Low magnetostriction oriented silicon steel and its manufacturing method

Abstract

A method for producing low magnetostriction oriented silicon steel is provided. The oriented silicon steel includes a silicon steel substrate and an insulating coating on the surface of the silicon steel substrate. The method for producing includes the following steps: performing one-sided laser etching on the silicon steel substrate; determining a deflection difference between a first surface and a second surface according to the power of the laser etching, and determining a difference in the amount of insulating coating on the first surface and the second surface based on the deflection difference; and forming an insulating coating on the first surface and the second surface. The amount of insulating coating on the second surface is greater than the amount of insulating coating on the first surface, and the amount of insulating coating on the first surface and the amount of insulating coating on the second surface satisfy the difference in the amount of insulating coating. By using the production method of the present invention, it is possible to solve the problem that the magnetostriction difference between both surfaces of the oriented silicon steel caused by one-sided laser etching is relatively large. Also provided is an oriented silicon steel produced by the above production method. A transformer core produced using oriented silicon steel makes it possible to reduce noise during the operation of a transformer.

Description

[Technical Field]

[0001] The present invention relates to a steel material and a manufacturing method thereof, and more particularly to a low magnetostriction oriented silicon steel and a manufacturing method thereof. [Background technology]

[0002] Currently, existing transformer cores are usually laminated or wound with oriented silicon steel. Transformer manufacturers mainly focus on two performance indicators: no-load loss characteristics and no-load excitation current characteristics, which correspond to the loss characteristics and excitation power characteristics of oriented silicon steel, respectively.

[0003] In recent years, as the market and users have become increasingly concerned with the noise characteristics of transformers, the noise characteristics of transformers have become an important indicator, similar to no-load loss, and this corresponds to the magnetostriction characteristics of oriented silicon steel. It should be noted that the dimensional change of oriented silicon steel sheets due to magnetization during AC excitation is known as magnetostriction, and is one of the main causes of transformer noise.

[0004] With the continuous optimization of processing technology and transformer design in transformer industries, magnetostriction of oriented silicon steel has become the main cause of transformer noise. The mechanism behind magnetostriction of oriented silicon steel is the shift and rotation of the magnetic domain by 90° away from the direction of easy magnetization during the magnetization process.

[0005] The ideal state for oriented silicon steel products is to have only 180° magnetic domains. However, in actual oriented silicon steel finished products, defects such as orientation deviation, inclusions, and grain boundaries cause additional small magnetic domains called lancet domains (90° magnetic domains) to occur within the 180° magnetic domains, reducing magnetostatic energy. Therefore, magnetostriction can be effectively reduced by reducing the number of 90° magnetic domains (closed magnetic domains).

[0006] In the prior art, the main methods used to reduce magnetostriction include: (1) the <001> (1) Improve the crystal plane orientation; (2) Reduce the thickness of the finished product; and (3) Increase the coating tension. By implementing these three technical solutions, the magnetostriction of the finished oriented silicon steel sheet can be reduced, thereby reducing the noise level of the transformer.

[0007] Patent Document 1, published on September 27, 2017, is titled "Grain-oriented electrical steel sheet, its manufacturing method, and method for predicting transformer noise characteristics" and discloses a grain-oriented electrical steel sheet, its manufacturing method, and a method for predicting transformer noise characteristics. Regarding the magnetostriction characteristics of grain-oriented electrical steel sheet, this patent discloses a technical solution in which the difference in tension between the front and rear of the forsterite coating is controlled to 0.5 MPa or more, while the difference in the total tension between the forsterite coating and the insulating coating is controlled to less than 0.5 MPa. The number of acceleration / deceleration points in the magnetostrictive speed level dλ / dt in one cycle of magnetostrictive vibration is set to four, and the magnitude of the speed level change between adjacent magnetostrictive speed level change points in the acceleration or deceleration section of the magnetostrictive vibration is set to 3.0 x 10 -4 sec -1 The magnetostriction can be reduced by adjusting the tension difference between the forsterite coatings and the total tension difference between the forsterite coating and the insulating coating. However, this method of adjusting the tension difference between the two surfaces of a grain-oriented silicon steel substrate that is laser-etched on one side is limited in its ability to improve the magnetostriction difference between the two surfaces. Furthermore, it is difficult to stably and cost-effectively control and produce grain-oriented electrical steel sheets that have excellent noise characteristics and minimal magnetostriction difference between the top and bottom surfaces in a single batch.

