Influence of the laser beam parameters on the depth and efficiency of the melting of metals by pulsed laser radiation

An experimental investigation was made of the geometric parameters of the melting zone and of some kinetic characteristics of the growth of a vapour — gas channel as a function of the spatial characteristics of a laser beam and of the profile of the radiation pulses. The depth of melting increased considerably, other conditions being equal, on reduction in the caustic angle of the laser beam incident on the irradiated surface. A new physical effect was discovered experimentally: the rate of growth of the vapour-gas channel increased when the length of this channel increased. This was the result of an increase in the laser radiation power density at the bottom of a channel during its growth. A molten zone depth of 6.5 mm was achieved for the first time for a pulse energy of 17.0 J.