Nippon Steel Corporation

Yoshiaki Suematsu

Kentaro Watanabe

Keisuke Mori

Toshiaki Mizoguchi

Yoshihiro Serizawa

Satoru Hayashi

Hitoshi Furuya

Takayuki Murai

Akira Mikasa

Hiroshi Niitani

Masanobu Hayakawa

Tomoya Nakao

Masakazu Asaba

Provided is a cooling device, where a hot-finish-rolling mill includes a plurality of nozzles which spray cooling water toward one of or both of upper and lower surfaces of a hot-rolled steel sheet just after rolled by rolling stands, the nozzles are provided on the inside of the upper and lower guides or adjoining to the guides on a downstream side, and a nozzle spray distance changes depending on a position of the nozzle in a rolling direction, wherein a spray angle of the nozzle at a position whose nozzle spray distance is the largest is smaller than a spray angle of the nozzle at a position whose nozzle spray distance is the smallest, and the spray angle of the nozzle becomes the same or smaller as the nozzle spray distance becomes large.

Cooling device and cooling method of hot-rolled steel sheet

A nickel-containing steel plate according to an aspect of the present invention has a chemical composition within a predetermined range, in which an average coarse grain size of prior austenite which is defined as a simple average value of maximum values of equivalent circle diameters of prior austenite grains in each of ten visual fields having an area of 200 &#x3bc;m, measured at a &#xbc;t position of the steel plate in a section formed by a rolling direction of the steel plate and a thickness direction of the steel plate is 20 &#x3bc;m or less, and a tensile strength is 690 MPa to 900 MPa.

Nickel-containing steel plate

The present invention provides a continuous casting method of steel preventing alumina and other nonmetallic inclusions becoming causes of slivers and argon bubbles becoming causes of blowholes from being entrained and thereby enabling the production of a cast slab superior in surface and internal quality, that is, one giving an inside boreof an immersion nozzlea horizontal sectional shape of an elliptical shape or oblong shape with a length ratio D/Dof that long axis Dand short axis Dof 1.2 to 3.8, making a direction of that long axis substantially parallel to a long side direction of the casting moldand making the sliding direction of the sliding nozzlea direction perpendicular to said long axis to supply the molten steel in the casting mold. Note that a ratio S/Sof a sectional area Sat a smallest sectional area partof the inside boreand a sectional area Sof a nozzle holeof the sliding nozzleis made 0.5 to 0.95

Continuous casting method of steel

Growing community of inventors

Tokyo, Japan

Yoshiaki Suematsu