Specification
Title of invention: grain-oriented electrical steel sheet
Technical field
[0001]
The present invention relates to grain-oriented electrical steel sheets.
The present application claims priority based on Japanese Patent Application No. 2018-14874 filed in Japan on January 31, 2018, the contents of which are incorporated herein by reference.
Background technology
[0002]
The iron core is widely used as a magnetic core for transformers, reactors, noise filters, and the like. As a material for such an iron core, a grain-oriented electrical steel sheet having a high magnetic flux density is used by increasing the degree of integration of the so-called Goth orientation. In the steel sheet having such an increased degree of integration, the crystal grains become large, and as a result, the width of the magnetic domain becomes wide. Since iron loss increases in grain-oriented electrical steel sheets with a wide magnetic domain, reduction of iron loss is one of the important issues from the viewpoint of improving efficiency.
Subdivision of magnetic domains (magnetic domain control) has been put into practical use as a means for reducing iron loss of grain-oriented electrical steel sheets. Examples of the magnetic domain control method include non-destructive magnetic domain control in which minute strains are formed on the steel sheet surface and destructive magnetic domain control in which minute grooves are formed on the steel sheet surface.
[0003]
　Here, the above-mentioned iron cores are roughly classified into stacked iron cores and wound iron cores. Winding iron cores manufactured by bending grain-oriented electrical steel sheets are usually manufactured through an annealing process to relieve stress generated during bending, so heat resistance is required for the grain-oriented electrical steel sheets used. Be done. Since minute strain introduced on the surface of the steel sheet by non-destructive magnetic domain control disappears in the annealing process (has no heat resistance), the surface of the steel sheet that does not disappear in the annealing process is used in the production of wound iron cores. It is common to use a destructive magnetic domain control material that forms minute grooves.
[0004]
　As a grain-oriented electrical steel sheet in which minute grooves are formed on the surface of the steel sheet, for example, in Patent Document 1, the cold-rolled steel sheet after the final cold rolling is erased even after undergoing a final processing step in a direction intersecting the rolling direction. A method for manufacturing a low iron loss unidirectional electromagnetic steel sheet, which is characterized by forming a non-grooving groove, is disclosed.
Further, in Patent Document 2, the average diameter of the crater formed on the surface of the grain-oriented electrical steel sheet is 100 to 200 μm, the depth is 10 to 30 μm, the hole is drilled 3 to 10 mm in the rolling direction, and the crater is drilled in the width direction of the steel sheet. Disclosed is a grain-oriented electrical steel sheet having traces of continuous patterns uniformly arranged so as to have a ratio of 1.0 or less and having a flat back surface of the steel sheet.
In Patent Document 3, after finish annealing, a part of the film on one side or both sides of the grain-oriented electrical steel sheet to which an insulating film is applied is removed in a linear or dotted manner to expose the base iron, and then a neutral salt solution is applied. A method for producing a low iron loss directional electromagnetic steel sheet is disclosed, which comprises forming a groove having a depth of 5 to 40 μm in an exposed portion of the ground steel on at least one side of the steel sheet by electrolytic etching used.
Prior art literature
Patent documents
[0005]
Patent Document 1: Japanese Patent Application Laid-Open No. 5-247538
Patent Document 2: Japanese Patent Application Laid-Open No. 7-220913
Patent Document 3: Japanese Patent Application Laid-Open No. 2001-316896
Outline of the invention
Problems to be solved by the invention
[0006]
In the electromagnetic steel sheet described in the prior art document, the effect of improving iron loss is maintained even after the annealing step for relieving stress, but in order to obtain a high effect of reducing iron loss, it is perpendicular to the rolling direction of the steel sheet surface. When a continuous and linear groove is formed in the steel sheet, there is a problem that the steel sheet is broken along the groove due to the bending process when the wound steel core is manufactured. Therefore, usually, a continuous and linear groove is formed at a certain angle with respect to the rolling direction to prevent the steel sheet from breaking due to bending.
However, if the angle with respect to the rolling direction and the direction perpendicular to the rolling direction becomes large, the magnetic domain control effect weakens, so there is a trade-off relationship that the iron loss worsens, and the direction has a high level of repeated bending characteristics and low iron loss. It was difficult to obtain electrical steel sheets.
[0007]
　The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a heat-resistant grain-oriented electrical steel sheet having both low iron loss and excellent repeated bending characteristics at a high level.
Means to solve problems
[0008]
　The present invention employs the following means in order to solve the above problems and achieve the object.
