JPH0679409A - Production of double layer cast slab - Google Patents

Abstract

PURPOSE:To provide a producing method for complex layer cast slab preventing the development of solidified material in the back side of a nozzle for inner layer in continuous casting for the double layer cast slab. CONSTITUTION:In the producing method for the double layer cast slab, stirring gas 12 is blown from a range at the upper part of a static magnetic field 5 zone to around the nozzle 2 for inner layer, and molten metal is supplied and cast while deviating the discharging direction of a nozzle 1 for surface layer toward gap direction between the nozzle 2 for inner layer and a mold 3 wall. By this method, the development of the solidified material developed in a meniscus part in the mold is restrained and the double layer cast slab can continuously and stably be produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a multi-layer cast product by injecting molten metals having different compositions from two nozzles charged in a mold.

[0002]

2. Description of the Related Art As a method for producing a composite steel material by continuous casting, two immersion nozzles having different lengths are inserted into a pool of molten metal in a mold, and the discharge ports of the respective nozzles are located at different depths. Japanese Patent Publication No. 44-27361 discloses a technique for injecting different kinds of molten metal in the above.

Japanese Patent Publication No. 49-44859 discloses that
It is disclosed that a partition made of a refractory is provided between different kinds of molten metals injected into a mold, and continuous casting is performed while preventing different kinds of metals from mixing with each other.

Further, in Japanese Patent Publication No. 63-108947, as shown in FIG. 2, a magnetic pole 4 is used between different kinds of molten metal injected into a mold 3 through immersion nozzles 1 and 2, and both metals are A technique for producing a multi-layer cast product while preventing mixing is disclosed.

This forms a static magnetic field 5 in which magnetic lines of force are present over the entire width of the slab in a certain length region in the casting direction, and with the static magnetic field 5 as a boundary, different kinds of molten metals 6, 7 are supplied above and below the static magnetic field 5. To do. As a result, it is possible to minimize the mixing of the upper and lower layers at the position where the upper and lower layers are in contact with each other.

[0006]

Conventionally, in continuous casting, a single immersion nozzle has been used in the mold. Therefore, no solidified material was generated in the vicinity of the meniscus 10 in the mold. On the other hand, in the technique of manufacturing two-layer cast product by simultaneously injecting two kinds of molten metals into a mold, two dipping nozzles with different lengths are inserted at upper and lower positions separated by a static magnetic field 5 in the mold. In order to supply the molten metal in the mold, the molten metal discharge stream 6 for the surface layer is not sufficiently supplied to the back of the inner layer nozzle 2 in the upper part of the static magnetic field in the mold, and therefore solidified matter is formed behind the inner layer nozzle. 8 is generated, and casting becomes impossible.

According to the present invention, in the continuous casting of the above-mentioned multi-layered slab, the formation of solidified matter behind the inner layer nozzle near the meniscus is prevented, and the multi-layered slab is stably produced by the continuous casting. Provide a way.

[0008]

According to the present invention, a surface layer nozzle is immersed in an upper part and an inner layer nozzle is in a lower part in a mold which is vertically divided by a static magnetic field, and molten metals having different components are injected from the respective nozzles. Then, in the method for producing a cast multi-layer slab that cools and solidifies this, the stirring gas in the meniscus portion is blown from the region above the static magnetic field region around the inner layer nozzle, and the discharge direction of the surface layer nozzle is changed. The method for producing a cast multi-layer cast product is characterized in that the inner layer nozzle and the mold wall are deflected and supplied in the gap direction.

Here, it is preferable that the slit for blowing the stirring gas is installed in a direction not facing the surface layer nozzle of the inner layer nozzle. Further, it is preferable that the gas is blown out not only from the slit but also from the porous plug provided in the surface layer portion through the slit portion to the outside of the nozzle.

[0010]

FIG. 1 shows a schematic side view of a continuous casting mold suitable for carrying out the present invention. This apparatus has a slit for blowing gas around the inner layer nozzle, and further has a discharge direction of the surface layer nozzle. A multi-layer cast slab is manufactured by a method of changing between the inner layer nozzle and the mold wall.

In the figure, a gas blowing slit 11 is provided around the inner layer nozzle 2 in the upper region of the static magnetic field 5 on the end side of the mold 3, and a gas 12 is blown through the slit 11, and further the inner layer of the surface layer nozzle 1 is provided. The discharge port in the direction of the working nozzle 2 is installed between the inner layer nozzle and the mold wall 3.

Then, in this region, the surface-layer molten metal discharge flow 6
Is supplied, the circulation of the molten metal between the inner layer nozzle 2 and the end piece of the mold 3 is promoted to suppress the formation of a solidified product while performing the casting.

