Cold-rolled high-strength steel plate having excellent phosphating performance and formability and manufacturing method therefor

Abstract

A cold-rolled high-strength steel plate having excellent phosphating performance and formability and a manufacturing method therefor. The chemical composition of the steel plate is, in percentage by weight, C 0.01-0.20%, Si 1.50-2.50%, Mn 1.50-2.50%, P≤0.02%, S≤0.02%, Al 0.03-0.06%, N≤0.01%, the remainder being Fe and impurities. The surface layer of the steel plate has an inner oxide layer with a thickness of 1-5 μm, and there is no enrichment of Si and Mn on the surface of the steel plate. The steel plate has good phosphating performance and formability, with a tensile strength of ≥980 MPa and an elongation of ≥20%. The structure at the room temperature contains retained austenite, ferrite, and martensite and/or bainite. In the method, the dew point of atmosphere in a heating zone and a soaking zone is controlled during continuous annealing, to inhibit the enrichment of elements such as Si and Mn on the surface of the steel plate, and transition external oxidation to internal oxidation, so that the steel plate has good phosphating performance.

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