(1) The directional electromagnetic steel sheet according to one aspect of the present invention is a directional electromagnetic steel sheet having a grooved steel sheet surface, and has a length of 5 to 10 mm on a straight line intersecting the rolling direction on the steel sheet surface. It has two or more broken lines including the groove having a length, and in the broken line including the groove, the grooves are arranged at equal intervals, and the length of the groove: the length ratio of the non-groove is 1: 1 to 1. The range is .5: 1.
[0009]
(2) In the grain-oriented electrical steel sheet according to (1) above, the broken lines including the adjacent grooves are parallel, the interval is in the range of 2.0 to 20 mm, the length A of the grooves and the non-grooves. The relationship between the length B of the above and the amount of overlap C between the grooves in the direction perpendicular to the broken line including the groove may satisfy the following equation (1).
　　　　　　　　　　C = (AB) / 2 ... (1)
[0010]
(3) In the grain-oriented electrical steel sheet according to (1) or (2) above, the broken line including the groove may have an angle in the range of 75 to 105 ° with respect to the rolling direction.
Effect of the invention
[0011]
According to the present invention, it is possible to provide a heat-resistant grain-oriented electrical steel sheet having both low iron loss and excellent repeated bending characteristics at a high level.
A brief description of the drawing
[0012]
FIG. 1A is a schematic view showing an example of a grain-controlled grain-controlled electrical steel sheet of the present invention.
[Fig. 1B] Fig. 1B is a schematic diagram comparing the groove pattern of this electrical steel sheet and the groove pattern of a conventional general electrical steel sheet on the same scale.
[Fig. 2] Fig. 2 is a schematic diagram showing an example of a wound iron core.
FIG. 3 is a schematic view of an electromagnetic steel sheet whose magnetic domain is controlled by forming a broken line having a non-groove length equal to that of the groove at right angles to the rolling direction.
FIG. 4 is a schematic view of an electromagnetic steel sheet whose magnetic domain is controlled by forming a broken line whose groove length is longer than the non-groove length at right angles to the rolling direction.
FIG. 5 is a schematic view showing an angle of a broken line having a groove with respect to the rolling direction.
Mode for carrying out the invention
[0013]
Hereinafter, the grain-oriented electrical steel sheet according to the present embodiment will be described in detail.
It should be noted that, as used in the present specification, terms such as "parallel", "vertical", "same", and "right angle" and values ​​of length and angle, etc., which specify the shape and geometric conditions and their degrees, are used. Is not bound by the strict meaning, but should be interpreted including the range in which similar functions can be expected.
[0014]
The grain-oriented electrical steel sheet according to the present embodiment (hereinafter, abbreviated as the grain-oriented electrical steel sheet) is a grain-oriented electrical steel sheet having a grooved steel sheet surface, and is on a straight line intersecting the rolling direction on the steel sheet surface. It has two or more broken lines including the groove having a length of 5 to 10 mm, and the grooves are arranged at equal intervals in the broken line including the groove, and the length of the groove: the length ratio of the non-groove is 1. It is characterized in that it is in the range of: 1 to 1.5: 1.
[0015]
As described above, for the purpose of reducing iron loss while maintaining heat resistance, a technique for subdividing magnetic domains and improving iron loss by forming grooves on the surface of the material steel sheet has been known. However, an electromagnetic steel sheet in which a continuous and linear groove is formed at right angles to the rolling direction of the material steel sheet and magnetic domain control is performed can obtain a high effect of improving iron loss, but it is possible to obtain a high iron loss improvement effect by bending when manufacturing a rolled iron core. , There was a problem that the steel plate was broken. FIG. 2 (A) shows a schematic view of the wound steel core, and FIG. 2 (B) shows a schematic diagram of the grain-oriented electrical steel sheet constituting one layer of the wound steel core. As shown in FIG. 2, the wound steel core is usually manufactured by laminating grain-oriented electrical steel sheets that have been bent at right angles to the rolling direction. This is because in a conventional electrical steel sheet in which magnetic domain control is performed by forming continuous (solid line) grooves in the perpendicular direction, stress is concentrated in the grooves and the steel sheet is easily broken.
Therefore, conventionally, knowing that the magnetic domain control effect is weakened, a continuous and linear groove is formed at a certain angle with respect to the rolling direction to break the steel sheet by bending. It was suppressed.
[0016]
The present inventors have formed a groove for controlling a magnetic domain on the surface of a grain-oriented electrical steel sheet in a discontinuous broken line shape with a specific pattern, thereby having both low iron loss and high repeated bending characteristics. It was found that More specifically, the present inventors have found that reduction of iron loss and improvement of repeated bending characteristics can be achieved at the same time when the groove formation pattern on the surface of the steel sheet satisfies at least the following two conditions.