[0008] Patent Document 2, published on February 22, 2017, is titled "Grain-oriented electrical steel sheet with low iron loss and low magnetostriction" and discloses a grain-oriented electrical steel sheet with low iron loss and low magnetostriction. The grain-oriented electrical steel sheet of the present invention comprises a steel sheet substrate, a primary coating formed on the surface of the steel sheet substrate, and a tensile insulating coating formed on the surface of the primary coating, where the ratio of the thickness of the tensile insulating coating to the thickness of the primary coating is ∈(0.1,3), the thickness of the tensile insulating coating is ∈(0.5,4.5) μm, and the total tension of the primary coating and the tensile insulating coating is ∈(1,10) MPa. Magnetic domain control is achieved by irradiating the surface of the tensile insulating coating from above with a laser. A strip-shaped sample measuring 300 mm in length parallel to the rolling direction and 60 mm in length parallel to the transverse direction of the grain-oriented electrical steel sheet is taken from the grain-oriented electrical steel sheet. At least one side of the sample is pickled to remove the tensile insulating coating from the surface to a depth of 5 μm from the interface between the base steel sheet and the primary coating toward the base steel sheet. The amount of warpage of the sample is then measured. In this case, the amount of warpage meets the specified requirements. However, this technical solution only considers the thickness and tension of the primary coating and the tensile insulating coating. There are limitations to improving the magnetostriction of the grain-oriented silicon steel substrate, making it difficult to consistently and cost-effectively produce grain-oriented electrical steel sheets with excellent noise characteristics and minimal magnetostriction difference between the top and bottom surfaces.

[0009] Patent Document 3, published on October 12, 2016, entitled "Grain-oriented Electrical Steel Sheet for Low-Noise Transformers and Manufacturing Method Thereof," discloses a grain-oriented electrical steel sheet obtained by irradiating the steel sheet surface with an electron beam having a beam diameter d of 0.40 mm or less in a linear region extending in a direction intersecting the rolling direction (the modulated irradiation linear region is formed of repeating units connected to each other in the direction of the linear region, the periodic distance of the repeating units in the modulated irradiation linear region is 2 / 3 × d mm to 2.5 × d mm, and the repeat interval in the rolling direction of the modulated irradiation linear region is 4.0 mm to 12.5 mm). The electron beam intensity is at least sufficient to form elongated divided magnetic domains extending in the direction of the modulated irradiation linear region on the irradiated surface, but is not sufficient to cause coating damage on the irradiated surface or to form plastically strained regions. This makes it possible to perform magnetic domain refinement under conditions that simultaneously achieve low iron loss and low noise in transformers, which was previously considered difficult. However, this technical solution only considers the effect of the etching conditions on magnetostriction, and does not consider matching of the etching conditions with the coating conditions. Therefore, it is difficult to effectively, efficiently, collectively, stably, and cost-effectively produce grain-oriented electrical steel sheets that have excellent noise characteristics and minimal difference in magnetostriction between the top and bottom surfaces. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Chinese Patent Application Publication No. 107210109 [Patent Document 2] Chinese Patent Application Publication No. 106460111 [Patent Document 3] Chinese Patent Application Publication No. 106029917 Summary of the Invention

[0011] The present invention aims to solve the problem that the uneven stress distribution in existing grain oriented silicon steel caused by one-sided laser etching causes the steel sheet to bend toward the etched surface, resulting in a large difference in magnetostriction between the etched and unetched surfaces of the grain oriented silicon steel.

[0012] To achieve the above object, the present invention provides a method for producing low-magnetostriction grain-oriented silicon steel. The grain-oriented silicon steel includes a silicon steel substrate and an insulating coating on the surface of the silicon steel substrate. The method includes the following steps: performing one-sided laser etching on the silicon steel substrate (the surface of the silicon steel substrate that has been laser-etched on one side is referred to as the first surface, and the surface opposite to the first surface is referred to as the second surface); determining a deflection difference between the first and second surfaces based on the laser etching power, and determining a difference in the amount of insulating coating between the first and second surfaces based on the deflection difference; and forming an insulating coating on the first and second surfaces (the amount of insulating coating on the second surface is greater than the amount of insulating coating on the first surface, and the amount of insulating coating on the first and second surfaces satisfies the difference in the amount of insulating coating).

