The effects of the liquid oxygen-depleted LBE on the tensile responses of pure BCC iron

One of the main challenges in understanding the sensitivity of the ferritic-martensitic steel or T91 on liquid metal embrittlement (LME) may come from the complex microstructure of the steels. To get better insights into the interactions between Fe-based materials and lead-bismuth eutectic (LBE), this study investigates pure iron (α−Fe) as a simplified model system. For this purpose, slow strain rate tensile tests (SSRTs) at 350°C and 5×10 ⁻⁵s ⁻¹ strain rate were employed to evaluate LME susceptibility of the α−Fe/(oxygen-depleted) LBE system. The obtained results indicated that interactions with the liquid LBE increased the total elongation and decreased the reduction of area of α−Fe compared to the reference condition. It was suggested that interactions with LBE changed the surface states of α−Fe resulting in a delay in necking. Adsorption-enhanced decohesion and plasticity mechanisms of LME may both play a role during the interactions between the liquid oxygen-depleted LBE and α−Fe at 350 °C and 5×10 ⁻⁵s ⁻¹ strain rate. Due to the increased in the total elongation of LBE tests compared to the inert tests, it was suggested that the term ”liquid metal embrittlement” may not suitable to describe the observation. It should be noted that this study does not aim to directly replicate the behavior of T91 steel but rather to provide a clearer understanding of LME mechanisms in a controlled, single-phase system. These insights may serve as a foundation for interpreting more complex behaviors in multi-phase steels.