JPH11285791A - Immersion nozzle for continuous casting and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently strengthen the neighborhood of a discharge port by stretching and embedding a fiber body of an inorg. material having a specific ratio of the total of Al2 O3 and SiO2 from a position parted by a specific size toward an aperture from one end on the inner side of the discharge port of the nozzle body to a longitudinal direction of the nozzle body into the refractories in the columnar part of the discharge port adjacent to the side part of the discharge port. SOLUTION: The fiber body is composed of >=80 wt.% the total of the Al2 O3 and SiO2 , its embedding position is set to the position parted by >=20 mm from one end on the inner side of the discharge port. The content of the fiber body in the embedment section is 0.1 to 2 wt.% and the diameter of the fiber body is 0.5 to 2 mm. The molten steel path 3 of the nozzle body 2 is provided with a base part 4. The peripheral flanks of the nozzle body 2 are provided with the two rectangular discharge ports 6. The nozzle body 2 is reinforced by embedding the fiber body 9 into the refractories 2a of the base part area 11 of the columnar part with the end 12 of the spacing distance from the discharge port columnar part 8 adjacent to the side part 7 and the ends 10 of the discharge ports 6 as a start point. The fiber body 9 is not deteriorated in strength by oxidation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an immersion nozzle for continuous casting and a method for manufacturing the same, and more particularly to an immersion nozzle for continuous casting with improved strength near the discharge port of the nozzle and a method for manufacturing the same.

[0002]

2. Description of the Related Art In a continuous casting process, when a molten steel is poured from a tundish into a mold, an immersion nozzle is used to prevent oxidation of the molten steel and to control the flow of the molten steel in the mold. Normally, the molten steel that has flowed down vertically from the tundish hits the bottom surface of the inner opening of the immersion nozzle and flows into the mold from a discharge port provided on the lower side surface of the immersion nozzle. At the time of initial molten steel injection, a large amount of molten steel flows from the tundish into the immersion nozzle, and a mechanical impact is applied to the inner bottom of the immersion nozzle. Since the discharge port is provided near the discharge port, the structural strength was the weakest in the part of the immersion nozzle, but in the past, since the safety factor of the structural strength near the discharge port could be taken sufficiently large, It was not a problem that the structural strength near the discharge port was weakest.

However, in recent years, the structural strength in the vicinity of the discharge port has been reduced due to the decrease in the area of the discharge port column due to the slimming of the nozzle itself and the increase in the size of the discharge port. Breaks into the immersion nozzle from
There is a problem that the tip of the immersion nozzle is chipped off.
In order to solve such a problem, the conventional method of reinforcing a refractory for casting is to add carbon fiber to the refractory,
Arrange carbon fiber nets, arrange carbon or graphite fiber bundles tied with single fibers with directivity, or disperse in non-directional refractories, The fibers are agglomerated.

However, these conventional reinforcing methods are
In the vicinity of the discharge port where it is difficult to ensure a sufficient thickness of the material, there is a high possibility that the fiber disposed in the refractory will come into contact with oxygen, and the strength of carbon and graphite based fibers will be extremely reduced due to oxidation, and A fiber of sufficient length suitable for this reinforcing method cannot be obtained. Metal fibers have low strength at high temperatures and do not provide reinforcement.

[0005]

Therefore, there has been a demand for a continuous casting immersion nozzle and a method of manufacturing the reinforcing fiber, in which the strength of the reinforcing fiber does not deteriorate due to oxidation and the strength near the discharge port is sufficiently obtained.

The present invention has been made in view of the above-described circumstances, and provides a continuous casting immersion nozzle and a method of manufacturing the same, in which the strength of the reinforcing fiber does not deteriorate due to oxidation and the strength near the discharge port is sufficiently obtained. The purpose is to do.

[0007]

Means for Solving the Problems In order to achieve the above-mentioned object, the invention of claim 1 of the present application provides a chemical composition of Al ₂ O ₃
And a fiber body made of an inorganic material having a total of 80% by weight or more of the chemical composition SiO ₂ and the starting point at a position separated from the inner end of the discharge port provided in the nozzle body by 20 mm or more in the opening direction of the nozzle body. The gist of the present invention is a continuous casting immersion nozzle characterized by being extended in the longitudinal direction of the nozzle body and buried in a refractory material forming a discharge port columnar portion adjacent to a side of the discharge port.

