Method for reducing tundish stopper nodules

Abstract

The invention discloses a method for reducing tundish stopper nodules, a tundish comprises a tundish body, an electrode bar, a stopper, a submersed nozzle and a power supply, the lower ends of the electrode bar and the stopper extend into the tundish body, the upper ends of the electrode bar and the stopper extend out of the tundish body, the positive electrode of the power supply is electrically connected with the submersed nozzle, and the negative electrode of the power supply is electrically connected with the submersed nozzle. The method comprises the steps that in the tundish continuous casting process, the rising speed of the stopper rod is obtained; under the condition that the rising speed of the stopper rod is not higher than a first set value, the power supply provides current with first intensity; under the condition that the rising speed of the stopper rod is higher than a first set value, the power supply provides current with second intensity; wherein the first strength is smaller than the second strength. According to the method provided by the invention, the nodulation rate of the stopper rod is reduced, and the stability of the casting process is improved.

Description

Technical Field

[0001] This application belongs to the technical field of continuous casting, and particularly relates to a method for reducing the nodulation of the stopper rod in the tundish. Background Art

[0002] For low-carbon steel and extra-low-carbon steel deoxidized by aluminum and silicon-aluminum composite deoxidation, the main deoxidation products in the steel are Al2O3-based inclusions. Although during the smelting process, techniques such as top slag optimization, RH refining, and steel liquid calming are used to promote the floating and removal of such inclusions, there are still a large number of fine and dispersed Al2O3-based inclusions in the steel liquid. These inclusions will deposit on the stopper rod during continuous casting to form nodules.

[0003] If too many nodules form on the stopper rod and peel off into the steel liquid, the larger-sized detached objects may enter the submerged entry nozzle, hindering the flow of the steel liquid from the tundish into the mold, affecting the stable control of the liquid level fluctuation in the mold, and causing the abnormal rise of the stopper rod, and even serious accidents such as stopping casting.

[0004] In related technologies, the normal casting process is mainly ensured by improving the cleanliness of the steel liquid, controlling the number of consecutive casting heats, optimizing the stopper rod material, etc. However, for steel grades such as aluminum-deoxidized steel, Al2O3-based inclusions in the steel liquid are inevitable, and the easy nodulation on the stopper rod during the casting process is a difficult problem that plagues the existing casting process. Summary of the Invention

[0005] To solve the technical problem that the current stopper rod is prone to nodulation and the nodules are likely to fall off, affecting the smooth progress of casting, this application provides a method for reducing the nodulation of the stopper rod in the tundish.

[0006] This application provides a method for reducing the nodulation of the stopper rod in the tundish. The tundish includes a tundish body, an electrode rod, a stopper rod, a submerged entry nozzle, and a power supply. The lower ends of the electrode rod and the stopper rod both extend into the tundish body, and the upper ends both extend out of the tundish body. The positive pole of the power supply is electrically connected to the submerged entry nozzle, and the negative pole is electrically connected to the electrode rod. The method includes:

[0007] During the continuous casting process of the tundish, obtain the rising rate of the stopper rod;

[0008] When the rising rate of the stopper rod is not higher than the first set value, the power supply provides a current of the first intensity; when the rising rate of the stopper rod is higher than the first set value, the power supply provides a current of the second intensity; wherein, the first intensity is less than the second intensity.

[0009] In some embodiments, when the rising rate of the stopper rod is higher than the first set value and not lower than the second set value, the power supply provides a current of the second intensity; when the rising rate of the stopper rod is higher than the second set value, the power supply provides a current of the third intensity; the third intensity is greater than the second intensity, and the second set value is greater than the first set value.

[0010] In some embodiments, the first set value is 0.04 - 0.06 mm / min, and the second set value is 0.08 - 0.12 mm / min.

[0011] In some embodiments, the first intensity is 50 - 100 A.

[0012] In some embodiments, the second intensity is 100 - 150 A.

[0013] In some embodiments, the third intensity is 150 A - 300 A.

[0014] In some embodiments, a plurality of electrode rods are provided, and the plurality of electrode rods are disposed around the outer periphery of the stopper rod.

[0015] In some embodiments, the number of the electrode rods is 2 - 4, and the distance between the electrode rods and the stopper rod is 80 mm - 400 mm.

[0016] In some embodiments, the voltage of the power supply is 10 - 35 V.

[0017] In some embodiments, the current provided by the power supply is a pulsed current, and the frequency of the pulsed current is 5000 Hz - 80000 Hz.

