Creep-to-rupture of T91 steel in static liquid lead-bismuth eutectic: Effects of cyclic temperature and oxygen environment

The creep-to-rupture behavior of T91 steel in static liquid lead-bismuth eutectic (LBE) is investigated, focusing on the impacts of cyclic temperature and oxygen condition. The results indicate that thermal cycling, oxygen deficiency, and high applied stress levels significantly accelerate creep deformation and reduce the creep-to-rupture lifetime of T91 steel in LBE. Surface oxide scales on T91 steel and their self-healing mechanisms play a crucial role in enhancing the creep resistance by isolating the LBE contact and delaying crack initiation and propagation. However, the integrity of this oxide scale is compromised under cyclic thermal conditions and low oxygen levels, leading to premature failure. Microstructural examinations reveal the evolution of oxide scale damage and self-healing mechanisms. The findings suggest that oxide scale failure mechanisms should be considered when designing the long-term operational performance of advanced LBE-based reactors.