2219铝合金TIG填丝堆焊成形薄壁试样组织特征

进行了2219铝合金多层单道TIG填丝堆焊成形试验，并观察了堆焊成形试样的宏观形貌与微观组织特征。结果表明，堆焊成形试样整体冶金结合良好、无明显的未熔合现象。在试样的中下部区域有平行条纹出现，条纹间距大约相等，并且条纹区域与层间位置大致重合。顶部区域组织呈树枝状，且Cu元素偏析严重。中下部区域组织形态多样，包括条纹组织、等轴组织、柱状组织和平面组织，各类组织依次循环出现，同时Cu元素偏析明显改善。堆焊试样中存在一定量的孔隙缺陷―气孔和缩孔，两者尺寸介于10~80μm之间，集中出现在层间位置（条纹）。

Microstructures of 2219-Al thin-walled parts produced by shaped metal deposition

A multi-layers single-pass thin-walled part was produced by shaped metal deposition and the macro-morphologies and microstructures were observed. Results show that the whole part exhibits a good metallurgical junction and fusion phenomenon. On a macro-level, many parallel stripes occur in the middle and bottom regions. The parallel stripes are equidistant distributed and coincident with the layers-interfaces. In top region, the dendritic grains dominate and the segregation of Cu-element is serious. In middle and bottom regions, the microstructures are varied, including equiaxed grains, columnar grains and planer grains. The grains arrange according a list-regular and the segregation of Cu-element is alleviated compared with top region. There are a lot of porosities and shrinkages in the part, whose sizes vary from 10 μm to 80 μm. Moreover, the porosities and shrinkages are more likely to occur in the interfaces.