[0013] In the technical solution of the present invention, the difference in deflection (representing the distance from the center of the surface to the axis of the original steel sheet after bending) between the first and second surfaces of the silicon steel substrate can be determined according to the laser etching power. The difference in the amount of insulating coating to be applied to the first and second surfaces is then determined according to the difference in deflection. The insulating coating is applied to the first and second surfaces based on the difference in the amount of insulating coating. In this way, the difference in deflection between the first and second surfaces of the finished grain-oriented silicon steel product caused by single-sided laser etching is reduced by adjusting the tension difference between the insulating coatings on the first and second surfaces, thereby reducing the difference in magnetostriction between the first and second surfaces. Single-sided laser etching is a method commonly used in the prior art to refine the magnetic domains of grain-oriented silicon steel and reduce losses.

[0014] The method for forming an insulating coating further includes applying an insulating coating solution to the first surface and the second surface, and firing and sintering the insulating coating solution to form an insulating coating on the first surface and the second surface. The firing and sintering of the insulating coating solution can be performed according to conventional techniques.

[0015] Preferably, in the present invention, the power of the laser etching is controlled so that the resulting oriented silicon steel can exhibit an A-weighted magnetostriction rate level of 55 db(A) or less.

[0016] Furthermore, the laser etching power in the present invention is set to 0.5-2.5 mJ / mm to achieve the purpose of reducing noise during operation of the oriented silicon steel transformer core. 2 is set to

[0017] Furthermore, the power of the laser etching is set to 1 to 2 mJ / mm in order to further reduce the noise generated during operation of the transformer core made from the oriented silicon steel of the present invention. 2 is set to

[0018] Furthermore, in the manufacturing method of the present invention, the deflection difference is calculated based on the following formula:

[0019]

number

[0020] In the formula, W is the power of single-sided laser etching in mJ / mm 2 The deflection difference is expressed in mm.

[0021] The formulas for calculating the difference in deflection and the difference in the amount of insulating coating are empirical formulas that the inventors derived using data obtained by changing parameters such as the thickness of the silicon steel substrate, the power of the laser etching, the composition of the coating, and the thickness of the coating under the conditions of a specific etching device, and then adapted based on the obtained data.

[0022] Furthermore, the difference in the amount of insulating coating is calculated based on the following formula:

[0023]

number

[0024] In the formula, the unit of difference in the amount of insulating coating is g / m 2is.

[0025] Furthermore, the amount of insulating coating on the first surface is 4.0 to 4.5 g / m 2 is.

[0026] If the insulation coating is too thin, the tension applied to the substrate by the insulation coating will be too small, resulting in suboptimal magnetic properties.If the insulation coating is too thick, it will affect the lamination properties of the finished product and will be prone to defects such as powder shedding and white edges during shearing.

[0027] Furthermore, the thickness H of the silicon steel substrate is 0.18 mm≦H≦0.23 mm.

[0028] Typically, the thickness of the silicon steel substrate is 0.18 mm or more. If the substrate thickness exceeds 0.23 mm, the thickness increases and the rigidity increases, resulting in a decrease in sensitivity to the non-uniform stress distribution caused by laser etching after an insulating coating is formed on the surface. As a result, the deflection difference caused by the non-uniform stress distribution due to laser etching becomes smaller, and the above empirical formula does not fit.

[0029] Furthermore, the components of the insulating coating solution are as follows by mass percentage: at least one of aluminum dihydrogen phosphate and magnesium dihydrogen phosphate: 2% to 25%; colloidal silicon dioxide: 4% to 16%; chromic anhydride: 0.15% to 4.50%; and the remainder being water and other unavoidable impurities.

[0030] Insulation coatings are used to improve the insulating performance of silicon steel substrate surfaces. The insulation coating solution commonly used in the prior art is an aqueous solution mainly composed of chromic anhydride, colloidal SiO2, and phosphates of Mg and Al.

