ARC WELDING (FCAW)

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

SELF-SHIELDED

ELECTRODE DIAMETER E70T-3 3/32 E70T-4 3/32

Lesson 5 Welding Filler Metals for Stainless Steels

0.12 E70T-6 5/64 3/32 E70T-6 3/32 7/64

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

E71T-7 .068 5/64 E71T-8 5/64 3/32 E61T8-K6 5/64

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

E70T-10 .045 1/16 5/64 E71T-11 .045 1/16 5/64 3/32 E70T4-K2 3/32 E71T-GS .030 .035 .045

Lesson 9 Estimating & Comparing Weld Metal Costs

1/16 5/64

AMPS

450 400 450 350 480 325 450 200 300 220 300 235 150 220 250 150 200 240 250 300 100 120 150 200 250

DEPOSITION EFFICIENCY RATE lbs/hr %

14 15 20 11.9 14.7 11.4 18 4.2 8 4.4 6.7 4.3 2.6 3.3 4 2.4 3.6 4.5 5 14 1.6 2.1 2.4 3.6 3.9

DEPOSITION DATA

Lesson 10 Reliability of Welding Filler Metals

GAS METAL ARC WELDING SOLID WIRES

FLUX CORED ARC WELDING,

FIGURE 11

88% 85% 81% 86% 81% 80% 86% 76% 84% 77% 77% 76% 88% 78% 94% 82% 83% 87% 91% 83% 75% 84% 82% 83% 81%

Cu Ch Tab Con

DEPOSITION RATE lbs/hr ELECTRODE DIAMETER AMPS 75 .030 100 150 200 80 .035 100 150 200 250 100 .045 125 150 200 250 300 350 250 1/16 275 300 350 400 450

98%A/2%O2 75%A/25%CO2 Straight CO2 *98% *96% *93% 2.0 1.9 1.8 2.6 2.6 2.5 4.1 4.0 3.9 6.8 6.7 6.5 2.2 2.1 2.0 2.7 2.7 2.6 4.2 4.1 4.0 6.2 6.0 5.9 9.0 8.8 8.6 2.1 2.0 1.9 2.8 2.8 2.7 3.6 3.5 3.4 5.6 5.5 5.3 7.8 7.6 7.4 10.2 10.0 9.7 13.2 12.9 12.5 6.5 6.4 6.2 7.7 7.6 7.3 9.0 8.8 8.5 11.3 11.0 10.7 14.0 13.7 13.3 17.4 17.1 16.5

* USE THIS FIGURE AS THE DEPOSITION EFFICIENCY IN THE COST CALCULATIONS ON SHEET ONE.

Go T

P

Glo

Turn

SUBMERGED ARC WIRES (1" STICKOUT)

ELECTRODE

MELT-OFF

EFFICIENCY

RATE lbs/hr

%

DIAMETER

AMPS

5/64

300

7.0

3/32

400 500 400

10.2 15.0 9.4

500 600 400 500

13.0 17.2 8.5 11.5

600 700 500

15.0 19.0 11.3

600 700

14.6 18.4

800

22.0

900 600

26.1 13.9

700 800 900 1000

17.5 21.0 25.0 29.2

1100

34.0

1/8

5/32

3/16

Assume 99%

Efficiency

NOTE: Values for 1" Stickout

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

LESSON IX

9.4 COST CALCULATIONS - EXAMPLE 1 9.4.1

Calculating the Cost Per Pound of Deposited Weld Metal

9.4.1.1

Example 1 - Calculate the cost of welding 1,280 ft. of a single bevel butt joint as

Cu Ch Tab Con

shown in Figure 14 using the following data. a. Electrode - 3/16” diameter, 14” long, E7018, operated at 25 volts, 250 amps.

