Mechanical properties of oxide dispersion strengthened Inconel 625 alloy produced by laser powder bed fusion

Date

2024-11-26

Author

Demirci, Kadir Tuğrul

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The global energy demand, especially in developing countries, is expected to increase by 50% in the coming decades due to improving living standards. Nuclear energy, especially produced by Generation IV reactors, will have a crucial role in meeting this demand. Among these, molten salt reactors (MSRs) stand out for their safety, efficiency, and versatility. However, current structural materials fail under the extreme conditions of MSRs, including high temperatures, radiation, and corrosive environments. Nickel-based superalloys are promising candidates for these challenges due to their high-temperature strength, resistance to radiation and corrosion. Oxide dispersion strengthening (ODS) can further enhance these properties, while additive manufacturing (AM) offers a sustainable route to produce complex ODS alloy geometries. In this study, a new ODS Inconel 625 (IN625) alloy, containing 0.3 wt% Y₂O₃ and 0.4 wt% Hf has been developed and produced, using laser powder bed fusion (L-PBF), which is one of the most important AM methods. A production matrix with varying laser power and scan velocity has led to over 99.9% densification for ODS IN625. Microstructural analysis revealed carbides and coarse oxide formations, while nano-oxides were observed using TEM. Two different heat treatments containing solutionizing and aging (SA), and direct aging (DA) have been applied to the samples Among heat-treated materials, DA applied ODS samples possessed the optimal mechanical properties at both room temperature and at 700 °C. For comparison, same mechanical tests have been applied on a standard IN625 produced by L-PBF, along with a conventionally produced IN625 rod.

Subject Keywords

Nuclear energy, Inconel 625, Oxide dispersion strengthening, Laser powder bed fusion, Mechanical properties

URI

https://hdl.handle.net/11511/112663

Collections

Graduate School of Natural and Applied Sciences, Thesis