Characterisation of the austenitic steels Super 304H and HR3C after air and steam oxidation

ABSTRACT

This work aimed to evaluate the effect of a long-term pre-oxidation process in the air (5000 hours at 650 °C) on the steam oxidation resistance of Cr-rich steels with around 18 wt.% Cr (Super 304H) and around 25 wt.% Cr (HR3C) content exposed for the additional 5000 hours at 650 °C. The effect showed a high impact of a long-term pre-oxidation process and a high content of Cr in the metal matrix of the exposed steels. The steel with a lower Cr content showed spallation of the oxide scale under the oxidation process in the air, and only the steel with 25 wt.% Cr showed no spallation of the oxide scale in both conditions: air and steam. The post-exposure analysis in this work was carried out using Scanning Electron Microscopy (SEM) supported by Energy Dispersive X-ray Spectroscopy (EDS) using an X-Ray mapping function. Phase analysis was performed using an XRD diffractometer.

KEYWORDS:

• Austenitic steels
• Super 304H
• HR3C
• steam oxidation
• high-temperature corrosion
• SEM/EDS
• XRD

Acknowledgments

This work was financed directly by the internal funds of ŁUKASIEWICZ – Krakow Institute of Technology contracted by the Ministry of Science and Higher Education in Poland. The project was cooperated based on cooperation with the Department of Materials Engineering, Czestochowa University of Technology, Poland, The grant title: Air and steam oxidation of boiler steels, contract number: 9011/00

Disclosure statement

No potential conflict of interest was reported by the author(s).