Thermal properties of powder beds in energy absorption and heat transfer during additive manufacturing with electron beam.

Powder bed properties affect the quality of the parts manufactured by powder bed fusion (PBF). On PBF with laser, researchers had thoroughly studied the impact of powder layer on consolidation. In terms of interaction mechanisms with materials, electron beam is different from laser. Thus, an in-depth discussion is required for PBF with electron beam. In this study, numerical simulations were performed to reconstruct the powder bed and analyze the subsequent consolidation. The powder layer's presence altered the emissivity and thermal conductivity to be different from those of a solid. Concerning the powder with different particle size distributions, the differences in thermal properties led to an alteration in the molten pool formation. The emissivity increased, and the thermal conductivity decreased as the fraction of fine powders increased. With the increased fraction of fine powders under a given layer thickness, relatively high energy should be input to ensure exceptional forming quality. Unlabelled Image • Numerical simulations were performed to investigate consolidation of powder beds in PBF-EB. • Powder layer possessed high emissivity and low thermal conductivity compared with a solid base. • Emissivity increased and thermal conductivity decreased as the fraction of fine powder increased. • Relatively high energy of electron beam should be applied as the fraction of fine powder increased. [ABSTRACT FROM AUTHOR]