Abstract
Damaging of materials by hydrogen absorption cannot be overlooked in considering the influence of hydrogen on the mechanical properties of iron and steels. In the present work the mechanical properties of steel specimens, with various carbon contents and heat treatments, were examined paying attention to damage by charging of hydrogen. Stress relaxation and creep tests were carried out during electrochemical charging of hydrogen.
The results were discussed referring to the direct observations of the surface and interior of the specimens, and to the amount of hydrogen extracted in glycerine. Soft materials, i.e. low carbon and annealed ones, are easily damaged by hydrogen charging; even with an applied stress far below the yield stress, the stress relaxation and creep elongation by hydrogen charging are markedly observed. The damage is accompanied with slip deformation due to the activation of the dislocation sources by charging of hydrogen. The amount of hydrogen stored in the defects formed by hydrogen charging is, therefore, considerable in the soft materials.
