WO2025070790A1 - 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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WO2025070790A1
WO2025070790A1 PCT/JP2024/034815 JP2024034815W WO2025070790A1 WO 2025070790 A1 WO2025070790 A1 WO 2025070790A1 JP 2024034815 W JP2024034815 W JP 2024034815W WO 2025070790 A1 WO2025070790 A1 WO 2025070790A1
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Prior art keywords
magnetic domain
domain control
grain
steel sheet
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 CN202480061156.2A priority Critical patent/CN121941784A/zh
Priority to JP2025543669A priority patent/JPWO2025070790A1/ja
Publication of WO2025070790A1 publication Critical patent/WO2025070790A1/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
    • 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
    • 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
    • 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

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 Si and has a secondary recrystallized texture consisting of an accumulation of ⁇ 110 ⁇ 001> oriented grains (Goss oriented grains) as secondary recrystallized grains 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. There is a demand for grain-oriented electrical steel sheet to reduce energy loss (iron loss).
  • a technique for narrowing the magnetic domain width of grain-oriented electromagnetic steel sheets has long been known in order to reduce iron loss.
  • 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 of irradiating with a laser or electron beam, a method using mechanical processing such as gears, and a method using chemical processing such as etching.
  • Patent Document 4 proposes a low iron loss grain-oriented electrical steel sheet and an advantageous manufacturing method thereof that alleviates problems such as a decrease in magnetic permeability and an increase in magnetostriction caused by linear grooves and local strain for magnetic domain refinement.
  • 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.
  • Patent Document 4 discloses that the ⁇ angle near the center of the rolling direction of the crystal grains is 0° on average, and that by performing magnetic domain control processing only in the region where the effect of reducing iron loss by magnetic domain control is large, it is possible to achieve both low noise and low iron loss.
  • the ⁇ angle near the center of the rolling direction of the crystal grains is not necessarily 0°, even if magnetic domain control processing is performed by the method disclosed in Patent Document 4, it is not possible to sufficiently achieve both low noise and low iron loss.
  • 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 is a grain-oriented electrical steel sheet having a plurality of magnetic domain control processing lines on a surface thereof, wherein a rectangular evaluation area is set in the grain-oriented electrical steel sheet, the length of a side parallel to the rolling direction of the grain-oriented electrical steel sheet being 50 mm and the length of a side parallel to the direction perpendicular to the rolling direction of the grain-oriented electrical steel sheet being 100 mm, and further, when virtual lines parallel to the direction perpendicular to the rolling direction and having a length of 100 mm are set inside the evaluation area at intervals of 5 mm in a direction parallel to the rolling direction, the standard deviation of the spacing between magnetic domain control points, which are 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 average value
  • the standard deviation of the spacing between the magnetic domain control points is 1.25 mm or more, and the average value
  • a ratio D L /D S of the maximum value D L of the spacing between the magnetic domain control points to the minimum value D S of the spacing between the magnetic domain control points is 2 or more.
  • the D L /D S ratio is preferably 4 or more.
  • the magnetic domain control treatment lines are thermally strained.
  • a maximum value of the tensile stress introduced into the thermal strain in the magnetic domain control treatment line is non-uniform for each measurement point of the tensile stress.
  • a rectangular evaluation area is set on the surface, with the length of a side parallel to the rolling direction being 50 mm and the length of a side parallel to the direction perpendicular to the rolling direction of the grain-oriented electrical steel sheet being 100 mm, and further, virtual lines parallel to the direction perpendicular to the rolling direction and having a length of 100 mm are set inside the evaluation area at 5 mm intervals in a direction parallel to the rolling direction, each of a plurality of intersections between the virtual lines and the plurality of magnetic domain control treatment lines is defined as a magnetic domain control point, and the maximum value of the tensile stress in unit MPa measured at each of the magnetic domain control points is defined as TS m and the variance of TS m is defined as ⁇ (TS m ) 2 , The condition ⁇ (TS m ) 2 > 5.0 is satisfied.
  • the magnetic domain control treatment lines are preferably grooves.
  • a maximum value of the groove depth in the magnetic domain control treatment line is non-uniform for each measurement point of the groove depth.
  • the length of a side parallel to the rolling direction is 50 mm and the length of a side parallel to the rolling transverse direction of the grain-oriented electrical steel sheet is 100 mm, and further, virtual lines parallel to the rolling transverse direction and having a length of 100 mm are set inside the evaluation area at 5 mm intervals in a direction parallel to the rolling direction,
  • Each of the multiple intersections between the virtual line and the multiple magnetic domain control processing lines is defined as a magnetic domain control point
  • D m the maximum value of the groove depth in unit ⁇ m measured at each of the magnetic domain control points
  • the variance of D m is defined as ⁇ (D m ) 2 , ⁇ (D m ) 2 > 3.0 is satisfied.
  • a manufacturing method of a grain-oriented electrical steel sheet according to another aspect of the present disclosure 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 rectangular evaluation area is set in the grain-
  • a region in which the magnetic domain width is equal to or greater than a predetermined value is determined to be the magnetic domain control treatment region.
  • a 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 of 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 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.
  • 1 is a graph showing the relationship between the ⁇ angle and the magnetic domain width.
  • 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.
  • 4C is a graph showing the difference between FIG. 4A and FIG. 4B.
  • FIG. 13 is a diagram 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. 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.
  • FIG. 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. 1 is a graph showing a schematic relationship between the magnetic domain width and the magnetic domain control saturation strength. 1 is a graph showing a schematic relationship between the magnitude of the ⁇ angle and the magnetic domain control saturation strength.
  • FIG. 2 is a cross-sectional schematic diagram of a grain-oriented electrical steel sheet in which the magnetic domain control treatment lines are thermally strained.
  • FIG. 2 is a schematic cross-sectional view of a grain-oriented electrical steel sheet in which the magnetic domain control treatment lines are grooves.
  • FIG. 13 is a schematic plan view illustrating a method for measuring the magnetic domain control strength at the intersection of a magnetic domain control processing line and a virtual line when the magnetic domain control processing line is thermally distorted.
  • FIG. 13 is a schematic plan view illustrating a method for measuring the magnetic domain control strength at the intersection of a magnetic domain control processing line and a virtual line when the magnetic domain control processing line is a groove.
  • the grain-oriented electrical steel sheet 1 has a plurality of magnetic domain control processing lines 11 on its surface, as exemplified in Fig. 1.
  • a rectangular evaluation area is set in which the length of the side parallel to the rolling direction RD of the grain-oriented electrical steel sheet 1 is 50 mm and the length of the side parallel to the rolling transverse direction TD of the grain-oriented electrical steel sheet 1 is 100 mm, and further, virtual lines VL parallel to the rolling transverse direction TD and having a length of 100 mm are set inside the evaluation area at intervals of 5 mm in a direction parallel to the rolling direction, in at least one virtual line VL, the standard deviation of the interval between the magnetic domain control points VP that are the intersections of the virtual line VL and the magnetic domain control processing lines 11 is 1.25 mm or more, and
  • 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 moments are 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. 1A, 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 rectangular evaluation area is set in the grain-oriented electromagnetic steel sheet 1, with the length of a side parallel to the rolling direction RD of the grain-oriented electromagnetic steel sheet 1 being 50 mm and the length of a side parallel to the direction perpendicular to the rolling direction TD of the grain-oriented electromagnetic steel sheet 1 being 100 mm.
