The influence of cyclic plastic deformation on electrode reactions on mild steel in aqueous chloride solutions of varying pH

Abstract

An attempt has been made to study the operative mechanisms which cause the corrosion-fatigue failure of mild steel in marine environments. To achieve this the influence of dynamic cyclic plastic strain on the electrode reactions on mild steel in 0.6 M (3.5% NaCl) at various pH levels has been investigated. Dynamic tensile and compressive strains were observed to enhance significantly both anodic and cathodic reactions. At open-circuit potentials in solutions of pH 1–11 where corrosion-fatigue failure is known to occur, the anodic reaction is stimulated significantly more than the cathodic reaction. At pH 1, where the corrosion-fatigue life is a minimum, the observed dissolution effects are greatest; at other pH values an inverse relationship exists between dissolution effects and corrosion-fatigue endurance. At pH 12, where the material exhibits its dry fatigue properties, enhanced dissolution effects were found to decrease rapidly with progressive strain cycling. It would appear therefore that a link has been established in this system between strain-enhanced dissolution and corrosion-fatigue properties.