[0031] Furthermore, the silicon steel substrate in the present invention is manufactured according to the prior art by the following steps: step a: smelting and casting; step b: heating; step c: normalizing; step d: cold rolling; step e: decarburization annealing; step f: finish annealing; and step g: hot stretch annealing.

[0032] Furthermore, in step c, the silicon steel substrate is subjected to a two-stage normalizing treatment: first, the silicon steel substrate is heated to 1100-1200°C, then cooled to 900-1000°C at a cooling rate of 1°C / s-10°C / s, and finally cooled to room temperature at a cooling rate of 10°C / s-70°C / s.

[0033] Furthermore, in the cold rolling in step d, either a first cold rolling or a second cold rolling including an intermediate annealing step is performed.

[0034] Furthermore, in step e, primary recrystallization annealing is performed at 800 to 900°C, and then an annealing separator is applied to the surface of the silicon steel substrate.

[0035] In the manufacturing process of grain-oriented silicon steel in the prior art, an annealing separator such as magnesium oxide must be applied to the surface of the silicon steel substrate before high-temperature final annealing to prevent adhesion between steel sheets at high temperatures.

[0036] Furthermore, in the step f, the annealing temperature is controlled to 1100 to 1200°C, and the holding time is set to 20 to 30 hours.

[0037] Furthermore, in step g, the silicon steel substrate is first heated to 800 to 900°C, then held at that temperature for 10 to 30 seconds, and finally cooled to room temperature at a cooling rate of 5°C / sec to 50°C / sec.

[0038] On the other hand, the present invention provides low magnetostriction oriented silicon steel with minimal difference in magnetostriction between the etched and non-etched surfaces of the oriented silicon steel and good average magnetostriction.

[0039] Since the vibration generated by the iron core made from the low magnetostriction oriented silicon steel of the present invention is small, the noise level of the entire transformer equipped with this iron core is low.

[0040] In order to achieve the above object, the present invention provides a low-magnetostriction oriented silicon steel manufactured by a method for manufacturing low-magnetostriction oriented silicon steel, wherein the magnetostriction difference between the first surface and the second surface of the oriented silicon steel is 2 db(A) or less, and the average magnetostriction of the oriented silicon steel is 55 db(A) or less.

[0041] Compared with the prior art, the low magnetostriction-oriented silicon steel and its manufacturing method of the present invention have the following advantages and beneficial effects: By using the manufacturing method of the present invention, it is possible to obtain a difference in the amount of insulating coating on the first surface and the second surface according to the difference in deflection between the etched surface and the non-etched surface of the steel substrate, thereby adjusting the tension of the insulating coating on the etched surface (first surface) and the non-etched surface (second surface), and reducing the difference in magnetostriction between the etched surface and the non-etched surface.

[0042] According to the present invention, the prepared low-magnetostriction oriented silicon steel achieves a magnetostriction difference between the etched and unetched surfaces of the oriented silicon steel of ≦2 db(A) and an average magnetostriction of ≦55 db(A). Since the vibration generated by the iron core made from the low-magnetostriction oriented silicon steel is small, the overall noise level of the transformer equipped with this iron core is low. [Brief explanation of the drawings]

[0043] [Figure 1] FIG. 1 shows the magnetostriction curve of the etched surface of the grain oriented silicon steel of the present invention when the energy density of the laser etching is changed. [Figure 2] FIG. 2 shows the curve of the deflection difference between the first surface and the second surface of the silicon steel substrate of the present invention when the energy density of the laser etching is changed after one-sided laser etching of the silicon steel substrate. [Figure 3] FIG. 3 shows the difference in the amount of insulating coating on the first and second surfaces required to maintain the straightness of the silicon steel substrate of the present invention under various deflection differences. DETAILED DESCRIPTION OF THE INVENTION

[0044] Hereinafter, embodiments of the present invention will be described through certain specific embodiments. However, those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed herein. Although the description of the present invention will be presented together with preferred embodiments, it should be understood that the features of the present invention are not limited to these embodiments. Rather, the purpose of presenting the present invention together with the embodiments is to cover other options or modifications that may be derived based on the scope of the claims of the present invention. In the following, numerous specific details are described to provide a thorough understanding of the present invention. The present invention can be practiced without these details. Furthermore, some specific details are omitted in the description to avoid confusion or ambiguity in the focus of the present invention. It should be noted that, unless inconsistent, the embodiments of the present invention and the features of the embodiments can be combined with each other. [Example]

