Long nozzle capable of blowing argon and method for producing ultra-low carbon steel by adopting long nozzle

Abstract

The invention belongs to the technical field of ferrous metallurgy, and particularly relates to a long nozzle capable of blowing argon and a method for producing ultra-low carbon steel through the long nozzle. The structure of the long nozzle is improved, and a gas guide ring groove is formed in the inner wall of the long nozzle in the horizontal direction; a plurality of vertical air entraining grooves are formed in the inner wall of the bowl part of the long nozzle; and the upper end of the air entraining groove is connected with the air guide ring groove, and the lower end of the air entraining groove is lower than the lower edge of a fireproof sealing gasket arranged on the inner wall of the long nozzle bowl part. And the blown argon is guided to flow towards the lower part of the long nozzle, so that the argon is entrained by the molten steel, argon bubbles are generated in the molten steel, the argon bubbles move downwards along with the molten steel, the argon bubbles are promoted to be broken into finer and dispersed argon bubbles, the removal effect of inclusions in the molten steel is promoted, and the production of high-cleanliness ultra-low carbon steel is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of iron and steel metallurgy, in particular to a long shroud capable of blowing argon and a method for producing ultra-low carbon steel by using the same. Background Art

[0002] Ultra-low carbon steel is often used in deep drawing to produce steel products, which requires good plasticity. The control of inclusions in steel is the focus of ultra-low carbon steel production control. However, ultra-low carbon steel is often produced using the converter steelmaking-RH decarburization refining-continuous casting process, which has a fast production rhythm and short refining time, making it difficult to control inclusions in steel. In actual production, the number of inclusions in ultra-low carbon steel is often controlled through system process optimization, especially the optimization of steelmaking and refining outside the furnace, but it is difficult.

[0003] Some improved argon blowing structures for long shrouds are disclosed in the prior art, but their structures are complex or holes are punched obliquely downward at the air inlet groove to form a ventilation channel, and a ventilation ring is set at the lower end of the ventilation channel, and the ventilation ring is connected to the air permeable layer. It is difficult to punch holes obliquely downward to form a ventilation channel, and the ventilation ring is located at a low position and connected to the air permeable layer, which makes it difficult to control the intake of air above the long shroud, which easily causes secondary oxidation of molten steel. Some literature also introduces research on blowing argon into the long shroud and generating tiny argon bubbles inside the molten steel to promote the removal of inclusions in the molten steel, but most of the research on the argon blowing structure of the long shroud is not clear, or the specific supporting process method parameters are not detailed and comprehensive, or the bubble breaking method and effect are not clear, and the application of argon blowing technology for long shrouds in molten steel production is very rare. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the main purpose of the present invention is to provide a long shroud capable of blowing argon and a method for producing ultra-low carbon steel using the same.

[0005] According to one aspect of the present invention, the present invention provides the following technical solution:

[0006] A long shroud capable of blowing argon has an air guide ring groove arranged horizontally along the inner wall of the long shroud bowl; a plurality of air guide grooves arranged vertically on the inner wall of the long shroud; the upper ends of the air guide grooves are connected to the air guide ring grooves, and the lower ends of the air guide grooves are lower than the lower edges of refractory sealing pads arranged on the inner wall of the long shroud bowl.

[0007] As a preferred solution of the argon-blown long shroud described in the present invention, the width of the air guide ring groove is 5-20 mm, the depth is 5-15 mm, and the cross-section is semicircular, elliptical or rectangular.

[0008] As a preferred solution of the argon-blown long shroud described in the present invention, wherein: the air guide ring groove is connected to the argon blowing channel extending horizontally from the outer side of the long shroud to the inner wall of the long shroud bowl; and a vent hole is opened at the position of the refractory sealing gasket facing the argon blowing channel, and the size of the vent hole is slightly larger than the size of the argon blowing channel, to ensure that part of the argon gas can enter the contact interface between the refractory sealing gasket and the sliding shroud of the ladle through the vent hole, thereby enhancing the protection of the casting effect.

