Evaluating the effects of environmental aging on the pitting corrosion of steam turbine blade steels

A flow loop has been setup to allow simulation of operating conditions in a steam turbine during transitions in water chemistry between on‐load (deaerated) and off‐load (aerated) environments. Electrochemical noise measurements were performed to establish the critical chloride concentration for pitt...

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Bibliographic Details
Published in:Materials and corrosion 2023-03, Vol.74 (3), p.373-383
Main Authors: Aldhous, Philip, Akid, Robert, Leiva‐Garcia, Rafael, Zhou, Shengqi
Format: Article
Language:English
Subjects:
Aeration
Aging (metallurgy)
Chlorides
Corrosion effects
Corrosion potential
Electrochemical noise
Photoelectrons
pitting corrosion
stainless steel
Stainless steels
Steam turbines
Turbine blades
Visual observation
Water chemistry
x‐ray photoelectron spectroscopy
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Summary:A flow loop has been setup to allow simulation of operating conditions in a steam turbine during transitions in water chemistry between on‐load (deaerated) and off‐load (aerated) environments. Electrochemical noise measurements were performed to establish the critical chloride concentration for pitting of 403 12Cr stainless steel. The results were confirmed by comparative measurements of corrosion potential and visual observation of pitting. X‐ray photoelectron spectroscopy was used to quantify changes in the passive film due to transient environmental conditions. The critical chloride concentration for pitting with/without pre‐exposure to on‐load conditions has been measured and the impact of environmental aging is discussed. Electrochemical measurements were performed on 12Cr stainless sheets of steel in a simulated steam turbine environment to determine the effects of “two‐shifting” between on‐load and off‐load water chemistries. A combination of electrochemical noise and x‐ray photoelectron spectroscopy measurements are used to show the effect that environmental aging has on the material's passive film properties.
ISSN:0947-5117
1521-4176
DOI:10.1002/maco.202213384