Phase transformation and blanking accuracy of boron steel B1500HS during hot blanking

To investigate the microstructure transformation and the change of the dimensional accuracy of the hot blanking parts, the hot blanking experiments for B1500HS steel were performed with different temperatures and die clearance ratios. The effects of blanking temperature on the phase transformation and mechanical properties of steel were analyzed using the cooling curves. The effects of blanking temperature and die clearance ratio on the dimensional accuracy of the hot blanking parts were analyzed based on the measured diameter of the parts. The fracture morphology of the parts was observed, and the effect of blanking temperature on the fracture quality was analyzed. The results show that, with decreasing die clearance ratio, the diameter of the blanking parts increases at the same blanking temperature. When the die clearance ratio remains constant with decreasing blanking temperature, the dimension deviation of the parts has a fluctuation tendency of "positive growth-negative growth-positive growth". The blanking parts have a higher accuracy as the blanking temperature is in the range of 600-650℃ or 750-800℃. While increasing the blanking temperature, the micro-hardness of the parts increases. The microstructure of the parts is full martensite and the micro-hardness is about HV 550 as the blanking temperature is in the range of 650-800℃. Furthermore, increasing the blanking temperature, the width of burnish zone increases.