GB
ICS 77.140.75 H 48
National Standard Standard of the People's Republic of China
GB/T 8162-2008 Replace GB/T 8162-1999
Seamless Steel Tubes for Structural Purposes
Issued on August 19, 2008 Jointly issued by
Implemented on April 1, 2009
the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China and Standardization Administration Of The People's Republic of China.
Forwards This national standard is not equivalent to EN 10297-1: 2003 "Seamless Circular Steel Tubes for Mechanical and General Engineering Purposes-Technical Delivery Conditions". This national standard replaces GB/T 8162-1999 "Seamless Steel Tubes for Structural Purposes", while comparing with it, this Standard has the following major variation: ——add order content; ——modify allowable deviation of the dimension; ——add requirements of the full-length tortuosity factor; ——add requirements of the terminal shear drag; ——cancel marking illustrations; ——add steel grades; ——cancel requirements of the expanding test; ——add negotiation provisions of the nondestructive test This national standard is proposed by China Iron & Steel Association. This national standard is under jurisdiction of China Steel Standardization Technical Committee. This Standard is mainly prepared (organizations) by Angang Steel Company Limited, Pangang Group Chengdu Iron & Steel Co., Ltd. and Hunan Hengyang Steel Tube Group Co., Ltd. This Standard is mainly prepared by (staffs): ZHANG Huixuan, ZHANG Peng, PIAO Zhimin, LI Qi, ZHAO Bin and LI Zhi. This national standard replaces the previous versions: ——GB/T 8162-1987, GB/T 8162-1999
Forwards This national standard is not equivalent to EN 10297-1: 2003 "Seamless Circular Steel Tubes for Mechanical and General Engineering Purposes-Technical Delivery Conditions". This national standard replaces GB/T 8162-1999 "Seamless Steel Tubes for Structural Purposes", while comparing with it, this Standard has the following major variation: ——add order content; ——modify allowable deviation of the dimension; ——add requirements of the full-length tortuosity factor; ——add requirements of the terminal shear drag; ——cancel marking illustrations; ——add steel grades; ——cancel requirements of the expanding test; ——add negotiation provisions of the nondestructive test This national standard is proposed by China Iron & Steel Association. This national standard is under jurisdiction of China Steel Standardization Technical Committee. This Standard is mainly prepared (organizations) by Angang Steel Company Limited, Pangang Group Chengdu Iron & Steel Co., Ltd. and Hunan Hengyang Steel Tube Group Co., Ltd. This Standard is mainly prepared by (staffs): ZHANG Huixuan, ZHANG Peng, PIAO Zhimin, LI Qi, ZHAO Bin and LI Zhi. This national standard replaces the previous versions: ——GB/T 8162-1987, GB/T 8162-1999
Contents Forwards ........................................................................................................................................... I 1. Scope.............................................................................................................................................1 2. Normative References...................................................................................................................1 3. Order content ................................................................................................................................4 4. Dimension, shape and weight .......................................................................................................4 4.1 Outside diameter and wall thickness...................................................................................4 4.2 Allowable Allowable deviation of outside diameter and wall thickness thickness ..............................................4 4.3 Length .................................................................................................................................5 4.4 Tortuosity Tortuosity factor.................................................................................................................. 6 4.5 Noncircularity Noncircularity and wall unevenness unevenness ...................................................................................6 4.6 Terminal Terminal shape ....................................................................................................................6 4.7 Weight .................................................................................................................................7 5. Technical Technical requirements .................................................................................................................7 5.1 Grade of steel and chemical chemical composition ...........................................................................7 5.2 Manufacturing method........................................................................................................8 5.3 Delivery state ......................................................................................................................8 5.4 Mechanical Mechanical properties .........................................................................................................9 5.5 Technical Technical properties ..........................................................................................................13 5.6 Surface quality ..................................................................................................................13 5.7 Nondestructive test............................................................................................................14 14 6. Test Test method ................................................................................................................................. .................................................................................................................................14 7. Inspection rules ...........................................................................................................................15 8. Packaging, marking and quality certification..............................................................................15
Seamless Steel Tubes for Structural Purposes
结构用无缝钢管 GB/T 8162-2008
1. Scope This national standard specifies order content, size, shape, weight, technical requirements, test methods, test rules, packaging, marking and quality certificate of seamless steel tubes for structural purposes. This Standard is applicable to seamless steel tubes for mechanical and general engineering structural purposes.
