A model for arc-cathode attachment in gas metal arc welding is presented. It considers the cathodic heating in the case of a non-refractory iron cathode, with the assumption of the lowering of the local plasma temperature, due to cold metal vapor. It takes the plasma bulk temperature as well as the cathode drop voltage as free parameters and it gives a maximum of heat flux and current density for a cathode surface temperature below boiling temperature. The applicability as a heat source description in a weld pool simulation has been shown, and the temperature field of the cathode was calculated, giving rise to heat flux and current density distributions, which differ significantly from the converntionally used axisymmetric Gaussian distribution. The maximum cathode surface temperature was lower than boiling temperature, which is in agreement with the observeration.

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A mathmatical model of electromagnetic processes occurring in the 'arc column -anode regionevaporating anode' system is presented. The anode region of electric arc with an evaporating metallic anode is described by a model, under which the non-equilibrium near anode plasma containing atoms and ions of the evaporated metal, along with atoms and ions of the ambient (inert) gas, is subdivided into a space charge layer immediately adjoining the anode surface and ionisation region adjacent to the arc column. This model allows determining the potential drop between welding arc column plasma and anode surface depending on the current density and plasma temperature near the anode, as well as upon the temperature of its surface.

Fig. 16. Plastic strain propagation contours in different regionsat different time periods during tensile test.

While the application of the Smoothed Particle Hydrodynamics (SPH) method for the modeling of welding processes has become increasingly popular in recent years, little is yet known about the quantitative predictive capability of this method. We propose a novel SPH model for the simulation of the tungsten inert gas (TIG) spot welding process and conduct a thorough comparison between our SPH implementation and two finite element method (FEM)-based models. In order to be able to quantitatively compare the results of our SPH simulation method with grid-based methods, we additionally propose an improved particle to grid interpolation method based on linear least-squares with an optional hole-filling pass which accounts for missing particles. We show that SPH is able to yield excellent results, especially given the observed deviations between the investigated FEM methods and as such, we validate the accuracy of the method for an industrially relevant engineering application.