Measurement of Heat Transfer Coefficient of Boron Steel in Hot Stamping

Abstract

The characteristic of the heat transfer coefficient of the boron steel for hot stamping process was studied in this paper. For obtaining the 1400 MPa high strength product by the hot stamping process, the microstructure of blank has to be transformed from austenite to fully martensite by the quenching process in closed tools. The heat transfer coefficient between the blank and tools then becomes an important role which may affect the cooling rate and the final microstructure distribution of the blank. In this study, the experimental platform was built, and the inverse calculating method was used for obtaining the heat transfer coefficient. The influence of the contact pressure on the heat transfer coefficient was also investigated, and it reveals that the contact pressure affect the interface heat transfer most. From the FEM simulations, it also shows that the temperature histories of the blank and tools are good agreement to the experiment results, which imply the feasibility of the experiment platform and the method for obtaining the heat transfer coefficient.