technical field
[One]
It relates to a grain-oriented electrical steel sheet and a method for manufacturing a grain-oriented electrical steel sheet. More specifically, it relates to a grain-oriented electrical steel sheet and a method of manufacturing a grain-oriented electrical steel sheet in which magnetic and hot-rolling properties are improved by controlling the thickness of the insulating film layer formed on the groove according to the thickness of the forsterite layer.
background
[2]
In order for the grain-oriented electrical steel sheet to be used as a high-efficiency transformer core, it is desirable to use an iron core material with excellent iron loss and insulating properties of the electrical steel sheet to minimize the loss of electronic devices.
[3]
The grain-oriented electrical steel sheet orients the secondary recrystallized grain texture in the Goss direction ({110}<001>) along the rolling direction through the steelmaking, hot rolling, cold rolling and annealing processes, so that the iron loss characteristic in the rolling direction is superior to that in the rolling right angle direction. It is a functional steel sheet for electronic devices with anisotropy characteristics. In particular, the magnetic domain refining technology in grain-oriented electrical steel sheet is a technology to improve iron loss by reducing the 180˚ domain width within the secondary crystal grains when a magnetic field is applied, and is applied to products of various thicknesses. It is necessary to minimize the stray field by improving the insulating properties when the plates are laminated. That is, when the leakage magnetic flux increases due to poor insulation properties of the low iron loss steel sheet lamination, it is not preferable because the excitation voltage of the iron core increases and it is necessary to conduct electricity more than the design magnetic flux density.
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[4]
An object of the present invention is to provide a grain-oriented electrical steel sheet and a method for manufacturing a grain-oriented electrical steel sheet. More specifically, an object of the present invention is to provide a grain-oriented electrical steel sheet and a method of manufacturing a grain-oriented electrical steel sheet, which have improved magnetism and hot-rolling properties by controlling the thickness of the insulating film layer formed on the groove according to the thickness of the forsterite layer.
means of solving the problem
[5]
In the grain-oriented electrical steel sheet according to an embodiment of the present invention, a groove including a bottom and a side is located on the surface of the electrical steel sheet, a metal oxide layer is located on the groove, an insulating layer is located on the metal oxide layer, and the steel sheet is a top groove in which the thickness of the metal oxide layer located on the bottom and on the side is greater than 0.5 μm, and a defect groove having a defect in which the thickness of the metal oxide layer located on the side or bottom is 0.5 μm or less, wherein the defect groove is located on the top groove The thickness of the insulating layer is 0.5 μm to 4.0 μm, and the insulating layer positioned on the defect groove has a thickness of 1.5 μm to 10 μm.
[6]
The defect groove includes a side defect groove having a defect portion on the side and a bottom defect groove having a defect portion on the bottom, the insulating layer located on the side defect groove having a thickness of 1.5 to 6 μm, the bottom defect groove The insulating layer positioned thereon may have a thickness of 2.0 to 10 μm.
[7]
The insulating layer positioned on the side of the top groove may have a thickness of 0.5 μm to 2.0 μm, and the insulating layer positioned on the bottom of the top groove may have a thickness of 1.0 μm to 4.0 μm.
[8]
The insulating layer positioned on the side of the side defect groove may have a thickness of 1.5 µm or more and less than 4.0 µm, and the insulating layer positioned on the bottom of the side defect groove may have a thickness of 4.0 µm to 6.0 µm.
[9]
The insulating layer positioned on the side of the bottom defect groove may have a thickness of 2.0 µm or more and less than 5.0 µm, and the insulating layer positioned on the bottom of the bottom defect groove may have a thickness of 5.0 µm to 10.0 µm.
[10]
By dividing sections in the vertical direction of rolling of the steel sheet, the thickness of the insulating layer may be formed for each section according to the thickness of the metal oxide layer positioned on the groove included in each section.
[11]
By dividing sections in the rolling direction of the steel sheet, the thickness of the insulating layer may be formed for each section according to the thickness of the metal oxide layer positioned on the groove included in each section.
[12]
The bottom portion of the groove may be a depth portion of 0.7 or more of the total depth of the groove, and the side portion of the groove may be a depth portion less than 0.7 of the total depth of the groove.
[13]
Defective grooves may be 10 to 80% with respect to the grooves of the entire steel sheet.
[14]
The grooves are formed in a linear shape, and 2 to 10 grooves may be intermittently located with respect to the vertical direction of rolling.
