Title of invention: grain-oriented electrical steel sheet
Technical field
[0001]
　The present invention relates to grain-oriented electrical steel sheets.
　This application applies to Japanese Patent Application No. 2018-143541 filed in Japan on July 31, 2018, Japanese Patent Application No. 2018-143897 filed in Japan on July 31, 2018, and Japan on July 31, 2018. Claim the priority based on Japanese Patent Application No. 2018-14393 filed in Japan, the contents of which are incorporated herein by reference.
Background technology
[0002]
　The grain-oriented electrical steel sheet contains 7% by mass or less of Si and has a secondary recrystallization texture accumulated in the {110} <001> orientation (Gossi orientation). The {110} <001> orientation means that the {110} plane of the crystal is arranged parallel to the rolling surface, and the <001> axis of the crystal is arranged parallel to the rolling direction.
[0003]
　The magnetic properties of grain-oriented electrical steel sheets are greatly affected by the degree of integration in the {110} <001> orientation. In particular, it is considered that the relationship between the rolling direction of the steel sheet, which is the main magnetization direction when the steel sheet is used, and the <001> direction of the crystal, which is the easy magnetization direction, is important. Therefore, in recent practical grain-oriented electrical steel sheets, the angle formed by the <001> direction of the crystal and the rolling direction is controlled so as to be within a range of about 5 °.
[0004]
　The deviation between the actual crystal orientation of the directional electromagnetic steel plate and the ideal {110} <001> orientation is the deviation angle α around the rolling surface normal direction Z, the deviation angle β around the rolling perpendicular direction C, and the rolling direction. It can be represented by the three components of the deviation angle γ around L.
[0005]
　FIG. 1 is a schematic diagram illustrating a shift angle α, a shift angle β, and a shift angle γ. As shown in FIG. 1, the deviation angle α is an angle formed by the <001> direction of the crystal projected on the rolled surface and the rolling direction L when viewed from the rolling surface normal direction Z. The deviation angle β is the angle formed by the <001> direction of the crystal projected on the L cross section (cross section with the rolling perpendicular direction as the normal) and the rolling direction L when viewed from the rolling perpendicular direction C (plate width direction). is there. The deviation angle γ is an angle formed by the <110> direction of the crystal projected on the C cross section (cross section with the rolling direction as the normal) and the rolling surface normal direction Z when viewed from the rolling direction L.
[0006]
　Of the deviation angles α, β, and γ, the deviation angle β is known to affect magnetostriction. Magnetostriction is a phenomenon in which a magnetic material changes its shape when a magnetic field is applied. In grain-oriented electrical steel sheets used for transformers of transformers, magnetostriction causes vibration and noise, so that magnetostriction is required to be small.
[0007]
　For example, Patent Documents 1 to 3 disclose that the shift angle β is controlled. Further, it is disclosed in Patent Documents 4 and 5 that the deviation angle α is controlled in addition to the deviation angle β. Further, Patent Document 6 discloses a technique for improving the iron loss characteristics by classifying the degree of integration of crystal orientations in more detail by using the deviation angle α, the deviation angle β, and the deviation angle γ as indexes.
[0008]
　Further, for example, Patent Documents 7 to 9 disclose that not only the magnitude and the average value of the absolute values ​​of the deviation angles α, β, and γ are controlled, but also the fluctuation (deviation) is included in the control. Further, Patent Documents 10 to 12 disclose that Nb, V and the like are added to the grain-oriented electrical steel sheet.
[0009]
　Further, the grain-oriented electrical steel sheet is required to have excellent magnetic flux density in addition to magnetostriction. So far, a method of controlling the growth of crystal grains in secondary recrystallization to obtain a steel sheet having a high magnetic flux density has been proposed. For example, in Patent Documents 13 and 14, a method of advancing secondary recrystallization while giving a temperature gradient to a steel sheet in the tip region of secondary recrystallized grains that are eroding the primary recrystallized grains in a finish annealing step. Is disclosed.
[0010]
　When secondary recrystallized grains are grown using a temperature gradient, the grain growth is stable, but the crystal grains may become excessively large. If the crystal grains become excessively large, the effect of improving the magnetic flux density may be hindered by the influence of the curvature of the coil. For example, in Patent Document 15, when the secondary recrystallization is allowed to proceed while giving a temperature gradient, a process of suppressing the free growth of the secondary recrystallization generated at the initial stage of the secondary recrystallization (for example, in the width direction of the steel sheet). The process of applying mechanical strain to the end of the surface) is disclosed.
Prior art literature
Patent documents
[0011]
Patent Document 1: Japanese Patent Application Laid-Open No. 2001-294996
Patent Document 2: Japanese Patent Application Laid-Open No. 2005-240102
Patent Document 3: Japanese Patent Application Laid-Open No. 2015-206114
Patent Document 4: Japanese Patent Application Laid-Open No. 2004-060026 JP
Patent Document 5: WO 2016/056501
Patent Document 6: Japanese Patent 2007-314826 JP
Patent Document 7: Japanese Patent 2001-192785 JP
Patent Document 8: Japanese Patent 2005-240079 JP
Patent Document 9: Japanese Patent 2012-052229 JP
Patent Document 10: Japanese Sho 52-024116 Patent Publication
JP 11: Japanese Patent Laid-Open 02-200732 discloses
Patent Document 12: Japanese Patent No. 4962516 JP
Patent Document 13: Japanese Sho 57-002839 Patent Publication
JP 14: Japanese Sho 61-190017 Patent Publication
JP 15: Japanese Patent Laid-Open 02-258923 discloses
Outline of the invention
Problems to be solved by the invention
[0012]
　As a result of studies by the present inventors, it cannot be said that the conventional techniques disclosed in Patent Documents 1 to 9 are particularly sufficient in reducing magnetostriction even though the crystal orientation is controlled.
[0013]
　Further, since the conventional techniques disclosed in Patent Documents 10 to 12 merely contain Nb and V, it cannot be said that the reduction of magnetostriction is sufficient. Further, the conventional techniques disclosed in Patent Documents 13 to 15 not only have a problem from the viewpoint of productivity, but also cannot be said to sufficiently reduce magnetostriction.
[0014]
　An object of the present invention is to provide a grain-oriented electrical steel sheet having improved magnetostriction in view of the current situation in which reduction of magnetostriction is required for grain-oriented electrical steel sheets. In particular, it is an object of the present invention to provide a grain-oriented electrical steel sheet having improved magnetostriction in a low magnetic field region (magnetic field of about 1.5 T).
Means to solve problems
[0015]
　The gist of the present invention is as follows.
