Mechanical and Microstructural Properties of Dissimilar Friction Stir Welded Joints: Aluminum AA 6061 and AA 5052

This study focuses on optimizing Friction Stir Welding (FSW) parameters, including rotational speed, feed rate, and tool geometry, for joining dissimilar aluminum alloys (AA 5052 and AA 6061). Experiments were conducted using cylindrical, triangular, and threaded pin tools with rotational speeds of 1300, 1950, and 2850 rpm and feed rates of 43, 130, and 240 mm/min. Mechanical testing (tensile strength, hardness, and bending strength) and microstructural analysis were performed to evaluate weld quality. The optimal parameters were identified at a rotational speed of 1300 rpm and a feed rate of 130 mm/min using the threaded tool, resulting in a tensile strength of 123.51 MPa, a hardness of 41.543 HB, and bending strength of 106.713 N/mm2. Microstructural observations revealed fine equiaxed grains in the Nugget Zone (NZ) under optimal conditions, enhancing mechanical properties, while grain coarsening in the Heat Affected Zone at higher speeds weakened the joint. The optimization graph provided a practical guide for parameter selection. This study offers valuable insights into FSW parameter optimization, contributing to improved weld quality in applications such as aerospace and automotive industries, where high-strength, lightweight joints are essential.