  • the virtual line VL is used for convenience in order to define the density of the magnetic domain control processing line 11.
  • the virtual line VL is set in the aforementioned evaluation area at intervals of 5 mm in a direction parallel to the rolling direction.
  • FIG. 1A shows a state in which only one virtual line VL is drawn as an example. When multiple virtual lines VL are set, a required number of other virtual lines can be set parallel to the virtual line VL in FIG. 1A.
  • the length of the virtual line VL is 100 mm.
  • the virtual line VL extends parallel to the rolling transverse direction TD.
  • the intersection of the virtual line VL and the magnetic domain control processing line 11 is defined as the 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 standard deviation of the spacing between the magnetic domain control points VP is 1.25 mm or more on at least one virtual line VL.
  • the spacing d between the magnetic domain control points VP is the distance between two adjacent magnetic domain control points VP along the virtual line VL.
  • the virtual line VL of the grain-oriented electrical steel sheet 1 illustrated in FIG. 1A has five magnetic domain control points VP. If the standard deviation of the spacings d1 to d4 between these magnetic domain control points VP is 1.25 mm or more, the grain-oriented electrical steel sheet 1 of FIG. 1A 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 virtual lines VL 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 where the magnetic domain control processing lines 11 are not intentionally provided, for example by interrupting the magnetic domain control processing lines, as illustrated in FIG. 1A.
  • the standard deviation of the spacing between the magnetic domain control points VP can change depending on the positions at which the evaluation area and the virtual line VL are arranged.
  • a grain-oriented electromagnetic steel sheet 1 in which one or more virtual lines VL 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. 1A 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 grain-oriented electromagnetic steel sheet 1 of FIG. 2 it is not possible to arrange a virtual line VL in which the standard deviation of the spacing between magnetic domain control points VP is 1.25 mm or more. Therefore, the grain-oriented electromagnetic steel sheet 1 of FIG. 2 does not satisfy the requirements of the present disclosure regarding the spacing between magnetic domain control points VP.
  • the ⁇ angle measured in the magnetic domain control processing line 11 is set within a predetermined range.
  • the ⁇ angle is the deviation angle of the crystal grains from the Goss orientation around the axis of the direction perpendicular to the rolling direction TD. It is known that controlling the ⁇ angle is effective in controlling the magnetic properties of the grain-oriented electrical steel sheet 1.
  • the deviation angle of the crystal grains from the Goss orientation around the axis of the normal direction ND of the rolling surface is called the ⁇ angle
  • the deviation angle of the crystal grains from the Goss orientation around the axis of the rolling direction RD is called the ⁇ angle.
  • FIG. 3 is a graph showing an example of the relationship between the ⁇ angle and the average magnetic domain width of the grain-oriented electromagnetic steel sheet 1 before the magnetic domain control process.
  • the smaller the ⁇ angle the larger the magnetic domain width.
  • the relationship shown in Figure 3 does not hold for the grain-oriented electromagnetic steel sheet 1 after the magnetic domain control process. This is because the magnetic domain control process reduces the magnetic domain width in areas where the magnetic domain width was wide before the magnetic domain control process, but does not change the orientation of the crystal grains ( ⁇ angle, ⁇ angle, ⁇ angle).
  • the ⁇ angle measured between two magnetic domain control points VP having the longest distance on a virtual line VL where the standard deviation of the distance between the magnetic domain control points VP is 1.25 mm or more is specified.
  • of the absolute values of the ⁇ angles measured between two magnetic domain control points VP having the above-mentioned maximum distance D L is 1.5° or more.
  • the magnetic domain width in the region X is wide and the ⁇ angle is small. Therefore, if an ordinary grain-oriented electrical steel sheet 1 were provided with a region X where no magnetic domain control treatment had been performed, the average absolute value of the ⁇ angles on the virtual line VL passing through that region would be small, and the magnetic domain width would be large. A person skilled in the art would try to make the region X where no magnetic domain control treatment had been performed as small as possible. However, in the grain-oriented electrical steel sheet 1 according to this embodiment, the magnetic domain width in the region X where no magnetic domain control treatment had been performed is narrow, and
  • is not particularly limited, but is more preferably, for example, 10.0° or less, 7.0° or less, or 5.0° or less.
  • a grain-oriented electrical steel sheet 1 can be provided in which a virtual line VL can be set such that the standard deviation of the spacing between magnetic domain control points VP is 1.25 mm or more, and in which
  • magnetic domain control treatment is applied only to portions that contribute to reducing iron loss, and magnetic domain control treatment lines 11 are not provided in portions where magnetic domain control treatment is not required.
  • Figure 4A shows an example of the distribution of the magnetic domain width of the grain-oriented electromagnetic steel sheet 1 before the magnetic domain control treatment.
  • Figure 4B shows the distribution of the magnetic domain width after the magnetic domain control treatment was applied to the surface of the grain-oriented electromagnetic steel sheet 1 in Figure 4A.
  • the magnetic domain control treatment here was performed by irradiating a continuous wave laser along a direction inclined by 2° with respect to the rolling direction RD.
  • the distribution of the magnetic domain width shown in Figures 4A and 4B was derived from the magnetic domain image of the grain-oriented electromagnetic steel sheet 1 using the two-dimensional Fourier transform described below.
  • Figure 4C shows the difference between Figure 4A and Figure 4B.
  • Figure 4C 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 Figures 4A and 4B.
  • Figure 4C makes it possible to visualize the area where the magnetic domain width has been subdivided by the magnetic domain control process.
  • the numerical values in Figures 4A to 4C are in ⁇ m.
  • the areas where magnetic domain subdivision of 50 ⁇ m or more has occurred as a result of the magnetic domain control process are the dark areas in Figure 4A, i.e., areas where the magnetic domain width was wide prior to the magnetic domain control process.
  • the magnetic domain subdivision effect is evident in areas where the original magnetic domain width was approximately 500 ⁇ m or more.
  • the light areas in Figure 4A i.e., areas where the magnetic domain width was narrow prior to the magnetic domain control process, the effect of the magnetic domain control process is barely evident. It can be seen that the effect of the magnetic domain control process differs depending on the magnetic domain width prior to the magnetic domain control process.
  • the present inventors further investigated the relationship between the amount of reduction in the magnetic domain width caused by the magnetic domain control process and the magnetic domain width before the magnetic domain control process.
  • Fig. 5 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 magnetic domain control processing is less likely to be observed.
