Validation of an improved dislocation density based flow stress model for Al-alloys

Abstract

A microstructure and flow stress model for cell forming metals, 3IVM (3 Internal Variables Model), was developed [1], in which the work hardening and softening effects due to interaction of dislocation densities are taken into account. This model had been applied in through process modelling of sheet production. In the present paper, improvements of 3IVM are introduced. In the new model (3IVM+) the softening effect of recovery by cross slip and by additional dislocation reactions are considered in addition to that of climb. Moreover an improved kinetic equation of state is utilized. For validation, compression tests on a commercial Al-alloy were carried out and the flow curves were determined. The comparison between model predictions and experimental results shows that 3IVM+ can replicate the flow curves much better than the previous model, in particular at low temperatures and in wide temperature range. Since the concept of the model is unchanged, its applicability for through process modelling is not compromised.