Effect of oxygen on corrosion of an alumina-forming duplex steel in static liquid lead-bismuth eutectic at 550 °C

Abstract

Corrosion in static liquid lead–bismuth eutectic (LBE) with varying oxygen content is investigated at 550 °C on an alumina-forming duplex steel which contains both austenite and ferrite phases. The duration of the tests is about 1000 h. For oxygen concentration ranging from 10−12 to 10-8 % by mass, the steel shows preferential nickel dissolution and LBE penetration. The degradation of the ferrite is delayed in contrast to the austenitic part of the duplex microstructure. At 10-6 % oxygen, the steel is protected from LBE attack due to the formation of a thin oxide layer rich in aluminum. The precipitation of NiAl in the steel does not compromise the formation of Al-rich oxide at this oxygen concentration.