Differentiation of SCC Susceptibility with EIS of Alloy 182 in High Temperature Water

Abstract

Electrochemical Impedance Spectroscopy (EIS) measurements were carried out in high temperature water with Ni-based Alloy-182. The aim was to correlate the EIS results with differences in Stress Corrosion Cracking (SCC) susceptibility that is present around the Ni-NiO transition. There was a clear difference between the EIS results at and away from the Ni-NiO transition. To make a more quantitative correlation a simple equivalent circuit was used to fit the experimental data. A clear correlation between the CPE exponent (n) and the SCC susceptibility could be obtained. Additionally, it was shown that the high frequency arc of the EIS data was related to the diffuse double layer

Keywords

• EIS
• Ni-based alloys
• high temperature water
• oxide layer