Ultrasonic vibration-assisted laser atomization of stainless steel

Abstract

In this paper, a novel ultrasonic vibration-assisted laser atomization process for producing fine metallic powder with average particle diameter of about 75–95 μm is proposed. The process involves irradiation of a high power continuous wave laser on a consumable metallic substrate vibrating at an ultrasonic frequency. The laser irradiation on the vibrating substrate causes surface melting and expulsion of fine droplets. Preliminary results are presented for the atomization of AISI 316 stainless steel using CO2 laser power of 950 W and vibration frequency of 20 kHz. The average particle size and size distribution is not significantly influenced by vibration displacement consistent with capillary wave theory of atomization. The microstructure of the larger atomized particles showed fine dendritic structure at the surface and shrinkage porosity at the center of particles indicating multiple surface nucleation for solidification.