[0018] According to the method for reducing the nodulation of the tundish stopper rod provided by the embodiment of the present application, it includes: during the continuous casting of the tundish, obtaining the rising rate of the stopper rod; when the rising rate of the stopper rod is not higher than the first set value, the power supply provides a current of the first intensity; when the rising rate of the stopper rod is higher than the first set value, the power supply provides a current of the second intensity; wherein, the first intensity is less than the second intensity. By applying an external electric field to the molten steel in the tundish by the power supply, the Al2O3 inclusion particles in the molten steel carry positive charges, and the current will drive the Al2O3 inclusions to migrate directionally to the negative electrode, that is, the electrode rod, effectively improving the cleanliness of the molten steel.

[0019] The rising rate of the stopper rod is related to the amount of Al2O3 inclusions in the molten steel. The faster the rising rate of the stopper rod, the more Al2O3 inclusions in the molten steel. Therefore, a low current intensity is adopted when the rising rate of the stopper rod is low, and a high current intensity is adopted when the rising rate of the stopper rod is high. In the whole casting cycle, the molten steel can continuously maintain a high cleanliness, reduce the rate of Al2O3 inclusions depositing on the stopper rod, and improve the service life of the stopper rod. Brief Description of the Drawings

[0020] Figure 1 The process flow diagram showing a method for reducing nodulation of the tundish stopper rod in the present application is shown. Detailed Embodiments

[0021] In order to enable those skilled in the art in the technical field to which the present application belongs to more clearly understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present application.

[0022] In the first aspect embodiment of the present application, a method for reducing nodulation of the tundish stopper rod is provided, which can reduce the nodulation rate of the stopper rod and improve the service life of the stopper rod.

[0023] The present application will be described below in conjunction with the drawings and with reference to specific embodiments:

[0024] The tundish includes a ladle body, an electrode rod, a stopper rod, a submerged nozzle, and a power supply.

[0025] The ladle body is provided with a chamber, a top opening communicating with the chamber, and a lower outlet. The top opening allows the molten steel in the ladle to enter the chamber, and the submerged nozzle is connected at the lower opening. The lower end of the submerged nozzle can extend into the mold, so that the molten steel in the ladle body enters the mold through the submerged nozzle.

[0026] The upper end of the electrode rod is located outside the molten steel in the ladle body and is connected to the negative pole of the power supply. The lower end of the electrode rod is located inside the ladle body and can extend into the molten steel, so that the positively charged Al2O3 inclusion particles in the molten steel migrate from the molten steel to the electrode rod and deposit on the electrode rod, reducing the inclusion content in the molten steel.

[0027] The upper end of the stopper rod is located outside the molten steel, and the lower end is inserted into the molten steel in the ladle. The position of the stopper rod corresponds to the position of the submerged nozzle, so that the size of the lower outlet can be adjusted, thereby adjusting the flow rate of the molten steel. In the process of the molten steel being discharged from the lower outlet, inclusions will be deposited on the stopper rod, forming a distribution pattern in which more inclusions are deposited at the lower end of the stopper rod, and the thickness of the inclusions deposited gradually decreases from bottom to top on the periphery. The stopper rod is generally inserted 50mm to 70mm below the molten steel surface, with a fluctuation range of 0mm to 10mm.

[0028] The power supply can provide pulse current, the positive electrode is electrically connected to the immersed nozzle, and the negative electrode is electrically connected to the electrode rod, so that an electric field will be formed in the molten steel in the tundish. The Al2O3 inclusions are positively charged and migrate toward the negative electrode rod, which promotes the deposition of inclusions and adheres to the outside of the negative electrode rod, which can effectively improve the cleanliness of the molten steel, reduce the deposition of inclusions on the stopper rod, keep the stopper rod head with a good appearance, and make the flow regulation of the molten steel stable and accurate.

[0029] In some embodiments, there may be multiple electrode rods, which are arranged around the outer periphery of the stopper rod. Since the electrode rod itself is the deposition position of Al2O3 particles, the arrangement of multiple electrode rods is equivalent to increasing the deposition area of ​​Al2O3 particles, which is more conducive to the attachment of Al2O3 particles and improves the cleanliness of the molten steel. In some embodiments, multiple electrode rods can be arranged around the stopper rod at equal intervals. Of course, multiple electrode rods can also be distributed at non-equal intervals, which can be adjusted according to the shape of the tundish.

