Electronic effect on hydrogen brittleness of austenitic steels

Hydrogen effects in austenitic steels are studied using the ab initio calculations of the electronic structure, conduction electron spin resonance, internal friction, and mechanical tests. It is shown that the hydrogen-caused elastic shielding of dislocations is not sufficient for interpretation of hydrogen-enhanced localized plasticity (HELP). Similar effects of hydrogen and nitrogen and the opposite effect of carbon on dislocation mobility are demonstrated, which cannot be explained within the framework of continuum mechanics. An interpretation of hydrogen embrittlement in terms of the hydrogen-increased concentration of free (conduction) electrons is proposed. Based on the electronic approach to the HELP phenomenon, practical recommendations for increase in hydrogen resistance of austenitic steels are made and tested. (C) 2010 American Institute of Physics. [doi:10.1063/1.3499610]