Tundish for continuous casting, method for continuous casting of steel, and gas supply device

Abstract

Provided is a tundish for continuous casting capable of improving the cleanliness of molten steel. The tundish for continuous casting is provided with a storage part for storing supplied molten steel. The storage unit has one or more molten steel outlets through which the molten steel flows out, and a gas supply unit which is disposed on the upstream side of the molten steel from the one or more molten steel outlets and supplies an inert gas to a space surrounded by the storage unit. The gas supply part is formed in a box shape with a bottom part and a wall part; the gas supply unit includes a porous portion in which a plurality of pores are formed as a whole, a support portion which supports the porous portion and is provided on the wall portion of the gas supply unit, and a pipe which is provided on the wall portion of the gas supply unit between the support portion and the bottom portion of the gas supply unit and discharges the inert gas.

Description

Technical Field

[0001] The present invention relates to a tundish for continuous casting, a continuous casting method for steel and a gas supply device. Background Art

[0002] The production of steel materials is carried out as follows. Specifically, molten steel supplied from a ladle to a tundish is supplied to a mold and cast into a slab. The slab is then formed into a desired shape through processes such as rolling to become steel materials.

[0003] Inclusions such as Al2O3 in molten steel can cause defects in steel materials, so they are preferably separated and removed from the molten steel before casting. Specifically, in a tundish, inclusions contained in the molten steel are floated and separated.

[0004] Such cleaning technology for removing inclusions from molten steel is essential for producing high-quality steel materials, and therefore its improvement is sought. Conventionally, a weir is installed to separate the steel receiving area where the molten steel is supplied to the tundish from the quasi-static area where the molten steel is discharged from the discharge port provided at the bottom.

[0005] For example, the weir described in Patent Document 1 has multiple holes formed on the bottom side of the tundish, extending from the surface on the steel receiving area to the surface on the steel quasi-stationary area. Therefore, the weir restricts the movement of inclusions lighter than the molten steel. Furthermore, the molten steel flows from the steel receiving area to the steel quasi-stationary area through the holes in the weir.

[0006] Furthermore, in Patent Document 2, in addition to the weir installed in the tundish as described in Patent Document 1, ribs protruding upward from the bottom of the tundish are provided on the side of the quasi-static steel zone. Therefore, even if inclusions migrate from the weir holes toward the quasi-static steel zone, their direction of movement is redirected upward by the ribs. This allows inclusions to float even on the steel receiving zone.

[0007] Furthermore, in Patent Document 3, in addition to installing a weir in the tundish as described in Patent Document 1, an inert gas is supplied upward from the bottom of the tundish toward the quasi-static steel region. This allows inclusions to float due to the inert gas even if they migrate from the weir opening toward the quasi-static steel region.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 53-6231

[0011] Patent Document 2: Japanese Patent Application Laid-Open No. 10-216909

[0012] Patent Document 3: Japanese Patent Application Laid-Open No. 2011-143449 Summary of the Invention

[0013] Problems to be solved by the invention

[0014] Even when a weir is provided in the tundish as in Patent Document 1, inclusions may pass through the holes of the weir. If inclusions are discharged from the outlet of the molten steel, there is a possibility that defects may be caused in the steel material.

[0015] In addition, regarding the use of ribs to float inclusions as in Patent Document 2, there is room for improvement in the desire to more effectively float inclusions. Furthermore, at the end of casting, steel mesh remains between the ribs and the weir, which increases the cost of handling the remaining steel.

[0016] When using an inert gas to float inclusions, as in Patent Document 3, there is the problem of having to increase the volume fraction of the inert gas in the molten steel to achieve a sufficient floating effect. Increasing the inert gas flow rate to increase the volume fraction of the inert gas in the molten steel can cause inclusions on the surface of the molten steel, namely, tundish slag, to be drawn into the molten steel by the inert gas. If tundish slag is drawn into the molten steel, the molten steel may be contaminated, potentially causing defects in the steel material.

[0017] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a tundish for continuous casting, a continuous steel casting method, and a gas supply device capable of improving the cleanliness of molten steel.

[0018] Means for solving problems

[0019] In order to solve the above-mentioned problems, the present invention has the following features.

[0020] [1] A tundish for continuous casting, comprising a receiving portion for storing supplied molten steel, wherein:

[0021] The housing portion includes one or more molten steel outflow ports for allowing the molten steel to flow out, and a gas supply portion that is arranged upstream of the one or more molten steel outflow ports and supplies an inert gas to a space surrounded by the housing portion.

