Heat transfer and fluid flow during gas-metal-arc fillet welding for various joint configurations and welding positions

Gas-metal-arc (GMA) fillet welding is one of the most commonly used welding processes in the industry. This welding process is characterized by the complex joint geometry, a deformable weld pool surface, and the addition of hot metal droplets. In this work, a three-dimensional numerical heat-transfer and fluid-flow model is developed to capture the effects of the tilt angle of the fillet joint and the welding positions, i.e., V, L, and other configurations on the temperature profiles, velocity fields, weld pool shape, weld pool free surface profile, thermal cycles, and cooling rates during GMA welding in spray mode. The governing equations of conservation of mass, momentum, and energy are solved using a boundary fitted curvilinear coordinate system. The weld pool free surface deformation is calculated by minimizing the total surface energy. A dimensional analysis is performed to understand the importance of heat transfer by conduction and convection and the role of various driving forces on convection in the liquid weld pool. The computed shape and size of the fusion zone, finger penetration characteristic of the GMA welds, and the solidified free surface profile are in fair agreement with the corresponding experimental results. The calculated cooling rates are also in good agreement with independent experimental data. The results reported here indicate a significant promise for understanding the effect of joint orientations and welding positions on weld pool shape, size, and the cooling rates based on fundamental principles of transport phenomena.