Abstract: Surface heat transfer coefficient is one of the most important boundary parameters in the hot stamping of boron steel, the accuracy of this parameter has an obvious effect on the simulation result of temperature, phase transformation, stress/strain and so on. In order to research the boundary pressure, which is the main factor affecting surface heat transfer coefficient, a testing device is designed according to the characteristic of heat transfer between boron steel and die in the hot stamping. In the process of testing, CMT5000 tensile testing machine is used to put a pressure on the boron sample and testing device, a high speed data acquisition system is used to record the cooling curves of boron sample when the pressure is 0 MPa, 1 MPa, 10 MPa, 20 MPa and 40 MPa. The self-developed software of inverse heat conduction is used to analyze the temperature variation and evaluate the surface heat transfer coefficient between the boron sample and testing device. The effect of boundary pressure on the surface heat transfer coefficient is attained, and the research results show that, the surface temperatures of boron steel and testing device have little effect on the surface heat transfer coefficient. The oxidation of boron steel has a remarkable effect on the surface heat transfer coefficient. The surface heat transfer coefficient increases with the rise of boundary pressure, and the relationship is approximately linear.

Key words: Heat conduction, Heat transfer coefficient, Hot stamping, Inverse problems