Oriented silicon steel and manufacturing method therefor

Abstract

Disclosed in the present invention is oriented silicon steel. In addition to Fe and inevitable impurities, the oriented silicon steel further contains the following chemical elements in percentages by mass: C: 0.020-0.080%, Si: 2.00-4.50%, Mn: 0.01-0.30%, 0＜S≤0.005%, Als: 0.010-0.040%, N: 0.002-0.01%, Nb: 0.005-0.08%, Sb: 0.01-0.30%, Cr: 0.01-0.30%, Bi: 0.01-0.60%, and at least one of P: 0.01-0.10%, Sn: 0.01-0.30% and Cu: 0.01-0.50%. In addition, further disclosed in the present invention is a manufacturing method for the oriented silicon steel. The oriented silicon steel has excellent magnetic performance and also has relatively low magnetostriction.

Description

A kind of oriented silicon steel and its manufacturing method Technical Field

[0001] The present disclosure relates to a steel material and a method for manufacturing the same, and in particular to a grain-oriented silicon steel and a method for manufacturing the same. Background Art

[0002] As we all know, oriented silicon steel is a kind of steel with sharp {110} <001> Grain-oriented silicon steel is a soft magnetic material characterized by grains with Gaussian orientation. Its production process is long, complex, and rigorous. Grain-oriented silicon steel is commonly used in the manufacture of transformer cores and is an important functional material in this process.

[0003] In existing technology, grain-oriented silicon steel can be divided into conventional grain-oriented silicon steel (CGO) and high magnetic induction grain-oriented silicon steel (Hi-B) based on its magnetic properties and Gaussian grain orientation. Compared to CGO steel, Hi-B steel has lower iron loss, higher magnetic induction, and less magnetostriction.

[0004] At present, high magnetic induction oriented silicon steel in the existing technology is generally produced by two technical routes: one route is the "inherent inhibitor method", that is, by heating the ingot at high temperature (1350-1400°C) to dissolve the inhibitor-forming elements, and then precipitating them in a fine and dispersed manner during the hot rolling and normalizing process to obtain sufficient inhibitors and inhibitory ability; the other route is the "obtained inhibitor method", that is, by adjusting the inhibitor element content, the ingot is heated at low temperature (usually 1100-1250°C) to precipitate some inhibitors during the hot rolling and normalizing process, and then new inhibitors are obtained through a nitriding process before high-temperature annealing to meet the inhibition ability required for secondary recrystallization during the high-temperature annealing process.

[0005] Compared to the "intrinsic inhibitor method," the "acquired inhibitor method" offers advantages such as lower billet heating temperatures, better billet surface quality, lower equipment energy consumption, and more stable magnetic properties in the finished product. Therefore, the "acquired inhibitor method" using low-temperature billet heating is currently a hot topic of research for grain-oriented silicon steel manufacturers both domestically and internationally.

[0006] For example, Chinese patent publication number CN102471819A, published on May 23, 2012, and entitled "Method for Manufacturing Direct-Oriented Magnetic Steel Sheet," discloses a method for producing grain-oriented silicon steel using a hot coiling process. The process involves soaking the steel billet at 1100-1150°C before hot rolling. Following rough hot rolling, the intermediate billet is coiled at 800-1000°C and held at this temperature for at least 300 seconds. Finish rolling then proceeds to below 1000°C. After finish rolling, the steel undergoes decarburization annealing, nitriding to a nitriding concentration of 220 ppm, and high-temperature annealing to obtain the finished product. Using this technical solution, researchers have found that coiling and holding effectively controls the precipitation morphology of the inhibitor, resulting in the precipitation of steel grade B as a composite of BN on MnS or MnSe, ensuring fine and uniform primary recrystallized grains and stable magnetic properties. The method controls the precipitation of inhibitors and the size of primary recrystallization by adding a hot coil box process, thereby ensuring stable production of the product.

[0007] Another example is Chinese patent document CN104726763A, published on June 24, 2015, and entitled "A Hot Rolling Method for Electrical Steel." This patent discloses a hot rolling method for electrical steel that utilizes heating coil boxes installed before and after the rolling mill. The method controls the thickness of the cast slab to 30-300 mm, the slab heating temperature to 950-1180°C, the rough rolling end temperature to 900-1000°C, the intermediate slab thickness to 10-45 mm, and the finishing temperature to 850-1000°C. This invention aims to utilize the hot coil boxes for insulation between hot rolling passes to reduce the slab heating temperature, control the solution precipitation of inhibitors, and alleviate the problem of uneven temperatures at the head and tail of the hot coils, thereby lowering the slab heating temperature while maintaining stable product performance.