[15]
The groove is formed in a linear shape, and may form an angle of 75 to 88° with respect to the vertical direction of rolling.
[16]
The depth of the groove may be 3 to 30 μm.
[17]
A method of manufacturing a grain-oriented electrical steel sheet according to an embodiment of the present invention comprises the steps of manufacturing a cold-rolled sheet; forming a groove including a bottom portion and a side portion on the surface of the cold-rolled sheet; forming a metal oxide layer by applying an annealing separator to the cold-rolled sheet and annealing at a high temperature; Measuring the thickness of the metal oxide layer positioned on the bottom and the side of the groove, and adjusting the viscosity of the insulating layer forming composition according to the measured metal oxide layer thickness and applying the coating to form an insulating layer.
[18]
In the step of forming the insulating layer, when the thickness of the metal oxide layer located on the bottom and the side is a normal groove of more than 0.5 μm, the viscosity of the insulating layer forming composition is adjusted to more than 80 cps, and the In the case of a defect groove having a defect portion having a thickness of 0.5 μm or less of the metal oxide layer, the viscosity of the insulating layer forming composition may be adjusted to 80 cps or less.
[19]
In the step of forming the insulating layer, when the thickness of the metal oxide layer located on the side is a side defect groove having a defect part of 0.5 μm or less, the viscosity of the insulating layer forming composition is adjusted to 20 to 80 cps, and the metal located on the bottom part When the oxide layer is a bottom defect groove having a defect portion having a thickness of 0.5 μm or less, the viscosity of the insulating layer forming composition may be adjusted to less than 20 cps.
[20]
In the step of measuring the thickness of the metal oxide layer, dividing the section in the rolling vertical direction, measuring the thickness, and in the step of forming the insulating layer, dividing the section in the rolling vertical direction, the insulating layer forming composition can be applied.
[21]
In the step of measuring the thickness of the metal oxide layer, dividing the section in the rolling direction, measuring the thickness, and in the step of forming the insulating layer, dividing the section in the rolling direction, the insulating layer forming composition may be applied.
Effects of the Invention
[22]
According to one embodiment of the present invention, even when a defect occurs in the metal oxide layer, by forming the insulating layer to an appropriate thickness, insulation can be improved.
[23]
In addition, according to one embodiment of the present invention, even when no defects occur in the metal oxide layer, the space factor can be improved by forming the insulating layer to an appropriate thickness.
Brief description of the drawing
[24]
1 is a schematic diagram of a rolled surface (ND surface) of a grain-oriented electrical steel sheet according to an embodiment of the present invention.
[25]
2 is a schematic diagram of a cross section of a groove according to an embodiment of the present invention.
[26]
3 is a schematic diagram of a cross-section of a normal groove according to an embodiment of the present invention.
[27]
4 is a schematic diagram of a cross section of a side defect groove according to an embodiment of the present invention.
[28]
5 is a schematic diagram of a cross section of a bottom defect groove according to an embodiment of the present invention.
[29]
6 shows a case in which sections are divided in the vertical direction of rolling.
[30]
7 shows a case in which sections are divided in the rolling direction.
Modes for carrying out the invention
[31]
Terms such as first, second and third are used to describe, but are not limited to, various parts, components, regions, layers and/or sections. These terms are used only to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Accordingly, 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.
[32]
The terminology used herein is for the purpose of referring to specific embodiments only, and is not intended to limit the present invention. As used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite. As used herein, the meaning of "comprising" specifies a particular characteristic, region, integer, step, operation, element and/or component, and the presence or absence of another characteristic, region, integer, step, operation, element and/or component. It does not exclude additions.
[33]
When a part is referred to as being “on” or “on” another part, it may be directly on or on the other part, or the other part may be involved in between. In contrast, when a part refers to being “directly above” another part, the other part is not interposed therebetween.
[34]
Although not defined otherwise, all terms including technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Commonly used terms defined in the dictionary are further interpreted as having a meaning consistent with the related technical literature and the presently disclosed content, and unless defined, are not interpreted in an ideal or very formal meaning.
[35]
Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein.
[36]
1 shows a schematic diagram of a grain-oriented electrical steel sheet 10 that has been refined into magnetic domains according to an embodiment of the present invention.
