Kabushiki Kaisha Kobe Seiko Sho

Kobe Steel, Ltd.

Kenzo Ayata

Takasuke Mori

Kiichi Narita

Takahiko Fujimoto

Jun Miyazaki

Hitoshi Nakata

Hideo Mori

Susumu Ishiguro

Masaki Nitta

Hiroshi Takagi

Koichi Fujiwara

Toshiyasu Onishi

Masakazu Itashiki

Takao Shiozawa

Yasuhiko Ohta

Takehisa Makino

Yasuo Suzuki

In a method of continuous casting for rolling down a cast strand at the final stage of solidification to reduce segregation and center porosity at the center of the casting as much as possible and in particular prevent spot-shaped segregation, the rolling down is started after the center solid phase ratio of the casting reaches 0.2 and the rolling down is executed so as to compensate the total amount of volume contraction by solidification and cooling of strand in the section of the rolling down until the center solid phase ratio reaches 0.9 and thereafter the rolling down in continuously executed by a rolling down gradient of 0.08%/m or more to 1.5%/m or less.

Method of continuous casting

To provide a continuous casting method to diminish as much as possible center segregation and center porosity in the center of the cast piece, structure, a continuous casting method includes the application of reduction to a cast piece in the final solidification stage of the cast piece draw out process of continuous casting. The reduction is commenced at a point after the center solid fraction of the cast piece has reached 0.2, and the reduction gradient is decreased as the center solid fraction grows larger. The enlargement of the center solid fraction is divided into at least three zones with an optimal reduction gradient (%/m) established for each of the zones.

Continuous casting method

A method of electromagnetically stirring molten metal in an unsolidified portion of a continuously cast strand by a magnetic field formed by applying alternating current to at least two exciting coils, the method comprising: supplying to one of the exciting coils a first alternating current of a frequency in the range of 1-60 Hz and to the other one of the exciting coils a second alternating current with a frequency difference in the range of 0.03-0.25 Hz from the first alternating current to form a varying composite magnetic field thereby to induce stirred movement of varying direction and intensity in the molten metal.

Method of electromagnetic stirring in continuous metal casting process

A method for the continuous production of cast steel strands which are 200 mm.times.200 mm or less in cross-section by a continuous casting process in which molten steel containing over 0.20% of carbon is fed into a casting mold with a lubricant through a submerged nozzle or in an open stream and continuously drawn out downwardly of the casting mold, which includes the steps of (a) electromagetically stirring the molten steel at a position within said casting mold by the application of a magnetic field induced by introducing into an electromagnetic coil an alternating current of a frequency (f) in the range of 1.5 to 15 and maintaining the magnetic flux density (gauss) in the range of 602 e.sup.-0.10f to 1844 e.sup.-0.12f at the center of the electromagnetic coil, and (b) electromagnetically stirring the molten steel at a position in the final solidifying zone, of the continuously cast strand, in which the shorter diameter of the molten steel pool is smaller than 1/2 the length of the shorter side of the cast strand, by the application of a magnetic field induced by introduing an alternating current into an electromagnetic coil and maintaining the magnetic flux density (gauss) in the range of 0.143.multidot.D.sup.2 +231 to 0.343.multidot.D.sup.2 +451 at the center of the electromagnetic coil, wherein D is the solidified shell thickness in millimeters of the continuously cast strand, the value of the D ranging from 20 to 90, thereby permitting the production of medium and high carbon killed steel billets, which are improved as to segregations, inclusions, surface quality, cold forgeability, and machinability, by a continuous casting process at low cost.

Method for the continuous production of cast steel strands

A method for the continuous production of cast steel strands which are 200 mm.times.200 mm or less in cross-section by a continuous casting process in which molten steel containing 0.20% or less of carbon is fed into a casting mold with a lubricant through a submerged nozzle or in an open stream and continuously drawn out downwardly of the casting mold. The method includes the steps of (a) electromagnetically stirring the molten steel at a position within said casting mold by the application of a magnetic field induced by introducing into an electromagnetic coil an alternating current of a frequency (f) in the range of 1.5 to 15 hertz and maintaining the magnetic flux density (Gaub) in the range of 602e.sup.-0.10f to 2441e.sup.-0.11f at the center of the electromagnetic coil, and (b) electromagnetically stirring the molten steel at a position in the final solidifying zone, of said continuously cast strand, in which the shorter diameter of the molten steel pool is smaller than 1/2 the length of the shorter side of the cast strand, by the application of a magnetic field induced by introducing an alternating current into an electromagnetic coil and maintaining the magnetic flux density (Gaub) in the range of 0.2.multidot.D.sup.2 +280 to 0.343.multidot.D.sup.2 +451 at the center of the electromagnetic coil, wherein D is the solidified shell thickness in millimeters of said continuously cast strand, the value of D ranging from 20 to 90. The method thereby permits the production of low carbon killed steel billets which are improved as to negative segregations, center cavities, inclusions, surface quality, cold forgeability, and machinability, by a continuous casting process at low cost.