According to a second aspect of the present invention, the content of the fiber body in the buried portion of the fiber body is 0.1%.
The immersion nozzle for continuous casting according to claim 1, wherein the amount is 浸漬 2% by weight.

[0009] The invention of claim 3 of the present application has a gist of the immersion nozzle for continuous casting according to claim 1 or 2, wherein the diameter of the fiber body is 0.5 to 2 mm.

According to the invention of claim 4 of the present application, a rubber mold having a mandrel and an opening is prepared, and a part of the rubber mold is filled with the refractory raw material from the opening, and the refractory raw material is not filled. A fiber body made of inorganic material is suspended in a ring shape in a rubber mold, and a refractory material is filled so as to bury the fiber body, and after pressing the refractory material filled in the rubber mold,
Demolding to form a molded body of a continuous casting immersion nozzle, cutting off a part of the molded body together with a fiber body, providing a discharge port, and firing the molded body. The gist is that this is a manufacturing method.

According to a fifth aspect of the present invention, the fiber body has a total of a chemical composition of Al ₂ O ₃ and a chemical composition of SiO ₂ of 80.
The fiber body made of an inorganic material having a weight percent or more is discharged from a position adjacent to the side of the discharge port starting from a position separated from the inner end of the discharge port provided in the nozzle body by at least 20 mm in the opening direction of the nozzle body. The gist of the present invention is a method for manufacturing a continuous casting immersion nozzle according to claim 4, wherein the nozzle is extended in the longitudinal direction of the nozzle body and buried in a refractory material forming the outlet columnar portion.

According to the invention of claim 6 of the present application, the content of the fiber body in the embedded portion of the fiber body is 0.1%.
The gist of the invention is a method for producing a continuous casting immersion nozzle according to claim 4 or 5, wherein

The invention according to claim 7 of the present application is the method for producing a continuous casting immersion nozzle according to any one of claims 4 to 6, wherein the diameter of the fiber body is 0.5 to 2 mm. The main point is.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a continuous casting immersion nozzle according to the present invention will be described below with reference to the accompanying drawings.

A continuous casting immersion nozzle 1 according to the present invention as shown in FIG. 1 comprises a nozzle body 2.
Has a molten steel channel 3 having a length of, for example, 700 mm in a hollow shape and a diameter of, for example, 72 mm for flowing molten steel, in the axial direction, and a bottom portion 4 is provided at an end portion of the molten steel channel 3. An inflow port 5 for inflow of molten steel is provided to face the portion 4, and a peripheral side surface of the nozzle body 2 close to the bottom surface portion 4 is provided with two molten steel discharge holes, for example, having a height of 80 on the diameter of the nozzle body 2. , A rectangular discharge port 6 having a width of 70 mm is provided facing the discharge port 6.

The nozzle body 2 for forming the discharge port 6
A discharge port column 8 is formed adjacent to the side 7 of the discharge port 6 between the discharge port 6 and the remaining portion of the nozzle body 2 which is partially cut away. A fiber body 9 made of an inorganic material is buried in the center of the thickness of the outlet column 8.

The fiber body 9 has a chemical composition of Al ₂ O
₃ and the chemical composition SiO ₂ are at least 80% by weight, for example, the chemical composition Al ₂ O ₃ is 60% by weight and the chemical composition SiO 2 is
₂ 25 wt%, an inorganic material of B ₂ O ₃ is 15 wt%, the diameter are bound by twisting monofilaments 0.5~2m
m, for example 0.8 mm.

The fiber body 9 has a chemical composition of Al ₂ O.
_It may be a single fiber having a total of ₃ and the chemical composition SiO ₂ of 80% by weight or more.