2. Normative References The following standards contain provisions which, through reference in this text, constitute provisions of this national Standard. For dated reference, subsequent amendments (excluding amending error in the text) to, or revisions of, any of these publications do not be applied. However, the parties whose enter into agreement according to these specifications a re encouraged to research whether the latest editions of these references are applied or not. For undated references, the latest edition of the normative document is applicable to this national standard. GB/T 222 Permissible Tolerances 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 Phosphorus ContentGB/T 223.5 Methods for Chemical Analysis of Iron, Steel and Alloy; the Reduced Molybdosilicate 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 Iron Steel and Alloy-Determination of Aluminium Content-Chrom Azurol S Photometric Method GB/T 223.11 Methods for Chemical Analysis of Iron, Steel and Alloy; the Ammonium Persulfate Oxidation Volumetric Method for the Determination of Chromium Content GB/T 223.12 Methods for Chemical Analysis of Iron, Steel and Alloy; The Sodium Carbonate Separation-diphenyl Carbazide Photometric Method for the Determination of Chromium Content GB/T 223.13 Methods for Chemical Analysis of Iron, Steel and Alloy; the Ammonium Ferrous Sulfate Titration Method for the Determination of Vanadium Content GB/T 223.14 Methods for Chemical Analysis of Iron, Steel and Alloy; the
N-benzoy-N-phenylhydroxylamine Extraction Photometric Method for the Determination of Vanadium Content GB/T 223.16 Methods for Chemical Analysis of Iron, Steel and Alloy; the Chromotropic Acid Photometric Method for the Determination of Titanium Content GB/T 223.18 Methods for Chemical Analysis of Iron, Steel and Alloy; the Sodium Thiosulfate Separation Iodimetric Method for the Determination of Copper Content GB/T 223.19 Methods for Chemical Analysis of Iron Steel and Alloy; the Neocuproine-chloroform Extraction Photometric Method for the Determination of Copper Content GB/T
223.23
Iron
Steel
and
Alloy-Determination
of
Nickel
Content;
the
Dimethylglyoxime Spectrophotometric Method GB/T 223.25 Methods for Chemical Analysis of Iron, Steel and Alloy; the Dimethylglyoxime Gravimetric Method for the Determination of Nickel Content GB/T 223.26 Iron Steel and Alloy-Determination of Molybdenum Content; the Thiocyanate Spectrophotometric Method GB/T 223.36 Methods for Chemical Analysis of Iron, Steel and Alloy; the Neutral Titration Method for the Determinaion of Nitrogen Content after Distillation Separation GB/T 223.37 Methods for Chemical Analysis of Iron Steel and Alloy; the Indophenal Blue Photometric Methods for the Determination of Nitrogen Content after Distillation Separation GB/T 223.40 Methods for Chemical Analysis of Iron, Steel and Alloy; the Sulphochlorophenol S Photometric Method for the Determination of Niobium Content GB/T 223.43 Iron Steel and Alloy-Determination of Tungsten Content-Gravimetric Method and Spectrophotometric Method GB/T 223.53 Methods for Chemical Analysis of Iron, Steel and Alloy; the Flame Atomic Absorption Spectrophotometric Method for the Determination of Copper Content GB/T 223.54 Methods for Chemical Analysis of Iron, Steel and Alloy; the Flame Atomic Absorption Spectrophotometric Method for the Determination of Nickel Content GB/T 223.58 Methods for Chemical Analysis of Iron, Steel and Alloy; the Sodium Arsenite-sodium Nitrite Titrimetric Method for the Determination of Manganese Content GB/T 223.59 Methods for Chemical Analysis of Iron, Steel and Alloy; the Reduced Molybdoantimonyl Phosphoric Acid Photometric Method for the Determination of Phosphorus Content GB/T 223.60 Methods for Chemical Analysis of Iron, Steel and Alloy; the Perchloric Acid Dehydration Gravimetric Method for the Determination of Silicon Content GB/T 223.6l Methods for Chemical Analysis of Iron, Steel and Alloy; the Ammonium Phosphomolybdate Volumetric Method for the Determination of Phosphorus Content GB/T 223.62 Methods for Chemical Analysis of Iron, Steel and Alloy; the Butyl Acetate Extraction Photometric Method for the Determination of Phosphorus Content GB/T 223.63 Methods for Chemical Analysis of Iron, Steel and Alloy; the Sodium (Potassium) Periodate Photometric Method for the Determination of Manganese Content GB/T 223.64 Iron Steel and Alloyed-Determination of Manganese Content-Flame Atomic Absorption Spectrometric Method GB/T 223.66 Methods for Chemical Analysis of Iron, Steel and Alloy; the
