Dynamic recrystallization-dependent damage modeling during hot forming

Abstract

Hot forming processes are extensively used to produce semi-finished and finished components. At elevated temperatures, dynamic recovery and recrystallization processes occur that enable large shape changes at low forming forces. In steel, non-metallic inclusions cannot be avoided during metallurgical processes. They may induce damage in the same way as at room temperature, but the softening of the matrix due to dynamic recrystallization may be used to control the initiation and progression of damage. Damage models do not take into account that dynamic recrystallization reduces the local stresses at the interface of matrix–inclusion. The purpose of the presented study is to analyze the interaction between dynamic recrystallization and damage initiation. Using representative volume elements, the influence of dynamic recrystallization on damage initiation is studied at different temperatures, strain rates, and stress states. Based on this study, a damage model is devised that couples dynamic recrystallization and damage on the macro level and hence can be used in macroscopic process simulations.