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This document is drafted in accordance with the rules given in GB/T 1.1-2020 Directives for Standardization — Part 1: Rules for the Structure and Drafting of Standardizing Documents.
This document is Part 7 of GB/T 20564 Continuously Cold Rolled High Strength Steel Sheet and Strip for Automobile. GB/T 20564 consists of the following 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 Steel;
— Part 8: Complex Phase Steel;
— Part 9: Quenching and Partitioning Steel;
— Part 10: Twinning Induced Plasticity Steel;
— Part 11: Carbon Manganese Steel;
— Part 12: Dual Phase Steel with High Formability.
This document replaces GB/T 20564.7-2010 Continuously Cold Rolled High Strength Steel Sheet and Strip for Automobile — Part 7: Martensitic Steel. In addition to structural adjustments and editorial changes, the following technical deviations have been made with respect to GB/T 20564.7-2010:
— the terminology of martensitic steel is modified (see 3.1 hereof; 3.1 of Edition 2010);
— the designation of CR1350/1700MS and its technical indicators of properties are added, and the designation of CR500/780MS is deleted (see Table 1 hereof; Table 1 of Edition 2010);
— the upper limit of yield strength of CR700/900MS is modified (see Table 4 hereof; Table 4 of Edition 2010);
— the index for elongation after fracture is modified (see Table 4 hereof; Table 4 of Edition 2010);
— the requirements for the inspection document type are added (see Clause 10).
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.
This document was proposed by China Iron and Steel Association.
This document is under the jurisdiction of the National Technical Committee on Iron and Steel of Standardization Administration of China (SAC/TC 183).
This document was issued in 2010 as first edition. This is the fourth revised edition.
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Introduction
GB/T 20564 Continuously Cold Rolled High Strength Steel Sheet and Strip for Automobile is one of the standards of steel sheet and strip for automobile developed by Subcommittee on Steel Sheet and Strip of National Technical Committee on Iron and Steel of Standardization Administration of China (hereinafter referred to as "Committee"). GB/T 20564 is developed to standardize the classification and designation representation method, order information, dimensions, shape, weight, specifications, test methods, inspection rules, packaging, marking and quality certificate of continuously cold rolled high strength steel sheet and strip for automobile.
GB/T 20564 consists of the following twelve parts.
— Part 1: Bake Hardening Steel. This part is applicable to the determination of specifications of continuously cold rolled, bake hardening high strength steel sheet and strip with thickness of 0.50 mm to 3.00 mm and mainly used to manufacture outer plate, inner plate and partial of the structural parts of automobile.
— Part 2: Dual Phase Steel. This part is applicable to the determination of specifications of continuously cold rolled high strength dual phase steel sheet and strip with thickness of 0.50 mm to 3.00 mm and mainly used to manufacture structural parts, reinforcement parts and partial of the inner and outer plates of automobile.
— Part 3: High Strength Interstitial Free Steel. This part is applicable to the determination of specifications of continuously cold rolled high strength interstitial free steel sheet and strip with thickness of 0.50 mm to 3.00 mm and mainly used to manufacture outer plate, inner plate and partial of the structural parts of automobile.
— Part 4: High Strength Low Alloy Steel. This part is applicable to the determination of specifications of continuously cold rolled high strength low alloy steel sheet and strip with thickness not more than 3.00 mm and mainly used to manufacture structural parts and reinforcement parts of automobile.
— Part 5: Isotropic Steel. This part is applicable to the determination of specifications of continuously cold rolled high strength isotropic steel sheet and strip with thickness not more than 2.5 mm and mainly used to manufacture outer covering parts of automobile.
— Part 6: Transformation Induced Plasticity Steel. This part is applicable to the determination of specifications of continuously cold rolled high strength transformation induced plasticity steel sheet and strip with thickness of 0.50 mm to 2.5 mm and mainly used to manufacture structural parts and reinforcement parts of automobile.
— Part 7: Martensitic Steel. This part is applicable to the determination of specifications of continuously cold rolled high strength martensitic steel sheet and strip with thickness of 0.50 mm to 2.1 mm and mainly used to manufacture structural parts, reinforcement parts and anti-collision parts of automobile.
— Part 8: Complex Phase Steel. This part is applicable to the determination of specifications of continuously cold rolled high strength complex phase steel sheet and strip with thickness of 0.50 mm to 2.5 mm and mainly used to manufacture structural parts, reinforcement parts and partial of the inner and outer plates of automobile.
— Part 9: Quenching and Partitioning Steel. This part is applicable to the determination of specifications of continuously cold rolled, quenching and partitioning high strength steel sheet and strip with thickness of 0.50 mm to 2.5 mm and mainly used to manufacture structural parts and reinforcement parts of automobile.
— Part 10: Twinning Induced Plasticity Steel. This part is applicable to the determination of specifications of continuously cold rolled high strength twinning induced plasticity steel sheet and strip with thickness of 0.50 mm to 3.00 mm and mainly used to manufacture complex shape structural parts and reinforcement parts of automobile.