  • the magnetic domain width was approximately the same before and after magnetic domain control processing. Therefore, it is believed that the iron loss reduction effect of magnetic domain control processing is large in areas where the magnetic domain width before magnetic domain control is wide, but is not sufficient in areas where the magnetic domain width before magnetic domain control is sufficiently narrow. It is believed that magnetic domain control processing lines 11 formed in areas with narrow magnetic domain widths cause deterioration of noise characteristics due to 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 virtual line VL 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 and the ⁇ angle was large before the magnetic domain control processing. Therefore, in the grain-oriented electromagnetic steel sheet 1 according to this embodiment, the ⁇ angle is also large 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 standard deviation of the interval between the magnetic domain control points VP is 1.25 mm or more in each of the two or more virtual lines VL, and the average value
  • the grain-oriented electrical steel sheet 1 includes an area X where the magnetic domain control processing line 11 is not provided to the extent that two or more virtual lines VL can be set such that the standard deviation of the interval between the magnetic domain control points VP is 1.25 mm or more and
  • the grain-oriented electrical steel sheet 1 according to this embodiment is characterized in that a magnetic domain control process is selectively applied to areas with a wide magnetic domain width before magnetic domain control. In this case, more significant effects can be obtained by applying the above process to a steel sheet having a coarse crystal grain size rather than to a steel sheet having a typical crystal grain size.
  • the crystal grain size tends to become larger due to the manufacturing method.
  • Steel sheets with such coarse crystal grain sizes have excellent magnetic flux density, but because the crystal grains are too large, they tend to have high iron loss if magnetic domain control processing is not performed, making it practically necessary to perform magnetic domain control.
  • conventional magnetic domain control processing is effective in reducing the iron loss of directional electrical steel sheets, it is likely to deteriorate the noise characteristics of the directional electrical steel sheets.
  • 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-mentioned characteristics, in particular, the value of the ratio D L /D S of the maximum value D L to the minimum value D S changes.
  • the ratio D L /D S of the maximum value D L of the spacing between the magnetic domain control points to the minimum value D S of the spacing between the magnetic domain control points is preferably 2 or more. This further improves both the iron loss characteristics and the noise characteristics. More preferably, D L /D S is 4 or more. There is no upper limit to D L /D S. If necessary, the upper limit of D L /D S may be 24.
  • 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.
  • Thermal distortion disappears by stress relief annealing or a heat treatment equivalent thereto. Therefore, when the grain-oriented electromagnetic steel sheet 1 is heat treated, it is preferable to make the magnetic domain control processing line 11 a groove. On the other hand, since thermal distortion can be easily formed, when simplification of the manufacturing process is required, it is preferable to make the magnetic domain control processing line 11 a thermal distortion.
  • the grain-oriented electromagnetic steel sheet 1 may have both thermal distortion and grooves.
  • the maximum value of the tensile stress introduced into the groove depth or thermal strain which is an indicator of the strength of the magnetic domain control in the magnetic domain control treatment wire, is non-uniform for each measurement point of the groove depth or tensile stress.
  • the greater the strength of the magnetic domain control the greater the effect of magnetic domain refinement, but the greater the strength of the magnetic domain control, the greater the tendency for hysteresis loss to increase and noise characteristics to deteriorate.
  • the magnetic domain control saturation strength is not uniform in grain-oriented electrical steel sheets. Therefore, it is preferable to make the magnetic domain control strength non-uniform depending on the magnetic domain control saturation strength.
  • the magnetic domain control saturation strength is the magnetic domain control strength at which the effect of the magnetic domain subdivision process is substantially saturated.
  • the magnetic domain control strength is equal to or less than the magnetic domain control saturation strength, the greater the magnetic domain control strength, the greater the reduction in iron loss.
  • the magnetic domain control strength exceeds the magnetic domain control saturation strength, the effect of reducing iron loss is hardly improved even if the magnetic domain control strength is increased.
  • the magnetic domain control strength exceeds the magnetic domain control saturation strength, the greater the magnetic domain control strength, the greater the hysteresis loss and the worse the noise characteristics become. Therefore, it is highly preferable that the magnetic domain control strength be within a range that does not exceed the magnetic domain control saturation strength.
  • each of the multiple intersections between the virtual line and the multiple magnetic domain control processing lines is a magnetic domain control point, and when the maximum value of the tensile stress in unit MPa introduced into the thermal distortion measured at each of the magnetic domain control points is TS m and the variance of TS m is ⁇ (TS m ) 2 > 5.0 is satisfied.
  • the "maximum value of tensile stress introduced into thermal strain” is the maximum value of tensile stress measured at any one measurement cross section.
  • the tensile stress varies in one measurement cross section, and therefore, one "maximum value of tensile stress introduced into thermal strain" is identified for one measurement cross section.
  • the thermal strain 541 has a certain degree of spread in the cross section.
  • the tensile stress is greatest at the site directly irradiated with the laser, and is small at sites away from that site. In other words, the measured value of tensile stress differs for each measurement site in the cross section. According to the tensile stress measurement method described below, the distribution and maximum value of tensile stress in the cross section can be derived.
  • the maximum value of the tensile stress introduced into the thermal distortion 541 is a constant value throughout the entire magnetic domain control processing line 11.
  • the maximum value of the tensile stress introduced into the thermal distortion in the magnetic domain control processing line is non-uniform for each measurement point of the tensile stress.
  • the maximum value of the tensile stress introduced into the thermal distortion may be simply referred to as "tensile stress”.
  • the magnetic domain control saturation strength has a strong correlation with the ⁇ angle.
  • the ⁇ angle is the deviation angle from the Goss orientation of the crystal grains around the axis perpendicular to the rolling direction (TD). Where the ⁇ angle is small, the magnetic domain control saturation strength is large.
  • an optimal magnetic domain control strength depending on the magnetic domain width or ⁇ angle For example, it is preferable to perform a magnetic domain subdivision process with a high magnetic domain control strength in a location where the magnetic domain width is large and the ⁇ angle is small, and to perform a magnetic domain subdivision process with a low magnetic domain control strength in a location where the magnetic domain width is small and the ⁇ angle is large. Also, as described above, the magnetic domain subdivision process is not performed in areas where the original magnetic domain width is narrow.
  • TSm ( ⁇ 2) the arithmetic mean value of the maximum value of the tensile stress in unit MPa introduced by thermal distortion measured at each of the magnetic domain control points having a ⁇ angle of less than 2°
  • TSm ( ⁇ 2) the arithmetic mean value of the maximum value of the tensile stress in unit MPa introduced by thermal distortion measured at each of the magnetic domain control points having a ⁇ angle of 2° or more
  • TSm ( ⁇ 2) it is preferable to satisfy TSm ( ⁇ 2) >TSm ( ⁇ 2) .
  • the iron loss of the grain-oriented electrical steel sheet after the magnetic domain control is further reduced, while the increase in hysteresis loss and the deterioration of noise characteristics of the grain-oriented electrical steel sheet after the magnetic domain control are further suppressed.
  • Fig. 17 An example of a method for measuring TS m and ⁇ (TS m ) 2 will be described with reference to Fig. 17.
  • the dashed lines in Fig. 17 are multiple imaginary lines VL set at 5 mm intervals in parallel along the direction perpendicular to the rolling direction TD of the grain-oriented electrical steel sheet.
  • the x marks and O marks in Fig. 17 are intersections between the imaginary lines VL and thermal strain 541, which is the magnetic domain control processing line. Note that the ⁇ angle at the location marked with the x mark is 2° or more, and the ⁇ angle at the location marked with the O mark is less than 2°. However, it is not necessary to take the ⁇ angle at the intersection into consideration when calculating ⁇ (TS m ) 2 .
