GB/T 1220-2007
Translated English of Chinese Standard: GB/T1220-2007 Translated by: www.ChineseStandard.net Wayne Zheng et al. Email:
[email protected]
GB ICS 77.140.20 H 40
NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA GB/T 1220-2007 Replacing GB/T 1220-1992
Stainless Steel Bars
Issued on: May 14, 2007 Issued by:
Implemented on: December 01, 2007
General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China; Standardization Administration of the People’s Republic of China.
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Page 1 of 39
GB/T 1220-2007
Table of Contents Foreword .......................................................................................................................................... 3 1.
Scope ......................................................................................................................................... 6
2.
Normative References ............................................................................................................. 6
3.
Terms and definitions ........................................................................................................... 10
4.
Contents in order sheet ......................................................................................................... 10
5.
Classification ......................................................................................................................... 10
6.
Dimension, shape, weight and permissible deviation ......................................................... 11
7.
Technical requirements ......................................................................................................... 12 7.1
Grade and chemical components ............................................................................ 12
7.2
Melting method......................................................................................................... 12
7.3
Delivery state ............................................................................................................ 12
7.4
Mechanical properties .............................................................................................. 12
7.5
Corrosion resistance ................................................................................................. 25
7.6
Macro structure ........................................................................................................ 26
7.7
Hot forging ................................................................................................................ 26
7.8
Surface quality .......................................................................................................... 26
7.9
Special requirements ................................................................................................ 27
8.
Test methods .......................................................................................................................... 27
9.
Inspection rules ..................................................................................................................... 28
10.
9.1
Inspection and acceptance ....................................................................................... 28
9.2
Lot organization rules .............................................................................................. 28
9.3
Sampling position and sampling quantity .............................................................. 28
9.4
Rules for re-inspection and determination ............................................................. 28
Packing, marking and quality certificate ....................................................................... 29
Annex A .......................................................................................................................................... 30 Annex B .......................................................................................................................................... 33
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GB/T 1220-2007
Foreword
This Standard replaces GB/T 1220-1992 Stainless steel bars. In comparison with Standard GB/T 1220—1992, main changes of this Standard include the following points:
Add the “Technical terms and definitions” and “Contents in order sheet” (See Chapter 3 and Chapter 4);
“Dimensions, shape, weight and permissible deviation” is changed to direct quotation of stipulations specified in universal basic standard (Chapter 4 of 1992 edition; Chapter 6 of this edition);
Delete
the
6
grades,
including
1Cr18Mn10Ni5Mo3N,
1Cr18Mn12Mo2Ti,
0Cr18Ni12Mo2Ti, 1Cr18Ni5Mo12Mo3Ti, 1Cr18Ni9Ti and 0Cr26Ni5Mo2, etc. (Table 2 and Table 3 of 1992 Edition);
Add the 6 grades and their properties, in including 022Cr18Mn22Ni5Mo3N, 022Cr23Ni5Mo3N,
022Cr25Ni6Mo2N,
03Cr25Ni6Mo3Cu2N,
17Cr16Ni2
and
05Cr15Ni5Cu4Nb, etc. (See Table 2 and Table 7, Table 4 and Table 9, Table 5 and Table 10);
Adjust the chemical compositions and phosphonium content of 21 steel grades (serial numbers: 1, 3, 13, 17, 23, 25, 35, 38, 39, 41, 43, 44, 52, 55, 62, 68, 93, 85, 98, 137 and 139) based on universal international steel grade (Table 2 in 1992 Edition and Tables 1 ~ 5 in this Edition);
Modify the “Smelting method” that shall apply to initial molten steel plus out-of-furnace refining process in priority (Article 5.2 of 1992 edition and Article 7.2 of this edition);
“Delivery state” is changed from “It may not be treated if it is required by the Buyer” into “It may not be treated through negotiations between the Supplier and the Buyer”, while for precipitation-hardening stainless steel bars it has added that annealing treatment to the delivery can be chosen by steel texture
(Article 5.3 of 1992 edition
and Article 7.3 of this edition);
For “Surface quality” it has added that “It may specify to remove scales formed from heat treatment by way of pickling, turning or other methods through negotiations between the Supplier and the Buyer, which shall be indicated in contract” (Article 7.8.3 of this edition);
The heat treatment system for all kinds of stainless steel bars or test pieces is separated from mechanical property table and listed into Annex A (Informative annex) (Table 3 ~ Table 5 of 1992 edition; Table A.1 ~ Table A.5 of this edition);
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GB/T 1220-2007
The yield strength for martensite and precipitation-hardening stainless steel is changed to necessary inspection indicator (Article 5.4.1.1 of 1992 edition; Table 9 and Table 10 of this edition);
For 022Cr19Ni5Mo3Si2N(00Cr18Ni5Mo3Si2) steel, it has added that Brinell hardness value HBW shall be no more than 290 (Table 3 of 1992 edition; Table 7 of this edition);
For 12Cr13(1Cr13) steel it has added that the lower limit of carbon content shall be 0.08%, while its percentage elongation after fracture is adjusted from 25% to 22% (Table 2 and Table 4 of 1992 edition; Table 4 and Table 9 of this edition);
For 30Cr13(Y3Cr13) steel, its percentage elongation after fracture is adjusted from 12% and 40% to 8% and 35% (Table 4 of 1992 edition; Table 9 of this edition);
The original yield strength
value for some martensite steels (No. 18, 22, 26, 39, 46,
σ 0.2
50 and 52) and 06Cr13Al(0Cr13Al) is adjusted from 177Mpa to proof strength at non-proportional extension RP0.2 value to be 175 N/mm2 (Table 3 of 1992 edition; Table 6 and Table 8 of this edition);
The yield strength
value for 022Cr12(00Cr12) steels is adjusted from 196MPa to
σ 0.2
proof strength at non-proportional extension RP0.2 value to be 195 N/mm2, while tensile strength is adjusted from 365MPa to 360N/mm 2 (Table 3 of 1992 edition; Table 8 of this edition);
The tensile strengths Rm for 20Cr13 (2Cr13) and 13Cr13 (1Cr13Mo) are adjusted respectively from 635MPa and 685MPa to 640N/mm 2 and 690N/mm2 (Table 4 of 1992 edition; Table 9 of this edition);
Delete the stipulations on section shrinkage rate of flat steel (Table 3 ~ Table 5 of 1992 edition; notes of Table 6 to Table 10 of this edition);
“Corrosion resistance” is changed to an item in agreement, where it has cancelled the two test methods contained in GB/T 4334.4 and GB/T 4334.6, while for the test condition of 06Cr19Ni13Mo3 (0Cr19Ni13Mo3) it has added “Sensitizing treatment” (Article 5.5 of 1992 edition; Article 7.5 of this edition);
For “Surface quality”, add the “It may specify to remove scales formed from heat treatment by way of pickling, turning or other methods through negotiations between the Supplier and the Buyer, which shall be indicated in contract” (Article 5.8 of 1992 edition; Article 7.8 of this edition);
It has clearly specified the sampling positions in “Macro structure” and “Tower shape” for inspection of continuous casting steel and the sampling quantity for “Corrosion resistance” test (Article 12 of 1992 edition; Article 16 of this edition);
Delete the “Check list for stainless steel grades of this Standard and stainless steel grades of each country” and changed to direct quotation of GB/T 20878: Stainless steel
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GB/T 1220-2007
and heat-resisting steel –Grade and chemical compositions (Annex B of 1992 edition; Table 1 ~ Table 5 of this edition). The Annex A and Annex B of this Standard are informative. This Standard was proposed by China Iron and Steel Association. This Standard shall be under jurisdiction of the National Technical Committee of Standardization for Iron and Steel. The main drafting organizations of this Standard: China Metallurgical Information and Standardization Institute, and Liaoning Dongbei Special Steel Group Co., Ltd.. The main drafters of this Standard: Luan Yan, Dai Qiang, Gu Qiang, Zeng Wentao, and Liu Baoshi. The historical versions to be substituted by this Standard include: -- GB/T 1220—1975, GB/T 1220—1984, GB/T 1220—1992.
