Quantitative Evaluation of residual life of heat-resistant alloy under random creep-fatigue loadings at elevated temperature

2023 Fiscal Year Annual Research Report

• Project/Area Number: 21H01205
• Research Institution: Tohoku University
• Principal Investigator: 三浦 英生 東北大学, 工学研究科, 教授 (90361112)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 高音強度 / クリープ疲労損傷 / 原子配列の秩序性 / 電子線後方散乱回折 / 粒界割れ

Outline of Annual Research Achievements

本研究では各種高効率エネルギープラントで応用される最先端耐熱合金の高温クリープ疲労損傷の支配因子を定量的な解明した．クリープ疲労損傷ではほぼ全ての粒界で割れが発生しており，著しい劣化の加速が生じている．この劣化は，粒界への炭化物や酸化物の偏析により加速されることも明らかにした．この劣化損傷の進行過程は，構造材料の高温高負荷環境における劣化損傷が材料を構成する構成原子の式(1)に示す応力依存の異方的増速原子拡散現象に基づき発生することを明らかにした．
D = D0exp{-(Q-σV)/kT}　　　　　… (1)
ここでDは拡散定数，D0は定数，Qは熱力学的に定義される平衡状態での活性化エネルギー，σは作用する応力，Vは等価体積，kはボルツマン定数，Tは絶対温度である．応力は引張応力が正の値，圧縮応力が負の値を示す．本式が適用される化学反応（核の発生や拡散）現象は引張応力の作用で加速され，圧縮応力の作用で抑制されることになる．本式を転位や原子空孔の発生や拡散，各種析出物の発生等に適用し，温度と機械的な応力の連成現象として材料組織の劣化機構を解明した．さらに，結晶粒界近傍や母相と析出物間の格子不整合に起因した局所歪み場の存在も局所応力場評価に取り込み，外力と内部歪み場による内力を統合した機械的応力場の解析も加え，クリープ疲労損傷を機械的な損傷に留まらず，化学的な組織変化に起因した応力歪み場との連成損傷と位置づけ，式（１）の応力を時間の関数とし，時間積分することで使用条件に依存した劣化進行の定量的な評価法を提案した．さらに分子動力学解析手法を応用し，電子線後方散乱解析から得られるIQ値の物理化学的意味づけとして原子レベルの欠陥密度との対応性を示した．転位や空孔分布に依存した原子配列の秩序性の劣化と粒界強度の低下の相関関係を定量的に予測評価する手法も提案した．

