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

Abstract

This grain-oriented electromagnetic steel sheet has a magnetic domain control processing line on the surface thereof, and satisfies |α All |-|α Dr |≥ 0.1°, where |α All | is the average value of absolute values of an α angle over the entire surface of the grain-oriented electromagnetic steel sheet, and |α Dr | is the average value of absolute values of an α angle at a magnetic domain control point that is an intersection point of the magnetic domain control processing line and a plurality of virtual lines set at 2 mm intervals in parallel along a rolling direction of the grain-oriented electromagnetic steel sheet. A method for manufacturing a grain-oriented electromagnetic steel sheet according to another aspect of the present disclosure comprises: a step for measuring an α-angle distribution on the surface of an original sheet of a grain-oriented electromagnetic steel sheet; a step for identifying a region having an α-angle absolute value equal to or smaller than 5°; and a step for applying magnetic domain control processing to the region having the α-angle absolute value equal to or smaller than 5°.

Description

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

[0001] The present invention relates to a grain-oriented electrical steel sheet and a method for manufacturing the grain-oriented electrical steel sheet. The present invention claims priority based on Japanese Patent Application No. 2023-166173, 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 technology using 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] Japanese Patent Publication No. 2012-57219 Japanese Patent Publication No. 2012-12664 Japanese Patent Publication No. 2012-57218

[0006] When magnetic domain control treatment is applied to grain-oriented electrical steel sheets, the magnetostriction characteristics of the grain-oriented electrical steel sheets change due to closure domains. This deteriorates the noise characteristics of the grain-oriented electrical steel sheets. Noise characteristics refer to the level of noise generated by electrical products (e.g., transformers, motors, etc.) manufactured using grain-oriented electrical steel sheets. 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 sheets are excited with alternating current, the magnitude of magnetostriction changes with changes in the strength of the magnetization, causing vibrations. Although the magnitude of this magnetostriction is very small, on the order of 10-6, it generates vibrations in the iron core, which then propagate to external structures such as transformer tanks, 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 |α Ａｌｌ |-|α Ｄｒ |≧0.1°, and |α Ａｌｌ | is the average value of the absolute value of the α angle over the entire surface of the grain-oriented electrical steel sheet, and |α Ｄｒ is the average value of the absolute values ​​of the α 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 |α Ａｌｌ |-|α Ｄｒ (3) Preferably, the grain-oriented electrical steel sheet according to (1) satisfies |α Ａｌｌ |-|αＤｒ (4) Preferably, the grain-oriented electrical steel sheet according to (1) satisfies |α Ａｌｌ |-|α Ｄｒ (5) Preferably, the grain-oriented electrical steel sheet according to any one of (1) to (4) above satisfies |γ≧1.0°. Ａｌｌ |-|α Ｄｒ |≧0.1°, and |γ Ａｌｌ | is the average value of the absolute value of the γ angle over the entire surface of the grain-oriented electrical steel sheet. (6) Preferably, the grain-oriented electrical steel sheet according to any one of (1) to (5) above has a σα Ｄｒ <σα Ａｌｌ and σα Ａｌｌ is the standard deviation of the absolute value of the α angle over the entire surface of the grain-oriented electrical steel sheet, and σα Ｄｒ is the standard deviation of the absolute value of the α 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 lines are grooves.

[0011] (8) A method for producing a grain-oriented electrical steel sheet according to another aspect of the present disclosure includes the steps of measuring the distribution of α angles on the surface of an original sheet of the grain-oriented electrical steel sheet, identifying regions where the absolute value of the α angle is 5° or less, and forming magnetic domain control treatment lines in the regions where the absolute value of the α angle is 5° or less. (9) Preferably, the method for producing a grain-oriented electrical steel sheet according to (8) above applies magnetic domain control treatment by irradiation with a laser or an electron beam.

[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] FIG. 1 is a plan view of a grain-oriented electrical steel sheet according to an embodiment of the present disclosure; FIG. 2 is a plan view of a normal grain-oriented electrical steel sheet; FIG. 3 is a schematic diagram showing an example of the configuration of a laser irradiation device; and FIG. 4 is a plan view of a raw sheet of the grain-oriented electrical steel sheet. Ａｌｌ 10 is an explanatory diagram of a virtual line VL1 and a virtual line VL2 that are set when calculating |.

