Papers
Liming TAN, Jin LÜ, Yi ZHANG, Zi WANG, Xin MA, Hailong ZHANG, Yiwei LUO, Juncheng WANG, Jie SU, Jinrong WEN, Lan HUANG, Feng LIU
Selective laser melting (SLM), as a prominent metal additive manufacturing technology, has achieved industrial applications in aerospace, biomedical, and energy sectors due to its near−net−shape forming capability and ability to fabricate complex structures. Superalloys, owing to their excellent high−temperature strength, oxidation resistance, and creep performance, are the preferred materials for SLM−fabricated heat−resistant components. However, the unmelted powder generated during SLM undergoes degradation (including thermal cycling, oxidation, and particle size distribution alterations), posing significant challenges to its efficient recycling and reconditioning, which constitutes a critical bottleneck for sustainable industrial development. This article is centered on the research progress concerning the recycling of superalloy powders during selective laser melting (SLM). It systematically analyzes the evolution of physical and chemical characteristics of powders throughout the recycling process, elucidates the impact of recycled powders on the formation of defects and mechanical properties of printed parts. As the number of recycling cycles increases, satellite particles and irregular granules appear on the powder surface, leading to an increase in surface roughness, along with a continuous rise in oxygen content. Additionally, the recycled powder results in an increased defect density in the fabricated parts, manifested as a higher prevalence of unmelted pores and micropores, while the mechanical properties exhibit complex variations. Technological breakthroughs and application cases in efficient recycling and reconditioning methods were summarized. Furthermore, it proposes future research priorities and development directions in this field.