Rare earth steel sheet billet production method

Abstract

The invention discloses a rare earth steel sheet billet production method, which relates to the technical field of metallurgical continuous casting, and comprises the following steps of: alternately pouring refined molten steel containing rare earth elements into an inlet of a crystallizer by adopting a first intermediate tank and a second intermediate tank, so that the molten steel in the crystallizer is not cut off; after the number of times of pouring of the first intermediate tank reaches the first preset number of times, refined molten steel containing rare earth elements is poured into an inlet of the crystallizer through the second intermediate tank, and the first intermediate tank is moved to a standby area to replace a first water gap; and after the number of times of pouring of the first intermediate tank reaches a second preset number of times, refined molten steel containing rare earth elements is poured into the inlet of the crystallizer through the second intermediate tank, the first intermediate tank is moved to the standby area to be replaced with a new first intermediate tank, and the second preset number of times is larger than the first preset number of times. The problem that continuous production cannot be achieved or the production process is long due to production interruption caused by serious nozzle nodulation during rare earth steel continuous casting can be solved.

Description

Technical Field

[0001] This invention relates to the field of metallurgical continuous casting technology, and in particular to a method for producing rare earth steel thin slabs. Background Technology

[0002] With the development of shipbuilding and marine engineering and the energy and petrochemical industries, the demand for manufacturing complex structures and large components has led to increasingly higher requirements for the comprehensive performance of steel materials. Steel is required to have a combination of high strength and high toughness. In addition, due to the requirements of high efficiency and low cost in engineering construction, steel needs to have good weldability. The addition of rare earth elements has enabled steel materials to reduce carbon content and carbon equivalent while ensuring strength and toughness, thereby improving the performance requirements of steel materials.

[0003] Although rare earth elements in steel can refine grains and effectively improve corrosion resistance and low-temperature toughness, rare earth steel with added rare earth elements is prone to severe nozzle clogging during continuous casting, which can cause production interruptions and prevent smooth production. Summary of the Invention

[0004] The applicant found that those skilled in the art have recognized the aforementioned problems in the prior art and have proposed various methods to alleviate the nozzle clogging and blockage phenomena to some extent. For example, patents with publication numbers CN120210457A, CN119571210A, and CN120400671A propose some rare earth steel smelting methods. In these methods, adding rare earth elements to the molten steel causes nozzle blockage, requiring nozzle cleaning. While this solves the nozzle clogging and blockage problem, it prevents continuous casting and rolling and results in an excessively long rare earth steel production process, with prolonged smelting time. Similarly, patents with publication numbers CN119973064A, CN109732072A, and CN213437064U propose solutions to the nozzle clogging problem, but these only suppress it. On average, after 4-5 castings in a 10-casting cycle, nozzle clogging still occurs. Since the system cannot be adjusted during continuous production, addressing the clogging problem necessitates production shutdown. For example, some solutions are proposed in patents with publication numbers CN117733092A and CN118682085A. In these solutions, the power consumption required by the pulse current is relatively large. Under the condition of high pulse voltage, the molten steel may cause safety accidents. In addition, the structure or process in these solutions is relatively complex and can only achieve the suppression effect. After multiple continuous pouring, the intermediate tank needs to be replaced, which is not cost-effective.

[0005] In order to overcome the above-mentioned defects of the prior art, the technical problem to be solved by the embodiments of the present invention is to provide a method for producing rare earth steel thin slabs, which can solve the problem that serious nozzle clogging is prone to occur during the continuous casting of rare earth steel, causing production interruption and inability to continue production or a long production process.

[0006] The specific technical solution of this invention is as follows: A method for producing rare earth steel slabs, the rare earth steel slab production system includes: a crystallizer, a first intermediate tank and a second intermediate tank, the inlet of the crystallizer extends along a first direction, when the first intermediate tank and the second intermediate tank move above the crystallizer, the first nozzle of the first intermediate tank and the second nozzle of the second intermediate tank are located directly above the inlet of the crystallizer and distributed along the first direction, and can allow their molten steel to flow into the inlet of the crystallizer; The method for producing rare earth steel slabs includes: The first intermediate tank and the second intermediate tank are used to alternately pour refined molten steel containing rare earth elements into the inlet of the crystallizer to ensure that the molten steel in the crystallizer does not stop flowing. After the first intermediate tank has been poured a first preset number of times, the second intermediate tank is used to pour refined molten steel containing rare earth elements into the inlet of the crystallizer, and the first intermediate tank is moved to the standby area to replace the first nozzle. After the first intermediate tank has been poured a second preset number of times, the second intermediate tank is used to pour refined molten steel containing rare earth elements into the inlet of the crystallizer. The first intermediate tank is then moved to the standby area to replace it with a new first intermediate tank. The second preset number of times is greater than the first preset number of times.

[0007] Preferably, after the second intermediate tank has been poured a third preset number of times, the first intermediate tank is used to pour refined molten steel containing rare earth elements into the inlet of the crystallizer, and the second intermediate tank is moved to the standby area to replace the second nozzle. After the second intermediate tank has been poured a fourth preset number of times, the first intermediate tank is used to pour refined molten steel containing rare earth elements into the inlet of the crystallizer. The second intermediate tank is then moved to the standby area to replace it with a new second intermediate tank. The fourth preset number of times is greater than the third preset number of times.

[0008] Preferably, when pouring refined molten steel containing rare earth elements into the inlet of the crystallizer from the second intermediate tank, and moving the first intermediate tank to the standby area to replace the nozzle, or when pouring refined molten steel containing rare earth elements into the inlet of the crystallizer from the second intermediate tank, and moving the first intermediate tank to the standby area to replace the first intermediate tank, the casting speed of the continuous casting machine is controlled to be reduced.

[0009] Preferably, the degree of reduction in the casting speed of the continuous casting machine is determined based on the time required for the first intermediate tank to move to the standby area to replace the nozzle or the time required for the first intermediate tank to move to the standby area to replace the new first intermediate tank, so as to at least ensure that the molten steel in the crystallizer does not experience a break in flow.

[0010] Preferably, when the first intermediate tank and the second intermediate tank are moved to the pouring position above the crystallizer, the first intermediate tank and the second intermediate tank are embedded in each other and there is a gap between them. The first intermediate tank and the second intermediate tank are arranged side by side. The first protruding part of the first intermediate tank is embedded in the second notch part of the second intermediate tank, and the second protruding part of the second intermediate tank is embedded in the first notch part of the first intermediate tank. The first sprue is located at the first protruding part of the first intermediate tank, and the second sprue is located at the second protruding part of the second intermediate tank.

