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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 11251-2009 Hot-rolled alloy structural steel plates. The following main technical changes have been made with respect to GB/T 11251-2009:
——the hot-rolled strip of alloy structural steel and relevant technical requirements are added, and the thickness range of hot-rolled plate of alloy structural steel is modified (see Clause 1);
——the order contents are modified (see Clause 3; Clause 3 of Edition 2009);
——the high-temperature tempered delivery condition is added (see 5.2);
——the Brinell hardness of steel plate delivered in high-temperature tempered condition is added (see 5.3.1);
——the requirements for macrostructure are deleted (see 5.5 of Edition 2009);
——the requirements for ultrasonic testing are added (see 5.7);
——the requirements for surface quality are modified (see 5.8; 5.8 of Edition 2009);
——the special requirements are added (see 5.9);
——the batching rules are modified (see 7.2; 7.2 of Edition 2009);
——the rounding-off requirements for numerical value are added (see 7.5);
——the Annex A (normative) "Dimension, shape, weight and tolerance for steel strip" is added (see Annex A).
This standard was proposed by China Iron and Steel Industry Association.
This standard is under the jurisdiction of the National Technical Committee on Iron and Steel of Standardization Administration of China (SAC/TC 183).
The previous editions of this standard are as follows:
——GB/T 11251-1989 and GB/T 11251-2009.
Alloy structural steel plate and strip
1 Scope
This standard specifies the order contents, dimension, shape and weight, technical requirements, test methods, inspection rules, as well as packaging, marking and quality certificate of alloy structural steel plate and strip.
This standard is applicable to the hot-rolled plate of alloy structural steel (hereinafter referred to as “steel plate”) having a thickness of 4~200mm and the hot-rolled strip of alloy structural steel (including sheared steel plate) (hereinafter referred to as “steel strip”) having a thickness not greater than 12mm and a width less than 600mm.
2 Normative references
The following referenced documents are indispensable for the application 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 222 Permissible tolerances for chemical composition of steel products
GB/T 224 Determination of depth of decarburization of steel
GB/T 228.1-2010 Metallic materials - Tensile testing - Part 1: Method of test at room temperature
GB/T 229 Metallic materials - Charpy pendulum impact test method
GB/T 231.1 Metallic materials - Brinell hardness test - Part 1: Test method
GB/T 232 Metallic materials - Bend test
GB/T 247 General rule of package, mark and certification for steel plates (sheets) and strips
GB/T 709-2019 Dimension, shape, weight and tolerance for hot-rolled steel strip, plate and sheet
GB/T 2970-2016 Method for ultrasonic testing of thicker steel plates
GB/T 2975 Steel and steel products - Location and preparation of samples and test pieces for mechanical testing
GB/T 3077 Alloy structure steels
GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values
GB/T 10561-2005 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 34474.1 Determination of banded structure of steel - Part 1: Micrographic method using standards diagrams
3 Order contents
Contracts or orders made based on this standard shall cover the following items:
a) No. of this standard;
b) product name;
c) grade;
d) dimension and thickness precision (wherein, thickness precision is only applicable to steel strip, see Table A.1);
e) delivery weight (or quantity);
f) delivery condition (see 5.2);
g) edge condition (see 5.2.1.4, 5.2.2 and Table A.2);
h) processing purpose;
i) special requirements.
4 Dimension, shape and weight
4.1 The dimension, shape, weight and tolerance of steel plate shall meet the requirements of GB/T 709-2019, wherein, the thickness tolerance shall conform to Category A deviation.
4.2 The dimension, shape, weight and tolerance of steel strip shall meet the requirements of Annex A.
5 Technical requirements
5.1 Grades and chemical composition
5.1.1 The common grades and chemical composition of steel shall meet the requirements of GB/T 3077.
5.1.2 The chemical composition tolerance of steel products shall meet the requirements of GB/T 222.
5.2 Delivery condition
5.2.1 Delivery condition of steel plate
5.2.1.1 The steel plate shall be delivered in the high-temperature tempered condition. As required by the purchaser and specified in the contract, it may also be delivered in the annealed, normalized or normalized + tempered condition.
5.2.1.2 The steel plate may be subjected to normalizing rolling instead of normalizing treatment provided that its mechanical properties meet those specified in 5.3.3.
5.2.1.3 As required by the purchaser and specified in the contract, the steel plate may be delivered after pickling.
5.2.1.4 The steel plate shall be delivered after trimming; the delivery in other edge conditions shall be indicated in the contract. The longitudinal edge of coil cutting steel plate may not be cut.
5.2.2 Delivery condition of steel strip
Generally, steel strips are delivered after hot rolling without edge trimming. As required by the purchaser, steel strips delivered in other special conditions may be supplied, with specific requirements indicated in the contract through negotiation between the supplier and the purchaser.
5.3 Mechanical properties
5.3.1 The surface Brinell hardness of the steel plate delivered in high-temperature tempered condition shall meet the requirements of GB/T 3077.
5.3.2 The mechanical properties of the steel plate delivered in annealed condition shall meet the requirements of Table 1.
Contents
Foreword i
1 Scope
2 Normative references
3 Order contents
4 Dimension, shape and weight
5 Technical requirements
6 Test methods
7 Inspection rules
8 Packaging, marking and quality certificate
Annex A (Normative) Dimension, shape, weight and tolerance for steel strip
