Grain-oriented electromagnetic steel sheet and method for producing grain-oriented electromagnetic steel sheet

Abstract

Provided is a grain-oriented electromagnetic steel sheet having a magnetic domain control processing line on a surface thereof. The grain-oriented electromagnetic steel sheet satisfies |βAll|-|βDr| ≥ 0.1°, wherein |βAll| is an average value of absolute values of β angles over the entire surface of the grain-oriented electromagnetic steel sheet, and |βDr| is an average value of absolute values of β angles at magnetic domain control points that are intersection points of a plurality of virtual lines with the magnetic domain control processing line, the virtual lines being provided in parallel at 2-mm intervals along the rolling direction of the grain-oriented electromagnetic steel sheet. Also provided is a method for producing a grain-oriented electromagnetic steel sheet, the method comprising: a step of acquiring a magnetic domain image of an original sheet for a grain-oriented electromagnetic steel sheet; a step of determining a magnetic domain control processing region on the basis of the distribution of the magnetic domain widths in the magnetic domain image; and a step of applying a magnetic domain control process to the magnetic domain control processing region determined on the basis of the distribution of the magnetic domain widths.

Description

Grain-oriented electrical steel sheet and method for manufacturing grain-oriented electrical steel sheet

[0001] This disclosure relates to a grain-oriented electrical steel sheet and a method for manufacturing the grain-oriented electrical steel sheet. This application claims priority to Japanese Patent Application No. 2023-166060, filed on September 27, 2023, the contents of which are incorporated herein by reference.

[0002] Grain-oriented electrical steel sheets are steel sheets containing 7 mass% or less of Si and having a secondary recrystallization texture in which secondary recrystallized grains are concentrated in the {110}<001> orientation (Goss orientation), with the easy axis of magnetization <001> oriented in the rolling direction. Grain-oriented electrical steel sheets are mainly used as iron cores for power transformers. Reduction of energy loss (iron loss) is required for grain-oriented electrical steel sheets.

[0003] A technique for narrowing the magnetic domain width of grain-oriented electrical steel sheets (magnetic domain refinement technique by magnetic domain control treatment) has long been known to reduce iron loss. The magnetic domain width can be narrowed by irradiating the surface of the grain-oriented electrical steel sheet with a laser or electron beam in a direction intersecting the rolling direction to introduce thermal strain. The magnetic domain width can also be narrowed by forming grooves in the surface of the grain-oriented electrical steel sheet in a direction intersecting the rolling direction. Groove formation methods include laser or electron beam irradiation, mechanical processing such as gear machining, and chemical processing such as etching.

[0004] In recent years, various improved techniques relating to magnetic domain refinement have been proposed in order to provide grain-oriented electrical steel sheets with good iron loss characteristics (see, for example, Patent Documents 1 to 3).

[0005] JP 2012-57219 A JP 2012-12664 A JP 2012-57218 A

[0006] When magnetic domain control treatment is applied to grain-oriented electrical steel sheet, the magnetostriction characteristics of the grain-oriented electrical steel sheet change due to the closure magnetic domains. This causes the noise characteristics of the grain-oriented electrical steel sheet to deteriorate. The noise characteristics refer to the level of noise generated by electrical products (e.g., transformers, motors, etc.) manufactured using grain-oriented electrical steel sheet as a material. Magnetostriction is a phenomenon in which the external shape of a ferromagnetic material is slightly deformed when it is magnetized. When grain-oriented electrical steel sheet is excited with an alternating current, the magnitude of magnetostriction changes with the change in the strength of the magnetization, causing vibration. The magnitude of this magnetostriction is 10 －６ Although it is on the order of magnitude very small, the magnetostriction generates vibrations in the iron core, which are then transmitted to external structures such as the transformer tank, resulting in noise.

[0007] While magnetic domain control treatment is effective in suppressing iron loss in grain-oriented electrical steel sheets, it also worsens the noise characteristics of grain-oriented electrical steel sheets. In recent years, there has been an increasing demand for grain-oriented electrical steel sheets to not only reduce iron loss but also reduce noise. However, no magnetic domain refining technology has been proposed to date that can achieve both low noise and low iron loss.

[0008] An object of the present disclosure is to provide a grain-oriented electrical steel sheet that can achieve both low iron loss and low noise, and a method for manufacturing the same.

[0009] The gist of the present disclosure is as follows.

[0010] (1) A grain-oriented electrical steel sheet according to one aspect of the present disclosure is a grain-oriented electrical steel sheet having magnetic domain control treatment lines on the surface, wherein |β Ａｌｌ |-|β Ｄｒ |≧0.1°, and |β Ａｌｌ | is the average absolute value of the β angle over the entire surface of the grain-oriented electrical steel sheet, and |β Ｄｒ is the average value of the absolute values ​​of the β angles at magnetic domain control points, which are intersections of the magnetic domain control treatment lines and a plurality of imaginary lines set at 2 mm intervals in parallel along the rolling direction of the grain-oriented electrical steel sheet. (2) Preferably, the grain-oriented electrical steel sheet according to (1) above has |β Ａｌｌ |-|β Ｄｒ (3) Preferably, the grain-oriented electrical steel sheet according to (1) satisfies |β Ａｌｌ|-|β Ｄｒ (4) Preferably, the grain-oriented electrical steel sheet according to (1) satisfies |β Ａｌｌ |-|β Ｄｒ (5) Preferably, the grain-oriented electrical steel sheet according to any one of (1) to (4) above satisfies |β Ａｌｌ |-|β Ｄｒ |>σ Ａｌｌ / 2 and σ Ａｌｌ is the standard deviation of the absolute value of the β angle over the entire surface of the grain-oriented electrical steel sheet. Ｄｒ <σ Ａｌｌ and σ Ａｌｌ is the standard deviation of the absolute value of the β angle over the entire surface of the grain-oriented electrical steel sheet, and σ Ｄｒ is the standard deviation of the absolute value of the β angle at the magnetic domain control point. (7) Preferably, in the grain-oriented electrical steel sheet according to any one of (1) to (6) above, the magnetic domain control treatment line is a thermal strain. (8) Preferably, in the grain-oriented electrical steel sheet according to any one of (1) to (7) above, the magnetic domain control treatment line is a groove. (9) Preferably, in the grain-oriented electrical steel sheet according to (7) above, the maximum value of the tensile strength introduced into the thermal strain at the magnetic domain control treatment line is non-uniform for each measurement point of the tensile strength. (10) Preferably, in the grain-oriented electrical steel sheet according to (9) above, σ ２ (TS ｍ ) > 5.0, and TS ｍ is the tensile strength in MPa induced by the thermal strain measured at each of the plurality of magnetic domain control points, and σ ２ (TS ｍ ) is T.S. ｍ (11) Preferably, in the grain-oriented electrical steel sheet according to (9) or (10) above, TS ｍ（β＜βＤｒ） >TS ｍ（β≧βＤｒ） Satisfying TS ｍ（β＜βＤｒ） is the magnetic domain processing point where the β angle is β Ｄｒis the arithmetic mean value of the maximum tensile strength in MPa introduced by the thermal strain, measured at each of the magnetic domain treatment points less than TS ｍ（β≧βＤｒ） is when the β angle is β Ｄｒ (12) Preferably, in the grain-oriented electrical steel sheet described in (8) above, the maximum value of the groove depth in the magnetic domain control treatment line is non-uniform for each measurement point of the groove. (13) Preferably, in the grain-oriented electrical steel sheet described in (12) above, σ ２ (D ｍ ) > 3.0, and D ｍ is the maximum value of the groove depth in μm at the magnetic domain control point, and σ ２ (D ｍ ) is D ｍ (14) Preferably, in the grain-oriented electrical steel sheet according to (12) or (13), D ｍ（β＜βＤｒ） >D ｍ（β≧βＤｒ） and D ｍ（β＜βＤｒ） is the magnetic domain control point whose β angle is β Ｄｒ is the arithmetic mean value of the maximum depth of the groove in μm measured at each of the magnetic domain control points less than D ｍ（β≧βＤｒ） is when the β angle is β Ｄｒ This is the arithmetic mean value of the maximum values ​​of the depth of the grooves measured at each of the magnetic domain control points in the unit of μm.

[0011] (15) A method for producing 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; and Ａｌｌ |-|β Ｄｒ |≧0.1°, and |β Ａｌｌ | is the average value of the absolute values ​​of the β angles over the entire surface of the grain-oriented electrical steel sheet to which the magnetic domain control treatment has been applied, and |β Ｄｒ| is the average value of the absolute values ​​of the β angles at magnetic domain control points, which are the intersections of multiple virtual lines set at 2 mm intervals in parallel along the rolling direction of the grain-oriented electrical steel sheet to which the magnetic domain control treatment has been applied and magnetic domain control treatment lines formed by the magnetic domain control treatment. (16) Preferably, in the method for producing a grain-oriented electrical steel sheet described in (15) above, a region where the magnetic domain width is equal to or greater than a predetermined value is defined as the magnetic domain control treatment region. (17) Preferably, in the method for producing a grain-oriented electrical steel sheet described in (15) or (16) above, the distribution of the magnetic domain width is derived from the magnetic domain image using a two-dimensional Fourier transform. (18) Preferably, in the method for producing a grain-oriented electrical steel sheet described in (15) or (16) above, the magnetic domain control treatment is applied by irradiation with a laser or an electron beam. (19) Preferably, in the method for producing a grain-oriented electrical steel sheet described in (15) above, the magnetic domain control strength is made non-uniform in the step of applying the magnetic domain control treatment to the magnetic domain control treatment region.

[0012] According to the present disclosure, it is possible to provide a grain-oriented electrical steel sheet that can achieve both low iron loss and low noise, and a method for manufacturing the same.

[0013] 4B is a diagram showing an example of the hardware configuration of an image acquisition device; FIG. 4C is a diagram showing an example of the hardware configuration of an analysis device; FIG. 4D is a diagram showing an example of the configuration of a laser irradiation device; FIG. 4E is a diagram showing an example of the hardware configuration of an image acquisition device; FIG. 4F is a diagram showing an example of the hardware configuration of an analysis device; FIG. 4G is a diagram showing an example of the hardware configuration of an analysis device; FIG. 4H is a diagram showing an example of the hardware configuration of an image acquisition device; FIG. 4H is a diagram showing an example of the hardware configuration of an analysis device; Ａｌｌ1 is an explanatory diagram of imaginary lines VL1 and VL2 set when calculating |. FIG. 2 is a plan view of a grain-oriented electrical steel sheet according to an embodiment of the present disclosure. FIG. 3 is a graph schematically showing the relationship between the size of the magnetic domain width and the magnetic domain control saturation strength. FIG. 4 is a graph schematically showing the relationship between the size of the β angle and the magnetic domain control saturation strength. FIG. 5 is a schematic cross-sectional view of a grain-oriented electrical steel sheet in which the magnetic domain control treatment lines are thermal strain. FIG. 6 is a schematic cross-sectional view of a grain-oriented electrical steel sheet in which the magnetic domain control treatment lines are grooves. FIG. 7 is a schematic plan view illustrating a method for measuring the magnetic domain control strength at the intersection of the magnetic domain control treatment line and the imaginary line when the magnetic domain control treatment line is thermal strain. FIG. 8 is a schematic plan view illustrating a method for measuring the magnetic domain control strength at the intersection of the magnetic domain control treatment line and the imaginary line when the magnetic domain control treatment line is a groove.

[0014] (1. Grain-oriented electrical steel sheet 1) The grain-oriented electrical steel sheet 1 according to this embodiment has magnetic domain control treatment lines 11 on its surface, and |β Ａｌｌ |-|β Ｄｒ |≧0.1° is satisfied. |β Ａｌｌ is the average value of the absolute value of the β angle over the entire surface of the grain-oriented electrical steel sheet 1. Ｄｒ | is the average value of the absolute value of the β angle at the magnetic domain control point VP2, which is the intersection of multiple virtual lines VL3 set parallel to the rolling direction RD of the grain-oriented electrical steel sheet 1 at intervals of 2 mm and the magnetic domain control processing line 11.

[0015] (Magnetic Domain Control Processing Lines 11) The multiple magnetic domain control processing lines 11 provided on the surface of the grain-oriented electrical steel sheet 1 function to subdivide the 180° magnetic domains. Subdividing the magnetic domains can reduce the iron loss of the grain-oriented electrical 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 domain walls of a 180° magnetic domain (domain wall spacing) is referred to as the width of the 180° magnetic domain. Hereinafter, unless otherwise specified, the width of a 180° magnetic domain will be simply referred to as the "magnetic domain width."

