Ultrahigh magnetic induction oriented silicon steel and manufacturing method thereof

Abstract

The invention discloses ultrahigh magnetic induction oriented silicon steel and a manufacturing method thereof. A slab of the oriented silicon steel comprises the following chemical components in percentage by weight: 0.03 to 0.07 percent of C, 2.75 to 3.45 percent of Si, 0.015 to 0.035 percent of Als, 0.0060 to 0.0095 percent of N, 0.06 to 0.20 percent of Mn, 0.0050 to 0.010 percent of S, 0.01 to 0.10 percent of Sn, 0.01 to 0.03 percent of P, 0.0010 to 0.02 percent of Bi and the balance of iron and inevitable impurities. The manufacturing method comprises the steps that after a plate blank is subjected to hot rolling and normalizing pickling, cold rolling, decarburization annealing, nitriding treatment, high-temperature annealing, leveling stretching and insulating coating coating are sequentially conducted, and the oriented silicon steel is obtained. And when the cold rolling reduction rate ranges from 75% to 84%, aging rolling is carried out. According to the method, segregation elements such as Bi and Sn are added to improve the number and strength of the oriented silicon steel inhibitor, a proper aging rolling process is adopted during primary cold rolling, and meanwhile, a proper nitriding amount is matched to finally obtain an ultrahigh-magnetic-induction oriented silicon steel product with B800 larger than or equal to 1.95 T.

Description

Technical Field

[0001] The invention relates to the technical field of oriented silicon steel, and in particular to ultra-high magnetic induction oriented silicon steel and a manufacturing method thereof. Background Art

[0002] Grain-oriented silicon steel is an important soft magnetic functional material that is indispensable in the power and electronics industries. It is mainly used to manufacture various power transformers, distribution transformers and large generator stators. It has the characteristics of high magnetic induction and low iron loss. Due to its complex production process, strict manufacturing technology, long manufacturing process and many factors affecting performance, it has always been the "top product" in the steel industry and is even known as the "special steel artwork".

[0003] In recent years, with the urgent requirements of energy conservation and reducing carbon emissions, there is an urgent need to further improve the magnetic induction strength of oriented silicon steel in transformer and motor design to meet the design needs of downstream users. Among them, low-frequency transformers are one of the application scenarios of ultra-high magnetic induction oriented silicon steel. Flexible low-frequency AC transmission technology combines the advantages of industrial frequency AC transmission and flexible DC transmission. It uses power electronics technology to flexibly select a suitable frequency of 0 to 50 Hz to improve the transmission capacity and flexible regulation capabilities of the power grid. It is a new and efficient AC transmission technology. However, the current low-frequency transformers mainly have problems with weight, volume, floor space, and large main material consumption. By developing ultra-high magnetic induction (for example, B800 ≥ 1.95T) oriented silicon steel, the design magnetic flux density of the core can be increased, and the weight, volume and total loss of low-frequency transformers can be reduced, which can better promote the development of flexible low-frequency AC transmission technology.

[0004] On the other hand, the application of ultra-high magnetic induction oriented silicon steel products can further improve the magnetic induction strength to reduce hysteresis loss and thus reduce transformer noise. With the further development of cities and the improvement of environmental awareness, noise pollution has become a major complaint of residents. By using ultra-high magnetic induction oriented silicon steel to make transformers, not only can the noise pollution caused by hysteresis loss be reduced, but the size of the transformer can also be further reduced to reduce the floor space.

[0005] In order to obtain high magnetic induction oriented silicon steel, domestic and foreign scholars have conducted extensive research on the manufacturing process of high magnetic induction oriented silicon steel.

