initiation and propagation of intergranular stress corrosion cracking

• Project/Area Number: 17H04899
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Materials/Mechanics of materials
• Research Institution: Shizuoka University
• Principal Investigator: Fujii Tomoyuki 静岡大学, 工学部, 准教授 (30377840)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Project Status: Completed (Fiscal Year 2020)
• Budget Amount: ¥24,440,000 (Direct Cost: ¥18,800,000、Indirect Cost: ¥5,640,000); Fiscal Year 2020: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000); Fiscal Year 2019: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000); Fiscal Year 2018: ¥3,120,000 (Direct Cost: ¥2,400,000、Indirect Cost: ¥720,000); Fiscal Year 2017: ¥16,250,000 (Direct Cost: ¥12,500,000、Indirect Cost: ¥3,750,000)
• Keywords: 応力腐食割れ / 粒界 / 応力 / ひずみ / 応力拡大係数 / ステンレス鋼 / き裂 / 粒界腐食 / 電気化学ノイズ / その場観察 / 環境強度 / 微視組織 / 転位密度 / き裂発生 / き裂進展 / 粒界性格

Outline of Final Research Achievements

The present study elucidated the processes of SCC initiation and growth in stainless steels subjected to tension in a corrosive environment to evaluate their SCC life. SCC initiates and grows at grain boundaries (GBs) with high susceptibility to intergranular corrosion. Crack initiation is characterized by normal strain at a GB on the surface of the material, which is caused by stress/strain concentration due to dislocation pile-up near GBs under tensile loading. Crack propagation rate can be formulated using the stress intensity factor K and its gradient dK/da.

Academic Significance and Societal Importance of the Research Achievements

本研究では，ステンレス鋼に生じるＳＣＣの発生および進展条件を明らかにした．ＳＣＣの発生には，力学および粒界構造に関する条件が必要であり，それらを排除することで耐ＳＣＣ性を有する材料の設計に生かすことが可能である．さらに，ＳＣＣ進展式を提案したことから，高精度な寿命予測が可能となる．これらの結果は，高経年化した機械構造物の健全性確保に資する．

