Liquid metal embrittlement of the T91 steel in lead bismuth eutectic: The role of loading rate and of the oxygen content in the liquid metal

The mechanical behavior of the T91 martensitic steel tempered at 750 °C has been studied in liquid lead–bismuth eutectic (LBE) and in inert atmosphere. Several conditions were considered to point out the most sensitive embrittling factor. The Small Punch Test technique has been employed by using smooth specimens in air, in Ar–3.5%H2 gas, in low oxygen content LBE and in oxygen saturated LBE at different temperatures and different loading rates. 1 steel exhibited in general a high degree of ductility. However, even with oxygen saturated LBE, it has been possible to observe LME at low strain rate. Furthermore, low oxygen content in LBE and an increase in temperature promoted the LME. It turns out that the strain rate appeared as the critical parameter for the occurrence of LME of the T91 steel in LBE.