[0009] As a preferred solution of the argon-blown long shroud described in the present invention, the depth of the air inlet groove is 2.0-10.0 mm, the width of the air inlet groove is 2.0-20.0 mm, and the number of the air inlet grooves is 4-8.

[0010] As a preferred solution of the argon-blown shroud described in the present invention, the lower end of the air inlet groove is 3-10 mm below the lower edge of the refractory sealing pad arranged on the inner wall of the shroud bowl.

[0011] As a preferred solution of the argon-blown long shroud described in the present invention, the air inlet grooves are unevenly distributed around the inner wall of the long shroud bowl, and more air inlet grooves are arranged on the side away from the argon blowing channel.

[0012] According to another aspect of the present invention, the present invention provides the following technical solution:

[0013] A method for producing ultra-low carbon steel comprises the following steps:

[0014] S1. Before the continuous casting starts, the above-mentioned long shroud capable of argon blowing is connected to the sliding shroud of the ladle, and a refractory sealing pad is arranged on the inner wall of the bowl of the long shroud capable of argon blowing;

[0015] S2. During the continuous casting process, argon gas is introduced into the long water nozzle through the air guide ring groove and the air guide groove to achieve the production of ultra-low carbon steel.

[0016] As a preferred embodiment of the method for producing ultra-low carbon steel of the present invention, in step S1, the ultra-low carbon steel is deoxidized by aluminum before continuous casting, and the acid-soluble aluminum content in the molten steel is controlled to be (150-750)×10 -6 、Total oxygen content is (20-80)×10 -6 .

[0017] As a preferred embodiment of the method for producing ultra-low carbon steel according to the present invention, in step S2, the argon pressure is (0.2-0.5)×10 6 Pa, the argon flow rate is Q, and Q = a × Q 钢 , where: Q is the argon blowing flow rate, NL / min; Q 钢 is the steel flow rate of the long shroud, t / min; a is the coefficient, and the value range of a is 5-50.

[0018] As a preferred embodiment of the method for producing ultra-low carbon steel described in the present invention, in step S2, the steel throughput of the long shroud is 3-15 t / min.

[0019] As a preferred embodiment of the method for producing ultra-low carbon steel described in the present invention, in step S2, the pressure between the long shroud and the sliding shroud is controlled to be 1000-6000N.

[0020] As a preferred embodiment of the method for producing ultra-low carbon steel of the present invention, the total oxygen content of the ultra-low carbon steel after continuous casting is ≤15×10 -6 .

[0021] The beneficial effects of the present invention are as follows:

[0022] The present invention proposes an argon-blown shroud and a method for producing ultra-low carbon steel using the shroud. The shroud structure is improved, and an air guide ring groove is provided in the horizontal direction along the inner wall of the shroud; a plurality of air guide grooves are provided in the vertical direction on the inner wall of the shroud bowl; the upper end of the air guide groove is connected to the air guide ring groove, and the lower end of the air guide groove is lower than the lower edge of the refractory sealing pad provided on the inner wall of the shroud bowl. The blown argon is guided to flow toward the lower part of the shroud, so that the molten steel rolls up the argon, generating argon bubbles in the molten steel, and the argon bubbles move downward with the molten steel, promoting the argon bubbles to break into smaller and more dispersed argon bubbles, promoting the removal of inclusions in the molten steel, and facilitating the production of ultra-low carbon steel with high cleanliness. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0024] Figure 1 It is a technical principle diagram of the present invention.

[0025] Figure 2 It is a schematic structural diagram of the long water nozzle capable of blowing argon according to the present invention.

[0026] In the figure, 1- ladle, 11- sliding nozzle, 2- tundish, 21- long nozzle, 211- air guide ring groove, 212- air guide groove, 213- refractory sealing pad, 214- argon blowing channel, 215- vent hole.