[0011] Preferably, the step of alternately pouring refined molten steel containing rare earth elements into the inlet of the crystallizer using the first intermediate tank and the second intermediate tank to prevent the molten steel in the crystallizer from becoming interrupted includes: Before the first intermediate tank is about to exhaust its supply of refined molten steel containing rare earth elements to the inlet of the crystallizer, the second intermediate tank is moved above the crystallizer and supplies refined molten steel containing rare earth elements to the inlet of the crystallizer. The flow rate of the molten steel supplied by the second intermediate tank to the inlet of the crystallizer is negatively correlated with the flow rate of the molten steel supplied by the first intermediate tank to the inlet of the crystallizer. After the molten steel in the first intermediate tank is used up, the first intermediate tank is removed and replenished with molten steel. Before the second intermediate tank runs out of refined molten steel containing rare earth elements poured into the inlet of the crystallizer, the first intermediate tank, which has been replenished with molten steel, is moved above the crystallizer and poured refined molten steel containing rare earth elements into the inlet of the crystallizer. The flow rate of molten steel poured from the second intermediate tank into the inlet of the crystallizer is negatively correlated with the flow rate of molten steel poured from the first intermediate tank into the inlet of the crystallizer.

[0012] Preferably, the first inlet of the first intermediate tank and the second inlet of the second intermediate tank are respectively provided with a first electromagnetic stirring device for stirring the molten steel flowing through the first inlet and a second electromagnetic stirring device for stirring the molten steel flowing through the second inlet. The first water inlet of the first intermediate tank and the second water inlet of the second intermediate tank are respectively provided with a first electromagnetic induction heating device for heating the molten steel flowing through the first water inlet and a second electromagnetic induction heating device for heating the molten steel flowing through the second water inlet. Before the refined molten steel containing rare earth elements poured from the first intermediate tank into the inlet of the crystallizer is exhausted, the heating power of the first electromagnetic induction heating device is gradually reduced until heating stops, and the first electromagnetic stirring device is stopped stirring. When the second intermediate tank is moved above the crystallizer and refined molten steel containing rare earth elements is poured into the inlet of the crystallizer, the second electromagnetic induction heating device is turned on, and the second electromagnetic stirring device is turned on.

[0013] Preferably, the first electromagnetic stirring device enables the molten steel flowing out of the first nozzle to enter the crystallizer in the form of a jet; the second electromagnetic stirring device enables the molten steel flowing out of the second nozzle to enter the crystallizer in the form of a jet; and a crystallizer electromagnetic stirring device is arranged around the crystallizer to stir the molten steel inside the crystallizer. Before the refined molten steel containing rare earth elements poured from the first intermediate tank to the inlet of the crystallizer is exhausted, when the flow rate of the molten steel poured from the first intermediate tank to the inlet of the crystallizer begins to decrease, the power of the electromagnetic stirring device of the crystallizer is gradually reduced. When the flow rate of molten steel poured from the first intermediate tank to the inlet of the crystallizer is the same as the flow rate of molten steel poured from the second intermediate tank to the inlet of the crystallizer, the power of the electromagnetic stirring device of the crystallizer is reduced to zero, so that the molten steel input into the crystallizer changes from a jet to a double circulation. During the process of the flow rate of molten steel poured from the second intermediate tank to the inlet of the crystallizer reaching its maximum, the direction of the current of the electromagnetic stirring device of the crystallizer is reversed and gradually increased.

[0014] Preferably, the method for producing rare earth steel slabs includes: The solidified billet shell formed after the crystallizer is passed through a continuous casting machine and then to a large reduction rolling mill for rough rolling. The starting temperature of the rough rolling section is controlled at 1200-1300℃. The rough rolling stage involves at least three passes of low-speed, large-deformation rolling, with a single pass reduction rate of 50-60%. The rolling speed of the first pass is 0.25-0.55 m / s, the rolling speed of the second pass is 0.3-0.7 m / s, and the rolling speed of the third pass is 0.7-3.0 m / s. The ending temperature of the rough rolling is controlled at greater than or equal to 1000℃.

[0015] Preferably, in roughing operations on a high-reduction mill, the thickness of the intermediate slab is controlled between 6mm and 18mm.

[0016] Preferably, when the thickness of the intermediate billet is higher than 18 mm, the reduction amount of the first pass is increased.

[0017] Preferably, the method for producing rare earth steel slabs includes: The intermediate billet formed after rough rolling is sent to the induction heating section for induction heating. The temperature of the intermediate billet before entering the induction heating section is controlled between 900℃ and 950℃, the temperature rise of the intermediate billet in the induction heating section is controlled between 210℃ and 320℃, and the temperature of the intermediate billet that finally enters the finishing rolling section is controlled between 1120℃ and 1200℃.

[0018] Preferably, the heating rate of the intermediate billet in the induction heating section is controlled between 15℃ / s and 40.5℃ / s, the movement speed of the intermediate billet in the induction heating section is controlled between 0.35m / s and 1.35m / s, and the total residence time of the intermediate billet in the induction heating section is controlled between 7.5s and 28.5s.

[0019] Preferably, the method for producing rare earth steel slabs includes: The intermediate billet, after being heated in the induction heating section, is subjected to a finishing rolling operation. The finishing rolling stage requires at least 5 passes of intermediate deformation rolling, with the reduction rate per pass controlled between 35% and 40%. The rolling speed of the first pass is controlled between 1.2 m / s and 3.2 m / s, the second pass between 2.0 m / s and 5.5 m / s, the third pass between 3.2 m / s and 9.0 m / s, the fourth pass between 4.2 m / s and 13.5 m / s, and the fifth pass between 5.4 m / s and 17.2 m / s. The temperature of the strip is controlled to be greater than or equal to 800°C at the end of the finishing rolling operation.

[0020] Preferably, the thickness of the strip formed by the finishing rolling process is controlled to be between 0.6 mm and 3 mm; When the thickness of the strip is greater than 3mm, the reduction amount of the first pass is increased.

