A STUDY ON THE 3-DIMENSIONAL ANALYSIS OF HEAT AND FLUID-FLOW IN GAS METAL ARC-WELDING USING BOUNDARY-FITTED COORDINATES

Computer simulation of three-dimensional heat transfer and fluid flow in gas metal arc (GMA) welding has been studied by considering the thr ee driving forces for weld pool convection, that is the electromagneti c force, the buoyancy force, and the surface tension force at the weld pool surface. Molten surface deformation, particularly in the case of GMA welding, plays a significant Part in the actual weld size and sho uld be considered in order to accurately evaluate the weld pool convec tion. The size and profile of the weld pool are strongly influenced by the volume of molten electrode wire, impinging force of the arc plasm a, and surface tension of molten metal. In the numerical simulation, d ifficulties associated with the irregular shape of the weld bead have been successfully overcome by adopting a boundary-fitted coordinate sy stem that eliminates the analytical complexity at the weld pool and be ad surface boundary. The method used in this paper has the capacity to determine the weld bead and penetration profile by solving the surfac e equation and convection equations simultaneously.