[0027] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0028] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The present invention provides a long shroud capable of blowing argon and a method for producing ultra-low carbon steel using the same. Figure 1-2 As shown, the argon blowing structure of the long shroud 21 is improved. Figure 1 The enlarged image of point A is Figure 2 The argon-blown shroud described in the foregoing utilizes the high argon blowing pressure of the shroud 21, the negative pressure of the area below the refractory sealing pad 213 provided at the shroud bowl, and the air guide groove 212 to allow most of the argon gas blown into the shroud 21 to be guided to the area below the refractory sealing pad 213 provided at the shroud bowl through the air guide groove 212; the argon gas introduced downwardly reduces the negative pressure in the area below the refractory sealing pad 213 provided at the shroud bowl, reduces the suction of the air above the shroud bowl by the negative pressure in the shroud 21 during the continuous casting process, and inhibits the secondary oxidation of the molten steel; the refractory sealing pad 213 is provided with an air vent 215 at the position opposite to the argon blowing channel 214, and the size of the air vent 215 is slightly larger than the cross-sectional size of the argon blowing channel 214, so as to ensure that part of the argon gas can enter the refractory sealing pad 213 through the air vent 215 The contact interface between the sealing gasket 213 and the sliding nozzle 11 of the ladle enhances the protection of the casting effect; the argon gas introduced downward contacts the ultra-low carbon molten steel flowing rapidly downward in the long nozzle 21, and the molten steel absorbs the argon gas to generate argon bubbles in the molten steel, and the argon bubbles move downward with the molten steel; the ultra-low carbon molten steel forms strong turbulent kinetic energy in the long nozzle 21 and in the injection area near the outlet of the long nozzle 21, and the turbulent ultra-low carbon molten steel shears and crushes the argon bubbles involved in the molten steel, and the aluminum oxide and its composite inclusions in the molten steel also continuously collide and scratch the argon bubbles, further breaking the argon bubbles, and the movement of the inclusions in the molten steel to the bubble surface will also reduce the bubble surface energy, further promoting the argon bubbles to break into smaller argon bubbles, most of which are 80-800 microns in size. The fine dispersed argon bubbles collide with the inclusions in the molten steel and capture the inclusions in the steel, forming a combination of bubbles and inclusions, driving the inclusions in the molten steel to float up and enter the tundish covering agent of the tundish 2, thereby promoting the removal of inclusions in the molten steel; the aluminum oxide inclusions in the ultra-low carbon molten steel are large in number and size, and the aluminum oxide inclusions have a strong tendency to adhere to the argon bubbles, so the bubbles have a good effect of capturing inclusions, thereby achieving efficient removal of inclusions in the ultra-low carbon molten steel. The fine dispersed argon bubbles move with the molten steel, avoiding the exposure of the molten steel caused by the gathering and rising of argon bubbles near the long water nozzle 21, and controlling the secondary oxidation of the molten steel. The method of the present invention can significantly promote the removal of inclusions in ultra-low carbon molten steel in continuous casting production, reduce inclusions in ultra-low carbon molten steel, and improve the cleanliness of ultra-low carbon steel.

[0030] According to one aspect of the present invention, the present invention provides the following technical solution:

[0031] A long shroud capable of blowing argon, with an air guide annular groove 211 provided in the horizontal direction along the inner wall of the bowl of the long shroud 21; a plurality of air guide grooves 212 provided in the vertical direction on the inner wall of the long shroud 21; the upper end of the air guide groove 212 is connected to the air guide annular groove 211, and the lower end of the air guide groove 212 is lower than the lower edge of the refractory sealing pad 213 provided on the inner wall of the bowl of the long shroud. It is ensured that the blown argon gas is guided to the lower side of the area of ​​the refractory sealing pad 213 provided on the inner wall of the bowl of the long shroud, so as to reduce the negative pressure in the area, and inhibit the suction of the molten steel above the long shroud 21 by the molten steel flowing rapidly downward in the long shroud 21 and the secondary oxidation of the molten steel. At the same time, it also helps the refractory sealing pad 213 to seal between the long shroud 21 and the sliding shroud 11, and controls the suction of the air at the upper end of the long shroud 21 by the flow of the molten steel in the long shroud 21.

