Method for manufacturing a low magnetic distortion oriented silicon steel sheet, and an oriented silicon steel sheet

Abstract

(a) Smelting and casting process; (b) Heating process; (c) Annealing process; (d) Cold rolling process; (e) Decarburizing annealing process; (f) Final annealing process; and (g) Hot stretching annealing process including applying an insulating coating. A method for manufacturing a low magnetostriction oriented silicon steel sheet is disclosed. The difference in coating amount between the insulating coatings is determined according to the difference in deflection between two surfaces of a silicon steel substrate subjected to single-sided laser scribing in step (g); then, on two surfaces of the silicon steel substrate manufactured in steps (a) to (f), an insulating coating is formed according to the difference in coating amount, and the difference in coating amount between the insulating coatings on the two surfaces satisfies the difference in coating amount.

Description

Technical Field

[0001] Technical Field The present invention relates to a steel sheet and a method for manufacturing the same, and particularly to a grain-oriented silicon steel sheet and a method for manufacturing the same.

Background Art

[0002] Background Currently, transformer cores are fabricated by laminating or winding grain-oriented silicon steel (GOSS). In transformer production and downstream users, the main performance indicators of transformers are focused on no-load loss characteristics and no-load exciting current characteristics, which correspond to the loss and exciting power characteristics of grain-oriented silicon steel.

[0003] The loss characteristics of grain-oriented silicon steel depend on hysteresis loss affected by the degree of crystallographic orientation and its purity of the finished product, classical eddy current loss affected by thickness and resistivity, and anomalous eddy current loss affected by the width of magnetic domains. Therefore, in the prior art, methods for reducing loss characteristics include increasing the degree of orientation of the finished GOSS to increase magnetic flux and thereby reduce hysteresis loss; increasing the Si content or decreasing the thickness of the steel to increase electrical resistivity and thereby reduce classical eddy current loss; and reducing the width of magnetic domains by etching and thereby reducing anomalous eddy current loss.

[0004] With the continuous improvement of production processes and technologies for grain-oriented silicon steel, the particle orientation degree of industrial grain-oriented silicon steel products is gradually approaching its limit. Further reduction in thickness significantly increases the production cost and technical difficulty. On the other hand, due to the coarse particles in high magnetic induction grain-oriented silicon steel products, introducing local residual stress on the surface of the steel sheet by laser etching reduces the 180° primary domain interval along the rolling direction and effectively reduces anomalous eddy current loss. This is currently a convenient and economical method for reducing iron loss in high magnetic induction grain-oriented silicon steel.

[0005] In recent years, as the demand for social noise reduction has increased, transformer manufacturers and downstream users have been paying increasing attention to the noise performance of transformers. The noise performance of transformers has become as important as no-load loss. Due to the continuous optimization of processing technology and transformer design, the magnetostriction of grain-oriented silicon steel has become the main cause of transformer noise.

[0006] During cross-excitation, the dimensional change of the finished grain-oriented silicon steel sheet caused by magnetization is known as magnetostriction and is the main cause of transformer noise. The mechanism of magnetostriction in grain-oriented silicon steel is the change and rotation of 90° magnetic domains in the easy magnetization direction perpendicular to the rolling direction during the magnetization process. Ideally, grain-oriented silicon steel has only 180° magnetic domains, but due to orientation deviation, inclusions, grain boundaries, and other defects, small auxiliary magnetic domains known as columnar closed magnetic domains (90° magnetic domains) are generated between the 180° magnetic domains to reduce the magnetostatic energy and increase the magnetostriction of the finished product. Therefore, reducing the 90° magnetic domains (closed magnetic domains) can effectively reduce magnetostriction.

[0007] In the prior art, the main methods used to reduce magnetostriction include the following: (1) improving the degree of orientation of the finished crystal; (2) reducing the thickness of the finished product; (3) increasing the tension of the coating. These methods can reduce the magnetostriction of the finished grain-oriented silicon steel sheet, thereby achieving a reduction in the noise level of the transformer.

