Powder recycling is widely applied in Selective Laser Melting (SLM) to reduce material costs and waste; however, repeated reuse may influence the characteristics of additively manufactured components. This study investigates the effect of powder recycling on the chemical composition, micropurity, and porosity of M300 maraging steel produced by SLM. Virgin and recycled powders were processed under identical conditions using a Renishaw AM500 system. The chemical composition of the printed samples was determined by glow discharge optical emission spectroscopy (GDOES), while powder morphology, defects, and micropurity were examined using scanning electron microscopy. Porosity was quantified by image analysis following a procedure comparable to ASTM. The results revealed measurable changes in chemical composition associated with powder recycling, particularly reduced nickel content and increased aluminum, silicon, and chromium concentrations. Despite these variations, both material conditions exhibited very low and comparable porosity levels. Typical SLM-related defects, including pores, keyholes, and microcracks, were observed in both cases. The findings indicate that recycled M300 maraging steel powder can be reused in SLM without a significant effect on porosity or defect formation, provided that powder quality is continuously monitored.
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