JP7331800B2 - Oriented electrical steel sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a grain-oriented electrical steel sheet suitable for core materials of transformers.

Electrical steel sheets are widely used as iron cores for transformers and motors. In grain-oriented electrical steel sheets in particular, the crystal orientation is highly concentrated in the {110}<001> orientation known as the Goss orientation. , large transformers, etc. In order to reduce no-load loss (energy loss) in transformers, grain-oriented electrical steel sheets are required to have low iron loss. It is known that magnetic domain refining is extremely effective as a means of reducing this iron loss.

Magnetic domain refining can be broadly classified into a heat-resistant type and a non-heat-resistant type. The former is characterized by exhibiting a magnetic domain refining effect even after stress relief annealing, and the method of forming grooves in the steel sheet is common. The latter has a large magnetic domain refining effect, but is characterized in that the effect disappears after stress relief annealing, and a method of slightly straining the crystal lattice is generally used.

As the former heat-resistant magnetic domain refining method, for example, Patent Document 1 discloses a method of forming grooves by electrolytic etching after cold rolling. Further, Patent Document 2 discloses a method of forming grooves by using a roll with projections and pressing the projections. Further, Patent Document 3 discloses a method of forming grooves by laser irradiation. On the other hand, as a non-heat-resistant magnetic domain refining method, for example, Patent Document 4 describes a method of magnetic domain refining using a plasma jet in a product sheet of a grain-oriented electrical steel sheet. Further, Patent Document 5 discloses a method of introducing strain by laser irradiation without forming grooves. Furthermore, Patent Document 6 discloses a method using an electron beam.

JP-A-7-62436 JP-A-10-298653 Japanese Patent Application Laid-Open No. 2003-27194 JP-A-10-130729 Japanese Patent Application Laid-Open No. 2014-25106 Japanese Patent Application Laid-Open No. 2015-183189

As noted above, there are two types of domain refining, each with drawbacks. In other words, since grooves are formed in the heat-resistant type, magnetic flux cannot pass through the grooves, and B ₈ (magnetic flux density when excited at 800 A/m), which is an index of magnetic flux density, is greatly reduced. On the other hand, in the non-heat-resistant type, the distortion of the crystal lattice is eliminated by stress relief annealing, so that the magnetic domain refining effect disappears.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a grain-oriented electrical steel sheet in which the magnetic domain refining effect does not deteriorate and the magnetic domain refining effect does not disappear even after stress relief annealing.

The present invention provides a grain-oriented electrical steel sheet that does not deteriorate in magnetic flux density and does not lose its magnetic domain refining effect even after stress relief annealing by introducing a minute difference in crystal orientation into the steel sheet without forming grooves. It is.
The experiments that have led to the success of the present invention are described below.
<Experiment 1>
It contains Si: 3.27 to 3.34% and Mn: 0.09 to 0.12% in mass%, and has a component composition in which C is decarburized to 0.0030% or less and the balance is Fe, and B ₈ is 1.934 to 1.936T. A grain-oriented electrical steel sheet (0.23 mm thick) having a high magnetic flux density and having a forsterite coating and a coating film in order from the base iron side was subjected to three types of magnetic domain refining treatments in the following manner. A Yb fiber laser was used for these magnetic domain refining treatments. In addition, in order to avoid unevenness in the processing conditions due to heating of the steel sheet by laser processing, a jig cooled at 10°C was placed on the back side of the steel sheet to keep the temperature of the steel sheet constant.

Condition (i): The surface of the steel sheet was continuously irradiated with a laser perpendicular to the rolling direction to remove the surface coating film and forsterite film. The laser irradiation conditions were an output of 50 W, a laser spot diameter of 100 μm on the steel plate, and a scanning speed of 10 m/s. This laser irradiation was performed continuously from one end in the width direction of the steel sheet to the other end at intervals of 3 mm in the rolling direction. At this time, no change was observed on the steel sheet base iron side, and the laser had no effect on the base iron. After that, grooves were formed at the locations irradiated with the laser by electropolishing. The groove depth was 20 μm.

Condition (ii): The surface of the steel sheet was continuously irradiated with a laser perpendicular to the rolling direction to introduce crystal lattice strain into the surface of the steel sheet. The laser irradiation conditions were an output of 150 W, a laser spot diameter of 100 μm on the steel plate, and a scanning speed of 10 m/s. This laser irradiation was performed continuously from one end in the width direction of the steel sheet to the other end at intervals of 3 mm in the rolling direction.

