Metallurgical study on erosion and corrosion behaviors of steels exposed to liquid lead–bismuth flow

The mechanism of erosion and corrosion of steels in lead–bismuth eutectic (45Pb–55Bi) flow was investigated. Nine steels were simultaneously exposed to the Pb–Bi flow at the temperature of 550 °C, the loop temperature difference of 150 °C, and the flow velocity of 2 m/s for 1000 h. The liquid metal corrosion, or Pb–Bi penetration into steels occurred in all the steels, and severe erosion took place in some of the steels under low oxygen concentration of 2 × 10−9 wt% in Pb–Bi. The corrosion layer penetrated by Pb–Bi was deeper in the steels containing a lower content of Cr. It was confirmed that the erosion was caused by hydrodynamic carrying away of weakened surface materials due to Pb–Bi penetration. The large-scale erosion could be caused by the detachment of lumps of corroded materials that had defects formed by dissolution of alloying elements.