[0030] In some embodiments, the electrode rods can be set to 2 to 4. If the number of electrode rods is too small, the deposition area of ​​Al2O3 particles will be reduced to a certain extent. If the number of electrode rods is too large, it will increase the cost and will not further improve the cleanliness of the molten steel. In some embodiments, the distance between the electrode rod and the stopper rod can be 80mm to 400mm, such as 90mm, 100mm, 150mm, 180mm, 200mm, 250mm, 260mm, 280mm, 290mm, 310mm, 350mm, 360mm, 380mm or 390mm. If the distance between the electrode rod and the stopper rod is too large, the removal effect of Al2O3 particles in the surrounding molten steel will be affected. If the distance between the electrode rod and the stopper rod is too small, it may affect the normal operation of the stopper rod, and sufficient safe operating distance needs to be reserved.

[0031] In other embodiments, the electrode rod can also be set as one, and the electrode rod and the immersed water nozzle are staggered in a direction perpendicular to the stopper rod, that is, the electrode rod and the stopper rod are staggered, so that a large-scale electric field is formed in the molten steel, thereby improving the adhesion effect of inclusions on the electrode rod and improving the cleanliness of the molten steel.

[0032] See also Figure 1 The method for reducing the nodule of the intermediate plug rod provided in the embodiment of the present application includes:

[0033] S1. During the continuous casting process in the tundish, obtain the rising rate of the stopper rod in the tundish.

[0034] S2. When the rising rate of the stopper rod is not higher than the first set value, the power supply provides a current of the first intensity; when the rising rate of the stopper rod is higher than the first set value, the power supply provides a current of the second intensity; wherein, the first intensity is less than the second intensity.

[0035] The stopper rod is a structure used to control the molten steel flow rate from the tundish into the mold. Generally speaking, as Al2O3 particles deposit on the head of the stopper rod, the gap between the stopper rod and the submerged nozzle will decrease, and the molten steel flow rate will decrease. The tundish is generally equipped with a stopper rod automatic lifting device to make the stopper rod rise when the gap between the stopper rod and the submerged nozzle decreases, so as to maintain the original molten steel flow rate. When a large flow rate of molten steel is required, the stopper rod can also be controlled to rise to increase the gap between the stopper rod and the submerged nozzle, thereby increasing the molten steel flow rate.

[0036] The rising rate of the stopper rod refers to the upward movement height of the stopper rod per unit time. In some embodiments, the height of the stopper rod can be detected by a height sensor first, and then the rising rate of the stopper rod can be calculated. In other embodiments, the rising rate of the stopper rod can also be directly detected by a rate sensor. The detection frequency of the rising rate of the stopper rod can be detected once every 5 min to 15 min, such as once every 6 min, 8 min, 9 min, 12 min, 13 min or 14 min, etc. Of course, it can also be detected once every 5 s to 15 s, such as once every 10 s, with higher accuracy.

[0037] The rising rate of the stopper rod is related to the cleanliness of the molten steel. The higher the cleanliness of the molten steel, the fewer the Al2O3 particles, the lower the deposition rate of Al2O3 particles on the stopper rod, and the slower the rising rate of the stopper rod. The lower the cleanliness of the molten steel, the more the Al2O3 particles, the higher the deposition rate of Al2O3 particles on the stopper rod, and the faster the rising rate of the stopper rod. Therefore, the rising rate of the stopper rod reflects the amount of Al2O3 particles in the molten steel.

[0038] When the rising rate of the stopper rod is not higher than the first set value, it means that the cleanliness of the molten steel is relatively high. By using the first-intensity current with a not-too-high current intensity, a large amount of Al2O3 particles in the molten steel can be deposited on the electrode rod, improving the cleanliness of the molten steel, reducing the Al2O3 particles deposited on the stopper rod, thus slowing down the nodulation rate of the stopper rod and increasing the service life of the stopper rod. When the rising rate of the stopper rod is higher than the first set value, it means that the cleanliness of the molten steel is relatively low. By using the second-intensity current with a higher current intensity, a large amount of Al2O3 particles in the molten steel can be promoted to deposit on the electrode rod, improving the cleanliness of the molten steel, reducing the Al2O3 particles deposited on the stopper rod, thus slowing down the nodulation rate of the stopper rod and increasing the service life of the stopper rod.

[0039] This application adjusts the current intensity according to the rising rate of the stopper rod, thereby improving the cleanliness of the molten steel, slowing down the nodulation rate of the stopper rod, increasing the service life of the stopper rod, and also saving costs.

