WO2025070780A1 - 方向性電磁鋼板、及び方向性電磁鋼板の製造方法 - Google Patents

方向性電磁鋼板、及び方向性電磁鋼板の製造方法 Download PDF

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WO2025070780A1
WO2025070780A1 PCT/JP2024/034799 JP2024034799W WO2025070780A1 WO 2025070780 A1 WO2025070780 A1 WO 2025070780A1 JP 2024034799 W JP2024034799 W JP 2024034799W WO 2025070780 A1 WO2025070780 A1 WO 2025070780A1
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Prior art keywords
magnetic domain
grain
steel sheet
domain control
electrical steel
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English (en)
French (fr)
Japanese (ja)
Inventor
稜 松原
悠祐 川村
励 本間
俊之 鈴間
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Nippon Steel Corp
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Nippon Steel Corp
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Priority to JP2025549212A priority Critical patent/JPWO2025070780A1/ja
Priority to CN202480059446.3A priority patent/CN121866354A/zh
Publication of WO2025070780A1 publication Critical patent/WO2025070780A1/ja
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
    • C21D8/12—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
    • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
    • H01F1/147—Alloys characterised by their composition
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/24—Magnetic cores
    • H01F27/245—Magnetic cores made from sheets, e.g. grain-oriented
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur

Definitions

  • the present disclosure relates to a grain-oriented electrical steel sheet and a method for manufacturing a grain-oriented electrical steel sheet.
  • Grain-oriented electrical steel sheet is a steel sheet that contains 7 mass% or less of Si and has a secondary recrystallized texture in which secondary recrystallized grains are concentrated in the ⁇ 110 ⁇ 001> orientation (Goss orientation) with the magnetization easy axis ⁇ 001> oriented in the rolling direction.
  • Grain-oriented electrical steel sheet is mainly used as the iron core of power transformers. Reduction of energy loss (iron loss) is required for grain-oriented electrical steel sheet.
  • the magnetic domain width can be narrowed by irradiating the surface of the grain-oriented electromagnetic steel sheet with a laser or electron beam in a direction intersecting the rolling direction to introduce thermal distortion.
  • the magnetic domain width can also be narrowed by forming grooves on the surface of the grain-oriented electromagnetic steel sheet in a direction intersecting the rolling direction. Methods for forming grooves include a method using a laser or electron beam, a method using mechanical processing such as gears, and a method using chemical processing such as etching.
  • Patent Documents 1 to 3 various improved techniques for magnetic domain refinement have been proposed to provide grain-oriented electrical steel sheets with good iron loss characteristics.
  • the magnetostriction characteristics of the grain-oriented electromagnetic steel sheet change due to the return magnetic domain. This deteriorates the noise characteristics of the grain-oriented electromagnetic steel sheet.
  • the noise characteristics refer to the level of noise generated by an electrical product (e.g., a transformer, a motor, etc.) manufactured using the grain-oriented electromagnetic steel sheet as a material.
  • Magnetostriction is a phenomenon in which the outer shape of a ferromagnetic material is slightly deformed when it is magnetized. When the grain-oriented electromagnetic steel sheet is excited with an alternating current, the magnitude of the magnetostriction changes with the change in the strength of the magnetization, causing vibration.
  • this magnetostriction is very small, on the order of 10 ⁇ 6 , but the magnetostriction generates vibration in the iron core, which propagates to external structures such as the tank of a transformer and becomes noise. That is, while the magnetic domain control treatment is effective for reducing the iron loss of the grain-oriented electromagnetic steel sheet, it deteriorates the noise characteristics of the grain-oriented electromagnetic steel sheet.
  • the purpose of this disclosure is to provide a grain-oriented electrical steel sheet that can achieve both low iron loss and low noise, and a manufacturing method thereof.
  • the gist of this disclosure is as follows:
  • a grain-oriented electrical steel sheet has a plurality of magnetic domain control processing lines on its surface, and the grain-oriented electrical steel sheet has a square evaluation area with one side 50 mm long and parallel to the rolling direction of the grain-oriented electrical steel sheet, and further has virtual lines 50 mm long and parallel to the rolling direction set at 5 mm intervals inside the evaluation area.
  • the standard deviation of the spacing between magnetic domain control points which are the intersections of the virtual line and the magnetic domain control processing lines, is 1.25 mm or more, and the average magnetic domain width measured along the virtual lines is 600 ⁇ m or less.
  • a grain-oriented electrical steel sheet according to another aspect of the present disclosure is a grain-oriented electrical steel sheet having a plurality of magnetic domain control processing lines on a surface thereof, wherein a square evaluation area is set in the grain-oriented electrical steel sheet, one side of which is 50 mm long and parallel to the rolling direction of the grain-oriented electrical steel sheet, and further, virtual lines 50 mm long and parallel to the rolling direction are set within the evaluation area at intervals of 5 mm, in which the standard deviation of the spacing between magnetic domain control points, which are the intersections of the virtual line and the magnetic domain control processing lines, for at least one of the virtual lines is 1.25 mm or more, and the maximum value of the magnetic domain width measured along the virtual line is 1,200 ⁇ m or less.
  • the maximum value of the magnetic domain width is 800 ⁇ m or less.
  • the standard deviation of the spacing between the magnetic domain control points is 1.25 mm or more, and the average value of the magnetic domain width is 600 ⁇ m or less.
  • the average value of the magnetic domain width is 500 ⁇ m or less in each of the two or more virtual lines in which the standard deviation of the spacing between the magnetic domain control points is 1.25 mm or more.
  • the standard deviation of the spacing between the magnetic domain control points is 2.50 mm or more, and the average value of the magnetic domain widths measured along the imaginary line is 600 ⁇ m or less.
  • the average value of the magnetic domain width is 500 ⁇ m or less on the imaginary line where the standard deviation of the spacing between the magnetic domain control points is 2.50 mm or more.
  • the grain-oriented electrical steel sheet according to any one of (1) to (2) and (5) to (8) above among the virtual lines in which the standard deviation of the spacing between the magnetic domain control points is 1.25 mm or more, at least one of the virtual lines has a number of grain boundary points, which are intersections between the virtual line and a crystal boundary, of two or less.
  • the number of grain boundary points on each of the two or more imaginary lines is two or less.
  • the standard deviation of the spacing between the magnetic domain control points is 1.25 mm or more, and the maximum value of the magnetic domain width is 1,200 ⁇ m or less.
  • the maximum value of the magnetic domain width is 800 ⁇ m or less.
  • the standard deviation of the spacing between the magnetic domain control points is 2.50 mm or more, and the maximum value of the magnetic domain width measured along the imaginary line is 1200 ⁇ m or less.
  • the maximum value of the magnetic domain width is 800 ⁇ m or less.
  • the magnetic domain control treatment lines are thermal distortions.
  • the magnetic domain control treatment lines are grooves.
  • the standard deviation of the spacing is preferably less than 1.25 mm for at least one of the imaginary lines.
  • a manufacturing method of grain-oriented electrical steel sheet includes the steps of acquiring a magnetic domain image of an original sheet of the grain-oriented electrical steel sheet, determining a magnetic domain control treatment area based on a distribution of magnetic domain widths in the magnetic domain image, and applying a magnetic domain control treatment to the magnetic domain control treatment area determined based on the distribution of magnetic domain widths, wherein a square evaluation area with one side length of 50 mm and one side parallel to the rolling direction of the grain-oriented electrical steel sheet is set in the grain-oriented electrical steel sheet, and virtual lines with lengths of 50 mm that are parallel to the rolling direction are set inside the evaluation area at intervals of 5 mm, and in at least one of the virtual lines, the standard deviation of the spacing between magnetic domain control points, which are intersections of the virtual line and the magnetic domain control treatment line formed by the magnetic domain control treatment, is 1.25 mm or more.
  • a region in which the magnetic domain width is equal to or greater than a predetermined value is defined as the magnetic domain control treatment region.
  • the distribution of the magnetic domain width is derived from the magnetic domain image using a two-dimensional Fourier transform.
  • the magnetic domain control treatment is applied by irradiation with a laser or an electron beam.
  • the above aspects of the present disclosure provide a grain-oriented electrical steel sheet that can achieve both low iron loss and low noise, and a method for manufacturing the same.
  • FIG. 1 is a plan view of a grain-oriented electrical steel sheet according to an embodiment of the present disclosure.
  • FIG. 1 is a plan view of a typical grain-oriented electrical steel sheet.
  • FIG. 2 is a diagram showing an example of the distribution of magnetic domain widths in a grain-oriented electrical steel sheet before magnetic domain refinement treatment.
  • FIG. 2 is a diagram showing an example of the distribution of magnetic domain widths of a grain-oriented electrical steel sheet after magnetic domain refinement treatment.
  • FIG. 3C is a diagram showing the difference between FIG. 3A and FIG. 3B.
  • 1 is a graph showing the relationship between the magnetic domain width before and after a magnetic domain control process.
  • FIG. 2 is a block diagram showing an example of a hardware configuration of the image acquisition device.
  • FIG. 1 is a plan view of a typical grain-oriented electrical steel sheet.
  • FIG. 2 is a diagram showing an example of the distribution of magnetic domain widths in a grain-oriented electrical steel sheet before magnetic domain refinement treatment.
  • FIG. 2
  • FIG. 2 is a block diagram showing an example of a hardware configuration of an analysis device.
  • FIG. 2 is a schematic diagram showing an example of the configuration of a laser irradiation device.
  • 1 is a flowchart showing a method for manufacturing a grain-oriented electrical steel sheet according to an embodiment of the present disclosure.
  • FIG. 13 is a schematic diagram illustrating a method for extracting a plurality of partial regions from a magnetic domain image of a grain-oriented electrical steel sheet. 13 is an example of a plurality of partial Fourier images obtained by performing a two-dimensional Fourier transform on each of a plurality of partial regions cut out from a magnetic domain image of a grain-oriented electrical steel sheet.