[0016] Suitable examples of the magnetic domain control processed wires 11 are thermal distortion and / or grooves. By subdividing the magnetic domains, it is possible to suppress the iron loss of the grain-oriented electrical steel sheet 1. However, the magnetic domain control processed wires 11 change the magnetostriction characteristics of the grain-oriented electrical steel sheet 1 due to closure domains. This deteriorates the noise characteristics of the grain-oriented electrical steel sheet 1.

[0017] The magnetic domain control treatment lines 11 are formed in a direction intersecting the rolling direction RD of the grain-oriented electrical steel sheet 1. In a typical grain-oriented electrical steel sheet 1 such as the one illustrated in Fig. 2, the magnetic domain control treatment lines 11 are formed across the entire width of the grain-oriented electrical steel sheet 1. However, in the grain-oriented electrical steel sheet 1 according to this embodiment as illustrated in Fig. 1, it is not essential to provide the magnetic domain control treatment lines 11 across the entire width of the grain-oriented electrical steel sheet 1. At least some of the magnetic domain control treatment lines 11 are interrupted in regions 12B with large β angles, which will be described later.

[0018] In the grain-oriented electrical steel sheet 1 exemplified in FIG. 1 , the magnetic domain control treatment lines 11 are straight. However, the magnetic domain control treatment lines 11 may also be curved. The magnetic domain control treatment lines 11 may have a shape including straight portions and bent portions. Furthermore, the magnetic domain control treatment lines 11 may be on one or both sides of the grain-oriented electrical steel sheet 1. When the magnetic domain control treatment lines 11 are on both sides of the grain-oriented electrical steel sheet 1, it is sufficient that the various aspects of the grain-oriented electrical steel sheet 1 according to this embodiment are applied to at least one side of the grain-oriented electrical steel sheet 1.

[0019] (β angle) In the grain-oriented electrical steel sheet 1 according to this embodiment, the value |β calculated by measuring the β angle Ａｌｌ | and |β Ｄｒ | satisfies a predetermined relational expression. The β angle is the angle of deviation of a crystal grain from the Goss orientation around the axis of the direction transverse to the rolling direction TD. It is known that controlling the β angle is effective in controlling the magnetic properties of the grain-oriented electrical steel sheet 1. The angle of deviation of a crystal grain from the Goss orientation around the axis of the normal direction ND of the rolling surface is called the α angle, and the angle of deviation of a crystal grain from the Goss orientation around the axis of the rolling direction RD is called the γ angle.

[0020] As shown in Figure 3, in grain-oriented electrical steel sheet 1 (original sheet 2 described later) before magnetic domain control treatment, there is a close relationship between the β angle and the magnetic domain width. Figure 3 is a graph showing an example of the relationship between the β angle and the average value of the magnetic domain width in grain-oriented electrical steel sheet 1 before magnetic domain control treatment. In grain-oriented electrical steel sheet 1 before magnetic domain control treatment, the smaller the β angle, the larger the magnetic domain width. However, the relationship shown in Figure 3 does not hold for grain-oriented electrical steel sheet 1 after magnetic domain control treatment. This is because the magnetic domain control treatment reduces the magnetic domain width in areas where the magnetic domain width was wide before magnetic domain control, but does not change the orientation of the crystal grains (α angle, β angle, γ angle).

[0021] (|β Ａｌｌ |-|β Ｄｒ |) The grain-oriented electrical steel sheet 1 according to this embodiment has |β Ａｌｌ |-|β Ｄｒ |≧0.1° is satisfied. |β Ａｌｌ is the average value of the absolute value of the β angle over the entire surface of the grain-oriented electrical steel sheet 1. Ｄｒ is an index of the β angle in the magnetic domain control processing line 11. Specifically, |β Ｄｒ is the average value of the absolute values ​​of the β angles at the magnetic domain control points VP2, which are the intersections of the magnetic domain control processing lines 11 and multiple imaginary lines VL3 set in parallel at intervals of 2 mm along the rolling direction RD of the grain-oriented electrical steel sheet 1. By averaging the absolute values ​​of the β angles measured at each of the multiple magnetic domain control points VP2, |β Ｄｒ |β Ａｌｌ | and |β Ｄｒ The method for measuring | will be described in detail later.

[0022] Grain-oriented electrical steel sheet 1 is |β Ａｌｌ |-|β Ｄｒ When |≧0.1° is satisfied, the magnetic domain control treatment lines 11 are preferentially provided in the regions 12A where the β angle is small. Generally, a grain-oriented electrical steel sheet 1 has regions 12A where the β angle is small and regions 12B where the β angle is large. In the grain-oriented electrical steel sheet 1 illustrated schematically in FIG. 1 , the magnetic domain control treatment lines 11 are preferentially arranged in the regions 12A where the β angle is small. Therefore, |β Ｄｒ | is the average value of the β angle over the entire surface of the grain-oriented electrical steel sheet 1 |β ＡｌｌOn the other hand, in the normal grain-oriented electrical steel sheet 1 shown in FIG. 2, the magnetic domain control treatment lines 11 are arranged without taking into consideration the distribution of the β angle. Therefore, |β Ｄｒ | is the average value of the β angle over the entire surface of the grain-oriented electrical steel sheet 1 |β Ａｌｌ | is substantially the same value.

[0023] (Basic Principle and Effects) The present inventors have found that |β Ａｌｌ |-|β Ｄｒ It has been found that the grain-oriented electrical steel sheet 1 satisfying | β ≧ 0.1° can achieve both low iron loss and low noise. Ａｌｌ |-|β Ｄｒ This is because, in the grain-oriented electrical steel sheet 1 in which |≧0.1° is satisfied, magnetic domain control processing lines 11 are provided in the regions 12A with small β angles, i.e., regions where the magnetic domain width was wide before the magnetic domain control processing, while the magnetic domain control processing is suppressed in the regions 12B with large β angles, i.e., regions where the magnetic domain width was narrow before the magnetic domain control processing. The basic principles and effects of the present disclosure will be described below with reference to Figures 4A to 4C, etc.

[0024] First, the inventors compared the magnetic domain structure of the grain-oriented electrical steel sheet 1 before and after magnetic domain control treatment. Fig. 4A shows an example of the magnetic domain width distribution of the grain-oriented electrical steel sheet 1 before magnetic domain control treatment. Fig. 4B shows the magnetic domain width distribution after magnetic domain control treatment was performed on the surface of the grain-oriented electrical steel sheet 1 of Fig. 4A. The magnetic domain control treatment here was performed by irradiating the surface with a continuous wave laser in a direction approximately perpendicular to the rolling direction RD. The magnetic domain width distributions shown in Figs. 4A and 4B were derived from magnetic domain images of the grain-oriented electrical steel sheet 1 using a two-dimensional Fourier transform, which will be described later.

[0025] Furthermore, Fig. 4C shows the difference between Fig. 4A and Fig. 4B. Fig. 4C shows the regions where the magnetic domain width has been subdivided by 50 μm or more before and after the magnetic domain control process shown in Fig. 4A and Fig. 4B. Fig. 4C visualizes the regions where the magnetic domain width has been subdivided by the magnetic domain control process.

[0026] 4C shows that the regions where magnetic domain refining of 50 μm or more has occurred as a result of the magnetic domain control treatment are the dark areas in FIG. 4A, i.e., regions where the magnetic domain width was wide before the magnetic domain control treatment. It can be seen that the magnetic domain refining effect is particularly pronounced in regions where the original magnetic domain width was approximately 500 μm or more. On the other hand, the effect of the magnetic domain control treatment is hardly apparent in the light areas in FIG. 4A, i.e., regions where the magnetic domain width was narrow before the magnetic domain control treatment. The effect of the magnetic domain control treatment differs depending on the magnetic domain width before the magnetic domain control treatment.

[0027] The present inventors further investigated in detail the relationship between the amount of reduction in magnetic domain width caused by the magnetic domain control treatment and the magnetic domain width before the magnetic domain control treatment. Figure 5 shows the relationship between the magnetic domain width before the magnetic domain control treatment and the magnetic domain width before the magnetic domain control treatment at the same position. The magnetic domain control treatment was performed by laser irradiation. During the laser irradiation, the average irradiation energy density Ua (mJ / mm ２ ), and irradiation pitch PL (mm), respectively, Ua = 1.5 mJ / mm ２ , PL=4 mm.

[0028] 5, it can be seen that the magnetic domain refinement effect of the magnetic domain control treatment is difficult to achieve in regions with narrow magnetic domain widths. In particular, in regions with magnetic domain widths of approximately 500 μm or less, the magnetic domain widths were substantially the same before and after the magnetic domain control treatment. Therefore, the iron loss reduction effect of the magnetic domain control treatment is significant in regions where the magnetic domain width before the magnetic domain control treatment was wide, but is not sufficiently achieved in regions where the magnetic domain width before the magnetic domain control treatment was narrower than a predetermined value. It is believed that magnetic domain control treatment lines 11 formed in regions where the magnetic domain width is narrower than a predetermined value will cause deterioration in noise characteristics due to closure domains.

[0029] Based on the above findings, it has become clear that in the magnetic domain control treatment of conventional grain-oriented electrical steel sheets 1, magnetic domain control is performed even in areas where magnetic domain control is not required, which contributes to increased noise. It has also been found that performing magnetic domain control treatment preferentially in areas with wide magnetic domain widths is extremely effective in achieving both low iron loss and low noise. Magnetic domain control treatment in areas with wide magnetic domain widths can reduce iron loss. Furthermore, by minimizing magnetic domain control treatment in areas with narrow magnetic domain widths, it is possible to prevent deterioration of noise characteristics.

[0030] 3, there is a close relationship between the magnetic domain width before the magnetic domain control process and the β angle. The region 12A with a small β angle is approximately the same as the region with a wide magnetic domain width before the magnetic domain control process. Therefore, the magnetic domain control process line 11 is preferentially provided in the region 12A with a small β angle, and |β Ａｌｌ |-|β Ｄｒ A grain-oriented electrical steel sheet 1 that satisfies |≧0.1° is a grain-oriented electrical steel sheet 1 in which magnetic domain control treatment has been preferentially performed on regions with wide magnetic domain widths. Ａｌｌ |-|β Ｄｒ The grain-oriented electrical steel sheet 1 that satisfies |≧0.1° can achieve both low iron loss and low noise by performing magnetic domain control treatment preferentially on regions with wide magnetic domain widths.

[0031] The above has described the most basic aspect of the grain-oriented electrical steel sheet 1 according to this embodiment. A more preferred aspect will now be described.

[0032] (|β Ａｌｌ |-|β Ｄｒ Preferred numerical range of | Ａｌｌ |-|β Ｄｒ From the viewpoint of improving noise characteristics, it is preferable that | is larger. Ａｌｌ |-|β Ｄｒ It is more preferable that | is, for example, 0.2° or more, 0.5° or more, or 1.0° or more. Ａｌｌ |-|β Ｄｒ |≧0.2°, |β Ａｌｌ |-|β Ｄｒ |≧0.5°, or |β Ａｌｌ |-|βＤｒ It is more preferable that |≧1.0° is satisfied, as this achieves a further improvement in noise characteristics.

[0033] |β Ａｌｌ |-|β Ｄｒ The upper limit of | is not particularly limited, but for example, |β Ａｌｌ |-|β Ｄｒ | may be 5.0° or less, 4.0° or less, or 3.0° or less.

[0034] (|β Ａｌｌ |-|β Ｄｒ | and σ Ａｌｌ The grain-oriented electrical steel sheet 1 preferably has a relationship of |β Ａｌｌ |-|β Ｄｒ |>σ Ａｌｌ / 2 is satisfied. σ Ａｌｌ is the standard deviation of the absolute value of the β angle over the entire surface of the grain-oriented electrical steel sheet 1. The β angle measured on the surface of the grain-oriented electrical steel sheet 1 varies. The index of the variation of the β angle is σ Ａｌｌ |β Ａｌｌ |-|β Ｄｒ | is σ Ａｌｌ When the β angle is greater than 2, this indicates that the region to which the magnetic domain control treatment is applied is selectively determined by the β angle. Since the magnetic domain control treatment is applied intensively to the region where the magnetic domain width before the magnetic domain control is wide and where the iron loss reduction effect is large, further improvement in noise characteristics is achieved.

[0035] (σ Ｄｒ and σ Ａｌｌ The grain-oriented electrical steel sheet 1 preferably has a relationship of σ Ｄｒ <σ Ａｌｌ Satisfies σ Ａｌｌ is the standard deviation of the absolute value of the β angle over the entire surface of the grain-oriented electrical steel sheet 1, and σ Ｄｒ is the standard deviation of the absolute value of the β angle at the magnetic domain control points VP2, which are the intersections of the magnetic domain control treatment lines 11 and multiple imaginary lines VL3 set in parallel at intervals of 2 mm along the rolling direction RD of the grain-oriented electrical steel sheet 1. Ｄｒ <σ ＡｌｌIn the grain-oriented electrical steel sheet 1 that satisfies the above requirement, the variation in the β angle at the magnetic domain control point VP2 is smaller than the variation in the β angle overall in the grain-oriented electrical steel sheet 1. That is, in this case, the magnetic domain control treatment is concentrated on the region where the magnetic domain width before the magnetic domain control is wide and where the iron loss reduction effect is large, thereby achieving a further improvement in noise characteristics.

