EFFECT OF APPLIED AXIAL FORCE ON FSW OF AA 6082 - T6 ALUMINIUM ALLOYS

Friction stir welding (FSW) offers nearly defect free welds with minimized distortion and fine grain structure. However, studies about the mechanism of metal joining and the effect of various process parameters for consistent and reliable results in FSW is yet to be concluded. Tool rotational speed, tool traversal speed, tool geometry, tool tilt and axial force are considered as the important process parameters for FSW. Many researchers report the effect of these parameters on weld quality and microstructural characterization. Nevertheless, the influence of the applied axial force on FSW process has not been elaborated considerably in these studies. Reported analytical and numerical analyses suggest that axial force has little effect on the weld characteristics as far as other parameters are fixed in a range, sufficient to produce good welds. The effect of the applied axial force on the weld quality and mechanical strength is elucidated in this study, in detail. Weld strength and microstructural features were examined and it was found that the applied axial force has considerable effect on the quality and strength of the welds generated. Experimental and analytical results suggested that there is an optimum value for the applied axial force to obtain defect free weld even for a FSW process carried out with other parameters selected in the range for good weld formation.