Detail of GB/T 20887.2-2022

Introduction of GB/T 20887.2-2022

GB/T 20887.2-2022Continuously 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 expression, order information, dimension, shape, weight, technical requirements, test methods, inspection rules, packaging, marking, and quality certificate of continuously hot rolled high strength high expansion steel sheet and strip for automobile. This document is applicable to the continuously hot rolled steel strip with thickness not greater than 6.0 mm and with high hole expansion performance, as well as the steel sheet and the silt wide strip respectively formed by cutting such steel strip horizontally and vertically (hereinafter referred to as “steel sheet and strip”). 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 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 GB/T 223.54 Iron, steel and alloy—Determination of nickel content—Flame atomic absorption spectrometric 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 223.60 Methods for chemical analysis of iron, steel and alloy—The perchloric acid dehydration gravimetric method for the determination of silicon 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 alloy—Determination of manganese content—Flame atomic absorption spectrometric method GB/T 223.76 Methods for chemical analysis of iron, steel and alloy—The flame atomic absorption spectrometric method for the determination of vanadium content GB/T 223.78 Methods for chemical analysis of iron, steel and alloy—Curcumin spectrophotometric method for the determination of boron content GB/T 223.84 Steel and alloy—Determination of titanium content—Diantipyrylmethane spectrophotometric 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 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 709 Dimension, shape, weight and tolerance for hot-rolled steel strip, plate and sheet 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 5028 Metallic materials—Sheet and strip—Determination of tensile strain hardening exponent (n-values) GB/T 6394 Determination of estimating the average grain size of metal GB/T 8170 Rules of rounding off for numerical values & expression and judgment 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 For the purposes of this standard, the following terms and definitions apply. 3.1 high hole expansion steel; HE steel with its microstructure mainly composed of “ferrite+bainite” or ferrite (or reinforced ferrite) or bainite (or reinforced bainite). Note: The high hole expansion steel is provided with relatively high tensile strength, high formability and good flanging formability, and is sometimes called ferrite-bainite steel (FB) or high-flanged high strength steel (SF) 4 Classification and designation expression 4.1 Classification 4.1.1 The steel sheet and strip shall be classified by surface condition into:

Contents of GB/T 20887.2-2022

Foreword i Introduction iii 1 Scope 2 Normative references 3 Terms and definitions 4 Classification and designation expression 5 Order information 6 Dimension, shape and weight 7 Technical requirements 8 Test methods 9 Inspection rules 10 Packaging, marking and quality certificate Annex A (Informative) Comparison of similar designations of standards both in China and abroad Bibliography