Numerical simulation of keyhole welding of aluminium thick plate with plasma arc

Abstract

Plasma arc welding can realize high-speed welding, deeper weld penetration and, furthermore, smaller thermal distortion. For these reasons, plasma arc welding is employed for keyhole welding. However, it has been pointed out that it is difficult to obtain the stability of the welding. In this study, we have developed a unified plasma arc welding model for analysing the welding mechanism and influence of the torch design and operation conditions of the arc on the welding process. In this paper, the keyhole welding of a thick aluminium plate employing the plasma arc was numerically analyzed for clarifying the mechanism determining the keyhole size which is important for improving the stability of the process. As a result, it was found that the keyhole size is determined mainly by a force balance between the surface tension of a weld pool and metal vapour pressure.