Understanding the liquid metal assisted damage sources in the T91 martensitic steel for safer use of ADS

The paper analyses the risks of corrosion damage and of accelerated fatigue damage by liquid lead–bismuth eutectic (LBE) of the T91 steel for reliability assessment of accelerating driven systems (ADS). The corrosion of the T91 in LBE is dependent on the oxygen concentration in the LBE. Dissolution process occurs when the oxygen concentration is low while a protective oxide film forms under high oxygen concentration. The low cycle fatigue resistance of the T91 steel is reduced by a factor at least of 2 when cycling at 300 °C in LBE instead of air. A pre immersion of T91 fatigue specimens in a LBE bath at 600 °C for about 600 h and with a dissolved oxygen concentration less than 10−10 wt% is detrimental on the fatigue resistance. However, an oxide layer resulting from high oxygen concentration appears to be protective against corrosion–deformation interaction.