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Combined with the applicable scenarios of chemical oxidation treatment of water-cooled reactor metals mentioned earlier, the following are the complete and specific process steps.: 1. Degreasing and degreasing the workpiece in the pretreatment stage: Use an alkaline degreaser to completely remove oil stains and cutting fluid residues on the metal surface to ensure that the surface is completely hydrophilic and free of oil spots. Pickling activation: Use a low-concentration nitric acid + hydrofluoric acid mixed solution to remove the native oxide scale and rust on the surface, exposing the pure metal matrix. Pure water rinse: Rinse the workpiece repeatedly with high-purity water more than 3 times to completely neutralize the residual acid and alkali to prevent impurities from being brought into the subsequent oxidation process. 2. Setting of working conditions parameters in the controlled oxidation film formation stage: Adjust the water environment in the primary loop of the water-cooled reactor to the target temperature (280~320°C) and pressure 15.5MPa, and accurately control the dissolved hydrogen/oxygen content to the preset threshold. Constant temperature oxidation treatment: Continuous constant temperature treatment for 500 to 1000 hours in a stable water chemical environment allows the metal surface to gradually form a dense oxide film with a double-layer structure. Process parameter monitoring: The coolant conductivity, dissolved oxygen, and pH value are monitored online throughout the entire process to avoid defects such as cracks and uneven thickness of the oxide film caused by parameter fluctuations. 3. Passivation and stabilization treatment in post-processing and detection stages: After the oxidation is completed, the workpiece is transferred to a low-concentration potassium dichromate passivation solution to seal the tiny pores on the surface of the oxide film and improve the stability of the film. Rinse alternately with hot and cold water: First rinse the remaining passivation liquid with running cold water, then rinse with hot water above 80℃ and dry with hot air to avoid residual water stains on the surface. Performance verification: The cross-sectional thickness of the oxide film was observed through a metallographic microscope, and a corrosion immersion test was conducted to confirm that the film thickness, density, and corrosion resistance met the design requirements of the water-cooled reactor.