Effect of trailing heat sink on residual stresses and welding distortion in friction stir welding Al sheets

Abstract

This paper investigates a trailing heat sink, which was designed and applied to friction stir welding (FSW) in order to control the residual stresses and welding distortion. Residual stresses, residual plastic strains and welding distortion of 2024-T3 and 5083-H321 Al sheets welded by FSW with and without the trailing heat sink were compared. The optimal placement of the heat sink was discussed. The results revealed that the reductions in peak tensile stresses were 66% for 2024-T3 and 58% for 5083-H321 by application of the trailing heat sink in FSW. In addition, the welding distortion could be reduced drastically by this method. The 5083-H321 sheet with a size of 1000×100×3·5 mm welded by this method was very flat and had almost no distortion. This method achieved in-process control of stresses and welding distortion, without additional complicated work before or after welding operation.