A kind of non-oriented silicon steel with high magnetic conductivity and its manufacturing method

Abstract

The present invention discloses a non-oriented silicon steel with high magnetic conductivity and a manufacturing method thereof, and belongs to the field of metallurgical technology. The chemical composition of the non-oriented silicon steel is required to include, by weight percentage: C≤0.0025%, Si: 0.5%~1.5%, Mn: 0.10%~0.30%, 0.30%≤Als≤1.0%, P: ≤0.05%, Sb: 0.04%~0.10%, S≤0.0040%, N≤0.0015%, Ti≤0.0020%, and the rest is Fe and unavoidable impurities. The non-oriented silicon steel is subjected to normalization treatment, and the magnetic permeability of the product is obtained through reasonable composition, process and texture control. 1.5 / 50 and μ 1.5 / 60 All above 2000Gs / Oe, and the finished product iron loss P 1.5 / 50 ≤3.5W / kg, P 1.5 / 60 ≤4.5W / kg.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy, and more specifically, relates to a non-oriented silicon steel with high magnetic conductivity and a manufacturing method thereof. Background Art

[0002] The quality evaluation indexes of non-oriented silicon steel products are mainly iron loss and magnetic induction. Magnetic permeability, as another important technical index of non-oriented silicon steel, has a great influence on the load current, temperature rise, efficiency and safety of the motor, and its size directly reflects the magnetic conductivity of non-oriented silicon steel.

[0003] In order to reduce the iron loss of non-oriented silicon steel, Si or Al elements are usually added to increase resistance to reduce eddy current loss, but the magnetic permeability will also decrease at the same time. Basically, the higher the grade, the lower the magnetic permeability. In the prior art, a secondary annealing method has been used to obtain a higher magnetic permeability, such as patent CN112921164A, but it is still difficult to increase the magnetic permeability while ensuring low iron loss using conventional production methods.

[0004] Patent CN103305748A discloses a non-oriented electrical steel sheet with low iron loss and high magnetic permeability and a manufacturing method thereof, wherein the ingot of the steel sheet comprises the following components: Si: 0.1-2.0wt%, Al: 0.1-1.0wt%, Mn: 0.10-1.0wt%, C: ≤0.005wt%, P: ≤0.2wt%, S: ≤0.005wt%, N: ≤0.005wt%, the remainder being Fe and unavoidable impurities, and also including one or both of Sn and Sb with a total content of ≤0.3wt%, and the magnetic permeability of the steel sheet satisfies the following relationship: μ 10 +μ 13 +μ 15 ≥13982-586.5P 15 / 50 ;μ 10 +μ 13 +μ 15 ≥10000, where P15 / 50 is the iron loss at 50Hz under 1.5T magnetic flux density; μ 10 , μ 13 , μ 15 They are the relative magnetic permeability at 1.0T, 1.3T, and 1.5T magnetic induction at 50Hz. It is mainly aimed at μ which has a greater relationship with iron loss. 10 Improvement of μ 15 In this formula, it accounts for less than 20%, 15 The improvement effect is not directly reflected.

[0005] Patent CN1293261A discloses a non-oriented electromagnetic steel sheet with high magnetic permeability and a manufacturing method thereof, wherein the magnetic permeability of the steel sheet is μ 15 / 60Lower, only required to be above 1500Gs / Oe, the magnetic permeability of this product is low. Summary of the invention

[0006] 1. Problem to be solved

[0007] Aiming at the problem that it is difficult to obtain silicon steel with low iron loss and high magnetic permeability by conventional production methods in the prior art, the present invention provides a non-oriented silicon steel with high magnetic permeability and a manufacturing method thereof, wherein the silicon steel obtained satisfies the performance of low iron loss and high magnetic permeability at the same time. 1.5 / 50 and μ 1.5 / 60 All above 2000Gs / Oe.

[0008] 2. Technical solution

[0009] In order to solve the above problems, the technical solution adopted by the present invention is as follows:

[0010] The chemical composition of the high magnetic conductivity non-oriented silicon steel is required to include by weight percentage:

[0011] C≤0.0025%, Si: 0.5%~1.5%, Mn: 0.10%~0.30%, 0.30%≤Als≤1.0%, P: ≤0.05%, Sb: 0.04%~0.10%, S≤0.0040%, N≤0.0015%, Ti≤0.0020%, and the rest are Fe and unavoidable impurities.

