Metallurgical Investigation of Under Water Friction Stir Welding (UWFSW) Process

Underwater friction stir welding (FSW) has been demonstrated to be an effective method to improve the mechanical properties of joints. To illuminate the characteristics of underwater FSW, the microstructural evolution and its effect on mechanical performance of an underwater joint were investigated in the present paper. This work compared the parameters of friction stir welding (FSW) and under water friction welding (UWFSW) on the weld joint .In this investigating Friction stir welding (FSW) used in under water environment, for this Operations research pin covered and shielded from contact water by hollow shaft spin (HSS), the HSS controlled the heat conduction of pin and disconnect with water, applying for the first time a novel under water FSW technique developed at marine structures.The novel technique acceptance given by the experimental setup on Al X۴۰۰۰ series, for studied the mechanical and metallographic exams. The metallographic exams indicate that weld nugget grain size has been decreased. The mechanical testing illustrated hardness and tensile strength have been increased, on the other hand the percentage of elongation and impact energy have been decreased.