JPH10328793A - Inclusion removal method in tundish for continuous casting - Google Patents

Abstract

(57) [Problem] To remove inclusions inexpensively and efficiently in a tundish for continuous casting. SOLUTION: In a continuous casting tundish 1 in which molten steel 3 injected from a ladle 2 into a molten steel injection portion 5 is relayed to a mold 4 from a tundish outlet 6, a center between the molten steel injection portion and the tundish outlet is provided. The protruding lengths ω and ω ′ from the side walls are in the range of 5% to 50% of the molten steel storage width W of the tundish on both sides of the tundish near the position, and 10
With the baffle 7 having a thickness of 0 mm or more, the molten steel retention amount V in the tundish is set in the range of 30 to 100 tons, and the value obtained by dividing the molten steel retention amount in the tundish by the molten steel passage amount Q per minute is 10 to 20. The amount of molten steel retained in the tundish or the amount of molten steel passing therethrough is controlled so as to be in the range of

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing inclusions in a tundish for continuous casting, which can efficiently remove nonmetallic inclusions in molten steel injected into a tundish.

[0002]

2. Description of the Related Art Non-metallic inclusions (hereinafter, referred to as "inclusions") in molten steel cause defects such as surface flaws in a final product, and must be removed as much as possible from the molten steel. . Therefore, the technology for reducing inclusions is an important technology for obtaining high-quality slabs by the continuous casting method.
Various countermeasures have been implemented, as seen in flow control by a magnetic field in a mold.

However, in recent operation modes in which the slab drawing speed is increased in order to improve productivity, there is a limit in separating and removing inclusions in a mold, and furthermore, the quality required in recent years is reduced. Taking account of the stricter requirements, it is extremely important to improve the cleanliness of molten steel before supplying it into a mold as a measure to reduce inclusions. Therefore, various measures for reducing inclusions in tundish have been proposed.

For example, Japanese Unexamined Patent Publication No. 6-7904 (hereinafter referred to as "prior art 1") discloses a method of blowing an inert gas into molten steel in a tundish to separate and remove inclusions by gas bubbles. Japanese Patent Application Laid-Open No. Hei 7-132353 (hereinafter referred to as "prior art 2") provides three weirs in a tundish and separates inclusions by these weirs.
Japanese Unexamined Patent Application Publication No. 7-132354 (hereinafter referred to as “prior art 3”) discloses a method for removing inclusions by forming the bottom surface of a tundish with a deep unevenness in an injection portion and an outflow portion. A method of separating and removing is disclosed.

[0005]

However, in the prior art 1, although the effect of reducing inclusions due to gas bubbles can be expected, the gas blowing device can usually be arranged only in a part of the tundish, and the fireproofing for performing gas blowing is difficult. Compared to the cost of goods and equipment, and the increased manufacturing costs due to the maintenance and maintenance costs for stable gas injection,
The effect of reducing inclusions is not as expected.

In the prior art 2, the effect of reducing inclusions can be expected because the occurrence of a circulating flow region of molten steel, which will be described later, can be prevented by the weir. In addition, when tundishes are continuously reused without any repairs with the aim of reducing tundish costs while hot, the weirs cannot be set up manually, and special installation equipment is required. Costs are significantly increased. In addition, the weir is likely to collapse, and its reliability is low as a measure for reducing inclusions.

In the prior art 3, since the bottom surface of the tundish is formed to have a highly irregular shape, a circulating flow region of the molten steel described later is unlikely to occur, and the molten steel flow in the tundish has a flow pattern in which inclusions easily float and separate. However, in actual operation, there is a problem with the treatment of residual molten steel in the concave shape of the injection part at the end of casting, a problem with the construction of tundish refractories, and a problem of molten steel caused by a large contact area between molten steel and the refractory. In view of the problem of heat loss, etc., it is not always excellent as a measure for reducing inclusions when judged comprehensively.

As described above, the conventional method of removing inclusions in a tundish is not efficient because the expected effect cannot be obtained as compared with the increase in manufacturing cost.