[37]
As shown in FIG. 1 , the grain-oriented electrical steel sheet 10 according to an embodiment of the present invention has a groove 20 including a bottom portion 21 and a side portion 22 on the surface of the electrical steel sheet.
[38]
As shown in FIG. 3 , the metal oxide layer 30 and the insulating layer 40 are sequentially disposed on the groove 20 .
[39]
The metal oxide layer 30 is formed through the reaction of the annealing separator and the oxide layer on the surface of the steel sheet in the secondary recrystallization annealing process during the manufacturing process of the grain-oriented electrical steel sheet. Although it is ideal that the metal oxide layer 30 be uniformly formed, the metal oxide layer 30 is affected by various process variables, so it is not easy to uniformly generate it. Furthermore, when the groove 20 is formed in the steel sheet as in an embodiment of the present invention, it is very difficult to form a uniform metal oxide layer 30 on the groove 20 .
[40]
Since the metal oxide layer 30 is widely known, a detailed description thereof will be omitted. For example, the metal oxide layer 30 may be made of forsterite (Mg 2 SiO 4 ).
[41]
As a result, in the actual process, a defect in which the thickness of the metal oxide layer 30 positioned on the groove 20 is partially thin occurs. In this case, the insulation in the defective groove becomes very weak. In addition, it may be considered to form the insulating layer 40 with a thick thickness over the entire steel sheet on the assumption that a defect groove will be formed, but in this case, the space factor deteriorates.
[42]
According to the thickness of the metal oxide layer 30, in an embodiment of the present invention, a normal groove and a defect groove are divided, and the insulating layer 40 having a different thickness is formed in each, thereby improving the insulation and the space factor at the same time.
[43]
Specifically, the normal groove and the defective groove may be classified as follows.
[44]
The top groove means a groove in which the thickness of the metal oxide layer 30 positioned on the bottom portion 21 and the side portion 22 is greater than 0.5 μm. An example of a normal groove is shown in FIG. 3 . As described in FIG. 3 , the metal oxide layer 30 is uniformly formed on the bottom part 21 and the side part 22 , and there is no defect part having a thickness of 0.5 µm or less.
[45]
On the other hand, the defect groove means a groove having a defect portion (d) in which the thickness of the metal oxide layer positioned on the side portion 22 or the bottom portion 21 is 0.5 μm or less. Examples of defective grooves are shown in FIGS. 4 and 5 . As shown in FIGS. 4 and 5 , a defect portion d is present on the side portion 22 or the bottom portion 21 . The defect groove can be subdivided into a side defect groove in which a defect d exists in the side 22 and a bottom defect groove in which a defect d is present in the bottom 21 . A side defect groove is illustrated in FIG. 4 and a bottom defect groove is illustrated in FIG. 5 . In an embodiment of the present invention, when the defective portion d is present in both the bottom portion 21 and the side portion 22, it is classified as a bottom portion defective groove.
[46]
Since the metal oxide layer 30 is appropriately formed in the top groove, the thickness of the insulating layer 40 does not need to be thick. Rather, when the thickness of the insulating layer 40 is too thick, the space factor may deteriorate. The insulating layer positioned on the top groove may have a thickness of 0.5 μm to 4.0 μm. More specifically, the insulating layer positioned on the top groove may have a thickness of 0.5 μm or more and less than 1.5 μm. More specifically, the insulating layer positioned on the top groove may have a thickness of 0.7 μm to 1.2 μm.
[47]
In the defect groove, since defects exist in the metal oxide layer 30 , the thickness of the insulating layer 40 should be thick. Specifically, the insulating layer positioned on the defect groove may have a thickness of 1.5 to 10 μm. More specifically, the insulating layer positioned on the defect groove may have a thickness of 3 to 7 μm. The thickness of the insulating layer 40 on the groove 20 may be different inside the groove 20 , and in an embodiment of the present invention, the thickness of the insulating layer 40 means an average thickness with respect to the groove width.
[48]
Among the defect grooves, in the bottom defect groove, the insulating layer 40 must be thicker to obtain proper insulating properties. Specifically, the insulating layer 40 positioned on the side defect groove may have a thickness of 1.5 to 6 μm, and the insulating layer 40 positioned on the bottom defect groove may have a thickness of 2.0 to 10 μm. More specifically, the insulating layer 40 positioned on the side defect groove may have a thickness of 2 to 4 μm, and the insulating layer 40 positioned on the bottom defect groove may have a thickness of 5 to 7 μm.
