Corrosion behavior of steels in liquid lead–bismuth with low oxygen concentrations

Corrosion tests in pots were conducted to elucidate corrosion behavior of various steels in liquid lead–bismuth for 3000 h under the condition of an oxygen concentration of 5 × 10−8 wt% at 450 °C and an oxygen concentration of 3 × 10−9 wt% at 550 °C, respectively. Significant corrosion was not observed at 450 °C for ferritic/martensitic steels, F82H, Mod.9Cr–1Mo steel, 410SS, 430SS except 2.25Cr–1Mo steel. Pb–Bi penetration into steels and dissolution of elements into Pb–Bi were severe at 550 °C even for ferritic/martensitic steels. Typical dissolution attack occurred for pure iron both at 550 °C without surface Fe3O4 and at 450 °C with a thin Fe3O4 film. Ferritization due to dissolution of Ni and Cr, and Pb–Bi penetration were recognized for austenitic stainless steels, 316SS and 14Cr–16Ni–2Mo steel at both temperatures of 450 °C and 550 °C. The phenomena were mitigated for 18Cr–20Ni–5Si steel. In some cases oxide films could not be a corrosion barrier in liquid lead–bismuth.