High-reaming high-plasticity 980MPa-grade cold-rolled continuously-annealed steel plate and preparation method thereof

Abstract

The invention provides a high-reaming high-plasticity 980MPa-grade cold-rolled continuous annealing steel plate and a preparation method thereof. The steel plate comprises the following components in percentage by mass: 0.15%-0.18% of C, 1.8%-2.5% of Mn, 0.3%-0.8% of Cr, 0.5%-1.5% of Si, 0.05%-0.6% of Al, less than or equal to 0.02% of P, less than or equal to 0.005% of S, less than or equal to 0.03% of Ti and the balance of Fe and inevitable impurities. The preparation method comprises the steps of smelting, hot rolling, acid pickling, cold rolling, continuous annealing and finishing. By means of the preparation method, a DH cold-rolled continuous annealing steel plate with the tensile strength being 980 MPa or above, the yield strength being 700-850 MPa, the ductility being 16%-18% and the reaming value being 50% or above can be produced; and the DH cold-rolled continuous steel sheet with the tensile strength being 980MPa or more, the yield strength being 650-850MPa, the ductility being 20%-22%, and the reaming value being 40%-50% can be produced.

Description

technical field [0001] The invention belongs to the field of metal materials, in particular to the field of steel manufacturing for automobiles, in particular to a 980MPa dual-phase cold-rolled continuous-annealing steel plate with high hole expansion and high plasticity and a preparation method thereof. Background technique [0002] In the competition between cold-formed steel and hot-formed steel, extremely poor formability has always been the key to limit the development of cold-formed steel. When the strength reaches above 980MPa, the low ductility makes it difficult to produce more complex structural parts by cold stamping, and the rolling method greatly increases the manufacturing cost of the material. This makes many car companies can only choose high-cost hot-formed parts instead of high-strength cold-formed parts. For cold-rolled automotive steel sheets, the incompatibility between strength and plasticity is indeed a technical bottleneck restricting the development...

AI Technical Summary

Problems solved by technology

However, a considerable amount of precious elements such as Nb, Cr, Mo, and Ni are added to the steel, which greatly increases the cost of the alloy

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