[0021] The technical solution of the present invention has the following significant beneficial effects: Because the rare earth steel slab production system of this application allows the first and second intermediate tanks to be positioned directly above the inlet of the crystallizer and distributed along the first direction when they are moved above the crystallizer, thus enabling their molten steel to flow into the inlet of the crystallizer, the first and second intermediate tanks can alternately pour refined molten steel containing rare earth elements into the inlet of the crystallizer to prevent the molten steel in the crystallizer from becoming interrupted. Furthermore, after one intermediate tank has poured a first or second preset number of times, the other intermediate tank can pour refined molten steel containing rare earth elements into the inlet of the crystallizer. At this time, the first intermediate tank can be moved to the standby area to replace the first nozzle or replace it with a new intermediate tank. In this way, one of the two intermediate tanks can be continuously poured into the crystallizer, ensuring that the molten steel in the crystallizer does not stop flowing and that production can continue without having to change the nozzle or intermediate tank, thus solving the problem that refined molten steel containing rare earth elements is prone to nodule formation and blockage at the nozzle, which can lead to production interruptions and disruptions to continuous production.

[0022] Specific embodiments of the invention are disclosed in detail below with reference to the description and accompanying drawings, indicating how the principles of the invention can be employed. It should be understood that the embodiments of the invention are not therefore limited in scope. Features described and / or shown for one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments. Attached Figure Description

[0023] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely illustrative to aid in understanding the invention and do not specifically limit the shapes and proportions of the components. Those skilled in the art, guided by the teachings of this invention, can select various possible shapes and proportions to implement the invention according to specific circumstances.

[0024] Figure 1 This is a schematic diagram of the first intermediate tank and the second intermediate tank moving above the crystallizer in an embodiment of the present invention; Figure 2 This is a schematic diagram of the electromagnetic stirring device and electromagnetic induction heating device at the water inlet in an embodiment of the present invention; Figure 3 This describes the flow characteristics of molten steel jetting into the crystallizer under high stirring in an embodiment of the present invention.

[0025] The reference numerals in the above figures are as follows: 1. Crystallizer; 2. First intermediate tank; 21. First nozzle; 22. First protrusion; 23. First notch; 24. First electromagnetic stirring device; 25. Second electromagnetic stirring device; 26. Stopper rod; 27. First turbulence suppressor; 3. Second intermediate tank; 31. Second nozzle; 32. Second protrusion; 33. Second notch; 34. Second turbulence suppressor; 5. Power supply device. Detailed Implementation

[0026] The details of the present invention can be more clearly understood by referring to the accompanying drawings and the description of specific embodiments. However, the specific embodiments of the present invention described herein are for illustrative purposes only and should not be construed as limiting the invention in any way. Under the teachings of this invention, those skilled in the art can conceive of any possible modifications based on the invention, all of which should be considered within the scope of the invention. It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or there may be an intervening element. The terms "mounted," "connected," and "connected" should be interpreted broadly, for example, they can refer to mechanical or electrical connections, or internal communication between two elements, and can be direct or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0028] To address the problem of severe nozzle clogging during rare earth steel continuous casting, which can lead to production interruptions, disruptions, or lengthy production processes, this application proposes a method for producing thin rare earth steel slabs. This method can be applied to a rare earth steel thin slab production system. Figure 1 This is a schematic diagram showing the first intermediate tank 2 and the second intermediate tank 3 moving above the crystallizer 1 in an embodiment of the present invention, as shown below. Figure 1As shown, the rare earth steel slab production system may include: a crystallizer 1, a first intermediate tank 2 and a second intermediate tank 3. The inlet of the crystallizer 1 extends along a first direction. When the first intermediate tank 2 and the second intermediate tank 3 move above the crystallizer 1, the first nozzle 21 of the first intermediate tank 2 and the second nozzle 31 of the second intermediate tank 3 are located directly above the inlet of the crystallizer 1 and distributed along the first direction, so that their molten steel can flow into the inlet of the crystallizer 1.

[0029] When the first intermediate ladle 2 and the second intermediate ladle 3 move above the crystallizer 1, the first nozzle 21 of the first intermediate ladle 2 and the second nozzle 31 of the second intermediate ladle 3 can simultaneously be located directly above the inlet of the crystallizer 1 and distributed along a first direction, allowing their molten steel to simultaneously flow into the inlet of the crystallizer 1. The first nozzle 21 of the first intermediate ladle 2 and the second nozzle 31 of the second intermediate ladle 3 do not interfere with each other. The lower end of the first nozzle 21 of the first intermediate ladle 2 can extend into the inlet of the crystallizer 1, allowing the molten steel from the first intermediate ladle 2 to flow downwards into the crystallizer 1. The lower end of the second nozzle 31 of the second intermediate ladle 3 can extend into the inlet of the crystallizer 1, allowing the molten steel from the second intermediate ladle 3 to flow downwards into the crystallizer 1.

[0030] Specifically, in one particular implementation, such as Figure 1 As shown, when the first intermediate tank 2 and the second intermediate tank 3 are moved above the crystallizer 1 and are in the pouring position, the first intermediate tank 2 and the second intermediate tank 3 are interlocked and distributed with a gap between them. The first intermediate tank 2 and the second intermediate tank 3 are arranged side by side and can extend along a second direction. Alternatively, the second direction can be perpendicular to the first direction. The first protruding part 22 of the first intermediate tank 2 is embedded in the second notch part 33 of the second intermediate tank 3, and the second protruding part 32 of the second intermediate tank 3 is embedded in the first notch part 23 of the first intermediate tank 2. The first gate 21 is located at the first protruding part 22 of the first intermediate tank 2, and the second gate 31 is located at the second protruding part 32 of the second intermediate tank 3. In this way, the first intermediate tank 2 and the second intermediate tank 3 can simultaneously pour water into the crystallizer 1 through their respective first gate 21 and second gate 31 without interfering with each other.

[0031] As a feasible option, such as Figure 1 As shown, a first turbulence suppressor 27 can be installed in the first intermediate tank 2, and the first turbulence suppressor 27 can be installed on the side away from the first inlet 21. A second turbulence suppressor 34 can be installed in the second intermediate tank 3, and the second turbulence suppressor 34 can be installed on the side away from the second inlet 31.

[0032] The method for producing rare earth steel slabs in this application may include the following steps: A first intermediate tank 2 and a second intermediate tank 3 are used to alternately pour refined molten steel containing rare earth elements into the inlet of crystallizer 1 to ensure that the flow of molten steel in crystallizer 1 is uninterrupted. Due to the structure of the rare earth steel slab production system, the first intermediate tank 2 and the second intermediate tank 3 can alternately pour refined molten steel containing rare earth elements into the inlet of crystallizer 1. When one intermediate tank is pouring molten steel into the inlet of crystallizer 1, the other intermediate tank can be moved aside to replenish molten steel. Then, before one intermediate tank finishes pouring molten steel into the inlet of crystallizer 1, it can be moved above crystallizer 1 to continue pouring molten steel into the inlet of crystallizer 1, thus ensuring that the pouring of molten steel into crystallizer 1 is uninterrupted. Alternatively, for a short period after one intermediate tank finishes pouring molten steel into the inlet of crystallizer 1, the other intermediate tank, having replenished its molten steel, can be moved above crystallizer 1 to continue pouring molten steel into the inlet of crystallizer 1. During this short period, molten steel remains in crystallizer 1, and the output of molten steel from crystallizer 1 will not be interrupted.