[0022] The gas supply unit is formed in a box shape having a bottom and a wall, and includes:

[0023] The porous portion has a plurality of pores formed throughout.

[0024] a supporting portion that supports the porous portion and is provided on the wall portion of the gas supply portion; and

[0025] A pipe is provided in the wall portion of the gas supply portion between the support portion and the bottom portion of the gas supply portion and discharges the inert gas.

[0026] [2] The tundish for continuous casting according to [1], wherein:

[0027] The gas supply portion includes a receiving chamber surrounded by the porous portion, the support portion, the wall portion of the gas supply portion, and the bottom portion of the gas supply portion.

[0028] The pipe is provided on the wall portion surrounding the gas supply portion of the accommodation chamber.

[0029] [3] The tundish for continuous casting according to [1] or [2], wherein:

[0030] The housing portion includes one or more weirs that partition the space surrounded by the housing portion, and the gas supply portion is provided adjacent to the weirs.

[0031] [4] The tundish for continuous casting according to any one of [1] to [3], wherein

[0032] The gas supply unit includes an adjustment unit that adjusts a flow rate of the inert gas supplied from the pipe.

[0033] [5] The tundish for continuous casting according to any one of [1] to [4], wherein:

[0034] The pipe is arranged along the wall of the housing portion and is covered with a fire-resistant covering material.

[0035] [6] A method for continuous casting of steel, using the tundish for continuous casting described in any one of [1] to [5], wherein:

[0036] The continuous casting method of steel includes a step of injecting an inert gas at a flow rate satisfying the following formula (1).

[0037] 0.2≤R≤10.0 (1)

[0038] R: Flow rate of inert gas per unit area of ​​the porous portion [NL / (s×m 2 )]

[0039] [7] A gas supply device is provided in a tundish for continuous casting and supplies an inert gas, wherein:

[0040] The gas supply device is formed in a box shape having a bottom and a wall, and includes:

[0041] The porous portion has a plurality of pores formed throughout.

[0042] a supporting portion supporting the porous portion and disposed on the wall portion; and

[0043] A pipe is provided in the wall portion between the support portion and the bottom portion and discharges the inert gas.

[0044] [8] The gas supply device according to [7], wherein:

[0045] The gas supply device includes a receiving chamber surrounded by the porous portion, the support portion, the wall portion, and the bottom portion.

[0046] The pipe is provided on the wall portion surrounding the accommodation chamber.

[0047] [9] The gas supply device according to [7] or [8], wherein:

[0048] The gas supply device includes an adjustment unit that adjusts a flow rate of the inert gas supplied from the pipe.

[0049] Effects of the Invention

[0050] According to the present invention, by supplying inert gas through the porous portion, fine inert gas bubbles can be supplied to the molten steel injection area. As a result, the volume fraction of the inert gas in the molten steel can be increased, effectively floating inclusions contained in the molten steel poured from the ladle into the tundish. This improves the cleanliness of the molten steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is an explanatory diagram showing the structure of a tundish for continuous casting.

[0052] Figure 2 This is an explanatory diagram showing a side view of a tundish for continuous casting.

[0053] Figure 3 It shows Figure 1 An explanatory diagram of the structure of the gas supply unit.

[0054] Figure 4 yes Figure 3 A top view of the gas supply unit.

[0055] Figure 5 This is an explanatory diagram showing a configuration in which piping is provided.

[0056] Figure 6 This is an explanatory diagram showing another embodiment in which piping is provided.

[0057] Figure 7 It is a graph showing the relationship between the gas flow rate per unit area and the number density of inclusions.

[0058] Figure 8 It is a graph showing the number density of inclusions in the conventional example and the present invention. DETAILED DESCRIPTION

[0059] Figure 1 This is an explanatory diagram showing the structure of a tundish for continuous casting. Figure 2 This is an explanatory diagram showing the side of a tundish for continuous casting. Figure 1 As shown, the tundish 100 for continuous casting is arranged between a ladle (not shown) storing molten steel MS and a mold 40 for cooling the molten steel MS.

