N. Mbonde and A.Kh. Mohamed (Tanzania)
Modeling, GMAW, Joule heating, Electron condensation, Magnetic forces, Cohesive force, Heat and Mass Transfer; Droplet forces.
The melting of the wire is a fundamental characteristic of Gas Metal Arc welding which influences process stability, productivity, and weld bead shape. The present work describes a model developed to calculate Heat and Mass transfer during the welding process including the effects of joule heating, Electron condensation, Cohesive and Magnetic forces. These forces have significant effects on the transient distributions of current density, Heat and mass transfer in GMAW. It has also been proven that physical properties of shielding gases affects some of arc characteristics like metal transfer, wetting behaviour, depth of penetration, shape of penetration, travel speed and easy of arc starting. In this paper it has been shown that, proper doping of inert gases with reasonable amounts of active components such as CO2, NO or O2 results in better arc stabilisation and therefore better heat and mass transfer. The dissociation energy of polyatomic components in gas mixtures enhance the heat input to the base material due to the energy released by recombination. The results were compared to the results obtained from the experiments and various literatures.
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