On the interaction of ductile damage and materials softening of a Ni-base alloy during hot deformation

Abstract

Abstract Macro- and micromechanically motivated damage models have been validated in the critical temperature range of 900 °C – 1000 °C with respect to their applicability and precision in fracture prediction using a commercial finite element code and by the means of an experimental database. The evaluation of the experimental and the calculated fracture strains corresponding to an averaged critical damage value shows major deviation for all models except the model of effective stresses based on the work of Lemaitre. The results have been improved further for 1000 °C either by using a microstructure model to consider dynamic recrystallization or the coupling of the flow stress and the damage parameter calculation. Electron backscatter diffraction analysis showed that cracks always started at grain boundaries but with the onset of dynamic recrystallization at higher temperatures crack growth also seems to take place within recrystallized grains.