[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 |αＡｌｌ |-|α Ｄｒ |≧0.1° is satisfied. |α Ａｌｌ is the average value of the absolute value of the α angle over the entire surface of the grain-oriented electrical steel sheet 1. Ｄｒ | is the average value of the absolute value of the α 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 2 mm intervals 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 called the width of the 180° magnetic domain.

[0016] Suitable examples of the magnetic domain control processed wire 11 are thermal distortion and 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 wire 11 changes 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 α 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] (α angle) In the grain-oriented electrical steel sheet 1 according to this embodiment, the value |α Ａｌｌ | and |α Ｄｒ | satisfies a predetermined relational expression. The α angle is the deviation angle of a crystal grain from the Goss orientation around the axis of the normal direction ND of the rolling surface. It is known that controlling the α angle is effective in controlling the magnetic properties of the grain-oriented electrical steel sheet 1. The deviation angle of a crystal grain from the Goss orientation around the axis of the direction transverse to the rolling direction TD is called the β angle, and the deviation angle of a crystal grain from the Goss orientation around the axis of the rolling direction RD is called the γ angle.

[0020] The inventors compared the iron loss values ​​before and after magnetic domain control treatment of multiple grain-oriented electrical steel sheets 1 with different α angles. As a result, it was found that when magnetic domain control treatment is performed on grain-oriented electrical steel sheets with small α angles, the iron loss reduction effect of magnetic domain control treatment is greater than when magnetic domain control treatment is performed on grain-oriented electrical steel sheets with large α angles. The iron loss changes before and after magnetic domain control treatment, but the α angle does not change. The mechanism by which the iron loss reduction effect of magnetic domain control treatment is greater in regions with small α angles is not clear, but it is thought that the fact that the deviation of the easy axis of magnetization from the rolling direction is small in regions with small α angles, and that hysteresis loss is small, etc., worked advantageously to reduce iron loss by magnetic domain control treatment.

[0021] On the other hand, it is believed that domain control treatment in an area where the α angle is large and the iron loss reduction effect is small will lead to deterioration of noise characteristics due to closure domains.

[0022] Based on the above findings, it was thought that both low iron loss and low noise could be achieved by preferentially performing magnetic domain control treatment on regions with small α angles, i.e., regions where magnetic domain control treatment has a large iron loss reduction effect.

[0023] (|α Ａｌｌ |-|α Ｄｒ |) The grain-oriented electrical steel sheet 1 according to this embodiment has |α Ａｌｌ |-|α Ｄｒ |≧0.1° is satisfied. |α Ａｌｌ is the average value of the absolute value of the α angle over the entire surface of the grain-oriented electrical steel sheet 1. Ｄｒ is an index of the α angle in the magnetic domain control processing line 11. Specifically, |α Ｄｒ is the average value of the absolute values ​​of the α 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 α angles measured at each of the multiple magnetic domain control points VP2, |α Ｄｒ |α Ａｌｌ | and | α Ｄｒ The method for measuring | will be described in detail later.

[0024] Grain-oriented electrical steel sheet 1 is |α Ａｌｌ |-|α Ｄｒ When |≧0.1° is satisfied, the magnetic domain control treatment lines 11 are preferentially provided in the regions 12A where the α angle is small. Generally, a grain-oriented electrical steel sheet 1 has regions 12A where the α angle is small and regions 12B where the α 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 α angle is small. Therefore, |α Ｄｒ | is the average value of the α angle over the entire surface of the grain-oriented electrical steel sheet 1 |α Ａｌｌ On 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 α angle. Therefore, |α Ｄｒ | is the average value of the α angle over the entire surface of the grain-oriented electrical steel sheet 1 |α Ａｌｌ | is substantially the same value.

[0025] (Basic Principle and Effects) The present inventors have determined that |α Ａｌｌ |-|α Ｄｒ It has been found that with the grain-oriented electrical steel sheet 1 in which |α ≧ 0.1° is satisfied, both low iron loss and low noise can be achieved. Ａｌｌ |-|α Ｄｒ This is because in the grain-oriented electrical steel sheet 1 where |≧0.1° is satisfied, the magnetic domain control processing lines 11 are provided in the region 12A where the α angle is small, i.e., the region where the magnetic domain control effect is large, while the magnetic domain control processing is suppressed in the region 12B where the α angle is large, i.e., the region where the magnetic domain control effect is small.

