The influence of Mo, V, W in ferrochrome alloys and of SO4=⁠, ClO4−⁠, Cl− in an aqueous electrolyte was investigated electrochemically. The effect of minor alloying elements was most pronounced in the active potential region, prior to passivation; Mo, V reduced pitting while W enhanced it. Cl− promoted pitting whereas SO4= and ClO4− were inhibitors. Removal of surface sulfate ions destroyed this inhibitive effect. Relationships were developed between Epit, Erep, ipp and [anion] which enabled the prediction of [SO4=] and [Cl−] required to inhibit and induce pitting respectively.

Subject
Anions, Pits, Anode potential, Stainless alloys, Chloride ion concentration, Molybdenum alloys, Passive films, Anodic polarization curves, Sodium chloride, Corrosion inhibitors, Pitting, Alloys, Electrodes
National Association of Corrosion Engineers
1989
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