Nippon Steel Corporation

Hidetoshi Hatanaka

Kazuhiko Honda

Akira Takahashi

Yoshihiro Suemune

Hajime Onozawa

Tsuyoshi Miyake

Wataru Yamada

Koki Tanaka

The present invention provides a highly corrosion-resistant plated steel sheet that can achieve excellent surface smoothness and formability and, according to the process of the present invention, a hot-dip galvanized steel product excellent in surface smoothness and formability having on the steel product surface a zinc alloy plating layer composed of 4 to 22% by mass of Al, 1 to 5% by mass of Mg, 0.000001 to 0.1% by mass of Ti, 0.000001 to 0.5% by mass of Si and the balance of Zn and unavoidable impurities, the plating layer of the plated steel product having a metal structure in which an [MgSi phase], an [Al phase], a [ZnMg phase] and a [Zn phase] are present in a mixture in the matrix of an [Al/Zn/ZnMg ternary eutectic structure], and the plating layer containing a Ti&#x2014;Al base intermetallic compound in the [Al phase] and/or the [ZnMg phase] and/or the [Zn phase], is produced.

Highly corrosion-resistant hot-dip galvanized steel product excellent in surface smoothness and formability and process for producing same

The object of the present invention is to provide a plated steel sheet capable of securing excellent post-painting corrosion resistance and brightness, and the present invention makes it possible to produce a plated steel sheet excellent in post-painting corrosion resistance and paint coat image clarity by further adding one or more elements selected from among 0.01 to 0.5% of Ca, 0.01 to 0.2% of Be, 0.0001 to 0.2% of Ti, 0.1 to 10% of Cu, 0.001 to 0.2% of Ni, 0.01 to 0.3% of Co, 0.0001 to 0.2% of Cr and 0.01 to 0.5% of Mn, in mass, to the plated layer of the plated steel sheet which is characterized in that the center line average roughness Ra of the Zn alloy plated steel sheet is 1.0 &#x3bc;m or less and the filtered waviness curve Wthereof is 0.8 &#x3bc;m or less, the Zn alloy plated steel sheet having on the surface thereof the plated layer containing 1 to 10% of Mg, 2 to 19% of Al and 0.001 to 2% of Si in mass and other elements the total amount of which is suppressed to 0.5% or less in mass, with the balance consisting of Zn.

Zinc-plated steel sheet excellent in corrosion resistance after coating and clarity of coating thereon

The present invention provides a plated steel material, said plated steel material having a plated layer which contains Al of 4% or more in mass, excellent in surface smoothness even when a cooling rate is low. In the present invention: a plated layer which contains Al of 4% or more in mass and has an Al-type intermetallic compound in an Al phase or abutting on an Al phase is formed on the surface of a steel material; in particular, high corrosion-resistance is secured in various environments by using a plated layer containing Al of 4 to 20% and Mg of 1 to 10% in mass with the balance consisting of Zn and unavoidable impurities or a plated layer containing Al of 4 to 20%, Mg of 1 to 10% and Si of 0.001 to 2% in mass with the balance consisting of Zn and unavoidable impurities; said plated layer contains an intermetallic compound having a melting point of 600&#xb0; C. or higher by 0.001 to 0.5% in mass; and a plated steel material having an excellent surface smoothness is obtained by using an Al-type intermetallic compound wherein at least one of the lattice constants is in the range from 3 to 5 &#x212b;.

Highly corrosion-resistant hot dip plated steel material excellent in surface smoothness

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Kimitsu, Japan

Hidetoshi Hatanaka