Absorption of Hydrogen by Austenitic Steels

Thin foils of austenitic stainless steels differing in chemical composition and thickness were electrolytically charged with hydrogen of either high or moderate input fugacity. The final content of hydrogen after charging and the permeation rate were measured using electrochemical techniques. Hydrogen desorption kinetics, and changes in morphology and in magnetic properties were assessed. It was found that after prolonged charging at ambient temperature, a steady state of the saturation with hydrogen of an external, severely damaged zone of steel was attained. The thickness of that zone and its final content of hydrogen after charging depended on the input fugacity of hydrogen. If a high cathodic current density was applied and arsenic was added to the electrolyte, the final concentration of hydrogen in the external zone approached the atomic ratio H/Me = 1, where Me was the sum of all metallic constituents of the alloy, iron included. An approximate correlation was observed between the final content of hydrogen and changes in the magnetic coercive force due to the hydrogen induced production of martensite.