[0008] Another example is Chinese patent publication CN101210297A, published on July 2, 2008, and entitled "A Method for Producing Grain-Oriented Silicon Steel." This patent discloses a method for producing grain-oriented silicon steel using a hot coil box after hot rolling. The method controls the strip temperature entering the finishing mill to 1100-1250°C, the finishing exit temperature to greater than 800°C, and laminar cooling after rolling. This method controls the precipitation of inhibitors during continuous casting during hot rolling, and ensures uniform product properties through a high-temperature, short, and rapid hot rolling heating process.

[0009] The aforementioned patent documents demonstrate that the hot coiling process improves the uniformity of hot-rolled microstructure and inhibitor precipitation control in grain-oriented silicon steel, while also promoting the stability of its magnetic properties. These patents also utilize hot coiling technology to achieve stable production of grain-oriented silicon steel, but they do not significantly improve its magnetic properties. From the perspective of ensuring magnetic stability, it is hoped that precise control of steelmaking composition and appropriate adjustments to post-processing processes can achieve uniform and stable magnetic properties in grain-oriented silicon steel, without the need for hot coiling technology.

[0010] In addition, it is also desired to ensure that the oriented silicon steel has excellent magnetic properties while also having low magnetostriction. However, the magnetostriction of the oriented silicon steel in the above prior art is relatively high. Summary of the Invention

[0011] One of the objectives of the present disclosure is to provide a grain-oriented silicon steel having excellent magnetic properties and low magnetostriction.

[0012] In order to achieve the above-mentioned object, the present disclosure provides a grain-oriented silicon steel, which, in addition to Fe and unavoidable impurities, further contains the following chemical elements in the following mass percentages:

[0013] C: 0.020~0.080%, Si: 2.00~4.50%, Mn: 0.01~0.30%, 0<S≤0.005%, Als: 0.010~0.040%, N: 0.002~0.01%, Nb: 0.005~0.08%, Sb: 0.01~0.30%, Cr: 0.01~0.30%, Bi: 0.01~0.60%, and at least one selected from P: 0.01~0.10%, Sn: 0.01~0.30% and Cu: 0.01~0.50%.

[0014] In some embodiments, the mass percentage of each chemical element in the grain-oriented silicon steel is:

[0015] C: 0.020~0.080%, Si: 2.00~4.50%, Mn: 0.01~0.30%, 0<S≤0.005%, Als: 0.010~0.040%, N: 0.002~0.01%, Nb: 0.005~0.08%, Sb: 0.01~0.30%, Cr: 0.01~0.30%, Bi: 0.01~0.60%, and at least one selected from P: 0.01~0.10%, Sn: 0.01~0.30% and Cu: 0.01~0.50%, and the balance is Fe and unavoidable impurities.

[0016] In some embodiments, the average diameter D of the secondary recrystallized grains in the finished product of the grain-oriented silicon steel is less than 12 mm, preferably D≤11 mm, and more preferably D≤10 mm. When the average diameter D of the secondary recrystallized grains in the finished product of the grain-oriented silicon steel is less than 12 mm, the finished product can have excellent magnetic properties, especially low magnetostriction.

[0017] In some embodiments, the magnetic induction B of the oriented silicon steel 800 ≥1.95T, preferably B 800 ≥1.952T.

[0018] In some embodiments, the iron loss P of the grain-oriented silicon steel is 17 / 50 ≤0.74W / kg, preferably P 17 / 50 ≤0.719W / kg.

[0019] In some embodiments, the magnetostriction L of the oriented silicon steel v A≤50dB, preferably L v A≤48dB.

[0020] In some embodiments, the grain-oriented silicon steel has a thickness of 0.10 to 0.30 mm.

