Anode melting from free-burning argon arcs

Predictions have been made of anode melting for free-burning arcs by making two-dimensional calculations of temperature profiles of the are and the electrodes to make predictions of weld depth and weld shape in are welding. Predicted properties at 150 A, for various arc lengths, are compared with experimental results of: 1) weld shape; 2) heat intensity as a function of radius; and 3) current density as a function of radius at the anode. The whole region of the arc system is modeled, including the tungsten cathode, the arc plasma and the solid and molten anode, including convection within the molten weld-pool. Theoretical and experimental results are also obtained for high- and low-sulfur steel, which have markedly different surface tension properties of the molten liquid, resulting in weld depths that differ by a factor of three because of changed convective circulation properties in the weld pool. Although total power to the anode increases with increasing electrode separation, the current density becomes less, with the result that for electrode distances above 2 mm, for argon, the width and depth of the molten region become less, in agreement with experimental results that we have obtained.