Influence of fabrication stresses on fatigue life of friction stir welded aluminium profiles

Influence of clamping and welding procedure on fatigue life of a friction stir (FS) welded aluminium profile has been analysed. Two series of aluminium profiles (series A and B) have been fatigue tested. The different clamping conditions in series A and B gave rise to different failure positions that could not be explained neither by the effective notch stress method, nor by the critical distance methods. The clamping in series A introduced plastic deformation at the weld notch that gave rise to tensile residual stresses. The failure position could be explained from the value of the stress intensity factor provided that the residual stresses were considered.