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 |
Grain Size Evolution in a Polycrystalline Ni Base Superalloy Under Temperature and Strain Gradients
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| Author(s) |
Yonguk Lee, Victoria M. Miller |
| On-Site Speaker (Planned) |
Victoria M. Miller |
| Abstract Scope |
Control of grain size during the manufacture of polycrystalline superalloy components is critical for enhancing fatigue life. One microstructural mechanism for controlling grain size is recrystallization. While recrystallization in general has been widely researched, there is a gap in the understanding of one particular recrystallization mechanism, heteroepitaxial recrystallization. This mechanism is poorly understood in part because it was discovered less than a decade ago. In this study, the activity of the heteroepitaxial recrystallization mechanism is examined under steep strain and temperature gradients, representative of the conditions encountered during the thermomechanical forming of complex geometries. Specimens were compressed, then uniformly heat treated below the gamma prime solvus to generate a microstructure that evolved under a strain gradient. Other specimens uniformly elongated in tension were heat treated via induction to generate microstructures that evolved under a steep thermal gradient. Both sets of microstructures were then characterized using combined electron backscatter diffraction and electron dispersive spectroscopy. Microstructures that evolved after small strains resulted in coarser grain sizes than those that evolved after moderate or high strains. Exceptional grain growth, facilitated by the formation of profuse annealing twins, was observed after small strains at the highest temperatures. The implications for potential evolution of microstructure, both during manufacturing and in service, are discussed. |
| Proceedings Inclusion? |
Definite: At-meeting proceedings |