[0026] 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.

[0027] (|α Ａｌｌ |-|α Ｄｒ Preferred numerical range of | Ａｌｌ |-|α Ｄｒ From the viewpoint of improving noise characteristics, it is preferable that | is larger. Ａｌｌ |-|α Ｄｒ It is more preferable that | is, for example, 0.2° or more, 0.5° or more, or 1.0° or more. Ａｌｌ |-|α Ｄｒ |≧0.2°, |α Ａｌｌ |-|α Ｄｒ |≧0.5°, or |α Ａｌｌ |-|α Ｄｒ It is more preferable that |≧1.0° is satisfied, as this achieves a further improvement in noise characteristics.

[0028] |α Ａｌｌ |-|α Ｄｒ The upper limit of | is not particularly limited, but for example, |α Ａｌｌ |-|α Ｄｒ | may be 5.0° or less, 4.0° or less, or 3.0° or less.

[0029] ( | γ Ａｌｌ |-|α Ｄｒ The grain-oriented electrical steel sheet 1 according to this embodiment preferably has a numerical range of |γＡｌｌ |-|α Ｄｒ |≧0.1° is satisfied. |γ Ａｌｌ | is the average value of the absolute value of the γ angle over the entire surface of the grain-oriented electrical steel sheet 1. Ａｌｌ The method for measuring | will be described in detail later. Ａｌｌ |-|α Ｄｒ By satisfying |≧0.1°, further improvement in noise characteristics is achieved.

[0030] (σα Ｄｒ and σα Ａｌｌ The grain-oriented electrical steel sheet 1 preferably has a relationship between σα Ｄｒ <σα Ａｌｌ Satisfies σα Ａｌｌ is the standard deviation of the absolute value of the α angle over the entire surface of the grain-oriented electrical steel sheet 1, and σα Ｄｒ is the standard deviation of the absolute value of the α 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 <σα Ａｌｌ In the grain-oriented electrical steel sheet 1 that satisfies the above requirement, the variation in the α angle at the magnetic domain control point VP2 is smaller than the variation in the α angle overall in the grain-oriented electrical steel sheet 1. That is, in this case, the magnetic domain control treatment is concentrated in the region where the iron loss reduction effect is large, and therefore a further improvement in noise characteristics is achieved.

[0031] (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 / or 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.

[0032] 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.

[0033] (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.

[0034] Known means such as laser irradiation, electron beam irradiation, ion implantation, etc. can be used to introduce 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 to form 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.

[0035] 3 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.

[0036] The strip threading device 515 threads the original strip 2 in the rolling direction RD.

[0037] 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.

[0038] 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 Fig. 3 represents the interval between adjacent magnetic domain control processing lines 11, i.e., the irradiation pitch of the laser beam LB.

[0039] 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 .

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] The control unit 513 also controls the power of the laser beam LB output by the light source device 503 to be turned on and off based on a stress introduction signal representing the magnetic domain control processing region 21 and the rotation angle signal output from the sensor 511. The stress introduction signal is input to the laser irradiation device 500 based on position data obtained in a step of specifying a region where the absolute value of the α angle is 5° or less, which will be described later.

[0045] (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 apparatuses will be referred to as appropriate in the description of the manufacturing method. However, the manufacturing apparatuses referred to below are merely suitable examples for carrying out the manufacturing method of the grain-oriented electrical steel sheet 1 according to this embodiment.

[0046] The manufacturing method of the grain-oriented electrical steel sheet 1 according to this embodiment includes a step of measuring the α angle, a step of identifying regions where the absolute value of the α angle is 5° or less, and a step of applying a magnetic domain control treatment to the regions where the absolute value of the α angle is 5° or less.

[0047] (Step of Measuring the Distribution of α Angle) First, the distribution of α angles is measured on the surface of the original sheet of the grain-oriented electrical steel sheet 1. The α angles are measured by the side reflection Laue method described below.

[0048] The original sheet 2 is the grain-oriented electrical steel sheet 1 before the application of the magnetic domain control treatment.

