This standard specifies the classification, code, dimensions, technical requirements, test methods, acceptance rules, etc. of high-quality carbon structural steel hot-rolled steel plates and strips for automobile manufacturing. This standard is applicable to high-quality carbon structural steel hot-rolled steel plates and strips with a thickness of 2.00~14.00 mm for the manufacture of automobile cold stamping parts and cold-bent parts. GB/T 3275-1991 High-quality carbon structural steel hot-rolled steel plates and strips for automobile manufacturing GB/T3275-1991 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
High-quality carbon structural steel for automobile manufacturing
Hot-rolled steel plates and strips
Hot-rolled quality carbon structural steel plates and strips for automobile 1 Subject content and scope of application
GB 3275--91
Replaces GB3275-82
This standard specifies the classification, code, dimensions, technical requirements, test methods, acceptance rules, etc. of hot-rolled quality carbon structural steel plates and strips for automobile manufacturing.
This standard applies to hot-rolled quality carbon structural steel plates and strips with a thickness of 2:00~14.00mm for the manufacture of cold stamping parts and cold bending parts of automobiles.
2 Reference standards
GB222 Sampling method for chemical analysis of steel and allowable deviation of chemical composition of finished products Chemical analysis methods for metals and alloys
Method for determining the depth of decarburized layer in steel
Metal tensile test method
Metal Brinell hardness test method
GB 247
Metal bending test method
General provisions for acceptance, packaging, marking and quality certification of sawn plates and steel strips Technical conditions for high-quality carbon structural steel
GB 699
Dimensions, shape, weight and allowable deviations of hot-rolled steel plates and steel strips GB 2975
GB6394
GB6397
Steel mechanical and process performance test sampling regulationsMethod for determining average grain size of metal
Metal tensile test specimen
Method for evaluating the microstructure of YB31 steel
3 Classification and code
Steel plates and strips are divided into three categories according to the deformation of automobile manufacturing processing: Deep drawing S
Ordinary drawing P
Cold bending W
4 Dimensions, shape and allowable deviation
4.1 The dimensions of steel plates and strips shall comply with the provisions of GB709. 4.2 The thickness allowable deviation of steel plates and strips shall comply with the provisions of Table 1. Approved by the State Technical Supervision Bureau on March 26, 1991, and implemented on November 1, 1991
Common thickness
(steel hoops and steel strips)
2. 50--2. 20
>2. 20~-2. 50
>3. 90~-3. 5]
8. 51 ~-4. 00
.>4. 00~-5. 50
>6. 60 ~-7. 50
>7. 50--14. 00
Advanced precision
4.3 Allowable deviation of the width of steel plates and steel strips
4.3.! The allowable deviation of the width of the steel plate
Width 800mm.+amm;
b.Width>800mm,*,-10 mm,
4. 3. 2 The allowable deviation of the thickness of the strip
Standard steel strip:
Width ≤1.000 mm.
Width ≥[ 000 mm..-.,+3C mm,
Cutting steel strip:
Width ≤i nc0 mm,*.**,—5 mm;
Height ≥1 000 mm.*,+[0 mm,
4.4 The allowable deviation of the length of the steel plate Www.bzxZ.net
Steel plate length:
a.2 000 mm..**+10 m:
? 000 um.... +?5 mm.
4. 5 Unevenness of steel plate per meter
Thickness:
a.mm......12mm:
b. ->4~10mm.***,$10 mm:
.>10 mm,..,3 mum.
5 Technical requirements
5.1 Grade and chemical composition
GB 3275 9 T
The roughness at the following widths is allowed to be different
Higher precision
= 3, 17
Ordinary precision
Advanced precision
= 0 28
Mosquito high precision
5.1.1 The grades of steel include: 08, 08F, 08A1.10, 10F, 15, 15F, 15A1, 20.25, 30, 35.+0, 45, 50 steel. tm
Ordinary steel
5.1.2 Chemical composition (melting analysis) of steel. 08A1 and 15A1 steels shall comply with the requirements in Table 2. Other steel grades shall comply with the requirements in GB 699.
3.05 -- 0.12
0.12-~0.9
5.1.2.1 Lead content of 5AI is not a delivery condition. GB3275-91
Chemical or chemical analysis.