[0009] On the other hand, the present inventors have compared and examined the slab quality and the casting conditions in an actual machine, and confirmed that measures conventionally considered to improve the effect of removing inclusions are not always effective. That is, the concept of the inclusion removal in the conventional tundish is based on the idea that the amount of molten steel retained in the tundish (hereinafter referred to as “the retained amount of molten steel in the tundish”) is defined as the amount of molten steel supplied from the tundish to the mold per unit time. The average residence time obtained by dividing by the amount (hereinafter, referred to as “amount of molten steel passing”) is extended by increasing the capacity of the tundish, and the floating time of the inclusions is secured and removed. However, in an actual machine, the average residence time and the quality are not necessarily in a proportional relationship.

Therefore, the flow of molten steel in the tundish was investigated by numerical analysis, and as a result, the following events were found.

1. The flow of molten steel in the tundish is caused by the inertial force of the injection flow that falls from the ladle by gravity, the convection caused by the temperature difference between the molten steel immediately after pouring from the ladle and the molten steel remaining in the tundish, and the tundish. The flow resulting from the supply flow to the mold at the outlet is formed in a mutually and complexly related manner.

2. A circulating flow region, a so-called dead water region, exists in the tundish, and the dead water region is more likely to occur as a large-capacity tundish. The area expands.

3. Since the dead water area is a stagnant area,
The injected molten steel is discharged from the tundish outlet without passing through the dead water area. Therefore, the generation of the dead water region decreases the actual residence time of the molten steel in the tundish (hereinafter, referred to as “actual residence time”), and hinders floating and separation of inclusions.

4. The actual residence time is shorter than the average residence time due to the occurrence of dead water areas.

[0015] 5. In order to improve the removal efficiency of inclusions in the tundish, the dead water area is reduced and the effective retention amount (effective retention amount is the amount of molten steel in the tundish excluding the amount of molten steel in the dead water area from the retained amount of molten steel in the tundish. It is important to increase).

The present invention has been made on the basis of the above-described findings. It is an object of the present invention to increase the effective residence time, extend the actual residence time of molten steel, and efficiently and efficiently remove inclusions at low cost. To provide a method for removing inclusions in a tundish.

[0017]

A method for removing inclusions in a tundish for continuous casting according to the present invention is to provide a tundish for continuous casting in which molten steel injected from a ladle into a molten steel injection portion is relayed to a mold from an outlet of the tundish. At
On both sides of the tundish near the center position between the molten steel injection portion and the tundish outlet, a baffle plate having a protruding length from the side wall in the range of 5% to 50% of the molten steel storage width of the tundish and 100 mm or more is provided. At the same time, the amount of retained steel in the tundish is set in the range of 30 to 100 tons, and the value obtained by dividing the retained amount of molten steel in the tundish by the amount of molten steel passing per minute is in the range of 10 to 20. It is characterized by controlling the amount of retained molten steel or the amount of molten steel passing therethrough.

Numerical analysis of the three-dimensional molten steel flow in the tundish using the Navier-Stokes equation,
The flow pattern of molten steel in the tundish was investigated. or,
Numerical analysis of inclusions in molten steel injected into a tundish was also performed, and the flotation efficiency of inclusions was also investigated. The numerical analysis was performed under the condition that the same amount of molten steel as the amount of molten steel passed was injected into the tundish and the amount of retained molten steel in the tundish was kept constant.

FIGS. 2 to 6 schematically show flow patterns of molten steel in a tundish obtained by numerical analysis. In these figures, 1 is a tundish, 3 is molten steel, 5 is a molten steel injection portion, 6 is a tundish outlet, 7 is a baffle plate, 8
Is a long nozzle, 12 is a dead water area, 13 is an adjoining flow, 14
Is a circulating flow.

FIG. 2 is a view schematically showing the flow pattern of molten steel in the central longitudinal section of the tundish obtained by numerical analysis. FIG. 2 shows the flow pattern of molten steel under the condition that the amount of molten steel passing through is appropriate for the amount of retained molten steel in the tundish.

When the capacity of the tundish 1 is increased to increase the amount of retained molten steel in the tundish, the problem is that the dead water region 12 increases. This dead water area 12
Is an inert molten steel 3, so the actual residence time can be shortened, but has no effect of extending it, and
It causes the temperature of the molten steel 3 to drop. As a result of numerical analysis, it was found that the cause of the occurrence of the dead water region was as follows.

