Corrosion Compatibility Studies of Stainless Steel 304L in Flowing Liquid Lead Bismuth Eutectic

Abstract

Stainless steel 304L is being considered as a structural material for some components in the lead–bismuth eutectic (LBE) target facility operating at a temperature of about 250°C. Data available on the corrosion of SS 304L in LBE for long duration exposure at these temperatures are scanty. This paper gives the corrosion behaviour of SS 304L after the exposure of 6500 h in LBE in a non-isothermal loop with oxygen concentration of ~4 × 10⁻¹⁰ wt% at temperatures of 250 and 350°C and with flow velocity of 16 cm s⁻¹. The composition of the surface film was analysed by energy dispersive X-ray (EDAX) and X-ray photoelectron spectroscopy techniques. To record the changes in the mechanical properties of SS 304L upon exposure tensile tests of the tensile specimens exposed to LBE were performed in air at room temperature and the fractured surfaces were examined by scanning electron microscope (SEM). Changes in microstructure and elemental composition of the exposed surface of SS 304L were studied using SEM and EDAX. While no changes were observed in the mechanical properties and microstructure due to prolonged exposure to LBE at either temperature, the specimens exposed to 350°C after 6500 h showed a corrosion rate of 1.2 × 10⁻³ μm h⁻¹. While no penetration of LBE into the grain boundaries was observed at either temperature after an exposure of 6500 h, a minor depletion of nickel was noted in specimens exposed at 350°C.