Condition (iii): The surface of the steel sheet was continuously irradiated with a laser perpendicular to the rolling direction to introduce crystal lattice strain into the surface of the steel sheet. The laser irradiation conditions were an output of 250 W, a laser spot diameter of 100 μm on the steel plate, and a scanning speed of 10 m/s, and a larger lattice strain than condition (ii) was introduced. This laser irradiation was performed continuously from one end in the width direction of the steel sheet to the other end at intervals of 3 mm in the rolling direction.

The magnetic properties of each steel sheet obtained by the magnetic domain refining treatment under each of the above conditions were measured by the single plate magnetic property test method described in JIS C2556. Furthermore, each steel sheet was subjected to stress relief annealing at 800° C. for 3 hours in a N ₂ atmosphere, and the magnetic properties were measured again by the method described in JIS C2556. The obtained iron loss and magnetic flux density are shown in FIG. Condition (i) has grooves in the steel plate and the magnetic flux density is low. Condition (ii) has poor iron loss properties after stress relief annealing. This is believed to be due to the release of strain in the crystal lattice. However, under condition (iii), although the magnetic flux density was equivalent to that under condition (ii), good iron loss properties were maintained before and after stress relief annealing.

In order to investigate the cause of this, the crystal state of the laser-irradiated portion of the steel sheet treated under the condition (iii) after stress relief annealing was investigated by the EBSD method. Software manufactured by TSL was used for the EBSD system used here. The measurement condition was 0.10 μm step. In addition, OIM Analysis 8 manufactured by the same company was used for the analysis. As a result, the crystal orientation was found to be in the vicinity of the Goss orientation in the entire measured region, and the existence of grains having other orientations was not recognized. However, a region with a minute misorientation angle of about 0.5 to 3.0° with respect to the Goss orientation was observed directly below the laser irradiation area. A similar measurement was performed on the steel sheet treated under the condition (ii) after stress relief annealing, but no region with a minute misorientation angle of 0.5° or more was observed. The survey results are shown in FIG.

In FIG. 2, the horizontal axis indicates the average misorientation angle from the Goss orientation of each measurement point (hereinafter also referred to as the average misorientation angle). Specifically, it is Kernel Average Misorientation, and is the result when the nearest point is set to 5th. A specific method for calculating the average misorientation angle will be described later. That is, since the measurement step is 0.10 μm and the nearest point is 5th, this horizontal axis corresponds to the average misorientation angle per 0.50 μm. Furthermore, as a result of strain analysis of the steel sheet treated under the condition (iii) after stress relief annealing by the EBSD-Wilkinson method, it was found that the tensile stress and compressive stress were intricately intertwined just below the laser irradiation area. It became clear. It was presumed that this stress exerted the effect of refining the magnetic domains, resulting in the effect of reducing the iron loss. In addition, it is considered that the magnetic flux density was also good because almost no recesses such as grooves were observed on the surface of the steel sheet.

Considering the above, there are two important requirements for this technology. One is to have a minute misorientation angle as described above. The other is that the region with this minute misorientation angle maintains the Goss neighborhood orientation. In order to satisfy these two requirements, it is presumed that the cooling of the steel sheet performed in this experiment plays an important role. In other words, it is thought that the above two requirements can only be satisfied by not only precisely controlling the laser conditions, but also combining cooling technology at the same time. I can say.

Incidentally, Japanese Patent Application Laid-Open No. 2000-109961 mentions a heat-affected zone in addition to grooves as a means for exhibiting the magnetic domain refining effect. Since it is described that the magnetic domain refining is caused by the fact that the permeability of this heat-affected zone is different from that of the surroundings, the crystal orientation of the heat-affected zone is considered to change greatly from the Goss orientation. This technique is fundamentally different from the technique of the present invention that utilizes minute differences in crystal orientation.

The present invention is based on the above findings. That is, the gist and configuration of the present invention are as follows.
1. In terms of mass%, Si: 2.0 to 8.0%, Mn: 0.02 to 1.0%, C: 0.0050% or less, and the balance being Fe and unavoidable impurities A grain-oriented electrical steel sheet, wherein regions having a crystal orientation difference of 0.5° or more and 3.0° or less per 0.5 μm are present in a straight line or in a dotted line.

2. 2. The grain-oriented electrical steel sheet according to 1 above, wherein the region having the crystal misorientation has a range of 10 μm or more and 300 μm or less in the rolling direction and a range of 5 μm or more and 50 μm or less in the depth direction.

