Modeling and numerical study of keyhole-induced porosity formation in laser beam oscillating welding of 5A06 aluminum alloy

This paper presents a numerical framework of keyhole-induced porosity formation and methods to suppress porosity in laser beam oscillating welding. Circular and infinity oscillating paths with amplitude of 2 mm and frequencies of 100 Hz and 200 Hz were used. A numerical model for multiple phases, including solid metal, liquid metal and shielding gas is presented using the commercial software FLUENT. An adaptive rotated Gaussian volumetric heat source was developed for analysis of the heat input and temperature distribution during laser oscillating welding. The mechanism of porosity formation caused by keyhole collapse is studied by means of numerical analysis and experiments, and compared to conventional laser welding without oscillation. The numerical simulations were in good agreement with the experimental results. It can be concluded that upon the use of oscillation during welding, porosity decreased and was fully inhibited when using infinity-oscillating path with a frequency of 200 Hz. The developed multi-physics model aids in understanding the dynamics characteristics and keyhole-induced porosity formation during laser beam oscillating welding of 5A06 aluminum alloy.