GB/T 20887.6-2017Continuously hot-rolled high strength steel sheet and strip for automobiles - Part 6: Complex phase steel (English PDF)

1 Scope

This Part of GB/T 20887 specifies the classification and designation representing method, ordering content, dimensions, shape, weight, technical requirements, test methods, inspection rules, package, mark, and quality certificate of hot rolled high strength complex phase steel sheet and strip.

This Part applies to the steel strip with a thickness of no more than 8 mm and steel plate cut transversely from steel strip and longitudinally-cut steel strip (hereafter known as "steel plate and strip" for short) for the production of automobile structural parts and reinforcements.

2 Normative references

The following documents are indispensable for the application of this document.

For the dated references, only the versions with the dates indicated are applicable to this document. For the undated references, the latest version (including all the amendments) are applicable 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 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 223.17 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 223.60 Methods for chemical analysis of iron, steel and alloy - The perchloric acid dehydration gravimetric method for the determination of silicon content

GB/T 223.68 Methods for chemical analysis of iron, steel and alloy - The potassium iodate titration method after combustion in the pipe furnace for the determination of sulfur content

GB/T 223.69 Iron, steel and alloy - Determination of carbon contents - Gas-volumetric method after combustion in the pipe furnace

GB/T 223.75 Iron, steel and alloy - Determination of boron content - Methanol distillation-curcumin photometric method

GB/T 223.76 Methods for chemical analysis iron, steel and alloy - The flame atomic absorption spectrometric method for the determination of vanadium content

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 709 Dimensions, Shape, Weight and Tolerances for Hot Rolled Steel Sheets and Strips

GB/T 2975 Steel and Steel Products - Location and Preparation of 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 6394 Metal - Methods for estimating the average grain size

GB/T 8170 Rules of rounding off for numerical values & expression and judgement of limiting values

GB/T 10561 Steel - Determination of Content of Nonmetallic Inclusions - Micrographic Method Using Standards Diagrams

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

(with Preheating)

GB/T 24524 Metallic materials - Sheet and strip - Hole expanding test

3 Terms and definitions

The following terms and definitions are applicable to this document.

4 Classification and designation representing method

6 Dimensions, shape, weight

The dimensions, shape, weight, and permissible tolerances of steel sheet and strip shall comply with the provisions of GB/T 709.

7 Technical requirements

9 Inspection rules

9.1 The inspection and acceptance of steel sheet and strip shall be performed by the supplier's inspection department.

9.2 The steel sheet and strip shall be accepted in batches. Each batch shall consist of steel sheets and strips of the same designation, the same furnace number, the same thickness, and the same rolling mechanism with a weight of no more than 60 t. For the steel strip and continuously rolled sheet with roll weight greater than 30 t, each two rolls shall be regarded as one batch.

9.3 The sampling quantity and sampling methods for steel sheet and strip shall conform to the provisions of Table 3.

9.4 The re-inspection and judgement rules of steel sheet and strip shall conform to the provisions of GB/T 17505.

9.5 The test results of chemical composition and mechanical properties shall be rounded off according to the rounding off value comparison method. The rounding off rules shall be in accordance with the provisions of GB/T 8170.

10 Package, mark, and quality certificate

The package, mark, and quality certificate of steel sheet and strip shall conform to the provisions of GB/T 247. If the demand side has a special requirement for the package, it can be negotiated when ordering. […]