(Condition 1) The surface of the steel sheet has two or more broken lines including grooves having a length of 5 to 10 mm on a straight line intersecting the rolling direction.
(Condition 2) The grooves are arranged at equal intervals in the broken line including the grooves, and the length ratio of the grooves to the non-grooves is in the range of 1: 1 to 1.5: 1.
As described above, by forming a groove having a specific length in a broken line shape, stress is concentrated on the groove portion due to bending to prevent the steel sheet from breaking, and the steel sheet is continuously and linearly used. It has become possible to realize iron loss equivalent to that of grain-oriented electrical steel sheets with various grooves.
[0017]
Hereinafter, this electrical steel sheet will be described in detail.
[0018]
1. 1. Basic configuration of the
electromagnetic steel sheet The electromagnetic steel sheet is not particularly limited as long as it is a steel sheet having a 180 ° magnetic wall parallel to the rolling direction, but the orientation of the crystal grains in the steel sheet is highly advanced to the {110} <001> orientation. It is an integrated steel sheet, and preferably has excellent magnetic properties in the rolling direction. From the grain-oriented electrical steel sheets known as the main electrical steel sheets, they can be appropriately selected and used according to the required performance. Hereinafter, an example of a preferable mother steel plate will be described, but the mother steel plate is not limited to the following examples.
[0019]
　The chemical composition of the base steel plate is not particularly limited, but for example, in mass%, Si: 0.8% to 7%, C: higher than 0% and 0.085% or less, acid-soluble Al: 0. % To 0.065%, N: 0% to 0.012%, Mn: 0% to 1%, Cr: 0% to 0.3%, Cu: 0% to 0.4%, P: 0% to 0.5%, Sn: 0% to 0.3%, Sb: 0% to 0.3%, Ni: 0% to 1%, S: 0% to 0.015%, Se: 0% to 0. It preferably contains 015% and the balance is composed of Fe and impurities. The chemical composition of the mother steel sheet is a preferable chemical component for controlling the crystal orientation to the Goss texture integrated in the {110} <001> orientation. Among the elements in the base steel sheet, Si and C are basic elements, and acid-soluble Al, N, Mn, Cr, Cu, P, Sn, Sb, Ni, S, and Se are selective elements. Since these selective elements may be contained according to the purpose, it is not necessary to limit the lower limit value, and the lower limit value may be 0%. Further, even if these selective elements are contained as impurities, the effect of the present invention is not impaired. In the base steel sheet, the balance of the basic element and the selective element is composed of Fe and impurities.
The term "impurity" means an element that is inevitably mixed with ore as a raw material, scrap, or the manufacturing environment when the base steel sheet is industrially manufactured.
In addition, electrical steel sheets generally undergo purification annealing during secondary recrystallization. In the purification annealing, the inhibitor-forming element is discharged to the outside of the system. In particular, the concentrations of N and S are significantly reduced to 50 ppm or less. Under normal purified annealing conditions, it reaches 9 ppm or less, further 6 ppm or less, and if purified annealing is sufficiently performed, it reaches a level that cannot be detected by general analysis (1 ppm or less).
The chemical composition of the base steel sheet may be measured by a general method for analyzing steel. For example, the chemical composition of the mother steel sheet may be measured using ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectroscopy). Specifically, for example, a 35 mm square test piece is obtained from the center position of the mother steel plate after the coating is removed, and under the conditions based on the calibration curve prepared in advance by Shimadzu ICPS-8100 or the like (measuring device). It can be identified by measuring. In addition, C and S may be measured by using the combustion-infrared absorption method, and N may be measured by using the inert gas melting-thermal conductivity method.
[0020]
The method for producing the grain steel sheet is not particularly limited, and a conventionally known method for producing a grain-oriented electrical steel sheet can be appropriately selected. As a preferable specific example of the manufacturing method, for example, the slab is heated to 1000 ° C. or higher to perform hot rolling, and then hot-rolled sheet is annealed as necessary, and then once or twice with intermediate annealing sandwiched. A cold-rolled steel sheet is obtained by the above cold-rolling, and the cold-rolled steel sheet is heated to 700 to 900 ° C. in a wet hydrogen-inert gas atmosphere to be decarburized and annealed, and if necessary, further nitrided and annealed to 1000 ° C. Examples include a method of finish annealing depending on the degree.
The thickness of the base steel plate is not particularly limited, but is preferably 0.1 mm or more and 0.5 mm or less, and more preferably 0.15 mm or more and 0.40 mm or less.
