Nippon Steel Corporation

Hiroshi Takechi

Kazuo Koyama

Hiroaki Masui

Hisashi Gondo

Mitsunobu Abe

Kazuo Namba

Munetsugu Matsuo

Tsuyoshi Kawano

Kunihiko Komiya

Takashi Furukawa

Hiroshi Katoh

Matsuo Usuda

Koichi Sakurai

Kazuo Kovama

Chikara Fujii

Kazuhide Usami

Mitsuo Yoshizawa

Hirohisa Ichihara

Hiroshi Nougata

Koji Ozaki

Ryoseki Katsutani

Yoshio Saito

An impeder for use in an apparatus for resistance tube welding by which a strip-shaped skelp continuously formed into a tubular or spirally tubular shape having spaced opposed edge portions defining a gap therebetween has the edge portions heated and pressed together for being welded. The impeder has a generally tubular casing and a core within the casing consisting of a plurality of laminated bodies each consisting of a plurality of substantially flat planar foils of metallic magnetic material, the core, when viewed in cross-section traverse to the central longitudinal axis of the casing, having the transverse cross-sections of the laminated bodies on parts of at least one circle concentric with the longitudinal axis of the casing and having the planes of the foils extending substantially radially outwardly from the longitudinal axis.

Impeder for electric resistance tube welding

A high strength cold rolled strip having excellent deep drawability and resistance to deterioration by natural aging and to planar cracking and useful for motor vehicles, is produced by hot rolling a steel slab comprising

Process for producing cold rolled steel strip having excellent

A method of producing a dual phase structure cold rolled steel sheet having tensile strength 35 to 50 kg/mm.sup.2, yield ratio less than 60% and high elongation which comprises hot rolling and cold rolling by conventional process a steel containing 0.01 to 0.05% C, less than 0.2% Si, 1.7 to 2.5% Mn, 0.01 to 0.10 Al with the balance being Fe and unavoidable impurities, holding the produced steel sheet for 20 seconds to 20 minutes at a temperature 720.degree. to 850.degree. C., and cooling the steel sheet at a cooling speed between 3.degree. and 50.degree. C. per second and also above a value (.degree.C. per second) shown by following formulae:

Method of producing dual phase structure cold rolled steel sheet

An apparatus for continuously producing a high strength dual-phase steel strip or sheet having a chemical composition which produces a dual-phase structure composed of ferrite grains and a low temperature transformed phase when rapidly cooled from the (.alpha.+.gamma.) temperature range or from the .gamma. temperature range. The apparatus has a continuous heat treatment furnace in which the strip moves vertically and which is composed of a heating zone, a soaking zone and a cooling zone, and conventional equipment associated therewith. The cooling zone has an upper hearth roll group, a lower hearth roll group and cooling equipment for cooling the strip at a rate in the range between 1.degree. and 300.degree. C./sec. for retaining the austenite in the steel of the strip. The hearth rolls of each hearth roll group are arranged to guide the strip coming from the soaking zone up and down through the cooling zone from the inlet end to the outlet end, alternately passing around the upper hearth rolls and the lower hearth rolls. The hearth roll at the position where the strip is subjected to straining and begins to work harden as a result of the bending, and the hearth rolls subsequent to such position, have diameters such that the strain induced phase transformation of the retained austenite and consequently the work hardening of the strip when it is turned around the hearth rolls is avoided.

Apparatus for continuously producing a high strength dual-phase steel

A process of producing a cold rolled killed steel sheet with good cold formabilities particularly by continuous-annealing, and more particularly to a process of producing cold rolled steel sheet and strip having particularly enhanced deep drawability by controlling the chemical composition and compositional proportions of the killed steel as well as the high temperature coiling after a hot rolling operation.

Process for producing cold rolled steel sheet and strip having improved

A method for levelling a metal strip or sheet in which the metal strip or sheet is subjected to repeated bending by means of a roll arrangement of two or more rolls having a diameter of at least 600 times the thickness of the metal while cooling the metal strip or sheet from at least about 210.degree. C to about 50.degree. C at a cooling rate not lower than a critical cooling rate C as defined by the following formula but not higher than 200.degree. C/sec., ##EQU1##

Method for levelling a metal strip or sheet

A vibration damping steel containing C .ltoreq. 0.10% and Mn .ltoreq. 0.40% as the essential constituents and having a lower yield point or 0.2% proof stress of 7-28kg/mm.sup.2 with the degree of refinement of the steel being not less than 0.18 while still maintaining the specific gravity at 7.859g/cm.sup.3 or less, and a process for producing the same. This steel material is particularly suited for use in items which to produce and transmit vibration and noise.

Vibration damping steel material and process for producing the same

A steel sheet, especially a thin one, can be manufactured from a hot rolled coil through heat treating steps by means of positively applying stress to the material. The product has excellent shape and mechanical properties such as drawability and toughness.

Method and an apparatus for the manufacture of a steel sheet

A hot-rolled steel sheet of high cold formability characterized in that it contains of 0.03-0.30 % C and 0.15-2.0 % Mn as the main ingredients and also by the average length of sulfide inclusions of stringer form and/or silicate inclusions of like form being less than 100 .mu..

Hot-rolled steel sheet of high cold formability and method of producing

A method for producing a cold rolled steel sheet having high strength and stretchability which comprises hot rolling a steel containing 0.03 to 0.30% C, less than 0.7% Si, 0.6 to 2.5% Mn, 0.01 to 0.20% sol.Al, not more than 0.015% O with the balance being Fe and unavoidable impurities, cold rolling with a reduction not less than 30%, heating with an average heating rate not less than 3.degree.C/sec. annealing in a temperature range from 650.degree.C to A.sub.3 transformation point for 1 to 15 minutes, and cooling with an average cooling rate of 0.5.degree. to 30.degree.C/sec. down to 500.degree.C.

Method for producing a high-strength cold rolled steel sheet having

A method for producing a high-strength cold rolled steel sheet or strip is disclosed. Steel comprising

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Kisarazu, Japan

Hiroshi Takechi