[0049] (Step of identifying regions where the absolute value of the α angle is 5° or less) Next, based on the distribution of the α angle, regions on the surface of the original sheet where the absolute value of the α angle is 5° or less are identified. Hereinafter, the regions where the absolute value of the α angle is 5° or less are referred to as magnetic domain control processing regions 21.

[0050] (Process for forming magnetic domain control treatment lines) FIG. 4 shows a plan view of an example of the original sheet 2. FIG. 4 shows magnetic domain control treatment areas 21 and non-magnetic domain control treatment areas 22 of the original sheet 2. Magnetic domain control treatment is applied to the dashed lines shown in FIG. 4. The magnetic domain control treatment lines can be formed using known magnetic domain control treatment means. When the magnetic domain control treatment lines 11 are thermal distortions, the magnetic domain control treatment may be performed by irradiation with a laser beam LB using a laser irradiation device 500, or other means such as ion implantation or electron beam irradiation may be used. When the magnetic domain control treatment lines 11 are grooves, the magnetic domain control treatment may be performed using a machining tool.

[0051] 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 the magnetic domain control processing lines 11 into the magnetic domain control processing regions 21 of the original sheet 2. Furthermore, in the non-magnetic domain control processing regions 22 of the original sheet 2, the introduction of the magnetic domain control processing lines 11 is minimized.

[0052] (Operation and Effect) According to the above-described manufacturing method, it is possible to manufacture a steel sheet that achieves both low iron loss and low noise.

[0053] Although the embodiments of the present invention have been described above, the present invention is not limited thereto and can be modified as appropriate without departing from the technical spirit of the invention. Below, more preferred examples of the grain-oriented electrical steel sheet 1 according to this embodiment and its manufacturing method will be described. Unless otherwise specified, the preferred aspects described below are applicable to both the grain-oriented electrical steel sheet 1 and its manufacturing method. The grain-oriented electrical steel sheet according to this 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.

[0054] (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 chemical composition of the grain-oriented electrical steel sheet 1 and the base sheet 2 may be, 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%, S The chemical composition may be as follows: b: 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.

[0055] 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.

[0056] (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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] (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.

[0061] 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.

[0062] (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.

[0063] 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.

[0064] (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.

[0065] 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.

[0066] (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.

[0067] 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.

[0068] The width of the groove (width at the opening) is not particularly limited, but is preferably 10 μm to 300 μm, for example. The groove width may be specified as 20 μm or more, 30 μm or more, or 50 μm or more. The groove width 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.

[0069] (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.

[0070] (Measurement Method) Below, a method for measuring various parameters of the grain-oriented electrical steel sheet 1 according to this embodiment will be described. Measurement of each parameter is performed 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.

[0071] (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.

[0072] 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. 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.

[0073] (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.

[0074] (Method for measuring α and γ angles) The α and γ angles are measured by the side reflection Laue method. The side reflection Laue method is widely known as a method for measuring crystal orientation. However, the α and γ angles are values ​​obtained by rounding off the measured values ​​to one decimal place. In other words, the significant figures for the α and γ angles are rounded to one decimal place.

[0075] (Method for Measuring the Distribution of α Angle) The method for measuring the distribution of α angles on the surface of the original sheet of the grain-oriented electrical steel sheet 1 is as follows: Measurement points are set in a grid pattern on the surface of the original sheet of the grain-oriented electrical steel sheet 1. The α angle is measured at each measurement point.

[0076] Specifically, measurement points are set in a grid pattern at intervals of 2 mm along the rolling direction RD and the direction transverse to the rolling direction TD on the surface of the original sheet of the grain-oriented electrical steel sheet 1. The α angle is measured at each measurement point, and the distribution of α angles on the surface of the original sheet of the grain-oriented electrical steel sheet 1 is measured.

[0077] (|α Ａｌｌ |Calculation method) |α 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. 5. The absolute value of the α angle is measured at each measurement point, and the average value of these is calculated. This average value is called |α Ａｌｌ |It is considered to be.

[0078] Specifically, on the surface of a sample (the rectangular area surrounded by the dashed line in FIG. 5 ) 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 α angle at the intersection VP1 between the virtual lines VL1 and VL2 is measured.

