Stifling of Crevice Corrosion in Alloy 22 During Constant Potential Tests

Abstract

Artificially creviced Alloy 22 (N06022) is susceptible to crevice corrosion in presence of high chloride aqueous solution when high temperatures and high anodic potentials are applied. The presence of oxyanions in the electrolyte, especially nitrate, inhibits the nucleation and growth of crevice corrosion. Crevice corrosion may initiate when a constant potential above the crevice repassivation potential is applied. The occurrence of crevice corrosion can be divided into three characteristic domains: (1) nucleation, (2) growth and (3) stifling and arrest. That is, crevice corrosion reaches a critical stage after which growth stops and the specimens start to regain the passive behavior displayed before the nucleation of localized attack.