Thiocyanate-chlorpromazine Hydrochloride-Chloroform Extraction Photometric Method for the Determination of Tungsten Content GB/T 223.67 Iron Steel and Alloy-Determination of Sulfur Content-Methylene Blue Spectrophotometric Method GB/T 223.68 Methods for Chemical Analysis of Iron, Steel and Alloy; the Potassium Iodate Titration Method after Combustion in the Pipe Furnace for the Determination of Sulfur Content GB/T 223.69 Methods for Chemical Analysis of Iron, Steel and Alloy; the Gas-Volumetric Method after Combustion in the Pipe Furnace for the 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 the Determination of Carbon Content GB/T 223.72 Iron Steel and Alloy-Determination of Sulfur Content-Gravimetric Method GB/T 223.74 Methods for Chemical Analysis of Iron, Steel and Alloy; the Combustion Gravimetric/gas-Volumetric Method for the Determination of Combined Carbon Content GB/T 223.75 Iron Steel and Alloy-Determination of Boron Content-Methanol Distillation-Curcumin Photometric Method GB/T 223.76 Methods for Chemical Analysis of Iron, Steel and Alloy; the Flame Atomic Absorption Spectrometric Method for the Determination of Vanadium Content GB/T 223.78 Methods for Chemical Analysis of Iron, Steel and Alloy-Curcumin Spectrophotometric Method for the Determination of Boron Content (GB/T 223.78-2000, ISO 10153: 1997, IDT) GB/T 228 Metallic Materials-Tensile Testing at Ambient Temperature (GB/T 228-2002, eqv ISO 6892: 1998) GB/T 229 Metallic Materials—Charpy Pendulum Impact Test Method (GB/T 229-2007, ISO 148-1: 2006, MOD) GB/T 231.1 Metallic Materials-Brinell Hardness Test-Part 1: Test Method (GB/T 231.1-2002, ISO 6506-1: 1999, EQV) GB/T 244 Metallic Materials-Tube-Bend Test (GB/T 244-2008, ISO 8491: 1996, IDT) GB/T 246 Metal materials—Tube—Flattening test (GB/T 246-2007, ISO 8492: 1998, IDT) GB/T 699 Quality Carbon Structural Steels GB/T 1591 Low-alloy High-tensile Structural Steel GB/T 2102 Acceptance Packing, Marking and Quality Certification of Steel Pipe 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 3077 Alloy Structure Steels GB/T 4336 Standard Test Method For Spark Discharge Atomic Emission Spectrometric Analysis of Carbon and Low-alloy Steel (Routine Method) GB/T 5777 Seamless Steel Pipe and Tubing-methods for Ultrasonic Testing (GB/T 5777-2008, ISO 9303: 1989, MOD) GB/T 7735 Steel Tubes—the Inspection Method on Eddy Current Test (GB/T 7735-2004, ISO 9304: 1989, MOD) GB/T 12606 Steel Tubes-The Testing Method of Magnetic Flux Leakage (GB/T 12606-
1999, eqv ISO 9402: 1989, ISO 9598: 1989) GB/T 17395 Dimensions, Shapes, Masses and Tolerances of Seamless Steel Tubes (GB/T 17395-2008, ISO 1127: 1992, ISO 4200: 1991, ISO 5252: 1991, NEQ) GB/T 20066 Steel and Iron-Sampling and Preparation of Samples for the Determination of Chemical Composition (GB/T 20066--2006, ISO 14284: 1996, IDT) GB/T 20123 Steel and Iron—Determination of Total Carbon and Sulfur Content Infrared Absorption Method after Combustion in an Induction Furnace (Routine Method) (GB/T 20123-2006, ISO 15350: 2000, IDT) GB/T
20124
Steel
and
Iron—Determination
of
Nitrogen
Content—Thermal
Conductimetric Method after Fusion in a Current of Inert Gas (Routine Method) (GB/T 20124-2006, ISO 15351: 1999, IDT) GB/T 20125 Low-Alloy Steel-Determination of Multi-element Contents-Inductively Coupled Plasma Atomic Emission Spectrometric Method
3. Order content Contract or order ordering steel pipes according to this Standard shall include the following contents: a) Standard number; b) Product name; c) Grade of steel, quality classification must be indicated while necessary; d) Dimensions; e) Order quantity (total weight or total length); f) Delivery state; g) Special requirement
4. Dimension, shape and weight
4.1 Outside diameter and wall th ickness The outside diameter (D) and wall thickness (S) of steel tubes shall comply with the provisions of GB/T 17395-1998. According to the requirements of the purchaser and through the mutual negotiation of both the purchaser and the supplier, the steel tube with other outside diameters and wall thicknesses can be supplied.