  • FIG. 2 is a plan view of an original sheet of a grain-oriented electrical steel sheet.
  • FIG. 1 is a schematic diagram for explaining a method for measuring the average or maximum value of the magnetic domain width along a virtual line.
  • the grain-oriented electrical steel sheet 1 in this embodiment has a plurality of magnetic domain control processing lines 11 on its surface, and a square evaluation area is set in the grain-oriented electrical steel sheet 1, with one side being 50 mm long and parallel to the rolling direction RD of the grain-oriented electrical steel sheet 1, and first virtual lines VL1, each 50 mm long and parallel to the rolling direction RD, are set at intervals of 5 mm inside the evaluation area.
  • first virtual lines VL1 the standard deviation of the spacing between magnetic domain control points VP, which are the intersections of the first virtual line VL1 and the magnetic domain control processing lines 11, is 1.25 mm or more, and at least one of the following conditions is satisfied.
  • the average value of the magnetic domain width measured along the first imaginary line VL1 is 600 ⁇ m or less
  • the maximum value of the magnetic domain width measured along the first imaginary line VL1 is 1200 ⁇ m or less.
  • the multiple magnetic domain control processing lines 11 provided on the surface of the grain-oriented electromagnetic steel sheet 1 have the function of subdividing the 180° magnetic domains. Subdividing the magnetic domains can reduce the iron loss of the grain-oriented electromagnetic steel sheet 1.
  • a magnetic domain is a collection of magnetic dipoles present inside a ferromagnetic material, and is a small region in which the magnetic moment is aligned in one direction.
  • a 180° magnetic domain is a magnetic domain whose magnetization direction is the ⁇ 100> orientation of the crystal and is sandwiched between two 180° magnetic domain walls that are approximately parallel to the rolling direction RD.
  • the distance between adjacent magnetic domain walls of the 180° magnetic domain is referred to as the width of the 180° magnetic domain.
  • the width of the 180° magnetic domain will be simply referred to as the "magnetic domain width".
  • Suitable examples of the magnetic domain control processing line 11 are thermal distortion and grooves. By subdividing the magnetic domains, it is possible to suppress the iron loss of the directional electromagnetic steel sheet 1. However, the magnetic domain control processing line 11 changes the magnetostrictive characteristics of the directional electromagnetic steel sheet 1 due to the return magnetic domains. This deteriorates the noise characteristics of the directional electromagnetic steel sheet 1.
  • the magnetic domain control processing lines 11 are formed in a direction intersecting the rolling direction RD of the grain-oriented electromagnetic steel sheet 1. In a typical grain-oriented electromagnetic steel sheet 1 as illustrated in FIG. 2, the magnetic domain control processing lines 11 are formed across the entire width of the grain-oriented electromagnetic steel sheet 1. However, in the grain-oriented electromagnetic steel sheet 1 according to this embodiment as illustrated in FIG. 1, it is not essential to provide the magnetic domain control processing lines 11 across the entire width of the grain-oriented electromagnetic steel sheet 1.
  • the magnetic domain control processing line 11 is straight.
  • the magnetic domain control processing line 11 may be curved.
  • the magnetic domain control processing line 11 may have a shape having straight portions and curved portions.
  • the magnetic domain control processing line 11 may be on one or both sides of the grain-oriented electromagnetic steel sheet 1.
  • the various aspects of the grain-oriented electromagnetic steel sheet 1 according to this embodiment are applied to at least one side of the grain-oriented electromagnetic steel sheet 1.
  • a square evaluation area is set with one side having a length of 50 mm and one side parallel to the rolling direction RD of the grain-oriented electrical steel sheet 1.
  • FIG. 1 shows a state in which only one first virtual line VL1 is drawn as an example. When multiple first virtual lines VL1 are set, a required number of other first virtual lines can be set parallel to the first virtual line VL1 in FIG. 1.
  • the length of the virtual line is 50 mm.
  • the virtual line extends parallel to the rolling direction RD.
  • the intersection of the virtual line and the magnetic domain control processing line 11 is defined as a magnetic domain control point VP.
  • the interval between the magnetic domain control points VP is an index of the density of the magnetic domain control processing line 11.
  • the virtual line is also used as a measurement point for the magnetic domain width of the grain-oriented electrical steel sheet 1.
  • the virtual line parallel to the rolling direction RD and having a length of 50 mm is referred to as the first virtual line VL1.
  • the standard deviation of the spacing between the magnetic domain control points VP on at least one first virtual line VL1 is 1.25 mm or more.
  • the spacing d between the magnetic domain control points VP is the distance between two adjacent magnetic domain control points VP along the first virtual line VL1.
  • the first virtual line VL1 of the grain-oriented electrical steel sheet 1 illustrated in FIG. 1 has eight magnetic domain control points VP.
  • the grain-oriented electrical steel sheet 1 of FIG. 1 satisfies the requirement of the present disclosure regarding the spacing between the magnetic domain control points VP.
  • a grain-oriented electromagnetic steel sheet 1 capable of arranging one or more first virtual lines VL1 such that the standard deviation of the spacing between magnetic domain control points VP is 1.25 mm or more will include an area X in which no magnetic domain control processing line 11 is provided, as illustrated in FIG. 1.
  • the standard deviation of the spacing between the magnetic domain control points VP may vary depending on the positions at which the evaluation area and the first virtual line VL1 are arranged. In the grain-oriented electromagnetic steel sheet 1 illustrated in FIG. 1, it is also possible to position the evaluation area and the first virtual line VL1 so that the standard deviation of the spacing between the magnetic domain control points VP is less than 1.25 mm. However, a grain-oriented electromagnetic steel sheet 1 in which one or more first virtual lines VL1 can be arranged at any location such that the standard deviation of the spacing between the magnetic domain control points VP is 1.25 mm or more is considered to satisfy the requirements of the present disclosure regarding the spacing between the magnetic domain control points VP. Therefore, the grain-oriented electromagnetic steel sheet 1 of FIG. 1 satisfies the requirements of the present disclosure regarding the spacing between the magnetic domain control points VP.
  • the grain-oriented electromagnetic steel sheet 1 illustrated in FIG. 2 in which multiple magnetic domain control processing lines 11 extending across the entire width of the grain-oriented electromagnetic steel sheet 1 are arranged at equal intervals does not include an area X where no magnetic domain control processing lines 11 are provided.
  • the standard deviation of the spacing between magnetic domain control points VP must be 1.25 mm or more, and there is no particular upper limit. However, if necessary, the upper limit of the standard deviation of the spacing between magnetic domain control points VP may be 23 mm.
  • the first virtual line VL1 (Average or maximum value of magnetic domain width measured along the first virtual line VL1)
  • the first virtual line VL1 in which the standard deviation of the intervals between the magnetic domain control points VP is 1.25 mm or more, further satisfies at least one of the following requirements.
  • the average value of the magnetic domain width measured along the first imaginary line VL1 is 600 ⁇ m or less
  • the maximum value of the magnetic domain width measured along the first imaginary line VL1 is 1200 ⁇ m or less.
  • both of the above-mentioned requirements (1) and (2) may be satisfied. That is, in the first imaginary line VL1 in which the standard deviation of the spacing between the magnetic domain control points VP is 1.25 mm or more, the average value of the magnetic domain width measured along the first imaginary line VL1 may be 600 ⁇ m or less, and the maximum value may be 1200 ⁇ m or less. In the first imaginary line VL1 in which at least one of the above-mentioned requirements (1) and (2) is satisfied, the magnetic domain width is a small value throughout the entire line.
  • the spacing between the magnetic domain control points VP varies on the first imaginary line VL1, which is the position where the magnetic domain width is measured.
  • the first imaginary line VL1, which is the position where the magnetic domain width is measured passes through the region X where the magnetic domain control processing line 11 is not provided.
  • the magnetic domain width is wide in the region X where no magnetic domain control processing has been performed. Therefore, when the magnetic domain width is measured along the first virtual line VL1 that passes through the region X where no magnetic domain control processing has been performed in a typical grain-oriented electromagnetic steel sheet 1, the average and maximum values of the magnetic domain width are extremely large. A person skilled in the art would try to make the region X where no magnetic domain control processing has been performed as small as possible. However, in the grain-oriented electromagnetic steel sheet 1 according to this embodiment, the average and/or maximum values of the magnetic domain width measured along the first virtual line VL1 where the standard deviation of the spacing between the magnetic domain control points VP is 1.25 mm or more are kept within the above-mentioned range.
  • the average value of the magnetic domain width measured along the first virtual line VL1, where the standard deviation of the spacing between the magnetic domain control points VP is 1.25 mm or more, is 500 ⁇ m or less, 450 ⁇ m or less, 400 ⁇ m or less, 380 ⁇ m or less, 350 ⁇ m or less, or 300 ⁇ m or less.
  • the maximum value of the magnetic domain width measured along the first virtual line VL1 is 1000 ⁇ m or less, 800 ⁇ m or less, 600 ⁇ m or less, 500 ⁇ m or less, 450 ⁇ m or less, or 400 ⁇ m or less.
  • Figure 3A shows an example of the distribution of magnetic domain widths of the grain-oriented electromagnetic steel sheet 1 before the magnetic domain control treatment.
  • Figure 3B shows the distribution of magnetic domain widths after the magnetic domain control treatment was applied to the surface of the grain-oriented electromagnetic steel sheet 1 in Figure 3A.
  • the magnetic domain control treatment here was performed by irradiating a continuous wave laser along a direction approximately perpendicular to the rolling direction RD.
