JPH08174163A - Continuous casting method using static magnetic field - Google Patents

Abstract

PURPOSE: To produce a slab having extremely high quality on the surface and in the inner part by using an immersion nozzle plugged with a metallic plate at the tip opening part and pouring molten steel while applying static magnetic field. CONSTITUTION: At the time of starting the casting, beforehand, the iron plate 13 is abutted on the lower surface of the immersion nozzle 11 and supported by using a jig 14. A tundish and a mold are aligned and the immersion nozzle 11 is set to a prescribed position in the mold and electric current is conducted to an electromagnet of a static magnetic field generator 16 beforehand arranged at the back surface of side wall on the long sides of the mold to generate the static magnetic field in the mold. Here, a dummy bar head 17 is arranged at the lower part in the mold, and the tundish and the immersion nozzle 11 are communicated at both inner parts to start the casting. At the time of starting the casting, the molten steel is spouted from the side spouting holes of the immersion nozzle 11 and then, at almost the same time of filling up the prescribed quantity of the molten steel, the iron plate 13 is melted and the lower end of the immersion nozzle 1 is opened. The molten steel lowers the speed at the sectional part 11a and is spouted from the lower end opening part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous casting method using a static magnetic field in which molten metal injected from a tundish into a casting mold for continuous casting is braked by a static magnetic field for continuous casting.

[0002]

2. Description of the Related Art Conventionally, in a continuous casting process, molten metal (hereinafter referred to as molten steel) after refining is poured from a ladle into a tundish, and non-metallic inclusions such as slag and tundish flux are included in the tundish. Most of them are floated and separated, and molten steel is injected from the tundish into a continuous casting mold using a dipping nozzle to form a slab.

In such a casting process, as shown in FIGS. 8 and 9, the upper surface of molten steel in the mold 2 (hereinafter, referred to as
The molten metal surface) is covered with a mold powder 8 for lubrication of the mold 2 and the solidified portion 9 of the slab, prevention of temperature drop of molten steel, prevention of reoxidation, adsorption of non-metallic inclusions in molten steel, and the like. .

The immersion nozzle for injecting the molten steel into the mold is a refractory cylinder, and the tip is immersed in the molten steel in the mold to inject the molten steel. A porous nozzle is generally used as the immersion nozzle. As shown in FIG. 8A, the porous nozzle 1 has a plurality of discharge holes 5 formed laterally to the tip of a bottomed cylinder.
The molten steel is discharged from these discharge holes 5 in a substantially horizontal direction.

In order to start casting using such a porous nozzle 1, first, a dummy bar head is arranged in the lower part of the mold 2 and a plurality of discharge holes 5 are formed on the dummy bar head.
After the molten steel is injected from the above, the tip of the porous nozzle 1 is immersed in the molten steel and the molten steel in the mold reaches a predetermined amount, the dummy bar is moved downward and pulled out.

When the porous nozzle 1 as described above is immersed in the molten steel in the mold 2 for casting, as shown in FIG. 8 (a), the discharge flow of the molten steel faces the side wall of the mold 2 and the front surface of the side wall. A downflow and an upflow are generated in the, and the upflow promotes the floating of nonmetallic inclusions. Further, when the porous nozzle 1 is used, it is possible to satisfactorily start casting by the dummy bar start using the dummy bar head described above.

[0007]

However, in such a porous nozzle 1, alumina A tends to adhere to the inner surface of the nozzle during continuous casting of aluminum-killed steel, and
As shown in FIG. 8 (b), the flow path of molten steel becomes narrower as the casting time elapses. In particular, when the alumina A adheres to the discharge holes 5, uneven flow occurs and the upward flow becomes faster. The upward flow having the increased velocity swirls in the vicinity of the lower surface of the mold powder 8 to increase the surface velocity of the molten steel. Therefore, when alumina A adheres to the discharge holes 5, not only cannot the desired amount of molten steel be injected into the mold 2, but also the drift causes a turbulence in the molten steel flow in the mold 2, resulting in an upward flow. The swirling flow increases the amount of the mold powder 8a to be entrained and disturbs the molten metal surface, resulting in a large decrease in the molten steel temperature in the mold 2. As an attempt to prevent the discharge hole of the porous nozzle from being narrowed, Ca that forms a low melting point compound with alumina
Attempts have been made such as a casting method using an immersion nozzle containing O and a method of introducing Ca into a tundish or a ladle. However, a sufficient effect has not been obtained by these methods.