[0033] After the first intermediate tank 2 has reached the first preset number of pouring times, the second intermediate tank 3 is used to pour refined molten steel containing rare earth elements into the inlet of the crystallizer 1, and the first intermediate tank 2 is moved to the standby area to replace the first nozzle 21.

[0034] In the above steps, after the first preset number of pours, the nozzle of the first intermediate tank 2 will form nodules to a certain extent. Therefore, when the second intermediate tank 3 pours refined molten steel containing rare earth elements into the inlet of the crystallizer 1, the first intermediate tank 2 can be moved to the standby area to replace the first nozzle 21. Then, molten steel is replenished and the tank is moved to the top of the crystallizer 1 to continue pouring molten steel into the inlet of the crystallizer 1, so that the pouring of molten steel into the crystallizer 1 does not stop.

[0035] In the above steps, when pouring refined molten steel containing rare earth elements into the inlet of the crystallizer 1 from the second intermediate tundish 3, and moving the first intermediate tundish 2 to the standby area to replace the nozzle, or when pouring refined molten steel containing rare earth elements into the inlet of the crystallizer 1 from the second intermediate tundish 3, and moving the first intermediate tundish 2 to the standby area to replace it with a new one, the casting speed of the continuous casting machine is reduced. This method reduces the consumption of molten steel in the crystallizer 1, thus allowing more time for moving the first intermediate tundish 2 to the standby area to replace the nozzle or to replace it with a new one, avoiding insufficient time to replace the nozzle or replace the first intermediate tundish 2. Generally, the first preset number of cycles can be controlled to around 5-6.

[0036] Furthermore, the degree of reduction in the casting speed of the continuous casting machine is determined based on the time required for the first tundish 2 to move to the standby area to replace the nozzle or the time required for the first tundish 2 to move to the standby area to replace the new first tundish 2, so as to at least ensure that the molten steel in the crystallizer 1 does not experience interruption. The longer the time required to replace the nozzle or replace the new first tundish 2, the greater the reduction in the casting speed of the continuous casting machine can be, and vice versa.

[0037] After the first intermediate tank 2 has reached the second preset number of pours, the second intermediate tank 3 is used to pour refined molten steel containing rare earth elements into the inlet of the crystallizer 1. The first intermediate tank 2 is then moved to the standby area to be replaced with a new one. The second preset number of pours is greater than the first preset number of pours. Generally, the second preset number of pours can be controlled to be around 10-11 times.

[0038] When the number of pouring operations of the first intermediate tank 2 reaches the second preset number, and the wear and tear of the refractory material, nozzle, and stopper rod 26 of the first intermediate tank 2 reaches a certain level, in order to ensure stable production and the quality of the molten steel, the first intermediate tank 2 needs to be replaced as a whole. When the second intermediate tank 3 pours refined molten steel containing rare earth elements into the inlet of the crystallizer 1, the first intermediate tank 2 can be moved to the standby area to replace it with a new one. After that, molten steel is replenished, and then it is moved above the crystallizer 1 to continue pouring molten steel into the inlet of the crystallizer 1, so that the pouring of molten steel into the crystallizer 1 does not stop.

[0039] Similarly, after the second intermediate tank 3 has been poured a third preset number of times, the first intermediate tank 2 is used to pour refined molten steel containing rare earth elements into the inlet of the crystallizer 1, and the second intermediate tank 3 is moved to the standby area to replace the second nozzle 31. After the second intermediate tank 3 has been poured a fourth preset number of times, the first intermediate tank 2 is used to pour refined molten steel containing rare earth elements into the inlet of the crystallizer 1, and the second intermediate tank 3 is moved to the standby area to replace it with a new second intermediate tank 3. The fourth preset number of times is greater than the third preset number of times.

[0040] Because the rare earth steel slab production system of this application has the first nozzle 21 of the first intermediate tank 2 and the second nozzle 31 of the second intermediate tank 3 located directly above the inlet of the crystallizer 1 and distributed along the first direction when the first intermediate tank 2 and the second intermediate tank 3 are moved above the crystallizer 1, and their molten steel can flow into the inlet of the crystallizer 1, the first intermediate tank 2 and the second intermediate tank 3 can alternately pour refined molten steel containing rare earth elements into the inlet of the crystallizer 1 so that the molten steel in the crystallizer 1 does not stop flowing. On this basis, when the number of pouring in one of the intermediate tanks reaches the first preset number or the second preset number, the other intermediate tank can pour refined molten steel containing rare earth elements into the inlet of the crystallizer 1. At this time, the first intermediate tank can be moved to the standby area to replace the first nozzle 21 or replace the new intermediate tank. In this way, one of the two intermediate tanks can be continuously poured into crystallizer 1, ensuring that the molten steel in crystallizer 1 does not stop flowing, thus ensuring continuous production. This avoids slowing down the production pace due to the need to change the nozzle and intermediate tank, thereby solving the problem of production interruption and continuous production caused by the formation and blockage of refined molten steel containing rare earth elements at the nozzle.

[0041] In one feasible implementation, the step of alternately pouring refined molten steel containing rare earth elements into the inlet of the crystallizer 1 from the first intermediate tank 2 and the second intermediate tank 3 to ensure that the molten steel in the crystallizer 1 does not experience interruption may include: Before the refined molten steel containing rare earth elements poured from the first intermediate tank 2 into the inlet of the crystallizer 1 is exhausted, the second intermediate tank 3 is moved above the crystallizer 1 and pours refined molten steel containing rare earth elements into the inlet of the crystallizer 1. The flow rate of molten steel poured from the second intermediate tank 3 into the inlet of the crystallizer 1 is negatively correlated with the flow rate of molten steel poured from the first intermediate tank 2 into the inlet of the crystallizer 1. Through this step, since the molten steel in the first intermediate tank 2 is about to be exhausted, the flow rate of molten steel poured into the crystallizer 1 will gradually decrease. The above method ensures that the total flow rate of molten steel poured from the first intermediate tank 2 and the second intermediate tank 3 into the inlet of the crystallizer 1 will not decrease too much or will remain roughly the same as before. Furthermore, the flow rate of molten steel poured from the second intermediate tank 3 to the inlet of the crystallizer 1 can be kept constant when added to the flow rate of molten steel poured from the first intermediate tank 2 to the inlet of the crystallizer 1. For example, the flow rate of molten steel poured from the first intermediate tank 2 to the inlet of the crystallizer 1 under normal conditions (when the first intermediate tank 2 and the second intermediate tank 3 are not alternating).

