Low-temperature high-magnetic-induction oriented silicon steel with excellent bottom layer and magnetic performance and preparation method of low-temperature high-magnetic-induction oriented silicon steel

Abstract

The invention belongs to the technical field of high-magnetic-induction oriented silicon steel, and discloses low-temperature high-magnetic-induction oriented silicon steel with excellent bottom layer and magnetic performance and a preparation method of the low-temperature high-magnetic-induction oriented silicon steel. When the oriented silicon steel is decarburized and annealed, the temperature rise rate of the heating section of the decarburization annealing and the atmosphere partial pressure # imgabs0 # of the heating section are adjusted according to the C content after the oriented silicon steel is smelted, so that the temperature of the soaking section of the decarburization annealing and the time of the soaking section are further adjusted, on one hand, the decarburization reaction can be smoothly carried out, and the C content of the oriented silicon steel is controlled to be 15 ppm or below; and on the other hand, the thickness and uniformity of an oxidation film formed on the surface of the steel plate in the decarburization process can be controlled, so that the low-temperature high-magnetic-induction oriented silicon steel with excellent bottom layer and magnetic performance is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of high magnetic induction oriented silicon steel, and in particular relates to a method for preparing low-temperature high magnetic induction oriented silicon steel with excellent bottom layer and magnetic properties. Background Art

[0002] High magnetic induction oriented silicon steel is an important soft magnetic material, which is widely used in power transmission and transformation industries such as large transformers. There are generally two production methods for high magnetic induction oriented silicon steel: one production method is called high temperature high magnetic induction oriented silicon steel manufacturing method, in which the inhibitor is given by the addition of chemical elements in the steelmaking process. In order to make the inhibitor fully dissolved, the ingot is heated to 1360-1400℃ before rolling. Due to the high heating temperature of the ingot, a series of problems such as high energy consumption, low yield rate and poor productivity are prone to occur. At present, another method is mainly used to produce high magnetic induction oriented silicon steel, which makes the heating temperature of the ingot lower than 1200℃ and has good productivity. The inhibitor is obtained by nitriding after decarburization annealing, which is an acquired inhibitor. The oriented silicon steel produced by this method is called low temperature high magnetic induction oriented silicon steel.

[0003] The manufacturing process of low-temperature high-magnetic induction oriented silicon steel mainly includes: steelmaking, hot rolling, pickling and normalizing, cold rolling, decarburization annealing, nitriding, coating of magnesium oxide isolation agent, high-temperature annealing, coating of insulating coating, flat stretching annealing, finishing, etc. In the production process of low-temperature oriented silicon steel, a long period of decarburization annealing is generally required to reduce the C content in the steel to below 30ppm in order to obtain oriented silicon steel with excellent magnetic properties, and the lower the C content, the better the magnetic properties.

[0004] Patent CN106755874A proposes a decarburization and nitriding annealing method for producing low-temperature high-magnetic induction oriented silicon steel. 13 / 50 The temperature, time and ammonia content in the nitriding atmosphere of decarburization annealing are adjusted by the value and nitriding amount, so as to obtain low-temperature high magnetic induction oriented silicon steel with excellent magnetic properties. This method needs to adjust the decarburization and nitriding process by predicting the magnetic properties of the decarburized plate. The error between the predicted result and the actual result is large, and the adjustment process is cumbersome, which is not suitable for large-scale on-site production.

[0005] Patent CN113249554A discloses a decarburization annealing process for high magnetic induction oriented silicon steel, with an ammonia flow rate of 6-20m 3 / h, humidification tank temperature 30-70℃, decarburization temperature 780-880℃, unit speed 45-75m / min, hydrogen ratio 20-60% in the atmosphere, nitrogen ratio 40-80%, through the optimization design of the decarburization annealing process of high magnetic induction oriented silicon steel, the parameters such as ammonia flow, atmosphere, humidification tank water temperature in the decarburization annealing process were adjusted, and the content of carbon, nitrogen and oxygen in high magnetic induction oriented silicon steel was optimized, and finally the high magnetic induction oriented silicon steel achieved stable performance, and the magnetic induction reached 1.92T. This method mainly increases the nitriding amount of the steel strip after decarburization through the design of the annealing furnace, without considering the decarburization process of the steel plate before nitriding, and the iron loss of the steel plate obtained is relatively high, greater than 1.0w / kg.

