Abstract: A stainless steel material including a base material made of ferritic stainless steel, a Cr oxide layer formed on a surface of the base material, and a spinel oxide layer formed on a surface of the Cr oxide layer, wherein a chemical composition of the base material satisfies [16.0?Cr+3×Mo?2.5×B?17×C?3?Si?35.0], a thickness of the Cr oxide layer (TCr) and a thickness of the spinel oxide layer (TS) satisfy [0.55?TCr/TS?6.7], the base material contains precipitate including one or more kinds selected from a M23C6, a M2B, a complex precipitate in which M2B acts as a precipitation nucleus, and M23C6 precipitates on a surface of the M2B, and a complex precipitate in which NbC acts as a precipitation nucleus, and M23C6 precipitates on a surface of the NbC, and a part of the precipitate protrude from the surface of the Cr oxide layer.

Abstract: A stainless steel material including a base material made of ferritic stainless steel, a Cr oxide layer formed on a surface of the base material, and a spinel oxide layer formed on a surface of the Cr oxide layer, wherein a chemical composition of the base material satisfies [16.0?Cr+3×Mo?2.5×B?17×C?3?Si?35.0], a thickness of the Cr oxide layer (TCr) and a thickness of the spinel oxide layer (TS) satisfy [0.55?TCr/TS?6.7], the base material contains precipitate including one or more kinds selected from a M23C6, a M2B, a complex precipitate in which M2B acts as a precipitation nucleus, and M23C6 precipitates on a surface of the M2B, and a complex precipitate in which NbC acts as a precipitation nucleus, and M23C6 precipitates on a surface of the NbC, and a part of the precipitate protrude from the surface of the Cr oxide layer.

Abstract: A carbon separator for a solid polymer fuel cell is provided that includes a core material made of steel, and a carbon layer. The chemical composition of the steel is, by mass %, C: more than 0.02% to 0.12% or less, Si: 0.05 to 1.5%, Al: 0.001 to 1.0%, Mn: 0.01 to 1.0%, P: 0.045% or less, S: 0.01% or less, N: 0.06% or less, V: 0.5% or less, Cr: more than 13.0% to less than 25.0%, Mo: 0 to 2.5%, Ni: 0 to 0.8%, Cu: 0 to 0.8%, REM: 0 to 0.1%, B: 0 to 1.0%, Sn: 0 to 2.5%, In: 0 to 0.1%, and the balance: Fe and impurities. The steel has therein precipitates including M23C6 type Cr carbides that are finely precipitated and dispersed. A part of the precipitates protrude from the steel surface.

Abstract: A carbon separator for a solid polymer fuel cell is provided that includes a core material made of steel, and a carbon layer. The chemical composition of the steel is, by mass %, C: more than 0.02% to 0.12% or less, Si: 0.05 to 1.5%, Al: 0.001 to 1.0%, Mn: 0.01 to 1.0%, P: 0.045% or less, S: 0.01% or less, N: 0.06% or less, V: 0.5% or less, Cr: more than 13.0% to less than 25.0%, Mo: 0 to 2.5%, Ni: 0 to 0.8%, Cu: 0 to 0.8%, REM: 0 to 0.1%, B: 0 to 1.0%, Sn: 0 to 2.5%, In: 0 to 0.1%, and the balance: Fe and impurities. The steel has therein precipitates including M23C6 type Cr carbides that are finely precipitated and dispersed. A part of the precipitates protrude from the steel surface.

Abstract: There is provided a separator for polymer electrolyte fuel cells having a substrate of a ferritic, having a chemical composition comprising, in mass %, C: 0.001 to 0.012%, Si: 0.01 to 0.6%, Mn: 0.01 to 0.6%, P: 0.035% or less, S: 0.01% or less, Cr: 22.5 to 35.0%, Mo: 0.01 to 4.5%, Ni: 0.01 to 2.5%, Cu: 0.01 to 0.6%, Sn: 0.01 to 1.0%, In: 0.001 to 0.30%, N: 0.015% or less, V: 0.01 to 0.35%, and Al: 0.001 to 0.050%, and the calculated value of {Content of Cr (%)+3×Content of Mo (%)} being 22.5 to 45.0, and includes a surface modified layer containing O: less than 30% and the balance: Sn and In. A polymer electrolyte fuel cell including the separator is remarkably excellent in corrosion resistance in an in-cell environment.