[0008] The Chinese patent document with publication number CN107210109A, publication date September 27, 2017, and title "Directional Electromagnetic Steel Sheet, Its Manufacturing Method, and Method for Predicting Transformer Noise Characteristics" discloses a directional electromagnetic steel sheet, its manufacturing method, and a method for predicting transformer noise characteristics. This patent discloses a technical solution regarding the magnetostriction characteristics of the directional electromagnetic steel sheet, which is controlled such that the surface-back surface tension difference of the forsterite film exceeds 0.5 MPa, while the total surface-back surface tension difference of the forsterite and the insulating coating is less than 0.5 MPa. The acceleration point or deceleration point at the magnetostriction speed level: dλ / dt is set to 4 within one cycle of the magnetostriction vibration, and the speed level change of adjacent speed change points in the acceleration region or deceleration region of the magnetostriction vibration is set to 3.0×10 -4 seconds -1 or less, thereby achieving a reduction in magnetostriction characteristics. However, this method of adjusting the tension difference between the forsterite coatings and the total tension difference between the forsterite coating and the insulating coating provides only limited improvement in the double-sided magnetostriction difference in the one-sided laser-printed directional silicon steel sheet, and it is difficult to control, making it difficult to produce a large amount of directional electromagnetic steel sheets with excellent noise characteristics and a minimum magnetostriction deviation between the upper and lower surfaces stably and at a reasonable cost.

[0009] A Chinese patent document with publication number CN106460111A, publication date February 22, 2017, and title "Directional electromagnetic steel sheet with low iron loss and low magnetic distortion" discloses a directional electromagnetic steel sheet with low iron loss and low magnetic distortion. This directional electromagnetic steel sheet includes: a base steel sheet, a primary film formed on the surface of the base steel sheet, and a tension insulation coating formed on the surface of the primary film, where the coating satisfies the following conditions: the ratio between the thickness of the tension insulation coating and the thickness of the primary film is 0.1 or more and 3.0 or less, the thickness of the tension insulation coating is 0.5 μm or more and 4.5 μm or less, and the total tension applied to the base steel sheet from the primary film and the tension insulation coating is 1 MPa or more and 10 MPa or less. Magnetic domain control is achieved by irradiating the surface of the tension insulation coating with a laser. A strip sample having a length of 300 mm in a direction parallel to the rolling direction and a length of 60 mm in a direction parallel to the width direction is taken from the directional electromagnetic steel sheet, and one side or both sides of the sample are pickled. By pickling the sample, a range from the surface of the tension insulation coating to a depth position of 5 μm toward the base steel sheet side from the interface between the base steel sheet and the primary film is removed. Then, the amount of warp at the tip of each sample is measured. In this case, the amount of warp satisfies the specified conditions. However, this method only considers the thickness and tension of the primary coating and the tension insulation coating, and provides limited improvement in the magnetic distortion of the directional silicon steel substrate. This process is difficult to control and cannot produce a large amount of directional electromagnetic steel sheets with excellent noise characteristics and minimum magnetic distortion deviation between the upper and lower surfaces stably and at a reasonable cost.

[0010] The Chinese patent document with publication number CN106029917A, publication date October 12, 2016, and title "Directional electromagnetic steel sheet for low-noise transformer and method for manufacturing the same" discloses a directional electromagnetic steel sheet obtained by irradiating the surface of a steel sheet 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. Here, the modulated irradiation linear region is formed from repeating units connected to each other in the linear region direction, 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 repeating interval in the rolling direction of the modulated irradiation linear region is 4.0 mm to 12.5 mm. The intensity of the electron beam is equal to or higher than the intensity at which at least an elongated divided magnetic domain extending in the direction of the modulated irradiation line region is formed on the irradiated surface, and is equal to or lower than the intensity at which no coating damage occurs and no plastic strain region is formed on the irradiated surface. Therefore, it is possible to perform magnetic domain subdivision processing under conditions that achieve both low iron loss and low noise of the transformer. However, this method only considers the influence of etching conditions on magnetic strain, and does not consider the matching between etching conditions and coating conditions. Therefore, it is difficult to efficiently produce a large amount of directional electromagnetic steel sheets with excellent noise characteristics and a small magnetic strain deviation between the upper and lower surfaces in a stable and cost-effective manner.

Summary of the Invention

Means for Solving the Problems

[0011] Abstract One object of the present invention is to provide a manufacturing method for a low magnetic strain directional silicon steel sheet. This method addresses the problem in the existing technology that a thin directional silicon steel sheet processed by laser scribing for low loss suffers from a non-uniform stress distribution due to single-sided laser scribing. This causes excessive magnetic strain deviation between the etched surface of the steel sheet and the non-etched surface when the steel sheet is bent towards the etched surface.