[0012] The role of each element in steel is as follows:

[0013] Si: Si is an element that increases resistance and is the most important alloying element in electrical steel. To obtain low iron loss, the Si content needs to be increased, but an increase in Si will reduce magnetic permeability;

[0014] Mn: Manganese and sulfur form MnS, which can prevent the hot brittleness caused by the formation of low-melting-point FeS along the grain boundaries. Therefore, a certain amount of manganese must be ensured to improve hot-rolled plasticity.

[0015] Al: Aluminum has a similar effect to silicon, increasing the ρ value, reducing the γ region and promoting grain growth, reducing iron loss while also reducing magnetic permeability.

[0016] Sb: It is a typical grain boundary segregation element. It tends to segregate near the grain boundary during hot rolling and annealing, reducing the grain boundary energy, inhibiting the nucleation and growth of grains, reducing the finished grain size, and reducing the iron loss P. 15 / 50 Deterioration. During the recrystallization process of cold-rolled non-oriented silicon steel, the {111} plane texture is more likely to nucleate at the original grain boundary. Since the grain boundary segregation of Sb directly affects the nucleation and growth of the {111} component, the strength of the {111} component in the finished steel strip is greatly reduced, the texture is improved, the magnetic induction B50 is greatly improved, and the magnetic permeability is further improved.

[0017] Since Si and Al alloys are not conducive to magnetic permeability, and in order to ensure that the Sb element can play its role to the maximum extent, the main alloy elements need to satisfy [Al] = 1.32-0.68[Si], and [Sb] = 1.12*([Si]+2[Al])^2-5.07*([Si]+2[Al])+5.79.

[0018] N: It is easy to form fine AlN particles with Al to inhibit grain growth. When N>0.0025%, the iron loss increases significantly.

[0019] S: In addition to combining with Mn to form MnS, S also forms a small Cu2S precipitate phase with a small amount of Cu. The size of Cu2S is generally small, ranging from 30 to 200 nm.

[0020] Ti: Ti will form fine-sized TiN, TiC and Ti(CN) with C and N, with a size of less than 100 nm.

[0021] In the production of non-oriented electrical steel, controlling the cleanliness of steel is the basis, mainly to reduce the types and quantities of harmful inclusions. On the one hand, it is to reduce the content of elements that form inclusions, that is, to minimize the content of harmful elements such as carbon, sulfur, nitrogen, titanium, etc., to avoid the formation of second phase particles. On the other hand, it is to adopt corresponding process means to modify the harmful inclusions.

[0022] The present invention also discloses a method for manufacturing the above-mentioned high magnetic conductivity non-oriented silicon steel, and the specific steps are as follows:

[0023] Step S1, hot metal pretreatment: the steel with the above chemical composition is first subjected to hot metal pretreatment, and the [S] content of the hot metal after pretreatment is ≤0.0008%;

[0024] Step S2, converter smelting: smelting the molten iron in a converter, blowing argon throughout the converter smelting process, and controlling the S content of the converter steel to be ≤30ppm;

[0025] Step S3, RH refining: the molten steel is subjected to vacuum treatment and deoxidation alloying in an RH refining furnace, and fed into a conventional commercial calcium silicon line to perform calcium treatment on the molten steel. On the one hand, the size of inclusions can be enlarged, thereby facilitating the removal of inclusions and obtaining a relatively pure molten steel quality. On the other hand, the calcium treatment process converts high-melting-point Al2O3-based inclusions into low-melting-point calcium-aluminate-based inclusions, thereby improving the castability of the molten steel and avoiding or reducing nozzle blockage. Since nitrogen absorption occurs during the calcium treatment process, the calcium feeding time should be shortened as much as possible to control Ca / S: 0.5 to 1.2;

[0026] Step S4, continuous casting: casting the molten steel with the above composition into 150-250 mm ingots under protective casting;

[0027] Step S5, hot rolling: the ingot is heated and hot rolled by hot charging. A lower heating temperature is conducive to further reducing iron loss, but it will increase the difficulty of hot rolling control. Therefore, it is generally above 1050°C. The heating temperature of the ingot in the present invention is controlled between 1050 and 1150°C, and the heating time is controlled between 150 and 220 minutes. The heated slab is rough rolled for 5 or 3 passes, and then fine rolled to 2.0 to 3.0 mm by 7 stands. The final rolling temperature is ≥900°C, and the coiling temperature is ≥700°C. A more uniform recrystallized structure is obtained, and the recrystallization ratio is more than 90%, which lays a good organizational foundation for subsequent grain growth and texture inheritance.