[0040] More specifically, in some embodiments, when the rising rate of the stopper rod is higher than the first set value and not lower than the second set value, the power supply provides the current of the second intensity; when the rising rate of the stopper rod is higher than the second set value, the power supply provides the current of the third intensity; the third intensity is greater than the second intensity, and the second set value is greater than the first set value.

[0041] The situation where the rising rate of the stopper rod is not lower than the first set value is more carefully divided into two segments, namely, when the rising rate of the stopper rod is higher than the first set value and not lower than the second set value, and when the rising rate of the stopper rod is higher than the second set value. For the situation where the rising rate of the stopper rod is higher than the first set value and not lower than the second set value, the power supply supplies the current of the second intensity. For the situation where the rising rate of the stopper rod is higher than the second set value, the power supply supplies the current of the third intensity. The third intensity is greater than the second intensity. That is to say, the smaller the rising rate of the stopper rod, the smaller the current intensity supplied by the power supply, and the larger the rising rate of the stopper rod, the larger the current intensity supplied by the power supply. This is because the higher the rising rate of the stopper rod, the lower the cleanliness of the molten steel and the more Al2O3 particles. Then, a stronger electric field is needed to promote the deposition of Al2O3 particles on the electrode rod to improve the cleanliness of the molten steel, reduce the amount of Al2O3 particles deposited on the stopper rod, thereby reducing the replacement frequency of the stopper rod and increasing the service life of the stopper rod.

[0042] In some embodiments, the first set value can be 0.04 - 0.06 mm / min, such as 0.045 mm / min, 0.048 mm / min, 0.05 mm / min, 0.052 mm / min, 0.053 mm / min, or 0.058 mm / min. The second set value can be 0.08 - 0.12 mm / min, such as 0.085 mm / min, 0.086 mm / min, 0.088 mm / min, 0.089 mm / min, 0.09 mm / min, 0.093 mm / min, 0.094 mm / min, 0.098 mm / min, 0.099 mm / min, 0.1 mm / min, or 0.11 mm / min, etc.

[0043] If the first set value is too large, to a certain extent, it will reduce the cleanliness of the molten steel and increase the deposition rate of nodules on the stopper rod. If the second set value is too large, to a certain extent, it will reduce the cleanliness of the molten steel and increase the deposition rate of nodules on the stopper rod.

[0044] In some embodiments, the current can be a pulsed current. The pulsed current can be a square-wave positive pulsed current, which has a peak value and a zero value for the current intensity. The aforementioned first intensity, second intensity, and third intensity are the peak values of the square-wave positive pulsed current. The zero value means the current intensity is 0. Using a pulsed current can form an instantaneous strong current in the molten steel. This strong electric field can promote the deposition of Al2O3 particles on the electrode rod and improve the cleanliness of the molten steel. In some other embodiments, the current can also be a constant current, which can also make the Al2O3 particles deposit on the electrode rod and improve the cleanliness of the molten steel.

[0045] When the current is a pulsed current, the voltage of the power supply can be 10 - 35 V, and the frequency of the pulsed current can be 5000 Hz - 80000 Hz.

[0046] In some embodiments, the first intensity is 50 - 100 A, such as 60 A, 70 A, 80 A, 90 A, or 95 A, etc. That is to say, when the rising rate of the stopper rod does not exceed the first set value, the peak value of the pulsed current is 50 - 100 A.

[0047] In some embodiments, the second intensity is 100 - 150 A, such as 110 A, 120 A, 125 A, 130 A, or 145 A, etc. That is to say, when the rising rate of the stopper rod is higher than the first set value and not lower than the second set value, the peak value of the pulsed current is 100 - 150 A.

[0048] In some embodiments, the third intensity is 150A to 300A, such as 160A, 165A, 170A, 180A, 185A, 190A, 192A, 194A, 196A, or 198A, etc. That is to say, when the rising rate of the stopper rod is higher than the second set value, the peak value of the pulsed current is 150A to 300A.

[0049] In certain embodiments, the molten steel to be cast is aluminum-deoxidized molten steel or silicon-aluminum composite deoxidized molten steel. This kind of molten steel contains Al2O3 particle inclusions, which are deposited on the electrode rod under the action of the pulsed current, improving the cleanliness of the molten steel. In certain embodiments, the molten steel to be cast is low-carbon steel molten steel or ultra-low-carbon steel molten steel.

[0050] The method for reducing the nodulation of the tundish stopper rod of the present application will be further described in detail below with specific embodiments.