[0016]
(1) The directional electromagnetic steel plate according to one aspect of the present invention has Si: 2.0 to 7.0%, Nb: 0 to 0.030%, V: 0 to 0.030%, Mo in mass%. : 0 to 0.030%, Ta: 0 to 0.030%, W: 0 to 0.030%, C: 0 to 0.0050%, Mn: 0 to 1.0%, S: 0 to 0. 0150%, Se: 0 to 0.0150%, Al: 0 to 0.0650%, N: 0 to 0.0050%, Cu: 0 to 0.40%, Bi: 0 to 0.010%, B: 0 to 0.080%, P: 0 to 0.50%, Ti: 0 to 0.0150%, Sn: 0 to 0.10%, Sb: 0 to 0.10%, Cr: 0 to 0.30 %, Ni: 0 to 1.0, the balance has a chemical composition consisting of Fe and impurities, and the directional electromagnetic steel plate has an texture oriented in the Goss direction. The deviation angle from the ideal Goss direction is defined as α, the deviation angle from the ideal Goss direction with the rolling perpendicular direction C as the rotation axis is defined as β, and the deviation angle from the ideal Goss direction with the rolling direction L as the rotation axis. The deviation angle is defined as γ, and the deviation angles of the crystal orientations measured at two measurement points adjacent to each other on the plate surface and having an interval of 1 mm are (α 1　β 1　γ 1 ) and (α 2　β 2　γ 2 ). The boundary condition BA is defined as | β 2- β 1 | ≧ 0.5 °, and the boundary condition BB is defined as [(α 2- α 1).) 2 + (β 2- β 1 ) 2 + (γ 2- γ 1 ) 2 ] 1/2 ≧ 2.0 °, the grain boundaries that satisfy the boundary condition BA and do not satisfy the boundary condition BB Exists.
(2) In the oriented electrical steel sheet according to (1), the average crystal grain size in the rolling direction L obtained based on the boundary conditions BA particle size RA L is defined as the rolling direction L obtained based on the boundary conditions BB the average crystal grain size of the particle diameter RB L when defining the particle size RA L and a particle size RB L and a, 1.10 ≦ RB L ÷ RA L may satisfy.
(3) In the oriented electrical steel sheet according to (1) or (2), the average crystal grain size of the perpendicular to the rolling direction C determined based on the boundary conditions BA particle size RA C is defined as, based on the boundary conditions BB the average crystal grain size of the perpendicular to the rolling direction C to obtain Te particle diameter RB CWhen defining the particle size RA C and a particle size RB C is a, 1.10 ≦ RB C ÷ RA C may satisfy.
(4) In the oriented electrical steel sheet according to any one of the above (1) to (3), the average crystal grain size in the rolling direction L particle size RA obtained based on the boundary conditions BA L is defined as the boundary the average crystal grain size of the perpendicular to the rolling direction C particle size RA determined based on the condition BA C when defining the particle size RA L and a particle size RA C and a, 1.15 ≦ RA C ÷ RA L be met Good.
(5) In the directional electromagnetic steel sheet according to any one of (1) to (4) above, the average crystal grain size in the rolling direction L obtained based on the boundary condition BB is defined as the particle size RB L, and the boundary is defined. When the average crystal grain size in the rolling perpendicular direction C obtained based on the condition BB is defined as the particle size RB C , the particle size RB L and the particle size RB C are 1.50 ≦ RB C.÷ RB L may be satisfied.
(6) In the oriented electrical steel sheet according to any one of the above (1) to (5), the average crystal grain size in the rolling direction L obtained based on the boundary conditions BA particle size RA L is defined as the boundary the average grain size in the rolling direction L particle diameter RB determined based on the conditions BB L is defined as the average crystal grain size of the perpendicular to the rolling direction C determined based on the boundary conditions BA particle size RA C is defined as the boundary condition the average crystal grain size of the perpendicular to the rolling direction C particle size RB determined based on BB C when defining the particle size RA L and a particle size RA C and particle size RB L and a particle size RB C and a, (RB C × RA L ) ÷ (RB L × RA C ) <1.0 may satisfy.
(7) In the grain-oriented electrical steel sheet according to any one of (1) to (6) above, the average crystal grain size in the rolling direction L determined based on the boundary condition BB is the particle size RB L.And defining, the average crystal grain size of the perpendicular to the rolling direction C particle size RB obtained based on boundary conditions BB C when defining the particle size RB L and particle size RB C may also be 22mm or more.
(8) In the oriented electrical steel sheet according to any one of the above (1) to (7), the average crystal grain size in the rolling direction L obtained based on the boundary conditions BA particle size RA L is defined as the boundary the average crystal grain size of the perpendicular to the rolling direction C particle size RA determined based on the condition BA C when defining the particle size RA L is at 30mm or less, the particle size RA C may also be 400mm or less.
(9) In the grain-oriented electrical steel sheet according to any one of (1) to (8) above, the standard deviation σ (| β |) of the absolute value of the deviation angle β is 0 ° or more and 1.70 ° or less. It may be.
(10) In the grain-oriented electrical steel sheet according to any one of (1) to (9) above, at least one selected from the group consisting of Nb, V, Mo, Ta, and W is used as the chemical composition. A total of 0.0030 to 0.030% by mass may be contained.
(11) In the grain-oriented electrical steel sheet according to any one of (1) to (10) above, the magnetic domain is subdivided by at least one of applying local microstrain or forming a local groove. May be good.
(12) In the grain-oriented electrical steel sheet according to any one of (1) to (11) above, the intermediate layer arranged in contact with the grain-oriented electrical steel sheet and the insulation arranged in contact with the intermediate layer. It may have a coating.
(13) In the grain-oriented electrical steel sheet according to any one of (1) to (12) above, the intermediate layer may be a forsterite film having an average thickness of 1 to 3 μm.
(14) In the grain-oriented electrical steel sheet according to any one of (1) to (13) above, the intermediate layer may be an oxide film having an average thickness of 2 to 500 nm.
Effect of the invention
[0017]
　According to the above aspect of the present invention, there is provided a grain-oriented electrical steel sheet having improved magnetostriction in a low magnetic field region (particularly, a magnetic field of about 1.5 T).
A brief description of the drawing
[0018]
FIG. 1 is a schematic diagram illustrating a shift angle α, a shift angle β, and a shift angle γ.
[Fig. 2] Fig. 2 is a schematic view illustrating a grain boundary of a grain-oriented electrical steel sheet.
FIG. 3 is a schematic cross-sectional view of a grain-oriented electrical steel sheet according to an embodiment of the present invention.
FIG. 4 is a flow chart of a method for manufacturing a grain-oriented electrical steel sheet according to an embodiment of the present invention.
Mode for carrying out the invention
[0019]
　A preferred embodiment of the present invention will be described in detail. However, the present invention is not limited to the configuration disclosed in the present embodiment, and various modifications can be made without departing from the spirit of the present invention. In addition, the lower limit value and the upper limit value are included in the numerical limitation range described below. Numerical values ​​that indicate "greater than" or "less than" are not included in the numerical range. Further, "%" regarding the chemical composition means "mass%" unless otherwise specified.
