Nippon Steel Corporation

Yoshio Shindou

Fumio Yamazaki

Motoo Kabeya

Takashi Shimazu

Katushi Saito

Taketoshi Taira

Joji Oka

Saburo Hinenoya

Yujiro Miyauchi

Mansei Tanaka

Toshimichi Murata

Yoshihiro Inuizawa

Shirou Fujii

Makoto Nakamura

Masami Ishida

Fuyuhiko Ohtsuki

Kazuyuki Suzuki

The present invention provides a method for producing a highly corrosion resistant organic composite-plated steel sheet which is inhibited from liberation of chromium, which comprises forming a chromate film comprising a composition of the following (A) as a first layer at a coating amount of 5-150 mg/m.sup.2 as a solid film on the surface of a zinc or zinc alloy plated or zinc composite alloy plated steel sheet and then, coating on the first layer an organic solvent coating composition of the following (B) as a second layer at a thickness of 0.3-5 .mu.m as a solid film.

Method of producing organic composite-plated steel sheet

Disclosed are electro-plated steel sheets having a primer coating composed of 5 to 30% by weight of Cr, 0.005 to 5% by weight of cation polymer, with the balance being Zn, with or without a further Zn or Zn-alloy coating formed on the primer coating. The primer coating may contain fine particles of oxides and/or iron-group metals, and may further be applied with a chromate film and/or an organic coating. Also disclosed is the process for producing an electro-plated steel sheet having excellent corrosion resistance and surface brightness, comprising performing electro-plating in an acidic Zn plating bath containing Cr ions and cation polymer, with the ratio of Cr.sup.6+ ions/Cr.sup.3+ ions being not more than 0.1.

Coated steel sheets and process for producing the same

Coated steel sheets

This invention provides an organic multicoated steel sheet susceptible to cationic electrodeposition coating which comprises a zinc or zinc alloy plated steel sheet and as a first layer provided on the surface of said plated steel sheet a sparely soluble chromate film of 1-30% in water soluble matter, 0.01-1.0 in Cr.sup.6+ /Cr.sup.3+ ratio and 10-150 mg/m.sup.2 in total chromium application amount on one surface and as a second layer provided said first layer a solid film having a thickness of 0.3-5 .mu.m of a solvent type coating composition having the following composition based on the weight of non-volatile matter:

Multicoated steel sheet susceptible to cationic electrodeposition coating

This invention provides a highly corrosion-resistant, colored thin film-coated steel sheet having excellent press-processability and spot-weldability, which comprises a plated steel sheet, a first layer of a sparingly soluble chromate film formed on surface(s) of the plated steel sheet and having a water soluble content of 1 to 30%, a Cr.sup.6+ /Cr.sup.3+ ratio of 0.01 to 1.0 and a total chromium build-up of 10 to 150 mg/m.sup.2 on one surface, and a second layer of a 0.3 to 5 .mu. thick solid coating film formed of an organic solvent-type coating composition, the solid coating film being comprised, based on the weight of the nonvolatile content, of

Highly corrosion-resistant, colored thin film-coated steel sheet having

A one-side electrogalvanized steel sheet with a distinguished susceptibility to a phosphate salt treatment and a distinguished appearance on the non-electrogalvanized side is produced by subjecting the non-electrogalvanized side of a steel sheet after one-side electrogalvanization in a galvanizing bath to an electrolytic peeling treatment using the non-electrogalvanized side of the one-side electrogalvanized steel sheet as an anode in an electrolytic peeling treatment bath containing 5 to 30% by weight of sodium sulfate as an electroconductive agent and at least 0.1% by weight of boric acid as a pH-controlling agent at a pH adjusted to a range of 5.0 to less than 9.0 as a posttreatment of the non-electrogalvanized side.

Process for producing one-side electrogalvanized steel sheet with

Disclosed is a Zn-Ni based composite plated steel sheet excellent in corrosion resistance and workability which comprises a ferrous substrate and, provided thereon, a Zn-Ni based composite electroplating layer comprising 1-15% by weight of Ni, 0.1-10% by weight of Cr, 0.1-10% by weight of SiO.sub.2, 0.01-3% by weight of Fe and the balance being essentially Zn. This steel sheet may further have a Zn or Zn based alloy electroplating upper layer to further improve corrosion resistance after coating. Furthermore, in order to remarkably improve corrosion resistance, the steel sheet may further have a hardly soluble chromate film layer of 10-150 mg/m.sup.2 in total Cr content and an epoxy resin thin film layer containing agglomerated SiO.sub.2 provided on said chromate film layer.

