Grain-oriented electrical steel sheet and method for refining magnetic domains therein

Abstract

The present invention provides a grain-oriented electrical steel sheet that can ensure both iron loss characteristics and electrical insulation by combining continuous grooves and discontinuous grooves, and a method for refining magnetic domains therein. [Solution] the magnetic steel sheet includes linear grooves formed on one or both sides thereof in a direction intersecting the rolling direction (X1 direction), and dot-like grooves arranged in a direction intersecting the rolling direction (X2 direction) on one or both sides thereof, the linear grooves and dot-like grooves being formed in a plurality of grooves along the rolling direction, and a distance (D3) between the dot-like grooves in the arrangement direction (X2 direction) of the dot-like grooves is 0.02 to 1.7 times the distance (D2) between the dot-like grooves in the rolling direction, The grooves are characterized in that the interval (D3) between the dot-like grooves in the arrangement direction (X2 direction) is 0.01 to 9.0 mm, and the interval (D2) between the dot-like grooves in the rolling direction is 1.8 to 5.0 mm.

Description

[Technical field]

[0001] The present invention relates to a grain-oriented electrical steel sheet and a method for refining its magnetic domains, and more particularly to a grain-oriented electrical steel sheet that can ensure both iron loss characteristics and electrical insulation by combining continuous grooves and discontinuous grooves, and a method for refining its magnetic domains. [Background technology]

[0002] Grain-oriented electrical steel sheets are used as transformer core materials that utilize the electromagnetic induction phenomenon in dry or oil-immersed environments, so they require coating material adhesion and corrosion resistance in the final finished product. Grain-oriented electrical steel sheets contain a large amount of silicon and are made by melting, casting, hot rolling, hot-rolled sheet annealing, cold rolling, and high-temperature annealing processes to give secondary recrystallized grains with a texture aligned in the same Goss orientation ({110} <001> ) is a functional steel sheet oriented in the direction of the grain. In particular, the magnetic domain refinement technology of grain-oriented electrical steel sheet is a technology that improves the iron loss characteristics by reducing the 180° magnetic domain width in the secondary crystal grains when a magnetic field is applied, and is applied to products with a wide range of thicknesses, from extremely thin products of less than 0.20 mm to thick products of up to 0.30 mm. Among magnetic domain refinement technologies, the technology that can ensure the magnetic domain refinement effect even after stress relief annealing (SRA) is called permanent magnetic domain refinement technology. This permanent magnetic domain refinement technology is used for transformer cores that require molding and heat treatment due to its technical characteristics, and it is necessary to ensure the iron loss characteristics of the core as well as electrical insulation in a dry (wet) environment above room temperature. Summary of the Invention [Problem to be solved by the invention]

[0003] An object of the present invention is to provide a grain-oriented electrical steel sheet that can ensure both iron loss characteristics and electrical insulation by combining continuous grooves and discontinuous grooves, and a method for refining magnetic domains in the same. [Means for solving the problem]

[0004] The grain-oriented electrical steel sheet of the present invention has a grain boundary on one or both sides of the electrical steel sheet, the grain boundary being in a direction intersecting the rolling direction (X 1 Linear grooves formed in the rolling direction (X direction) on one or both sides of the magnetic steel sheet, and grooves in the rolling direction (X direction) on one or both sides of the magnetic steel sheet 2 A plurality of linear grooves and dot-like grooves are formed along the rolling direction, and the dot-like grooves are aligned in the direction (X 2 The interval (D3) between the dot-like grooves in the rolling direction is 0.02 to 1.7 times the interval (D2) between the dot-like grooves in the rolling direction. The direction of the groove dots (X 2 The interval (D3) between the dot-like grooves in the rolling direction may be 0.01 to 9.00 mm, and the interval (D2) between the dot-like grooves in the rolling direction may be 1.8 mm to 5.0 mm. The distance (D1) between the linear grooves in the rolling direction may be 0.2 to 3 times the distance (D2) between the dot-like grooves in the rolling direction. The linear grooves and dot-like grooves are formed on one side of the steel plate. The depth of the linear grooves and dot-like grooves may be 5 to 15% of the thickness of the steel plate. The longitudinal direction of the linear grooves and the arrangement direction of the dotted grooves may form an angle of 75 to 105° with the rolling direction. Two to ten linear grooves are formed discontinuously along the direction perpendicular to the rolling direction of the steel plate. The dotted grooves are aligned in the direction of the dotted groove arrangement (X 2 direction) to diameter (L G ) may be 0.02 mm to 0.4 mm.