[0020]
　Generally, in order to reduce the magnetostriction, the crystal orientation is set so that the deviation angle β becomes small (specifically, the maximum value and the average value of the absolute value | β | of the deviation angle β become small). Be controlled. In fact, until now, the strength of the magnetic field at the time of magnetization is generally the magnetic field region near 1.7T, which is the strength of the magnetic field at the time of measuring the magnetic characteristics (hereinafter, simply referred to as "medium magnetic field region"). It has been confirmed that the correlation between the deviation angle β and the magnetostriction is relatively high.
[0021]
　On the other hand, secondary recrystallization in a practical grain-oriented electrical steel sheet proceeds in a state of being wound around a coil. That is, the secondary recrystallized grains grow in a state where the steel sheet has a curvature. Therefore, even if the crystal grains have a small deviation angle β in the initial stage of secondary recrystallization, the deviation angle β inevitably increases as the crystal grains grow.
[0022]
　Of course, if it is possible to generate a large number of crystal grains having a small deviation angle β at the stage of secondary recrystallization grain generation, it is almost ideal {110} even if those individual crystal grains do not grow so large. It is also possible to fill the entire region of the steel sheet with the secondary recrystallized grains in the <001> orientation. However, in reality, it is not possible to generate a large number of crystal grains having such alignment.
[0023]
　While investigating the relationship between the crystal orientation and noise of the material steel sheet used for the practical iron core, the present inventors have found that the correlation between the deviation angle β and noise may be weakened in some materials. I found out. That is, it was found that the noise in the actual use environment was not sufficiently reduced even if the grain-oriented electrical steel sheet having a small magnetostriction with the deviation angle β controlled as in the conventional case was used.
[0024]
　The present inventors presumed this cause as follows. First, in an actual use environment, the magnetic flux does not flow uniformly in the steel sheet, and there are places where the magnetic flux is locally concentrated. Along with this, there is a region where the magnetic flux density weakens, and the area is wider in the region where the magnetic flux weakens. Therefore, it is considered that the noise in the actual use environment is strongly influenced not only by the magnetostriction under the general excitation condition of about 1.7 T but also by the magnetostriction in the lower excitation region.
[0025]
　According to this estimation, we investigated the situation where the correlation between the deviation angle β and noise became low, and found that the behavior was the "difference between the minimum and maximum magnetostriction", which is the amount of magnetostriction at 1.5T (hereinafter, It was found that it can be evaluated by (denoted as "λpp@1.5T"). Then, if this behavior can be optimally controlled, it is possible to further reduce the noise of the transformer.
[0026]
　Therefore, the present inventors have investigated not to grow the secondary recrystallized grains while maintaining the crystal orientation at the stage of growth of the secondary recrystallized grains, but to grow the crystals with the orientation change. As a result, during the growth of the secondary recrystallized grains, a large number of local and small tilt angle changes that were not conventionally recognized as grain boundaries are generated, and one secondary recrystallized grain has a deviation angle β. It was found that the state of being divided into slightly different small regions is advantageous for reducing magnetostriction in the low magnetic field region.
[0027]
　Further, in order to control the above-mentioned orientation change, it is important to consider a factor that facilitates the orientation change itself and a factor that makes the orientation change continuously occur in one crystal grain. I found out. Then, in order to facilitate the occurrence of the orientation change itself, it is effective to start the secondary recrystallization from a lower temperature. For example, it was confirmed that the primary recrystallization particle size can be controlled and elements such as Nb can be utilized. .. Furthermore, by using a conventionally used inhibitor such as AlN in an appropriate temperature and atmosphere, it is possible to continuously generate an orientation change up to a high temperature region in one crystal grain in the secondary recrystallization. I confirmed that I could do it.
[0028]
[First Embodiment] In the
　grain-oriented electrical steel sheet according to the first embodiment of the present invention, the secondary recrystallized grains are divided into a plurality of regions having slightly different deviation angles β. That is, in the directional electromagnetic steel plate according to the present embodiment, in addition to the grain boundaries having a relatively large angle difference corresponding to the grain boundaries of the secondary recrystallized grains, the inside of the secondary recrystallized grains is locally divided. It has a small grain boundary.
[0029]
　Specifically, the directional electromagnetic steel plate according to the present embodiment has Si: 2.0 to 7.0%, Nb: 0 to 0.030%, V: 0 to 0.030%, Mo in mass%. : 0 to 0.030%, Ta: 0 to 0.030%, W: 0 to 0.030%, C: 0 to 0.0050%, Mn: 0 to 1.0%, S: 0 to 0. 0150%, Se: 0 to 0.0150%, Al: 0 to 0.0650%, N: 0 to 0.0050%, Cu: 0 to 0.40%, Bi: 0 to 0.010%, B: 0 to 0.080%, P: 0 to 0.50%, Ti: 0 to 0.0150%, Sn: 0 to 0.10%, Sb: 0 to 0.10%, Cr: 0 to 0.30 A directional electromagnetic steel plate containing%, Ni: 0 to 1.0%, having a chemical composition in which the balance is composed of Fe and impurities, and having a texture oriented in the Goss direction, in the
　rolling surface normal direction. The deviation angle from the ideal Goss direction with Z as the rotation axis is defined as α, the deviation angle from the ideal Goss direction with the rolling perpendicular direction (plate width direction) C as the rotation axis is defined as β, and the rolling direction L is defined as β. The deviation angle from the ideal Goss orientation as the rotation axis is defined as γ, and the deviation angle of
　the crystal orientation measured at two measurement points adjacent to each other on the plate surface and having an interval of 1 mm is (α 1　β 1).　Expressed as γ 1 ) and (α 2　β 2　γ 2 ), the boundary condition BA is | β 2- β 1| ≧ 0.5 °, and the boundary condition BB is [(α 2- α 1 ) 2 + (β 2- β 1 ) 2 + (γ 2- γ 1 ) 2 ] 1/2 ≧ 2.0 ° When defined as, the
　directional electromagnetic steel sheet according to the present embodiment satisfies the boundary condition BA in addition to the grain boundaries satisfying the boundary condition BB (grain boundaries corresponding to the secondary recrystallized grain boundaries). It has grain boundaries (grain boundaries that divide secondary recrystallized grains) that do not satisfy the above boundary condition BB.
[0030]
　The grain boundaries satisfying the boundary condition BB substantially correspond to the secondary recrystallized grain boundaries observed when the conventional grain-oriented electrical steel sheet is macro-etched. The grain-oriented electrical steel sheet according to the present embodiment has, in addition to the grain boundaries satisfying the above-mentioned boundary condition BB, a grain boundary satisfying the boundary condition BA and not satisfying the above-mentioned boundary condition BB at a relatively high frequency. The grain boundaries that satisfy the boundary condition BA and do not satisfy the boundary condition BB correspond to the local and small tilt angle grain boundaries that divide the secondary recrystallized grains. That is, in the present embodiment, the secondary recrystallized grains are in a state of being finely divided by small regions having slightly different deviation angles β.
