JPH08257710A - Immersion nozzle for continuous casting - Google Patents

Abstract

PURPOSE: To provide an immersion nozzle easily feeding a wire-additive in the case of a sliding nozzle system, etc., at the time of shape-controlling and reforming non-metallic inclusion in a continuous casting. CONSTITUTION: This immersion nozzle for continuous casting is provided with an introducing tube 10 between a continuous casting mold 1 and a tundish 3 for supplying molten steel into this mold for wire-additive 5 extending in the diagonally upper direction at the side surface of the immersion nozzle 2. Therefore, even in the case of being impossible to feed the wire just above the immersion nozzle 2, the additive 5 is fed from the side surface of the nozzle to execute a melting and reaction, and a shape-control and a reform of the inclusions can efficiently be executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dipping nozzle which facilitates the supply of a wire additive for controlling the shape and modification of non-metallic inclusions in molten steel in a continuous casting machine.

[0002]

2. Description of the Related Art In continuous casting of steel, non-metallic inclusions such as alumina (Al ₂ O ₃ ) mixed in molten steel are very hard and have a high melting point. If it is rolled as it is, this will remain as a surface flaw (sliver flaw) of the product, which is not preferable in terms of quality.

As a means for modifying these hard inclusions, for example, by adding Ca as an additive, alumina is soft and has a low melting point of (Al ₂ O ₃ ) _m (CaO) _n.
To prevent the occurrence of surface defects during rolling.

As a method of adding this additive to the molten steel, for example, a method of directly adding lump Ca to a ladle of molten steel or a tundish, and a method of adding the additive to the core of a stopper for opening and closing a discharge nozzle of the tundish There is a method in which a wire introduction hole is provided and a wire-shaped additive is fed from the introduction hole to the immersion nozzle.

In the former method of directly adding the lump-shaped additive, since the additive substance generally has a smaller specific gravity than molten steel,
Even if it was put into a ladle or tundish as it was, it floated on the surface of the ladle and could not be dissolved or reacted normally, which was inefficient and wasted.

In the latter method of feeding the wire-shaped additive to the immersion nozzle, the wire is rapidly melted by the flow of the molten steel in the immersion nozzle, and the mixture is uniformly stirred in the molten steel. The additive reacts effectively without waste, and is effective in that it can reduce the basic unit of the additive and uniformly disperse the additive.

Generally, many of the additive substances have a low solubility in molten steel and have a low boiling point and are easily gasified. Therefore, it is necessary to rapidly push the molten steel to a position where the flow velocity of the molten steel is as fast as possible. Therefore, it is possible to linearize the additive. It is effective. For this reason, this is made into a wire shape, and when it is intended to be added only to a specific part of the cast piece, for example, the bottom piece (B piece), the additive is supplied in the immersion nozzle with a high molten steel flow rate. It is also effective in reducing the chance of pollution such as oxidation.

As a means for supplying the wire-shaped additive into the dipping nozzle, for example, US Pat. No. 4,520,861 is used.
(Jun, 4.1985) discloses a method and apparatus for continuously feeding an alloy wire into a dipping nozzle through a stopper rod in continuous casting.

[0009] This technique is originally intended to infiltrate molten steel into the wire conduit provided in the stopper rod at the initial stage of casting.
As shown in FIG. 2, the device shown here prevents clogging due to solidification, but as shown in FIG. 2, the introduction hole 4a is provided in the stopper 4 that opens and closes the discharge nozzle 3a at the bottom of the tundish 3.
Is provided, and the wire additive 5 is vertically passed therethrough.

Next, the wire additive 5 supplied from the wire feeder 8 is fed into the immersion nozzle 2 through the stopper 4, and the additive is supplied to the molten steel 9 in the nozzle 2. In the figure, 1 is a mold, 6 is an inert gas supply device, and 7 is a wire insertion tube.

[0011]

By the way, for example, a sliding nozzle or the like may be inserted instead of the stopper between the tundish and the dipping nozzle, and the wire or the like may not be supplied from the upper part, so that the shape control of the inclusions, At the time of modification, the advantage of adding a wire-shaped additive having a sharp bend was not utilized, and the conventional method of directly adding an inefficient lump-shaped additive to the tundish had to be resorted to.

The present invention has been made in view of the above problems,
Provided is a dipping nozzle capable of smoothly supplying a wire additive even in a dipping nozzle of a sliding nozzle type when controlling and modifying the shape of molten steel in continuous casting.

[0013]

DISCLOSURE OF THE INVENTION The present invention relates to a dipping nozzle mounted between a continuous casting mold and a tundish for supplying molten steel to the mold, and a wire additive extending obliquely on the side surface of the dipping nozzle. It is an immersion nozzle for continuous casting, which is equipped with an introduction pipe.

