High-magnetic-induction oriented silicon steel and manufacturing method thereof

Abstract

The invention discloses high-magnetic-induction oriented silicon steel which comprises the following chemical elements in percentage by mass besides Fe and other inevitable impurity elements: less than or equal to 0.005% of C; 3.0 to 3.8 percent of Si; the content of Als is 0.010 to 0.035 percent; mn: 0.05 to 0.20%; wherein in other inevitable impurity elements, N is smaller than or equal to 0.005%, S is smaller than or equal to 0.005%, V is smaller than or equal to 0.005%, and Ti is smaller than or equal to 0.005%. Wherein the average size of secondary grains of the high-magnetic-induction oriented silicon steel is 6-16 mm; wherein the area percentage of the secondary crystal grains of which the average deviation angle between the rolling direction and the < 001 > direction is in the range of 0-3 degrees accounts for more than 50% of the area of all the secondary crystal grains. Correspondingly, the invention further provides a manufacturing method of the high-magnetic-induction oriented silicon steel.

Description

Technical Field

[0001] The present invention relates to a steel grade and a manufacturing method thereof, and particularly to an oriented electrical steel and a manufacturing method thereof. Background Art

[0002] Oriented electrical steel is a soft magnetic material with excellent magnetic properties, which is composed of grains called Goss texture. The Goss texture is expressed in Miller indices as {110}<001>. The {110} crystal plane of the grains is parallel to the rolling plane, and the <001> crystal direction of the grains is parallel to the rolling direction. The <001> crystal direction of iron has the best magnetization performance under a directional magnetic field. By making full use of the magnetocrystalline anisotropy, the best magnetic properties of the polycrystalline material can be achieved. The transformer core made of oriented electrical steel can significantly save materials and electric energy under the working condition of a directional magnetic field due to its extremely high magnetic induction intensity and extremely low iron loss.

[0003] Generally, the iron loss P 17 / 50 and the magnetic induction intensity B8 are usually used to characterize the magnetic property level of oriented electrical steel, where P 17 / 50 represents the iron loss of a unit kg sample when the magnetic induction intensity is 1.7T and the frequency is 50Hz; B8 represents the magnetic induction intensity corresponding to a magnetic field strength of 800A / m. These two parameters can effectively reflect the advantages and disadvantages of the magnetic properties of oriented electrical steel under different magnetic fields and frequency conditions.

[0004] Existing preparation processes all need to control the evolution of the whole process of microstructure, texture and inhibitor through complex processes to obtain a finished plate with abnormal growth of Goss grains. Oriented electrical steel can be classified into a single cold rolling method and a double cold rolling method according to the process flow. Among them, the single cold rolling method is used to prepare high magnetic induction oriented electrical steel with AlN and MnS as the main inhibitors, and the double cold rolling method is used to prepare ordinary oriented electrical steel with MnS and Cu2S as the main inhibitors. It can also be classified into a low-temperature slab heating process and a high-temperature slab heating process according to the slab heating temperature. Among them, the slab heating temperature of the low-temperature slab heating process is lower than 1250°C.

[0005] Since the low-temperature slab heating process can produce high magnetic induction oriented electrical steel at a lower cost, this process has developed rapidly and gradually become the mainstream. In the low-temperature slab heating process, the inhibitor comes from both the inclusions existing in the slab, and this part of the inhibitor is called the primary inhibitor, which has an important influence on primary recrystallization and thus also affects the magnetic properties of the final product; it also comes from the nitriding treatment after decarburization annealing, and this part of the inhibitor is called the secondary inhibitor, which promotes secondary recrystallization together with the primary inhibitor. Although the inhibitor control of the low-temperature slab heating process is difficult and the annealing process window is narrow, with the application of some improved processes, such as adding auxiliary inhibitors, controlling the inclusion morphology, and using rapid induction heating, the product grade of this process has been continuously improved.

[0006] To improve the efficiency of transformers, the fundamental measure is to improve the magnetic properties of the core material, which requires the core material to have low iron loss and high magnetic induction intensity. Among them, the iron loss is determined by both the material itself and the working frequency of the material in the alternating magnetic field and the influence of the magnetic induction intensity, etc. For the magnetic induction intensity, its value is mainly affected by the Goss grain orientation degree of the material. The grain orientation degree refers to the arrangement direction and degree of the grains in the material. Generally speaking, the higher the Goss grain orientation degree, the higher the magnetic induction intensity of the grain-oriented silicon steel.

[0007] The iron loss of grain-oriented silicon steel is mainly composed of hysteresis loss and eddy current loss, and the eddy current loss accounts for the main part. Common techniques for reducing the iron loss of grain-oriented silicon steel include: increasing the grain orientation degree, reducing the strip thickness, and refining magnetic domains by scribing. However, with the continuous progress of the manufacturing technology of grain-oriented silicon steel, increasing the grain orientation degree and refining magnetic domains by scribing have entered a relatively mature stage, and the improvement effect on magnetic properties is limited. Therefore, reducing the strip thickness has become the main means to reduce the iron loss of grain-oriented silicon steel.

[0008] The strip thickness has a significant impact on the total core loss. By reducing the strip thickness, the eddy current loss can be effectively suppressed, thereby significantly reducing the total core loss. As the number of laminations increases, the total loss of the equal-volume core decreases rapidly. It should be noted that if the strip thickness is too thin, it may lead to a sharp increase in manufacturing costs, and the magnetic properties will also deteriorate significantly due to the increase in hysteresis loss. Therefore, when choosing to reduce the strip thickness, it is necessary to comprehensively consider the balance between manufacturing costs and magnetic properties.

[0009] Although reducing the strip thickness can reduce the iron loss, there are also some challenges and limitations. One is the reduction in the number of effective Goss crystal nuclei: as the strip thickness decreases, its specific surface area increases significantly, the number of effective Goss crystal nuclei will decrease accordingly, and at the same time, the coarsening and decomposition of inhibitors during the annealing process are aggravated, and the inhibitor force weakens. This will have an adverse impact on the secondary recrystallization process, and thus affect the magnetic properties of the product. The second is the control of the cold rolling reduction rate: to obtain the desired primary recrystallization texture, it is necessary to ensure an appropriate cold rolling reduction rate. However, if the strip thickness is too thin, it will cause the thickness of the hot coil to also have to be reduced, thus increasing the difficulty of hot rolling shape control and the stability of hot rolling production becomes poor. The third is the decrease in the production efficiency of the hot-rolled sheet annealing unit: the reduction in the thickness of the hot-rolled sheet will lead to a significant decrease in the production efficiency of the annealing unit. When the thickness of the hot-rolled sheet is reduced from 2.6 mm to 1.8 mm, the unit efficiency is reduced by about 30%. It is precisely because of the above problems that on the premise of ensuring product quality and production stability, the finished product thickness of the existing grain-oriented silicon steel preparation process mostly ranges from 0.23 to 0.30 mm, and it is difficult to further reduce the thickness.

