2000 Fiscal Year Final Research Report Summary
Development of Repairing Processes for of Single Crystal Turbine Blade using a phase-field model
| Project/Area Number |
10555242
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Material processing/treatments
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| Research Institution | the University of Tokyo |
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Principal Investigator |
SUZUKI Toshio the University of Tokyo, School of Engineering, Professor, 大学院・工学系研究科, 教授 (70115111)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHINARI Akira Hitachi Co. Ltd., Hitachi Institute Researcher, 日立研究所, 主任研究員
OKAZAKI Masakazu the University of Tokyo, School of Engineering, Associate professor, 大学院・工学系研究科, 助教授 (00134974)
MAEDA Masafumi the University of Tokyo, Institute of Industrial Science, Professor, 生産技術研究所, 教授 (70143386)
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| Project Period (FY) |
1998 – 2000
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| Keywords | Ni-based super alloy / turbine blade / repairing / recrystallization / Fe-C alloy |
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| Research Abstract |
In the repairing of a single crystal turbine blade, the repairing material should be the same as the blade for preventing the decrease of creep resistance. It is also necessary to obtain the continuously single-crystallized structure by depressing the grain boundaries and cracks formed during the repairing process. In the part of the turbine blade where the repairing is needed, there remains the retained strain by mechanical damages, which sometimes causes a new grain or colony structure. Therefore the stress and repairing conditions should be appropriately controlled. In the present work, the process and mechanism of the grain or colony formation at the region during the heat treatment after repairing have been investigated. From the experimental results, it is shown that the colony structure is the re-crystallized one and that the fatigue crack propagates along the newly formed grain boundary. Since the fracture resistance is low at the boundary, the fatigue life decreases once the boundary is formed. It is also shown that an anti-corrosion coating including boundary-strengthen elements prevents the reduction of fatigue life. A new non-destructive detection using a ultra sonic wave has been proposed and its applicability for the degraded structure in the turbine blade has been demonstrated.
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