Inverse Estimation of Interfacial Heat Transfer Coefficient Between Blank and Die in Hot Stamping

In this paper, a FEM method based on optimization was used to estimate the interfacial heat transfer coefficient between blank and die during hot stamping process. The temperature data of blank center and the point 1.5 mm under die surface's center at the holding pressure range from 5 MPa to 40 MPa were foremost obtained during hot stamping experiment by a two-piece cylindrical die experiment. The interfacial heat transfer coefficient (IHTC) depended on holding pressure was computed through FEM method based on optimization, and the effect of thermocouple response time and latent heat resulting from martensitic transformation were taken into account. The results show that the approximate relationship of IHTC and holding pressure is linear, and the relative error between experiment data and simulated data can be controlled within 15%. Moreover, the mean absolute error is less than 24°C, whereas different IHTC values and trends will be gained when using different experiment models and inverse methods.