  • the direction perpendicular to the rolling direction TD of the grain-oriented electrical steel sheet is identified.
  • the direction perpendicular to the rolling direction TD can be identified by the method described below.
  • imaginary lines VL are set at 5 mm intervals parallel to the direction perpendicular to the rolling direction TD of the grain-oriented electrical steel sheet.
  • the intersections of the imaginary lines VL and the thermal distortion 541, which is the magnetic domain control processing line, are identified. If the thermal distortion 541 cannot be seen with the naked eye, the thermal distortion 541 is identified based on the magnetic domain image.
  • the shape of the measurement area is preferably a rectangle whose size along the rolling direction RD is 50 mm or more and whose size along the rolling direction TD is 100 mm or more. One side of the rectangle is preferably parallel to the rolling direction RD.
  • a rectangular evaluation area is set on the surface, with the length of a side parallel to the rolling direction being 50 mm and the length of a side parallel to the direction perpendicular to the rolling being 100 mm, and further, virtual lines parallel to the direction perpendicular to the rolling and having a length of 100 mm are set inside the evaluation area at intervals of 5 mm in a direction parallel to the rolling direction.
  • TS m is measured at the intersections of all the virtual lines in the set area and the magnetic domain control processing lines, and the variance ⁇ (TS m ) 2 of TS m is calculated.
  • the tensile stress TS m introduced by thermal strain is measured by the EBSD Wilkinson method and a Cross Court manufactured by BLG Vantage.
  • the thermal strain 541 which is the magnetic domain control processing line
  • the grain-oriented electrical steel sheet 1 is cut through the magnetic domain control processing line and perpendicular to the magnetic domain control processing line. This cut surface is used as the measurement surface.
  • the cross section of the magnetic domain control processing line included in the measurement surface is analyzed by the EBSD Wilkinson method and the Cross Court manufactured by BLG Vantage, and the tensile stress component in any direction is extracted and its magnitude is measured.
  • the tensile stress components in the normal direction of the rolling surface, the direction parallel to the magnetic domain control processing line, and the direction perpendicular to the normal direction of the rolling surface and the magnetic domain control processing line can be extracted.
  • the variance ⁇ (TS M ) 2 of the maximum tensile stress value TS M identified at each of the multiple measurement points is derived in accordance with the method for deriving population variance described in paragraph 2.36 of JIS Z 8101-1:2015 “Statistics - Terms and symbols - Part 1: General statistical terms and terms used in probability.”
  • TS m ( ⁇ 2) and TS m ( ⁇ 2) are measured by the following method.
  • the measurement of the ⁇ angles in grain-oriented electrical steel sheets is performed by the side reflection Laue method.
  • the side reflection Laue method is widely known as a method for measuring crystal orientation.
  • the maximum tensile stress TSm is identified at each of all intersections where the ⁇ angle is 2° or more, and the arithmetic mean of these values is calculated. This value is regarded as TSm ( ⁇ 2) .
  • the maximum tensile stress TSm is identified at each of all intersections where the ⁇ angle is less than 2°, and the arithmetic mean value of these values is calculated. This value is regarded as TSm ( ⁇ 2) .
  • the method for measuring the maximum tensile stress TSm introduced into the thermal strain 541 at the intersections is as described above.
  • a rectangular evaluation area is set on the surface with sides parallel to the rolling direction being 50 mm long and sides parallel to the direction perpendicular to the rolling being 100 mm long, and virtual lines parallel to the direction perpendicular to the rolling and 100 mm long are set inside the evaluation area at 5 mm intervals in a direction parallel to the rolling direction.
  • the maximum groove depth measured at each of the magnetic domain control points is Dm in units of ⁇ m and the variance of Dm is ⁇ ( Dm ) 2 , it is more preferable that ⁇ ( Dm ) 2 > 3.0 is satisfied.
  • the magnetic domain control strength is changed based on the size of the magnetic domain width or the size of the ⁇ angle, and the increase in hysteresis loss and the deterioration of noise characteristics of the grain-oriented electrical steel sheet after magnetic domain control are further suppressed.
  • the arithmetic mean value of the maximum value of the groove depth in unit ⁇ m measured at each of the magnetic domain control points having a ⁇ angle of less than 2° is defined as Dm ( ⁇ 2)
  • the arithmetic mean value of the maximum value of the groove depth in unit ⁇ m measured at each of the magnetic domain control points having a ⁇ angle of 2° or more is defined as Dm ( ⁇ 2)
  • Dm( ⁇ 2) > Dm ( ⁇ 2) it is even more preferable that Dm( ⁇ 2) > Dm ( ⁇ 2) is satisfied.
  • the magnetic domain control strength is large where the ⁇ angle is small, and the magnetic domain control strength is small where the ⁇ angle is large. Therefore, the iron loss of the grain-oriented electrical steel sheet after magnetic domain control is further reduced.
  • the increase in hysteresis loss and the deterioration of noise characteristics of the grain-oriented electrical steel sheet after magnetic domain control are further suppressed.
  • FIG. 18 An example of a method for measuring Dm and ⁇ ( Dm ) 2 is shown in Figure 18.
  • the dashed lines in Figure 18 are multiple imaginary lines VL set at 5 mm intervals in parallel along the direction perpendicular to the rolling direction TD of the grain-oriented electrical steel sheet.
  • the x marks and O marks in Figure 18 are intersections between the imaginary lines VL and the grooves 542, which are magnetic domain control processing lines.
  • the ⁇ angle at the points marked with the x marks is 2° or more, and the ⁇ angle at the points marked with the O marks is less than 2°. However, the ⁇ angle at the intersections does not need to be taken into consideration when calculating ⁇ ( Dm ) 2 .
  • the rolling direction of the grain-oriented electrical steel sheet is identified.
  • imaginary lines VL are set at 5 mm intervals parallel to the direction perpendicular to the rolling direction TD of the grain-oriented electrical steel sheet.
  • the intersections of the imaginary lines VL and the magnetic domain control processing lines are identified.
  • the shape of the measurement area is preferably a rectangle whose size along the rolling direction RD is 50 mm or more and whose size along the direction perpendicular to the rolling direction TD is 100 mm or more.
  • One side of the rectangle is preferably parallel to the rolling direction RD.
  • a rectangular evaluation area is set with sides parallel to the rolling direction being 50 mm long and sides parallel to the direction perpendicular to the rolling being 100 mm long, and virtual lines parallel to the direction perpendicular to the rolling and 100 mm long are set inside the evaluation area at 5 mm intervals in a direction parallel to the rolling direction.
  • the maximum groove depths Dm are measured at the intersections of all the virtual lines in the set area with the magnetic domain control processing lines, and the variance ⁇ ( Dm ) 2 of the maximum groove depths Dm is calculated.
  • the method for measuring the maximum groove depth Dm is as follows. Measurements are performed using a white light interference microscope Control GT-I manufactured by Bruker.
  • the lens used is a 5x objective (numerical aperture 0.12, optical resolution 2.2 ⁇ m) and an internal 1x lens, a white LED light source, and a monochrome CCD (1200 x 1000 pixels) camera.