3. 3. The grain-oriented electrical steel sheet according to 1 or 2 above, wherein the region having the crystal orientation difference has a surface roughness difference of 5 μm or less.

4. 4. The grain-oriented electrical steel sheet according to any one of 1 to 3 above, wherein the region having the crystal orientation difference remains after the steel sheet is annealed at a temperature of 750 ° C. for 1 hour. steel plate.

5. The region having the crystal misorientation exists on one of the front and back surfaces of the steel plate, and the front and back surfaces of the steel plate have a coating and / or a forsterite coating that has a tensile tension in the rolling direction of the steel plate, 5. The grain-oriented electrical steel sheet according to any one of 1 to 4, wherein the tensile tension on the one surface is lower than the tensile tension on the other surface by 5% or more.

6. The component composition is further, in mass%, Ni: 0.010 to 1.50%, Cr: 0.01 to 0.50%, Cu: 0.01 to 0.50%, Bi: 0.005 to 0.50%, Sb: 0.010 to 0.200%, Sn: 0.010 to 0.200%. , Mo: 0.010 to 0.200%, P: 0.010 to 0.200%, and Nb: 0.001 to 0.015%.

The present invention generates a minute crystal orientation difference in the extreme surface layer of a grain-oriented electrical steel sheet without forming grooves, thereby obtaining low iron loss characteristics even after stress relief annealing without deteriorating the magnetic flux density. is possible.

FIG. 4 is a diagram showing magnetic flux density and iron loss for different laser irradiation conditions; FIG. 4 is a diagram showing the distribution of the average misorientation angle at each measurement point in the vicinity of the laser irradiation area after stress relief annealing for each irradiation condition. FIG. 4 is an explanatory diagram of a method of calculating an average misorientation angle;

Next, the reasons for limiting the constituent elements of the present invention will be described.
In the following description, the % display regarding the chemical composition of the steel sheet means % by mass unless otherwise specified.
Si: 2.0-8.0%
Si is an element necessary for increasing the specific resistance of steel and improving the iron loss, and for that purpose the content is 2.0% or more. On the other hand, if the content exceeds 8.0%, the workability of the steel deteriorates, making slitting and bending of the steel plate difficult, so the content is limited to 8.0% or less. Desirably, it is 3.0 to 6.5%.

Mn: 0.02-1.0%
If the Mn content exceeds 1.0%, the magnetic flux density of the product sheet is greatly reduced, and if it is less than 0.02%, the secondary recrystallization becomes difficult and the cost increases significantly. Desirably, it is 0.05 to 0.50%.

C: 0.0050% or less C is limited to 0.0050% or less because iron loss increases due to magnetic aging when C exceeds 0.0050%. Desirably, it is 0.0030% or less. Of course, it may be 0%, but from the viewpoint of economy, it is preferably 0.0010% or more.

The basic components of the present invention have been described above, but in the present invention, the following elements can be included as appropriate. That is, for the purpose of improving the magnetic flux density, Ni: 0.010 to 1.50%, Cr: 0.01 to 0.50%, Cu: 0.01 to 0.50%, Bi: 0.005 to 0.50%, Sb: 0.010 to 0.200%, Sn: 0.010 to At least one of 0.200%, Mo: 0.010-0.200%, P: 0.010-0.200% and Nb: 0.001-0.015% can be contained. If the amount of each element added is less than the respective lower limits, there is no effect of improving the magnetic properties.

Furthermore, on at least one of the front and back surfaces of the steel sheet, a region having a crystal orientation difference of 0.5° or more and 3.0° or less per 0.5 μm (hereinafter simply referred to as a crystal orientation difference) is present in a straight line or in a dotted line. is essential for the reasons given above.

Here, the region to which the above-described misorientation angle is given is linear or dotted, and the form of the line or row may be straight or curved, and may be of any shape. The magnitude of the misorientation angle must be 0.5 to 3.0° per 0.5 μm as described above. However, as can be seen from FIG. 2, there is no problem even if there is a region where the misorientation angle is less than 0.5° in the region where the misorientation angle is given. In that case, the area ratio of the area of less than 0.5° in the area providing the misorientation angle is 20% or less, preferably 15% or less.

