Method and device for controlling center segregation of high carbon steel billet

Abstract

The application relates to the technical field of continuous steel casting, and discloses a high-carbon-steel small square billet center segregation control method and device, which comprises the following steps: obtaining the molten steel temperature and the pulling speed of each flow on a continuous casting machine; substituting the molten steel temperature and the pulling speed into a pre-established control model to determine the increase and decrease proportion of the crystallizer cooling water amount and the two-cooling-zone specific water amount; and adjusting the crystallizer cooling water amount and the two-cooling-zone specific water amount based on the increase and decrease proportion, so that the liquid core thickness of each flow of the continuous casting billet at the end position of an electromagnetic stirrer is 20mm+ / -0.1mm. The method is favorable for the electromagnetic stirrer to uniformly control the composition and temperature of the liquid core molten steel, improves the center segregation and porosity problems of the last solidification of the continuous casting billet, and improves the stability of the continuous casting billet quality.

Description

Technical Field

[0001] This invention relates to the field of continuous steel casting technology, specifically to a method and apparatus for controlling center segregation in high-carbon steel small square billets. Background Technology

[0002] In actual production, due to the different temperatures of molten steel in each heat of continuous casting and the different outlet positions of the tundish, the temperatures of the molten steel flowing out of the submerged entry nozzles vary in each heat. If the same cooling water volume is set during continuous casting, it will directly affect the morphology of the solidification structure, as well as the thickness of the solidified billet shell and the length of the solidification endpoint, causing the problem of center segregation of the billet, and consequently resulting in the instability of the quality of the continuous casting billets in each heat.

[0003] To ensure stable molten steel temperature in the tundish during casting and achieve constant-temperature, constant-speed continuous casting with consistent billet quality, induction heating temperature control technology for tundishes is receiving increasing attention. However, induction heating tundishes are expensive and rarely used for general steel grades. Furthermore, while induction heating tundishes heat the molten steel flowing from the ladle to the tundish in the flow channel, they cannot eliminate temperature differences between the molten steel flows, which still affects the internal quality and stability of the billet, leading to severe center segregation in square billets. Summary of the Invention

[0004] In view of this, the present invention provides a method and apparatus for controlling center segregation of high carbon steel small square billets, so as to solve the technical problem of severe center segregation of continuously cast billets in the prior art.

[0005] In a first aspect, the present invention provides a method for controlling center segregation in high-carbon steel small square billets, the method comprising:

[0006] To obtain the temperature and casting speed of the molten steel in each stage of the continuous casting machine;

[0007] Substitute the molten steel temperature and casting speed into the pre-established control model to determine the increase or decrease ratio of the cooling water volume in the crystallizer and the water volume in the secondary cooling zone.

[0008] Based on the increase / decrease ratio, the cooling water volume of the crystallizer and the water volume of the secondary cooling zone are adjusted so that the liquid core thickness of each continuous casting billet at the end electromagnetic stirrer position is 20mm±0.1mm.

[0009] The control model is as follows:

[0010]

[0011] Where Q is the increase / decrease ratio, T is the temperature of molten steel, and Tc is L For the liquidus temperature of molten steel, TT L This refers to the superheat of the molten steel.

[0012] In one optional implementation, the cooling intensity benchmark is set at 1750 L / min for the crystallizer cooling water flow rate and 1.5 L / kg for the secondary cooling zone specific water flow rate. Based on the cooling intensity benchmark, the cooling water flow rate of the crystallizer and the specific water flow rate of the secondary cooling zone are adjusted according to the increase or decrease ratio.

[0013] In one alternative embodiment, the continuous casting machine is a full-arc continuous casting machine with an arc radius of 9m, and the end electromagnetic stirrer is installed below the secondary cooling zone of the continuous casting machine at a position of 8.3m of the arc length.

[0014] In one alternative implementation, the length of the second cooling zone is 6.8m.

[0015] In one alternative implementation, the secondary cooling zone includes four sub-cooling zones with a cooling water volume ratio of 78:96:29:25.

[0016] In one alternative embodiment, the current of the end electromagnetic stirrer is 400A-600A, the frequency is 11Hz-13Hz, and the central magnetic induction intensity is 120mT-160mT.

