A Computational Fluid Dynamic Study on Transient Thermal Characteristics of Two-Phase Gas Metal Arc Welding Process

Abstract

Gas Metal Arc Welding (GMAW) is a welding process where an electrode wire is continuously fed from an automatic wire feeder through a conduit and welding gun to the base metal, where a weld pool is created. The formation of droplet and transfer of droplet are governed by the conservation equations. This study on GMAW aims to simulate transient behavior of welding arc and shielding gas flow. Computational Fluid Dynamics (CFD) is used as a tool to understand multifaceted physics involved in GMAW process. A two dimensional axisymmetric model is prepared to reduce computational time. The heat transfer and fluid flow in the arc column were studied based on the transient distributions of velocity, turbulence, voltage, current density, and temperature. An interactive coupling between welding arc, plasma, current and temperature were considered. The assumed steady state and laminar gas flow in traditional models studied so for does not reflect the real distributions in the welding process. Hence influence of the welding arc on the shielding gas flow and vice versa was taken up for study. From the study it is found that as the arc is struck, the shielding gas is accelerated towards axis. When the plasma reaches towards workpiece, axial momentum of gases is changed to radial momentum and flows away from the workpiece. The shielding gas also carries current from electrode to workpiece which helps in reducing spatter of the arc and hence concentrated arc is obtained