Early oxidation mechanism of austenitic stainless steel TP347H in supercritical water

• Published in: Corrosion science 2017-11, Vol.128, p.241-252
• Main Authors: Li, Yanhui, Wang, Shuzhong, Sun, Panpan, Xu, Donghai, Ren, Mengmeng, Guo, Yang, Lin, Guike
• Format: Article
• Language: English
• Subjects: A. Stainless steel; Austenitic stainless steel; Austenitic stainless steels; B. AFM; B. Raman spectroscopy; B. SEM; B. XPS; C. Oxidation; Corrosion mechanisms; Oxidation; Oxidation resistance; Scanning electron microscopy; X-rays
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2017.09.023

[Display omitted] •Early forming mechanism of scales on typical austenitic steels in SCW.•Three oxidation stages: rapid, transitory stage, and diffusion-controlled.•Formation priority of continuous inner Cr-rich layer relative to outer layer.•The Cr6+ species (likely CrO2(OH)2) only occurred in the very early phase.•Relative constant content of hydroxides on sample surface. The initial corrosion behaviour of austenitic TP347H exposed to supercritical water was investigated. The early oxidation can be categorized into three stages (rapid oxidation, transitory, and diffusion-controlled stages). Higher temperature resulted in a transformation towards the subsequent stage earlier and less oxidation resistance. Cr6+ species (likely CrO2(OH)2) were only generated on the surface in the very early phase, and then they gradually disappeared as the exposure time increased. Compared with a complete outer Fe-rich oxide layer, the formation priority of a continuous inner Cr-rich layer was observed at 540°C within 35h. A corresponding early oxidation process was determined.