Effect of Diffused Hydrogen on Surface Oxide Film of 9Cr-ODS steel Cooling Tubes in High Temperature and High Pressure Water

Based on the operating conditions of the cooling tubes in the fusion reactor blanket, the effect of dynamic diffusible hydrogen on the oxide film of 9Cr-ODS steel thin-walled tubes was investigated after 400 h corrosion in high-temperature high-pressure (325 ℃/15.5 MPa) deoxygenated water. The results indicate that a dual-layer structure was exhibited by the oxide film on 9Cr-ODS steel, with the inner layer composed of (Fe, Cr)₂O₄ and Cr₂O₃ and the outer layer consisting of Fe₃O₄. The stability of the oxide film was reduced by diffusible hydrogen, with defects and cracks generated on its surface, while no significant interfacial penetration was observed.