[0006] Patent CN102758127A proposes a method for producing high magnetic induction oriented silicon steel with excellent magnetic properties and good bottom layer. This method mainly controls the thickness of the SiO2 oxide layer through a special nitriding process. By forming an oxide layer of suitable thickness and a suitable proportion of SiO2 outside the nitriding layer, it is beneficial for the oxide layer to form a bottom layer earlier during high-temperature annealing, and solve the problem of nitrogen stability in the plate after nitriding, thereby obtaining an excellent bottom layer. However, this method has high requirements for the control accuracy of the furnace condition. Once the furnace condition fluctuates, it is easy to cause poor formation in the oxide layer, and then produce bottom layer defects.

[0007] In the preparation method of low-temperature high-magnetic induction oriented silicon steel disclosed in patent CN109136503A, in the decarburization annealing process, the rapid heating technology is adopted and the decarburization annealing time is calculated according to the heating rate. The decarburization annealing process includes a heating section and a soaking section. The heating section controls the heating rate v of the steel strip to be 150℃ / s~1500℃ / s, and the temperature is raised to between 700℃ and the soaking section temperature; the soaking section temperature is 825~845℃, and the size and uniformity of the initial crystallization of the low-temperature high-magnetic induction oriented silicon steel are controlled, thereby improving the magnetic properties of the product. This method mainly improves the magnetic properties of the product by controlling the size of the primary grains. However, the heating rate of the decarburization annealing heating section is too fast, which is difficult to meet with the existing production equipment, and it is difficult to achieve the production goal.

[0008] Patent CN110218853A proposes a process for preparing low-temperature high-magnetic induction oriented silicon steel. Nitriding is carried out within the temperature range of the initial recrystallization starting from the initial stage of decarburization annealing of cold-rolled plates, and the nitrogen content of different plate thicknesses and the formation of the inner oxide layer during decarburization are controlled to reduce the escape of nitrogen, which helps to form a stable nitride precipitation phase. This method controls the size of the primary recrystallization grains after nitriding and decarburization, increases the number of Gaussian nuclei, reduces the grain size of the finished product, and obtains the beneficial effects of improving product iron loss, improving magnetic stability, and saving energy and reducing consumption. However, the process adopts a process of nitriding first and then decarburization, which does not meet the process conditions of existing production equipment and is difficult to achieve production goals.

[0009] Patent CN102517592A proposes a nitriding treatment method for high magnetic induction oriented silicon steel strip. This method uses a one-time nitriding and homogenization treatment after decarburization annealing to ensure that the metastable nitride formed by nitriding diffuses into the steel strip in time and is converted into stable AlN at the same time, thereby ensuring the stability of the inhibitor during subsequent high-temperature annealing and obtaining stable magnetic properties. This method is mainly to obtain a stable AlN inhibitor and ensure the stability of secondary recrystallization, thereby obtaining the final magnetic stability of the steel plate. In terms of ensuring the quality of the bottom layer, the damage to the oxide layer after decarburization caused by nitriding is mainly repaired by homogenization treatment after nitriding, so as to avoid the oxide layer being too thin and causing the bottom layer to fall off. However, under this method, it is easy to cause the oxide layer to be too thick, and it is easy to cause the residual SiO2 to decompose and release gas in the subsequent high-temperature annealing process, destroying the bottom layer.

[0010] How to effectively control the complex decarburization process to achieve the goal of reducing the C content of steel plates with different carbon content components, obtaining an excellent bottom layer, and obtaining excellent magnetic properties of the steel plates is of great significance. Summary of the invention

[0011] The present invention provides a method for preparing low-temperature and high-magnetic-induction oriented silicon steel with excellent bottom layer and magnetic properties, which controls the C content of the oriented silicon steel below 15 ppm and controls the thickness and uniformity of the oxide film formed on the surface of the steel plate during the decarburization process, thereby obtaining a low-temperature and high-magnetic-induction oriented silicon steel with excellent bottom layer and magnetic properties.