The molten steel 3 in the tundish 1 is cooled by heat conduction from the refractory of the tundish and radiant heat transfer on the surface of the molten steel in the tundish. There is always a temperature difference between the molten steel 3 and the molten steel 3 staying in the tundish, and the temperature difference causes a density difference in the molten steel 3. Therefore, the molten steel 3 immediately after being injected into the tundish 1 receives buoyancy. Incidentally, the molten steel 3 immediately after being injected is usually 5 ° C. to 10 ° C. higher than the retained molten steel 3.

The molten steel 3 injected from the ladle via the long nozzle 8 collides with the bottom of the tundish 1 (this collision position is defined as a "molten steel injection section 5"), and then the gravity from the ladle. An attempt is made to flow in the horizontal direction toward the tundish outlet 6 by the inertia force caused by the drop. However, because of the above buoyancy, the molten steel 3 flows toward the tundish outlet 6 while rising, and
In the vicinity, it descends toward the tundish outlet 6 and is supplied from the tundish outlet 6 into the mold. At that time, since the molten steel 3 is a viscous fluid, the accompanying flow 13 is formed due to the viscosity. This means that more molten steel 3 than is supplied to the mold forms a flow toward the tundish outlet 6. However, since only a required amount flows out at the tundish outlet 6, most of the formed accompanying flow 13 cannot flow out, and becomes a circulating flow 14 that turns around in the direction of the molten steel injection section 5 and returns. Then, a dead water region 12 is generated in a range surrounded by the circulation flow 14 at the bottom of the tundish 1.

The results of analyzing the effect of the amount of molten steel passing on the formation of the dead water region 12 are as follows.

FIG. 3 is a diagram schematically showing a molten steel flow pattern in the central longitudinal section of the tundish obtained by numerical analysis under the condition that the amount of molten steel passing through is relatively smaller than the amount of retained molten steel in the tundish. is there. In this case, since the injection flow rate from the ladle is small, after colliding with the molten steel injection section 5, the bottom of the tundish 1 is horizontally moved toward the tundish outlet 6 by the inertial force due to gravity drop from the ladle. The flow to be caused to flow is weak, so that the injected molten steel 3 rises to the surface side of the molten steel 3 due to the buoyancy caused by the molten steel temperature difference. Furthermore, the flow which tends to flow in the horizontal direction toward the tundish outlet 6 collides with the circulating flow 14 flowing from the tundish outlet 6 toward the molten steel injection section 5 and is attenuated. A dead water region 12 which is enlarged in the portion occurs.

FIG. 4 is a diagram schematically showing a molten steel flow pattern in a central longitudinal section of a tundish obtained by numerical analysis under the condition that the amount of molten steel passing through is relatively large. In this case, the influence of the buoyancy is small because the heat removal in the tundish 1 is relatively small, and the inertial force of the injection flow in the horizontal direction toward the tundish outlet 6 is large, so that it collides with the molten steel injection part 5. The molten steel flow becomes a flow toward the tundish outlet 6 near the bottom of the tundish 1 as it is, and as a result, a dead water region 12 is generated on the surface side of the molten steel 3. This dead water area 12 is relatively small.

As described above, when the amount of molten steel passing through the tundish is too small relative to the amount of retained molten steel in the tundish, the dead water region 1
2, the actual residence time is short because the effective residence time is small, and when the molten steel passage is too large, the dead water region 12 is small, but the actual residence time is short because the molten steel passage is large. Become. That is, it can be seen that there is an appropriate amount of molten steel passing according to the amount of molten steel retained in the tundish.

From the results of the investigation of the molten steel flow pattern and the efficiency of flotation separation of inclusions, the dead water region 12 is small and the actual residence time can be ensured. Therefore, the molten steel flow pattern shown in FIG. I understood. Furthermore, when the value obtained by dividing the retained amount of molten steel in the tundish by the amount of molten steel passing per minute was in the range of 10 to 20, it was found that the molten steel flow pattern in the tundish was as shown in FIG. If the division value is less than 10, the amount of molten steel passing through is too small, and if it exceeds 20, it becomes too large.

However, even when the amount of molten steel passing through the tundish is appropriate with respect to the amount of molten steel retained in the tundish, as shown in FIG. After colliding with the portion 5, the temperature of the molten steel is lowered by the cooling by the tundish side wall, so that a flow toward the tundish outlet 6, that is, a so-called short-circuit flow s, is generated with little influence of buoyancy. FIG. 5 is a diagram schematically showing a molten steel flow pattern in a vertical section near the tundish side wall under the condition that the amount of molten steel passing through the tundish is retained with respect to the amount of retained molten steel in the tundish. The molten steel flow p at the center is also shown for comparison. Since the short-circuit flow s stays in the tundish 1 for a short time, the floating time of the inclusions is short, so that the inclusions in the short-circuit flow s flow into the mold.