[0006] The Chinese invention patent with application number CN201811519969.4 discloses a method for producing high magnetic induction oriented silicon steel, the production method comprising: obtaining a slab; hot rolling, cold rolling and decarburizing the slab to obtain a decarburized plate; curling the decarburized plate to obtain a steel coil; high temperature annealing the steel coil comprising: first heating to 600-750°C, keeping warm for 10-20h; second heating to the lower limit temperature Tmin of the secondary recrystallization start temperature; third heating To the upper limit temperature Tmax of the secondary recrystallization starting temperature; the fourth temperature is raised to 1170-1220℃, and kept warm for 20-30h; the annealed steel coil is stretched and flattened to obtain the high magnetic induction oriented silicon steel; the lower limit temperature Tmin is determined by the maximum value P13max of the residual aluminum Alr and the decarburized plate's steel strip iron loss value P13 / 50, and the upper limit temperature Tmax is determined by the minimum value P13min of the residual aluminum Alr and the steel strip iron loss value P13 / 50 of the decarburized plate. According to the steel strip iron loss value P13 / 50 and the residual aluminum Alr, the furnace temperature range for the start of secondary recrystallization can be obtained, thereby improving the performance of the steel coil. However, the maximum magnetic induction intensity B800 of the finished oriented silicon steel obtained by this method is only 1.936T.

[0007] The Chinese invention patent with application number CN201711318051.9 discloses an energy-saving high magnetic induction oriented silicon steel production method: heating after smelting and continuous casting into billets; hot rolling and coiling; two-stage normalizing annealing; cold rolling; decarburization annealing after alkali washing; nitriding annealing; coating high-temperature annealing separator MgO; determining the secondary recrystallization temperature T0 according to the formula T0=1016-40×A+5.85×105×Als: high-temperature annealing with atmosphere changed at different temperature stages according to the secondary recrystallization temperature T0; and performing the post-process. The present invention uses the composition and the detected iron loss value P13 / 50 of the steel strip after decarburization and nitriding annealing to define the secondary recrystallization temperature T0 of the product, so as to improve the secondary recrystallization heating rate and atmosphere conversion control, and the high-temperature annealing heating process time is shortened by not less than 40%, and by increasing the holding time in the secondary recrystallization temperature area and maintaining the inhibitor effect through the atmosphere in a targeted manner, the secondary recrystallization of the product is perfected, the performance is stable and improved to not less than 1.92T.

[0008] With the advancement of technology and the improvement of product performance requirements, the magnetic induction performance of the above patented products has gradually begun to fail to meet the needs of market and technological development. Summary of the invention

[0009] In order to overcome the deficiencies of the above-mentioned technologies, the object of the present invention is to provide an ultra-high magnetic induction oriented silicon steel and a method for manufacturing the same, so as to further improve the magnetic induction intensity of the oriented silicon steel.

[0010] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0011] A method for manufacturing ultra-high magnetic induction oriented silicon steel, which is special in that: after hot rolling and normalizing pickling of the slab, cold rolling, decarburization annealing, nitriding treatment, high temperature annealing, flat stretching, and insulating coating are sequentially performed to obtain the oriented silicon steel; during the cold rolling process, when the reduction rate is between 75% and 84%, aging rolling is performed. Aging rolling can improve the texture of the cold-rolled plate, so that it has a relatively strong favorable texture during the decarburization annealing and initial recrystallization, thereby effectively improving the magnetic induction intensity of the oriented silicon steel product.

[0012] As a preferred solution, the cold rolling adopts one-time cold rolling, the total cold rolling reduction rate is 85-92%, and the temperature is controlled at 150-240°C for aging rolling when the cold rolling reduction rate is between 75-84%, and the aging rolling time is not less than 30 minutes. Among them, the aging rolling is a process of intermittent rolling in which the steel plate temperature rises due to rolling when the cold rolling reduction rate is between 75-84%, the steel plate temperature rises when the rolling is stopped when the steel plate temperature rises to the set temperature range, and the steel plate is placed for a set time and then rolled again, and the rolling and placement are repeated. The use of aging rolling can improve the texture of the cold-rolled plate, so that it has a relatively strong favorable texture during the decarburization annealing and initial recrystallization, thereby effectively improving the magnetic induction intensity of the oriented silicon steel product. Too short aging rolling time will lead to insufficient solid solution, so the aging rolling time is controlled to be not less than 30 minutes.