[0021]
A film may be formed on the surface of the main steel sheet (the surface of the base steel sheet). Examples of such a film include a glass film formed on the mother steel sheet. The glass coating has, for example, one or more oxides selected from forsterite (Mg 2 SiO 4 ), spinel (Mg Al 2 O 4 ), and cordierite (Mg 2 Al 4 Si 5 O 16 ). A coating may be mentioned.
The thickness of the coating film is not particularly limited, but is preferably 0.5 μm or more and 3 μm or less.
[0022]
2. 2. Magnetic domain control (groove pattern of this electrical steel sheet) In the
present embodiment, magnetic domain control is performed by forming a broken line groove on the surface of the main steel sheet (surface of the main steel sheet) in a specific pattern. FIG. 1A shows an example of this electrical steel sheet whose magnetic domain is controlled by forming grooves in a broken line shape.
As shown in FIG. 1A, the electrical steel sheet has two or more broken lines including grooves having a length of 5 to 10 mm on a straight line intersecting the rolling direction on the surface of the steel sheet.
If the length of the groove exceeds 10 mm, stress tends to be concentrated in the groove, and the steel plate tends to break. On the other hand, if the length of the groove is less than 5 mm, it is difficult to process so that the overlap (overlap amount) between the grooves is minimized in the direction perpendicular to the broken line including the groove, as will be described later, due to the problem of processing accuracy. Therefore, the effect of reducing iron loss may not be sufficiently obtained. Therefore, the length of the groove is 5 to 10 mm, preferably 7 to 8 mm.
The width of the groove is not particularly limited, but is usually in the range of 10 to 500 μm and may be in the range of 20 to 400 μm in order to efficiently control the magnetic domain.
The depth of the groove is also not particularly limited, but in order to efficiently control the magnetic domain, it is usually in the range of 2 to 50 μm, and may be in the range of 4 to 40 μm.
There is no particular limitation as long as there are two or more broken lines including the groove, but it is preferable that the steel sheet has a specific pattern described below.
[0023]
In the broken line including the groove, the grooves are arranged at equal intervals, and the length: non-groove length ratio of the grooves is 1: 1 to 1.5: 1. If the non-groove length exceeds 1 times the groove length, the effect of improving iron loss is not sufficient, and if the groove length exceeds 1.5 times the non-groove length, the repeated bending characteristics are sufficiently high. Cannot be obtained. The groove length: non-groove length ratio is preferably 1: 1. The term "non-groove" means a region between adjacent grooves on a single broken line, that is, a region where no groove exists.
[0024]
As described above, the length of the groove in this electrical steel sheet is 5 mm to 10 mm, but this length is very short as compared with the length of a conventional general groove. The length of a conventional general groove is on the order of several hundred mm such as about 200 mm. FIG. 1B is a schematic view in which the groove pattern of the main electromagnetic steel sheet and the groove pattern of a conventional general electromagnetic steel sheet are compared on the same scale. As shown in FIG. 1B, when the groove pattern of the main electromagnetic steel sheet and the groove pattern of the conventional general electrical steel sheet are compared on the same scale, it can be easily understood that both patterns are clearly different. ..
As described above, the length of the conventional groove is set in order to obtain the iron loss reduction effect, and is not set for the purpose of improving the repeated bending characteristics. Therefore, a comparison on the order of several hundred mm is made. It was a large number. On the other hand, as a result of diligent research not only to obtain the iron loss reducing effect but also to improve the repeated bending characteristics, the present inventors have determined that the iron loss is reduced when at least the following two conditions are satisfied. They found that it was possible to improve the repeated bending characteristics at the same time.
(Condition 1) The surface of the steel sheet has two or more broken lines including grooves having a length of 5 to 10 mm on a straight line intersecting the rolling direction.
(Condition 2) The grooves are arranged at equal intervals in the broken line including the grooves, and the length ratio of the grooves to the non-grooves is in the range of 1: 1 to 1.5: 1.
　Therefore, it is possible for a person skilled in the art to form a groove having an extremely short length of 5 to 10 mm like this electrical steel sheet based on the conventional groove forming technique which has no interest in improving the repeated bending characteristics. It is not something that can be easily conceived.
[0025]
In the electromagnetic steel plate, the broken lines including the adjacent grooves are parallel and the interval is in the range of 2.0 to 20 mm, and the groove length A, the non-groove length B, and the broken line including the groove are included. It is preferable that the relationship between the groove and the amount of overlap C between the grooves in the direction perpendicular to the above satisfies the following equation (1).