4.2 Allowable deviation of outside diameter and wall thick ness 4.2.1 The allowable deviation of outside diameter of the steel tube shall be in accordance with
those specified in Table 1.
Table 1 Allowable Deviation of Outside Diameter of the Steel Tube Steel tube kinds
Allowable deviation
Hot rolling (extruding and expanding) steel tube
±1%D or ±0.50, take the larger value
Cold drawing (rolling) steel tube
±1%D or ±0.30, take the larger value
in: mm
4.2.2 The allowable deviation of wall thickness of the hot rolling (extruding and expanding)
steel tube shall be in accordance with those specified in Table 2. Table 2 Allowable Deviation of Wall Thickness Hot Rolling (Extruding and Expanding) Steel Tube in: mm Nominal outside Steel tube kinds
S/D
Allowable deviation
≤102
—
±12.5%S or ±0.40, takes the larger value
>102
≤0.05
±15% S or±0.40, takes the larger value
>102
>0.05~0.10
±12.5% S or±0.40, takes the larger value
>102
>0.10
diameter of steel tube Hot rolling (extruding) steel tube
Hot rolling (extruding) steel tube
Hot expanding steel tube
12.5% S 10% S
—
±15%S
4.2.3 The allowable deviation of wall thickness of the cold drawing (rolling) steel tube shall
be in accordance with those specified in Table 3.0.2. Table 3 Allowable Deviation of Wall Thickness of the Cold Drawing (rolling) Steel Tube Steel tube kinds
Nominal wall thickness of steel tube
Cold drawing (rolling)
≤3
Cold drawing (rolling)
>3
in: mm
Allowable deviation 15% S 10% S or ±0.15, take the larger value
12.5% S +12.5%S 10% S
4.2.4 According to the requirements of the purchaser, through the mutual negotiation of both
the purchaser and the supplier and indicated in the contract, steel tube with allowable deviation of dimensions excluded of Table 1, Table 2 or Table 3.
4.3 Length 4.3.1 Usual length
Usual length of the steel tube is 3000mm~12500mm. 4.3.2 Scope length
According to requirements of the purchaser, through the mutual negotiation of both the purchaser and the supplier, and indicated in the contract, steel tube may be delivered according to the scope length. The length scope shall be within the scope of usual length. 4.3.3 Cut-to-length and multiple lengths 4.3.3.1 According to requirements of the purchaser, through the mutual negotiation of both
the purchaser and the supplier, and indicated in the contract, the steel tube may be delivered according to the cut length or multiple lengths. 4.3.3.2 The cut length of steel tube shall be within the usual length scope, and the allowable
deviation of the cut lengths shall comply with the following provisions: a) The cut length is no greater than 6000 mm,
10
mm;
b) The cut length is greater than 6000 mm,
15 0 mm.
4.3.3.3 Total multiple length of the steel tube shall be within the usual length, the full-length
allowable deviation is
20 0
mm, and multiple lengths shall be set aside kerf surplus according
to the following provisions: a) The outside diameter is no greater than 159 mm, 5 mm~10 mm; b) The outside diameter is greater than 159 mm, 10 mm~15 mm.
4.4 Tortuo sity factor 4.4.1 The tortuosity factor of steel tube per meter shall be in accordance with those specified
in Table 4. Table 4 Tortuosity Factor of Steel Tube Nominal wall thickness of steel tube /mm
Tortuosity factor of per meter (mm/m)
≤15
≤1.5
>15~30
≤2.0
>30 or D≥351
≤3.0
4.4.2 Full-length tortuosity factor of the steel tube shall be no greater than 1.5‰ of the total
steel tube length.
4.5 Noncircularity and wall unevenness According to the requirements of the purchaser, through the negotiation of both the purchaser and the supplier, and indicated in the contract, the noncircularity and wall unevenness of steel tube shall be no more than 80% of the outside diameter and wall thickness tolerances respectively.
