Nippon Steel Corporation

Nippon Steel Stainless Steel Corporation

Yoshio Tarutani

Takumi Nishimoto

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&#x2264;Cr+3&#xd7;Mo&#x2212;2.5&#xd7;B&#x2212;17&#xd7;C&#x2212;3&#x2212;Si&#x2264;35.0], a thickness of the Cr oxide layer (T) and a thickness of the spinel oxide layer (T) satisfy [0.55&#x2264;T/T&#x2264;6.7], the base material contains precipitate including one or more kinds selected from a MC, a MB, a complex precipitate in which MB acts as a precipitation nucleus, and MCprecipitates on a surface of the MB, and a complex precipitate in which NbC acts as a precipitation nucleus, and MCprecipitates on a surface of the NbC, and a part of the precipitate protrude from the surface of the Cr oxide layer.

Stainless steel material, constituting component, cell, and fuel cell stack

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 MCtype Cr carbides that are finely precipitated and dispersed. A part of the precipitates protrude from the steel surface.

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Tokyo, Japan

Yoshio Tarutani