[0045] The silicon steel substrates of Examples 1 to 6 and the comparative steel sheets of Comparative Examples 1 to 4 are prepared by the following procedure: Smelting and casting: Smelting is carried out according to the chemical composition shown in Table 1 and then cast into slabs; Heating: Heat the plate to 1200-1280°C, hold for 1-4 hours, and then hot roll it into a steel strip; Normalizing: Apply two-stage normalizing treatment, firstly heat the steel strip to 1100-1200℃, then cool it to 900-1000℃ at a cooling rate of 1℃ / s-10℃ / s, and then cool it to room temperature at a cooling rate of 10℃ / s-70℃ / s; Cold rolling: Perform primary cold rolling or secondary cold rolling with intermediate annealing step; Decarburization annealing: Primary recrystallization annealing is performed at a temperature of 800-900°C, and then annealing separator is applied; Final annealing: the annealing temperature is 1100-1200°C, and the holding time is 20-30 hours; and Hot stretching annealing: First, the steel strip is heated to 800-900°C, held for 10-30 seconds, and then cooled to room temperature at a cooling rate of 5°C / s-50°C / s to obtain a silicon steel substrate.

[0046] It should be noted that the relevant operations and specific manufacturing process parameters of the grain oriented silicon steels of Examples 1 to 6 of the present invention satisfy the preferred design specifications of the technical solutions of the present invention. However, the comparative steel sheets of Comparative Examples 1 to 4 do not control the difference in the amount of insulating coating corresponding to the difference in deflection between the two surfaces caused by laser etching.

[0047] Table 1 shows the mass percentages of various chemical elements in the silicon steel substrate and the thickness of the finished grain-oriented silicon steel for the low-noise grain-oriented silicon steels of Examples 1 to 6 and the comparative steel sheets of Comparative Examples 1 to 4. In the following examples and comparative examples, the remainder of the chemical composition of the silicon steel substrate / steel sheet is Fe and other unavoidable impurities.

[0048] [Table 1]

[0049] In the present invention, to obtain grain-oriented silicon steel with the desired performance, one-sided laser etching is performed on a silicon steel substrate. The power of the laser etching determines the difference in deflection between the first and second surfaces, and the difference in the amount of insulating coating is determined based on this difference in deflection. An insulating coating is then formed on the first and second surfaces to obtain the grain-oriented silicon steel. The amount of coating on the silicon steel substrate surface must satisfy the following conditions: the amount of insulating coating on the second surface must be greater than the amount of coating on the first surface, and the amount of insulating coating on the first surface and the amount of insulating coating on the second surface must satisfy the difference in the amount of insulating coating.

[0050] The specific chemical compositions of the insulating coating solutions applied to the silicon steel substrates of Examples 1 to 6 and the comparative steel sheets of Comparative Examples 1 to 4 can be expressed in mass percentage as follows: at least one of aluminum dihydrogen phosphate or magnesium dihydrogen phosphate: 2% to 25%; colloidal silicon dioxide: 4% to 16%; chromic anhydride: 0.15% to 4.50%; and the remainder being water and other unavoidable impurities.

[0051] Table 2 shows the specific chemical compositions of the insulating coating solutions applied to the surfaces of the silicon steel substrates of Examples 1-6 and the comparative steel sheets of Comparative Examples 1-4.

[0052] [Table 2]

[0053] Specific parameters for the manufacturing process of the silicon steel substrates of Examples 1 to 6 and the comparative steel plates of Comparative Examples 1 to 4 are shown in Table 3-1.

[0054] [Table 3]

[0055] Table 3-2 shows the power, deflection difference, amount of insulating coating on the surface, and difference in the amount of insulating coating between the two sides of the finally obtained oriented silicon steel for the one-sided laser etching performed on the silicon steel substrates of Examples 1 to 6 and the comparative steel plates of Comparative Examples 1 to 4.

