Hybrid laser-MIG welding technology has several advantages over laser welding alone or MIG welding alone. These include the possibility of modifying weld bead shape including the elimination of undercut, the change of weld compositions, and the reduction of porosity formation in the weld. Although the hybrid laser-MIG welding method is becoming popular in industry, its development has been based on the trial-and-error procedure. In this paper, mathematical models and the associated numerical techniques were developed to calculate the heat and mass transfer and fluid flow during the laser-MIG welding process. The continuum formulation was used to handle solid phase, liquid phase, and mushy zone during the melting and solidification processes. The volume-of-fluid (VOF) method was employed to handle free surfaces, and the enthalpy method was used for latent heat. The absorption (Inverse Bremsstrahlung and Fresnel absorption) and the thermal radiation by the plasma in the keyhole, and multiple reflections at the keyhole wall were all considered in the models. The transient keyhole dynamics, interactions between droplets and weld pool, and the shape and composition of the solidified weld bead were all predicted for both the pulsed laser-MIG welding and three-dimensional moving laser-MIG welding. Computer animations showing the fluid flow, weld pool dynamics, and the interaction between droplets and weld pool will be shown in the presentation.

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