4.6 Terminal shape 4.6.1 The steel tube with nominal outside diameter of no greater than 60 mm, the pipe
terminal shear drag shall be no more than 1.5 mm; the steel tube with nominal outside diameter of greater than 60 mm, the pipe terminal shear drag shall be no more than 2.5% of the nominal outside diameter of steel tube, but the maximum outside diameter shall be no more than 6mm. The shear drag of the steel tube sees Figure 1.
Figure 1 Shear Drag
4.6.2 Terminal kerf burr of the steel tube shall be removed.
4.7 Weight 4.7.1 The steel tube shall be delivered according to the actual weight, or it may be delivered
according to theoretical weight. Calculation for theoretical weight of the steel tube complies with GB/T 17395 and the steel density is 7.85 kg/dm 3. 4.7.2 According to the requirements of the purchaser, through mutual negotiation of the
purchaser and the supplier, and indicated in the contract, the deviation between theoretical weight and actual weight of the delivered steel tube shall comply with the following requirements: a) Unipivot steel tube: ±10%; b) Steel tube with minimum lot's weight of 10t:±7.5%.
5. Technical requirements
5.1 Grade of steel and chemical composi tion 5.1.1 The grade and chemical composition (heat analysis) of carbon constructional quality
steel shall comply with the requirements of 10, 15, 20, 25, 35, 45, 20Mn and 25Mn specified in GB/T 699. The grade and chemical composition (heat analysis) of the low-alloy high-tensile structural steel shall comply with GB/T 1591, therein, phosphine and sulfur content of steel with quality grade of A, B and C shall not be greater than 0.030%. The grade and chemical composition (heat analysis) of alloy structure steels shall comply with GB/T 3077. Chemical composition (heat analysis) of the steel in grades of Q235 and Q275 shall be in accordance with those specified in Table 5.
Table 5 Chemical Composition (Heat Analysis) of Q235 and Q275 Steel Chemical composition (mass fraction)a/% Grade
Quality grade
P C
Si
S
Mn
Alt(Total aluminium) b
No greater than A
≤0.22
— 0.030
B Q235
0.030
≤0.20
— ≤0.35
C
≤1.4
0.030
0.030
—
0.025
0.025
≥O.020
0.030
0.030
≤0.17
D A Q275
B
≤0.24 ≤0.21
— ≤0.35
—
≤1.50
C
0.030
0.030
—
0.025
0.025
≥O.020
≤0.20
D a
The content of residual elements Cr and Ni shall be no greater than 0.30%, and Cu content shall be no greater than
0.20%. b
When analyzing Als (acid-soluble aluminium), Als≥0.015%.
5.1.2 According to the requirements of the purchaser and through the mutual negotiation of
both the purchaser and the supplier, the steel tube with other grades can be produced. 5.1.3 When the purchaser requires product analysis, it shall be indicated in the contract, and
the allowable deviation of the chemical composition of the finished steel tube shall comply with GB/T 222.
5.2 Manufacturi ng method 5.2.1 Smelting process of steel
The steel shall be smelted with electric arc furnace plus out-of-furnace refining or oxygen converter plus out-of-furnace refining method. Through the mutual negotiation of the purchaser and the supplier, the steel may also be smelted by other method with higher requirements. If the purchaser specifies some smelting process, the smelting process shall be clearly indicated in the contract. 5.2.2 Manufacturing method of the tubular billet
The tubular billet is made by continuous casting or hot rolling (forging), and the steel ingot may also be used as tubular billet directly. 5.2.3 Manufacturing method of the steel tube
The steel tube shall be made with hot rolling (extruding and expanding) or cold drawing (rolling) seamless method. If the purchaser specifies some steel tube manufacturing process, the manufacturing process shall be clearly indicated in the contract.
5.3 Delivery state 5.3.1 The hot rolling (extruding and expanding) steel tube shall be delivered in hot rolling
state or heat treatment condition. If the purchaser requires delivery in heat treatment condition,
it shall be clearly indicated in the contract. 5.3.2 The cold drawing (rolling) steel tube shall be delivered in heat treatment condition.
According to the requirement of the purchaser, through the mutual negotiation of the purchaser and the supplier, and indicated in the contract, the cold drawing (rolling) steel tube may be delivered in cold drawing (rolling) state as well.
5.4 Mechanical properties 5.4.1 Tensile property 5.4.1.1 The tensile property of carbon constructional quality steel, low-alloy high-tensile
structural steel or Q235 and Q275 steel tubes shall be in accordance with those specified in Table 6 in their delivery state. 5.4.1.2 Sample roughcast of alloy structure steel tube is heat-treated according to heat
treatment system recommended in Table 7, and the longitudinal tensile property measured for the sample shall be in accordance with those specified in Table 7. 5.4.1.3 The mechanical properties of steel tube delivered in cold drawing (rolling) state
agreed by both the purchaser and the supplier.