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GB/T 1220-2007
Stainless steel bars
1. Scope This Standard specifies the dimensions, shape, technical requirements, test methods, inspection rules, packing marks, and certificate quality of stainless steel bars (generic terms of round steel, square steel, flat steel, hexagonal steel and octagonal steel, hereinafter refer to as “Steel bar”). This Standard is applicable to the hot rolled and forged steel bars of which the dimension (diameter, side length, thickness or subtense distance, hereinafter refer to as “Dimension”) is no more than 250mm. Through negotiations of both the Supplier and Buyer, it may also supply the hot rolled and forged steel bars of which the dimension is more than 250mm.
2. Normative References The articles contained in the following documents have become part of this Standard when they are quoted herein. For the dated documents so quoted, all the modifications (excluding corrections) or revisions made thereafter shall not be applicable to this Standard. For the undated documents so quoted, the latest editions shall be applicable to this Standard. GB/T 222 Permissible deviations for chemical composition of steel products GB/T 223.3 Methods for chemical analysis of iron, steel and alloy - The Diantipyrylmethane Phosphomolybdate Gravimetric Method for the Determination of phosphonium content GB/T 223.4 Methods for chemical analysis of iron, steel and alloy - The volumetric method for determination of manganese content by ammonium nitrate oxidation GB/T 223.5 Methods for chemical analysis of iron, steel and alloy – The reduction type silicomolybdic acid spectrophotometric method for the determination of acid-soluble silicon content GB/T 223.8 Methods for chemical analysis of iron, steel and alloy –The sodium fluoride separation-EDTA titration method for the determination of aluminium content GB/T 223.9 Methods for chemical analysis of iron, steel and alloy –The chromazurine S spectrophotometric method for the determination of aluminium content GB/T 223.11 Methods for chemical analysis of iron, steel and alloy –The ammonium persulphate oxidation volumetric method for the determination of chrome content GB/T 223.14 Methods for chemical analysis of iron, steel and alloy –The tantalum reagent extraction spectrophotometric method for the determination of vanadium content GB/T 223.16 Methods for chemical analysis of iron, steel and alloy –The chromotropic acid
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GB/T 1220-2007
spectrophotometric method for the determination of titanium content GB/T 223.17 Methods for chemical analysis of iron, steel and alloy –The diantipyrylmethane spectrophotometric method for the determination of titanium content GB/T 223.18 Methods for chemical analysis of iron, steel and alloy – The sodium thiosulfate separation - iodine volumetric method for the determination of cuprum content GB/T 223.23 Methods for chemical analysis of iron, steel and alloy – The dimethyl glyoxime spectrophotometric method for the determination of nickel content GB/T 223.25 Methods for chemical analysis of iron, steel and alloy – The dimethyl glyoxime gravimetric method for the determination of nickel content GB/T 223.26 Methods for chemical analysis of iron, steel and alloy – The thiocyanate direct spectrophotometric method for the determination of molybdenum content GB/T 223.28 Methods for chemical analysis of iron, steel and alloy – The alpha-Benzoin oxim gravimetric method for the determination of molybdenum content GB/T 223.36 Methods for chemical analysis of iron, steel and alloy – The distillation separation - neutralization titration method for the determination of nitrogen content GB/T 223.37 Methods for chemical analysis of iron, steel and alloy – The distillation separation - indophenol blue spectrophotometric method for the determination of nitrogen content GB/T 223.40 Determination of niobium content in iron, steel and alloy – The sulfochlorophenol S spectrophotometric method GB/T 223.52 Methods for chemical analysis of iron, steel and alloy –The hydroxylamine hydrochloride - iodine gravimetric method for the determination of selenium content GB/T 223.58 Methods for chemical analysis of iron, steel and alloy –The sodium arsenite sodium nitrite titration method for the determination of manganese content GB/T 223.59 Methods for chemical analysis of iron, steel and alloy –The molybdenum blue photometric method for the determination of phosphonium content GB/T 223.60 Methods for chemical analysis of iron, steel and alloy –The perchloric acid dehydration method for the determination of silicon content GB/T 223.61 Methods for chemical analysis of iron, steel and alloy –The ammonium phosphomolybdate volumetric method for the determination of phosphonium content GB/T 223.62 Methods for chemical analysis of iron, steel and alloy –The Butyl Acetate extraction photometric method for the determination of phosphonium content
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GB/T 1220-2007