[0017] In one alternative implementation, an automatic temperature measuring instrument is used to detect the temperature of the molten steel. The automatic temperature measuring instrument is located near the inlet of the tundish of the continuous casting machine.

[0018] In one alternative implementation, the billet section of the continuous casting machine is 140mm × 140mm.

[0019] In one alternative embodiment, the steel cast by the continuous casting machine is high-carbon steel with a carbon content of 0.6%-0.8%.

[0020] Secondly, the present invention provides a device for controlling center segregation in high-carbon steel small square billets, the device comprising:

[0021] The acquisition module is used to acquire the temperature of molten steel and casting speed for each stage on the continuous casting machine;

[0022] The determination module is used to input the molten steel temperature and casting speed into a pre-established control model to determine the increase or decrease ratio of the cooling water volume of the crystallizer and the water volume of the secondary cooling zone.

[0023] The adjustment module is used to adjust the cooling water volume of the crystallizer and the water volume ratio of the secondary cooling zone based on the increase or decrease ratio, so that the liquid core thickness of each continuous casting billet at the end electromagnetic stirrer position is 20mm±0.1mm.

[0024] The control model is as follows:

[0025]

[0026] Where Q is the increase / decrease ratio, T is the temperature of molten steel, and Tc isL For the liquidus temperature of molten steel, TT L This refers to the superheat of the molten steel.

[0027] In this invention, by adjusting the cooling water volume of the crystallizer and the water volume ratio in the secondary cooling zone, the differences in molten steel temperature and casting speed in each heat are balanced, ensuring that the solidification process of each continuous casting billet is similar. This also maintains the liquid core thickness at the end of the electromagnetic stirrer at 20mm ± 0.1mm. This facilitates the uniformity of the composition and temperature of the molten steel in the liquid core by the electromagnetic stirrer, improving the center segregation and porosity problems during the final solidification of the continuous casting billet, and enhancing the stability of the continuous casting billet quality. Furthermore, since the continuous casting cooling water system and the automatic temperature measuring instrument in the tundish are existing equipment in the workshop, they can be put into use with minor modifications, which helps reduce equipment investment costs. By adjusting the cooling water volume of the crystallizer and the water volume ratio in the secondary cooling zone, the differences in molten steel temperature and casting speed can be offset, and the control model is simple and effective, with high reliability and good on-site operability. Attached Figure Description

[0028] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a flowchart illustrating a method for controlling center segregation in high-carbon steel small square billets according to an embodiment of the present invention.

[0030] Figure 2 This is a graph showing the influence of different drawing speeds and molten steel superheat on the position of the liquid core when the thickness is 20 mm, according to an embodiment of the present invention.

[0031] Figure 3 This is a diagram showing the influence of different pulling speeds and cooling water intensities on the position of a liquid core with a thickness of 20 mm, according to an embodiment of the present invention.

[0032] Figure 4 This is a diagram showing the relationship between different drawing speeds, different superheats of molten steel, and cooling water intensity according to an embodiment of the present invention.

[0033] Figure 5 This is a structural block diagram of a device for controlling center segregation of high-carbon steel small square billets according to an embodiment of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] In some technologies, besides induction heating temperature control in the tundish, numerical simulation of the tundish can optimize the flow field and reduce dead zones, thus minimizing temperature differences between flows. However, it cannot improve temperature differences between furnaces. Other technologies propose dynamically controlling the cooling water flow rate on each face of the crystallizer by calculating the heat flux density, promoting symmetrical heat transfer of molten steel within the crystallizer and ensuring uniform growth of the initial solidified billet shell. However, this technology only considers the heat flux difference between the symmetrical faces of the crystallizer at the same moment, neglecting the temperature differences of molten steel in different heats and flows, thus requiring improvement in the billet quality stability in the casting direction.

[0036] The present invention dynamically adjusts the cooling intensity of the billet according to the changes in molten steel temperature and continuous casting speed, reduces the solidification difference of the billet, thereby improving the problem of carbon segregation in the center of high carbon steel small square billet and improving the stability of billet quality.