  • the distribution of magnetic domain widths shown in Figures 3A and 3B was derived from the magnetic domain image of the grain-oriented electromagnetic steel sheet 1 using the two-dimensional Fourier transform described below.
  • FIG. 3C shows the difference between FIG. 3A and FIG. 3B.
  • FIG. 3C shows the area where the magnetic domain width has been subdivided by 50 ⁇ m or more before and after the magnetic domain control process shown in FIG. 3A and FIG. 3B.
  • FIG. 3C makes visible the area where the magnetic domain width has been subdivided by the magnetic domain control process.
  • the areas where domain refinement of 50 ⁇ m or more has occurred as a result of the domain control process are the dark areas in Figure 3A, i.e., areas where the domain width was wide prior to the domain control process.
  • the effect of domain refinement is evident in areas where the original domain width was approximately 500 ⁇ m or more.
  • the light areas in Figure 3A i.e., areas where the domain width was narrow prior to the domain control process, the effect of the domain control process is barely noticeable.
  • the effect of the domain control process differs depending on the domain width prior to the domain control process.
  • FIG. 4 shows the relationship between the magnetic domain width before the magnetic domain control process and the magnetic domain width before the magnetic domain control process at the same position.
  • the magnetic domain refinement effect of the magnetic domain control process is less likely to appear in areas with narrow magnetic domain widths.
  • the magnetic domain widths were approximately the same before and after the magnetic domain control process. Therefore, it is believed that the iron loss reduction effect of the magnetic domain control process is large in areas where the magnetic domain width before the magnetic domain control is wide, but is not sufficient in areas where the magnetic domain width before the magnetic domain control is sufficiently narrow. It is believed that the magnetic domain control process line 11 formed in areas with narrow magnetic domain widths leads to deterioration of noise characteristics due to the return domains.
  • the magnetic domain control processing lines 11 are not provided in the areas where the magnetic domain width was narrow before the magnetic domain control processing. Therefore, the grain-oriented electromagnetic steel sheet 1 according to this embodiment includes an area X where the magnetic domain control processing lines 11 are not provided.
  • the standard deviation of the spacing between the magnetic domain control points VP along the first virtual line VL1 is 1.25 mm or more.
  • the region X where the magnetic domain control processing lines 11 are not provided is a region where the magnetic domain width was narrow before the magnetic domain control processing. Therefore, in the grain-oriented electromagnetic steel sheet 1 according to this embodiment, the magnetic domain width is also narrow in the region X where the magnetic domain control processing lines 11 are not provided. In the grain-oriented electromagnetic steel sheet 1 according to this embodiment, the region X where the magnetic domain control processing lines 11 are not provided does not impair iron loss.
  • a magnetic domain control process is performed in areas with a wide magnetic domain width before the magnetic domain control process. Therefore, the iron loss of the grain-oriented electromagnetic steel sheet 1 according to this embodiment is improved by the magnetic domain control process.
  • the grain-oriented electrical steel sheet 1 when first virtual lines VL1 parallel to the rolling direction RD and 50 mm long are set at intervals of 5 mm inside the evaluation region, it is preferable that the standard deviation of the spacing between the magnetic domain control points VP is 1.25 mm or more in each of the two or more first virtual lines VL1.
  • the grain-oriented electrical steel sheet 1 includes an area X in which no magnetic domain control processing line 11 is provided, to the extent that two or more first virtual lines VL1 can be set such that the standard deviation of the spacing between the magnetic domain control points VP is 1.25 mm or more. It is even more preferable that the number of first virtual lines VL1 in which the standard deviation of the spacing between the magnetic domain control points VP is 1.25 mm or more is 3 or more, 4 or more, 5 or more, or 10 or more.
  • the magnetic domain width in the two or more first virtual lines VL1 that satisfy the standard deviation of the intervals between the magnetic domain control points VP of 1.25 mm or more is narrow. Therefore, it is preferable that one or both of the following requirements are satisfied in each of the two or more first virtual lines VL1.
  • the average value of the magnetic domain width measured along the first imaginary line VL1 is 600 ⁇ m or less
  • the maximum value of the magnetic domain width measured along the first imaginary line VL1 is 1200 ⁇ m or less.
  • the average value of the magnetic domain width measured along the first virtual lines VL1 is 500 ⁇ m or less, 450 ⁇ m or less, 400 ⁇ m or less, 380 ⁇ m or less, 350 ⁇ m or less, or 300 ⁇ m or less.
  • the maximum value of the magnetic domain width measured along the first virtual lines VL1 is 800 ⁇ m or less, 600 ⁇ m or less, 500 ⁇ m or less, 450 ⁇ m or less, or 400 ⁇ m or less.
  • the type of the magnetic domain control processing line 11 is not particularly limited, but a suitable example is a thermal distortion and/or a groove.
  • the thermal distortion can be formed by means of, for example, laser irradiation, electron beam irradiation, ion implantation, etc.
  • the groove can be formed by means of, for example, laser irradiation, electron beam irradiation, machining, etc.
  • a grain-oriented electrical steel sheet can be obtained that has excellent magnetic flux density as well as low iron loss and low noise.
  • the steel sheet has a coarse crystal grain size, and as a result, among the above characteristics, in particular the value of the standard deviation of the spacing between the magnetic domain control points VP changes.
  • the grain-oriented electrical steel sheet 1 according to this embodiment further satisfies the following characteristics.
  • the standard deviation of the distance between the magnetic domain control points VP which are the intersections of the virtual line VL1 and the magnetic domain control processing line 11, is 2.50 mm or more, and that the maximum magnetic domain width measured along the virtual line VL1 is 1200 ⁇ m or less.
  • the number of intersections between virtual lines and grain boundaries can be used as an index to determine whether a steel sheet has a coarse crystal grain size.
  • the number of intersections between virtual lines and grain boundaries can be used as an index to determine whether a steel sheet has a coarse crystal grain size.
  • the number of intersections between virtual lines and grain boundaries can be used as an index to determine whether a steel sheet has a coarse crystal grain size.
  • the number of intersections between virtual lines and grain boundaries can be used as an index to determine whether a steel sheet has a coarse crystal grain size.
  • the number of intersections between virtual lines and grain boundaries can be used as an index to determine whether a steel sheet has a coarse crystal grain size.
  • the number of grain boundary points may be two or less on each of two or more virtual lines VL1.
  • the number of grain boundary points is approximately 3 to 10.
  • the grain-oriented electrical steel sheet 1 is characterized in that a magnetic domain control process is selectively applied to regions with a wide magnetic domain width before magnetic domain control.
  • the standard deviation of the spacing between magnetic domain control points VP in at least one virtual line VL1 is 1.25 mm or more
  • the standard deviation of the spacing between magnetic domain control points VP in at least one virtual line VL1 may be less than 1.25 mm.
  • the standard deviation of the spacing between the magnetic domain control points VP on at least one virtual line VL1 may be less than 1.25 mm.
  • the virtual line VL1 in which the standard deviation of the spacing between the magnetic domain control points VP is less than 1.25 mm is not necessarily included in the square evaluation area with one side 50 mm long and parallel to the rolling direction of the grain-oriented electromagnetic steel sheet.
  • the magnetic domain control process has been selectively performed on the area with a wide magnetic domain width before magnetic domain control.
  • FIG. 5 shows an example of the hardware configuration of an image acquisition device 30 that acquires magnetic domain images of the original sheet 2, i.e., the grain-oriented electromagnetic steel sheet 1 before the magnetic domain control process.
  • the image acquisition device 30 includes a light source unit 31, a magneto-optical sensor (MO sensor 33), an image sensor 35, and a signal processing unit 37.
  • the light source unit 31 has a light source consisting of a light emitting diode (LED) and irradiates the MO sensor 33 with light with a uniform polarization plane.
  • LED light emitting diode
  • the MO sensor 33 is a device that measures the magnetic domain structure of a magnetic material.
  • the MO sensor 33 has an observation surface on which the magnetic material sample to be measured is placed. Light irradiated from the light source unit 31 passes through the inside of the MO sensor 33 and is reflected by the reflective layer. The reflected light passes through the inside of the MO sensor 33 again and is output to the outside of the MO sensor 33.
  • a leakage magnetic field corresponding to the direction of spontaneous magnetization of the original plate 2 is generated inside the MO sensor 33. This leakage magnetic field rotates the polarization plane of the reflected light.
  • the image sensor 35 is a complementary metal-oxide-semiconductor (CMOS) image sensor.
  • CMOS complementary metal-oxide-semiconductor
  • the image sensor 35 forms an image of the reflected light from the MO sensor 33 on its light receiving surface, photoelectrically converts it, and outputs the analog signal after photoelectric conversion to the signal processing unit 37.
  • the distribution of the leakage magnetic field can be obtained, and the magnetic domain structure of the original plate 2 becomes clear.
  • the signal processing unit 37 has an amplifier, an AD converter, a digital signal processor (DSP), etc.
  • the analog signal output from the image sensor 35 is amplified by the amplifier.
  • the analog signal is then converted into a digital signal by the AD converter.
  • An image signal is generated by performing a predetermined digital processing on this digital signal using the DSP.
  • the image signal generated by the signal processing unit 37 is output to the analysis device 40 (see Figure 6) via a cable or wireless communication.
  • FIG. 6 shows the hardware configuration of an analysis device 40 that analyzes the magnetic domain structure of the original plate 2.
  • the analysis device 40 is a computer device such as a personal computer (PC).
  • the analysis device 40 includes a calculation unit 41, a memory 43, a display unit 45, an input unit 47, and a communication I/F 49.
  • the calculation unit 41 has a Central Processing Unit (CPU).
  • the calculation unit 41 analyzes the magnetic domain structure from the magnetic domain image of the original plate 2 according to a program stored in the memory 43.