[0079] (|α Ｄｒ |Calculation method) |α ＤｒThe 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 |α 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 α 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 |α Ｄｒ The method for specifying the rolling direction RD and the magnetic domain control treatment line 11, and the method for measuring the α angle are as described above.

[0080] (σα Ａｌｌ (Measuring method) σα Ａｌｌ is |α Ａｌｌ It can be obtained by calculating the standard deviation of the absolute values ​​of the α angles at each measurement point used in calculating |. The method for determining the absolute value of the α angle at each measurement point is as described above.

[0081] (σα Ｄｒ (Measuring method) σα Ｄｒ is obtained by calculating the standard deviation of the absolute value of the α angle at each magnetic domain control point VP2. The method for identifying the magnetic domain control point VP2 is as described above.

[0082] ( | γ Ａｌｌ |Calculation method) |γ Ａｌｌ The outline of the method for calculating | is as follows. On the surface of a sample taken from the grain-oriented electrical steel sheet 1, measurement points are set in a grid pattern at intervals of 2 mm along the rolling direction RD and the direction transverse to the rolling direction TD, as exemplified in FIG. 5 . The absolute value of the γ angle is measured at each measurement point, and the average value of these is calculated. This average value is called |γ Ａｌｌ |It is considered to be.

[0083] (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.

[0084] If a forsterite coating and / or an insulating coating is formed on the grain-oriented electrical steel sheet 1, the forsterite coating and / or the insulating coating can be removed from the grain-oriented electrical steel sheet 1 before analyzing the chemical composition of the grain-oriented electrical steel sheet 1 (i.e., the chemical composition of the base steel sheet). The insulating coating can be removed, for example, by immersing the sample in a sodium hydroxide solution, followed by 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 appropriately adjusted so as not to excessively dissolve the base steel 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. The sample is then immersed in a 10% dilute sulfuric acid solution at 80°C for 4 minutes. Sludge adhering to the surface of the sample is then removed with a rag or the like. The sample is then immersed in a 10% nitric acid solution at room temperature for approximately 10 seconds while being stirred. The forsterite film 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 film 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. The sample is then dried. Next, the sample is immersed in 10% nitric acid at room temperature for approximately 5 seconds while stirring.

[0085] (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.

[0086] (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.

[0087] (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.

[0088] 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.

[0089] 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 in 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. When a measurement point where the tensile stress in any direction is 40 MPa or more is found, the measurement of the tensile stress may be stopped.

[0090] (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.

[0091] The effects of one embodiment of the present invention will be explained in more detail using examples. However, the conditions in the examples are merely examples adopted to confirm the feasibility and effects of the present invention. The present invention is not limited to these examples. Various conditions may be adopted in the present invention as long as they do not deviate from the gist of the present invention and achieve the object of the present invention.

[0092] Grain-oriented electrical steel sheets of the same lot with a sheet thickness of 0.20 mm were used as the 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 been subjected to magnetic domain control treatment were evaluated and 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 satisfy the pass / fail criteria below are underlined.

[0093] The noise and iron loss were evaluated as follows. First, a three-phase transformer core was fabricated by stacking 205 grain-oriented electrical steel sheets with a thickness of 0.20 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 shape of the three-phase transformer core were both 750 mm. The noise and iron loss of these three-phase transformer cores were measured. The measurement conditions were a frequency of 60 Hz and an excitation magnetic flux density of 1.8 T.

[0094] 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 51.00 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.

[0095] 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 1.8 T, as described above. The determined iron loss is shown in Table 2 as the iron loss evaluation results (unit: W / kg) of the grain-oriented electrical steel sheet. Examples with an iron loss evaluation result of 1.270 W / kg or less were determined to be examples in which low iron loss was achieved. Noise evaluation results that were determined to be unacceptable are underlined.

[0096] Furthermore, in grain-oriented electrical steel sheets that have undergone magnetic domain control processing, |α Ａｌｌ |, |α Ｄｒ |, |γ Ａｌｌ |, σα Ａｌｌ and σα 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.

[0097]

[0098]

[0099] 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 magnetic domain control treatment line width. Ａｌｌ |-|α Ｄｒ In Example No. 10, the iron loss was within the acceptable range, but the noise characteristics were unacceptable.