[0028] Step S6, normalizing treatment: After the hot rolled plate is normalized at 900-980°C, a coarse and uniform equiaxed grain structure of 80-100 μm is obtained; the main purpose of normalizing the hot rolled plate is to make the hot rolled plate structure more uniform, increase the number of recrystallized grains, prevent ridge defects, and coarsen the grains and precipitates, strengthen the {100} and {110} components and weaken the {111} component, and significantly improve the magnetic properties, especially B 50 , while B 50 The magnetic permeability μ at 1.5T 15 Has a direct impact.

[0029] Step S7, cold rolling: the strip steel after normalization treatment is cold rolled to 0.35-0.65 mm;

[0030] Step S8, annealing: anneal the cold-rolled steel strip in a nitrogen-hydrogen mixed atmosphere (N2:H2=7:3) at 780-950°C with a dew point below -10°C to obtain the required recrystallized structure. During the annealing process, the unit tension in the furnace is ≤2.5N / mm 2 , then apply an insulating coating on the surface of the strip, dry and solidify it at a temperature below 500°C to obtain excellent insulation performance;

[0031] The annealing stage adopts rapid heating and appropriate slow cooling, especially in the early stage of annealing (below 500℃), the heating rate is ≥10℃ / s, and a large number of recrystallized nucleation grains are formed quickly to reach the required absorptive temperature (780~950℃), and the temperature is kept for 25~45s. The absorptive temperature should not be too high, and the absorptive time should not be too long. Higher temperature and longer time will make the recrystallized grains too large. Although the iron loss will be reduced, the magnetic induction will be low and the magnetic permeability will also be reduced. The size of the recrystallized structure obtained by annealing is 44~56μm. The size of the recrystallized structure is mainly controlled to obtain a higher magnetic induction, thereby ensuring the magnetic permeability.

[0032] The magnetic permeability of the product is μ 1.5 / 50 and μ 1.5 / 60 All above 2000Gs / Oe, and the finished product iron loss P1.5 / 50 ≤3.5W / kg, P 1.5 / 60 ≤4.5W / kg, compared with the reference document CN103305748A, the present invention has carried out a series of designs for improving magnetic permeability while ensuring low iron loss, including the control of the content of Si and Al alloys in the components, and the addition of normalization treatment in the manufacturing method. The reason is that in order to ensure low iron loss, a certain amount of Si and Al must be added, but the addition of Si and Al will reduce the magnetic permeability, and Si reduces the magnetic permeability more significantly than Al. Therefore, in order to reduce iron loss, the main alloy elements are controlled to meet [Al] = 1.32-0.68[Si], and at the same time, in order to ensure that the Sb element plays its role to the maximum extent to improve the magnetic permeability, the present invention controls the content of the Sb element to meet: [Sb] = 1.12*([Si]+2[Al])^2-5.07*([Si]+2[Al])+5.79. However, the addition of alloys will still reduce the magnetic permeability to a certain extent, so the present invention is normalized. Compared with the definition of μ in CN103305748A 10 +μ 13 +μ 15 The main contribution value is μ 10 , μ 10 The relationship with iron loss is greater, so this solution does not need to be normalized, and μ 15 Mainly affected by B 50 The impact of B 50 It is another conventional evaluation index besides steel loss of non-oriented silicon steel. It mainly reflects the magnetization ability of non-oriented silicon steel and has the following relationship with magnetic permeability: μ = dB / dH, that is, magnetic permeability μ is equal to the ratio of the differential of magnetic induction intensity B in the magnetic medium to the differential of magnetic field intensity H. If you want to obtain a higher B 50 Normalization plays a decisive role. Therefore, the present invention adopts a normalization process to make the hot-rolled plate structure more uniform, increase the number of recrystallized grains, and coarsen the grains and precipitates, thereby improving B 50 , thereby increasing the magnetic permeability μ at 1.5T 15 .