GB/T 223.63 Methods for chemical analysis of iron, steel and alloy –The sodium periodate (potassium periodate) photometric method for the determination of manganese content (GB/T 223.63-1998, neq ISO R 629) GB/T 223.64 Methods for chemical analysis of iron, steel and alloy –The flame atom absorption spectral method for the determination of manganese content GB/T 223.67 Methods for chemical analysis of iron, steel and alloy –The potassium iodate titration method after combustion in the pipe furnace for determination of phosphonium content GB/T 223.68 Methods for chemical analysis of iron, steel and alloy –The gas volumetric method after combustion in the pipe furnace for determination of carbon content GB/T 223.71 Methods for chemical analysis of iron, steel and alloy –The gravimetric method after combustion in the pipe furnace for determination of carbon content GB/T 223.72 Methods for chemical analysis of iron, steel and alloy –The aluminium oxide color layer separation - barium sulfate gravimetric method for determination of phosphonium content GB/T 226 Etch test for macrostructure and defect of steels (GB/T 226-1991, neq ISO4969: 1980, Steel – Macroscopic examination by etching with strong mineral acids) GB/T 228 Metallic material – Greenhouse tension test method (GB/T 228 –2002, eqv ISO 6892: 1998) GB/T 229 Metal – Charpy impact test method (GB/T 229 –1994, eqv ISO 83: 1976, Steel – Charpy impact test (U-notch), eqv ISO 148; 1983, Steel – Charpy impact test (V-notch)) GB/T 230.1 Metal –Rockwell hardness test, Part I: Test method (A, B, C, D, E, F, G, H, K, N, T measuring scales) (GB/T 230.1-2004, ISO 6508: 1999, MOD) GB/T 231.1 Metal –Brinell hardness test, Part I: Test method (GB/T 231.1-2002, eqv ISO 6506-1: 1999) GB/T 702—2004 Metal – Hot-rolled round steel and square steel – Dimension, shape, weight and permissible deviation (GB/T 702—2004, ISO 1035-1: 1980, Hot-rolled steel bar – Part 1: Dimension of round bars, ISO1035-2: 1980, Hot-rolled steel bar – Part 1: Dimension of square bars, ISO1035-4: 1982, Hot-rolled steel bar – Part 4:Tolerances, MOD) GB/T 704—1988 Metal – Hot-rolled flat steel – Dimension, shape, weight and permissible deviation GB/T 705—1985 Metal – Hot-rolled hexagonal steel and octagonal steel
– Dimension,
shape, weight and permissible deviation GB/T 908—1987 Metal – Forged round steel and square steel
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– Dimension, shape, weight
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GB/T 1220-2007
and permissible deviation GB/T 1979 Standard diagrams for macrostructure and defect of structural steels GB/T 2101 General requirements of acceptance, packaging, marking and certification for section steel GB/T 2975 Steel and steel products--Location and preparation of test pieces for mechanical testing (GB/T 2975-1998, eqv ISO 377: 1997) GB/T 4334.1 Stainless steel – 10% oxalic acid etch test method GB/T 4334.2 Stainless steel –sulfuric acid - ferric sulfate corrosion test method GB/T 4334.3 Stainless steel – 65% nitric acid corrosion test method GB/T 4334.5 Stainless steel –sulfuric acid - copper sulfate corrosion test method GB/T 4340.1 Metal –Vickers hardness test, Part I: Test method (GB/T 4340.1-1999, eqv ISO 6507-1: 1997) GB/T 6394 Metal – Methods for determination of the average grain size GB/T 6401-1986 Micrographic method for determining area fraction of the alpha-phases using charts in ferritic-austenitic duplex stainless steel GB/T 7736 Ultrasonic inspecting method for macro-structure and defect of steel GB/T 9971-2004 Pure iron for raw material GB/T 10121 Steel products--Method for magnetic particle inspection of tower sample GB/T 10561 Determination of nonmetal inclusion content in steels -- Methods for radiographic inspection and classification of radiographs (GB/T 10561-2005, ISO 4967: 1998, IDT) GB/T 11170 Method for photoelectric emission spectral analysis of stainless steel GB/T 13305-1991 Micrographic method for determining area fraction of the alpha-phases in austenitic stainless steel GB/T 15574 Classification for steel products GB/T 15711 Steel products－Method for etch test of tower sample GB/T 16761-1997 Forged flat steel – Dimension, shape, weight and permissible deviation GB/T 17505 General technical requirements on delivery of steel and steel products (GB/T 17505 –1998, eqv ISO 404: 1992)
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GB/T 1220-2007
GB/T 20066 Iron and steel – Sampling and sample preparation method for determination of chemical compositions (GB/T 20066-2006, ISO 14284: 1996, IDT) GB/T 20878 Stainless steel and heat-resisting steel – Grades and chemical compositions YB/T 5293 Metallic materials-Forging test
3. Terms and definitions The technical terms and definitions established in GB/T 20878 and GB/T 15574 are applicable to this Standard.
4. Contents in order sheet The contract for goods or order form made according this Standard shall contain the following contents: a)
Standard code;
b) Product description; c)
Grade or unified numerical code;
d) Section shape (round, square, flat, hexagonal or octagonal); e)
Dimensions and shape (see Chapter 6);
f)
Weight (or quantity);
g) Processing method used (See 5.2); h) Delivery state (See 7.2); i)
Special requirements (See 7.9).
5. Classification 5.1
By structural features, steel bars are divided into 5 categories - austenite type, austenite-ferrite type, ferrite type, martensite type, and precipitation-hardening type.
5.2
By application methods, steel bars are divided into 2 categories as follows. Application methods of steel bars shall be indicated in contract, otherwise, it shall supply the steel for the purpose of cutting processing. a)
Steel for pressing processing
UP
1) Hot-pressing processing
UHP
2) Steel for hot-forging
UHF
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GB/T 1220-2007
stipulations set forth in Table 6 ~ Table 10 respectively. 7.4.3
For the non-heat-treated steel bars, the blank of test pieces shall be heat treated and its mechanical properties shall conform to the stipulations set forth in Table 6 ~ Table 10 respectively.
7.4.4
The mechanical properties of precipitation-hardening type steel bars shall be indicated in contract, otherwise it shall execute the second group in contract.
7.4.5
If the Supplier can guarantee the qualification of mechanical properties, it may wholly or partially omit mechanical property test.
