Low-carbon low-cost ultra-high-strength composite steel plate/steel strip and manufacturing method thereof

Abstract

Low-cost ultra-high-strength multi-phase steel plate / steel strip and its manufacturing method, its composition weight percentage is: C 0.03-0.07%, Si 0.1-0.5%, Mn 1.3-1.9%, P≤0.02%, S≤0.01%, Al 0.01~0.05%, Cr 0.2~0.5%, Ti 0.07~0.14%, (Ni+Nb+Mo+V)<0.03%, the rest is Fe and other unavoidable impurities; and Mn+1.5Cr+5(Ti+ Al+Cu)+10(Mo+Ni)+20(Nb+V)<3.0; Mn+2Cr+4Ti+4Nb+4V+4MoSi / 3+2C≤3.0. The tensile strength of the steel plate of the present invention is ≥780MPa, the yield strength is ≥680MPa, the elongation is ≥15%, the yield strength ratio is ≥0.9, and the hole expansion rate satisfies: if the original hole is a punched hole: the hole expansion rate is ≥85%; if the original The hole is a reamed hole: the hole expansion rate is ≥115%, and the bending performance meets the 180°bending test. The bending angle diameter is equal to 0.5 plate thickness (d=0.5a) and will not crack; it is mainly used for the preparation of automobile chassis and suspension system parts.

Description

technical field [0001] The invention belongs to the field of metal materials, and in particular relates to a low-carbon, low-cost, ultra-high-strength complex-phase steel sheet / steel strip and a manufacturing method thereof, which are mainly used for manufacturing parts and components of automobile chassis and suspension systems. Background technique [0002] "Lightweight" automobiles can directly reduce emissions and fuel consumption, which is the goal of today's automobile manufacturing industry. An important measure for the "lightweight" of automobiles is to replace low-strength steel plates with high-strength and ultra-high-strength steel plates. At present, the concept of "lightweight" is further applied to the automobile chassis and suspension system. The increasingly stringent environmental protection requirements and market demands also require the use of high-strength steel for automobile chassis materials to achieve "lightweight". [0003] However, in addition to ...

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Problems solved by technology

[0011] Therefore, for this kind of low-carbon composite phase steel (hereinafter referred to as low-carbon high-strength composite phase steel) with a tensile strength of 800 MPa used in the manufacture of automobile chassis and suspension system parts, the existing technology cannot solve its low-cost design. Contradictions with high comprehensive service performance, even if the low-cost design that has been disclosed is adopted, the strength, yield ratio, hole expansion performance and bending performance of the material cannot be achieved at the same time

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