[0036] (Mode of magnetic domain control processing line 11) The type of magnetic domain control processing line 11 is not particularly limited, but suitable examples are thermal distortion and grooves. Thermal distortion can be formed by means of, for example, laser irradiation, electron beam irradiation, ion implantation, etc. Grooves can be formed by means of, for example, laser irradiation, electron beam irradiation, machining, etc.

[0037] Thermal distortion disappears by stress relief annealing or a heat treatment equivalent thereto. Therefore, when the grain-oriented electrical steel sheet 1 is heat treated, it is preferable to form the magnetic domain control treatment lines 11 as grooves. On the other hand, since thermal distortion can be easily formed, when simplification of the manufacturing process is required, it is preferable to form the magnetic domain control treatment lines 11 as thermal distortion. The grain-oriented electrical steel sheet 1 may have both thermal distortion and grooves.

[0038] In this embodiment, the magnetic domain control strength is preferably determined according to the magnetic domain width of the grain-oriented electrical steel sheet before the magnetic domain control treatment, which is the amount of thermal strain when the magnetic domain control method is thermal strain, or the groove depth when the magnetic domain control method is grooves.

[0039] The stronger the magnetic domain control strength, the greater the effect of subdividing the magnetic domains. On the other hand, the stronger the magnetic domain control strength, the more likely it is to lead to an increase in hysteresis loss and a deterioration in noise characteristics. Furthermore, according to the new findings of the inventors, the magnetic domain control saturation strength is not uniform in grain-oriented electrical steel sheets.

[0040] The magnetic domain control saturation strength is the magnetic domain control strength at which the effect of dividing the magnetic domains substantially saturates. When 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. However, when the magnetic domain control strength exceeds the magnetic domain control saturation strength, increasing the magnetic domain control strength hardly improves the iron loss reduction effect. On the other hand, even when 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. 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.

[0041] The inventors also found that the magnetic domain control saturation strength has a strong correlation with the β angle. The magnetic domain control saturation strength is high where the β angle is small. Furthermore, in grain-oriented electrical steel sheets before magnetic domain control treatment, there is also a correlation between the β angle and the magnetic domain width. In grain-oriented electrical steel sheets before magnetic domain control treatment, the larger the β angle, the narrower the magnetic domain width. However, in grain-oriented electrical steel sheets after magnetic domain control treatment, the correlation between the magnetic domain width and the β angle becomes weaker. This is because the magnetic domain control treatment changes the magnetic domain width but does not change the β angle.

[0042] Therefore, it is preferable to select an optimal magnetic domain control strength depending on the magnetic domain width or β angle. Specifically, it is preferable to perform magnetic domain control treatment with a high magnetic domain control strength in areas where the magnetic domain width is large and the β angle is small, and to perform magnetic domain control treatment with a low magnetic domain control strength in areas where the magnetic domain width is small and the β angle is large. Furthermore, as described above, magnetic domain control treatment is not performed in areas where the original magnetic domain width is narrower than a predetermined value. This results in a grain-oriented electrical steel sheet with non-uniform magnetic domain control strength. In such a grain-oriented electrical steel sheet, the iron loss of the grain-oriented electrical steel sheet after magnetic domain control is further reduced. Meanwhile, 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.

[0043] FIG. 15 shows a graph that schematically illustrates a method for determining the magnetic domain control strength based on the magnetic domain width. The vertical axis of FIG. 15 represents the magnetic domain control strength, and the horizontal axis represents the magnetic domain width. The solid line in FIG. 15 represents the magnetic domain control saturation strength. In regions where the magnetic domain width is narrow, the magnetic domain control effect is not obtained, and the magnetic domain control saturation strength is 0. For example, in regions where the magnetic domain width exceeds 500 μm, the magnetic domain control effect is obtained. Furthermore, in regions where the magnetic domain width exceeds 500 μm, the magnetic domain control saturation strength increases as the magnetic domain width increases. Furthermore, for example, in regions where the magnetic domain width exceeds approximately 1200 μm, the magnetic domain control saturation strength becomes approximately constant. Here, the region where the magnetic domain control effect is obtained is not limited to regions exceeding 500 μm. The region where the magnetic domain control saturation strength becomes approximately constant is not limited to regions exceeding approximately 1200 μm. These regions vary depending on various conditions.

[0044] FIG. 16 shows a graph that schematically illustrates a method for determining the magnetic domain control strength based on the β angle. The vertical axis of FIG. 16 represents the magnetic domain control strength, and the horizontal axis represents the magnitude of the β angle. The solid line graph in FIG. 16 represents the magnetic domain control saturation strength. In regions where the β angle is large, the effect of magnetic domain control is not obtained, so the magnetic domain control saturation strength is 0. In regions where the β angle is below a predetermined value, the effect of magnetic domain control is obtained. For example, when the β angle is 2.0° or less, it is estimated that the effect of magnetic domain control is obtained. In regions where the β angle is below a predetermined value, the larger the β angle, the greater the magnetic domain control saturation strength. In regions where the β angle is even smaller, the magnetic domain control saturation strength is approximately constant.

[0045] It is most preferable that 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 11. Alternatively, it is most preferable that the relationship between the β angle at the location where magnetic domain control is performed and the magnetic domain control strength is on the solid line graph in Figure 16. The magnetic domain control saturation strength can be used as a target value for the magnetic domain control strength.

[0046] Furthermore, there is a minimum magnetic domain control strength, which is the minimum strength at which the magnetic domain control effect is exhibited. When magnetic domain control is performed, it is more preferable that the magnetic domain control strength is equal to or greater than the minimum magnetic domain control strength.

[0047] However, the magnetic domain control strength may vary slightly from the target value of the magnetic domain control saturation strength. In Figures 15 and 16, the region that is equal to or greater than the minimum magnetic domain control strength and that is within a certain range of the graph of the magnetic domain control saturation strength is referred to as the target range of the magnetic domain control strength. It is preferable that the magnetic domain control strength and the magnetic domain width of the magnetic domain control target portion are within the shaded region surrounded by dashed lines in Figures 15 and 16.

[0048] This results in a grain-oriented electrical steel sheet with non-uniform magnetic domain control strength. In such grain-oriented electrical steel sheets, the magnetic domain control strength varies depending on the β angle. In such grain-oriented electrical steel sheets, the iron loss of the grain-oriented electrical steel sheet after magnetic domain control is further reduced. Meanwhile, 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.

[0049] The multiple magnetic domain control treatment lines 11 provided on the surface of the grain-oriented electrical steel sheet 1 may be straight as shown in Fig. 1 or curved as shown in Fig. 14. If the multiple magnetic domain control treatment lines 11 provided on the surface of the grain-oriented electrical steel sheet 1 are curved, the degree of freedom in the magnetic domain control treatment is improved, making it easier to selectively perform magnetic domain control treatment only on areas with small β angles, and improving the performance of the grain-oriented electrical steel sheet 1, which is preferable.

[0050] (2. Manufacturing Apparatus for Manufacturing Grain-Oriented Electrical Steel Sheet 1) Next, an example of a manufacturing apparatus for the grain-oriented electrical steel sheet 1 according to this embodiment will be described. However, the manufacturing apparatus described below is merely illustrative. The grain-oriented electrical steel sheet 1 according to this embodiment can be manufactured using any apparatus.

[0051] 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 electrical 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.

[0052] The light source unit 31 has a light source made up of a light emitting diode (LED), and irradiates the MO sensor 33 with light having a uniform polarization plane.

[0053] The MO sensor 33 is a device for measuring the magnetic domain structure of a magnetic material. The MO sensor 33 has an observation surface on which a magnetic sample to be measured is placed. Light emitted from the light source unit 31 passes through the interior of the MO sensor 33 and is reflected by the reflective layer. The reflected light passes through the interior of the MO sensor 33 again and is output to the outside of the MO sensor 33. When the original plate 2, which is a magnetic sample, is placed on the observation surface 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.

[0054] The image sensor 35 is a complementary metal-oxide-semiconductor (CMOS) image sensor. The image sensor 35 forms an image of the reflected light from the MO sensor 33 on its light-receiving surface, performs photoelectric conversion, and outputs the photoelectrically converted analog signal to a signal processing unit 37. By detecting the reflected light with a rotated polarization plane using the image sensor 35, the distribution of the leakage magnetic field can be obtained, and the magnetic domain structure of the original plate 2 can be clarified.

[0055] The signal processing unit 37 includes 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. This digital signal is subjected to predetermined digital processing using the DSP to generate an image signal. The image signal generated by the signal processing unit 37 is output to an analysis device 40 (see FIG. 7 ) via a cable or wireless communication.

[0056] 7 shows the hardware configuration of an analysis device 40 that analyzes the magnetic domain structure of the original sheet 2. The analysis device 40 is a computer device such as a personal computer (PC), and includes a calculation unit 41, a memory 43, a display unit 45, an input unit 47, and a communication I / F 49.

[0057] 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 sheet 2 in accordance with a program stored in the memory 43. The calculation unit 41 then determines the magnetic domain control processing region 21, which is the location where the magnetic domain control processing is to be applied. The processing executed by the calculation unit 41 will be described in detail later.

[0058] The memory 43 includes 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 necessary for executing these programs. The programs and data stored in the ROM are loaded into the RAM and executed.

[0059] The memory 43 may include a magnetic memory such as a hard disk drive (HDD) or an optical memory such as an optical disk. Alternatively, the memory 43 may store programs and data in a computer-readable recording medium that is detachable from the analysis device 40. Alternatively, the memory 43 may receive the programs executed by the calculation unit 41 from a network via the communication I / F 49.

[0060] 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.

[0061] The input unit 47 has input devices such as a mouse, a keyboard, etc. 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.

[0062] As the calculation unit 41, instead of general-purpose hardware such as a CPU, dedicated hardware such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA) specialized for analyzing magnetic domain structures may be adopted.

[0063] Although FIGS. 6 and 7 show the 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 employed.

[0064] Known means such as laser irradiation, electron beam irradiation, ion implantation, etc. can be used as a means for introducing thermal strain into the surface of the original plate 2. Known means such as laser irradiation, electron beam irradiation, mechanical processing, etc. can be used as a means for forming grooves in the surface of the original plate 2. The configuration of a laser irradiation device 500 that introduces thermal strain by laser irradiation will be described below.

[0065] 8 shows the configuration of the laser irradiation device 500. The laser irradiation device 500 includes a polygon mirror 501, a light source device 503, a collimator 505, a condenser lens 507, a motor 509, a sensor 511, a control unit 513, and a strip threading device 515.

[0066] The strip threading device 515 threads the original strip 2 in the rolling direction RD.

[0067] The polygon mirror 501 has, for example, a regular polygonal prism shape. A plurality of plane mirrors are provided on each of the plurality of side surfaces constituting the regular polygonal prism-shaped polygon mirror 501. A laser beam LB is emitted from a light source device 503, passes through a collimator 505, and is incident on the plane mirror of the polygon mirror 501 in one direction (horizontal direction) and is reflected by the plane mirror.

[0068] The polygon mirror 501 can be rotated around a 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, enabling scanning of the surface of the original plate 2. The symbol P in Figure 8 represents the interval between adjacent magnetic domain control processing lines 11, i.e., the irradiation pitch of the laser beam LB.

[0069] The light source device 503 outputs a laser beam LB in a predetermined irradiation method (for example, a continuous irradiation method or a pulse irradiation method) under the control of the control unit 513 .

[0070] 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 condensing optical system with a predetermined focal length. The laser beam LB reflected from the polygon mirror 501 is condensed onto the surface of the original plate 2 via the condenser lens 507, thereby introducing thermal strain into the surface of the original plate 2.

[0071] The motor 509 is connected to the polygon mirror 501. The motor 509 drives the polygon mirror 501 to rotate under the control of the control unit 513.

[0072] 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 a rotation angle signal) to the control unit 513.

[0073] The control unit 513 is made up of a processor. The control unit 513 is connected to the light source device 503, the motor 509, the sensor 511, and the strip threading device 515. The control unit 513 receives a speed signal from the strip threading device 515. The control unit 513 also outputs a signal to the motor 509 to instruct the motor 509 to rotate the polygon mirror 501.

