Influence of Friction Stir Welding Parameters on Dissimilar Joints AA6061-T6 and AA5052-H32

In this present study, two dissimilar aluminum alloys of AA5052-H32 and AA6061-T6 were joined in butt joint configuration to examine the influence of process parameter on tensile strength and microstructural examination. Tool profiles such as square, cylinder, triangle with welding speeds like 30, 60, 80 mm/min and tool rotational speeds such as 800, 950, 1100 rpm were selected as process parameters for friction stir welding. Among the various tool profiles, square pin profile produced good pulsating action of 60 pulses and having max SV/DV ratio of 2.3 which helped to produce higher tensile strength. Microstructural examination on the nugget zone revealed that higher welding speed causes some cracks in the nugget zone due to insufficient stirring of the materials. Microhardness examination reveals that HAZ of both zones exhibited lower hardness on both sides. Nugget zone at centre was measured with increased hardness than BM of AA5052 and lower than AA6061. SEM fractography revealed that the specimens were failed in ductile mode and specimens failed at higher tensile strength observed with high ductility. Taguchi optimization technique has been implemented and the process parameters combination was optimized for higher tensile strength. The dissimilar joints fabricated at optimized process parameters produced maximum tensile strength of 181 MPa are as follows: Tool Profile—Square, Tool-Rotational Speed—1100 rpm and Welding speed—60 mm/min.