The cathodic and anodic characteristics of freshly polished and pre-reduced UNS S32550 (ASTM A479) super duplex stainless steel in a filtered and conductivity-adjusted seawater have been investigated under controlled flow conditions. A rotating cylinder electrode was used together with both steady and non-steady-state voltammetry and a potential step current transient technique to investigate the electrode reactions in the fully characterized electrolyte. Both oxygen reduction and hydrogen evolution were highly irreversible and the material exhibited excellent passivation and repassivation kinetics. Relative corrosion rates were derived and the corrosion mechanism of the alloy was found to be completely independent of the mass-transfer effects, which can contribute to flow-induced corrosion.

Subject
Corrosion rate, Metal surfaces, Oxide films, Anode surfaces, Seawater, Mass transfer, Oxide surfaces, Film formation, Risk reduction, Alloys, Electrodes, Corrosion potential, Electrode potential
Keywords:
duplex stainless steel, flow-induced corrosion, mass transfer, oxygen reduction, polarization, rotating cylinder electrode, transpassivity
NACE International
2004
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