  • the calculation unit 41 determines the magnetic domain control processing area 21, which is the location where the magnetic domain control processing is applied. The processing executed by the calculation unit 41 will be described in detail later.
  • Memory 43 has a Read Only Memory (ROM) and a Random Access Memory (RAM).
  • the ROM stores programs executed by the CPU of the calculation unit 41, and data required for the execution of these programs.
  • the programs and data stored in the ROM are loaded into the RAM and executed.
  • the memory 43 may have a magnetic memory such as a hard disk drive (HDD) or an optical memory such as an optical disk.
  • the memory 43 may be detachable from the analysis device 40 and store the programs and data in a computer-readable recording medium.
  • the memory 43 may receive the programs executed by the calculation unit 41 from a network via the communication I/F 49.
  • the display unit 45 has a display such as a liquid crystal display (LCD), a plasma display, or an organic electroluminescence (EL) display.
  • the display unit 45 displays an image based on the image signal output from the image acquisition device 30.
  • the display unit 45 also displays the analysis results of the magnetic domain structure by the calculation unit 41.
  • the input unit 47 has input devices such as a mouse and a keyboard.
  • the communication I/F 49 is an interface for transmitting and receiving data to and from external devices via a network such as a Local Area Network (LAN), a Wide Area Network (WAN), or the Internet.
  • LAN Local Area Network
  • WAN Wide Area Network
  • Internet the Internet
  • the calculation unit 41 may be dedicated hardware such as an application-specific integrated circuit (ASIC) or a field programmable gate array (FPGA) specialized for analyzing magnetic domain structures.
  • ASIC application-specific integrated circuit
  • FPGA field programmable gate array
  • Figures 5 and 6 show a case where the image acquisition device 30 and the analysis device 40 are separate devices, a system in which the image acquisition device 30 and the analysis device 40 are integrated may also be used.
  • known means such as laser irradiation, electron beam irradiation, ion injection, etc. can be used.
  • a means for forming grooves in the surface of the original plate known means such as laser irradiation, electron beam irradiation, mechanical processing, etc. can be used.
  • laser irradiation device 500 that introduces thermal strain by laser irradiation is described.
  • FIG. 7 shows the configuration of the laser irradiation device 500.
  • the laser irradiation device 500 includes a polygon mirror 501, a light source device 503, a collimator 505, a condenser lens 507, a motor 509, a sensor 511, a control unit 513, and a plate threading device 515.
  • the plate threading device 515 threads the original plate 2 in the rolling direction RD.
  • Polygon mirror 501 is, for example, in the shape of a regular polygonal prism.
  • a number of plane mirrors are provided on each of the multiple side surfaces that make up polygon mirror 501 in the shape of a regular polygonal prism.
  • a laser beam LB is incident on the plane mirror of polygon mirror 501 in one direction (horizontal direction) from light source device 503 via collimator 505 and is reflected by the plane mirror.
  • the polygon mirror 501 can be rotated around the rotation axis O1 by being driven by a motor 509.
  • the angle of incidence of the laser beam LB with respect to the plane mirror changes sequentially according to the rotation angle of the polygon mirror 501. This sequentially changes the reflection direction of the laser beam LB, making it possible to scan the surface of the original plate 2.
  • the symbol P in FIG. 7 represents the distance between adjacent magnetic domain control processing lines 11, i.e., the irradiation pitch of the laser beam LB.
  • the light source device 503 outputs a laser beam LB in a predetermined irradiation method (e.g., continuous irradiation method or pulse irradiation method) under the control of the control unit 513.
  • a predetermined irradiation method e.g., continuous irradiation method or pulse irradiation method
  • the condenser lens 507 is provided in the optical path of the laser beam LB reflected from the polygon mirror 501.
  • the condenser lens 507 constitutes a focusing optical system with a predetermined focal length.
  • the laser beam LB reflected from the polygon mirror 501 is focused on the surface of the original plate 2 via the condenser lens 507, thereby introducing thermal distortion into the surface of the original plate 2.
  • the motor 509 is connected to the polygon mirror 501.
  • the motor 509 drives and rotates the polygon mirror 501 under the control of the control unit 513.
  • the sensor 511 is connected to the drive shaft of the motor 509.
  • the sensor 511 detects the rotation angle of the polygon mirror 501 rotated by the motor 509. Furthermore, the sensor 511 outputs a signal indicating the detected rotation angle (hereinafter referred to as the rotation angle signal) to the control unit 513.
  • the control unit 513 is composed of a processor.
  • the control unit 513 is connected to the light source device 503, the motor 509, the sensor 511, and the plate threading device 515.
  • the control unit 513 receives a speed signal from the plate threading device 515. Furthermore, the control unit 513 outputs a signal to the motor 509 to instruct the motor 509 to rotate the polygon mirror 501.
  • the control unit 513 also controls the power of the laser beam LB output by the light source device 503 to be turned on and off based on the stress introduction signal representing the magnetic domain control processing region 21 and the rotation angle signal output from the sensor 511.
  • the stress introduction signal is input from the analysis device 40 to the laser irradiation device 500.
  • the stress introduction signal may also be input to the laser irradiation device 500 by an operator.
  • the grain-oriented electromagnetic steel sheet 1 according to the present embodiment can be suitably manufactured.
  • the manufacturing method described below is merely one example of a suitable method for manufacturing the grain-oriented electromagnetic steel sheet 1, and does not limit the grain-oriented electromagnetic steel sheet 1.
  • a manufacturing apparatus will be referred to as appropriate in the explanation of the manufacturing method.
  • the manufacturing apparatus referred to below is merely a suitable example for carrying out the method for manufacturing the grain-oriented electromagnetic steel sheet 1 according to the present embodiment.
  • the manufacturing method of the grain-oriented electromagnetic steel sheet 1 includes a step S62 of acquiring a magnetic domain image of the original sheet 2 of the grain-oriented electromagnetic steel sheet 1, a step S64 of determining a magnetic domain control processing area 21 based on the distribution of magnetic domain widths in the magnetic domain image, and a step S66 of applying magnetic domain control processing to the magnetic domain control processing area 21 determined based on the distribution of magnetic domain widths.
  • a square evaluation area is set with one side 50 mm long and parallel to the rolling direction RD of the grain-oriented electromagnetic steel sheet 1, and first virtual lines VL1, each 50 mm long and parallel to the rolling direction RD, are set at intervals of 5 mm within the evaluation area.
  • the standard deviation of the intervals between the magnetic domain control points VP which are the intersections of the first virtual line VL1 and the magnetic domain control processing line 11 formed by the magnetic domain control processing, is set to 1.25 mm or more in at least one of the first virtual lines VL1.
  • a magnetic domain image of the original sheet 2 is obtained (see S62 in FIG. 8).
  • the original sheet 2 refers to the directional electromagnetic steel sheet 1 before the application of the magnetic domain control process.
  • the magnetic domain image can be obtained, for example, by the image acquisition device 30.
  • the distribution of the widths of the 180° magnetic domains is derived from the magnetic domain image.
  • the distribution of the magnetic domain widths in the original sheet 2 can be derived, for example, by using the calculation unit 41 of the analysis device 40.
  • FIG. 11 shows the original sheet 2 of the grain-oriented electromagnetic steel sheet 1 in FIG. 1.
  • the shaded regions in FIG. 11 are magnetic domain control processing regions 21.
  • the white regions in FIG. 11 are non-magnetic domain control processing regions 22.
  • the magnetic domain width of the magnetic domain control processing regions 21 is equal to or greater than the predetermined value, and the magnetic domain width of the non-magnetic domain control processing regions 22 is less than the predetermined value.
  • the magnetic domain control processing area 21 may be determined by the operator visually observing the magnetic domain image displayed on the display unit 45, and a stress introduction signal representing the magnetic domain control processing area 21 may be input to the laser irradiation device 500.
  • the magnetic domain control processing is preferentially performed on the magnetic domain control processing area 21 (see S66 in FIG. 8).
  • the magnetic domain control processing is performed only on the magnetic domain control processing area 21.
  • the magnetic domain control processing line 11 is a thermal distortion
  • the magnetic domain control processing may be performed by irradiation with a laser beam LB by a laser irradiation device 500, or other means such as ion injection or irradiation with an electron beam may be used.
  • the magnetic domain control processing line 11 is a groove, the magnetic domain control processing may be performed using a tool for machining.
  • the process for identifying the magnetic domain control processing area 21 is executed by, for example, the calculation unit 41 of the analysis device 40.
  • the calculation unit 41 derives the distribution of the magnetic domain width of the original plate 2, for example, using a line segment method or a Fourier transform. The calculation unit 41 then determines the areas where the magnetic domain width is equal to or greater than a predetermined value (for example, equal to or greater than about 500 ⁇ m) as the areas where the magnetic domain control process should be applied preferentially.
  • a predetermined value for example, equal to or greater than about 500 ⁇ m
  • evaluation is performed by drawing lines perpendicular to the magnetic domains.
  • the lines are spaced so that there are three lines per cm in the direction parallel to the magnetic domains.
  • the magnetic domain width is calculated based on the distance between the intersections of the 180° domain walls and the lines.
  • the Fourier transform is particularly effective as a means of analyzing the magnetic domain structure of magnetic materials with periodic magnetic domain structures, such as the grain-oriented electromagnetic steel sheet 1 and the original sheet 2.
  • ST2DFT short-term two-dimensional Fourier transform
  • the image (magnetic domain image) represented by the image signal acquired by the image acquisition device 30 is expressed as a data string of two-dimensional coordinates (k-l coordinates) as x(k, l).
  • the magnetic domain image to be analyzed in this embodiment is an image binarized with two types of colors, such as grayscale, or an image expressed in three or more gradations (multiple gradations).
  • the calculation unit 41 executes the following processes (A-1), (A-2) and (A-3).
