Evaluation of hydrogen distribution at vicinity of a crack employing a local strain measurement

2016 Fiscal Year Final Research Report

• Project/Area Number: 15K17930
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Materials/Mechanics of materials
• Research Institution: Kyushu University (2016); Tohoku University (2015)
• Principal Investigator: Takakuwa Osamu 九州大学, 水素材料先端科学研究センター, 特任准教授 (60633518)
• Project Period (FY): 2015-04-01 – 2017-03-31
• Keywords: 水素脆化

Outline of Final Research Achievements

Hydrogen concentrating around a crack tip significantly accelerates crack propagation, i.e., hydrogen embrittlement. In order to clarify the mechanism leading to this, the local hydrogen concentration behavior, i.e., at a crack tip, was evaluated by numerical analysis and experimental measurements. Although thermal desorption analysis can be used to evaluate the total hydrogen content in metals, it cannot be applied to local areas. Microprint methods, which use chemical reactions between hydrogen and coated elements cannot quantitatively evaluate the hydrogen content. The present study takes account of hydrogen-induced strain, and X-ray diffraction in a confined area was employed to detect variations in lattice spacing before and after hydrogen charging. Using X-ray diffraction applied to a small area, it was demonstrated that the hydrogen concentrates in the vicinity of the crack, i.e., at the elastic-plastic boundary.

Free Research Field

材料力学