High-strength thermal forming martensitic steel

Abstract

The invention belongs to the field of alloy steel, in particular to a high intensity hotforming martensite steel which is mainly applied to a thin part with the anti-tension intensity of 1.7 to 2.0GPa that is formed by hot punching. The main chemical components (weight percentage)of the steel are: 0.26 to 0.45 percent of C, 0.50 to 2.30 percent of Si, 0.50 to 2.00 percent of Mn, 0.50 to 1.50 percent of Cr, less than or equal to 0.018 percent of P, less than or equal to 0.010 percent of S, 0.015 to 0.060 percent of Al, equal to or less than 0.003 percent of [O], 0.002 to 0.015 percent of [N] and the rest are Fe as well as other unavoidable impurities. Besides, any one of or more than of 0.0005 to 0.0050 percent of B, 0.02 to 0.10 percent of Ti, 0.02 to 0.10 percent of Nb, 0.02 to 0.15 percent of V and 0.001 to 0.050 percent of RE are added. Compared with the 22MnB5 steel of the existing hotforming martensite steel, the anti-tension intensity of the steel of the invention is improved from 1.0-1.5GPa to 1.7-2.0GPa; besides, the steel has excellent plasticity (percentage of elongtation is larger than 12 percent) and the sensitivity to hydrogen induced delayed fracture is reduced remarkably; thereby providing foundation for vehicle light weight and high safety performance.

Description

Technical field [0001] The invention belongs to the field of alloy steel, and particularly relates to a high-strength hot-forming martensitic steel, which is mainly suitable for hot-stamping and forming thin-thickness parts steel with a tensile strength of 1.7-2.0 GPa. Background technique [0002] With the improvement of automobile light weight and safety, the steel for automobile structural parts is required to have higher and higher strength requirements under the premise of weight reduction. The strength levels of traditional ferritic steel, pearlite steel and bainite steel are all lower than 1.2GPa, so only ultra-high-strength martensitic steel can meet the requirements. Under normal circumstances, martensitic steel is obtained by quenching and tempering heat treatment after processing and forming. The quenching deformation of thin-thickness parts is very serious; and if the heat treatment and then cold stamping are used, the deformation will be difficult and the deformation...

AI Technical Summary

Problems solved by technology

For hot-formed martensitic steels, which are generally not tempered after the hot-forming process, the problem of hydrogen-induced delayed fracture may be more prominent due to the high dislocation density in the steel

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