[0037] According to an embodiment of the present invention, a method for controlling center segregation in high-carbon steel small square billets is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0038] This embodiment provides a method for controlling center segregation in high-carbon steel small square billets, which can be executed by a server, terminal, continuous casting machine control system, etc. Figure 1 This is a flowchart of a method for controlling center segregation in high-carbon steel small square billets according to an embodiment of the present invention, as shown below. Figure 1 As shown, the process includes the following steps:

[0039] Step S101: Obtain the temperature of molten steel and casting speed for each stage on the continuous casting machine.

[0040] The term "flow" refers to the number of billets that can be cast simultaneously on a continuous casting machine. In this embodiment, the temperature of molten steel near the inlet of the tundish can be collected in real time by an automatic temperature measuring instrument, and the set casting speed can also be obtained directly from the continuous casting machine control system.

[0041] Step S102: Substitute the molten steel temperature and drawing speed into the pre-established control model to determine the increase or decrease ratio of the cooling water volume of the crystallizer and the water volume of the secondary cooling zone.

[0042] The control model is as follows:

[0043]

[0044] Where Q is the increase / decrease ratio, T is the temperature of molten steel, and Tc is L For the liquidus temperature of molten steel, TT L This refers to the superheat of the molten steel.

[0045] The control model in this embodiment was obtained from previous experimental calculations. Specifically, firstly, based on solidification heat transfer calculations, the effects of different drawing speeds, cooling water intensities, and molten steel superheat on the position of the 20mm thick liquid core were measured. Then, using the 20mm thick liquid core position as a reference, the relationship between molten steel superheat, drawing speed, and cooling water intensities was transformed to establish a control model between molten steel superheat and cooling water intensities under different drawing speeds.

[0046] Specifically, taking a continuous casting machine with an arc radius of 9m, and the end electromagnetic stirrer installed below the secondary cooling zone of the continuous casting machine at a position of 8.3m in arc length, and using a crystallizer cooling water flow rate of 1750L / min and a secondary cooling zone specific water flow rate of 1.5L / kg as a benchmark, based on solidification heat transfer calculations, the changes in the liquid core thickness at a position of 20mm under single-factor variations in molten steel superheat and casting speed are shown in Table 1. Figure 2 As shown in Table 2, the changes in the position of the liquid core thickness of 20 mm under the single-factor variations of cooling water intensity and pulling speed are illustrated. Figure 3 As shown. Generally, when the pulling speed is 2.7 m / min and the superheat is 20℃, the position with a liquid core thickness of 20 mm is below the secondary cooling zone and at an arc length of 8.3 m. According to... Figure 2 and Figure 3 As shown, when the continuous casting speed is 2.6 m / min, 2.7 m / min, and 2.8 m / min, for every 1°C increase in the superheat of the molten steel, the thickness of the 20 mm liquid core increases by 0.0468 m, 0.0486 m, and 0.0509 m, respectively. When the continuous casting speed is 2.6 m / min, 2.7 m / min, and 2.8 m / min, for every 1% increase in the cooling water intensity, the thickness of the 20 mm liquid core decreases by 0.0267 m, 0.0272 m, and 0.0281 m, respectively. Then, using the 20 mm thick liquid core position as a reference, the relationship between molten steel superheat, casting speed, and cooling water intensity is transformed, generating a control model for different casting speeds, different molten steel superheats, and different cooling water intensities, as shown in the figure. Figure 4 As shown.

[0047] In actual use, the temperature of each stream of molten steel is obtained directly from real-time monitoring. Then, based on the temperature of each stream of molten steel and the casting speed, the control model is used to calculate the increase or decrease ratio of the cooling water volume of the crystallizer to the water volume of the secondary cooling zone, so that the liquid core thickness of each continuous casting billet at the end electromagnetic stirrer position is 20mm±0.1mm.

[0048] Table 1

[0049]

[0050] Table 2

[0051]

[0052] Step S103: Based on the increase / decrease ratio, adjust the cooling water volume of the crystallizer and the water volume ratio of the secondary cooling zone so that the liquid core thickness of each continuous casting billet at the end electromagnetic stirrer position is 20mm±0.1mm.