In the present invention, as shown in FIG. 6, a baffle plate 7 is provided on both sides of the tundish near the central position between the molten steel injection part 5 and the tundish outlet 6 in a direction perpendicular to the molten steel flow. Prevent the generation of stream s. By providing the baffle plate 7, since the molten steel flow near the tundish wall flows around the baffle plate 7 as shown in FIG. 6, the short-circuit flow s is reduced. FIG. 6 is a diagram schematically showing the flow of molten steel in a tundish in a flat cross section.

If the length of the baffle plate 7 protruding from the side wall of the tundish 1 is less than 5% of the molten steel storage width of the tundish 1, the molten steel flow does not change, and the molten steel storage width of the tundish 1 is 50%. %, The molten steel flow is throttled, a high-speed flow is locally generated, a circulating flow 14 is formed downstream of the baffle plate 7, and the dead water region 12 is generated, thereby preventing the inclusion from floating. On the other hand, unless the projecting length of the baffle plate 7 from the side wall of the tundish 1 is at least 100 mm or more, the molten steel flow does not change and the short circuit flow s cannot be prevented.

Further, in the present invention, the retained amount of molten steel in the tundish needs to be in the range of 30 to 100 tons. If the amount of retained steel in the tundish is less than 30 tons,
This is because the absolute amount of molten steel is small, and the heat loss to the molten steel surface in the tundish and the tundish refractory increases, which is disadvantageous due to the floating property of inclusions. This is because the furnace volume is too large compared to the furnace volume, and the refractory cost increases, which is not practical.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings.
FIG. 1 is a schematic view of a tundish for continuous casting to which the present invention is applied, (a) is a front sectional view, and (b) is a side sectional view.

A ladle 2 is disposed above a cuboid tundish 1 having an inner surface made of a refractory, and molten steel 3 in the ladle 2 has a long nozzle 8 installed at the bottom of the ladle 2. Through the tundish 1 into the molten steel injection section 5. The poured molten steel 3 stays in the tundish 1 with the molten steel accommodation depth being H, the molten steel accommodation width being W, the molten steel accommodation length being L, and the molten steel staying amount in the tundish being V. At that time, the retained amount of molten steel (V) in the tundish is 3
It is necessary to determine the molten steel storage depth (H), the molten steel storage width (W), and the molten steel storage length (L) so as to be in the range of 0 to 100 tons.

Tundish 1 on the opposite side of molten steel injection section 5
A tundish outlet 6 is installed at the bottom of the
The molten steel 3 injected into the tundish 1 is supplied from the tundish outlet 6 into the mold 4 via the immersion nozzle 9 connected to the tundish outlet 6 with the molten steel passing amount per minute being Q. Molten steel 3 supplied in mold 4
Is cooled and solidified in the mold 4 to form a slab 10. At this time, the molten steel injection amount (Q ') per minute from the ladle 2 is controlled to be substantially equal to the molten steel passage amount (Q) so that the molten steel retention amount (V) in the tundish becomes a constant value. Control.

On both side walls of the tundish 1 near the central position between the molten steel injection part 5 and the tundish outlet 6, there are provided baffle plates 7 made of refractory whose projecting lengths from the side walls are ω and ω '. 7a is arranged. The protrusion length ω and the protrusion length ω ′ are
It is not necessary to make the protruding length of the left and right baffle plates 7 and 7a equal to any value within the range of 5% to 50% of the molten steel storage width (W) of the tundish and 100 mm or more. The depth of the baffle plates 7 and 7a may be greater than or equal to the molten steel accommodation depth (H). Further, the baffle plates 7 and 7a are not limited to rectangles, but may be trapezoids. In the case of a trapezoid, the maximum value of the protrusion length from the side wall is 50% or less of the molten steel storage width (W) of the tundish, and the minimum value of the protrusion length from the side wall is 5% of the molten steel storage width (W). It is sufficient if it is at least 100 mm.