  • the pixel size is 1.37 ⁇ m, and after performing tilt correction by fitting to a least squares plane using analysis software Vision64 Map Premium 9.2, a Gaussian filter with a cutoff value of 2.5 mm is used to remove long wavelength undulations and perform analysis. If necessary during analysis, the pixel size may be resampled to 10 ⁇ m.
  • parts that are clearly determined to be abnormal points may be excluded from the analysis, and the type of lens, filter value, and correction method may be changed depending on the properties of the sample. If grooves are formed on the grain-oriented electromagnetic steel sheet but the unevenness cannot be measured from the surface due to an insulating coating, etc., the insulating coating, etc. are removed using a known method and the above measurement is performed.
  • the ⁇ angle at the intersection is measured to identify the intersections with a ⁇ angle of 2° or more and the intersections with a ⁇ angle of less than 2°.
  • the arithmetic average value of Dm at all intersections with a ⁇ angle of 2° or more is calculated and this is regarded as Dm ( ⁇ 2) .
  • the arithmetic average value of Dm at all intersections with a ⁇ angle of less than 2° is calculated and this is regarded as Dm ( ⁇ 2) .
  • the method for measuring the maximum groove depth Dm at the intersection is as described above.
  • FIG. 6 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 7) via a cable or wireless communication.
  • FIG. 7 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 6 and 7 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 adopted.
  • 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.
  • 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 strip threading device 515.
  • the threading device 515 threads the original sheet 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. 8 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 manufacturing method of the grain-oriented electromagnetic steel sheet 1 according to the present embodiment.
  • the manufacturing method of the grain-oriented electromagnetic steel sheet 1 in this embodiment includes a process S62 of acquiring a magnetic domain image of the original sheet 2 of the grain-oriented electromagnetic steel sheet 1, a process S64 of determining a magnetic domain control processing area 21 shown in Figure 12 based on the distribution of magnetic domain widths in the magnetic domain image, and a process 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 rectangular evaluation area is set in the grain-oriented electromagnetic steel sheet 1, with the length of the side parallel to the rolling direction RD of the grain-oriented electromagnetic steel sheet 1 being 50 mm and the length of the side parallel to the rolling transverse direction TD of the grain-oriented electromagnetic steel sheet 1 being 100 mm, and further, when virtual lines VL parallel to the rolling transverse direction TD and having a length of 100 mm are set at intervals of 5 mm within the evaluation area, the standard deviation of the interval between the magnetic domain control points VP, which are the intersections of the virtual line VL and the magnetic domain control processing line 11, is set to 1.25 mm or more for at least one virtual line VL.
  • a magnetic domain image of the original sheet 2 is obtained (see S62 in FIG. 9).
  • 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. 12 shows the original sheet 2 of the grain-oriented electromagnetic steel sheet 1 in FIG. 1.
  • the shaded regions in FIG. 12 are magnetic domain control processing regions 21.
  • the white regions in FIG. 12 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 strength is determined according to the magnetic domain width of the grain-oriented electrical steel sheet before the magnetic domain refinement process.
  • the magnetic domain control strength is the amount of thermal distortion when the magnetic domain control means is thermal distortion, and is the depth of the groove when the magnetic domain control means is a groove.
  • the maximum value of tensile strength or the depth of the groove introduced by the thermal distortion in the magnetic domain control process line becomes non-uniform for each measurement point of the tensile strength or the groove depth.
  • the magnetic domain control saturation strength is not uniform in grain-oriented electrical steel sheets.
  • the magnetic domain control saturation strength is the magnetic domain control strength at which the effect of the magnetic domain subdivision process becomes saturated.
  • the magnetic domain control strength is equal to or less than the magnetic domain control saturation strength, the greater the magnetic domain control strength, the greater the reduction in iron loss.
  • increasing the magnetic domain control strength does not improve the effect of reducing iron loss.
  • the magnetic domain control strength exceeds the magnetic domain control saturation strength, the greater the magnetic domain control strength, the greater the hysteresis loss and the worse the noise characteristics become. Therefore, it is highly preferable to set the magnetic domain control strength within a range that does not exceed the magnetic domain control saturation strength.
  • the magnetic domain refinement process it is preferable to perform a magnetic domain refinement process with a high magnetic domain control strength in areas where the magnetic domain width is large and the ⁇ angle is small, and to perform a magnetic domain refinement process with a low magnetic domain control strength in areas where the magnetic domain width is small and the ⁇ angle is large.
  • the effect of magnetic domain control is not obtained, so the magnetic domain control saturation strength is 0.
  • the effect of magnetic domain control is obtained. For example, when the ⁇ angle is 2° or less, it is estimated that the effect of magnetic domain control is obtained.
  • the magnetic domain control saturation strength is approximately constant.
  • FIG. 18 shows a graph that illustrates a method for determining the magnetic domain control strength based on the magnetic domain width.
  • the vertical axis of FIG. 18 is the magnetic domain control strength, and the horizontal axis is the magnetic domain width.
  • the solid line graph in FIG. 18 is the magnetic domain control saturation strength. In areas where the magnetic domain width is small, the effect of magnetic domain control cannot be obtained, so the magnetic domain control saturation strength is 0. In areas where the magnetic domain width exceeds 500 ⁇ m, the effect of magnetic domain control can be obtained. And in areas where the magnetic domain width exceeds 500 ⁇ m, the magnetic domain control saturation strength increases as the magnetic domain width increases. And in areas where the magnetic domain width exceeds approximately 1200 ⁇ m, the magnetic domain control saturation strength is approximately constant.
  • Figure 14 shows a graph that illustrates a method for determining the magnetic domain control strength based on the ⁇ angle.
  • the vertical axis of Figure 14 is the magnetic domain control strength, and the horizontal axis is the magnitude of the ⁇ angle.
  • the solid line graph in Figure 14 is the magnetic domain control saturation strength. In areas where the ⁇ angle is large, the effect of magnetic domain control cannot be obtained, so the magnetic domain control saturation strength is 0. In areas where the ⁇ angle is below a predetermined value, the effect of magnetic domain control can be obtained. For example, when the ⁇ angle is 2° or less, it is estimated that the effect of magnetic domain control can be obtained. And in areas where the ⁇ angle is below a predetermined value, the larger the ⁇ angle, the greater the magnetic domain control saturation strength becomes. And in areas where the ⁇ angle is even smaller, the magnetic domain control saturation strength is approximately constant.
  • the relationship between the magnetic domain width at the location where magnetic domain control is performed and the magnetic domain control strength is on the solid line graph in Figure 14. Or, it is most preferable that the relationship between the ⁇ angle at the location where magnetic domain control is performed and the magnetic domain control strength is on the solid line graph in Figure 14.
  • the magnetic domain control saturation strength can be used as a target value for the magnetic domain control strength.
  • the magnetic domain control strength is the minimum strength at which the magnetic domain control effect is manifested.
  • the magnetic domain control strength is equal to or greater than the minimum magnetic domain control strength.
  • the magnetic domain control strength may vary slightly from the magnetic domain control saturation strength, which is the target value.
