Metallographic study of denudation in laser powder-bed fusion

Abstract Recent experiments on laser powder-bed fusion (L-PBF) revealed intensive transport of powder particles in the gas phase and on the surface due to a gas flow indicating that it is the key mass-transfer process, understanding of which is important for optimizing and controlling the L-PBF. In the present work, the width of the so-called denuded zone formed around the fused bead as the result of powder transport is measured as function of the powder material and particle size. An original technique is proposed to fix non-consolidated particles on the substrate surface to visualize the denuded zone in the cross-section. To understand the influence of the gravity force, two materials of different specific mass are compared, cemented carbide and aluminum bronze. A theoretical analysis of inter-particle forces explains the measured dependencies of the denuded width versus the particle size.