[0051] Example 1

[0052] In this embodiment, the steel grade produced is ultra-low-carbon IF steel, and continuous casting is carried out for 7 furnaces in a row. The initial immersion depth of the tundish stopper rod is 65mm, the first set value is 0.04mm / min, and the second set value is 0.08mm / min. The specific production steps are as follows:

[0053] 1) Obtain qualified molten steel through converter - RH refining;

[0054] 2) In the continuous casting process, connect a circuit system between the submerged entry nozzle in the mold and the electrode rod inserted into the molten steel in the tundish. Among them, the submerged entry nozzle is the positive electrode, and 2 electrode rods are inserted into the molten steel in the tundish as the negative electrodes. The electrode rods are 100mm away from the stopper rod and are symmetrically distributed;

[0055] 3) After the continuous casting of molten steel starts, turn on the pulsed current in the above circuit system;

[0056] 4) Set the current voltage to 35V and the frequency to 10000Hz;

[0057] 5) Monitor the depth change curve of the tundish stopper rod. In the first 2 furnaces before pouring, the height of the stopper rod is relatively stable, and the rising rate is 0.03mm / min. A smaller current with an intensity of 75A is passed; from the 3rd furnace to the 5th furnace during pouring, the rising rate of the stopper rod is 0.15mm / min, and a larger current with an intensity of 200A is passed; in the last 2 furnaces during pouring, the rising rate of the stopper rod is 0.06mm / min, and a medium current with an intensity of 100A is passed.

[0058] Example 2

[0059] In this embodiment, the steel grade produced is extra-low carbon IF steel. During the continuous casting process, 7 furnaces are continuously cast. The initial immersion depth of the tundish stopper rod is 65 mm, the first set value is 0.05 mm / min, and the second set value is 0.09 mm / min. The specific production steps are as follows:

[0060] 1) Obtain qualified molten steel through converter - RH refining;

[0061] 2) In the continuous casting process, connect a circuit system between the submerged entry nozzle in the mold and the electrode rods inserted into the molten steel in the tundish. Among them, the submerged entry nozzle is the positive electrode, and 2 electrode rods are inserted into the molten steel in the tundish as the negative electrode. The electrode rods are 100 mm away from the stopper rod and are symmetrically distributed;

[0062] 3) After the continuous casting of molten steel starts, turn on the pulsed current in the above circuit system;

[0063] 4) Set the current voltage to 35 V and the frequency to 10000 Hz;

[0064] 5) Monitor the change curve of the tundish stopper rod depth. In the initial stage of pouring, the height of the stopper rod is relatively stable, and the rising rate is 0.04 mm / min. A relatively small current with an intensity of 85 A is applied; in the middle stage of pouring, the rising rate of the stopper rod is 0.13 mm / min, and a relatively large current with an intensity of 230 A is applied; in the final stage of pouring, the rising rate of the stopper rod is 0.07 mm / min, and a medium current with an intensity of 120 A is applied.

[0065] Example 3

[0066] In this embodiment, the steel grade produced is extra-low carbon IF steel. During the continuous casting process, 7 furnaces are continuously cast. The initial immersion depth of the tundish stopper rod is 65 mm, the first set value is 0.06 mm / min, and the second set value is 0.1 mm / min. The specific production steps are as follows:

[0067] 1) Obtain qualified molten steel through converter - RH refining;

[0068] 2) In the continuous casting process, connect a circuit system between the submerged entry nozzle in the mold and the electrode rods inserted into the molten steel in the tundish. Among them, the submerged entry nozzle is the positive electrode, and 2 electrode rods are inserted into the molten steel in the tundish as the negative electrode. The electrode rods are 100 mm away from the stopper rod and are symmetrically distributed;

[0069] 3) After the continuous casting of molten steel starts, turn on the pulsed current in the above circuit system;

[0070] 4) Set the current voltage to 35 V and the frequency to 10000 Hz;

[0071] 5) Monitor the change curve of the stopper rod depth in the tundish. At the initial stage of pouring, the height of the stopper rod is relatively stable, with an increasing rate of 0.05 mm / min, and a relatively small current with an intensity of 90 A is applied; at the middle stage of pouring, the increasing rate of the stopper rod is 0.11 mm / min, and a relatively large current with an intensity of 190 A is applied; at the final stage of pouring, the increasing rate of the stopper rod is 0.09 mm / min, and a medium current with an intensity of 118 A is applied.

[0072] Comparative Example 1

[0073] Taking Example 1 as a reference, the difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, the current intensity of the pulsed current during the entire casting campaign is a single set value of 100 A.