As a method for avoiding the above problem, a method of frequently replacing the porous nozzle can be considered, but the cost of the porous nozzle increases and the unsteady work increases, which is practically impossible. Is. For this reason, normally, when injecting molten steel into the mold, an inert gas such as argon is injected into the immersion nozzle to prevent the formation of oxides.

However, in the method of injecting an inert gas, during high speed high speed casting, as shown in FIG. 9, it becomes difficult to float the inert gas B in the mold 2, and the bubbles B are trapped inside the slab. Therefore, there is a problem that a blister defect occurs after cold rolling.

Therefore, the blowing amount of the inert gas is
It is set to a small amount so that the oxide does not adhere to the discharge holes of the porous nozzle. However, even if the amount of the inert gas is reduced, it is not possible to completely prevent defects due to the inert gas.

As another method for avoiding the narrowing of the discharge hole of the above-mentioned porous nozzle, a straight nozzle having an open tip (a dipping nozzle having a simple straight pipe shape)
There is a method of using. JP-A-62-3857 discloses a method of injecting molten steel into a mold by using a straight nozzle and applying a static magnetic field to a discharge flow forming region in the mold.

According to the method of applying the static magnetic field to the molten steel discharge flow forming region of the straight nozzle, the molten steel is discharged downward from the open nozzle tip, so that the molten steel surface flow in the mold is slow and the fluctuation amount of the molten metal surface is large. Becomes smaller. Therefore, the entrainment of mold powder does not occur, the temperature drop of the molten steel is suppressed, the level of the molten metal surface can be accurately controlled, and the drift of the molten steel flow due to the oxide adhering to the discharge holes does not occur. Therefore, it is possible to significantly improve the surface and internal quality of the slab.

However, in the casting method using the straight nozzle, since the discharge flow directly collides with the central portion of the dummy bar head at the start of casting (dummy bar start), there is a delay in solidification and a re-solidification at the joint between the dummy bar head and the slab portion. Dissolution may occur and the dummy bar head may be separated from the slab. Therefore, there is a problem that the straight nozzle cannot be used at the start of casting (dummy bar start).

The present invention has been made in view of the above circumstances, and an object thereof is to provide a continuous casting method capable of greatly improving the surface and internal quality of a slab.

[0015]

In order to achieve the above object, the continuous casting method according to the present invention comprises a static magnetic field generated by a static magnetic field generator disposed on the back surface of the opposite side wall of the continuous casting mold. In order to perform continuous casting by applying braking to the discharge flow of the molten metal injected from the tundish into the mold through the immersion nozzle, prior to the start of the casting of the molten metal, an open portion is formed at the tip. A metal plate for closing at least the tip opening portion is attached to the tip of the immersion nozzle formed of a substantially cylindrical body having a side discharge hole on the side surface of the immersion nozzle, and the tundish is formed at the start of the casting. The molten metal inside is discharged from the side discharge holes formed in the immersion nozzle and injected into the mold, and after a predetermined time elapses, the metal plate is melted by the molten metal to obtain the immersion nozzle. The end open part is opened, and the molten metal in the tundish is discharged from this open end part to be injected into the mold, and is arranged in the entire long side direction of the mold corresponding to the vicinity of the tip of the immersion nozzle. The static magnetic field generated by the static magnetic field generator is applied to the molten metal discharged into the mold.

Here, it is preferable that the tip of the immersion nozzle is formed with a diverging end portion whose inner surface is divergent toward the tip.

Further, it is preferable that the static magnetic field generators are arranged in a plurality of stages with a gap provided therebetween.

[0018]

According to the continuous casting method of the present invention, a metal plate is attached to the tip of an immersion nozzle having an open tip to close the open portion of the bottom surface and form a side discharge hole. Since molten steel is poured in from the
It is possible to prevent the molten steel from dropping straight into the mold and to start the dummy bar start satisfactorily. After the start of casting, the metal plate is melted by the molten steel, and the molten steel is discharged from the open part of the tip of the dipping nozzle, and the static magnetic field is applied to this discharge flow, so that the molten steel does not penetrate deeply into the mold, Bubbles and non-metallic inclusions float, the surface velocity of the molten steel is slow, and fluctuations in the molten metal surface are extremely small. In addition, since molten steel is discharged straight from the open end, it is difficult for oxides such as alumina to adhere to the inner surface of the immersion nozzle. As a result, the discharge flow does not become uneven. Therefore, it is not always necessary to blow an inert gas to prevent the generation of oxides.