[0031]
　Conventional grain-oriented electrical steel sheets may have secondary recrystallized grain boundaries that satisfy the boundary condition BB. Further, the conventional grain-oriented electrical steel sheet may have a displacement of a displacement angle β within the grains of the secondary recrystallized grains. However, in the conventional grain-oriented electrical steel sheet, the displacement angle β tends to be continuously displaced in the secondary recrystallized grains. Therefore, the displacement of the grain angle β existing in the conventional grain-oriented electrical steel sheet is the above boundary. It is difficult to satisfy the condition BA.
[0032]
　For example, in a conventional grain-oriented electrical steel sheet, the displacement of the displacement angle β may be discriminated in the long range region in the secondary recrystallized grain, but the displacement of the displacement angle β in the short range region in the secondary recrystallized grain. Is difficult to identify because it is very small (it is difficult to satisfy the boundary condition BA). On the other hand, in the grain-oriented electrical steel sheet according to the present embodiment, the deviation angle β is locally displaced in a short range region and can be identified as a grain boundary. Specifically, the displacement at which the value of | β 2- β 1 | is 0.5 ° or more is relatively high between two measurement points adjacent to each other and having an interval of 1 mm in the secondary recrystallized grain. Exists with frequency.
[0033]
　In the grain-oriented electrical steel sheet according to the present embodiment, by precisely controlling the manufacturing conditions as described later, grain boundaries (grains that divide secondary recrystallized grains) that satisfy the boundary condition BA and do not satisfy the boundary condition BB are satisfied. The world) is intentionally created. In the grain-oriented electrical steel sheet according to the present embodiment, the secondary recrystallized grains are divided into small regions having slightly different displacement angles β, and magnetostriction in the low magnetic field region is reduced.
[0034]
　Hereinafter, the grain-oriented electrical steel sheet according to the present embodiment will be described in detail.
[0035]
1. 1. Crystal Orientation
　First, the description of the crystal orientation in the present embodiment will be described.
　In the present embodiment, two {110} <001> orientations of "actual crystal {110} <001> orientation" and "ideal {110} <001> orientation" are distinguished. The reason for this is that in the present embodiment, it is necessary to distinguish between the {110} <001> orientation when displaying the crystal orientation of the practical steel sheet and the {110} <001> orientation as the academic crystal orientation. Because.
[0036]
　Generally, in the measurement of the crystal orientation of a recrystallized practical steel sheet, the crystal orientation is defined without strictly distinguishing the angle difference of about ± 2.5 °. In the case of conventional grain-oriented electrical steel sheets, the angular range of about ± 2.5 ° centered on the geometrically exact {110} <001> orientation is defined as the "{110} <001> orientation". .. However, in this embodiment, it is necessary to clearly distinguish the angle difference of ± 2.5 ° or less.
[0037]
　Therefore, in the present embodiment, when the orientation of the grain-oriented electrical steel sheet is meant in a practical sense, it is simply described as "{110} <001> orientation (Goss orientation)" as in the conventional case. On the other hand, when the {110} <001> orientation as a geometrically exact crystal orientation is meant, in order to avoid confusion with the {110} <001> orientation used in conventional publicly known documents and the like, " "Ideal {110} <001> direction (ideal Goss direction)".
[0038]
　Therefore, in the present embodiment, for example, there is a description that "the {110} <001> orientation of the grain-oriented electrical steel sheet according to the present embodiment deviates by 2 ° from the ideal {110} <001> orientation." Sometimes.
[0039]
　Further, in the present embodiment, the following four angles α, β, γ, and φ related to the crystal orientation observed in the grain-oriented electrical steel sheet are used.
[0040]
　Deviation angle α: The deviation angle of the crystal orientation observed on the grain-oriented electrical steel sheet from the ideal {110} <001> orientation around the rolling surface normal direction Z.
　Deviation angle β: The deviation angle of the crystal orientation observed on the grain-oriented electrical steel sheet from the ideal {110} <001> orientation around the rolling perpendicular direction C.
　Deviation angle γ: The deviation angle of the crystal orientation observed on the grain-oriented electrical steel sheet from the ideal {110} <001> orientation around the rolling direction L.
　A schematic diagram of the deviation angle α, the deviation angle β, and the deviation angle γ is shown in FIG.
[0041]
　Angle φ: The deviation angles of the crystal orientations measured at two measurement points adjacent to each other on the rolled surface of the directional electromagnetic steel plate and having an interval of 1 mm are (α 1 , β 1 , γ 1 ) and (α 2 ) , respectively. , Β 2 , γ 2 ), the angle obtained by φ = [(α 2- α 1 ) 2 + (β 2- β 1 ) 2 + (γ 2- γ 1 ) 2 ] 1/2 .
　This angle φ may be described as “spatial three-dimensional directional difference”.
[0042]
2. Crystal grain boundaries of grain boundaries of grain boundaries
　The grain boundaries of grain boundaries according to this embodiment are conventionally recognized as grain boundaries, which occur during the growth of secondary recrystallized grains in order to control the deviation angle β. Utilize local changes in crystal orientation that were not present. In the following description, the above-mentioned directional change that occurs so as to divide the inside of one secondary recrystallized grain into small regions having slightly different deviation angles β may be described as “switching”.
　Further, the crystal grain boundary (grain boundary satisfying the boundary condition BA) considering the angle difference of the deviation angle β is described as "β grain boundary", and the crystal grain distinguished by the β grain boundary as the boundary is described as "β crystal grain". Sometimes.
[0043]
　Further, regarding the magnetostriction (λp-p@1.5T) when excited at 1.5T, which is a characteristic related to the present embodiment, in the following description, it is simply described as “low magnetic field (at) magnetostriction”. There is.
[0044]
　It is considered that the above switching occurs in the process in which the change in crystal orientation is about 1 ° (less than 2 °) and the growth of the secondary recrystallized grains continues. Details will be described later in relation to the production method, but it is important to grow the secondary recrystallized grains in a situation where switching is likely to occur. For example, it is important to start the secondary recrystallization at a relatively low temperature by controlling the primary recrystallization particle size and to continue the secondary recrystallization to a high temperature by controlling the type and amount of the inhibitor.
[0045]
　The reason why the control of the deviation angle β affects the low magnetic field magnetostriction is not always clear, but it is presumed as follows.
[0046]
　Generally, the magnetization behavior in a low magnetic field is caused by the movement of the 180 ° magnetic domain. It is considered that this movement of the magnetic domain is affected by the continuity of the magnetic domain with the adjacent crystal grains especially in the vicinity of the grain boundary, and the orientation difference with the adjacent grain may be linked to the magnitude of the obstacle of the magnetization behavior. As described above, since secondary recrystallization in a practical grain-oriented electrical steel sheet proceeds in a state of being wound around a coil, it is conceivable that the difference in the deviation angle β between adjacent crystal grains at the grain boundaries becomes large. .. In the switching controlled in the present embodiment, switching (local orientation change) occurs frequently in one secondary recrystallized grain, so that the relative orientation difference with the adjacent grain is reduced and the directionality is directional. It is considered that it acts to enhance the continuity of the crystal orientation in the entire electromagnetic steel sheet.