[0021] The present disclosure also provides a method for manufacturing the above-mentioned grain-oriented silicon steel, comprising the following steps:

[0022] (1) smelting and casting to obtain slabs;

[0023] (2) heating the slab;

[0024] (3) Hot rolling, which includes: rough rolling, coiling and holding in a hot coil box, and finishing rolling; wherein the rough rolling end temperature is higher than 960°C; the coiling temperature is 830-1060°C, the coiling time is 30-200s; the finishing rolling start temperature is lower than 1050°C;

[0025] (4) Normalizing annealing, the normalizing annealing temperature is 600-1000℃;

[0026] (5) Cold rolling;

[0027] (6) Decarburization annealing;

[0028] (7) Nitriding;

[0029] (8) Applying annealing isolation agent;

[0030] (9) High temperature annealing;

[0031] (10) Insulation coating and laser scoring.

[0032] In some embodiments, in the method of the present disclosure, the average diameter of recrystallized grains in the surface layer of the hot-rolled plate obtained after step (3) is d1>40 μm, preferably d1>60 μm, and more preferably d1>65 μm.

[0033] In some embodiments, in the method of the present disclosure, the average diameter of the recrystallized grains in the surface layer of the normalized plate obtained after step (4) is d2>120 μm, preferably d2>130 μm, and more preferably d2>135 μm.

[0034] In some embodiments, in the method of the present disclosure, the average diameter d1 of the recrystallized grains in the surface layer of the hot-rolled plate obtained after step (3) and the average diameter d2 of the recrystallized grains in the surface layer of the normalized plate obtained after step (4) satisfy the following relationship: d1 + d2 < 300 μm. When the average diameter d1 of the recrystallized grains in the surface layer of the hot-rolled plate and the average diameter d2 of the recrystallized grains in the surface layer of the normalized plate are controlled to satisfy the above relationship, a perfect match between the hot-rolled plate structure and the normalized plate structure can be further achieved.

[0035] In some embodiments, in step (2) of the method of the present disclosure, the slab heating temperature is 900-1150°C.

[0036] In some embodiments, in step (4) of the method of the present disclosure, the normalizing annealing time is 20 to 200 seconds.

[0037] In some embodiments, in step (5) of the method of the present disclosure, the cold rolling reduction ratio is greater than 80%, preferably the cold rolling reduction ratio is greater than or equal to 88%.

[0038] In some embodiments, in step (6) of the method of the present disclosure, the decarburization annealing temperature is 800-900°C.

[0039] In some embodiments, in step (7) of the disclosed method, the nitriding amount is 50 to 280 ppm.

[0040] In some embodiments, in step (9) of the disclosed method, the high temperature annealing temperature is 1100-1250° C., and the annealing time is greater than 25 h.

[0041] The disclosed manufacturing method utilizes the "inhibitor acquisition" method of low-temperature slab heating, leveraging the positive effects of the hot coiling process and grain boundary segregation elements on the microstructure uniformity and inhibitory effect of hot-rolled oriented silicon steel sheets. Furthermore, by controlling the grain size of the hot-rolled and normalized sheets, the disclosed manufacturing method further improves the magnetic properties of oriented silicon steel while reducing energy consumption during the production process, resulting in a highly efficient and energy-efficient overall production process. DETAILED DESCRIPTION

[0042] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0043] Herein, the average diameter of the crystallites is determined by the intercept method.

[0044] In this paper, the magnetic induction B 800 Indicates the magnetic induction intensity of the material when the magnetic field strength is 800 amperes per meter (A / m). 800 The measurement was carried out in accordance with the national standard GB / T 13789-2008 (magnetic properties of single electrical steel strip).

[0045] In this paper, the iron loss P 17 / 50 It indicates the iron loss value of the material under the conditions of a frequency of 50 Hz and a maximum magnetic induction intensity of 1.7 Tesla (T). 17 / 50 The measurement was carried out in accordance with the national standard GB / T 13789-2008 (magnetic properties of single electrical steel strip).

[0046] In this paper, magnetostrictive L v A was measured according to IEC technical report IEC / TP 62581 using a non-contact laser Doppler vibrometer at B = 1.7 T and f = 2 MPa.

[0047] Herein, the "surface layer" of the hot-rolled plate or normalized plate refers to the layer from the surface to 1 / 8 of the plate thickness of the hot-rolled plate or normalized plate.