According to the preferred embodiment of the continuous casting method of the present invention, since the immersion nozzle having the divergent portion at the tip portion is used to apply braking to the discharge flow, the flow rate of the molten steel is reduced in the divergent portion and the molten steel is released. Since it is discharged from the part and braking is applied to this discharge flow, the flow does not enter deeply downward and spreads in the horizontal direction, and the flow velocity distribution is quickly uniformized.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The continuous casting method of the present invention will be described below in detail with reference to the preferred embodiments shown in the accompanying drawings.

Prior to the description of the continuous casting method of the present invention, continuous casting equipment preferably used in the continuous casting method of the present invention will be described.

FIGS. 1 to 3 are views showing a state at the start of casting of a part of the continuous casting equipment for carrying out the continuous casting method of the present invention, and FIG. 3 shows immersion at the start of casting. Nozzle 1
1 is a plan view showing the mold 1, the mold 12, and the static magnetic field generator 16, FIG. 1 is a sectional view taken along line AA of FIG. 3, and FIG. 2 is B of FIG.
It is a -B sectional view.

The mold 12 is for forming a slab having a rectangular cross section, and as shown in FIG. 3, it is movable between the opposing long sides 12a, 12a made of copper and these long sides 12a, 12a. Installed opposite copper short sides 12b, 1
2b for cooling the molten steel discharged from the immersion nozzle 11.

The immersion nozzle 11 is a refractory tubular body having an opening at the lower end on the tip and on the side surface near the tip,
This is a so-called straight nozzle, the upper end of which is connected to a tundish (not shown) and the lower end of which is immersed in the molten steel in the mold 12. The lower end has an oval cross section, as shown in FIGS.
The long axis is in the direction of the long side 12a of the mold 12,
The major axis of this elliptical cross section becomes longer as it goes downward. That is, the lower end of the immersion nozzle 11 widens in the direction of the short side 12b of the mold 12 and forms the divergent end 11a. At the lower end of the immersion nozzle 11, as shown in FIG. 2, a notch 15 that constitutes a lateral opening of the present invention is formed at both ends of the mold 12 in the direction of the long side 12a.
a is formed. Further, at the lower end of the immersion nozzle 11, grooves 14a are formed on the outer surface of both ends of the mold 12 in the direction of the short side 12b. A metal plate 30 is attached to the groove 14a.

Before the start of casting, the metal plate 30 is
The immersion nozzle 1 is attached to the lower end of the immersion nozzle 11.
An iron plate 13 for closing the front end of the immersion nozzle 12 for closing the front end open portion of No. 1 and forming a side discharge hole 15 of molten steel by a notch 15a which is a side surface open portion.
And a jig 14 for attaching the iron plate 13. The iron plate 13 is for preventing molten steel from being discharged downward from the open portion of the immersion nozzle 11 at the start of casting, and discharging molten steel only from the side discharge holes 15 formed by the notches 15a. The molten steel starts to melt at the start of casting, and eventually melts in the mold 12 to become molten steel, and the material thereof needs to be the same as the slab to be formed. Casting can be started using other materials, but it is not preferable because the composition of the slab changes. The iron plate 13 is a plate having a shape along the outer periphery of the lower surface of the immersion nozzle 11. That is, it is a substantially elliptical shape in which both ends in the major axis direction of the ellipse are missing. The iron plate 13 has a thickness and a connecting portion with the jig 14 at which molten steel is not melted until a predetermined amount of molten steel is injected into the mold 12, preferably until the notch 15a of the immersion nozzle 11 is immersed. To have. It should be noted that these can be easily determined in advance by heat calculation from conditions such as the staying time of molten steel. Jigs 14 are attached to both ends of the iron plate 13 in the minor axis direction.