[0013] Furthermore, the aging rolling includes a process of alternating rolling and placing. The temperature of the steel plate can be kept at 150-240° C. and the aging rolling time can be not less than 30 minutes by alternating rolling and placing in a heat preservation manner.

[0014] As a preferred solution, during the decarburization annealing process, the decarburization annealing temperature is 800-900° C., and the decarburization annealing time is 90-140 seconds.

[0015] Further, when the decarburization annealing temperature calculated by the following formula is within the range of 800-900°C, the decarburization annealing temperature is determined according to the following formula:

[0016]

[0017] Where, T 脱碳温度 It indicates the decarburization annealing temperature of the steel strip, in °C; [Als], [N], [Bi], and [Sn] respectively indicate the acid-soluble aluminum content, nitrogen content, bismuth content, and tin content in the cold-rolled steel strip, all in ppm.

[0018] As a preferred solution, in the nitriding process, the nitriding temperature is 780-900° C., the nitriding time is 10-40 seconds, and the nitriding atmosphere includes H 2 and N 2 .

[0019] Furthermore, the total nitrogen content of the steel strip after the nitriding treatment satisfies the following formula:

[0020]

[0021] Where W 氮含量 Indicates the total nitrogen content of the steel strip after nitriding, in ppm.

[0022] Furthermore, the method for manufacturing the ultra-high magnetic induction oriented silicon steel comprises the following steps:

[0023] 1) The molten steel is smelted in a converter, subjected to RH refining treatment, continuously cast into slabs, and then hot rolled and normalized pickling;

[0024] 2) One-time cold rolling to finished product thickness;

[0025] 3) After decarburization annealing and nitriding, the cold-rolled steel strip is coated with a magnesium oxide separator;

[0026] 4) High temperature annealing;

[0027] 5) The steel plate is flattened, stretched and coated with an insulating coating to obtain ultra-high magnetic induction oriented silicon steel.

[0028] Furthermore, the thickness of the hot-rolled plate after hot rolling treatment is 2.6 mm, and the thickness of the finished product is 0.3 mm; and the total reduction ratio of the first cold rolling is 88%.

[0029] The present invention also provides an ultra-high magnetic induction oriented silicon steel, which is special in that: it is made by the above-mentioned manufacturing method; the slab of the oriented silicon steel comprises the following chemical components in weight percentage: C 0.03-0.07%, Si 2.75-3.45%, Als 0.015-0.035%, N 0.0060-0.0095%, Mn 0.06-0.20%, S0.0050-0.010%, Sn 0.01-0.10%, P 0.01-0.03%, Bi 0.0010-0.02%, and the rest are iron and inevitable impurities.

[0030] As a preferred solution, the magnetic induction intensity B800 of the oriented silicon steel is ≥1.95T.

[0031] The mechanism and function of the main process of the present invention:

[0032] The present invention adopts cold rolling and aging rolling because aging rolling can significantly enhance the γ texture, especially the {111} <112> texture, and more shear bands are formed. The Goss grains are mainly in {111} <112> Nucleation is formed in the shear band within the deformed grain, so the primary recrystallization structure of the steel strip after aging rolling has a relatively strong Goss texture. Aging rolling is a process of rapid rolling using rough working rolls, large reduction, and closing the emulsion. The deformation heat generated during the rolling process increases the temperature of the steel plate, and the steel plate is aged while rolling, so it is called aging rolling. During the aging rolling process, the deformation resistance of the metal is reduced by appropriate temperature increase compared to conventional cold rolling, which is helpful for the rolling of the steel plate and reduces wear during the rolling process. The present invention combines the composition characteristics of the steel and the cold rolling reduction rate, and performs aging rolling for a sufficient time when the cold rolling reduction rate is between 75% and 84%. This not only further dissolves small-sized carbides, but more importantly, improves the texture of the cold-rolled plate, so that it has a relatively strong favorable texture during the initial recrystallization of decarburization annealing.