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GB/T 1220-2007
Table 1 Code in GB/T 20878
Unified numerical code
Chemical compositions of austenite type stainless steel Chemical compositions (mass fraction) %
New grade
Previous grade
C
Si
1
S35350
12Cr17Mn6Ni5N
1Cr17Mn6Ni5N
0.15
1.00
3
S35450
12Cr18Mn9Ni5N
1Cr18Mn8Ni5N
0.15
1.00
Mn 5.50~7. 50 7.50~1 0.00
P
S
Ni
Cr
Mo
Cu
0.050
0.030
3.50~5.50
16.00~18.00
—
—
0.050
0.030
4.00~6.00
17.00~19.00
—
—
Other elements
N 0.05~0 .25 0.05~0 .25
—
—
9
S30110
12Cr17Ni7
1Cr17Ni7
0.15
1.00
2.00
0.045
0.030
5.00~8.00
16.00~18.00
—
—
0.10
—
13
S30210
12Cr18Ni9
1Cr18Ni9
0.15
1.00
2.00
0.045
0.030
8.00~10.00
17.00~19.00
—
—
0.10
—
15
S30317
Y12Cr18Ni9
Y1Cr18Ni9
0.15
1.00
2.00
0.20
≥0.15
8.00~10.00
17.00~19.00
(0.60)
—
—
—
16
S30327
Y12Cr18Ni9Se
Y1Cr18Ni9Se
0.15
1.00
2.00
0.20
0.060
8.00~10.00
17.00~19.00
—
—
—
Se≥0.15
17
S30408
06Cr19Ni10
0Cr18Ni9
0.08
1.00
2.00
0.045
0.030
8.00~11.00
18.00~20.00
—
—
—
—
18
S30403
022Cr19Ni10
00Cr19Ni10
0.030
1.00
2.00
0.045
0.030
8.00~12.00
18.00~20.00
—
—
—
—
22
S30488
06Cr18Ni9Cu3
0Cr18Ni9Cu3
0.08
1.00
2.00
0.045
0.030
8.50~10.50
17.00~19.00
—
23
S30458
06Cr19Ni10N
0Cr19Ni9N
0.08
1.00
2.00
0.045
0.030
8.00~11.00
18.00~20.00
—
—
24
S30478
06Cr19Ni9NbN
0Cr19Ni10NbN
0.08
1.00
2.00
0.045
0.030
7.50~10.50
18.00~20.00
—
—
25
S30453
022Cr19Ni10N
00Cr18Ni10N
0.030
1.00
2.00
0.045
0.030
8.00~11.00
18.00~20.00
—
—
26
S30510
10Cr18Ni12
1Cr18Ni12
0.12
1.00
2.00
0.045
0.030
10.50~13.00
17.00~19.00
—
—
—
—
32
S30908
06Cr23Ni13
0Cr23Ni13
0.08
1.00
2.00
0.045
0.030
12.00~15.00
22.00~24.00
—
—
—
—
35
S31008
06Cr25Ni20
0Cr25Ni20
0.08
1.50
2.00
0.045
0.030
19.00~22.00
24.00~26.00
—
—
—
—
3.00~ 4.00
—
—
0.10~0 .16 0.15~0 .30 0.10~0 .16
—
Nb0.15
—
2.00~3. 38
S31608
06Cr17Ni12Mo2
0Cr17Ni12Mo2
0.08
1.00
2.00
0.045
0.030
10.00~14.00
16.00~18.00
—
—
—
00
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GB/T 1220-2007
Table 2
Chemical compositions of austenite-ferrite type stainless steel
Code in GB/T 20878
Unified numerical code
New grade
Previous grade
67
S21860
14Cr18Ni 11Si4A1Ti
1Cr18Ni11Si4 A1Ti
68
70
71
73
75
S21953
S22253
S22053
S22553
S25554
Chemical compositions (mass fraction) %
022Cr19Ni5Mo3Si2N
022Cr22Ni5Mo3N
022Cr23Ni5Mo3N
022Cr25Ni6Mo2N
03Cr25Ni6Mo3Cu2N
00Cr18Ni5Mo3Si2
C
Si
0.10~0.
3.40~4.
18
00
Mn
P
S
0.80
0.035
0.030
1.30~2.
1.00~2.
00
00
1.00
2.00
0.030
0.030
0.030
0.030
0.04
0.035
1.00
1.00
1.00
2.00
2.00
1.50
0.030
0.030
0.035
0.035
Mo
Cu
N
—
—
—
Other elements Ti0.40~0.7 0 A10.10~0. 30
Ni
Cr
10.00~12
17.50~1
.00
9.50
4.50~5.5
18.00~1
2.50~3.
0
9.50
00
4.50~6.5
21.00~2
2.50~3.
0
3.00
50
4.50~6.5
22.00~2
2.50~3.
0
3.00
50
5.50~6.5
24.00~2
1.20~2.
0
6.00
50
4.50~6.5
24.00~2
2.90~3.
1.50~2.
0.10~0.
0
7.00
90
50
25
0.030
0.05~0. —
0.020
— 12 0.08~0.
—
0.020
— 20 0.14~0.
—
0.030
— 20 0.10~0.
—
— 20
0.030
—
Note 1: All the elements listed in the table shall be maximum value, unless it is otherwise indicated for range or minimum value. Note 2: The comparison between the grades of this Standard and those of foreign standards refer to GB/T 20878.
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GB/T 1220-2007
Table 6 Proof strength, non-proportional extension RP0.2 b/(N/mm2)
(Continued) Tensile strength Rm /(N/mm2)
Shrinkage rate after fracture A /%
Section shrinkage rate Zc /%
Hardness b
Code in GB/T 20878
Unified numerical code
24
S30478
06Cr19Ni9NbN
0Cr19Ni10NbN
345
685
35
50
250
100
260
25
S30453
022Cr19Ni 10N
00Cr18Ni1 0N
245
550
40
50
217
95
220
26
S30510
10Cr18Ni1 2
1Cr18Ni12
175
480
40
60
187
90
200
32
S30908
06Cr23Ni1 3
0Cr23Ni13
205
520
40
60
187
90
200
35
S31008
06Cr25Ni2 0
0Cr25Ni20
205
520
40
50
187
90
200
38
S31608
06Cr17Ni1 2Mo2
0Cr17Ni12 Mo2
205
520
40
60
187
90
200
39
S31603
022Cr17Ni 12Mo2
0Cr17Ni12 Mo2
175
480
40
60
187
90
200
41
S31668
06C17Ni12 Mo2Ti
0Cr18Ni12 Mo3Ti
205
530
40
55
187
90
200
43
S31658
06Cr17Ni1 2Mo2N
0Cr17Ni12 Mo2N
275
550
35
50
217
95
220
44
S31653
022Cr17Ni 12Mo2N
00Cr17Ni1 3Mo2N
245
550
40
50
217
95
220
45
S31688
06Cr18Ni1 2Mo2Cu2
0Cr18Ni1 2Mo2Cu2
205
520
40
60
187
90
200
46
S31683
022Cr18Ni 14Mo2Cu2
00Cr18Ni 14Mo2Cu2
175
480
40
60
187
90
200
49
S31708
06Cr19Ni1 3Mo3
0Cr19Ni13 Mo3
205
520
40
60
187
90
200
50
S31703
022Cr19Ni 13Mo3
00Cr19Ni13 Mo3
175
480
40
60
187
90
200
52
S31794
03Cr18Ni1 6Mo5
0Cr18Ni16 Mo5
175
480
40
45
187
90
200
55
S32168
06Cr18Ni11Ti
0Cr18Ni1 0Ti
205
520
40
50
187
90
200
62
S34778
06Cr18Ni 11Nb
0Cr18Ni11Nb
205
520
40
50
187
90
200
64
S38148
06Cr18Ni1 3Si4
0Cr18Ni13 Si4
205
520
40
60
207
95
218
a. b. c.