The jig 14 is for attaching the iron plate 13 to the immersion nozzle 11, and supports the iron plate 13 by abutting it on the lower surface of the immersion nozzle 11. Even if it is made of the same material as the iron plate 13, it is different. It may be a material. The jig 14 of the illustrated example has a lower end connected to a side end of the iron plate 13, and an upper end bent in the horizontal direction to form a horizontal portion. By fitting this horizontal portion into the groove 14a of the immersion nozzle 11, the jig 14 is locked to the outer surface of the immersion nozzle 11, and the iron plate 13 is supported in contact with the lower surface of the immersion nozzle 11. The jig 14 only needs to have a shape and thickness capable of supporting the iron plate 13 until the molten steel is poured into the mold 12 by a predetermined amount.

The jig 14 and the iron plate 13 may be connected by welding or the like, or the jig 14 may be formed integrally with the iron plate 13, and the lower end of the jig 14 may be connected to the jig 14. It may be bent in the same direction as the upper end to form a horizontal portion, and the iron plate 13 may be placed on the upper surface of the lower end horizontal portion.

A static magnetic field generator 16 is installed on the back surface of the side walls of the long sides 12a, 12a of the mold 12. The static magnetic field generator 16 applies a braking force to the molten steel flow in the mold 12, and is installed at a position corresponding to the entire area of the inner surface of the mold 12 in the direction of the long side 12a, and is sandwiched by the static magnetic field generator 16. A uniform magnetic field is applied to the molten steel. Here, this static magnetic field generator is preferably arranged from the vicinity of the meniscus to the vicinity of the lower end of the mold, but as at least the illustrated example, it corresponds to the discharge flow forming region from the open portion near the lower end of the immersion nozzle 11. It is arranged at the height. The static magnetic field generator 16 has a pair of magnetic poles in which an electromagnet is arranged, and applies a magnetic field perpendicularly to the flow of molten steel in the mold 12. Here, a similar static magnetic field generator is installed with a gap below the static magnetic field generator 16 so that the static magnetic field in the mold 12 has a sufficient strength even in high throughput high speed continuous casting. It may be a static magnetic field generator in stages.

Next, a casting method using the above equipment will be described. In the continuous casting method of the present invention, molten steel is poured from a ladle (not shown) into a tundish (not shown) which is an intermediate container, as in the conventional case.

Before the start of casting, the iron plate 13 is brought into contact with the lower surface of the immersion nozzle 11 and supported by the jig 14. The notch 15a of the immersion nozzle 11 forms the side discharge hole 15 by attaching the iron plate 13 to the immersion nozzle 11. The side discharge holes 15 have the same function as the discharge holes of the conventional porous nozzle.

Then, the tundish (not shown) and the mold 12 are aligned with each other, and the divergent portion 11a of the immersion nozzle 11 connected to the tundish has its major axis in the direction of the short side 12b as shown in FIG. And soaking nozzle 1
The immersion nozzle 11 is installed at a predetermined position in the mold 12 so that the discharge holes 15 on both sides of the nozzle 1 face the short sides 12b and 12b, respectively. Then, an electric current is caused to flow through the electromagnet of the static magnetic field generator 16 installed on the back surface of the side walls of the long sides 12a and 12a of the mold 12 in advance to generate a static magnetic field in the mold 2.

Here, the dummy bar head 17 is arranged in the lower portion of the mold 12 as in the case of starting the casting using the conventional porous nozzle. Then, the inside of the tundish and the inside of the immersion nozzle 11 are communicated with each other, the molten steel is lowered into the inside of the immersion nozzle 11, and casting is started.

The molten steel descending in the immersion nozzle at the start of casting fills the divergent portion 11a at the lower part of the immersion nozzle 11 and, as shown by the arrow in the figure, the side discharge holes 15 of the immersion nozzle 11 are formed. , 15 to the short side 12 of the mold 12
It is discharged toward b and 12b and falls on the dummy bar head 7 in the mold 12.

After the casting is started, when the casting mold 12 is filled with a predetermined amount of molten steel, the metal plate 30 is melted and the lower end of the immersion nozzle 11 is opened almost at the same time. The molten steel that has descended from the tundish has a reduced velocity at the end widening portion 11a and is discharged from the lower end open portion. Then, the discharge flow is subjected to braking by the static magnetic field.