[49]
Even in the normal groove and the defective groove, the thickness of the bottom part 21 being thicker than the side part 22 helps to improve insulation. Specifically, the thickness of the insulating layer on the side portion 21 may be less than 20% of the depth of the groove (H). The thickness of the insulating layer on the bottom part 21 may be 20 to 80% of the depth of the groove (H).
[50]
Specifically, the insulating layer positioned on the side 22 of the normal groove may have a thickness of 0.5 to 2.0. More specifically, it may be 0.5 μm or more and less than 1.5 μm. The insulating layer positioned on the bottom portion 21 of the top groove may have a thickness of 1.5 μm to 4.0 μm. More specifically, it may be 1.5 to 2.0 μm. More specifically, the insulating layer positioned on the side 22 of the top groove may have a thickness of 0.6 μm to 1.0 μm, and the insulating layer positioned on the bottom 21 of the top groove may have a thickness of 1.7 μm to 1.8 μm. there is.
[51]
The insulating layer positioned on the side 22 of the side defect groove may have a thickness of 1.5 μm or more and less than 4.0 μm, and the insulating layer positioned on the bottom of the side defect groove may have a thickness of 4.0 μm to 6.0 μm. More specifically, the insulating layer positioned on the side 22 of the side defect groove may have a thickness of 1.5 μm to 3.0 μm, and the insulating layer positioned on the bottom of the side defect groove may have a thickness of 5.0 μm to 6.0 μm. .
[52]
In addition, the insulating layer located on the side 22 of the bottom defect groove has a thickness of 2.0 μm or more and less than 5.0 μm, and the insulating layer located on the bottom 11 of the bottom defect groove has a thickness of 5.0 μm. to 10.0 μm. More specifically, the insulating layer located on the side 22 of the bottom defect groove has a thickness of 2.0 μm to 3.0 μm, and the insulating layer located on the bottom 11 of the bottom defect groove has a thickness of 7.0 μm. to 9.0 μm.
[53]
The bottom 21 and side 22 of the groove are described in detail in FIG. 2 . More specifically, the bottom portion 21 of the groove is a depth portion of 0.7 or more of the total depth H of the groove, and the side portion 22 of the groove means a depth portion of less than 0.7 of the total depth H of the groove.
[54]
By dividing sections in the vertical direction of rolling of the steel sheet, the thickness of the insulating layer may be formed for each section according to the thickness of the metal oxide layer 30 positioned on the groove included in each section. Since the thickness of the metal oxide layer 30 is changed by process variables, it is not rapidly changed along the vertical rolling direction of the steel sheet. Therefore, even if the thickness of the insulating layer 40 located on the groove included in each section is divided into sections in the vertical direction of rolling of the steel sheet to be unified, it is not a big problem. At this time, the thickness of the insulating layer 40 is determined according to the thickness of the metal oxide layer 30 of any groove existing in the section.
[55]
In addition, by dividing the section in the rolling direction of the steel sheet, it is also possible to form the thickness of the insulating layer for each section according to the thickness of the metal oxide layer located on the groove included in each section. Even if sections are divided in the rolling direction of the steel sheet to unify the thickness of the insulating layer 40 located on the grooves included in each section, it is not a big problem. At this time, the thickness of the insulating layer 40 is determined according to the thickness of the metal oxide layer 30 of any groove existing in the section.
[56]
6 and 7 illustrate a case in which the thickness of the insulating layer 40 is formed by dividing sections in the rolling direction or in the rolling direction. By selecting an arbitrary groove (dotted line circle) in the section, the thickness of the metal oxide layer on the groove (dotted line circle) can be measured and reflected in the thickness of the insulating layer 40 of all grooves in the section.
[57]
The thickness of the insulating layer may be formed for each section according to the thickness of the metal oxide layer positioned on the groove included in each section by dividing the section in the vertical direction or the rolling direction.
[58]
The number of defective grooves may be 20 to 80% with respect to the grooves of the entire steel sheet. As described above, it is ideal that the defect groove does not occur, but in the actual process, the defect groove may occur in the above range. In this case, the defect groove refers to a ratio of the bottom defect groove and the side defect groove.
[59]
The grooves are formed in a linear shape, and 2 to 10 grooves may be intermittently located with respect to the vertical rolling direction. 1 illustrates a case in which four are intermittently formed.
