Ferrite low-density high-strength steel and manufacturing method thereof

Abstract

A ferrite low-density high-strength steel and manufacturing method thereof. The ferrite low-density high-strength steel chemical comprises the following chemical components composition by mass percentage: 0.05-0.40% of C, 4.0-12.0% of Mn, 3.0-7.0% of Al, no more than 0.02% of P, no more than 0.01% of S, no more than 0.01% of N, and the balance of Fe and inevitable impurity elements. The above elements satisfy the following relationship: 1.0<Mn / Al, 3.5 <1.5Mn / Al+10C, and Mn / Al + 10C <5.2 The manufacturing method comprises hot rolling, annealing, pickling, cold rolling and annealing to prepare the low-density high-strength steel plate. In addition to ferrite, the microstructure of the steel plate also contains 6-40% of residual austenite. The low-density high-strength steel plate has tensile strength no less than 800MPa, elongation no less than 25%, and density less than 7500kg / m<3>.

Description

technical field [0001] The invention relates to high-strength steel, in particular to a ferrite low-density high-strength steel and a manufacturing method thereof. Background technique [0002] The application of high-strength steel and advanced high-strength steel to replace traditional low-strength grade steel can increase the specific strength (ratio of strength to density) of automotive steel and reduce the thickness of structural parts to achieve lightweight automotive structures. Another effective way to increase the specific strength of automotive steel is to reduce the density of the steel on the basis of maintaining the excellent mechanical properties of the above-mentioned high-strength steel. Therefore, the current development of low-density, high-strength and toughness steel plates is just to meet the urgent need to further realize the lightweight of automobiles. [0003] The mechanical properties of high-strength steel are determined by its chemical composition...

AI Technical Summary

Problems solved by technology

However, when the content of alloying elements is too high, the manufacturability of the steel grade is significantly reduced; moreover, the addition of excessive Al will inhibit the occurrence of the transformation-induced plasticity strengthening and toughening mechanism of ferritic steel, and will instead reduce the strength of the steel plate and plasticity

In addition, when the C content in the steel is too high, the surface layer of the steel plate will be severely decarburized during the hot working process.

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