[0074] Furthermore, the control unit 513 controls the power of the laser beam LB output by the light source device 503 to be turned on and off based on a stress introduction signal representing the magnetic domain control processing region 21 and a rotation angle signal output from the sensor 511. When the laser irradiation device 500 is electrically connected to the analysis device 40, the stress introduction signal is input from the analysis device 40 to the laser irradiation device 500. Note that the stress introduction signal may also be input to the laser irradiation device 500 by an operator.

[0075] (3. Manufacturing Method of Grain-Oriented Electrical Steel Sheet 1) Next, a manufacturing method of the grain-oriented electrical steel sheet 1 according to this embodiment will be described. According to the manufacturing method of the grain-oriented electrical steel sheet 1 according to this embodiment, the grain-oriented electrical steel sheet 1 according to this embodiment can be suitably manufactured. However, the manufacturing method described below is merely one example of a suitable manufacturing method of the grain-oriented electrical steel sheet 1, and does not limit the grain-oriented electrical steel sheet 1. For ease of explanation, manufacturing equipment will be referred to as appropriate in the description of the manufacturing method. However, the manufacturing equipment referred to below is merely a suitable example for carrying out the manufacturing method of the grain-oriented electrical steel sheet 1 according to this embodiment.

[0076] As shown in the flowchart of Figure 9, the manufacturing method of the grain-oriented electrical steel sheet 1 according to this embodiment includes step S62 of acquiring a magnetic domain image of the original sheet 2 of the grain-oriented electrical steel sheet 1, step S64 of determining a magnetic domain control processing area 21 based on the distribution of magnetic domain widths in the magnetic domain image, and step S66 of applying magnetic domain control processing to the magnetic domain control processing area 21 determined based on the distribution of magnetic domain widths.

[0077] First, a magnetic domain image of the original sheet 2 is acquired (see S62 in FIG. 9 ). The original sheet 2 refers to the grain-oriented electrical steel sheet 1 before the magnetic domain control process is applied. The magnetic domain image can be acquired, for example, by the image acquisition device 30. Next, the distribution of the widths of the 180° magnetic domains (magnetic domain widths) 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.

[0078] Then, regions where the magnetic domain width is equal to or greater than a predetermined value (for example, equal to or greater than about 500 μm) are determined as magnetic domain control processing regions 21 (see S64 in FIG. 9 ). Note that the regions in the original sheet 2 where the magnetic domain width is equal to or greater than the predetermined value correspond to the regions 12A in the grain-oriented electrical steel sheet 1 where the β angle is small.

[0079] The magnetic domain control processing region 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 region 21 may be input to the laser irradiation device 500.

[0080] Next, the magnetic domain control treatment is preferentially performed on the magnetic domain control treatment region 21 (see S66 in FIG. 9). Preferably, the magnetic domain control treatment is performed only on the magnetic domain control treatment region 21. If the magnetic domain control treatment line 11 is a thermal distortion, the magnetic domain control treatment may be performed by irradiation with a laser beam LB by a laser irradiation device 500, or other means such as ion implantation or electron beam irradiation may be employed. If the magnetic domain control treatment line 11 is a groove, the magnetic domain control treatment may be performed using a machining tool.

[0081] A detailed description will be given of an example of a method for determining the magnetic domain control processing area 21. The processing for identifying the magnetic domain control processing area 21 is executed by the calculation unit 41 of the analysis device 40, for example.

[0082] The calculation unit 41 uses, for example, a line segment method or a Fourier transform to derive the distribution of the magnetic domain width of the original sheet 2. Then, the calculation unit 41 determines regions where the magnetic domain width is equal to or greater than a predetermined value (for example, equal to or greater than approximately 500 μm) as locations where the magnetic domain control process should be applied preferentially.

[0083] In the line segment method, evaluation is performed by drawing line segments perpendicular to the magnetic domains. The line segments are drawn at intervals of three per centimeter in the direction parallel to the magnetic domains. The magnetic domain width is calculated based on the intervals between the intersections of the 180° domain walls and the line segments.

[0084] The Fourier transform is particularly effective as a means for analyzing the magnetic domain structure of a magnetic material having a periodic magnetic domain structure, such as the grain-oriented electrical steel sheet 1 and the original sheet 2. Below, we will explain a method for deriving the distribution of the magnetic domain width of the original sheet 2 using the short-term two-dimensional Fourier transform (hereinafter referred to as "ST2DFT"), which is an extension of the short-term Fourier transform, a signal processing method that has long been used in the time-frequency analysis of audio signals, to a two-dimensional region.

[0085] 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, such as grayscale, or an image expressed in three or more gradations (multi-gradation).

[0086] In order to derive the distribution of magnetic domain widths of the original sheet 2, the calculation unit 41 executes the following processes (A-1), (A-2), and (A-3): (A-1) Process of extracting multiple partial regions from the magnetic domain image; (A-2) Process of performing ST2DFT; (A-3) Process of deriving the distribution of magnetic domain widths. Processes A-1 to A-3 will be explained in detail below.

[0087] (A-1) Processing for extracting multiple partial regions from a magnetic domain image In order to extract multiple partial regions from a magnetic domain image and analyze the frequency structure of each partial region, the range in the k direction is set to 0≦k≦N. ｋ -1, and the range in the l direction is 0≦l≦N ｌ -1 is used as the rectangular window function Wa(k, l) (N ｋ and N ｌ (k, l is a natural number). As the window function Wa(k, l), a Hamming window, a Hanning window, a Blackman window, etc. can be applied.

[0088] The observation position in the data sequence x(k, l) of the magnetic domain image is expressed by an index (n, m), and the shift amounts of the window function Wa(k, l) in the k direction and the l direction are respectively expressed as S ｋ and S ｌ When written as (n, m, S ｋ , S ｌ is an integer), and nS is calculated from the magnetic domain image as in equation (1). ｋ ≦k≦nS ｋ +N ｋ -1, mS ｌ ≦l≦mS ｌ +N ｌ Data string x of the partial region cut out from the range of -1 ｎｍ (k-nS ｋ , l-mS ｌ ) is obtained.

[0089] Figure 10 shows an example in which partial regions corresponding to the observation positions (n, m) = (1, 1), (2, 2), (3, 3), ..., (P, Q) (P and Q are natural numbers) are cut out from the magnetic domain image G.

[0090] In this embodiment, N which determines the range of the window function Wa(k, l) ｋ and N ｌare parameters corresponding to the number of pixels in the k direction and the number of pixels in the l direction in the partial region, respectively.

[0091] (A-2) Processing to perform ST2DFT The data sequence of the partial region is x ｎｍ (n', m') = x ｎｍ (k-nS ｋ , l-mS ｌ ) and x ｎｍ When a two-dimensional Fourier transform is performed on (n', m'), a partial Fourier image X(f ｋ , f ｌ , n, m) are obtained. where f ｋ and f ｌ is the spatial frequency.

[0092] spatial frequency f ｋ The resolution of Δf ｋ , spatial frequency f ｌ The resolution of Δf ｌ When written as Δf ｋ and Δf ｌ is defined as in equation (3). Here, Δk and Δl are the spatial resolutions in the k and l directions, respectively, of the magnetic domain image.

[0093] For example, the data string x of each partial region shown in FIG. ｎｍ (k-nS ｋ , l-mS ｌ ) is subjected to a two-dimensional Fourier transform, a partial Fourier image X(f ｋ , f ｌ , n, m) are obtained.

[0094] (A-3) Processing to derive the distribution of magnetic domain widths Partial Fourier image X(f ｋ , f ｌ , n, m) is obtained, the partial Fourier image X(f ｋ , f ｌ , n, m) ｋ ｍａｘ (n, m) and l component f ｌ ｍａｘ(n, m)) can be obtained. Note that, in deriving the peak position, the region near k=0, l=0 is excluded because it is a portion that is highly dependent on the contrast of the image.

[0095] Then, from the spatial frequency resolution defined by equation (3) and the peak positions of the spots in the partial Fourier image, the distribution L(n, m) of the magnetic domain width is derived as shown in equation (4).

[0096] In this way, by using ST2DFT, it is possible to quantitatively derive the magnetic domain width distribution L(n, m) while preserving the position information of the magnetic domain image. Figures 4A to 4C above show the analysis results of the magnetic domain width derived by ST2DFT.

[0097] Fig. 12 shows a plan view of an example of the original sheet 2. Fig. 12 shows a magnetic domain control processed region 21 and a non-magnetic domain control processed region 22 of the original sheet 2 identified based on the magnetic domain image. The magnetic domain control processed region 21 of the original sheet 2 roughly corresponds to the region 12A with a small β angle in the grain-oriented electrical steel sheet 1. The non-magnetic domain control processed region 22 of the original sheet 2 roughly corresponds to the region 12B with a large β angle in the grain-oriented electrical steel sheet 1. The magnetic domain control process is applied to the dashed lines shown in Fig. 12.

[0098] When the calculation unit 41 derives the magnetic domain width distribution L(n, m), the calculation unit 41 determines regions where the magnetic domain width is equal to or greater than a predetermined value as magnetic domain control processing regions 21 (i.e., regions to which magnetic domain control processing is applied). The control unit 513 of the laser irradiation device 500 controls the power of the laser beam LB to be on for the magnetic domain control processing regions 21, and preferably to be off for the non-magnetic domain control processing regions 22 (i.e., regions other than the magnetic domain control processing regions 21). This introduces magnetic domain control processing lines 11 into the magnetic domain control processing regions 21 of the original sheet 2. Furthermore, the introduction of magnetic domain control processing lines 11 is minimized in the non-magnetic domain control processing regions 22 of the original sheet 2.

[0099] The above-described procedure can also be used to obtain a magnetic domain image of the grain-oriented electrical steel sheet 1 after the magnetic domain control treatment. In the magnetic domain image of the grain-oriented electrical steel sheet 1, the magnetic domain control treatment lines 11 may be unclear. In this case, the observation conditions may be adjusted so that the magnetic domain control treatment lines 11 can be clearly seen. For example, the magnetic domain control treatment lines 11 can be made clear by applying a DC magnetic field in the direction perpendicular to the sheet surface (thickness direction) of the grain-oriented electrical steel sheet 1.

[0100] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited thereto and can be modified as appropriate without departing from the technical spirit thereof. Below, more preferred examples of the grain-oriented electrical steel sheet 1 according to the present embodiment and the manufacturing method thereof will be described. Unless otherwise specified, the preferred aspects described below are applicable to both the grain-oriented electrical steel sheet 1 and the manufacturing method thereof. The grain-oriented electrical steel sheet 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 below. Each of these will be described below. However, when the grain-oriented electrical steel sheet has a base steel sheet and a forsterite coating and / or an insulating coating, the following specifications regarding the chemical composition, magnetic domain control treatment line, magnetic domain control region, and non-magnetic domain control treatment line apply to the base steel sheet. However, the specifications regarding the sheet thickness apply to the entire grain-oriented electrical steel sheet, including the base steel sheet and the forsterite coating and / or the insulating coating.

[0101] (Chemical Composition and Sheet Thickness) The chemical composition of the grain-oriented electrical steel sheet 1 and the base sheet 2 is not limited, and may be the same as that of a known grain-oriented electrical steel sheet 1. For example, the grain-oriented electrical steel sheet 1 and the base sheet 2 may have the following chemical composition, in mass %, 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 0.300%, and the like. : 0-0.300%, Ni: 0-1.000%, S: 0-0.015%, Se: 0-0.015%, Bi: 0-0.020%, Nb: 0-0.030%, V: 0-0.030%, Mo: 0-0.030%, Ta: 0-0.030%, W: 0-0.030%, B: 0-0.080%, Ti: 0-0.015%. The balance of the chemical composition includes Fe and impurities.

[0102] The thickness of the grain-oriented electrical steel sheet 1 and the base sheet 2 is not limited, but is preferably 0.15 to 0.30 mm, for example. By setting the thickness to 0.30 mm or less, classical eddy current loss can be suppressed and iron loss can be further improved. On the other hand, by setting the thickness to 0.15 mm or more, rolling efficiency can be improved, thereby improving productivity.

[0103] (Surface Treatment) The grain-oriented electrical steel sheet 1 and the base sheet 2 may have a forsterite coating. The grain-oriented electrical steel sheet 1 and the base sheet 2 may also 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.

[0104] The forsterite coating is an inorganic coating containing, for example, magnesium silicate as a main component. The forsterite coating is formed, for example, during finish 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. The forsterite coating has a composition derived from the components of the annealing separator and the base steel sheet (more specifically, Mg ２ SiO ４ On the other hand, in the final annealing, ２ O ３When an annealing separator containing mainly SiO 2 is used, the forsterite film may not be formed.

