Dissolution corrosion behavior and mechanisms of 316L steel in static Pb-Mg at 450°C and 550°C

The lead-magnesium eutectic (Pb‑Mg, 97.5 wt.% Pb-2.5 wt.% Mg) has been identified as a promising coolant for next‑generation nuclear systems. The compatibility between structural materials and candidate coolants is a critical feasibility factor for advanced nuclear systems. Corrosion studies were conducted on 316 L steel in Pb-Mg at 450°C and 550°C for exposure durations up to 2000 hours. The 316 L steel exhibited significant dissolution attack, primarily due to selective leaching of nickel from the matrix. The dissolution mechanism is fundamentally identical at both temperatures, exhibiting the same linear kinetics in the early stages. Due to the increase in corrosion depth, the corrosion rate gradually decreases over time. The Ni dissolution rate constant in Pb-Mg is calculated and an Arrhenius relationship with temperature is established. This study elucidates the corrosion behavior and mechanism of 316 L steel in Pb‑Mg, providing valuable insights for its application in advanced nuclear energy systems.