Lesson 3 Covered Electrodes for Welding Mild Steels

Go T

b. Stub Loss - 2 inches

P

c. Labor and Overhead - $30.00/hr d. Electrode Cost - $.57/lb e. Power Cost - $.045/kWh

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Glo 9.4.1.2

The formulas for the calculations are shown on the Weld Metal Cost Worksheet in Figure 12. The following explains each step in the calculations. Line 1- Labor and Overhead - $30.00/hr (given)

Lesson 5 Welding Filler Metals for Stainless Steels

Deposition Rate - From shielded metal arc welding deposition data chart in Figure 9 = 5.36 lbs/hr. Operating Factor - Since it is not stated above, use an average value of 30% (.30)

Turn

shown in Figure 2.

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

The cost of labor and overhead per pound of deposited weld metal can now be calculated as $18.66/lb. Line 2 - Electrode Cost Per Pound - $.57 (given)

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Deposition Efficiency - From the shielded metal arc welding deposition table in Figure 9 = 74.6%. Since this is a coated electrode, the efficiency must be adjusted for stub loss by the formula following Figure 3. We know that the electrode length is 14" and the stub loss is 2" (given). The formula becomes: Efficiency - Stub Loss = (14-2) x .746

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Se Ch (Fa Dow

÷

14 = .639 or 63.9%

63.9% is the adjusted efficiency to be used in Line 2. The cost of the electrode per pound of deposited weld metal can now be calculated as $.89/lb. Line 3 - Not applicable for coated electrodes. Line 4 - Not applicable for coated electrodes.

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IX

EXAMPLE 1 WELD METAL COST WORKSHEET COST PER POUND OF DEPOSITED WELD METAL

Lesson 2 Common Electric Arc Welding Processes 1.

Lesson 3 Covered Electrodes for Welding Mild Steels

LABOR & OVERHEAD

2. ELECTRODE

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

LABOR & OVERHEAD COST/HR DEPOSITION OPERATING RATE (LBS/HR) x FACTOR

=

ELECTRODE COST/LB DEPOSITION EFFICIENCY

=

30.00

30.00

=

5.36 x .30

= 18.66

Go T

1.608

P .57

=

.89

.639

Glo

3. GAS

GAS FLOW RATE (CU FT/HR) x GAS COST/CU FT

=

=

=

=

=

N A

DEPOSITION RATE (LBS/HR) 4.

Lesson 5 Welding Filler Metals for Stainless Steels

Cu Ch Tab Con

5.

FLUX

FLUX COST/LB x 1.4 DEPOSITION EFFICIENCY

=

POWER

COST/kWh x VOLTS x AMPS 1000 x DEPOSITION RATE

=

X

1.4

.045 x 25 x 250

=

1000 x 5.36

281.25 5,360

=

N A

.052

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

6.

TOTAL COST PER LB. OF DEPOSITED WELD METAL

$ 19.60

COST PER FOOT OF DEPOSITED WELD METAL 7.

COST PER POUND OF DEPOSITED X WELD METAL

POUNDS PER FOOT OF WELD JOINT

=

19.60x .814

= $15.95

8. COST PER FOOT

=

1,280x

Se Ch (Fa Dow

Se Doc (Sl Dow

COST OF WELD METAL - TOTAL JOB

TOTAL FEET X OF WELD

Lesson 9 Estimating & Comparing Weld Metal Costs

SUM OF 1 THROUGH 5 ABOVE

15.95

= $20,422

FIGURE 12

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON IX Line 5 - Cost of Power - $ .045/kWh (given).

Cu Ch Tab Con

Volts & Amperes - 25V and 250A (given).

Lesson 2 Common Electric Arc Welding Processes

Constant - The 1,000 already entered, is a constant necessary to convert to watt-hours. Deposition Rate - 5.36 lbs/hr as used in Line 1. The cost of electrical power to deposit one pound of weld metal can now be

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Line 6 - Total Lines 1, 2, and 5 to find the total cost of depositing one pound weld

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

9.4.2

Calculating The Cost Per Foot of Deposited Weld Metal

Glo

Calculating the weight of weld metal requires that we consider the following items.

9.4.2.1

a.

Area of the cross-section of the weld.

b.

Length of the weld.

c.

Volume of the weld in cubic inches.

d.

Weight of the weld metal per cubic inch.