— Part 11: Carbon Manganese Steel. This part is applicable to the determination of specifications of continuously cold rolled high strength carbon manganese steel sheet and strip with thickness of 0.50 mm to 3.00 mm and mainly used to manufacture structural parts of automobile.
— Part 12: Dual Phase Steel with High Formability. This part is applicable to the determination of specifications of continuously cold rolled high strength dual phase steel sheet and strip with high formability, with thickness of 0.50 mm to 3.00 mm and mainly used to manufacture structural parts and reinforcement parts of automobile.
The Committee shall not be held responsible for any comprehension ambiguities and the resulting consequences caused by the publicizing or interpretation of this standard by other organizations without written entitlement or approval of the Committee.
Continuously Cold Rolled High Strength Steel Sheet and Strip for Automobile — Part 7: Martensitic Steel
1 Scope
This document specifies the classification and designation representation methods, order information, dimensions, shape, weight, specifications, test methods, inspection rules, packaging, marking and quality certificate of continuously cold rolled high strength martensitic steel sheet and strip for automobile.
This part is applicable to the continuously cold rolled high strength martensitic steel sheet and strip (hereinafter referred to as "steel sheet and strip") with thickness of 0.50 mm to 2.1 mm and mainly used to manufacture structural parts, reinforcement parts and anti-collision parts of automobile.
2 Normative References
The following referenced documents are indispensable for the application 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 223.5 Steel and Iron — Determination of Acid-soluble Silicon and Total Silicon Content — Reduced Molybdosilicate Spectrophotometric Method
GB/T 223.9 Iron, Steel and Alloy — Determination of Aluminium Content — Chrom Azurol S Photometric Method
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 223.23 Iron, Steel and Alloy — Determination of Nickel Content — The Dimethylglyoxime Spectrophotometric Method
GB/T 223.26 Iron, Steel and Alloy — Determination of Molybdenum Content — The Thiocyanate 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 223.63 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 223.85 Steel and Iron — Determination of Sulfur Content — Infrared Absorption Method after Combustion in an Induction Furnace
GB/T 223.86 Steel and Iron — Determination of Total Carbon Content — Infrared Absorption Method after Combustion in an Induction Furnace
GB/T 228.1-2021 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 Plates and Sheets
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 Judgment of Limiting Values
GB/T 17505 Steel and Steel Products — General Technical Delivery Requirements
GB/T 18253-2018 Steel and Steel Products — Types of Inspection Documents
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 purpose of this document, the following terms and definitions apply.
3.1
martensitic steel (MS)
steel with the microstructure almost entirely composed martensite, and a small amount of ferrite and/or bainite
Note: Martensitic steel has high strength and certain formability.
4 Classification and Designation Representation Methods
4.1 Designation representation methods
The designation of steel sheet and strip consists of three parts: the initial capital letters of “Cold Rolled”, i.e., “CR”, the specified value of minimum yield strength/minimum tensile strength, and the initial capital letters of “Martensitic Steel”, i.e., “MS”.
Example: CR1200/1500MS, where:
CR — the initial capital letters of “Cold Rolled”;
1200/1500 — 1200: the specified value of minimum yield strength; 1500: the specified value of minimum tensile strength, in Megapascals (MPa);
MS — the initial capital letters of "Martensitic Steel".
4.2 Classification
4.2.1 See Table 1 for the designations and recommended uses of steel sheets and strips
Table 1 Designations and recommended uses
Designation Recommended uses
CR700/900MS
Structural parts, reinforcement parts and anti-collision parts
CR700/980MS
CR860/1100MS
CR950/1180MS
CR1030/1300MS
CR1150/1400MS
CR1200/1500MS
CR1350/1700MS
4.2.2 See Table 2 for steel sheets and strips classified according to the surface quality.
Table 2 Classification of surface quality
Grade Code
Fairly high surface FB
Higher grade surface FC
4.2.3 See Table 3 for steel sheets and strips classified according to the surface structure.
Table 3 Classification of surface structure
Surface structure Code
Pitted surface D
Shiny surface B
5 Order Information
5.1 Contracts or orders made based on this document shall include the following information:
a) product name (steel sheet or strip);
b) No. of this document;
c) designation;
d) specification, dimension and unevenness precision;
e) surface quality grade;
f) surface structure;
g) edge condition;
h) packaging method;
i) weight;
j) uses;
k) other special requirements.
5.2 If information, e.g. dimension and roughness precision, surface quality class, surface structure type, edge condition and packaging, is not specified in the order contract, the products in this document shall be supplied as trimmed steel sheets/strips in common size and roughness precision, fairly high class finishing surface and pitted surface structure, and shall be packed in the manner given by the supplier .
Foreword II
Introduction IV
1 Scope
2 Normative References
3 Terms and Definitions
4 Classification and Designation Representation Methods
5 Order Information
6 Dimensions, Shape and Weight
7 Specifications
8 Test Methods
9 Inspection Rules
10 Packaging, Marking and Quality Certificate
Annex A (Informative) Chemical Composition of Steel Sheets and Strips
Annex B (Informative) Comparison of Designations in This Document and Those in Foreign Standards
Bibliography