[60]
The groove is formed in a linear shape, and may form an angle of 75 to 88° with respect to the vertical direction of rolling. Iron loss can be further improved through proper angle formation.
[61]
The depth of the groove may be 3 to 30 μm. Iron loss can be further improved through an appropriate depth.
[62]
A method of manufacturing a grain-oriented electrical steel sheet according to an embodiment of the present invention comprises the steps of manufacturing a cold-rolled sheet; forming a groove including a bottom portion and a side portion on the surface of the cold-rolled sheet; forming a metal oxide layer by applying an annealing separator to the cold-rolled sheet and annealing at a high temperature; Measuring the thickness of the metal oxide layer positioned on the bottom and the side of the groove, and adjusting the viscosity of the insulating layer forming composition according to the measured metal oxide layer thickness and applying the coating to form an insulating layer.
[63]
First, a cold-rolled sheet is manufactured. The alloy component and manufacturing method of the cold-rolled sheet can be variously applied to the alloy component and manufacturing method of the grain-oriented electrical steel sheet, and is not particularly limited.
[64]
As an example, based on 100% by weight of the total composition of the cold-rolled sheet, O: 0.0020 to 0.0080%, Si: 2.5 to 6.0%, C: 0.02 to 0.10%, Al: 0.02 to 0.04%, Mn: 0.05 to 0.20% , N: 0.002 to 0.012%, S: 0.001% to 0.010%, and P: 0.01 to 0.08%, the balance being Fe and impurities (Ni, Cr, Sb and Rare Earth metal total weight within 0.1%) may include
[65]
Next, a groove including a bottom portion and a side portion is formed on the surface of the cold-rolled sheet.
[66]
A method of forming the groove may be applied in various ways, and is not particularly limited. For example, the groove may be formed through laser irradiation. In this case, a laser beam having an average power of several kilowatts may be used. Since the laser beam is widely known, a detailed description thereof will be omitted.
[67]
An annealing separator is applied to the cold-rolled sheet and annealed at a high temperature to form a metal oxide layer. Since the annealing separator and high-temperature annealing are widely known in the field of grain-oriented electrical steel, a detailed description will be omitted. For example, as an annealing separator, MgO may be used. During the high-temperature annealing process, MgO may combine with the oxide layer on the surface of the steel sheet to form forsterite.
[68]
Measure the thickness of the metal oxide layer located on the bottom and sides of the groove. At this stage, the grooves are divided into normal grooves and defective grooves. The defect groove can be further subdivided into a side defect groove and a bottom defect groove.
[69]
The thickness measurement method is not limited and can be applied variously, and as an example, an optical microscopy method, an electron microscopy method, a GDS method, etc. may be used.
[70]
Next, the insulating layer is formed by adjusting the viscosity of the insulating layer-forming composition according to the measured thickness of the metal oxide layer.
[71]
Specifically, in the step of forming the insulating layer, when the thickness of the metal oxide layer located on the bottom and the side is a normal groove of more than 0.5 μm, the viscosity of the insulating layer forming composition is adjusted to more than 80 cps, and the side or bottom part In the case of a defect groove having a defect portion having a thickness of 0.5 μm or less of the metal oxide layer disposed thereon, the viscosity of the insulating layer forming composition may be adjusted to 80 cps or less.
[72]
Various methods may be used to adjust the viscosity of the insulating layer-forming composition. For example, the viscosity may be controlled by adjusting the amount of solvent added in the composition. Alternatively, the viscosity can be controlled by changing the type of composition in the composition. That is, inorganic particles may be included in the composition, and in this case, the viscosity may be controlled by controlling the specific surface area of ​​the inorganic particles. In addition, various methods can be used without limitation.
[73]
The above-mentioned viscosity is a viscosity based on a temperature of 25 °C.
[74]
When the viscosity is low, it becomes possible to form a thick insulating layer on the groove. Conversely, if the viscosity is high, it is possible to form a thin insulating layer on the groove. In one embodiment of the present invention, the thickness of the insulating layer may be adjusted by using the viscosity of the composition for forming the insulating layer. Since the thickness of the insulating layer is the same as that described above, overlapping description will be omitted.
[75]
In the case of a side defect groove in which the thickness of the metal oxide layer located on the side is 0.5 μm or less, the viscosity of the insulating layer forming composition is adjusted to 20 to 80 cps, and the thickness of the metal oxide layer located on the bottom is 0.5 μm or less in the bottom defect In the case of a groove, the viscosity of the insulating layer forming composition may be adjusted to less than 20 cps.
