1.5 GPa-grade ultrahigh-strength high-plasticity high-reaming DH steel plate and preparation method thereof

Abstract

The invention provides a 1.5 GPa-grade ultrahigh-strength high-plasticity high-reaming DH steel plate and a preparation method thereof. The steel plate comprises the following components in percentages by weight: 0.20%-0.26% of C, 1.8%-2.8% of Mn, 1.0%-2.0% of Si, 0.02%-0.08% of Al, 0.20%-0.80% of Cr, less than or equal to 0.01% of P, less than or equal to 0.01% of S, 0.02%-0.15% of Nb, 0.02%-0.15% of V, 0-0.10% of Ti and the balance of Fe and inevitable impurities. The preparation method comprises the steps of smelting, medium and thin slab continuous casting, hot continuous rolling, acid pickling and cold rolling, continuous annealing and finishing. The yield strength of the steel plate produced by the method is 1000-1350 MPa, the tensile strength is 1470-1650 MPa, the A80 percentage elongation after fracture is greater than or equal to 9.0%, and the hole expansion rate is greater than or equal to 15%.

Description

technical field [0001] The invention belongs to the field of metal materials, and in particular relates to a cold-rolled DH1500 steel plate for automobiles with ultra-high strength, high plasticity and high hole expansion performance and a manufacturing method thereof. Background technique [0002] In recent years, as the automotive industry has higher and higher requirements on the formability of materials, traditional dual-phase steels have been difficult to meet the high ductility requirements of complex stamping parts, and TRIP steels have expensive production costs due to high alloy content. This limits its widespread use. Due to the introduction of a certain amount of retained austenite into the traditional dual-phase steel, the DH steel that emerged at the historic moment can make the material exhibit excellent formability through the TRIP effect, which can significantly overcome the shortcomings of DP steel and TRIP steel in the above application process , DH steel ...

AI Technical Summary

Problems solved by technology

This invention adopts the production process of cold rolling and continuous annealing to produce cold-rolled dual-phase steel with a strength level of 1200MPa. However, the product has very poor plasticity, and it is difficult to combine ultra-high strength with good ductility and formability.

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