[0042] After the molten steel in the first intermediate ladle 2 is used up, the first intermediate ladle 2 is removed and replenished with molten steel.

[0043] Before the refined molten steel containing rare earth elements poured from the second intermediate tank 3 into the inlet of the crystallizer 1 is exhausted, the first intermediate tank 2, after being replenished with molten steel, is moved above the crystallizer 1 and poured refined molten steel containing rare earth elements into the inlet of the crystallizer 1. The flow rate of molten steel poured from the second intermediate tank 3 into the inlet of the crystallizer 1 is negatively correlated with the flow rate of molten steel poured from the first intermediate tank 2 into the inlet of the crystallizer 1. Several methods for achieving this negative correlation between the flow rate of molten steel poured from the second intermediate tank 3 into the inlet of the crystallizer 1 and the flow rate of molten steel poured from the first intermediate tank 2 into the inlet of the crystallizer 1 are similar to those described above and will not be elaborated upon here.

[0044] In one alternative implementation, Figure 2 This is a schematic diagram of the electromagnetic stirring device and electromagnetic induction heating device at the water inlet in an embodiment of the present invention, as shown below. Figure 2 As shown, the first nozzle 21 of the first intermediate tank 2 and the second nozzle 31 of the second intermediate tank 3 are respectively equipped with a first electromagnetic stirring device 24 for stirring the molten steel flowing through the first nozzle 21 and a second electromagnetic stirring device 25 for stirring the molten steel flowing through the second nozzle 31. Furthermore, the first electromagnetic stirring device 24 enables the molten steel flowing out of the first nozzle 21 to enter the crystallizer 1 in a jet form. The second electromagnetic stirring device 25 enables the molten steel flowing out of the second nozzle 31 to enter the crystallizer 1 in a jet form. The first electromagnetic stirring device 24 is connected to its corresponding power supply device 5; the second electromagnetic stirring device 25 is also connected to its corresponding power supply device 5. The electromagnetic stirring devices can stir the molten steel flowing through the nozzles to accelerate the flotation of the deoxidation product, alumina inclusions. Additionally, the electromagnetic stirring devices can accelerate the outflow of the molten steel through the nozzles, allowing it to enter the crystallizer 1 in a jet form, facilitating diffusion within the crystallizer 1 and mitigating nozzle blockage to some extent.

[0045] In one alternative implementation, such as Figure 2As shown, the first nozzle 21 of the first intermediate tank 2 and the second nozzle 31 of the second intermediate tank 3 are respectively equipped with a first electromagnetic induction heating device for heating the molten steel flowing through the first nozzle 21 and a second electromagnetic induction heating device for heating the molten steel flowing through the second nozzle 31. The first electromagnetic induction heating device is connected to its corresponding power supply device 5. The second electromagnetic induction heating device is also connected to its corresponding power supply device 5. The electromagnetic induction heating device can increase the temperature of the molten steel in the nozzle. Since the nozzle of the intermediate tank is prone to blockage during production, increasing the temperature of the molten steel in this area can reduce the viscosity of inclusions such as rare earth oxides and rare earth sulfides in the molten steel, improve its fluidity, and make it easier for rare earth inclusions to flow out of the nozzle. It can also cause rare earth inclusions that have adhered to the nozzle and are used to control the flow of molten steel into the nozzle to fall off and flow into the nozzle, improving the nozzle nodule formation and blockage phenomenon. In addition, it can also prevent the condensation of molten steel in the nozzle, further suppressing the nozzle nodule problem. This method enables the production of rare earth steels of different grades, reducing the carbon content and carbon equivalent of steel materials while ensuring strength and toughness.

[0046] Electromagnetic induction heating and electromagnetic stirring devices can suppress nozzle clogging, thereby reducing the frequency of nozzle and intermediate tank replacement.

[0047] Optionally, the electromagnetic stirring device can be positioned higher than the electromagnetic induction heating device at a sprue. For example, the output frequency of the electromagnetic induction heating coil in the electromagnetic induction heating device can be between 3kHz and 10kHz, the current between 100A and 1000A, and the voltage 380V. When the electromagnetic induction heating device is working, the current can vary from 100A to 1000A, and the frequency of the current variation can be adjusted according to the degree of nodule formation in the sprue.

[0048] Based on the above structure, as feasible, before the refined molten steel containing rare earth elements poured from the first intermediate tank 2 into the inlet of the crystallizer 1 is exhausted, the heating power of the first electromagnetic induction heating device can be gradually reduced until heating stops, and the first electromagnetic stirring device 24 can be stopped stirring. When the second intermediate tank 3 is moved above the crystallizer 1 and the refined molten steel containing rare earth elements is poured into the inlet of the crystallizer 1, the second electromagnetic induction heating device and the second electromagnetic stirring device 25 are turned on.

[0049] An electromagnetic stirring device for crystallizer 1 is installed around crystallizer 1 to agitate the molten steel inside. The agitation by the electromagnetic stirring device for crystallizer 1 ensures that the molten steel is evenly distributed within crystallizer 1. Figure 3 The flow characteristics of molten steel jetting into crystallizer 1 under high stirring are shown in the embodiment of the present invention, such as... Figure 3As shown, since the first nozzle 21 of the first intermediate tank 2 and the second nozzle 31 of the second intermediate tank 3 extend into completely different positions in the crystallizer 1, i.e., on both sides of the crystallizer 1, the molten steel input into the crystallizer 1 from the first nozzle 21 of the first intermediate tank 2 or the second nozzle 31 of the second intermediate tank 3 needs to be regulated by the electromagnetic stirring device of the crystallizer 1 to achieve rapid and uniform diffusion. Furthermore, the electromagnetic stirring device of the crystallizer 1 requires a relatively large stirring force. The current of the electromagnetic stirring coil in the electromagnetic stirring device of the crystallizer 1 can be controlled between 100A and 300A. When the coil is working, the direction of the coil current is adjusted according to the nozzle position to control the direction of the electromagnetic drive flow, thereby allowing the molten steel jet from the nozzle to diffuse throughout the entire crystallizer 1.