[0060] like Figure 1 and 2 As shown, a tundish for continuous casting (hereinafter referred to as a tundish) 100 includes a box-shaped container 10 with an open top and a bottom. In this embodiment, the container 10 of the tundish 100 for continuous casting is shaped like an inverted frustum, with the upper bottom being longer than the lower bottom. Therefore, the container 10 has a space 10a for storing molten steel MS.

[0061] The housing 10 includes a molten steel injection area AR1 that receives molten steel MS from the ladle nozzle N1. The molten steel injection area AR1 is formed along the axis AX of the nozzle N1. In other words, the molten steel injection area AR1 extends from the tip of the nozzle N1 along the axis AX of the nozzle N1. The molten steel injection area AR1 extends in the circumferential direction of the axis AX of the nozzle N1.

[0062] The receiving portion 10 has one or more molten steel outflow ports 11 for allowing the molten steel MS to flow out to the mold. Figure 1 As shown, in this embodiment, the molten steel outflow port 11 is formed on one end side and the other end side in the left-right direction of the bottom 12 of the accommodating portion 10 .

[0063] The housing 10 includes one or more weirs 20 that partition the space 10a enclosed by the housing 10. In this embodiment, the weirs 20 are provided to partition the molten steel injection area AR1 from the molten steel outflow port 11. Two weirs 20 are provided to partition the molten steel outflow ports 11 provided in the left-right direction of the housing 10 from the molten steel injection area AR1.

[0064] The weir 20 is formed in a plate shape, for example, and has a through hole 21 on the bottom 12 side of the housing portion 10 , which penetrates from the surface on the molten steel pouring area AR1 side to the surface on the molten steel outlet 11 side.

[0065] The housing 10 includes a gas supply unit 30, which is arranged upstream of the molten steel MS relative to the molten steel outlet 11 and supplies an inert gas to the space 10a surrounded by the housing 10. In other words, the gas supply unit 30 functions as a gas supply device for supplying the inert gas to the housing 10. The gas supply unit 30 is formed in a hollow box shape with a bottom.

[0066] like Figure 2 As shown, the gas supply unit 30 includes a wall 31 and a bottom 32 provided at the lower end of the wall 31. In other words, the wall 31 is provided upright from the bottom 32. The bottom 32 is provided facing the bottom 12 of the housing 10 and in contact with the bottom 12.

[0067] The gas supply unit 30 is preferably provided in an area of ​​the container 10 where the flow velocity of the molten steel MS is relatively high. Examples of such an area include the vicinity of the weir 20. In the present embodiment, the gas supply unit 30 is provided adjacent to the weir 20 in the direction of movement of the molten steel MS. The gas supply unit 30 may be provided upstream of the weir 20 in the direction of movement of the molten steel MS, or may be provided downstream of the weir 20 in the direction of movement of the molten steel MS. In the present embodiment, the gas supply unit 30 is provided downstream of the weir 20 in the direction of movement of the molten steel MS.

[0068] The gas supply unit 30 supplies the inert gas toward the upper portion of the space 10a of the housing unit 10. In the present embodiment, the gas supply unit 30 supplies the inert gas toward the direction along the axis AX of the nozzle N1.

[0069] Each molten steel outlet 11 is provided with a nozzle N2 that connects the tundish 100 and the mold 40. Molten steel MS is supplied from the molten steel outlet 11 through the nozzle N2 to the mold 40. The molten steel MS is cooled in the mold 40 to form a cast strand 50.

[0070] Figure 3 It is an explanatory diagram showing the structure of the gas supply unit 30 . Figure 4 FIG shows the upper surface of the gas supply portion 30. Figure 3 and 4 As shown, the gas supply unit 30 is formed in a hollow box shape having a wall portion 31 and a bottom portion 32 .

[0071] The gas supply unit 30 includes a porous portion 35 having a plurality of fine pores 35a formed throughout and a support portion 36 supporting the porous portion 35. The gas supply unit 30 also includes a pipe 37 provided in the wall portion 31 between the porous portion 35 and the bottom portion 32 and ejecting an inert gas.

[0072] The porous portion 35 is formed by a ceramic refractory. As such a refractory, for example, one or more refractory particles selected from refractory inorganic particles such as alumina and silica can be mixed and sintered. It should be noted that, as a refractory, a refractory mainly composed of alumina is particularly preferred.

[0073] The porous portion 35 can be produced by using spherical particles mainly composed of alumina as aggregate and firing them at 1600° C. or higher. The porous portion 35 can be produced, for example, by casting a dense castable refractory.