[0010] In addition, in order to achieve the desired inhibitor distribution state, annealing of hot-rolled sheets has become an essential process step in the preparation of high magnetic induction oriented silicon steel. During the annealing of hot-rolled sheets, the hot-rolled pickled sheets are rapidly heated to about 1120 °C, held for 2 - 4 minutes, air-cooled to about 900 °C, water-cooled through the water, or processed in a two-stage manner with an additional 2-minute holding followed by water-cooling. After annealing, the surface recrystallized grains of the hot-rolled sheets grow, and a certain amount of martensite structure is formed during the rapid cooling process. Mechanical twins are also generated due to the rapid cooling and phase transformation stresses. These factors all increase the difficulty of cold rolling. Due to reasons such as hot-rolled sheet annealing and a large reduction ratio in the first pass, existing high magnetic induction oriented silicon steel requires a twenty-high reversing mill with high rolling stress for cold rolling, which makes it difficult to improve the rolling efficiency.

[0011] In order to manufacture thin-gauge high magnetic induction oriented silicon steel with high efficiency, several new manufacturing technologies for oriented silicon steel have been developed in recent years.

[0012] For example, Chinese Patent Document with Publication No. CN116460139A, Publication Date of July 21, 2023, and Title of "An Ultra-Thin High Magnetic Induction Oriented Silicon Steel and Its Rolling Method" discloses an ultra-thin high magnetic induction oriented silicon steel and its rolling method. In this technical solution, the final finished product thickness obtained is 0.12 - 0.20 mm. The main difference between this method and the existing preparation process of high magnetic induction oriented silicon steel lies in the rolling process, where the reversible rolling used in the existing single cold rolling is changed to a combined rolling of tandem cold rolling plus reversible rolling. The work roll diameter of the tandem cold rolling is 300 - 500 mm, and the total reduction ratio is 60 - 91%; the work roll diameter of the reversible rolling is 70 - 150 mm, and the total reduction ratio is 10 - 50%. Compared with the existing preparation process, this technical solution only adjusts the cold rolling method, has limited effects on reducing the manufacturing cost of thin-gauge oriented silicon steel and improving the magnetic properties of the product, and does not solve the problem of difficult cold rolling after annealing of the existing oriented silicon steel hot-rolled sheets.

[0013] Another example is that Chinese Patent with Publication No. CN114134423A, Publication Date of March 4, 2022, and Title of "A Ultra-Short Process Rare Earth Oriented Silicon Steel and Its Preparation Method" discloses a solution for preparing oriented silicon steel by a thin strip continuous casting process. The production process of this technical solution includes: molten steel smelting, thin strip continuous casting, cold rolling, primary recrystallization annealing, coating an isolation agent, secondary recrystallization annealing, etc. A 2 - 2.5 mm thick cast strip can be directly obtained, and the finished product thickness of the prepared oriented silicon steel is 0.20 - 0.35 mm, and the iron loss P 17 / 50 is 0.9 - 1.1 W / kg, and the magnetic induction intensity B8 is 1.87 - 1.95 T. Compared with the existing process, this technical solution eliminates important processes such as continuous casting, rough rolling, hot tandem rolling, and normalizing in the conventional process, and has obvious cost advantages, but the production stability of the thin strip continuous casting technology and the magnetic properties of the product need to be improved. Summary of the Invention

[0014] One of the objectives of the present invention is to provide a high magnetic induction oriented silicon steel, which can obtain a thin-gauge high magnetic induction oriented silicon steel by a reasonable process route design, on the premise of canceling the hot rolled sheet annealing step, thereby reducing the manufacturing cost while improving the magnetic properties of the product.

[0015] To achieve the above objective, the present invention provides a high magnetic induction oriented silicon steel, which contains Fe and other inevitable impurities, and in addition, it also contains chemical elements with the following mass percentages:

[0016] C ≤ 0.005%;

[0017] Si: 3.0 - 3.8%;

[0018] Als: 0.010 - 0.035%;

[0019] Mn: 0.05 - 0.20%;

[0020] Among them, among other inevitable impurity elements, N ≤ 0.005%, S ≤ 0.005%, V ≤ 0.005%, Ti ≤ 0.005%.

[0021] Among them, the average secondary grain size of the high magnetic induction oriented silicon steel is 6 - 16 mm; among them, the area percentage of secondary grains with an average deviation angle between the rolling direction and the <001> direction within the range of 0° - 3° in all secondary grains > 50%.

[0022] Furthermore, in the high magnetic induction oriented silicon steel of the present invention, the mass percentages of its various chemical elements are:

[0023] C ≤ 0.005%;

[0024] Si: 3.0 - 3.8%;

[0025] Als: 0.010 - 0.035%;

[0026] Mn: 0.05 - 0.20%;

[0027] The balance is Fe and other inevitable impurities; among other inevitable impurity elements, N ≤ 0.005%, S ≤ 0.005%, V ≤ 0.005%, Ti ≤ 0.005%.

[0028] In the high magnetic induction oriented silicon steel of the present invention, the design principles of its various chemical elements are as follows:

[0029] C: In the high magnetic induction oriented silicon steel of the present invention, excessive C will precipitate fine and dispersed ε-carbide particles in the material, resulting in magnetic aging phenomenon, that is, the magnetic properties of the material change with the service time. Therefore, C is a residual element of the present invention. During the production process of oriented silicon steel, C needs to be purified and removed in processes such as decarburization annealing and high-temperature annealing. Based on this, in the high magnetic induction oriented silicon steel of the present invention, the mass percentage content of C element is limited to C≤0.005%.

[0030] Si: In the high magnetic induction oriented silicon steel of the present invention, Si is a basic element in the oriented silicon steel, which can increase the resistivity and reduce the iron loss. It should be noted that when the mass percentage content of Si element in the steel is less than 3.0%, it will cause the resistivity of the material to decrease and cannot effectively reduce the eddy current loss of the oriented silicon steel; correspondingly, the content of Si element in the steel should not be too high. When the mass percentage content of Si element in the steel is higher than 3.8%, due to the tendency of Si to segregate along the grain boundaries, it will lead to an increase in the brittleness of the steel plate, poor rollability, and instability of the recrystallized structure and inhibitor, resulting in imperfect secondary recrystallization. Based on this, in the high magnetic induction oriented silicon steel of the present invention, the mass percentage content of Si element is controlled between 3.0 and 3.8%.

