The effect of process parameters on keyhole welding with a 400 W Nd : YAG pulsed laser

A low average power pulsed Nd : YAG laser is used for bead-on-plate welding of low carbon steel plate. The criterion for welding in the conduction and keyhole regime together with the effect of laser process parameters on weld quality is studied. It is established that for a weld with full penetration and velocities viable for industrial applications, welding in the conduction mode would not be suitable. The formation of a keyhole is found to be highly dependent on laser pulse parameters. With an average power in the range 220-240 W and a peak power of 1.8 kW, full penetration through keyhole generation of a 0.7 mm thick st14 sheet metal is achieved