Numerical and experimental investigations on mechanical trimming process for hot stamped ultra-high strength parts

In this paper, the mechanical trimming process for hot stamped ultra-high strength parts was studied, in which the properties of fracture profile were analyzed and the effects of process parameters were evaluated. The research was carried out by FEM simulation with comparison and chosen of damage models, where the critical damage values were obtained through an iterative “predictor-corrector approach”. In addition, an experimental trimming tool was designed to study the effects of variable process parameters and verify the simulation results. By comparison, it was found that the Oyane damage model agreed with the experimental results better than others. The simulation and experimental results showed that the quality of trimmed hot stamped surface was poor with not straight profile and small burnish zone, but it can be improved by choosing proper trimming angle and blade radius. Such phenomena were discussed and explained in terms of stress state. Tensile stress accelerates the damage value while compress stress inhibits it. This paper helps to better understand the mechanical properties of hot stamped ultra-high strength steel.