Characterization of the keyhole formed during pulsed Nd-YAG laser interaction with a Ti-6Al-4V metallic target

We observed, with an x-ray apparatus, the keyhole formed during the interac tion of a pulsed Nd-YAG laser beam with a metallic target of a Ti-6Al-4V ti tanium alloy. We noted that the keyhole formation is not instantaneous and that it grows linearly during the duration of the interaction. We highlight ed that its depth, at the end of the laser pulse, is practically equal to t he melting-zone depth in the material. Finally, we showed from the results of these tests that a quick estimation of the melting depth can be made sim ply from the ratio of the power densities used with a reference test. (C) 2 001 American Institute of Physics.