Investigation of austenitising behaviour of medium-Mn steel in the hot-stamping heating process

In this study, the austenite transformation behaviour in a medium-Mn (MMn) steel is investigated during heat treatments that replicate those occurring low-temperature hot stamping (LTHS), with aim of better understanding to optimise heat-treatment design. The austenitisation and critical phase temperatures LTHS heating process their dependence on conditions are using dilatometry Gleeble 3800 thermal-mechanical simulator, covering rates 1–25 °C s?1 soaking 630–900 °C. Both higher rate temperature found be beneficial shorten time required for obtaining given fraction. martensite start (Ms) shows rapid increase increasing when partial, slower after full austenitisation. Excellent ultimate tensile strength values around 1750 MPa total elongation 9.3 % obtained material process. A physically based model describing austenitic under these has been adopted calibrated. good agreement diagrams constructed from experimental data, thus can function as guide selecting optimum parameters LTHS.