Turn

In the fillet weld show in Figure 13, we know that the area of the cross-section (the

triangle) is equal to one-half the base times the height, the volume of the weld is equal to the area times the length, and the weight of the weld then, is the volume times the weight of the material (steel) per cubic inch. 9.4.2.2

Se Ch (Fa Dow

We can then write the formula: Weight of Weld Metal = ½ x Base x Height x Length x Weight of Material

Substituting the values from Figure 13, we have: Wt/Ft = .5 x .5 x .5 x 12 x .283 = .4245 lbs 9.4.2.3

Weights may vary depending on the density of the particular material you are at-

tempting to calculate. The chart in Figure 14 will eliminate the need for these calculations for

Lesson 9 Estimating & Comparing Weld Metal Costs

steel fillet and butt joints, since it lists the weight per foot directly. 9.4.2.4

Estimating the weight per foot of a weld using the chart, requires that you make a

drawing of the weld joint to exact scale, and dimension the leg lengths, root gap, thickness, angles and other pertinent measurements as shown in Figure 15. Divide the cross-section of

Lesson 10 Reliability of Welding Filler Metals

P

metal. The total of $19.60.

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Go T

calculated as $.052.

Lesson 3 Covered Electrodes for Welding Mild Steels

the weld into right triangles and rectangles as shown. Sketch in the reinforcement, i.e., the

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IX

Lesson 2 Common Electric Arc Welding Processes

(A) HEIGHT

1/2" Volume of Weld = 1/2 B x A x 12 Weight of Steel = .283 lb per cu. in. Weight of Weld = 1/2 (1/2) x 1/2 x 12 x .283 = .424 lbs.

1/2"

Lesson 3 Covered Electrodes for Welding Mild Steels

Cu Ch Tab Con

(B) BASE

Go T

P

CALCULATING THE WEIGHT PER FOOT OF A FILLET WELD FIGURE 13

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Glo

domed portion above or below the surface of the plate, where required. The reinforcement

Lesson 5 Welding Filler Metals for Stainless Steels

should extend slightly beyond the edges of the joint. Measure the length and height of the reinforcement and note them on your drawing. The reinforcement is only an approximation because the contour cannot be exactly controlled in welding. Refer to the weight tables in Figure 14 for the weights per foot of each of the component parts of the weld, as sketched.

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

The sum of the weights of all the components is the total weight of the weld, per foot as shown in Figure 15A. Line 7 - The total cost per pound as determined in Line 6 is entered, and multiplied by the weight per foot as determined in Figure 14. 9.4.3

Calculating the Cost of Weld Metal - Total Job Line 8 - The cost of the weld for the total job is determined by multiplying the total

9.5 COST CALCULATIONS - EXAMPLE 2 Calculate the total cost of depositing 1,280 ft of weld metal using the CO2 shielded, flux cored

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals

welding process in the double V-groove joint shown in Figure 14 using the following data. 1.

Electrode - 3/32”, E70T-1 @ 31 volts, 450 amps.

2.

Labor and Overhead - $30.00/hr.

3.

Deposition Rate - 15 lbs/hr. From Table in Figure 10.

4.

Operating Factor - 45% (.45). Average from Figure 2.

Se Ch (Fa Dow

Se Doc (Sl Dow

feet of weld (given) by the cost per foot as determined in Line 7.

Lesson 8 Hardsurfacing Electrodes

Turn

© COPYRIGHT 2000 THE ESAB GROUP, INC.

