Influences of pin profile and rotational speed of the tool on the formation of friction stir processing zone in AA2219 aluminium alloy

AA2219 aluminium alloy has gathered wide acceptance in the fabrication of light weight structures requiring a high strength-to-weight ratio. Compared to the many fusion welding processes that are routinely used for joining structural aluminium alloys, friction stir welding (FSW) process is an emerging solid state joining process in which the material that is being welded does not melt and recast. The welding parameters and tool pin profile play a major role in deciding the weld quality. In this investigation an attempt has been made to understand the influences of rotational speed and pin profile of the tool on friction stir processed (FSP) zone formation in AA2219 aluminium alloy. Five different tool pin profiles (straight cylindrical, tapered cylindrical, threaded cylindrical, triangular and square) have been used to fabricate the joints at three different tool rotational speeds. The formation of FSP zone has been analysed macroscopically. Tensile properties of the joints have been evaluated and correlated with the FSP zone formation. From this investigation it is found that the square tool pin profile produces mechanically sound and metallurgically defect free welds compared to other tool pin profiles.