A comparative study of microstructure and mechanical properties of conventional and synergistic double-sided FSW joints of 6061 zxaluminium alloy

In this study, synergistic double-sided friction stir welding (DS-FSW) is proposed to solve the problems of large deformation and the time-consuming of traditional DS-FSW. The microstructure, mechanical properties, and fracture paths of novel and conventional joints are studied under different welding parameters. Results show that defects in novel joints have been improved. However, the grain size in the stir zone of novel joints is larger than that of conventional joints. The microhardness map of the novel joint shows a more uniform distribution compared to that of the conventional joint. At a rotational speed of 1800 rpm and transverse speed of 1000 mm min⁻¹, the distortion of the novel joint and conventional joint is 0.1 and 1 mm, respectively. The tensile force of novel joints is higher than that of conventional joints for the same welding parameters. The maximum tensile force of novel and conventional joints is 36.8 and 34.9 kN, respectively.