Continuously cold rolled high strength steel sheet and strip for automobile –
Part 4: High strength low alloy steel
1 Scope
This document specifies the classification and designation expression, order content, dimension, shape, weight, technical requirements, test methods, inspection rules, packaging, marking and quality certificate of continuously cold rolled high strength low alloy steel sheet and strip for automobile.
This document is applicable to continuously cold rolled high strength low alloy steel sheet and strip with thickness of 3.0 mm or below, which are mainly used for making structural parts and stiffeners of automobile (hereinafter referred to as "sheet and strip").
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions 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 223.5 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 aluminum content - Chrome azurol S photometric method
GB/T 223.40 Iron, steel and alloy - Determination of niobium content by the sulphochlorophenol S spectrophotometric 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 223.63 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 228.1-2021 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/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 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 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 20126 Unalloyed steel - Determination of low carbon content - Part 2: Infrared absorption method after combustion in an induction furnace (with preheating)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
high strength low alloy steel; LA
low carbon steel with higher strength by refining grains of microalloying elements and adding such single or composite microalloying elements as niobium, titanium and vanadium to precipitate the carbohydrates and nitrogenous compounds particles
4 Designation expression and classification
4.1 Designation expression
The designation of steel sheet and strip consists of three parts: the initial capital letters of "Cold Rolled", i.e., "CR", the specified minimum yield strength and the initial capital letters of "Low Alloy", i.e., "LA".
For example: CR260LA, where:
CR——the initial capital letters of "Cold Rolled";
260——the specified minimum yield strength, in MPa;
LA——the initial capital letter of "Low Alloy".
4.2 Classification
4.2.1 The designation and recommended application of steel sheet and strip are shown in Table 1.
Foreword i
Introduction iii
1 Scope
2 Normative references
3 Terms and definitions
4 Designation expression and classification
5 Order contents
6 Dimension, shape and weight
7 Technical requirements
8 Test methods
9 Inspection rules
10 Packaging, marking and quality certificate
11 Comparison of designations in this part and those in foreign standards
Annex A (Informative) Reference values for chemical composition (melting analysis) of steels
Annex B (Normative) Mechanical properties of steel sheet and strip (the sample is in longitudinal direction)
Annex C (Informative) Comparison of designations in this document and those in foreign standards
Bibliography