　　　　　　　　　C = (AB) / 2 ... (1) When the
adjacent broken lines are not parallel to each other and the distance between the adjacent broken lines is out of the above range, the effect of improving the iron loss is not sufficient. In order to obtain an excellent iron loss improving effect, the distance between adjacent broken lines is preferably in the range of 2 to 20 mm, and more preferably in the range of 5 to 10 mm.
[0026]
Further, in the adjacent broken line, it is preferable that the amount of overlap C between the grooves is the minimum in the direction perpendicular to the broken line. When the relationship between the groove length A, the non-groove length B, and the amount of overlap C between the grooves in the direction perpendicular to the broken line including the groove satisfies the above equation (1), the overlap between the grooves. The quantity C is the minimum. Even if the amount of overlap C between adjacent broken-line grooves is not the minimum (when the relationship between A, B, and C does not satisfy the above equation (1)), the repeated bending characteristics are not affected, but it is sufficient. Iron loss cannot be reduced.
Hereinafter, referring to FIGS. 3 and 4, the groove is divided into a case where the non-groove length B is the same as the groove length A and a case where the non-groove length B is shorter than the groove length A. A groove pattern in which the overlap amount C between the two is the minimum will be described.
[0027]
(1) When the non-groove length B is the same as the groove length A In
FIG. 3, a broken line having the non-groove length B the same as the groove length A is formed at right angles to the rolling direction. A schematic diagram of an electromagnetic steel plate whose magnetic domain is controlled is shown.
In the broken line having the grooves shown in FIGS. 3 (b) and 3 (c), the overlap amount C between the grooves of the adjacent broken lines in the perpendicular direction is not the minimum, and all or a part of the grooves overlap. In this way, in the portion where the grooves overlap each other, the distance between the grooves becomes too narrow, and the iron loss worsens. Further, since the area of ​​the portion having no groove, that is, the portion not controlled by the magnetic domain is increased, the iron loss is exacerbated.
Therefore, even if the groove length A: non-groove length B ratio is 1: 1, iron loss cannot be sufficiently reduced.
In the broken line having the grooves shown in FIG. 3A, the overlap amount C between the grooves of the adjacent broken lines in the perpendicular direction is the minimum (C = 0), and the grooves do not overlap each other. In this case, the optimum condition is maintained for the spacing between the grooves, and the area of ​​the portion having no groove whose magnetic domain is not controlled is minimized, so that the effect of reducing iron loss is high. Therefore, it is possible to sufficiently reduce the iron loss.
[0028]
(2) When the groove length A is longer than the non-groove length B In
FIG. 4, a broken line having a non-groove length B shorter than the groove length A is formed at right angles to the rolling direction to control the magnetic domain. A schematic diagram of the rolled electromagnetic steel plate is shown. In FIG. 4, the groove length A: non-groove length B ratio is 1.5: 1.
In the broken line having the grooves shown in FIGS. 4 (b), 4 (c) and 4 (d), the overlap amount C between the adjacent broken lines in the perpendicular direction is not the minimum, and all or one of the grooves is not the minimum. The parts overlap. In this way, in the portion where the grooves overlap each other, the distance between the grooves becomes too narrow, and the iron loss worsens. Further, since the area of ​​the portion having no groove that is not controlled by the magnetic domain becomes large, the iron loss is exacerbated. Therefore, even if the groove length: non-groove length ratio is 1.5: 1, iron loss cannot be sufficiently reduced.
In the broken line having grooves shown in FIG. 4A, some of the grooves overlap each other, but the amount of overlap C between the adjacent broken lines in the perpendicular direction is the minimum. In this case, the optimum distance between the grooves is maintained, and since there is no portion having no groove whose magnetic domain is not controlled, the effect of reducing iron loss is high. Therefore, it is possible to sufficiently reduce the iron loss.
[0029]
In this electrical steel sheet, the broken line including the groove preferably has an angle in the range of 75 to 105 ° with respect to the rolling direction. FIG. 5 schematically shows the angle of the broken line having a groove with respect to the rolling direction. The more the angle of the broken line having the groove with respect to the rolling direction deviates from 90 °, the less stress is concentrated in the groove, so that the repeated bending characteristic is excellent, but the magnetic domain control effect is weakened, so that the iron loss becomes high.
This electrical steel sheet is more than a conventional electrical steel sheet having grooves that exist continuously and linearly in the width direction of the steel sheet surface by appropriately selecting the angle of the broken line having grooves with respect to the rolling direction within the range of 75 to 105 °. , The performance required for the wound steel core can be achieved at a high level.
At 75 ° and 105 °, the difference from the case where the angle with respect to the rolling direction is 90 ° is the same as 15 °, so that the characteristics as a steel sheet are the same.