  • the region that is equal to or greater than the magnetic domain control minimum strength and is within a certain range from the graph of the magnetic domain control saturation strength is referred to as the target range of the magnetic domain control strength.
  • the magnetic domain control strength and the magnetic domain width of the magnetic domain control target part are preferably within the shaded region surrounded by the dashed line in Fig. 13 and Fig. 14.
  • the magnetic domain control processing line is a thermal strain
  • the magnetic domain control strength can be changed by changing the irradiation conditions of the laser or electron beam. Specifically, the power, irradiation time, irradiation interval, etc. of the laser or electron beam can be changed to change the average irradiation energy density Ua (mJ/ mm2 ) per unit area.
  • the magnetic domain control processing line is a groove
  • the depth of the groove formed in the grain-oriented electrical steel sheet can be changed by adjusting the time, intensity, shape, etc. of the method of irradiating the laser or electron beam, the method of mechanical processing such as gears, or the method of chemical processing such as etching.
  • the magnetic domain control processing is preferentially performed on the magnetic domain control processing area 21 (see S66 in FIG. 9).
  • 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 two-dimensional 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 approximately 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 approximately 500 ⁇ m
  • the two-dimensional 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 using two types of colors, or an image expressed in three or more gradations (multiple gradations), such as grayscale.
  • the calculation unit 41 executes the following processes (A-1), (A-2) and (A-3).
  • A-1 Processing for cutting out a plurality of partial regions from a magnetic domain image
  • A-2 Processing for performing ST2DFT
  • A-3 Processing for deriving the distribution of magnetic domain widths
  • (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.
  • ⁇ k and ⁇ l are the spatial resolutions in the k and l directions, respectively, of the magnetic domain image.
  • the distribution of magnetic domain widths L(n, m) is derived from the spatial frequency resolution defined in equation (3) and the peak positions of the spots in the partial Fourier image, as shown in equation (4).
  • FIG. 12 shows a plan view of an example of the original sheet 2.
  • the original sheet 2 in FIG. 12 is the material of the grain-oriented electromagnetic steel sheet 1 in FIG. 1.
  • FIG. 12 shows a magnetic domain control processing region 21 and a non-magnetic domain control processing region 22 of the original sheet 2 identified based on the magnetic domain image.
  • the magnetic domain control processing region 21 is a region where the magnetic domain width is equal to or greater than a predetermined value.
  • the magnetic domain control processing region 21 of the original sheet 2 roughly corresponds to a region in the grain-oriented electromagnetic steel sheet 1 where the ⁇ angle is small.
  • the non-magnetic domain control processing region 22 of the original sheet 2 roughly corresponds to a region in the grain-oriented electromagnetic steel sheet 1 where the ⁇ angle is large.
  • the non-magnetic domain control processing region 22 is a region where the magnetic domain width is less than a predetermined value and where the ⁇ angle is large.
  • the magnetic domain control processing is applied to the region not surrounded by the dashed line shown in FIG. 12.
  • a rectangular evaluation area is set in the grain-oriented electrical steel sheet 1, with the length of the side parallel to the rolling direction RD of the grain-oriented electrical steel sheet 1 being 50 mm and the length of the side parallel to the rolling transverse direction TD of the grain-oriented electrical steel sheet 1 being 100 mm, and further, virtual lines VL parallel to the rolling transverse direction TD and 100 mm long are set inside the evaluation area at intervals of 5 mm in a direction parallel to the rolling direction, and in at least one of the virtual lines VL, the standard deviation of the intervals along the virtual line VL of the intersections between the virtual line VL and the magnetic domain control processing line 11 is set to 1.25 mm or more.
  • 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 a 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 direction perpendicular to the rolling direction TD is not particularly limited.
  • the angle between the magnetic domain control process line 11 and the rolling-perpendicular direction TD must be greater than 0°.
  • the angle between the magnetic domain control process 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 process line 11 and the rolling-perpendicular direction TD may be 2° or more, 3° or more, or 5° or more.
  • the angle between the magnetic domain control process 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 2° 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 which is determined by the irradiation pitch P of the laser beam LB shown in Fig. 8, 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 process 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 process may be 10.0 mm or less, 9.0 mm or less, 8.0 mm or less, or 7.0 mm or less.
  • the spacing P of the magnetic domain control process is a value measured along the rolling direction RD.
  • the magnetic domain control process line 11 is drawn approximately parallel to the direction perpendicular to the rolling for the sake of simplicity, but in reality, as explained above, it is inclined at a predetermined angle with respect to the direction perpendicular to the rolling TD.
  • 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. All 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 along the rolling transverse direction TD may be 50 mm or more and less than 100 mm, as long as the length of one side of the sample along the rolling transverse direction TD is 100 mm or more. At that time, it is desirable to take the sample by a method such as wire cutting processing 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. 5, 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 which has the smallest deviation angle from the magnetization easy axis ⁇ 001> 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.
  • Standard deviation of spacing between magnetic domain control points VP The standard deviation of the intervals between the magnetic domain control points is calculated according to the following procedure. First, a rectangular evaluation area is set in the grain-oriented magnetic steel sheet 1, with the length of the side parallel to the rolling direction RD of the grain-oriented magnetic steel sheet 1 being 50 mm, and the length of the side parallel to the rolling transverse direction TD of the grain-oriented magnetic steel sheet 1 being 100 mm. Then, inside the evaluation area, virtual lines VL parallel to the rolling transverse direction TD and having a length of 100 mm are set on the surface of the grain-oriented magnetic steel sheet 1 at intervals of 5 mm.
  • the magnetic domain control points VP which are the intersections of the virtual lines VL and the magnetic domain control processing lines 11, are identified.
  • the rolling transverse direction TD and the magnetic domain control processing lines 11 are identified according to the above-mentioned procedure. 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 virtual line VL are set are not limited.
  • the virtual line VL may be set at any location where the virtual line VL 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 virtual line VL 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 virtual line VL 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 minimum value D S and maximum value D L of the distance between the magnetic domain control processing points are calculated according to the following procedure.
  • the above-mentioned virtual line VL is set on the surface of the grain-oriented electrical steel sheet 1.
  • the magnetic domain control point VP which is the intersection of the virtual line VL and the magnetic domain control processing line 11, is identified.
  • the rolling direction RD and the magnetic domain control processing line 11 are identified according to the above-mentioned procedure.
  • the distance between adjacent magnetic domain control points VP is measured, and the minimum and maximum values of these measurements are obtained.
  • the ⁇ angle is measured by the side reflection Laue method.
  • the side reflection Laue method is widely known as a method for measuring crystal orientation.
  • the ⁇ angle is the value obtained by rounding off the measured value to one decimal place. In other words, the significant figures of the ⁇ angle are rounded to one decimal place.
  • the ⁇ angle between each adjacent magnetic domain control point VP is measured at 1 mm intervals from the midpoint P ⁇ L of the magnetic domain control point VP, and the average value of the absolute values of these ⁇ angles may be regarded as
  • is the same as that of
  • two adjacent magnetic domain control points VP whose interval is the minimum value D S on the virtual line VL are identified by the above-mentioned means.