[0012] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0013] Provided is a method for preparing low-temperature high-magnetic induction oriented silicon steel with excellent bottom layer and magnetic properties, comprising the following steps: molten steel is subjected to converter smelting, billet heating, hot rolling, pickling and normalizing, and cold rolling, followed by decarburization annealing and nitriding annealing, then coating with a high-temperature annealing separator, high-temperature annealing, and finally coating with an insulating layer and conducting stretching and flattening annealing; wherein:

[0014] The C content in the ingot is 400-800ppm;

[0015] Decarburization annealing is divided into heating section and soaking section:

[0016] The heating section controls the heating rate of the steel strip to be V, and heats it to the decarburization annealing soaking section temperature; the heating rate V of the steel strip in the heating section and the C content [C] in the ingot have the following relationship:

[0017] e [C] / 200 ≤V≤e [C] / 150 Relation 1

[0018] Atmosphere partial pressure in heating section The relationship between the C content [C] in the ingot is as follows:

[0019]

[0020] C diffusion is a controlling factor of the decarburization reaction rate. The present invention specifically adjusts the heating rate of the decarburization annealing heating section and the atmosphere partial pressure of the heating section according to the C content of the oriented silicon steel after smelting. It is beneficial to regulate the decarburization reaction and oxidation reaction according to the C diffusion rate along the thickness direction. On the one hand, it can ensure the smooth progress of the decarburization reaction, and on the other hand, it can control the formation of oxide film on the surface of the steel plate in the early stage of decarburization to ensure the subsequent formation of the oriented silicon steel bottom layer.

[0021] As the temperature rises in the heating section, the C in the steel strip diffuses to the surface along the thickness direction, and a decarburization reaction gradually occurs; at the same time, as the temperature rises, the O in the atmosphere diffuses into the steel, and the Si inside the silicon steel diffuses to the surface of the steel strip, and an oxidation reaction gradually occurs, forming an inner oxide layer with a surface layer of Fe2SiO4 and an inner layer of SiO2 on the surface of the steel strip. Further, in the subsequent coating of high-temperature annealing separators and high-temperature annealing stages, the SiO2 in the oxide layer reacts with the magnesium oxide in the annealing separator to form a 2MgO+SiO2→Mg2SiO4 bottom layer of forsterite or glass film. The oxide layer formed during the decarburization process has an important influence on the formation of the subsequent bottom layer. If the oxide layer is too thin or unevenly formed, the bottom layer will be poorly formed, which will eventually cause poor adhesion of the finished steel plate and also affect the magnetic properties of the steel plate.

[0022] The C content is relatively high, and the faster the heating rate should be, the more conducive it is to increase the diffusion rate of C and accelerate the decarburization reaction. The heating rate of the steel strip in the heating section is regulated according to the C content of the ingot. The heating rate of the steel strip in the heating section is regulated within a certain range. By controlling the heating rate within an appropriate range, it should not be too slow to avoid the formation of coarse Fe2SiO4 particles on the steel surface, which is not conducive to the formation of the subsequent bottom layer; it should not be too fast to avoid the uneven formation of the oxide film on the surface of the oriented silicon steel, which affects the adhesion of the subsequent bottom layer.

[0023] At the same time, according to the C content of the ingot, the atmosphere partial pressure in the heating section is adjusted Suitable range. At relatively high C content, the required atmosphere partial pressure in the heating section The lower the atmospheric pressure, the It cannot be too high to avoid excessive and dense Fe2SiO4 on the surface of oriented silicon steel, which will completely cover the surface of oriented silicon steel and inhibit the subsequent decarburization reaction; it cannot be too low to avoid Too low will result in too little water vapor. Since the diffusion speed of C to the surface of the steel strip is slow, too little water vapor will preferentially undergo oxidation reaction instead of decarburization reaction, resulting in a high C content in the steel plate after annealing, affecting the magnetic properties of the steel plate. The regulation can coordinate with the regulation of the heating rate of the heating section to achieve the regulation of the decarburization reaction process and the formation of the silicon steel surface layer. On the one hand, it can ensure the smooth progress of the decarburization reaction, and on the other hand, it can control the formation of the oxide film on the surface of the steel plate in the early stage of decarburization to ensure the subsequent formation of the oriented silicon steel bottom layer.

[0024] Then the steel strip enters the soaking section, the temperature T of the decarburization annealing soaking section and the atmosphere partial pressure of the heating section There are the following relationships:

[0025]

