Behavior of 12% Cr low-activation ferritic-martensitic steel EK-181 after holding in a static lead melt at 600 °С for 3000 hours

•On the surface of the low-activation ferritic-martensitic steel EK-181 after holding at 600 °C for 3000 h in a static lead melt two-layer oxide scale with a thickness of 5 to 45 µm is formed.•The scale is mainly represented by particles of iron oxides Fe3O4 and Fe2O3, and to a lesser extent by chromium oxides – Cr2O3.•The oxide films protect the ferritic-martensitic steel from the aggressive action of the liquid coolant.•Microstructure of the bulk of the material retains its stability during long-term exposure in liquid lead. The behavior of low-activation 12% chromium ferritic-martensitic steel EK-181 (RUSFER-EK181) is investigated during holding in an oxygen-containing lead melt at 600 °C for 3000 h. Following this exposure, a 5 to 45 µm bi-layer oxide scale is formed on steel surface. Its outer and inner layers represent oxide films mainly enriched with iron and chromium, respectively. The X-ray diffraction and electron microscopy analyses show that the oxide scale is primarily represented by particles of Fe3O4 and Fe2O3 iron oxides, and to a lesser extent by Cr2O3 chromium oxides. A chromium-depleted region of the matrix several micrometers thick is found under the scale layer. It is shown that the bulk microstructure of steel retains its stability during long-term exposure in liquid lead. No qualitative changes are observed after such exposure. [Display omitted]