[0032] Preferably, the width of the air guide ring groove 211 is 5-20 mm, the depth is 5-15 mm, and the cross-section is semicircular, elliptical or rectangular.

[0033] Preferably, the air guide annular groove 211 is connected to an argon blowing channel 214 extending horizontally from the outer side of the long shroud 21 to the inner wall of the long shroud bowl.

[0034] Preferably, the refractory sealing gasket 213 is provided with a vent hole 215 at a position facing the argon blowing channel 214 , and the size of the vent hole 215 is slightly larger than the cross-sectional size of the argon blowing channel 214 .

[0035] Preferably, the depth of the air guide groove 212 is 2.0-10.0 mm, the width of the air guide groove 212 is 2.0-20.0 mm, and the number of the air guide grooves 212 is 4-8.

[0036] Preferably, the lower end of the air guide groove 212 is 3-10 mm below the lower edge of the refractory sealing pad 213 provided on the inner wall of the long water nozzle bowl.

[0037] Preferably, the air inlet grooves 212 are unevenly distributed around the inner wall of the long shroud bowl, and more air inlet grooves 212 are arranged on the side away from the argon blowing channel 214. It is ensured that the argon gas blown into the long shroud 21 is introduced into the lower side of the refractory sealing pad 213 area provided on the inner wall of the long shroud bowl through the air inlet grooves 212 and the sealing effect of the sealing pad;

[0038] According to another aspect of the present invention, the present invention provides the following technical solution:

[0039] A method for producing ultra-low carbon steel comprises the following steps:

[0040] S1. Before the continuous casting starts, the long argon-blowing nozzle 21 is connected to the sliding nozzle 11 of the ladle 1, and a refractory sealing pad 213 is arranged on the inner wall of the bowl of the long argon-blowing nozzle;

[0041] S2. During the continuous casting process, argon gas is introduced into the long water nozzle 21 through the air guide ring groove 212 and the air guide groove 212 to achieve ultra-low carbon steel production.

[0042] Preferably, in step S1, the ultra-low carbon steel is deoxidized by aluminum before continuous casting, and the acid-soluble aluminum content in the molten steel is controlled to be (150-750)×10 -6 、Total oxygen content is (20-80)×10 -6 .

[0043] Preferably, in step S2, the argon pressure is (0.2-0.5)×10 6 Pa, the argon flow rate is Q, and Q = a × Q 钢 , where: Q is the argon blowing flow rate, NL / min; Q 钢 is the steel flow rate of the long nozzle, t / min; a is a coefficient, and the value range of a is 5-50. Ensure that the argon gas blown into the long nozzle 21 is introduced into the lower side of the refractory sealing pad 213 area set on the inner wall of the long nozzle bowl through the air inlet groove 212 to generate a reasonable number of argon bubbles and protect the balance of the casting effect.

[0044] Preferably, in step S2, the steel throughput of the shroud is 3-15 t / min. When the molten steel flows downward into the tundish 2 through the shroud 21, the molten steel in the tundish 2 forms a strong turbulent motion near the shroud 21 and the shroud outlet, and the turbulent molten steel shears and crushes the argon bubbles involved in the molten steel.

[0045] Preferably, in step S2, the pressure between the long nozzle 21 and the sliding nozzle 11 is controlled to be 1000-6000N. To ensure that the long nozzle 21 protects the casting effect, the air above the long nozzle 21 is controlled to be sucked into the long nozzle.

[0046] Preferably, the total oxygen content of the ultra-low carbon steel after continuous casting is ≤15×10 -6 .