[0105] The insulating coating has the function of imparting electrical insulation and tension to the grain-oriented electrical steel sheet 1. By applying tension to the grain-oriented electrical steel sheet 1 and facilitating domain wall movement in the grain-oriented electrical steel sheet 1, it is possible to reduce iron loss in the grain-oriented electrical steel sheet 1. The insulating coating also provides the grain-oriented electrical steel sheet 1 with various properties such as corrosion resistance, heat resistance, and slip resistance. The insulating coating may be a known coating formed, for example, by applying a coating solution containing phosphate and colloidal silica as main components to the surface of a forsterite coating and baking it.

[0106] The insulating coating is preferably formed after the final annealing and the magnetic domain control treatment. Alternatively, 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 an insulating coating again on the magnetic domain control treatment wire 11 after the magnetic domain control treatment.

[0107] (Angle Between Magnetic Domain Control Processing Line 11 and the Direction Orthogonal to Rolling TD) The angle between the magnetic domain control processing line 11 and the direction orthogonal to rolling TD is not particularly limited. The magnetic domain control processing line 11 and the direction orthogonal to rolling TD may be approximately parallel. That is, the angle between the magnetic domain control processing line 11 and the direction orthogonal to rolling TD may be substantially 0°. On the other hand, as exemplified in FIG. 1 , the angle between the magnetic domain control processing line 11 and the direction orthogonal to rolling TD may be greater than 0°. For example, the angle between the magnetic domain control processing line 11 and the direction orthogonal to rolling TD may be any value within the range of 0° to 45°. The angle between the magnetic domain control processing line 11 and the direction orthogonal to rolling TD may be 1° or more, 3° or more, or 5° or more. The angle formed by the magnetic domain control processing line 11 and the direction perpendicular to the rolling direction TD may be 40° or less, 35° or less, or 30° or less.

[0108] As exemplified in Fig. 1 , the angles formed by all the magnetic domain control processing lines 11 and the direction transverse to rolling TD may be the same. That is, all the magnetic domain control processing lines 11 may extend parallel to one another. On the other hand, the angles formed by the magnetic domain control processing lines 11 and the direction transverse to 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 transverse to rolling TD may be 1° or more, 3° or more, or 5° or more. The average value of the angles formed by the magnetic domain control processing lines 11 and the direction transverse to rolling TD may be 40° or less, 35° or less, or 30° or less. The average angle can be calculated by measuring the angle between one magnetic domain control processing line and the direction perpendicular to the rolling direction TD at multiple positions, or by measuring the angles between multiple magnetic domain control processing lines and the direction perpendicular to the rolling direction TD at one point or multiple positions and then calculating the average value.

[0109] (Spacing of magnetic domain control treatment lines 11 along the rolling direction RD) The spacing P along the rolling direction RD between adjacent magnetic domain control treatment lines 11 along the rolling direction RD is not particularly limited. The smaller the spacing P, the greater the effect of improving iron loss. On the other hand, the larger the spacing P, the more improved the noise characteristics. The spacing can be selected appropriately depending on the characteristics required of the grain-oriented electrical steel sheet 1. For example, the spacing P along the rolling direction RD between adjacent magnetic domain control treatment lines 11 along the rolling direction RD 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 along the rolling direction RD between adjacent magnetic domain control treatment lines 11 along the rolling direction RD may be 10.0 mm or less, 9.0 mm or less, 8.0 mm or less, or 7.0 mm or less.

[0110] In the grain-oriented electrical steel sheet 1 illustrated in Fig. 1 , the magnetic domain control treatment lines 11 are provided at regular intervals. However, the spacing P along the rolling direction RD between adjacent magnetic domain control treatment lines 11 may vary. For example, the average value of the spacing P along the rolling direction RD between adjacent magnetic domain control treatment lines 11 along the rolling direction RD 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 along the rolling direction RD between adjacent magnetic domain control treatment lines 11 along the rolling direction RD may be 10.0 mm or less, 9.0 mm or less, 8.0 mm or less, or 7.0 mm or less.

[0111] (Magnitude of tensile stress introduced by thermal strain) The magnetic domain control treatment wire 11 may be thermally strained. In the thermal strain, 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 improved the noise characteristics. The tensile stress can be appropriately selected according to the characteristics required of the grain-oriented electrical steel sheet 1.

[0112] 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. If the tensile stress in at least one direction is 40 MPa or more, the requirement of "tensile stress in any direction is 40 MPa or more" is considered to be met. Furthermore, 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.

[0113] (Groove Depth and Width) The magnetic domain control treatment line 11 may be a groove. The greater the groove depth and width, the greater the effect of improving iron loss. On the other hand, the smaller the groove depth and width, the more the noise characteristics are improved. The shape of the groove can be selected appropriately depending on the characteristics required of the grain-oriented electrical steel sheet 1.

[0114] The depth of the groove is not particularly limited, but is preferably 5 μm to 50 μm, for example. The depth of the groove may be 6 μm or more, 7 μm or more, or 10 μm or more. The depth of the groove may be 48 μm or less, 45 μm or less, or 40 μm or less.

[0115] The width of the groove is not particularly limited, but is preferably 10 μm to 300 μm, for example. The width of the groove may be specified as 20 μm or more, 30 μm or more, or 50 μm or more. The width of the groove may be specified as 280 μm or less, 250 μm or less, or 200 μm or less. The depth and width of the groove may be uniform or may vary. If there is variation, it is preferable that the average depth and width of multiple grooves be within the above range.

[0116] (Number of magnetic domain control points) The more magnetic domain control points there are, the more magnetic domain control processing lines there are, and the wider the magnetic domain control processed area. Therefore, from the viewpoint of iron loss reduction, it is preferable to have a large number of magnetic domain control points. For example, when the number of magnetic domain control points in the grain-oriented electrical steel sheet 1 is 10,000 mm ２ Preferably, the score is 10 or more, 50 or more, or 100 or more.

[0117] (Measurement Method) Hereinafter, a method for measuring various parameters of the grain-oriented electrical steel sheet 1 according to this embodiment will be described. Note that all parameters are measured on a sample taken from the grain-oriented electrical steel sheet 1. For example, a rectangular sample with both sides measuring 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 on the coil. Also, when the grain-oriented electrical steel sheet 1 is a component incorporated into an electrical product such as a transformer or motor, the sample may be taken from any location on the component. When the component is small, the length of one side of the sample may be less than 100 mm. In this case, the total sample area is 10,000 mm. ２ At this time, it is desirable to collect the sample by a method such as wire cutting in order to minimize the influence of mechanical distortion on the sample.

[0118] (Method for Identifying Magnetic Domain Control Treatment Lines 11) When the magnetic domain control treatment lines 11 are grooves, the magnetic domain control treatment lines 11 can be identified visually. When the grain-oriented electrical steel sheet 1 has an insulating coating, the insulating coating can be removed using a known stripping agent, thereby making the magnetic domain control treatment lines 11 visible.

[0119] If the magnetic domain control treatment lines 11 are thermally strained, they may not be identifiable by visual inspection. In this case, a magnetic domain image is taken using, for example, an image acquisition device 30 as shown in FIG. 6 . 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 location of the thermal strain can be identified.

[0120] (Method for determining the rolling direction RD and the transverse direction TD) The rolling direction RD and the transverse direction TD of the grain-oriented electrical steel sheet 1 are determined by the following means. (1) When the sample is cut out from a coil-shaped grain-oriented electrical steel sheet 1, the width direction of the coil is considered to be the transverse direction TD. Also, the direction perpendicular to the transverse direction TD and the normal direction ND to the rolling surface is considered to be the rolling direction RD. (2) When the sample is cut out from a part of an electrical product, etc., the rolling direction RD and the transverse direction TD are determined from rolling defects on the surface of the grain-oriented electrical steel sheet 1. The extension direction of the rolling defects is considered to be the rolling direction RD. The direction perpendicular to the rolling direction RD and the normal direction ND to the rolling surface is considered to be the transverse direction TD. (3) When it is difficult to identify the rolling direction RD and the direction transverse to the rolling direction TD from the rolling defects on the surface of the grain-oriented electrical steel sheet 1, the rolling direction RD and the direction transverse 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. Then, the direction in which the angle between the crystal orientation at the measurement point and the direction normal to the rolling surface ND (sheet thickness direction) is closest to a right angle and which has the smallest deviation angle from the axis of easy magnetization <001> is regarded as the rolling direction RD, and the direction perpendicular to the rolling direction RD and the direction normal to the rolling surface ND is regarded as the direction transverse to the rolling direction TD.

[0121] (Method for measuring β angles) β angles are measured using the side reflection Laue method. The side reflection Laue method is widely known as a method for measuring crystal orientation. However, the β angle is a value obtained by rounding off the measured value to one decimal place. In other words, the significant figures for the β angle are rounded to one decimal place.

[0122] (|β Ａｌｌ |Calculation method) |β Ａｌｌ The outline of the method for calculating | is as follows. Measurement points are set in a grid pattern on the surface of a sample taken from the grain-oriented electrical steel sheet 1, as shown in FIG. 13. The absolute value of the β angle is measured at each measurement point, and the average value of these is calculated. This average value is called |β Ａｌｌ |It is considered to be.

[0123] Specifically, on the surface of a sample (the rectangular area surrounded by the dashed line in FIG. 13 ) with one side of 100 mm or more, a virtual line VL1 parallel to the direction perpendicular to the rolling direction TD and a virtual line VL2 parallel to the rolling direction RD are set. When setting the virtual lines VL1 and VL2, the existence of the magnetic domain control processing line 11 is not taken into consideration. The spacing between the virtual lines VL1 is 2 mm. The spacing between the virtual lines VL2 is 2 mm. The virtual lines VL1 and VL2 are arranged over the entire surface of the sample. The absolute value of the β angle at the intersection VP1 between the virtual lines VL1 and VL2 is measured.

[0124] (|β Ｄｒ |Calculation method) |β Ｄｒ The method for calculating | is as follows. First, on the surface of a sample (a rectangular area surrounded by a dashed line in FIG. 1 or FIG. 2) with one side of 100 mm or more, a plurality of imaginary lines VL3 are set at regular intervals in parallel along the rolling direction RD of the grain-oriented electrical steel sheet 1. VL3 is calculated by |β Ａｌｌ The imaginary lines VL3 may be the same as or different from the imaginary lines VL2 parallel to the rolling direction RD when calculating |. The interval between the imaginary lines VL3 is 2 mm. The imaginary lines VL3 are arranged over the entire surface of the sample. Next, the magnetic domain control points VP2 (i.e., the intersections of the imaginary lines VL3 and the magnetic domain control processing lines 11) are identified. Then, the absolute values ​​of the β angles at each of the magnetic domain control points VP2 are measured, and the average value of these is calculated. This average value is called |β ＤｒThe method for specifying the rolling direction RD and the magnetic domain control treatment line 11, and the method for measuring the β angle are as described above.

[0125] (σ Ａｌｌ (Method of measurement) σ Ａｌｌ is |β Ａｌｌ It can be obtained by calculating the standard deviation of the absolute values ​​of the β angles at each measurement point used in calculating |. The method for determining the absolute value of the β angle at each measurement point is as described above.

[0126] (σ Ｄｒ (Method of measurement) σ Ｄｒ is obtained by calculating the standard deviation of the absolute values ​​of the β angles at each of the magnetic domain control points VP2. The method for identifying the magnetic domain control points VP2 is as described above.

[0127] (Method for measuring the chemical composition of the master sheet 2 and the grain-oriented electrical steel sheet 1) The chemical compositions of the grain-oriented electrical steel sheet 1 and the master sheet 2 may be measured by a general steel analysis method. For example, the chemical compositions may be measured using ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry). Specifically, a test piece is obtained from the center of the sample in the thickness direction, and the chemical compositions of the grain-oriented electrical steel sheet 1 and the master sheet 2 can be measured by measuring the test piece using a measuring device such as an ICPS-8100 manufactured by Shimadzu Corporation under conditions based on a pre-created calibration curve. 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.

[0128] If a forsterite coating and / or an insulating coating is formed on the grain-oriented electrical steel sheet 1 and the base sheet 2, the forsterite coating and / or the insulating coating can be removed from the grain-oriented electrical steel sheet 1 and the base sheet 2 before analyzing the chemical composition of the grain-oriented electrical steel sheet 1 and the base sheet 2. The forsterite coating can be removed, for example, by immersing the sample in sulfuric acid and then in nitric acid. The conditions, such as the temperature and concentration of the sulfuric acid and nitric acid, and the immersion time, are adjusted appropriately so as not to excessively dissolve the base steel of the sample. An example of the conditions for removing the forsterite coating is as follows: First, the sample is immersed in 10% sulfuric acid at 80°C for 3 minutes. Then, the surface of the sample is washed with water using a rag or the like to remove any sludge adhering to the surface. Then, the sample is dried. Next, 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. The temperature and concentration of the sodium hydroxide, dilute sulfuric acid, and nitric acid solutions, as well as the immersion time, are adjusted appropriately to prevent excessive dissolution of the steel substrate of the sample. An example of the conditions for removing the insulating coating 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. Next, the sample is immersed in a 10% dilute sulfuric acid solution at 80°C for 4 minutes. After that, any sludge adhering to the sample surface is removed using a rag or similar. Next, the sample is immersed in a 10% nitric acid solution at room temperature for approximately 10 seconds while stirring.

