Effects of Oxide on Plasma in Arc Welding With Activating Fluxes

Investigation on effects of oxide activating fluxes on arc plasma was carried out in tungsten inert gas (TIG) welding on light metals, including magnesium alloy and aluminum alloy. In this paper, four oxides, i.e., ZnO, MnO
₂
, Cr
₂
O
₃
, and CdO, were used to study the roles of oxide on the arc state. When the fluxes were applied, it was observed that the information of the arc (electron density and electron temperature) change obviously. Based on the results produced, the contributions of oxides were studied from two viewpoints, including the information of arc plasma and the input of energy. Under the influence of oxides, both the electron density and the arc voltage got enhanced; however, the electron temperature decreased. In addition, the phenomenon of arc constriction was not observed with the contribution of fluxes. By comparing the experimental results of single TIG welding between with and without fluxes, increase in energy was suggested as the main contribution to the augment weld morphology.