Sumitomo Metal Industries, Inc.

Masayuki Kawamoto

Masahito Hanao

Hiroshi Hayashi

Atsushi Hirata

Yuichi Tsukaguchi

Manabu Adachi

Toshihiko Murakami

Masahiko Oka

Seiji Kumakura

Toru Kato

Hirohisa Kikuchi

Masashi Hara

Norihiro Nishida

Yoshinori Tanizawa

In a mold for continuously casting a round billet with a curved type continuous casting apparatus, assuming that D(m) is an inner diameter at a lower mold edge and R(m) is a curvature radius of an outer curvature side at the lower mold edge, when a rate of change Tp (%/m) in mold inner diameter per unit length along a casting direction is expressed by Formula 1, and when a rate of change Rp (%/m) in curvature radius of an outer curvature side per unit length along the casting direction is expressed by Formula 2, the rate of change Tp in mold inner diameter and the rate of change Rp in curvature radius satisfy a relationship expressed by Formula 3;=(1/)&#xd7;()&#xd7;100(%/)&#x2003;&#x2003;Formula 1=(1/)&#xd7;()&#xd7;100(%/)&#x2003;&#x2003;Formula 2where D in Formula 1 is a mold inner diameter at a distance x away from an upper mold edge and R in Formula 2 is a curvature radius of the outer curvature side at the distance x,=(/2)&#xd7;()&#x2003;&#x2003;Formula 3 Uniform and good contact is obtained between the billet and a mold inner peripheral surface over a whole circumference, so that the casting-defect-free high-quality round billet can stably be produced.

Continuous casting mold and continuous casting method of round billet

In a mold for casting a billet with a curved type continuous casting apparatus, D(m) is an inner diameter at a lower mold edge and R(m) is a curvature radius of an outer curvature side at the lower mold edge. When a rate of change Tp (%/m) in mold inner diameter per unit length along a casting direction is Tp=(1/D)&#xd7;(dD/dx)&#xd7;100 (%/m), and when a rate of change Rp (%/m) in curvature radius of an outer curvature side per unit length along the casting direction is Rp=(1/R)&#xd7;(dR/dx)&#xd7;100 (%/m), the rate of change Tp in mold inner diameter and the rate of change Rp in curvature radius satisfy a relationship expressed Rp=(Tp/2)&#xd7;(D/R), where D is a mold inner diameter at a distance x away from an upper mold edge and R in Formula 2 is a curvature radius of the outer curvature side at the distance x.

A method for continuously casting a billet with a small cross section in which a curved type or vertical type continuous casting machine is used while oscillating the mold upward and downward is characterized in that the casting machine is provided with a mechanism for withdrawing speed oscillation. The mechanism has structural play in the directions of driving and reverse driving in such a manner that the amount of a play-incurred displacement from the neutral position of the structural play in the direction of billet driving or reverse driving is &#xb1;2 to &#xb1;30 mm in the direction of driving on the pinch roll circumferential length equivalent basis. The mechanism produces a returning force toward the neutral position and operational parameters such as the billet length, the specific amount of secondary cooling water, the casting speed as well as the oscillation amplitude and frequency are optimized.

Method of continuous casting of small cross section billet

Continuously casting a billet with a small cross section by pouring molten steel into a mold using a cylindrical immersion nozzle is characterized by measuring the molten steel level in the mold using an eddy current sensor. The level is controlled based on the thus-measured value, motion of steel in the mold is adjusted by electromagnetic stirring, a cooling zone during the final period of solidification is disposed within a certain region ranging from the meniscus to the specific site, and casting speed is adjusted so that the region in which the solid phase ratio at the billet center is 0.3-0.99 may be included in the cooling zone during the final period of solidification. The secondary cooling water amount and the billet surface temperature at the entrance to the cooling zone the density of cooling water in the cooling zone during the final period of solidification are optimized.

Method for continuously casting billet with small cross section

An apparatus for supplying molten steel and a continuous casting method therewith are described. The apparatus is equipped with a tundish having an upper nozzle at the bottom, a flow control mechanism disposed below the upper nozzle an immersion nozzle formed by a refractory material having a good electrical conductivity, one electrode disposed in the inner space of the tundish the other electrode disposed in the immersion nozzle and a power supply connected to the electrodes and In the method, the molten steel is supplied into a mold in the state of supplying an electric current between the inner surface of the immersion nozzle and the molten steel passing through the inside thereof by utilizing the apparatus for supplying molten steel. The deposition of the Al oxide or the like in the molten steel onto the inner surface of the immersion nozzle and others can be prevented, and thereby the generation of the surface defects in the products can also be prevented.

Molten steel supplying apparatus for continuous casting and continuous casting method therewith

A method of continuous casting of a steel employs a mold power having a viscosity of 0.5-1.5 poise at 1,300&deg; C. and a solidification temperature of 1,190-1,270&deg; C., in which the mass ratio of CaO to SiO is 1.2-1.9, and casting is carried out under the following conditions: casting speed is 2.5-10 m/minute; mold oscillation stroke is 4-15 mm; and specific cooling intensity in secondary cooling of a slab is 1.0-5.0 liter/kg-steel.

Method for continuous casting of steel

A mold powder for continuous steel casting, contains CaO, SiO.sub.2 and fluoride as the main components. The ratio by weight of CaO', represented by the following equation, to SiO.sub.2 is 0.9-2.8 and the CaF.sub.2 content is about 5-60 wt. %. The powder contains Na.sub.2 O in an amount of 0-25 wt. % and C in an amount of 0-10 wt. %.

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Kashima, Japan

Masayuki Kawamoto