JP6606991B2 - Oriented electrical steel sheet and manufacturing method thereof - Google Patents

Description

  The present invention relates to a grain-oriented electrical steel sheet that can reduce noise from a member when used as a material for an electric member, and a method for manufacturing the grain-oriented electrical steel sheet.

  In magnetic materials widely used in electrical and electronic equipment, the degree of change in length when a magnetic field is applied (this is called magnetostriction) causes transformer noise, and is an important evaluation item in quality control. ing. In recent years, noise from electric appliances is becoming more restrictive along with a demand for comfortable living environment. For this reason, research on noise reduction by reducing magnetostriction has been actively conducted.

Among magnetic materials, there is a technique for reducing magnetostriction by reducing the number of return magnetic domains for grain-oriented electrical steel sheets used for transformer iron cores. The reflux magnetic domain referred to here is a region having magnetization that is oriented at right angles to the magnetic field application direction. Magnetostriction occurs when this magnetization moves in the direction parallel to the magnetic field by the applied magnetic field. Therefore, the smaller the reflux magnetic domain amount, the smaller the magnetostriction. The following are known as main methods for reducing magnetostriction.
1) A method in which the <001> direction of crystal grains is aligned with the rolling direction and a reflux magnetic domain that causes a shape change by magnetization rotation is not created (Non-patent Document 1).
2) A method of erasing the reflux magnetic domain by releasing plastic strain (Non-patent Document 2).
3) A method of erasing the reflux magnetic domain by applying a film tension to the steel sheet (Non-patent Document 3).
4) A method of erasing the reflux magnetic domain by reducing the bore angle β (Non-patent Document 4).

Mainly by these four methods, the magnetostriction has been reduced and the noise of the electrical equipment has been reduced. For example, in the method of reducing magnetostriction with a high-tensile film, one or more oxides selected from SiO ₂ , ZrO ₂ , and SnO _{2 on} the surface of Al ₂ O ₃ have an average particle size. To obtain a high-strength coating consisting of 120 to 250 parts by weight of a solid phosphate selected from Al, Mg, Ca, and Zn with respect to 100 parts by weight of a multi-layer colloidal material coated with 3 to 30%. An insulating film forming agent for the grain-oriented electrical steel sheet is used (Patent Document 1).

  The bore angle is studied from the viewpoint of iron loss, and it is described that the larger the bore angle β, the more the return magnetic domain. Similarly, it is described that the iron loss increases (Non-patent Document 4).

  The demand for further noise reduction of electrical equipment is strong, and advanced technology is required to achieve the purpose. Conventional research on noise reduction has mainly been aimed at reducing magnetostriction due to the disappearance of the return magnetic domain. However, there is a problem that the reduction of magnetostriction has reached its peak in the conventional method in which the reflux magnetic domain existing in the grain-oriented electrical steel sheet is reduced overall and uniformly by the film tension. Therefore, new technology is needed.

T. Nozawa et al, "Relationship BetweenTotal Losses under Tensile Stress in 3 Percent Si-Fe Single Crystals and Their Orientations near (110) [001]", IEEE Trans. On Mag., Vol. MAG-14, No. 4, 1978 . [Development of iconic direction-oriented silicon steel sheet Orient Core Hibee]: OHM1972.2) T. Nozawa et al, "Relationship between Total Losses under Tensile Stress in 3 Percent Si-Fe Single Crystals and Their Orientations near (110) [001]", IEEE Trans.on Mag., Vol. MAG-14, No. 4, 1978. M. Imamuraet al, "Magnetization process and Magnetostriction of a Four Percent Si-Fe Single Crystal Close to (110) [001]", IEEE Trans. On Mag., Vol. MAG-17, No. 5, 1981.

Japanese Patent Laid-Open No. 10-1779

  The present invention pays attention to the crystal grain size in the rolling direction and the corner angle β in the vicinity of the grain boundary, finds the optimum magnetostriction reduction condition, and effectively realizes low noise, for a low noise transformer with excellent magnetostriction characteristics. It is to provide a grain-oriented electrical steel sheet that can be applied.