[0050] In an optional implementation, before the refined molten steel containing rare earth elements poured from the first intermediate tank 2 into the inlet of the crystallizer 1 is exhausted, as the flow rate of the molten steel poured from the first intermediate tank 2 into the inlet of the crystallizer 1 begins to decrease, the power of the electromagnetic stirring device in the crystallizer 1 is gradually reduced. In this step, the power of the electromagnetic stirring device in the crystallizer 1 can be reduced to zero in advance when the refined molten steel containing rare earth elements poured from the first intermediate tank 2 into the inlet of the crystallizer 1 is almost exhausted. Correspondingly, in the above process, the first electromagnetic stirring device 24 and the first electromagnetic induction heating device can be controlled to stop stirring and stop heating before the refined molten steel containing rare earth elements poured from the first intermediate tank 2 into the inlet of the crystallizer 1 is almost exhausted.

[0051] When the flow rate of molten steel poured from the first intermediate tank 2 to the inlet of the crystallizer 1 is the same as the flow rate of molten steel poured from the second intermediate tank 3 to the inlet of the crystallizer 1, the power of the electromagnetic stirring device in the crystallizer 1 can be reduced to zero, so that the molten steel input into the crystallizer 1 changes from a jet to a double circulation. This double circulation is caused by the operation of the first electromagnetic stirring device 24 corresponding to the first nozzle 21 and the second electromagnetic stirring device 25 corresponding to the second nozzle 31. In this step, after the second intermediate tank 3 is moved above the crystallizer 1, the second electromagnetic stirring device 25 is activated for stirring and the second electromagnetic induction heating device is activated for heating, and then the stopper rod 26 is slowly raised.

[0052] During the process where the flow rate of molten steel poured from the second intermediate tank 3 into the inlet of the crystallizer 1 reaches its maximum, the current direction of the electromagnetic stirring device controlling the crystallizer 1 is reversed and gradually increased. During this process, the molten steel in the crystallizer 1 becomes a jet stream opposite to its initial direction. By switching between the first intermediate tank 2 and the second intermediate tank 3, the stirring direction of the electromagnetic stirring device in the crystallizer 1 can be switched with relatively low energy consumption. Otherwise, at other times, because the intermediate tanks consistently supply molten steel to the crystallizer 1 at a relatively high and normal flow rate, the electromagnetic stirring device in the crystallizer 1 will stir in one direction to ensure the molten steel diffuses throughout the entire crystallizer 1. Switching the stirring direction would affect the diffusion of the newly supplied large amount of molten steel, and since the molten steel in the crystallizer 1 rotates in one direction, switching to another direction would consume a large amount of electrical energy from the electromagnetic stirring device.

[0053] To ensure the production rhythm of the rare earth steel production line, the equipment used needs to have production speeds and temperature drops that match the process requirements, ensuring a short process flow and thus improving production efficiency and increasing output. The rare earth steel thin slab production method includes: passing the solidified slab shell formed after crystallizer 1 through a continuous casting machine to a high-reduction rolling mill for rough rolling. The initial temperature of the rough rolling section is controlled at 1200-1300℃, and at least three passes of low-speed, large-deformation rolling are performed during the rough rolling stage. The reduction rate per pass is 50-60%. The rolling speed for the first pass is 0.25-0.55 m / s, the second pass is 0.3-0.7 m / s, and the third pass is 0.7-3.0 m / s. The final temperature of the rough rolling is controlled at ≥1000℃. Furthermore, during the rough rolling operation on the high-reduction rolling mill, the thickness of the intermediate slab is controlled between 6mm and 18mm. When the thickness of the intermediate billet is greater than 18mm, the reduction amount needs to be increased, preferably by increasing the reduction amount of the first pass.

[0054] Furthermore, the rare earth steel slab production method includes: feeding the intermediate slab formed after rough rolling into an induction heating section for induction heating. Specifically, the temperature of the intermediate slab before entering the induction heating section is controlled between 900℃ and 950℃, the temperature rise of the intermediate slab in the induction heating section is controlled between 210℃ and 320℃, and the temperature of the intermediate slab finally entering the finishing rolling section is controlled between 1120℃ and 1200℃.

[0055] To control the amount of iron oxide scale formation, the heating rate of the induction heating section is relatively fast. The heating rate of the intermediate billet in the induction heating section is controlled between 15℃ / s and 40.5℃ / s, the movement speed of the intermediate billet in the induction heating section is controlled between 0.35m / s and 1.35m / s, and the total residence time of the intermediate billet in the induction heating section is controlled between 7.5s and 28.5s.

[0056] Alternatively, the production method for rare earth steel slabs may include: performing a finishing rolling operation on an intermediate slab heated by induction heating. The finishing rolling stage requires at least five passes of intermediate deformation rolling, with a single-pass reduction rate controlled between 35% and 40%. The rolling speed for the first pass is controlled between 1.2 m / s and 3.2 m / s, the second pass between 2.0 m / s and 5.5 m / s, the third pass between 3.2 m / s and 9.0 m / s, the fourth pass between 4.2 m / s and 13.5 m / s, and the fifth pass between 5.4 m / s and 17.2 m / s. The temperature of the strip at the end of the finishing rolling operation is controlled to be greater than or equal to 800℃. Furthermore, the thickness of the strip formed after the finishing rolling operation is controlled to be between 0.6 mm and 3 mm. When the strip thickness is greater than 3 mm, the reduction needs to be increased, with priority given to increasing the reduction in the first pass.

[0057] Afterward, the strip steel product needs to undergo laminar flow cooling, slitting, shearing, and then re-forming. After laminar flow cooling, a surface coating can be applied to ensure insulation. Then, it is slitting, shearing, and re-forming to obtain rare earth oriented silicon steel.

[0058] Example 1

[0059] This embodiment processes and obtains a rare earth-oriented silicon steel. By weight percentage, the main element contents are: C: 0.04-0.06wt%, Si: 3.2-4.1wt%, Mn: 0.05-0.15wt%, Al: 0.028-0.036wt%. In addition, appropriate amounts of Ce or La elements need to be added during the refining of the molten steel, and their proportion in the molten steel is: 0.003-0.0042wt%.