[0074] By using spherical particles as aggregates, the pores 35a of the porous portion 35 can be formed. The pores 35a of the porous portion 35 are not particularly limited, but for example, the average pore diameter measured by mercury intrusion porosimetry can be formed to be 10 to 40 μm. By forming the pores 35a in this way, the bubbles of the inert gas supplied from the porous portion 35 can be made small. That is, when the inert gas is supplied using the conventional method, the diameter of the bubbles is about 100 μm, but by supplying the inert gas in this way, the diameter of the bubbles can be reduced to about 1 / 10 to 1 / 20 of the conventional diameter. In addition, by making the pores 25a of the porous portion 25 10 to 40 μm, the flow rate of the inert gas can be appropriately controlled.

[0075] The shape of the porous portion 35 is not particularly limited, but in this embodiment, it is formed into a plate shape. Figure 4 As shown, it is formed into a rectangle when viewed from above.

[0076] The support portion 36 is formed of a ceramic refractory. As such a refractory, for example, one or more refractory particles selected from refractory inorganic particles such as alumina and silica can be mixed and sintered. It should be noted that, as a refractory, a refractory mainly composed of alumina is particularly preferred.

[0077] The support portion 36 is formed into a frame shape to support the edge of the bottom of the porous portion 35. The shape of the support portion 36 is not particularly limited, but in this embodiment, it is formed into a rectangular frame shape when viewed from above. The support portion 36 is provided on the wall portion 31. The support portion 36 is fixed by, for example, fitting into a fitting recess (not shown) formed in the wall portion 31.

[0078] The gas supply unit 30 includes a housing chamber 38 surrounded by a porous portion 35, a support portion 36, a wall portion 31, and a bottom portion 32. A pipe 37 is provided in the wall portion 31 surrounding the housing chamber 38.

[0079] It is preferable that the pipe 37 has fire resistance. Figure 5 FIG. 2 shows a solution in which a pipe 27 is provided. Figure 5 As shown, the pipe 27 is arranged along the wall 13 of the housing 10. In addition, the pipe 27 is covered by a fire-resistant coating material 60. As the coating material 60, for example, a prefabricated refractory can be cited. In addition, as the coating material 60, a prefabricated refractory and a repair material can also be used in combination. Figure 5In the example shown, a precast refractory 61 is provided as the cladding material 60 provided on the edge side of the housing portion 10. In addition, a patching material 62 is provided as the cladding material 60 provided on the bottom 12 side of the tundish 100.

[0080] Alternatively, a pipe cover may be used as the covering material 60 . Figure 6 Another solution is shown in which a pipe 27 is provided. Figure 6 In the example shown, replace Figure 5 The prefabricated refractory material described in the example shown is used as the pipe cover 63. In addition, a plurality of pipe covers 63 may be used. Figure 6 In the illustrated example, four pipe covers 63 are connected along the axial direction of the pipe 27 .

[0081] By configuring the pipe 27 in this manner, refractory installation can be facilitated. Furthermore, the maintainability of the pipe 27 can be improved compared to inserting the pipe 27 through the bottom 12 of the tundish 100. Furthermore, since no processing is required to insert the pipe 27 through the bottom 12 of the tundish 100, leakage of molten steel from the bottom 12 can be suppressed.

[0082] The pipe 37 is preferably provided with an adjustment unit 39 for adjusting the flow rate of the inert gas. A valve can be used as the adjustment unit 39. The adjustment unit 39 may be manually operated or its opening may be adjusted by a control unit (not shown).

[0083] The inert gas supplied from the pipe 37 is introduced into the storage chamber 38. When the inert gas is introduced into the storage chamber 38, the pressure of the inert gas is uniformly applied to the surface of the porous portion 35 facing the bottom 32. As a result, the inert gas is supplied from the storage chamber 38 through the pores 35a of the porous portion 35 into the space 10a.

[0084] By supplying the inert gas in this manner, the gas supply unit 30 can suppress variations in the inert gas supply pattern. The inert gas is not particularly limited, but examples thereof include Ar, N 2 , and CO 2 .

[0085] It should be noted that in this embodiment, the inert gas is supplied from the storage chamber 38 to the porous portion 35. However, the inert gas may be supplied to the porous portion 35 without passing through the storage chamber 38. For example, an attachment (not shown) that can cover the surface of the bottom 32 side of the porous portion 35 may be attached to the piping 37.