[0056] [Table 4]

[0057] The prepared oriented silicon steels of Examples 1 to 6 and the comparative steel sheets of Comparative Examples 1 to 4 were each sampled. Using a non-contact laser Doppler vibrometer TD9600, the magnetostriction performance (A-weighted magnetostriction rate level LvA) of the steel sheet samples of the Examples and Comparative Examples was measured under the conditions of B = 1.7 T and f = -2 MPa (under the actual operating conditions of a transformer, the oriented silicon steel is subjected to a compressive stress of 2 to 3 MPa). The specific measurement method is described in the International Electrotechnical Commission (IEC) Technical Report - IEC / TP 62581. The magnetostriction performance test results obtained for each Example and Comparative Example are shown in Table 4.

[0058] Table 4 shows the performance test results of the oriented silicon steels having low noise characteristics of Examples 1 to 6 and the comparative steel sheets of Comparative Examples 1 to 4.

[0059] [Table 5]

[0060] Further, 240 KVA three-phase transformers were fabricated using the oriented silicon steels of Examples 1 to 6 and the comparative steel sheets of Comparative Examples 1 to 4. Noise detection was performed on each of the three-phase transformers fabricated in the examples and comparative examples under magnetization conditions of 50 Hz and 1.7 T (GB / T 1094.10-2003). The test results are shown in Table 5.

[0061] Table 5 shows the results of noise tests on 240 KVA three-phase transformers manufactured using the low-noise oriented silicon steels of Examples 1 to 6 and the comparative steel sheets of Comparative Examples 1 to 4.

[0062] [Table 6]

[0063] Combining Tables 4 and 5, it can be seen that the performance of each example of the present invention is superior to that of Comparative Examples 1 to 4. The difference in magnetostriction between the first and second surfaces of the low magnetostriction oriented silicon steel of each example is significantly smaller than that of the comparative steel sheets of Comparative Examples 1 to 4.

[0064] As shown in Table 4, the magnetostriction difference between the first surface and the second surface of the oriented silicon steel of Examples 1 to 6 is ≦2 db(A), and the average magnetostriction is ≦55 db(A). Furthermore, as shown in Table 5, the overall noise level of the 240 KVA three-phase transformer manufactured using the low-noise oriented silicon steel of Examples 1 to 6 is significantly lower than that of Comparative Examples 1 to 4.

[0065] 1 shows the magnetostriction curve of the etched surface of the grain-oriented silicon steel of the present invention as a function of the laser etching energy density, with the shaded areas corresponding to the performance of the grain-oriented silicon steel of Examples 2 to 4. It can be seen that with an increase in the laser etching energy density, the improvement rate of the magnetic performance (reduction in iron loss) first increases and then stabilizes, and the magnetostriction performance first decreases and then increases.

[0066] 2 shows the curves of the deflection difference between the first and second surfaces of the silicon steel substrate after single-sided laser etching in accordance with the present invention as a function of the laser etching energy density, with the shaded areas corresponding to the performance of the silicon steel substrates in Examples 2 to 4. It can be seen that with an increase in the laser etching energy density, the deflection difference between the first and second surfaces of the silicon steel substrate initially increases exponentially and then stabilizes.

[0067] Figure 3 shows the difference in the amount of insulating coating between the first and second surfaces required to maintain the straightness of the silicon steel substrate of the present invention under various conditions of deflection difference. The shaded areas correspond to the performance of the silicon steel substrates in Examples 2 to 4. It can be seen that in order to maintain the straightness of the finished oriented silicon steel and reduce the difference in magnetostriction between the two surfaces, it is necessary to adjust the difference in the amount of insulating coating between the first and second surfaces based on the deflection difference caused by laser etching.

[0068] In conclusion, the method for producing low-magnetostriction oriented silicon steel of the present invention can adjust the tension difference of the insulating coating between the etched and unetched surfaces of the silicon steel substrate according to the difference in deflection between the etched and unetched surfaces of the silicon steel substrate after one-sided laser etching, thereby reducing the difference in magnetostriction between the etched and unetched surfaces of the oriented silicon steel.

[0069] The low-magnetostriction oriented silicon steel produced using this manufacturing method can achieve a magnetostriction difference between the etched and unetched surfaces of the oriented silicon steel of ≦2 db(A) and an average magnetostriction of ≦55 db(A). Because the vibration generated by the iron core made from low-magnetostriction oriented silicon steel is small, the overall noise level of the transformer equipped with this iron core is consequently low.

