High temperature electrochemical reaction parameters affecting electrochemical corrosion potential of nickel-base Alloy 82 weld metal

ABSTRACT

The electrochemical corrosion potential (ECP) data of nickel-base alloy 82 weld metal (Alloy 82) in both O₂ and H₂O₂ environments were measured. Although Alloy 82 is used at various welds in boiling water reactors (BWRs), the ECP data of Alloy 82 under BWR conditions are limited. The ECP data measured in this study revealed that Alloy 82 had higher ECPs than 304 and 316 L stainless steels and nickel-base alloy 182 weld metal (Alloy182) at low oxidant concentrations in both O₂ and H₂O₂ environments. The ECPs of Alloy 82 calculated with an analytical ECP model that was developed in this study agreed with measured values in the cases that it was acceptable for the model to have an error range of ± 0.1 V in the tested range of O₂ and H₂O₂ concentrations. The possible reason for the ECPs of Alloy 82 to be higher than those other materials at low oxidant concentrations is given as follows: the anodic polarization curve of Alloy 82 exhibits a lower current density at low potentials because of its higher Ni and Cr contents. The developed ECP model validated by the ECP data will contribute to evaluations of the effectiveness of mitigation technologies for stress corrosion cracking environments.

KEYWORDS:

• BWR
• ECP
• polarization curve
• cathodic reaction
• nickel-base alloy weld metal
• Alloy 82

Disclosure statement

No potential conflict of interest was reported by the author(s).

References