As described above in detail, according to the present invention, as compared with the continuous casting method using the porous nozzle,
Since the surface speed of the molten steel in the mold is slow and the amount of fluctuation of the molten metal surface is small, the entrainment of the mold powder can be prevented, the temperature drop of the molten steel in the mold can be suppressed, and the molten steel level can be controlled accurately. In addition, the discharge flow does not become uneven due to the oxide adhesion. Therefore, it is not necessary to blow the inert gas. Further, since the static magnetic field generator 16 applies braking to the molten steel flow discharged from the open portion of the immersion nozzle 11 having the divergent portion 11a, the downward flow does not enter deeply into the mold, and the flow velocity distribution is made uniform quickly. The floating of bubbles and inclusions is promoted. As a result, slabs with extremely high surface and internal quality can be produced. Further, since the metal plate 30 is attached and the casting is started, one portion of the dummy bar is not melted, but the casting can be started favorably.

(Example) The continuous casting method of the present invention and the conventional method were carried out by using a two-strand continuous casting machine in which two immersion nozzles were connected to a single tundish and molten steel was injected into each mold. Curved casting of ultra-low carbon aluminum killed steel was performed. The casting conditions at this time are shown below. -Casting slab size Thickness: 260 mm Width: 1300 mm-Maximum casting speed of casting slab: 1.2 m / min-Tundish superheat: 30-35 ° C-Lower end position of immersion nozzle: 200 mm below meniscus-Inside of immersion nozzle Blow-in amount of argon gas: 15 NL / min

As a conventional example, the first strand was cast using a conventional porous nozzle. The discharge holes of this porous nozzle are formed in two places at 15 ° downward,
The total area of these discharge holes is 8500 mm ² .

The method of the present invention was applied to the second strand, and a dipping nozzle having an inner diameter of 70 mm and a longitudinal axis of the lower end of 145 mm was used and a static magnetic field generator was used to apply a static magnetic field as follows. I went. Static magnetic field specification 0.27T (1200A) Uniform magnetic field 1300mm width From position 474mm below meniscus to position 690mm below meniscus

The following comparison was made under the casting conditions described above. Fluctuation level of molten metal in the mold The fluctuation amount of molten metal was measured by the vortex flow level type. The results are shown in FIG. The fluctuation amount of the inventive example was 1/2 or less of the fluctuation amount of the conventional example, and the molten metal surface of the inventive example was very stable. Temperature of molten metal in the mold 0.6m / min during the process of increasing casting speed,
The molten metal surface temperature in the mold at 0.8 m / min, 1.0 m / min and the maximum casting speed (1.2 m / min) was measured using a thermocouple. As shown in FIG. 5, at any casting speed, the inventive example was higher by about 10 ° C. than the conventional example. Cold Rolled Coil Quality A slab formed according to the present invention example and the conventional example was cold rolled to form a coil, and surface defects and internal defects of the coil were examined. -1 Coil surface quality Fig. 6 shows the defect occurrence rate on the surface of the cold rolled coil. The surface defect generation amount of the example of the present invention was about 1/5 of that of the conventional example. -2 Coil internal quality Fig. 7 shows the results of evaluating the coil internal quality by the magnetic particle flaw detection method (MT defect). In the present invention example, the number of defects was ½ or less of the number of defects in the conventional example.

As another embodiment of the present invention, casting was carried out without blowing an inert gas such as argon gas into the immersion nozzle. Also in this case, as in the case of blowing the argon gas, it is possible to perform continuous casting with three charges, and the amount of alumina deposited on the inner surface of the immersion nozzle is 1 to 1.
It was about 2 mm, and there was no significant difference from the adhesion amount when the argon gas was blown.

The present invention is not limited to the above embodiment, and the shapes of the immersion nozzle, the metal plate and the like used in the present invention can be appropriately changed. For example, the immersion nozzle has a shape that does not have a notch up to the notch 15a of the immersion nozzle 11, the portion below the notch 15a of the immersion nozzle 11 and the iron plate 13 are integrally formed as a metal plate,
When this metal plate is attached to the immersion nozzle having no notch, the immersion nozzle 11 and the metal plate 30 of the above embodiment may have the same shape as the connected shape.

[0042]

As described in detail above, according to the continuous casting method of the present invention, a metal plate is attached to the tip of a substantially cylindrical immersion nozzle having an opening at the tip, and the tip opening is used as the bottom. Since the side discharge hole is formed by the side opening with the blockage, it is possible to prevent the molten steel from protruding straight down the mold at the start of casting, and the molten steel is concentrated in the center of the dummy bar head. Casting can be started satisfactorily without collision.