[0031] Als: In the high magnetic induction oriented silicon steel of the present invention, Als can form a secondary inhibitor during the subsequent nitriding treatment of the material, which can act together with the primary inhibitor to form sufficient pinning strength to promote secondary recrystallization. However, it should be noted that when the mass percentage content of Als in the steel is less than 0.010%, the pinning strength of the inhibitor will be insufficient, the directional inhibition effect will be weakened, and secondary recrystallization will be incomplete or even cannot occur; if the mass percentage content of Als in the steel is higher than 0.035%, the nitrides of Als will coarsen, the inhibitor effect will decrease, and the magnetic properties of the material will deteriorate. Based on this, in the high magnetic induction oriented silicon steel of the present invention, the mass percentage content of Als is controlled between 0.010 and 0.035%.

[0032] Mn: In the high magnetic induction oriented silicon steel of the present invention, the Mn element is similar to the Si element in that both can increase the resistivity and reduce the eddy current loss. In addition, the Mn element can also expand the γ-phase region, having the effect of improving the hot rolling plasticity and structure, thereby effectively improving the hot rollability of the material. However, it should be noted that when the mass percentage content of the Mn element in the steel is less than 0.05%, the above-mentioned effects cannot be effectively exerted; while if the mass percentage content of the added Mn element in the steel is higher than 0.20%, an α and γ mixed two-phase structure is likely to appear, resulting in phase transformation stress during annealing and generating the γ-phase, causing unstable secondary recrystallization. Based on this, in the high magnetic induction oriented silicon steel of the present invention, the mass percentage content of the Mn element is controlled between 0.05% and 0.20%.

[0033] S and N: In the high magnetic induction oriented silicon steel of the present invention, excessive S or N will precipitate fine and dispersed MnS, Fe 16 N4 and other particles in the material, resulting in the phenomenon of magnetic aging, that is, the magnetic properties of the material change with the service time. Therefore, S and N are impurity elements in the present invention. During the production process of oriented silicon steel, S and N need to be purified and removed in processes such as decarburization annealing and high-temperature annealing. Based on this, in the high magnetic induction oriented silicon steel of the present invention, the mass percentage content of the S element is limited to S≤0.005%, and the mass percentage content of the N element is limited to N≤0.005%.

[0034] V and Ti: In the high magnetic induction oriented silicon steel of the present invention, the V element will form VN after the material is nitrided, affecting the secondary recrystallization and being unfavorable to the magnetic properties of the material. And due to the Ti element, it can preferentially precipitate TiN, and MnS will precipitate attached to TiN, and then AlN will precipitate attached to MnS, thus easily forming coarse MnS + AlN composite inclusions, which is also unfavorable to the magnetic properties of the material. In addition, reducing the content of Ti and V can also reduce the harmful inclusions of TiN and VN in the finished product. Based on this, in the high magnetic induction oriented silicon steel of the present invention, the mass percentage content of the Ti element is limited to Ti≤0.005%, and the mass percentage content of the V element is limited to V≤0.005%.

[0035] Furthermore, in the high magnetic induction oriented silicon steel of the present invention, it also contains at least one of the following chemical elements:

[0036] P: 0.01 - 0.08%; Cr: 0.01 - 0.40%, Sn: 0.03 - 0.30%, Cu: 0.01 - 0.40%, 0 < Sb ≤ 0.1%, 0 < Bi ≤ 0.1%, 0 < Nb ≤ 0.1%, 0 < Mo ≤ 0.1%.

[0037] In the high magnetic induction oriented electrical steel of the present invention, each of the above chemical elements can further improve the performance of the high magnetic induction oriented electrical steel of the present invention, and its design principle is as follows:

[0038] P: In the high magnetic induction oriented electrical steel of the present invention, in some preferred embodiments, P is a grain boundary segregation element, which can act as an auxiliary inhibitor. During the secondary recrystallization process, even at a high temperature of about 1000 °C, the P element still has the effect of grain boundary segregation, which can delay the premature oxidation and decomposition of AlN and is beneficial to secondary recrystallization. At the same time, the P element can also increase the resistivity of the material and reduce the eddy current loss. However, it should be noted that when the mass percentage content of the P element in the steel is less than 0.01%, the above effects cannot be effectively exerted; but when the mass percentage content of the P element in the steel is higher than 0.08%, not only the nitriding efficiency will be reduced, but also the cold rolling workability will become poor. Therefore, in the high magnetic induction oriented electrical steel of the present invention, in some preferred embodiments, the mass percentage content of added P can be preferably set to 0.01 - 0.08%.

[0039] Cr: In the high magnetic induction oriented electrical steel of the present invention, in some preferred embodiments, adding the Cr element can not only increase the resistivity, but also be beneficial to improving the mechanical properties of the material, and can significantly improve the surface quality by promoting the oxidation of the steel plate. In order to fully exert the role of the Cr element, the mass percentage content of the Cr element in the steel can be higher than 0.01%, but considering that when the added Cr is higher than 0.40%, a dense oxide layer will be formed during the decarburization process, which will affect the decarburization and nitriding efficiency. Therefore, in the high magnetic induction oriented electrical steel of the present invention, in some preferred embodiments, the mass percentage content of added Cr can be preferably set to 0.01 - 0.40%.

[0040] Sn: In the high magnetic induction oriented electrical steel of the present invention, in some preferred embodiments, Sn is a grain boundary segregation element, which has the role of an auxiliary inhibitor and can effectively compensate for the problem of the decrease in inhibition force caused by the coarsening of AlN inclusions when the Si content in the steel increases or the strip thickness decreases, etc., expand the process window, and is beneficial to the stability of the magnetic properties of the product. However, considering that when the added amount of the Sn mass percentage content is less than 0.03%, the above effects cannot be effectively obtained; while when the added amount of the Sn mass percentage content is higher than 0.30%, not only the decarburization efficiency will be affected, but also the surface quality will be poor, and the magnetic properties will not be improved, and the manufacturing cost will increase. Therefore, in the high magnetic induction oriented electrical steel of the present invention, in some preferred embodiments, the mass percentage content of added Sn can be preferably set to 0.03 - 0.30%.

[0041] Cu: In the high magnetic induction oriented silicon steel of the present invention, in some preferred embodiments, Cu is added because: similar to the Mn element, the Cu element can both expand the γ-phase region, which helps to obtain fine AlN inclusions. In addition to expanding the γ-phase region, the Cu element can also preferentially combine with the S element to form Cu2S rather than Mn, which is beneficial to suppressing the change of primary grain size. Considering that the mass percentage content of the Cu element added to the steel is less than 0.01%, its above functions cannot be exerted; however, if the mass percentage content of the Cu element added to the steel is higher than 0.40%, the manufacturing cost will increase and the magnetic properties will not be improved either. Therefore, in the high magnetic induction oriented silicon steel of the present invention, in some preferred embodiments, the mass percentage content of the added Cu can preferably be set to 0.01 - 0.40%.

