Effect of tool probe geometry on the material flow and mechanical behaviour of dissimilar AA2024/AA7075 friction stir welded joints

This work focused on improving the weld quality and productivity of dissimilar friction stir welding of AA 7075-T6 and AA 2024-T3 aluminium alloys by controlling the process parameters of tool axial force, welding speed, tool offset, and rotational speed. A newly developed hybrid pentagonal tool is used for the fabrication of welds to enhance productivity. In this study, an RSM based on a central composite method is used for the design of experiments, optimisation, and data analysis. The result found that the ideal range of welding process parameters for 6-mm-thick AA7075-T6 and AA2024-T3 aluminium alloys by friction stir welding is to use a tool spindle rotational speed of 1178.51 rpm, an axial load of 7.78 KN, a traverse speed of 132.74 mm/min, and 0.958 mm tool offset towards the AA2024-T3 material side. Based on the UTS, a joint efficiency of 67.19% is achieved. It is observed that while increasing the value of FSW parameters like tool spindle rotational speed and traverse speed, the tensile strength and elongation values tend to increase drastically after further increasing those parameters, UTS and TE seem to decrease.