The present invention employs the following means in order to solve the above problems and achieve the object.
(1)
Average length DLmax in the rolling direction of crystal grains is 12 mm or more, film tension is 1 MPa or less, plate thickness is 0.35 mm or less ,
The length of the crystal grain in the rolling direction is divided into four equal parts, and the crystal orientation is determined for the grain boundary neighboring area within a distance of 2 mm from the grain boundary existing in the two outer areas to the inside of the crystal grain. The absolute value of the corner angle is β, and (directional area of grain boundary region where β is 4.0 ° or less) / (total area of grain boundary region) ≧ 0.50 steel sheet.
( 2 )
A method for producing the grain-oriented electrical steel sheet according to (1),
A method for producing a grain-oriented electrical steel sheet, characterized in that a sleeving radius when winding a finish annealing coil is 350 mm or more and a winding speed is 60 mpm or less.
( 3 )
The method for producing a grain-oriented electrical steel sheet according to ( 2 ), wherein a winding tension when winding the finish annealing coil is 5 MPa or more.

  According to the present invention, it is possible to reduce the magnetostriction of a grain-oriented electrical steel sheet. For example, when used as a material for an electrical member such as a transformer, noise from the member can be reduced.

It is explanatory drawing which showed typically the magnetic domain structure of the grain-oriented electrical steel sheet which concerns on a prior art. It is a figure which shows the effect of this invention. It is a schematic diagram of the crystal grain for demonstrating the length of the rolling direction of a crystal grain. It is a schematic diagram of the crystal grain for demonstrating a grain boundary vicinity area | region.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 schematically shows a magnetic domain structure of a grain-oriented electrical steel sheet according to the prior art. In this figure, the state of crystal grain boundaries and magnetic domains of the steel sheet is observed from the steel sheet surface. The steel plate of the present invention conforms to a general grain-oriented electrical steel sheet, the crystal orientation is accumulated in the {110} <001> orientation, and most of the magnetic domains are magnetized in the rolling direction. The main domain wall is a so-called 180 ° domain wall along the rolling direction. This 180 ° domain wall penetrates within one crystal grain, but is blocked by the grain boundary where the crystal structure is disturbed and the crystal orientation discontinuity becomes large. In this region, the magnetic field corresponding to the crystal orientation discontinuity Magnetic flux leaks out of the steel sheet due to discontinuity. For this reason, a reflux magnetic domain having a magnetization direction perpendicular to the rolling direction is formed in this region. Such a structure is generally known, and it is considered that the greater the number of return magnetic domains, the greater the magnetostriction (Non-Patent Document 4).

  The present inventors investigated in detail the reflux magnetic domains of grain-oriented electrical steel sheets. As a result, it has been found that this reflux magnetic domain is not a grain boundary extending in the direction along the rolling direction, but a high ratio is generated in the vicinity of the grain boundary extending in the direction orthogonal to the rolling direction. This is presumed that the deviation of the orientation between the adjacent crystal grains is larger because the deviation between the crystal grains adjacent to the rolling direction side is larger than the deviation of the crystal grains adjacent to the side perpendicular to the rolling direction. The

  Since there is a bias in the presence of the reflux magnetic domain in this way, the present inventor has devised a more efficient elimination rather than eliminating the reflux magnetic domain uniformly, and the reflux magnetic domain generated in the vicinity of a specific grain boundary. Considering selective reduction. Although it is simple as an initial study, as described above, since the reflux magnetic domain tends to occur near the grain boundary extending in the direction perpendicular to the rolling direction in relation to the crystal orientation with the adjacent grain, the rolling We investigated in detail about the relationship with directional particle size.

  As a result, the correlation between the magnetostriction and the crystal grain size in the rolling direction is not clear when the film tension is large, but the dependence appears when the film tension becomes small. It has been shown that there is a possibility that the magnetostriction can be made smaller than that of the high film tension material. FIG. 2 shows representative data organized by the relationship between the maximum distance DLmax and the magnetostriction between grain boundaries intersecting a straight line parallel to the rolling direction in one crystal grain. From a different perspective, this correlation is a phenomenon in which, when the grain size in the rolling direction is large, decreasing the film tension reduces the magnetostriction, and the conventional common sense that applying the film tension reduces the magnetostriction. This is exactly the opposite phenomenon. In addition, the balance between the film tension and the grain size in the rolling direction to further reduce magnetostriction is studied in detail, and the reflux magnetic domain and crystal orientation in the region near the grain boundary extending in the direction perpendicular to the rolling direction are controlled. It was made after confirming that the maximum effect can be obtained.