[0042] Sb and Bi: In the high magnetic induction oriented silicon steel of the present invention, in some preferred embodiments, Sb and Bi are added because: Sb and Bi are also grain boundary segregation elements, both having the function of auxiliary inhibitors, which can improve the grain boundary migration conditions of Goss nuclei, help to expand the process window, and improve the finished product magnetic induction. However, when the mass percentage content of Sb and Bi in the steel is higher than 0.1%, it will not only affect the decarburization efficiency, but also cause poor surface quality and the magnetic properties will not be significantly improved, increasing the manufacturing cost. Therefore, in the high magnetic induction oriented silicon steel of the present invention, in some preferred embodiments, the mass percentage content of Sb can preferably be set to be less than 0.1%, and the mass percentage content of Bi can also preferably be set to be less than 0.1%.

[0043] Nb and Mo: In the high magnetic induction oriented silicon steel of the present invention, in some preferred embodiments, Nb and Mo are added because: Nb and Mo are both effective grain refinement microalloying elements, which can promote the formation of fine and uniform primary grain sizes. At the same time, the formed carbonitrides can also be used as auxiliary inhibitors, reducing the difficulty of adjusting the morphology of primary inhibitors. However, when the mass percentage content of Nb and Mo exceeds 0.1%, it has a strong inhibitory effect on recrystallization and the secondary recrystallization is imperfect. Therefore, in the high magnetic induction oriented silicon steel of the present invention, in some preferred embodiments, the mass percentage content of Nb can preferably be set to be less than 0.1%, and the mass percentage content of Mo can preferably be set to be less than 0.1%.

[0044] Furthermore, the thickness of the high magnetic induction oriented silicon steel of the present invention is 0.13 - 0.20 mm.

[0045] Furthermore, in the high magnetic induction oriented silicon steel of the present invention, the area percentage of secondary grains with a size < 6 mm or > 16 mm in all secondary grains < 15%.

[0046] Furthermore, in the high magnetic induction oriented silicon steel of the present invention, the typical iron loss P 17 / 50 ≤0.86 + 2 × plate thickness - 16 × Si, the typical magnetic induction intensity B8 ≥ 2.14 - 6.5 × Si, where the unit parameter of the plate thickness is mm, Si is substituted with the mass percentage of Si element, and the unit parameter of P 17 / 50 is W / kg, and the unit parameter of B8 is T.

[0047] Correspondingly, another object of the present invention is to provide a manufacturing method of the above high magnetic induction oriented silicon steel. By using this method in combination with the above-mentioned component ratio, it is possible to obtain a thin-gauge high magnetic induction oriented silicon steel without the hot-rolled sheet annealing step, thereby reducing the manufacturing cost while improving the magnetic properties of the product.

[0048] To achieve the above object, the present invention proposes a manufacturing method of high magnetic induction oriented silicon steel, which includes the steps:

[0049] (1) Smelting and casting;

[0050] (2) Slab heating;

[0051] (3) Hot rolling;

[0052] (4) First cold rolling

[0053] (5) Intermediate annealing;

[0054] (6) Second cold rolling;

[0055] (7) Decarburization annealing, nitriding treatment, coating with an isolation agent coating, the average primary grain size of the obtained decarburized annealed sheet is 6 - 18 μm, and the proportion of Goss grains with an average deviation angle (α + β) / 2 less than 15° is greater than 1.5%;

[0056] (8) High-temperature annealing;

[0057] (9) Insulation coating and skin pass annealing.

[0058] In the manufacturing method of the present invention, since the morphology of the inhibitor can be adjusted in step (5) intermediate annealing instead of in the conventional hot-rolled sheet annealing process. This change can eliminate the hot-rolled sheet annealing process and greatly reduce the cold rolling difficulty.

[0059] In the existing decarburized plates of high magnetic induction oriented silicon steel, the number of Goss grains with an average deviation angle (α+β) / 2 less than 15° is usually less than 1.5%. Thinning the strip thickness will lead to insufficient number of effective Goss nuclei, which will have an adverse effect on the magnetic properties of the product. The present invention can better control the primary recrystallization structure, texture and primary inhibitor by adopting a double cold rolling process including a primary cold rolling and a secondary cold rolling, so that the decarburized plate in step (7) can more easily obtain a high proportion of Goss grains, which means that the present invention can increase the number of effective Goss nuclei to solve the problem caused by thinning the strip thickness, thereby improving the magnetic properties of the product.

[0060] Furthermore, in step (2) of the manufacturing method described in the present invention, the slab heating temperature is ≤1250°C.

[0061] Furthermore, in step (4) of the manufacturing method of the present invention, the first cold rolling adopts cold tandem rolling, and the reduction rate thereof is 50 to 75%.

[0062] Furthermore, in step (6) of the manufacturing method of the present invention, the secondary cold rolling adopts cold tandem rolling, and the reduction rate thereof is 60 to 85%.

[0063] Although in the present invention, the cold rolling steps (4) and / or (6) may also adopt conventional reversible rolling, from the perspective of improving rolling efficiency and yield rate, cold tandem rolling is preferably adopted.

[0064] In addition, in the manufacturing method of the present invention, by adopting the cold rolling reduction rate of the two cold rollings in step (4) and step (6), it is not only conducive to the formation of fine and uniform recrystallized grains in the decarburized plate, but also conducive to increasing the number ratio of Goss grains. In addition, since the rolling efficiency and yield rate of cold rolling are significantly superior to reversible rolling, the overall cold rolling efficiency in the present invention is also significantly improved.

[0065] Furthermore, in step (5) of the manufacturing method of the present invention, the intermediate annealing temperature is 900-1050°C.

[0066] In the manufacturing method of the present invention, the total oxygen content of the sample after annealing can be controlled to be ≤600ppm, and the C element content can be ≥300ppm. This is conducive to the stable production of the secondary cold rolling in step (6), and promotes the formation of a strong γ texture, which is conducive to the formation of a complete secondary recrystallization.

[0067] Furthermore, after step (3) and before step (4) of the manufacturing method of the present invention, there is a hot-rolled plate annealing step, and the hot-rolled plate annealing temperature is ≤1000°C.

[0068] As described above, in the manufacturing method of the present invention, cold rolling can be directly carried out after hot rolling without hot rolling annealing, thus reducing the process flow, improving production efficiency, and reducing production costs. However, in some embodiments, hot rolling annealing can also be carried out after the hot rolling step, but the annealing temperature of the hot rolled sheet needs to be ≤ 1000 °C, because when the maximum annealing temperature is higher than 1000 °C, it will cause the surface grains of the hot rolled sheet to coarsen, which is not conducive to the stable production of the first cold tandem rolling in the subsequent step (4).

