Parametric study of friction stir welding induced distortion in thin aluminium alloy plates: A coupled numerical and experimental analysis

Welding distortion and residual stresses in Friction Stir Welding (FSW) of thin AA5754-H22 aluminium plates were analysed. An experimental work was conducted concerning the influence of plates' dimensions, process parameters and welding procedures on friction stir welding induced distortion. Plates' distortion was evaluated using Digital Image Correlation (DIC). The experimental work was complemented by a fully coupled thermomechanical Finite Element Analysis (FEA). The numerical results enabled to correlate the distortion modes observed experimentally with the residual stresses distribution in the welds. It was observed that both the distortion magnitude and mode, as well as the longitudinal residual stresses, are strongly influenced by plates width and thickness. Nor the realising sequence, nor the cooling time after welding, have a strong influence on plates' distortion and residual stresses. The numerical results also indicate that using ultra high welding speeds enables to suppress distortion in thin plates welding.