Numerical study of keyhole-induced porosity suppression mechanism in laser welding with beam oscillation

The suppression mechanism of keyhole-induced porosity of oscillating laser beam welding (OLBW) was investigated via numerical simulation with keyhole dynamics and melt flow. The established model was verified by the corresponding experimental results. Results show that the weld porosity of 304 stainless steel can be controlled within 0.6% in OLBW and the large keyhole and well-balanced energy of the melt pool are contributing to porosity reduction. Also, two kinds of porosity suppression mechanisms in OLBW were clarified: first, the stirring effect of the oscillating beam keeps the bubble migration speed is superior in the competition with the solidification rate; second, bubbles can be absorbed timely by the dynamic keyhole when the moving speed of the keyhole reaches 504.6 mm s(-1).

Automated summary

By investigating the suppression mechanism of keyhole-induced porosity in oscillating laser beam welding through numerical simulation and experimental verification, it was found that controlling the energy balance of the keyhole and melt pool can effectively reduce the weld porosity of 304 stainless steel. Additionally, two mechanisms were identified for porosity suppression: the stirring effect of the oscillating beam and the timely absorption of bubbles by the dynamic keyhole.