[0026] In the soaking section after 800℃, the decarburization reaction H2O+C=H2+CO mainly occurs, and the primary recrystallization texture and organization are formed. At the same time, accompanied by the diffusion of Si element in the steel, an oxidation reaction occurs: Si+H2O=SiO2+H2. Adjusting the temperature of the soaking section of the decarburization annealing is conducive to controlling the formation of the oxide layer and achieving further decarburization. The partial pressure of the atmosphere in the heating section will affect the oxygen content in the steel plate, that is, the thickness of the oxide layer formed. If the partial pressure of the atmosphere in the heating section is high, the temperature of the soaking section should be reduced to avoid the Fe2SiO4 and SiO2 particles in the inner oxide layer being too large, which will affect the formation of the subsequent bottom layer. Since the diffusion rate of C will increase significantly when the temperature is higher than 800°C, the decarburization reaction can proceed smoothly at this time. Therefore, regulating the temperature of the soaking section according to the partial pressure of the atmosphere in the previous heating section is conducive to controlling the oxygen content in the steel plate while ensuring the smooth progress of decarburization. If the temperature of the soaking section of the decarburization annealing is too low, it is not conducive to controlling the C content of the oriented silicon steel below 15ppm, which affects the final magnetic properties of the finished product; if the temperature of the soaking section of the decarburization annealing is too high, the manufacturing cost of the oriented silicon steel will increase.

[0027] Atmosphere partial pressure in the soaking zone If the atmosphere partial pressure in the soaking section is too high, it will cause too much FeO to form in the oxide layer, affecting the formation of the subsequent bottom layer. If the atmosphere partial pressure in the soaking section is too low, it is not conducive to controlling the C content of oriented silicon steel below 15ppm, affecting the final magnetic properties of the finished product.

[0028] Heating time t in the soaking zone of decarburization annealing and the C content [C] in the ingot and the partial pressure of the atmosphere in the soaking zone The following relationship exists:

[0029]

[0030] If the heating time is too long, it will affect the production efficiency and cause too much FeO to form in the oxide layer, which will affect the formation of the subsequent bottom layer. If the heating time is too short, it will not be conducive to controlling the C content of oriented silicon steel below 15ppm, which will affect the final magnetic properties of the finished product.

[0031] The decarburization reaction and the formation of the oxide layer on the steel plate surface are both reactions with water molecules. The partial pressure of the atmosphere in the soaking section The larger the value, the faster the decarburization reaction and the formation of the oxide layer. At this time, the soaking time can be reduced. The higher the C content in the steel plate, the longer the heating time in the soaking zone. Therefore, according to the C content in the steel plate and the partial pressure of the atmosphere in the soaking zone, Adjusting the heating time t of the decarburization annealing soaking section can, on the one hand, ensure that the C content in the steel plate after decarburization annealing of the oriented silicon steel is controlled below 15ppm, and on the other hand, obtain an oxide layer of uniform thickness on the surface of the oriented silicon steel, which is beneficial to the subsequent formation of the bottom layer and improves the adhesion of the bottom layer.

[0032] Among them, in the above-mentioned relationship formulas 1-4, V, [C] and T are expressed in units without units and represent specific values, wherein V is expressed in units of ℃ / s, [C] is expressed in units of ppm, and T is expressed in units of ℃.

[0033] According to the above scheme, the ingot is heated to 1100-1250℃.

[0034] According to the above scheme, the final thickness of the steel plate after cold rolling is 0.21-0.30mm.

[0035] According to the above scheme, under the above decarburization annealing process, an oxide layer with a thickness of 2-4 μm can be formed, which is conducive to obtaining an excellent bottom layer.

[0036] According to the above scheme, nitriding is performed after decarburization annealing, the nitriding temperature is 830-930°C, and the nitrogen content of the steel plate after nitriding is controlled to be 120-200ppm.

[0037] According to the above scheme, an annealing separator with magnesium oxide as the main component is coated in a conventional manner, high-temperature annealing is performed, and after high-temperature annealing, an insulating coating is coated and flattening and stretching annealing is performed.

[0038] According to the above scheme, the weight percentage of the ingot composition is: C: 0.04%-0.08%, Si: 3.14%-3.4%, Mn: 0.06%-0.12%, S: 0.02%-0.03%, Als: 0.02%-0.03%, N: 0.006%-0.01%, and the remainder is Fe and unavoidable impurities.

[0039] Provided is a low-temperature high-magnetic induction oriented silicon steel prepared by the above-mentioned preparation method.

[0040] According to the above scheme, the C content of the low-temperature and high-magnetic induction oriented silicon steel is controlled below 15 ppm; and the adhesion reaches above Grade C.

[0041] According to the above scheme, the magnetic induction B8 of the ultra-thin oriented silicon steel strip obtained from the low-temperature and high-magnetic induction oriented silicon steel is 1.916-1.925T.

[0042] According to the above scheme, the iron loss P of the ultra-thin oriented silicon steel strip obtained by the low-temperature high magnetic induction oriented silicon steel is 17 / 50 It is 0.87-0.91w / kg.

