Determination of the Interfacial Heat Transfer Coefficient in the Hot Stamping of AA7075

Abstract

The interfacial heat transfer coefficient (IHTC) is a key parameter in hot stamping processes, in which a hot blank is formed and quenched by cold dies simultaneously. The IHTC should therefore be identified and used in FE simulations to improve the accuracy of simulation results of hot stamping processes. In this work, a hot stamping simulator was designed and assembled in a Gleeble 3800 thermo-mechanical testing system and a FE model was built in PAM-STAMP to determine the IHTC values between a hot aluminium alloy 7075 blank and cold dies. The IHTC values were determined at different contact pressures under both dry and lubricated (Omega-35) conditions. In addition, a model to calculate the IHTC value at different contact pressures and area densities of lubricant was developed for the hot stamping process, which was proved to be working well with verification tests.