GB/T 20887.7-2017Continuously hot-rolled high strength steel sheet and strip for automobiles - Part 7: Steels for hydraulic forming (English PDF)

Foreword

GB/T 20887, Continuously hot rolled high strength steel sheet and strip for automobile, comprises 7 parts.

-- Part 1. High yield strength steel for cold forming;

-- Part 2. High hole expansion steel;

-- Part 3. Dual phase steel;

-- Part 4. Transformation induced plasticity steel;

-- Part 5. Martensitic steel;

-- Part 6. Complex phase steel;

-- Part 7. Steels for hydraulic forming.

This Part is Part 7 of GB/T 20887.

This Part was drafted in accordance with the rules given in GB/T 1.1-2009.

1 Scope

This Part of GB/T 20887 specifies the terms and definitions, classification and designation, ordering content, dimensions, shapes, weights, technical requirements, test methods, inspection rules, packaging, marking and quality certification of continuously hot rolled high strength steel sheet and strip.

This Part applies to steel strip of thickness not greater than 6 mm, and steel sheet transversely cut or steel strip longitudinally cut from steel strip, which are used for the structural parts of automobile such as auxiliary frames and dashboard supports (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 dated applies to this document. For undated references, the latest edition of the referenced documents (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 - Chrom azurol S photometric method

GB/T 223.16, Methods for chemical analysis of iron, steel and alloy - The chromotropic acid photometric method for the determination of titaninm content

GB/T 223.40, Iron, steel and alloy - Determination of niobium content by the sulphochlorophenol S spectrophotometric method

GB/T 223.62, Methods for chemical analysis of iron, steel and alloy - The butyl acetate extraction photometric method for the determination of phosphorus 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 223.79, Iron and steel - Determination of multi-element contents - X-ray fluorescence spectrometry(Routine 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 tolerances for hot rolled sheets and strips

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

GB/T 8170, Rules of rounding off for numerical values and 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

4 Classification and designation

HF - initials of "Hydraulic Forming" in English.

5 Ordering content

5.1 The contract or order based on this Part shall include the following content.

a) product name (steel sheet or strip);

b) a reference to this Part;

c) designation;

d) specifications, dimensions and roughness accuracy;

e) surface quality level;

f) surface condition (when it is an acid pickled surface, it is represented by "P");

g) edge condition;

h) oil coated or not;

i) control method when used for control (such as electric resistance welding ERW and laser welding LBW);

j) weight;

k) other special requirements.

5.2 If it is not stated in the purchase contract, including thickness accuracy, surface quality level, edge condition and whether oil is coated or not, then the products of this Part are supplied in accordance with the normal thickness accuracy, common level surface (FA), trimmed condition and oil coated condition.

6 Dimensions, shapes and weights

The dimensions, shapes and weights and tolerances for steel sheet and strip shall be as specified in GB/T 709.

7 Technical requirements