  • the ⁇ angle between these magnetic domain control points VP is measured by the above-mentioned means at 1 mm intervals from the midpoint P ⁇ S of the magnetic domain control points VP.
  • the interval there may be two or more locations on one virtual line VL where the interval is D S.
  • the ⁇ angle between each adjacent magnetic domain control point VP is measured at 1 mm intervals from the midpoint P ⁇ S of the magnetic domain control point VP, and the average value of the absolute values of these ⁇ angles may be regarded as
  • 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 components 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 compositions of the grain-oriented electrical steel sheet 1 and the original sheet 2 are measured under conditions based on a calibration curve created in advance using a measuring device such as Shimadzu Corporation's ICPS-8100.
  • 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 the insulating coating may be removed from the grain-oriented electrical steel sheet 1 and the original sheet 2 before the chemical components of the grain-oriented electrical steel sheet 1 and the original sheet 2 are analyzed.
  • the forsterite film 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 does not dissolve excessively.
  • An example of the conditions for removing the forsterite film is as follows.
  • the sample is immersed in 10% sulfuric acid at 80°C for 3 minutes. Then, 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, followed by immersion in dilute sulfuric acid and nitric acid. Conditions such as the temperature and concentration of the sodium hydroxide, dilute sulfuric acid, and nitric acid solutions, and the immersion time are appropriately adjusted so that the base iron of the sample does not dissolve excessively.
  • An example of conditions for the insulating coating removal process is as follows: First, 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. After that, sludge adhering to the surface of the sample is removed with a rag or the like. Furthermore, the sample is 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 process line 11 is identified by the above-mentioned procedure.
  • the grain-oriented electrical steel sheet 1 is cut through the magnetic domain control process line 11 and perpendicular to the magnetic domain control process 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 by the EBSD Wilkinson method and Cross Court manufactured by BLG Vantage, and tensile stress components in any direction are extracted and their magnitude is measured. For example, tensile stress components in the normal direction (ND) of the rolling surface, the direction parallel to the magnetic domain control processing line 11, and the direction perpendicular to the normal direction ND of the rolling surface and the magnetic domain control processing line 11 can be extracted.
  • the number of measurement points is, for example, 10.
  • 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. Therefore, if the purpose is to determine whether the maximum value of the tensile stress is 40 MPa or more, the measurement of the tensile stress may be stopped when a measurement point where the tensile stress in any direction is 40 MPa or more is found. However, when ⁇ (TS m ) 2 , TS m ( ⁇ 2) , or TS m ( ⁇ 2) described later is to be obtained, the measurement is not stopped and the tensile stress at each measurement point is obtained.
  • 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 Grain-oriented electrical steel sheets of the same lot having a thickness of 0.20 mm were used as the original sheets.
  • the original sheets were subjected to magnetic domain control treatment under various conditions shown in Table 1.
  • Table 1 For the steel sheets No. 1 to 13 obtained by each treatment, the number of VLs (virtual lines) with a standard deviation of 1.25 mm or more is shown in column A of Table 1, and the number of VLs in column A that further satisfy the relationship
  • Column C of Table 1 shows the number of VLs in column B that further satisfy the relationship 2 ⁇ D L /D S , and column D of Table 1 shows the number of VLs in column C that further satisfy the relationship 0.5° ⁇
  • were measured according to the above-mentioned procedure.
  • a rectangular sample with both sides of 100 mm was cut out from a three-phase transformer core for measuring noise and iron loss, which will be described later, and was used for the measurement.
  • a rectangular evaluation area was set in the rectangular sample, with the length of the side parallel to the rolling direction RD being 50 mm and the length of the side parallel to the rolling transverse direction TD being 100 mm, and virtual lines VL, which were parallel to the rolling transverse direction TD and had a length of 100 mm, were set at 5 mm intervals within the evaluation area. The number of virtual lines VL was nine.
  • Samples No. 1 to 10 in Table 1 are samples with linear magnetic domain control processing lines formed in the wide magnetic domain width area.
  • Sample No. 11 is a sample with linear magnetic domain control processing lines formed across the entire width.
  • Sample No. 12 is a sample with regularly broken magnetic domain control processing lines formed.
  • Sample No. 13 is a sample with randomly broken magnetic domain control processing lines formed.
  • Sample No. 14 is a sample with linear magnetic domain control processing lines including curves formed in the wide magnetic domain width area.
  • Sample No. 15 is a sample with magnetic domain control processing lines formed at intervals of 4 mm only in the area within ⁇ 4 mm from the center of the rolling direction of each crystal grain in the rolling direction RD. The radius of curvature of the steel sheet at the position where the crystal grain was located during final annealing was 250 mm.
  • thermo distortion thermal distortion
  • Table 1 The samples labeled "thermal distortion" in Table 1 were subjected to a magnetic domain control treatment by irradiating a laser beam with an average irradiation energy density of 1.5 mJ/ mm2 at intervals of 4 mm.
  • the samples indicated as having grooves in Table 1 had grooves (depth: 15 ⁇ m, width: 20 ⁇ m) formed therein to control the magnetic domains.
  • the term "mixed” shown in Table 1 means that the magnetic domain control processing conditions were such that the thermal distortion and the grooves described above were controlled so that the total length was 1:1.
  • the noise and core loss of the grain-oriented electrical steel sheets that had been subjected to the above-mentioned magnetic domain control treatment were measured.
  • the measurement results are shown in Table 2.
  • the method for measuring noise and iron loss was as follows. First, 205 grain-oriented electromagnetic steel sheets with a thickness of 0.20 mm were laminated to produce a three-phase transformer core. The widths of the legs and yoke of the three-phase transformer core were both 150 mm. The height and width of the outer shape 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 50 Hz and an excitation magnetic flux density of 1.8 T.
  • noise evaluation results (unit: dBA) for the grain-oriented electrical steel sheet. Examples with a noise evaluation result of 43.50 dBA or less were determined to be examples in which low noise had been achieved. In Table 2, noise evaluation results that were determined to be unsatisfactory are underlined.
  • the iron loss was determined by measuring the voltage and current on the primary and secondary sides with a power analyzer when excitation was performed at a frequency of 50 Hz and an excitation magnetic flux density of 1.8 T.
  • the determined iron loss is shown in Table 3 as the iron loss evaluation results (unit: W/kg) of the grain-oriented electrical steel sheet. Examples with an iron loss evaluation result of 1.270 W/kg or less were determined to be examples in which low iron loss had been achieved.
  • Samples Nos. 1 to 3 and 14 shown in Table 2 were samples in which the standard deviation of the intervals between the magnetic domain control points, which are the intersections between the virtual lines and the magnetic domain control processing lines, was 1.25 mm or more, and the average absolute value of the ⁇ angle
  • sample No. 11 was subjected to magnetic domain control treatment over the entire width, so the iron loss was good, but the noise characteristics were poor.
  • Sample No. 12 was subjected to magnetic domain control treatment in the broken line shape, so the noise was improved compared to sample No. 11, but both the iron loss characteristics and the noise characteristics were unacceptable.
  • Sample No. 13 was subjected to random magnetic domain control treatment in the broken line shape, so the noise was further improved compared to sample No. 12, but the iron loss characteristics were unacceptable.
