Corrosion characteristics of T91 steel in lead–bismuth eutectic with different oxygen concentrations at 500°C

Corrosion tests of T91 were carried out in the stagnant lead–bismuth eutectic (LBE) containing 10−6, 10−7, and 10−8 wt% oxygen at 500°C for up to 2000 h, respectively. The dependence of corrosion characteristics on oxygen concentrations in LBE was obtained. The results show that the oxide‐scale structure changes from a three‐layer magnetite/spinel/internal oxidation zone (IOZ) scale under the oxygen concentration of 10−6 wt%, to the formation of a two‐layer spinel/IOZ scale under the oxygen concentrations of 10−7 and 10−8 wt%. In addition, with the decrease of the oxygen concentration, the Cr/Fe ratio in the Fe–Cr spinel slightly increases in a linear rule while the thicknesses of the oxide layers gradually decrease.