A mathematical model of gas tungsten arc welding considering the cathode and the free surface of the weld pool

Abstract

A two-dimensional axisymmetric numerical model, including the influence of the cathode and the free surface of the weld pool, is developed to describe the heat transfer and fluid flow in gas tungsten arc (GTA) welding. In the model, a boundary-fitted coordinate system is adopted to precisely describe the cathode shape and deformed weld-pool surface. The current continuity equation has been solved with the combined arc plasma-cathode system, independent of the assumption of current density distribution on the cathode surface, which was essential in the previous studies of arc plasma. It has been shown that the temperature profile, the current, and the heat flux to the anode show good agreement with the experimental data. Moreover, the current and the heat-flux distributions may be affected by the shape of the cathode and the free surface of the weld pool.

A comparison between different numerical formulations for welding arc representations

“…When the jet reaches the anode it is deflected, producing a high stagnation pressure. This pressure is expected to deform the free surface of the weld pool [7]. The jet flows radially outwards from the symmetry axis at the anode producing the characteristic bell like shape of high intensity arcs.…”

Efecto de la Corriente y Longitud de Arco en Soldaduras con Arco Eléctrico Asistido por Modelado Matemático

“…Las suposiciones más significativas consideradas en este modelo son: i) se considera que el arco está en el Equilibrio Termodinámico Local (LTE) (Boulos et al, 1994), ii) se supone que la densidad de corriente en el cátodo es constante con un valor de 6.5 ×10 7 Am −2 sobre la base de las mediciones experimentales disponibles (Mckelliget y Szekely, 1986), iii) Se considera que la superficie del ánodo es plana. Esto es ciertamente una simplificación excesiva, ya que la depresión de la piscina de soldadura es un problema muy bien documentado (Kim et al, 1997). Las ecuaciones que gobiernan incluyen: i) la ecuación de continuidad, ii) las ecuaciones turbulentas de Navier-Stokes en 2D, iii) la ecuación de conservación de energía que incluye como términos fuente el efecto de calentamiento Joule, el efecto Thompson y las pérdidas de radiación del plasma caliente, Iv) las ecuaciones de Maxwell, v) la ley de Ohm y vi) la ecuación de conservación de carga.…”

Susceptibility of iron castings to heat absorption from an electric arc and to hardened-layer shaping

“…The arc efficiency () is given as [2] Definition of arc efficiency actually represents heat transferred to the base metal (the energy content obtained from…”

“…The effect of this is the rise in the heat stream and temperature gradients, which favor the intensification of thermal flows in the molten pool. [2,3,4] The welding current induces a magnetic field, which also affects this phenomenon. For a symmetric magnetic field, the electromagnetic forces produce a streamlike flow of metal into the molten pool.…”