[0086] In addition, in this embodiment, an example in which the weir 20 is provided in the tundish 100 is described. However, even when the tundish 100 is not provided with the weir 20, the same effects as those of this embodiment can be achieved by providing the gas supply unit 30 in this manner. For example, when the tundish 100 is not provided with the weir 20, it is preferable to provide the gas supply unit 30 in an area where the flow velocity of the molten steel MS is faster than in other areas. An example of an area with a faster flow velocity of the molten steel MS is the molten steel injection area AR1.

[0087] In the continuous steel casting method, molten steel MS is first supplied from a nozzle N1 connected to a ladle (not shown) to a tundish 100. Next, inclusions contained in the molten steel MS are removed from the tundish 100. Finally, the molten steel MS is caused to flow from the molten steel outflow port 11 of the tundish 100 into the mold 40. Finally, the molten steel MS is cooled in the mold 40 to produce a cast strand.

[0088] The step of removing inclusions contained in the molten steel MS in the tundish 100 includes a step of injecting an inert gas at a flow rate satisfying the following formula (1).

[0089] 0.2≤R≤10.0 (1)

[0090] R: Flow rate of inert gas per unit area of ​​the porous portion [NL / (s×m 2 )]

[0091] The gas flow rate (R) per unit area of ​​the porous portion 35 is preferably 0.2 to 10.0 NL / (s×m 2 ) is supplied from the gas supply unit 30, more preferably at a rate of 2.0 to 10.0 NL / (s×m 2 It should be noted that the gas flow rate (R) per unit area of ​​the porous portion 35 can be adjusted by the adjustment unit 39.

[0092] The gas flow rate (R) per unit area of ​​the porous portion 35 is 0.2 NL / (s×m 2 ) or more, it is possible to promote the floating of inclusions in the molten steel MS.

[0093] The gas flow rate (R) per unit area passing through the porous portion 35 is 10.0 NL / (s×m 2 ) or less, the entrapment of tundish slag can be prevented.

[0094] As described above, according to the tundish 100 of the present invention, by supplying the inert gas through the porous portion 35, fine bubbles of the inert gas can be supplied to the space 10a of the housing portion 10. As a result, the volume ratio of the inert gas in the molten steel MS can be increased, and inclusions contained in the molten steel poured from the ladle into the tundish 100 can be efficiently floated.

[0095] In particular, the flow rate of molten steel MS near the weir 20 is faster than that in other areas. Therefore, by supplying inert gas from a position adjacent to the weir 20 toward the space 10a of the containment section 10, the frequency of contact between inert gas bubbles can be increased. As a result, the inert gas bubbles can be made smaller. This further increases the volume fraction of inert gas in the molten steel MS. Furthermore, by placing the gas supply section 30 in the high-flow area of ​​the tundish 100, the inert gas bubbles can be made finer than conventional bubbles. Fine bubbles can further enhance the buoyancy of inclusions. Consequently, inclusion entrapment in the molten steel can be suppressed. Furthermore, the location of the gas supply section 30 can be easily changed. Therefore, by changing the location of the porous section 35 according to the flow conditions of the molten steel in the tundish 100, inclusion buoyancy can be further promoted and inclusion entrapment can be further suppressed.

[0096] Therefore, the tundish 100 of the present invention can enhance the effect of floating inclusions. Furthermore, inclusions can be floated with a lower flow rate of inert gas, thereby suppressing slag entrapment in the tundish 100. Thus, the tundish 100 of the present invention can efficiently float inclusions and suppress the entrapment of molten steel inclusions, thereby enabling the production of high-cleanliness steel.

[0097] Example

[0098] (Test Example 1: Inclusion Measurement Test)

[0099] (Sample)

[0100] 300 tons of molten steel that had been subjected to oxygen blowing and RH vacuum degassing in a converter was used and supplied from a ladle to a tundish.

[0101] (Continuous Casting)

[0102] Continuous casting was performed using Ar as the inert gas blown from the weir. Specifically, multiple experiments were conducted by varying the flow rate (R) of the inert gas per unit area of ​​the porous portion. (R: flow rate of the inert gas per unit area of ​​the porous portion [NL / (s×m 2 )])

[0103] (Determination of the number of inclusions)

[0104] The number of inclusions in the slabs produced by continuous casting was measured by ultrasonic testing. Inclusions larger than 10 μm were measured. 2 The number of inclusions is calculated as the density.