The position of the tundish 1 in the molten steel injecting section 5 and the tundish outlet 6 in the direction of the molten steel storage length of the tundish 1 with respect to the molten steel storage length (L) is from the short side wall 11, 11a of each tundish 1. Is preferably within L / 5. This is because when the distance from the short side wall 11, 11a exceeds L / 5, the distance between the molten steel injection part 5 and the short side wall 11 and the distance between the tundish outlet 6 and the short side wall 11a are reduced. This is because a dead water region may be generated in between.

During the casting, the molten steel retained in the tundish (V) divided by the molten steel passing per minute (Q) is divided into 10 to 20 and preferably 12 to 16 so that the molten steel stays in the tundish. The amount of molten steel retained in the dish (V) or the amount of molten steel per minute (Q) is controlled. The range in which the divided value is from 12 to 16 is, as described later,
This is because the best performance is obtained.

Although the shape of the tundish 1 shown in FIG. 1 is a rectangular parallelepiped, the present invention can be applied to a case where the cross section is trapezoidal. In that case, the molten steel storage width (W)
The weighted average may be determined at the place where the baffle plate 7 is installed. In FIG. 1, the baffle plates 7 are arranged to face each other, but the installation locations are the molten steel injection part 5 and the tundish outlet 6.
In the vicinity of the central position between the baffles 7, the baffle plate 7 does not need to be opposed. Further, although the tundish 1 shown in FIG. 1 is a single strand, it is needless to say that the tundish 1 can be similarly applied to a two-strand in which a molten steel injection portion 5 is provided at the center of the tundish 1 in the molten steel accommodation length direction. Absent.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention was carried out using a rectangular parallelepiped tundish shown in FIG. The used tundish had a molten steel storage depth (H) and a molten steel storage width (W) of 1.5 m, a molten steel storage length (L) of 4.9 m, and a retained amount of molten steel in the tundish of 77 tons. A baffle plate having a protruding length from the side wall of 200 mm, a depth of 1.7 m, and a thickness of 150 mm was installed on both side walls of the tundish substantially at the center in the molten steel storage length direction. Further, the molten steel injection part was set at a position of 0.8 m from the side wall of the tundish short side, and the tundish outlet was set at a position of 0.6 m from the side wall of the short side of the tundish. And low carbon Al killed steel, thickness 250mm,
It was cast in a single strand with a slab size of 1850 mm in width.

The slab drawing speed was 1.0 m / min.
4 m / min, 1.8 m / min, and 2.2 m / mi
n conditions. Converting the amount of molten steel passing per minute from the slab pulling rate assuming a slab specific gravity of 7.85 gives 3.63 tons, 5.08 tons, 6.54 tons, and 7.99 tons, respectively. The values obtained by dividing the amount of retained molten steel by the amount of molten steel passing per minute were 21.2, 15.2, 11.8, and 9.6, respectively, and the slab drawing speeds were 1.4 m / min and 1. 8m /
The case of min is a casting condition within the scope of the present invention.

Further, in order to confirm the effect of the baffle plate, casting was performed without setting up the baffle plate and setting other conditions to the same conditions as above.

The slab cast under these conditions was rolled into a thin steel sheet, and the thin steel sheet was examined for surface defects due to inclusions. FIG. 7 shows the result. In this survey, the quality evaluation is indicated by a quality index, and the quality index is indicated by a larger value as the number of surface defects due to inclusions is smaller. As shown in FIG. 7, the slab drawing speed within the scope of the present invention is 1.4 m / min (Example) and 1.8 m / min.
/ Min (Example), the quality evaluation was good, and particularly, when the slab drawing speed was 1.4 m / min, the quality index was 12, which was good. On the other hand, when the slab drawing speed which is out of the range of the present invention is 1.0
In the case of m / min (comparative example) and 2.2 m / min (comparative example), the quality index was low, about 3 to 4, and the quality evaluation was inferior. Further, even when no baffle plate is installed, the slab drawing speed is 1.4 m / min and 1.8 m / m.
At the time of “in”, the quality index was 8 to 10 to improve the quality, and showed the same quality tendency as when the baffle plate was installed. However, by installing the baffle plate, about 2
0% quality index improved.