[0129] (Method for measuring the angle between the magnetic domain control processing line 11 and the direction transverse to rolling TD) The angle between the magnetic domain control processing line 11 and the direction transverse to rolling TD can be measured using a known angle measuring means after the magnetic domain control processing line 11 and the direction transverse to rolling TD have been identified using the procedure described above.

[0130] (Method for measuring the spacing of the magnetic domain control processing lines 11 along the rolling direction RD) The spacing of the magnetic domain control processing lines 11 along the rolling direction RD can be measured using a known length measuring means after the magnetic domain control processing lines 11 and the rolling direction RD have been identified using the procedure described above.

[0131] (Method for measuring the magnitude of tensile stress induced by thermal strain) The magnitude of tensile stress induced by thermal strain is measured by the EBSD Wilkinson method and a Cross Court manufactured by BLG Vantage. The EBSD Wilkinson method is described in A. J. Wilkinson, et al., "High-resolution elastic strain measurement from electron backscatter diffraction patterns: New levels of sensitivity," Ultramicroscopy, Vol. 106, No. 4-5, March 2006, pp. 111-115, 2006. 307-313.

[0132] When measuring the magnitude of the tensile stress induced by thermal strain using the EBSD Wilkinson method and a Cross Court manufactured by BLG Vantage, first, the magnetic domain control treatment line 11 is identified using the procedure described above. Next, the grain-oriented electrical steel sheet 1 is cut through the magnetic domain control treatment line 11 and perpendicular to the magnetic domain control treatment line 11. This cut surface is used as the measurement surface. The cross section of the magnetic domain control treatment line 11 included in the measurement surface is analyzed using the EBSD Wilkinson method and a Cross Court manufactured by BLG Vantage, and tensile stress components in any direction are extracted and their magnitudes are measured. For example, tensile stress components in the normal direction ND of the rolling surface, the direction parallel to the magnetic domain control treatment line 11, and the direction perpendicular to the normal direction ND of the rolling surface and the magnetic domain control treatment line 11 can be extracted.

[0133] The number of measurement points is, for example, 10. If the tensile stress in any direction is 40 MPa or more at at least one point of the grain-oriented electrical steel sheet 1 (i.e., if the tensile stress in at least one direction is 40 MPa or more), the maximum value of the tensile stress in any direction in the magnetic domain control treatment 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 tensile stress is 40 MPa or more, the measurement of tensile stress may be stopped when a measurement point where the tensile stress in any direction is 40 MPa or more is found. However, if the σ(TSｍ ) ２ , T.S. ｍ（β＜２） , or TS ｍ（β≧２） When determining the tensile stress, do not stop the measurement and determine the tensile stress at each measurement point.

[0134] (Method for Measuring Groove Depth and Width) The groove depth and width 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 a tensile insulating coating, the insulating coating is removed using the procedure described above before three-dimensional measurement of the sample surface is performed.

[0135] Preferably, in the grain-oriented electrical steel sheet according to this embodiment, the magnetic domain control strength in the magnetic domain control treatment region is made non-uniform. The magnetic domain control strength is the maximum value of the tensile strength introduced by the thermal strain 541 when the magnetic domain control means is the thermal strain 541, and is the maximum value of the depth of the groove 542 when the magnetic domain control means is the groove 542.

[0136] The "maximum tensile strength introduced into thermal strain 541" refers to the maximum tensile strength measured at a single arbitrary measurement cross-section. It should be noted here that the magnitude and direction of the tensile strength vary across a single measurement cross-section, and therefore, a single "maximum tensile strength introduced into thermal strain 541" is identified for a single measurement cross-section. As shown schematically in FIG. 17 , thermal strain 541 has a certain degree of spread across the cross-section. The tensile strength is greatest at the location directly irradiated with the laser, and is smaller at locations distant from that location. In other words, the measured tensile strength value differs for each measurement location and measurement direction on the cross-section. Using the tensile strength measurement method described below, the distribution and maximum value of tensile strength across the cross-section can be derived.

[0137] When the magnetic domain control strength is uniform, the maximum value of the tensile strength introduced into the thermal strain 541 is constant throughout the entire magnetic domain refinement treatment line 54. On the other hand, when the magnetic domain control strength is non-uniform, the maximum value of the tensile strength introduced into the thermal strain on the magnetic domain refinement treatment line is non-uniform for each tensile strength measurement point. Hereinafter, the maximum value of the tensile strength introduced into the thermal strain may be simply referred to as "tensile strength."

[0138] The "maximum depth of groove 542" is the maximum depth of groove 542 at one arbitrary measurement point, measured by the method described below. As shown schematically in FIG. 18, the depth of groove 542 is also not uniform at one measurement point. In general, the closer to the edge of the groove, the smaller the depth of the groove. Therefore, one "maximum depth of groove 542" is identified for one measurement cross section.

[0139] When the magnetic domain control strength is uniform, the maximum depth of the grooves 542 is constant across the entire magnetic domain refining process line 54. On the other hand, when the magnetic domain control strength is non-uniform, the maximum depth of the grooves 542 on the magnetic domain refining process line is non-uniform for each measurement point of the groove depth. Hereinafter, the maximum depth of the grooves 542 may be simply referred to as the "groove depth."

[0140] As described above, the magnetic domain control saturation strength is high in areas with small β angles. It is preferable to perform magnetic domain control treatment with high magnetic domain control strength in areas with small β angles, and magnetic domain control treatment with low magnetic domain control strength in areas with large β angles. In this way, in grain-oriented electrical steel sheets that have undergone magnetic domain control treatment, which selects the optimal magnetic domain control strength depending on the size of the β angle, the magnetic domain control strength in the magnetic domain control treatment region becomes non-uniform. In magnetic domain control treatment lines provided in areas with large β angles, the grooves are shallow or the tensile strength induced by thermal distortion is low. In magnetic domain control treatment lines provided in areas with small β angles, the grooves are deep or the tensile strength induced by thermal distortion is high. In such grain-oriented electrical steel sheets, the iron loss of the grain-oriented electrical steel sheet after magnetic domain control is further reduced. Meanwhile, 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.

[0141] When the magnetic domain control processing line is thermal distortion, the grain oriented electrical steel sheet is σ ２ (TS ｍ ) > 5.0. ｍ is the tensile strength in units of MPa introduced by thermal strain, measured at each of the multiple magnetic domain control points, which are the intersections of the multiple virtual lines VL3 and the magnetic domain control treatment lines. ２ (TS ｍ ) is T.S. ｍ This is the variance of

[0142] σ ２ (TS ｍ ) > 5.0, the magnetic domain control strength is changed based on the size of the magnetic domain width or the size of the β 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.

[0143] TS ｍ and σ ２ (TS ｍ An example of a method for measuring the β angle is shown in FIG. 19. The dashed line in FIG. 19 is the imaginary line VL3. The marks X and O in FIG. 19 are the intersections of the imaginary line VL3 and the thermal distortion 541, which is the magnetic domain control processing line. The β angle at the point marked with the mark X is β Ｄｒ The β angle at the point marked with O is β Ｄｒ is less than σ ２ (TS ｍ ) the β angle at the intersection point does not need to be taken into account.

[0144] First, the intersection of the virtual line VL3 and the thermal strain 541, which is the magnetic domain control processing line, is identified. If the thermal strain 541 cannot be seen with the naked eye, the thermal strain 541 is identified based on a magnetic domain image. The shape of the measurement region is preferably a rectangle whose size along the rolling direction RD is 100 mm or more and whose size along the rolling perpendicular direction TD is 100 μm or more. One side of the rectangle is preferably parallel to the rolling direction RD.

[0145] Then, σm at all intersections in the measurement area is measured, and the variance σm ２ (TS ｍ The maximum tensile strength TS determined at each of the multiple measurement points is calculated. Ｍ Variance σ ２ (TS Ｍ ) 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."

[0146] Or, when the magnetic domain control processing line is thermal distortion, the grain oriented electrical steel sheet is TS ｍ（β＜βＤｒ） >TS ｍ（β≧βＤｒ）It is preferable to satisfy the following. ｍ（β＜βＤｒ） is a point where the β angle is β among a plurality of magnetic domain processing points, which are intersections of a plurality of imaginary lines VL3 set in parallel at intervals of 2 mm along the rolling direction of the grain-oriented electrical steel sheet and the magnetic domain control processing line. Ｄｒ TS is the arithmetic mean value of the maximum tensile strength in MPa introduced by thermal strain, measured at each of the magnetic domain processing points less than 1000 MPa. ｍ（β≧βＤｒ） is the angle β Ｄｒ This is the arithmetic mean value of the maximum values ​​of tensile strength in units of MPa introduced by thermal strain, measured at each of the above magnetic domain processing points.

[0147] TS ｍ（β＜βＤｒ） >TS ｍ（β≧βＤｒ） When the above condition is satisfied, the magnetic domain control strength is high where the β angle is small, and low where the β angle is large. Therefore, the iron loss of the grain-oriented electrical steel sheet after magnetic domain control is further reduced. On the other hand, 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.

[0148] On the other hand, when the magnetic domain control processing line is the groove 542, it is preferable that the grain-oriented electrical steel sheet is σ ２ (D ｍ )>3.0. Dm is the depth of the groove 542 in μm at the magnetic domain control point, which is the intersection of the multiple virtual lines VL3 and the magnetic domain control processing line. σ ２ (D ｍ ) is D ｍ is the variance of

[0149] σ ２ (D ｍ ) > 3.0, the magnetic domain control strength is changed based on the size of the magnetic domain width or the size of the β 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.

[0150] D ｍ and σ ２ (D ｍAn example of a method for measuring the β angle is shown in Figure 20. The dashed lines in Figure 20 are multiple imaginary lines VL3 set at 2 mm intervals in parallel along the rolling direction RD of the grain-oriented electrical steel sheet. The marks X and O in Figure 20 are intersections between the imaginary lines VL3 and the grooves 542, which are magnetic domain control treatment lines. The β angle at the points marked with X is β Ｄｒ The β angle at the point marked with O is β Ｄｒ is less than σ ２ (D ｍ ) the β angle at the intersection point does not need to be taken into account.

[0151] First, the intersection of the virtual line VL3 and the magnetic domain control treatment line is identified. If the magnetic domain control treatment line is not visible to the naked eye, the magnetic domain control treatment line is identified based on the magnetic domain image. If the magnetic domain refining treatment line is a groove 542, it is easy to see the magnetic domain refining treatment line with the naked eye. The shape of the measurement area is preferably a rectangle whose size along the rolling direction RD is 100 mm or more and whose size along the rolling perpendicular direction TD is 100 mm or more. One side of the rectangle is preferably parallel to the rolling direction RD.

[0152] The maximum value D of the groove depth at all intersections in the measurement area ｍ The maximum groove depth D ｍ Variance σ ２ (D ｍ) is calculated. The maximum groove depth Dm is measured as follows. Measurements are made using a Bruker Control GT-I white light interference microscope. The lens used is a 5x objective (numerical aperture 0.12, optical resolution 2.2 μm) with an internal 1x magnification, a white LED light source, and a monochrome CCD camera (1200 x 1000 pixels). The pixel size is 1.37 μm, and after performing tilt correction by fitting to a least-squares plane using the 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. Note that the pixel size may be resampled to 10 μm if necessary during analysis. Additionally, areas that are clearly deemed to be abnormal points may be excluded from the analysis. The type of lens, filter value, and correction method may be changed depending on the properties of the sample. In addition, if grooves are formed in the grain-oriented electrical steel sheet but the unevenness cannot be measured from the surface due to an insulating coating or the like, the insulating coating or the like is removed using a known method and the above measurement is carried out.

[0153] Alternatively, when the magnetic domain control processing line is the groove 542, the grain-oriented magnetic steel sheet is D ｍ（β＜βＤｒ） >D ｍ（β≧βＤｒ） It is preferable to satisfy the following. ｍ（β＜βＤｒ） is the intersection of a plurality of imaginary lines VL3 set parallel to the rolling direction of the grain-oriented electrical steel sheet at intervals of 2 mm with the magnetic domain control treatment line, and is the point where the β angle is β Ｄｒ D is the arithmetic mean value of the maximum groove depth in μm measured at each magnetic domain control point less than ｍ（β≧βＤｒ） is the angle β Ｄｒ This is the arithmetic mean value of the maximum groove depths measured at each of the above magnetic domain control points in the unit of μm.