Further, the fiber body 9 is located in the base region 11 where the distance X between the end 12 of the fiber body 9 and the inner end 10 of the discharge port 6 is 20 mm or more, for example, 20 mm. Refractory 2a forming column-shaped portion base region 11 and discharge port column-shaped portion 8 starting from portion 12
The inside extends parallel to the longitudinal direction of the nozzle body 2 and is embedded. Note that the columnar base region 11 is a region located on an extension of the upper part of the discharge port columnar portion 8 and within a certain distance X from the inner end 10 of the discharge port 6.

The refractory 2 forming the buried portion of the fiber body 9, that is, the columnar portion base region 11 and the discharge port columnar portion 8.
The content of the fiber body 9 in a is 0.1 to 2% by weight, for example, 1% by weight.

The reason why the diameter of the fiber body 9 is required to be 0.5 to 2 mm is that the fiber body 9 has a diameter of 0.5 mm in order to manufacture the molded body 1a of the immersion nozzle 1 as shown in FIG. If not, the work of embedding in the refractory raw material 2a is difficult, and if it is not more than 2 mm, the refractory is peeled off from the embedded portion of the fiber body 9, that is, the discharge port column portion 8.

The reason that the total of the chemical composition Al ₂ O ₃ and the chemical composition SiO ₂ of the fiber body 9 needs to be 80% by weight or more is that the immersion nozzle 1 is about 1200
This is because the fiber body 9 can be used only at 80% by weight or more of Al ₂ O ₃ + SiO ₂ when used at a temperature higher than this temperature.

The installation position at the end 12 of the fiber body 9, that is, the starting point of the fiber body 9 is the upper end 7 inside the discharge port 6.
The reason is that the structural strength is weakest in the vicinity of the upper portion of the discharge port 6 in the columnar base region 11, and the fiber body 8 is buried to a position 20 mm or more than the inner end 10. Otherwise, there is a risk that the tip portion including the bottom surface portion 4 of the nozzle body 2 may fall from the columnar portion base region 11 due to the impact at the time of initial molten steel injection.

The reason why the content of the fiber body 8 in the embedded portion of the fiber body 8 is 0.1 to 2% by weight is as follows.
If the content is less than 0.1% by weight, the strength cannot be improved. If the content is more than 2% by weight, the refractory 2a is peeled off from the embedded portion of the fiber body 9 due to the mechanical impact at the time of initial molten steel injection.

Next, a method of manufacturing a continuous casting immersion nozzle according to the present invention will be described with reference to FIG.

A rubber mold 15 provided with a mandrel 13 and having an opening 14 is prepared.
5 is filled with the refractory raw material 2a. Next, a fiber body 9 made of an inorganic material having a total of 80% by weight of the chemical composition Al ₂ O ₃ and the chemical composition SiO ₂ as described above was placed in the other portion 17 of the rubber mold 15 not filled with the refractory raw material 2a. The material material 2a is suspended in a ring shape at a position corresponding to the thickness center portion, and the other portion 17 is further filled with the refractory material 2a so as to bury the fiber body 9.

Further, the refractory raw material 2a filled in the rubber mold 15 is pressed via the rubber mold 15 by a hydrostatic pressure press.
The mold is removed to form a molded body 1a of the immersion nozzle 1. A part of the molded body 1a is cut out together with the fiber body 9 to provide a discharge port 6, and the molded body 1a is fired to manufacture the immersion nozzle 1.

Since the immersion nozzle 1 according to the present invention has the above-described structure, when the immersion nozzle 1 is used by attaching it to a tundish, molten steel is injected into the tundish through the immersion nozzle 1. At the time of initial molten steel injection, the mold is not filled with molten steel and the immersion nozzle 1
Since the molten steel does not press the back surface of the bottom surface portion z of the immersion nozzle 1, all impacts by the flow of the molten steel are applied to the bottom surface portion 4 of the immersion nozzle 1. However, the immersion nozzle 1 is configured such that the fiber body 9 is inserted into the column base portion 11 and the discharge port column 8 which are structurally weakest in the nozzle body 2 from the upper end 10 inside the discharge port 6.
Starting from a position of 0 mm or more, the column base portion 11 and the discharge port column 8 are buried in parallel to the longitudinal direction of the nozzle body 2 to reinforce the structural strength. The tip of the nozzle body 2 does not fall off the part 8.