[0048] In the grain-oriented silicon steel disclosed herein, the design principles of each chemical element are specifically described as follows:

[0049] C: In the grain-oriented silicon steel disclosed herein, adding an appropriate amount of C ensures an appropriate proportion of γ phase during hot rolling and normalizing, facilitating inhibitor precipitation. When the C content in the steel is less than 0.020%, the γ phase ratio is low, hindering inhibitor precipitation. However, when the C content in the steel exceeds 0.080%, decarburization costs increase. Therefore, in the grain-oriented silicon steel disclosed herein, the mass percentage of C is controlled between 0.020% and 0.080%.

[0050] Si: In the oriented silicon steel disclosed in the present invention, Si is the main element for reducing iron loss. In order to ensure the quality of the finished steel, the Si content in the steel should not be too low. When the Si content in the steel is lower than 2.00%, it is difficult to reduce the iron loss of the steel. Correspondingly, the Si content in the steel should not be too high either. When the Si content in the steel is higher than 4.50%, it will cause difficulties in cold rolling and reduce the yield rate. Based on this, in the oriented silicon steel disclosed in the present invention, the mass percentage of the Si element is controlled between 2.00 and 4.50%.

[0051] Mn: In the oriented silicon steel disclosed herein, adding an appropriate amount of Mn element can effectively improve the structure and rollability of the oriented silicon steel. However, the Mn content in the steel should not be too high. When the Mn content in the steel is higher than 3.0%, it will lead to deterioration of the magnetic properties of the finished product. In order to ensure the performance of the oriented silicon steel, in the oriented silicon steel disclosed herein, the mass percentage of the Mn element is controlled between 0.01 and 0.30%, preferably 0.02 to 0.30%, and more preferably 0.08 to 0.30%.

[0052] S: In the grain-oriented silicon steel disclosed herein, S can form auxiliary inhibitors such as MnS and Cu2S. However, it is important to note that the S content in the steel should not be too high. Excessive S content in the steel significantly increases the heating temperature for the ingot, hindering production. Therefore, in the grain-oriented silicon steel disclosed herein, the mass percentage of S is controlled to 0 < S ≤ 0.005%.

[0053] Als: In the grain-oriented silicon steel disclosed herein, Als is a key element in the formation of the primary inhibitor, AlN. However, it's important to note that excessive Als content in the steel can lead to coarsening of the AlN inhibitor, while low Als content can lead to insufficient inhibitory properties. Therefore, the Als content in the steel must be strictly controlled. In the grain-oriented silicon steel disclosed herein, the Als content is controlled within a range of 0.010% to 0.040% by weight.

[0054] N: In the grain-oriented silicon steel disclosed herein, the addition of an appropriate amount of N can inhibit grain growth. The added N combines with AlS to form AlN prior to nitriding, effectively suppressing the growth of primary recrystallized grains. When the N content in the steel is less than 0.002%, it fails to effectively inhibit the growth of primary recrystallized grains. When the N content exceeds 0.01%, steelmaking becomes significantly more difficult. Therefore, in the grain-oriented silicon steel disclosed herein, the N content is controlled between 0.002% and 0.01% by weight.

[0055] Nb: In the oriented silicon steel disclosed in the present invention, the Nb element can form an auxiliary inhibitor Nb (C, N), which plays the role of an auxiliary inhibitor. In addition, since the solid solution temperature of Nb (C, N) is relatively low, it can also play a role in reducing the heating temperature of the ingot. When the Nb element content in the steel is too low, the inhibitory effect of the formed inhibitor Nb (C, N) is not obvious; when the Nb element content in the steel is too high, the inhibitory force will be too strong, hindering the occurrence of secondary recrystallization. Based on this, in the oriented silicon steel disclosed in the present invention, the mass percentage of the Nb element is controlled between 0.005 and 0.08%.

[0056] In the oriented silicon steel disclosed herein, Sb, Cr, and Bi are all grain boundary segregation elements. Adding an appropriate amount of Sb, Cr, and Bi elements to the steel can play the role of auxiliary inhibitors. However, when the content of Sb, Cr, and Bi elements in the steel is too high, it will have an adverse effect on decarburization and nitriding; when the content of Sb, Cr, and Bi elements in the steel is too low, the auxiliary inhibitory effect is not obvious. Therefore, in the oriented silicon steel disclosed herein, the mass percentage of the Sb element is controlled between 0.01 and 0.30%, preferably 0.09 to 0.30%, the mass percentage of the Cr element is controlled between 0.01 and 0.30%, preferably 0.08 to 0.30%, and the mass percentage of the Bi element is controlled between 0.01 and 0.60%, preferably 0.09 to 0.60%, and more preferably 0.19 to 0.60%.