[0033] The reason why the present invention determines the decarburization annealing temperature and the total amount of nitriding according to the key components in the steel is that the segregation elements Sb, Bi, Sn, P, etc. added to the steel play the role of auxiliary inhibitors, which will hinder the initial grain growth during decarburization annealing. During the high-temperature annealing process, Sb, Bi, Sn, P, etc. are segregated near AlN, slowing down the inhibitor ripening speed and improving the inhibitory force. After adding Bi, the initial grain growth is hindered by segregation along the grain boundary, and the AlN morphology is changed, so the magnetic induction intensity can be improved. The diffusion activation energy of Bi is Q=85kcal / mol, while the diffusion activation energy of Fe is Q=60kcal / mol. The diffusion coefficient of Bi in Fe is D=3.9×103exp(-85000 / T). According to the diffusion law D=D0exp(-Q / RT), Bi with a large Q value can still segregate at the grain boundary when it is higher than 1000°C, so the inhibitory force is strengthened, while AlN and MnS have begun to decompose when it is higher than 1000°C. Bi generally segregates around AlN and MnS to slow down the decomposition rate of AlN and MnS, thereby increasing the starting temperature of secondary recrystallization and achieving the purpose of increasing magnetic induction intensity. Sn can be used as an auxiliary inhibitor to improve the inhibition force and overcome the uneven precipitation characteristics of AlN. At the same time, Sn is also a surface enrichment element, which will hinder the nitriding efficiency during the nitriding process, but will prevent premature denitrification and nitrogenation during the high-temperature annealing process. After adding Sb, Bi, Sn, and P, in order to obtain a suitable primary grain size, the decarburization annealing temperature must be appropriately increased to ensure that the primary grains grow to a suitable size. Otherwise, secondary recrystallization will start early during the high-temperature annealing process, the finished grains will be large and the grain boundaries will be round, the Gauss orientation grains will be inaccurate, and ultra-high magnetic induction oriented silicon steel will not be obtained. Since the overall inhibition force is enhanced after adding elements such as Sb, Bi, Sn, and P, the conversion of silicon nitride to aluminum nitride will be partially inhibited during the high-temperature annealing process, so a higher nitriding amount is required to meet the requirements of the number and strength of inhibitors.

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

[0035] The present invention increases the number and strength of oriented silicon steel inhibitors by adding segregation elements such as Bi and Sn, adopts a suitable aging rolling process during the first cold rolling, and matches a suitable nitriding amount to finally obtain an ultra-high magnetic induction oriented silicon steel product with B800≥1.95T. The present invention clearly provides a calculation method for the decarburization annealing temperature and the nitriding temperature, providing an important reference for further research and development of ultra-high magnetic induction oriented silicon steel. DETAILED DESCRIPTION

[0036] In order to better explain the present invention, the main contents of the present invention are further explained below in conjunction with specific embodiments, but the contents of the present invention are not limited to the following embodiments.

[0037] The chemical composition and weight percentage of the ultra-high magnetic induction oriented silicon steel slabs in Examples 1 to 12 and Comparative Examples 1 to 10 are: C 0.03-0.07%, Si 2.75-3.45%, Als 0.015-0.035%, N 0.0060-0.0095%, Mn 0.06-0.20%, S 0.0050-0.010%, Sn 0.01-0.10%, P 0.01-0.03%, Bi 0.0010-0.02%, and the rest are iron and unavoidable impurities.

[0038] The manufacturing method of the ultra-high magnetic induction oriented silicon steel in Examples 1 to 12 and Comparative Examples 1 to 10 comprises the following steps: the molten steel is smelted in a converter, RH refined, continuously cast into a slab, hot rolled to a thickness of 2.6 mm, normalized pickling, and cold rolled once to a finished product thickness of 0.30 mm. After cold rolling, the steel plate is decarburized annealed and nitrided, coated with a magnesium oxide separator, and sent to a ring furnace for high-temperature annealing, and then hot stretched flat and coated with an insulating coating.

