Crevice Corrosion of Low-Pressure Steam Turbine Materials in the Boiler Water Contained Impurity Ions

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Abstract:

Crevice corrosion of 3.5NiCrMoV and 13Cr steels, which are used as low-pressure (LP) steam turbine materials, was investigated by electrochemical corrosion tests in the simulated boiler water contained chloride and sulfate ions. For 3.5NiCrMoV steel, by comparison with the surfaces outside crevice, the surfaces inside crevice of the specimens coupled with both of the same steel and 13Cr steel showed no remarkably corroded pattern even though pitting corrosion was observed. The specimen of 13Cr steel coupled with the same steel plate exhibited pitting corrosion inside the crevice, and a lower open cycle potential (Ocp) than the single plate of 13Cr steel. On the other hand, the specimen of 13Cr steel coupled with 3.5NiCrMoV steel plate showed the lowest Ocp, as the anodic dissolutions of 3.5NiCrMoV steel became the dominate corrosion mechanism.

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192-197

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June 2017

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© 2017 Trans Tech Publications Ltd. All Rights Reserved

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