780MPa stage cold rolled hot galvanizing dual-phase steel with higher forming property and manufacturing method thereof

Abstract

The invention discloses 780MPa stage cold rolled hot galvanizing dual-phase steel with a higher forming property and a manufacturing method thereof. The steel comprises chemical components including,by mass percent, 0.1 to 0.2% of C, 1.3 to 2.5% of Mn, 0.4 to 1.0% of Si, not larger than 0.02% of P, not larger than 0.01% of S, not larger than 0.008% of N and the balance Fe and inevitable impurities. After conventional smelting, hot rolling and cold acid continuous rolling, through a QP process, hot dip galvanizing recrystallization annealing is carried out, a final tissue of a galvanized sheetmainly comprises ferrite, tempered martensite and residual austenite, the tensile strength is larger than or equal to 780 MPa, the percentage elongation is larger than or equal to 18%, n10 to 20% islarger than or equal to 0.14, the hole expansion rate lambda is larger than or equal to 25%, through control over the cold rate, the galvanized sheet reduces use of alloy elements, and the needs of reducing the alloy cost and improving the hot galvanizing dual-phase steel forming property can be achieved.

Description

technical field [0001] The invention belongs to the technical field of hot-dip galvanized steel sheets, and in particular relates to a 780MPa grade cold-rolled hot-dip galvanized dual-phase steel with relatively high formability and a manufacturing method thereof. Background technique [0002] Since the development of the automobile industry, dual-phase steel is still the most advanced high-strength steel used in body-in-white. Among them, hot-dip galvanized dual-phase steel is mostly used for body structural parts and reinforcements because of its excellent corrosion resistance. However, in the process of use, it is increasingly difficult for dual-phase steel to meet the stamping needs of complex parts. [0003] Patent documents such as Chinese Patent Publication No. CN105603306A, CN106119716A, US Patent US8882938B2 and WO2017 / 001303A1 disclose hot-dip galvanized DP steel with high elongation characteristics. The above patents all use C, Mn, Si, Al, and Cr as the main allo...

AI Technical Summary

Problems solved by technology

However, the high-strength cold-rolled hot-dip galvanized dual-phase steel involved in the patent has a high content of Al and Cr, which makes the manufacturability of the steel worse and the cost of the alloy increases.

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