Abstract: A stainless steel sheet used for a separator of a polymer electrolyte fuel cell, wherein the steel sheet has a volume ratio of M2B boride-based metal precipitates of 8% or higher and a volumetric-basis particle-size frequency distribution of M2B boride-based metal precipitates having sphere-equivalent diameters of 6.72 ?m or less of 99.5% or higher, in a surface layer which has a depth of 0.2 t from at least one of surfaces (t is an overall thickness of the steel sheet), and the steel sheet has an apparent density of 0.995 or higher, assuming a real density to be 1. A polymer electrolyte fuel cell in which the stainless steel sheet is used for a separator is given an excellent cell performance without high-cost surface treatment such as expensive gold plating for the reduction of the contact resistance of a surface.

Abstract: There is provided a ferritic stainless steel material that has a chemical composition comprising, in mass %: C: 0.001 to 0.030%, Si: 0.20 to 1.5%, Mn: 0.01 to 1.5%, P: 0.035% or less, S: 0.01% or less, Cr: 22.5 to 35.0%, Mo: 0.01 to 6.0%, Ni: 0.01 to 6.0%, Cu: 0.01 to 1.0%, Sn: 0.10 to 2.5%, In: 0.001 to 1.0%, N: 0.035% or less, V: 0.01 to 0.35%, Al: 0.001 to 1.0%, and the balance of Fe and inevitable impurities, and the calculated value of {Content of Cr (mass %)+3×Content of Mo (mass %)} being 22.5 to 45.0%. A polymer electrolyte fuel cell including a separator for which the steel material is used is remarkably excellent in corrosion resistance in an in-cell environment and has a contact electric resistance the same as that of a gold-plated member.

Abstract: A ferritic stainless steel material is provided that has a chemical composition containing, by mass %, C: 0.001 to less than 0.020%, Si: 0.01 to 1.5%, Mn: 0.01 to 1.5%, P: 0.035% or less, S: 0.01% or less, Cr: 22.5 to 35.0%, Mo: 0.01 to 6.0%, Ni: 0.01 to 6.0%, Cu: 0.01 to 1.0%, N: 0.035% or less, V: 0.01 to 0.35%, B: 0.5 to 1.0%, Al: 0.001 to 6.0%, Sn: 0.02 to 2.50%, rare earth metal: 0 to 0.1%, Nb: 0 to 0.35%, Ti: 0 to 0.35%, and the balance: Fe and impurities, in which a value calculated as {Cr content (mass %)+3×Mo content (mass %)?2.5×B content (mass %)} is from 20 to 45%, and M2B boride-based metallic precipitates are dispersed in and exposed on the surface of a parent phase composed only of a ferritic phase.

Abstract: A ferritic stainless steel material contains, by mass %, C: 0.02 to 0.15%, Si: 0.01 to 1.5%, Mn: 0.01 to 1.5%, P: 0.035% or less, S: 0.01% or less, Cr: 22.5 to 35.0%, Mo: 0.01 to 6.0%, Ni: 0.01 to 6.0%, Cu: 0.01 to 1.0%, N: 0.035% or less, V: 0.01 to 0.35%, B: 0.5 to 1.0%, Al: 0.001 to 6.0%, rare earth metal: 0 to 0.10%, Sn: 0 to 2.50%, and the balance: Fe and impurities, and a value calculated in mass % as {Cr+3×Mo?2.5×B?17×C} ranges from 20 to 45%. The ferritic stainless steel material has a parent phase comprising only a ferritic phase. At least composite metallic precipitates including M23C6 carbide-based metallic precipitates precipitated on surfaces and at peripheries of M2B boride-based metallic precipitates serving as precipitation nuclei are dispersed and exposed on a parent phase surface.

Abstract: 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.

Abstract: 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.

Abstract: Provided is a first method for producing a source blank for a clad steel sheet composed of a stainless steel containing 0 to 0.3% B as a core component and a stainless steel containing 0.3 to 2.

Abstract: 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.

Abstract: 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.