[0057] In the oriented silicon steel disclosed herein, P and Sn are also grain boundary segregation elements. Adding an appropriate amount of P and Sn to the steel can act as an auxiliary inhibitor. However, when the content of P and Sn in the steel is too high, it will have an adverse effect on decarburization and nitriding; when the content of P and Sn in the steel is too low, the auxiliary inhibitory effect is not obvious. Therefore, in the oriented silicon steel disclosed herein, when containing the above-mentioned elements, the mass percentage of P element can be controlled between 0.01 and 0.10%, and the mass percentage of Sn element can be controlled between 0.01 and 0.30%, preferably between 0.14 and 0.30%.

[0058] In the present disclosure, adding an appropriate amount of Cu element to the steel can not only form an auxiliary inhibitor of Cu2S, but also effectively expand the γ phase region, which is conducive to the precipitation of other inhibitors. However, it should be noted that the Cu element content in the steel should not be too high. When the Cu element content in the steel is higher than 0.5%, the production cost will increase. However, when the Cu element content in the steel is lower than 0.01%, the role it plays is not obvious. Based on this, in the oriented silicon steel disclosed in the present disclosure, when Cu is contained, the mass percentage of the Cu element can be controlled between 0.01 and 0.50%, preferably 0.05 to 0.50%.

[0059] The method for manufacturing grain-oriented silicon steel disclosed herein comprises the following steps:

[0060] (1) smelting and casting to obtain slabs;

[0061] (2) heating the slab;

[0062] (3) Hot rolling, which includes: rough rolling, coiling and holding in a hot coil box, and finishing rolling; wherein the rough rolling end temperature is higher than 960°C; the coiling temperature is 830-1060°C, the coiling time is 30-200s; the finishing rolling start temperature is lower than 1050°C;

[0063] (4) Normalizing annealing, the normalizing annealing temperature is 600-1000℃;

[0064] (5) Cold rolling;

[0065] (6) Decarburization annealing;

[0066] (7) Nitriding;

[0067] (8) Applying annealing isolation agent;

[0068] (9) High temperature annealing;

[0069] (10) Insulation coating and laser scoring.

[0070] Through extensive experimental research and analysis, the inventors have discovered that when hot-rolled coils are coiled and held within a suitable temperature range after rough rolling, the temperature difference between the head and tail of the hot-rolled coil is minimized, inhibitors disperse and precipitate, and grain recrystallization of the hot-rolled plate structure is more complete. Furthermore, post-coiling insulation can be achieved by utilizing the heat of the rough-rolled coil itself to heat each layer, eliminating the need for additional heating equipment or steps. If the coiling temperature exceeds 1060°C or the coiling time exceeds 200 seconds, the grain structure of the intermediate billet and the precipitated inhibitors will coarsen, adversely affecting subsequent microstructural development.

[0071] In addition, the inventors' research on the evolution of microstructures under different hot rolling and normalizing processes found that for hot-rolled plates coiled at 830-1060°C, when subjected to a subsequent normalizing annealing temperature of 600-1000°C, the surface layers (the layer from the surface to 1 / 8 of the plate thickness) of the hot-rolled and normalized plates exhibited perfect recrystallization, with the average recrystallized grain diameter d1 of the hot-rolled plate surface being greater than 40 μm, and the average recrystallized grain diameter d2 of the normalized plate surface being greater than 120 μm. Accordingly, if the hot-rolled plate is not coiled and held, or if the normalizing annealing temperature after coiling and holding is higher than 1000°C or lower than 600°C, the surface grain diameters of the hot-rolled and normalized plates will not reach the ideal size or the two will not be well matched, resulting in poor magnetic properties of the final product.

[0072] In addition, in the technical solution disclosed herein, in step (3), due to the addition of an intermediate coiling process during hot rolling of the hot-rolled plate, the recrystallization of the surface structure of the hot-rolled plate is more complete, and some inhibitors are also dispersed and precipitated. Therefore, the normalizing annealing temperature of the normalizing step in step (4) cannot be too high. If annealing is performed using a conventional normalizing annealing process (1100-1200°C), not only will the grain structure of the normalized plate be too large, but the inhibitors will also coarsen, ultimately leading to deterioration of the magnetic properties.