Further, since a static magnetic field is generated in the mold to inject the molten steel into the mold from the side discharge holes of the immersion nozzle, the metal plate is melted, and then the molten steel is injected from the open portion at the tip of the immersion nozzle. The surface velocity of the molten steel in the mold is low, the fluctuation of the molten metal surface is very small, the entrainment of mold powder can be prevented, and the quality of the slab to be formed can be improved. Further, since the molten metal surface in the mold is stable, it is possible to precisely control the molten steel level. Further, the temperature drop of the molten steel in the mold is small, and a slab without segregation can be formed.

Further, the oxide is unlikely to adhere to the inner surface of the immersion nozzle, and even if the oxide is adhered to the immersion nozzle, the size of the discharge hole is hardly changed and the discharge flow is not unevenly distributed. Aluminum killed steel can also be continuously cast for a relatively long time. As a result, the nozzles also rise, and the cost of the immersion nozzle can be kept low. Further, it is not necessary to add Ca. Further, when casting aluminum killed steel or the like, it is possible to perform casting without blowing an inert gas. Therefore, the bulging defect caused by the gas of the coil after cold rolling can be significantly reduced.

According to the preferred embodiment of the continuous casting method of the present invention, since the immersion nozzle having the divergent portion at the tip portion is used and braking is applied to the discharge flow, in addition to the above effects, bubbles and inclusions are further added. It can promote levitation. Therefore, it is possible to manufacture slabs with extremely high surface and internal quality.

[Brief description of drawings]

FIG. 1 is a partial front sectional view showing a part of an embodiment of a dipping nozzle and a mold for carrying out a continuous casting method according to the present invention.

FIG. 2 is a partial side cross-sectional view showing the immersion nozzle and the mold shown in FIG.

FIG. 3 is a partially cutaway plan view showing the immersion nozzle and the mold shown in FIG.

FIG. 4 is a graph showing variations in molten metal level in casting in which the method of the present invention and the conventional method are applied.

FIG. 5 is a graph showing a molten metal surface temperature in casting in which the method of the present invention and the conventional method are applied.

FIG. 6 is a graph showing a surface defect mixing rate of a coil formed by a slab formed by applying the method of the present invention and the conventional method.

FIG. 7 is a graph showing the number of internal defects in a coil formed by a slab formed by applying the method of the present invention and the conventional method.

8 (a) and 8 (b) are cross-sectional views showing an example of a dipping nozzle and a mold used in a conventional continuous casting method, showing a state in which no oxide is adhered and a discharge of the dipping nozzle, respectively. It is sectional drawing which shows the state which the oxide adhered to the hole.

FIG. 9 is a sectional view showing an example of a dipping nozzle and a mold used in a conventional continuous casting method.

[Explanation of symbols]

 11 Immersion Nozzle 11a End Spread 12 Mold 30 Metal Plate 15 Side Discharge Hole 16 Static Magnetic Field Generator

Claims (3)

[Claims] 1. A molten metal injected from a tundish into a casting mold through a dipping nozzle by a static magnetic field generated by a static magnetic field generator disposed on the back surface of an opposite side wall of a continuous casting mold. At the time of performing continuous casting by applying braking to the discharge flow, prior to the start of casting of the molten metal, at least the tip open part is closed at the tip of the immersion nozzle formed of a substantially cylindrical body having an open part at the tip. Attach a metal plate to form a side discharge hole on the side surface of the immersion nozzle, and at the start of the pouring, discharge the molten metal in the tundish from the side discharge hole formed in the immersion nozzle. The molten metal melts the metal plate after a predetermined time to open the open end of the immersion nozzle, and the molten gold in the tundish is opened from the open end. While injecting into the mold, the static magnetic field generated by the static magnetic field generator arranged in the entire long side direction of the mold corresponding to the vicinity of the tip of the immersion nozzle is discharged into the mold. A method for continuous casting of steel using a static magnetic field, characterized in that it is applied to molten metal. 2. The continuous casting method according to claim 1, wherein the tip of the immersion nozzle is formed with a diverging end portion whose inner surface is divergent toward the tip. 3. The continuous casting method according to claim 1, wherein the static magnetic field generator is arranged in a plurality of stages with a gap.