Nippon Steel Sumitomo Metal Corporation

Nippon Steel Corporation

Sintokogio, Ltd.

Usinor

Yoichi Ikematsu

Kazuhiko Honda

Koki Tanaka

Noriyuki Suzuki

Michio Kaneko

Hiroshi Kihira

Mitsuharu Yamagata

Akira Takahashi

Masayoshi Suehiro

Yoshihisa Takada

Yoichi Matsuzaki

Wataru Hisada

Hideaki Sawada

Kazuto Kawakami

Shunichi Hayashi

Suguru Suzuki

Yoshihiro Suemune

Tetsuo Nishiyama

Takeo Itoh

The production method of the galvannealed steel sheet includes: performing a hot dip galvanization on a steel sheet; performing an alloying and forming a galvannealed layer; performing a skin pass rolling at an elongation ratio of 0.3% or more; applying a treatment liquid on a surface of the galvannealed layer using a roll coater, and allowing the treatment liquid to react with the surface immediately after the application to form a mixed layer; in the forming the mixed layer: a first applied part is formed in the mixed layer using the protrusions of the roll coater; and a second applied part is formed in the mixed layer using the recesses of the roll coater; the second applied part having an attached amount of P of 20 mg/mor more, a surface area of the second applied part being 20% to 80% of a surface areas of the mixed layer.

Production method of galvannealed steel sheet having excellent formability and exfoliation resistance after adhesion

A galvannealed steel sheet includes: a steel sheet; a galvannealed layer which is formed on at least one surface of the steel sheet and includes Al, Fe, and the balance composed of Zn and inevitable impurities; and a composite oxide layer of Mn, Zn, and P which is formed on the surface of the galvannealed layer, includes Mn, P, and Zn, and has the P/Mn ratio of equal to or higher than 0.3 and equal to or lower than 50. The galvannealed layer includes a flat portion having an area ratio of equal to or higher than 10% and equal to or lower than 70% and a rough portion which is at a position closer to the steel sheet than the flat portion at the interface of the galvannealed layer and the composite oxide layer. The composite oxide layer of Mn, Zn, and P contains an amorphous compound.

Galvannealed steel sheet and producing method thereof

The galvannealed steel sheet includes: a galvannealed layer formed on at least one surface of a steel sheet and contains includes an amount of 0.05 mass % to 0.5 mass % of Al, an amount of 6 mass % of 12 mass % of Fe, and the balance composed of Zn and inevitable impurities; and a mixed layer formed on a surface of the galvannealed layer and includes a composite oxide of Mn, Zn, and P and an aqueous P compound, wherein the composite oxide includes 0.1 mg/mto 100 mg/mof Mn, an amount of 1 mg/mto 100 mg/mof P, and Zn, and a P/Mn ratio is 0.3 to 50, and wherein the total size of an area of the mixed layer in which an attached amount of P is equal to or more than 20 mg/mis 20% to 80% of a surface area of the mixed layer.

Galvannealed steel sheet having excellent formability and exfoliation resistance after adhesion and production method thereof

Hot dip galvanized steel sheet excellent in shapeability and plateability comprised of high strength steel sheet according to the present invention can be provided containing, by mass % about, C: 0.05 to 0.25%, Si: 0.3 to 2.5%, Mn: 1.5 to 2.8%, P: 0.03% or less, S: 0.02% or less, Al: 0.005 to 0.5%, N: 0.0060% or less and the balance of Fe and unavoidable impurities. The exemplary steel sheet can have thereon a galvanized layer containing, e.g., about Al: 0.05 to 10 mass % and Fe: 0.05 to 3 mass % and the balance of Zn and unavoidable impurities. Such exemplary hot dip galvanized steel sheet can have oxides containing Si in an average content of about 0.6 to 10 mass % at the crystal grain boundaries and in the crystal grains at the sheet steel side 5 &#x3bc;m or less from the interface between the high strength steel sheet and the plating layer and by the presence of Fe&#x2014;Zn alloy with an average grain size of about 0.5 to 3 &#x3bc;m at the plating side.

High strength hot dip galvanized steel sheet and high strength galvannealed steel sheet excellent in shapeability and plateability

The present invention releases a method of producing a metal separator for a solid polymer fuel cell by stainless steel, titanium, or titanium alloy during which securing lower cost and mass producibility by using a material having a high workability to form a complicated shape by a high productivity, then using an inexpensive blast process to drive a conductive substance into the surface of the metal separator member, that is, provides a stainless steel, titanium, or titanium alloy solid polymer fuel cell separator comprised of stainless steel, titanium, or titanium alloy in the surface of which a low ion release conductive substance is buried, having an arithmetic mean roughness (Ra) of the separator surface of 0.5 to 5.0 &#x3bc;m, having a 10-point mean roughness (Rz) of 3 to 20 &#x3bc;m, having an average spacing of surface relief shapes (Sm) of 300 &#x3bc;m or less, having values of a warp rate and twist rate of a separator of 0.1 or less, and having a contact resistance value with respect to carbon paper of 15 m&#x3a9;cmor less at a surface pressure of 1 MPa.

Stainless steel, titanium, or titanium alloy solid polymer fuel cell separator and its method of production and method of evaluation of warp and twist of separator

The present invention provides an alloyed molten zinc plated steel sheet having an area of the Fe and Zn alloy phase in the unformed parts in the plating layer of less than 10% of the area of the steel sheet as a whole and superior in strength and shapeability and a method of producing this alloyed molten zinc plating steel sheet by a continuous zinc plating production system which enables production at a low cost without modification of the system or addition of steps, said alloyed molten zinc plated steel sheet characterized by comprising a steel sheet including C: 0.05 to 0.40%, Si: 0.2 to 3.0%, and Mn: 0.1 to 2.5%, the balance comprised of Fe and unavoidable impurities, having on its surface a Zn alloy plating layer comprised of Fe in a concentration of 7 to 15 wt %, Al in a concentration of 0.01 to 1 wt %, and the balance of Zn and unavoidable impurities, said plating layer containing oxide particles of at least one type of oxide selected from an Al oxide, Si oxide, Mn oxide, and complex oxides of the same alone or in combination.

Alloyed molten zinc plated steel sheet and process of production of same

A molten zinc plated steel sheet superior in plating bondability and provided with both strength and shapeability is provided and a method of producing this molten zinc plating steel sheet by a continuous zinc plating production system which enables production at a low cost without modification of the system or addition of steps is provided, said molten zinc plated steel sheet characterized by comprising, by wt %, a steel sheet including C: 0.05 to 0.40%, Si: 0.2 to 3.0%, and Mn: 0.1 to 2.5%, the balance comprised of Fe and unavoidable impurities, having on its surface a Zn plating layer containing Al: 0.01 to 1% and the balance of Zn and unavoidable impurities and containing inside the steel sheet within 2 &#x3bc;m from the interface of said plating layer and steel sheet oxide particles of at least one type of oxide selected from an Al oxide, Si oxide, Mn oxide, or complex oxide comprised of at least two of Al, Si, and Mn.

High strength molten zinc plated steel sheet and process of production of same

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Futtsu, Japan

Yoichi Ikematsu