Effects of surface tension on predictions of weld pool formation in TIG welding

Abstract

TIG welding process consists of close energy balance between arc plasma and weld pool which plays an important role of anode electrode. Although arc is a heat source of welding and then energy produced by the arc is transferred into the anode, energy transfer inside the weld pool as the anode is more important for welding due to formation of weld geometry. In particular, the difference of convective direction of fluid flow in the weld pool dramatically leads to different weld geometry. In this paper, mechanisms of weld pool formation in TIG welding process is discussed on the basis of numerical simulation which takes account of close interaction between the arc plasma and the anode electrode. We also discuss the influence of the data of surface tensions from literatures. It is shown that surface tension gradient with temperature strongly dominates the direction of convective flow in the weld pool due to Marangoni effect and then greatly affects the formation of weld pool due to change in energy transfer inside the weld pool.