Microstructural features and mechanical properties of AM60 and AZ31 friction stir spot welds

Friction Stir Spot Welding: A Review on Joint Macro- and Microstructure, Property, and Process Modelling

“…Recrystallization was not observed in TMAZ of AA7075 refill FSSW due to insufficient deformation strain [28]. The heating rate of FSSW was rapid, which limited the dissolution of secondphase particle in TMAZ [34]. Hence Yin et al [34] observed -Mg grains for AZ31 weld.…”

Lap shear strength and fatigue life of friction stir spot welded AZ31 magnesium and 5754 aluminum alloys

“…Mallick and Agarwal [30] evaluated the fatigue performance of FSS welds made of AM60 and AA5754 alloys but the failure mechanisms were not studied in detail. FSS welds of dissimilar Al and Mg alloys were observed to exhibit different failure modes compared with those with identical alloys for both top and bottom sheets [18,25,31]. However, the integrity and durability issues of similar Mg and Al welds and dissimilar Al-to-Mg welds especially under cyclic loading have not been systematically studied, and no fatigue behavior for such FSS welds in relation to the change in the failure mode has been reported in the open literature.…”

Influence of tool thread on mechanical properties of dissimilar Al alloy friction stir spot welds

“…Similar failure loads were found in joints made using threaded and half threaded tools with higher tool rotational speed settings (2250 and 3000 rev min 21 ). In contrast, the failure loads of joints made using the half threaded tool were lower (by y1?0 kN) in joints made using a rotational speed of 1000 rev min 21 . Figure 4 shows the microstructural features of Al 5754/Al 6111 friction stir spot welds made using the threaded and half thread tools having the highest failure load.…”

“…The curvature values also increased almost linearly in the joints made using the threaded and half thread tool with increasing tool rotational speed. The angles of curvature of the hook regions increased from 133 to 170u in joints made using the threaded tool as the tool rotational speed increased from 1000 to 3000 rev min 21 . Similarly, the angles of curvature of the hook regions increased from y124 to y153u in joints made using the half thread tool when rotational speeds increased.…”

“…In Al 5754/Al 6111 friction stir spot welds made using the threaded tool with a lower tool rotational speed setting, though the failure loads were higher, the stir zone widths produced (promotion of larger stir zone widths being the main role of the thread) were still small. It follows that the bonded conditions were exceptional in the joints made using the threaded tool with a tool rotational speed of 1500 rev min 21 . In Al 5754/Al 6111 friction stir spot welds, the stir zone widths of the joints made using the half thread tool always decreased compared with the joints made using the threaded tool.…”