Model for grain evolution during friction stir welding of aluminium alloys

Abstract

A simple model for recrystallisation and grain growth in the nugget of friction stir welds has been developed on the basis that the dominant recrystallisation mechanism is geometric dynamic recrystallisation. In combination with a process model capable of predicting the strain, strain rate and temperature history of any region within the weld, the current model can predict the grain size after friction stir welding. The model has been tested against experimental data in the literature for a friction stir welding in AA2524 and found to give a reasonable prediction of the final nugget grain size without arbitrary fitting. The model has then been used to predict the influence of dispersoid particles and the effect of cooling rate behind the tool on the grain size evolution in the nugget.