Investigation of filler wire melting and transfer behaviors in laser welding with filler wire

Abstract For laser welding with filler wire process, there exist numerous technical parameters about the position between the laser beam and the filler wire, so it is difficult to guarantee the process stability and weld quality. In order to obtain stable welding process and high quality weld, the wire melting and transfer behavior must be controlled as the interaction between the laser beam and filler wire is extremely complicated. In this work, laser welding with filler wire process was studied, with particular attention to the melting dynamics of filler wire, the wire melting and transfer behavior. The high-speed camera system was used to observe the wire melting and transfer behaviors. The direct observation of the welding process by the high-speed camera can help to uncover the mechanism of the process stability of laser welding with filler wire. Systematic experiments were carried out in this study for liquid bridge and droplet transfer mode. The results indicated that the relative distance (Wx) between the filler wire and the laser beam and wire feed rate could influence the wire melting and transfer behaviors even the whole welding stability significantly. Therefore, control the Wx and wire feed rate is the key to obtain stable transfer mode for the liquid bridge. The research findings provided a clearer understanding for improving process stability and weld quality.