[0014]

With the above configuration, a sliding nozzle or the like is provided between the immersion nozzle and the tundish, and even when the wire additive cannot be supplied from directly above the immersion nozzle, the side surface of the immersion nozzle is inclined upward. An extending introducing pipe is attached, and the wire additive is supplied into the dipping nozzle from the introducing pipe.

In this way, the additive is rapidly melted by the flow of molten steel and reacts in the immersion nozzle without waste, so that the unit consumption of the additive can be reduced and the additive can be uniformly dispersed. It is possible to use a dipping nozzle that takes advantage of the advantages of a wire-shaped additive.

If the diameter of the wire additive is too small, a constant amount of the additive has to be supplied at a high speed at all times, which is not preferable for equipment. Further, if this diameter is made thick, it is inconvenient to store and handle, and the supply device becomes large, and the diameter which can be usually handled easily is about 7 to 8 mmφ. Therefore, the wire feeding speed may be taken into consideration with this diameter as a standard.

[0017]

【Example】

FIG. 1 is a schematic side sectional view showing an embodiment of the continuous casting immersion nozzle of the present invention. In this embodiment, the tundish 3 is placed on the upper part of the continuous casting mold 1 through the immersion nozzle 2.
And a sliding nozzle 12 is attached between the discharge nozzle 3a attached to the bottom of the tundish and the base of the immersion nozzle 2.

Further, an introducing pipe 11 for the wire additive 5 is attached through a nozzle 10 provided on the side surface of the immersion nozzle 2 so as to extend obliquely upward, and an inert gas supply for feeding Ar or the like to the introducing pipe. The device 6 is connected.

With the above construction, for example, the molten steel in which the wire additive 5 fed from the wire feeding device installed adjacently to the dipping nozzle 2 through the introducing pipe 11 is injected into the nozzle. It is supplied to the inside and melts and reacts here to control the morphology of inclusions in the molten steel and modify it.

Calcium (Ca) is often used as an additive for controlling and modifying the morphology of molten steel. In addition, bismuth (Bi), lead (Pb), boron (B), titanium (Ti) are added as additives to impart special properties to the cast slab.
Etc. may be used. These additives are covered with a steel tube, drawn to an outer diameter of about 7 to 8 mmφ, and used as a wire.

As described above, even when the sliding nozzle or the like is provided between the immersion nozzle and the tundish and the wire additive cannot be supplied from directly above the immersion nozzle,
Attach an inlet pipe that extends obliquely upward to the side of the immersion nozzle,
By supplying the wire additive from the introduction pipe into the immersion nozzle, it can be melted and reacted smoothly in the immersion nozzle, reducing the waste of the additive and further reducing the chance of contamination such as oxidation. Target.

[0023]

As described above, according to the present invention, even when the wire additive cannot be supplied from directly above the immersion nozzle,
The additive is supplied smoothly into the nozzle by attaching the introduction pipe to the side of the dipping nozzle in an obliquely upward direction, and the supplied wire additive is rapidly melted by the flow of the molten steel in the dipping nozzle. Stir evenly.

In this way, while taking advantage of the addition of the wire-shaped additive, the additive is dissolved and reacted in the immersion nozzle, the additive reacts effectively without waste, and the unit consumption of the additive is reduced and the additive is uniformly dispersed. Therefore, the morphology of non-metallic inclusions can be efficiently controlled and modified.

[Brief description of drawings]

FIG. 1 is a schematic side sectional view showing an embodiment of the immersion nozzle of the present invention.

FIG. 2 is a schematic side sectional view showing an example of a conventional wire additive supply type immersion nozzle.

[Explanation of symbols]

 1 Mold 2 Immersion Nozzle 3 Tundish 3a Discharge Nozzle 4 Stopper 4a Inlet Hole 5 Wire Additive 6 Inert Gas Supply Device 7 Wire Insertion Pipe 8 Wire Feeder 9 Molten Steel 10 Nozzle 11 Inlet Pipe 12 Sliding Nozzle

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shiomi Kiyomi 20-1 Shintomi, Futtsu City Nippon Steel Co., Ltd. Technical Development Division (72) Inventor Kiyoshi Isono 1 Fuji-machi, Hirohata-ku, Himeji City New Japan Steel Stock company Hirohata Works

Claims (1)

[Claims] 1. An immersion nozzle installed between a continuous casting mold and a tundish for supplying molten steel to the mold, wherein a wire additive introducing pipe extending obliquely upward is attached to a side surface of the immersion nozzle. Immersion nozzle for continuous casting.