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

Abstract 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.