[0047]
　In this embodiment, two types of boundary conditions are defined for changes in crystal orientation including switching. In this embodiment, the definition of "grain boundary" based on these boundary conditions is important.
[0048]
　Currently, the crystal orientation of practically manufactured grain-oriented electrical steel sheets is controlled so that the deviation angle between the rolling direction and the <001> direction is approximately 5 ° or less. This control is the same for the grain-oriented electrical steel sheet according to the present embodiment. Therefore, when defining the "grain boundaries" of grain-oriented electrical steel sheets, the "boundary where the orientation difference between adjacent regions is 15 ° or more", which is the general definition of grain boundaries (large tilt angle grain boundaries), is applied. Can't. For example, in a conventional grain-oriented electrical steel sheet, grain boundaries are revealed by macro-etching of the steel sheet surface, and the crystal orientation difference between the two side regions of the grain boundaries is usually about 2 to 3 °.
[0049]
　In this embodiment, as will be described later, it is necessary to strictly define the boundary between crystals. Therefore, as a method for specifying grain boundaries, a visual-based method such as macro etching is not adopted.
[0050]
　In the present embodiment, in order to specify the grain boundaries, measurement lines including at least 500 measurement points are set on the rolled surface at 1 mm intervals, and the crystal orientation is measured. For example, the crystal orientation may be measured by an X-ray diffraction method (Laue method). The Laue method is a method of irradiating a steel sheet with an X-ray beam and analyzing the transmitted or reflected diffraction spots. By analyzing the diffraction spots, the crystal orientation of the place where the X-ray beam is irradiated can be identified. By analyzing the diffraction spots at a plurality of locations by changing the irradiation position, the crystal orientation distribution at each irradiation position can be measured. The Laue method is a method suitable for measuring the crystal orientation of a metal structure having coarse crystal grains.
[0051]
　The number of measurement points for the crystal orientation may be at least 500, but it is preferable to appropriately increase the number of measurement points according to the size of the secondary recrystallized grains. For example, when the number of secondary recrystallized grains contained in the measurement line is less than 10 when the measurement point for measuring the crystal orientation is 500 points, 10 or more secondary recrystallized grains are included in the measurement line. It is preferable to extend the above measurement line by increasing the number of measurement points at 1 mm intervals.
[0052]
　The crystal orientation is measured at 1 mm intervals on the rolled surface, and then the above-mentioned deviation angle α, deviation angle β, and deviation angle γ are specified for each measurement point. Based on the deviation angle at each specified measurement point, it is determined whether or not there is a grain boundary between two adjacent measurement points. Specifically, it is determined whether or not the two adjacent measurement points satisfy the above-mentioned boundary condition BA and / or boundary condition BB.
[0053]
　Specifically, when the deviation angles of the crystal orientations measured at two adjacent measurement points are expressed as (α 1 , β 1 , γ 1 ) and (α 2 , β 2 , γ 2 ), respectively, the boundary condition BA Is defined as | β 2- β 1 | ≧ 0.5 °, and the boundary condition BB is [(α 2- α 1 ) 2 + (β 2- β 1 ) 2 + (γ 2- γ 1 ) 2 ] 1 It is defined as / 2 ≧ 2.0 °. It is determined whether or not there is a grain boundary satisfying the boundary condition BA and / or the boundary condition BB between two adjacent measurement points.
[0054]
　The grain boundary satisfying the boundary condition BB has a spatial three-dimensional orientation difference (angle φ) between two points sandwiching the grain boundary of 2.0 ° or more, and this grain boundary was recognized by macro etching. It can be said that it is almost the same as the grain boundary of the conventional secondary recrystallized grains.
[0055]
　Apart from the grain boundaries that satisfy the above boundary condition BB, the directional electromagnetic steel sheet according to the present embodiment has grain boundaries that are strongly related to "switching", specifically, the boundary condition BA that satisfies the boundary condition BA. Grain boundaries that do not satisfy BB are present at a relatively high frequency. The grain boundaries defined in this way correspond to the grain boundaries that divide one secondary recrystallized grain into small regions with slightly different deviation angles β.
[0056]
　The above two grain boundaries can also be determined using different measurement data. However, considering the time and effort of measurement and the deviation from the actual situation due to the difference in data, the deviation angle of the crystal orientation obtained from the same measurement line (at least 500 measurement points at 1 mm intervals on the rolled surface) is used. Therefore, it is preferable to obtain the above two grain boundaries.
[0057]
　Since the directional electromagnetic steel plate according to the present embodiment has a grain boundary satisfying the boundary condition BB and a grain boundary satisfying the boundary condition BA and not satisfying the boundary condition BB at a relatively high frequency, it is secondary. The inside of the recrystallized grains is divided into small regions having slightly different deviation angles β, and as a result, magnetostriction in the low magnetic field region is reduced.
[0058]
　In this embodiment, it is sufficient that the steel sheet has a "grain boundary that satisfies the boundary condition BA and does not satisfy the boundary condition BB". However, in order to substantially reduce the magnetostriction in the low magnetic field region, it is preferable that grain boundaries satisfying the boundary condition BA and not satisfying the boundary condition BB exist at a relatively high frequency.
[0059]
　For example, the present embodiment is characterized in that the inside of the secondary recrystallized grains is divided into small regions having slightly different deviation angles β, so that the β grain boundaries are relatively larger than those of the conventional secondary recrystallized grain boundaries. It is preferably present at a high frequency.
[0060]
　Specifically, when the crystal orientation is measured at at least 500 measurement points at 1 mm intervals on the rolled surface, the deviation angle is specified at each measurement point, and the boundary condition is determined at two adjacent measurement points. The "grain boundaries satisfying the boundary condition BA" may be present at a ratio of 1.10 times or more than the "grain boundaries satisfying the boundary condition BB". That is, when the boundary condition is determined as described above, the value obtained by dividing the "number of boundaries satisfying the boundary condition BA" by the "number of boundaries satisfying the boundary condition BB" may be 1.10 or more. In the present embodiment, when the above value is 1.10 or more, it is determined that the grain grain boundary satisfying the boundary condition BA and not satisfying the boundary condition BB exists in the grain-oriented electrical steel sheet.
[0061]
　The upper limit of the value obtained by dividing the "number of boundaries satisfying the boundary condition BA" by the "number of boundaries satisfying the boundary condition BB" is not particularly limited. For example, this value may be 80 or less, 40 or less, and 30 or less.
[0062]
[Second Embodiment]
　Subsequently, the grain-oriented electrical steel sheet according to the second embodiment of the present invention will be described below. Further, in each of the embodiments described below, the differences from the first embodiment will be mainly described, and the other features will be the same as those of the first embodiment, and duplicate description will be omitted.
[0063]
　In the directional electromagnetic steel sheet according to the second embodiment of the present invention, the particle size of the β crystal grains in the rolling direction is smaller than the particle size of the secondary recrystallized grains in the rolling direction. That is, the grain-oriented electrical steel sheet according to the present embodiment has β crystal grains and secondary recrystallized grains whose particle size is controlled with respect to the rolling direction.
