Xie Liangwen, Zhu Xianyong, Fan Yuexiang, Sun Weijia, Wang Peng, Jiang Cheng, Xiao Xiong, Yang Song, Song Yulai
School of Mechanical and Aerospace Engineering, Jilin University, Changchun 130022, China.
Chongqing Research Institute, Jilin University, Chongqing 401123, China.
Materials (Basel). 2021 Dec 21;15(1):23. doi: 10.3390/ma15010023.
In order to clarify the microstructural evolution and the mechanical property of dissimilar friction stir-welded joints of ZK60 and Mg-4.6Al-1.2Sn-0.7Zn magnesium alloys, two types of arrangement with ZK60 at advancing side (AS) or retreating side (RS) were adopted. The macrostructure and the microstructure of the dissimilar welded joints were discussed, and the microhardness and the transverse tensile properties of the joints were measured. There are three stirring sub-zones with different compositions and two clear interfaces within the joints. Due to the effect of both the original grain size of base materials and the growth of recrystallized grains, in the stir zone (SZ), the grain size of ZK60 increased slightly, while the grain size of Mg-4.6Al-1.2Sn-0.7Zn decreased significantly. The dissolution of precipitates was gradually significant from RS to AS within the SZ due to the gradual increase in strain and heat. The grain refinement led to an increase in hardness, while the dissolution of precipitates resulted in a decrease in hardness. The performance of the joints obtained with ZK60 placed on the RS is slightly better than that of that on the AS. The tensile fracture of both joints occurred at the interface between SZ and the thermos-mechanical affected zone at the AS, and showed a quasi-dissociative fracture.
为了阐明ZK60与Mg-4.6Al-1.2Sn-0.7Zn镁合金异种搅拌摩擦焊接接头的微观组织演变和力学性能，采用了两种将ZK60置于前进侧（AS）或后退侧（RS）的排列方式。讨论了异种焊接接头的宏观组织和微观组织，并测量了接头的显微硬度和横向拉伸性能。接头内存在三个具有不同成分的搅拌子区域和两个清晰的界面。由于母材原始晶粒尺寸和再结晶晶粒生长的共同作用，在搅拌区（SZ），ZK60的晶粒尺寸略有增加，而Mg-4.6Al-1.2Sn-0.7Zn的晶粒尺寸显著减小。由于应变和热量逐渐增加，搅拌区内从后退侧到前进侧析出相的溶解逐渐显著。晶粒细化导致硬度增加，而析出相的溶解导致硬度降低。ZK60置于后退侧时获得的接头性能略优于置于前进侧时的接头性能。两种接头的拉伸断裂均发生在搅拌区与前进侧热机械影响区之间的界面处，并呈现准解离断裂。
