GB/T 2517-1981
General Structural Hot Rolled Steel Sheets and Strips Allowable Deviation
GB/T 2517-1981 is a standard for hot rolled steel sheets and strips for general structural purposes. Adopted on June 1, 1981, it was issued and promulgated by the Peoples Republic of China General Administration of Quality Supervision, Inspection and Quarantine.
GB/T 2517-1981 defines the allowable deviation of thickness, width and diagonal differences. The allowable deviation of steel sheet and strip thickness shall be plus or minus 0.3 mm. The allowable deviation of width and diagonal difference shall be determined according to the basic width of the sheet, and the ratio of the width tolerance to the basic width shall not exceed ±5%.
The steel sheets and strips manufactured according to GB/T 2517-1981 shall be tested on bending and tension strength and elongation. According to the specifications of the products, all the products shall produce corresponding test results in order to establish the qualification.
In order to ensure the quality and performance of the products, GB/T 2517-1981 stipulates requirements for grain size and surface quality. The acceptable grain sizes are No. 6 and No. 8 respectively. The surface quality according to the types of products, for hot-rolled sheets, the surface should be free of any cracks, scars or other defects; for hot-rolled strips, it should be free from any scrapes and other defects that may influence the use.
GB/T 2517-1981 provides specifications for designating hot rolled steel sheets and strips for general purposes. The designation requires that the designation must include the steel grade, the type and batch of product, the size and strength rate of the products. The grade is expressed using a three-digit number defining the yield point. Type of product is expressed in a two-digit number, batch is expressed by a one-digit number and size is expressed in a five-digit number which should be specified in millimeters. The strength rate is expressed as a number representing the proportion between strength level and thickness in percentage.
In conclusion, GB/T 2517-1981 is a standard for hot rolled steel sheets and strips for general structure purposes. It stipulates the requirements of product tolerances, surface quality, grain size, and the designation of steel sheet and strip. With the implementation of the standard, manufacturers of general structural hot rolled steel sheet and strip can produce product that can meet the requirements and needs of the market.
