Effects of Ti6al4v Powder Oxidation on Process Dynamics in Laser Powder Bed Fusion Additive Manufacturing

Recycling of unused powder for laser powder bed fusion (L-PBF) additive manufacturing is vital for its manufacturing sustainability. It is widely reported that the powder oxidation occurs during manufacturing and the oxygen levels of recycled Ti6Al4V powder continues to increase with increasing number of powder reuse. However, the impact of powder oxidation during laser-matter interaction, such as the melt pool dynamics, spatter, surface roughness and defects during L-PBF are not well understood. This study investigates the influence of Ti6Al4V powder with low (0.12 wt.%) and high-oxygen-content (0.40 wt.%) during multilayer thin-wall L-PBF part manufacturing using in situ synchrotron high speed X-ray imaging. The results indicated that the high-O-content powder particles had a positive effect in reducing melt ejections, surface roughness, and defect population in the built parts. The part produced from the high-O-content powder displayed higher microhardness possibly due to the solid solution strengthening mechanism and no obvious difference in the microstructure was observed.