HIGH-STRENGTH-AND-TOUGHNESS AND HIGH-STRENGTH-DUCTILITY-PRODUCT AUTOMOBILE STEEL AND PREPARATION METHOD THEREFOR

摘要

A high-strength-and-toughness and high-strength-ductility-product automobile steel and a preparation method therefor. The present invention belongs to the technical field of the manufacturing of high-strength-and-toughness and high-strength-ductility-product automobile steels. The chemical composition of the steel comprises: 0.15-0.60 wt% of C, 0-2.0 wt% of Si, 0-2.0 wt% of Ni, 3.0-6.0 wt% of Mn and 2.0-6.0% of Al, with the balance being Fe and inevitable impurity elements. On this basis, one or more of the following microalloying elements may be added: 0-0.10 wt% of Nb, 0-0.10 wt% of V, 0-0.10 wt% of Ti, 0-0.10 wt% of Mo, 0-0.50 wt% of Cu, and 0.0005-0.005 wt% of B. The advantages lie in forming a multiphase, multilayer and metastable microstructure by means of alloying with C, Mn, Al, etc., performing dual phase zone rolling and annealing, having a V-shaped impact toughness of not less than 120 J at -40°C and a strength-ductility product of not less than 50 GPa%, and a low cost and a high performance, wherein the cost is much lower than that of traditional high manganese steel, and the comprehensive mechanical performance is much higher than that of medium manganese steel. The present invention can be used in the field of the manufacturing of automobile bodies in white and transmission parts and components in the form of a bar or plate.