Improvement of Mechanical Properties of Automotive Components Using Hot Stamping With Integrated Q-P Process

Cold forming of high strength materials is accompanied by an undesirable spring-back effect and therefore the automotive industry prefers to produce components from high strength steels by hot stamping. Hot deformation and cooling in a die are applied to obtain shaped components with martensitic microstructure and high yield strength and ultimate tensile strength. This article presents new applications of this forming technology by incorporating another innovative heat treatment by the Q-P process, which improves both strength and ductility of obtained structures at the same time. Ultimate strengths over 2000 MPa with ductility above 10% can be achieved by this processing. To test microstructure development, thin sheet was hot formed and a corresponding FEM simulation was created. This processing was applied to low alloyed AHS steel with 0.42% of carbon and with an alloying strategy based on Mn, Si and Cr. Martensitic microstructure with retained austenite was obtained by this processing with a strength of around 2000 MPa and ductility of 10%.