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GB/T 20564 Continuously cold rolled high strength steel sheet and strip for Automobile is divided into 11 parts:
— Part 1: Bake hardening steel
— Part 2: Dual phase steel
— Part 3: High strength interstitial free steel
— Part 4: High strength low alloy steel
— Part 5: Isotropic steel
— Part 6: Transformation induced plasticity steel
— Part 7: Martensitic steels
— Part 8: Complex phase steel
— Part 9: Quenching and partitioning steel
— Part 10: Twinning induced plasticity steel
— Part 11: Carbon manganese steel
This part is the Part 11 of GB/T 20564.
This part is developed in accordance with the rules given in GB/T 1.1-2009.
This part was proposed by China Iron and Steel Association.
This standard is under the jurisdiction of the SAC/TC 183 National Technical Committee on Iron and Steel of Standardization Administration of China.
Continuously cold rolled high strength steel sheet and strip for automobile
— Part 11: Carbon manganese steel
1 Scope
This standard specifies the terms and definitions, classification and steel grade representation methods, order details, dimension, shape, weight, technical requirements, test methods, inspection rules, packaging, marking, and product quality certificate of cold-rolled carbon manganese high strength steel sheet and strip.
This part is applicable to the manufacture of automotive structural parts with a thickness of 0.50 mm ~ 3.00 mm steel sheet and strip (hereinafter referred to as “steel sheet and strip”).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 223.9 Iron, steel and alloy — Determination of aluminum content — Chrome azurol S photometric method
GB/T 223.59 Iron, steel and alloy — Determination of phosphorus content — Bismuth phosphomolybdate blue spectrophotometric method and antimony phosphomolybdate blue spectrophotometric method
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 223.68 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 Iron, steel and alloy — Determination of carbon contents — Gas-volumetric method after combustion in the pipe furnace
GB/T 228.1-2010 Metallic materials — Tensile testing — Part 1: Method of test at room temperature
GB/T 247 General rule of package, mark and certification for steel plates (sheets) and strips
GB/T 708 Dimension, shape, weight and tolerance for cold-rolled steel strip and sheet
GB/T 2523 Measuring method of surface roughness and peak count for cold-rolled metal sheet (strip)
GB/T 2975 Steel and steel products — Location and preparation of samples and test pieces for mechanical testing
GB/T 4336 Carbon and low-alloy steel — Determination of multi-element contents — Spark discharge atomic emission spectrometric method (routine method)
GB/T 8170 Rules of rounding off for numerical values & expression and judgement of limiting values
GB/T 17505 Steel and steel products — General technical delivery requirements
GB/T 20066 Steel and iron — Sampling and preparation of samples for the determination of chemical composition
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 20125 Low-alloy steel — Determination of multi-element contents — Inductively coupled plasma atomic emission spectrometric method
GB/T 20126 Unalloyed steel — Determination of low carbon content — Part 2: Infrared absorption method after combustion in an induction furnace (With preheating)
3 Terms and definitions
For the purposes of this standard, the following terms and definitions apply.
3.1
carbon manganese steel
on the basis of low carbon steel, carbon and manganese are the main solid solution strengthening elements, and the microstructure is composed of ferrite and a small amount of pearlite.
4 Classification and steel grade representation methods
4.1 Classification
4.1.1
Refer to Table 1 for the classification of steel sheets and strips by purposes.
Table 1 Classification of products by purposes
Steel grade Purpose
CR205S Structural member
CR235S
CR265S
CR295S
CR325S Structural members and reinforcing members
4.1.2
Refer to Table 2 for the classification of steel sheets and strips by surface quality.
Table 2 Surface quality classification
Grade Code
Superior grade surface FB
Higher grade surface FC
4.1.3
Steel sheets and strips are classified by surface structure as shown in Table 3.
Table 3 Surface structure classification
Surface structure Code
Pitted surface D
Smooth surface B
4.2 Steel grade representation methods
The grades of steel sheets and strips are composed of the initials “CR” of “Cold Rolled”, the specified minimum yield strength value and the characteristic letter “S” of “Solid Solution Strengthening”.
Example: CR205S
CR — the initials of “Cold Rolled”;
205 — the specified minimum value of minimum yield strength (MPa).
S — the characteristic letter of “Solid Solution Strengthening”.
5 Order contents
5.1
Contracts or orders made based on this part shall cover the following contents:
a) product name (steel sheet or strip);
b) number of this part;
c) steel grade;
d) specification, dimension and roughness accuracy;
e) surface quality grade;
f) surface structure;
g) edge state;
h) packing method;
i) weight;
j) use;
k) other special requirements.
5.2
If the information of dimensional and roughness accuracy, surface quality grade, surface structure type, edge state and packaging is not specified in the order contract, the products of this part will be supplied with ordinary dimensional and roughness accuracy, superior grade surface, pitted surface structure and cut edge state, and packaged in the packaging method provided by the supplier.
6 Dimension, shape and weight
The dimension, shape, weight and allowable tolerance of steel sheets and strips shall meet the requirements specified in GB/T 708.
7 Technical requirements
7.1 Chemical composition
Refer to Annex A for reference values for the chemical composition of steel (melting analysis). If the purchaser has any special requirements for chemical composition, it shall be negotiated when ordering. Refer to Annex C for the approximate comparison of steel grades specified in domestic and foreign standards.
7.2 Smelting process
The steel used for steel sheets and strips is smelted by oxygen converter; unless otherwise specified, the smelting method shall be chosen by the supplier.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Classification and steel grade representation methods
5 Order contents
6 Dimension, shape and weight
7 Technical requirements
8 Test methods
9 Inspection rules
10 Package, marking and quality certificate
Annex A (Informative) Chemical composition of steel
Annex B (Informative) Approximate comparisons of domestic and foreign steel grades
