The Effects of Long-Term High-Temperature Aging on the Microstructural Evolution and Impact Fracture Behavior of Inconel 625 Superalloy.
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| Title: | The Effects of Long-Term High-Temperature Aging on the Microstructural Evolution and Impact Fracture Behavior of Inconel 625 Superalloy. |
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| Authors: | Li, Zhining1 (AUTHOR), Li, Kejian1,2 (AUTHOR), Wu, Yao1 (AUTHOR), Cai, Zhipeng1,2 (AUTHOR), Liu, Qu1,2 (AUTHOR) liuqu@mail.tsinghua.edu.cn |
| Source: | Materials (1996-1944). May2026, Vol. 19 Issue 10, p1932. 14p. |
| Subjects: | Inconel, Microstructure, Impact response, Precipitation (Chemistry), Carbides |
| Abstract: | Inconel 625 is widely used in high-temperature structural components because of its excellent strength, toughness, and corrosion resistance. However, long-term exposure to elevated temperatures can induce precipitation of carbides, γ″ phase, and δ phase, leading to microstructural degradation and reduced mechanical reliability. Although precipitation evolution and tensile properties of aged Inconel 625 have been widely studied, the relationship between long-term precipitate evolution and impact fracture behavior remains insufficiently clarified. In this study, solution-treated Inconel 625 alloy was aged at 700 °C and 750 °C for up to 5000 h, with additional stress-assisted aging at 750 °C under 30 MPa and 51 MPa. Impact toughness, microhardness, fracture morphology, and precipitate evolution were systematically investigated. The results show that long-term aging significantly reduces impact toughness at both room and elevated temperatures, with a more pronounced reduction at room temperature. The room-temperature impact energy decreases from 314 J to approximately 10 J and stabilizes after 2000 h. Quantitative analysis shows that γ″ precipitate coarsening follows the Lifshitz–Slyozov–Wagner relationship, indicating diffusion-controlled growth. Stress-assisted aging under the present low stress levels has only a limited influence on precipitate evolution and impact toughness. The toughness degradation is mainly attributed to chain-like grain-boundary carbides and needle-like or plate-like δ phase, which embrittle grain boundaries, segment the austenitic matrix, and limit impact energy absorption. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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| Abstract: | Inconel 625 is widely used in high-temperature structural components because of its excellent strength, toughness, and corrosion resistance. However, long-term exposure to elevated temperatures can induce precipitation of carbides, γ″ phase, and δ phase, leading to microstructural degradation and reduced mechanical reliability. Although precipitation evolution and tensile properties of aged Inconel 625 have been widely studied, the relationship between long-term precipitate evolution and impact fracture behavior remains insufficiently clarified. In this study, solution-treated Inconel 625 alloy was aged at 700 °C and 750 °C for up to 5000 h, with additional stress-assisted aging at 750 °C under 30 MPa and 51 MPa. Impact toughness, microhardness, fracture morphology, and precipitate evolution were systematically investigated. The results show that long-term aging significantly reduces impact toughness at both room and elevated temperatures, with a more pronounced reduction at room temperature. The room-temperature impact energy decreases from 314 J to approximately 10 J and stabilizes after 2000 h. Quantitative analysis shows that γ″ precipitate coarsening follows the Lifshitz–Slyozov–Wagner relationship, indicating diffusion-controlled growth. Stress-assisted aging under the present low stress levels has only a limited influence on precipitate evolution and impact toughness. The toughness degradation is mainly attributed to chain-like grain-boundary carbides and needle-like or plate-like δ phase, which embrittle grain boundaries, segment the austenitic matrix, and limit impact energy absorption. [ABSTRACT FROM AUTHOR] |
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| ISSN: | 19961944 |
| DOI: | 10.3390/ma19101932 |