  • A-1) A process of extracting a plurality of partial regions from a magnetic domain image;
  • A-2) Processing for performing ST2DFT;
  • A-3) Processing for deriving distribution of magnetic domain width.
  • the processes A-1 to A-3 will be described in detail below.
  • (A-1) Processing for Cutting out Multiple Partial Regions from a Magnetic Domain Image In order to cut out multiple partial regions from a magnetic domain image and analyze the frequency structure of each partial region, a rectangular window function Wa(k,l) is used in which the range in the k direction is 0 ⁇ k ⁇ N k -1 and the range in the l direction is 0 ⁇ l ⁇ N l-1 (N k and N l are natural numbers).
  • the window function Wa(k,l) a Hamming window, a Hanning window, a Blackman window, etc. can be used.
  • N k and N l that define the range of the window function Wa(k, l) are parameters that correspond to the number of pixels in the k direction and the number of pixels in the l direction, respectively, in the partial region.
  • ⁇ f k and ⁇ f 1 are defined as shown in equation (3).
  • ⁇ k and ⁇ l are the spatial resolutions in the k and l directions, respectively, of the magnetic domain image.
  • Figure 11 shows a plan view of an example of original plate 2.
  • Original plate 2 in Figure 11 is made of the material of grain-oriented electromagnetic steel sheet 1 in Figure 1.
  • Figure 11 shows magnetic domain control processing areas 21 and non-magnetic domain control processing areas 22 of original plate 2 identified based on a magnetic domain image.
  • Magnetic domain control processing area 21 is an area where the magnetic domain width is equal to or greater than a predetermined value.
  • Non-magnetic domain control processing area 22 is an area where the magnetic domain width is less than a predetermined value.
  • Magnetic domain control processing is applied to the dashed lines provided inside magnetic domain control processing area 21 shown in Figure 11.
  • a square evaluation area is set in the grain-oriented electrical steel sheet 1, with one side 50 mm long and parallel to the rolling direction RD of the grain-oriented electrical steel sheet 1, and first virtual lines VL1, each 50 mm long and parallel to the rolling direction RD, are set at 5 mm intervals within the evaluation area.
  • the standard deviation of the intervals along the first virtual line VL1 at the intersections of the first virtual line VL1 and the magnetic domain control processing line 11 for at least one first virtual line VL1 is set to 1.25 mm or more. This results in the grain-oriented electrical steel sheet 1 of FIG. 1 being obtained.
  • the calculation unit 41 determines the area where the magnetic domain width is equal to or greater than a predetermined value as the magnetic domain control processing area 21 (i.e., the area to which the magnetic domain control processing is applied).
  • the control unit 513 of the laser irradiation device 500 turns on the power of the laser beam LB for the magnetic domain control processing area 21, and preferably controls the power of the laser beam LB to be turned off for the non-magnetic domain control processing area 22 (i.e., the area other than the magnetic domain control processing area 21).
  • This introduces the magnetic domain control processing line 11 into the magnetic domain control processing area 21 of the original plate 2. Furthermore, in the non-magnetic domain control processing area 22 of the original plate 2, the introduction of the magnetic domain control processing line 11 is suppressed to a minimum.
  • the above-mentioned procedure can also be used to obtain a magnetic domain image of the grain-oriented electromagnetic steel sheet 1 after the magnetic domain control process.
  • the magnetic domain control process lines 11 may be unclear.
  • the observation conditions may be adjusted so that the magnetic domain control process lines 11 can be clearly seen.
  • the magnetic domain control process lines 11 can be made clear by applying a DC magnetic field along the direction perpendicular to the sheet surface (thickness direction) of the grain-oriented electromagnetic steel sheet 1.
  • the grain-oriented electrical steel sheet 1 according to the present embodiment may have a forsterite coating and/or an insulating coating on the surface of the base steel sheet, as described later. Each of these will be explained below.
  • a grain-oriented electrical steel sheet has a base steel sheet, a forsterite coating and/or an insulating coating
  • the following regulations regarding the chemical composition, magnetic domain control treatment line, magnetic domain control region, and non-magnetic domain control treatment line are regulations regarding the base steel sheet.
  • the regulations regarding the sheet thickness are regulations regarding the entire grain-oriented electrical steel sheet including the base steel sheet, the forsterite coating and/or the insulating coating.
  • the chemical composition of the grain-oriented electrical steel sheet 1 and the original sheet 2 is not limited, and may be the same as that of the known grain-oriented electrical steel sheet 1.
  • the grain-oriented electrical steel sheet 1 and the original sheet 2 have a chemical composition, in mass %, of Si: 2.500 to 7.000%, Mn: 0.00 to 1.000%, C: 0 to 0.085%, acid-soluble Al: 0 to 0.065%, N: 0 to 0.012%, Cr: 0 to 0.300%, Cu: 0 to 0.400%, P: 0 to 0.500%, Sn: 0 to 0.300%, Sb: 0 to 0.500%, and Mn: 0 to 0.500%.
  • the balance of the chemical composition includes Fe and impurities.
  • the thickness of the grain-oriented electrical steel sheet 1 and the original sheet 2 is not limited, but is preferably, for example, 0.15 mm to 0.30 mm. By making the thickness 0.30 mm or less, classical eddy current loss can be suppressed and iron loss can be further improved. On the other hand, by making the thickness 0.15 mm or more, rolling efficiency can be improved, and productivity can be improved.
  • the grain-oriented electrical steel sheet 1 and the original sheet 2 may have a forsterite coating. Furthermore, the grain-oriented electrical steel sheet 1 and the original sheet 2 may have an insulating coating. The forsterite coating and the insulating coating may be formed on one side or both sides of the grain-oriented electrical steel sheet 1.
  • the forsterite coating is, for example, an inorganic coating mainly composed of magnesium silicate.
  • the forsterite coating is formed, for example, in the final annealing, by a reaction between an annealing separator containing magnesia (MgO) applied to the surface of the base steel sheet and the components of the surface of the base steel sheet.
  • MgO magnesia
  • the forsterite coating has, for example, a composition derived from the components of the annealing separator and the base steel sheet (more specifically, a composition mainly composed of Mg 2 SiO 4 ).
  • an annealing separator mainly composed of Al 2 O 3 is used in the final annealing, the forsterite coating may not be formed.
  • the insulating coating has the function of imparting electrical insulation and tension to the oriented electromagnetic steel sheet 1. By imparting tension to the oriented electromagnetic steel sheet 1 and facilitating magnetic domain wall movement in the oriented electromagnetic steel sheet 1, the iron loss of the oriented electromagnetic steel sheet 1 can be reduced. Furthermore, the insulating coating can provide the oriented electromagnetic steel sheet 1 with various properties such as corrosion resistance, heat resistance, and slipperiness.
  • the insulating coating may be a known coating formed, for example, by applying a coating solution mainly composed of phosphate and colloidal silica to the surface of the forsterite coating and baking it.
  • the insulating coating is preferably formed after the final annealing and after the magnetic domain control treatment.
  • the insulating coating may be formed after the final annealing step and before the magnetic domain control treatment. If the insulating coating is formed before the magnetic domain control treatment, the insulating coating may peel off from the magnetic domain control treatment wire 11. Therefore, it is preferable to form the insulating coating again on the magnetic domain control treatment wire 11 after the magnetic domain control treatment.
  • the angle between the magnetic domain control processing line 11 and the rolling-perpendicular direction TD is not particularly limited.
  • the magnetic domain control processing line 11 and the rolling-perpendicular direction TD may be substantially parallel. That is, the angle between the magnetic domain control processing line 11 and the rolling-perpendicular direction TD may be substantially 0°.
  • the angle between the magnetic domain control processing line 11 and the rolling-perpendicular direction TD may be more than 0°.
  • the angle between the magnetic domain control processing line 11 and the rolling-perpendicular direction TD may be any value within the range of 0° to 45°.
  • the angle between the magnetic domain control processing line 11 and the rolling-perpendicular direction TD may be 1° or more, 3° or more, or 5° or more.
  • the angle between the magnetic domain control processing line 11 and the rolling-perpendicular direction TD may be 40° or less, 35° or less, or 30° or less.
  • the angles formed by all the magnetic domain control processing lines 11 and the direction perpendicular to the rolling TD may be the same. That is, all the magnetic domain control processing lines 11 may extend parallel to one another.
  • the angles formed by the magnetic domain control processing lines 11 and the direction perpendicular to the rolling TD may vary. That is, some or all of the multiple magnetic domain control processing lines 11 may extend non-parallel to one another.
  • the average value of the angles formed by the magnetic domain control processing lines 11 and the direction perpendicular to the rolling TD may be 1° or more, 3° or more, or 5° or more.
  • the average value of the angles formed by the magnetic domain control processing lines 11 and the direction perpendicular to the rolling TD may be 40° or less, 35° or less, or 30° or less.
  • the average angle can be calculated by measuring the angle that one magnetic domain control processing line makes with the direction perpendicular to the rolling direction TD at multiple positions, or by measuring the angles that multiple magnetic domain control processing lines make with the direction perpendicular to the rolling direction TD at one point or multiple positions, and then calculating the average value.
  • the interval P of the magnetic domain control treatment such as the irradiation pitch P of the laser beam LB shown in Fig. 7, is not particularly limited.
  • the smaller the interval P of the magnetic domain control treatment the greater the effect of improving iron loss.
  • the larger the interval P of the magnetic domain control treatment the more the noise characteristics are improved.
  • the interval can be appropriately selected according to the characteristics required of the grain-oriented electrical steel sheet 1.
  • the interval P at which the magnetic domain control process is performed corresponds to the interval between the magnetic domain control process lines 11 in the grain-oriented electromagnetic steel sheet 1 according to this embodiment and the virtual lines along these lines.
