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.