Fracture assessment in dual phase and transformation-induced plasticity steels during 3-point bending

Abstract

The goal of this study was to examine the fracture behavior of advanced high strength steel (AHSS) sheets in bending. For this purpose, 3-point bending (3 PB) tests were conducted on DP980 and TRIP1180 sheet samples. The test specimens were prepared in different orientations with respect to the rolling direction of the sheets. The onset of fracture and fracture strains were determined through digital image correlation technique. The fracture regions of the deformed specimens were observed at different magnifications to understand the crack initiation mechanism. Apart from fracture characterization, a finite element study was performed for both steels using an Abaqus/Explicit solver. The parameters required for the constitutive equations were obtained based on mechanical characterizations carried out on these sheets in a previous work. Finally, an uncoupled fracture model was adopted to predict the fracture location and onset of cracking during the 3 PB test. The predicted results were found in reasonable agreement with the experimental data when the fracture model was calibrated using an appropriate set of mechanical tests.