Effect of pH and Temperature on the Corrosion Potential of Alloy 22 in Aerated Solutions

Alloy 22 (N06022) is a nickel based alloy highly resistant to all types of corrosion. Under certain conditions of electrolyte composition and temperature, tightly creviced Alloy 22 may be prone to crevice corrosion. Many external and internal variables control the susceptibility of Alloy 22 to crevice corrosion. These variables determine the likelihood of crevice corrosion by influencing two critical parameters; the crevice repassivation potential (CRP) and the corrosion potential (E_corr). Provided conditions of electrolyte composition, temperature, etc. and crevice geometry are appropriate, Alloy 22 may suffer crevice corrosion only if the corrosion potential reaches the crevice repassivation potential in the environment of interest. A review of values of E_corr for Alloy 22 in a variety of environments is presented. The dependence of E_corr with the temperature and the pH of the bulk electrolyte are specially discussed.