激光-电弧复合焊接相对激光焊接的优势之一是通过焊接材料的添加，调整焊缝的合金元素成分，改善焊缝组织与性能。焊接材料添加的合金元素在焊缝中的均匀分布是体现激光-电弧复合焊接这一优势的关键。然而，对于窄而深的激光-电弧复合焊焊缝，实现合金元素的均匀分布是非常困难的。研究了焊接工艺参数对CO2激光-熔化极气体保护(GMA)复合焊焊缝合金元素分布的影响规律，并讨论了熔池流动行为与合金元素分布均匀性的关系。结果表明，随着焊接速度的减小，CO2 激光-GMA 复合焊焊缝合金元素的分布趋向于均匀分布；随着坡口间隙的增大，焊缝合金元素均匀程度越高。焊接方向为激光在前时，激光-电弧复合焊接熔池流动为内向流动时(即熔池表面从熔池后部向小孔流动，并且小孔后沿液体向下流动)，焊缝合金元素分布较均匀，其均匀性高于焊接方向为电弧在前时的情况。焊接方向对焊缝合金元素分布的影响规律主要取决于电弧拖拽力和熔滴对熔池冲击力的方向。当焊接方向为激光在前时，电弧拖拽力和熔滴对熔池冲击力指向小孔方向，促进了熔池内向流动。

Compared with laser welding, laser-arc hybrid welding has a lot of advantages. One of these advantages is to improve the weld metal microstructure and mechanical properties by feeding welding materials. In this case, it is essential to achieve the homogeneous distribution of alloying elements. In deep and narrow hybrid welds, however, it is very difficult to attain the homogeneous distribution. The effect of welding parameters on the distribution of wire feeding elements is investigated during CO2 laser and gas metal arc (GMA) hybrid welding process, and the influence of fluid flow behaviour on the homogeneity of weld metal is also discussed. The results indicate that the homogeneity of weld metal is improved when decreasing the welding speed or increasing the gap width. When the welding direction is leading laser, the molten metal flows from the rear end to the keyhole on the pool surface and then goes down just behind the keyhole during hybrid welding, namely inward flow, resulting in almost homogeneous distribution of alloying elements. The distribution of alloying elements is more homogeneous in leading laser compared with leading arc, since both of the drag force of the plasma jet and momentum of droplet direct to the keyhole, promoting the inward flow in leading laser.