Experimental study of the defects, mechanical and microstructural characteristics of friction-stir-welded Al 6061 sheets

Abstract A promising solid-state welding technique, Friction Stir Welding- FSW- and its influence on microstructure and defects formation of the Al6061 welded plates and though consequence mechanical properties have formed the central part of the present study. The current research focuses on studying the effect of 3 crucial parameters of FSW, welding and rotating speed, and pin profile (each varying in 3 levels) on grains’ modification and the occurrence of flaws after nine designed trials with the help of the Taguchi method. Vickers micro-hardness and tensile tests were conducted to determine how the grain formation and defects affected mechanical properties. It was observed that all three central regions of the welded pieces, NZ, TMAZ, and HAZ, have experienced grain modification, plastic deformation, and defect formation with different severity. The distance of the region from the weld line, welding and rotating speeds, and ratios were affecting the severity of changes. According to the obtained results, HAZ showed less strength than others since all samples’ failure occurred in this zone. Higher values of hardness and tensile strength for each pin profile resulted from higher welding speeds and lower rotational ones.