Table 6 Mechanical Properties of Carbon Constructional Quality Steel, Low-alloy High-tensile Structural Steel, or Steel Tubes in Grades of Q235 And Q275
Quality
Post-breaking
ReLa/MPa
extensibility
Tensile strength
Grade grade
Lower yield strength
Rm/MPa
Wall thickness/mm
A/%
Impact test Absorbed energy Temperature /℃
No less than
KV2/J No greater than
10
—
≥335
205
195
185
24
—
—
15
—
≥375
225
215
205
22
—
—
20
—
≥410
245
235
225
20
—
—
25
—
≥450
275
265
255
18
—
—
35
—
≥510
305
295
285
17
—
—
45
—
≥590
335
325
315
14
—
—
20Mn
—
≥450
275
265
255
20
—
—
25Mn
—
≥490
295
285
275
18
—
—
—
—
A B
Q235
225
215
25
D
-20
A
— 415~540
275
265
255
22
0
D
-20 390~570
295
275
255
22
A
20
B C
470~630
345
325
295 21
A
18
B 490~650
390
370
350 19
A
18
B
34
—
—
— 20 -40
27
—
—
34
-20 — 40
27
—
—
520~680
420
400
380
0 19
-40
C
0 550~720
460
E a
440
420
17
34
-20
E
D
34
+20
D
Q460
+20
0
E
C
—
+20
D
Q420
27
—
0
E
C
—
+20
D
Q390
27
+20
C
B
Q345
+20 0
A
Q295
235
C
B
Q275
375~500
27 34
-20 — 40
27
During the tensile test period, if yield strength cannot be measured, the specified non-proportion extension intensity
RP0.2 may be measured to replace ReL.
Table 7 Mechanical Properties of Alloy Steel Tube Recommended heat treatment system a
Brinell Hardness
Tensile property
of steel tube Quenching (normalizing)
Tensile Lower yield Post- reaking
Tempering
Serial Grade number
Temperature /℃ Temperature Coolant For the
For the
/℃
strength
strength f
R m/MPa
R eL/MPa
extensibility A/%
annealing or high tempering in delivery state
Coolant No less than
No greater than
first time second time 1
40Mn2
840
2
45Mn2
3
Water and oil
540
Water and oil
885
735
12
217
840
Water and oil
550
Water and oil
885
735
10
217
27SiMn
920
Water
450
Water and oil
980
835
12
217
4
40MnB b
850
oil
500
Water and oil
980
785
10
207
5
45MnB b
840
oil
500
Water and oil
1030
835
9
217
6
20Mn2B b, c
880
oil
200
Water and air
980
785
10
187
835
540
10
179
785
490
10
179
7
c, e
20Cr
880
—
800
Water and oil
200
Water and air
8
30Cr
860
—
oil
500
Water and oil
885
685
11
187
9
35Cr
860
—
oil
500
Water and oil
930
735
11
207
10
40Cr
850
—
oil
520
Water and oil
980
785
9
207
11
45Cr
840
—
oil
520
Water and oil
1030
835
9
217
12
50Cr
830
—
oil
520
Water and oil
1080
930
9
229
13
38CrSi
900
—
oil
600
Water and oil
980
835
12
255
14
12CrMo
900
—
air
650
air
410
265
24
179
15
15CrMo
900
—
air
650
air
440
295
22
179
20CrMoc, e
885
685
11
197
16
880
—
Water and oil
500
Water and oil 845
635
12
197
17
35CrMo
850
—
oil
550
Water and oil
980
835
12
229
18
42CrMo
850
—
oil
560
Water and oil
1080
930
12
217
19
12CrMoV
970
—
air
750
air
440
225
22
241
20
12CrlMoV
970
—
air
750
air
490
245
22
179
38CrMoAIe
980
835
12
229
21
940
—
Water and oil
640
Water and oil 930
785
14
229
22
50CrVA
860
—
oil
500
Water and oil
1275
1130
10
255
23
20CrMn
850
—
oil
200
Water and air
930
735
10
187
24
20CrMnSie
880
—
oil
480
Water and oil
785
635
12
207
30CrMnSic, e
1080
885
8
229
25
880
—
oil
520
Water and oil 980
835
10
229
1620
—
9
229
26
35CrMnSiAe
880
—
oil
230
Water and air
Table 7 (Continued) Recommended heat treatment system a
Brinell
Tensile property
Hardness of Quenching (normalizing)
Lower
Tempering
Tensile
Post-breaking
steel tube
extensibility
annealing or
A/%
high tempering
yield strength
Serial Grade
Temperature /℃
number
R m/MPa Temperature Coolant
For the
/℃
strength f R eL/MPa
in delivery state
Coolant
For the second
No less than
No greater than
first time time 27
20CrMnTid-e
880
870
oil
200
Water and air
1080
835
10
217
28
30CrMnTid-e
880
850
oil
200
Water and air
1470
—
9
229
29
12CrNi2
860
780
Water and oil
200
Water and air
785
590
12
207
30
12CrNi3
860
780
oil
200
Water and air
930
685
11
217
31
12Cr2Ni4
