Research Progress of the Metal Powder Reuse for Powder Bed Fusion Additive Manufacturing Technology

Additive manufacturing (AM), epitomized by powder bed fusion (PBF), has emerged as one of the fastest-growing, most dynamic, and highly focused techniques within the advanced manufacturing sector. Nevertheless, as the primary factor determining cost and quality of PBF-produced parts, amounts of metal powder feedstock remains unused and requires recycling after each PBF build. Due to the unique thermal history experienced by individual particles during manufacturing, recycled powders exhibit variations in chemical composition, particle morphology, size, size distribution, microstructure, and even thermal-physical properties. Moreover, these alterations are influenced by the inherent properties of the metal powder, machine setup, and manufacturing process. Consequently, the repeatability and reproducibility of the recycled powders cannot be defined uniformly. Using Ti6Al4V, Inconel 718, AlSi10Mg, and stainless steel metal powders as examples, this paper reviews recent literature specifically addressing recyclability and reusability of the recycled powders, in particular the subsequent effects of the reused powder on powder beds, process operation, and product properties in PBF builds. By exploring the interaction between energy beam, powder and melt pool, we discuss the formation mechanism and composition of the recycled powders, and analyze the impact of powder building cycles and varying powder characteristics on powder bed properties, manufacturing processes, part microstructures, and mechanical properties. Additionally, we discuss the solutions for identifying end-of-life powder and introduce strategies to enhance powder reusability. In doing so, we seek to provide a comprehensive understanding of powder feedstock for building an optimized processing window, with a view to contributing to extending the service life of metal powders.