When the mold is filled with molten steel, the nozzle body 2 is constantly exposed to high-temperature molten steel.
The fiber body 9 has a chemical composition of Al ₂ O ₃ and a chemical composition of SiO.
₂ is an inorganic material having a total weight of 80% by weight and is embedded in the thick portion of the discharge port columnar portion 8, so that the fiber main body 9 is less likely to be oxidized and deteriorated, and can withstand high temperatures.
Also, even if a crack is formed in the columnar base region 11 or the discharge port columnar portion 8, the progress of the crack is hindered by the fiber body 9, and the progress from the crack to the tear is reliably prevented.

Further, since the content of the fiber 9 in the column base portion 11 and the discharge port column 8, which are the buried portions of the fiber 9, was set to 0.1 to 2% by weight, the mechanical properties during the initial molten steel injection were increased. The refractory does not separate from the column base region 11 or the discharge port column 8 due to a strong impact.
Further, since the diameter of the fiber body 9 is 0.5 to 2 mm, the workability for embedding the fiber body 9 in the refractory raw material 2a in the manufacturing process of the immersion nozzle 1 as described above is good, and the fiber The degree of bonding between the body 9 and the refractory 2a is strong, so that the refractory 2a does not peel off from the columnar portion base region 11 or the discharge port columnar portion 8.

[0031]

EXAMPLE In order to evaluate the degree of reinforcement of a refractory by burying a fiber body, the cross-sectional shape of alumina-graphite as a refractory raw material in which the fiber body was buried by changing the type, diameter, burying position and content of the fiber body A rectangular parallelepiped sample having a size of 25 mm × 25 mm and a length of 150 mm was prepared.

The bending strength (bonding strength) of the fiber body and the refractory raw material was measured for these samples by a test method as shown in FIG. The test results are shown in Tables 2 to 4.

When the type of the fiber body was changed, the results of the fiber body measurements shown in Table 1 are shown in Table 1.
In Example 1, the bending strength was 9.8 MPa at room temperature and 140
In Example 2, the bending strength was 9.5 MPa at room temperature and 7.9 MPa at 1400 ° C., whereas in Comparative Example 1 using stainless steel as a fiber body, it was 10.0 MPa at room temperature in Example 2. Although the bending strength at room temperature of 5.0 MPa at 1400 ° C. is improved, the bending strength is not reinforced at 1400 ° C. where the immersion nozzle is actually used.

[0034]

[Table 1]

Table 5 shows the properties of the used fiber body-A and the used fiber body-B.

When the diameter of the fiber body was changed Table 2 shows the measurement results obtained by changing the diameter of the fiber body under the conditions shown in Table 2.

In Examples 1, 3, and 4 in which the diameter of the fiber body is in the range of 0.5 to 2 mm, the room temperature, 1400
Although the sample shows good bending strength at both temperatures, Comparative Example 2 in which the diameter of the fiber body is 0.1 mm is 6.9 MPa and 14
The bending strength at 4.8 MPa at 00 ° C. could not be reinforced, and the fiber body was filled into the refractory in a twisted state.

In Comparative Example 3 in which the fiber body had a diameter of 2.5 mm, the refractory peeled off before the measurement, and the measurement could not be performed.

[0039]

[Table 2]

When the installation position of the end of the fiber body is changed Table 3 shows the measurement results obtained by changing the installation position of the fiber body under the conditions shown in Table 3.

[0041]

[Table 3]

Embodiments 1 and 2 where the installation position of the end is 20 mm
All of Example 5 of 5 mm showed good bending strength,
In Comparative Example 4 where the installation position was 0 mm, the bending strength was 6.
9MPa, 4.8MPa at 1400 ° C, installation position 15
In Comparative Example 5 mm, the flexural strength was 7.0 MPa at room temperature,
At 1400 ° C. and 5.0 MPa, the effect of reinforcement by the fiber body was not sufficiently obtained.

When the amount of the fiber body was changed Table 4 shows the results obtained by performing the measurement while changing the amount of the fiber body under the conditions shown in Table 4.

