Deep penetration welding, also called Keyhole welding, is one of the most interesting flow and heat transfer phenomena in laser welding. Once a threshold power density is reached a small diameter vapor cavity, which is characteristic of keyhole welding, is formed. Understanding the fundamental aspects of deep penetration welding will aid in the design and control of welding processes. Of particular interest is the prediction of penetration depths given certain process parameters such as material velocity and laser power.
The present investigation focuses attention on the lower portion of the keyhole where the essential features of the flow are primarily two-dimensional in the plane perpendicular to the axis of the laser. Further it is proposed that by focusing on the stagnation region an approximate solution can be obtained which would capture the essential features of the problem for large Peclet numbers. This work can later be used as a basis for more exact methods of solving the Navier-Stokes equations.