[0005] The method for refining magnetic domains in a grain-oriented electrical steel sheet of the present invention includes the steps of preparing a grain-oriented electrical steel sheet, irradiating one or both sides of the grain-oriented electrical steel sheet with a continuous frequency laser in a direction intersecting with the rolling direction to form linear grooves, and irradiating one or both sides of the grain-oriented electrical steel sheet with a pulsed frequency laser in a direction intersecting with the rolling direction to form dot-like grooves. The step of forming linear grooves and the step of forming dot-like grooves are performed a plurality of times, so that the arrangement direction of the dot-like grooves (X 2 The interval (D3) between the dot-like grooves in the rolling direction is 0.02 to 1.7 times the interval (D2) between the dot-like grooves in the rolling direction. In the step of forming the dot-shaped grooves, the laser frequency (F q ) may be 20 kHz to 100 kHz. In the step of forming the dot-like grooves, the duty of the laser may be 50% or less. In the step of forming a linear groove and the step of forming a dot-shaped groove, the energy density of the laser is 0.5 to 2 J / mm 2 may be also possible. In the step of forming the grooves and the step of forming dot-like grooves, the laser beam length in the direction perpendicular to the rolling direction of the steel plate may be 50 to 750 μm, and the laser beam width in the rolling direction of the steel plate may be 10 to 30 μm. Effect of the Invention

[0006] According to the present invention, the coercive force and core loss are improved by forming a combination of continuous and discontinuous grooves, while at the same time improving electrical insulation properties. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a schematic diagram of the rolled surface (ND surface) of the grain-oriented electrical steel sheet of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of the rolled surface (ND surface) of the grain-oriented electrical steel sheet of the present invention. [Diagram 3] 1 is a schematic diagram of a cross section (TD surface) of a grain-oriented electrical steel sheet of the present invention. [Figure 4] FIG. 2 is a schematic diagram of a groove of the present invention. [Diagram 5] FIG. 2 is a schematic diagram showing the shape of a laser beam according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Terms such as first, second and third are used to describe various parts, components, regions, layers and / or sections, but are not limited thereto. These terms are used only to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Thus, a first part, component, region, layer or section described below may be referred to as a second part, component, region, layer or section without departing from the scope of the present invention. The terminology used herein is merely for the purpose of referring to particular embodiments and is not intended to limit the present invention. As used herein, the singular form includes the plural form unless the text clearly indicates otherwise. As used herein, the meaning of "comprising" embodies certain features, regions, integers, steps, operations, elements and / or components and does not exclude the presence or addition of other features, regions, integers, steps, operations, elements and / or components. When we say that a part is "on" another part, it means that it is directly on top of the other part, or that there are other parts between them. In contrast, when we say that a part is "directly on top of" another part, there are no other parts between them.

[0009] Unless otherwise defined, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention belongs. Predefined terms commonly used are additionally interpreted to have a meaning consistent with the relevant technical literature and the presently disclosed content, and are not interpreted in an ideal or very formal sense unless defined. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to exemplary embodiments thereof so that those skilled in the art can easily practice the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments set forth herein.

