Improved hot-stamping analysis of tubular boron steel with direct measurement of heat convection coefficient

There are two types of hot-stamping processes, direct and indirect, depending on the sequence of the heating, forming, and quenching steps and the method used for each step. In this study, an indirect hot-stamping process consisting of forming at room temperature, heating, and water quenching was applied to develop a coupled torsion beam axle. The analysis results indicated that the application of the heat convection coefficient is critical in the simulations and must take into account the temperature and specific location in the model to ensure the accuracy of the heating and quenching analysis. The heat convection coefficients used in the analysis were directly measured at various positions of the tube (e.g., outside, inside, and bending region) using thermocouples, and the final values were determined through correlation between the actual tests and numerical analysis. The experimental and simulated final deformed shape and temperature distribution were in good agreement.