Nippon Steel Sumitomo Metal Corporation

Nippon Steel Corporation

Takeo Itoh

Tooru Akashi

Shingo Kuriyama

Koji Noguchi

Shigeru Ogawa

Koki Tanaka

Kazuhiko Honda

Daisuke Kasai

Yoshiaki Hirota

Yoshihiro Suemune

Yoichi Ikematsu

Tetsuo Nishiyama

Hitoshi Nikaido

Masato Taira

Fuminori Tasaki

An induction heating device for a metal strip, including: an induction coil provided on one side or on both sides of a front face side or a reverse face side of a metal strip, and that induces an induction current in the strip when a primary current is passed through the coil, the induction current configuring a closed loop as viewed from a direction perpendicular to a metal strip face; plural magnetic cores disposed at a specific position, this being a position at a back face side of the coil and separated from the strip by a specific distance, to concentrate magnetic flux generated by the coil in the strip; and a moving mechanism coupled to the magnetic cores, and that moves the cores to increase or decrease a disposed number of the cores at the specific position disposed side-by-side along a metal strip width direction.

Induction heating device for metal strip

The apparatus for cooling a hot-rolled steel sheet of the invention includes a thermometer that measures the temperature of the hot-rolled steel sheet; a shape meter that measures a shape of the hot-rolled steel sheet; a top side cooling device that cools a top surface of the hot-rolled steel sheet in a cooling section; a bottom side cooling device that cools a bottom surface of the hot-rolled steel sheet in the cooling section; and a control device that controls at least one of an amount of heat dissipated from the top surface by cooling and an amount of heat dissipated from the bottom surface by cooling of the hot-rolled steel sheet in the cooling section by controlling the top side cooling device and the bottom side cooling device based on temperature measurement results and shape measurement results.

Apparatus for cooling hot-rolled steel sheet

A method for manufacturing a steel sheet of the invention includes a hot-rolling process in which a steel material is hot-rolled using a finishing mill so as to obtain a hot-rolled steel sheet; and a cooling process in which the hot-rolled steel sheet is cooled. The hot-rolling process includes a target steepness-setting process in which a target steepness of the edge wave shape is set based on first correlation data indicating a correlation between a steepness of the edge wave shape of the hot-rolled steel sheet and a temperature standard deviation Y; and a shape-controlling process in which operation parameters of the finishing mill are controlled so as to match the steepness of the edge wave shape with the target steepness.

Method for manufacturing steel sheet

The method for cooling a hot-rolled steel sheet of the invention includes a target ratio-setting process in which a top and bottom heat transfer coefficient ratio X1, at which a temperature standard deviation Y becomes a minimum value Ymin, is set as a target ratio Xt based on correlation data between a top and bottom heat transfer coefficient ratio X of the hot-rolled steel sheet and the temperature standard deviation Y of the hot-rolled steel sheet; and a cooling control process in which at least one of an amount of heat dissipated from a top surface by cooling and an amount of heat dissipated from a bottom surface by cooling of the hot-rolled steel sheet in the cooling section is controlled so that the top and bottom heat transfer coefficient ratio X of the hot-rolled steel sheet in the cooling section matches the target ratio Xt.

Method for cooling hot-rolled steel sheet

Hot dip galvanized steel sheet excellent in shapeability and plateability comprised of high strength steel sheet according to the present invention can be provided containing, by mass % about, C: 0.05 to 0.25%, Si: 0.3 to 2.5%, Mn: 1.5 to 2.8%, P: 0.03% or less, S: 0.02% or less, Al: 0.005 to 0.5%, N: 0.0060% or less and the balance of Fe and unavoidable impurities. The exemplary steel sheet can have thereon a galvanized layer containing, e.g., about Al: 0.05 to 10 mass % and Fe: 0.05 to 3 mass % and the balance of Zn and unavoidable impurities. Such exemplary hot dip galvanized steel sheet can have oxides containing Si in an average content of about 0.6 to 10 mass % at the crystal grain boundaries and in the crystal grains at the sheet steel side 5 &#x3bc;m or less from the interface between the high strength steel sheet and the plating layer and by the presence of Fe&#x2014;Zn alloy with an average grain size of about 0.5 to 3 &#x3bc;m at the plating side.

High strength hot dip galvanized steel sheet and high strength galvannealed steel sheet excellent in shapeability and plateability

Growing community of inventors

Tokyo, Japan

Takeo Itoh