[0053] In this embodiment, the cooling water volume of the crystallizer and the specific water volume of the secondary cooling zone can be dynamically adjusted according to the calculated increase / decrease ratio to ensure that the liquid core thickness of each continuous casting billet at the end electromagnetic stirrer position is 20mm ± 0.1mm. This ensures that each continuous casting billet maintains a similar solidification process at the end electromagnetic stirrer position, thereby improving the internal quality of the billet and increasing the stability of the billet quality, and reducing center segregation of the square billet.

[0054] It should be noted that in actual production, the temperature of molten steel fluctuates significantly, and the continuous casting speed is also greatly affected by the production rhythm. When there are significant fluctuations in molten steel temperature and continuous casting speed, the thickness of the liquid core at the end electromagnetic stirrer location also fluctuates significantly. If the liquid core thickness is too large, the timing of the end electromagnetic stirrer's action is too early, causing the concentrated molten steel between the columnar crystals to re-aggregate to the center of the billet in the later stage of solidification, resulting in renewed bridging of the columnar crystals and leading to center segregation and porosity defects in the billet. If the liquid core thickness is too small, the timing of the end electromagnetic stirrer's action is too late, failing to stir and concentrate the molten steel and thus failing to improve center segregation and porosity defects.

[0055] In this embodiment of the invention, by adjusting the cooling water volume of the crystallizer and the water volume of the secondary cooling zone, the differences in the temperature and casting speed of the molten steel in each heat are balanced, so that the solidification process of each continuous casting billet is kept similar, and the thickness of the liquid core at the end of the electromagnetic stirrer is kept at 20mm±0.1mm. This is beneficial to the electromagnetic stirrer to uniformly distribute the composition and temperature of the liquid core molten steel, improve the center segregation and porosity problems during the final solidification of the continuous casting billet, and improve the stability of the quality of the continuous casting billet.

[0056] Furthermore, since the continuous casting cooling water system and the tundish automatic temperature measuring instrument are existing equipment in the workshop, they can be put into use with slight modifications, which helps to reduce equipment investment costs. By adjusting the cooling water volume of the crystallizer and the water volume of the secondary cooling zone, the differences caused by the steel temperature and casting speed can be offset. Moreover, the control model is simple and effective, the results are highly reliable, and the on-site operability is good.

[0057] In some optional implementations, the cooling intensity benchmark is a crystallizer cooling water flow rate of 1750 L / min and a secondary cooling zone specific water flow rate of 1.5 L / kg. Based on the cooling intensity benchmark, the crystallizer cooling water flow rate and the secondary cooling zone specific water flow rate are adjusted according to the increase or decrease ratio.

[0058] In this embodiment, when the continuous casting speed is 2.6m / min, 2.7m / min, or 2.8m / min, the cooling intensity benchmark can be set at 1750L / min for the crystallizer cooling water flow rate and 1.5L / kg for the secondary cooling zone water flow rate. The cooling water flow rate of the crystallizer and the water flow rate of the secondary cooling zone can be adjusted accordingly.

[0059] In some alternative implementations, the continuous casting machine is a full-arc continuous casting machine with an arc radius of 9m, and the end electromagnetic stirrer is installed below the secondary cooling zone of the continuous casting machine at a position of 8.3m of the arc length.

[0060] In some alternative implementations, the length of the secondary cooling zone is 6.8m.

[0061] In some optional implementations, the secondary cooling zone comprises four sub-cooling zones with a cooling water volume ratio of 78:96:29:25. The specific water volume of the secondary cooling zone is the ratio of the total water consumed per unit time in the secondary cooling zone of the continuous casting machine to the mass of the cast billet passing through the secondary cooling zone per unit time, expressed in L / kg. The cooling water volume of all sub-cooling zones per unit time constitutes the total water consumption of the secondary cooling zone per unit time.

[0062] In some alternative implementations, the current of the end electromagnetic stirrer is 400A-600A, the frequency is 11Hz-13Hz, and the central magnetic induction intensity is 120mT-160mT.

[0063] In some alternative implementations, an automatic temperature measuring instrument is used to detect the temperature of the molten steel. The automatic temperature measuring instrument is set near the inlet of the tundish of the continuous casting machine, without affecting the operation of the stopper rod.