[0030]
The method of forming the groove in the electrical steel sheet is not particularly limited, and for example, a method such as etching, gear pressing, or laser irradiation can be used.
Above all, it is preferable to use a special polygon mirror that reflects the laser beam and irradiates the steel plate because the groove can be efficiently formed. Polygon mirrors are usually in the shape of 6-8 prisms, but in the special polygon mirrors, several to dozens of comb-shaped grooves are formed on the side surfaces of the rectangle forming the prism. The bottom surface of the groove has an inclination of several degrees.
When a groove is formed in a steel sheet during the manufacturing process of the electromagnetic steel sheet, there is no particular limitation on in which process the groove is formed. Grooves may be formed in the cold-rolled steel sheet, or grooves may be formed in the cold-rolled steel sheet so as not to break the insulating film.
[0031]
3. 3. Use of heat-resistant grain-oriented electrical steel sheet
This electrical steel sheet is particularly suitable as a material for wound steel cores because it has heat resistance and has excellent iron loss and repeated bending characteristics.
Example
[0032]
Hereinafter, the technical contents of the present invention will be further described with reference to examples of the present invention. The conditions in the examples shown below are examples of conditions adopted for confirming the feasibility and effect of the present invention, and the present invention is not limited to these conditions. Further, the present invention can adopt various conditions as long as the gist of the present invention is not deviated and the object of the present invention is achieved.
The mother steel sheet used in this example is a steel sheet having a plate width of 1050 mm and a plate thickness of 0.23 mm manufactured as described below, and is characterized by containing 3.01% Si in Fe as a chemical component. Further, the width and depth of the grooves formed by laser treatment after the cold rolling process are common to all steel sheets.
[0033]
1. 1. Manufacture of grain-oriented electrical steel sheet
(Example 1)
(1) The
main component of the grain steel sheet contains Si with a mass fraction of 3.01% and Mn with a mass fraction of 0.058%, and the balance has a chemical component consisting of Fe and impurities. Molten steel was supplied to a continuous casting machine to continuously produce slabs. Subsequently, after heating the obtained slab, hot rolling was performed on the slab to obtain a hot-rolled steel sheet having a thickness of 1.6 mm.
The obtained hot-rolled steel sheet was annealed under the condition of heating at 900 ° C. for 30 seconds, and then cold-rolled with the surface pickled to obtain a cold-rolled steel sheet having a thickness of 0.23 mm. It was.
Grooves were formed on the obtained cold-rolled steel sheet under the conditions described below.
After the groove was formed, it was decarburized and annealed by heating in a wet hydrogen-inert gas atmosphere at 800 ° C., and further nitrided and annealed.
An annealing separator containing magnesia (MgO) as a main component is applied to the surface of the grooved steel sheet (the surface of the oxide layer), and the temperature condition of 1100 ° C. is applied to the steel sheet coated with the annealing separator. Heat treatment was carried out for 20 hours to obtain a finished annealed steel sheet.
The obtained finished annealed steel sheet is coated with an insulating coating liquid containing colloidal silica and phosphate and heat-treated at 840 ° C. to finally obtain a plate width of 1050 mm and a plate thickness of 0.23 mm. Therefore, the grain-oriented electrical steel sheet of Example 1 in which the grooves shown in Table 2 were formed was obtained.
(2) Magnetic domain control (groove formation)
For the formation of the broken line-shaped grooves on the cold-rolled steel sheet, a special polygon mirror obtained by processing a general polygon mirror that reflects laser light and irradiates the steel sheet was used. Polygon mirrors are usually in the shape of 6-8 prisms, but the special polygon mirrors used have several to dozens of comb-shaped grooves formed on the sides of the rectangle that forms the prism. The bottom of this groove has an inclination of several degrees. Using such a special polygon mirror, a dashed groove (groove length 10 mm, non-groove length 10 mm, depth 20 μm, width) is formed on the surface of a cold-rolled steel sheet at an angle of 90 ° with respect to the rolling direction. 100 μm) was formed at 2 mm intervals.
[0034]
(Examples 2 to 17)
Electrical steel sheets of Examples 2 to 17 were obtained in the same manner as in Example 1 except that the grooves were formed under the conditions shown in Tables 2 to 6.
[0035]
(Comparative Example 1) It
was used as a grain-oriented electrical steel sheet of Comparative Example 1 without forming a groove in the mother steel sheet used in Example 1.
[0036]
(Comparative Examples 2 to 24)
Electrical steel sheets of Comparative Examples 2 to 24 were obtained in the same manner as in Example 1 except that the grooves were formed under the conditions shown in Tables 1 to 6.