In this case, the molten steel behind the inner layer nozzle 2 is agitated by the gas 12 blown from the nozzle. Further, heat is supplied by the surface layer molten metal discharge stream 6 supplied between the inner layer nozzle 2 and the mold wall 3.

Here, the slit 11 for gas injection of the inner layer nozzle 2 is installed only on the mold end side, that is, when the slit 11 is installed on the surface layer nozzle 1 side, the gas 12 from the slit discharges the surface layer. 6 was agitated,
This is because the surface layer discharge stream 6 is not efficiently supplied between the inner layer nozzle 2 and the end portion of the mold 3.

In the apparatus used in the conventional process, the molten metal for the surface layer is cast without changing the discharge direction 6 or blowing gas, so that the flow behind the inner layer nozzle 2 stagnates, so A solidified product 8 is generated as shown in FIG. In the figure, 7 is the inner layer molten metal discharge flow, and 9 is
Is a molten metal flow in the mold, and 10 is a meniscus.

Further, in FIG. 1, when the slit 11 was provided inside and a porous refractory (not shown) was provided outside this, the molten steel flow due to the gas was improved and no solidified matter in the mold was generated.

[0017]

EXAMPLE A continuous casting mold having a horizontal cross section of 250 × 980 mm and a continuous casting mold was used to cast a multi-layer slab having a stainless steel outer layer and an aluminum killed steel inner layer at a casting speed of 1 m / min by a continuous casting method. Manufactured in.

Initially, as a conventional method, as shown in FIG. 2, two nozzles for the surface layer and the inner layer were dipped in a mold,
Casting was performed while ensuring a heating degree of ° C. However, since the molten steel flow between the inner layer nozzle and the mold end piece stagnates, a solidified product is generated between the inner layer nozzle and the mold end piece during casting,
Further, the solidified product came into contact with the inner layer nozzle and casting became impossible.

Therefore, as shown in FIG. 1, a slit for gas injection is installed on the mold end around the inner layer nozzle in the upper region of the static magnetic field, and 1 liter / min of gas is injected into the molten steel through the slit. It is.

Further, the discharge direction of the molten steel from the surface layer nozzle was made the inner layer nozzle direction, and the direction was changed so that the molten steel was supplied between the inner layer nozzle and the mold wall. As a result, the solidified material that had been conventionally generated in the meniscus portion in the mold is no longer generated.

[0021]

According to the method for producing a multi-layer cast product of the present invention,
The stirring gas is blown around the inner layer nozzle, and the discharge direction of the surface layer nozzle is deflected in the gap direction with the mold wall to supply the gas, thereby suppressing the generation of the solidified product in the meniscus portion in the mold. Therefore, it becomes possible to continuously and stably manufacture the multi-layer cast product while avoiding the situation that casting is impossible.

[Brief description of drawings]

FIG. 1 is a schematic side view (a) and a plan view (b) of a continuous casting mold suitable for carrying out the present invention, in which a slit for blowing gas is installed around a nozzle for an inner layer and a nozzle for a surface layer is provided. The state which manufactures a multi-layer cast product by the method of changing a discharge direction between a nozzle for inner layers and a mold wall is shown.

2A and 2B are a schematic side view (a) and a plan view (b) of a conventional example of a continuous casting mold, in which gas is not blown from around the inner layer nozzle and a solidified product is formed between the inner layer nozzle and the mold end portion. Shows the state generated by.

[Explanation of symbols]

 1 Surface Layer Nozzle 2 Inner Layer Nozzle 3 Mold 4 Magnetic Pole 5 Static Magnetic Field 6 Surface Layer Molten Metal Discharge Flow 7 Inner Layer Molten Metal Discharge Flow 8 Solidified Material 9 Mold Molten Metal Flow 10 Meniscus 11 Gas Blowing Slit 12 Gas Bubble

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location B22D 11/10 360 D 7362-4E

Claims (1)

[Claims] 1. A surface layer nozzle is immersed in an upper part and an inner layer nozzle is immersed in a lower part in a mold divided into upper and lower parts by a static magnetic field,
Inject molten metal with different components from each nozzle,
In the method for producing a cast multi-layer cast product in which this is cooled and solidified, a stirring gas is blown from the upper region of the static magnetic field around the inner layer nozzle, and the discharge direction of the surface layer nozzle is set to the inner layer nozzle and the mold. A method for producing a cast multi-layer cast slab, characterized in that it is supplied while being deflected in a gap direction with respect to a wall.