Abstract
Hydrogen energy society has required for lower cost BCC metals with high-resistance to hydrogen environmental degradation instead of FCC metals with higher cost. However, BCC metals such as steels have higher degradation susceptibility than FCC metals, then the susceptibility must be improved. In the present study, the identification of lattice defect affecting the hydrogen environmental degradation has been investigated using pure iron emphasizing vacancy and dislocation, since the influence of other elements and inclusions is almost negligible.
