Effects of 405 stainless steel on crevice corrosion behavior of Alloy 690 in high-temperature pure water

Effects of 405 stainless steel (405 SS) on crevice corrosion behavior of Alloy 690 in high-temperature pure water were investigated. Results revealed that the corrosion rate of Alloy 690 was low within the crevice. It was likely attributed to the fact that a Cr-rich inner oxide film and a Ni-rich layer beneath this oxide film formed upon Alloy 690, inhibiting the diffusion of oxygen towards the oxide/matrix interface. Moreover, the Fe2+ ions dissolved from 405 SS consumed most of oxygen, leading to less oxygen participating in the oxidation of Alloy 690. In addition, it was found that Fe concentration continuously decreased from the surface of the inner oxide film to the oxide/matrix interface of Alloy 690 within the crevice, which was probably due to the diffusion of Fe2+ ions dissolved from 405 SS into the inner oxide film. (C) 2020 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.