Interaction of hydrogen with dislocation pile-ups and hydrogen induced softening of pure iron

The equations for the equilibrium in a simple dislocation pile-up taking into account the shielding effects of hydrogen atmospheres were obtained. The analysis of the experimental results of hydrogen softening in high-purity iron using the obtained equations showed that the hydrogen shielding of elastic stresses in a simple dislocation pile-up is insufficient to account for the observed effects and the real data. Significant effects of softening observed experimentally in pure iron during electrochemical hydrogen charging in tensile loading can not be accounted for by the effects of shielding of elastic fields of dislocation pile-ups by hydrogen. They are more likely caused by the hydrogen enhanced non-conservative processes of dislocation climb in the dipole type dislocation pile-ups.