Hydrogen concentration behavior around a crack tip under the constant wind rate condition simulated to a moving crack with constant rate

Clarification of the hydrogen diffusion behavior in the metal is important for prevention of hydrogen embrittlement fracture. Previously, some numerical analysis has been performed about hydrogen diffusion behavior under local stress fields by using Finite Element Method or finite difference method. On the other hand, the fatigue crack growth in air, that is, in inert atmosphere, has original speed. However, there is few analysis of hydrogen diffusion behavior including original fatigue crack growth speed. In this research, the effect of crack growth rate on hydrogen diffusion behavior around a crack tip under fatigue condition was clarified based on the numerical analysis and these analyses were conducted under various yield stress. The crack growth speed was modeled by giving uniform flow velocity to the hydrogen distribution in the whole analytical area. The upwind difference method was used for uniform flow velocity. The analytic results were compared between upwind difference and central difference.