Investigation on the water vapor oxidation of Super304H at 600 ℃

Abstract

Steam oxidation is the main limited factor for the heat-resistant steel in fossil power plant. Disclosing the oxidation mechanism and kinetics could be helpful for the daily inspection to ensure the safety operation. To investigate the water vapor oxidation behavior of Super304H, the oxidation test was conducted at 600 ℃ for 25, 50, 100, 150 and 200 h in flowing steam. The structure and compositions of the oxide layers were investigated by line-scanning of scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). Surface morphology was observed after the oxidation test. The oxide phases were identified by XRD. The results showed that the oxide layer was duplex structure consisted of a Fe _3 O _4 - Fe _2 O _3 outer layer and an inner oxide layer which contained nickel oxide, Cr _2 O _3 , and FeCr _2 O _4 . As the oxidation time increased, the thickness of the total oxide layer and inner layer both increased. After 100 h oxidation, oxide layer exfoliation occurred and resulted in rapid growth of new oxide layer in the exfoliation region.

Keywords

• Super304H
• water vapor oxidation
• duplex oxide layer
• exfoliation