Jfe Steel Corporation

Satoshi Ueoka

Takashi Kuroki

Naoki Nakata

Nobuo Nishiura

Akio Fujibayashi

Shougo Tomita

Takashi Matsumoto

Takeshi Fujita

Nobuyuki Nakamura

Hideyuki Kimura

Yukio Kimura

Hirokazu Sugihara

Yuta Tamura

Hiroto Goto

Takeshi Yokota

Hiroyuki Fukuda

Kenji Adachi

Nobuyuki Ishikawa

Kazuhiro Seto

Kazukuni Hase

Tomoyuki Yokota

Junji Shimamura

Sonomi Shirasaki

Naoya Aoki

Yukako Katayama

Masato Sasaki

Norichika Aramaki

Takeshi Chiba

Akitoshi Matsui

Shusaku Ota

Yoshitsugu Iijima

Tsutomu Sugiyama

Yoichi Tominaga

Kenichi Mitsuzuka

Masaru Miyake

Masayuki Horie

Shunji Iizuka

Kazuya Ibuki

Takaomi Kato

Shuhei Irie

Sho Kokufu

Kenichi Osuka

Takahiro Hirano

Ori Kumano

Naoki Harada

A method for continuously casting steel capable of reducing center segregation that occurs in a slab. In a section in a continuous casting machine in a slab withdrawal direction, a section from a start point at which the average value of solid phase ratios along a thickness direction at a widthwise center of a slab is within a range of 0.4 or more and 0.8 or less to an end point at which the average value of solid phase ratios along the thickness direction at the widthwise center of the slab is greater than the average value of solid phase ratios at the start point and is 1.0 or less is set as a first section. The slab is cooled by water in the first section at a water flow rate per surface area of the slab within a range of 50 L/(m&#xd7;min) or more and 2,000 L/(m&#xd7;min) or less.

Method for continuously casting steel

A hot-rolled steel sheet not exceeding a coil opener allowable load during unwinding includes a steel sheet cut in unsteady portions at its longitudinal head and tail ends in a cutting step after a rough rolling step, having a width of 1,200 mm to 2,300 mm, a thickness of 13 mm to 25.4 mm, and at least an API standard X65-grade strength, and used in a state of being unwound after having been wound around a coil. A longitudinal end corresponding to the unwinding start includes a portion at its widthwise center recessed inwards in the longitudinal direction with respect to its two widthwise ends, the two widthwise ends projection sizes with respect to the recessed portion at the widthwise center are 20 to 295 mm, and the sum of the widths of projecting portions at the two widthwise ends is set to &#xbc; to &#xbd; of the sheet width.

Hot-rolled steel sheet and method for manufacturing same

A production equipment line for a hot-rolled steel strip comprises a rough rolling mill comprising rough rolling mills for hot rolling a material, which is heated to a predetermined temperature to a finish rolling start sheet thickness and a finish rolling mill comprising finish rolling mills for controlled-rolling the material to a final sheet thickness. At least one of the rough rolling mills is a reversible rolling mill. The production equipment line is provided on an upstream side of the reversible rolling mill with one of a slow cooling apparatus for slowly cooling at a water volume density of less than 1000 L/min&#xb7;mand a rapid cooling apparatus for rapidly cooling after the slow-cooling at a water volume density of not less than 1000 L/min&#xb7;mand the other of the slow cooling apparatus and rapid cooling apparatus on a downstream side of the reversible rolling mill.

Production equipment line for hot-rolled steel strip and production method for hot-rolled steel strip

A production equipment line for a hot-rolled steel strip comprises a rough rolling mill group comprised of plural rough rolling mills for hot rolling a material which is heated up to a predetermined temperature to a finish rolling start sheet thickness and a finish rolling mill group comprised of plural finish rolling mills for controlled-rolling the material to a final sheet thickness, wherein at least one of the plural rough rolling mills is a reversible rolling mill. The production equipment line for a hot-rolled steel strip is provided with a slow cooling apparatus for slowly cooling the material at a water volume density of less than 1000 L/min&#xb7;mand a rapid cooling apparatus which is arranged next to the slow cooling apparatus and rapidly cools the material after the slow-cooling at a water volume density of not less than 1000 L/min&#xb7;m.

A method for manufacturing a hot-rolled steel sheet having a large thickness and a large width, a larger sheet width and a lower temperature can stably be cut at a cutting load equal to that of a conventional steel sheet having a usual sheet thickness, a usual sheet width and a usual temperature. In a rough rolling step, the steel sheet is formed so that the shortest length L (mm) from a concave portion bottom to a convex portion top of the fishtail shape satisfies Equation (1) mentioned below, and an intermediate portion between the concave portion bottom and the convex portion top, defined as a desired cutting location, is cut:(2+30)&#x2264;&#x2264;300&#x2003;&#x2003;(1),in which X is a maximum deviation (mm) of the cutting location of a crop cutting machine and 0&#x2264;X&#x2264;90.