860
780
oil
200
Water and air
1080
835
10
269
32
40CrNiMoA
850
—
oil
600
Water and oil
980
835
12
269
33
45CrNiMoVA
860
—
oil
460
oil
1470
1325
7
269
a
The permissible adjustment range of heat treatment temperature listed in the table: ±20℃ for quenching; ±30℃ for low-temperature tempering;
±50℃ f or high-temperature tempering. b
The boracic steel may be normalizing before quenching, and the normalizing temperature shall be no higher than its quenching temperature.
c
Delivered according to a group of data specified by the purchaser; when the purchaser is not specified, it may be delivered according to any
group of data therein. d
The first quenching of Cr-Mn-Ti steel may be replaced by normalizing.
e
Isothermal quenching at temperature of 280℃ ~ 320℃ .
f
During the tensile test period, if yield strength cannot be measured, the specified non-proportion extension intensity R P0.2 may be measured to
replace R eL.
5.4.2 Hardness test
The alloy structure steel tube delivered in annealing or high-temperature tempering state and in wall thickness of no greater than 5mm, the Brinell hardness shall be in accordance with those specified in Table 7. 5.4.3 Impact test
5.4.3.1 For low-alloy high-tensile structural steel and Q235 or Q275 steel tubes, when their outside diameter is no less than 70mm and their wall thickness is no less than 6.5 mm, impact test shall be made, while the impact absorbed energy and test temperature of its compound ratio V-notch impact test shall be in accordance with those specified in Table 6. Impact absorbed energy is calculated according to arithmetic mean value of three samples of one group, single value of one of the samples therein is permitted to be less than the specified value, but it shall be no less than 70% of the specified value. 5.4.3.2 Impact absorbed energy listed in Table 6 is the desired value of impact absorbed
energy for Charpy V-notch samples in standard dimension. When the steel tube dimension cannot prepare samples in standard dimension, undersized bearing samples may be prepared; when the undersized bearing impact sample is used, the desired value of minimum Charpy
energy of standard sized sample multiplied by reduction coefficient listed in Table 8. The dimension of the impact sample shall give preference to select larger dimension. Table 8 Reduction Coefficient of Impact Absorbed Energy for Undersized Bearing Sample Sample specifications
Sample size (height×width) (mm×mm)
Reduction coefficient
Standard sample
10×10
1.00
Small sample
10×7.5
0.75
Small sample
10×5
0.50
5.4.3.3 According to the requirements of the purchaser, through mutual negotiation of both
the purchaser and the supplier, and indicated in the contract, steel with other grades and quality grades may also be made with Charpy V test, and its test temperature, testing size and impact absorbed energy are determined by the agreement of both the purchaser and the supplier.
5.5 Technical properties 5.5.1 Flattening test
The steel tube made of steels in grades of 10, 15, 20, 25, 20Mn, 25Mn, Q235, Q275, Q295, Q345, with outside diameter of >22 mm~400mm and with wall thickness to outside diameter ratio of no greater than 10% shall be made with flattening test; after flattening, the flat plate interval of the steel tube shall be in accordance with those specified in Table 9. After flattening, crack or rupture is not allowed to emerge on the sample. Table 9 Flat Plate Interval after Steel Tube Flattening
a
Grade
Flat plate interval of the flattening test (H)a/mm
10, 15, 20, 25, Q235
2/3D
Q275, Q295, Q345, 20Mn, 25Mn
7/8D
The minimum value of flat plate interval (H) for the flattening test shall be 5×wall thickness of the steel tube.
