Effect of Particle Surface Roughness on the Flowability and Spreadability of Haynes 230 Powder During Laser Powder Bed Fusion Process

Abstract

The flowability and spreadability of powders are the important factors for additive manufacturing as these two factors directly impact the powder bed packing density, which further affect the quality and mechanical properties of the built components. The flowability and spreadability of powders are dramatically influenced by particle surface roughness as well as the surface energy. The present research attempt to demonstrate the effect of the particle surface roughness on the flowability and spreadability of Haynes 230 powder. The virgin atomized Haynes 230 powder and the atomized powder after ball milling treatment were employed in the present research. The results show that after ball milling, the surface roughness rms of the initial powder increased from 14.87nm to 42.54 nm and the surface energy of powder increased from 41.19 to 77.21mJ/m2, the rest angle of powder increased 30% and the static cohesion index increased from 0.63 to 2.00. According to the calculated Bog coefficient of the two powders (from 2.85 to 15.56), the increase of particle surface roughness leading to the increase of contact force and non-contact force among particles, which were caused by the increased cohesion, leading to the decrease of powder flowability and spreadability as well as the powder bed packing density.

Keywords: Laser powder bed fusion process, Metal powder, Surface roughness, Flowability, Spreadability