[0073] In step (8) of the present disclosure, an annealing separator is applied to the nitrided plate. The annealing separator used can be MgO.

[0074] In step (2) of the method for producing grain-oriented silicon steel disclosed herein, the slab heating temperature is 900-1150°C.

[0075] In the manufacturing method disclosed herein, since the "inhibitor acquisition method" is adopted, the inhibitor element content in the cast slab is relatively low. Therefore, during the slab heating process in step (2), the slab heating temperature can be controlled between 900 and 1150°C. This is because: if the slab heating temperature is higher than 1150°C, it will not only increase energy consumption but also increase the heat load of the heating furnace; if the slab heating temperature is lower than 900°C, the inhibitor elements cannot be effectively dissolved.

[0076] In step (6) of the method for producing grain-oriented silicon steel disclosed herein, the decarburization annealing temperature is 800-900°C.

[0077] In the manufacturing method disclosed herein, the decarburization annealing temperature in step (6) is controlled to be 800-900°C. This is because: when the decarburization annealing temperature is higher than 900°C, the primary recrystallized grains will be too coarse, affecting the secondary recrystallization; and when the decarburization annealing temperature is lower than 800°C, the decarburization effect will be less obvious.

[0078] In step (7) of the method for producing grain-oriented silicon steel disclosed herein, the nitriding amount is 50 to 280 ppm.

[0079] In the manufacturing method disclosed herein, since the "inhibitor acquisition method" is employed, nitriding treatment must be performed before high-temperature annealing to form inhibitors capable of inhibiting the growth of primary recrystallized grains. In step (7), when the nitriding amount is less than 50 ppm, the amount of inhibitor formed is insufficient; when the nitriding amount is greater than 280 ppm, the formation of the magnesium silicate bottom layer during the high-temperature annealing process is adversely affected. Therefore, during the nitriding process of step (7) of the method disclosed herein, the nitriding amount is controlled between 50 and 280 ppm.

[0080] Compared with the prior art, the oriented silicon steel and its manufacturing method disclosed in the present invention have the following advantages and beneficial effects:

[0081] The oriented silicon steel disclosed herein adopts a reasonable chemical element composition design to obtain higher magnetic properties and lower magnetostriction.

[0082] The manufacturing method disclosed herein, based on a reasonable chemical element composition design and in combination with optimized process steps, can obtain oriented silicon steel with higher magnetic properties and lower magnetostriction on the basis of energy saving and consumption reduction, stable production and improved production efficiency.

[0083] The manufacturing method of the oriented silicon steel disclosed in the present invention is based on the "inhibitor acquisition method" of low-temperature ingot heating. By giving full play to the positive effects of the hot coil box process and the boundary segregation elements on the uniformity of the structure of the oriented silicon steel hot-rolled plate and the inhibitor effect, and combining the optimal normalizing process with the control of the grain size of the surface structure of the hot-rolled plate or the normalized plate, the magnetic properties of the oriented silicon steel are further improved, the magnetostriction is reduced, and the energy consumption of the production process is reduced, so that the entire production process has the characteristics of high efficiency and energy saving.

[0084] The oriented silicon steel disclosed in the present invention has excellent magnetic properties, can be effectively used to manufacture transformer cores, and has good promotion prospects and application value.

[0085] Example

[0086] The oriented silicon steel and the manufacturing method thereof disclosed in the present invention will be further explained and illustrated below in conjunction with specific embodiments. However, such explanation and illustration do not constitute an undue limitation to the technical solution disclosed in the present invention.

[0087] Examples 1-12 and Comparative Examples 1-14

[0088] The grain-oriented silicon steels of Examples 1-12 were prepared by the following steps:

[0089] (1) According to the chemical composition shown in Table 1, slabs were produced by smelting and casting.

[0090] (2) Heating the slab: The slab heating temperature is 900-1150°C.

[0091] (3) Hot rolling, which includes: rough rolling, coiling and heat preservation in a hot coil box, and finishing rolling; wherein the finishing temperature of rough rolling is higher than 960℃; the thickness of the intermediate billet after the rough rolling is 35-50mm; the coiling temperature is 830-1060℃, and the coiling time is 30-200s; the starting temperature of finishing rolling is lower than 1050℃.

