Hydrogen Brittleness of Austenitic Steels

The electronic concept for hydrogen embrittlement (HE) of austenitic steels is developed based on the hydrogen-caused increase of the concentration of free (i.e. conduction) electrons. It is shown that, as consequence, the shear module locally decreases, which in turn leads to the decrease in the stress for activation of dislocation sources, the line tension of dislocations, the distance between the dislocations in pileups and, in consistency with the theory of hydrogen-enhanced localized plasticity (HELP), promotes the reversible hydrogen brittleness. The analysis of the electronic and elasticity approaches to HELP is carried out using the experimental data. The effect of alloying elements on the mechanical properties is studied and a concept for design of hydrogen-resistant austenitic steels is proposed.