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This study proposes a novel mechanism of intergranular fracture in alpha-iron, focusing on the effects of trapped vacancies, H atoms, and their synergistic interplay under tensile strain. We present a methodology for the introduction of H into grain boundaries (GBs) resulting in a realistic distribution by considering H – H interactions. Accordingly, optimal H concentrations were determined under specific environmental conditions for GBs with and without vacancy-induced segregation under zero and 2% tensile strain, respectively. Subsequently, the reduction in cohesive energy at GBs was evaluated at the optimal H concentration under these conditions. In the case of H segregation without vacancies at zero applied strain, the reduction in the cohesive energy ranged approximately from 15% to 35% for all the GB configurations. Eventually, vacancy segregation increased H concentration at the GBs, defined as vacancy-induced H segregation. The vacancy-induced H segregation resulted in a 60%–117% increase in H concentration and a 70%–80% decrease in cohesive energy at a vacancy concentration of 7.491/nm2 under zero applied strain. The proposed vacancy-induced H-segregation mechanism explained the delayed fracture in steel. Furthermore, the effect of tensile strain on embrittlement was elucidated, with strain-induced vacancy redistribution and vacancy-induced H segregation synergistically promoting GB decohesion, resulting in a 73%–93% reduction in cohesive energy at the same vacancy concentration.

権利情報:

• Creative Commons BY Attribution 4.0 International
  

キーワード: Intergranular failure, Iron, Tensile behavior, Hydrogen, Vacancy-induced

刊行年月日: 2025-12-31

出版者: Taylor & Francis

掲載誌:

• Science and Technology of Advanced Materials (ISSN: 14686996) vol. 26 2459060

研究助成金:

原稿種別: 著者最終稿 (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.5322

公開URL: https://doi.org/10.1080/14686996.2025.2459060

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更新時刻: 2025-07-16 16:17:06 +0900

MDRでの公開時刻: 2025-02-13 12:30:18 +0900