Influence of process parameters on residual stresses in dissimilar friction stir welding of Aluminum alloys

Abstract

Foreseeing how welded structures will behave requires careful consideration of the residual stresses that the friction stir welding (FSW) process introduces. These residual stresses can cause severe deformation and compromise the ability of friction stir welded structures to bear imposed external loads. This work uses a Sequentially Coupled Thermo-mechanical finite element simulation to quantitatively evaluate the influence of such residual stresses coming from the FSW process. This modelling method examines the thermal and post-weld stress distributions during the friction stir welding of dissimilar AA2024-T3 and AA5086-O alloys. The procedure entails an initial thermal analysis followed by a mechanical analysis to determine the distribution of residual stresses across the entire dissimilarly welded alloys. The study examined how alterations in FSW operational parameters, such as rotational and translational speeds, influence both the thermal conditions and residual stress distribution. The findings highlighted that both temperature and residual stress exhibited higher values on the retreating side of the specimen compared to the intended advancing side. As the tool rotational speed rose, the magnitude of longitudinal residual stress dropped, however it showed an increase with greater tool translational speeds. Moreover, the simulated outcomes demonstrate the substantial impact of welding fixtures on the profiles and magnitudes of residual stresses.