5.5.2 Bending test
According to the requirements of the purchaser, through the mutual negotiation of both the purchaser and the supplier, and indicated in the contract, steel tube with the outside diameter of no greater than 22mm may be made with bending test, with bend angle of 90°, and bend core radius of 6×outside diameter of the steel tube; after the bending, the sample sinuosity is not allowed to emerge crack or rupture.
5.6 Surface quality Inside and outside surface of the steel tube are not allowed with visible crack, foldover, scar, rolling and delamination. These flaws shall be removed completely, and the removing depth shall not be more than the minus tolerance of the nominal wall thickness; the practical wall thickness at the removing part shall be no less than the minimum allow of the wall thickness deviation. As for other partial flaws, if their wall thickness is no less than the minus tolerance, they are allowed to be present.
5.7 Nondestru ctive t est According to the requirements of the purchaser, through mutual negotiation of both the purchaser and the supplier, and indicated in the contract, the steel tube may be nondestructive tested with one or more of the following methods, or with other methods. a) The artificial flaw dimension for making ultrasonic inspection according to GB/T 5777: L3 (C10) for cold drawing (rolling) pipe; L4 (C12) for hot rolling (extruding and expanding steel tube); b) Eddy current inspection is made according to requirements of GB/T 7735, with its acceptance grade is A; c) Magnetic leakage test is made according to requirements of GB/T 12606, with its acceptance grade is L4.
6. Test method 6.1 The dimensions and contour of steel pipe shall be measured with the measuring tools in line with accuracy requirement. 6.2 The internal and external surfaces of steel pipe shall be subject to visual inspection under sufficient lighting conditions. 6.3 The sampling method and test method for other inspection items of steel pipe shall meet the requirements as set in Table 10. Table 10 Inspection item, sampling quantity, sampling method and test method No.
Inspection item
sampling quantity
sampling method
test method
1
Chemical composition
One sample from each furnace
GB/T 20066
2
Tensile test
One sample from each of two pipes for each batch
GB/T 2975
GB/T 223 GB/T 4336 GB/T 20123 GB/T 20124 GB/T 20125 GB/T 228
3
Hardness test
One sample from each of two pipes for each batch
GB/T 2975
GB/T 231.1
4
Impact test
One group of 3 samples from each of two pipes for each batch
GB/T 2975
GB/T 229
5
Flattening test
One sample from each of two pipes for each batch
GB/T 246
GB/T 246
6
Bending test
One sample from each of two pipes for each batch
GB/T 244
GB/T 244
7 8
Ultrasonic flaw detection test Eddy current test
Piece by piece Piece by piece
-----
GB/T 5777
9
Magnetic flux leakage flaw detection test
Piece by piece
---
GB/T 12606
GB/T7735
7. Inspection rules 7.1 Examination and acceptance
The examination and acceptance of steel pipe shall be carried out by the quality and technical supervision department of the Supplier. 7.2 Rules for batch grouping 7.2.1 Examination and acceptance of steel pipe shall be conducted in terms of batch. 7.2.2 If the steel pipes are no longer heat treated after cut into single pieces, then, all the segments
cut from the steel pipe rolled from one pipe ingot shall be deemed as one piece. 7.2.3 Each batch shall be composed of the steel pipes of the same grade, the same furnace number,
the same size and the same treatment system (furnace). The quantity of each batch of steel pipes shall not exceed the following provisions: a) Outer diameter no greater than 76mm and wall thickness no greater than 3 mm: 400 pieces; b) Outer diameter greater than 351mm: 50 pieces; c) Other dimensions: 200 pieces. 7.2.4 When special requirements are proposed by the Buyer in advance, one batch can be
composed of the steel pipes of the same grade and the same size from different furnace numbers as for 10, 15, 20, 25, 35, 45, Q235, Q275, 20Mn and 25MN. 7.2.5 For the number of pieces of remaining steel pipes, if it is no less than 50% of the above
provisions, it shall constitute one batch separately, if less than 50% of the above provisions, it can be integrated into the adjacent batch of the same grade, furnace number and size. 7.3 Sampling quantity
The sampling quantity for each inspection item of each batch steel pipe shall meet the requirement of Table 10 hereof. 7.4 Rules for reinspection and determination
The reinspection and determination of steel pipes shall meet the requirement of GB/T 2102.
8. Packaging, marking and quality certification The packaging, marking and quality certification of steel pipes shall meet the requirement of GB/T 2102.