[0039] Examples 1 to 6 and Comparative Examples 1 to 4

[0040] The chemical composition and weight percentage of the slabs in Examples 1 to 6 and Comparative Examples 1 to 4 are the same, including: C 0.053%, Si 3.31%, Als 0.0261%, N 0.0082%, Mn 0.096%, S 0.0065%, Sn 0.058%, P 0.022%, Bi 0.0061%, and the rest are iron and unavoidable impurities.

[0041] In the method for manufacturing ultra-high magnetic induction oriented silicon steel in Examples 1 to 6 and Comparative Examples 1 to 4, the decarburization annealing temperature satisfies the following formula: The decarburization annealing time is 120 seconds. The total nitrogen content of the steel strip after nitriding satisfies the following formula: The nitriding temperature is 850°C, the nitriding time is 25 seconds, and the nitriding atmosphere is 60% H2+40% N2.

[0042] The difference between Examples 1 to 6 and Comparative Examples 1 to 4 is the different cold rolling processes. Among them, Comparative Example 1 does not adopt the cold rolling aging process, but adopts the ordinary one-time cold rolling process; Examples 1 to 6 and Comparative Examples 2 to 4 adopt the one-time cold rolling and cold rolling aging process of the present invention, and the difference lies in the different process parameters. The texture quantitative detection is carried out on the decarburization and nitriding samples under different cold rolling processes in Examples 1 to 6 and Comparative Examples 1 to 4, wherein the texture content in each direction is expressed by the volume percentage content of the texture within the maximum deviation angle of 15°. The process parameters and texture quantitative detection results are shown in Table 1.

[0043] Table 1: Some process parameters and texture quantitative test results in Examples 1 to 6 and Comparative Examples 1 to 4

[0044]

[0045] As shown in Table 1, from the results of texture content measured under different rolling processes, when the slab composition, decarburization and nitriding process and other processes are the same, when the cold rolling reduction rate is between 75% and 84%, the temperature is 150-240℃, and the aging rolling time is more than 30 minutes, the favorable texture {111} of the sample after decarburization is <112> 、{011} <100> The volume percentage increases significantly, and these favorable textures will be transformed into accurate Gaussian textures during the secondary recrystallization process, greatly improving the magnetic induction strength of the finished product.

[0046] Examples 7 to 12 and Comparative Examples 5 to 10

[0047] The chemical composition and weight percentage of the slabs in Examples 7 to 12 and Comparative Examples 5 to 10 are shown in Table 2. In the manufacturing method of ultra-high magnetic induction oriented silicon steel in Examples 7 to 12 and Comparative Examples 5 to 10, the aging rolling process parameters are the same, which are: the reduction rate during aging rolling is 82%, the aging temperature is 235°C, and the aging time is 55 minutes. After the aging rolling is completed, the cold-rolled plate is subjected to decarburization annealing and nitriding. The decarburization annealing time is 120 seconds, the nitriding temperature is 850°C, the nitriding time is 25 seconds, and the nitriding atmosphere is 60% H2+40% N2. The total nitrogen content of the steel strip after nitriding treatment is adjusted by adjusting the NH3 flow rate. The decarburization annealing temperature and the total nitrogen content of the steel strip after nitriding treatment in Examples 7 to 12 are controlled according to the formula: T 脱碳温度 =900-0.5×([Als]-27 / 14[N])+(0.25[Bi]+0.01[Sn]), Conventional processes were used for the decarburization annealing temperature and the total nitrogen content of the steel strip after nitriding treatment in Comparative Examples 5 to 10. After decarburization and nitriding, the steel coil was annealed at high temperature in a ring furnace, and then subjected to hot stretching, flattening and insulating coating to obtain ultra-high magnetic induction oriented silicon steel.

