Irradiation damage induced breakaway oxidation of chromia-forming ferritic-martensitic steel at high-temperature CO2

• Irradiation accelerated the oxidation of chromia-forming SIMP steel. • Transition from Cr-rich to Fe-rich oxide growth happened with the increasing irradiation dose. • Breakaway oxidation occurred when the irradiation damage was more than 1.75 dpa. • Fe-rich nodules appeared with internal oxide of (Cr, Mn) 3 O 4 . • Cr supply is insufficient to maintain the local growth of Cr 2 O 3 due to irradiation. This work studied the high-temperature CO 2 corrosion behavior of a novel chromia-forming ferritic-martensitic steel under the influence of irradiation damage. The role of irradiation damage in the corrosion behavior of 3 MeV Fe 11+ irradiated SIMP steel at 600 ℃ CO 2 was investigated by comparing the morphology, thickness, composition and microstructure of the oxide films formed on SIMP steel with different damage levels. With the increase of irradiation dose, the thickness of the oxide films increased significantly, and the transition from Cr-rich to Fe-rich oxide growth occurred accompanied by the appearance of Fe-rich nodules and internal oxidation when the irradiation damage increased to more than 1.75 dpa, indicating the trigger of breakaway oxidation. The mechanism of irradiation-induced breakaway oxidation was discussed from the perspective of the displacement damage and implanted Fe ions brought about by Fe-ion irradiation and the evolution of oxide films with irradiation damage.