New grade
Previous grade
HBW
No less than
HRB
HV
No larger than
This table is only applicable to the steel bars that the diameter, side length, thickness or subtense distance is less than or equal to 180mm, for the steel bars of more than 180mm, it can be forged into 180mm sample blank for test, or through negotiation of the Supplier and Buyer to stipulate that it is allowable to reduce the value of its mechanical properties. Proof strength, non-proportional extension and hardness shall only be tested when it is required by the Buyer (to be indicated in contract), in this case, the Supplier can select one method to determine hardness according to the dimension and state of steel bars. It is not applicable to flat steel, but when it is required by the Buyer, it shall be decided through negotiation of both the Supplier and Buyer.
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Page 20 of 39
GB/T 1220-2007
Table 8
Mechanical properties of ferrite type steel bars or test pieces through annealing treatment (See Table A.3) a Proof strength, non-proportional extension RP0.2 b/(N/mm2)
Tensile strength Rm /(N/mm2)
Shrinkage rate after fracture A /%
Section shrinkage rate Zc
Charpy absorbed energy Aku2d/J
Hardness b
Code in GB/T 20878
Unified numerical code
78
S11348
06Cr13A1
0Cr13A1
175
410
20
60
78
183
83
S11203
022Cr12
00Cr12
195
360
22
60
-
183
85
S11710
10Cr17
1Cr17
205
450
22
50
-
183
86
S11717
Y10Cr17
Y1Cr17
205
450
22
50
-
183
88
S11790
10Cr17Mo
1Cr17Mo
205
450
22
60
-
183
94
S12791
008Cr27Mo
00Cr27Mo
245
410
20
45
-
219
95
S13091
008Cr30Mo2
00Cr30Mo2
295
450
20
45
-
228
a. b. c. d.
New grade
Previous grade
No less than
HBW No more than
Table 7 is only applicable to the steel bars that the diameter, side length, thickness or subtense distance is less than or equal to 75mm, for the steel bars of more than 75mm, it can be forged into 75mm sample blank for test, or through negotiation of the Supplier and Buyer to stipulate that it is allowable to reduce the value of its mechanical properties. Proof strength, non-proportional extension and hardness shall only be tested when it is required by the Buyer (to be indicated in contract), in this case, the Supplier can select one method to determine hardness according to the dimension and state of steel bars. It is not applicable to flat steel, but when it is required by the Buyer, it shall be decided through negotiation of both the Supplier and Buyer. For the round steel, hexagonal steel and octagonal steel that diameter or subtense distance is less than or equal to 16mm, or for the square steel and flat steel that the thickness is less than 12mm, it shall not conduct impact test.
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Page 22 of 39
GB/T 1220-2007
Table 10 Code in GB/T 20878
136
Mechanical properties of precipitation-hardening type (See Table A.5) steel bars or test pieces
New grade
S51550
05Cr15Ni5Cu4Nb
Previous grade Type
Grou p
Solution treatment
0
h a a r t i d o e n n i
r e c p t
480°C aging 550°C aging 580°C aging 620°C aging
Solution treatment
137
S51740
05Cr17Ni4Cu4Nb
0Cr17Ni4Cu4N b
h a r d e n i
a t i o n
r e c p t
480°C aging 550°C aging 580°C aging 620°C aging
Solution treatment
138
S51770
07Cr17Ni7Al
0Cr17Ni7A1 i a n o t
510°C aging 565°C aging
Solution treatment
139
S51570
07Cr15Ni7Mo2Al
0Cr15Ni7Mo2Al i a n o t
a. b. c.
roo strengt , non-proportional extension RP0.2 b/(N/mm2)
Heat treatment
Unified numerical code
510°C aging 565°C aging
1 2 3 4 0 1 2 3 4
Tensile strength R m /(N/mm2)
Shrinkage rate after fracture A /%
Section shrinkage rate Z b/%
Hardness
c
HBW
HRW
— 35 45 45 50 — 40 45 45 50
≤363
≤38
≥375 ≥331 ≥302 ≥277
≥40 ≥35 ≥31 ≥28
≤363
≤38
≥375 ≥331 ≥302 ≥277
≥40 ≥35 ≥31 ≥28
NO LESS THAN
0 1 2 3 4 0 1 2 3 4
— 1180 1000 865 725 — 1180 1000 865 725
— 1310 1070 1000 930 — 1310 1070 1000 930
— 10 12 13 16 — 10 12 13 16
0
0
—
—
—
—
≤229
—
1 2
1 2
1030 960
1230 1140
4 5
10 25
≥388 ≥363
— —
0
0
—
—
—
—
≤269
—
1 2
1 2
1210 1100
1320 1210
6 7
20 25
≥388 ≥375
— —
Table 10 is only applicable to the steel bars that the diameter, side length, thickness or subtense distance is less than or equal to 75mm, for the steel bars of more than 75mm, it can be forged into 75mm sample blank for test, or through negotiation of the Supplier and Buyer to stipulate that it is allowable to reduce the value of its mechanical properties. It is not applicable to flat steel, but when it is required by the Buyer, it shall be decided through negotiation of both the Supplier and Buyer. The Supplier can select one method to determine hardness according to the dimension and state of steel bars
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Page 24 of 39
GB/T 1220-2007
7.6 7.6.1
Macro structure
The acid dip macroscopic test piece of steel bar shall have no visible shrinkage cavity, air bubble, crack, inclusion, skull patch or shatter crack. It is permissible for steel bars for cutting processing to have subsurface inclusion or other inclusion with depth to be no more than half of nominal dimension tolerance.
