Font Size: 

In hydrogen diffusion in metals, we have to consider not only the hydrogen flux
driven by hydrogen concentration but also the hydrogen flux driven by
hydrostatic stress. Such hydrogen diffusion is a multi-physics problem coupled
hydrogen diffusion with a stress field. We developed a three-dimensional
computer program for a transient hydrogen diffusion analysis by combining an inhouse
three-dimensional finite element program for a hydrogen diffusion analysis
with a general-purpose finite element computer program for a stress analysis.
Using this computer program, we performed transient diffusion analyses of a
surface crack in a finite plate under tensile load or bending moment, and clarified
the hydrogen concentration around the periphery of a surface crack. We also made
a discussion on the effect of hydrogen on the crack growth behavior under cyclic
loading. As a result, it is concluded that hydrogen does not have a harmful effect
on the leak-before-break.