[0033] 3. Beneficial effects

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention obtains a non-oriented silicon steel with high magnetic conductivity through reasonable composition, process and texture control. The magnetic permeability of the product is μ 1.5 / 50 and μ 1.5 / 60 All above 2000Gs / Oe, and the finished product iron loss P 1.5 / 50 ≤3.5W / kg, P 1.5 / 60 ≤4.5W / kg. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments, but it should be understood that these drawings are designed only for explanation purposes and are not intended to limit the scope of the present invention. In addition, unless otherwise specified, these drawings are intended only to conceptually illustrate the structural configurations described herein and are not necessarily drawn to scale.

[0037] Figure 1 The hot-rolled structure of Example 2;

[0038] Figure 2 The hot-rolled structure of Comparative Example 3;

[0039] Figure 3 This is a typical morphology of the recrystallized structure obtained by annealing in Example 2. DETAILED DESCRIPTION

[0040] The following illustrates exemplary embodiments of the present invention that can be implemented. Although these exemplary embodiments are described in sufficient detail to enable those skilled in the art to implement the present invention, it should be understood that other embodiments can be implemented and that various changes can be made to the present invention without departing from the spirit and scope of the present invention. The following more detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but is merely for illustration and does not limit the description of the characteristics and features of the present invention, in order to propose the best mode for performing the present invention, and is sufficient to enable those skilled in the art to implement the present invention. Therefore, the scope of the present invention is limited only by the appended claims.

[0041] The present invention will be described in detail below in conjunction with embodiments.

[0042] Table 1 shows the chemical composition (%) of the non-oriented silicon steel with high magnetic conductivity of the present invention.

[0043] Table 1 Chemical composition of the non-oriented silicon steel with high magnetic conductivity of the present invention (%)

[0044]

[0045]

[0046] Example 1

[0047] A high magnetic conductivity non-oriented silicon steel, the chemical composition and weight percentage of which are shown in Example 1 in Table 1. The production method comprises the following steps:

[0048] Step S1, hot metal pretreatment: the steel with the above chemical composition is first subjected to hot metal pretreatment, and the [S] content of the hot metal after pretreatment is 0.0005%;

[0049] Step S2, converter smelting: smelting the molten iron in a converter, blowing argon throughout the converter smelting process, and controlling the sulfur content of the converter steel to 25ppm;

[0050] Step S3, RH refining: the molten steel is subjected to vacuum treatment in an RH refining furnace, and conventional commercial calcium silicon is fed, with the Ca content satisfying Ca / S=0.7;

[0051] Step S4, continuous casting: casting the molten steel with the above composition into 230 mm ingot under protective casting;

[0052] Step S5, hot rolling: the ingot is heated and hot rolled by hot charging, the heating temperature of the ingot is 1120°C, and the heating time is between 170min; the heated slab is rough rolled for 5 passes, and then fine rolled to 2.5mm by 7 stands, the final rolling temperature is 900°C, the coiling temperature is 710°C, and a relatively uniform recrystallized structure is obtained, with an average grain size of 35μm;

[0053] Step S6, normalizing treatment: after the obtained 2.5 mm hot-rolled plate is normalized at 980° C., a 95 μm coarse and uniform equiaxed grain structure is obtained;

[0054] Step S7, cold rolling: the normalized steel strip is cold rolled to 0.50 mm;

[0055] Step S8, annealing: anneal the cold-rolled strip in a nitrogen-hydrogen mixed atmosphere (N2:H2=7:3), with a dew point below -10°C, an initial heating rate of 11°C / s, and when reaching the soaking stage, keep at 860°C for 28s to obtain a 44μm recrystallized structure. During the annealing process, the unit tension in the furnace is 2.0N / mm 2 Then, an insulating coating is applied on the surface of the steel strip, and dried and cured at a temperature below 500° C. to obtain excellent insulating properties. The performance of the product is shown in Example 1 in Table 2.

[0056] Example 2

[0057] A high magnetic conductivity non-oriented silicon steel, the chemical composition and weight percentage of which are shown in Example 2 in Table 1. The production method comprises the following steps:

[0058] Step S1, hot metal pretreatment: the steel with the above chemical composition is first subjected to hot metal pretreatment, and the [S] content of the hot metal after pretreatment is 0.0008%;

[0059] Step S2, converter smelting: smelting the molten iron in a converter, blowing argon throughout the converter smelting process, and controlling the sulfur content of the converter steel to 30ppm;

[0060] Step S3, RH refining: the molten steel is subjected to vacuum treatment in an RH refining furnace, and conventional commercial calcium silicon is fed, with the Ca content satisfying Ca / S=0.9;

