10% of plasma arc outflows from the keyhole exit. The heat conduction flux is more than two times of the
electron condensation flux in the welding process. It is also found that the Marangoni shear takes obvious
priority over the electromagnetic force, and two circular flows appear in the weld pool. Moreover, arc
flows, electrical potential, current density and electromagnetic force were all predicted to further the
understanding of thermal plasma process. Two velocity-transition points were found within the keyhole,
from which the arc begins to flow outwards and upwards and finally outflows through the top metal surface.
Finally, experiment was conducted on the stainless steel plate, and the measured weld pool is close
to that calculated by our model.