Nippon Steel Sumitomo Metal Corporation

Nippon Steel & Sumikin Coated Sheet Corporation

Nippon Steel Coated Sheet Corporation

Tomonari Hamamura

Hiromasa Nomura

Hiroshi Kanai

Yuji Kubo

Takao Kanai

Toshiaki Sakamoto

Yoshio Kimata

Hideaki Nasu

Yoichi Tozaki

A surface-treated steel material having cut edge corrosion resistance that is equal to or more than that of a chromate treatment without use of hexavalent chromium. The surface-treated steel material includes a coating film formed on a surface of a steel material through a plating layer that is obtained by immersing the steel material in a galvalume bath containing Mg. The coating film is formed using a coating composition containing a coating film-forming resin, a cross-linking agent, a predetermined vanadium compound, and trimagnesium phosphate; the vanadium compound is a compound satisfying a predetermined electrical conductivity; the content of the vanadium compound is restricted to a predetermined amount; the vanadium compound satisfies a predetermined pH; and the content of the trimagnesium phosphate is a predetermined amount.

Surface-treated steel material

This surface-treated metal includes a metal, and a coated material on a surface of the metal, in which an outermost layer is a photocatalytic film that contains particles showing photocatalytic activity and an organic-inorganic composite resin, a volume ratio of the particles to the film is in a range from 0.5 to 50 vol %, the resin contains a siloxane bond and at least one group selected from the group consisting of an aryl group, a carboxyl group, an amino group, a hydroxyl group, and an alkyl group having 1 to 12 carbon atoms, the coated material has concaves on a surface thereof on the outermost layer side, an area of the outermost layer is 50% to 98% of an area of a surface of the metal, and a surface area of the outermost layer is 101% to 5000% of the area of the surface of the metal.

Surface-treated metal and method for producing same

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Tokyo, Japan

Tomonari Hamamura