[76]
In the step of measuring the thickness of the metal oxide layer, dividing the section in the rolling vertical direction, measuring the thickness, and in the step of forming the insulating layer, dividing the section in the rolling vertical direction, the insulating layer forming composition can be applied.
[77]
In the step of measuring the thickness of the metal oxide layer, dividing the section in the rolling direction, measuring the thickness, and in the step of forming the insulating layer, dividing the section in the rolling direction, the insulating layer forming composition may be applied.
[78]
Various types of the insulating layer forming composition may be used without limitation. For example, an insulating layer-forming composition including silica and a metal phosphate may be used.
[79]
Hereinafter, the present invention will be described in more detail through examples. However, these examples are only for illustrating the present invention, and the present invention is not limited thereto.
[80]
Example 1
[81]
A cold-rolled sheet having a thickness of 0.27 mm was prepared. The cold-rolled sheet was irradiated with a 1.5kW Gaussian mode continuous wave laser to form a 15㎛ deep groove. After groove formation, decarburization annealing was performed, MgO was applied, and high temperature annealing was performed.
[82]
While performing the process, the process was performed so that all the metal oxide layers formed on the grooves in the specimen had defects at the bottom.
[83]
Then, the viscosity was adjusted to 15 cps, and an insulating layer forming composition containing silica and Al phosphate was applied to form an insulating layer.
[84]
Insulation layer thickness, iron loss (W 17/50 ) and leakage current were measured and shown in Table 1 below.
[85]
Example 2
[86]
The same procedure as in Example 1 was performed, except that the metal oxide layer formed on the groove in the specimen had defects on the side thereof.
[87]
An insulating layer was formed by adjusting the viscosity to 50 cps.
[88]
Insulation layer thickness, iron loss (W 17/50 ) and leakage current were measured and shown in Table 1 below.
[89]
Comparative Example 1
[90]
The same procedure as in Example 1 was performed, but the viscosity was adjusted to 100 cps to form an insulating layer.
[91]
Insulation layer thickness, iron loss (W 17/50 ) and leakage current were measured and shown in Table 1 below.
[92]
[Table 1]
[93]
As shown in Table 1, even when the bottom defect groove and the side defect groove are formed, when the insulating layer is formed to an appropriate thickness, it can be confirmed that the core loss is excellent and the insulation is excellent. On the other hand, as in Comparative Example 1, despite the formation of the bottom defect groove, when the insulating layer is formed thin, it can be seen that the core loss and insulation is inferior.
[94]
The present invention is not limited to the embodiments, but can be manufactured in various different forms, and those of ordinary skill in the art to which the present invention pertains can use other specific forms without changing the technical spirit or essential features of the present invention. It will be appreciated that this may be practiced. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.
[95]
[Explanation of code]
[96]
10: grain-oriented electrical steel sheet,
[97]
20: Groove,
[98]
21: bottom,
[99]
22: side,
[100]
30: metal oxide layer;
[101]
40: insulating layer
Claims
[Claim 1]
On the surface of the electrical steel sheet, a groove including a bottom and a side is located, a metal oxide layer is located on the groove, an insulating layer is located on the metal oxide layer, and the steel sheet is a metal oxide located on the bottom and the side a defect groove having a top groove in which the thickness of the layer is greater than 0.5 μm, a defect portion in which a thickness of a metal oxide layer located on a side or a bottom portion is 0.5 μm or less, wherein the insulating layer located on the top groove has a thickness of 0.5 μm to 4.0 μm, and the insulating layer positioned on the defect groove has a thickness of 1.5 to 10 μm.
[Claim 2]
The insulating layer according to claim 1, wherein the defect groove comprises a side defect groove having a defect portion on a side thereof and a bottom defect groove having a defect portion on a bottom portion, and the insulating layer located on the side defect groove has a thickness of 1.5 to 6㎛, the insulating layer located on the bottom defect groove is a grain-oriented electrical steel sheet having a thickness of 2.0 to 10㎛.
[Claim 3]
The directional electricity according to claim 1, wherein the insulating layer positioned on the side of the top groove has a thickness of 0.5 μm to 2.0 μm, and the insulating layer positioned on the bottom of the top groove has a thickness of 1.0 μm to 4.0 μm. grater.
