Kawasaki Steel Corporation

Jfe Steel Corporation

Other

Mitsubishi Heavy Industries Limited

Mitsubishi Jukogyo Kabushiki Kaisha

Chiaki Kato

Yoichi Tobiyama

Nobuyuki Morito

Kazuhiro Seto

Hajime Kimura

Hisatada Nakakoji

Toshitane Matsukawa

Kenichi Unoki

Akira Yasuda

Yoshitsugu Suzuki

Kei Sakata

Kazuo Mochizuki

Seiji Nakajima

Kazuaki Kyono

Kazumasa Mihara

Shigeru Umino

Tomofumi Shigekuni

Makoto Isobe

Yasuji Uesugi

Masahiko Tada

Kouichi Yasuda

Osamu Furukimi

Hiroki Nakamaru

Toshiyuki Kato

Kazuhide Ishii

Chiyoko Tada

Kyoko Hamahara

Kazunori Osawa

Ritsuo Hashimoto

Akio Shinohara

Masaaki Kohno

Tomokatsu Katagiri

Kazumasa Yoshida

Noriyuki Kawata

Katsuhiro Takebayashi

Kazumi Yamashita

Hideo Sasaoka

Yasuo Hukada

Nobuhiko Uesugi

Disclosed is a phosphated galvanized steel sheet comprising a steel sheet, a zinc-plating layer of &#x3b7; single phase which is formed on at least one side of the steel sheet and contains Ni in an amount of not less than 10 ppm by mass and not more than the solubility limit thereof, and a phosphate layer which is formed on the zinc-plating layer and contains Mg in an amount of not less than 0.1 % by mass and less than 2.0 % by mass. Although this steel sheet is not subjected to sealing, it has corrosion resistance equivalent to or higher than those of conventional steel sheets which have been subjected to sealing, while having excellent blackening resistance.

Phosphate-treated zinc-coated steel sheet

The present invention provides for a zinc-based coated steel sheet having a zinc-based coating layer and a lubricant film, which is formed on the zinc-based coating layer, containing zinc phosphate particles in an amount of 50 wt. % or more, and having substantially no reaction layer formed by reaction between the zinc-based coating and the zinc phosphate particles, and a method for the manufacture thereof. The zinc-based coated steel sheet according to the present invention has an excellent anti-peeling property, excellent frictional property, even in the non-lubricated condition which occurs at areas where the press oil film is broken, and excellent anti-galling property.

Zinc-based coated steel sheet having excellent anti-peeling property, frictional property, and anti-galling property and method of manufacturing the same

A coated steel sheet composed of a steel sheet and at least two types of coating layers formed thereon is provided with an electrodeposition painting having a superior appearance. The coated steel sheet has an arithmetic mean roughness Ra, which is defined by JIS B 0601-, of from about 0.7 to about 1.5 &#x3bc;m and a peak per inch PPI of from about 180 to about 250.

Coated steel sheet provided with electrodeposition painting having superior appearance

A steel composition, in which, Si content is regulated to a given range and Nb and Cu or Ni, Mo are compositively added, and a recrystallization annealing is carried out to form an internal oxide layer just beneath a surface of a steel sheet and a surface oxide simultaneously formed on the surface of the steel sheet is removed by pickling. As a result, the formation of oxides of Si, Mn and the like is considerably decreased on the surface of the steel sheet in a subsequent heating before plating because the above internal oxide layer acts as a diffusion barrier. Thus, there can be obtained high tensile strength hot-dipped steel sheets having a considerably excellent plating property.

High tensile strength hot dip plated steel and method for production thereof

The tin-plated steel sheet includes a base steel sheet; a tin plating layer coating approximately more than 97.0% of the base steel sheet; and a chemical conversion coating having approximately 0.5 to 100 mg/m phosphorus and approximately 0.1 to 250 mg/m silicon formed on the tin plating layer and an unplated region corresponding to approximately less than 3.0%. The tin-plated steel sheet does not contain chromium which is harmful to the environment but has superior overcoat adhesion property, discoloration resistance, and rust resistance.

Tin-plated steel sheet

A surface treated tin-plated steel sheet which has an alloy layer formed on the surface of a steel sheet, a tin plating layer being formed on said alloy layer with a remaining exposed portion of the alloy layer having an area of 30% or more of that of the alloy layer and, formed on said tin plating layer and said exposed portion of the alloy layer, a coating film containing P and Si in an amount of 0.5 to 100 mg/m2 and 0.1 to 250 mg/m2, respectively; and a chemical treatment solution for use in preparing the steel sheet which comprises a phosphate ion, a tin ion and a silane coupling agent and has a pH of 1.5 to 5.5. The surface treated tin-plated steel sheet is free from chromium which causes problems from an environmental view point, and also is excellent in adhesion with a paint, corrosion resistance after being coated, rust resistance, and formability.

