喷射成形Al-Zn-Mg-Cu合金电子束焊接接头组织研究

National Center of Analysis for Nonferrous Metal and Electronic Material,

摘要:

采用真空电子束焊接的方法对10 mm厚的喷射成形Al-Zn-Mg-Cu合金进行了焊接实验。采用金相显微镜、扫描电镜、透射电镜等方法分析了焊接接头的微观组织特点。结果表明，喷射成形Al-Zn-Mg-Cu合金电子束焊接接头由3个区域(近缝区母材、熔合区、热影响区)组成。焊缝宽0.3～1 mm，熔合区由尺寸3～8 μm的等轴细晶组成，析出相沿晶界均匀分布，晶内析出相较少；热影响区小部分区域发生了重熔，存在大量的共晶组织，部分保留了母材的原始组织特征。经T6处理后熔合区晶粒尺寸无明显变化，晶界变细，沿晶界分布的连续析出相溶解，变成了孤立的析出相，尺寸1~2 μm。同时存在少量长约2 μm的针状(棒)的Al7Cu2Fe相, 热影响区共晶组织消失

Abstract:

The electron-beam welded microstructure of spray formed Al-Zn-Mg-Cu alloy was investigated using optical microscopy, scanning electron microscopy, transmission electron microscopy etc. The results indicate that the welds are composed of three zones, the base metal, nugget and heat affected zone. The width of the weld is 0.3~1 mm, and the weld nugget zone is composed of equiaxed grains with an average grain size of 3~8 μm, and the second phases are mainly distributed along the grain boundaries. Heat-affected zone is composed of α (Al) and Al/AlZnMgCu eutectic structure. Some of the heat affected zone have displayed remelting characteristics. After T6 treatment, most of the AlZnMgCu phases in weld nugget were dissolved into α (Al), and the eutectic structure in heat-affected zone disappeared