Ultra-high-strength medium-manganese automotive steel plate with excellent plasticity and preparation method thereof

Abstract

The invention provides a super-high-strength medium-Mn automobile steel plate with excellent plasticity and a preparing method thereof and belongs to the technical field of production of third-generation steel plate rolls for automobiles. The super-high-strength medium-Mn automobile steel plate comprises the following chemical components in a percent: 0.3-0.5wt% of C, 8-12wt% of Mn, 1.8-3.5wt% of Al, 0.25-0.7wt% of V, smaller than or equal to 0.008wt% of P, smaller than or equal to 0.08wt% of S and the balance of Fe and unavoidable impurities. Through reasonable chemical components and technical design, a comprehensive application strengthened by various mechanisms, such as precipitation strengthening, deformation induced phase change strengthening and twinning strengthening, is realized, thereby obtaining super-high strength. Through hot rolling, acid pickling, warm rolling and cover annealing technologies, the steel plate with more than 1500MPa tensile strength and 20-40GPa.% static toughness can be obtained; and otherwise, the cold-rolled steel plate with more than 1200MPa tensile strength and 35-65GPa.% static toughness can be obtained through hot rolling, hot rolling annealing, acid pickling, cold rolling and continuous annealing technologies.

Description

technical field [0001] The invention belongs to the production technical field of the third-generation high-strength steel sheet coil for automobiles, and in particular provides an ultra-high-strength medium-manganese automobile steel sheet with excellent plasticity and a preparation method. It is a new steel grade developed based on a variety of strengthening mechanisms and the design concept of combining composition and structure control. It focuses on obtaining ultra-fine grains and submicron precipitates through different rolling process control and composition design, and adopts suitable The critical zone annealing treatment obtains ferrite and austenite and other multiphase structures, and the preparation process of a new type of ultra-high-strength automotive steel plate with excellent plasticity is obtained by means of precipitation strengthening, deformation-induced phase transformation strengthening and twinning strengthening. Background technique [0002] With the...

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Problems solved by technology

[0004] It can be seen from the above that although the medium manganese TRIP steel can obtain good plasticity through the composition of no more than 9% Mn content, and the strong plastic product reaches more than 30GPa·%, but its yield strength is generally <700MPa, and its tensile strength is generally in Within 1000Pa, no more than 1300MPa, which seriously hinders the process of further lightweighting of automobiles

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