Potentiodynamic polarization techniques were used to determine characteristic pitting potentials for Alloy 800 in chloride and chloride-sulfate media. The effect of chloride concentration in the range of 0.001 to 1 M was investigated. Decreasing chloride concentrations resulted in noble shifts of the critical nucleation potential. Immunity to pitting corrosion was evident at chloride levels below 0.01 M. Increasing sulfate concentrations resulted in improved chloride pitting resistance, although detrimental effects associated with pitting at transpassive potentials were evident with low-level sulfate additions to dilute chloride media. Potentiodynamic and potentiostatic polarization results for Alloy 800 in a lake water environment were found to be consistent with that predicted on the basis of lake water chloride and sulfate contents.

Subject
Noble potential, Pits, Transpassivation, Water, Overpotential, Sulfates, Repassivation potentials, Nucleation, Corrosion attacks, Pitting, Alloys, Chlorides, Protection potential
National Association of Corrosion Engineers
1987
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