[0064]
　Specifically, the grain-oriented electrical steel sheet according to the present embodiment, the average crystal grain size in the rolling direction L obtained based on the boundary conditions BA particle size RA L is defined as the rolling direction L obtained based on the boundary conditions BB When the average crystal grain size of is defined as the particle size RB L , the
　particle size RA L and the particle size RB L satisfy 1.10 ≦ RB L ÷ RA. Also, RB L ÷ RA L is preferably ≦ 80.
[0065]
　This provision describes the above-mentioned "switching" situation with respect to the rolling direction. That is, the boundary where | β 2- β 1 | is 0.5 ° or more and the angle φ is less than 2 ° in the secondary recrystallized grains whose grain boundaries are the boundaries where the angle φ is 2 ° or more. It means that the crystal grains containing at least one of the above are present at an appropriate frequency with respect to the rolling direction. In the present embodiment, the status of this switch, the rolling direction of the grain size RA L and particle size RB L defines evaluated by.
[0066]
　FIG. 2 is a schematic view showing the grain boundaries of the secondary recrystallized grains of the grain-oriented electrical steel sheet and the switching situation occurring in the secondary recrystallized grains. In FIG. 2, the steel sheet immediately after finish annealing (immediately after secondary recrystallization) is wound around a coil and has a curvature, and the steel sheet after flattening (during use) is unwound from the coil. Is shown.
[0067]
　As shown in FIG. 2, when the steel sheet is wound around a coil, the rolling direction of the steel sheet (longitudinal direction of the steel sheet) is curved according to the curvature of the steel sheet in space. On the other hand, in general, a crystal that grows during secondary recrystallization does not change its orientation in space. Therefore, in one crystal grain, the angle formed by the rolling direction and the crystal direction changes depending on the position in the space. This change increases as the crystal grains grow. That is, in the vicinity of the grain boundaries of the secondary recrystallized grains, which are coarsened enough to reach other secondary recrystallized grains at the final stage of grain growth, the orientation change due to the curvature of the steel sheet becomes particularly large.
[0068]
　When such secondary recrystallized grains are adjacent to each other, the orientation difference between the adjacent crystal grains (direction difference at the crystal grain boundary) is larger than the orientation difference that each crystal grain had at the time of formation. growing. That is, even if each crystal grain itself (recrystallized nucleus) is generated as a crystal grain that is close to the Goss orientation and has a relatively small orientation difference, the orientation difference at the grain boundary at the time when the grain grows and is adjacent to each other. Will be bigger.
[0069]
　For example, consider the case where secondary recrystallization proceeds in a state where the steel sheet is wound as a coil having a diameter of about 1000 mm. When this steel sheet is finished and annealed and then rewound from the coil and flattened, an orientation change of about 0.1 ° per 1 mm in the rolling direction occurs due to the curvature of the steel sheet. The secondary recrystallized grains of the directional electromagnetic steel plate are coarse, and for example, if the crystal grain size in the rolling direction is 50 mm, the orientation difference at the grain boundaries of the crystal grains adjacent to the rolling direction is as much as 5 °.
[0070]
　In general secondary recrystallization, that is, secondary recrystallization in a conventional grain-oriented electrical steel sheet, switching (local change in crystal orientation) does not occur during grain growth of secondary recrystallized grains. Therefore, if the particle size in the rolling direction is about 50 mm, the orientation difference at the grain boundaries of the crystal grains adjacent to the rolling direction caused by the curvature of the steel sheet during secondary recrystallization is about 5 °.
[0071]
　On the other hand, in the grain-oriented electrical steel sheet according to the present embodiment, a local orientation change (switching) occurs during the progress of secondary recrystallization. As will be described later, this orientation change acts to suppress an increase in the grain boundary energy and surface energy of the crystal, and occurs so as to approach the orientation in which the crystal has high symmetry. In the grain-oriented electrical steel sheet according to the present embodiment, the crystal orientation is controlled in the vicinity of the Goss orientation, and the above switching basically occurs so as to approach the orientation in which the crystal symmetry is high, that is, the Goss orientation. That is, the switching acts to eliminate the orientation change caused by the curvature of the steel plate and return it to the Goss orientation for each secondary recrystallized grain. As a result, the orientation difference at the grain boundaries of the crystal grains adjacent to the rolling direction is smaller than when the switching does not occur.
[0072]
　As will be described later, the above switching is considered to be caused by the rearrangement of the dislocations remaining in the secondary recrystallized grains during the secondary recrystallization. Upon this rearrangement, the dislocations take a local arrangement, and the orientation change corresponding to the switching can be identified as a local boundary, i.e. the grain boundary described above. In the grain-oriented electrical steel sheet according to the present embodiment, the orientation change such that | β 2- β 1 | ≧ 0.5 ° is established between two measurement points adjacent to each other and having an interval of 1 mm in the secondary recrystallized grains. Can be identified.
[0073]
　In the grain-oriented electrical steel sheet according to the present embodiment, the grain size of the β crystal grains in the rolling direction is made smaller than the grain size of the secondary recrystallized grains in the rolling direction by controlling the above-mentioned “switching”. Specifically, beta grain particle diameter RA of the L and the particle size RB of secondary recrystallized grains L and is, 1.10 ≦ RB L ÷ RA L meet. Particle size RA L and a particle size RB L and is, by satisfying the above condition, magnetostriction in a low magnetic field region is preferably reduced.
[0074]
　Particle size RB L for small, or the particle size RB L is larger switches less particle size RA L because of the large, RB L / RA L If value is less than 1.10, the switching frequency is not sufficient , Low magnetic field magnetostriction may not be sufficiently improved. RB L / RA L value is preferably 1.30 or more, more preferably 1.50 or more, more preferably 2.0 or more, more preferably 3.0 or more, more preferably 5.0 or more.
[0075]
　RB L / RA L is not particularly limited on the upper limit of the value. High RB occurrence frequency switching L / RA L The larger the value, because the continuity of the crystal orientation of the whole grain-oriented electromagnetic steel sheet is increased, preferred for improvement of the magnetostriction. On the other hand, since switching is also a residual lattice defect in the crystal grains, there is a concern that if the frequency of occurrence is too high, the effect of improving iron loss may be particularly reduced. Therefore, RB L / RA L 80 may be mentioned as a practical maximum value of values. If particular care must be taken about the iron loss, RB L / RA L preferably 40, more preferably include 30 as the maximum value of values.
[0076]
Incidentally, RB L / RA L value may be less than 1.0. RB L is an average particle diameter in the rolling direction defined based on the grain boundaries at which the angle φ is 2 ° or more. On the other hand, RA L is | beta 2 -beta 1 | is the average particle size of the defined rolling direction on the basis of the grain boundary becomes 0.5 ° or more. Simply put, it seems that grain boundaries with a smaller lower limit of the angle difference are detected more frequently. That, RB L is always RA L becomes larger than, RB L / RA L value appears always to be 1.0 or more.