[0069] Furthermore, in step (7) of the manufacturing method of the present invention, the decarburization annealing temperature is 800 - 900 °C, the decarburization annealing time is 80 - 170 s, and the heating rate is 30 - 150 °C / s.

[0070] Furthermore, in step (7) of the manufacturing method of the present invention, the nitrogen content of the decarburized annealed sheet after nitriding treatment is 160 - 260 ppm.

[0071] In the manufacturing method of the present invention, nitrogen combines with the original aluminum in the steel through nitriding treatment to form secondary inhibitors of fine and dispersed particles such as AlN, (Al,Si)N, (Al,Si,Mn)N, etc. During the subsequent high-temperature annealing process, the secondary inhibitors and the primary inhibitors jointly promote the secondary recrystallization process.

[0072] The high magnetic induction oriented silicon steel of the present invention has the following advantages and

[0073] beneficial effects compared with the prior art:

[0074] The high magnetic induction oriented silicon steel of the present invention can significantly reduce the annealing temperature of the hot rolled sheet or even cancel the annealing of the hot rolled sheet by adopting the two-stage cold rolling method to adjust the primary recrystallization structure, texture and precipitation of the primary inhibitor, as well as appropriate composition and process design, so as to realize the efficient production of thin-gauge high magnetic induction oriented silicon steel by the cold tandem rolling method.

[0075] Compared with the prior art, the present invention can solve the problem of insufficient number of effective Goss crystal nuclei after the strip thickness is reduced, which is beneficial to improving the magnetic properties of the final product. Therefore, it is possible to produce thin-gauge high magnetic induction oriented silicon steel without further reducing the thickness of the hot rolled sheet, thus avoiding a series of problems brought by the production of thin-gauge hot coils on a conventional hot rolling production line.

[0076] At the same time, canceling the annealing of the hot rolled sheet and realizing the efficient production of thin-gauge high magnetic induction oriented silicon steel by the cold tandem rolling method can significantly reduce the manufacturing cost.

[0077] In addition, the manufacturing method of the present invention also has the above-mentioned advantages and beneficial effects. Detailed embodiments

[0078] The high magnetic induction oriented silicon steel and its manufacturing method according to the present invention will be further explained and described below in conjunction with specific embodiments. However, such explanations and descriptions shall not unduly limit the technical solutions of the present invention.

[0079] First, various detection means of the embodiments and comparative examples of this case are described as follows:

[0080] (1) The average primary grain size is the grain size of the decarburized plate after treatment measured by the equivalent circle diameter specified in GB / T 36165.

[0081] (2) The finished product secondary grain size is the grain size of the finished product plate after pickling measured by the intercept method specified in GB / T 6394.

[0082] (3) The Gaussian orientation deviation angle is measured by EBSD and includes the rolling direction deviation angle α and the inclination angle β with the rolling plane.

[0083] (4) The P of the non-notch product steel 17 / 50 and B8 are obtained by the method of measuring the magnetic properties of electrical steel sheets (strips) using an Epstein square coil as specified in Standard GB / T 3655.

[0084] (5) The P of the notched product steel 17 / 50 and B8 are obtained by the method of measuring the magnetic properties of electrical steel sheets (strips) using a single-sheet tester as specified in Standard GB / T 13789.

[0085] Examples 1-6 and Comparative Examples 1-5

[0086] The high magnetic induction oriented silicon steel of Examples 1-6 and the comparative steel of Comparative Examples 1-5 are manufactured according to the following steps:

[0087] (1) Smelting and casting: Smelt using a converter or an electric furnace and continuously cast into a slab with a thickness of 230 mm.

[0088] (2) Slab heating: Control the slab heating temperature at 1140 °C and control the heating time at 200 min.

[0089] (3) Hot rolling: Roll into hot-rolled sheets with thicknesses of 2.4 mm and 2.6 mm as shown in Table 1-1.

[0090] (4) Prepare cold-rolled sheets with a finished thickness of 0.18 mm according to the process shown in Table 1-1. Among them, Examples 1-6 and Comparative Examples 3-5 adopt the two-pass cold rolling process described in the present invention, without hot-rolled sheet annealing. Intermediate annealing is carried out between the first cold rolling and the second cold rolling. The intermediate annealing adopts the open-coil continuous annealing method, and the intermediate annealing and its maximum temperature are controlled according to the process shown in Table 1-1. The annealing time is 220 s. Comparative Examples 1-2 adopt the conventional single-pass cold rolling process, control the maximum temperature of hot-rolled sheet annealing to be 1150 °C, and control the annealing time to be 250 s.

[0091] (5) Decarburizing annealing: The decarburizing annealing temperature is 835 °C, the decarburizing annealing time is 125 s, and the heating rate in the heating section is 115 °C / s. Reduce the [C] content in the steel sheet to below 30 ppm, and obtain the primary grain size and the proportion of Goss grains shown in Table 1-2 through detection.

[0092] (6) Nitriding treatment: Control the nitrogen content of the decarburized annealing sheet to be 180-250 ppm.

[0093] (7) Coating with MgO coating: Coat the MgO coating on the steel sheet.

[0094] (8) High-temperature annealing: Carry out 20-hour purification annealing under the condition of a conventional reducing atmosphere and a high-temperature annealing temperature of 1200 °C to reduce the [S] and [N] contents in the steel to below 40 ppm.

[0095] (9) Insulating coating and skin pass annealing: After coating the insulating coating and hot-stretching skin pass annealing, the finished product is obtained. The chemical composition of the obtained finished product is: Si 3.22%, C 0.0016%, Als 0.0334%, N 0.0012%, Mn 0.088%, S 0.0013%, V 0.0025%, Ti 0.0015%. The indexes of the secondary grains of the measured finished product are listed in Table 1-2.

[0096] Table 1-1

[0097]

[0098] Table 1-2 lists the average primary grain size of the decarburized sheets involved in Examples 1-6 and Comparative Examples 1-5, the proportion of Goss grains in the decarburized sheets, the average secondary grain size, the proportion of the average deviation angle in the range of 0°-3°, the proportion of secondary grain sizes <6 mm or >16 mm, the finished product P 17 / 50 and the finished product B8.

