Hydrogen is expected as anext-generation energy to reduce dependence on fossil energy and atmospheric contamination. Hydrogen-powered fuel cell vehicles and stationary fuel cell systems are typical applications for hydrogen usage. However, it is well-known that hydrogen enter metallic materials and degrades the mechanical properties; so-called "hydrogen embrittlement". We have been carrying out research on the effects of hydrogen gas environment on the fatigue crack growth behavior to establish the evaluation method for the crack growth rate. Rational evaluation method requires the mechanism of hydrogen effects on the crack growth behavior. In order to elucidate the mechanism of hydrogen effects on the crack growth behavior, we conduct in-situ observation by high magnification on the crack growth behavior in low hydrogen gas environment.
|Crack growth rate||Propagating fatigue crack|
Hydrogen-Enhanced Localized Plasticity (HELP) is known to play a key role on hydrogen embrittlement. In this study, we quantitatively clarify an aspect of hydrogen embrittlement mechanism through finite element simulation.
The HELP phenomenon mentioned above shows various behaviours at different scales: micro- (nm ~ μm), meso- (μm~mm), and macro- (mm~) scopic scales. In this study, we artificially introduce hydrogen with different degrees of hydrogen locality, and observe various types of HELP to clarify the multi-scale HELP effect.