Character of Liquid Metal Embrittlement of the Steel T91 in Contact With Lead-Bismuth Eutectic

This work summarizes results of the work carried out in CVR (Centrum výzkumu Rez) on the evaluation of the susceptibility to LME (Liquid Metal Ebrittlement) of the ferritic/martensitic steel T91 in contact with LBE (Lead-Bismuth Eutectic) at 300 and 350°C. The work, carried out in the past few years, through tensile and fracture toughness tests, revealed a marked sensitivity to embrittlement for the T91 in contact with LBE. Tests were carried out in well defined conditions and according to ASTM standards. It was observed that the LBE decreased the fracture toughness, J_IC, by more than 30%, compared to the value in air. The results are discussed based on examinations of the fracture surface evidencing LME occurrence. The fracture toughness measured in LBE is proposed to be the appropriate value for fracture resistance evaluation, applied to extension of a pre-existing LME crack.