0.25 ~0.635
0.35-~0.65
0.02--0.07
0.02~0.07
5.1. 3 Under the condition that the chemical properties of steel products meet the requirements of this standard; the lower limit of carbon and sawdust content in 08F, 08A1, 08, 10, 10F, 15AI, 15, 20 steels can be regarded as not being a delivery condition, but their content (melting analysis) should be noted in the quality certificate. 5.1.4 The allowable deviation of the chemical composition of the steel plates and strips should meet the requirements of GB222. 5.2 Delivery status
The steel plates and strips are delivered after heat treatment and pickling. The heat treatment method should be noted in the contract. The party agrees that the steel plates and strips may not be treated with annealing, but the steel plates and strips that are not heat treated shall ensure that the pre-inspection results meet the requirements of this standard.
Due to equipment conditions, they can be delivered without pickling, but a pickling margin of 0.1 mm must be left. 5.3 Mechanical properties, process properties and microstructure The mechanical properties, process properties and microstructure of steel plates and strips shall comply with the requirements in Table 3. 5.3. 1
Test requirements
Min brand
08, 1CF, :0
Tensile strength
275--370
275-420
:315~/440
315~-440
345~-490
39G540
150635
10~655
$10~685
540-~735
Not small hand
Brinell hardness
Not to
Cold driving test
2 = 2r
— 2s
Free permeability
Crystallinity
--1 velvet
5~1 level
6~:1 level
5~i source
5~! level
5--:1 level
5.3.1.1 For deep-drawn steel plates and strips, tests 1 to 7 as specified in Table 3 shall be carried out. 5.3.1.2 For continuous-drawn steel plates and strips, tests 1 to 4 as specified in Table 3 shall be carried out. 5.3.1.3 For dry-cold-bent steel plates and strips, tests 1, 2 and 4 as specified in Table 3 shall be carried out. 0~3 level
0~3 velvet
banded structure
1-~3 level
5.408Al, 35A1 steel plates and strips shall be subjected to wide cold bending (B-35mm) test. If the wide cold bending test fails, it is allowed to be delivered according to the narrow cold bending test.
5.5 Free cementite and banded structure shall be graded according to the first and second rating diagrams in the YB31 standard respectively. GB3275—91
5.6 According to the requirements of the buyer, the depth of the surface decarburized layer of steel plates and strips above No. 30 steel shall be checked according to the provisions of the GB221 standard. The depth of the full decarburized layer (ferrite) shall not exceed 2.5% on one side and 4% on both sides. 5.7 Surface quality
5.7.1 There shall be no bubbles, cracks, scars, folds, inclusions and separation on the surface of steel plates and strips. If there are any defects on the surface of the steel plate, they can be removed with a chisel or grinding wheel: but the minimum thickness of the steel plate must be ensured. The surface defects of the steel plate shall not be filled or welded.
5.7.2 The following defects are allowed on the surface of the steel plate and steel strip, which do not exceed half of the thickness tolerance of the steel plate and steel strip: generally slight and local cracks, scratches, rolling marks and pits (pits within half of the thickness tolerance, no more than 2 per square meter). 6 Test method
6.1 The test items, number of samples, sampling methods and test methods of each batch of steel plates and strips shall comply with the provisions of Table 4 and 6.2 and 6.3 of this standard.
6.2 Tensile, cold bending and microstructure samples can be cut from the same sheet or roll of steel plates or strips. 6.3 Hardness samples must be cut from three stainless steel plates or directly tested on three steel plates. One hardness test specimen is taken for each roll of continuous rolled steel strip.
Test Items
Chemical Analysis
Product Particle Size
Free Cementite
Strip Short Weave
Complete Delamination
7 Acceptance Rules
Number of Samples (pcs)
1(Sensitive Tank Number)
Sampling Method
GB2975
GB 6397
GB2975
Test Method
GB 288 Test Method P04, PC5
GB6394
7.1Steel plates and steel strips shall be accepted in batches. Each batch shall consist of steel plates and steel strips with the same furnace number, thickness, grade and heat treatment system (heat treated). The weight of each batch shall not exceed 40 t. 7.2 The re-inspection of steel plates and steel strips shall comply with the provisions of CB247 standard. 8 Packaging, marking and quality certificate
The packaging, marking and quality certificate of steel plates and steel strips shall comply with the provisions of GB247 standard. Additional notes:
GB3275-91
This standard was proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard was drafted by Anshan Iron and Steel Company and the Information and Standards Research Institute of the Ministry of Metallurgy. The main drafters of this standard are Wang Huifan, Tong Wenying and Tang Fan. The horizontal grade mark of this standard
GB327591J
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