Thermo-Mechanical Modelling and Experimental Characterisation of Residual Stress Development in Dissimilar AA5052-H32/AA6061-T6 Friction Stir Welds

This study investigates residual stress development during friction stir welding of dissimilar AA5052-H32 and AA6061-T6 aluminium alloys using a combined thermo-mechanical modelling and neutron diffraction approach. A finite element model was developed in COMSOL Multiphysics to predict the transient temperature field and residual stress evolution. The predicted thermal histories agreed with thermocouple measurements within 10%, and the residual stress predictions were validated against neutron diffraction measurements. The model reproduced the longitudinal residual stress profile with peak differences within 30 MPa. The stress profiles showed similar overall trends under different welding parameters, but the peak magnitude, peak location, and width of the tensile stress region were strongly affected by heat input. Higher heat input broadened tensile residual stress region, while lower heat generation generally reduced peak stresses. The asymmetric longitudinal stress profile peaked on the AA5052-H32 side, 10-12 mm from the weld centreline, within the heat affected zone. The multi-peak stress profile reflected the combined effects of dissimilar material properties, local softening, and non-uniform thermal exposure. These results demonstrate the capability of the validated model to support residual stress prediction in dissimilar aluminium FSW joints.