搅拌摩擦焊对Mg-Gd-Y-Zr合金组织与性能的影响

Effect of Friction Stir Welding on Microstructures and Mechanical Properties of Mg-Gd-Y-Zr Alloy

对一种Mg-Gd-Y-Zr合金cast-T6状态板片试样搅拌摩擦焊接后的组织与性能进行了研究。结果表明:Mg-Gd-Y-Zr合金的搅拌摩擦焊的焊核区发生动态再结晶,为等轴细晶,硬度值最高;热机影响区基体组织具有热变形特征,第二相会粗化、溶解,硬度值稍低;热影响区晶粒尺寸与母材相当,第二相粗化,硬度值低于母材。在本工作实验条件下,cast-T6铸件试样的焊接系数达0.91,且伸长率相对于母材有大幅度提高。断口形貌SEM分析显示,接头断裂模式为韧性断裂。

Microstructures and mechanical properties of Mg-Gd-Y-Zr alloy slices as cast-T6 were studied after friction stir welding（FSW）.The results showed that the weld nugget zone（WNZ）,where the microstructures were consisted of refined and equiaxed grains by dynamic recrystallization,had the highest hardness.The thermo-mechanically affected zone（TMAZ）,where the matrix grains had the characteristic of hot-deformation,and the second phases particles were coarsened or dissolved,had the higher hardness.The heat affected zone（HAZ）,where the grain size was equal to the base metal,and the second phases particles became coarse,had the lower hardness than that of the base metal.During the present experimental condition,the ultimate-tensile-strength of the sample perpendicularly cut to the welding line reached as much as 0.91 of the one of the base metal,and the elongation was greatly improved.The fracture analysis by SEM showed that the fracture mode of the joint was ductile.