[0012] To achieve the above object, the present invention provides a method for manufacturing a low magnetostriction oriented silicon steel sheet, including the following steps: (a) A step of smelting and casting; (b) A step of heating; (c) A step of annealing; (d) A step of cold rolling; (e) A step of decarburizing annealing; (f) A step of final annealing; (g) A step of hot stretch annealing including applying an insulating coating; where step (g) includes the following: (1) Applying an insulating coating component on two surfaces of the silicon steel substrate A with an equal coating amount V; (2) Sintering and cooling to form an insulating coating on each of the two surfaces of the silicon steel substrate A; (3) Performing single-sided laser etching on one surface of the silicon steel substrate A having the insulating coating, defining this single-sided laser-etched surface as the first surface, and defining the surface opposite to the first surface as the second surface; (4) Measuring the difference in deflection between the first surface and the second surface, and determining the difference in coating amount ΔV between the insulating coatings based on the deflection difference; and (5) Based on the coating amount difference ΔV, forming insulating coatings on two surfaces of the silicon steel substrate B produced by steps (a) to (f), where the coating amount of the insulating coating on the surface to be laser-etched is V, and the coating amount of the insulating coating on the surface not subjected to laser etching is V + |ΔV|.

[0013] In the technical scheme of the present invention, the process of the above step (g) is optimized by first applying the insulating coating component on two surfaces of the silicon steel substrate A with an equal coating amount, and then sintering and cooling to form insulating coatings on each surface of the silicon steel substrate A. The steps of sintering and cooling can be carried out according to the existing technology to ensure that insulating coatings of equal thickness are formed on both surfaces of the silicon steel substrate A.

[0014] In the technical scheme of the present invention, for a silicon steel substrate having insulating coatings of equal thickness on two surfaces, based on the iron loss P17 / 50 and the improvement rate of magnetic strain before and after laser etching, the output of laser etching can be optimized. By detecting the difference in deflection (i.e., the distance from the center of the end face of the bent steel plate to the axis of the steel plate when not bent) between the first surface laser-etched and the second surface not laser-etched on a silicon steel substrate having equal coating amounts on two surfaces, the difference in coating amount ΔV between the insulating coatings can be determined based on this difference in deflection. According to the difference in coating amount ΔV, the insulating coatings are formed on two surfaces of the silicon steel substrate B produced by steps (a) to (f), where the coating amount of the insulating coating on the etched surface is V, and the coating amount of the insulating coating on the unetched surface is V + |ΔV|. The compositions and manufacturing processes for the above-mentioned silicon steel substrates A and B are the same.

[0015] A silicon steel substrate satisfying the difference in coating amount ΔV for the insulating coating can maintain flatness and exhibit good magnetic strain performance after laser etching. By adjusting the difference in coating amount between the etched surface and the unetched surface, the difference in coating tension can be adjusted, which can effectively reduce the difference in deflection between the etched surface and the unetched surface of the finished grain-oriented silicon steel product caused by the non-uniform stress distribution due to single-sided laser etching, thereby reducing the magnetic strain deviation between the etched surface and the unetched surface.

[0016] Single-sided laser etching of a silicon steel substrate with an insulating coating is a common method for subdividing the magnetic domains of grain-oriented silicon steel and reducing the losses in the prior art. Therefore, the prospect of practical application of the manufacturing method designed by the present invention is broad.

[0017] Preferably, in the above step (4), the difference in coating amount between the insulating coating on the first surface and the insulating coating on the second surface = 3 × 10 -5 - 0.407 × difference in deflection ± 0.1; more preferably, the difference in coating amount between the insulating coatings = 3 × 10 -5 - 0.407 × difference in deflection, where the unit of the difference in coating amount between the insulating coatings is g / m 2 and the unit of the difference in deflection is mm.

[0018] Preferably, in the manufacturing method of the present invention, in step (3), the laser output X of the single-sided laser etching is determined based on the following formula: Set magnetostriction target value = -0.0006 × X 5 + 0.012 × X 4 - 0.04 × X 3 - 0.18 × X 2 + 0.37 × X + 54.8; and / or, Set improvement rate of iron loss P17 / 50 before and after laser etching = -0.177 × X 2 + 3.2 × X - 2.4; where the unit of the magnetostriction target value is db(A), and the unit of the laser output is mJ / mm 2 is.

[0019] Preferably, in the manufacturing method of the present invention, the composition of the insulating coating component includes the following: At least one selected from aluminum dihydrogen phosphate and magnesium dihydrogen phosphate: 2% - 25%; Colloidal SiO2: 4% - 16%; Chromic anhydride: 0.15% - 4.50%; and The balance is water and unavoidable impurities.

