Nippon Steel Corporation

Nippon Steel Sumitomo Metal Corporation

Nihon Parkerizing Co., Ltd.

Bluescope Steel Limited

Nippon Steel & Sumikin Coated Sheet Corporation

Nippon Steel Coated Sheet Corporation

Shiro Fujii

Nobuyuki Shimoda

Tatsuo Yokoi

Takao Ogino

Hiroshi Kanai

Yasuharu Sakuma

Yasuhide Morimoto

Yoshihiro Suemune

Takayuki Aoki

Wayne Andrew Renshaw

Atsushi Itami

Joe Williams

Arata Suda

Kohsaku Ushioda

Tooru Oohashi

Nobuki Shiragaki

Cat Tu

Makoto Tezuka

Jason Hodges

Makoto Yoshida

Motoo Kabeya

Yoshio Shindou

Teruaki Izaki

Shuichi Kondo

Takashi Hirasawa

Yoshikazu Yamanaka

A method of forming an Al&#x2014;Zn&#x2014;Si&#x2014;Mg alloy coating on a steel strip includes dipping steel strip into a bath of molten Al&#x2014;Zn&#x2014;Si&#x2014;Mg alloy and forming a coating of the alloy on exposed surfaces of the steel strip. The method also includes controlling conditions in the molten coating bath and downstream of the coating bath so that there is a uniform Al/Zn ratio across the surface of the coating formed on the steel strip. An Al&#x2014;Zn&#x2014;Mg&#x2014;Si coated steel strip includes a uniform Al/Zn ratio on the surface or the outermost 1-2 &#x3bc;m of the Al&#x2014;Zn&#x2014;Si&#x2014;Mg alloy coating.

Metal-coated steel strip

The present invention provides a hot-dipped steelthat demonstrates favorable corrosion resistance and formability, and has a favorable appearance of a plating layer. The hot-dipped steel of the present invention includes a steel substrate formed thereon with an aluminum-zinc alloy plating layer. The aluminum-zinc alloy plating layer contains Al, Zn, Si and Mg as constituent elements thereof and the Mg content is 0.1% to 10% by weight. The aluminum-zinc alloy plating layer contains 0.2% to 15% by volume of an Si&#x2014;Mg phase, and the weight ratio of Mg in the Si&#x2014;Mg phase to the total weight of Mg is 3% or more.

Hot-dipped steel and method of producing same

Ultra low carbon, cold rolled steel sheet and galvanized steel sheet

A chromating liquid for forming a chromate film on a Zn or Zn-alloy plated steel sheet, is prepared by adding and mixing a silane coupling agent in a molar ratio of from 0.05 to 0.3 relative to Cr.sup.6+ contained in an aqueous chromating liquid which contains 1-30 g/l of Cr.sup.6+ and 1-30 g/l of Cr.sup.3+ at a weight ratio of Cr.sup.6+ /Cr.sup.3+ ranging from 0.1 to 2.0; and further contains 1-59 g/l of hydrofluoric acid and 1-59 g/l of phosphoric acid at total of hydrofluoric acid and phosphoric acid ranging from 2 to 60 g/l and at a weight ratio of (fluoride ions+phosphate ions)/Cr.sup.3+ ranging from 0.5 to 3.5. and, further said chromating liquid is applied on a surface of the zinc-based plated steel sheet and is then dried, thereby forming the chromate film having a coating amount of from 10 to 150 mg/m.sup.2 in terms of the chromium.

Chromating method of zinc-based plated steel sheet

Growing community of inventors

Tokyo, Japan

Shiro Fujii