Research Progress Status

令和5年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

令和5年度が最終年度であるため、記入しない。

Research Products

• [Int'l Joint Research] East China U. of Science and Technology/U. of Science and Technology Beijing/Tsinghua University(中国)
  • Country Name: CHINA
  • Counterpart Institution: East China U. of Science and Technology/U. of Science and Technology Beijing/Tsinghua University
• [Journal Article] Acceleration of Creep-Fatigue Damage of Ni-Base Alloy by Viscoelasticity at Elevated Temperature (2024)
  • Author(s): 5)Hideo Miura, Ayane Yasumura, Takuma Yamawaki, Takuto Kudo, Hayato Matsuda, Le, Xu
  • Journal Title: Mechanics of Solids, Structures and Fluids Volume: 11 Pages: V011T12A021
  • DOI: 10.1115/IMECE2023-112200
  • Peer Reviewed / Open Access
• [Journal Article] Surrogate-modeling-assisted creep-fatigue reliability assessment in a low-pressure turbine disc considering multi-source uncertainty (2023)
  • Author(s): Wang, Run-Zi, Gu, Hang-Hang, Liu, Yu, Miura, Hideo, Zhang, Xian-Cheng, Tu, Shan-Tung
  • Journal Title: RELIABILITY ENGINEERING & SYSTEM SAFETY Volume: 240 Pages: 109550
  • DOI: 10.1016/j.ress.2023.109550
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Microstructural evolutions and life evaluation of non-proportional creep-fatigue considering loading path and holding position effects (2023)
  • Author(s): Xu, Le, Wang, Run-Zi, Wang, Yu-Chen, He, Lei, Itoh, Takamoto, Suzuki, Ken, Miura, Hideo, Zhang, Xian-Cheng
  • Journal Title: MATERIALS CHARACTERIZATION Volume: 204 Pages: 113209
  • DOI: 10.1016/j.matchar.2023.113209
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Acceleration mechanism of the degradation of the lifetime of Ni-based superalloys under creep-fatigue loading at elevated temperatures (2023)
  • Author(s): Luo, Yifan, Takahashi, Yukako, Nakayama, Koki, Nakayama, Ayumi, Suzuki, Ken, Miura, Hideo
  • Journal Title: FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES Volume: 46 Pages: 3043-3059
  • DOI: 10.1111/ffe.14013
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Evaluation of fatigue and creep-fatigue damage levels on the basis of engineering damage mechanics approach (2023)
  • Author(s): Sun, Li, Zhang, Xian-Cheng, Wang, Run-Zi, Wang, Xiao-Wei, Tu, Shan-Tung, Suzuki, Ken, Miura, Hideo
  • Journal Title: INTERNATIONAL JOURNAL OF FATIGUE Volume: 166 Pages: 107277
  • DOI: 10.1016/j.ijfatigue.2022.107277
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] High Strain-Rate-induced Acceleration of Creep-Fatigue Damage in Ni-base Superalloys at Elevated Temperature (2023)
  • Author(s): Hideo MIURA
  • Organizer: ESIA17 FESI/CSIC International Conference
  • Int'l Joint Research / Invited
• [Presentation] Degradation of Integrity of Thin-Film Interfaces in Advanced Electronic Devices Caused by Point Defects and Strain (2023)
  • Author(s): Hideo MIURA
  • Organizer: Advanced Technology in Experimental Mechanics 2023
  • Int'l Joint Research / Invited
• [Presentation] Creep-fatigue crack nucleation criterion for crystallographic evolutions based on damage mechanics descriptions (2023)
  • Author(s): Run-Zi WANG
  • Organizer: 13th International Fatigue Congress
  • Int'l Joint Research
• [Presentation] Acceleration of Creep-Fatigue Damage due to viscoelasticity by considering local stress evaluation at elevated temperature (2023)
  • Author(s): Le XU
  • Organizer: 13th International Fatigue Congress
  • Int'l Joint Research
• [Presentation] Acceleration Mechanism of Intergranular Cracking of Stainless Steel SUS316LN at Elevated Temperature Caused by Local Strain Energy Around Grain Boundaries (2023)
  • Author(s): Ayane YASUMURA
  • Organizer: 13th International Fatigue Congress
  • Int'l Joint Research
• [Presentation] Nondestructive Observation of the Change of Micro texture of Ni-base Superalloys under Creep-Fatigue Loading at Elevated Temperature in the Atmosphere (2023)
  • Author(s): Hayato MATSUDA
  • Organizer: Advanced Technology in Experimental Mechanics 2023
  • Int'l Joint Research
• [Presentation] Molecular Dynamics Analysis of the Acceleration Mechanism of the Degradation of Grain Boundary Strength in Alloy GH4169 Caused by δ-Phase Precipitation (2023)
  • Author(s): Takuto KUDO
  • Organizer: 13th International Fatigue Congress
  • Int'l Joint Research
• [Presentation] Molecular dynamics analysis of the effect of strain rate on accelerated degradation of grain boundary quality under high temperature fatigue loading molecular dynamics analysis (2023)
  • Author(s): Takuma YAMAWAKI
  • Organizer: 13th International Fatigue Congress
  • Int'l Joint Research
• [Remarks] 東北大学 三浦・鈴木研究室
  • URL: http://www.miura.rift.mech.tohoku.ac.jp