V-GROOVE

Lesson 1 The Basics of Arc Welding

LESSON IX WEIGHT PER FOOT OF WELD METAL FOR FILLET WELDS AND ELEMENTS OF COMMON BUTT JOINTS (lbs/ft) STEEL

Lesson 2 Common Electric Arc Welding Processes

S

G

S

S G C

C

Lesson 3 Covered Electrodes for Welding Mild Steels

B

T

B

S

S

S B

T

T

A

T

T

P C SINGLE V-GROOVE

B

S

G

B

T

C DOUBLE BEVEL

SINGLE V NO GAP

1/4"

3/8"

1/8 3/16 1/4

.027 .040 .053

.053 .080 .106

.080 .119 .159

.106 .159 .212

.159 .239 .318

5/16 3/8 7/16 9/16 5/8 11/16 3/4

.066 .080 .091 .106 .119 .133 .146 .159

.133 .159 .186 .212 .239 .265 .292 .318

.199 .239 .279 .318 .358 .398 .438 .478

.265 .318 .371 .425 .478 .531 .584 .637

13/16 7/8 15/16 1

.172 .186 .199 .212

.345 .371 .398 .425

.517 .557 .597 .637

1 1/4 1 3/8 1 1/2

.239 .265 .292 .318

.478 .531 .584 .637

.345 .371 .390 .425 .478 .530 .584 .636

1/2"

5°

10°

15°

.212 .318 .425

.002 .005 .009

.005 .011 .019

.007 .016 .028

.390 .478 .557 .637 .716 .796 .876 .995

.531 .637 .743 .849 .955 1.061 1.167 1.274

.015 .021 .028 .037 .047 .058 .070 .084

.029 .042 .057 .075 .095 .117 .142 .169

.690 .743 .796 .849

1.035 1.114 1.194 1.274

1.380 1.486 1.592 1.698

.098 .114 .131 .149

.716 .796 .876 .955

.955 1.061 1.167 1.274

1.433 1.592 1.751 1.910

1.910 2.123 2.335 2.547

.690 .743 .796 .649

1.035 1.114 1.194 1.274

1.380 1.486 1.592 1.698

2.069 2.229 2.388 2.547

.955 1.061 1.167 1.274

1.433 1.592 1.751 1.910

1.910 2.123 2.335 2.547

2.865 3.184 3.502 3.821

Turn

lbs./ft. Reinforcement C

S

1/16"

2 3/4 3

3/16"

REINFORCEMENT

lbs./ft. of Triangle B

G

Inches

2 1/4

T T

lbs./ft. of Rectangle A

2

B

B

B

T

1 5/8 1 3/4

H

C A

C

1/8"

S

C B

A

T

DOUBLE

Lesson 10 Reliability of Welding Filler Metals

Go T B

C

G

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 9 Estimating & Comparing Weld Metal Costs

T

SINGLE BEVEL

C

Lesson 8 Hardsurfacing Electrodes

B

Glo

B

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

A

T

EQUAL LEG FILLETS (USE 45°COLUMN)

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Cu Ch Tab Con

H 22 1/2°

30°

45°

1/16"

1/8"

3/16"

1/4"

.011 .025 .044

.015 .035 .061

.027 .060 .106

.027 .035

.044 .064 .087 .114 .144 .178 .215 .256

.069 .099 .129 .176 .223 .275 .332 .396

.096 .138 .188 .245 .311 .383 .464 .552

.166 .239 .325 .425 .451 .664 .804 .956

.044 .053 .062 .071 .080 .088 .097 .106

.884 .106 .124 .141 .159 .177 .195 .212

.212 .239 .265 .292 .318

.354 .389 .424

.198 .230 .263 .300

.301 .349 .400 .456

.464 .538 .618 .703

.648 .751 .863 .981

1.121 1.300 1.493 1.698

.115 .124 .133 .141

.230 .248 .266 .283

.345 .371 .398 .424

.460 .495 .530 .566

.188 .232 .281 .334

.379 .468 .567 .674

.577 .712 .861 1.023

.890 1.099 1.330 1.582

1.241 1.532 1.853 2.206

2.149 2.653 3.210 3.821

.159 .177 .195 .212

.318 .354 .389 .424

.477 .531 .584 .637

.637 .707 .777 .849

2.759 2.972 3.184 3.396

.393 .455 .523 .594

.792 .918 1.053 1.197

1.201 1.393 1.599 1.820

1.857 2.154 2.473 2.813

2.589 3.002 3.447 3.921

4.484 5.200 5.970 6.792

.230 .248 .266 .283

.460 .495 .531 .566

.690 .743 .796 .849

.920 .990 1.061 1.132

3.821 4.245 4.669 5.094

.752 .928 1.123 1.337

1.516 1.871 2.264 2.695

2.303 2.844 3.441 4.095

3.561 4.396 5.319 6.330

4.963 6.127 7.414 8.823

8.596 .318 10.613 .354 12.841 .389 15.282 .424

.637 .707 .778 .849

.955 1.061 1.167 1.273

1.273 1.415 1.556 1.698

Se Ch (Fa Dow

© COPYRIGHT 2000 THE ESAB GROUP, INC.

