Elucidation of the relationship between resistance to hydrogen embrittlement and the structure of surface oxide film

2015 Fiscal Year Final Research Report

• Project/Area Number: 25420750
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Structural/Functional materials
• Research Institution: Ibaraki University
• Principal Investigator: Itoh Goroh 茨城大学, 工学部, 教授 (80158758)
• Co-Investigator(Kenkyū-buntansha): ITOH NOBUHIDE 茨城大学, 工学部, 教授 (70203156)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 表面酸化皮膜 / 水素 / アルミニウム合金 / 塑性変形 / 粒界 / すべり線

Outline of Final Research Achievements

In ferritic steels, it was found that the surface oxide film is not a crucial barrier for hydrogen emission. In an Al-9%Mg alloy, hydrogen emission was observed in some of the grain boundaries as well as slip bands when specimen was deformed in tension. At the grain boundaries where hydrogen was emitted, it was presumed that the hydrogen was transported with slipping in a neighboring grain, with a formation of the surface step causing the fracture of the surface oxide film, and then emitted. In an Al-Zn-Mg alloy, similar result was obtained but the deformation was localized near the grain boundaries because of the presence of the precipitate free zones, and hence hydrogen was emitted at grain boundaries with more variety. Therefore, it was concluded that the surface oxide film plays an important role in hydrogen intrusion and emission.

Free Research Field

機械金属材料学