Susceptibility to LME of 316L and T91 steels by LBE: Effect of strain rate

The effect of liquid lead–bismuth eutectic on 316L and T91 steels at 160 °C has been studied as a function of strain rate, using a centre cracked in tension specimen adapted for the study of crack propagation. Brittle fracture, characterized by elongated river cracks on all the fracture surfaces, indicates that T91 is sensitive to the embrittlement by LBE. This embrittlement effect is very pronounced at low deformation rate (∼10−5 mm s−1). A ductile–brittle transition is observed in the high strain rate range investigated. In the transitory regime, there is a competition between the growth of dimples and brittle cracking induced by the liquid metal. Ductility recovery is complete at the highest investigated deformation rate. The mechanical properties of the 316L steel are not clearly affected by the presence of LBE, in spite of a modification in the plastic deformation mode which strongly affects fracture surfaces.