Mechanical properties optimization of friction stir welded lap joints in aluminium alloy

This work focuses on the influence of the rotational and travel speed on the strength of AA 2024 T3 friction stir welded lap joints. Tensile tests were carried out on mini-specimens extracted from different welding zones. A central composite design was applied to identify the relative importance of the variable factors’ effects and their interaction on yield/ultimate strength and elongation for both heat affected zone (HAZ) and nugget zone. Surface methods and gradient algorithms were used to optimize the yield strength of the joints. Shear and micro hardness tests were executed to achieve a more complete mechanical characterization.