The relation between electrode lifetime and additive consumption during TIG welding

Abstract

The temporal evaluation in the distribution of additives inside the electrode was clarified by the cross-section observation of the electrode after the arc discharge and the numerical simulation. The effect of the adsorption energy of additives on the electrode lifetime was also investigated by the numerical simulation. During the arc discharge, additives whose work function is lower than tungsten are gradually consumed from the electrode tip due to evaporation of additives on the electrode surface and diffusion of additives inside of the electrode. When the operating temperature of the electrode exceeds the melting point of tungsten, the electrode reaches the lifetime by melting and deforming. Furthermore, by setting an appropriate adsorption energy, the two dimensional computational model including diffusion and evaporation of additives obtains the electrode lifetime that agrees with the experimental result. In addition, the larger the adsorption energy of additives inside of the electrode is, the longer the electrode lifetime is.