[0064] In some alternative implementations, the billet cross-section of the continuous casting machine is 140mm × 140mm.

[0065] In some alternative implementations, the steel cast by the continuous casting machine is high-carbon steel with a carbon content of 0.6%-0.8%.

[0066] The following detailed description is provided through specific examples.

[0067] Example 1:

[0068] The continuous casting machine is a full-arc square billet continuous casting machine, casting C72DA steel with a billet cross-section of 140mm×140mm. The end electromagnetic stirrer is installed 8.3m from the meniscus. The secondary cooling zone uses water spray cooling, with a length of 6.8m and a cooling water volume ratio of 78:96:29:25 for each zone. The end electromagnetic stirrer has a current of 500A, a stirring frequency of 12Hz, and a central magnetic induction intensity of 140mT. When the casting speed is 2.7m / min and the molten steel superheat is 20℃, the coolant volume in the crystallizer is 1750L / min, and the specific water volume in the secondary cooling zone is 1.5L / kg. This is used as the cooling intensity benchmark, and the cooling water volume is adjusted according to changes in casting temperature and casting speed.

[0069] The continuous casting machine has 5 strands. An automatic temperature measuring instrument is installed near the stopper rod in the tundish of each strand to monitor the temperature of the molten steel in real time. The casting speed is 2.7 m / min. The superheat of the molten steel in strands 1 and 5 is 20℃, in strands 2 and 4 it is 23℃, and in strand 3 it is 21℃. The cooling water intensity is dynamically adjusted according to the superheat of the molten steel. Strands 1 and 5 use the standard cooling water intensity, while strands 2 and 4 have their intensity increased by 5.00%, and strand 3 has its intensity increased by 1.80%.

[0070] Temperature measurements using an infrared thermometer showed that the surface center temperature of the billet at each flow straightening position was 1060±4℃. Low-magnification testing during pickling revealed that the carbon segregation index at the center of each flow was controlled between 0.95 and 1.05.

[0071] Example 2:

[0072] The continuous casting machine is a full-arc square billet continuous casting machine, casting C72DA steel with a billet cross-section of 140mm×140mm. The end electromagnetic stirrer is installed at a distance of 8.3m from the meniscus. The secondary cooling zone uses water spray cooling, with a length of 6.8m and a cooling water volume ratio of 78:96:29:25 for each zone. The end electromagnetic stirring current is 500A, the stirring frequency is 12Hz, and the magnetic induction intensity at the center of the stirrer is 140mT.

[0073] The continuous casting machine has 5 strands. An automatic temperature measuring instrument is installed near the stopper rod in the tundish of each strand to monitor the temperature of the molten steel in real time. The casting speed is 2.7 m / min. The superheat of the molten steel in strands 1 and 5 is 25℃, in strands 2 and 4 it is 28℃, and in strand 3 it is 26℃. Although the casting temperatures of each strand are different, the cooling water flow rate in the crystallizer for each strand is 1750 L / min, and the specific water flow rate in the secondary cooling zone of each strand remains constant at 1.5 L / kg.

[0074] Temperature measurements using an infrared thermometer showed that the surface center temperature of the billet at each flow straightening position was 1065±20℃. Low-magnification testing during pickling revealed that the carbon segregation index at the center of each flow was controlled between 0.90 and 1.10.

[0075] Compared to Example 2, which serves as a comparative example, the highest central carbon segregation index in Example 1 is only 1.05, indicating that central segregation is effectively controlled.

[0076] This embodiment also provides a control device for center segregation of high-carbon steel small square billets. This device is used to implement the above embodiments and preferred embodiments, and will not be repeated as already described. As used below, the term "module" can be a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0077] This embodiment provides a device for controlling center segregation in high-carbon steel small square billets, such as... Figure 5 As shown, the device includes:

[0078] The acquisition module 501 is used to acquire the temperature of molten steel and the casting speed of each stage on the continuous casting machine;

[0079] The determination module 502 is used to input the molten steel temperature and casting speed into the pre-established control model to determine the increase or decrease ratio of the cooling water volume of the crystallizer and the water volume of the secondary cooling zone.

