Nkk Corporation

Tokyo Shibaura Denki Kabushiki Kaisha

Nippon Kokan Kabushiki Kaisha

Kabushiki Kaisha Toshiba

Nkk Cororation

Jfe Steel Corporation

Junichi Inagaki

Masaaki Yamashita

Masaru Sagiyama

Akira Hiraya

Mitsuru Yamaura

Masaki Abe

Michitaka Sakurai

Ryotaro Kondow

Masaya Morita

Toyofumi Watanabe

Toru Imokawa

Yoshikazu Takada

Kaoru Sato

Yoshiharu Sugimoto

Kenji Tahara

Kazuhide Nakaoka

Takayuki Urakawa

Satoshi Hashimoto

Akira Hiura

Yuji Yamasaki

Masaki Tada

Eiichi Okamoto

Satoru Ando

Masayasu Nagoshi

Masayasu Ueno

Fumio Andow

Yuichi Fukushima

Yukio Kimura

Shoichiro Taira

Sadakazu Masuda

Hisato Noro

Akira Gamou

Shuji Nomura

Yoichi Miyakawa

Masahiro Iwabuchi

Keiji Yoshida

Nobuyuki Ishida

Takafumi Yamaji

Toshihiko Ooi

Fumio Fujita

Masamoto Kamata

Kunio Matsuzawa

Takashi Ariizumi

Masahiro Hattori

Hachidai Ito

Yasuhiro Sodani

Shunsaku Node

Norio Inoue

Shogo Tomita

Yuji Okami

Yuichiro Tanaka

Masahiko Yoshini

Shinji Hori

Yasuhiro Majima

The method for manufacturing galvanized steel sheet has a step of adjusting the surface texture thereof by blasting solid particles against the surface thereof. The surface texture is defined by at least one parameter selected from the group of parameters consisting of mean roughness Ra on the surface of steel sheet, peak count PPI on the surface of steel sheet, and filtered centerline waviness Wca on the surface of steel sheet. The galvanized steel sheet has a surface in dimple-pattern texture.

Galvanized steel sheet, method for manufacturing the same, and method for manufacturing press-formed product

The invention provides a galvannealed steel sheet which has an oxide layer having 10 nm or larger thickness on the plateau of the coating layer flattened by temper rolling. With the use of the galvannealed steel sheet, no powdering occurs during press-forming, and stable and excellent sliding performance is attained. By selecting the area percentage of the plateau of the flattened coating layer to a range from 20 to 80%, making the coating layer single layer of &dgr; phase, and letting &zgr; phase exist in the &dgr; phase, further improved sliding performance and anti-powdering property are obtained.

Galvannealed steel sheet and method for manufacturing the same

The method for manufacturing coated steel sheet has the steps of: immersing a steel sheet in a hot-dip coating bath to form an Al&mdash;Zn base coating layer containing 20 to 95 mass % Al on the steel sheet, forming a passivated layer on the coating layer; and applying thermal history to the coating layer. The thermal history is applied immediately after the steel sheet left the hot-dip coating bath or in a temperature range of from T(&deg; C.) between 130&deg; C. and 300&deg; C. to 100&deg; C.

Coated steel sheet and method for manufacturing the same

A zinciferous coated steel sheet comprises a steel sheet, a zinciferous coating layer formed on the steel sheet, a Fe--Ni--Zn--O film formed on the zinciferous coating layer, and an oxide layer formed on a surface portion of the Fe--Ni--Zn--O film. The method comprises providing an electrolyte of an acidic sulfate aqueous solution, carrying out an electrolysis treatment in the electrolyte under a current density ranging from 1 to 150 A/dm.sup.2, and carrying out an oxidation treatment to a surface of the zinciferous coated steel sheet.

Zinciferous coated steel sheet and method for producing the same

Method for producing a galvannealed steel sheet wherein a slab consisting essentially of C in an amount of 0.004 wt. % or less, N in an amount of 0.004 wt. % or less, Ti in an amount of 0.01 to 0.15 wt %, Si in an amount of 0.05 wt. % or less, Mn in an amount up to 2.5 wt. %, P in an amount up to 0.1 wt. %, S in an amount of 0.015 wt. % or less, sol. Al in an amount of 0.02 to 0.1 wt. % and the balance being Fe, is soaked for at least 30 minutes at a specified temperature (range). The soaked slab is hot rolled to produce a hot-rolled steel sheet which is coiled at a temperature of 500 to 700.degree. C. The coiled hot-rolled steel sheet is cold rolled at a reduction ratio of 60% or more to produce a cold-rolled steel sheet which is annealed at a temperature of from recrystallization temperature to Ac3 transformation temperature. Galvanizing the annealed cold-rolled steel sheet and then galvannealing at a temperature of 450 to 600.degree. C.

