A study of low-power density laser welding process with evolution of free surface

In this study, numerical investigation has been performed on the evolution of weld pool geometry with moving free surface during low-energy density laser welding process. The free surface elevates near the weld pool edge and descends at the center if dσ/dT is dominantly negative. It is shown that the predicted width and depth of the weld pool with moving free surface are a little greater than those with flat weld pool surface. It is also believed that the oscillation of the weld pool surface during the melting process augments the rate of convective heat transfer in the weld pool. The present analysis with moving free surface should be considered when Peclet number is greater and Weber number is much smaller than one since the deformation of the weld pool surface is noticeable as Pe number increases and We number decreases, especially when Pe/We is greater than the order of 10.