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GB/T 20887.2-2022 English PDF (GBT20887.2-2022)

GB/T 20887.2-2022 English PDF (GBT20887.2-2022)

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GB/T 20887.2-2022: Continuously hot rolled high strength steel sheet and strip for automobile -- Part 2: High hole expansion steel
This document specifies the terms and definitions, classification and designation representation method, order content, dimension, shape, weight, technical requirements, test methods, inspection rules, package, mark and certification of continuously hot rolled high-strength high hole expansion steel sheet and strip for automobile. This document applies to continuously hot rolled steel strips with high hole expansion property with a thickness of not more than 6.0 mm, steel sheets cross-cut from them, and longitudinally-cut steel strips.
GB/T 20887.2-2022
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.50
CCS H 46
Replacing GB/T 20887.2-2010
Continuously hot rolled high strength steel sheet and strip
for automobile - Part 2: High hole expansion 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 ... 10
5 Order content ... 10
6 Dimension, shape, weight ... 11
7 Technical requirements ... 11
8 Test methods ... 14
9 Inspection rules ... 15
10 Package, mark and certification ... 15
Appendix A (Informative) Comparison of similar designations at home and abroad . 16 Bibliography ... 17
Continuously hot rolled high strength steel sheet and strip
for automobile - Part 2: High hole expansion steel
1 Scope
This document specifies the terms and definitions, classification and designation representation method, order content, dimension, shape, weight, technical requirements, test methods, inspection rules, package, mark and certification of continuously hot rolled high-strength high hole expansion steel sheet and strip for automobile. This document applies to continuously hot rolled steel strips with high hole expansion property with a thickness of not more than 6.0 mm, steel sheets cross-cut from them, and longitudinally-cut steel strips (hereinafter referred to as "steel sheets and strips"). 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 222 Permissible Tolerances for Chemical Composition of Steel Products 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 223.40 Iron, Steel and Alloy - Determination of Niobium Content by the Sulphochlorophenol S Spectrophotometric Method
- Spark Discharge Atomic Emission Spectrometric Method (Routine Method) GB/T 5028 Metallic materials - Sheet and strip - Determination of tensile strain hardening exponent
GB/T 6394 Metal - Methods for Estimating the Average Grain Size
GB/T 8170 Rules of Rounding off for Numerical Values and Expression and Judgement of Limiting Values
GB/T 10561 Steel - Determination of Content of Nonmetallic Inclusions - Micrographic Method Using Standards Diagrams
GB/T 13298 Inspection methods of microstructure for metals
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 24524 Metallic materials - Sheet and strip - Hole expanding test
GB/T 38813 General requirements for hot-rolled pickled steel sheet and strip 3 Terms and definitions
The following term and definition applies to this document.
3.1
High hole expansion steel; HE
A steel whose microstructure is mainly "ferrite + bainite" or ferrite (or strengthened ferrite) or bainite (or strengthened bainite), etc.
Note: High hole expansion steel has high tensile strength, high formability, and good flange flanging formability. High hole expansion steel is also sometimes referred to as ferritic-bainitic steel (FB) or high flange flanging high-strength steel (SF).
4 Classification and designation representation method
4.1 Classification
4.1.1 According to the surface state, steel sheets and strips are classified into: a) Hot rolled surface;
b) Hot rolled pickled surface. When the surface state is hot rolled pickled surface, it is represented by the code "P".
4.1.2 According to the surface quality, steel sheets and strips are classified into: a) Ordinary surface (FA);
b) Relatively-advanced surface (FB).
4.2 Designation representation method
The designation of the steel sheets and strips is composed of three parts: The initials "HR" of the English "Hot Rolled"; the specified minimum yield strength value/the specified minimum tensile strength value; the initials "HE" of the English "Hole Expansion".
Example: HR440/580HE
HR - The initials of the English "Hot Rolled";
440/580 - 440 is the specified minimum yield strength value; 580 is the specified minimum tensile strength value; in megapascals (MPa);
HE - The initials of the English "Hole Expansion".
5 Order content
5.1 Contracts or orders placed according to this document shall include the following: a) Product name (steel sheet or strip);
b) Number of this document;
c) Designation;
d) Specification and dimension, roughness accuracy;
e) Surface state (Pickled surface is represented by the code "P");
9 Inspection rules
9.1 The inspection and acceptance of steel sheets and strips shall be carried out by the quality inspection department of the supplier.
9.2 Steel sheets and strips shall be accepted in lots. Each lot shall consist of steel sheets or strips of the same designation, heat number, thickness and rolling system with a weight not greater than 60 t. Steel strips and continuously rolled steel sheets with a rolled coil weight greater than 30 t can be batched into two rolled coils. 9.3 The sampling quantity and sampling methods of steel sheets and strips shall comply with the provisions of Table 4.
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.
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