Method for manufacturing hot-rolled steel sheet, steel sheet cutting location setting device, steel sheet cutting location setting method, and steel sheet manufacturing method

Provided are a cooling method and a cooling apparatus that, in the cooling of a hot-rolled steel strip, regulates the amount of cooling water in a two-stage manner for each set of headers in the width direction and changes the rate at which the steel strip is cooled, in a multistage manner by a simple method, and that is effective particularly in cooling the lower surface of the steel strip, where space is narrow. The spray nozzlesare arranged in a row in the width direction of the steel strip at a predetermined pitch. Two systems of cooling headersare arranged for one set so that spray nozzlesadjacent in the width direction can be supplied with cooling water from different pipe systems, and a spray valveis attached to each cooling headerso that spraying/stop of spraying of cooling water can be individually performed.

Method and apparatus for cooling hot-rolled steel strip

A hot rolled steel sheet cooling apparatus includes a gradual cooling headerincluding a rod-like cooling water nozzlefor gradual cooling and a rapid cooling headerincluding a rod-like cooling water nozzlefor rapid cooling such that the headers constitute a cooling unit. The cooling unitincludes an elevating unitcapable of moving upward and downward in unison with the cooling unit. In cooling the upper surface of a hot rolled steel sheet (hot rolled steel strip or steel plate), uniform and stable cooling is achieved while both of high cooling rate and low cooling rate are ensured.

Hot rolled steel sheet cooling apparatus

A method for manufacturing a high strength hot rolled steel sheet includes heating a slab to a temperature in the range of 1150 to 1300&#xb0; C.; hot rolling the slab with a finishing rolling temperature being in the range of 800 to 1000&#xb0; C.; cooling the steel sheet at a mean cooling rate of 30&#xb0; C./s or higher to a cooling termination temperature in the range of 525 to 625&#xb0; C.; suspending cooling for a time period in the range of 3 to 10 seconds; cooling the steel sheet in such a manner that cooling of the steel sheet is nucleate boiling; and coiling the steel sheet at a temperature in the range of 400 to 550&#xb0; C.

Method for manufacturing high strength hot rolled steel sheet

A method for cooling a hot strip conveyed on a run-out table after finishing, including ejecting rod-like flows of cooling water from nozzles to the upper surface of the steel strip such that the flows are inclined toward a traveling direction of the steel strip, and draining the cooling water using draining means disposed downstream of the nozzles.

Method for cooling hot strip

A hot-strip cooling device for cooling a hot strip that has been subjected to finish rolling while being conveyed over a run-out table. The device includes a plurality of cooling nozzles that are disposed above a steel strip and eject rod-like flows of coolant at an ejection angle tilted toward the upstream side in a steel-strip traveling direction; and purging means that is disposed on the upstream side with respect to the cooling nozzles and purges the coolant that has been ejected from the cooling nozzles and resides on the steel strip.

Hot-strip cooling device

A cooling device and a cooling method for a hot strip allow uniform and stable cooling of the strip at a high cooling rate when supplying the coolant to the upper surface of the hot strip. The cooling device includes an upper header unitfor supplying a rod-like flow to the upper surface of the strip. The upper header unitis formed of the first upper header group including plural first upper headersarranged in a conveying direction and a second upper header group including plural second upper headersarranged in the conveying direction. The cooling device is provided with an ON-OFF mechanismto allow each of the upper headersandof the first and the second upper header groups to independently execute the ON-OFF control (start/end injection control) of an injection (feeding) of the rod-like flow.

Device and method for cooling hot strip

A cooling device and cooling method for a hot-rolled strip in which the strip can be uniformly cooled from a leading edge to a trailing edge with coolant by properly realizing a great cooling ability and a stable cooling zone.

Cooling device and cooling method for hot strip

A device and a method for cooling a hot strip capable of uniformly cooling the hot-rolled steel strip from the leading end to the trailing end thereof during cooling of the steel strip using cooling water are provided. A cooling deviceincludes a plurality of tubular nozzlesinclined so as to eject rod-like flows of cooling water to a steel stripat an ejecting angle &#x3b8; in a traveling direction of the steel stripand a pinch rollerdisposed downstream of the tubular nozzles, the steel stripto be nipped between the pinch rollerand a table roller

A hot-strip cooling device and a cooling method are provided wherein uniform cooling of a hot-rolled steel strip using coolant is possible from the leading end to the trailing end of the steel strip. A cooling device () includes a plurality of round nozzles () disposed obliquely in such a manner as to eject rod-like flows of coolant at an ejection angle &#x3b8; toward the upstream side in a direction in which a steel strip () travels, and a pinch roll () disposed on the upstream side with respect to the round nozzles () and configured to pinch the steel strip () in combination with a roller table ().

Hot-strip cooling device and cooling method

The method for cooling a hot strip which is obtained after a hot rolling process to the temperature range of 500&#xb0; or less. Cooling water is brought into contact with the hot strip. The method includes a first cooling step and a subsequent second cooling step. Cooling is stopped at a strip temperature that is higher than a transition boiling initiation temperature in the first cooling step, and the cooling is conducted using the cooling water having a water flow rate that causes nucleate boiling in the subsequent second cooling step. Entering the temperature range of transition boiling can be completely prevented to avoid thermal instability in cooling resulting from the transition boiling, and the temperature variation of the strip after cooling is controlled to be small while the cooling end temperature can be precisely controlled.

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Fukuyama, Japan

Satoshi Ueoka