Development and Validation of Corrosion Behavior Models for T91 Materials With Different Bismuth Contents and Oxygen Concentrations

This paper proposes a physically based double‐layer oxide film growth model for T91 ferritic–martensitic steel in lead–bismuth eutectic (LBE). It describes the growth and evolution of oxide scales under varying bismuth contents and dissolved oxygen concentrations, using mass transport and thermodynamics with numerical solutions via the Brent algorithm. Validated against static corrosion experiments, the model uniquely incorporates bismuth content via composition‐dependent solubility of oxygen and iron. Compared with existing LBE corrosion models, it shows reasonable accuracy in predicting oxide layer thicknesses. The model reproduces magnetite and Fe–Cr spinel growth, as well as the transition from oxidation to dissolution corrosion under low‐oxygen conditions, offering a theoretical reference for material reliability assessment in lead‐bismuth‐cooled fast reactors.