Investigations of fracture on DP980 steel sheet in roll forming process

Advanced high strength steel (AHSS), especially dual phase steel, is widely used on modern automobiles to achieve high strength-to-weight ratios. Roll forming is one of the most widely used forming processes in the steel industry. In this study, roll forming process, where bending is the main deformation mode, is adopted to investigate the fracture mechanism. A set of rollers is designed to investigate the fracture mechanism on roll formed part. The fracture behavior is studied during roll forming processes. Microstructure observation and macro mechanics analysis with FEM simulation are adopted to investigate the fracture mechanism. The analysis of stress triaxiality and Lode angle parameter from FEM simulation results meets the results of microstructure observation. In the end, the Oyane fracture is calibrated with two basic tests. Then the fracture behavior of roll forming process is predicted and analyzed with the Oyane fracture criterion in FEM simulations.