2012 Volume 30 Issue 2 Pages 107-115
Friction stir spot welding of dissimilar aluminium alloys using the three-flat tool is carried out in order to investigate the effects of probe geometry on mechanical properties. The failure loads in A5754/A6111 lap joints made using a three-flat 0.5 mm no-thread tool were always higher than the joints made using a three-flat 0.5 mm threaded tool. Material flows due to the shear deformations were observed in the stir zone of A5754/A6111 and A5052/A6061 lap joints made using the three-flat tools. In addition, the bonded and stir zone widths in A5052/A6061 lap joints made using a three-flat 0.7 mm no-thread tool (in which the arc lengths of the triangular vertex region in the cross-section of probe were shortened) were always smaller than the joints made using a three-flat 0.5 mm no-thread tool. Therefore, it is suggested that there are pressures in a horizontal direction which are produced by the triangular vertex regions on the probe.
