Numerical calculation of variable polarity keyhole plasma arc welding process for aluminum alloys based on finite difference method

Variable polarity keyhole plasma arc welding process was simulated via the developed models in nonorthogonal body-fitted curvilinear coordinate system depicting the physical phenomena in the keyhole weld pool. Free surface shape of the keyhole weld pool, variable polarity welding current, temperature-dependent material thermophysical properties, wire filling, and turbulent mixing in the molten metal were considered in the computation. Transient evolution of the geometry for the keyhole weld pool was predicted. Geometrical dimensions for the keyhole molten pool at different welding conditions were computed. Effects of wire filling, enhanced fluid thermal conductivity also kinetic viscosity on geometry and velocity field for the keyhole weld pool were analyzed. Temperature distribution for the plasma arc was calculated. In addition, the models used were experimentally validated through the geometry of the weld cross-section.