[0099] Table 1-2

[0100]

[0101] As can be seen from Table 1-1 and Table 1-2, in Examples 1-6, the 0.18 mm grain-oriented silicon steel was prepared by the double cold rolling method described in the present invention, and appropriate primary grain sizes could be obtained, and the proportion of Goss grains in the decarburized sheet was higher. At the same time, the various indexes of the secondary grains also met the requirements, and the magnetic properties of the obtained products were more excellent. The iron loss P 17 / 50 was lower than the reference iron loss of 0.705 W / kg calculated based on the formula 0.86 + 2×sheet thickness - 16×Si, and the magnetic induction intensity B8 was higher than the reference magnetic induction of 1.931 T calculated based on the formula 2.14 - 6.5×Si. In Comparative Examples 1-2, the 0.18 mm grain-oriented silicon steel was prepared by the conventional single cold rolling method, or in Comparative Examples 3-5, the double cold rolling method was used, but the average primary grain size of the decarburized sheet or the proportion of Goss grains in the decarburized sheet did not meet the requirements of this case, and the obtained iron loss and / or magnetic induction were inferior to the reference values calculated above.

[0102] Examples 7-10 and Comparative Examples 6-13

[0103] The high magnetic induction grain-oriented silicon steel of Examples 7-10 and the comparative steel of Comparative Examples 6-13 were manufactured according to the following steps:

[0104] (1) Smelting and casting: Smelted by a converter or an electric furnace and continuously cast into a slab with a thickness of 230 mm.

[0105] (2) Slab heating: Control the slab heating temperature at 1190 °C and the heating time at 160 min.

[0106] (3) Hot rolling: Hot rolled into a hot rolled sheet with a thickness of 2.6 mm.

[0107] (4) First cold tandem rolling: Cold rolled to the thickness shown in Table 2-1 for the first time.

[0108] (5) Intermediate annealing: Annealed by an uncoiling continuous annealing method for 180 s, and control the maximum intermediate annealing temperature according to Table 2-1 to obtain the total oxygen content and C element content of the intermediate annealed sheet shown in Table 2-1.

[0109] (6) Second cold tandem rolling: Cold rolled to a thickness of 0.15 mm for the second time.

[0110] (7) Decarburizing annealing: Control the decarburizing annealing temperature according to Table 2-1, the decarburizing annealing time is 100 s, and the heating rate in the heating section is 80 °C / s. Reduce the [C] content in the steel plate to less than 30 ppm, and detect the primary grain size and the proportion of Goss grains shown in Table 2-2.

[0111] (8) Nitriding treatment: Control the nitrogen content of the decarburized annealed sheet according to Table 2-1.

[0112] (9) Coating with MgO coating: Coating the MgO coating on the steel plate.

[0113] (10) High-temperature annealing: Under the condition of a conventional reducing atmosphere and a high-temperature annealing temperature of 1170 °C, carry out purification annealing for 18 hours to reduce the [S] and [N] contents in the steel to below 50 ppm.

[0114] (11) Insulating coating and leveling annealing: After applying the insulating coating and hot-stretching leveling annealing, the finished product is obtained. The chemical composition of the obtained finished product is: Si 3.39%, C 0.0007%, Als 0.0275%, N 0.0017%, Mn 0.183%, S 0.0008%, V 0.0031%, Ti 0.0010%. The indexes of the secondary grains of the finished product are listed in Table 2-2.

[0115] Table 2-1

[0116]

[0117] Table 2-2

[0118]

[0119]

[0120] It can be seen from Table 2-1 and Table 2-2 that although Examples 7-10 and Comparative Examples 6-13 both use the double cold rolling method described in the present invention to prepare 0.15 mm grain-oriented silicon steel, the reduction ratios of the first cold rolling, the reduction ratios of the second cold rolling, the highest temperature of the intermediate annealing, the total oxygen content of the intermediate annealing plate, the C element content of the intermediate annealing plate, the nitriding amount of the decarburized plate, the average primary grain size of the decarburized plate, the proportion of the number of Goss grains in the decarburized plate, and the indexes of the secondary grains in Examples 7-10 all meet the requirements of this case. Therefore, its iron loss P 17 / 50 are all lower than the reference iron loss of 0.618 W / kg calculated based on the formula 0.86 + 2 × plate thickness - 16 × Si, and the magnetic induction intensity B8 is higher than the reference magnetic induction of 1.920 T calculated based on the formula 2.14 - 6.5 × Si. On the contrary, the iron loss and / or magnetic induction of Comparative Examples 6-13 are inferior to the reference values obtained from the above calculations.

[0121] Examples 11-22 and Comparative Examples 14-21

[0122] Manufacture the high magnetic induction grain-oriented silicon steel of Examples 11-22 and the comparative steel of Comparative Examples 14-21 according to the following steps:

[0123] (1) Smelting and casting: Use a converter or an electric furnace for smelting and continuously cast a slab with a thickness of 230 mm.

[0124] (2) Slab heating: Control the slab heating temperature at 1200 °C and the heating time at 250 min.

[0125] (3) Hot rolling: Hot roll into a hot-rolled sheet with a thickness of 2.3 mm.

[0126] (4) First tandem cold rolling: Obtain a thickness of 0.75 mm after the first cold rolling, and control the reduction rate of the first tandem cold rolling at 67.4%.

[0127] (5) Intermediate annealing: Adopt the method of uncoiling and continuous annealing, control the intermediate annealing temperature at 975 °C and the intermediate annealing time at 120 s, and obtain the total oxygen content of the sample after intermediate annealing in the range of 261 - 594 ppm and the C element content in the range of 308 - 939 ppm.

[0128] (6) Second tandem cold rolling: Obtain a thickness of 0.19 mm after the second cold rolling, and control the reduction rate of the second tandem cold rolling at 74.7%.

[0129] (7) Decarburizing annealing: The decarburizing annealing temperature is 835 °C, the decarburizing annealing time is 125 s, and the heating rate in the heating section is 115 °C / s. Reduce the [C] content in the steel plate below 50 ppm to obtain the primary grain size and the proportion of Goss grains shown in Table 4.

[0130] (8) Nitriding treatment: Control the nitrogen content of the decarburized annealing plate in the range of 190 - 250 ppm.

[0131] (9) Coating with MgO coating: Coat the MgO coating on the steel plate.

[0132] (10) High-temperature annealing: Conduct a 25-hour purification annealing under the condition of a conventional reducing atmosphere with a high-temperature annealing temperature of 1180 °C to reduce the [S] and [N] contents in the steel below 50 ppm.

[0133] (11) Insulating coating and skin pass annealing: After coating the insulating coating and performing hot stretch skin pass annealing, obtain the finished product with the chemical compositions shown in Table 3-1 and Table 3-2. The indexes of the secondary grains of the finished product are listed in Table 4.