[0020] In the above manufacturing method of the present invention, the insulating coating can be used to improve the insulating properties on the surface of the silicon steel substrate. The composition used to form the insulating coating of the present invention can use an insulating coating solution widely used in the prior art, which is mainly an aqueous solution composed of anhydrous chromic acid, colloidal SiO2, and phosphates of magnesium and aluminum. This insulating coating solution forms a transparent insulating coating on the surface of the silicon steel substrate after sintering, enabling the laser to directly reach the surface of the silicon steel substrate during the subsequent laser etching process.

[0021] Preferably, in the manufacturing method of the present invention, in step (1), the coating amount of the insulating coating component on both surfaces of the silicon steel substrate is between 4.0 and 4.5 g / m 2 2.

[0022] In the present invention, it is preferable to control the coating amount of the insulating coating component on both surfaces of the silicon steel substrate within 4.0 - 4.5 g / m 2 2. When the coating amount is less than 4.0 g / m 2 2, the insulating coating is too thin, the tension exerted by the insulating coating on the silicon steel substrate is insufficient, and the magnetic optimization is insufficient. On the contrary, when the coating amount is more than 4.5 g / m 2 2, the insulating coating is too thick, which not only affects the stacking factor of the finished product but also easily causes defects such as powder falling and white edges during the shearing process.

[0023] Preferably, in the manufacturing method of the present invention, in step (b): First, heat the silicon steel substrate to 800 - 900 °C and hold it for 10 - 30 seconds, and then cool it to room temperature at a cooling rate of 5 - 50 °C / s.

[0024] Preferably, in the manufacturing method of the present invention, in step (c), a two-stage annealing treatment is employed: First, the steel sheet is heated to 1100 - 1200 °C, and then it is cooled to 900 - 1000 °C at a cooling rate of 1 - 10 °C / s; subsequently, it is cooled to room temperature at a cooling rate of 10 - 70 °C / s.

[0025] Preferably, in the manufacturing method of the present invention, in step (d), cold rolling is carried out together with an intermediate annealing step using single-pass cold rolling or double cold rolling.

[0026] Preferably, in the manufacturing method of the present invention, in step (e), the first recrystallization annealing is carried out at 800 - 900 °C, and subsequently, an annealing separator is applied. Before the final annealing in step (f), an annealing separator such as magnesium oxide is applied to the surface of the silicon steel substrate to prevent the steel sheets from bonding during the subsequent high-temperature annealing environment.

[0027] Preferably, in the manufacturing method of the present invention, in step (f), the annealing temperature is 1100 - 1200 °C with a holding time of 20 - 30 hours.

[0028] Another object of the present invention is to provide a low magnetostriction oriented silicon steel sheet, where the magnetostriction deviation between the etched surface and the unetched surface after single-sided laser etching is minimized, and it has a good average magnetostriction. The core made from this low magnetostriction oriented silicon steel sheet generates low vibrations, resulting in a low overall noise level for the transformer using this core.

[0029] To achieve the above object, the present invention proposes a low magnetostriction oriented silicon steel sheet manufactured by the above manufacturing method.

[0030] Preferably, the thickness of the finished oriented silicon steel sheet product prepared according to the present invention is 0.18 mm - 0.23 mm.

[0031] In the present invention, it is generally preferable to control the thickness of the completed low-magnetostriction oriented silicon steel sheet product within 0.18 mm to 0.23 mm. When the finished product thickness of the steel sheet is greater than 0.23 mm, the increased thickness and rigidity reduce the sensitivity to non-uniform stress distribution by laser scribing even after forming an insulating coating on the surface.

[0032] Preferably, in the oriented silicon steel sheet of the present invention, the magnetostriction deviation between the etched surface and the non-etched surface of the low-magnetostriction oriented silicon steel sheet is ≦ 2 dB(A), and the average magnetostriction of the low-magnetostriction oriented silicon steel sheet is ≦ 55 dB(A).

[0033] Compared with the prior art, the manufacturing method and the oriented silicon steel sheet for the low-magnetostriction oriented silicon steel sheet according to the present invention have the following advantages and beneficial effects:

[0034] The manufacturing method for the low-magnetostriction oriented silicon steel sheet according to the present invention can solve the problem of excessive magnetostriction deviation between the etched surface and the non-etched surface of the oriented silicon steel due to the non-uniform stress distribution introduced by single-sided laser etching, and the steel sheet bends towards the etched surface due to this excessive magnetostriction deviation.

[0035] By using the manufacturing method of the present invention, a silicon steel substrate having an insulating coating with an equal coating amount on both surfaces can be etched. The difference in tension between the insulating coatings on the etched surface (the first surface) and the non-etched surface (the second surface) can be determined based on the difference in deflection between these two surfaces, enabling adjustment of the coating amount difference and reducing the magnetostriction deviation between the insulating coatings on the etched surface and the non-etched surface of the oriented silicon steel.