Abstract: A stainless steel having excellent corrosion resistance to ozone added water, such as ozone added ultrapure water used in semiconductor manufacturing processes and the like, as well as a manufacturing method. The stainless steel comprises a base metal and an oxide film formed on the surface of the base metal, the base metal being a stainless steel which contains 12 to 30% of Cr, 0 to 35% of Ni, and 1 to 6% of Al and Si while the contents of the other alloying elements are limited to as low a level as possible, the oxide film mainly comprising Al oxide or a Si oxide or both. The oxide film may be formed on the base metal surface through the dry oxidation process or the wet oxidation process. In the stainless steel, metallic ions are rarely dissolved from the base metal into the ozone added water.

Abstract: The invention or the instant application relates to a process for manufacturing a colored metal plate, in that forming an electrophotosensitive layer mainly composed of titanium dioxide and a binder resin on a metal plate as a raw material having a smooth surface of 2 .mu.m Ra or less in the center line average height, and then forming an toner image having a surface granularity of 0.3 or less on the photosensitive layer by electrophotographic method.

Abstract: A superplastic hot working method for a duplex-phase, nitrogen-containing ferrous alloy and stainless steel, and a superplastic duplex-phase ferrous alloy are disclosed. The ferrous alloy comprises: at least one of Si and Mn in an amount of not less than 0.5 % and not less than 1.7%, respectively; and N: at least 0.01% in solid solution, wherein Si eq and Mn eq which are defined as: Si eq=Si+(2/3) (Cr+Mo), and Mn eq=Mn+2Ni+60C+50N, satisfy the formula:(5/6) (Si eq)-15/2.ltoreq.Mn eq.ltoreq.(11/5)(Si eq)-77/5,and its superplastic hot working is carried out by deforming the alloy heated to 700.degree.-1200.degree. C. at a strain rate of 1.times.10.sup.-6 S.sup.-1 to 1.times.10.sup.0 S.sup.-1. In another aspect, superplastic hot working of a duplex-phase stainless steel comprising Cr: 10.0-35.0%, Ni: 2.0-18.0%; Mo: 0-6.0%, and N: 0.005-0.3% and having the values of Si eq and Mn eq as above is carried out by deforming the steel at a strain rate of from 1.times.10.sup.-6 S.sup.-1 to 1.times.10.sup.1 S.sup.

Abstract: 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.

Abstract: A superplastic hot working method for a duplex-phase, nitrogen-containing ferrous alloy and stainless steel, and a superplastic duplex-phase ferrous alloy are disclosed. The ferrous alloy comprises: at least one of Si and Mn in an amount of not less than 0.5% and not less than 1.7%, respectively; and N: at least 0.01% in solid solution, wherein Si eq and Mn eq which are defined as:Si eq=Si+(2/3)(Cr+Mo), and Mn eq=Mn+2 Ni+60 C+50 N,satisfy the formula:(5/6)(Si eq)-15/2.ltoreq.Mn eq.ltoreq.(11/5)(Si eq)-77/5,and its superplastic hot working is carried out by deforming the alloy heated to 700.degree.-1200.degree. C. at a strain rate of 1.times.10.sup.-6 S.sup.-1 to 1.times.10.sup.0 S.sup.-1. In another aspect, superplastic hot working of a duplex-phase stainless steel comprising Cr: 10.0-35.0%, Ni: 2.0-18.0%, Mo: 0-6.0%, and N: 0.005-0.3% and having the values of Si eq and Mn eq as above is carried out by deforming the steel at a strain rate of from 1.times.10.sup.-6 S.sup.-1 to 1.times.10.sup.1 S.sup.

Abstract: A sintered stainless steel and sintered seamless steel pipe exhibiting improved resistance to stress corrosion cracking are disclosed. The metallurgical structure comprises a matrix phase and a dispersing phase, which are different from each other in their metallurgical structures, the matrix phase comprising a substantially single ferritic structure, and the dispersing phase comprising a structure selected from the group consisting of an austenitic structure, an austenitic+ferritic dual phase structure, an austenitic+martensitic dual phase structure, and an austenitic+ferritic+martensitic triple phase structure. The sintered seamless stainless steel pipes are useful as heat exchanging tubes and piping to which sea water or industrial water is fed.