[0060] After passing through crystallizer 1, the molten rare earth steel forms a solidified billet shell and moves with the continuous casting machine to the large reduction rolling mill to start rough rolling. The starting temperature of the rough rolling section is controlled between 1250℃ and 1290℃. The rough rolling stage has three passes of low-speed, large-deformation rolling: the single-pass reduction rate is 52-58%. The rolling speed of the first pass is controlled between 0.25m / s and 0.55m / s, the rolling speed of the second pass is controlled between 0.3m / s and 0.7m / s, and the rolling speed of the third pass is controlled between 0.7m / s and 3.0m / s. The finishing temperature of the rough rolling is controlled to be greater than or equal to 1050℃. The thickness of the intermediate billet after passing through a high-reduction rolling mill should be controlled between 7mm and 15mm. When the thickness of the intermediate billet is higher than 15mm, the reduction amount needs to be increased, and the reduction amount of the first pass should be increased first.

[0061] After the intermediate billet passes through the roughing mill and the head billet is removed by the swing shear, it enters the induction heating section. The temperature of the intermediate billet before entering the induction heating section is controlled between 920℃ and 930℃. The temperature rise of the intermediate billet in the heating section is controlled between 250℃ and 310℃. The temperature of the intermediate billet that finally enters the finishing mill is controlled between 1150℃ and 1180℃.

[0062] In order to control the amount of iron oxide scale formation, the heating rate of the induction heating section is relatively fast, and the temperature rise range is controlled within 25℃ / s-38℃ / s. The movement speed of the intermediate billet in the induction heating section is controlled at 0.35-1.35m / s, and the total residence time is controlled at 11s-24s.

[0063] After passing through the induction heating section, the intermediate billet undergoes finish rolling, which consists of five passes of medium deformation rolling: the reduction rate per pass is controlled at 38%-40%, the rolling speed of the first pass is controlled between 1.2 m / s and 3.2 m / s, the second pass between 2.0 m / s and 5.5 m / s, the third pass between 3.2 m / s and 9.0 m / s, the fourth pass between 4.2 m / s and 13.5 m / s, and the fifth pass between 5.4 m / s and 17.2 m / s, and the finish rolling temperature is controlled to be greater than or equal to 850℃. The thickness of the strip after finish rolling is controlled between 0.6 mm and 2.5 mm. When the thickness of the strip exceeds 2.5 mm, the reduction needs to be increased, prioritizing increasing the reduction in the first pass. After precision rolling, the rare earth silicon steel sheet is cooled to room temperature by laminar flow and then coated with a coating to ensure insulation. The product is then slit, sheared, and rolled into shape to obtain rare earth oriented silicon steel.

[0064] All articles and references disclosed herein, including patent applications and publications, are incorporated herein by reference for various purposes. The term “substantially constitutes…” used to describe a combination should include the identified element, component, part, or step, as well as other elements, components, parts, or steps that do not substantially affect the essential novelty of the combination. The use of the terms “comprising” or “including” to describe combinations of elements, components, parts, or steps herein also contemplates embodiments substantially constituted by such elements, components, parts, or steps. The use of the term “may” herein is intended to indicate that any described attribute “may” include is optional. Multiple elements, components, parts, or steps can be provided by a single integrated element, component, part, or step. Alternatively, a single integrated element, component, part, or step can be divided into multiple separate elements, components, parts, or steps. The disclosure of “a” or “an” used to describe an element, component, part, or step does not imply exclusion of other elements, components, parts, or steps.

[0065] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for producing rare earth steel thin slabs, characterized in that, The rare earth steel slab production system includes: a crystallizer, a first intermediate tank and a second intermediate tank. The inlet of the crystallizer extends along a first direction. When the first intermediate tank and the second intermediate tank move above the crystallizer, the first nozzle of the first intermediate tank and the second nozzle of the second intermediate tank are located directly above the inlet of the crystallizer and distributed along the first direction, so that their molten steel can flow into the inlet of the crystallizer. The method for producing rare earth steel slabs includes: The first intermediate tank and the second intermediate tank are used to alternately pour refined molten steel containing rare earth elements into the inlet of the crystallizer to ensure that the molten steel in the crystallizer does not stop flowing. After the first intermediate tank has been poured a first preset number of times, the second intermediate tank is used to pour refined molten steel containing rare earth elements into the inlet of the crystallizer, and the first intermediate tank is moved to the standby area to replace the first nozzle. After the first intermediate tank has been poured a second preset number of times, the second intermediate tank is used to pour refined molten steel containing rare earth elements into the inlet of the crystallizer. The first intermediate tank is then moved to the standby area to replace it with a new first intermediate tank. The second preset number of times is greater than the first preset number of times.

2. The method for producing rare earth steel thin slabs according to claim 1, characterized in that, After the second intermediate tank has been poured a third preset number of times, the first intermediate tank is poured into the inlet of the crystallizer with refined molten steel containing rare earth elements, and the second intermediate tank is moved to the standby area to replace the second nozzle. After the second intermediate tank has been poured a fourth preset number of times, the first intermediate tank is used to pour refined molten steel containing rare earth elements into the inlet of the crystallizer. The second intermediate tank is then moved to the standby area to replace it with a new second intermediate tank. The fourth preset number of times is greater than the third preset number of times.

3. The method for producing rare earth steel thin slabs according to claim 1, characterized in that, When pouring refined molten steel containing rare earth elements into the inlet of the crystallizer from the second intermediate tank, and moving the first intermediate tank to the standby area to replace the nozzle, or when pouring refined molten steel containing rare earth elements into the inlet of the crystallizer from the second intermediate tank, and moving the first intermediate tank to the standby area to replace the first intermediate tank, the casting speed of the continuous casting machine is reduced.

4. The method for producing rare earth steel thin slabs according to claim 3, characterized in that, The degree of reduction in casting speed of the continuous casting machine is determined based on the time required for the first intermediate tank to move to the standby area to replace the nozzle or the time required for the first intermediate tank to move to the standby area to replace the new first intermediate tank, so as to at least ensure that the molten steel in the crystallizer does not experience a break in flow.

5. The method for producing rare earth steel thin slabs according to claim 1, characterized in that, When the first intermediate tank and the second intermediate tank move to the pouring position above the crystallizer, the first intermediate tank and the second intermediate tank are embedded in each other and there is a gap between them. The first intermediate tank and the second intermediate tank are arranged side by side. The first protruding part of the first intermediate tank is embedded in the second notch part of the second intermediate tank, and the second protruding part of the second intermediate tank is embedded in the first notch part of the first intermediate tank. The first sprue is located at the first protruding part of the first intermediate tank, and the second sprue is located at the second protruding part of the second intermediate tank.