Surface treated tin-plated steel sheet and surface treatment solution

The hot dip Zn galvanized steel sheet has excellent balance between tensile strength and ductility and excellent coating adhesion, an average composition of a base steel thereof includes: 0.05-0.25 mass % of C; not more than 2.0 mass % of Si; 1.0-2.5 mass % of Mn; and 0.005-0.10 mass % of Al, wherein the C content at the base steel surface layer portion right under a coating layer is not more than 0.02 mass %, the base steel structure contains not less than 50% of martensite phase, the martensite phase including both tempered martensite phase and fine size martensite phase, and the remaining portion of the base steel structure being formed by ferrite phase and residual austenite phase. A method of producing the hot dip Zn galvanizing steel sheet is described.

Hot dip Galvanized steel plate excellent in balance of strength and ductility and in adhesiveness between steel and plating layer

The high tension steel sheet includes 0.1 wt % or more of silicon and has a zinc-plating layer thereon. When sputtering analysis is performed in the depth direction from the surface of the high tension steel sheet after the zinc-comprising-plating layer is removed by dissolution, a surface-concentrated Si index X defined by the formula, X&equals;(the maximum intensity A of Si on the surface of the high tension steel sheet/the average intensity B of Si in the steel)&times;the content of Si in the steel sheet on a wt % basis, is 12 or less.

Zinc-comprising-plated high tension steel sheet

The present invention provides a high strength thin excellent workability and galvanizability, having a composition comprising from 0.01 to 0.20 wt. % C, up to 1.0 wt. % Si, from 1.0 to 3.0 wt. % Mn, up to 0.10 wt. % P, up to 0.05 wt. % S, up to 0.10 wt. % Al, up to 0.010 wt. % N, up to 1.0 wt. % Cr, from 0.001 to 1.00 wt. % Mo, and the balance Fe and incidental impurities, wherein a band structure comprising a secondary phase has a thickness satisfying the relation Tb/T&lE;0.005 (where, Tb: average thickness of the band structure in the thickness direction of steel sheet; T: steel sheet thickness), and a manufacturing method thereof, and a manufacturing method of a high strength hot-dip galvanized steel sheet or a high strength galvannealed steel sheet applying hot-dip galvanizing or further galvannealing, and giving an excellent workability, a high tensile strength, and excellent galvanizability, coating adhesion and corrosion resistance.

High strength thin steel sheet, high strength alloyed hot-dip zinc-coated steel sheet, and method for producing them

Galvannealed steel sheet and manufacturing method

A hot dip coating apparatus enables stable and continuous production of a coated steel strip having a high degree of uniformity of the coating quality over the breadth of the steel strip and clean coated surfaces free of deposition of dross. The hot dip coating apparatus has a bottom slit through which a steel strip to be coated is introduced and pulled upward through the coating tank, and an electromagnetic sealing device which applies a magnetic field to the molten metal in the coating tank so as to hold the molten metal inside the tank. The coating tank is provided at its top with an overflow dam for allowing the molten mental to overflow out of the coating tank. The apparatus also has a molten metal supply system which produces a circulating flow of the molten metal through the coating tank. The molten metal supply system has molten metal buffers which communicate with a molten metal supply passage and from which the molten metal is discharged towards the steel strip.

Hot dip coating apparatus

Plated steel sheet

A process for producing plated steel sheet comprises the steps of heating a steel slab containing not more than 0.5 wt % C to the temperature range not lower than the transformation point Ac.sub.3, and jetting high-pressure water to the surface of a steel sheet at a discharge pressure of 300 kgf/cm.sup.2 or more at least once during hot rough rolling and hot finish rolling, thereby removing a layer of iron oxide on the surface of the steel sheet. The steel sheet is thereafter coiled while keeping a finishing delivery temperature of the steel sheet in the range of 500-800.degree. C., reducing the layer of iron oxide on the surface of the steel sheet at 50-98 % in an annealing furnace with the temperature of the steel sheet held in the range of 750-900.degree. C., and plating the steel sheet. With the process of the invention, plated steel plates having superior workability and plating adhesion can be produced at low cost, even when cold rolling and pickling are omitted from the production steps.

Process for producing plated steel sheet

A hot dip coating apparatus and method, enables stable and continuous production of a coated steel strip having a high degree of uniformity of the coating quality over the breadth of the steel strip and clean coated surfaces free of deposition of dross. The hot dip coating apparatus has a bottom slit through which a steel strip to be coated is introduced and pulled upward through the coating tank, and an electromagnetic sealing device which applies a magnetic field to the molten metal in the coating tank so as to hold the molten metal inside the tank. The coating tank is provided at its top with an overflow dam for allowing the molten metal to overflow out of the coating tank. The apparatus also has a molten metal supply system which produces a circulating flow of the molten metal through the coating tank. The molten metal supply system has molten metal buffers which communicate with a molten metal supply passage and from which the molten metal is discharged towards the steel strip.

Hot dip coating apparatus and method

Method and apparatus for holding molten metal

Growing community of inventors

Chiba, Japan

Chiaki Kato