A microstructure and flow stress model for cell forming metals, 3IVM (3 internal variables model), was developed in which the work hardening and softening effects due to interaction of dislocation densities were taken into account. This model had been applied in through process modelling of sheet production. In the present paper, improvements to the model were introduced. In the new model, the softening effect of recovery by cross-slip and by additional dislocation reactions were considered in addition to that of climb. Moreover an improved kinetic equation of state was 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 showed that the new model could 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 was unchanged, its applicability for through process modelling was not compromised.

Validation of an Improved Dislocation Density Based Flow Stress Model for Al-Alloys. V.Mohles, X.Li, C.Heering, G.Hirt, S.Bhaumik, G.Gottstein: International Journal of Material Forming, 2008, 1[1], 77-80