On the kinetics of LME for the ferritic–martensitic steel T91 immersed in liquid PbBi eutectic

Abstract

Use of heavy liquid metals (HLM), such as the Lead–Bismuth eutectic (LBE), is foreseen for targets and coolants in the newly designed accelerator driven systems (ADS). However, most of the structural materials suffer severe damage when in contact with the HLM. In particular, the simultaneous presence of load and environment can induce a phenomenon named Liquid Metal Embrittlement (LME) in the reference material (ferritic–martensitic steel T91). This phenomenon could give rise to high crack growth rates and the abrupt collapse of the structural material. In this study the effect of LBE on the crack growth rate of the T91 steel was evaluated. The effect of pre-exposure to flowing LBE was considered and assessed in terms of crack growth rates and fracture surface appearance. It was concluded that if conditions for wetting were reached during exposure in LBE, e.g. by dissolution or rupture of protective oxide layers, LME was likely to occur under stress, at 300 °C, regardless of the LBE chemistry.