Next, the limiting conditions of the present invention will be described.
An important feature of the present invention is that the average value DLmax in the rolling direction of crystal grains is 12 mm or more and the film tension is 1 MPa or less. These two quantitative numerical ranges are indispensable conditions for obtaining the magnetostriction reducing effect by controlling the particle size under low tension, which is a feature of the present invention.

  The “length in the rolling direction of crystal grains” may be described as “L direction grain size” in the present specification. The grain size in the L direction is typically as shown in FIG. 3 for crystal grains having various forms. It should be noted that the “L direction grain size” in the present invention is generally determined in the L direction as determined by the line segment method or the like based on the number of crystal grains existing in the section along the L direction. This is different from the average crystal grain size related to. What is to be controlled in the present invention is the maximum diameter along the L direction for each crystal grain.

  In the present invention, the grain size in the L direction is measured for a sufficiently large number of crystal grains, and the average is defined as DLmax. In the field of view including 10 or more crystal grains, the average is obtained by averaging the L direction grain sizes of all the crystal grains in which the entire crystal grains are within the field of view.

  One reason for increasing DLmax is to suppress the number density of reflux magnetic domains that frequently occur in the vicinity of grain boundaries, particularly in the vicinity of crystal grain boundaries extending in a direction perpendicular to the rolling direction. This is because increasing the DLmax simply reduces the grain boundaries existing in the unit area, resulting in a decrease in the reflux magnetic domain. However, this rule is not limited only for such a simple reason, and the effect of the present invention is manifested by satisfying the scope of the invention together with the rule of the film tension.

  In the present invention, the effect of the present invention can be obtained by defining DLmax as 12 mm or more and the film tension as 1 MPa or less. The effect of the present invention cannot be sufficiently obtained in a region outside this range. Preferably, DLmax is 16 mm or more, more preferably 21 mm or more. The film tension is preferably 0.7 MPa or less, more preferably 0.4 MPa or less. Conventionally, the tension applied by the film may be zero.

  The above boundary value was experimentally obtained in a grain-oriented electrical steel sheet produced by a manufacturing method described later and having a crystal orientation strongly accumulated in the {110} <001> orientation by secondary recrystallization. Is.

  If the plate thickness exceeds 0.35mm, the transformer manufacturer will not use it for low noise transformer applications, so it is limited to 0.35mm or less.

  Further, in the region near the grain boundary schematically shown in FIG. 4 in one crystal grain, the effect of the invention becomes remarkable by controlling the abundance of the reflux magnetic domain in relation to the drilling angle of the crystal orientation.

  The region near the grain boundary is determined as follows. First, attention is paid to one crystal grain, and this crystal grain is divided into four regions divided by the grain size in the L direction. A region within a distance of 2 mm from the crystal grain boundary existing in the two outer regions to the inner side of the crystal grain is a region near the grain boundary. In the present invention, with respect to the region near the grain boundary, where β is the absolute value of the flue angle of the crystal orientation, (area of the region near the grain boundary where β is 4.0 ° or less) / (total area of the region near the grain boundary) ≧ 0 The effect of the invention can be sufficiently obtained by setting. Here, the boring angle β is an angle formed by the orientation closest to the rolling direction of the steel plate to the steel plate surface among the <001> orientations of the crystal grains. Β in the vicinity of the grain boundary is determined by measuring the crystal orientation by performing EBSD mapping by SEM on 10 or more crystal grains from the steel plate surface of the steel plate after removal of the film.

  The grain of the grain-oriented electrical steel sheet targeted by the present invention is usually occupied by one crystal grain in the thickness direction, and the measurement of the crystal grain size and crystal orientation is performed by removing the film. It shall be carried out from the surface.

  The grain boundary region range, β value, area ratio, and the like specified here are all experimentally determined. When these characteristics are within this range, the effect of the present invention is remarkably exhibited. In a steel plate having a large β, the magnetostriction cannot be sufficiently reduced no matter how Dmax and tension are controlled.