6. The method for producing rare earth steel thin slabs according to claim 1, characterized in that, The step of alternately pouring refined molten steel containing rare earth elements into the inlet of the crystallizer using the first intermediate tank and the second intermediate tank to ensure that the molten steel flow in the crystallizer is not interrupted includes: Before the first intermediate tank is about to exhaust its supply of refined molten steel containing rare earth elements to the inlet of the crystallizer, the second intermediate tank is moved above the crystallizer and supplies refined molten steel containing rare earth elements to the inlet of the crystallizer. The flow rate of the molten steel supplied by the second intermediate tank to the inlet of the crystallizer is negatively correlated with the flow rate of the molten steel supplied by the first intermediate tank to the inlet of the crystallizer. After the molten steel in the first intermediate tank is used up, the first intermediate tank is removed and replenished with molten steel. Before the second intermediate tank runs out of refined molten steel containing rare earth elements poured into the inlet of the crystallizer, the first intermediate tank, which has been replenished with molten steel, is moved above the crystallizer and poured refined molten steel containing rare earth elements into the inlet of the crystallizer. The flow rate of molten steel poured from the second intermediate tank into the inlet of the crystallizer is negatively correlated with the flow rate of molten steel poured from the first intermediate tank into the inlet of the crystallizer.

7. The method for producing rare earth steel thin slabs according to claim 6, characterized in that, The first water inlet of the first intermediate tank and the second water inlet of the second intermediate tank are respectively provided with a first electromagnetic stirring device that stirs the molten steel flowing through the first water inlet and a second electromagnetic stirring device that stirs the molten steel flowing through the second water inlet. The first water inlet of the first intermediate tank and the second water inlet of the second intermediate tank are respectively provided with a first electromagnetic induction heating device for heating the molten steel flowing through the first water inlet and a second electromagnetic induction heating device for heating the molten steel flowing through the second water inlet. Before the refined molten steel containing rare earth elements poured from the first intermediate tank into the inlet of the crystallizer is exhausted, the heating power of the first electromagnetic induction heating device is gradually reduced until heating stops, and the first electromagnetic stirring device is stopped stirring. When the second intermediate tank is moved above the crystallizer and refined molten steel containing rare earth elements is poured into the inlet of the crystallizer, the second electromagnetic induction heating device is turned on, and the second electromagnetic stirring device is turned on.

8. The method for producing rare earth steel thin slabs according to claim 7, characterized in that, The first electromagnetic stirring device enables the molten steel flowing out of the first nozzle to enter the crystallizer in the form of a jet; the second electromagnetic stirring device enables the molten steel flowing out of the second nozzle to enter the crystallizer in the form of a jet; and a crystallizer electromagnetic stirring device is arranged around the crystallizer to stir the molten steel inside the crystallizer. Before the refined molten steel containing rare earth elements poured from the first intermediate tank to the inlet of the crystallizer is exhausted, when the flow rate of the molten steel poured from the first intermediate tank to the inlet of the crystallizer begins to decrease, the power of the electromagnetic stirring device of the crystallizer is gradually reduced. When the flow rate of molten steel poured from the first intermediate tank to the inlet of the crystallizer is the same as the flow rate of molten steel poured from the second intermediate tank to the inlet of the crystallizer, the power of the electromagnetic stirring device of the crystallizer is reduced to zero, so that the molten steel input into the crystallizer changes from a jet to a double circulation. During the process of the flow rate of molten steel poured from the second intermediate tank to the inlet of the crystallizer reaching its maximum, the direction of the current of the electromagnetic stirring device of the crystallizer is reversed and gradually increased.

9. The method for producing rare earth steel thin slabs according to claim 1, characterized in that, The method for producing rare earth steel slabs includes: The solidified billet shell formed after the crystallizer is passed through a continuous casting machine and then to a large reduction rolling mill for rough rolling. The starting temperature of the rough rolling section is controlled at 1200-1300℃. The rough rolling stage involves at least three passes of low-speed, large-deformation rolling, with a single pass reduction rate of 50-60%. The rolling speed of the first pass is 0.25-0.55 m / s, the rolling speed of the second pass is 0.3-0.7 m / s, and the rolling speed of the third pass is 0.7-3.0 m / s. The ending temperature of the rough rolling is controlled at greater than or equal to 1000℃.

10. The method for producing rare earth steel thin slabs according to claim 9, characterized in that, In roughing operations on a high-reduction rolling mill, the thickness of the intermediate slab is controlled between 6mm and 18mm.

11. The method for producing rare earth steel thin slabs according to claim 10, characterized in that, When the thickness of the intermediate billet is higher than 18mm, adjust and increase the reduction amount of the first pass.

12. The method for producing rare earth steel thin slabs according to claim 9, characterized in that, The method for producing rare earth steel slabs includes: The intermediate billet formed after rough rolling is sent to the induction heating section for induction heating. The temperature of the intermediate billet before entering the induction heating section is controlled between 900℃ and 950℃, the temperature rise of the intermediate billet in the induction heating section is controlled between 210℃ and 320℃, and the temperature of the intermediate billet that finally enters the finishing rolling section is controlled between 1120℃ and 1200℃.

13. The method for producing rare earth steel thin slabs according to claim 12, characterized in that, The heating rate of the intermediate billet in the induction heating section is controlled between 15℃ / s and 40.5℃ / s, the movement speed of the intermediate billet in the induction heating section is controlled between 0.35m / s and 1.35m / s, and the total residence time of the intermediate billet in the induction heating section is controlled between 7.5s and 28.5s.

14. The method for producing rare earth steel thin slabs according to claim 12, characterized in that, The method for producing rare earth steel slabs includes: The intermediate billet, after being heated in the induction heating section, is subjected to a finishing rolling operation. The finishing rolling stage requires at least 5 passes of intermediate deformation rolling, with the reduction rate per pass controlled between 35% and 40%. The rolling speed of the first pass is controlled between 1.2 m / s and 3.2 m / s, the second pass between 2.0 m / s and 5.5 m / s, the third pass between 3.2 m / s and 9.0 m / s, the fourth pass between 4.2 m / s and 13.5 m / s, and the fifth pass between 5.4 m / s and 17.2 m / s. The temperature of the strip is controlled to be greater than or equal to 800°C at the end of the finishing rolling operation.

15. The method for producing rare earth steel thin slabs according to claim 14, characterized in that, The thickness of the strip formed after the finishing rolling process is controlled to be between 0.6 mm and 3 mm; When the thickness of the strip is greater than 3mm, the reduction amount of the first pass is increased.

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