Effects of thiosulfate and dissolved oxygen on crevice corrosion of Alloy 690 in high-temperature chloride solution

Fangqiang Ning^1,2，Jibo Tan¹，Ziyu Zhang¹，Xinqiang Wu¹，Xiang Wang¹，En-Hou Han¹，Wei Ke¹

1. CAS Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning Key Laboratory for Safety and Assessment Technique of Nuclear Materials,Institute of Metal Research, Chinese Academy of Sciences2. School of Materials Science and Engineering, University of Science and Technology of China

摘 要：The crevice corrosion behavior of Alloy 690 was investigated in high-temperature chloride solution containing different concentrations of thiosulfate(S₂O₃^2-) and dissolved oxygen（DO）. The S₂O₃^2- inhibited corrosion of Alloy 690 through consuming oxygen in aerated chloride solution. In deaerated chloride solution,the S₂O₃^2- was reduced to S° and S^2- and subsequently incorporated into the oxide films, which promoted the pitting corrosion at locations of both TiN inclusions and matrix inside the crevice during the crevice corrosion as well as influenced the composition and thickness of the oxide films. The effect mechanisms of S₂O₃^2- and DO on crevice corrosion in high-temperature chloride solution are discussed.

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