Pulsed laser enhanced metal transfer of aluminum alloy in GMAW

摘要

Pulsed laser enhanced metal transfer of gas metal arc welding (GMAW) is a recent modification of conventional GMAW that applies a relatively low-power pulsed laser to the droplet. Previously current-independent metal transfer of carbon steel, in free-flight or short-circuiting mode, was achieved by utilizing single-side pulsed laser irradiation on the droplet. However, there are few studies on laser enhanced aluminum alloy metal transfer of GMAW due to the high reflectivity of aluminum alloy. In addition, the low melting point of aluminum alloy makes it possible to cut off the welding wire (irradiate on the wire) directly by pulsed laser with high energy density, instead of irradiating on the solid-liquid interface of the droplet. Hence, the laser-enhanced aluminum alloy metal transfer process is studied in this paper. The results demonstrate that when the pulsed laser irradiated the solid-liquid interface of the droplet, the laser was found to lead to a significant increase in the stability of welding process as an additional detaching force and change the transfer mode and flight path of the droplet. Both the short-circuiting (SC) transfer and the spray transfer processes were promoted by changing the stress state of the droplet, and the transfer frequency was effectively increased. Moreover, when the pulsed laser irradiated the welding wire, the welding wire was cut off and the arc climbed to the laser incident point. The cut wire-droplet (W-D) changed into a molten droplet by the heating of the arc and entered into the molten pool. A new spray transfer balance formed at the incident point and the restriction that the laser must impinge on the solid-liquid (S-L) interface of the droplet was released.