“…Since then, the effect of H-assisted degradation has been widely researched and explained [11,35,213,241]. However, the underlying mechanisms are still being discussed with numerous theories suggested and extensively reviewed [30,123,138,169,178,227]. Due to complexity of the HE phenomena, it is required to have knowledge of the hydrogen interactions on the metal surface, how it enters the metal, its transport through the crystal lattice, its interaction with crystal defects (vacancies, dislocations, grain boundaries, solutes) and precipitates, inclusions, interfaces, etc., and most importantly, its effect on the modification of material properties.…”