Hot-formed steel directly rolled from medium-thin sheet billet and having tensile strength equal to or higher than 1300 MPa and production method

Abstract

The invention provides hot-formed steel directly rolled from a medium-thin sheet billet and having the tensile strength equal to or higher than 1300 MPa. The hot-formed steel comprises, by weight, 0.17%-0.20% of C, 0.21%-0.25% of Si, 1.0%-1.3% of Mn, 0-0.01% of P, 0-0.008% of S, 0.015%-0.060% of Als, 0.19%-0.24% of Cr, 0.021%-0.025% of Ti, or 0.021%-0.025% of Nb, or 0.021%-0.025% of V or the mixture of any two of Ti, Nb and V according to any proportion, 0.002%-0.003% of B, 0.14%-0.16% of Mo, and 0-0.005% of N. A production method comprises the steps of molten iron desulphurization, smelting and refining in an electric furnace or a converter, continuous casting, descaling treatment before molten iron enters a soaking pit, soaking, heating, high-pressure water descaling before the molten iron enters a rolling mill, rolling, cooling, reeling, austenitizing, stamp-forming through a die, and quenching. According to the hot-formed steel directly rolled from the medium-thin sheet billet and having the tensile strength equal to or higher than 1300 MPa and the production method, the procedure is short, the surface quality of a product is good, the thickness precision is high, the requirement for the quality of cold-rolled products can be met, and complex deformation can be completed successfully; and in addition, restoration after deformation is avoided, and the dimensional precision of parts is high.

Description

technical field [0001] The invention relates to a steel for auto parts and a production method thereof, in particular to a hot-formed steel with a tensile strength ≥ 1300 MPa directly rolled with a medium-thin slab and a production method thereof, and is suitable for producing products whose thickness is greater than 2 to 100 MPa. 10mm. Background technique [0002] With the development of the automobile industry and the gradual development of automobile design and manufacturing in the direction of energy saving, environmental protection and safety, automobile lightweight has become the mainstream direction of automobile design at present and for a long time to come. [0003] The study found that the vehicle's vehicle weight and energy consumption have a linear relationship. According to statistics, every 10% reduction in vehicle weight can increase fuel efficiency by 6% to 8%. One of the most important ways to reduce the weight of automobiles is to use high-strength and u...

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Problems solved by technology

[0006] The present invention overcomes the low strength level existing in the prior art and cannot meet the shortage of automobile design for ultra-high-strength parts, and provides a short process, good product surface quality, high thickness precision, and can meet the quality requirements of cold-rolled products. Complicated deformation can be successfully completed, and there is no springback after deformation, the dimensional accuracy of the parts is high, the tensile strength is ≥ 1300MPa hot-formed steel and its production method

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