A nitrogen control structure for continuous casting of steel

Abstract

The utility model discloses a kind of nitrogen control structure of steelmaking continuous casting, including ladle long nozzle, ladle base brick in upper part of pouring zone, sealing cover in lower part of pouring zone;The lower part of ladle base brick is set ladle lower nozzle, and ladle lower nozzle is convex cone shape;The upper part port of ladle long nozzle is set ladle sleeve bowl mouth;Ladle sleeve bowl mouth is taper hole, and the taper hole and the conical shape of ladle lower nozzle form clearance fit;The outer circle of lower part of ladle long nozzle and sealing cover form close fit.Adopt above technical scheme, through the implementation of LF refining nitrogen control specific method, nitrogen content in steel is effectively controlled, and continuous casting nitrogen content is controlled below 50ppm, reduce the degree of harm of nitrogen in molten steel, to ensure the deep-drawing performance of steel, reduce aging, eliminate yield point extension phenomenon, make steel surface smooth, improve yield.

Description

Technical Field

[0001] This utility model belongs to the technical field of continuous casting equipment and process equipment in steel production. More specifically, this utility model relates to a nitrogen control structure for continuous casting in steelmaking. Background Technology

[0002] Nitrogen induces quenching and deformation aging in carbon steel, significantly impacting its properties. While nitrogen aging increases hardness and strength, it reduces toughness and ductility, particularly during deformation aging, where the decrease is more pronounced. Therefore, aging is detrimental to ordinary low-alloy steels, making nitrogen a harmful element. Excessive nitrogen content also reduces weldability, electrical conductivity, and magnetic permeability; furthermore, high nitrogen content can lead to cracking in cast billets.

[0003] Therefore, effective measures must be taken to reduce the nitrogen content in steel, especially for high-grade steels where nitrogen control is particularly important. However, current technologies have not yet been able to solve this problem satisfactorily.

[0004] Using keywords such as "steelmaking; continuous casting; control; nitrogen; nozzle," a search was conducted on existing publicly available technical literature, yielding the following results:

[0005] 1. Chinese patent document: "A precise nitrogen control method for nitrogen-containing high-strength steel", patent (application) number: 202211262945.1; the technical solution described therein is:

[0006] "The precise nitrogen control method for nitrogen-containing high-strength steel includes the following steps: 1. Converter: Bottom-blown nitrogen is used during the converter smelting process. Deoxidizer is added first, followed by nitrogen-enhancing agent during the steel tapping process; 2. LF refining: The molten steel enters the LF refining furnace. The LF furnace adopts an alternating nitrogen / argon blowing mode. Bottom-blown nitrogen is used in the early and middle stages of LF refining. After the white slag refining is completed, the nitrogen content in the steel is measured and the nitrogen content is precisely controlled by feeding nitrogen line. At the same time, bottom blowing is switched to argon; 3. Continuous casting: Gas-protected casting is used in the continuous casting process. The type of protective gas is switched in combination with the nitrogen content control of the molten steel when it exits the LF station."

[0007] The technical effects described are:

[0008] "By precisely controlling the converter smelting temperature, the carbon and oxygen content at the converter endpoint, the amount of nitrogen-enhancing agent added, and the composition of refining slag, nitrogen can be controlled through multiple means, which can effectively solve the problem of unstable nitrogen content in steel and achieve precise nitrogen control of high-strength nitrogen-containing steel containing V and Cr."

[0009] 2. Chinese patent document: "A method for reducing the nitrogen content in steel to obtain low-nitrogen steel in an electric arc furnace steelmaking process", patent (application) number: 202110433004.9; the technical solution described therein is:

[0010] "Methods to reduce nitrogen content in steel to obtain low-nitrogen steel in electric arc furnace steelmaking process: In the electric arc furnace smelting process, scrap steel and molten iron are mixed and smelted, supplemented by rapid slag-forming technology; ferrosilicon is added during tapping to weakly deoxidize the molten steel; in the LF refining process, high-temperature resistant material sealing sleeves are installed at the electrode ports; refining synthetic slag is added during smelting to form slag, and the appropriate bottom-blown argon flow rate is adjusted; in the VD vacuum treatment process, high vacuum degree, extended treatment time, and increased bottom-blown argon flow rate are used for strong stirring; in the continuous casting process, protective casting and immersion sleeve sealing measures are adopted."

[0011] The technical effects described are:

[0012] "Based on the nitrogen absorption and denitrification mechanism of molten steel, and combined with the operational characteristics of each process, the nitrogen content in steel is significantly reduced. This method is simple to operate, and nitrogen control is stable throughout the electric arc furnace steelmaking process, which can effectively ensure that the nitrogen content in the final product is less than 30 ppm."

[0013] However, in reality, the technical solutions recorded in the aforementioned technical documents, as well as the existing publicly applied related technical solutions, have not been able to effectively solve the problems and defects of "high nitrogen content" and "deterioration of steel performance" in the existing technology. Utility Model Content

[0014] This invention provides a nitrogen control structure for continuous casting in steelmaking, the purpose of which is to effectively reduce the nitrogen content in steel and improve material properties.