[0036] In the present invention, the prepared low magnetostriction oriented silicon steel sheet can achieve a magnetostriction deviation of ≤2 dB(A) and an average magnetostriction deviation of ≤55 dB(A) between the etched surface and the unetched surface. The core made from this low magnetostriction oriented silicon steel sheet generates low vibrations, leading to a low overall noise level for the transformer using this core and showing excellent practical applications.

Brief Description of the Drawings

[0037]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0038] Detailed Description The following provides a further description and examples of the method for manufacturing a low magnetostriction oriented silicon steel sheet and the low magnetostriction oriented silicon steel sheet described in the present invention with specific embodiments and drawings. However, this description does not unduly limit the technical scope of the present invention.

[0039] Examples 1 to 6 and Comparative Examples 1 to 4 The low magnetostriction oriented silicon steel sheets of Examples 1 to 6 and the comparative oriented silicon steel sheets of Comparative Examples 1 to 4 were manufactured using the following steps: (a) Smelt according to the chemical composition shown in Table 1 and cast into slabs. (b) Heating: Heat the slab to 1200 - 1280 °C, hold for 1 - 4 hours, and hot roll it into a steel strip. (c) Annealing: Adopt a two-stage annealing process. First, heat the steel strip to 1100 - 1200 °C, then cool it to 900 - 1000 °C at a rate of 1 °C / s - 10 °C / s; subsequently, cool it to room temperature at a cooling rate of 10 °C / s - 70 °C / s. (d) Cold rolling: Perform single-pass cold rolling or double cold rolling together with an intermediate annealing process. (e) Decarburizing annealing: Conduct the first recrystallization annealing at a temperature of 800 - 900 °C, and then apply an annealing release agent. (f) Final annealing: Anneal at a temperature of 1100 - 1200 °C and hold for 20 - 30 hours. (g) Apply an insulating coating to the annealed silicon steel substrate A, and then perform hot stretching annealing to prepare a grain-oriented silicon steel sheet with a thickness of 0.18 mm - 0.23 mm:

[0040] In step (g), first, apply an equal amount of insulating coating components to both surfaces of the silicon steel substrate A. Then, heat the steel sheet to 800 - 900 °C, hold it for 10 - 30 seconds, and then sinter and cool it by cooling it to room temperature at a rate of 5 °C / s - 50 °C / s to obtain a silicon steel substrate with an insulating coating.

[0041] Apply single-sided laser etching to one surface of a silicon steel substrate coated with an insulating coating, define the surface subjected to single-sided laser etching as the first surface, and define the surface opposite the first surface as the second surface. Measure the difference in deflection between the first surface and the second surface, and determine the difference ΔV in coating amount between the insulating coatings on the etched surface and the unetched surface of the silicon steel substrate based on this deflection difference. Then, form an insulating coating on the surface of the silicon steel substrate B manufactured by steps (a) to (f) according to the difference in coating amount, where the unetched surface has a larger coating amount than the etched surface and satisfies the required difference ΔV in coating amount.

[0042] In the present invention, it should be noted that in the above step (g), the laser output X for single-sided laser etching can be determined by either the set magnetostriction target value or the set improvement rate of the iron loss P17 / 50 before and after laser etching. Set magnetostriction target value = -0.0006 × X 5 + 0.012 × X 4 - 0.04 × X 3 - 0.18 × X 2 + 0.37 × X + 54.8. Set improvement rate of iron loss P17 / 50 before and after laser etching = -0.177 × X 2 + 3.2 × X - 2.4. In these formulas, the unit of the magnetostriction target value is db(A), and the unit of the laser output is mJ / mm 2 is.

[0043] Accordingly, the difference in coating amount between the insulating coatings on the etched surface and the unetched surface of the silicon steel substrate is determined based on the following formula: Difference in coating amount between insulating coatings = 3 × 10 -5 - 0.407 × deflection difference ± 0.1, preferably, difference in coating amount = 3 × 10 -5 - 0.407 × deflection difference, where the unit of the difference in coating amount between the insulating coatings is g / m 2and the unit of the difference in deflection is mm.

[0044] In the present invention, the operations and specific manufacturing parameters of the low-magnetic-strain oriented silicon steel sheets in Examples 1 to 6 according to the present invention satisfy the technical requirements of the present invention. On the other hand, it should be noted that for the comparative oriented silicon steel sheets in Comparative Examples 1 to 4, the difference in coating amount between the corresponding insulating coatings is not controlled based on the difference in deflection between the etched surface and the non-etched surface caused by laser etching.

