Investigation on Tensile Behavior of Solid Solution-Strengthened Ni-Co-Cr-Based Superalloy During Long-Term Aging
This study investigated how long-term aging (750 °C and 950 °C) affects the microstructure and room-temperature tensile properties of the Ni-Co-Cr superalloy GH3617. Characterization (SEM, EDS, EBSD) showed that initial aging (750 °C, 500 h) formed discontinuous M<sub>23</sub>C<sub>...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-06-01
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| Series: | Crystals |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2073-4352/15/7/617 |
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| Summary: | This study investigated how long-term aging (750 °C and 950 °C) affects the microstructure and room-temperature tensile properties of the Ni-Co-Cr superalloy GH3617. Characterization (SEM, EDS, EBSD) showed that initial aging (750 °C, 500 h) formed discontinuous M<sub>23</sub>C<sub>6</sub> carbides, pinning grain boundaries and improving strength. Prolonged aging (750 °C, 5000 h) caused M<sub>23</sub>C<sub>6</sub> to coarsen into brittle chain-like structures (width up to 1.244 μm) and precipitated M<sub>6</sub>C carbides, degrading grain boundaries. Aging at 950 °C accelerated this coarsening via LSW kinetics (rate constant: 6.83 × 10<sup>−2</sup> μm<sup>3</sup>/s), with Mo segregation promoting M<sub>6</sub>C formation. Tensile properties resulted from competing γ′ precipitation strengthening (post-aging strength increased up to 23.3%) and grain boundary degradation (elongation dropped from 70.1% to 43.3%). Fracture shifted from purely intergranular (cracks along M<sub>23</sub>C<sub>6</sub>/γ interfaces at 750 °C) to mixed mode (cracks initiated by M<sub>6</sub>C fragmentation at 950 °C). These insights support superalloy microstructure optimization and lifetime prediction. |
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| ISSN: | 2073-4352 |