Mechanical Bending Property of Ultra-High Strength Steel Sheets IN Roll Forming Process

摘要

Ultra-high strength steel (UHSS) plays an important role in the automotive lightweight industry owing to its insubstantial weight and high specific strength. Roll forming is one of the effective forming processes for UHSS in the steel industry. In this study, the minimum bending radius is determined by roll forming experiments, taking into account the 1200MPa level of the V-profiled parts of UHSS. The ductile fracture criterion (DFC), which considers both the tensile ductile fracture and shear ductile fracture, is applied to predict the fracture of sheets in the roll forming process, where bending is the main deformation mode. A set of rolls is designed to investigate the fracture behavior in the roll forming process. In addition, finite element models (FEMs) are built and four sets of experiments are conducted to calibrate the fracture of the V-profiled parts for R/T = 1, 2, 3, and 4. Furthermore, the fracture time and fracture location of the V-profiled parts for R/T = 1 and 2 are predicted and the prediction results agree with the experimental results.