High-hole-expanding and high-plasticity 980mpa cold-rolled continuous stripping steel plate and preparation method thereof

Abstract

The invention provides a 980MPa grade cold-rolled continuous stripping steel plate with high hole expansion and high plasticity and a preparation method thereof. The composition of the steel plate is calculated as follows in terms of mass percentage: C: 0.15%-0.18%, Mn: 1.8%-2.5%, Cr: 0.3% %~0.8%, Si: 0.5%~1.5%, Al: 0.05%~0.6%, P≤0.02%, S≤0.005%, Ti:≤0.03%, the rest are Fe and inevitable impurities. The preparation method includes smelting, hot rolling, pickling, cold rolling, continuous retreat, and smoothing; the application of the invention can produce a tensile strength of more than 980 MPa, a yield strength of 700 to 850 MPa, an elongation of 16% to 18%, and a hole expansion value of 50 MPa. % or more DH cold-rolled and continuously withdrawn steel sheets; and DH cold-rolled and continuously withdrawn steel sheets with a tensile strength of 980 MPa or more, a yield strength of 650 to 850 MPa, an elongation of 20% to 22%, and a hole expansion value of 40% to 50%.

Description

technical field [0001] The invention belongs to the field of metal materials, in particular to the field of automobile steel manufacturing, in particular to a 980MPa grade dual-phase steel cold-rolled and continuously withdrawn steel sheet with high hole expansion and high plasticity and a preparation method thereof.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 restrict the development of cold-formed steel. When the strength reaches more than 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 have to choose high-cost hot-formed parts instead, and abandon the use of high-strength cold-formed parts. For cold-rolled automotive steel sheets, the incompatibility of strength and plasticity is indeed a technical bot...

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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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