[0045] Table 1 lists the mass percentages of each chemical element in the low-magnetic-strain oriented silicon steel sheets in Examples 1 to 6 and in the comparative oriented silicon steel sheets in Comparative Examples 1 to 4.

[0046]

Table 1

[0047] In the present invention, in order to obtain a low-magnetic-strain oriented silicon steel having target performance, an operator needs to apply laser etching on one surface of a silicon steel substrate A having an insulating coating with the same coating amount on both surfaces. Next, the difference in deflection between the first surface and the second surface caused by laser etching is measured, and based on this difference in deflection, the difference in coating amount between the insulating coatings on the etched surface and the non-etched surface of the silicon substrate is determined. Then, based on the difference in coating amount, the coating amounts of the etched surface and the non-etched surface of the silicon steel substrate B prepared by steps (a) to (f) are adjusted, so that the difference in coating amount between the etched surface and the non-etched surface of the silicon steel substrate B satisfies the calculated difference in coating amount, and thus a low-magnetic-strain oriented silicon steel is obtained.

[0048] In this embodiment, it should be noted that the insulation coating components applied to the low magnetostriction oriented silicon steel sheets in Examples 1 to 6 and the comparative oriented silicon steel sheets in Comparative Examples 1 to 4 include the following in mass percentage: at least one selected from aluminum dihydrogen phosphate and magnesium dihydrogen phosphate: 2% to 25%; colloidal SiO2: 4% to 16%; chromic anhydride: 0.15% to 4.50%; the balance is water and unavoidable impurities.

[0049] Table 2 lists the specific chemical compositions of the insulation coating components applied on the surfaces of the low magnetostriction oriented silicon steel sheets in Examples 1 to 6 and the comparative oriented silicon steel sheets in Comparative Examples 1 to 4.

[0050] [Table 2]

[0051] Table 3-1 lists the specific process parameters used to manufacture the low magnetostriction oriented silicon steel sheets in Examples 1 to 6 and the comparative oriented silicon steel sheets in Comparative Examples 1 to 4.

[0052] [Table 3-1]

[0053] Table 3-2 lists the output of single-sided laser etching for the silicon steel substrates A in Examples 1 to 6 and the comparative steel sheets in Comparative Examples 1 to 4, the difference in deflection between the two surfaces of the silicon steel substrate, the difference in coating amount between the insulation coatings on the etched surface and the unetched surface, and the coating amounts of the insulation coatings on the etched surface and the unetched surface of the finished oriented silicon steel B.

[0054] [Table 3-2]

[0055] From Tables 3-1 and 3-2, it can be observed that an equal amount of the insulating coating component was applied to the first surface and the second surface of the silicon steel substrate A. After subjecting the first surface to single-sided laser etching, the difference in deflection between the first surface and the second surface was measured. Based on the difference in deflection, the difference in the coating amount between the insulating coatings on the etched surface and the unetched surface of the silicon steel substrate was determined. According to the difference in the coating amount, the coating amount between the etched surface and the unetched surface of the silicon steel substrate B prepared by steps (a) to (f) was then adjusted to ensure that the unetched surface of the silicon steel substrate B had a greater insulating coating amount than the etched surface, and that the difference in the coating amount between the etched surface and the unetched surface of the silicon steel substrate B satisfied the calculated difference in the coating amount.

[0056] The deflections on the first surface and the second surface of the silicon steel substrates in Examples 1 to 6 and Comparative Examples 1 to 4 were tested according to YB / T 4292-2012 to obtain the difference in deflection.

[0057] Samples from the low magnetostriction oriented silicon steel sheets of Examples 1 to 6 and the comparative oriented silicon steel sheets of Comparative Examples 1 to 4 were measured for magnetostriction performance (magnetostriction velocity sound pressure level LvA) using a non-contact laser Doppler vibrometer TD9600 under the conditions of B = 1.7 T and f = -2 MPa (under the actual operating conditions of a transformer, subjecting the oriented silicon steel to a compressive stress of 2 to 3 MPa). For the specific measurement method, refer to IEC (International Electrotechnical Commission) Technical Report - IEC / TP 62581. The iron loss P17 / 50 represents the iron loss of a 1 kg sample at a magnetic flux density of 1.7 T and a frequency of 50 Hz, measured according to the national standard GB / T 3655-2008 "Method for Measuring Magnetic Properties of Electrical Steel Sheets and Strips by Epstein Frame". The test results of the magnetostriction performance of each example and comparative example are listed in Table 4.