[0154] In a magnetic domain control processed wire that satisfies this formula, the magnetic domain control strength is high where the β angle is small and low where the β angle is large. Therefore, the iron loss of the grain-oriented electrical steel sheet after magnetic domain control is further reduced. At the same time, 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.

[0155] TS ｍ (β<2) and TSｍ An example of a method for measuring (β≧2) is shown in FIG. 20. As described above, the X mark and the O mark in FIG. 20 are the intersections of the imaginary line VL3 and the groove 542, which is the magnetic domain control processing line. The β angle at the point marked with the X mark is β Ｄｒ The β angle at the point marked with O is β Ｄｒ is less than.

[0156] First, measure the β angle at the intersection, and determine that the β angle is β Ｄｒ The above intersections and β angles are β Ｄｒ Identify the intersection point where the β angle is less than β Ｄｒ D at all the above intersections ｍ The arithmetic mean value of ｍ（β≧βＤｒ） Furthermore, the β angle is β Ｄｒ D at all intersections less than ｍ The arithmetic mean value of ｍ（β≧βＤｒ） The maximum depth of the groove at the intersection D ｍ The measurement method is as described above.

[0157] The effects of one embodiment of the present disclosure will be explained in more detail using examples. However, the conditions in the examples are merely examples of conditions adopted to confirm the feasibility and effects of the present disclosure. The present disclosure is not limited to this 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 object of the present disclosure is achieved.

[0158] (Example 1) Grain-oriented electrical steel sheets of the same lot, classified as 23P085 in Table 2 of JIS C 2553:2019 "Grain-oriented electrical steel strip," with a thickness of 0.23 mm were used as base sheets. The base sheets were subjected to magnetic domain control treatment under various conditions shown in Table 1. The noise and iron loss of the grain-oriented electrical steel sheets thus obtained that had undergone magnetic domain control treatment were evaluated and the results are shown in Table 2. In Table 1, values ​​outside the range for the grain-oriented electrical steel sheet according to this embodiment are underlined. In Table 2, values ​​that do not meet the following pass / fail criteria are underlined.

[0159] The noise and transformer iron loss W16 / 50 were evaluated as follows. Hereinafter, transformer iron loss W16 / 50 will be simply referred to as iron loss. First, a three-phase transformer core was fabricated by stacking 180 grain-oriented electrical steel sheets with a thickness of 0.23 mm. The widths of the legs and yoke of the three-phase transformer core were both 150 mm. The height and width of the outer dimensions of the three-phase transformer core were both 750 mm. The noise and iron loss of these three-phase transformer cores were measured. The measurement conditions were a frequency of 60 Hz and an excitation magnetic flux density of 1.5 T.

[0160] To measure the noise, microphones were placed at equal intervals around eight locations around the transformer incorporating the three-phase transformer core. The distance between the transformer and the microphones was 30 cm. The noise measurement results from these microphones were A-weighted corrected and averaged to obtain values, which are listed in Table 2 as the noise evaluation results (unit: dBA) of the grain-oriented electrical steel sheet. Examples with a noise evaluation result of 30.50 dBA or less were determined to be examples in which low noise was achieved. Noise evaluation results that were determined to be unacceptable are underlined.

[0161] 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 60 Hz and an excitation magnetic flux density of 1.5 T, as described above. The determined iron loss is shown in Table 2 as the iron loss evaluation results (unit: W / kg) of the three-phase transformer. Examples with an iron loss evaluation result of 0.850 W / kg or less were determined to be examples in which low iron loss was achieved. Noise evaluation results that were determined to be unacceptable are underlined.

[0162] Furthermore, in grain-oriented electrical steel sheets that have undergone magnetic domain control processing, |β Ａｌｌ |, |β Ｄｒ |, σ Ａｌｌ and σ Ｄｒ The results are shown in Table 2. The measurement method essentially followed the procedure described above. A rectangular sample with both sides measuring 100 mm was cut out from the iron core of a three-phase transformer used for measuring noise and iron loss, and was used for the measurement.

[0163]

[0164]

[0165] In Sample No. 10, all of the magnetic domain control treatment lines were formed across the entire width of the grain-oriented electrical steel sheet. As a result, Sample No. 10 had a low |β Ａｌｌ |-|β Ｄｒ In Example No. 10, the iron loss was within the acceptable range, but the noise characteristics were unacceptable.

[0166] In Example No. 11, the magnetic domain control processing lines were formed in the shape of dashed lines. That is, in Example No. 11, similar to Example Nos. 1 to 9, an area where magnetic domain control processing was not performed was provided. However, in Example No. 11, the size of the gap between the magnetic domain control processing lines included in the dashed lines was randomly varied. The areas where magnetic domain control processing was not performed were provided randomly without any consideration of the distribution of magnetic domain widths in the magnetic domain image. As a result, in Example No. 11, |β Ａｌｌ |-|β Ｄｒ |≧0.1° was not satisfied. In Example No. 11, the iron loss was within the acceptable range, but was the same value as the acceptable judgment value of 0.850. In addition, in Example No. 11, the noise characteristics were unacceptable.

[0167] In Example No. 12, the magnetic domain control processing lines were formed in a regular dashed line shape. That is, in Example No. 12, similar to Example Nos. 1 to 9, an area where magnetic domain control processing was not performed was provided. However, in Example No. 12, the size of the gap between the magnetic domain control processing lines included in the dashed lines was set to a constant value. The areas where magnetic domain control processing was not performed were provided in a regular pattern without any consideration of the distribution of magnetic domain widths in the magnetic domain image. As a result, in Example No. 12, |β Ａｌｌ |-|β Ｄｒ |≧0.1° was not satisfied. In Example No. 12, both the iron loss and noise characteristics were unacceptable.

[0168] In Example Nos. 13 and 14, the magnetic domain control process was applied to the area where the β angle was large. Ａｌｌ |-|β Ｄｒ |≧0.1° was not satisfied. In Example Nos. 13 and 14, the iron loss was unacceptable.

[0169] On the other hand, in Examples 1 to 9, the magnetic domain control treatment was applied to a magnetic domain control treatment region (region with a small β angle) limited based on the distribution of the magnetic domain width.Ａｌｌ |-|β Ｄｒ |≧0.1° was satisfied, and both the noise characteristics and iron loss were within the acceptable range. Example Nos. 1 to 9 achieved both low iron loss and low noise.

[0170] According to Example Nos. 1 to 9, |β Ａｌｌ |-|β Ｄｒ It was confirmed that the larger |β is, the better the noise characteristics are. Ａｌｌ |-|β Ｄｒ |>σ Ａｌｌ In Example 9, σ Ｄｒ <σ Ａｌｌ In these examples, noise characteristics and iron loss were even better.

[0171] Second Example In order to evaluate the properties of grain-oriented electrical steel sheets with non-uniform magnetic domain control strength, the following experiments were carried out. Ａｌｌ |-|β Ｄｒ | ≥ 0.1° was satisfied.

[0172] The original sheets were subjected to magnetic domain control treatment under various conditions. The noise and iron loss of the grain-oriented electrical steel sheets obtained by the magnetic domain control treatment were evaluated, and the results are shown together with the conditions in Tables 3 and 4. The original sheets used were grain-oriented electrical steel sheets of the same lot with a thickness of 0.23 mm, classified as 23P085 in Table 2 of JIS C 2553:2019 "Grain-oriented electrical steel strips."

[0173] The methods for measuring and evaluating noise and iron loss were the same as those in the first example.

[0174]

[0175] Example number A1 is |β Ａｌｌ |-|β Ｄｒ |≧0.1 was satisfied, the iron loss evaluation results and noise evaluation results were better than those of conventional grain-oriented electrical steel sheets.

[0176] On the other hand, in example number A2, |β Ａｌｌ |-|β ＤｒIn addition to satisfying the condition |≧0.1, the maximum value of the tensile strength introduced into the amount of thermal strain in the magnetic domain control treated wire was non-uniform for each measurement point of the tensile strength. The evaluation results of iron loss and noise of Example No. A2 were even better than those of Example No. A1.

[0177] Example number A3 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1, the maximum value of the tensile strength introduced into the amount of thermal strain in the magnetic domain control processed wire is non-uniform for each measurement point of the tensile strength, and further, σ ２ (TS ｍ )>5.0. The evaluation results of iron loss and noise of Example No. A3 were even better than those of Example Nos. A1 and A2.

[0178] Example number A4 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1, the maximum value of the tensile strength introduced into the amount of thermal strain in the magnetic domain control processed wire is non-uniform for each measurement point of the tensile strength, and further, TS ｍ（β＜βＤｒ） >TS ｍ（β≧βＤｒ） At least one of the evaluation results of iron loss and noise of sample number A4 was better than those of sample numbers A1 and A2.

[0179] Example number A5 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1, the maximum value of the tensile strength introduced into the amount of thermal strain in the magnetic domain control processed wire is non-uniform for each measurement point of the tensile strength, and further, σ ２ (TS ｍ ) > 5.0 and TS ｍ（β＜βＤｒ） >TS ｍ（β≧βＤｒ） At least one of the evaluation results of iron loss and noise of sample number A5 was superior to those of sample numbers A1 to A5.

[0180] Example number A6 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1, the maximum value of the tensile strength introduced into the amount of thermal strain in the magnetic domain control processed wire is non-uniform for each measurement point of the tensile strength, and |β Ａｌｌ |-|β Ｄｒ |>σ ＡｌｌThe evaluation results of iron loss and noise of sample number A6 were even better than those of sample numbers A1 and A2.

[0181] Example number A7 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1, the maximum value of the tensile strength introduced into the amount of thermal strain in the magnetic domain control processed wire is non-uniform for each measurement point of the tensile strength, and σ ２ (TS ｍ ) > 5.0, and |β Ａｌｌ |-|β Ｄｒ |>σ Ａｌｌ The evaluation results of iron loss and noise of sample number A7 were even better than those of sample numbers A1 to A3 and A6.

[0182] Example number A8 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1°, the maximum value of the tensile strength introduced into the amount of thermal strain in the magnetic domain control processed wire is non-uniform for each measurement point of the tensile strength, and TS ｍ（β＜βＤｒ） >TS ｍ（β≧βＤｒ） In addition to satisfying |β Ａｌｌ |-|β Ｄｒ |>σ Ａｌｌ At least one of the evaluation results of iron loss and noise of sample number A8 was superior to sample numbers A1 to A4 and A6.

[0183] Example number A9 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1°, the maximum value of the tensile strength introduced into the amount of thermal strain in the magnetic domain control processed wire is non-uniform for each measurement point of the tensile strength, and σ ２ (TS ｍ ) > 5.0 and TS ｍ（β＜βＤｒ） >TS ｍ（β≧βＤｒ） In addition to satisfying |β Ａｌｌ |-|β Ｄｒ |>σ Ａｌｌ The evaluation results of iron loss and noise of Example No. A9 were even better than those of Example Nos. A1 to A5 and A6 to A8.

[0184] Example number A10 is |β Ａｌｌ |-|β ＤｒIn addition to satisfying |≧0.1, the maximum value of the tensile strength introduced into the amount of thermal strain in the magnetic domain control processed wire is non-uniform for each measurement point of the tensile strength, and σ Ｄｒ <σ Ａｌｌ The evaluation results of iron loss and noise of sample number A10 were even better than those of sample numbers A1 and A2.

[0185] Example number A11 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1, the maximum value of the tensile strength introduced into the amount of thermal strain in the magnetic domain control processed wire is non-uniform for each measurement point of the tensile strength, and σ ２ (TS ｍ ) > 5.0, and σ Ｄｒ <σ Ａｌｌ At least one of the evaluation results of iron loss and noise of sample number A11 was superior to sample numbers A1 to A3 and A10.

[0186] Example number A12 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1°, the maximum value of the tensile strength introduced into the amount of thermal strain in the magnetic domain control processed wire is non-uniform for each measurement point of the tensile strength, and TS ｍ（β＜βＤｒ） >TS ｍ（β≧βＤｒ） In addition to satisfying Ｄｒ <σ Ａｌｌ At least one of the evaluation results of iron loss and noise of sample number A12 was superior to sample numbers A1 to A4 and A10.

[0187] Example number A13 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1°, the maximum value of the tensile strength introduced into the amount of thermal strain in the magnetic domain control processed wire is non-uniform for each measurement point of the tensile strength, and σ ２ (TS ｍ ) > 5.0 and TS ｍ（β＜βＤｒ） >TS ｍ（β≧βＤｒ） In addition to satisfying Ｄｒ <σ Ａｌｌ At least one of the evaluation results of iron loss and noise of sample number A13 was superior to sample numbers A1 to A5 and A10 to A12.