[0010] 1 and 2 show schematic diagrams of a grain-oriented electrical steel sheet 10 with fine magnetic domains according to the present invention. As shown in FIG. 1 and FIG. 2, the grain-oriented electrical steel sheet 10 of the present invention has a grain boundary 11 or a grain boundary 12 on one side 11 or both sides 11, 12 of the electrical steel sheet, the grain boundary 11 being in a direction (X direction) intersecting the rolling direction (RD direction). 1 A groove 20 is formed on one surface 11 or both surfaces 11, 12 of the magnetic steel sheet in a direction intersecting the rolling direction (X direction). 2 and dot-like grooves 30 arranged in a direction parallel to the surface of the substrate. A plurality of linear grooves 20 and dot-like grooves 30 are formed along the rolling direction, and the arrangement direction of the dot-like grooves (X 2 The interval (D3) between the dot-like grooves in the rolling direction is 0.02 to 1.7 times the interval (D2) between the dot-like grooves in the rolling direction. According to the present invention, the linear grooves 20 and the dotted grooves 30 are simultaneously formed to improve both the magnetic properties and the electrical insulation properties. For example, when the linear grooves 20 or the dotted grooves 30 are formed separately, the magnetic properties and the electrical insulation properties are inferior because the groove depth is increased in order to ensure the magnetic properties. In one embodiment of the present invention, the magnetic properties and the electrical insulation properties are improved simultaneously by combining the linear grooves 20 and the dotted grooves 30.

[0011] In the present invention, the arrangement direction of the dot-like grooves (X 2 Equally important is the ratio (D3) of the spacing between the dotted grooves to the rolling direction (direction) and the spacing between the dotted grooves to the rolling direction (D2) (D3 / D2). If this ratio is too small, the dot-like grooves 30 will have a shape similar to the linear grooves, making it difficult to obtain the effect of simultaneously forming the linear grooves 20 and the dot-like grooves 30. If this ratio is too large, the dot-like grooves 30 will be practically not formed, making it difficult to obtain the effect of simultaneously forming the linear grooves 20 and the dot-like grooves 30. Therefore, the arrangement direction (X 2 The spacing (D3) between the dot-like grooves in the rolling direction (direction) should be 0.02 to 1.7 times the spacing (D2) between the dot-like grooves in the rolling direction. More specifically, it should be 0.30 to 1.7 times. Even more specifically, it should be 0.65 to 1.7 times.

[0012] In FIG. 3, the distance between the linear grooves 20 is indicated as D1, and the distance between the dot-like grooves 30 in the rolling direction is indicated as D2. 2 The distance between the dot-like grooves in the rolling direction (X direction) is indicated as D3. When a plurality of linear grooves 20 and a plurality of dot-like grooves 30 are formed as in FIG. 1, the distance between any linear groove 20 and the linear groove 20 closest to that arbitrary linear groove 20 is defined as the distance between the grooves (D1). Also, the distance between any dot-like groove 30 and the dot-like groove 30 closest to the rolling direction is defined as the distance between the dot-like grooves (D2). Furthermore, as shown in FIG. 3, the distance between any dot-like groove 30 and the arrangement direction (X direction) of the dot-like grooves is indicated as D4. 2 The distance between the dot-like grooves (D2) and the dot-like groove 30 closest to the groove (direction) is defined as the distance between the dot-like grooves (D1).

[0013] In addition, since the linear groove 20 and the dot-like groove 30 have a thickness in the rolling direction (RD direction), the interval is defined based on the center line of the linear groove 20 and the outermost line of the dot-like groove 30. Furthermore, the linear groove 20 and the dot-like groove 30 are substantially parallel, but if they are not parallel, the closest position is considered to be the interval. In addition, when a plurality of linear grooves 20 and a plurality of dot-like grooves 30 are formed, the average value of the respective intervals (D1, D2, D3), that is, the value obtained by dividing the sum of the intervals (D1, D2, D3) by the total number of grooves, satisfies the above-mentioned range.

