Field studies of steam oxidation behavior of austenitic heat-resistant steel 10Cr18Ni9Cu3NbN

• Field study of steam oxidation of 10Cr18Ni9Cu3NbN steel was investigated.
• Shot blasting improved the steam oxidation resistance of 10Cr18Ni9Cu3NbN steel.
• After the initial scale exfoliation, the new oxide on 10Cr18Ni9Cu3NbN steel was similar to the oxide on 9–12%Cr steels.

The steam oxidation of austenitic steel 10Cr18Ni9Cu3NbN at about 605 °C after in service for 12,000 h and 34,696 h in a 660 MW USC power plant was investigated. Results show that a double layer structure consisting of a magnetite outer layer and Cr-rich inner layer was observed. After 12,000 h, shot blasting treatment improved the steam oxidation resistance of 10Cr18Ni9Cu3NbN steel compared with previous report. Scale oxide which was beneficial from shot blasting treatment spalled off within a short time before 34,696 h. After initial scale exfoliation, the newly formed scale oxide was more likely to be the oxide in 9–12%Cr steels, which was attributed to the low chromium under the initial oxide.