The investigation of molten pool dynamic behaviors during the “∞” shaped oscillating laser welding of aluminum alloy

To reduce the pore defect during the laser welding of aluminum alloy, a 3D numerical model is developed to study the dynamic behaviors characteristics of molten pool in the oscillating laser welding. The “∞” shaped oscillating laser welding process of 5052 aluminum alloy is calculated by the numerical model. The characteristics of morphology, temperature field, flow field of the molten pool are analyzed and discussed in details by the numerical calculation. The results show that the molten pool formed in the “∞” shaped oscillating laser welding is wide and shallow and the bottom part of the molten pool is flat. The complex fluid flowing characteristics induced by the formed vortexes are found in the molten pool. The influence of oscillating amplitude and frequency on “∞” shaped oscillating laser welding is also investigated. It is clearly seen that the maximum temperature and maximum flow velocity of the molten pool are decreased with the increase of oscillating amplitude or frequency and then the molten pool becomes more stable and shallower, which is benefit for the bubble escaping and weld porosity reduction. Therefore, the proposed numerical simulation method for the “∞” shaped oscillating laser welding is efficient for the weld porosity reduction and welding quality improvement in the laser welding of aluminum alloy.