Reducing the shear affected zone to improve the edge formability using a two-stage shear cutting simulation

Edge cracks are a well-known problem in the series production of vehicle body components. Various approaches were developed to predict the sensitivity of edge cracks and to improve the forming behavior of shear cut edges. The two-stage shear cutting process has become a popular method for reducing the edge crack sensitivity of steels and thus maximizing the formability of the shear cut edge. The application of this method with adapted shear cutting parameters has the advantage that the severely damaged shear affected zone is cut off in the second stage and the scrap is less stiff than in a normal shear cutting process. In the second stage only a small amount of deformation, and thus damage, is generated in the final component edge, as forming mainly occurs in the scrap. In this work a simulation model is presented and validated as well as the results of the numerical parameter analysis using the material HCT780X. The influence of the radius of the cutting line, the wear condition of the active elements of the shear cutting tool as well as the width of the cutting-offset on the resulting damage within the shear affected zone were investigated. It was found that using adapted two-stage shear cutting parameters lead to the formation of two separate shear zones and therefore can reduce the hardening of the shear affected zone by more than half.