The simultaneous presence of bicarbonate and chloride ions may be necessary to induce stress corrosion cracking (SCC) in alloy 22 at anodic applied potentials. It has been suggested that the susceptibility to SCC could be related to the occurrence of an anodic peak in the polarization curves below the transpassive range. The aim of this preliminary work is to study the anodic behavior of alloy 22 and three other nickel alloys in different media containing various concentrations of bicarbonate and chloride ions as a function of the temperature to determine which element in the alloy maybe be responsible for the anodic peak and/or cracking. The studied materials included alloys 22, Ni-201, alloy 800H and 600. Results show that for alloy 22 the potential and the peak current increased with the temperature and chloride concentration in the solution. For the alloys with smaller alloying content the peak potential decreased to the point of disappearing. There was no dependence of the current of the peak with the amount of alloying. In a future work, slow strain rate tests will be performed to determine if there is correspondence between SCC and the presence of the anodic peak.
The ability of nickel (Ni) to dissolve large amounts of different alloying elements has led to the development of several families of Ni alloys. The largest family of Ni alloys is the Nickel- Chromium-Molybdenum (Ni-Cr-Mo) or C-type, which provides corrosion resistance in reducing and oxidizing hot acids. Alloy 22 (N06022) is one of the most versatile members of the C family. It was generally reported that alloy 22 is highly resistant to localized and general corrosion in the ground water environments. 1-6 Relatively fewer experimental studies were performed to understand the processes related to the stress corrosion cracking resistance of alloy 22.