[0061] Step S4, continuous casting: casting the molten steel with the above composition into 230 mm ingot under protective casting;

[0062] Step S5, hot rolling: the ingot is heated and hot rolled by hot charging, the heating temperature of the ingot is 1120°C, and the heating time is between 170min; the heated slab is rough rolled for 5 passes, and then fine rolled to 2.5mm by 7 stands, the final rolling temperature is 910°C, the coiling temperature is 710°C, and a relatively uniform recrystallized structure is obtained, with an average grain size of 42μm;

[0063] Step S6, normalizing treatment: after the obtained 2.5 mm hot-rolled plate is normalized at 950° C., a 90 μm coarse and uniform equiaxed grain structure is obtained;

[0064] Step S7, cold rolling: the normalized steel strip is cold rolled to 0.50 mm;

[0065] Step S8, annealing: anneal the cold-rolled strip in a nitrogen-hydrogen mixed atmosphere (N2:H2=7:3), with a dew point below -10°C, an initial heating rate of 10°C / s, and when reaching the soaking stage, keep at 900°C for 30s to obtain a 50μm recrystallized structure. During the annealing process, the unit tension in the furnace is 2.0N / mm 2 Then, an insulating coating is applied on the surface of the steel strip, and dried and cured at a temperature below 500° C. to obtain excellent insulating properties. The performance of the product is shown in Example 1 in Table 2.

[0066] Example 3

[0067] A high magnetic conductivity non-oriented silicon steel, the chemical composition and weight percentage of which are shown in Example 1 in Table 1. The production method comprises the following steps:

[0068] Step S1, hot metal pretreatment: the steel with the above chemical composition is first subjected to hot metal pretreatment, and the [S] content of the hot metal after pretreatment is 0.0007%;

[0069] Step S2, converter smelting: smelting the molten iron in a converter, blowing argon throughout the converter smelting process, and controlling the sulfur content of the converter steel to 20ppm;

[0070] Step S3, RH refining: the molten steel is subjected to vacuum treatment in an RH refining furnace, and conventional commercial calcium silicon is fed, with the Ca content satisfying Ca / S=1.2;

[0071] Step S4, continuous casting: casting the molten steel with the above composition into 230 mm ingot under protective casting;

[0072] Step S5, hot rolling: the ingot is heated and hot rolled by hot charging, the heating temperature of the ingot is 1120°C, and the heating time is between 170min; the heated slab is rough rolled for 5 passes, and then fine rolled to 2.5mm by 7 stands, the final rolling temperature is 920°C, the coiling temperature is 720°C, and a relatively uniform recrystallized structure is obtained, and the average grain size is 40μm;

[0073] Step S6, normalizing treatment: After the obtained 2.5 mm hot-rolled plate is normalized at 930° C., a coarse and uniform equiaxed grain structure of 85 μm is obtained;

[0074] Step S7, cold rolling: the normalized steel strip is cold rolled to 0.50 mm;

[0075] Step S8, annealing: anneal the cold-rolled strip in a nitrogen-hydrogen mixed atmosphere (N2:H2=7:3), with a dew point below -10°C, an initial heating rate of 13°C / s, and when reaching the soaking stage, keep at 930°C for 40s to obtain a 56μm recrystallized structure. During the annealing process, the unit tension in the furnace is 2.0N / mm 2 Then, an insulating coating is applied on the surface of the steel strip, and dried and cured at a temperature below 500° C. to obtain excellent insulating properties. The performance of the product is shown in Example 3 of Table 2.

[0076] Comparative Example 1

[0077] A high magnetic conductivity non-oriented silicon steel, whose chemical composition and weight percentage are shown in Comparative Example 1 in Table 1, does not add Sb element compared with Example 1. The production method of the non-oriented silicon steel is otherwise the same as Example 1, and the performance of the obtained product is shown in Comparative Example 1 in Table 2.

[0078] Comparative Example 2

[0079] A high magnetic conductivity non-oriented silicon steel, whose chemical composition and weight percentage are shown in Comparative Example 2 in Table 1. The production method of the non-oriented silicon steel does not perform normalization treatment in step S6, and the rest is the same as in Example 2, and the performance of the obtained product is shown in Comparative Example 2 in Table 2.

