GB/T Translated English of Chinese Standard: GB/T NATIONAL STANDARD OF THE

Transcription

1 Translated English of Chinese Standard: GB/T GB NATIONAL STANDARD OF THE PEOPLE S REPUBLIC OF CHINA ICS H 46 GB/T Replacing GB/T Steel plate for building structure 建筑结构用钢板 Issued on: December 10, 2015 Implemented on: November 1, 2016 Issued by: General Administration of Quality Supervision, Inspection and Quarantine of the People s Republic of China; Standardization Administration of the People s Republic of China. Page 1 of 17

2 Table of Contents Foreword Scope Normative references Grade representation Order contents Dimension, shape, weight and tolerance Technical requirements Test methods Inspection rules Packaging, symbols and quality certificate Rounding off for numerical values Page 2 of 17

3 Foreword This Standard was drafted in accordance with the rules given in GB/T This Standard replaces GB/T Steel plate for building structure. Compared with GB/T , the major technical changes are as follows: ADD the grades for the steel of high strength, namely Q500GJ, Q550GJ, Q620GJ and Q690GJ, and corresponding technical requirements. ADD Level B to the quality levels Q390GJ, Q420GJ and Q460GJ. EXPAND the maximum thickness of Q345GJ steel plates from 100mm to 200mm. EXPAND the maximum thickness of Q235GJ, Q390GJ, Q420GJ and Q460GJ steel plates from 100mm to 150mm. S content of Levels D and E steel is tightened from S 0.015% to S 0.010%. STIPULATE the carbon equivalent (CEV) and welding crack susceptibility index (Pcm) values of Q460GJ. Clearly EXPRESS the yield strength as lower yield strength Rel. DECREASE the thickness effect for the yield strength of the steel plates with the thicknesses of not greater than 100mm from 20MPa to 10MPa. Respectively ADJUST the yield ratios of Q345GJ, Q390GJ, Q420GJ and Q460GJ from not greater than 0.83, 0.85, 0.85 and 0.85 to not greater than 0.80, 0.83, 0.83 and REDUCE the yield strength range of Q235GJ and Q345GJ from 120MPa to 110MPa. INCREASE the percentage elongation after fracture of Q420GJ from not less than 19% to not less than 20%. INCREASE the percentage elongation after fracture of Q460GJ from not less than 17% to not less than 18%. INCREASE the minimum impact energy absorption value of Q235GJ, Q345GJ, Q390GJ, Q420GJ and Q460GJ from 34J to 47J. This Standard was proposed by China Iron and Steel Association. This Standard shall be under the jurisdiction of the National Technical Committee for Standardization of Steels (SAC/TC 183). Page 3 of 17

4 Steel plate for building structure 1 Scope This Standard specifies the grade representation, order contents, dimension, shape, weight, tolerance, technical requirements, test methods, inspection rules, packaging, symbols and quality certificate of the steel plates for building structure. This Standard is applicable to the Q345GJ hot-rolled steel plates within the thickness range of 6mm to 200mm, Q235GJ, Q390GJ, Q420GJ and Q460GJ hot-rolled steel plates within the thickness range of 6mm to 150mm, Q500GJ, Q550GJ, Q620GJ and Q690GJ hot-rolled steel plates within the thickness range of 12mm to 40mm for manufacturing high-rise building structure, longspan structure and other important building structures (hereinafter referred to as steel plates ). Hot-rolled steel plates can also make reference to this Standard. 2 Normative references The following documents are essential to the application of this document. For dated references, only the editions with the dates indicated are applicable to this document. For undated references, only the latest editions (including all the amendments) are applicable to this document. GB/T 222 Permissible tolerances for chemical composition of steel products GB/T Steel and iron - Determination of acid-soluble silicon and total silicon content - Reduced molybdosilicate spectrophotometric method GB/T Iron, steel and alloy - Determination of aluminium content - Chrom azurol S photometric method GB/T Iron, steel and alloy - Determination of chromium content - Visual titration or potentiometric titration method GB/T Methods for chemical analysis of iron, steel and alloy - The N- benzoyl-n-phenylhydroxylamine extraction photometric method for the determination of vanadium content Page 5 of 17