[0077]
　However, RB L is the particle diameter determined by the grain boundary based on the angle phi, RA L a particle diameter determined by the grain boundary based on the edge angle beta, RB L and RA L particle for obtaining the particle size at The definition of the world is different. Therefore, RB L / RA L in some cases value is less than 1.0.
[0078]
　For example, even if | β 2- β 1 | is less than 0.5 ° (for example, 0 °), if the deviation angle α and / or the deviation angle γ is large, the angle φ becomes sufficiently large. That is, there is a grain boundary that does not satisfy the boundary condition BA but satisfies the boundary condition BB. If such grain boundaries increase, the value of the particle size RB L becomes small, and as a result, the RB L / RA L value can be less than 1.0. In the present embodiment, each condition is controlled so that the frequency of switching due to the shift angle β increases. When the switching control is not sufficient and the deviation from the present embodiment is large, the shift angle β does not change and the RB L / R A L value becomes less than 1.0. Note that sufficiently increases the incidence of β grain boundaries in the present embodiment, RB L / RA L be an essential condition that the value is 1.10 or more, as already described.
[0079]
　Regarding the grain-oriented electrical steel sheet according to the present embodiment, the boundaries between two measurement points adjacent to each other on the rolled surface and having an interval of 1 mm are classified into Cases 1 to 4 in Table 1. The above particle diameter RB L is determined based on the grain boundaries satisfying the casing 1 and / or case 2 of Table 1, the particle size RA L is the grain boundary satisfying the casing 1 and / or the case 3 in Table 1 Find based on. For example, the deviation angle of the crystal orientation is measured on a measurement line including at least 500 measurement points along the rolling direction, and the average value of the line segment lengths sandwiched between the grain boundaries of Case 1 and / or Case 2 on this measurement line is calculated. the particle size RB L and. Similarly, in the above measuring line, a line segment length of the average value held between the grain boundaries of the case 1 and / or the case 3 particle size RA L and.
[0080]
[table 1]

[0081]
　RB L / RA L is the control of the value not affecting reason always clear downfield magnetostriction, as described schematically in Figure 2, the switching is one in the secondary recrystallized grains (local orientation By causing a change), the relative orientation difference with the adjacent grains is reduced (the crystal orientation change near the grain boundaries becomes gentle), and the continuity of the crystal orientation in the entire directional electromagnetic steel plate is enhanced. It is thought that it is acting on.
[0082]
[Third Embodiment]
　Subsequently, the grain-oriented electrical steel sheet according to the third embodiment of the present invention will be described below. In the following, the differences from the above-described embodiment will be mainly described, and duplicate description will be omitted.
[0083]
　In the directional electromagnetic steel plate according to the third embodiment of the present invention, the particle size of the β crystal grains in the direction perpendicular to the rolling direction is smaller than the particle size of the secondary recrystallized grains in the direction perpendicular to the rolling direction. That is, the grain-oriented electrical steel sheet according to the present embodiment has β crystal grains and secondary recrystallized grains whose particle size is controlled with respect to the direction perpendicular to rolling.
[0084]
　Specifically, the grain-oriented electrical steel sheet according to the present embodiment, the average crystal grain size of the perpendicular to the rolling direction C determined based on the boundary conditions BA particle size RA C perpendicular to the rolling which is defined as, obtained based on the boundary conditions BB particle size RB the mean crystal grain size of the direction C C when defined as,
　particle size RA C and a particle size RB C is a, 1.10 ≦ RB C ÷ RA C meet. Also, RB C ÷ RA C is preferably ≦ 80.
[0085]
　This provision describes the above-mentioned "switching" situation with respect to the direction perpendicular to rolling. That is, the boundary where | β 2- β 1 | is 0.5 ° or more and the angle φ is less than 2 ° in the secondary recrystallized grain whose grain boundary is the boundary where the angle φ is 2 ° or more. It means that the crystal grains containing at least one of the above are present at a reasonable frequency in the direction perpendicular to the rolling direction. In the present embodiment, the status of this switch, the particle diameter RA of the direction perpendicular to the rolling direction C and particle size RB C defined and evaluated by.
[0086]
　Particle size RB C for the small or the particle size RB C is larger switches less particle size RA C because of the large, RB C / RA C the value is less than 1.10, the switching frequency is not sufficient , Low magnetic field magnetostriction may not be sufficiently improved. RB C / RA C value is preferably 1.30 or more, more preferably 1.50 or more, more preferably 2.0 or more, more preferably 3.0 or more, more preferably 5.0 or more.
[0087]
　RB C / RA C There is no particular limitation on the upper limit of the value. High RB occurrence frequency switching C / RA C The greater the value, because the continuity of the crystal orientation of the whole grain-oriented electromagnetic steel sheet is increased, preferred for improvement of the magnetostriction. On the other hand, since switching is also a residual lattice defect in the crystal grains, there is a concern that if the frequency of occurrence is too high, the effect of improving iron loss may be particularly reduced. Therefore, RB C / RA C 80 can be mentioned as a practical maximum value of values. Particularly if necessary considerations for iron loss, RB C / RA C as the maximum value of the values, preferably 40, more preferably include 30.
[0088]
　Incidentally, RB C is the particle diameter determined by the grain boundary based on the angle phi, RA C is the particle diameter determined by the grain boundary based on the edge angle beta. RB C and RA C for the grain boundaries to determine the particle size Defining different, RB C / RA C sometimes value is less than 1.0.
[0089]
　The above particle diameter RB C is determined based on the grain boundaries satisfying the casing 1 and / or case 2 of Table 1, the particle size RA C is the grain boundary satisfying the casing 1 and / or the case 3 in Table 1 Find based on. For example, the deviation angle of the crystal orientation is measured on a measurement line including at least 500 measurement points along the rolling perpendicular direction, and the average value of the line segment lengths sandwiched between the grain boundaries of Case 1 and / or Case 2 on this measurement line. the particle size RB C and. Similarly, in the above measuring line, a line segment length of the average value held between the grain boundaries of the case 1 and / or the case 3 particle size RA C and.
[0090]
　RB C / RA C control value is not affected reason always clear downfield magnetostriction, but in one of the secondary recrystallized grains that switch (local orientation changes) occurs, the adjacent grains It is considered that the relative orientation difference is reduced and the continuity of the crystal orientation in the entire grain-oriented electrical steel sheet is enhanced.
[0091]
[Fourth Embodiment]
　Subsequently, the grain-oriented electrical steel sheet according to the fourth embodiment of the present invention will be described below. In the following, the differences from the above-described embodiment will be mainly described, and duplicate description will be omitted.
[0092]
　In the directional electromagnetic steel plate according to the fourth embodiment of the present invention, the particle size of the β crystal grains in the rolling direction is smaller than the particle size of the β crystal grains in the direction perpendicular to the rolling direction. That is, the grain-oriented electrical steel sheet according to the present embodiment has β crystal grains whose particle size is controlled with respect to the rolling direction and the rolling perpendicular direction.