[0080] The adjustment module 503 is used to adjust the cooling water volume of the crystallizer and the water volume ratio of the secondary cooling zone based on the increase or decrease ratio, so that the liquid core thickness of each continuous casting billet at the end electromagnetic stirrer position is 20mm±0.1mm.

[0081] The control model is as follows:

[0082]

[0083] Where Q is the increase / decrease ratio, T is the temperature of molten steel, and Tc is L For the liquidus temperature of molten steel, TT L This refers to the superheat of the molten steel.

[0084] In this embodiment, the control device for center segregation of high-carbon steel small square billets is presented in the form of functional units. Here, a unit refers to an ASIC circuit, a processor and memory that execute one or more software or fixed programs, and / or other devices that can provide the above functions.

[0085] Further functional descriptions of the above modules and units are the same as those in the corresponding embodiments described above, and will not be repeated here.

[0086] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for controlling center segregation in high-carbon steel small square billets, characterized in that, The method includes: To obtain the temperature and casting speed of the molten steel in each stage of the continuous casting machine; Substitute the molten steel temperature and the drawing speed into the pre-established control model to determine the increase or decrease ratio of the cooling water volume of the crystallizer and the water volume of the secondary cooling zone. Based on the aforementioned increase / decrease ratio, the cooling water volume of the crystallizer and the water volume ratio of the secondary cooling zone are adjusted so that the liquid core thickness of each continuous casting billet at the end electromagnetic stirrer position is 20mm ± 0.1mm. The control model is as follows: in, Q The increase / decrease ratio is expressed in % %. T The temperature of the molten steel; T L This refers to the liquidus temperature of molten steel. T - T L This represents the superheat of molten steel, expressed in °C.

2. The control method according to claim 1, characterized in that, With the cooling water flow rate of the crystallizer being 1750 L / min and the water flow rate of the secondary cooling zone being 1.5 L / kg as the cooling intensity benchmark, the cooling water flow rate of the crystallizer and the water flow rate of the secondary cooling zone are adjusted based on the increase / decrease ratio on the basis of the cooling intensity benchmark.

3. The control method according to claim 1, characterized in that, The continuous casting machine is a full-arc continuous casting machine with an arc radius of 9m. The end electromagnetic stirrer is installed below the secondary cooling zone of the continuous casting machine at a position of 8.3m of the arc length.

4. The control method according to claim 3, characterized in that, The length of the second cooling zone is 6.8m.

5. The control method according to claim 4, characterized in that, The second cooling zone includes four sub-cooling zones, and the cooling water volume ratio of the sub-cooling zones is 78:96:29:

25.

6. The control method according to claim 1, characterized in that, The current of the end electromagnetic stirrer is 400A-600A, the frequency is 11Hz-13Hz, and the central magnetic induction intensity is 120mT-160mT.

7. The control method according to claim 1, characterized in that, The temperature of the molten steel is detected using an automatic temperature measuring instrument, which is located near the inlet of the tundish of the continuous casting machine.

8. The control method according to claim 1, characterized in that, The billet cross-section of the continuous casting machine is 140mm × 140mm.

9. The control method according to claim 1, characterized in that, The steel cast by the continuous casting machine is high-carbon steel with a carbon content of 0.6%-0.8%.

10. A device for controlling center segregation in high-carbon steel small square billets, characterized in that, The device includes: The acquisition module is used to acquire the temperature of molten steel and casting speed for each stage on the continuous casting machine; The determination module is used to input the molten steel temperature and the drawing speed into a pre-established control model to determine the increase or decrease ratio of the cooling water volume of the crystallizer and the water volume of the secondary cooling zone. The adjustment module is used to adjust the cooling water volume of the crystallizer and the water volume ratio of the secondary cooling zone based on the increase / decrease ratio, so that the liquid core thickness of each continuous casting billet at the end electromagnetic stirrer position is 20mm±0.1mm. The control model is as follows: in, Q The increase / decrease ratio is expressed in % %. T The temperature of the molten steel; T L This refers to the liquidus temperature of molten steel. T - T L This represents the superheat of molten steel, expressed in °C.

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