[0058] Table 4 lists the performance test results of the low magnetostriction oriented silicon steel sheets of Examples 1 to 6 and the comparative oriented silicon steel sheets of Comparative Examples 1 to 4.

[0059]

Table 4

[0060] Accordingly, 240KVA three-phase transformers were further prepared using the low magnetostriction oriented silicon steel sheets of Examples 1 to 6 and the comparative oriented silicon steel sheets of Comparative Examples 1 to 4, respectively. A noise test was conducted on each of the three-phase transformers prepared in the examples and comparative examples under magnetization conditions of 50 Hz and 1.7 T (GB / T 1094. 10-2003), and the test results are listed in Table 5.

[0061] Table 5 lists the noise test results of 240KVA three-phase transformers prepared using the low magnetostriction oriented silicon steel sheets of Examples 1 to 6 and the comparative oriented silicon steel sheets of Comparative Examples 1 to 4.

[0062]

Table 5

[0063] As can be seen from Tables 4 and 5, the performance of each example of the present invention is excellent compared with Comparative Examples 1 to 4. The magnetostriction deviation between the etched surface and the non-etched surface of the low magnetostriction oriented silicon steel in each example is significantly smaller than the magnetostriction deviation of the comparative oriented silicon steel sheets in Comparative Examples 1 to 4.

[0064] Specifically, as shown in Table 4, the magnetostriction deviation between the etched surface and the non-etched surface of the low magnetostriction oriented silicon steel in Examples 1 to 6 is ≦2 db(A), and the average magnetostriction is ≦55 db(A). Accordingly, as shown in Table 5, the overall noise level of the 240KVA three-phase transformers made of the low magnetostriction oriented silicon steel sheets of Examples 1 to 6 is significantly lower than the overall noise level of the 240KVA three-phase transformers made in Comparative Examples 1 to 4.

[0065] Figure 1 schematically shows the curves of the magnetostriction and magnetic improvement rate of the etched surface of the low-magnetostriction oriented silicon steel sheet according to the present invention by changing the energy density of laser etching.

[0066] As shown in Figure 1, when the energy density of laser etching increases, the improvement rate of the magnetic properties of the low-magnetostriction oriented silicon steel sheet first increases and then tends to become stable. On the other hand, the magnetostriction performance first decreases and then increases.

[0067] Figure 2 schematically shows the curve of the difference in deflection between the etched surface and the unetched surface by changing the energy density of laser etching after single-sided laser etching of the silicon steel substrate of the present invention having an equal coating amount on two surfaces.

[0068] As shown in Figure 2, after single-sided laser etching of the silicon steel substrate having an equal amount of coating on both surfaces, when the energy density of laser etching increases, the difference in deflection between the etched surface and the unetched surface of the silicon steel substrate first increases and then tends to become stable.

[0069] Figure 3 schematically shows the difference in the coating amount of the insulating coating between the etched surface and the unetched surface required to maintain the flatness of the low-magnetostriction oriented silicon steel according to the present invention under different deflection conditions.

[0070] As shown in Figure 3, in order to maintain the flatness of the oriented silicon steel product and reduce the magnetostriction deviation between the two surfaces, the difference in the coating amount between the etched surface and the unetched surface needs to be adjusted according to the difference in deflection caused by laser etching.

[0071] In summary, according to the difference in deflection between the etched surface and the unetched surface of a silicon steel substrate having a coating amount that matches on two surfaces, the manufacturing method for low magnetostriction oriented silicon steel in the present invention enables adjustment of the difference in coating amount of the insulating coating between the etched surface and the unetched surface of a silicon steel substrate prepared by the same process, thereby reducing the magnetostriction deviation between the etched surface and the unetched surface of the oriented silicon steel obtained by laser etching with the same energy density.

[0072] The low magnetostriction oriented silicon steel prepared by the above manufacturing method can ensure that the magnetostriction deviation between the etched surface and the unetched surface of the oriented silicon steel is ≦ 2 dB(A), and the average magnetostriction is ≦ 55 dB(A). A transformer having a core made of this low magnetostriction oriented silicon steel exhibits low vibration, and thus reduces the overall noise level of the transformers equipped with these cores.

[0073] It should be noted that the prior art part within the protection scope of the present invention is not limited to the embodiments presented in the application documents. All prior arts that do not conflict with the solution of the present invention, including but not limited to prior patents, publications, and known applications, are included in the protection scope of the present invention.