[0134] Table 3-1. (wt%, the balance is Fe and other inevitable impurity elements except N, S, V, Ti)

[0135] Number C Si Als Mn S N V Ti Example 11 0.0012 3.12 0.0330 0.083 0.0035 0.0014 0.0035 0.0035 Example 12 0.0021 3.39 0.0289 0.052 0.0018 0.0022 0.0023 0.0049 Example 13 0.0003 3.79 0.0303 0.199 0.0015 0.0031 0.0050 0.0045 Example 14 0.0010 3.58 0.0177 0.183 0.0023 0.0015 0.0035 0.0025 Example 15 0.0048 3.24 0.0195 0.164 0.0008 0.0012 0.0049 0.0005 Example 16 0.0018 3.29 0.0313 0.069 0.0004 0.0023 0.0028 0.0037 Example 17 0.0022 3.52 0.0101 0.150 0.0030 0.0016 0.0015 0.0050 Example 18 0.0023 3.69 0.0205 0.075 0.0050 0.0013 0.0041 0.0034 Example 19 0.0016 3.50 0.0347 0.111 0.0013 0.0020 0.0025 0.0025 Example 20 0.0020 3.48 0.0274 0.099 0.0013 0.0023 0.0035 0.0013 Example 21 0.0050 3.59 0.0213 0.144 0.0035 0.0030 0.0011 0.0023 Example 22 0.0010 3.02 0.0244 0.123 0.0008 0.0025 0.0005 0.0015 Comparative Example 14 0.0009 3.09 0.0341 0.149 0.0045 <![CDATA 0.0052 > <![CDATA 0.0051 > 0.0045 Comparative Example 15 0.0015 3.41 <![CDATA 0.0358 > 0.173 <![CDATA 0.0056 > 0.0037 0.0015 <![CDATA 0.0052 > Comparative Example 16 <![CDATA 0.0051 > 3.80 0.0159 0.053 0.0020 0.0050 0.0035 0.0035 Comparative Example 17 0.0010 3.29 0.0198 <![CDATA 0.048 > 0.0033 0.0012 0.0035 0.0024 Comparative Example 18 0.0012 3.34 0.0272 0.076 <![CDATA 0.0051 > 0.0011 <![CDATA 0.0055 > 0.0025 Comparative Example 19 0.0011 3.48 0.0304 <![CDATA 0.205 > 0.0018 0.0028 0.0015 0.0016 Comparative Example 20 <![CDATA 0.0053 > 3.12 <![CDATA 0.0099 > 0.112 0.0013 0.0024 0.0035 <![CDATA 0.0058 > Comparative Example 21 0.0017 3.25 0.0226 0.198 0.0048 <![CDATA 0.0051 > 0.0005 0.0043

[0136] Table 3-2 (wt%, the balance is Fe and other inevitable impurity elements except N, S, V, Ti)

[0137]

[0138]

[0139] Table 4

[0140]

[0141]

[0142] Combined with Table 3-1, Table 3-2 and Table 4, it can be seen that for the slab composition of the high magnetic induction oriented silicon steel in Examples 11-22 of the present invention, the average primary grain size of the decarburized slab, the proportion of Goss grain quantity in the decarburized slab, and the various indexes of the secondary grains all meet the scope defined by the claims of this case. Therefore, its iron loss P 17 / 50 is lower than the reference iron loss calculated based on the formula 0.86 + 2×plate thickness - 16×Si, and the magnetic induction intensity B8 is higher than the reference magnetic induction calculated based on the formula 2.14 - 6.5×Si. On the contrary, the iron loss and / or magnetic induction of Comparative Examples 14-21 are inferior to the reference values obtained from the above calculations.

[0143] Examples 23-29 and Comparative Examples 22-28

[0144] Manufacture the high magnetic induction oriented silicon steel in Examples 23-29 and the comparative steel in Comparative Examples 22-28 according to the following steps:

[0145] (1) Smelting and casting: Use a converter or an electric furnace for smelting and continuously cast into a slab with a thickness of 230 mm.

[0146] (2) Slab heating: Control the slab heating temperature at 1250 °C and the heating time at 120 min.

[0147] (3) Hot rolling: Hot roll into a hot-rolled sheet with a thickness of 2.5 mm, and anneal some of the hot-rolled sheets according to Table 5-1.

[0148] (4) First cold tandem rolling: Obtain a thickness of 0.75 mm by first cold rolling, and control the reduction rate of the first cold tandem rolling at 70.0%.

[0149] (5) Intermediate annealing: Conduct intermediate annealing according to the intermediate annealing method, intermediate annealing temperature, and intermediate annealing time shown in Table 5-1, where the uncoiling continuous annealing time is 220 s and the coil annealing time in a bell furnace is 12 h, to obtain a total oxygen content of 350-450 ppm and a C element content of 450-550 ppm for the sample after intermediate annealing.

[0150] (6) Second cold tandem rolling: Obtain a thickness of 0.13 mm by second cold rolling, and control the reduction rate of the second cold tandem rolling at 82.7%.

[0151] (7) Decarburizing annealing: Control the heating rate in the heating section, the decarburizing annealing temperature, and the decarburizing annealing time according to Table 5-1, reduce the [C] content in the steel plate to below 30 ppm, and obtain the primary grain size and the proportion of Goss grains shown in Table 5-2.

[0152] (8) Nitriding treatment: Control the nitrogen content of the decarburized annealing plate to be 200 - 230 ppm.

[0153] (9) Coating with MgO coating: Coat the MgO coating on the steel plate.

[0154] (10) High-temperature annealing: Conduct a 20-hour purification annealing under the condition of a conventional reducing atmosphere with a high-temperature annealing temperature of 1200 °C, and reduce the [S] and [N] contents in the steel to below 30 ppm.

[0155] (11) Insulating coating and skin pass annealing: Apply an insulating coating and perform hot stretch skin pass annealing to obtain the finished product. The chemical composition of the obtained finished product is: Si 3.17%, C 0.0009%, Als 0.0254%, N 0.0019%, Mn 0.144%, S 0.0027%, V 0.0025%, Ti 0.0015%, Sn 0.065%, Cu 0.12%. The indicators of the secondary grains of the finished product are listed in Table 5-2.

[0156] Table 5-1

[0157]

[0158] Table 5-2

[0159]

[0160]

[0161] It can be seen from Table 5-1 and Table 5-2 that although Examples 23 - 29 and Comparative Examples 22 - 28 both use the two-pass cold rolling method described in the present invention to prepare 0.13 mm grain-oriented silicon steel, the hot-rolled plate annealing and the highest annealing temperature, the intermediate annealing and the highest annealing temperature, the heating rate in the heating section of the decarburizing annealing, the decarburizing annealing temperature, the decarburizing annealing time, as well as the average primary grain size of the decarburized plate, the proportion of Goss grains in the decarburized plate, and the indicators of the secondary grains in Examples 23 - 29 all meet the requirements of this case. Therefore, their iron loss P 17 / 50 is lower than the reference iron loss of 0.613 W / kg calculated based on the formula 0.86 + 2 × plate thickness - 16 × Si, and the magnetic induction intensity B8 is higher than the reference magnetic induction of 1.934 T calculated based on the formula 2.14 - 6.5 × Si. On the contrary, the iron loss and / or magnetic induction of Comparative Examples 22 - 28 are inferior to the reference values obtained from the above calculations, and even the rolling is difficult, resulting in strip breakage.

