Detail of GB/T 20564.12-2019

Introduction of GB/T 20564.12-2019

Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative. GB/T 20564 Continuously cold rolled high strength steel sheet and strip for automobile is divided into 12 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; — Part 12: Dual phase steel with high formability. This part is Part 12 of GB/T 20564. This part is prepared 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 National Technical Committee on Iron and Steel of Standardization Administration of China (SAC/TC 183). Continuously cold rolled high strength steel sheet and strip for automobile — Part 12: Dual phase steel with high formability 1 Scope This part 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 for cold rolled low carbon steel sheet and strip. This part is applicable to the manufacture of steel sheets and steel strips (hereinafter referred to as “steel sheets and steel strips”) with a thickness of 0.50 mm to 3.00 mm for complex automobile structural parts and reinforcements. 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 223.4 Iron, steel and alloy — Determination of chromium content — Visual titration or potentiometric titration method GB/T 223.9 Iron, steel and alloy — Determination of aluminum content — Chrome azurol S photometric method GB/T 223.11 Iron steel and alloy — Determination of chromium content — Visual titration or potentiometric titration 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 223.17 Methods for chemical analysis of iron steel and alloy. The diantipyrylmethane photometric method for the determination of titanium content 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 223.58 Methods for chemical analysis of iron, steel and alloy. The sodium arsenite-sodium nitrite titrimetric method for the determination of manganese content 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 223.223.60 Methods for chemical analysis of iron, steel and alloy — The perchloric acid dehydration gravimetric method for the determination of silicon content GB/T 223.67 Iron, Steel and Alloy — Determination of Sulfur Content — Methylene Blue Spectrophotometric Method GB/T 223.69 Iron, steel and alloy — Determination of carbon contents — Gas-volumetric method after combustion in the pipe furnace GB/T 223.72 Iron, Steel and Alloy — Determination of Sulfur Content - Gravimetric Method GB/T 223.78 Methods for chemical analysis of iron, steel and alloy — Curcumin spectrophotometric method for the determination of boron content GB/ T223.86 Steel and iron — Determination of total carbon content — Infrared absorption method after combustion in an induction 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/ T2975 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 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) GB/T 24174 Iron — Determination method for the bake hardening value (BH2) 3 Terms and definitions For the purposes of this standard, the following terms and definitions apply. 3.1 dual phase steel with high formability; DH steel whose microstructure is mainly ferrite, martensite and a small amount of retained austenite or bainite. Note: Compared with dual-phase steel with the same tensile strength, it has higher percentage elongation after fracture and strain hardening exponent. It is suitable for forming parts with higher drawing requirements. 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 surface quality. Table 1 Surface quality classification Grade Code Superior grade surface FB High grade surface FC 4.1.2 Refer to Table 2 for the classification of steel sheets and strips by surface structure. Table 2 Surface structure classification Surface structure Code Pitted surface D Smooth surface B 4.2 Steel grade representation methods The steel grade of steel sheet and strip consists of Cold Rolled initials CR, the specified minimum yield strength value/minimum tensile strength value, and the characteristic letter of Dual phase steel with high formability DH. Example: CR440/780DH: CR — the Cold Rolled initials; 440/780 — the specified minimum yield strength value is 440, the specified minimum tensile strength is 780 in megapascals (MPa). DH — the characteristic letter of Dual phase steel with high formability.

Contents of GB/T 20564.12-2019

1 Scope 2 Normative References 3 Terms and definitions 4 Classification and steel grade representation methods 4.1 Classification 4.2 Steel grade representation methods 5 Order content 6 Dimension, shape and weight 7 Technical requirements 7.1 Chemical composition 7.2 Smelting method 7.3 Delivery state 7.4 Mechanical properties 7.5 Welding 7.6 Surface quality 7.7 Surface structure 8 Test methods 9 Inspection rules 10 Packaging, marking and quality certificate Annex A (Informative) Chemical composition of steel Annex B (Informative) Approximate comparisons of domestic and foreign steel grades