  • the virtual lines along the magnetic domain control process lines 11 provided in the grain-oriented electromagnetic steel sheet 1 are set across the entire width of the grain-oriented electromagnetic steel sheet 1, and the interval between these lines is measured, thereby determining the interval P for the magnetic domain control process.
  • the spacing P of the magnetic domain control treatment may be 1.0 mm or more, 2.0 mm or more, 3.0 mm or more, or 5.0 mm or more.
  • the spacing P of the magnetic domain control treatment may be 10.0 mm or less, 9.0 mm or less, 8.0 mm or less, or 7.0 mm or less. Note that the spacing P of the magnetic domain control treatment is a value measured along the rolling direction RD.
  • the spacing P of the magnetic domain control treatment is constant.
  • the spacing P of the magnetic domain control treatment may vary.
  • the average value of the spacing P of the magnetic domain control treatment may be 1.0 mm or more, 2.0 mm or more, 3.0 mm or more, or 5.0 mm or more.
  • the average value of the spacing P of the magnetic domain control treatment may be 10.0 mm or less, 9.0 mm or less, 8.0 mm or less, or 7.0 mm or less.
  • the magnetic domain control processing line 11 may be thermally strained. In the thermal strain, a tensile stress is introduced. The larger the tensile stress, the greater the effect of improving iron loss. On the other hand, the smaller the tensile stress, the more the noise characteristics are improved.
  • the tensile stress can be appropriately selected according to the characteristics required for the grain-oriented electrical steel sheet 1.
  • the magnitude of the tensile stress is not particularly limited, but for example, in at least a portion of the magnetic domain control processing line 11, the tensile stress in any direction is preferably 40 MPa or more, 60 MPa or more, or 80 MPa or more. When the tensile stress in at least one direction is 40 MPa or more, the requirement that "tensile stress in any direction is 40 MPa or more" is deemed to be satisfied. Also, for example, in at least a portion of the magnetic domain control processing line 11, the tensile stress in any direction is preferably 300 MPa or less, 200 MPa or less, 180 MPa or less, or 150 MPa or less. The tensile stress in any direction in the magnetic domain control processing line 11 may be uniform or may vary.
  • the magnetic domain control processing line 11 may be a groove.
  • the greater the depth and width of the groove the greater the effect of improving iron loss.
  • the smaller the depth and width of the groove the greater the improvement in noise characteristics.
  • the shape of the groove can be appropriately selected according to the characteristics required for the grain-oriented electrical steel sheet 1.
  • the depth of the groove is not particularly limited, but is preferably 5 ⁇ m to 50 ⁇ m, for example.
  • the depth of the groove may be 6 ⁇ m or more, 7 ⁇ m or more, or 10 ⁇ m or more.
  • the depth of the groove may be 48 ⁇ m or less, 45 ⁇ m or less, or 40 ⁇ m or less.
  • the width of the groove is not particularly limited, but is preferably, for example, 10 ⁇ m to 300 ⁇ m.
  • the width of the groove may be specified as 20 ⁇ m or more, 30 ⁇ m or more, or 50 ⁇ m or more.
  • the width of the groove may be specified as 280 ⁇ m or less, 250 ⁇ m or less, or 200 ⁇ m or less.
  • the depth and width of the groove may be uniform or may vary. If they vary, it is preferable that the average depth and width of multiple grooves is within the above range.
  • a method for measuring various parameters of the grain-oriented electrical steel sheet 1 according to this embodiment will be described below. Note that all of the parameters are measured on a sample taken from the grain-oriented electrical steel sheet 1. For example, a rectangular sample with both sides of 100 mm (or 100 mm or more) can be cut out from the grain-oriented electrical steel sheet 1 and used for measurement. When the grain-oriented electrical steel sheet 1 is a coil, the sample may be taken from any location of the coil. Also, when the grain-oriented electrical steel sheet 1 is a component incorporated in an electrical product such as a transformer or a motor, the sample may be taken from any location of the component.
  • the length of one side of the sample may be less than 100 mm as long as the length of one side is 50 mm or more. In this case, it is desirable to take the sample by a method such as wire cutting in order to minimize the influence of mechanical distortion on the sample.
  • the magnetic domain control processing lines 11 When the magnetic domain control processing lines 11 are grooves, the magnetic domain control processing lines 11 can be identified visually. When the grain-oriented electrical steel sheet 1 has an insulating coating, the magnetic domain control processing lines 11 can be visually observed by removing the insulating coating using a known stripping agent.
  • the magnetic domain control processing line 11 is thermally distorted, it may not be possible to visually identify the magnetic domain control processing line 11.
  • a magnetic domain image is taken using an image acquisition device 30 as illustrated in FIG. 6, for example. If necessary, the magnetic domain image is taken while applying a DC magnetic field along the normal direction ND of the rolled surface of the grain-oriented electrical steel sheet 1. By observing the magnetic domain image, the position of the thermal distortion can be identified.
  • the rolling direction RD and the direction perpendicular to the rolling direction TD of the grain-oriented electrical steel sheet 1 are specified by the following means. (1) In the case where the sample is cut out from a coil-shaped grain-oriented electrical steel sheet 1, the width direction of the coil is regarded as the direction transverse to rolling TD. In addition, the direction perpendicular to the direction transverse to rolling TD and the normal direction ND of the rolling surface is regarded as the rolling direction RD. (2) When the sample is cut out from a part of an electrical product, the rolling direction RD and the direction perpendicular to the rolling direction TD are identified from the rolling scratches on the surface of the grain-oriented electrical steel sheet 1.
  • the direction in which the rolling scratches extend is regarded as the rolling direction RD.
  • the direction perpendicular to the rolling direction RD and the normal direction ND to the rolling surface is regarded as the direction perpendicular to the rolling direction RD and the normal direction ND to the rolling surface is regarded as the direction perpendicular to the rolling direction TD.
  • the rolling direction RD and the direction perpendicular to the rolling direction TD are identified from the crystal orientation of the grain-oriented electrical steel sheet 1. Specifically, the crystal orientation of the grain-oriented electrical steel sheet 1 to be evaluated is measured at multiple points.
  • the direction in which the angle between the crystal orientation at the measurement point and the rolling surface normal direction ND (sheet thickness direction) is closest to a right angle and the deviation angle from the easy axis of magnetization ⁇ 001> is the smallest is regarded as the rolling direction RD
  • the direction perpendicular to the rolling direction RD and the rolling surface normal direction ND is regarded as the rolling direction perpendicular to the rolling direction RD.
  • the standard deviation of the intervals between the magnetic domain control processing points is calculated according to the following procedure. First, a square evaluation area with one side having a length of 50 mm and parallel to the rolling direction RD of the grain-oriented magnetic steel sheet 1 is set on the grain-oriented magnetic steel sheet 1. Then, inside the evaluation area, first virtual lines VL1 parallel to the rolling direction RD and having a length of 50 mm are set on the surface of the grain-oriented magnetic steel sheet 1 at intervals of 5 mm. Next, magnetic domain control points VP that are intersections of the first virtual lines VL1 and the magnetic domain control processing lines 11 are identified. The rolling direction RD and the magnetic domain control processing lines 11 are identified according to the procedure described above. Then, the intervals between adjacent magnetic domain control points VP are measured, and the standard deviation of these measured values is calculated.
  • the locations where the evaluation area and the first virtual line VL1 are set are not limited.
  • the first virtual line VL1 may be set at any location where the first virtual line VL1 can be set so that the standard deviation of the spacing between the magnetic domain control points VP falls within the range of this disclosure.
  • the first virtual line VL1 may be set so that it passes through an area X where no magnetic domain control processing line 11 is provided.
  • a location where the first virtual line VL1 can be set so that the standard deviation of the spacing between the magnetic domain control points VP falls within the range of this disclosure cannot be found it is presumed that the requirements of this disclosure are not met.
  • the average and maximum values of the magnetic domain widths measured along the first imaginary line VL1 are calculated according to the following procedure.
  • a magnetic domain image of a sample is captured using an image acquisition device 30 as exemplified in Fig. 5.
  • a first virtual line VL1 used for measuring the standard deviation of the intervals between magnetic domain control points VP is superimposed on the magnetic domain image.
  • a plurality of virtual lines perpendicularly intersecting the first virtual line VL1 are set at intervals of 2 mm.
  • the plurality of virtual lines perpendicularly intersecting the first virtual line VL1 are referred to as second virtual lines VL2.
  • each of the second virtual lines VL2 is 5 mm.
  • the second virtual lines VL2 intersect with the first virtual line VL1 at their centers.
  • the number of magnetic domains included in each second imaginary line VL2 is measured.
  • the value obtained by dividing the length of the second imaginary line VL2 by the number of magnetic domains included in the second imaginary line VL2 is regarded as the magnetic domain width in the second imaginary line VL2.
  • the average value of the magnetic domain width and the maximum value of the magnetic domain width on the second imaginary line VL2 are calculated.
  • FIG. 12 is a schematic diagram of a magnetic domain image.
  • magnetic domain 601A and magnetic domain 601B have a band shape.
  • adjacent magnetic domains are shown with different patterns in FIG. 12. That is, magnetic domain 601A is hatched, and magnetic domain 601B adjacent to magnetic domain 601A is not hatched.
  • the boundary between the two adjacent magnetic domains 601A and 601B is a magnetic domain wall 602.
  • the first virtual line VL1 and the second virtual line VL2 are superimposed.
  • the average and maximum magnetic domain widths are determined according to the above-mentioned steps (1) to (5). If the standard deviation of the spacing between magnetic domain control points is 1.25 mm or more and the average magnetic domain width is 600 ⁇ m or less for one or more first virtual lines VL1, the sample is deemed to be a grain-oriented electrical steel sheet according to the present disclosure. Also, if the standard deviation of the spacing between magnetic domain control points is 1.25 mm or more and the maximum magnetic domain width is 1200 ⁇ m or less for one or more first virtual lines VL1, the sample is deemed to be a grain-oriented electrical steel sheet according to the present disclosure. The more first virtual lines VL1 that satisfy the requirements of the present disclosure, the more preferable.