[0105] exist Figure 7 The relationship between the flow rate (R) of the inert gas per unit area of ​​the porous portion and the density of inclusions in the slab is shown in FIG. Figure 7 As shown, when the flow rate (R) of the inert gas is lower than 0.2, the density of inclusions is higher than that under other conditions.

[0106] When the inert gas flow rate (R) was between 0.2 and 10.0, the inclusion density was lower than under other conditions. When the inert gas flow rate (R) exceeded 10.0, the inclusion density was lower than when no inert gas was supplied. Furthermore, under these conditions, the inclusion density was higher than when the inert gas flow rate (R) was 0.2 or less.

[0107] It is believed that when the inert gas flow rate (R) is lower than 0.2, the inclusion floating effect in the tundish cannot be fully achieved under this condition. Therefore, it is believed that the density of inclusions is high under this condition.

[0108] Furthermore, it is believed that when the inert gas flow rate (R) exceeds 10.0, the tundish slag (inclusions) is drawn into the molten steel by the inert gas. Therefore, under these conditions, the density of inclusions is believed to be higher than when the inert gas flow rate (R) is between 0.2 and 10.0.

[0109] (Test Example 2: Inclusion Measurement Test)

[0110] (Sample)

[0111] The same molten steel as that in Test Example 1 was used.

[0112] (Continuous Casting)

[0113] Continuous casting was performed using the tundishes of Conventional Example (1) and Inventive Examples (Inventive Examples 1 to 9).

[0114] Furthermore, Ar was used as the inert gas blown into each tundish. Specifically, in Conventional Example 1, the inert gas was supplied toward the space of the housing portion without providing a gas supply device in the tundish.

[0115] In addition, in the inventive examples, a gas supply device was provided, and inert gas was supplied from the gas supply device into the space of the housing. Inventive examples (Inventive Examples 1-9), the flow rate of the inert gas supplied from the gas supply device at the weir was varied. The inert gas flow rates for each inventive example are shown in Table 1.

[0116]

[0117] R: Flow rate of inert gas per unit area of ​​the porous portion [NL / (s×m 2 )]

[0118] (Determination of the number of inclusions)

[0119] The same method as in Test Example 1 was used.

[0120] Figure 8 The density of inclusions in Conventional Example 1 and Invention Examples 1 to 9 is shown. Figure 8 As shown, it can be seen that the density of inclusions in the slabs of Inventions 1 to 9 is significantly lower than that of Conventional Example 1. In particular, Inventions 1 to 6 have an inert gas flow rate (R) of 0.2 to 10.0, and thus achieve better results than Inventions 7 to 9.

[0121] Description of Reference Numerals

[0122] 100 Tundish

[0123] 10 Containment Department

[0124] 10a Space

[0125] 11 Molten steel outlet

[0126] 20 Weir

[0127] 30 Gas supply unit (gas supply device)

[0128] 31 Wall

[0129] 32 bottom

[0130] 35 porous part

[0131] 36 Support

[0132] 37 Piping

[0133] 38 Containment Chamber

[0134] 39 Adjustment Unit

[0135] AR1 Molten steel injection area.

Claims

1. A tundish for continuous casting, comprising a receiving portion for storing supplied molten steel, wherein: The receiving portion includes one or more molten steel outflow ports for allowing the molten steel to flow out, and a gas supply portion that is disposed upstream of the one or more molten steel outflow ports and supplies an inert gas to a space surrounded by the receiving portion. The gas supply unit is formed into a box shape having a bottom and a wall, and includes: The porous portion has a plurality of pores formed throughout. a supporting portion that supports the porous portion and is provided on the wall portion of the gas supply portion; and A pipe is provided in the wall portion of the gas supply portion between the support portion and the bottom portion of the gas supply portion and discharges the inert gas.

2. The tundish for continuous casting according to claim 1, wherein: The gas supply portion includes a receiving chamber surrounded by the porous portion, the support portion, the wall portion of the gas supply portion, and the bottom portion of the gas supply portion. The pipe is provided on the wall portion of the gas supply portion surrounding the accommodation chamber.

3. The tundish for continuous casting according to claim 1 or 2, wherein: The housing portion has one or more weirs that partition the space surrounded by the housing portion, and the gas supply portion is provided adjacent to the weirs.