[0015] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0016] This utility model discloses a nitrogen control structure for continuous casting in steelmaking, comprising a ladle nozzle, a ladle seat brick at the top of the casting zone, and a sealing cover at the bottom of the casting zone; a ladle outlet is provided at the bottom of the ladle seat brick, and the ladle outlet is a raised cone shape; a ladle sleeve bowl is provided at the upper end of the ladle nozzle; the ladle sleeve bowl is a conical hole, which forms a clearance fit with the cone shape of the ladle outlet; and the lower outer circle of the ladle nozzle forms a tight fit with the sealing cover.

[0017] A circumferential seam is provided in the gap between the bowl of the large sleeve and the mating conical surface of the large sleeve outlet; an argon blowing hole for the circumferential seam is provided on the bowl of the large sleeve; the argon blowing hole for the circumferential seam is located at the position where the circumferential seam of the bowl area is connected.

[0018] The argon blowing hole of the large sleeve is connected to the protective casting argon gas control cabinet through a protective casting argon blowing conduit.

[0019] The lower end face of the bowl-shaped sleeve is the lower edge end face of the circumferential seam in the bowl-shaped area, and a sealing ring is provided on the lower edge end face of the circumferential seam in the bowl-shaped area.

[0020] Add tundish covering agent and carbonized rice husk to the impact zone of the molten steel poured in the tundish.

[0021] The thickness of the intermediate slag layer is ≤100mm.

[0022] Cover the sampling and temperature measurement holes with asbestos felt.

[0023] This utility model adopts the above-mentioned technical solution. Through the implementation of the specific method of nitrogen control in LF refining, the nitrogen content in steel is effectively controlled, and the nitrogen content in continuous casting is controlled below 50ppm. This reduces the harmfulness of nitrogen in molten steel, thereby ensuring the deep drawing performance of steel, reducing aging, eliminating yield point extension phenomenon, making the steel surface smooth, and improving the yield. Attached Figure Description

[0024] The following is a brief explanation of the contents shown in the attached figure and the markings therein:

[0025] Figure 1 This is a schematic diagram of the structure of this utility model.

[0026] The diagram is marked as follows:

[0027] 1. Long water inlet of the large package; 2. Sealing ring; 3. Lower edge of the circumferential seam in the bowl area; 4. Argon blowing hole of the circumferential seam of the large package sleeve; 5. Circumferential seam in the bowl area; 6. Bowl of the large package sleeve; 7. Large package seat brick; 8. Large package drain outlet; 9. Sealing cover; 10. Protective casting argon control cabinet; 11. Protective casting argon blowing conduit. Detailed Implementation

[0028] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, so as to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention.

[0029] like Figure 1 The structure shown is a nitrogen control structure for continuous casting in steelmaking, including a ladle nozzle 1, a ladle seat brick 7 at the top of the casting zone, and a sealing cover 9 at the bottom of the casting zone.

[0030] The key point of this utility model is to clarify the nitrogen increase process in continuous casting and propose a process structure and method for nitrogen control in continuous casting.

[0031] In order to solve the problems and overcome the defects of the existing technology, and to achieve the invention objective of effectively reducing the nitrogen content in steel and improving material properties, the technical solution adopted by this utility model is as follows:

[0032] like Figure 1 As shown, in the nitrogen control structure for continuous casting in steelmaking of this utility model, a ladle drain 8 is provided at the lower part of the ladle seat brick 7, and the ladle drain 8 is a raised cone shape; a ladle sleeve bowl 6 is provided at the upper end of the ladle long nozzle 1; the ladle sleeve bowl 6 is a conical hole, and the conical hole and the cone shape of the ladle drain 8 form a clearance fit; the lower outer circle of the ladle long nozzle 1 forms a tight fit with the sealing cover 9.

[0033] Through the implementation of the above specific methods for nitrogen control in LF refining, the nitrogen content in steel is effectively controlled, and the nitrogen content in continuous casting is controlled below 50ppm, which reduces the harmfulness of nitrogen in molten steel, thereby ensuring the deep drawing performance of steel, reducing aging, eliminating yield point extension phenomenon, making the steel surface smooth and the yield high.

[0034] A bowl-shaped circumferential seam 5 is provided at the gap between the bowl-shaped opening 6 and the taper of the large casing 8; an argon blowing hole 4 is provided on the bowl-shaped opening 6 of the large casing; the argon blowing hole 4 of the circumferential seam of the large casing is located at the position where the bowl-shaped circumferential seam 5 is connected.

[0035] Argon gas replacement is performed in the tundish before casting begins, through the argon blowing hole in the circumferential seam of the ladle casing.

[0036] The large sleeve circumferential argon blowing hole 4 is connected to the protective casting argon gas control cabinet 10 through the protective casting argon blowing conduit 11.

[0037] The argon gas supply is started and stopped, and the flow rate of the argon gas is controlled, on the argon gas control cabinet 10 for protection casting.