[0047] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0048] Each embodiment adopts the long shroud capable of blowing argon as described above.

[0049] Example 1

[0050] A steel plant produces DC06 steel with a carbon content of ≤0.0030wt% by continuous casting. The conventional shroud is used. The argon blowing rate is 80NL / min and the steel flow rate is controlled at 6.9t / min. The total oxygen in the slab after continuous casting is 24×10 -6 .

[0051] The production using the argon-blowing long shroud of the present invention comprises the following steps:

[0052] S1. Before continuous casting, the above-mentioned argon-blowing long nozzle is connected to the sliding nozzle of the ladle, and a refractory sealing pad is set on the inner wall of the bowl of the argon-blowing long nozzle. The refractory sealing pad is opened at the position of the argon blowing channel. The vent hole is 20 mm long horizontally and 8 mm wide vertically. Before continuous casting, the ultra-low carbon steel is deoxidized by aluminum, and the acid-soluble aluminum content in the molten steel is controlled to 300×10 -6 , total oxygen content is 47×10 -6 ; The width of the air guide ring groove of the argon-blowing long nozzle is 5mm, the depth is 5mm, and the cross section is semicircular. Five vertical air guide grooves are opened on the inner wall of the long nozzle bowl. The air guide grooves are unevenly distributed around the inner wall of the long nozzle bowl. Among them, three air guide grooves are distributed on the side away from the argon blowing channel. The depth of the air guide groove is 5.0mm, the width is 4.0mm, and the length is 80mm; the upper end of the air guide groove starts from the argon ring groove of the long nozzle bowl, and the lower end is 5.0mm below the lower edge of the refractory sealing pad.

[0053] S2. During the continuous casting process, argon gas is introduced into the long nozzle through the air guide ring groove and the air guide groove. The argon gas pressure is 0.2×10 6 Pa, the steel throughput of the long shroud is 7.8t / min, and the argon flow rate is 160NL / min; ultra-low carbon steel production is achieved, and the total oxygen in the molten steel after continuous casting is 15×10 -6 .

[0054] Example 2

[0055] A steel plant produces M3A35 steel with a carbon content of ≤0.0020wt% by continuous casting of slabs. The conventional shroud is used. The argon blowing of the shroud is 90NL / min. The steel throughput is controlled at 6.6t / min. The total oxygen in the slab after continuous casting is 21×10 -6 .

[0056] The production using the argon-blowing long shroud of the present invention comprises the following steps:

[0057] S1. Before continuous casting, the above-mentioned argon-blowing long nozzle is connected to the sliding nozzle of the ladle, and a refractory sealing pad is set on the inner wall of the bowl of the argon-blowing long nozzle. The refractory sealing pad is opened at the position of the argon blowing channel. The vent hole is 30 mm long horizontally and 8 mm wide vertically. Before continuous casting, the ultra-low carbon steel is deoxidized by aluminum, and the acid-soluble aluminum content in the molten steel is controlled to 400×10 -6 , total oxygen content is 39×10 -6The width of the air guide ring groove of the argon-blowing shroud is 7mm, the depth is 10mm, and the cross section is rectangular. Eight vertical air guide grooves are opened on the inner wall of the shroud, and the air guide grooves are unevenly distributed around the inner wall of the shroud bowl. Five of the air guide grooves are distributed on the side away from the argon blowing channel. The depth of the air guide groove is 3.0mm, the width is 4.0mm, and the length is 85mm; the upper end of the air guide groove starts from the argon ring groove of the shroud bowl, and the lower end is 10.0mm below the lower edge of the refractory sealing pad.

[0058] S2. During the continuous casting process, argon gas is introduced into the long nozzle through the air guide ring groove and the air guide groove. The argon pressure is 0.4×10 6 Pa, the steel throughput of the long shroud is 8.6t / min, and the argon flow rate is 250NL / min; ultra-low carbon steel production is achieved, and the total oxygen in the molten steel after continuous casting is 12×10 -6 .

