Kelvin probe measurements of the corrosion potential of low-alloy steels in dry-wet cycles

Corrosion potentials of a mild steel and low-alloy steels containing Cr have been examined under humidity films and under very thin electrolyte layers using the Kelvin probe technique. It was found that the corrosion potential was strongly affected by the thickness of the electrolyte layer due to the very large effect of the transport kinetics of the oxygen reduction reaction. Addition of Cr to the mild steel influenced the corrosion potential probably due to the change in the quality of a corrosion product which affects both the anodic and the cathodic reactions.