Behaviors of element density distribution and melting metal flow in CO₂ laser-MAG hybrid welding

The distributions of the elements in CO₂ lasermetal active gas (MAG) hybrid welding were investigated with scanning electron microscope. The relation between the forming process of weld and the distribution of the element in CO₂ laser-MAG hybrid welding process was analysed with high-speed camera and scanning electron microscope. Both the melting metal flow and position of adding elements decide the element distributions. Metal flow varies due to changes of DLA (distance between laser and arc). The fluctuation of the keyhole can promote the uniform distribution of the element,but the impactness of the metal vapour enriches element in local zone of welding pool. The scanning and stiring of laser beam further make the uniform element distribution. The highest content and uniform distribution of elements can be obtained in the molten pool when the distance between laser and arc is 3 mm and elements are added from the location 1.0 mm away from the surface.