Method for producing galvanized steel sheet

Zinciferous plated steel sheet and method for manufacturing same

Alloying-treated iron-zinc alloy dip-plated steel sheet excellent in

It is an object to provide a process for manufacturing galvannealed steel sheets exhibiting excellent anti-powdering property when press formed, and uniform frictional properties in a coil. A steel strip is galvanized in a bath having a low aluminum content after entering it at a high temperature as defined in relation to the aluminum content of the both, so that the formation of a .zeta. phase may be promoted. Then, the strip is heated for alloying in a high-frequency induction heating furnace so as to have a temperature not exceeding 495.degree. C. when leaving the furnace to yield a plated steel strip having a coating containing a uniformly distributed .zeta. phase. After such heat treatment and cooling, the strip can be plated with an iron or iron-alloy top coating having an iron content of at least 50% and a coating weight of at least 1 g/m.sup.2 to achieve an improved press formability.

Process for manufacturing galvannealed steel sheet having excellent

Process for manufacturing galvannealed steel sheets having high

A method for manufacturing an iron-zinc alloy plated steel sheet having two plating layers and excellent in electropaintability and press-formability, which comprises the steps of: applying an alloying treatment under a temperature of from 420.degree. to 520.degree. C. to a zinc dip-plated steel sheet to form on the surface of the steel sheet an alloying-treated iron-zinc alloy dip-plating layer having on the surface thereof fine irregularities comprising numerous fine concavities and numerous fine convexities; then applying a temper rolling treatment at a reduction rate of from 0.3 to 1.5 to the alloying-treated steel sheet, to level the numerous fine convexities on the surface of the alloying-treated iron-zinc alloy dip-plating layer, so as to form on the surface of the steel sheet the alloying-treated iron-zinc alloy dip-plating layer as a lower layer having the numerous fine concavities on the surface thereof; and then applying an iron-zinc alloy electroplating treatment to the temper rolling treated steel sheet to form, on the alloying-treated iron-zinc alloy dip-plating layer as the lower layer, an iron-zinc alloy electroplating layer as an upper layer. The above-mentioned iron-zinc alloy electroplating treatment is carried out with an electric current density of from 50 to 150 A/dm.sup. 2 in an acidic electroplating bath containing iron ions and zinc ions, and having a pH value of from 1.0 to 4.0 and a temperature of from 40.degree. to 70.degree. C.

Method for manufacturing iron-zinc alloy plated steel sheet having two

A digital protective relay apparatus for protecting a power system comprises an accident determination section for determining an accident in the power system, which receives a voltage and a current of the power system from the power system to determine an accident in the power system using the voltage and the current, outputs a determination signal indicating the presence/absence of an accident in accordance with a result of the accident determination, and outputs a first trip signal upon detecting an accident in the power system in accordance with the accident determination, a protection sequence section for receiving the determination signal from the accident determination section to determine necessity of a trip output by performing predetermined sequence processing using the determination signal, and outputting a second trip signal upon obtaining a determination result indicating that a trip command is to be output, and a trip generator for generating, when both of the first and second trip signals are output, a third trip signal for opening a circuit breaker provided to protect the power system.

Digital protective relay apparatus

A method for manufacturing an iron-zinc alloy plated steel sheet having two plating layers and excellent in electropaintability and press-formability, which comprises the steps of: passing a steel sheet through a zinc dip-plating bath to form a zinc dip-plating layer on at least one surface of the steel sheet; then, heating the steel sheet, on which the zinc dip-plating layer has been formed, to alloy the zinc dip-plating layer and the surface portion of the steel sheet, so as to form, on the surface thereof, an alloying-treated iron-zinc alloy dip-plating layer as a lower layer having a plating weight of from 30 to 120 g/m.sup.2 per surface of the steel sheet; then, passing the steel sheet through an acidic plating bath for 1 to 5 seconds without electrifying same to dissolve the surface portion of the alloying-treated iron-zinc alloy dip-plating layer, so as to form numerous fine jogs on the surface thereof; and then, electroplating the steel sheet in an iron alloy acidic electroplating bath to form an iron alloy electroplating layer as an upper layer, having a plating weight of 1 to 10 g/m.sup.2 per surface of the steel sheet, on the alloying-treated iron-zinc alloy dip-plating layer as the lower layer having the numerous fine jogs.

Process for making non-oriented high silicon steel sheet

Method of producing silicon iron sheet having excellent soft magnetic

Method of producting thin sheet of high Si-Fe alloy

Growing community of inventors

Tokyo, Japan

Junichi Inagaki