7.6.2
The qualification level for acid dip macro structure shall conform to the stipulations set forth in Table 13. When the Buyer requires group 1, it shall be indicated in contract. For steel bars with dimension no more than 200mm, the qualification level for macro structure shall be decided through negotiations of the two parties.
7.6.3
If it can be guaranteed by the Supplier, it is permissible to apply ultrasonic detection or other nondestructive flaw detection methods in place of macro structure inspection. Table 13
7.7 7.7.1
Macro structure qualification level
Group
Common porosity
Center porosity
Ingot type segregation
Group 1
≤Level 2
≤Level 2
≤Level 2
Group 2
≤Level 3
≤Level 3
≤Level 3
Hot forging
Steel for hot heading upsetting (to be indicated in contract) shall be subject to hot forging test to forge test piece to one third of the original height without crack or breach on the surface.
7.7.2
This test can be omitted for steel bar with dimension to be more than 80mm if the Supplier can guarantee the qualification of forging test.
7.8 7.8.1
Surface quality
The surface of steel bars for pressing processing shall have no crack, scab, fold or inclusion on surface, otherwise, the defects mentioned above must be eliminated. The depth for such elimination shall conform to the stipulation in Table 14 and the width shall be no less than 5 times of depth, while the maximum elimination depth on the same cross section shall be no more than one and it is permissible for individual scratches, impressions or pockmarks whose size is no more than half of nominal dimension counting from actual dimension, or the minor cracks with depth to be no more than 0.20mm to exist on surface. Based on the agreement of the Supplier and Buyer, the surface of steel bars for cutting processing can be turned or peeled.
Table 14
Permissible depth for defect elimination on the surface of steel bars for pressing processing purpose
Nominal dimension of steel bars/mm
Permissible depth of elimination
≤80
Half of nominal dimension tolerance of steel bars
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Page 26 of 39
GB/T 1220-2007
3
Impact
2
4
Hardness
2
5
intercrystalline corrosion
2
On different steel bars
2
different steel bars or blank equivalent to ingot head; on any of different steel bars for continuous cast steel
2
On full piece of steel bar
6
7 8
Macro structure
Ultrasonic inspection Hot forging
2975
GB/T 230.1, GB/T 231.1, GB/T 4340.1
2
Nonmetallic inclusion
2
On different steel bars
10 11
Grain size Alpha phase
1 1
Any steel bar
2
different steel bars or blank equivalent to ingot head; on any of different steel bars for continuous cast steel
Tower shape
13
Dimension
14
Surface
ece y piece ece y piece
GB/T 4334.1, GB/T 4334.2, GB/T 4334.3, GB/T 4334.5
GB/T 226, GB/T 1979
GB/T 7736 YB/T 5293
9
12
GB/T 229
On full piece of steel bar
GB/T 10561 GB/T 6394 GB/T 6401 –1986, GB/T 13305—991
GB/T 15711, GB/T 10121 Calipers, micrometer caliper Visual inspection
In addition to surface and dimension inspections piece by piece, the sampling quantity for all the other inspection items of electroslag re-melted steel shall be 1. When lot is organized by the consumable electrode melting mother furnace number, in addition to 1 sample taken from each electroslag furnace number for chemical compositions, the sampling quantity for other inspection items shall be the same as stipulations in this table.
9. Inspection rules 9.1
Inspection and acceptance
The inspection and acceptance of steel bars shall be conducted by the technical and quality control departments of the Supplier. 9.2
Lot organization rules
The inspection and acceptance of steel bars shall be carried out lot by lot. Each lot shall be composed of steel bars of the same grade, same furnace number, same processing method, same dimension and same delivery state (same furnace number of heat treatment). For the electroslag re-melted steel, it is permissible to make delivery by the lot organized by the consumable electrode melting mother furnace number under the conditions that the process is stable and all technical requirements in this Standard can be guaranteed, which shall be noted in certificate of quality. 9.3
Sampling position and sampling quantity
The sampling position and sampling quantity for each lot of steel bars shall conform to the stipulations set forth in Table 16. 9.4
Rules for re-inspection and determination
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GB/T 1220-2007
9.4.1
Rules for re-inspection and determination shall execute the stipulations of GB/T 17505.
9.4.2
If the Supplier can guarantee the qualification of steel bars, it is permissible to use blank in place of product or use the large one in place of small one in the inspection results in connection with the mechanical property, macro structure and nonmetallic inclusion of steel bars or steel blanks from the same furnace number.
10. Packing, marking and quality certificate The packing, marking and quality certificate shall conform to the stipulations of GB/T 2101.
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Page 29 of 39
