Sumitomo Metal Industries, Inc.

Nippon Steel Sumitomo Metal Corporation

Nippon Steel Corporation

Akira Seki

Yoshio Tarutani

Koutarou Hayashi

Takashi Doi

Wataru Takahashi

Hideya Kaminaka

Takeo Kudo

Junko Imamura

Kouichi Takeuchi

Hideaki Yamamoto

Masaru Nishiguchi

Takeo Yazawa

Motomichi Kanbe

Kunihiko Ushio

Kazuya Mishio

Takashi Maeda

Shuhei Shimokawa

Shinji Fukuta

Steel has a chemical composition that contains 0.050% to 0.40% of C, 0.50% to 3.0% of Si, 3.0% to 8.0% of Mn, and 0.001% to 3.0% of sol. Al, by mass %, and has a metallographic structure that contains 10% to 40% of austenite in terms of % by volume. The average concentration of C in austenite is 0.30% by 0.60%, by mass %, structure uniformity, which is represented by a value obtained by subtracting the minimum value from the maximum value of Vickers hardness that is measured, in the metallographic structure is 30 Hv or less, and the tensile strength is 900 MPa to 1800 MPa.

Steel and method of manufacturing the same

Provided is a hot-formed member according to the present invention, having a predetermined chemical composition and having a metallographic microstructure containing austenite at an area ratio of 10 area % to 40 area % and in which total number density of particles of the austenite and martensite is equal to or greater than 1.0 number/&#x3bc;m, in which tensile strength is from 900 MPa to 1300 MPa.

Hot-formed member and manufacturing method of same

A stainless steel member for a separator of a solid polymer fuel cell has excellent cell properties with little deterioration in performance over long periods of operation without worsening of the corrosion resistance of a stainless steel separator. The stainless steel member has a stainless steel base metal, and a passive film and electrically conductive precipitates both provided on a surface of the stainless steel base metal. The electrically conductive precipitate penetrates the passive film and includes a substance originating from the stainless steel base metal. An electrically conductive layer comprising a nonmetallic electrically conductive substance is preferably provided on the surface of the passive film, and the electrically conductive layer is preferably electrically connected to the stainless steel base member through the electrically conductive precipitates.

Stainless steel sheet for a separator for a solid polymer fuel cell and a solid polymer fuel cell employing the separator

A method for producing a stainless steel three-ply clad sheet for a fuel cell separator comprises heating a source blank and then performing rough rolling, hot rolling and cold rolling thereto, whereby the clad steel sheet for the fuel cell separator or a solid polymer type fuel cell separator thereby is obtained. The source blank for the clad steel sheet is composed of a stainless steel utilizing 0 to 0.3% B as a core component and a stainless steel containing 0.3 to 2.5% B as face component. The source blank is made using face components, a core component, tabs and protectors and performing steps including bonding of the tabs and protectors to the face components, removing portions of the tabs and protectors, piling of the face components to the core component, and further bonding of the face and core components together to form the source blank.

Source blank for stainless steel three-ply clad sheet, production methods of clad steel plate and sheet for solid polymer type fuel cell separator, and solid polymer type fuel cell separator

A separator material effective for decreasing the weight of fuel cells is provided which is lightweight, has good corrosion resistance, and exhibits a minimized increase in electrical contact resistance during use for a long period. Titanium or a titanium alloy is prepared by melting so as to contain not greater than 5 mass % B, thereby forming a titanium-based material in which fine TiB-type boride particles are precipitated and dispersed. The material is then etched in an aqueous acidic solution such that some of the TiB-type boride particles are exposed on the surface through the passive film formed thereon.

Titanium-based material for fuel cell separators and a method for the production thereof

The stainless steel product has passive film on the surface, and at least one of a conductive metallic inclusion of carbide and a conductive metallic inclusion of boride protrudes through an outer surface of passive film from stainless steel under the passive film. The stainless steel product has low contact electrical resistance and suitable for use in bipolar plates of a polymer electrode fuel cell.

Stainless steel product for producing polymer electrode fuel cell

A sintered stainless steel exhibiting improved resistance to stress corrosion cracking which comprises a matrix phase and a dispersed phase and a process for manufacturing same are disclosed. The dispersed phase is of an austenitic metallurgical structure and is dispersed throughout the matrix phase which is comprised of an austenitic metallurgical structure having a steel composition different from that of the dispersed phase or a ferrite-austenite duplex stainless steel.

Sintered stainless steel and production process therefor

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Ashiya, Japan

Akira Seki