[0048] Table 2: Chemical composition and weight percentage / % of the slabs in Examples 7 to 12 and Comparative Examples 5 to 10, the remainder being iron and unavoidable impurities

[0049] Serial number C Si Als N Mn S Sn P Bi Example 7 0.053 3.31 0.0261 0.0082 0.096 0.0065 0.058 0.022 0.0061 Example 8 0.050 3.26 0.0276 0.0080 0.112 0.0078 0.055 0.024 0.0062 Example 9 0.048 3.27 0.0283 0.0075 0.118 0.0083 0.048 0.026 0.0097 Example 10 0.056 3.31 0.0280 0.0078 0.098 0.0075 0.045 0.024 0.0102 Embodiment 11 0.054 3.28 0.0270 0.0085 0.091 0.0066 0.052 0.025 0.0051 Example 12 0.053 3.25 0.0269 0.0074 0.099 0.0077 0.096 0.025 0.0036 Comparative Example 5 0.053 3.31 0.0261 0.0082 0.096 0.0065 0.058 0.022 0.0061 Comparative Example 6 0.050 3.26 0.0276 0.0080 0.112 0.0078 0.055 0.024 0.0062 Comparative Example 7 0.048 3.27 0.0283 0.0075 0.118 0.0083 0.048 0.026 0.0097 Comparative Example 8 0.056 3.31 0.0280 0.0078 0.098 0.0075 0.045 0.024 0.0102 Comparative Example 9 0.054 3.28 0.0270 0.0085 0.091 0.0066 0.052 0.025 0.0051 Comparative Example 10 0.053 3.25 0.0269 0.0074 0.099 0.0077 0.096 0.025 0.0036

[0050] Table 3: Some process parameters and magnetic properties test results in Examples 7 to 12 and Comparative Examples 5 to 10

[0051]

[0052] The difference between Examples 7 to 12 and Comparative Examples 5 to 10 lies in the different chemical compositions and the use of different decarburization annealing and nitriding processes in the corresponding manufacturing methods. The process parameters and the corresponding square ring magnetic property test results of the ultra-high magnetic induction oriented silicon steel products are shown in Table 3.

[0053] It can be seen from Table 2 that the chemical compositions of the slabs in Examples 7 to 12 are all different. The chemical composition of the slab in Example 7 is consistent with that in Comparative Example 5, the chemical composition of the slab in Example 8 is consistent with that in Comparative Example 6, the chemical composition of the slab in Example 9 is consistent with that in Comparative Example 7, and so on.

[0054] It can be seen from the performance results in Table 3 that, under the same chemical composition of the slab and the same other processes such as the aging rolling process, the magnetic properties of the finished square ring of the oriented silicon steel product produced by the decarburization annealing process and the nitriding process of the present invention in Example 7 are significantly better than those of the oriented silicon steel product produced by the decarburization annealing process and the nitriding process of the present invention in Comparative Example 5. Compared with the corresponding comparative examples, the magnetic properties of the finished square rings of other embodiments are also significantly better than those of the products in the comparative examples. In addition, the magnetic properties B800 of the oriented silicon steel products in Examples 7 to 12 are all over 1.95T, which is greatly improved compared with the magnetic properties of the comparative examples.

[0055] As shown in Table 3, from the comparison results of the total nitrogen content of the steel strip after decarburization annealing temperature and nitriding treatment, the addition of segregation elements such as Bi and Sn significantly inhibits the growth of the primary grains. After the conventional decarburization annealing temperature and the total amount of nitriding process, the magnetic induction after secondary recrystallization is generally low, and when the nitriding content is too low, the secondary recrystallization is even incomplete. The low-magnification microstructure detection of other finished products also generally shows that the secondary grains are particularly large and the grain boundaries are relatively round. After the decarburization annealing and nitriding process of the present invention is adopted, the primary grains can be fully grown, the primary grain size is properly matched with the inhibitor strength, and finally after the secondary recrystallization, B800≥1.95T ultra-high magnetic induction oriented silicon steel products are obtained.

