Corrosion Potentials and Corrosion Behavior of AISI 304 Stainless Steel in High-Temperature Water Containing Both Dissolved Hydrogen and Oxygen^⋆

The corrosion potential of AISI 304 stainless steel (SS) in high-temperature water is affected markedly by the absolute and relative concentrations of dissolved hydrogen and oxygen as well as by mass transport of these species to the metal surface. This reflects the coupled electrochemical recombination reaction of the hydrogen and oxygen on the surface. The fact that the effects are more pronounced in water containing a stoichiometric excess of hydrogen than in the reverse case suggests that the electrochemical oxidation of hydrogen on an oxide-covered steel electrode is markedly inhibited. The work also implies that when hydrogen injection is used to control the corrosion potentials of SS, monitoring and maintaining low oxygen concentrations in the circulating cooling water is more important than maintaining a specific hydrogen level if the latter is in stoichiometric excess of the oxygen.