2022 Fiscal Year Final Research Report
Acceleration of diffusional transformation by applied stress and its application to microstructural control
Project/Area Number |
20H02488
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Research Category |
Grant-in-Aid for Scientific Research (B)
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Allocation Type | Single-year Grants |
Section | 一般 |
Review Section |
Basic Section 26050:Material processing and microstructure control-related
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Research Institution | National Institute for Materials Science |
Principal Investigator |
UEJI Rintaro 国立研究開発法人物質・材料研究機構, 構造材料研究拠点, 主幹研究員 (80380145)
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Co-Investigator(Kenkyū-buntansha) |
田中 克志 神戸大学, 工学研究科, 教授 (30236575)
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Project Period (FY) |
2020-04-01 – 2023-03-31
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Keywords | 構造材料 / 鉄鋼 / 相変態 / 残留応力 / 高温変形 |
Outline of Final Research Achievements |
Concerning the thermomechanical heat treatment process, which is effective for improving the mechanical properties of steel materials, the relationship between stress and transformation necessary for optimizing the process conditions was clarified. For spring steel (Fe-0.53C-1.5Si-0.8Cr-0.7Mn), electron back scattering diffraction (EBSD) measurement was performed to observe the structure after transformation. It was clarified that were miniaturized by the stress larger than the threshold stress independent with the grain size. This suggests that the promotion of diffusion transformation by stress is due to the increase in nucleation site density. Also, the elastic constants of austenite at high temperatures were measured by the resonance method of elastic constants using an elastic constant measurement system.
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Free Research Field |
材料組織学
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Academic Significance and Societal Importance of the Research Achievements |
構造用金属材料の高強度化は構造物の軽量化などに貢献する基本的課題である。一般に高強度化は靭性や延性の劣化を伴う。そのため、熱処理条件の最適化により強化相と軟質相の複合組織化を図り、実用に適した機械的性質を付与する必要がある。工業生産技術の発展に伴い、新しい指導原理に基づく複合組織化加工熱処理技術も開発され続けており、需要の規模が大きく、その社会的要望も大きい。本研究では、応力の増大に伴い拡散変態が促進されることをメカニズムとともに明らかにした。TTT図に大きな変化が見られた数秒~数百秒間で冷却が完了する製造プロセスにおいて、現実的に付与可能な小応力による新しい組織制御法の可能性を見出した。
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