  Although the physical meaning of these control values is not clear, the deviation of the orientation with the adjacent grains is controlled to be small, particularly in the region in the vicinity of the grain boundary extending in the direction perpendicular to the rolling direction in which reflux magnetic domains are likely to occur. This is considered to contribute to the magnetostriction reduction effect under low tension, which is a characteristic phenomenon of the present invention.

  Preferred embodiments of the other features and manufacturing method of the steel sheet of the present invention will be described. The present invention is not limited to the form of the steel sheet or the manufacturing conditions described below, and various modifications can be made without departing from the spirit of the present invention. Moreover, a lower limit value and an upper limit value are included in the numerical limit range described below. However, the lower limit value does not include the lower limit value, and the upper limit value does not include the upper limit value.

  A grain-oriented electrical steel sheet is a combination of a cold rolling process and an annealing process in which the crystal orientation is controlled so that the easy axis of crystal grains coincides with the rolling direction, and the surface of the steel sheet ( A glass film formed on the surface of the steel sheet and an insulating film formed on the surface of the glass film.

  The steel sheet has, for example, mass fractions as chemical components, Si: 0.8% to 7%, C: more than 0% to 0.085%, acid-soluble Al: 0% to 0.065%, N: 0% 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 0.015%, with the balance being Fe and Consists of impurities.

  The chemical component of the steel sheet is a preferable chemical component for controlling the Goss texture in which the crystal orientation is accumulated in the {110} <001> orientation. Of the above elements, 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 the above-mentioned selective element 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%. Even if these selective elements are contained as impurities, the effect of the present embodiment is not impaired. In the steel sheet, the balance of the basic element and the selective element may be Fe and impurities. In addition, an impurity means the element inevitably mixed from the ore as a raw material, a scrap, or a manufacturing environment, when manufacturing a steel plate industrially.

  In general, grain oriented electrical steel sheets undergo purification annealing during secondary recrystallization. In the purification annealing, the inhibitor forming elements are discharged out of the system. In particular, for N and S, the decrease in the concentration is remarkable, and it becomes 50 ppm or less. Under normal purification annealing conditions, 9 ppm or less, further 6 ppm or less. If the purification annealing is sufficiently performed, it reaches a level that cannot be detected by general analysis (1 ppm or less).

  What is necessary is just to measure the chemical component of the said steel plate with the general analysis method of steel. For example, the chemical composition of the steel sheet may be measured using ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry). Specifically, a 35 mm square test piece from the center position of the steel sheet after film removal is measured by using an ICPS-8100 manufactured by Shimadzu Corporation (measurement device) under conditions based on a calibration curve prepared in advance. it can. C and S may be measured using a combustion-infrared absorption method, and N may be measured using an inert gas melting-thermal conductivity method.

  The glass film is made of a composite oxide such as forsterite (Mg2SiO4), spinel (MgAl2O4), or cordierite (Mg2Al4Si5O16). The glass film is a film formed in order to prevent the steel sheet from being seized in the finish annealing step, which is one of the manufacturing processes of the grain-oriented electrical steel sheet. Therefore, the glass film is not an essential element as a component of the grain-oriented electrical steel sheet.

  The insulating film contains, for example, colloidal silica and phosphate, and plays a role of imparting not only electrical insulation properties but also tension, corrosion resistance, heat resistance, and the like to the steel sheet.

  In addition, the glass film and insulating film of a grain-oriented electrical steel sheet can be removed by the following method, for example. A grain-oriented electrical steel sheet having a glass film or an insulating film is immersed in a sodium hydroxide aqueous solution of NaOH: 10% by mass + H 2 O: 90% by mass at 80 ° C. for 15 minutes. Subsequently, it is immersed in a sulfuric acid aqueous solution of H2SO4: 10% by mass + H2O: 90% by mass at 80 ° C. for 3 minutes. Thereafter, the substrate is dipped and washed with a nitric acid aqueous solution of HNO3: 10% by mass + H2O: 90% by mass for 1 minute at room temperature. Finally, dry with a warm air blower for 1 minute.

Next, the manufacturing method of the grain-oriented electrical steel sheet according to the present embodiment will be described.
In the first casting process of grain-oriented electrical steel sheets, by mass fraction, for example, Si: 0.8% to 7%, C: more than 0% to 0.085%, acid-soluble Al: 0.01% 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%, Molten steel containing Ni: 0% to 1%, S: 0% to 0.015%, Se: 0% to 0.015%, with the balance being a chemical component consisting of Fe and impurities is supplied to a continuous casting machine. Is produced continuously.

