Study on Austenitizing Process in Hot Stamping of 2000 MPa Grade Ultra-High Strength Steel

Abstract

With the rapid development of the automobile industry and the increasing requirement of the environmental protection, ultra-high strength hot stamping steel is widely used in body parts of the car. In this paper, the precipitation changes of the second phase particles and CCT curves of 2000 MPa ultra-high strength steel under different austenitizing conditions are studied by the thermodynamic calculations and simulations. The effects of austenitizing temperature, holding time and cooling rate on the quenching transformation behaviors of the steel in the hot stamping process are explored. The microstructure differences on the surface and internal positions of the steel in the austenitizing quenching process are compared and analyzed. The austenitizing process parameters suitable for 2000 MPa ultra-high strength hot stamping steel are formulated, which provides a theoretical basis for the formulation of 2000 MPa ultra-high strength steel in the hot stamping process.