Nippon Steel Corporation

Mitsubishi Electric Corporation

Kazuo Watanabe

Suguru Yoshida

Kohichi Yamamoto

Hideki Tokita

Koe Nakajima

Kenji Yamada

Taneharu Nishino

Minoru Kawaharada

Yoshito Tsuyama

Kanichi Kishikawa

Seiichi Nagasoe

Shigeru Uchida

Kousaku Ozawa

Toshio Harada

Hiromi Seki

Koei Nakashima

Hironori Kawasaki

Keiichi Miura

Shiro Araki

Shinichi Nakamata

After a predeoxidation treatment of a molten steel comprising as basic ingredients, in terms of % by weight, 0.04 to 0.20% of C, 0.05 to 0.50% of Si, 0.4 to 2.0% of Mn, 0.3 to 0.7% of Mo, 0.003 to 0.015% of N, 0.04 to 0.20% of V and less than 0.005% of Al to regulate [O %] to 0.003 to 0.015% by weight, titanium is added thereto so as to satisfy a requirement represented by the formula: -0.006.ltoreq.[Ti %]-2[O %].ltoreq.0.008 to crystallize a titanium-based oxide in an amount of 20 particles/mm.sup.2 or more, and MnS, TiN and V(C, N) are deposited on the titanium-based oxide to disperse the titanium-based oxide as a composite precipitate in the steel to provide a cast slab, and a high-strength high-toughness shape steel having an excellent fire resistance is provided by a combination of water cooling between rolling passes at the time of rolling with accelerated cooling after the completion of the rolling.

Shape steel material having high strength, high toughness and excellent

Process for producing rolled shape steel material having high strength,

A cast strip for an H-shape steel having excellent fire resistance and toughness for use as a structural member for constructions and a shape steel having a flange, such as an I-shape steel, produced by accelerated cooling and controlled rolling of the cast slab, are produced in an in-line manner. After the regulation of the oxygen concentration of a molten steel by a predeoxidation treatment in a steel making process to form a steel having predetermined ingredients, the steel is subjected to final deoxidation with a minor amount of Al to provide a cast slab containing, in a dispersed state, compound oxide precipitate having a capability of forming intragranular ferrite. The stead is then subjected to a treatment comprising a combination of water cooling between rolling passes with accelerated cooling after hot rolling to attain refinement of the structure and a low alloy steel, thereby improving the strength at room temperature and at high temperature and the toughness.

Refractory shape steel material containing oxide and process for

First, a rectangular metal plate having thinner and thicker portions corresponding to a lighter-wall portion and heavier-wall portion of a pipe to be manufactured is prepared. Before bending the plate until both edges thereof meet to form a tubular piece, the plate width is adjusted by cutting off part of the thinner portion so that the desired peripheral lengths are attained in both lighter- and heavier-wall portions of the pipe. The width-adjusted plate is then bent until both edges are butted together to form a tubular piece. By butt-welding the adjoining edges, a metal pipe with longitudinally differentiated wall thickness is obtained.

Method of manufacturing metal pipe with longitudinally differentiated

In a press-rolling process for producing a metal tubular product, which comprises a pipe-forming procedure in which a square metal billet is fed into a rolling mill which consists of a pair of pressing rolls which have semi-circular grooves forming circular shape and which is provided with a plug held in the center line of the circular shape, according to the present invention, the press-rolling process is characterized in that a cavity is formed in the center portion of the forward surface of the billet before the pipe-forming procedure, the diameter of the cavity corresponding to 70% or more but less than 100% of the diameter of the plug and the volume of the cavity being equal to or more than the volume of a portion of the plug located in the inserting side of the billet from the axial center of the rolling mill.

Press-rolling process for producing a metal tubular product

In making metal sections, starting material having a quadrangular cross-section is hot-forged into a blank resembling the desired product in cross-section, and the length of the piece is divided into sections of a given length. Then, the blank is hot-rolled into the product having the desired cross-section.

Method and apparatus for manufacturing metal sections

A method for rolling a steel section having flanges or flange-like portions from a steel bloom of rectangular cross section in a rolling mill having a train of roughing rolling stands for roughing, a universal rolling stand with a pair of opposing horizontal rolls and a pair of opposing vertical rolls, and a train of finishing rolling stands for finishing. The method includes rolling the bloom in the train of roughing rolling stands for roughing to a rough shape having a width greater than the shortest distance between the outer circumferences of the opposed vertical rolls in the universal rolling stand and having a reduced almost flat cross section including a portion to be shaped into flanges or flange-like portions in the final product, rolling the rough shape of flat cross section thus obtained in the universal rolling stand for causing the pair of vertical rolls and the pair of horizontal rolls to cooperatively give bending deformation mainly to the portions to be shaped into the flanges or flange-like portions, and finish rolling the rough shape produced from the bending deformation in the finishing rolling stands for finishing.

Method for rolling steel sections having flanges or flange-like portions

A process for hot rolling an H-shaped metallic material from a workpiece of rectangular cross section which comprises reducing the workpiece in the width direction thereof while wedgewise knifing the opposing sides of the workpiece by means of a first pair of grooves formed in rolls of a vertical roll stand; reducing the workpiece in the width direction thereof while spreading the knifed sides by means of a second pair of grooves which may be formed in rolls of another vertical roll stand or in the rolls having said first pair of grooves; and subsequently rolling the workpiece to a required size by universal rolling mills. This process thus enables a starting material of a rectangular cross section to be employed instead of that of H-shaped cross section.

H-shape metallic material rolling process

There is described a method for compensating tail end of rolling materials for rolling shaped steel sections in an optimum manner. According to this method, in a continuous tension free rolling operation of a shaped steel section comprising a flat section and a flange section through a plural number of roll stands, the operating speed of a first roll stand is reduced by a predetermined amount as compared with a second or succeeding roll stand when the crop at the tail end of the rolling material enters the first rolling unit, thereby to prevent overfeeding.

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Sakai, Japan

Kazuo Watanabe