Microstructure and Mechanical Properties of Dissimilar Joints of Al-Mg2Si and 5052 Aluminum Alloy by Friction Stir Welding
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Al-Mg2Si alloy and 5052 Al alloy were welded successfully by friction stir welding (FSW) in this study. The results show that the alloy consists of three distinct zones after FSW: the base material zone (BMZ), the transitional zone, and the weld nugget (WN). The morphologies of the primary Mg2Si phases are identified as coarse equiaxed crystals for Al-Mg2Si alloys in the BMZ. The WN is a mixture of rich Al-Mg2Si and rich 5052 alloy, and a banded structure is formed in the zone. Interestingly, in the WN, the equiaxed crystals changed to polygonal particles with substantially reduced sizes in the rich Al-Mg2Si zone. However, in addition to the white rich Mg phase appearing in the rich 5052 zone near the interface, the 5052 alloy does not show obvious changes. The hardness gradually increases from the BMZ of the 5052 to the welded joint to the Al-Mg2Si BMZ. In addition, the ultimate tensile strength (UTS) of the welded joint is higher than that of the base material of the Al-Mg2Si, whereas it is lower than that of the 5052 base alloy. The results of the elongation are similar to the UTS results. The fracture mechanism is also investigated.
Keywordsfriction stir welding dissimilar weld microstructure mechanical properties
This work was supported by the National Natural Science Foundation of China ; the Program for the Distinguished Young Scientific Talents of Guizhou [Qian Ke He Platform and talent (2017) 5633]; the New Process Engineering Research Center of Process industry, Guizhou Province [Qian Jiao He KY(2017) 021]; the Key Laboratory of Light Metal Materials Processing of Guizhou Province [Qian Ke He Platform and talent (2016) 5104]; and the Scientific &Technological Innovation Talent Team of Guizhou Province [Qian Ke He Talent Team (2015) 4008].