Study the Shielding Gas Effects on Transport Phenomena in GMAW Arc
This article presents a numerical investigation on the transient transport phenomena including the arc plasma generation and evolution; droplet formation, detachment, transfer and impingement onto the workpiece; weld pool dynamics and final weld bead shape for pure argon and three argon-helium mixtures (75% Ar + 25% He, 50% Ar + 50% He, and 25% Ar + 75% He) during the GMAW process. The results indicate that the arcs in different shielding gases behave very differently due to the significant differences in thermophysical properties, including the ionization potential and the electrical conductivity, thermal conductivity, specific heat, and viscosity at high temperatures. For the same welding power input, the increase of helium content in the mixture leads to a stronger convergence of electric current at the workpiece and a stronger upward electromagnetic force near the workpiece, resulting in a cone-like plasma arc, which is in contrast to a bell-like plasma arc for argon-rich mixtures.
J. Hu et al., "Study the Shielding Gas Effects on Transport Phenomena in GMAW Arc," Proceedings of the 20th International Symposium on Transport Phenomena, 20th International Symposium on Transport Phenomena, Jan 2012.
20th International Symposium on Transport Phenomena
Mechanical and Aerospace Engineering
Article - Conference proceedings
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