[0043] The beneficial effects of the present invention are as follows:

[0044] During the decarburization annealing of oriented silicon steel, the heating rate of the decarburization annealing heating section and the partial pressure of the atmosphere in the heating section are adjusted according to the C content of the oriented silicon steel after smelting. Further adjusting the temperature and soaking time of the decarburization annealing soaking section can, on the one hand, ensure the smooth progress of the decarburization reaction and control the C content of the oriented silicon steel below 15ppm, and on the other hand, control the thickness and uniformity of the oxide film formed on the surface of the steel plate during the decarburization process, thereby obtaining low-temperature and high-magnetic induction oriented silicon steel with excellent base layer and magnetic properties, in which the adhesion reaches above grade C and the magnetic induction B8 reaches above 1.916T. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] Each embodiment of the present invention is prepared according to the following steps:

[0047] 1) Smelting and continuous casting into billets and then heating them conventionally; the billet composition weight percentage: C: 0.04%-0.08%, Si: 3.14%-3.4%, Mn: 0.06%-0.12%, S: 0.02%-0.03%, Als: 0.02%-0.03%, N: 0.006%-0.01%, the balance is Fe and unavoidable impurities; the billet is heated to 1100-1250° C. The specific composition ratios of each embodiment and comparative example are shown in Table 1.

[0048] 2) Conventional hot rolling, normalized pickling and one cold rolling, the final steel plate thickness after cold rolling is 0.21-0.30mm;

[0049] 3) Carry out decarburization annealing according to the process shown in Table 2.

[0050] Decarburization annealing is divided into a heating section and a soaking section, where:

[0051] The heating section controls the heating rate of the steel strip to be V, and heats it to the decarburization annealing soaking section temperature; the heating rate V of the steel strip in the heating section and the C content [C] in the ingot have the following relationship:

[0052] e [C] / 200≤V≤e [C] / 150 Relation 1

[0053] Atmosphere partial pressure in heating section The relationship between the carbon content in the steel plate is as follows:

[0054]

[0055] Then the steel strip enters the soaking section, the temperature T of the decarburization annealing soaking section and the atmosphere partial pressure of the heating section There are the following relationships:

[0056]

[0057] Atmosphere partial pressure in the soaking zone Heating time t in the soaking zone of decarburization annealing and the carbon content [C] in the steel plate and the partial pressure of the atmosphere in the soaking zone The following relationship exists:

[0058]

[0059] Among them, in the above-mentioned relationship formulas 1-4, V, [C] and T are expressed in units without units and represent specific values, wherein V is expressed in units of ℃ / s, [C] is expressed in units of ppm, and T is expressed in units of ℃.

[0060] The carbon content on the steel plate surface is controlled to be ≤15ppm and the oxide layer thickness is 2-4μm.

[0061] 4) Perform nitriding treatment in a mixed gas atmosphere of NH3, N2, and H2 at a nitriding temperature of 830-930°C, and control the nitrogen content of the steel plate after nitriding to be 120-200ppm. Apply an annealing separator with magnesium oxide as the main component and then dry;

[0062] 5) High temperature annealing at 1190°C for 20 hours;

[0063] 6) Apply insulation coating, stretch and flatten anneal.

[0064] Table 1 shows the composition of the ingots in various embodiments and comparative examples of the present invention.

[0065] Table 2 shows the main process parameters of various embodiments and comparative examples of the present invention.

[0066] Table 3 shows the performance results of various embodiments and comparative examples of the present invention.

[0067] Table 1. Composition of the ingots in the embodiments of the present invention and the comparative examples (wt%)

[0068]

[0069]

[0070] Table 2. Main process parameters of various embodiments of the present invention and comparative examples

[0071]

[0072] Table 3. Properties of steel plates obtained from the examples of the present invention and the comparative examples

[0073]

[0074]

[0075] It can be seen from Table 3 that when the decarburization annealing process meets the scope of the technical solution of the present invention, the C content of the steel plate after decarburization is ≤15ppm, the adhesion of the oriented silicon steel reaches above Grade C, and low-temperature and high magnetic induction oriented silicon steel with excellent bottom layer and magnetic properties can be obtained.

