Powder Recycling Effects on the Tensile and Fatigue Behavior of Additively Manufactured Ti-6Al-4V Parts

Additive manufacturing technology has enabled industries to generate functional parts with an increased level of complexity via layer-by-layer fabrication. In laser-powder bed fusion (L-PBF), powder is often recycled due to its high cost. However, there is no comprehensive study on how powder recycling affects its rheological properties, as well as the mechanical and fatigue behavior of the manufactured part. This study compares powder characteristics and mechanical performance of as-built and machined specimens fabricated from new and heavily used Ti-6Al-4V powder. Powder characteristics include particle size distribution and morphology, flowability, apparent density, compressibility, thermal conductivity, oxygen concentration, and more. Results indicate that particle size distribution becomes narrower and flowability increases with recycling. Not a significant effect of recycling was observed on the monotonic tensile and fatigue behavior of specimens in the as-built surface condition. However, machined specimens fabricated from used powder demonstrated longer fatigue lives in the high cycle regime.