[0014] The direction of the groove dots (X 2 The spacing (D3) between the dot-like grooves in the arrangement direction (X direction) may be 0.01 to 9.00 mm, and the spacing (D2) between the dot-like grooves in the rolling direction may be 1.8 mm to 5.0 mm. 2 If the distance (D3) between the dot-like grooves in the rolling direction (X direction) is too large, it may occur that only linear grooves 20 are formed instead of dot-like grooves 30, resulting in poor magnetic properties and insulating properties. If the distance (D2) between the dot-like grooves in the rolling direction (X direction) is too small, it may occur that only dot-like grooves 30 are formed instead of linear grooves 20, resulting in poor magnetic properties and insulating properties. Conversely, if the distance (D2) between the dot-like grooves in the rolling direction (X direction) is too large, it may occur that only linear grooves 20 are formed, resulting in poor magnetic properties and insulating properties. More specifically, if the distance (D3) between the dot-like grooves in the rolling direction (X direction) is too large, it may occur that only linear grooves 20 are formed, resulting in poor magnetic properties and insulating properties. 2 The interval (D3) between the dot-like grooves in the rolling direction may be 0.1 to 3.0 mm, and the interval (D2) between the dot-like grooves in the rolling direction may be 2.0 mm to 4.0 mm.

[0015] The interval (D1) between the linear grooves 20 in the rolling direction may be 0.2 to 3.0 times the interval (D2) between the dot-like grooves 30 in the rolling direction. FIG. 3 shows a case where one dot-like groove 30 is formed between linear grooves 20, that is, where D2 / D1 is 1, but the present invention is not limited to this. If the interval (D1) between the linear grooves 20 in the rolling direction is too large, the effect of only dot-like grooves 30 being formed may occur, resulting in poor magnetic properties and insulating properties. Conversely, if the interval (D1) between the linear grooves 20 in the rolling direction is too small, the effect of only the linear grooves 20 being formed may occur, resulting in poor magnetic properties and insulating properties. More specifically, the interval (D1) between the linear grooves 20 in the rolling direction may be 0.5 to 1.5 times the interval (D2) between the dot-like grooves 30 in the rolling direction. More specifically, the distance (D1) between the linear grooves 20 in the rolling direction may be 2 to 15 mm.

[0016] The distance (D1) between the linear grooves 20 in the rolling direction, the distance (D2) between the dot-like grooves 30 in the rolling direction, and the arrangement direction of the dot-like grooves (X 2 The spacing (D3) between the dot-like grooves in the direction (axis direction) may be constant within the entire electrical steel sheet. Specifically, all spacings (D1, D2, D3) within the entire electrical steel sheet may correspond to within 10% of the average spacing (D1, D2, D3). More specifically, all spacings (D1, D2, D3) within the entire electrical steel sheet may correspond to within 1%.

[0017] 1 and 2 show that the linear grooves 20 and the dotted grooves 30 are formed on one surface 11 of the steel plate, but the present invention is not limited thereto. For example, the linear grooves 20 may be formed on one surface 11 of the steel plate, and the dotted grooves 30 may be formed on the other surface 12 of the steel plate. For example, it is possible for D2 / D1 to be smaller than 1. More specifically, the interval (D2) between the dot-like grooves 30 may be 0.2 to 0.5 times the interval (D1) between the linear grooves 20. In this case, as described above, the average value of each interval (D1, D2) satisfies the above-mentioned range. More specifically, the interval (D2) between the dot-like grooves 30 is 0.2 to 0.4 times the interval (D1) between the linear grooves 20. Conversely, it is also possible for D2 / D1 to be greater than 1. More specifically, the distance (D2) between the dot-like grooves 30 may be 2 to 2.8 times the distance (D1) between the linear grooves 20.

[0018] As shown in Fig. 3, the linear groove 20 and the dotted groove 30 refer to portions of the surface of a steel sheet that have been removed by irradiation with a laser, plasma, ion beam, etc. In Fig. 1, the linear groove 20 is depicted as having a wedge shape, and the dotted groove 30 is depicted as having a semicircular shape, but this is merely an example and the grooves may be formed in various shapes such as a rectangle, a trapezoid, a U-shape, a W-shape, etc.

[0019] FIG. 4 shows a schematic diagram of the linear groove 20 or dot-like groove 30 of the present invention. G The groove depth (H G If the groove depth (H G If the groove depth 20 is too deep, the strong laser irradiation may significantly change the structural characteristics of the steel sheet 10, or may form a large amount of hill-ups and spatters, deteriorating the magnetic properties. Therefore, the depth of the linear grooves 20 or dot-like grooves 30 can be controlled within the above-mentioned range.

