Oxidation behavior of alumina-forming duplex stainless steels in high temperature steam environments

Abstract

Oxidation behavior of alumina-forming duplex stainless steels (ADSS), which are developed as accident tolerant fuel cladding materials, and commercial FeCrAl alloy, APM, were evaluated as the alloys exposed to pure steam and hydrogen added steam environments at various temperature. When the ADSS was exposed to pure steam at $800^\circ C$, $900^\circ C$ and $1050^\circ C$, weight gain after $900^\circ C$ oxidation was highest value due to formation of transient alumina. Weight gain after 800 oC exposure was lower value. As compared to APM, similar oxidation behavior was shown at $800^\circ C$. Since some spinel oxide was found on the ADSS alloys above $900^\circ C$, ADSS had higher weight gain than APM above $900^\circ C$ exposure. Additionally, it seems that the spinel oxide was formed at early state of high temperature oxidation and usually on austenite phase, which has lower aluminum content in the matrix than ferrite phase. Also, the oxidation behavior of ADSS was evaluated after exposure to hydrogen added environment. The difference in weight gain was not much significant