[0092] (4) Normalizing: The normalizing annealing temperature is 600-1000°C, and the normalizing annealing time is 20-200s.

[0093] (5) Cold rolling: cold rolling reduction ratio>80%.

[0094] (6) Decarburization annealing: Control the decarburization annealing temperature to 800-900℃.

[0095] (7) Nitriding: Control the nitriding amount to 50-280ppm.

[0096] (8) Coating annealing isolation agent: MgO is used as the annealing isolation agent.

[0097] (9) High temperature annealing: Control the high temperature annealing temperature to 1100-1250℃ and the annealing time to be greater than 25h.

[0098] (10) Insulation coating and laser scoring: An insulation coating is applied to the sample after high-temperature annealing, and laser scoring is performed to obtain oriented silicon steel with excellent magnetic properties.

[0099] The comparative grain-oriented silicon steels of Comparative Examples 1-14 were prepared using the same steps as above, with the only differences being in the component content and / or specific process parameters.

[0100] Table 1 lists the mass percentage content of each chemical element in the grain-oriented silicon steels of Examples 1-12 and the comparative grain-oriented silicon steels of Comparative Examples 1-14. Table 2 lists the specific process parameters of the grain-oriented silicon steels of Examples 1-12 and the comparative grain-oriented silicon steels of Comparative Examples 1-14 in the above process steps.

[0101] In the above steps (3) and (4), the plates and strips of each embodiment and comparative example after hot rolling and normalization were observed and analyzed, and the average diameter d1 of the recrystallized grains in the surface layer of the hot-rolled plate (the layer from the surface to 1 / 8 of the plate thickness) and the average diameter d2 of the recrystallized grains in the surface layer of the normalized plate (the layer from the surface to 1 / 8 of the plate thickness) were respectively detected, and the relevant test results are listed in the following Table 3.

[0102] Table 3.

[0103] It can be seen from Table 3 above that the average diameter d1 of the recrystallized grains in the surface layer of the hot-rolled plates (the layer from the surface to 1 / 8 of the plate thickness) of Examples 1-12 is greater than 40 μm, the average diameter d2 of the recrystallized grains in the surface layer of the normalized plates (the layer from the surface to 1 / 8 of the plate thickness) is greater than 120 μm, and d1+d2 is less than 300 μm.

[0104] In contrast, the average diameter of the recrystallized grains in the surface layer of the hot-rolled plates or normalized plates of Comparative Examples 11-14 does not meet the above conditions.

[0105] The obtained oriented silicon steels of Examples 1-12 and comparative oriented silicon steels of Comparative Examples 1-14 were sampled respectively, and the secondary recrystallization average diameter, thickness, iron loss, magnetic induction and magnetostrictive vibration velocity sound pressure level L of the finished products of the oriented silicon steels were measured. v A was tested and the results are listed in Table 4 below. The relevant magnetic performance test methods are as follows:

[0106] Magnetic property test: Tested in accordance with the national standard GB / T 13789-2008 (magnetic property measurement method of single piece electrical steel strip).

[0107] Magnetostriction Testing: According to IEC Technical Report IEC / TP 62581, a non-contact laser Doppler vibrometer was used to measure the magnetostrictive vibration velocity sound pressure level (LvA) of the grain-oriented silicon steels of Examples 1-12 and Comparative Examples 1-14 under the conditions of B = 1.7 T and f = 2 MPa (in actual transformer operating conditions, the compressive stress experienced by grain-oriented silicon steel is 2-3 MPa). Herein, LvA refers to the magnetostrictive vibration velocity sound pressure level of the grain-oriented silicon steel under these test conditions, expressed in dB(A).

[0108] Table 4.

[0109] It can be seen from Table 4 above that the average diameter D of the secondary recrystallized grains of the finished products of the oriented silicon steel of Examples 1-12 is less than 12 mm, and the magnetic induction B 800 All are greater than 1.95T, iron loss P 17 / 50 All are less than 0.74W / kg, magnetostriction L v A is less than 50dB, and it has good magnetic properties and magnetostriction.

[0110] In contrast, the magnetic properties and magnetostriction L of Comparative Examples 1-14 v A performance is poor.

[0111] All publications, patent applications, patents, and other references mentioned in this disclosure are incorporated by reference in their entirety.