[0020] As shown in FIG. 4, the solidified alloy layer 40 is formed under the linear groove 20 or the dot-like groove 30. The solidified alloy layer 40 has a thickness (H c) may be 0.1 μm to 3 μm. By appropriately controlling the thickness of the solidified alloy layer 40, the formation of the secondary recrystallization is not affected, and only spike domains are formed in the grooves after the final insulating coating. If the thickness of the solidified alloy layer 40 is excessively thick, it affects the recrystallization during the primary recrystallization, and the Goss integration degree of the secondary recrystallization after the secondary recrystallization annealing is poor, so that the iron loss improvement effect characteristics may not be secured even if the secondary recrystallized steel sheet is irradiated with a laser. The solidified alloy layer includes recrystallization with an average grain size of 1 to 10 μm, and is distinguished from other steel sheet parts. An insulating coating layer 50 is formed on the upper part of the square groove 20 or the dot-like groove 30.

[0021] 1 and 2, the longitudinal direction (X 1 direction) or the arrangement direction of the dot-like grooves 30 (X 2 1 shows that the longitudinal direction (X direction) of the linear groove 20 and the rolling direction (RD direction) form a right angle, but is not limited thereto. 1 direction) or the arrangement direction of the dot-like grooves 30 (X 2 The angle between the grains (direction) may be 75 to 105°. When the above-mentioned angle is formed, it can contribute to improving the iron loss of the grain-oriented electrical steel sheet. More specifically, it may be 75 to 88° or 97 to 105°.

[0022] 1 shows that the linear grooves 20 are continuously formed along the rolling direction (TD direction), but the present invention is not limited thereto. For example, 2 to 10 linear grooves 20 are intermittently formed along the rolling direction (TD direction) of the steel sheet. When the linear grooves 20 are formed intermittently in this manner, it can contribute to improving the iron loss of the grain-oriented electrical steel sheet.

[0023] The dot-like grooves 30 are aligned in the dot-like groove arrangement direction (X 2 direction) to diameter (L G The appropriate diameter (L G ) can contribute to improving the iron loss of grain-oriented electrical steel sheets.2 direction) to diameter (L G ) may be 0.05 mm to 0.3 mm.

[0024] The method for refining magnetic domains in grain-oriented electrical steel sheet of the present invention includes the steps of preparing a grain-oriented electrical steel sheet 10, irradiating one or both sides of the grain-oriented electrical steel sheet 10 with a laser in a direction intersecting the rolling direction (RD direction) to form linear grooves 20 using a continuous frequency laser, and irradiating one or both sides of the grain-oriented electrical steel sheet 10 with a pulsed frequency laser in a direction intersecting the rolling direction to form dot-like grooves 30.

[0025] First, a grain-oriented electrical steel sheet 10 is prepared. The present invention is characterized by a magnetic domain refinement method and the shapes of the linear grooves 20 and dot-like grooves 30 formed, and any grain-oriented electrical steel sheet can be used as the target of magnetic domain refinement. In particular, the effects of the present invention are achieved regardless of the alloy composition of the grain-oriented electrical steel sheet. Therefore, a detailed description of the alloy composition of the grain-oriented electrical steel sheet will be omitted.

[0026] The grain-oriented electrical steel sheet of the present invention may be a grain-oriented electrical steel sheet that has been rolled from a slab to a predetermined thickness by hot rolling and cold rolling, or a grain-oriented electrical steel sheet that has been subjected to primary recrystallization annealing or secondary recrystallization annealing. Next, a laser is irradiated onto one surface 11 of the grain-oriented electrical steel sheet in a direction intersecting the rolling direction (RD direction) to form linear grooves 20. At this time, the laser energy density (Ed) is 0.5 to 2 J / mm 2 If the energy density is too low, the linear grooves 20 are not formed to an appropriate depth, making it difficult to obtain the iron loss improvement effect. Conversely, if the energy density is too high, the linear grooves 20 are formed to an excessively large depth, making it difficult to obtain the iron loss improvement effect.