The misorientation angle can be calculated by Kernel Average Misorientation of the EBSD method. The important thing is that the resolution of EBSD itself is about 0.5°, so as shown in Fig. 3, the measurement step interval is as small as about 0.1 μm, and the nearest point at the time of calculation is 5th or more, and the average of the misorientation angle is It is necessary to increase the number of parameters to take. For example, it is possible to set the measurement step interval to 0.5 μm and set the nearest point at the time of calculation to 1st, but in this case, if the measurement grid is hexagonal, only the six first adjacent measurement points are averaged. In this case, the measurement error in EBSD cannot be ignored. Therefore, since there are 30 fifth closest points on the hexagonal grid, it is considered that errors can be absorbed by averaging them.

Therefore, the crystal orientation difference per 0.5 μm in the present invention means that EBSD measurement is performed, the measurement step is 0.1 μm, and the nearest point when calculating the average misorientation angle (Kernel Average Misorientaion) is 5th (5 steps = per 0.5 μm ). It is desirable that this region with a crystal misorientation of 0.5 to 3.0° exists in a depth direction of 5 μm or more and 50 μm or less when observed from the L section (RD-ND section parallel to the rolling direction). If the laser irradiation treatment is performed so that the region exists deeper than this, recesses may be generated on the steel sheet surface due to the influence of the treatment, and the magnetic flux density may decrease. More desirably, the depth from the surface is 10 μm or more and 30 μm or less. Moreover, it is desirable that the rolling direction is in the range of 10 μm or more and 500 μm or less. Outside this range, the iron loss reduction effect may be reduced. More preferably, it is 50 μm or more and 250 μm or less. Since this area may not be a simple rectangle or semi-circle, we apply the longest diameter (distance) of the area. In addition, it is desirable that there are no recesses such as grooves on the surface of the region. Therefore, it is desirable that the unevenness difference is 5 μm or less. More preferably, it is less than 3 μm.

The constituent requirements of the present invention have been described above, and the manufacturing method for achieving them will also be described below.
First, from molten steel containing arbitrary components, slabs are continuously produced by a continuous casting machine, or ingots are produced by a casting method to obtain raw materials. This material has the above-described chemical composition, but it is difficult to change the components other than C during the process, so it is desirable to adjust the components during the molten steel stage. Also, Al, N, S and Se, which are called inhibitor components, can be added. The slab or ingot is heated and hot rolled in the usual way. The slab heating temperature before hot rolling is about 1400°C if it contains an inhibitor component, but if it does not contain an inhibitor component, high temperature heating is required to dissolve the inhibitor, which was conventionally essential. In view of cost, it is desirable to set the temperature to 1250°C or less.

Then, hot-rolled sheet annealing may be performed if necessary. In order to obtain good magnetic properties, the hot-rolled sheet annealing temperature is preferably 800°C or higher and 1150°C or lower. If the hot-rolled sheet annealing temperature is lower than 800° C., the band structure from hot rolling remains, making it difficult to achieve a primary recrystallized structure with regular grains and inhibiting the development of secondary recrystallization. If the hot-rolled sheet annealing temperature exceeds 1150°C, the grain size after the hot-rolled sheet annealing becomes too coarse, which is extremely disadvantageous in achieving a primary recrystallization structure with regular grains.

After the hot-rolled sheet is annealed, it is subjected to cold rolling one or more times with intervening intermediate annealing as necessary, and then decarburization annealing. The intermediate annealing temperature is preferably 900°C or higher and 1200°C or lower. If this temperature is less than 900° C., the recrystallized grains become finer, the number of Goss nuclei in the primary recrystallized structure decreases, and the magnetic properties deteriorate. On the other hand, if the intermediate annealing temperature exceeds 1200° C., the grain size becomes too coarse as in the case of hot-rolled sheet annealing, which is extremely disadvantageous in realizing a primary recrystallized structure with regular grain size. In the final cold rolling, raising the cold rolling temperature to 100° C. to 300° C. is effective for changing the recrystallized texture and improving the magnetic properties.

From the viewpoint of decarburization, it is effective to hold the decarburization annealing at 800°C or higher and 900°C or lower. At that time, a heating rate of 100° C./s or more is desirable because the core loss property is improved. However, the faster the temperature rise rate, the more expensive the equipment for achieving it, so 1200° C./s or less is desirable. From the viewpoint of decarburization, the atmosphere is desirably a moist atmosphere, and the dew point is desirably 30°C or higher. Also, from the same viewpoint of decarburization, it is desirable to include H ₂ in the atmosphere, and its concentration is preferably 5% or more and 70% or less.