  • the magnetic domain control treatment was performed only on the central region in the rolling direction of each crystal grain, so although the noise was within a preferable range, the core loss characteristics were unacceptable.
  • Samples No. 4 and 5 satisfy the conditions met by samples No. 1 to 3 described above, and in addition, among the multiple virtual lines spaced 5 mm apart, in each of two or more virtual lines, the standard deviation of the spacing between the magnetic domain control points is 1.25 mm or more, and the average absolute value of the ⁇ angle
  • the iron loss of samples No. 4 and 5 is superior to that of samples No. 1 and 2, and in terms of noise, excellent characteristics equivalent to those of samples No. 1 and 2 can be obtained.
  • Sample No. 6 satisfies the conditions met by samples No. 1 to 3 above, and also has a D L /D S ratio of 2 or more. The iron loss of sample No. 6 is superior to the iron loss of samples No.
  • sample No. 6 can be evaluated as having superior characteristics in terms of both iron loss and noise.
  • Sample No. 7 not only fulfills the conditions fulfilled by samples No. 4 and 5, but also has a D L /D S ratio of 2 or more. The iron loss and noise of sample No. 7 were superior to those of samples No. 1 to 3 in terms of iron loss and noise.
  • Sample No. 8 satisfies the conditions satisfied by samples No. 1 to 3, and also satisfies the relationship 0.5° ⁇
  • the iron loss and noise of sample No. 8 were superior to those of samples No. 1 to 3 in terms of iron loss and noise.
  • Sample No. 9 is a sample that satisfies both the conditions satisfied by samples No. 6 and No. 8. The iron loss and noise of sample No. 9 were superior to the iron loss and noise of samples No. 1 to 3.
  • Sample No. 10 is a sample that satisfies all of the conditions satisfied by samples No. 7 and 8. The iron loss and noise of sample No. 10 were superior to those of samples No. 7 to 9 in terms of iron loss and noise.
  • Example 2 A grain-oriented electrical steel sheet of the same lot having a thickness of 0.20 mm was used as the original sheet.
  • the original sheet was subjected to a magnetic domain control treatment under various conditions shown in Table 3.
  • Table 3 For steel sheets No. 16 to 23 obtained by each treatment, the number of VLs (virtual lines) having a standard deviation of 1.25 mm or more is shown in column A of Table 1, and the number of VLs in column A that further satisfy the relationship
  • Column C of Table 1 shows the number of VLs in column B that further satisfy the relationship 4 ⁇ D L /D S , and column D of Table 1 shows the number of VLs in column C that further satisfy the relationship 0.5° ⁇
  • were measured according to the above-mentioned procedure.
  • a rectangular sample with both sides of 100 mm was cut out from a three-phase transformer core for measuring noise and iron loss, which will be described later, and was used for the measurements.
  • a rectangular evaluation area was set in the rectangular sample, with the length of the side parallel to the rolling direction RD being 50 mm and the length of the side parallel to the rolling transverse direction TD being 100 mm, and virtual lines VL, which were parallel to the rolling transverse direction TD and had a length of 100 mm, were set at 5 mm intervals within the evaluation area. The number of virtual lines VL was nine.
  • Samples No. 16 to 22 shown in Table 3 are samples in which linear magnetic domain control processing lines are formed in areas with wide magnetic domain widths.
  • Sample No. 23 is a sample in which linear magnetic domain control processing lines, including curves, are formed in areas with wide magnetic domain widths.
  • thermo distortion The samples labeled "thermal distortion" in Table 3 were irradiated with a laser beam having an average irradiation energy density of 1.5 mJ/ mm2 at intervals of 4 mm, and subjected to a magnetic domain control treatment.
  • grooves depth: 15 ⁇ m, width: 20 ⁇ m
  • mixed the magnetic domain control processing conditions were such that the thermal distortion and the grooves described above were controlled so that the total length was 1:1.
  • Example 3 Grain-oriented electrical steel sheets of the same lot having a thickness of 0.20 mm were used as the original sheets.
  • the original sheets were subjected to magnetic domain control treatment under various conditions shown in Table 5.
  • Table 5 For steel sheets No. 24 to 61 obtained by each treatment, the number of VLs (virtual lines) having a standard deviation of 1.25 mm or more is shown in column A of Table 1, and the number of VLs in column A that further satisfy the relationship
  • Column C of Table 1 shows the number of VLs in column B that further satisfy the relationship 2 ⁇ D L /D S
  • column D of Table 1 shows the number of VLs in column B that further satisfy the relationship 4 ⁇ D L /D S
  • column E shows the number of VLs in column C that further satisfy the relationship 0.5° ⁇
  • column F shows the number of VLs in column D that further satisfy the relationship 0.5° ⁇
  • were measured according to the above-mentioned procedure. A rectangular sample with both sides 100 mm long was cut out from a three-phase transformer core for measuring noise and iron loss, which will be described later, and used for the measurement.
  • a rectangular evaluation area was set in this rectangular sample, with the side parallel to the rolling direction RD being 50 mm long and the side parallel to the rolling transverse direction TD being 100 mm long, and virtual lines VL, parallel to the rolling transverse direction TD and 100 mm long, were set at 5 mm intervals within the evaluation area.
  • the number of virtual lines VL was nine.
  • Samples No. 24 to No. 61 shown in Table 5 are samples in which linear magnetic domain control processing lines are formed in areas with wide magnetic domain widths.
  • the samples labeled "thermal distortion" in Table 5 were subjected to a magnetic domain control treatment by linearly irradiating the samples with 4 mm intervals with a laser beam having an average irradiation energy density of 0.5 mJ/mm 2 to 4.0 mJ/mm 2 .
  • grooves depth: 15 ⁇ m to 41 ⁇ m, width: 20 ⁇ m

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PCT/JP2024/034815 2023-09-27 2024-09-27 方向性電磁鋼板、及び方向性電磁鋼板の製造方法 Pending WO2025070790A1 (ja)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11124629A (ja) * 1997-10-16 1999-05-11 Kawasaki Steel Corp 低鉄損・低騒音方向性電磁鋼板
JP2001192785A (ja) * 2000-01-06 2001-07-17 Kawasaki Steel Corp 磁気特性に優れた方向性電磁鋼板およびその製造方法
JP2021169655A (ja) * 2020-04-16 2021-10-28 日本製鉄株式会社 方向性電磁鋼板、方向性電磁鋼板の磁区構造の解析方法及び解析システム

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6015919B2 (ja) * 2012-10-05 2016-10-26 Ｊｆｅスチール株式会社 方向性電磁鋼板の製造方法

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11124629A (ja) * 1997-10-16 1999-05-11 Kawasaki Steel Corp 低鉄損・低騒音方向性電磁鋼板
JP2001192785A (ja) * 2000-01-06 2001-07-17 Kawasaki Steel Corp 磁気特性に優れた方向性電磁鋼板およびその製造方法
JP2021169655A (ja) * 2020-04-16 2021-10-28 日本製鉄株式会社 方向性電磁鋼板、方向性電磁鋼板の磁区構造の解析方法及び解析システム

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