Abstract: Titanium material less susceptible to discoloration and method for thereof are provided. Titanium materials less susceptible to discoloration in the atmosphere are obtainable by controlling the fluorine and carbon contents in the oxide film on the surface thereof and the thickness of the oxide film. Such titanium materials are obtainable by dissolving the surface thereof in an aqueous fluonitric acid solution with a nitric acid concentration of not higher than 80 g/l or heat-treating at between 300 and 900° C. in a vacuum or in an inert gas atmosphere of argon or helium after dissolving in the aqueous fluonitric acid solution.

Abstract: Titanium resistant to discoloration in an atmospheric environment characterized by having an average carbon concentration of 14 at % or less in a range to a depth of 100 nm from the surface and having an oxide film of a thickness of 12 to 40 nm at its surface. Titanium resistant to discoloration in an atmospheric environment characterized in that, in X-ray diffraction of its surface, a ratio (X1/X2) of a (200) peak intensity X1 of TiC to a (110) peak intensity X2 of titanium is not more than 0.18 and by having an oxide film of a thickness of 12 to 40 nm at its surface.

Abstract: Titanium material less susceptible to discoloration and method for thereof are provided. Titanium materials less susceptible to discoloration in the atmosphere are obtainable by controlling the fluorine and carbon contents in the oxide film on the surface thereof and the thickness of the oxide film. Such titanium materials are obtainable by dissolving the surface thereof in an aqueous fluonitric acid solution with a nitric acid concentration of not higher than 80 g/l or heat-treating at between 300 and 900° C. in a vacuum or in an inert gas atmosphere of argon or helium after dissolving in the aqueous fluonitric acid solution.

Abstract: Titanium resistant to discoloration in an atmospheric environment characterized by having an average carbon concentration of 14 at % or less in a range to a depth of 100 nm from the surface and having an oxide film of a thickness of 12 to 40 nm at its surface. Titanium resistant to discoloration in an atmospheric environment characterized in that, in X-ray diffraction of its surface, a ratio (X1/X2) of a (200) peak intensity X1 of TiC to a (110) peak intensity X2 of titanium is not more than 0.18 and by having an oxide film of a thickness of 12 to 40 nm at its surface.