Anodic Stress Corrosion Cracking Susceptibility 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 found to be susceptible to stress corrosion cracking (SCC) in presence of bicarbonate ions, at temperatures higher than 60°C and anodic applied potentials in the order of 400 mVSCE, (where SCE is the saturated calomel electrode) when using slow strain rate tests (SSRTs). This potential range of cracking susceptibility was associated with 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, four alloys—C-22 (N06022), 600 (N06600), 800H (N08800) and 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.