780MPa-grade tensile strength hot rolling double-phase steel plate and manufacture method thereof

Abstract

The invention provides a 780MPa-grade tensile strength hot rolling double-phase steel plate and a manufacture method of the 780MPa-grade tensile strength hot rolling double-phase steel plate. The 780MPa-grade tensile strength hot rolling double-phase steel plate is prepared by the following components in percentage by weight: 0.07 to 0.12% of C, 0.2 to 0.7% of Si, 1.0 to 1.8% of Mn, 0.02 to 0.08% of Als, 0.5 to 1.2% of Cr, 0.02 to 0.05% of Nb, 0.01 to 0.03% of Ti, less than 0.02% of P, less than 0.005% of S, and the balance of Fe. The manufacture method is characterized by comprising steps as follows: heating a continuous casting slab blank of 80 to 230mm in thickness to reach a temperature of 1220+-20 DEG C, and maintaining the temperature for 2 to 4 hours; rolling in two stages in a control way, wherein initial rolling is carried out at the temperature of 1050 DEG C in a recrystallizing area; final rolling is carried out at the temperature of 840 to 920 DEG C in a non-recrystallizing area; a finished product is 2.5 to 6mm in thickness; and cooling a final rolled layer at a cooling rate at the temperature of 20 to 40 DEG C per second in a flowing way; and coiling at the temperature of 500 to 600 DEG C. Compared with a conventional intermediate-temperature coiled Mo-contained hot rolling double-phase steel, the 780MPa-grade tensile strength hot rolling double-phase steel plate provided by the invention has the advantages that cost is greatly reduced, a higher final rolling temperature is adopted, and a continuous cooling technology is carried out, so that load of a rolling machine can be reduced, and production processes can be simplified.

Description

technical field [0001] The invention belongs to the technical field of iron and steel production, and in particular relates to a hot-rolled dual-phase steel plate with a tensile strength reaching 780 MPa and mainly suitable for the automotive field and a manufacturing method thereof. Background technique [0002] Due to its superior mechanical properties and formability, dual-phase steels composed of soft phase ferrite and hard phase martensite are widely used in the automotive industry. In recent years, with the rapid development of the automobile industry, the lightweight of automobile structures has become increasingly important. In the ultra-light steel car body plan (ULSAB) formulated by the World Iron and Steel Association, the steel for ultra-light cars can increase the strength of the car body to 132% of the existing strength, reduce the weight of the car by 35%, and no longer need to add reinforcement components , can greatly reduce the manufacturing cost, and the ...

AI Technical Summary

Problems solved by technology

Although the hot-rolled dual-phase steel plate mentioned in the patent with the publication number CN1793400A has high strength, it adopts a staged cooling process after final rolling, which will make the cooling process complicated and difficult to control, thus affecting the final structure and performance of the steel plate Uniformity of

Images