[0188] Example number A14 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1°, the maximum value of the tensile strength introduced into the amount of thermal strain in the magnetic domain control processed wire is non-uniform for each measurement point of the tensile strength, and σ ２ (TS ｍ ) > 5.0 and TS ｍ（β＜βＤｒ） >TS ｍ（β≧βＤｒ） In addition to satisfying |β Ａｌｌ |-|β Ｄｒ |>σ Ａｌｌ / 2 and σ Ｄｒ <σ Ａｌｌ The evaluation results of iron loss and noise for sample number A14 were the best among sample numbers A1 to A14.

[0189]

[0190] Example number B1 is |β Ａｌｌ |-|β Ｄｒ |≧0.1° was satisfied, and therefore the iron loss evaluation results and noise evaluation results were better than those of conventional grain-oriented electrical steel sheets.

[0191] Example number B2 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying the condition |≧0.1°, the maximum value of the groove depth in the magnetic domain control processed line was not uniform for each measurement point of the groove. The evaluation results of iron loss and noise for Example No. B2 were even better than those for Example No. B1.

[0192] Example number B3 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1°, the maximum value of the depth of the groove in the magnetic domain control processing line is non-uniform for each measurement point of the groove, and further, σ ２ (D ｍ )>3.0. The evaluation results of iron loss and noise of Example No. B3 were even better than those of Example Nos. B1 and B2.

[0193] Example number B4 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1°, the maximum value of the depth of the groove in the magnetic domain control processing line is non-uniform for each measurement point of the groove, and further, D ｍ（β＜βＤｒ） >Dｍ（β≧βＤｒ） The evaluation results of iron loss and noise of Example No. B4 were even better than those of Example Nos. B1 and B2.

[0194] Example number B5 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1°, the maximum value of the depth of the groove in the magnetic domain control processing line is non-uniform for each measurement point of the groove, and further, σ ２ (D ｍ ) > 3.0 and D ｍ（β＜βＤｒ） >D ｍ（β≧βＤｒ） The evaluation results of iron loss and noise for Example No. B5 were the best among Example Nos. B1 to B5.

[0195] Example number B6 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1°, the maximum value of the depth of the groove in the magnetic domain control processing line is non-uniform for each measurement point of the groove, and |β Ａｌｌ |-|β Ｄｒ |>σ Ａｌｌ The iron loss and noise evaluation results of Example No. B6 were even better than those of Example Nos. B1 and B2.

[0196] Example number B7 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1°, the maximum value of the depth of the groove in the magnetic domain control processing line is non-uniform for each measurement point of the groove, and σ ２ (D ｍ )>3.0, and |β Ａｌｌ |-|β Ｄｒ |>σ Ａｌｌ The iron loss and noise evaluation results of Example No. B7 were even better than those of Example Nos. B1, B2, and B6.

[0197] Example number B8 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1°, the maximum value of the depth of the groove in the magnetic domain control processing line is non-uniform for each measurement point of the groove, and D ｍ（β＜βＤｒ） >D ｍ（β≧βＤｒ） In addition to satisfying |β Ａｌｌ |-|β Ｄｒ |>σ ＡｌｌThe iron loss and noise evaluation results of Example No. B8 were even better than those of Example Nos. B1, B2, and B6.

[0198] Example number B9 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1°, the maximum value of the depth of the groove in the magnetic domain control processing line is non-uniform for each measurement point of the groove, and σ ２ (D ｍ ) > 3.0 and D ｍ（β＜βＤｒ） >D ｍ（β≧βＤｒ） In addition to satisfying |β Ａｌｌ |-|β Ｄｒ |>σ Ａｌｌ At least one of the evaluation results of iron loss and noise of sample number B9 was superior to those of samples B1 to B5 and B6 to B8.

[0199] Example number B10 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1°, the maximum value of the depth of the groove in the magnetic domain control processing line is non-uniform for each measurement point of the groove, and σ Ｄｒ <σ Ａｌｌ The evaluation results of iron loss and noise of Example No. B10 were even better than those of Example Nos. B1 and B2.

[0200] Example number B11 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1°, the maximum value of the depth of the groove in the magnetic domain control processing line is non-uniform for each measurement point of the groove, and σ ２ (D ｍ )>3.0, and σ Ｄｒ <σ Ａｌｌ At least one of the evaluation results of iron loss and noise of sample number B7 was superior to those of sample numbers B1, B2, and B10.

[0201] Example number B12 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1°, the maximum value of the depth of the groove in the magnetic domain control processing line is non-uniform for each measurement point of the groove, and D ｍ（β＜βＤｒ） >D ｍ（β≧βＤｒ） In addition to satisfying Ｄｒ <σＡｌｌ The evaluation results of iron loss and noise of Example No. B12 were even better than those of Example Nos. B1, B2, and B10.

[0202] Example number B13 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1°, the maximum value of the depth of the groove in the magnetic domain control processing line is non-uniform for each measurement point of the groove, and σ ２ (D ｍ ) > 3.0 and D ｍ（β＜βＤｒ） >D ｍ（β≧βＤｒ） In addition to satisfying Ｄｒ <σ Ａｌｌ At least one of the evaluation results of iron loss and noise of sample number B13 was superior to those of samples B1 to B5 and B10 to B12.

[0203] Example number B14 is |β Ａｌｌ |-|β Ｄｒ In addition to satisfying |≧0.1°, the maximum value of the depth of the groove in the magnetic domain control processing line is non-uniform for each measurement point of the groove, and σ ２ (D ｍ ) > 3.0 and D ｍ（β＜βＤｒ） >D ｍ（β≧βＤｒ） In addition to satisfying |β Ａｌｌ |-|β Ｄｒ |>σ Ａｌｌ / 2 and σ Ｄｒ <σ Ａｌｌ The evaluation results of iron loss and noise for sample number B14 were the best among B1 to B14.

[0204] 1 Grain-oriented electrical steel sheet 11 Magnetic domain control treatment line 12A Region with small β angle 12B Region with large β angle RD Rolling direction TD Direction perpendicular to rolling ND Direction normal to rolling surface VL1 |β Ａｌｌ | Imaginary line VL2 parallel to TD for calculation |β Ａｌｌ | Imaginary line VL3 parallel to RD for calculation |β Ｄｒ| Imaginary line VP1 parallel to TD for calculation Intersection VP2 of imaginary line VL1 and imaginary line VL2 Magnetic domain control point 2 Original sheet 21 Magnetic domain control processing area 22 Non-magnetic domain control processing area 30 Image acquisition device 31 Light source unit 33 MO sensor 35 Image sensor 37 Signal processing unit 40 Analysis device 41 Calculation unit 43 Memory 45 Display unit 47 Input unit 49 Communication I / F 500 Laser irradiation device 501 Polygon mirror 503 Light source device 505 Collimator 507 Condenser lens 509 Motor 511 Sensor 513 Control unit 515 Strip threading device

Claims

1. A grain-oriented electrical steel sheet having a magnetic domain control processing line on the surface, Ａｌｌ |-|β Ｄｒ |≧0.1° is satisfied, and |β Ａｌｌ | is the average absolute value of the β angle over the entire surface of the grain-oriented electrical steel sheet, Ｄｒ | is the average value of the absolute values ​​of the β angles at the domain control points, which are the intersections of a plurality of imaginary lines set parallel to the rolling direction of the grain-oriented electrical steel sheet at intervals of 2 mm and the magnetic domain control treatment lines.

2. |β Ａｌｌ |-|β Ｄｒ The grain-oriented electrical steel sheet according to claim 1, wherein | ≧ 0.2° is satisfied.

3. |β Ａｌｌ |-|β Ｄｒ The grain-oriented electrical steel sheet according to claim 1, wherein | ≧ 0.5° is satisfied.

4. |β Ａｌｌ |-|β Ｄｒ The grain-oriented electrical steel sheet according to claim 1, wherein | ≧ 1.0° is satisfied.

5. |β Ａｌｌ |-|β Ｄｒ |>σ Ａｌｌ / 2, and σ Ａｌｌ The grain-oriented electrical steel sheet according to any one of claims 1 to 4, wherein x is the standard deviation of the absolute values ​​of the β angles over the entire surface of the grain-oriented electrical steel sheet.

6. σ Ｄｒ <σ Ａｌｌ and σ Ａｌｌ is the standard deviation of the absolute value of the β angle over the entire surface of the grain-oriented electrical steel sheet, and σ Ｄｒ The grain-oriented electrical steel sheet according to any one of claims 1 to 4, wherein β is the standard deviation of the absolute value of the β angle at the magnetic domain control point.

7. The grain-oriented electrical steel sheet according to any one of claims 1 to 4, wherein the magnetic domain control treatment line is a thermal strain.

8. The grain-oriented electrical steel sheet according to any one of claims 1 to 4, wherein the magnetic domain control treatment lines are grooves.

9. The grain-oriented electrical steel sheet according to claim 7, characterized in that the maximum value of the tensile strength introduced by the thermal strain in the magnetic domain control treatment wire is non-uniform for each measurement point of the tensile strength.

10. σ ２ (TS ｍ )>5.0, TS ｍ is the tensile strength in MPa induced by the thermal strain measured at each of the plurality of magnetic domain control points; and σ ２ (TS ｍ ) is T.S. ｍ The grain-oriented electrical steel sheet according to claim 9, characterized in that 11. T.S. ｍ（β＜βＤｒ） >T.S. ｍ（β≧βＤｒ） Fulfilling the requirements, TS ｍ（β＜βＤｒ） Among the magnetic domain processing points, the β angle is β Ｄｒ TS is the arithmetic mean value of the maximum tensile strength in MPa introduced during thermal strain, measured at each of the magnetic domain treatment points less than TS ｍ（β≧βＤｒ） The β angle is β Ｄｒ 11. The grain-oriented electrical steel sheet according to claim 9 or 10, wherein the maximum tensile strength is an arithmetic average value of the maximum values ​​of the tensile strength in unit MPa introduced by the thermal strain, the maximum values ​​being measured at each of the magnetic domain treatment points.

12. The grain-oriented electrical steel sheet according to claim 8, characterized in that the maximum value of the depth of the groove in the magnetic domain control treatment line is non-uniform for each measurement point of the groove.

13. σ ２ (D ｍ ) > 3.0, D ｍ is the maximum depth of the groove in μm at the magnetic domain control point, and σ ２ (D ｍ ) is D ｍ The grain-oriented electrical steel sheet according to claim 12, characterized in that 14. D ｍ（β＜βＤｒ） >D ｍ（β≧βＤｒ） Satisfying D ｍ（β＜βＤｒ） Among the magnetic domain control points, the β angle is β Ｄｒ D is the arithmetic mean value of the maximum depth of the groove in μm measured at each of the magnetic domain control points less than ｍ（β≧βＤｒ） The β angle is β Ｄｒ The grain-oriented electrical steel sheet according to claim 12 or 13, characterized in that it is an arithmetic average value of maximum values ​​of the groove depths measured in unit μm at each of the magnetic domain control points.

15. A method for manufacturing a grain-oriented electrical steel sheet, comprising: a step of acquiring a magnetic domain image of an original sheet of the grain-oriented electrical steel sheet; a step of determining a magnetic domain control treatment area based on a distribution of magnetic domain widths in the magnetic domain image; and a step of applying magnetic domain control treatment to the magnetic domain control treatment area determined based on the distribution of magnetic domain widths, wherein in the grain-oriented electrical steel sheet to which the magnetic domain control treatment has been applied, |β Ａｌｌ |-|β Ｄｒ |≧0.1°, and |β Ａｌｌ | is the average absolute value of the β angle over the entire surface of the grain-oriented electrical steel sheet to which the magnetic domain control treatment has been applied, and |β Ｄｒ | is the average value of the absolute values ​​of the β angles at domain control points, which are the intersections of a plurality of virtual lines set at 2 mm intervals in parallel along the rolling direction of the grain-oriented electrical steel sheet to which the magnetic domain control treatment has been applied, and magnetic domain control treatment lines formed by the magnetic domain control treatment.

16. The method for producing grain-oriented electrical steel sheet according to claim 15, characterized in that the region in which the magnetic domain width is equal to or greater than a predetermined value is defined as the magnetic domain control treatment region.

17. A method for producing grain-oriented electrical steel sheet as set forth in claim 15 or 16, characterized in that the distribution of the magnetic domain widths is derived from the magnetic domain image using a two-dimensional Fourier transform.

18. The method for producing grain-oriented electrical steel sheet according to claim 15 or 16, characterized in that the magnetic domain control treatment is applied by irradiation with a laser or an electron beam.

19. The method for producing grain-oriented electrical steel sheet according to claim 15, characterized in that in the step of applying magnetic domain control treatment to the magnetic domain control treatment region, the magnetic domain control strength is made non-uniform.

Images