1200MPa-grade hot-rolled high-strength dual-phase steel plate and manufacturing method thereof

Abstract

The invention discloses a 1200MPa-grade hot-rolled high-strength dual-phase steel plate which is prepared from the following chemical components in percentage by weight: 0.10-0.18 percent of C, 0.80 -1.50 percent of Si, 1.50-2.20 percent of Mn, smaller than or equal to 0.015 percent of P, smaller than or equal to 0.008 percent of S, 0.40-0.80 percent of Cr, 0.010 -0.050 percent of Nb, 0.010-0.040percent of Ti, 0.020-0.060 percent of Als and the balance of Fe and inevitable impurities. The microstructure of the 1200MPa-grade hot-rolled high-strength dual-phase steel plate is a dual-phase tissue with ferrite plus martensite, wherein the volume fraction of the ferrite is 20-30 percent, the volume fraction of the martensite is 70-80 percent, the yield strength of a product is larger than or equal to 650MPa, the tensile strength is larger than or equal to 1200MPa, the elongation A50 is larger than or equal to 16 percent, the yield ratio is smaller than or equal to 0.65, the cold bending performance is 180 DEG C, the product is qualified if D is equal to 4a, and the 1200MPa-grade hot-rolled high-strength dual-phase steel plate has relatively high strength, relatively low yield ratio andrelatively good forming performance.

Description

technical field [0001] The invention relates to the technical field of hot-rolled high-strength steel production technology, in particular to a 1200MPa hot-rolled high-strength dual-phase steel plate and a manufacturing method thereof. Background technique [0002] Hot-rolled dual-phase steel has been used in the manufacture of automobile wheels by GM, Ford, Beijing Jeep and other automobile manufacturers due to its good strong plasticity, low yield ratio, high initial work hardening rate, good bake hardening performance and fatigue resistance. . At present, subject to factors such as product surface quality, microstructure uniformity, and hole expansion performance, the hot-rolled dual-phase steel produced and applied at home and abroad is mainly DP540-DP600, and the dual-phase steel of DP980 and above is still cold-rolled. Mainly. Therefore, the development of DP980 and above hot-rolled dual-phase steel is of great significance for promoting the "replacing heat with cold...

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Problems solved by technology

[0004] The above-mentioned patents for DP980 and above hot-rolled dual-phase steel, the chemical composition is mainly C-Si-Mn or C-Si-Mn-Al design ideas, and the structure type of dual-phase steel corresponding to the C-Si-Mn composition design ideas It is ferrite + martensite, and the product strength level is only 980MPa; the structure types of dual-phase steel corresponding to the C-Si-Mn-Al composition design idea are ferrite + martensite and ferrite + bainite. Among them, the tensile strength level of the product corresponding to the ferrite + martensite dual phase structure is 1180MPa, and the product tensile strength level corresponding to the ferrite + bainite dual phase structure is 980MPa; but the C-Si-Mn- Al composition design ideas, Al content ranges from 0.5 to 1.0%, higher Al content will cause poor castability of molten steel

At present, there is still no patent related to the design of other chemical compositions, except for C-Si-Mn-Al series, and through the optimization of the rolling, cooling and coiling process, it is possible to produce 1200MPa hot-rolled high-strength dual-phase with good cold-bending performance steel

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