Cyclic response-electrochemical interaction in mono- and polycrystalline AISI 316L stainless steel in H 2SO 4 solution—III. Potential dependence of the mechanical behavior during corrosion fatigue

Abstract

Measurements of mechanical parameters and surface examinations have been carried out on mono- and polycrystalline specimens of an AISI 316L stainless steel which were cycled in a 1 N H 2SO 4 solution. Analysis was made in relation to both the number of cycles and the applied potentials. The environment was found to have no influence on such bulk properties as the softening rate and flow stress, because the oxide film on the stainless steel is very thin. The magnitude of the strain localization was enhanced by preferential dissolution of atoms in the slip bands, a tendency which decreased with increas in potential. Crack nucleation within the slip bands was caused by either the high dissolution rate imposed by the applied potentials (in the corrosion and the transition regions) or by the galvanic effect (in the passive I region). General corrosion was found to have major effects on the crack propagation process in both the corrosion region, where blunting inhibited propagation, and the transition region where corrosion-stimulated “sharpening” promoted propagation. In the passive II region, environment-assisted strain localization and the galvanic effect were prevented by the stable passive film and the rapid passivation reaction.