Numerical simulation of plasma arc welding with keyhole-dependent heat source and arc pressure distribution

A three-dimensional and transient model with keyhole geometry-dependent heat source and arc pressure distribution is developed for plasma arc welding process. The influence of the keyhole evolution on heat flux and arc pressure distribution on the keyhole wall is taken into consideration. The dynamic variation of the temperature field and fluid flow in the weld pool as well as the keyhole shape and size are quantitatively analyzed. The experimentally observed phenomena, i.e., the backward curved keyhole channel and the very thin layer of molten metal at the front edge of weld pool, are first demonstrated with numerical simulation. The predicted establishment time of open keyhole, displacement of keyhole exit, and fusion line generally agree with the experimental ones.