FIGURE 14

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IX 22.5°

22.5°

Cu Ch Tab Con

45° 1/ 16"

Lesson 2 Common Electric Arc Welding Processes

B 5/8"

1/2"

1/2"

1"

1/8"

A

Go T

B

C

1/16"

lbs./ft. A= B= C= TOTAL WEIGHT/FT.

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

1/2"

.265 .425 .124 .814 lbs

lbs./ft. B = .176 x 4 = C = .071 x 2 = TOTAL WEIGHT/FT.

.704 .142 .846 lbs

5.

Electrode Cost - $.80/lb (from supplier).

6.

Deposition Efficiency - 86% (.86) From Table in Figure 10.

7.

Gas Flow Rate - 45 cubic feet per hour. From Figure 7.

8.

Gas Cost - $.03/cubic foot (from supplier).

9.

Cost of Power - $.045/kWh.

10.

Wt/Ft of Weld - From Figure 15B = .846 lbs/ft.

Turn

These values are shown inserted into the formulas on the Weld Metal Cost Worksheet in Figure 16.

9.6 COMPARING WELD METAL COSTS It is interesting to note that the amount of weld metal deposited in Example 1 and Example 2 is

Example 1 as shown below. This is because the flux cored process has a higher deposition rate, efficiency and operating factor and also allows a tighter joint due to the deep penetrating characteristics of the process. Example 1 - 1,280 ft x .814 lbs/ft = 1,041.9 lbs at $13,939

Lesson 9 Estimating & Comparing Weld Metal Costs

Example 2 - 1,280 ft x .846 lbs/ft = 1,082.9 lbs at $ 4,352 9.6.0.1

When comparing welding processes, all efforts should be made to assure that you

use the proper welding current for the electrode or wire in the position in which the weld must

Lesson 10 Reliability of Welding Filler Metals

Glo

FIGURE 15

almost the same, while the total cost of depositing the weld metal is three times higher in

Lesson 8 Hardsurfacing Electrodes

P

ESTIMATING WELD METAL WEIGHT

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

B

A

B

Lesson 3 Covered Electrodes for Welding Mild Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

C

7/8" C

be made. As an example, consider depositing a given size fillet weld in the vertical-up posi-

© COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

LESSON IX

EXAMPLE 2 WELD METAL COST WORKSHEET COST PER POUND OF DEPOSITED WELD METAL

Lesson 2 Common Electric Arc Welding Processes 1.

Lesson 3 Covered Electrodes for Welding Mild Steels

LABOR & OVERHEAD

2. ELECTRODE

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

30.00

LABOR & OVERHEAD COST/HR DEPOSITION OPERATING RATE (LBS/HR) x FACTOR

=

ELECTRODE COST/LB DEPOSITION EFFICIENCY

=

GAS

30.00

=

4.44

Go T

6.75

15 x .45

P .80

GAS FLOW RATE (CU FT/HR) x GAS COST/CU FT

=

.93

=

.86

45 x .03

1.35

=

1 5

DEPOSITION RATE (LBS/HR)

5.

=

Glo

3.

4.

Lesson 5 Welding Filler Metals for Stainless Steels

Cu Ch Tab Con

FLUX

FLUX COST/LB x 1.4 DEPOSITION EFFICIENCY

=

POWER

COST/kWh x VOLTS x AMPS 1000 x DEPOSITION RATE

=

x 1.4

.045 x 31 x 450

=

.09

1 5

=

NA

=

=

1000 x 15

627.75

.042

=

15,000

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing Electrodes

6.

