Abstract: Friction Stir Welding (FSW) is a contact welding process that uses the heat generated by friction to fuse two different materials. The heat generated makes the metals attain plasticity and thus, fusion occurs which results in a joint. In the present study, welding of dissimilar aluminium alloys AA5052 with AA2024 and AA5052 with AA8090 has been done using Friction stir welding and the microstructure along with the mechanical properties of the welded joint are determined. An investigation has been done by varying FSW process parameters which include axial load, rotational speed of the spindle, and traverse speed of the weld, while keeping the tilt angle constant. Microstructures of the weld joints have been studied through SEM analysis. The weld joint between AA2024 and AA5052 welded at 710rpm has shown the highest tensile strength of 80.068 N/mm². Studies on microstructures revealed that the weld zone has better microstructure with uniform material distribution and negligible flaws were identified. The weld joint between AA5052 and AA8090 welded at 710rpm has the highest Brinell hardness of 32.7271 kgf/mm² compared to other joints. In a surface roughness check by tallysurf, the sample of AA2024+AA5052 welded at 710rpm has a smoother weld surface. Optimal results state that a higher order transformation model can improve durability and reliability of the given specimen.

Key words: Microstructure, Welding, Alloy, Hardness, Surface Roughness