Effect of Processing Parameters on Microstructure and Mechanical Properties of Friction Stir Welded 6061 Aluminium Alloy Joints

Abstract

In this research, friction stir welding was successfully conducted on 6 mm thick Al6061 plates, employing rotation speeds of 1200, 1400, and 1600 rpm, along with a constant traverse speed of 66 mm/min. Microstructural analyses of welded joints were performed using optical and scanning electron microscopy techniques. Notably, joints fabricated at a welding speed of 1600 rpm exhibited superior tensile properties. A discernible transformation occurred in the microstructure, wherein coarse grains within the parent material underwent a morphological change, transitioning into fine equiaxed recrystallized grains specifically within the nugget zone. Hardness assessments revealed that the hardness values of the nugget zones in all welded joints surpassed those of the parent material, with the lowest recorded hardness values observed in the heat-affected zone (HAZ). This observed microstructural refinement and hardness variation signify the successful alteration of material properties, particularly within the nugget zone, as a consequence of the FSW process.