[0100] In Example No. 11, the magnetic domain control processing lines were formed in a dashed line shape. 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 line was randomly varied. The areas where magnetic domain control processing was not performed were randomly provided. As a result, in Example No. 11, |α Ａｌｌ |-|α 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 1.270. In addition, in Example No. 11, the noise characteristics were unacceptable.

[0101] In Example No. 12, the magnetic domain control processing lines were formed in a regular broken 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 broken line was set to a constant value. The areas where magnetic domain control processing was not performed were regularly provided. As a result, in Example No. 12, |α Ａｌｌ |-|α Ｄｒ |≧0.1° was not satisfied. In Example No. 12, both the iron loss and noise characteristics were unacceptable.

[0102] In Example Nos. 13 and 14, the magnetic domain control processing lines were formed in a dashed line shape, as in Example No. 11. That is, in Example Nos. 13 and 14, similar to Example Nos. 1 to 9, an area was provided where the magnetic domain control processing was not performed. However, in Example Nos. 13 and 14, the magnetic domain control processing was applied to an area where the α angle was larger than a predetermined value, which was limited based on the distribution of the α angle. In these examples, |α Ａｌｌ |-|α Ｄｒ |≧0.1° was not satisfied. In Example Nos. 13 and 14, the iron loss was unacceptable.

[0103] On the other hand, in sample numbers 1 to 9, the magnetic domain control process was applied to a region limited based on the distribution of the α angle, where the α angle was equal to or less than a predetermined value. Ａｌｌ |-|α 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.

[0104] According to Example Nos. 1 to 9, |α Ａｌｌ |-|α Ｄｒ It was confirmed that the larger | is, the better the noise characteristics are. Ａｌｌ |-|α Ｄｒ In these examples, the noise characteristics were even better. Ａｌｌ |-|α Ｄｒ |≧0.1° is satisfied, and σα Ｄｒ <σα Ａｌｌ In this example, the noise characteristics were even better.

[0105] The hot-rolled steel sheet of the present disclosure can achieve both low iron loss and low noise, and therefore has high industrial applicability.

[0106] 1 Grain-oriented electrical steel sheet 11 Magnetic domain control processed wire 12A Region with small α angle 12B Region with large α angle RD Rolling direction TD Direction perpendicular to rolling ND Direction normal to rolling surface VL1 |α Ａｌｌ | Imaginary line VL2 parallel to TD for calculation |α Ａｌｌ | Imaginary line VL3 parallel to RD for calculation |α Ｄｒ | Imaginary line VP1 parallel to TD for calculation Intersection of imaginary line VL1 and imaginary line VL2 VP2 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 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 |-|α Ｄｒ |≧0.1° is satisfied, and |α Ａｌｌ | is the average absolute value of the α angle over the entire surface of the grain-oriented electrical steel sheet, and |α Ｄｒ | is the average value of the absolute values ​​of the alpha angles at 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. |α Ａｌｌ |-|α Ｄｒ The grain-oriented electrical steel sheet according to claim 1, wherein | ≧ 0.2° is satisfied.

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

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

5. |γ Ａｌｌ |-|α Ｄｒ |≧0.1° is satisfied, and |γ Ａｌｌ The grain-oriented electrical steel sheet according to any one of claims 1 to 4, wherein | is an average value of the absolute value of the γ angle over the entire surface of the grain-oriented electrical steel sheet.

6. σα Ｄｒ <σα Ａｌｌ and σα Ａｌｌ is the standard deviation of the absolute value of the α angle over the entire surface of the grain-oriented electrical steel sheet, and σα Ｄｒ The grain-oriented electrical steel sheet according to any one of claims 1 to 4, wherein α angle α is the standard deviation of the absolute value of the α 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 lines are grooves.

8. A method for manufacturing grain-oriented electrical steel sheet, comprising the steps of: measuring the distribution of alpha angles on the surface of an original sheet of grain-oriented electrical steel sheet; identifying areas where the absolute value of the alpha angle is 5° or less; and forming magnetic domain control treatment lines in the areas where the absolute value of the alpha angle is 5° or less.

9. The method for producing grain-oriented electrical steel sheet according to claim 8, characterized in that a magnetic domain control treatment is applied by irradiation with a laser or an electron beam.

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