Modeling of Transport Phenomena in Gas Tungsten Arc Welding of Ni to 304 Stainless Steel

This study investigates transport phenomena in the weld pool (WP) of gas tungsten arc (GTA) welding of Nickel to 304 stainless steel. A finite element 3D simulation of fluid flow and heat transfer of spot welding without consumable is accomplished which leads to prediction of the weld zone shape, weld penetration and dilution of alloying elements. The model includes magneto-hydrodynamics (MHD), the effects of surface tension and buoyancy, and the moving interface of solidliquid. Different thermophysical properties of alloys subjected to the weld also makes the problem more complicated. Lower melting temperature of 304 as compared to that of Ni leads to creation of an asymmetric WP which is larger in the 304 side. Higher thermal diffusivity of Ni accelerates heat removal in the Ni piece; accordingly maximum temperature happens at the 304 side.