Modelling of heterogeneous precipitate distribution evolution during friction stir welding process

A numerical model based on the Kampmann and Wagner method is developed to predict the evolution of precipitate distribution during friction stir welding (FSW). The model has been applied to FSW of AA7449, an aerospace aluminium alloy. It considers both metastable and equilibrium precipitate phases and the transition between them. It also predicts the evolution of grain boundary precipitates and their effect on the precipitate free zone size. The model has been calibrated against results from isothermal and quench experiments. Subsequent predictions for welds show good qualitative agreement between the model and observation. The model has also been used to explore the effect of different FSW parameters on the predicted precipitate evolution.