A device for electromagnetically regulating the pouring rate in continuous casting, including a cylindrical molten steel container having a molten steel inlet formed in a peripheral section of an upper surface thereof and a molten steel outlet formed in central section of a lower surface thereof to pour the molten steel into a mold, and electromagnetic coils disposed around the side wall of the molten steel container so as to generate a rotating magnetic field perpendicularly to the side wall. The pouring rate is determined by the interactive function of the head of the molten steel in the tundish disposed above the molten steel container with the outlet thereof joined to the inlet of the molten steel container, the intensity of the rotating magnetic field, namely, the magnitude of the electric current supplied to the electromagnetic coils, and the size of the molten steel outlet, namely, a replaceable pouring nozzle.

Method and device for electromagnetically regulating pouring rate in

A horizontal continuous casting process wherein at least two electromagnetic stirring devices of a rotary magnetic field type are arranged in series direction whereby electromagnetic stirring force acts on non-solidified molten metal, and the distance between the electromagnetic stirring devices of first and second stages is set to specified relation.

Electromagnetic stirring method in horizontal continuous casting process

An electromagnetic within-mold stirring method and apparatus wherein electromagnetic stirring is imparted to molten steel passing through a mold, under the following conditions where the maximum flux density (in gauss) of a magnetic field induced by an electro-magnetic coil ranges from 1045.e.sup.-0.16f to 2054.e.sup.-0.12f (f: frequency, 1-15 Hz) and the place of the maximum magnetic flux density is within the range of 350 mm from the junction between the pouring nozzle and the mold in the direction of drawing of the cast-piece.

Electromagnetic within-mold stirring method of horizontal continuous

A continuous steel casting process adapted to produce steel castings of satisfactory quality with less center segregations is described. A molten steel is electromagnetically stirred in at least two of three locations, viz., a casting mold and intermediate and final solidifying zones of a continuously cast strand. In the casting mold, is applied a magnetic field induced by alternate current of a frequency f=1.5.about.10 Hz and having G in the range of 195.times.e.sup.-0.18f .about.1790.times.e.sup.-0.2f at the inner surface of the casting mold. The intermediate solidifying zone employs a magnetic field induced by alternate current of a frequency f=1.5.about.10 Hz and having a magnetic flux density G in the range of 195.times.e.sup.-0.18f .about.1790.times.e.sup.-0.2f at the surface of the strand or a magnetic field induced by alternate current of a frequency f=50.about.60 Hz and having a magnetic flux density G in the range of 0.6.times.10.sup.6 /(D-107).sup.2 .about.1.8.times.10.sup.6 /(D-100).sup.2 (in which D=the thickness of a solidified shell layer of the strand) at the surface of the strand. For electromagnetic stirring in the final solidifying zone, a magnetic field induced by alternate current of a frequency f=1.5.about.10 Hz and having a magnetic flux density in the range of 895.times.e.sup.-0.2f .about.2137.times.e.sup.-0.2f is applied.

Continuous steel casting process

A method for treating molten steel utilizing an induction coil, a ladle, a treating vessel and at least one passage pipe interconnecting the ladle and the treating vessel which includes the steps of lifting up a part of the molten steel from the ladle to the treating vessel disposed over the ladle through adjustment of molten steel composition and/or degassing in the treating vessel, thereafter returning the molten steel to the ladle through the at least one passage pipe, circulating or reciprocating the molten steel between the ladle and the treating vessel while heating the molten steel by the induction coil disposed around the at least one passage pipe and operating the linear motor at a frequency of 50 to 60 cycles.

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Kobe, Japan

Kenzo Ayata