[0044]

[Table 4]

In Comparative Example 6 in which the amount of the fiber body was 0.05% by weight, the flexural strength was 6.9 MPa at room temperature, 1400 ° C.
In Comparative Example 7 where the bending strength was 4.7 MPa and the amount of the fiber body was 2.1% by weight, the bending strength was 7.2 MPa and 1400 at room temperature.
In Comparative Example 8 in which 5.8 MPa at ℃ and the amount of the fiber body was 2.5% by weight, the flexural strength was 5.0 MPa at room temperature, 140 MPa.
At 0 ° C., 4.2 MPa, the effect of reinforcement by the fiber body was not sufficiently obtained.

[0046]

[Table 5]

[0047]

According to the immersion nozzle for continuous casting according to the present invention, a fiber body made of an inorganic material having a predetermined chemical composition and a diameter is disposed in a refractory at a predetermined position near a discharge port by a predetermined length. Since the fiber body is buried so as to be parallel to the direction, there is no deterioration in the strength due to oxidation of the fiber body, preventing the nozzle body from being broken, and a continuous casting immersion nozzle capable of sufficiently obtaining the strength near the discharge port and a method of manufacturing the same. Can be provided.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a continuous casting immersion nozzle according to the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG. 1;

FIG. 3 is a conceptual diagram illustrating a method for manufacturing a continuous casting immersion nozzle according to the present invention.

FIG. 4 is an explanatory diagram of a measurement method for testing a refractory in which a fiber body is embedded.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Immersion nozzle for continuous casting 1a Molded body 2 Nozzle body 2a Refractory 3 Molten steel channel 4 Bottom part 5 Inlet 6 Discharge port 7 Side part 8 Discharge port columnar part 9 Fiber body 10 Inner end part 11 Column base part area 12 End Part 13 Mandrel 14 Opening 15 Rubber mold 16 Part 17 Other part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Chitoshi Oya No.1, Minamifuji, Ogakie-cho, Kariya-shi, Aichi Pref. Toshiba Ceramics Corporation Kariya Works

Claims (7)

[Claims] A chemical composition of Al ₂ O ₃ and a chemical composition of SiO ₂
The fiber body made of an inorganic material having a total of 80% by weight or more is separated from the inner end of the discharge port provided in the nozzle body by 20 mm or more in the opening direction of the nozzle body as a starting point. A continuous casting immersion nozzle characterized by being extended in the longitudinal direction of the nozzle body and buried in a refractory forming a discharge port columnar portion adjacent to the nozzle. 2. The immersion nozzle for continuous casting according to claim 1, wherein the content of the fiber body in an embedded portion of the fiber body is 0.1 to 2% by weight. 3. The fiber body has a diameter of 0.5 to 2 m.
3. The immersion nozzle for continuous casting according to claim 1, wherein m is m. 4. A rubber mold having a mandrel and an opening is prepared, a part of the rubber mold is filled with a refractory material from the opening, and an inorganic material is filled in the rubber mold not filled with the refractory material. The refractory material is filled so that the fiber body is buried, and the refractory material filled in the rubber mold is pressed.Then, the molded body of the immersion nozzle for continuous casting is removed. A method for producing a continuous casting immersion nozzle, characterized in that a formed body is cut, a part of the formed body is cut off together with a fiber body, a discharge port is provided, and the formed body is fired. 5. The fiber body has a chemical composition of Al ₂ O _3.
And a fiber body made of an inorganic material having a total of 80% by weight or more of the chemical composition SiO ₂ and the starting point at a position separated from the inner end of the discharge port provided in the nozzle body by 20 mm or more in the opening direction of the nozzle body. 5. The method for producing a continuous casting immersion nozzle according to claim 4, wherein the immersion nozzle is extended in the longitudinal direction of the nozzle body and buried in a refractory forming a discharge port columnar portion adjacent to a side of the discharge port. 6. The method for producing a continuous casting immersion nozzle according to claim 4, wherein the content of the fiber body in the embedded portion of the fiber body is 0.1 to 2% by weight. 7. The fiber body has a diameter of 0.5 to 2 m.
7. The method for producing a continuous casting immersion nozzle according to claim 4, wherein m is m.