After that, by applying an annealing separator mainly composed of MgO and then performing finish annealing, it is possible to prevent fusion between the steel sheets and form a forsterite coating. It is desirable that the final annealing be performed at 800°C or higher in order to develop secondary recrystallization. In addition, it is desirable to hold the temperature at 800° C. or higher for 20 hours or longer in order to complete the secondary recrystallization. In order to purify impurities in the steel and form a forsterite film, it is desirable to raise the temperature to about 1200°C. Furthermore, it is desirable to retain the temperature at 1180° C. or higher for 3 hours or longer because it promotes purification of impurities. After the finish annealing, it is useful to wash with water, brush, or pickle in order to remove the attached annealing separator. After that, flattening annealing is performed to correct the shape, which is effective for reducing iron loss.

In the case of using laminated steel sheets, it is effective to apply an insulating coating to the surface of the steel sheets before or after flattening annealing in order to improve iron loss. The insulating coating is preferably a coating that can apply tension to the steel plate in order to reduce iron loss. For example, if a tension coating application method using a binder or a coating method in which an inorganic material is deposited on the steel sheet surface layer by physical vapor deposition or chemical vapor deposition is adopted, the coating adhesion is excellent and the iron loss is significantly reduced. desirable because

If a region having a crystal orientation difference of 0.5° or more and 3.0° or less per 0.5 μm is applied to either the front or back surface of the steel sheet according to the present invention, the steel sheet may warp slightly. In this case, it is desirable to correct the warp by changing the tension due to the film or coating on the front and back surfaces of the steel sheet. Specifically, when the above-described warpage occurs, the warp occurs with the surface to which the region having the crystal misorientation applied is on the inside, so the tension on the surface can be made 5% or more lower than the surface on the opposite side. desirable. The reason is to avoid the above-described warpage. The upper limit of the tension difference is preferably 20% in order to avoid warping to the opposite side.

It is effective to irradiate the surface of the steel sheet with a laser or an electron beam as described above in order to generate a minute difference in crystal orientation on the surface of the steel sheet, which is the key to this technology. The timing can be after or before applying the insulating coating. However, even if the difference in crystal orientation is imparted before the secondary recrystallization, the orientation difference is relaxed during the secondary recrystallization, so it is desirable after the secondary recrystallization. However, since a certain degree of effect can be expected, there is no problem even if it is applied before the secondary recrystallization. Also, from the above experiment, it was considered effective to cool simultaneously with these processes (irradiation). The reason for this is not clear, but by cooling at the same time as the laser or electron beam irradiation, the temperature unevenness within the steel plate becomes smaller, and changes occur in the melting-resolidification process. It is considered that the solidified as an orientation close to As for the cooling method, in the above experiment, the cooling jig was brought into contact with the back side of the steel plate, but in the same way, another method such as blowing low-temperature gas may also be used.

The present invention is characterized in that there is no reduction in magnetic flux density after stress relief annealing and low iron loss is obtained. This strain relief annealing is generally performed after slitting into a predetermined size and then processing into a final product such as a transformer. Since the purpose is to remove the strain introduced by slitting, processing, etc., the stress relief annealing conditions are preferably 700 to 900° C. for 1 to 5 hours. However, short-time annealing of about several tens of seconds does not pose any problem.

As described above, a steel sheet having a region having a crystal orientation difference of 0.5° or more and 3.0° or less per 0.5 μm on either side of the front or back surface is characterized in that the magnetic flux density does not decrease after stress relief annealing. Specifically, after the steel sheet is annealed at a temperature of 750° C. for 1 hour, the region having the above-mentioned crystal misorientation remains.

It contains Si: 3.38% and Mn: 0.21% in terms of mass%, and has a component in which C is decarburized to 0.0030% or less, the balance is Fe, and B ₈ has a high magnetic flux density of 1.933 to 1.936T. A grain-oriented electrical steel product sheet (thickness: 0.23 mm) not subjected to magnetic domain refining treatment was subjected to magnetic domain refining treatment using an electron beam. In order to avoid unevenness in the processing conditions due to the heating of the steel plate by the electron beam processing, a jig cooled with water at 10°C was applied to the back surface of the steel plate to keep the temperature of the steel plate in the vicinity of the processing constant. The electron beam irradiation conditions were variously changed as shown in Table 1. The output shown in Table 1 is the product of the beam current and the acceleration voltage, and the point interval is the point interval in the beam scanning direction (that is, the direction perpendicular to the rolling direction) when irradiation is performed in a dot sequence.

