Effects of pre-formed nanostructured surface layer on oxidation behaviour of 9Cr2WVTa steel in air and liquid Pb–Bi eutectic alloy

• Surface mechanical rolling treatment was applied to 9Cr2WVTa steel.
• Microstructure in the surface layer of the steel was refined into nanometer scale.
• Oxidation resistance of the nanostructured sample is evidently enhanced in air.
• Oxide scale on the nanostructured sample is more compact and enriched with Mn.
• Oxide scale on the nanostructured sample is more protective in liquid Pb–Bi.

A nanostructured surface layer was pre-formed on a 9Cr2WVTa reduced activation ferritic/martensitic steel sample by means of surface mechanical rolling treatment (SMRT). In comparison with the initial sample, oxidation experiments at 600 °C in air showed that the oxidation resistance of the SMRT sample is markedly enhanced, due to the formation of a more continuous, homogenous, and compact oxide scale enriched with Mn. Furthermore, oxidation experiments at 550 °C in oxygen-saturated liquid Pb–Bi eutectic alloy showed that the oxidation resistance is improved on the SMRT sample after pre-oxidation in air, due to depressed diffusivities in the pre-formed oxide scale.