Effect of powder recycling on powder characteristics and mechanical properties of materials produced by laser powder bed fusion (LPBF): A review

As the Laser powder bed fusion (LPBF) process advances toward industrial-scale production, the sustainability of metal powder feedstocks has become a focal point of research. The powder recycling approach, while environmentally and economically favorable, results in a series of physicochemical variations that could compromise the part quality. The resulting variation in powder characteristics with powder recycling could affect the powder layer density and melt pool dynamics, resulting in defect formation and hindering the structural integrity of LPBFed parts. These alterations pose significant constraints to mechanical performance, particularly in fatigue-sensitive applications where even minor imperfections can substantially reduce service life. The current article explores the intricate causal relationship between powder reuse and the resulting physical, chemical, and mechanical performance of built parts, focusing on the fundamental deterioration mechanisms that could cause degradation in powder's physical and chemical characteristics. It explores how such variations could impact powder bed density (PBD) and, consequently, the durability of produced parts. Promising powder deterioration prevention approaches, involving real-time monitoring and improved replenishment procedures, are evaluated extensively. Furthermore, the study reveals substantial research gaps in the field, emphasizing future research directions that could enhance the sustainability of the LPBF process through optimizing powder recycling techniques. The discussion section presents a holistic perspective on powder recycling in LPBF by integrating experimental findings with industrial standard operating procedures, along with providing a roadmap for improving the efficiency of materials while preserving structural reliability.