[0037]
2. 2. Evaluation of iron loss For
samples of grain-oriented electrical steel sheets (width 30 mm x length 300 mm, 1 set 0.5 kg) of Examples and Comparative Examples, a single sheet of electrical steel sheet using the H coil method described in JIS C 2556. The measurement by the magnetic characteristic test was carried out under the conditions of a frequency of 50 Hz and a magnetic flux density of 1.7 T, and the iron loss value W17 / 50 (W / Kg) of the grain-oriented electrical steel sheets of Examples and Comparative Examples was determined.
From the obtained iron loss value, the amount of iron loss improvement obtained was calculated using the following formula (2).
Equation (2)
Iron loss improvement amount (%) = (base steel sheet iron loss value-test steel sheet iron loss value) / mother steel sheet iron loss value x 100
[0038]
3. 3. Evaluation of
Repeated Bending Characteristics The method for evaluating repeated bending characteristics was measured by the method shown in the item of mechanical test described in JIS C 2550. The sample is a rectangle of 30 x 300 mm, performed at room temperature (20 ± 15 ° C), sandwiched between rounded metal testers with a radius of 5 mm, the test piece bent 90 ° to one side along the entire length, and then the original. Return to the position (this is referred to as one bend), and then in the same manner, return to the 90 ° bending original position (this is referred to as two bends). This number of times is counted, and when the crack passes through the back surface of the test piece, the number of times of bending is not counted and the process ends.
From the obtained minimum number of breaks, the ratio of the minimum number of breaks obtained was calculated using the following formula (3). In this test, the minimum fracture frequency ratio of 8.1% or more is an index of whether or not it can be used as a material for a wound iron core.
Equation (3)
Minimum number of fractures ratio (%) = Minimum number of fractures of test steel sheet / Minimum number of fractures of mother steel sheet x 100 The
average number of fractures ratio obtained by using the following formula (4) from the obtained average number of fractures. Was calculated.
Equation (4)
Average number of breaks (%) = Average number of breaks of test steel sheet / Average number of breaks of mother steel sheet x 100
[0039]
4. Evaluation results The
results are summarized in Tables 1 to 6.
[0040]
[table 1]

[0041]
As shown in Table 1, in the mother steel sheet of Comparative Example 1 in which magnetic domain control was not performed, the minimum number of fractures was 37 and there was no problem with the repeated bending characteristics, but the iron loss value was extremely high at 0.85 W / kg. Further, in the grain-oriented electrical steel sheet of Comparative Example 2 in which magnetic domain control was performed by forming continuous (solid line) grooves in the direction perpendicular to the rolling direction at intervals of 5 mm, the amount of improvement in iron loss was 14.12. There is no problem as high as%, but the minimum number of breaks ratio is 2.7% and the repeated bending characteristics are extremely poor. In the grain-oriented electrical steel sheet of Comparative Example 3 in which magnetic domain control was performed by forming solid linear grooves at intervals of 2.5 mm in the direction perpendicular to the rolling direction (90 °), the amount of improvement in iron loss was 7. Since it deteriorated to 06%, it is considered that the effect of improving the iron loss is optimal when the grooves are formed at intervals of 5 mm.
As shown in Comparative Examples 3 to 7, solid linear grooves were formed at 95 ° (85 °), 100 ° (80 °), 105 ° (75 °), and 105 ° (75 °) with respect to the rolling direction for the purpose of improving the repeated bending characteristics. When formed at an angle of 110 ° (70 °), the steel sheet of Comparative Example 6 in which a solid line groove was formed at an angle of 105 ° had an iron loss improvement amount of 12.47% and a minimum fracture frequency ratio of 8. At 0.1%, the balance between iron loss and repeated bending characteristics was the best, but it was not sufficient for manufacturing rolled iron cores.
[0042]
[Table 2]

[0043]
On the other hand, as shown in Table 2, in the grain-oriented electrical steel sheet in which magnetic domain control is performed by forming at intervals of 2 mm of broken lines so that the groove: non-groove ratio is 1: 1 in the direction perpendicular to the rolling direction. In the grain-oriented electrical steel sheets of Examples 1 to 3 in which the groove length is in the range of 5 to 10 mm, the amount of iron loss improvement is 14.12% and the minimum number of breaks ratio is 8.1% or more, and Comparative Example 6 It was clarified that the steel sheet can be more well-balanced than the steel sheet of.
