Improving Sustainability of Additive Manufacturing Through the Application of Discarded L-PBF Ti-6Al-4V Powder in EB-PBF

Powder bed fusion (PBF) processes can reduce end-user costs and improve the sustainability of metal additive manufacturing by increasing material utilization via recycling of feedstock. A study was conducted where used Ti-6Al-4V laser (L-PBF) powder, that had been labeled as “oversized” and discarded based on powder handling processes, was repurposed for use in the electron beam (EB-PBF) process. Initially, the discarded feedstock was characterized for chemical composition and flowability to establish an as-received condition. The EB-PBF process parameters were adjusted to produce specimens, and the tensile performance of the material was characterized. After the discarded L-PBF feedstock had been used for multiple EB-PBF builds, the tensile performance was compared with EB-PBF virgin Ti-6Al-4V powder. Fracture surfaces revealed that EB-PBF specimens manufactured from the discarded L-PBF powder had more-planar fracture surfaces and lower gross plastic deformation overall when compared to the virgin EB-PBF powder specimens. These results were further evaluated in the context of ductile plastic fracture analysis methodologies by considering two common models: Continuum Damage Mechanics (CDM) and Gurson-Tvergaard-Needleman (GTN). The conclusions highlight that while the EB-PBF process can manufacture parts from discarded L-PBF powders for improved process sustainability, managing chemical composition remains critical for Ti-6Al-4V.