Method of forming passive oxide film based on chromium oxide, and stainless steel

摘要

A method of readily forming passive oxide film based on chromium oxide characterized by subjecting stainless steel to electrolytic polishing and fluidized abrasive polishing, baking the steel thus treated in an inactive gas to remove moisture from its surface, and heat treating the resultant steel at 300 to 600° C. in a gaseous atmosphere comprising hydrogen or a mixture with an inactive gas and containing less than 4 ppm of oxygen or less than 500 ppb of moisture. An oxidized stainless steel characterized by comprising a stainless steel having a crystal grain number of 6 or above and, formed on the surface thereof, a passive oxide film based on chromium oxide, wherein the oxide film has a thickness of 5 nm or above and the atomic ratio of chromium to iron in the outermost layer of the film is 1 or above.