[0074] Furthermore, the combination of the technical features of the present invention is not limited to the combinations listed in the claims or specific embodiments. All technical features of the present invention can be freely combined as long as they do not conflict with each other.

[0075] Also, it should be noted that the above embodiments are merely specific examples of the present invention. It is obvious that the present invention is not limited to the above embodiments. All similar deformations and modifications directly derived or conceived by those skilled in the art from the disclosure content of the present invention are included in the protection scope of the present invention.

Claims

1. A manufacturing method for a grain-oriented silicon steel sheet, comprising the following steps: (a) a smelting and casting step; (b) a heating step; (c) a normalizing step; (d) a cold rolling step; (e) a decarburizing annealing step; (f) a final annealing step; (g) a hot stretching annealing step including applying an insulating coating; where step (g) includes the following: (1) Applying an insulating coating component onto two surfaces of a silicon steel substrate A with an equal coating amount V; (2) Sintering and cooling to form an insulating coating on each of the two surfaces of the silicon steel substrate A; (3) Performing single-sided laser etching on one surface of the silicon steel substrate A having the insulating coating, defining this single-sided laser-etched surface as the first surface, and defining the surface opposite to the first surface as the second surface; (4) Measuring the difference in deflection between the first surface and the second surface, and determining the difference in coating amount ΔV between the insulating coatings based on this deflection difference; and (5) Forming insulating coatings on two surfaces of a silicon steel substrate B obtained by steps (a) to (f) according to the coating amount difference ΔV, where the coating amount of the insulating coating on the surface to be laser-etched is V, and the coating amount of the insulating coating on the surface not subjected to laser etching is V + |ΔV|.

2. The manufacturing method according to claim 1, wherein in step (4), the coating amount difference ΔV is determined based on the following formula: Coating amount difference ΔV = 3 × 10 -5 - 0.407 × deflection difference ± 0.1; preferably, coating amount difference ΔV = 3 × 10 -5 - 0.407 × deflection difference; the unit of the coating amount difference is g / m 2 and the unit of the deflection difference is mm

3. The manufacturing method according to claim 1, wherein in step (3), the laser output X of the single-sided laser etching is determined based on the following formula: Set the magnetostriction target value = -0.0006 × X 5 + 0.012 × X 4 - 0.04 × X 3 - 0.18 × X 2 + 0.37 × X + 54.8; and / or, Setting improvement rate of iron loss P17 / 50 before and after laser etching = -0.177 × X 2 + 3.2 × X - 2.4; Here, the unit of the magnetostriction target value is dB(A), and the unit of the laser output is mJ / mm 2 is as follows.

4. The manufacturing method according to claim 1, wherein the insulating coating component contains the following by mass percentage: At least one selected from aluminum dihydrogen phosphate and magnesium dihydrogen phosphate: 2% - 25%; Colloidal SiO 2 : 4% to 16%; Chromic anhydride: 0.15% - 4.50%; and The balance is water and unavoidable impurities.

5. In step (1), the coating amount V is 4.0 to 4.5 g / m 2 The manufacturing method according to claim 1, wherein the coating amount is as described above.

6. In step (b): First, heating the silicon steel substrate to 800 - 900 °C, holding it for 10 - 30 seconds, and then cooling it to room temperature at a cooling rate of 5 - 50 °C / s. The manufacturing method according to claim 1.

7. The manufacturing method according to claim 1, satisfying one or more of the following processes: In step (c), a two-stage normalizing process is adopted: First, the steel sheet is heated to 1100 - 1200 °C, then cooled to 900 - 1000 °C at a cooling rate of 1 - 10 °C / s, and subsequently cooled to room temperature at a cooling rate of 10 - 70 °C / s; In step (d), cold rolling is carried out together with an intermediate annealing process by adopting single-pass cold rolling or double-pass cold rolling; In step (e), the steel sheet is subjected to the first recrystallization annealing at 800 - 900 °C, and subsequently an annealing release agent is applied; In step (f), the annealing temperature is 1100 - 1200 °C with a holding time of 20 - 30 hours.

8. A grain-oriented silicon steel sheet manufactured using the manufacturing method according to any one of Claims 1 to 8.

9. The grain-oriented silicon steel sheet according to Claim 8, wherein the thickness of the grain-oriented silicon steel sheet is 0.18 mm - 0.23 mm.

10. The grain-oriented silicon steel sheet according to Claim 8, wherein the magnetostriction deviation between the etched surface and the non-etched surface of the grain-oriented silicon steel sheet is ≦ 2 dB(A), and the average magnetostriction of the grain-oriented silicon steel sheet is ≦ 55 dB(A).

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