Characterization of Crack Nucleation in Titanium Alloys with Metastable Microstructures
| Project/Area Number |
20F40737
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| Research Category |
Grant-in-Aid for JSPS Fellows
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| Allocation Type | Single-year Grants |
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| Section | 外国 |
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| Review Section |
Basic Section 18010:Mechanics of materials and materials-related
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| Research Institution | Kyushu University |
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Principal Investigator |
陳 強 九州大学, 工学研究院, 教授 (30264451)
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| Co-Investigator(Kenkyū-buntansha) |
LIU HANQING 九州大学, 工学(系)研究科(研究院), 外国人特別研究員
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| Project Period (FY) |
2020-11-13 – 2023-03-31
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| Project Status |
Completed (Fiscal Year 2022)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 2022: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2021: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2020: ¥600,000 (Direct Cost: ¥600,000)
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| Keywords | Titanium alloy / Metastable / Electron Beam Welding / Fatigue / Crack nucleation / Slip deformation / Twinning / Recrystallization / Phase transformation / Titanium Alloy / Crack Nucleation |
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| Outline of Research at the Start |
チタン合金は高強度ゆえに耐熱性にも優れるため自動車や航空機業界に広く応用されており「革新的構造材料」として注目を浴びている。しかし、チタン合金の疲労信頼性とりわけ準安定構造を持つチタン合金の寿命評価法が確立されておらず、喫緊の課題である。本研究では、チタン合金の超高サイクル疲労き裂の発生および伝ぱ挙動に着目し、そのき裂発生のメカニズムに及ぼす準安定構造の影響を最新鋭走査透過電子顕微鏡（STEM/HAADF）法による原子尺度での構造解析に基づいて明らかにすることであり、超高サイクル疲労における疲労寿命の評価法の確立を目指すものである。
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| Outline of Annual Research Achievements |
Definitive evidence for the nanostructured process within FGA is provided by a multi-scale characterization of the nanograin orientation, grain rotation, and the lattice strain up to atom scale by utilizing the transmission Kikuchi diffraction (TKD) and aberration-corrected scanning transmission electron microscope. Direct aging treatment can be used to optimize the mechanical properties of the weldment by decomposition of the thermal martensites and precipitation of the nano lamellar alpha structure within the coarse beta grain, thereby enhancing the crack nucleation resistance. Cracking interfaces of the oxidation domain and topmost nanograins facilitate surface degradation, thereby promoting the stress mismatch along the contact area boundary and giving rise to the formation of macrocrack thereafter with the assistance of oxygen pick-up at the crack tip.
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| Research Progress Status |
令和4年度が最終年度であるため、記入しない。
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| Strategy for Future Research Activity |
令和4年度が最終年度であるため、記入しない。
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Report
(3 results)
Research Products
(10 results)
