Analysis on the sites of existence and paths of migration for hydrogen in metallic materials for structural use by means of some visualization techniques

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K05128
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 26040:Structural materials and functional materials-related
• Research Institution: Ibaraki University
• Principal Investigator: Itoh Goroh 茨城大学, 理工学研究科(工学野), 特命研究員 (80158758)
• Co-Investigator(Kenkyū-buntansha): 小林 純也 茨城大学, 理工学研究科(工学野), 講師 (20735104) ; 倉本 繁 茨城大学, 理工学研究科(工学野), 教授 (10292773)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 水素 / 可視化 / トリチウムオートラジオグラフィ / 純鉄 / 塑性変形 / 水素誘起欠陥 / 粒界 / 変形帯

Outline of Final Research Achievements

As multiple techniques to visualize the hydrogen, hydrogen microprint technique (HMPT) and tritium autoradiography (TARG) were used to comprehend the behavior of hydrogen that correlates hydrogen embrittlement in metallic materials. In pure iron, the relationship between the theories that have been proposed on hydrogen embrittlement, and the results obtained in the present study has been closely investigated. As a result, it has been concluded that lattice defects caused by plastic deformation together with hydrogen atoms are formed in consequence of the dislocation intersection in deformation bands and near grain boundaries when deformed with hydrogen charging. These lattice defects are deduced to survive even after de-hydrogenation and cause hydrogen embrittlement, which is consistent with hydrogen-enhanced strain-induced vacancy theory.

Free Research Field

金属材料工学

Academic Significance and Societal Importance of the Research Achievements

水素マイクロプリント（HMPT）法とトリチウムオートラジオグラフィ（TARG）法という2つの可視化手法を利用することにより、金属材料の水素脆化に関わる水素の挙動を捉え、水素助長ひずみ誘起空孔説を支持する結果が得られたことは、この学術分野において、長年の論争に終止符を打つという意義を持つと思われる。一方、社会的にも、水素脆化は高強度金属材料を使用する上で、克服しなければならない重要な課題であり、本研究成果はその課題克服の端緒となるという大きな意義を持つ。