[0027] FIG. 5 shows a schematic diagram of the shape of the laser beam. In the step of forming the linear groove 20, the laser beam length (L) in the direction perpendicular to the rolling direction (TD direction) of the steel sheet may be 50 to 750 μm. If the beam length (L) in the direction perpendicular to the rolling direction (TD direction) is too short, the laser irradiation time is too short, making it difficult to form an appropriate groove, and making it difficult to obtain an iron loss improvement effect. Conversely, if the beam length (L) in the direction perpendicular to the rolling direction (TD direction) is too long, the laser irradiation time is too long, making it difficult to form a linear groove 20 with an excessively deep depth, making it difficult to obtain an iron loss improvement effect. The laser beam width (W) in the rolling direction (RD direction) of the steel sheet may be 10 to 30 μm. If the beam width (W) is excessively short or long, the width of the linear groove 20 becomes too short or long, and the appropriate magnetic domain refinement effect cannot be obtained. Although the beam shape is shown as an ellipse in FIG. 5, there is no restriction on the shape, such as a sphere or a rectangle.

[0028] The laser may have an output of 10W to 100kW, and may be a Gaussian mode, single mode, or fundamental Gaussian mode laser. It is a TEMoo type beam, and the M2 value may range from 1.0 to 1.2. Next, a pulsed oscillation frequency laser is irradiated onto one or both surfaces of the grain-oriented electrical steel sheet 10 in a direction intersecting the rolling direction (RD direction) to form dot-like grooves 30.

[0029] The above-mentioned step of forming the linear groove 20 and the step of forming the dot-like groove 30 are performed without any time restriction. Specifically, the dot-like groove 30 can be formed after the step of forming the linear groove 20. Also, the linear groove 20 can be formed after the step of forming the dot-like groove 30. Furthermore, the linear groove 20 and the dot-like groove 30 can be formed simultaneously. In the step of forming the dot-like grooves 30, the energy density, shape, output, and type of the laser can be the same as those in the step of forming the linear grooves 20 described above. However, unlike the step of forming the linear groove 20, the step of forming the dot-like groove 30 can be irradiated with a pulsed oscillation frequency laser. Unlike a continuous oscillation frequency laser, a pulsed oscillation frequency laser is a laser in which the output of the laser beam changes over time. Due to this output change, grooves are not formed in the areas where the laser peak energy is low, and grooves are formed only in the areas where the laser peak energy is high, forming the dot-like grooves 30.

[0030] In the step of forming the dot-like grooves 30, the laser frequency (Fq) and the interval (D2) between the dot-like grooves in the rolling direction can satisfy the following formula 1. [Formula 1] 1 1≦ [Fq] / [D2]≦2000 0 (In formula 1, [Fq] represents the laser frequency (Hz) in the step of forming dot-like grooves, and [D2] represents the interval (mm) between dot-like grooves in the rolling direction.) If this ratio is too small, the dot-like grooves 30 will have a shape similar to the linear grooves, making it difficult to obtain the effect of simultaneously forming the linear grooves 20 and the dot-like grooves 30. If this ratio is too large, the dot-like grooves 30 will be substantially not formed, making it difficult to obtain the effect of simultaneously forming the linear grooves 20 and the dot-like grooves 30. More specifically, the value of formula 1 must be 111 to 2000 mm s. The laser frequency (Fq) is 20 to 100 kHz. The dot-like grooves 30 are appropriately formed within the above-mentioned range, and the magnetic property and the insulating property can be improved at the same time.

[0031] The duty of the laser may be 50% or less. The duty is determined by the [output modulation period] (T a) for [time when irradiation was performed at 10% or more of the maximum output (Pmax)] (T b ) ratio (T b / T a Only when the duty is appropriately adjusted can the dot-like grooves 30 be properly formed, thereby improving the magnetic property and the insulating property at the same time. More specifically, the duty may be 2 to 30%.

