Multiphysics modelling and numerical simulation of GTA weld pools

It is well reported in the literature that the characteristics of the weld joint and the heat transfer at the solid/liquid interface are highly dependent on the fluid flow in the weld pool. In the present work, we numerically investigate the effects of welding parameters on GTA weld pools developments. A 2D model including the cathode, arc plasma and anode domains is developed to study in-depth stationary GTAW. This also permits to quantify the effects of the chemical composition of the shielding gas, and to study new welding techniques such as GTAW with alternate supply of shielding gases. The study of moving GTAW with filler metal is performed using a hybrid 2D-3D approach. The numerical simulations conducted for horizontal-position welding reveal a huge asymmetry of the weld towards the opposite gravity direction, which is numerically found to be the effect of buoyancy-induced flows and asymmetrical free surface deformation. This defect can be significantly reduced in dissimilar sulfur content welds by placing the low sulfur plate at the bottom.