[0059] Example 3

[0060] A steel plant produces St13 steel with a carbon content of ≤0.0030wt% by continuous casting. The conventional shroud is used. The argon blowing rate is 80NL / min and the steel flow rate is controlled at 6.9t / min. The total oxygen in the slab after continuous casting is 22×10 -6 .

[0061] The production using the argon-blowing long shroud of the present invention comprises the following steps:

[0062] S1. Before continuous casting, the above-mentioned argon-blowing long nozzle is connected to the sliding nozzle of the ladle, and a refractory sealing pad is set on the inner wall of the bowl of the argon-blowing long nozzle; a vent hole is set on the refractory sealing pad directly opposite to the argon blowing channel, and the vent hole is 35 mm long horizontally and 10 mm wide vertically; before continuous casting, the ultra-low carbon steel is deoxidized by aluminum, and the acid-soluble aluminum content in the molten steel is controlled to 400×10 -6 , total oxygen content is 35×10 -6 The width of the air guide ring groove of the argon-blowing shroud is 10mm, the depth is 8mm, and the cross section is elliptical. Five vertical air guide grooves are opened on the inner wall of the shroud, and the air guide grooves are unevenly distributed around the inner wall of the shroud bowl. Among them, three air guide grooves are distributed on the side away from the argon blowing channel. The depth of the air guide groove is 4.0mm, the width is 10.0mm, and the length is 83mm; the upper end of the air guide groove starts from the argon ring groove of the shroud bowl, and the lower end is 8.0mm below the lower edge of the refractory sealing pad.

[0063] S2. During the continuous casting process, argon gas is introduced into the long nozzle through the air guide ring groove and the air guide groove. The argon pressure is 0.4×10 6 Pa, the steel throughput of the long shroud is 8.5t / min, and the argon flow rate is 300NL / min; ultra-low carbon steel production is achieved, and the total oxygen in the molten steel after continuous casting is 11×10 -6 .

[0064] Example 4

[0065] A steel plant produces electrode flat steel YT2 steel with a carbon content of ≤0.0080wt%. The traditional long shroud is used. The argon blowing at the long shroud is 20NL / min, and the steel flow rate is controlled at 3.3t / min. The total oxygen in the billet after continuous casting is 39×10 -6 .

[0066] The production using the argon-blowing long shroud of the present invention comprises the following steps:

[0067] S1. Before continuous casting, the above-mentioned argon-blowing long nozzle is connected to the sliding nozzle of the ladle, and a refractory sealing pad is set on the inner wall of the bowl of the argon-blowing long nozzle. The refractory sealing pad is opened at the position of the argon blowing channel. The horizontal length of the vent hole is 25 mm and the vertical width is 10 mm. Before continuous casting, the ultra-low carbon steel is deoxidized by aluminum, and the acid-soluble aluminum content in the molten steel is controlled to 400×10 -6 , total oxygen content is 38×10 -6 The width of the air guide ring groove of the argon-blowing shroud is 10mm, the depth is 13mm, and the cross section is semicircular. Two vertical air guide grooves are opened on the inner wall of the shroud, and the air guide grooves are unevenly distributed around the inner wall of the shroud bowl. The two air guide grooves are distributed on the side away from the argon blowing channel. The depth of the air guide groove is 5.0mm, the width is 4.0mm, and the length is 83mm; the upper end of the air guide groove starts from the argon ring groove of the shroud bowl, and the lower end is 8.0mm below the lower edge of the refractory sealing pad.

[0068] S2. During the continuous casting process, argon gas is introduced into the long nozzle through the air guide ring groove and the air guide groove. The argon gas pressure is 0.2×10 6 Pa, the steel throughput of the long shroud is 4.0t / min, and the argon flow rate is 30NL / min; ultra-low carbon steel production is achieved, and the total oxygen in the molten steel after continuous casting is 15×10 -6 .