5 GB/T Methods for chemical analysis of iron, steel and alloy - The neocuproine-chloroform extraction photometric method for the determination of copper content GB/T Iron, steel and alloy - Determination of nickel content - The dimethylglyoxime spectrophotometric method GB/T Iron, steel and alloy - Determination of molybdenum content - The thiocyanate spectrophotometric method GB/T Iron, steel and alloy - Determination of niobium content by the sulphochlorophenol S spectrophotometric method GB/T Methods for chemical analysis of iron, steel and alloy - The sodium arsenite-sodium nitrite titrimetric method for the determination of manganese content GB/T Methods for chemical analysis of iron, steel and alloy - The butyl acetate extraction photometric method for the determination of phosphorus content GB/T Methods for chemical analysis of iron, steel and alloy - Curcumin spectrophotometric method for the determination of boron content GB/T Iron and steel - Determination of multi-element contents - X-ray fluorescence spectrometry (routine method) GB/T Iron, steel and alloy - Determination of total aluminum and total boron contents - Microwave digestion-inductively coupled plasma mass spectrometric method GB/T Iron, steel and alloy - Determination of titanium content - Diantipyrylmethane spectrophotometric method GB/T Iron, steel and alloy - Determination of sulfur content - Infrared absorption method after combustion in an induction furnace GB/T Iron, steel and alloy - Determination of total carbon content - Infrared absorption method after combustion in an induction furnace GB/T Metallic materials - Tensile testing - Part 1: Method of test at room temperature GB/T 229 Metallic materials - Charpy pendulum impact test method GB/T 232 Metallic materials - Bend test Page 6 of 17

6 GB/T 247 General rule of package, mark and certification for steel plates (sheets) and strips GB/T Dimension, shape, weight and tolerances for hot-rolled plates and sheets GB/T 2970 Thicker steel plates - Method for ultrasonic inspection GB/T 2975 Steel and steel products - Location and preparation of test pieces for mechanical testing GB/T 4336 Standard test method for spark discharge atomic emission spectrometric analysis of carbon and low-alloy steel (routine method) GB/T 5313 Steel plates with through-thickness characteristics GB/T 8170 Rules of rounding off for numerical values & expression and judgement of limiting values GB/T General requirement for surface condition of hot-rolled steel plates GB/T Steel and steel products - General technical delivery requirements GB/T Steel and iron - Sampling and preparation of samples for the determination of chemical composition GB/T Steel and iron - Determination of total carbon and sulfur content - Infrared absorption method after combustion in an induction furnace (routine method) GB/T Low-alloy steel - Determination of multi-element contents - Inductively coupled plasma atomic emission spectrometric method 3 Grade representation The steel grades shall be composed of the Chinese phonetic alphabet (Q) representing the yield strength, numerical value of specified minimum yield strength, Chinese phonetic alphabet (GJ) representing the steel for highperformance building structure, symbols for quality levels (B, C, D, E), for instance, Q345GJC. For the steel plates with through-thickness characteristics, ADD the levels of through-thickness characteristics (Z15, Z25 or Z35) after the quality levels, for instance, Q345GJCZ25. Page 7 of 17

7 6.1.3 The carbon equivalent (CEV) or welding crack susceptibility index (Pcm) of all quality levels of steels with various grades shall conform to the relevant provisions of Table 3. In general, the steel plates shall be delivered in carbon equivalent (CEV). After agreed upon by the supplier and demander and making indications in the contract, the carbon equivalent (CEV) of steels can be replaced by the welding crack susceptibility index. The carbon equivalent or welding crack susceptibility index of steels shall use smelting analysis values, and shall be calculated according to Equations (1) and (2). In addition, the chemical compositions used for calculating the carbon equivalent or welding crack susceptibility index shall be indicated in the quality certificate The tolerances for the chemical compositions of finished steel plates shall conform to the provisions of GB/T 222. If the supplier can guarantee, it is allowed not to make analysis. Page 9 of 17