[0038] The key points of implementing this utility model are:

[0039] 1. Long sprue nozzle alignment for large packages: Improve the success rate of one-time assembly of long sprue nozzles for large packages. The workshop continuously tracks the operational awareness and skills of the personnel on duty to ensure the success rate of one-time assembly of sprue nozzles and vertical alignment.

[0040] 2. Argon sealing of the water inlet and timely adjustment of argon flow rate according to the needs of the process;

[0041] 3. Perform argon purging before pouring in the continuous casting tundish according to regulations, ensuring that the atmosphere purging time is ≥5 minutes until the molten steel enters the tundish;

[0042] 4. Protective casting of the long nozzle in the ladle, and adjustment of argon gas volume; ensure that the argon gas volume of the long nozzle in the ladle meets the requirements of the work instruction, and avoid excessive or insufficient gas volume; if there is no flow meter, manual confirmation is required to ensure that the injection point area of ​​the long nozzle fluctuates slightly but does not expose molten steel.

[0043] 5. Before pouring the large batch of water, check the protective pouring pipes for leaks. If any leaks are found, replace or repair them.

[0044] 6. After the ladle automatically flows down, immediately lower the ladle and insert the long nozzle into the molten steel to reduce the contact time between the molten steel and the air and prevent the molten steel from being contaminated.

[0045] 7. When using the fiber sealing cap for the long nozzle of the large package, a sealing cap with a rim is required. When wearing it, the sealing cap must be flat and intact, and must not be damaged. It should be replaced for each batch as required.

[0046] 8. The nozzle bowl area of ​​the large ladle must be thoroughly cleaned by blowing it with a shower head in the furnace section, and no residual steel or cold slag is allowed to adhere to it.

[0047] 9. Adding covering agent and carbonized rice husk black surface to the tundish: Add tundish covering agent and carbonized rice husk to the impact zone and other parts of the tundish where molten steel is poured; strictly follow the requirements of the work instructions during the pouring process, and add tundish covering agent and carbonized rice husk to the pouring point area and various cavities in the tundish in a timely manner.

[0048] 10. Each heat sample temperature measurement hole must be covered with asbestos felt in a timely manner to ensure black surface operation of the tundish and prevent molten steel from being exposed;

[0049] 11. Constant temperature and constant speed casting: During the steel casting process, the ladle must ensure a constant liquid level during casting; if the molten steel level in the tundish is <400mm, the billet must be thrown out in time; the protective slag in the crystallizer must be blackened during operation; if the liquid level fluctuation exceeds the standard, the billet must be thrown out in time.

[0050] 12. The thickness of the slag layer in the tundish must not exceed 100mm; the thickness of the slag layer in the tundish must be ≤100mm. Slag must be removed in a timely manner.

[0051] The lower end face of the bowl 6 of the large sleeve is the lower edge end face 3 of the circumferential seam in the bowl area, and a sealing ring 2 is provided on the lower edge end face 3 of the circumferential seam in the bowl area.

[0052] The lower end face of the cup mouth 6 of the large package sleeve is reliably sealed to the lower end face of the long water inlet 1 of the large package by means of the sealing ring 2.

[0053] The present invention has been described above with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A nitrogen control structure for continuous casting in steelmaking, comprising a ladle nozzle (1), a ladle seat brick (7) above the casting zone, and a sealing cover (9) below the casting zone, characterized in that: The lower part of the large package seat brick (7) is provided with a large package drain outlet (8), which is a raised cone shape; the upper end of the large package long water outlet (1) is provided with a large package sleeve bowl (6); the large package sleeve bowl (6) is a conical hole, which forms a clearance fit with the cone shape of the large package drain outlet (8); the lower outer circle of the large package long water outlet (1) forms a tight fit with the sealing cover (9).

2. The nitrogen control structure for continuous casting steelmaking according to claim 1, characterized in that: A bowl-shaped circumferential seam (5) is provided at the gap between the bowl-shaped opening (6) of the large sleeve and the taper surface of the large sleeve (8); an argon blowing hole (4) is provided on the bowl-shaped opening (6) of the large sleeve; the argon blowing hole (4) of the large sleeve is located at the position where the bowl-shaped circumferential seam (5) is connected.

3. The nitrogen control structure for continuous casting steelmaking according to claim 2, characterized in that: The large sleeve circumferential argon blowing hole (4) is connected to the protective casting argon gas control cabinet (10) through the protective casting argon blowing conduit (11).

4. The nitrogen control structure for continuous casting steelmaking according to claim 1, characterized in that: The lower end face of the large sleeve bowl (6) is the lower edge end face (3) of the bowl area circumferential seam, and a sealing ring (2) is provided on the lower edge end face (3) of the bowl area circumferential seam.

5. The nitrogen control structure for continuous casting steelmaking according to claim 1, characterized in that: Add tundish covering agent and carbonized rice husk to the impact zone of the molten steel poured in the tundish.

6. The nitrogen control structure for continuous casting steelmaking according to claim 5, characterized in that: The thickness of the intermediate slag layer is ≤100mm.

7. The nitrogen control structure for continuous casting steelmaking according to claim 1, characterized in that: Cover the sampling and temperature measurement holes with asbestos felt.

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