TWI

A softening model was constructed for friction stir welding (FSW) of 2xxx series aluminium alloys and was combined with previously derived thermal cycle modelling work. A thermal model of energy input and heat conduction was used to calculate thermal history data for different points in the workpiece plate (e.g. 2014-T6 aluminium alloy of thickness 6.5 mm). Modelling of microstructure involved the effect of thermal cycles on the workpiece material and the hardness distribution in the weld (resulting from dissolution and reprecipitation). The combined model predicts the shape and extent of loss of hardness (softening) across the weld HAZ, and may find application in predicting the limiting welding speed in a given alloy. Comparisons were made between theoretical predictions and experimental data.

1st International Symposium, 14-16 Jun 1999, Session 08: Modelling 2, Paper 03