Anodic Stress Corrosion Cracking Suspectibility of Nickel and Nickel-Chromium Alloys Containing Molybdenum and Iron in Bicarbonate Plus Chloride Solutions at 90°C

Abstract

It is reported in the literature that Alloy C-22 (N06022) was foundsusceptible to stress corrosion cracking (SCC) in presence of bicarbonate ions, at temperatures higher than 60°Cand anodic applied potentials in the order of +400 mVSCE, when using slow strain rate tests (SSRT). This potential range of cracking susceptibility was associated to the instability of a film that may form on the surface. In order to elucidate the role of the alloying elements on the SCC susceptibility of nickel (Ni) based alloys, the following four Alloy C-22 (N06022), Alloy 600 (N06600), Alloy 800H (N08800) and Alloy Ni-201 (N02201)were tested under the same conditions. Results showed that even though C-22, 600 and 800 may have similar electrochemical anodic behavior, only C-22 may present a clear case of SCC at anodic potentials.