Low-carbon, low-cost and ultrahigh-strength complex-phase steel plate/steel strip and manufacturing method thereof

Abstract

The invention discloses a low-cost and ultrahigh-strength complex-phase steel plate / steel strip and a manufacturing method thereof. The low-cost and ultrahigh-strength complex-phase steel plate / steel strip comprises the following components in percentage by weight: 0.03-0.07% of C, 0.1-0.5% of Si, 1.3-1.9% of Mn, less than or equal to 0.02% of P, less than or equal to 0.01% of S, 0.01-0.05% of Al, 0.2-0.5% of Cr, 0.07-0.14% of Ti, less than 0.03% of (Ni+Nb+Mo+V) and the balance of Fe and other inevitable impurities, Mn+1.5Cr+5(Ti+Al+Cu)+10(Mo+Ni)+20(Nb+V) is less than 3.0; and Mn+2Cr+4Ti+4Nb+4V+4Mo-Si / 3+2C is less than or equal to 3.0. The tensile strength of the steel plate is larger than or equal to 780 MPa, the yield strength is larger than or equal to 680 MPa, the ductility is larger than or equal to 15%, the yield ratio is larger than or equal to 0.9, and the hole expansion rate meets the conditions that if original holes are punched holes, the hole expansion rate is larger than or equal to 85%; If the original holes are reamed holes, the hole expansion rate is greater than or equal to 115%, and the bending property meets the requirement that when the bending angle diameter in a 180-degree bending experiment is equal to 0.5 plate thickness (d is equal to 0.5 a), the original holes do not crack; and the method is mainly used for preparing automobile chassis and suspension system parts.

Description

technical field [0001] The invention belongs to the field of metal materials, and specifically relates to a low-carbon, low-cost, ultra-high-strength composite steel plate / steel strip and a manufacturing method thereof, which are mainly used in the manufacture of parts and components of automobile chassis and suspension systems. Background technique [0002] The "light weight" of automobiles can directly reduce emissions and fuel consumption, which is the goal of the development of today's automobile manufacturing industry. An important measure of automobile "lightweight" is to use high-strength and ultra-high-strength steel plates instead of low-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 demand also require the use of high-strength steel for automobile chassis materials to achieve "lightweight". [0003] Howeve...

AI Technical Summary

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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