Evaluating the Effects of Shielding Gas Composition on Arc Plasma in Gas Metal Arc Welding (GMAW)

Abstract

Gas metal arc welding (GMAW) is one of the prime arc welding processes in which an electric arc is formed between a consumable wire electrode and the metal work piece, which heats the metal work piece allowing them to join by melting. Significant advancements have been made in this field in recent years to improve and optimize welding performance with high efficiency and a higher rate of production. The shielding gas is an essential component of gas shielded welding processes, its purpose is to shield the weld area from atmospheric gas contamination and provide a transport medium for the electrical current to flow. It is crucial to determine an ideal composition of the shielding gas to achieve its effective exploitation and thereby optimization of the process. A shielding gas mixture composing of two or more gases is commonly used in GMAW to benefit from the distinguishing abilities of each gas. The shielding gas composition is known to affect various weld aspects including arc characteristics, metal transfer process, weld appearance, geometry, and mechanical properties. These factors play a crucial role in determining the weld quality. In this research, a two-component mixture of the shielding gas is used in GMAW. The research primarily focuses on evaluating the effect of different mixtures of shielding gases on arc characteristics including temperature distribution, pressure distribution, flow velocity, current density, electric potential, and electric field along with a DH-36 steel workpiece considered through numerical simulation in Ansys CFX. We use different inert and reactive gases to observe the influence of shielding gases. The effects of pure argon, as well as varying percentages of O2 and CO2 mixed with argon, are observed. The obtained results are analyzed using diverse properties of the shielding gases including density, viscosity, electrical conductivity, thermal conductivity, radiative emission coefficient and specific heat. This research is aimed at guiding the manufacturing industries in utilizing the shielding gases in an optimized way and improve the overall welding efficiency.