8 6.4 Mechanical properties and process performance The tensile, Charpy V-notch impact and bend test results of Q235GJ, Q345GJ, Q390GJ, Q420GJ and Q460GJ steel plates shall conform to the provisions of Table 4. The tensile, Charpy V-notch impact and bend test results of Q500GJ, Q550GJ, Q620GJ and Q690GJ steel plates shall conform to the provisions of Table 5. When the supplier can guarantee that the bend test is qualified, it is allowed not to conduct the bend test When there are requirements for the through-thickness characteristics of the steel plates with the thicknesses of not less than 15mm, the rates of reduction in area for the levels of through-thickness characteristics shall conform to the corresponding provisions of Table 6. Page 12 of 17

9 Level of through-thickness characteristics Table 6 Mean value of three samples Rate of reduction in area Z / % Individual sample value Z Z Z Charpy (v-notch) impact test results of the steel plates shall be calculated according to the arithmetic mean value of a group of three test pieces. One of the test piece values is allowed to be less than the specified value, but shall not be less than 70% of the specified value. When the test results do not conform to the above-mentioned provisions, three more test pieces shall be taken from the same piece of steel plate (or the same sample billet) for testing. The arithmetic mean value of six test pieces in the former and latter groups shall not be less than the specified value. Two test pieces are allowed to be less than the specified value. However, only one of them is allowed to be less than 70% of the specified value For the steel plates with the thicknesses of less than 12mm, Charpy (vnotch) impact test shall use the test pieces with small dimensions. For the steel plates with the thicknesses of greater than 8mm and less than 12mm, the test piece dimensions shall be 7.5mm 10mm 55mm. The test results shall not be less than 75% of the specified value. For the steel plates with the thicknesses of 6mm to 8mm, the test piece dimensions shall be 5mm 10mm 55mm. The test results shall not be less than 50% of the specified value. 6.5 Surface quality There shall be no cracks, bubbles, scabs, creases, inclusions and rolled-in oxide scales on the surfaces of the steel plates. There shall be no visible delamination on the steel plates It is allowed to have thin layers of scale and rust not affecting the inspection of surface defects as well as unapparent surface asperities, scratches, creases and other local defects caused by the detachment of rolledin oxide scale. However, the depths thereof shall not be greater than half of the thickness tolerances. Furthermore, ENSURE the minimum thicknesses of the steel plates It is allowed to remove the surface defects of the steel plates by grinding. The positions to be ground shall be smooth without any edges and corners. Furthermore, ENSURE the minimum thicknesses of the steel plates. After agreed upon by the supplier and demander, it is allowed to repair by welding. The weld repairs shall conform to the provisions of GB/T Page 15 of 17

10 8.2 Steel plates shall be accepted in batches. Each batch shall be composed of the steel plates with the same grade, furnace number, thickness, delivery status and smelting under heat treatment. The weight of each batch shall not be greater than 60t. After agreed upon by the supplier and demander, and making indications in the contract, it is allowed to conduct group batching to the rolled steel plates sheet by sheet. 8.3 As for the steel plates with through-thickness characteristics, the rules for group batching shall conform to the provisions of GB/T Re-inspection and determination The re-inspection and determination of the steel plates shall conform to the provisions of GB/T After conducting or re-conducting heat treatment to the steel plates with through-thickness characteristics that do not pass the re-inspection, the supplier is allowed to submit the above-mentioned steel plates as a new batch for acceptance After re-conducting heat treatment to the steel plates that do not pass the delivery re-inspection after heat treatment, the supplier is allowed to submit the above-mentioned steel plates as a new batch for acceptance. 9 Packaging, symbols and quality certificate The packaging, symbols and quality certificate of steel plates shall conform to the provisions of GB/T Rounding off for numerical values The inspection results of the steel plates shall use the comparison method for rounding off values. The carbon equivalent and welding crack susceptibility index shall be calculated according to the equation before rounding off. The rules of rounding off shall be in accordance with the provisions of GB/T END Page 17 of 17