Nippon Steel Corporation

Yasushi Takeshima

Akira Inagaki

Kazuo Fujita

Teruyuki Wakatsuki

Yasushi Horiuchi

Takeshi Hioki

Hiroyuki Hasegawa

Toshihiro Ishibashi

Hiroaki Hadano

Masao Kurokawa

Yoshimi Toriyama

Kohichi Yamamoto

Naoki Oda

A method for producing a steel section by a rolling process including a rough rolling step, an intermediate rolling step and a finishing rolling step. The intermediate rolling step comprises water-cooling the flange portion of the rough-rolled steel section between rolling passes in the intermediate rolling step to cool the surface layer of the flange to a temperature not higher than 750.degree. C., and rolling the flange portion during recuperation of the surface layer of the flange at least one time between the rolling passes with a total draft not less than 20% and at an average rolling temperature not higher than 950.degree. C. and, after the finishing rolling step the outer surface of the flange is cooled at a cooling rate ranging from 0.5.degree. to 10.degree. C./sec depending on the thickness of the flange. Also the carbon equivalent of the steel is controlled. The advantage is that steel sections of various contours and dimensions can be produced from minimized varieties of steel compositions.

Method for producing low carbon equivalent rolled steel shapes by

An apparatus for cooling thin-webbed H-beam steel includes means for forcibly spray cooling the flanges of the H-beam in intermediate and final hot rolling zones. The cooling is based upon tracking information with respect to predetermined positions along the length of the H-beam. A plurality of flow quantity control blocks are disposed in parallel with each having a three way valve having a water supply side port, a nozzle side port, and a water drain port. A plurality of on-off valves connect the nozzle side port to nozzles in a nozzle group to select nozzles based upon the flange width of the H-beam. A variable throttle mechanism maintains pressure loss at the water drain side equal to pressure loss at the nozzle side. Switching of the three way valve of one flow quantity control block can be carried out without affecting other flow quantity control blocks.

Apparatus for cooling thin-webbed H-beam steel

A thin-webbed H-beam steel having a web thinner that flanges is produced by forcibly water cooling the outer surface of the flanges during an intermediate hot rolling prior to a final hot rolling by cooling to less than 700.degree. C., interrupting the cooling to return the temperature to greater than 700.degree. C., and repeating the cooling and interrupting in order to refine the microstructure of the surface of the flanges to a predetermined depth from the surface; final-hot rolling the intermediate-hot rolled H-beam steel; and forcibly water cooling the flanges of the final-hot rolled H-beam steel in a manner such that the web does not wave during this forcible water cooling, and such that upon completion of the forcible water cooling, thermal stress, generated in the web during air cooling to room temperature, does not exceed the buckling strength of the web.

Process for producing thin-webbed H-beam steel

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Sakai, Japan

Yasushi Takeshima