Study of microstructure and mechanical property of mismatched 2A12 friction stir weld

Abstract A study was conducted on homogenous FSW joints of twin Aluminum alloy plates 2A12-T4 and 2A12-O respectively, using a sequence of microscopic and mechanical tests. The results of sustained properties testing revealed that both joints exhibit two distinct material behaviors with respect to the FSW joining technique, as well as tangential properties. The Vickers Hardness distribution graph was plotted by means of a Vickers hardness indenter, using HV values obtained individually from both joints throughout the cross-sectional area. The graph showed different fluctuations, with the T4-joints experiencing a rough 20% base property derivation in mechanical testing, while the O-joints underwent a significant enhancement of over 50%. These initial findings suggest that each mechanical property experiment may potentially reveal an equivalency in properties mismatch from base to joints on each joint. In addition to the mechanical tests, OM and metallographic analysis showed that FSW leads to recrystallization and refinement of grain morphology. Both joints exhibited fine recrystallized equiaxed grains, which were deformed into much smaller sizes, particularly in the nugget zone. Notably, the O-joints showed an onion-ring pattern that was clearly observed. Overall, this study provides valuable insights into the behavior of FSW joints in aluminum alloy plates, highlighting the impact of FSW on mechanical properties and grain morphology. The findings may have significant implications for the development of more efficient and effective welding techniques in the future.