  • the chemical compositions of the grain-oriented electrical steel sheet 1 and the original sheet 2 may be measured by a general analysis method for steel.
  • the chemical composition may be measured using ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry).
  • ICP-AES Inductively Coupled Plasma-Atomic Emission Spectrometry
  • a test piece is obtained from the center of the thickness direction of the sample, and the chemical composition of the grain-oriented electrical steel sheet 1 and the original sheet 2 can be measured by measuring under conditions based on a calibration curve created in advance using a measuring device such as ICPS-8100 manufactured by Shimadzu Corporation.
  • the contents of C and S, which are difficult to measure using ICP-AES may be measured using a combustion-infrared absorption method.
  • the content of N may be measured using an inert gas fusion-thermal conductivity method.
  • the forsterite coating and/or insulating coating may be removed from the grain-oriented electrical steel sheet 1 and the original sheet 2 before analyzing the chemical composition of the grain-oriented electrical steel sheet 1 and the original sheet 2.
  • the forsterite coating can be removed, for example, by immersing the sample in sulfuric acid and then immersing it in nitric acid.
  • the conditions such as the temperature and concentration of the sulfuric acid and nitric acid and the immersion time are appropriately adjusted so that the base iron of the sample is not excessively dissolved.
  • An example of the conditions for removing the forsterite coating is as follows. First, the sample is immersed in 10% sulfuric acid at 80°C for 3 minutes.
  • the surface of the sample is washed with water using a rag or the like to remove sludge adhering to the surface. Then, the sample is dried. Furthermore, the sample is immersed in 10% nitric acid at room temperature for about 5 seconds while stirring.
  • the insulating coating can be removed, for example, by immersing the sample in a sodium hydroxide solution and then immersing it in dilute sulfuric acid and nitric acid.
  • the conditions such as the temperature and concentration of the sodium hydroxide, dilute sulfuric acid, and nitric acid solutions, and the immersion time are adjusted appropriately so that the base steel of the sample does not dissolve excessively.
  • An example of the conditions for removing the insulating coating is as follows.
  • the sample is immersed in a 20% sodium hydroxide solution at 80°C for 15 minutes.
  • the sample is then dried.
  • the sample is then immersed in a 10% dilute sulfuric acid solution at 80°C for 4 minutes.
  • the sludge adhering to the surface of the sample is then removed with a rag or similar.
  • the sample is then immersed in a 10% nitric acid solution at room temperature for about 10 seconds while stirring.
  • the angle between the magnetic domain control process line 11 and the direction perpendicular to the rolling direction TD can be measured using a known angle measuring means after the magnetic domain control process line 11 and the direction perpendicular to the rolling direction TD are specified by the above-mentioned procedure.
  • the spacing P of the magnetic domain control processing is obtained by first identifying the magnetic domain control processing line 11 and the rolling direction RD in the above-described procedure, then setting a virtual line along the magnetic domain control processing line 11, and measuring the spacing of the virtual line using a known length measuring means.
  • the magnetic domain control processing line 11 is identified using the procedure described above.
  • the grain-oriented electrical steel sheet 1 is cut through the magnetic domain control processing line 11 and perpendicular to the magnetic domain control processing line 11. This cut surface is used as the measurement surface.
  • the cross section of the magnetic domain control processing line 11 included in the measurement surface is analyzed using the EBSD Wilkinson method and BLG Vantage's Cross Court to extract the tensile stress components in any direction and measure their magnitude.
  • the tensile stress components can be extracted in the normal direction ND of the rolling surface, in a direction parallel to the magnetic domain control processing line 11, and in a direction perpendicular to the normal direction ND of the rolling surface and the magnetic domain control processing line 11.
  • the number of measurement points is, for example, 10. If the tensile stress in any direction is 40 MPa or more at at least one point of the grain-oriented electrical steel sheet 1 (i.e., if the tensile stress in at least one direction is 40 MPa or more), the maximum value of the tensile stress in any direction in the magnetic domain control processing line of the grain-oriented electrical steel sheet 1 is determined to be 40 MPa or more. When a measurement point where the tensile stress in any direction is 40 MPa or more is found, the measurement of the tensile stress may be stopped.
  • the depth and width of the groove can be measured by identifying the surface shape of the sample using a known three-dimensional measuring machine. If the grain-oriented electrical steel sheet 1 has an insulating coating, the insulating coating is removed using the above-mentioned procedure before three-dimensional measurement of the sample surface is performed.
  • the conditions in the example are merely one example of conditions adopted to confirm the feasibility and effects of the present disclosure.
  • the present disclosure is not limited to this one example of conditions.
  • Various conditions may be adopted in the present disclosure as long as they do not deviate from the gist of the present disclosure and the purpose of the present disclosure is achieved.
  • Example 1 A grain-oriented electrical steel sheet (a grain-oriented electrical steel sheet having a general crystal grain size) of the same lot having a thickness of 0.23 mm and classified as 23P085 in Table 2 of JIS C 2553:2019 "Grain-oriented electrical steel strip" was used as the original sheet. For example, the average heating rate of this electrical steel sheet from 1000 ° C to 1200 ° C during the temperature rise process of the finish annealing was set to 15 ° C / hour.
  • This original sheet was subjected to magnetic domain control treatment under various conditions shown in Table 1. The noise and iron loss of the grain-oriented electrical steel sheet obtained by the magnetic domain control treatment were evaluated and listed in Table 2. In Table 2, values determined to be unacceptable are underlined.
  • the shapes of the magnetic domain control processing lines were any of the following: The shapes applied to the samples are listed in the “Remarks” column of Table 1.
  • E Magnetic domain control treatment lines were formed at intervals of 4 mm only in the region within ⁇ 4 mm in the rolling direction RD from the center of each crystal grain in the rolling direction. The radius of curvature of the steel sheet at the position where the crystal grain was located during the final annealing was 250 mm.
  • the noise and iron loss were evaluated as follows. First, a three-phase transformer core was created by stacking 180 sheets of 0.23 mm-thick grain-oriented electromagnetic steel sheets. The widths of the legs and yoke of the three-phase transformer core were both 150 mm. The external height and width of the three-phase transformer core were both 750 mm. The noise and iron loss of these three-phase transformer cores were measured. The measurement conditions were a frequency of 60 Hz and an excitation magnetic flux density of 1.7 T.
  • noise evaluation results (unit: dBA) for the grain-oriented electrical steel sheet. Examples with a noise evaluation result of 37.00 dBA or less were determined to be examples in which low noise had been achieved. Noise evaluation results that were determined to be unsatisfactory are underlined.
  • the iron loss was determined by using a power analyzer to measure the voltage and current on the primary and secondary sides when excitation was performed at a frequency of 60 Hz and an excitation magnetic flux density of 1.7 T.
  • the determined iron loss is shown in Table 2 as the iron loss evaluation results (units: W/kg) of the grain-oriented electrical steel sheet. Examples with an iron loss evaluation result of 1.10 W/kg or less were determined to be examples in which low iron loss had been achieved. Noise evaluation results that were determined to be unsatisfactory are underlined.
  • the standard deviation of the spacing between the magnetic domain control points and the magnetic domain width in the grain-oriented electrical steel sheet that had been subjected to the magnetic domain control treatment were measured and listed in Table 1.
  • the measurement method essentially followed the procedure described above.
  • a rectangular sample with both sides 100 mm long was cut out from a three-phase transformer core for measuring noise and iron loss and used for measurement.
  • a square evaluation area with one side 50 mm long and one side parallel to the rolling direction of the grain-oriented electrical steel sheet was set in this rectangular sample, and virtual lines VL1 with a length of 50 mm and parallel to the rolling direction were set at 5 mm intervals inside the evaluation area. There were nine virtual lines.
  • the standard deviation of the spacing between the magnetic domain control points for each of these nine virtual lines VL1 was measured.
  • the number of virtual lines VL1 for which the standard deviation of the spacing between the magnetic domain control points was 1.25 mm or more was listed in the "Number of VL1s with a standard deviation of 1.25 mm or more" column in Table 1.
  • the average magnetic domain width and maximum magnetic domain width were also measured along each of the virtual lines VL1 where the standard deviation of the spacing between the magnetic domain control points was 1.25 mm or more.
  • the number of VL1s where the average magnetic domain width was 600 ⁇ m or less among the virtual lines VL1 where the standard deviation of the spacing between the magnetic domain control points was 1.25 mm or more was recorded in the "Number of VL1s with average magnetic domain width of 600 ⁇ m or less" column in Table 1.
  • the sample with the number recorded in the "Number of VL1s with average magnetic domain width of 600 ⁇ m or less" column as 1 corresponds to a grain-oriented electromagnetic steel sheet in which the standard deviation of the spacing between the magnetic domain control points, which are the intersections of the virtual line VL1 parallel to the rolling direction and 50 mm long, and the magnetic domain control processing line, is 1.25 mm or more, and the average magnetic domain width measured along the virtual line VL1 is 600 ⁇ m or less.
  • samples with a number of 2 or more listed in the "Number of VL1s with an average magnetic domain width of 600 ⁇ m or less" column are grain-oriented electrical steel sheets in which the standard deviation of the spacing between magnetic domain control points on two or more virtual lines VL1 is 1.25 mm or more, and the average magnetic domain width measured along the two or more virtual lines VL1 is 600 ⁇ m or less.
  • the number of virtual lines VL1 where the standard deviation of the spacing between magnetic domain control points was 1.25 mm or more is listed in the "Number of VL1s with average magnetic domain width of 500 ⁇ m or less" column of Table 1.