In a tundish having a baffle plate, casting is performed under various conditions including molten steel retention and molten steel passage in the tundish including the above, and the obtained slab is rolled into a thin steel plate to be interposed in the thin steel plate. The quality was evaluated by investigating surface defects due to the objects. FIG. 8 shows the results obtained by summarizing the values obtained by dividing the amount of molten steel retained in the tundish by the amount of molten steel passing on the horizontal axis and the quality index on the vertical axis, and summarizing the relationship between the ranges of the present invention and comparative examples. is there. As shown in FIG.
The scope of the present invention is good when the quality index is higher than 5, and even within the scope of the present invention, especially when the division value is 1
In the range of 2 to 16, the quality index was stably high and the best.

FIG. 9 shows that in a tundish with a baffle plate, the slab withdrawal speed is set to 1.0 m / min (the molten steel passing amount per minute is 3.6 when replacing the ladle during continuous casting).
3 tons) and the steady state of 1.4 m / m
FIG. 4 is a diagram showing a comparison of the change of the quality index by changing the amount of molten steel retained in a tundish with a slab drawing speed of in (the molten steel passing amount per minute is 5.08 tons). . The numbers in the figure are values obtained by dividing the retained amount of molten steel in the tundish by the amount of molten steel passing therethrough. As shown in FIG. 9, when the slab drawing speed was 1.4 m / min, the quality was the best with the retained amount of molten steel in the tundish being 77 tons, but the slab drawing speed was 1.0 m / min. In the case of (1), the best quality result was obtained when the retained amount of molten steel in the tundish was reduced from the steady state to 56 tons. As described above, when the casting speed is changed, the stagnation amount of the molten steel in the tundish is controlled in an appropriate range each time, so that a good slab with stable quality can be manufactured.

By installing the baffle in this way, the inclusions can be efficiently removed without deteriorating the maintainability as in a weir installed at the bottom of the tundish.

[0047]

According to the present invention, baffle plates are provided on both side walls of the tundish, and the amount of molten steel retained in the tundish and the amount of molten steel passing therethrough are controlled to be within an appropriate range. Without taking measures to reduce inclusions
Inclusion removal efficiency can be increased, and as a result, a high-quality cast piece with few inclusions can be stably manufactured at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic view of a tundish for continuous casting to which the present invention is applied, (a) is a front sectional view, and (b) is a side sectional view.

FIG. 2 is a view schematically showing a molten steel flow pattern in a central vertical section of a tundish under a condition in which the amount of molten steel passing through obtained by numerical analysis is appropriate.

FIG. 3 is a diagram schematically showing a flow pattern of molten steel in a tundish center longitudinal section under a condition where the amount of molten steel passing through is small, obtained by numerical analysis.

FIG. 4 is a view schematically showing a molten steel flow pattern in a tundish center longitudinal section under a condition in which the amount of molten steel passing through is too large, obtained by numerical analysis.

FIG. 5 is a view schematically showing a molten steel flow pattern in a vertical section near a tundish side wall under a condition in which the amount of molten steel passing through obtained by numerical analysis is appropriate.

FIG. 6 is a diagram schematically showing a molten steel flow in a tundish in a cross section when a baffle plate is installed.

FIG. 7 is a diagram showing the effect of slab drawing speed on slab quality with and without baffle plate, with the amount of molten steel retained in the tundish constant.

FIG. 8 is a diagram summarizing the effects on the quality of a value obtained by dividing the retained amount of molten steel in the tundish by the amount of molten steel passed through.

FIG. 9 is a view showing that an appropriate molten steel retention amount in a tundish changes by changing a slab drawing speed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tundish 2 Ladle 3 Molten steel 4 Mold 5 Molten steel pouring part 6 Tundish outlet 7 Baffle plate 8 Long nozzle 9 Immersion nozzle 10 Cast piece 11 Short side wall

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kentaro Mori 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Hiroshi Shimizu 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Sun Honko Co., Ltd.

Claims (1)

[Claims] 1. A tundish for continuous casting in which molten steel injected from a ladle into a molten steel injection part is relayed to a mold from a tundish outlet, and a tundish near a central position between the molten steel injection part and the tundish outlet. On both side walls,
The protruding length from the side wall is 5 of the tundish molten steel storage width.
% To 50% and a baffle plate of 100 mm or more was provided, and the retained amount of molten steel in the tundish was set in the range of 30 to 100 tons, and the retained amount of molten steel in the tundish was divided by the amount of molten steel per minute. A method for removing inclusions in a tundish for continuous casting, comprising controlling the amount of molten steel retained in a tundish or the amount of molten steel passing therethrough such that the value falls within a range of 10 to 20.