Microstructural modelling for friction stir welding of aluminium alloys

Predictive models have been developed to calculate the hardness profile and precipitate distribution after friction stir welding of aerospace aluminium alloys. A coupled modelling approach has been used, linking a thermal model to predict the thermal cycle to microstructure and property models. Two levels of modelling have been considered. The first is a semi-empirical approach that predicts hardness profiles. This simple model is demonstrated to correctly reproduce measured profiles in an example weld. The second model provides a detailed prediction of the precipitate evolution. Particle nucleation, growth, dissolution, and coarsening are all accounted for. Model predictions have been compared with experiments for the case of friction stir welded AA7449 thick plate.