Corrosion of ferritic–martensitic steels in the eutectic Pb–17Li

Three different ferritic–martensitic steels were exposed to Pb–17Li under dynamic conditions at 480°C up to 8000 h. On the surface of all 7–10% Cr reduced-activation steels, a two-layer oxide scale consisting of MnCr2O4 spinel and (Fe,Cr)2O3 formed during the heat treatment. This was detected by means of XPS and AES analysis. It was found that the corrosive attack started with the dissolution of MnCr2O4 spinel and (Fe,Cr)2O3. When the oxide scale was dissolved by the liquid metal the corrosive attack continued into the steel matrix. Investigations of the corrosion mechanism have revealed that the steel elements Fe and Cr were strongly dissolved. Those steel elements, which have a low solubility in Pb–17Li, like W, Mo, V, remained in the matrix and were enriched in the surface near layer.