The magnetic properties of the samples thus obtained were measured by the single plate magnetic property test method described in JIS C2556. Further, each sample was subjected to stress relief annealing at 750° C. for 3 hours in a N ₂ atmosphere, and the magnetic properties were measured again by the method described in JIS C2556. Table 1 also shows the obtained iron loss and magnetic flux density. In addition, for the samples after stress relief annealing, the crystal orientation near the electron beam irradiated area was investigated by the EBSD method. The measurement surface was an L section (a section parallel to the rolling direction), and the EBSD measurement conditions were 0.10 µm steps. In order to determine the area where the minute misorientation exists, as an analysis, when the nearest point of Kernel Average Misorientation is 5th, the area where the average misorientation angle is 0.05 to 0.30° is mapped, and the maximum depth direction and rolling The direction and length were calculated. The results are also shown in Table 1. As is clear from the table, good magnetic flux density and iron loss are obtained even after stress relief annealing under the conditions within the range of the present invention.

Product sheet of grain-oriented electrical steel sheet ( _plate 0.23 mm thick) was subjected to magnetic domain refining treatment using an electron beam. In order to avoid unevenness in the processing conditions due to the heating of the steel sheet by the electron beam processing, a jig cooled by water at 10°C was applied to the back surface of the steel sheet to keep the temperature of the steel sheet constant. The irradiation conditions of the electron beam were as follows: output of 5500 W, scanning speed of 200 m/s, point spacing of 0.30 mm, and irradiation spacing of 3 mm.

The magnetic properties of the samples thus obtained were measured by the single plate magnetic property test method described in JIS C2556. Further, each steel sheet was subjected to stress relief annealing at 815° C. for 4 hours in a N ₂ atmosphere, and the magnetic properties were measured again by the method described in JIS C2556. The obtained iron loss and magnetic flux density are also shown in Table 2. In addition, for the samples after stress relief annealing, the crystal orientation near the electron beam irradiated area was investigated by the EBSD method. The measurement plane was an L section, and the EBSD measurement conditions were 0.10 μm steps. In order to ascertain the area where a minute misorientation exists, as an analysis, when the nearest point of Kernel Average Misorientation is 5th, the area where the average misorientation angle is 0.05 to 0.30° is mapped, and the maximum depth direction and rolling The direction and length were calculated. The results were 31-55 μm in the depth direction and 130-145 μm in the rolling direction. As is clear from Table 2, good magnetic flux density and iron loss are obtained even after stress relief annealing under the conditions within the range of the present invention.

Claims (6)

At least one of the groove-free front and back surfaces of a steel sheet containing 2.0 to 8.0% Si, 0.02 to 1.0% Mn, 0.0050% or less C, and the balance being Fe and unavoidable impurities. A grain-oriented electrical steel sheet characterized in that regions having a crystal misorientation of 0.5° or more and 3.0° or less per 0.5 μm are present linearly or in a dotted line on the surface of the grain-oriented electrical steel sheet. 2. The grain-oriented electrical steel sheet according to claim 1, wherein the region having the crystal misorientation has a range of 10 μm or more and 300 μm or less in the rolling direction and a range of 5 μm or more and 50 μm or less in the depth direction. 3. The grain-oriented electrical steel sheet according to claim 1, wherein the region having the crystal orientation difference has a surface irregularity difference of 5 μm or less. 4. The grain-oriented electrical steel sheet according to claim 1, wherein after the steel sheet is annealed at a temperature of 750° C. for 1 hour, the region having the crystal orientation difference remains. electromagnetic steel sheet. The region having the crystal misorientation exists on one of the front and back surfaces of the steel plate, and the front and back surfaces of the steel plate have a coating and / or a forsterite coating that has a tensile tension in the rolling direction of the steel plate, The grain-oriented electrical steel sheet according to any one of claims 1 to 4, wherein the tensile tension on the one surface is lower than the tensile tension on the other surface by 5% or more. The component composition is further, in mass%, Ni: 0.010 to 1.50%, Cr: 0.01 to 0.50%, Cu: 0.01 to 0.50%, Bi: 0.005 to 0.50%, Sb: 0.010 to 0.200%, Sn: 0.010 to 0.200%. , Mo: 0.010 to 0.200%, P: 0.010 to 0.200%, and Nb: 0.001 to 0.015%.

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