Study of fracture damage criteria and influence of process parameters on punching of hot stamped ultra-high strength steel

Punching is an important process of the production for ultra-high-strength steel automobile components. By selecting the appropriate punching parameters, the punching quality can be effectively improved and the punching force can be reduced. In this study, several typical fracture damage models applicable to the punching process of high strength steel were compared, where the critical damage values were calculated through an iterative predictor–corrector approach. Meanwhile, the effects of punching parameters on maximum punching force (MPF) and punched face quality for hot stamped ultra-high strength steel Usibor1500P were investigated experimentally. The results show that the Oyane damage model is the most suitable one in simulating the punching process of Usibor1500P, which can better predict the punched profile features and the variation of punching force within one stroke. The increase in die clearance decreases the MPF, while the plate thickness, punch diameter and punch corner radius increase the MPF. The change of the punch corner radius has the most significant effect on the improvement of the punched face quality.