Low-cost 780MPa-grade cold-rolling dual-phase steel and production method thereof

Abstract

The invention discloses low-cost 780MPa-grade cold-rolling dual-phase steel which is prepared from the chemical components in percentage by mass: 0.11 percent to 0.13 percent of C, 0.30 percent to 0.38 percent of Si, 1.55 percent to 1.65 percent of Mn, less than or equal to 0.020 percent of P, less than or equal to 0.003 percent of S, 0.020 percent to 0.060 percent of Alt, 0.32 percent to 0.40 percent of Cr, and less than or equal to 0.0070 percent of N. The invention further discloses a production method thereof. According to the low-cost 780MPa-grade cold-rolling dual-phase steel and the production method thereof provided by the invention, 780MPa-grade cold-rolling dual-phase steel smelting components with low cost are designed, a high hydrogen rapid-cooling function in the continuous annealing process is fully played, the cooling speed is accelerated, and the sufficient amount of martensitic structures can be produced by phase change, so that the performance of a final product meetsthe standard requirement of the 780MPa-grade cold-rolling dual-phase steel, the surface quality reaches to more than the FB grade, the percentage elongation after tensile fracture is high, and an excellent punch forming performance is realized.

Description

technical field [0001] The invention relates to the technical field of metallurgy, in particular to a low-cost 780MPa grade cold-rolled dual-phase steel and a production method thereof. Background technique [0002] In recent years, the rapid development of the automobile industry has strongly promoted the medium-to-high speed development of my country's national economy, but the resulting high energy consumption and high emissions are seriously polluting the environment and causing many negative effects on people's daily life. Therefore, in order to realize the sustainable development of the automobile industry, it is necessary to solve the problems of energy saving, emission reduction, low-carbon and environmental protection, which is also the primary problem faced by the automobile industry of various countries. This has led people to put forward new requirements for modern vehicles that integrate safety, environmental protection, comfort, and energy saving. It is necessa...

AI Technical Summary

Problems solved by technology

The 780MPa cold-rolled dual-phase steel smelting process involved in this patent adopts the double refining process of LF+RH. A certain amount of Nb and Ti elements are added to the alloy elements, and the smelting cost is relatively high. The annealing process only controls the soaking temperature of 750-800°C , the soaking time is 60-220s, the overaging temperature is 240-300℃, the holding time of the overaging section is 300-1225s, the large temperature fluctuation range leads to the unstable proportion of martensite in the final product, and the holding time control of the overaging section will be It will affect the production capacity of the cold rolling continuous annealing production line, and the production cost is high

[0008] To sum up, there are certain unfavorable factors in the existing 780MPa cold-rolled dual-phase steel production methods. Part of the unfavorable factors is that the annealing control needs to be kept warm, which affects the production capacity of the cold-rolled production line; the other part is that the cost of the alloy is too high. Need to add expensive trace elements such as Nb and Ti

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