Recycling of selective laser melting medical Ti6Al4V powders and the impact on forming quality

The recycling of metal powders is an important way to save costs and shorten the preparation cycle in the selective laser melting process. However, the influences of the recycling times on the powder characteristics and the formed part performance are still unclear. The effects of the recycling times on the physical and chemical properties of the medical Ti6Al4V powders in selective laser melting were studied, such as particle size distribution, morphology, chemical composition, and fluidity, and the microstructure and mechanical properties of the formed samples were analyzed. The results show that after 30 recycling times, the particle size distribution of the powders becomes concentrated, the particle size is increased, the adhesion and agglomeration of the particles are decreased, the contents of Al and O are changed, the fluidity and sphericity of the powders fluctuate slightly, and the bulk density and tapped density increase slightly. With the increase of recycling times, the microstructure of the formed samples is not affected, which is composed of fine lamellar α+β phases, the density and hardness remain stable, the tensile strength is increased, while the fracture characteristics remain unchanged.