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GB/T 20564.7-2022 English PDF (GBT20564.7-2022)

GB/T 20564.7-2022 English PDF (GBT20564.7-2022)

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GB/T 20564.7-2022: Continuously cold rolled high strength steel sheet and strip for automobile -- Part 7: Martensitic steel

This document specifies the classification and designation representation method, order content, dimension, shape, weight, technical requirements, test methods, inspection rules, package, mark and certification of continuously cold rolled high strength martensitic steel sheet and strip.
GB/T 20564.7-2022
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 77.140.50
CCS H 46
Replacing GB/T 20564.7-2010
Continuously cold rolled high strength steel sheet and strip
for automobile - Part 7: Martensitic steel
ISSUED ON: APRIL 15, 2022
IMPLEMENTED ON: NOVEMBER 01, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3
Introduction ... 5
1 Scope ... 7
2 Normative references ... 7
3 Terms and definitions ... 9
4 Classification and designation representation method ... 9
5 Order content ... 10
6 Dimension, shape, weight ... 11
7 Technical requirements ... 11
8 Test methods ... 13
9 Inspection rules ... 14
10 Package, mark and certification ... 14
Appendix A (Informative) Chemical composition of steel sheets and strips ... 15 Appendix B (Informative) Comparison of similar designations at home and abroad 16 Bibliography ... 17
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 method, order content, dimension, shape, weight, technical requirements, test methods, inspection rules, package, mark and certification of continuously cold rolled high strength martensitic steel sheet and strip.
This document applies to the continuously cold rolled high strength martensitic steel sheet and strip (hereinafter referred to as "steel sheet and strip") with a thickness of 0.50 mm~2.1 mm, which are mainly used for manufacturing automobile structures, reinforcements, and anti-collision parts.
2 Normative references
The contents of the following documents, through normative references in this text, constitute indispensable provisions of this document. Among them, for dated references, only the edition corresponding to that date applies to this document. For undated references, the latest edition (including all amendments) applies to this document. 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 - Chrome 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
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 in an induction furnace (With preheating) 3 Terms and definitions
The following term and definition applies to this document.
3.1
Martensitic steel; MS
A steel whose microstructure is almost entirely martensitic structure and may contain a small amount of ferrite and/or bainite.
Note: Martensitic steel has high strength and certain formability.
4 Classification and designation representation method
4.1 Designation representation method
The designation of the steel sheet and strip consists of three parts: The initials "CR" of the English "Cold Rolled"; the numerical value of the specified minimum yield strength/the numerical value of the specified minimum tensile strength; the initials "MS" of the English "Martensitic Steel".
Example: CR1200/1500MS, where:
CR - The initials of the English "Cold Rolled";
1200/1500 - 1200 is the specified minimum yield strength value; 1500 is the specified minimum tensile strength value; in megapascals (MPa);
MS - The initials of the English "Martensitic Steel".
4.2 Classification
4.2.1 See Table 1 for the designations and recommended uses of steel sheets and strips. h) Package method;
i) Weight;
j) Purpose;
k) Other special requirements.
5.2 If the information, such as dimension and roughness accuracy, surface quality level, surface structure type, edge state and package, is not specified in the order contract; for the products in this document, it shall supply trimmed-edge steel sheets or strips with ordinary dimension and roughness accuracy, higher finishing surfaces, and pitted surface structure. And it shall be packaged according to the package method provided by the supplier.
6 Dimension, shape, weight
The dimension, shape, weight and tolerance of steel sheets and strips shall comply with the provisions of GB/T 708.
7 Technical requirements
7.1 Chemical composition
Refer to Appendix A for reference values of the chemical composition (heat analysis) of steel. If the purchaser has requirements on the chemical composition, it shall be negotiated when ordering. See Appendix B for the comparison of similar designations at home and abroad.
7.2 Smelting method
The steel used for steel sheets and strips shall be smelted by oxygen converter or electric furnace. Unless otherwise specified, the smelting method shall be selected by the supplier.
7.3 Delivery state
7.3.1 Steel sheets and strips are delivered in a flat state after annealing. 7.3.2 Steel sheets and strips are usually supplied oiled. The oil film applied shall be able to be removed with an alkaline aqueous solution or a common solvent. Under the usual package, transportation, handling, and storage conditions, the supplier guarantees that, within 6 months from the date of completion of manufacture, the surface of steel sheet and strip will not rust. If the purchaser requires supply without oiling, it shall negotiate when ordering.
9 Inspection rules
9.1 The inspection and acceptance of steel sheets and strips shall be carried out by the inspection department of the supplier.
9.2 Steel sheets and strips shall be inspected in lots. Each inspection lot shall be composed of steel sheets or strips of the same designation, specification, and processing state. The weight of each lot shall be no more than 30 t. For the steel strip with a coil weight greater than 30 t, each coil is regarded as one inspection lot.
9.3 The sampling quantity and sampling methods of steel sheets and strips shall comply with the provisions of Table 7.
9.4 The re-inspection and determination rules for steel sheets and strips shall comply with the provisions of GB/T 17505.
9.5 The test results of chemical composition and mechanical properties are rounded according to the rounding value comparison method. The rules of rounding off shall be in accordance with the provisions of GB/T 8170.
10 Package, mark and certification
The package, mark and certification of steel sheets and strips shall comply with the provisions of GB/T 247. The type of certification (inspection document) shall comply with the provisions in GB/T 18253-2018. When the inspection document type is not specified, it shall be in accordance with Type 3.1 of GB/T 18253-2018. If the purchaser has special requirements for package, it can be negotiated when ordering.

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