Revealing the microstructure characteristics, deformation behavior and mechanical properties of weakly textured Mg–Y-Nd-Gd-Zr alloy FSW joints

Abstract

In this work, friction stir welding (FSW) was performed on Mg–Y-Nd-Gd-Zr plate using two different welding parameters: 100 mm/min-1600 rpm and 100 mm/min-1000 rpm. The mechanical properties, deformation characteristic and microstructure of the FSW joints were thoroughly explored. Microstructure analysis revealed a significant refinement in the nugget zone (NZ), with original precipitates being considerably remelted into the matrix. Moreover, the micro-texture in NZ showed symmetrical distribution features, with the highest texture intensity at the NZ-side of the advancing side. Tensile results displayed that the strength of both joints exceeded 95% of the base material (BM), while their elongation was markedly inferior to the BM, with values of 13.8% and 12.2%, respectively. The higher joint connection strength was attributed to the combined effects of dislocation strengthening, grain refinement, precipitation phase re-dissolution softening, and favorable orientation of basal slip near the weld interface.