[0056] The present invention increases the number and strength of oriented silicon steel inhibitors by adding segregation elements such as Bi and Sn, adopts a suitable aging rolling process during the first cold rolling, and matches a suitable primary grain size and nitriding amount to finally obtain an ultra-high magnetic induction oriented silicon steel product with B800≥1.95T. The present invention clearly provides a calculation method for the decarburization annealing temperature and the nitriding temperature. It can be seen from the above embodiments and comparative examples that the calculation method is reasonable and reliable, and can effectively obtain oriented silicon steel with excellent magnetic properties, providing an important reference basis for further research and development of ultra-high magnetic induction oriented silicon steel.

[0057] Those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for manufacturing ultra-high magnetic induction oriented silicon steel, characterized in that: The process comprises hot rolling and normalizing pickling of the slab, followed by cold rolling, decarburization annealing, nitriding treatment, high temperature annealing, flattening and stretching, and insulating coating to obtain the oriented silicon steel; during the cold rolling process, when the reduction rate is between 75% and 84%, aging rolling is performed.

2. The method for manufacturing ultra-high magnetic induction oriented silicon steel according to claim 1, characterized in that: The cold rolling adopts one-time cold rolling, and the total cold rolling reduction rate is 85-92%. When the cold rolling reduction rate is between 75-84%, the temperature is controlled at 150-240°C for aging rolling, and the aging rolling time is not less than 30 minutes.

3. The method for manufacturing ultra-high magnetic induction oriented silicon steel according to claim 2, characterized in that: The aging rolling includes a process of alternating rolling and placing.

4. The method for manufacturing ultra-high magnetic induction oriented silicon steel according to claim 1, characterized in that: In the decarburization annealing process, the decarburization annealing temperature is 800-900° C., and the decarburization annealing time is 90-140 seconds.

5. The method for manufacturing ultra-high magnetic induction oriented silicon steel according to claim 4, characterized in that: When the decarburization annealing temperature calculated by the following formula is within the range of 800-900°C, the decarburization annealing temperature is determined according to the following formula: Where, T 脱碳温度 It indicates the decarburization annealing temperature of the steel strip, in °C; [Als], [N], [Bi], and [Sn] respectively indicate the acid-soluble aluminum content, nitrogen content, bismuth content, and tin content in the cold-rolled steel strip, all in ppm.

6. The method for manufacturing ultra-high magnetic induction oriented silicon steel according to claim 1, characterized in that: In the nitriding process, the nitriding temperature is 780-900° C., the nitriding time is 10-40 seconds, and the nitriding atmosphere includes H 2 and N 2 .

7. The method for manufacturing ultra-high magnetic induction oriented silicon steel according to claim 1, characterized in that: The total nitrogen content of the steel strip after nitriding treatment satisfies the following formula: Where W 氮含量 Indicates the total nitrogen content of the steel strip after nitriding, in ppm.

8. The method for manufacturing ultra-high magnetic induction oriented silicon steel according to any one of claims 1 to 7, characterized in that: The following steps are involved: 1) The molten steel is smelted in a converter, subjected to RH refining treatment, continuously cast into slabs, and then hot rolled and normalized pickling; 2) One-time cold rolling to finished product thickness; 3) After decarburization annealing and nitriding, the cold-rolled steel strip is coated with a magnesium oxide separator; 4) High temperature annealing; 5) The steel plate is flattened, stretched and coated with an insulating coating to obtain ultra-high magnetic induction oriented silicon steel.

9. An ultra-high magnetic induction oriented silicon steel, characterized in that: The oriented silicon steel is prepared by the manufacturing method according to any one of claims 1 to 8; the slab of the oriented silicon steel comprises the following chemical components in weight percentage: C 0.03-0.07%, Si 2.75-3.45%, Als 0.015-0.035%, N 0.0060-0.0095%, Mn 0.06-0.20%, S 0.0050-0.010%, Sn 0.01-0.10%, P 0.01-0.03%, Bi 0.0010-0.02%, and the rest are iron and unavoidable impurities.

10. The ultra-high magnetic induction oriented silicon steel according to claim 9, characterized in that: The magnetic induction intensity B800 of the oriented silicon steel is ≥1.95T.

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