[0080] Comparative Example 3

[0081] A non-oriented silicon steel with high magnetic conductivity, whose chemical composition and weight percentage are shown in Comparison 2 of Table 1. The production method of the non-oriented silicon steel is the same as that of Example 2, except that the hot rolling final rolling temperature is 840°C, the coiling temperature is 620°C, and the hot rolled structure is as shown in Figure 2 As shown, only the edge is equiaxed crystal, and the rest is basically fibrous, no obvious recrystallization occurs, and the normalizing temperature is 880°C, which is lower than the process range required by the present invention. The performance of the obtained product is shown in Table 2 Comparative Example 3.

[0082] Comparative Example 4

[0083] A high magnetic conductivity non-oriented silicon steel, whose chemical composition and weight percentage are shown in Comparative Example 4 in Table 1. The production method of the non-oriented silicon steel does not perform Ca treatment in the step S3RH refining process, and the other parts are the same as Example 3. The performance of the obtained product is shown in Comparative Example 4 in Table 2.

[0084] Comparative Example 5

[0085] A non-oriented silicon steel with high magnetic conductivity, whose chemical composition and weight percentage are shown in Comparative Example 5 in Table 1. The production method of the non-oriented silicon steel is the same as that of Example 2, but the components do not meet the corresponding relationship required by the present invention, and the performance of the obtained product is shown in Comparative Example 4 in Table 2.

[0086] Table 2 Product performance of high magnetic conductivity non-oriented silicon steel of the present invention

[0087]

[0088]

Claims

1. A non-oriented silicon steel with high magnetic conductivity, characterized in that: The chemical composition requirements are as follows by weight percentage: C≤0.0025%, Si: 0.5%~1.5%, Mn: 0.10%~0.30%, 0.30%≤Als≤1.0%, P: ≤0.05%, Sb: 0.04%~0.10%, S≤0.0040%, N≤0.0015%, Ti≤0.0020%, and the rest are Fe and inevitable impurities, wherein [Al]=1.32-0.68[Si], and [Sb]=1.12*([Si]+2[Al])^2-5.07*([Si]+2[Al])+5.

79. The high magnetic conductivity non-oriented silicon steel is subjected to normalization treatment at 900~980℃, and a coarse and uniform equiaxed crystal structure of 80~100μm is obtained after normalization treatment. The magnetic permeability μ of the high magnetic conductivity non-oriented silicon steel is 1.5 / 50 and μ 1.5 / 60 Greater than 2000Gs / Oe, iron loss P 1.5 / 50 ≤3.5W / kg, P 1.5 / 60 ≤4.5W / kg.

2. A method for manufacturing the high magnetic permeability non-oriented silicon steel according to claim 1, characterized in that: The following steps are involved: Step S1, molten iron pretreatment; Step S2, converter smelting; Step S3, RH refining: Step S4, continuous casting; Step S5, hot rolling; Step S6, normalization processing; Step S7, cold rolling; Step S8: annealing.

3. The method for manufacturing high magnetic permeability non-oriented silicon steel according to claim 2, characterized in that: In step S3, the molten steel is treated with calcium to control Ca / S: 0.5~1.

2.

4. The method for manufacturing high magnetic permeability non-oriented silicon steel according to claim 3, characterized in that: In step S5, the heating temperature of the ingot is between 1050 and 1150°C, and the heating time is 150 to 220 minutes; the heated slab is rough-rolled for 5 or 3 passes, and then fine-rolled to 2.0 to 3.0 mm by 7 stands, with a final rolling temperature of ≥900°C and a coiling temperature of ≥700°C.

5. The method for manufacturing high magnetic permeability non-oriented silicon steel according to claim 4, characterized in that: In step S8, the cold-rolled strip is annealed in a nitrogen-hydrogen mixed atmosphere of N2:H2=7:3 at 780-950°C, with a dew point below -10°C. During the annealing process, the unit tension in the furnace is ≤2.5N / mm 2 .

6. The method for manufacturing high magnetic permeability non-oriented silicon steel according to claim 5, characterized in that: During the annealing stage, rapid heating combined with slow cooling is adopted, and the heating rate below 500°C is ≥10°C / s.

7. The method for manufacturing high magnetic permeability non-oriented silicon steel according to claim 6, characterized in that: The size of the recrystallized structure obtained by annealing is 44~56μm.

8. The method for manufacturing high magnetic permeability non-oriented silicon steel according to claim 7, characterized in that: After annealing, an insulating coating is applied to the surface of the steel strip, and then dried and solidified at a temperature below 500°C.

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