[Claim 4]
The insulating layer according to claim 2, wherein the insulating layer located on the side of the side defect groove has a thickness of 1.5 μm or more and less than 4.0 μm, and the insulating layer located on the bottom of the side defect groove has a thickness of 4.0 μm to 6.0 ㎛ grain-oriented electrical steel sheet.
[Claim 5]
3. The insulating layer according to claim 2, wherein the insulating layer located on the side of the bottom defect groove has a thickness of 2.0 μm or more and less than 5.0 μm, and the insulating layer located on the bottom of the bottom defect groove has a thickness of 5.0 μm. to 10.0㎛ grain-oriented electrical steel sheet.
[Claim 6]
The grain-oriented electrical steel sheet according to claim 1, wherein a section is divided in a vertical direction for rolling of the steel sheet, and the thickness of the insulating layer is formed for each section according to the thickness of the metal oxide layer located on the groove included in each section.
[Claim 7]
The grain-oriented electrical steel sheet according to claim 1, wherein by dividing sections in the rolling direction of the steel sheet, the thickness of the insulating layer is formed for each section according to the thickness of the metal oxide layer located on the groove included in each section.
[Claim 8]
The grain-oriented electrical steel sheet according to claim 1, wherein the bottom portion of the groove is a depth portion of 0.7 or more of the total depth of the groove, and the side portion of the groove is a depth portion of less than 0.7 of the total depth of the groove.
[Claim 9]
The grain-oriented electrical steel sheet according to claim 1, wherein the number of defective grooves is 10 to 80% with respect to the grooves of the entire steel sheet.
[Claim 10]
The grain-oriented electrical steel sheet according to claim 1, wherein the grooves are formed in a linear shape, and 2 to 10 grooves are intermittently located with respect to the vertical rolling direction.
[Claim 11]
The grain-oriented electrical steel sheet according to claim 1, wherein the grooves are formed in a linear shape and form an angle of 75 to 88° with respect to the vertical direction of rolling.
[Claim 12]
The grain-oriented electrical steel sheet according to claim 1, wherein the groove has a depth of 3 to 30 μm.
[Claim 13]
manufacturing a cold-rolled sheet; forming a groove including a bottom portion and a side portion on the surface of the cold-rolled sheet; forming a metal oxide layer by applying an annealing separator to the cold-rolled sheet and annealing at a high temperature; Grain-oriented electrical steel sheet comprising the steps of measuring the thickness of the metal oxide layer located on the bottom and the side of the groove, and forming the insulating layer by applying by adjusting the viscosity of the insulating layer forming composition according to the measured metal oxide layer thickness manufacturing method.
[Claim 14]
The method according to claim 13, wherein in the step of forming the insulating layer, when the thickness of the metal oxide layer located on the bottom and the side is a normal groove of more than 0.5 μm, the viscosity of the insulating layer forming composition is adjusted to more than 80 cps, In the case of a defect groove having a defect portion having a thickness of 0.5 μm or less of a metal oxide layer located on a side or a bottom portion, a method of manufacturing a grain-oriented electrical steel sheet for controlling the viscosity of the insulating layer forming composition to 80 cps or less.
[Claim 15]
14. The method of claim 13, wherein in the step of forming the insulating layer, in the case of a side defect groove having a defect portion having a thickness of 0.5 μm or less of the metal oxide layer located on the side, the viscosity of the insulating layer forming composition is adjusted to 20 to 80 cps, and , In the case of a bottom defect groove having a defect portion having a thickness of 0.5 μm or less of a metal oxide layer located on the bottom portion, a method of manufacturing a grain-oriented electrical steel sheet for controlling the viscosity of the insulating layer forming composition to less than 20 cps.
[Claim 16]
14. The method of claim 13, wherein in the step of measuring the thickness of the metal oxide layer, dividing the section in the rolling vertical direction to measure the thickness, and in the step of forming the insulating layer, dividing the section in the rolling vertical direction, forming the insulating layer A method of manufacturing a grain-oriented electrical steel sheet applying a composition.
[Claim 17]
14. The method of claim 13, wherein in the step of measuring the thickness of the metal oxide layer, dividing the section in the rolling direction to measure the thickness, and in the step of forming the insulating layer, dividing the section in the rolling direction, the insulating layer forming composition Method for manufacturing grain-oriented electrical steel sheet to be coated.