  Subsequently, in the hot rolling process, the slab obtained from the casting process is heated to a predetermined temperature (for example, 1150 to 1400 ° C.), and then the hot rolling is performed on the slab. Thereby, for example, a hot-rolled steel sheet having a thickness of 1.8 to 3.5 mm is obtained.

  Subsequently, in the annealing process, an annealing treatment is performed on the hot-rolled steel sheet obtained from the hot rolling process under a predetermined temperature condition (for example, a condition of heating at 750 to 1200 ° C. for 30 seconds to 10 minutes). The Subsequently, in the cold rolling process, after the pickling process is performed on the surface of the hot-rolled steel sheet that has been annealed in the annealing process, the hot-rolled steel sheet is cold-rolled. Thereby, for example, a cold-rolled steel sheet having a thickness of 0.15 to 0.35 mm is obtained.

Subsequently, in the decarburization annealing process, the cold-rolled steel sheet obtained from the cold rolling process is heat-treated under a predetermined temperature condition (for example, a condition of heating at 700 to 900 ° C. for 1 to 3 minutes) (that is, Decarburization annealing treatment) is performed. If such a decarburization annealing process is implemented, in a cold-rolled steel plate, carbon will be reduced to a predetermined amount or less, and a primary recrystallized structure will be formed. In the decarburization annealing step, an oxide layer containing silica (SiO ₂ ) as a main component is formed on the surface of the cold rolled steel sheet.

  Subsequently, in the annealing separator coating step, an annealing separator containing magnesium (MgO) as a main component is applied to the surface of the cold-rolled steel sheet (the surface of the oxide layer). Subsequently, in the finish annealing step, the cold-rolled steel sheet coated with the annealing separator is subjected to heat treatment (ie, finish annealing at a temperature of 1100 to 1300 ° C. for 20 to 24 hours) under a predetermined temperature condition. Process). When such a finish annealing treatment is performed, secondary recrystallization occurs in the cold-rolled steel sheet, and the cold-rolled steel sheet is purified. As a result, a cold-rolled steel sheet having the above-described chemical composition of the steel sheet and having a crystal structure controlled so that the easy axis of crystal grains coincides with the rolling direction X is obtained.

In addition, when the finish annealing treatment as described above is performed, the oxide layer containing silica as a main component reacts with an annealing separator containing magnesia as a main component, so that forsterite (Mg _A glass film made of a complex oxide such as ₂ SiO ₄ ) is formed. In the finish annealing step, the finish annealing process is performed in a state where the steel sheet is wound in a coil shape. By forming a glass film on the surface of the steel sheet during the finish annealing treatment, it is possible to prevent seizure from occurring on the steel sheet wound in a coil shape.

Furthermore, in addition to planarization annealing, an insulating film agent is applied and baked to form an insulating film, thereby obtaining a final grain-oriented electrical steel sheet product. Here, it is possible to adjust the coating tension to meet the provisions of the invention by setting the coating amount of the coating agent to be less than usual and adjusting the coating amount at 0.1 to 1.5 g / m ² .

  Among the above-mentioned production methods, the winding conditions for the finish annealing coil are particularly effective for preferably controlling the aforementioned L direction grain size and tension, and further the region near the grain boundary.

  In the present invention, the effect of the invention can be sufficiently obtained by setting the sleeve radius when winding the finish annealing coil to 350 mm or more. Preferably it is 420 mm or more, More preferably, it is 510 mm or more. This is simply to reduce the bore angle caused by performing secondary recrystallization in a coiled state having a curvature. If it is out of this range, the corner angle becomes large and it becomes difficult to obtain the invention effect.

  Further characteristic conditions are that the winding speed at this time is 60 mpm or less, preferably 50 mpm or less, more preferably 40 mpm or less. The reason for this is not clear, but when the winding speed is high, the coil winding becomes uneven, and the contact between the surface of the wound steel sheet and the atmosphere during finish annealing (secondary recrystallization) changes, Ultimately, it is considered that it is difficult to realize the control of the grain growth in the L direction and the corner angle in the vicinity of the grain boundary, which is preferable for the present invention.