[0032] The method for refining magnetic domains in a grain-oriented electrical steel sheet according to the present invention may further include a step of forming an insulating coating layer. The step of forming the insulating coating layer is included after the step of preparing the grain-oriented electrical steel sheet, after the step of forming linear grooves, or after the step of forming dot-like grooves. More specifically, the step of forming the insulating coating layer is included after the step of forming linear grooves and dot-like grooves. After forming the linear grooves and dot-like grooves, there is an advantage in that insulating coating can be performed only once when forming the insulating coating layer. The method for forming the insulating coating layer is not particularly limited, and as an example, the insulating coating layer can be formed by applying an insulating coating liquid containing phosphate. As the insulating coating liquid, it is preferable to use a coating liquid containing colloidal silica and a metal phosphate. In this case, the metal phosphate may be Al phosphate, Mg phosphate, or a combination thereof, and the content of Al, Mg, or a combination thereof relative to the weight of the insulating coating liquid may be 15 wt % or more.

[0033] The present invention will be described in more detail with reference to the following examples, which are merely for illustrative purposes and are not intended to limit the scope of the present invention. Experimental Example 1 A grain-oriented electrical steel sheet with a thickness of 0.30 mm was prepared, which had been cold-rolled, and then subjected to primary and secondary recrystallization annealing. A continuous wave laser in Gaussian mode with 1.0 kW.M2=1.07 was irradiated onto this electrical steel sheet to form linear grooves at an angle of 86° with the RD direction. The width (W) of the laser beam was 20 μm, and the length (L) of the laser beam was 600 μm. The energy density of the laser was 1.5 J / mm2 The spacing between the linear grooves was 2.5 mm. The groove depths are shown in Table 1 below.

[0034] A pulsed laser with an average output of 500 W and M2=1.2 was irradiated onto this electromagnetic steel sheet to form dot-shaped grooves at an angle of 86° with the RD direction. The width (W) of the laser beam was 20 μm, and the length (L) of the laser beam was 500 μm. The energy density of the laser was 1.5 J / mm. 2 The interval between the dot-like grooves in the rolling direction (D2), the interval between the dot-like grooves in the arrangement direction (D3), and the groove depth are shown in Table 1 below. After the grooves were formed, the plate was pickled, brushed, and coated with an insulating coating. Table 1 shows examples of the present invention. Thereafter, the material was heat-treated at 840° C., and the coercive force, core loss and insulation properties were measured. The results are summarized in Table 1 below. The coercive force was measured at 50 Hz and 1.7 T. The iron loss is the iron loss value (W) when the magnetic flux density is 1.7 Tesla and the frequency is 50 Hz. 17 / 50 ) was measured. Insulation was measured according to the Franklin Insulation Test method of ASTM A717.

[0035] [Table 1]

[0036] As shown in Table 1, in Examples 1 to 4, the spacing (D2) between the dot-like grooves in the rolling direction and the arrangement direction (X 2 It can be seen that the spacing (D3) between the dot-like grooves in the direction (axis) is appropriately adjusted to simultaneously achieve excellent coercive force, core loss, and insulation properties. In contrast, in Comparative Example 1, 2 It can be seen that the spacing (D3) between the dot-like grooves in the direction (distance between the grooves) is too narrow, which is similar to the case where only linear grooves are formed, and that the coercive force, core loss, and insulation properties are poor.

[0037] In Comparative Example 2, the arrangement direction (X 2 It can be seen that the spacing (D3) between the dot-like grooves in the direction (axis direction) is too wide, resulting in poor coercive force, core loss, and insulation. The present invention is not limited to the embodiments, and can be manufactured in various different forms, and a person skilled in the art to which the present invention pertains will understand that the present invention can be embodied in other specific forms without changing the technical idea or essential features of the present invention. Therefore, it should be understood that the embodiments described above are illustrative in all respects and are not limiting. [Explanation of symbols]

[0038] 10: Grain-oriented electrical steel sheet, 11: One side of the steel plate, 12: The other side of the steel plate, 20: Linear groove, 30: Dotted groove, 40: solidified alloy layer, 50: Insulating coating layer

