Experimental Study of Defects and Mechanical Properties During Under-Water Friction Stir Welding of Al6061-6063 Alloys

Abstract

In this study, welding samples were attributed with reduced welding defects such as a tunnel, onion ring, exit pinhole, surface flash and micro-voids with improved mechanical strength through underwater friction stir welding. Two dissimilar aluminum alloys with different mechanical properties were successfully joined by using direct application of groundwater during friction stir welding. Taguchi method was used to design the experimental runs and identify optimal process parameters setting. After the welding process, the samples were cut into the desired size as required for tensile test and hardness test. Scanning electron microscopy was used to understand grain behavior at weld nugget zone after the tensile test. Fewer defects as well as improved mechanical strength with minimum spindle speed i.e.1000 rpm and welding speed 16 & 20 mm/min were observed. Minimum spindle speed leads to reduce power consumption. Fine equiaxed grains were also observed.