[0069] It can be seen from the above embodiments that the present invention improves the structure of the shroud, and an air guide ring groove is provided in the horizontal direction along the inner wall of the shroud; a plurality of air guide grooves are provided in the vertical direction on the inner wall of the shroud bowl; the upper end of the air guide groove is connected to the air guide ring groove, and the lower end of the air guide groove is lower than the lower edge of the refractory sealing pad provided on the inner wall of the shroud bowl. The blown argon gas is guided to flow toward the lower part of the shroud, so that the molten steel absorbs the argon gas, and argon bubbles are generated in the molten steel. The argon bubbles move downward with the molten steel, promoting the argon bubbles to break into smaller and more dispersed argon bubbles, promoting the removal of inclusions in the molten steel, and facilitating the production of high-cleanliness ultra-low carbon steel.

[0070] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A long shroud capable of blowing argon, characterized in that: An air guide ring groove is provided horizontally along the inner wall of the long shroud bowl; a plurality of air guide grooves are provided vertically on the inner wall of the long shroud; the upper end of the air guide groove is connected to the air guide ring groove, and the lower end of the air guide groove is lower than the lower edge of the refractory sealing pad provided on the inner wall of the long shroud bowl.

2. The argon-blown shroud according to claim 1, characterized in that: The width of the air guide ring groove is 5-20 mm, the depth is 5-15 mm, and the cross-section is semicircular, elliptical or rectangular.

3. The argon-blowable shroud according to claim 1, characterized in that: The air guide ring groove is connected to an argon blowing channel horizontally extending from the outer side of the long shroud to the inner wall of the long shroud bowl; a vent hole is provided in the refractory sealing pad facing the argon blowing channel, and the size of the vent hole is slightly larger than that of the argon blowing channel.

4. The argon-blown shroud according to claim 1, characterized in that: The depth of the air introduction groove is 2.0-10.0mm, the width of the air introduction groove is 2.0-20.0mm, and the number of the air introduction grooves is 4-8; the distance between the lower end of the air introduction groove and the lower edge of the refractory sealing pad arranged on the inner wall of the long water nozzle bowl is 3-10mm; the air introduction grooves are unevenly distributed around the inner wall of the long water nozzle bowl, and more air introduction grooves are arranged on the side away from the argon blowing channel.

5. A method for producing ultra-low carbon steel, characterized in that: The steps include: S1. Before the continuous casting starts, the argon-blown long shroud according to any one of claims 1 to 4 is connected to the ladle sliding shroud, and a refractory sealing pad is provided on the inner wall of the bowl of the argon-blown long shroud; S2. During the continuous casting process, argon gas is introduced into the long water nozzle through the air guide ring groove and the air guide groove to achieve ultra-low carbon steel production.

6. The method for producing ultra-low carbon steel according to claim 5, characterized in that: In step S1, the ultra-low carbon steel is deoxidized by aluminum before continuous casting, and the acid-soluble aluminum content in the molten steel is controlled to be (150-750)×10 -6 、Total oxygen content is (20-80)×10 -6 .

7. The method for producing ultra-low carbon steel according to claim 5, characterized in that: In step S2, the argon pressure is (0.2-0.5)×10 6 Pa, the argon flow rate is Q, and Q = a × Q 钢 , where: Q is the argon blowing flow rate, NL / min; Q 钢 is the steel flow rate of the long shroud, t / min; a is the coefficient, and the value range of a is 5-50.

8. The method for producing ultra-low carbon steel according to claim 5, characterized in that: In step S2, the steel throughput of the long shroud is 3-15 t / min.

9. The method for producing ultra-low carbon steel according to claim 5, characterized in that: In step S2, the pressure between the long shroud and the sliding shroud is controlled to be 1000-6000N.

10. The method for producing ultra-low carbon steel according to claim 5, characterized in that: After continuous casting, the total oxygen content of ultra-low carbon steel is ≤15×10 -6 .

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