Claims

1. On one or both sides of the electromagnetic steel sheet, a direction intersecting the rolling direction (X １ A linear groove formed in the direction of the groove; The magnetic steel sheet is provided on one or both sides with a direction intersecting the rolling direction (X ２ and dot-like grooves arranged in a direction parallel to the surface of the substrate, The linear grooves and the dot-like grooves are formed in a plurality of grooves along the rolling direction, The arrangement direction of the dot-like grooves (X ２ a distance (D3) between dot-like grooves in the rolling direction (direction) is 0.02 to 1.7 times a distance (D2) between dot-like grooves in the rolling direction (direction).

2. The arrangement direction of the dot-like grooves (X ２ 2. The grain-oriented electrical steel sheet according to claim 1, wherein a distance (D3) between the dot-like grooves in the rolling direction (direction) is 0.01 to 9.0 mm, and a distance (D2) between the dot-like grooves in the rolling direction is 1.8 to 5.0 mm.

3. The grain-oriented electrical steel sheet according to claim 1 or 2, characterized in that the distance (D1) between the linear grooves in the rolling direction is 0.2 to 3 times the distance (D2) between the dot-like grooves in the rolling direction.

4. The grain-oriented electrical steel sheet according to any one of claims 1 to 3, characterized in that the linear grooves and the dot-like grooves are formed on one surface of the steel sheet.

5. The grain-oriented electrical steel sheet according to any one of claims 1 to 4, characterized in that the depth of the linear grooves and the dot-like grooves is 5 to 15% of the thickness of the steel sheet.

6. The grain-oriented electrical steel sheet according to any one of claims 1 to 5, characterized in that the longitudinal direction of the linear grooves and the arrangement direction of the dot-like grooves form an angle of 75 to 105° with the rolling direction.

7. The grain-oriented electrical steel sheet according to any one of claims 1 to 6, characterized in that 2 to 10 of the linear grooves are intermittently formed along a direction perpendicular to the rolling direction of the steel sheet.

8. The dot-like grooves are aligned in a direction (X ２ The grain-oriented electrical steel sheet according to any one of claims 1 to 7, characterized in that a diameter in the direction perpendicular to the grain boundary (i.e., the grain boundary direction) is 0.02 to 0.4 mm.

9. preparing a grain-oriented electromagnetic steel sheet; irradiating a continuous wave laser in a direction intersecting with the rolling direction on one or both sides of the grain-oriented electrical steel sheet to form linear grooves; and irradiating a pulsed oscillation frequency laser in a direction intersecting a rolling direction on one or both sides of the grain-oriented electrical steel sheet to form dot-shaped grooves; performing the step of forming the linear groove and the step of forming the dot-like groove a plurality of times to form a plurality of the linear grooves and the dot-like grooves along the rolling direction; The arrangement direction of the dot-like grooves (X ２ a spacing (D3) between dot-like grooves in the rolling direction (direction) is 0.02 to 1.7 times a spacing (D2) between dot-like grooves in the rolling direction.

10. In the step of forming the dot-shaped grooves, the laser frequency (F ｑ 10. The method for refining magnetic domains in a grain-oriented electrical steel sheet according to claim 9, wherein the frequency of the magnetic field is 0.5 kHz to 2.5 kHz.

11. 11. The method according to claim 9, wherein the dot-shaped grooves are formed at a laser duty of 50% or less.

12. In the step of forming the linear groove and the step of forming the dot-like groove, the energy density of the laser is 0.5 to 2 J / mm ２ The method for refining magnetic domains in a grain-oriented electrical steel sheet according to any one of claims 9 to 11,

13. The method for refining magnetic domains in a grain-oriented electrical steel sheet according to any one of claims 9 to 12, characterized in that, in the step of forming the linear grooves and the step of forming the dot-like grooves, the laser has a beam length of 50 to 750 μm in a direction perpendicular to the rolling of the steel sheet, and a beam width of 10 to 30 μm in the rolling direction of the steel sheet.

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