  • the number of virtual lines VL1 where the maximum magnetic domain width was 1200 ⁇ m or less is listed in the "Number of VL1s with maximum magnetic domain width of 1200 ⁇ m or less" column of Table 1.
  • the number of VL1s where the maximum magnetic domain width was 800 ⁇ m or less is listed in the "Number of VL1s with maximum magnetic domain width of 800 ⁇ m or less" column of Table 1.
  • Example 1 to 3 the standard deviation of the spacing between the magnetic domain control points was 1.25 mm or more, and there was one virtual line VL1 with an average magnetic domain width of 600 ⁇ m or less. In Examples 1 to 3, both the iron loss and noise evaluation results were acceptable. In Examples 1 to 3, there were zero virtual lines VL1 with a maximum magnetic domain width of 1200 ⁇ m or less, but there was one virtual line VL1 with an average magnetic domain width of 600 ⁇ m or less, so good characteristics were obtained. In Examples 4 and 8 to 11, there was also one or more virtual lines VL1 with an average magnetic domain width of 600 ⁇ m or less, so good results were obtained, just like in Examples 1 to 3.
  • Example 4 the standard deviation of the spacing between the magnetic domain control points was 1.25 mm or more, and the number of virtual lines VL1 in which the average magnetic domain width was 500 ⁇ m or less was one. In Example 4, both the iron loss and noise evaluation results were acceptable. Furthermore, the iron loss and noise evaluation results in Example 4 were better than those in Examples 1 to 3.
  • Example 5 the standard deviation of the spacing between the magnetic domain control points was 1.25 mm or more, and there was one virtual line VL1 whose maximum magnetic domain width was 1200 ⁇ m or less. In Example 5, both the iron loss and noise evaluation results were acceptable. In Example 5, there were zero virtual lines VL1 whose average magnetic domain width was 600 ⁇ m or less, but there was one virtual line VL1 whose maximum magnetic domain width was 1200 ⁇ m or less, so good characteristics were obtained. In Examples 7 and 12 to 15, there was also one or more virtual lines VL1 whose maximum magnetic domain width was 1200 ⁇ m or less, so good results were obtained, just like in Example 5.
  • Example 6 the standard deviation of the spacing between the magnetic domain control points was 1.25 mm or more, there was one virtual line VL1 with an average magnetic domain width of 500 ⁇ m or less, and there was one virtual line VL1 with a maximum magnetic domain width of 1200 ⁇ m or less. In Example 6, both the iron loss and noise evaluation results were acceptable.
  • Example 7 the standard deviation of the spacing between the magnetic domain control points was 1.25 mm or more, and the number of virtual lines VL1 with a maximum magnetic domain width of 800 ⁇ m or less was one. In Example 7, both the iron loss and noise evaluation results were acceptable. Furthermore, the iron loss evaluation result in Example 7 was better than that in Example 5.
  • Example 8 the standard deviation of the spacing between the magnetic domain control points was 1.25 mm or more, and the number of virtual lines VL1 with an average magnetic domain width of 600 ⁇ m or less was two. In Example 8, both the iron loss and noise evaluation results were acceptable. Furthermore, the iron loss and noise evaluation results for Example 8 were better than those for Examples 1 to 3.
  • Example 9 the standard deviation of the spacing between the magnetic domain control points was 1.25 mm or more, and the number of virtual lines VL1 in which the average magnetic domain width was 500 ⁇ m or less was one. In Example 9, both the iron loss and noise evaluation results were acceptable. The iron loss and noise evaluation results for Example 9 were better than those for Examples 1 to 3.
  • Example 10 the standard deviation of the spacing between the magnetic domain control points was 1.25 mm or more, and the number of virtual lines VL1 with an average magnetic domain width of 500 ⁇ m or less was two. In Example 10, both the iron loss and noise evaluation results were acceptable. Furthermore, the iron loss evaluation result in Example 10 was even better than that in Example 8.
  • Example 11 the standard deviation of the spacing between the magnetic domain control points was 1.25 mm or more, and the number of virtual lines VL1 with an average magnetic domain width of 500 ⁇ m or less was four. In Example 11, both the iron loss and noise evaluation results were acceptable. Furthermore, the iron loss evaluation result of Example 11 was even better than that of Example 10.
  • Example 12 the standard deviation of the spacing between the magnetic domain control points was 1.25 mm or more, and the number of virtual lines VL1 with a maximum magnetic domain width of 1200 ⁇ m or less was two. In Example 12, both the iron loss and noise evaluation results were acceptable. Furthermore, the iron loss and noise evaluation results of Example 12 were even better than those of Example 5.
  • Example 13 the standard deviation of the spacing between the magnetic domain control points was 1.25 mm or more, and the number of virtual lines VL1 with a maximum magnetic domain width of 1200 ⁇ m or less was four. In Example 13, both the iron loss and noise evaluation results were acceptable. Furthermore, the iron loss evaluation result of Example 13 was even better than that of Example 12.
  • Example 14 the standard deviation of the spacing between the magnetic domain control points was 1.25 mm or more, and the number of virtual lines VL1 with a maximum magnetic domain width of 800 ⁇ m or less was two. In Example 14, both the iron loss and noise evaluation results were acceptable. Furthermore, the iron loss evaluation result of Example 14 was even better than that of Example 12.
  • Example 15 the standard deviation of the spacing between the magnetic domain control points was 1.25 mm or more, and the number of virtual lines VL1 with a maximum magnetic domain width of 800 ⁇ m or less was three. In Example 14, both the iron loss and noise evaluation results were acceptable. Furthermore, the iron loss evaluation result of Example 15 was even better than that of Example 14.
  • Example 19 magnetic domain control processing lines were formed with a spacing of 4 mm only in the region within ⁇ 4 mm in the rolling direction RD from the center of each crystal grain in the rolling direction.
  • the radius of curvature of the steel sheet at the position where the crystal grain was located during final annealing was 250 mm.
  • the average magnetic domain width was more than 600 ⁇ m, and the maximum magnetic domain width was more than 1200 ⁇ m.
  • the noise evaluation results were good, but the iron loss evaluation results were poor. It is presumed that this is because magnetic domain control processing lines were not formed in the areas where magnetic domain control was required.
  • Example 2 A magnetic domain control treatment was carried out on the grain-oriented electrical steel sheet under the same conditions as in Example 1, except for the type of grain-oriented electrical steel sheet used as the original sheet. Specifically, grain-oriented electrical steel sheets (grain-oriented electrical steel sheets having coarse crystal grain sizes) of the same lot with a sheet thickness of 0.23 mm were used as the original sheet. For example, the average heating rate of this electrical steel sheet from 1000°C to 1200°C during the temperature rise process of the finish annealing was set to less than 5°C/hour.
  • the magnetic domain control treatment was carried out on this original sheet under various conditions shown in Table 3. The magnetic flux density, noise, and iron loss of the grain-oriented electrical steel sheets obtained by the magnetic domain control treatment were evaluated and listed in Table 4. In Table 4, values that were determined to be unacceptable are underlined.
  • the shape of the magnetic domain control processing line is the same as in Example 1 described above, the method of evaluating noise and iron loss is the same as in Example 1 described above, and the method of presenting the manufacturing results and evaluation results in the table is also the same as in Example 1 described above.
  • the magnetic flux density was evaluated as follows.
  • the magnetic flux density was determined by measuring using the Epstein method specified in JIS C 2550-1:2011.
  • the magnetic flux density B 8 (T) in the rolling direction of the steel sheet when excited at 800 A/m was measured.
  • the measured magnetic flux density is shown in Table 4 as the magnetic flux density evaluation result (unit: T) of the grain-oriented electrical steel sheet. Examples with a magnetic flux density evaluation result of 1.935 T or more were judged to be examples preferably superior in magnetic flux density to grain-oriented electrical steel sheets having a general crystal grain size.
  • one or more virtual lines VL1 could be set, in which the standard deviation of the spacing between the magnetic domain control points VP was 2.50 mm or more, and either the average magnetic domain width measured along the virtual line VL1 was 600 ⁇ m or less, or the maximum magnetic domain width was 1200 ⁇ m or less, the magnetic flux density results, iron loss evaluation results, and noise evaluation results were all good.
  • steel sheets with coarse crystal grain sizes have excellent magnetic flux density, but noise characteristics tend to deteriorate when conventional magnetic domain control processing is performed.
  • magnetic domain control processing lines are selectively formed based on the distribution of magnetic domain widths, and therefore, as described above, the magnetic flux density results, iron loss evaluation results, and noise evaluation results were all good.
  • Examples 35, 36, and 37 where selective magnetic domain control was not performed, there were zero virtual lines VL1 in which the standard deviation of the spacing between magnetic domain control points VP was 2.50 mm or more.
  • the average magnetic domain width was greater than 600 ⁇ m, and the maximum magnetic domain width was greater than 1200 ⁇ m. In these examples, at least one of the evaluation results for iron loss or noise was unacceptable.
  • Example 38 magnetic domain control processing lines were formed with a spacing of 4 mm only in the region within ⁇ 4 mm in the rolling direction RD from the center of each crystal grain in the rolling direction.
  • the radius of curvature of the steel sheet at the position where the crystal grain was located during final annealing was 250 mm.
  • the average magnetic domain width was more than 600 ⁇ m, and the maximum magnetic domain width was more than 1200 ⁇ m.
  • the noise evaluation results were good, but the iron loss evaluation results were poor. It is presumed that this is because magnetic domain control processing lines were not formed in the areas where magnetic domain control was required.
  • the present disclosure provides a grain-oriented electrical steel sheet that can achieve both low iron loss and low noise, and a manufacturing method thereof. Therefore, it has high industrial applicability.

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