Research Products

• [Journal Article] Mechanical criterion for nucleation of intergranular stress corrosion cracking in austenitic stainless steel (2021)
  • Author(s): Fujii Tomoyuki、Sawada Tatsuro、Tohgo Keiichiro、Shimamura Yoshinobu
  • Journal Title: Forces in Mechanics Volume: 3 Pages: 100013-100013
  • DOI: 10.1016/j.finmec.2021.100013
  • Peer Reviewed / Open Access
• [Journal Article] Analysis of the early stage of stress corrosion cracking in austenitic stainless steel by EBSD and XRD (2021)
  • Author(s): Fujii Tomoyuki、Yamakawa Ryohei、Tohgo Keiichiro、Shimamura Yoshinobu
  • Journal Title: Materials Characterization Volume: 172 Pages: 110882-110882
  • DOI: 10.1016/j.matchar.2021.110882
  • NAID: 120007151899
  • Peer Reviewed
• [Journal Article] Crystallographic Evaluation of Susceptibility to Intergranular Corrosion in Austenitic Stainless Steel with Various Degrees of Sensitization (2020)
  • Author(s): Fujii Tomoyuki、Furumoto Takaya、Tohgo Keiichiro、Shimamura Yoshinobu
  • Journal Title: Materials Volume: 13 Issue: 3 Pages: 613-613
  • DOI: 10.3390/ma13030613
  • NAID: 120006816587
  • Peer Reviewed / Open Access
• [Journal Article] Strain-based approach to investigate intergranular stress corrosion crack initiation on a smooth surface of austenitic stainless steel (2019)
  • Author(s): Fujii Tomoyuki、Yamakawa Ryohei、Tohgo Keiichiro、Shimamura Yoshinobu
  • Journal Title: Materials Science and Engineering: A Volume: 756 Pages: 518-527
  • DOI: 10.1016/j.msea.2019.04.083
  • NAID: 120006644918
  • Peer Reviewed / Open Access
• [Journal Article] Crystallographic and mechanical investigation of intergranular stress corrosion crack initiation in austenitic stainless steel (2019)
  • Author(s): Tomoyuki Fujii, Keiichiro Tohgo, Yota Mori, Yutaro Miura, and Yoshinobu Shimamura
  • Journal Title: Materials Science & Engineering A Volume: 751 Pages: 160-170
  • DOI: 10.1016/j.msea.2019.02.069
  • NAID: 120006606182
  • Peer Reviewed
• [Journal Article] Crystallography of intergranular corrosion in sensitized austenitic stainless steel (2018)
  • Author(s): Tomoyuki Fujii, Keiichiro Tohgo, Yota Mori, and Yoshinobu Shimamura
  • Journal Title: Materials Characterization Volume: 144 Pages: 219-226
  • DOI: 10.1016/j.matchar.2018.07.014
  • NAID: 120006533612
  • Peer Reviewed
• [Journal Article] Characterization of stress corrosion crack growth in austenitic stainless steel under variable loading in small- and large-scale yielding conditions (2018)
  • Author(s): Tomoyuki Fujii, Keiichiro Tohgo, Motohiro Kawamori, and Yoshinobu Shimamura
  • Journal Title: Engineering Fracture Mechanics Volume: 205 Pages: 94-107
  • DOI: 10.1016/j.engfracmech.2018.11.020
  • NAID: 120006549590
  • Peer Reviewed
• [Presentation] Investigation of intergranular stress corrosion cracking based on X-ray diffraction analysis (2019)
  • Author(s): Ryohei Yamakawa, Tomoyuki Fujii, Keiichiro Tohgo, and Yoshinobu Shimamura
  • Organizer: The 6th Joint-Symposium on Mechanics of Advanced Materials & Structures (JSMAMS 2019)
  • Int'l Joint Research
• [Presentation] 局所ひずみに基づく粒界型応力腐食割れ発生条件の検討 (2019)
  • Author(s): 藤井朋之，山川椋平，東郷敬一郎，島村佳伸
  • Organizer: M&M2019材料力学カンファレンス
• [Presentation] Nucleation of intergranular stress corrosion cracking based on surface strain distribution measured by DIC (2018)
  • Author(s): Ryohei Yamakawa, Tomoyuki Fujii, Keiichiro Tohgo, and Yoshinobu Shimamura
  • Organizer: The 14th Asia-Pacific Symposium on Engineering Plasticity and Its Applications (AEPA2018)
  • Int'l Joint Research
• [Presentation] 材料表面のひずみ分布に基づく応力腐食割れの発生挙動評価 (2018)
  • Author(s): 山川椋平，藤井朋之，東郷敬一郎，島村佳伸
  • Organizer: M&M2018材料力学カンファレンス
• [Presentation] Fracture mechanics approach to stress corrosion crack growth in sensitized austenitic stainless steel (2017)
  • Author(s): Tomoyuki Fujii, Keiichiro Tohgo, Motohiro Kawamori, Yoshinobu Shimamura
  • Organizer: The 5th Joint Symposium on Mechanics of Advanced Materials and Structures (JSMAMS2017)
  • Int'l Joint Research
• [Presentation] オーステナイト系ステンレス鋼の粒界型応力腐食割れ発生挙動 (2017)
  • Author(s): 藤井朋之, 東郷敬一郎, 森要太, 島村佳伸
  • Organizer: M&M2017材料力学カンファレンス
• [Remarks] 静岡大学工学部 機械工学科 島村・藤井研究室
  • URL: https://mechmat.eng.shizuoka.ac.jp/
• [Remarks] 東郷・島村・藤井研究室
  • URL: https://mechmat.eng.shizuoka.ac.jp/
• [Remarks] 静岡大学大学院工学研究科 機械工学専攻 藤井朋之
  • URL: https://mechmat.eng.shizuoka.ac.jp/~tofujii/