High-surface-quality hot-rolled automobile steel with tensile strength larger than 1300MPa and manufacturing method of high-surface-quality hot-rolled automobile steel

Abstract

The invention provides high-surface-quality hot-rolled automobile steel with the tensile strength larger than 1300 MPa and a manufacturing method of the high-surface-quality hot-rolled automobile steel. The high-surface-quality hot-rolled automobile steel is prepared from 0.22%-0.25% of C, 1.20%-1.80% of Si, 1.60%-2.20% of Cr, 1.00%-1.40% of Mn, 0.020%-0.030% of Nb, 0.020%-0.050% of Al, smaller than or equal to 0.020% of P, smaller than or equal to 0.010% of S, smaller than or equal to 0.0003% of H, smaller than or equal to 1.1% of C + (Mn + Si + Cr) / 6, smaller than or equal to 1.5% of Si / Mn and the balance Fe and inevitable impurities. Compared with the prior art, according to the brand-new hot forming steel component design added with Cr and Si, the production method is controlled, and a layer of compact oxidation film is formed on the surface of the steel plate; the yield strength of the finished product is larger than or equal to 800 MPa, the tensile strength is larger than or equal to 1300 MPa, the ductility A80 is larger than or equal to 8%, and Rp0.2 / Rm of the finished product is smaller than or equal to

Description

technical field [0001] The invention belongs to the technical field of metal material processing, and in particular relates to a hot-rolled automobile steel with a thickness of 2.0-4.0 mm, a tensile strength greater than 1300 MPa and high surface quality and a manufacturing method thereof. Background technique [0002] Energy saving, environmental protection and safety are the three major challenges facing the development of the automobile industry today. The implementation of lightweight vehicles can reduce the weight of the vehicle body and reduce energy consumption without sacrificing safety performance. At the same time, the light weight will also improve vehicle handling stability and collision safety to a certain extent. In the selection of lightweight materials for automobiles, the application of high-strength steel is one of the main ways. [0003] As the strength of the steel plate increases, its elongation decreases significantly, and the formability also decreas...

AI Technical Summary

Problems solved by technology

However, the above preparation methods have the following defects: as the strength increases, the coherent distortion is non-uniformly distributed, thereby increasing the tendency of the material to produce cracks during the deformation process, ensuring that the material has high strength while maintaining good plasticity at the same time. Meet the market's requirements for high-strength thinning and plastic processing; the cost is greatly increased due to the large amount of alloying elements such as Mo and W, which is not conducive to widespread use; The steel and continuous casting process presents greater difficulties and will greatly reduce the weldability of the finished product

This patent does not add Nb, Cr, and Mo alloys, but in order to obtain the strength requirement above 1300MPa, a large amount of Mn and Al elements are added, and in order to reduce the harmful effect of Al, Re rare earth elements are added to form compounds with higher melting points. Improve the plasticity of the material, but a large amount of Mn will reduce the welding performance of the finished product

In addition, the yield strength of the finished product is ≥1000MPa, the tensile strength is ≥1300MPa, the yield strength ratio is high (77%), and the part formability is poor

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