[0070] Although the present invention has been illustrated and described with reference to certain preferred embodiments, those skilled in the art should understand that the above content has been combined with certain embodiments to further describe the present invention in detail, and that specific implementations of the present invention cannot be considered limited to these descriptions. Those skilled in the art may make various changes in form and details, including making certain simple inferences or substitutions, without departing from the spirit and scope of the present invention.

Claims

1. A method for producing a low magnetostriction oriented silicon steel sheet comprising a silicon steel substrate and an insulating coating on a surface of the silicon steel substrate, the method comprising: a step of performing one-side laser etching on the silicon steel substrate (the surface of the silicon steel substrate that has been subjected to one-side laser etching is designated as a first surface, and the surface opposite to the first surface is designated as a second surface); determining a difference in deflection between the first surface and the second surface in response to the power of the laser etching, and determining a difference in the amount of insulating coating between the first surface and the second surface based on the difference in deflection; and a step of forming an insulating coating on the first surface and the second surface (wherein the amount of insulating coating on the second surface is greater than the amount of insulating coating on the first surface, and the amount of insulating coating on the first surface and the amount of insulating coating on the second surface satisfy the difference in the amount of insulating coating); Including, The differential deflection is determined based on the following formula: [Equation 3] (Wherein, W is the laser etching power in mJ / mm ２ and the deflection difference is expressed in mm) The difference in insulating coating volume is determined based on the following formula: [Equation 4] (where the unit of the difference in the amount of insulating coating is g / m ２ is) a magnetostriction difference between the first surface and the second surface is 2 db (A) or less; The thickness of the silicon steel substrate is 0.18-0.23 mm; Manufacturing method.

2. 10. The method of claim 1, wherein the step of forming the insulating coating comprises applying an insulating coating solution to the first surface and the second surface, and firing and sintering the insulating coating solution to form the insulating coating on the first surface and the second surface.

3. Laser etching power is 0.5 to 2.5 mJ / mm ２ The method according to claim 1, wherein

4. Laser etching power is 1 to 2 mJ / mm ２ The method according to claim 3, wherein

5. The amount of insulating coating on the first surface is 4.0 to 4.5 g / m ２ The method according to claim 1, wherein

6. The method of claim 2, wherein the components of the insulating coating solution are as follows in mass percentage: at least one of aluminum dihydrogen phosphate and magnesium dihydrogen phosphate: 2% to 25%; Colloidal silicon dioxide: 4% to 16%; Chromic anhydride: 0.15% to 4.50%; and The balance is water and other inevitable impurities.

7. 2. The method of claim 1, wherein the silicon steel substrate is produced by the following steps in sequence: Step a: smelting and casting; Step b: heating; Step c: normalizing; Step d: cold rolling; Step e: decarburization annealing; Step f: final annealing; and Step g: Hot stretch annealing.

8. The method of claim 7, which satisfies at least one of the following manufacturing process conditions: In step c, the silicon steel substrate is subjected to a two-stage normalizing treatment (first, the silicon steel substrate is heated to 1100-1200°C, then cooled to 900-1000°C at a cooling rate of 1-10°C / s, and finally cooled to room temperature at a cooling rate of 10-70°C / s); in step d, either a first cold rolling or a second cold rolling including an intermediate annealing step is performed; In step e, primary recrystallization annealing is performed at 800 to 900°C, and then an annealing separator is applied to the surface of the silicon steel substrate; In step f, the annealing temperature is controlled to 1100 to 1200 ° C., and the holding time is set to 20 to 30 hours; and In step g, the silicon steel substrate is first heated to 800-900° C., held for 10-30 seconds, and then cooled to room temperature at a cooling rate of 5° C. / sec-50° C. / sec.

9. A low magnetostriction oriented silicon steel sheet, a laser etched first surface; a second surface opposite the first surface, an insulating coating is formed on the first surface and the second surface, and the amount of the insulating coating on the second surface is greater than that on the first surface; The thickness of the steel plate substrate is 0.18-0.23 mm; The low magnetostriction oriented silicon steel plate has a magnetostriction difference between the first surface and the second surface of 2 db (A) or less, The low magnetostriction-oriented silicon steel sheet has an average magnetostriction of 55 db (A) or less.

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