Abstract:An extensive investigation was carried out on the retractable friction stir welding of 2219 aluminium
alloy with the thickness of 8 mm, and the retractable track, microstructure and mechanical properties of the welding
joint at the different locations have been analyzed. The results indicated that the actual trajectory of the RPT is the
combination of welding speeed and retracting speed, and showed a linear relationship. The morphology at the beginning
and end of the retractable FSW welded seam showed a typical conventional FSW microstructure, while the joint
located in the middle of the retractable FSW welded seam can be considered as the composite of a 100% penetration
welded joint and a joint with gradually shallower depth. The results of the tensile test indicated that the mechanical
property of the joint at the end of weld seam is the highest, followed by the joint loacated at the beginning and middle
of the retractable FSW welded seam. With the retracting distance increasing gradually, the performance of the joint in
the middle of the retractable FSW welded seam also gradually increased. The fracture mechanism of the joint at different
position is all ductile fracture.
