The Effect of Mechanical Factors on Hydrogen Diffusion and Concentration around a Crack Tip

Recently, the researches of hydrogen energy have been developed. However, the hydrogen penetrates into the metal and it causes hydrogen embrittlement. Concerning the investigation of hydrogen embrittlement, in spite of the fact that stile studies have been conducted for many years, the mechanism of hydrogen embrittlement has not yet been clarified. For example, hydrogen embrittlement is typical for steels used for a petroleum-refining reactor. This will be due to the following reason. Hydrogen penetrates from a container wall surface when a petroleum-refining reactor operates under high temperature and pressurized hydrogen environmental conditions. Major part of the hydrogen remain in the wall for a long time during cooling process when the reactor is out of operation, which results in the delayed fracture [1,2]. Therefore, clarification of the hydrogen diffusion behavior in the metal is important for prevention of hydrogen embrittlement fracture. To clarify the behavior