Plasticity and fracture behavior of high-strength steel sheets at low temperatures

The plasticity and fracture properties of two different types of high-strength steel sheets have been thoroughly investigated by integrating experimental characterization and numerical simulation. Quasi-static tensile tests on flat specimens with various notch configurations, characterized by distinct stress states in the critical region, were performed at several different temperatures. Enormous plastic deformation occurred under certain cryogenic loading conditions. Detailed fractography analysis revealed the combined effects of stress state and temperature on the damage mechanisms of high-strength steels. A continuum mechanics based fracture model was developed to reproduce the observed temperature and stress state dependent plasticity and fracture phenomena using the finite element method. Both the global fracture displacements and local failure mechanisms can be well captured by the proposed failure criterion, which can be potentially applied to describe the failure behavior of other sheet materials.