[0112] Although the present disclosure has been illustrated and described with reference to certain preferred embodiments thereof, it should be understood by those skilled in the art that the above description is provided to further illustrate the present disclosure in conjunction with specific embodiments thereof, and that the present disclosure is not limited to these descriptions. Those skilled in the art may make various changes in form and detail, including simple deductions or substitutions, without departing from the spirit and scope of the present disclosure.

Claims

1. A oriented silicon steel, wherein: In addition to Fe and inevitable impurities, the oriented silicon steel also contains the following chemical elements in the following mass percentages: C: 0.020-0.080%, Si: 2.00-4.50%, Mn: 0.01-0.30%, 0<S≤0.005%, Als: 0.010-0.040%, N: 0.002-0.01%, Nb: 0.005-0.08%, Sb: 0.01-0.30%, Cr: 0.01-0.30%, Bi: 0.01-0.60%, and at least one selected from P: 0.01-0.10%, Sn: 0.01-0.30% and Cu: 0.01-0.50%.

2. The oriented silicon steel according to claim 1, wherein: The mass percentage of each chemical element of the oriented silicon steel is: C: 0.020-0.080%, Si: 2.00-4.50%, Mn: 0.01-0.30%, 0<S≤0.005%, Als: 0.010-0.040%, N: 0.002-0.01%, Nb: 0.005-0.08%, Sb: 0.01-0.30%, Cr: 0.01-0.30%, Bi: 0.01-0.60%, and at least one selected from P: 0.01-0.10%, Sn: 0.01-0.30% and Cu: 0.01-0.50%, and the balance is Fe and unavoidable impurities.

3. The oriented silicon steel according to claim 1 or 2, wherein: The average diameter of the secondary recrystallized grains of the finished product of the oriented silicon steel is D<12 mm, preferably D≤11 mm, and more preferably D≤10 mm.

4. The oriented silicon steel according to any one of claims 1 to 3, wherein: The magnetic induction B of the oriented silicon steel 800 ≥1.95T; Iron loss P 17 / 50 ≤0.74W / kg, preferably P 17 / 50 ≤0.719W / kg; and / or magnetostriction L v A≤50dB, preferably L v A≤48dB.

5. The oriented silicon steel according to any one of claims 1 to 4, wherein: The thickness of the oriented silicon steel is 0.10-0.30 mm.

6. A method for manufacturing the grain-oriented silicon steel according to any one of claims 1 to 5, comprising the following steps: (1) smelting and casting to obtain slabs; (2) heating the slab; (3) hot rolling, which includes: rough rolling, coiling and heat preservation in a hot coil box, and finishing rolling; wherein the rough rolling end temperature is higher than 960°C; the coiling temperature is 830-1060°C, the coiling time is 30-200s; the finishing rolling start temperature is lower than 1050°C; (4) Normalizing annealing, the normalizing annealing temperature is 600-1000°C; (5) Cold rolling; (6) Decarburization annealing; (7) Nitriding; (8) Applying annealing isolation agent; (9) High temperature annealing; (10) Insulation coating and laser scoring.

7. The method of claim 6, wherein: The average diameter of recrystallized grains in the surface layer of the hot-rolled sheet obtained after step (3) is d1>40 μm, preferably d1>60 μm, and more preferably d1>65 μm.

8. The method according to claim 6 or 7, wherein: The average diameter of the recrystallized grains in the surface layer of the normalized plate obtained after step (4) is d2>120 μm, preferably d2>130 μm, and more preferably d2>135 μm.

9. The method according to any one of claims 6 to 8, wherein: The average diameter d1 of the recrystallized grains on the surface of the hot-rolled plate obtained after step (3) and the average diameter d2 of the recrystallized grains on the surface of the normalized plate obtained after step (4) satisfy the following relationship: d1+d2<300μm.

10. The method according to any one of claims 6 to 9, wherein: The process parameters in each step satisfy at least one of the following: In step (2), the slab is heated to a temperature of 900 to 1150°C; In step (4), the normalizing annealing time is 20 to 200 seconds; In step (5), the cold rolling reduction ratio is >80%, preferably ≥88%; In step (6), the decarburization annealing temperature is 800-900°C; In step (7), the nitriding amount is 50 to 280 ppm; and / or In step (9), the high temperature annealing temperature is 1100-1250° C., and the annealing time is greater than 25 hours.

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