4. The tundish for continuous casting according to claim 1 or 2, wherein: The gas supply unit includes an adjustment unit that adjusts a flow rate of the inert gas supplied from the pipe.

5. The tundish for continuous casting according to claim 3, wherein: The gas supply unit includes an adjustment unit that adjusts a flow rate of the inert gas supplied from the pipe.

6. The tundish for continuous casting according to claim 1 or 2, wherein: The pipe is arranged along the wall of the housing portion and is covered with a fire-resistant covering material.

7. The tundish for continuous casting according to claim 3, wherein: The pipe is arranged along the wall of the housing portion and is covered with a fire-resistant covering material.

8. The tundish for continuous casting according to claim 4, wherein: The pipe is arranged along the wall of the housing portion and is covered with a fire-resistant covering material.

9. The tundish for continuous casting according to claim 5, wherein: The pipe is arranged along the wall of the housing portion and is covered with a fire-resistant covering material.

10. A method for continuous casting of steel, using the tundish for continuous casting according to claim 1 or 2, wherein: The continuous casting method of steel includes a step of blowing an inert gas at a flow rate satisfying the following formula (1), 0.2≤R≤10.0 (1) R: flow rate of inert gas per unit area of ​​the porous portion [NL / (s×m 2 )].

11. A method for continuous casting of steel, using the tundish for continuous casting according to claim 3, wherein: The continuous casting method of steel includes a step of blowing an inert gas at a flow rate satisfying the following formula (1), 0.2≤R≤10.0 (1) R: flow rate of inert gas per unit area of ​​the porous portion [NL / (s×m 2 )].

12. A method for continuous casting of steel, using the tundish for continuous casting according to claim 4, wherein: The continuous casting method of steel includes a step of blowing an inert gas at a flow rate satisfying the following formula (1), 0.2≤R≤10.0 (1) R: flow rate of inert gas per unit area of ​​the porous portion [NL / (s×m 2 )].

13. A method for continuous casting of steel, using the tundish for continuous casting according to claim 5, wherein: The continuous casting method of steel includes a step of blowing an inert gas at a flow rate satisfying the following formula (1), 0.2≤R≤10.0 (1) R: flow rate of inert gas per unit area of ​​the porous portion [NL / (s×m 2 )].

14. A method for continuous casting of steel, using the tundish for continuous casting according to claim 6, wherein: The continuous casting method of steel includes a step of blowing an inert gas at a flow rate satisfying the following formula (1), 0.2≤R≤10.0 (1) R: flow rate of inert gas per unit area of ​​the porous portion [NL / (s×m 2 )].

15. A method for continuous casting of steel, using the tundish for continuous casting according to claim 7, wherein: The continuous casting method of steel includes a step of blowing an inert gas at a flow rate satisfying the following formula (1), 0.2≤R≤10.0 (1) R: flow rate of inert gas per unit area of ​​the porous portion [NL / (s×m 2 )].

16. A method for continuous casting of steel, using the tundish for continuous casting according to claim 8, wherein: The continuous casting method of steel includes a step of blowing an inert gas at a flow rate satisfying the following formula (1), 0.2≤R≤10.0 (1) R: flow rate of inert gas per unit area of ​​the porous portion [NL / (s×m 2 )].

17. A method for continuous casting of steel, using the tundish for continuous casting according to claim 9, wherein: The continuous casting method of steel includes a step of blowing an inert gas at a flow rate satisfying the following formula (1), 0.2≤R≤10.0 (1) R: flow rate of inert gas per unit area of ​​the porous portion [NL / (s×m 2 )].

18. A gas supply device, arranged in a tundish for continuous casting and supplying an inert gas, wherein: The gas supply device is formed in a box shape having a bottom and a wall, and includes: The porous portion has a plurality of pores formed throughout. a supporting portion supporting the porous portion and disposed on the wall portion; and A pipe is provided in the wall portion between the support portion and the bottom portion and discharges the inert gas.

19. The gas supply device according to claim 18, wherein: The gas supply device includes a receiving chamber surrounded by the porous portion, the support portion, the wall portion, and the bottom portion. The pipe is provided on the wall portion surrounding the accommodation chamber.

20. The gas supply device according to claim 18 or 19, wherein: The gas supply device includes an adjustment unit that adjusts a flow rate of the inert gas supplied from the pipe.

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