Zn-Ni based composite electroplated steel sheet and multi-layer

The present invention provides an organic composite plated steel sheet highly susceptible to cationic electrodeposition comprising a steel substrate plated with one selected from the group consisting of zinc, a zinc alloy, a zinc composite alloy, or aluminum, and a first layer of a less soluble chromate film having a water soluble content of 5% or less formed on the substrate in an amount of 10 to 150 mg as the total amount of chromium per square meter, and a second layer as a solid thin coating film of 0.1 to 2 .mu.m formed on the first layer, the second layer being formed with a coating composition containing 10 to 50% by weight of solids comprising:

Organic composite plated steel sheet highly susceptible to cationic

Disclosed is a steel sheet having an organic composite plating layer excellent in press workability, spot weldability, electrodeposition coatability and corrosion resistance which comprises a zinc plated, aluminum plated or zinc base composite alloy plated steel sheet, a first layer of an insoluble chromate film of 5% or less in the content of water-soluble matter formed on the surface of the steel sheet at a coverage of 10-150 mg/m.sup.2 in terms of chromium content and a second layer of a coating composition having the following composition coated at a thickness of 0.3-5 .mu.m as a solid film on said first layer:

Organic composite-plated steel sheet

A colored zinc composite-plated steel sheet which comprises a steel sheet or a plated steel sheet, a colored composite-plating film comprising zinc and an oxide of a coloring metal such as nickel, cobalt, iron, chromium, tin or copper and provided on the steel sheet at a coverage of 0.1-5 g/m.sup.2 and a transparent guard coat of 3 .mu.m or less thick provided on the film is obtained by carrying out electrolysis in an acidic aqueous solution containing zinc ion, a coloring metal ion and nitrate ion, nitrite ion, perchlorate ion, chlorate ion, condensed phosphate ion and having a pH of 1-4 using the steel sheet or plated steel sheet as a cathode at a current density of 5-100 A/dm.sup.2 and a current quantity of 20-200 coulomb/dm.sup.2.

Method of making a black surface treated steel sheet

A Zn-Al hot-dip galvanized coating on a steel sheet may exhibit intergranular corrosion and be degraded due to the Al's secular enrichment in the grain boundaries of coating. This is prevented in accordance with the present invention by the galvanizing bath composition which contains from 0.15 to 10% of Al, from 0.1 to 1% of Sb, from 0.01 to 2% of Si, and the balance being Zn and unavoidable impurities such as Pb, Sn, and Cd in an amount less than 0.02%, and additionally contains at least from 0.01 to 1% of at least one member selected from the group consisting of Mg and mischmetal.

Zn-Al hot-dip galvanized steel sheet having improved resistance against

A Zn-Al hot dip galvanized steel sheet having an improved resistance to secular peeling of a galvanized layer, characterized by a composition of the layer and galvanizing bath which consist of from more than 0.3 wt % to 10 wt % of Al, from 0.2 to 1.0 wt % of Sb, a total of less than 0.02 wt % of impurities including Pb and Sn, and a balance of Zn.

A weldable steel plate plated with zinc, a zinc base alloy or zinc composite and coated on the plating with a coating material comprising a mixture of at least one type of ferrous alloy powder with an oxygen concentration of 1.0% by weight or less and zinc dust, is provided, and the weldable coated steel plate also has good workability, coherence, weldability and corrosion resistance.

Anticorrosive weldable coated steel

A polypropylene coated steel pipe comprising a steel pipe, an adhesive layer coated on the external surface of the steel pipe, which has been subjected to a pretreatment, and a polypropylene layer coated on the adhesive layer. The outermost polypropylene layer comprises, as a main constituent, a crystalline ethylene-propylene block copolymer and the adhesive layer comprises a modified polyolefin adhesive.

Polypropylene coated steel pipe

In repairing by electrodeposition coating an end or top plate of an easy-open can along a score groove where the material metal has been exposed or along a deteriorated coated film chiefly on the reverse side of said end, a sine wave A. C. voltage is imparted as the bath voltage under the particular conditions, wherein the electric current of reverse direction is effectively utilized to effect penetration of the deteriorated coated part or removal of wax. In this case, special advantage can be obtained if an electrode made of the particular metal having an anodic oxidation film thereon is used.

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Kimitsu, Japan

Yoshio Shindou