[0076] In Comparative Example 1, the heating rate of the decarburization annealing heating section does not satisfy the formula (1) proposed in the present invention, and the partial pressure of the atmosphere in the decarburization annealing heating section P H2O / P H2 The formula (2) proposed by the present invention is not satisfied, the heating stage heating rate is too slow, and the atmosphere partial pressure is If the temperature is too high, decarburization will not be completed and the surface of the oriented silicon steel will be covered with an oxide film, which will inhibit the decarburization reaction. Under this process, the C content of the steel plate after decarburization is 41ppm, the magnetic properties of the steel plate are poor, and the adhesion of the bottom layer is also poor.

[0077] In Comparative Example 2, the atmosphere partial pressure P H2O / P H2 does not satisfy the formula (2) proposed in the present invention, the temperature of the decarburization annealing soaking section does not satisfy the formula (3) proposed in the present invention, the soaking section holding time does not satisfy the formula (4) proposed in the present invention, and the atmosphere partial pressure in the heating section The temperature in the soaking section is too high, the temperature in the soaking section is too low, and the heating time is too short, so that the oxide layer on the surface of the oriented silicon steel is formed too quickly in the heating section and completely covers the surface of the oriented silicon steel, inhibiting the subsequent decarburization reaction. Under this process, the C content of the steel plate after decarburization is 38ppm, the adhesion of the bottom layer is poor and is grade F, and the magnetic properties of the steel plate are also poor.

[0078] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A method for preparing low-temperature high magnetic induction oriented silicon steel with excellent bottom layer and magnetic properties, characterized in that: The following steps are involved: After the molten steel is smelted in a converter, heated by ingot casting, hot rolled, pickled and normalized, and cold rolled, it is subjected to decarburization annealing, nitriding annealing, and then coated with a high-temperature annealing separator, high-temperature annealing, and finally coated with an insulating layer and stretched and flattened annealing; wherein: The C content in the ingot is 400-800ppm; Decarburization annealing is divided into heating section and soaking section: The heating section controls the heating rate of the steel strip to be V, and heats it to the decarburization annealing soaking section temperature; the heating rate V of the steel strip in the heating section and the C content [C] in the ingot have the following relationship: e [C] / 200 ≤V≤e [C] / 150 Relation 1 Atmosphere partial pressure P in the heating section H2O / P H2 The relationship between the C content [C] in the ingot is as follows: Then the steel strip enters the soaking section, the temperature T of the decarburization annealing soaking section and the atmosphere partial pressure P of the heating section H2O / P H2 There are the following relationships: 800≤T<800-10*ln(P H2O / P H2 ) Relation 3 Atmosphere partial pressure P' in the soaking zone H2O / P H2 =0.1-0.2; The heating time t of the decarburization annealing soaking zone is related to the C content [C] in the ingot and the atmosphere partial pressure P' in the soaking zone H2O / P H2 The following relationship exists: Among them, in the above-mentioned relationship formulas 1-4, V, [C] and T are expressed in units without units and represent specific values, wherein V is expressed in units of ℃ / s, [C] is expressed in units of ppm, and T is expressed in units of ℃.

2. The preparation method according to claim 1, characterized in that: The ingot is heated to 1100-1250℃.

3. The preparation method according to claim 1, characterized in that: The final steel plate thickness after cold rolling is 0.21-0.30mm.

4. The preparation method according to claim 1, characterized in that: After decarburization annealing, nitriding is performed at a temperature of 830-930°C. The nitrogen content of the steel plate after nitriding is controlled to be 120-200ppm.

5. The preparation method according to claim 1, characterized in that: An annealing separator with magnesium oxide as the main component is applied in a conventional manner, and high-temperature annealing is performed. After the high-temperature annealing, an insulating coating is applied and flattening and stretching annealing is performed.

6. The preparation method according to claim 1, characterized in that: The composition of the ingot by weight percentage: C: 0.04%-0.08%, Si: 3.14%-3.4%, Mn: 0.06%-0.12%, S: 0.02%-0.03%, Als: 0.02%-0.03%, N: 0.006%-0.01%, and the balance is Fe and unavoidable impurities.

7. A low-temperature, high-magnetic-induction oriented silicon steel having excellent bottom layer and magnetic properties prepared by the preparation method according to any one of claims 1 to 6.

8. The low temperature and high magnetic induction oriented silicon steel according to claim 7, characterized in that: The C content of the low-temperature high-magnetic induction oriented silicon steel is controlled below 15 ppm; and the adhesion reaches above Grade C.

9. The low temperature and high magnetic induction oriented silicon steel according to claim 7, characterized in that: The magnetic induction B8 of the low-temperature and high-magnetic induction oriented silicon steel is 1.916-1.925T.

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