Effect of friction stir welding tool on temperature, applied forces and weld quality

In friction stir welding (FSW), a proper selection of the FSW tool is an important factor which, as an appropriate tool, cannot only improve the quality of the weld but also diminish the destructive effects including applied forces and high temperature induced during the welding process. This research is aimed to scrutinise the effect of the tool geometries on the axial and translational forces, temperature and mechanical properties for AA7075-T6 are investigated. The threaded tapered, non-threaded triangular and non-threaded cylindrical pins were employed. It was observed that the tool shoulder diameter was directly correlated with the generated temperature, axial and translational forces and weld characteristics. Moreover, the lowest amounts of measured forces were recorded in the case of threaded tapered pin whereas the generated temperature, UTS, elongation and grain size were higher for this pin as compared with the other pins. Nevertheless, in the tapered pin, hardness is lower than that of the other pins. It was also shown that the created fluctuations during the FSW process and stabilising time were lower for the threated tapered pin compared with the other two pins.