Numerical simulation of hot blanking for boron steel B1500HS based on ductile fracture criterion

The distribution and evolution of stress-strain in the sheared zone at elevated temperature is an important theoretical basis for studying the hot blanking mechanism. The fracture criterions and fracture thresholds are the main factors affecting the accuracy of numerical simulation for the hot blanking. To research the mechanism of hot blanking, B1500HS steel sheet with full austenitization was blanked at the different temperatures (650, 700, 750, and 800 A degrees C). Finite element model of hot blanking was established, and five fracture criterions (normalized Cockroft and Latham, Brozzo, Freudenthal, Oyane, and Rice and Traccy) were used to simulate the hot blanking of B1500HS steel. According to the results of numerical simulation and experiment, the fracture thresholds of five fracture criterions were evaluated using the method of "regression fitting-calculation-prediction-correction." The fracture thresholds attained by this method were used to simulate the hot blanking, and the location where crack occur initially and fracture shape was obtained. Comparing the simulation results and the experimental results, the results show that the crack occurs at the edges of die and punch as the hydrostatic stress reaches to the maximum value, and the simulation results based on the Oyane fracture criterion and Brozzo fracture criterion are well consistent with the experiment results. The fracture thresholds attained by the method of "regression fitting-calculation-prediction-correction" have the better reliability and practicability.