GB/T 1220-2007
(Informative) Typical heat treatment regulations for stainless steel bars or test pieces
Table A.1
Typical heat treatment regulations for austenite type stainless steel bars or test pieces
Code in GB/T 20878
Unified numerical code
New grade
Previous grade
Solution treatment/°C
1
S35350
12Cr17Mn6Ni5N
1Cr17Mn6Ni5N
1 010 ~ 1 120, fast-cooling
3
S35450
12Cr18Mn9Ni5N
1Cr18Mn8Ni5N
1 010 ~ 1 120, fast-cooling
9
S30110
12Cr17Ni7
1Cr17Ni7
1 010 ~ 1 150, fast-cooling
13
S30210
12Cr18Ni9
1Cr18Ni9
1 010 ~ 1 150, fast-cooling
15
S30317
Y12Cr18Ni9
Y1Cr18Ni9
1 010 ~ 1 150, fast-cooling
16
30327
Y12Cr18Ni9Se
Y1Cr18Ni9Se
1 010 ~ 1 150, fast-cooling
17
S30408
06Cr19Ni10
0Cr18Ni9
1 010 ~ 1 150, fast-cooling
18
S30403
022Cr19Ni10
00Cr19Ni10
1 010 ~ 1 150, fast-cooling
22
S30488
06Cr18Ni9Cu3
0Cr18Ni9Cu3
1 010 ~ 1 150, fast-cooling
23
S30458
06Cr19Ni10N
0Cr19Ni9N
1 010 ~ 1 150, fast-cooling
24
S30478
06Cr19Ni9NbN
0Cr19Ni10NbN
1 010 ~ 1 150, fast-cooling
25
S30453
022Cr19Ni10N
00Cr18Ni10N
1 010 ~ 1 150, fast-cooling
26
S30510
10Cr18Ni12
1Cr18Ni12
1 010 ~ 1 150, fast-cooling
32
S30908
06Cr23Ni13
0Cr23Ni13
1 030 ~ 1 150, fast-cooling
35
S31008
06Cr25Ni20
0Cr25Ni20
1 030 ~ 1 150, fast-cooling
38
S31608
06Cr17Ni12Mo2
0Cr17Ni12Mo2
1 010 ~ 1 150, fast-cooling
39
S31603
022Cr17Ni12Mo2
00Cr17Ni14Mo2
1 010 ~ 1 150, fast-cooling
41
S31668
06Cr17Ni12Mo2Ti*
0Cr18Ni12Mo3Ti*
1 000 ~ 1 100, fast-cooling
43
S31658
06Cr17Ni12Mo2N
0Cr17Ni12Mo2N
1 010 ~ 1 150, fast-cooling
44
S31653
022Cr17Ni12Mo2N
00Cr17Ni13Mo2N
1 010 ~ 1 150, fast-cooling
45
S31688
06Cr18Ni12Mo2Cu2
0Cr18Ni12Mo2Cu2
1 010 ~ 1 150, fast-cooling
46
S31683
022Cr18Ni14Mo2Cu2
00Cr18Ni14Mo2Cu2
1 010 ~ 1 150, fast-cooling
49
S31708
06Cr19Ni13Mo3
0Cr19Ni13Mo3
1 010 ~ 1 150, fast-cooling
50
S31703
022Cr19Ni13Mo3
00Cr19Ni13Mo3
1 010 ~ 1 180, fast-cooling
52
S31794
03Cr18Ni16Mo5
0Cr18Ni16Mo5
1 030 ~ 1 150, fast-cooling
55
S32168
06Cr18Ni11Ti*
0Cr18Ni10Ti*
920 ~ 1 150, fast-cooling
62
S34778
06Cr18Ni11Nb*
0Cr18Ni11Nb*
980 ~ 1 150, fast-cooling
64
S38148
06Cr18Ni13Si4
0Cr18Ni13Si4
1 010 ~ 1 150, fast-cooling
a
When it is indicated in contract by the Buyer, it may conduct heat treatment, in this case, the heat treatment temperature shall be 850°C
~ 930°C.
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Page 30 of 39
GB/T 1220-2007
(Informative) Stainless steel properties and applications
Table B.1 Code in GB/T 20878
Unified numerical code
New grade
Stainless steel properties and applications
Previous grade
Properties and applications
1Cr17Mn6Ni5N
Ni-free type steel, its property is similar to 12Cr17Ni7 (1Cr17 Ni7), which can be used in place of 12Cr17Ni7 (1Cr17Ni7). It is nonmagnetic in solution state and slightly magnetic after cold processing. It is mainly used for manufacturing hotel facilities, kitchenware, water pool and traffic means, etc.
1Cr18Mn8Ni5N
Ni-free type steel is the most typical and better developed Cr-Mn-Ni-N type steel. It possesses very good anti-oxidation property below 800°C while keeping higher strength, which can be used in place of 12Cr18Ni9(1Cr18Ni9). It is mainly used for manufacturing the parts subject to weak media corrosion and load below 800°C, such as cooking utensils and tableware, etc.
1Cr17Ni7
Metastable austenite steel is the steel subject to easiest cold deformation strengthening. It can obtain high strength and hardness through cold processing while keeping sufficient plastic strength, it possesses better corrosion resistance under atmospheric conditions. It is mainly used to manufacture the equipment and units that are to withstand higher load under cold processing state while expecting lighter weight and corrosion resistance, such as railway cars, decoration plates, conveyer belt and fasteners, etc.
Austenite type 1
3
9
S35350
S35450
S30110
12Cr17Mn6Ni5N
12Cr18Mn9Ni5N
12Cr17Ni7
13
S30210
12Cr18Ni9
1Cr18Ni9
The austenite stainless steel with the longest history possesses excellent plasticity, toughness and cold processing property in solid solution state and better corrosion resistance in oxidable acid, atmosphere, water, steam or other media. Cold processing shall offer high strength, but its elongation is a slightly poorer than 12Cr17Ni7(1Cr17Ni7). It is mainly used to manufacture the structural parts and welded parts with lower requirements on corrosion resistance and strength, such as external decoration materials of buildings; it can be used f or nonmagnetic parts and parts for low temperature device. But it intends to have intergranular corrosion in sensitizing state or after welding, so, it is not proper to be used as welded structural material.
15
S30317
Y12Cr18Ni9
Y1Cr18Ni9
12Cr18Ni9(1Cr18Ni9) improved cutting property steel. It is the best material to make roller, shaft, bolt and nut, etc., by fast cutting (by automatic lathe, etc.)
Y1Cr18Ni9Se
In addition to adjustment made to phosphonium and sulphur contents in 12Cr18Ni9(1Cr18Ni9) steel, selenium has also been added to improve the cutting property of 12Cr18Ni9(1Cr18Ni9) steel. It is applicable to less cutting volume, and also suitable for hot processing or cold processing, such as screw and rivet, etc.
