About this Abstract |
| Meeting |
11th International Symposium on Superalloy 718 and Derivatives 2026: Legacy, Innovations, and Future Directions
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| Symposium
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Superalloy 718 and Derivatives 2026: Legacy, Innovations, and Future Directions
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| Presentation Title |
Mechanical Properties and Microstructure of Irradiated Superalloy 718 With High Concentrations of Hydrogen and Helium |
| Author(s) |
David McClintock, Maxim Gussev, Tim Lach, Soyoung Kang, Wei Lu, Frank Garner |
| On-Site Speaker (Planned) |
David McClintock |
| Abstract Scope |
The microstructure and mechanical properties of structural components in high-energy radiation environments are altered during operation and typically manifest as an increase in strength commensurate with a decrease in both ductility and fracture toughness, which limit the component’s useful lifetime due to embrittlement concerns. Lifetime limits for these components are difficult to define without experimental results for a particular material and radiation environment of interest. Post irradiation examination (PIE) of components after removal from service is the best method for characterizing the radiation-induced changes to mechanical properties and microstructure. A PIE program is maintained at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) for proton beam windows (PBW) and targets to characterize radiation-induced changes and inform decisions on administrative lifetime limits. Superalloy 718 is used for the window material in PBWs at the SNS due to its high strength, corrosion resistance, and use at other nuclear facilities. Previous tensile testing and microscopy of samples from a 718 PBW showed an increase in ductility with increasing dose and small (1-3 nm) nanocavities enriched in transmutation products hydrogen and helium. Recently, tensile tests and microstructure characterizations were performed on PIE samples removed from a solution-annealed 718 PBW operated to a maximum dose of approximately 19.6 displacements per atom (dpa) and transmutation product concentrations of 3950 appm helium and 15,300 appm hydrogen. The results from tensile testing and microstructure characterization will be presented, and the lifetime limit philosophy employed for Superalloy 718 PBWs at the SNS will be discussed. |
| Proceedings Inclusion? |
Definite: At-meeting proceedings |