TOTAL COST PER LB. OF DEPOSITED WELD METAL

COST PER FOOT OF DEPOSITED WELD METAL 7.

COST PER POUND OF DEPOSITED WELD METAL

X

POUNDS PER FOOT OF WELD JOINT

=

5.51

x .846

=

$4.66

8. X

COST PER FOOT

=

1,280x 4.66

Se Ch (Fa Dow

Se Doc (Sl Dow

COST OF WELD METAL - TOTAL JOB

TOTAL FEET OF WELD

Lesson 9 Estimating & Comparing Weld Metal Costs

$ 5.51

SUM OF 1 THROUGH 5 ABOVE

= $5,965

FIGURE 16

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Lesson 1 The Basics of Arc Welding

LESSON IX tion by the GMAW process and FCAW process semi-automatically. In both processes the

Cu Ch Tab Con

welding current and voltage must be lowered to weld out-of-position, and in GMAW, the short

Lesson 2 Common Electric Arc Welding Processes

circuiting arc transfer must be used. Example 3 compares the weld metal cost per pound deposited by these processes, using the proper current and voltage for depositing a ¼” fillet weld on ¼” plate, vertically up. Note: The cost of electrical power is comparable in all processes and therefore, can be eliminated as a factor.

Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

9.6.1

Example 3

P FCAW

GMAW

Electrode Type -

.045” dia. E71T-1

.045” dia. ER70S-3

Labor & Overhead -

$30.00/hr

$30.00/hr

Welding Current -

180 amperes

125 amperes

Deposition Rate -

4.9 lbs/hr (Fig. 9)

2.8 lbs/hr (Fig. 10)

Operating Factor -

45% (Fig. 2)

50% (Fig. 2)

Electrode Cost -

$1.44/lb

$.66/lb

Deposition Efficiency -

85% (Fig. 9)

96% (Fig. 6)

Gas Flow Rate -

35 cfh (Fig. 7)

35 cfh (Fig. 7)

Gas Cost Per Cu. Ft. -

$.03 CO

$.11 75% Ar/25% CO

2

Glo

Turn 2

This data is tabulated in the chart in Figure 17. 9.6.1.1

As you can see, the cost of depositing the weld metal is about 33% less using the

Flux Cored Arc Welding process. Since there is no slag to help hold the vertical weld puddle in the GMAW process, the welding current with solid wire must be lowered considerably. This, of course, lowers the deposition rate, and since labor and overhead is the largest factor involved, it substantially raises deposition costs. In the flat or horizontal position, where the

Lesson 8 Hardsurfacing Electrodes

Go T

welding current on the solid wire would be much higher, the cost difference would be considerably less pronounced.

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes Lesson 3 Covered Electrodes for Welding Mild Steels Lesson 4 Covered Electrodes for Welding Low Alloy Steels

LESSON IX The following information/variables must be determined prior to completing calculations: (1) Proposed Method Cost Calculation (2) Present Method Cost Calculation Flux Cored Arc Welding Gas Metal Arc Welding E71T-1 .045 Dia. at 180 Amps (3) (4) ER70S-3 .045 Dia. at 125 Amps Actual Labor & O/H Rate for your Customer $ 30.00 $ 30.00 Actual Labor & O/H Rate for your Customer Deposition Rate in Pounds per Hour 4.9 2.8 Deposition Rate in Pounds per Hour Operating Factor 45% 50% Operating Factor Electrode Cost per Pound $ 1.44 $ 0.66 Electrode Cost per Pound Deposition Efficiency 85% 96% Deposition Efficiency Gas Type CO2 75% Ar/25% CO2 Gas Type Gas Flow Rate 35 30 Gas Flow Rate Gas Cost per Cubic Foot $ 0.03 $ 0.11 Gas Cost per Cubic Foot Equipment Cost $ Prepared For: NAME INFO Customer Name: NAME INFO Date: Result (1) Proposed Method Cost Calculation (2) Present Method Cost Calculation (Cost Reduction ) Formulas for Calculating Flux Cored Arc Welding Gas Metal Arc Welding Cost Cost per Pound Deposited Weld Metal E71T-1 .045 Dia. at 180 Amps ER70S-3 .045 Dia. at 125 Amps Increase Labor& Overhead