[0162] In addition, the present invention also uses a laser scoring method to refine the finished magnetic domains of the 0.13 mm finished samples in Examples 23-29 in Table 5-2, and the iron loss comparison results before and after scoring are listed in Table 6.

[0163] Table 6

[0164] Number <![CDATA[Iron loss P before notching 17 / 50 (W / kg)]]> <![CDATA[Post-Notch Iron Loss P 17 / 50 (W / kg)]]> Example 23 0.596 0.543 Example 24 0.563 0.498 Example 25 0.602 0.536 Example 26 0.592 0.524 Example 27 0.575 0.505 Example 28 0.579 0.499 Example 29 0.609 0.533

[0165] It can be seen from Table 6 that the iron loss of each embodiment after notching is reduced compared with its original iron loss.

[0166] In summary, it can be seen that the high magnetic induction oriented silicon steel and the manufacturing method thereof described in the present invention have significant advantages and beneficial effects compared with the prior art, can improve product quality, reduce manufacturing costs and avoid common problems, and have good application prospects.

[0167] It should be pointed out that the composition design and manufacturing process described in the present invention are not only applicable to thin-gauge oriented silicon steel of 0.13-0.20 mm, but also to oriented silicon steel of conventional thickness, such as oriented silicon steel of 0.23-0.30 mm. For oriented silicon steel of conventional thickness, the prominence of the problem in the present invention may be relatively low, but since the manufacturing principles of oriented silicon steels of different thicknesses are similar, it can be considered that the technical solution proposed in the present invention is also applicable to the manufacturing of oriented silicon steel of conventional thickness.

[0168] It should be noted that the combination of the various technical features in this case is not limited to the combination described in the claims of this case or the combination described in the specific embodiments. All technical features recorded in this case can be freely combined or combined in any way unless there is a contradiction between them.

[0169] It should also be noted that the above-listed embodiments are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made therewith can be directly derived or easily associated with by those skilled in the art from the contents disclosed in the present invention, and all should belong to the protection scope of the present invention.

Claims

1. A high magnetic induction oriented silicon steel, which contains Fe and other inevitable impurities, is characterized in that, It also contains chemical elements with the following mass percentages: C≤0.005％； Si: 3.0 - 3.8%; Als: 0.010 - 0.035%; Mn: 0.05 - 0.20%; Among them, in other inevitable impurity elements, N ≤ 0.005%, S ≤ 0.005%, V ≤ 0.005%, Ti ≤ 0.005%; Among them, the average secondary grain size of the high magnetic induction oriented silicon steel is 6 - 16 mm; among which, the area percentage of secondary grains with an average deviation angle between the rolling direction and the <001> direction within the range of 0° - 3° in all secondary grains > 50%.

2. The high magnetic induction oriented silicon steel according to claim 1, wherein The mass percentages of its various chemical elements are: C≤0.005％； Si: 3.0 - 3.8%; Als: 0.010 - 0.035%; Mn: 0.05 - 0.20%; The balance is Fe and other inevitable impurities; among other inevitable impurity elements, N ≤ 0.005%, S ≤ 0.005%, V ≤ 0.005%, Ti ≤ 0.005%.

3. The high magnetic induction oriented silicon steel according to claim 1 or 2, characterized in that It also contains at least one of the following chemical elements: P: 0.01 - 0.08%; Cr: 0.01 - 0.40%, Sn: 0.03 - 0.30%, Cu: 0.01 - 0.40%, 0 < Sb ≤ 0.1%, 0 < Bi ≤ 0.1%, 0 < Nb ≤ 0.1%, 0 < Mo ≤ 0.1%.

4. The high magnetic induction oriented silicon steel according to claim 1 or 2, characterized in that, Its thickness is 0.13 - 0.20 mm.

5. The high magnetic induction oriented silicon steel according to claim 1 or 2, characterized in that, The area percentage of secondary grains with a size < 6 mm or > 16 mm in all secondary grains < 15%.

6. The high magnetic induction oriented silicon steel according to claim 1 or 2, characterized in that, Its typical iron loss P 17 / 50 ≤0.86 + 2×plate thickness - 16×Si, typical magnetic induction intensity B8 ≥ 2.14 - 6.5×Si, where the unit parameter of the plate thickness is mm, and Si is substituted with the mass percentage content of Si element, P 17 / 50 The unit parameter of The unit parameter of B8 is T.

7. The manufacturing method of the high magnetic induction oriented silicon steel according to any one of claims 1-6, characterized in that, It includes the steps: (1) Smelting and casting; (2) Slab heating; (3) Hot rolling; (4) First cold rolling (5) Intermediate annealing; (6) Second cold rolling; (7) Decarburizing annealing, nitriding treatment, coating with an isolating agent coating, and the average primary grain size of the obtained decarburized annealed sheet is 6 - 18 μm, and the proportion of Goss grains with a deviation angle less than 15° is greater than 1.5%; (8) High - temperature annealing; (9) Insulating coating and skin - pass annealing.

8. The manufacturing method according to claim 7, characterized in that, In step (2), the slab heating temperature ≤ 1250°C.

9. The manufacturing method according to claim 7, characterized in that, In step (4), the first cold rolling uses tandem cold rolling, and its reduction ratio is 50 - 75%.

10. The manufacturing method according to claim 7, characterized in that, In step (5), the intermediate annealing temperature is 900 - 1050°C.

11. The manufacturing method according to claim 7, characterized in that, In step (6), the second cold rolling uses tandem cold rolling, and its reduction ratio is 60 - 85%.

12. The manufacturing method according to claim 7, characterized in that, There is a hot - rolled sheet annealing step between step (3) and step (4), and the hot - rolled sheet annealing temperature ≤ 1000°C.

13. The manufacturing method according to claim 7, characterized in that, In step (7), the decarburizing annealing temperature is 800 - 900°C, the decarburizing annealing time is 80 - 170 s, and the heating rate is 30 - 150°C / s.

14. The manufacturing method according to claim 7, characterized in that, In step (7), the nitrogen content of the decarburized annealed sheet after nitriding treatment is 160 - 260 ppm.

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