Nippon Steel Corporation

Atsuhiro Wakako

Osamu Akisue

Kichi Nakazawa

Kenichi Matsui

Yoshio Inoi

Takeshi Ono

Kunio Kawamura

Kouji Hyoudou

Seiryo Hatae

Takeyuki Fukuda

Hiroaki Toki

A hot rolling method, wherein portions of a hot-rolled steel material having suffered a temperature fall below Ar.sub.3 transformation temperature thereof during hot rolling are subjected to an intermediate heating to have a temperature not less than Ac.sub.3 transformation temperature before the steel material is finally finish-hot-rolled, whereby a resultant hot-rolled product can have a superior uniform structure without duplex structure, and apparatus for effecting the method.

Hot rolling method and apparatus for hot rolling

In a method for producing a cold-rolled steel sheet by continuously casting, hot-rolling, cold-rolling, and continuously annealing Al-killed steel, it is known to coil a hot-rolled strip at a coiling temperature of 630.degree. C. to 710.degree. C. so as to attain satisfactory precipitation of AlN in the hot-rolling step. When the direct-rolling of a continuously cast strand (DR method) is employed to produce a cold-rolled strip, it is impossible to attain satisfactory precipitation of AlN even by carrying out the known coiling method. The present invention is characterized in that an extremely high coiling temperature of at least 780.degree. C. is used to essentially prevent aging due to the precipitation of AlN, and, further, the carbon content of a continuously cast slab is 0.005% at the highest so as to essentially prevent the occurrence of orange peel. Heat conservation due to use of the DR method and excellent properties of the cold-rolled steel strip are simultaneously attained.

Method for producing a cold-rolled steel sheet having excellent

There is described a method for controlling the profile of a workpiece on a rolling mill, wherein the workpiece is imparted with a predetermined profile in the roughing stage which is suitable for further control in the following finishing stage. In the finishing stage, the desired profile of the workpiece is attained by controlling the temperature of the workpiece at inlet position of the second finishing stage and/or controlling the thickness of the workpiece at outlet position of the first roughing stage. To determine the temperature and/or the thickness of the workpiece at inlet position of the second finishing stage a crown model formula is utilized. The crown model formula includes some constants, and variables which represent the mean temperature of the workpiece in the second finishing stage, and the thickness of the workpiece at the outlet of the first roughing stage.

Method for controlling the profile of workpieces on rolling mills

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Tokyo, Japan

Atsuhiro Wakako