Effects of dynamic grain boundary migration during the hot compression of high stacking fault energy metals

Abstract A simple one-dimensional model is proposed for predicting the effects of grain boundary migration (GBM) occurring during hot compression testing of polycrystalline specimens. Strain hardening, dynamic recovery, and GBM induced softening are accounted for using a modified Laasraoui–Jonas equation. The movement of grain boundaries has two origins, viz. convection driven by material flow, and migration induced by the local dislocation density differences. The disappearance of grains during straining leads to changes in the local topology. Using parameters pertaining to aluminium, it is shown that the average grain thickness tends to a steady state value, while significant flow stress softening occurs, both predictions in agreement with experimental data. Moreover, the model allows the true average migration rate to be simply estimated from grain thickness evolution.