Electrode

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Cu Ch Tab Con

= Labor & Overhead Cost /Hr = Deposition Operating X Rate (lbs / hr) Factor Electrode Cost/lb

$30.00 4.9

X

=

Gas Flow Rate (Cuft/hr) = X Gas Cost/Cu ft. Deposition Rate (lbs&/hr) Sum of the Above

$30.00 = $13.605

=

2.205

1.44

Deposition Efficiency Gas

=

0.45

$30.00 2.8

=

1.694

X

Lesson 9 Estimating & Comparing Weld Metal Costs

($7.823 )

=

0.688

$1.007

1.179

($0.964 )

Gas Type = 75% Ar/25% CO2

=

1.05

=

0.214 3 0

X 0.11 =

3.3 =

4.9 Total Variable Cost/lb Deposited Weld Metal

2.8

Turn

Total Variable Cost/lb = $15.514 Deposited Weld Metal = $23.295

( $7.781) T otal

9.7 OTHER USEFUL FORMULAS The information discussed below will assist you in making other useful calculations:

Total Pounds =

Wt/Ft of Weld x No. of Ft of Weld Deposition Efficiency

Substituting the values from Example 1:

.814 x 1,280 = 1,631 lbs .630

WELDING TIME REQUIRED (REF. EXAMPLE 1) Lesson 10 Reliability of Welding Filler Metals

Glo

1.4

TOTAL POUNDS OF ELECTRODES REQUIRED (REF. EXAMPLE 1) Lesson 8 Hardsurfacing Electrodes

P

0.96

Gas Type = CO2

0.03

= $30.00 = $21.429

0.5 =

0.66

0.85

35

X

Go T

Welding Time =

Wt/Ft of Weld x Ft of Weld Deposition Rate x Operating Factor

Substituting the values in Example 1:

.814 x 1,280 5.36 x .30

=

1,042

= 648 Hrs.

1.608 © COPYRIGHT 2000 THE ESAB GROUP, INC.

Se Ch (Fa Dow

Se Doc (Sl Dow

Lesson 1 The Basics of Arc Welding

Lesson 2 Common Electric Arc Welding Processes

LESSON IX

9.8 AMORTIZATION OF EQUIPMENT COSTS Calculations show that you can save $7.00 per pound of deposited weld metal by switching from E7018 electrodes and the SMAW process to an ER70S0-3 solid wire using the GMAW process. However, the cost of the necessary equipment (power source, wire feeder and gun) is $2,800. How long will it take to amortize or regain the cost of the equipment knowing that the deposition rate of the ER70S-3 is 7.4 lbs/hr and the operating factor of the GMAW process

Lesson 3 Covered Electrodes for Welding Mild Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Go T

is 50%? The formula is:

P Equipment Cost $ Savings/Lb

Lesson 4 Covered Electrodes for Welding Low Alloy Steels

Cu Ch Tab Con

÷

(Deposition Rate x Operating Factor) = Man Hrs

Glo Substituting the values in the formula:

2,800 7.00

400

÷ ÷

(7.4 x .50) = Man Hrs

3.7 = Man Hrs

If we divide 108 into eight hour days (108 ÷ 8 = 13.5) the deposited weld metal savings of one man working an eight hour day for 13-1/2 days will pay for the cost of the equipment.

Turn Lesson 6 Carbon & Low Alloy Steel Filler Metals GMAW,GTAW,SAW

Se Ch (Fa Dow

Lesson 7 Flux Cored Arc Electrodes Carbon Low Alloy Steels

Se Doc (Sl Dow

Lesson 8 Hardsurfacing Electrodes

Lesson 9 Estimating & Comparing Weld Metal Costs

Lesson 10 Reliability of Welding Filler Metals © COPYRIGHT 2000 THE ESAB GROUP, INC.