  The other is to make the winding tension 5 MPa or more. The invention effect can be sufficiently obtained when the pressure is preferably 7 MPa or more, more preferably 13 MPa or more. The reason for this is not clear, but the winding tension is simply the tension in the L direction, which contributes to the preferential growth of the crystal grains in the L direction during the progress of secondary recrystallization, and at that time, the region near the grain boundary. This is considered to be because the bore angle becomes favorable.

In the first casting process of grain-oriented electrical steel sheet, by mass fraction, Si: 3.21%, C: 0.045%, acid-soluble Al: 0.030%, N: 0.0065%, Mn: 0.15%, Cr: 0.11%, S: Molten steel containing a chemical component containing 0.007% and the balance consisting of Fe and impurities is supplied to a continuous casting machine to produce a slab.

Subsequently, it is heated to 1150 ° C. in the hot rolling process, and the slab is hot rolled to obtain a hot rolled steel sheet having a thickness of 2.3 mm.

Subsequently, in the annealing process, heating was performed at 1000 ° C. for 3 minutes, and in the cold rolling process, annealing was performed in the annealing process, the hot-rolled steel sheet was pickled, cold-rolled, and 0.30 mm A cold-rolled steel sheet having a thickness is obtained.

Subsequently, in the decarburization annealing step, the cold rolled steel sheet is heated at 840 ° C. for 2 minutes to perform a decarburization annealing process.

Subsequently, in the annealing separator coating process, an annealing separator containing magnesia (MgO) as a main component is applied to the surface of the cold-rolled steel sheet. Subsequently, in the finish annealing process, the cooling separator coated with the annealing separator is applied. The rolled steel sheet is heat treated at 1200 ° C. for 20 hours. Here, secondary recrystallization occurs in the cold-rolled steel sheet, and the cold-rolled steel sheet is purified.

In addition, when the finish annealing treatment as described above is performed, the oxide layer containing silica as a main component reacts with an annealing separator containing magnesia as a main component, so that forsterite (Mg _A glass film made of a complex oxide such as ₂ SiO ₄ ) is formed. In the finish annealing step, the finish annealing process is performed in a state where the steel sheet is wound in a coil shape. By forming a glass film on the surface of the steel sheet during the finish annealing treatment, it is possible to prevent seizure from occurring on the steel sheet wound in a coil shape. As a result, a grain-oriented electrical steel sheet having a crystal structure controlled so that the easy axis of crystal grains coincides with the rolling direction can be obtained.

In the above process, the conformity to the following conditions 1 and 2 is changed according to the winding condition of the coil for finish annealing, the temperature raising condition in the finish annealing, and the tension coating application condition, and the magnetostriction is measured to obtain the effect of the invention. Verified.
(Condition 1) The grain size in the rolling direction is 12 mm or less.
(Condition 2) The orientation in the vicinity of the grain boundary is controlled so that β is 4.0 ° or less.
Here, λ ₁₇ is the magnetostriction at a magnetic flux density of 1.7T.

  The results are shown in Table 1. The steel sheet within the scope of the present invention has a small magnetostriction.

  According to the present invention, it is possible to reduce the magnetostriction of the steel sheet in order to reduce the noise of the electric member, so the present invention has sufficient industrial applicability.

Claims (3)

Average length DLmax in the rolling direction of crystal grains is 12 mm or more, film tension is 1 MPa or less, plate thickness is 0.35 mm or less ,
The length of the crystal grain in the rolling direction is divided into four equal parts, and the crystal orientation is determined for the grain boundary neighboring area whose distance from the grain boundary existing in the two outer areas to the inside of the crystal grain is 2 mm. The absolute value of the corner angle is β, and (directional area of grain boundary region where β is 4.0 ° or less) / (total area of grain boundary region) ≧ 0.50 steel sheet. A method for producing the grain-oriented electrical steel sheet according to claim 1,
A method for producing a grain-oriented electrical steel sheet, characterized in that a winding radius for winding a finish annealing coil is 350 mm or more and a winding speed is 60 mpm or less. The method for producing a grain-oriented electrical steel sheet according to claim 2 , wherein a winding tension when winding the finish annealing coil is 5 MPa or more.