Numerical Analysis for Weld Formation Using a Free-Burning Helium Arc at Atmospheric Pressure

Abstract

In order to clarify the formative mechanism of weld penetration in an arc welding process, a numerical model is useful to understand quantitative values of the balances of mass, energy and force in the welding phenomena. In the present paper, the whole region of welding process using a free-burning arc, namely, tungsten cathode, arc plasma and weld pool is treated in a unified numerical model to take into account the close interaction between the arc plasma and the liquid metal. Calculations are made for the time dependent development of the weld pool for the free-burning arc in helium at atmospheric pressure. It is shown that the calculated convective flow in the weld pool is dominated by the surface tension gradient force and the electromagnetic force. It is also shown that different surface tension properties can change the direction of re-circulatory flow in the weld pool and dramatically vary the weld penetration geometry.