[0044]
[Table 3]

[0045]
Next, as a result of examining the groove: non-groove ratio, as shown in Table 3, in the grain-oriented electrical steel sheets of Examples 4 to 7 having a groove: non-groove ratio of 1: 1 to 1.5: 1. It was clarified that the amount of improvement in iron loss was 13.76% or more and the minimum number of fractures ratio was 8.1% or more, which made it possible to obtain a steel sheet having a better balance than the steel sheet of Comparative Example 6.
[0046]
[Table 4]

[0047]
Next, as a result of examining the spacing between adjacent broken lines, as shown in Table 4, iron loss in the grain-oriented electrical steel sheets of Examples 8 to 12 in which the spacing between adjacent broken lines is in the range of 2.0 to 20 mm. It was clarified that the amount of improvement was 12.71% or more and the minimum number of breaks ratio was 8.1% or more, and the steel sheet having a better balance than the steel sheet of Comparative Example 6 could be obtained.
[0048]
[Table 5]

[0049]
Next, as a result of examining the positions of the grooves of the adjacent broken lines, as shown in Table 5, the overlap (overlap amount) with the grooves of the adjacent broken lines is eliminated (minimum) in the direction perpendicular to the broken lines. In the grain-oriented electrical steel sheet of Example 13 arranged in, the amount of improvement in iron loss is 14.12% and the minimum number of breaks ratio is 10.8%, which is a steel sheet having a better balance than the steel sheet of Comparative Example 6. It became clear that
[0050]
[Table 6]

[0051]
Next, as a result of examining the angle of the broken line having a groove with respect to the rolling direction, as shown in Table 6, the directionality of Examples 14 to 17 in which the angle is in the range of 90 ° to 105 ° in the direction perpendicular to the broken line. It has been clarified that the electromagnetic steel sheet can be a steel sheet having a better balance than the steel sheet of Comparative Example 6 with an iron loss improvement amount of 12.47% or more and a minimum breaking frequency ratio of 8.1% or more.
[0052]
[Table 7]

[0053]
Table 7 shows Comparative Examples 25 to 27 having a groove length of less than 5 mm and Comparative Examples 28 to 30 having a groove length on the order of several hundred mm. In Comparative Examples 25 to 30, the ratio of the groove length to the non-groove length is 1: 1, the overlap between the grooves is "none" (that is, the amount of overlap between the grooves is zero), and the spacing between the grooves is zero. Is 2 mm and the groove angle is 90 °. As shown in Table 7, the iron loss improvement rate and the minimum fracture frequency ratio deteriorate between the case where the groove length is extremely short and the case where the groove length is extremely long, and the magnetic characteristics and the repeated bending characteristics are deteriorated. It can be seen that excellent grain-oriented electrical steel sheets cannot be obtained in both cases.
[0054]
From the above results, it is a grain-oriented electrical steel sheet having a 180 ° magnetic wall parallel to the rolling direction, and the length is in the range of 5 to 10 mm on a straight line on the surface of the grain-oriented electrical steel sheet that intersects the rolling direction. It has two or more broken lines including the grooves, the grooves are arranged at equal intervals in the broken lines including the grooves, and the length ratio of the grooves to the non-grooves is 1: 1 to 1.5: 1. The directionality of the present disclosure is such that the broken lines including the adjacent grooves are parallel, the interval is in the range of 2.0 to 20 mm, and the overlap between the grooves is the minimum in the direction perpendicular to the broken line including the groove. It was clarified that the electrical steel sheet has both low iron loss and excellent repeated bending characteristics at a high level.
Code description
[0055]
1 Electrical steel sheet
2 Bending part
The scope of the claims
[Claim 1]
A directional electromagnetic steel sheet having a grooved steel sheet surface, which has
two or more broken lines including the groove having a length of 5 to 10 mm on a straight line intersecting the rolling direction on the steel sheet surface.
in dashed line including the groove, the groove is arranged at equal intervals, the length of the groove: length ratio of the non-groove 1: 1 to 1.5: 1 range
directional electromagnetic, characterized in that Steel plate.
[Claim 2]
　The dashed lines including the adjacent grooves are parallel and the spacing is in the range of 2.0 to 20 mm, and the
groove length A, the non-groove length B, and the groove in the direction perpendicular to the broken line including the groove. The directional electromagnetic steel plate according to claim 1, wherein the relationship between the overlap amount C and each other satisfies the following equation (1).
　　　　　　　　　C = (AB) / 2 ... (1)
[Claim 3]
　The grain-oriented electrical steel sheet according to claim 1 or 2, wherein the broken line including the groove has an angle in the range of 75 to 105 ° with respect to the rolling direction.