Crevice corrosion of a Ni-Cr-Mo-Fe alloy in natural and chlorinated seawater
Thesis/Dissertation
·
OSTI ID:6973340
Alloys 625 is a high-strength, corrosion-resistant Ni-Cr-Mo-Fe alloy that exhibits excellent resistance to pitting, but has been found to be susceptible to crevice corrosion in seawater and in oxidizing environments such as chlorinated seawater. To investigate the mechanism of crevice corrosion for alloy 625 and to assess the role that chlorination plays in crevice-corrosion propagation, a three-fold approach was taken: (1) simulated environments corresponding to those present during the initiation and propagation stages of crevice corrosion were chosen based on mathematical-model predictions, information in the literature and actual measurements; (2) steady-state polarization behavior for alloy 625 in environments corresponding to those found inside and outside an active crevice was ascertained and anodic polarization curves were generated in these simulated crevice environments and cathodic polarization curves were generated in natural seawater and chlorinated seawater; and (3) mixed potential theory, including the effects of IR drop down a crevice, was applied to the polarization data to identify the crevice-corrosion mechanism in natural seawater and to determine the role that chlorination plays in crevice-corrosion propagation. A mixed potential analysis utilizing an anodic polarization curve for alloy 625 generated in an environment simulating that found inside a crevice at initiation and a cathodic polarization curve generated in natural seawater reveals that crevice corrosion initiates by an IR-induced mechanism.
- Research Organization:
- Johns Hopkins Univ., Baltimore, MD (USA)
- OSTI ID:
- 6973340
- Country of Publication:
- United States
- Language:
- English
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