STEEL FOR HOT STAMPING FORMING, HOT STAMPING FORMING PROCESS AND HOT-STAMPING FORMED COMPONENT

摘要

The present invention relates to a steel material for hot stamp forming with ultra-fine grains and a process of making the same, a hot stamp forming process and a hot stamp formed member. The steel material for hot stamp forming comprises the following components by weight: 0.27 to 0.40% of C; 0.2 to 3.0% of Mn; 0.11 to 0.4% of V; 0 to 0.8 % of Si; 0 to 0.5% of Al; 0 to 2% of Cr; 0 to 0.15% of Ti; 0 to 0.15% of Nb; 0 to 0.004% B; a total of less than 2% of Mo, Ni, Cu and other alloying elements that are beneficial to improving the hardenability, and other impurity elements. After hot stamp forming or equivalent heat treatment, the steel material or the formed member of the present invention can achieve a yield strength of 1300 MPa to 1700 MPa, a tensile strength of 1800 to 2200 MPa, and an elongation of 6 to 9% after direct hot stamping quenching and without tempering, which properties cannot be achieved by a material with a composition in the prior art in the situation of direct quenching (no tempering). After the tempering treatment of the present invention, preferably 1500 MPa - 1900 MPa - 8%, and 1600 MPa - 2100 MPa - 7% can be reached.