Numerical modelling and physical simulation of the softening behaviour of hot work tool steels during thermal fatigue

Abstract
Fatigue due to thermal cycling is one of the main reasons for the damage of tools used in die casting processes. In order to investigate the thermal fatigue behaviour of tool steels a thermal fatigue testing facility was designed and built up. For better understanding of the mechanisms of thermal fatigue finite element-simulations were carried out. To specify the cyclic material behaviour push-pull-tests at different temperatures were performed. The Chaboche-model was used to describe the kinematic material response. Isotropic softening is also taken into account. Depending on the arising accumulated plastic strain stable cyclic deformation or continuous softening occurs. The results are consistent with the accomplished thermal fatigue tests on different hot work tool steels.