0Cr18Ni9
A steel developed on the basis of 12Cr18Ni9(1Cr18Ni9) steel, its property is similar to 12Cr18Ni9(1Cr18Ni9) steel, but its corrosion resistance is better than 12Cr18Ni9(1Cr18Ni9) steel, it can be used to make welded part of small section dimension, so it is a kind of stainless steel of largest quantity and most extensive range in application. It is suitable for manufacturing deep-punching formed parts, as well as acid delivery pipe, vessel and structural parts, etc., it can also be used to make nonmagnetic/low-temperature equipment and parts
16
17
S30327
S30408
Y12Cr18Ni9Se
06Cr19Ni10
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Page 33 of 39
GB/T 1220-2007
Table B.1 (continued) Code in GB/T 20878
Unified numerical code
New grade
Previous grade
83
S11203
022Cr12
00Cr12
85
S11710
10Cr17
1Cr17
86
S11717
Y10Cr17
Y1Cr17
88
S11790
10Cr17Mo
1Cr17Mo
94
S12791
008Cr27Mo
00Cr27Mo
95
S13091
008Cr30Mo2
00Cr30Mo2
96
S40310
12Cr12
1Cr12
97
S41008
06Cr13
0Cr13
98
S41010
12Cr13
1Cr13
100
S41617
Y12Cr13
Y1Cr13
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Properties and applications
It contains less carbon than 022Cr13 (0Cr13), with better bending property at welded position, processing property and high temperature oxidation resistance. It can applied in vehicle exhaust treatment device, boiler combustion chamber, nozzle, etc. It features high corrosion resistance, mechanical property and thermal conductivity with stainlessness in atmosphere, water vapor or other media, but its stainlessness is not sufficient in the media containing higher chloride ion. It is mainly used in the chemical facilities producing nitric acid and grisoutite, such as absorption tower, heat exchanger, storage tank, etc.; sheet plate is mainly applied in internal decorations of building, office equipment, kitchen utensil, car decoration and gas burner, etc. As its brittleness changing temperature is higher than room temperature and it is sensitive to notching, it is not suitable to be used to make the equipment and parts to withstand load below room temperature, and the section dimension for the steel material commonly used shall not exceed 4mm It is a steel for cutting purpose improved from 10Cr17(1Cr17) mainly used to make the parts to be processed with large cutting volume by automatic lathe, such as bolt and nut, etc. Molybdenum is added to 10Cr17(1Cr17) steel to improve the pitting corrosion resistance, crevice corrosion resistance and strength of the steel, its salt solution resistance is better than 10Cr17(1Cr17) steel. It is mainly used as material for vehicle hub, fastener and external decoration of vehicle It is the earliest steel among high pure ferrite stainless steel, its properties are similar to 008Cr30Mo2(00Cr30Mo2) steel. It is suitable for the applications requiring both corrosion resistance and soft-magnetic It is a high pure ferrite stainless steel with low brittleness changing temperature and good property of halogen ion stress corrosion damage resistance, its corrosion resistance is equivalent to pure nickel, possessing excellent toughness, processing/forming properties and welding performance. It is mainly applied in complete set of equipment for chemical industry (acetic acid, lactic acid or other organic acids and super alkali concentration engineering), food industry, oil refining industry, electric power industry, water treatment industry and pollution control, etc., to make heat exchanger, pressure vessel, tank and other equipment Martensite type It is an excellent heat-resisting stainless steel for steam turbine blades and high-stress parts Applicable to parts requiring higher toughness and subject to impact load, such as steam turbine blades, structural frame, lining, bolt and screw cap, etc. It is a semi-martensite type stainless steel with higher strength and toughness through quench tempering treatment, it possesses excellent corrosion resistance and machining property. It is mainly applied to the parts requiring higher toughness, stainlessness and subject to impact load, such as cutting tool, blade, fastener, valve for water press and pyrolysis ant-sulphur corrosion equipment, etc.; it can also be used to make the equipment and parts requiring weak corrosive media resistance under normal temperature condition It is a steel with best cutting property among stainless steel, used for automatic lathe
Page 37 of 39
GB/T 1220-2007
Table B.1 (continued) Code in GB/T 20878
Unified numerical code
New grade
Previous grade
112
S44090
95Cr18
9Cr18
115
S45710
13Cr13Mo
1Cr13Mo
116
S45830
32Cr13Mo
3Cr13Mo
117
S45990
102Cr17Mo
9Cr18Mo
118
S46990
90Cr18MoV
9Cr18MoV
136
S51550
05Cr15Ni5Cu4Nb
137
S51740
05Cr17Ni4Cu4Nb
138
S51770
07Cr17Ni7A1
139
S51570
07Cr15Ni7Mo2A1
Properties and applications
High-carbon Martensite type stainless steel. Corrosion resistance is better than Cr17 type Martensite type stainless steel, while other properties are similar to Cr17 type Martensite type stainless steel. It is mainly used to make corrosion resistant and wearing resistant high-strength parts, such as shaft, pump, valve element, levers, spring and fastener, etc. Uneven carbohydrate is easy to form in this steel to affect steel quality and property, which shall be noted in production. It is high strength steel with better corrosion resistance than 12Cr13(1Cr13) steel. It is used to make steam turbine blades and high temperature parts, etc. Molybdenum is added to 30Cr13(3Cr13) steel to improve steel strength and hardness, which has also strengthened secondary hardening effect, and it corrosion resistance is better than 30Cr13(3Cr13) steel. Its main applications are similar to 30Cr13(3Cr13) steel The property and applications are similar to 95Cr18(9Cr18) steel. Because molybdenum and vanadium are added to this steel, its high temperature strength and anti-tempering capacity are better than 95Cr18(9Cr18) steel. The main applications are the same as 30Cr13(3Cr13) steel. It is mainly used to make the parts to withstand friction and work in corrosive media, such as measuring tool and cutting tool, etc.
Precipitation-hardening type It is martensite precipitation-hardening type stainless steel developed from 05Cr17Ni4Cu4Nb (1Cr17Ni2) steel, in addition to high strength, it possesses also high transverse toughness and sound forgeability, its corrosion resistance is equivalent to 05Cr17Ni4Cu4Nb (1Cr17Ni2) steel, it is mainly applied to the service environment requiring not only high strength and good toughness, but also excellent corrosion resistance, such as high strength forged parts, valve elements of high pressure system and parts of air plane It is martensite precipitation-hardening type stainless steel added with copper and niobium, its strength can be adjusted through changing heat treatment technique, the corrosion resistance is better than Cr13 type, 95Cr18(9Cr18) and 14Cr17Ni2 (1Cr17Ni2) steels, the resistance to corrosion, fatigue and water drop erosion is better than 12% martensite type stainless steel, welding procedure is simple and easy to be 0Cr17Ni4Cu4Nb processed, but it is hard to conduct deep cold forming. It is mainly used to make high strength parts requiring both of stainlessness and resistance to corrosion of weak acid, alkalis and salt. Such as the final level moving blade of steam turbine and the structural parts working in corrosive environment with operating temperature to be less than 300°C It is semi-martensite precipitation-hardening type stainless steel added with aluminium, the compositions is nearly the same as 18-8 type austenite stainless steel with excellent melting and processing properties. It can be used to make the structural parts, vessel, pipe, spring, washer and measuring device parts to work 0Cr17Ni7A1 below 350°C for a prolonged period of time. The technique for heat treatment of this steel is complicated, so there is tendency to be substituted by martensite ageing worldwide, but there are still extensive application fields It is a semi-martensite precipitation-hardening type stainless steel using 2% Mo to substitute 2% Cr in 07Cr17NiAl (0Cr17NiAl) steel to improve its resistance to the corrosion of reductive media and its comprehensive performance is better than 0Cr15Ni7Mo2A1 07Cr17NiAl (0Cr17NiAl) steel. It is used to make the high strength vessel, parts and structural parts with certain corrosion resistant requirements in astronautical navigation, petrochemical and energy fields, etc.
__________ END __________
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Page 39 of 39
