Study of porosity suppression in oscillating laser-MIG hybrid welding of AA6082 aluminum alloy

Abstract

The AA6082 aluminum alloy was welded by oscillating laser-MIG hybrid welding. By using beam oscillation, the porosity can be effectively suppressed in the range of 100−300 A arc current, especially at low arc current level. Percent porosity decreased greatly with the increase of the oscillating amplitude and frequency. The threshold frequency of porosity-free at different amplitudes were achieved. The effect of beam oscillation on porosity formation and suppression was studied by observing keyhole behavior via a “sandwich” high-speed video method. It was found that the porosity suppression depended on three reasons. Firstly, high-frequency oscillating keyhole can “capture” the bubbles or cavities in the molten pool and solidification front. Secondly, high-frequency oscillating keyhole can enlarge the diameter of keyhole and improve keyhole stability. Thirdly, beam oscillation can form stirring effect in molten pool, which can produce turbulence to reduce possibility of bubbles moving to the solidification front.