铝锂合金填充式摩擦点焊微观组织演化

Microstructure evolution during refill friction spot weldingof aluminium-lithium alloy

利用光学显微镜、扫描电镜、电子背散射衍射(EBSD)等手段对5A90铝锂合金填充式摩擦点焊接头各个区域的微观组织进行了分析.结果表明,焊核区发生完全动态再结晶,由细小的等轴晶组成,底部存在晶粒更加细小的细晶带,焊核区晶粒分布无明显织构.热力影响区发生了部分再结晶,由发生再结晶的等轴晶以及发生部分回复的变形晶粒组成,具有较多的变形组织特征;热力影响区与焊核区存在明显的分界面,分界面由尺寸明显小于周围晶粒的细晶组成,晶界较为密集.

The optical microscope,scanning electron microscope( SEM) and electron back scattered diffraction( EBSD)were used to analyze the microstructure in different reigns of refill friction spot welded( RFSW) joints. The results showed that complete dynamic recrystallization occurred in the nugget zone with fine equiaxial grains,and much finer grains existed at the bottom. The nugget zone had no obvious texture. Part dynamic recrystallization occurred in the TMAZ which contained fine equiaxial grains and partly recovery grains with deformed structure. An obvious interface existed between the nugget zone and TMAZ,and its grain was much finer than those on both sides,and the grain boundary was denser.