[0074] Table 1

[0075] The T.O content in the molten steel in Table 1 represents the oxygen content in the molten steel. The higher the oxygen content, the worse the cleanliness of the molten steel; the lower the oxygen content, the higher the cleanliness of the molten steel. The average thickness of the stopper rod nodulation is obtained by the following method: along the axial direction of the stopper rod, 5 points are equally spaced in the nodulation area on the outer periphery of the stopper rod, the single-sided radial dimension of the nodulation is measured at the positions of the 5 points, and then the average value of the 5 dimensions is calculated.

[0076] It can be seen from the data in Table 1 that in the methods for reducing the nodulation of the tundish stopper rod provided in Examples 1 to 3, the average thickness of the nodulation on the outer periphery of the stopper rod is 1.8 mm to 3 mm. In the method provided in Comparative Example 1, the nodulation thickness of the stopper rod reaches 8 mm, which is much larger than the nodulation thickness in Examples 1 to 3.

[0077] The method for reducing the nodulation of the tundish stopper rod provided in this application evaluates the inclusion level in the molten steel based on the rising rate of the stopper rod, and adjusts the intensity of the electric field accordingly, effectively reducing the nodulation rate of the stopper rod and the nodulation thickness. Using this method to judge the inclusion level is more intuitive and the adjustment is more rapid. It not only eliminates the need to frequently sample and detect the oxygen content of the molten steel, reducing the labor intensity of the operators, but also does not require waiting for the total oxygen test results, improving the adjustment efficiency of the current.

[0078] In this application, unless otherwise clearly defined or limited, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may also include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is less than that of the second feature.

[0079] In the description of this application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to this application.

[0080] In this application, unless otherwise clearly defined or limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0081] In addition, in this application, the descriptions such as "first", "second", etc. are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of this application, "a plurality of" means two or more, unless otherwise specifically and clearly defined.

[0082] Although the embodiments of this application have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and purposes of this application, and the scope of this application is defined by the claims and their equivalents.

Claims

1. A method for reducing the nodulation of the stopper in the tundish. The tundish includes a ladle body, an electrode rod, a stopper, a submerged nozzle, and a power source. The lower ends of the electrode rod and the stopper extend into the ladle body, and the upper ends extend out of the ladle body. The positive pole of the power source is electrically connected to the submerged nozzle, and the negative pole is electrically connected to the electrode rod. It is characterized in that, The method includes: During the continuous casting in the tundish, obtaining the rising rate of the stopper rod; When the rising rate of the stopper rod is not higher than the first set value, the power supply provides a current of the first intensity; when the rising rate of the stopper rod is higher than the first set value, the power supply provides a current of the second intensity; wherein, the first intensity is less than the second intensity.

2. The method for reducing the nodulation of the submerged entry nozzle in the tundish according to claim 1, characterized in that, When the rising rate of the stopper rod is higher than the first set value and not lower than the second set value, the power supply provides a current of the second intensity; when the rising rate of the stopper rod is higher than the second set value, the power supply provides a current of the third intensity; the third intensity is greater than the second intensity, and the second set value is greater than the first set value.

3. The method for reducing the nodulation of the submerged entry nozzle in the tundish according to claim 2, characterized in that, The first set value is 0.04 - 0.06 mm / min, and the second set value is 0.08 - 0.12 mm / min.

4. The method for reducing the nodulation of the submerged entry nozzle in the tundish according to claim 2, wherein, The first intensity is 50 - 100 A.

5. The method for reducing the nodulation of the submerged entry nozzle in the tundish according to claim 2, characterized in that, The second intensity is 100 - 150 A.

6. The method for reducing the nodulation of the submerged entry nozzle in the tundish according to claim 2, wherein, The third intensity is 150 A - 300 A.

7. The method for reducing the nodulation of the submerged entry nozzle in the tundish according to any one of claims 1-6, characterized in that, There are multiple electrode rods, and the multiple electrode rods are arranged around the outer periphery of the stopper rod.

8. The method for reducing the nodulation of the submerged entry nozzle in the tundish according to claim 7, characterized in that, The number of the electrode rods is 2 - 4, and the distance between the electrode rods and the stopper rod is 80 mm - 400 mm.

9. The method for reducing the nodulation of the submerged entry nozzle in the tundish according to any one of claims 1-6, characterized in that, The voltage of the power supply is 10 - 35 V.

10. The method for reducing the nodulation of the submerged entry nozzle in the tundish according to any one of claims 1-6, characterized in that ,, the current provided by the power supply is a pulsed current, and the frequency of the pulsed current is 5000 Hz - 80000 Hz.

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