[0093]
　Specifically, the grain-oriented electrical steel sheet according to the present embodiment, the average crystal grain size in the rolling direction L obtained based on the boundary conditions BA particle size RA L perpendicular to the rolling direction is defined as, obtained based on the boundary conditions BA the average grain size of C particle size RA C when defined as,
　particle size RA L and a particle size RA C and a, 1.15 ≦ RA C ÷ RA L meet. Furthermore, RA C ÷ RA L is preferably ≦ 10.
[0094]
　In the following description, the shape of the crystal grains may be described as "(in-plane) anisotropy" or "flat (shape)". The shape of these crystal grains describes the shape when observed from the surface (rolled surface) of the steel sheet. That is, the shape of the crystal grains does not consider the size in the plate thickness direction (observed shape in the plate thickness cross section). Incidentally, in the grain-oriented electrical steel sheet, almost all the crystal grains have the same size as the sheet thickness in the plate thickness direction. That is, in the grain-oriented electrical steel sheet, the thickness of the steel sheet is often occupied by one crystal grain except for a peculiar region such as the vicinity of the grain boundary.
[0095]
　RA and the C / RA L prescribed value, for the rolling direction and the direction perpendicular to the rolling direction, indicating the status of the "switching" described above. That is, it means that the frequency with which the local crystal orientation changes to the extent that it is recognized as switching differs depending on the in-plane direction of the steel sheet. In this embodiment, the status of this switch, the particle diameter RA of the two orthogonal directions in the steel sheet surface C and particle size RA L was assessed by defining.
[0096]
　RA C / RA L that value is greater than 1 may, beta grains are defined by switching Viewed on average, and stretched in the direction perpendicular to the rolling direction, and shown to have a flat form collapsed in the rolling direction There is. That is, it is shown that the morphology of the crystal grains defined by the β grain boundaries has anisotropy.
[0097]
　The reason why the low magnetic field magnetostriction is improved by the in-plane anisotropy of the β crystal grain shape is not clear, but it is considered as follows. As mentioned above, in a low magnetic field, "continuity" with adjacent crystal grains is important when the 180 ° magnetic domain moves. For example, when one secondary recrystallized grain is divided into small regions by switching, if the number of these small regions is the same (the area of ​​the small regions is the same), the shape of the small regions is more than isotropic. , The more anisotropic, the larger the abundance ratio of the boundary (β grain boundary) due to switching. That, RA C / RA L will be present frequency of switching is a local change of orientation is increased by controlling the value is considered to enhance the continuity of the crystal orientation of the whole grain-oriented electromagnetic steel sheet.
[0098]
　The anisotropy of the occurrence of such switching is some anisotropy existing in the steel plate before the secondary recrystallization: for example, the anisotropy of the shape of the primary recrystallized grain; the anisotropy of the shape of the hot-rolled plate crystal grain. Anisotropy of the crystal orientation distribution of the primary recrystallized grains (colony distribution); arrangement of precipitates stretched by hot spreading and precipitates crushed and arranged in a row in the rolling direction; It is considered to be caused by the distribution of precipitates due to fluctuations in the thermal history in the longitudinal direction; anisotropy of the crystal particle size distribution; However, the details of the generation mechanism are unknown. However, if the steel sheet in the secondary recrystallization has a temperature gradient, it gives direct anisotropy to the growth of crystal grains (dislocation disappearance and grain boundary formation). That is, the temperature gradient in the secondary recrystallization is a very effective control condition for controlling the anisotropy defined in the present embodiment. Details will be described in relation to the manufacturing method.
[0099]
　Further, although it is related to the above-mentioned process of giving anisotropy by the temperature gradient at the time of secondary recrystallization, the current general production is that the direction in which the β crystal grains are stretched in the present embodiment is the direction perpendicular to rolling. It is preferable to consider the method. In this case, the rolling direction of the grain size RA L is the particle size RA of the direction perpendicular to the rolling direction C becomes smaller than. The relationship between the rolling direction and the direction perpendicular to the rolling will be described in relation to the manufacturing method. The direction in which the β crystal grains are stretched is determined not by the temperature gradient but by the frequency of occurrence of β grain boundaries.
[0100]
　Particle size RA C due to the small or the particle size RA C is larger in particle size RA L because of the large, RA C / RA L If value is less than 1.15, the switching frequency is not sufficient, downfield Magnetostriction may not be sufficiently improved. RA C / RA L value is preferably 1.50 or more, more preferably 1.80 or more, more preferably 2.10 or more.

The scope of the claims
[Claim 1]
　By mass%,
　　Si: 2.0 to 7.0%,
　　Nb: 0 to 0.030%,
　　V: 0 to 0.030%,
　　Mo: 0 to 0.030%,
　　Ta: 0 to 0.030%. ,
　　W: 0 to 0.030%,
　　C: 0 to 0.0050%,
　　Mn: 0 to 1.0%,
　　S: 0 to 0.0150%,
　　Se: 0 to 0.0150%,
　　Al: 0 to 0.0650%,
　　N: 0 to 0.0050%,
　　Cu: 0 to 0.40%,
　　Bi: 0 to 0.010%,
　　B: 0 to 0.080%,
　　P: 0 to 0.50%,
　　Ti: 0 to 0.0150%,
　　Sn: 0 to 0.10%,
　　Sb: 0 to 0.10%,
　　Cr: 0 to 0.30%,
　　Ni: 0 to 1.0%,
　and the balance In
　a directional electromagnetic steel plate having a chemical composition consisting of Fe and impurities and having an texture oriented in the Goss orientation.
　The deviation angle from the ideal Goss direction with the rolling surface normal direction Z as the rotation axis is defined as α, the deviation angle from the ideal Goss direction with the
　rolling perpendicular direction C as the rotation axis is defined as β, and the
　rolling direction L is defined as β. The deviation angle from the ideal Goss orientation as the rotation axis is defined as γ, and the deviation angle of
　the crystal orientation measured at two measurement points adjacent to each other on the plate surface and having an interval of 1 mm is (α 1　β 1　γ 1 ). And (α 2　β 2　γ 2 ), the
　boundary condition BA is defined as | β 2- β 1 | ≧ 0.5 °, and the
　boundary condition BB is [(α 2- α 1 ) 2 + (β 2 −). β 1 ) 2 + (γ 2- γ 1)) 2 ] 1/2 ≧ 2.0 ° and when defining,
　the boundary conditions grain boundaries is not satisfied satisfied and the boundary condition BB of BA are present,
oriented electrical steel sheet, characterized in that.
[Claim 2]
　Wherein an average crystal grain size of the rolling direction L obtained based on the boundary conditions BA particle size RA L is defined as,
　the particle diameter RB of the average crystal grain size in the rolling direction L obtained based on the boundary conditions BB L defined as to time,
　the particle size RA L and the grain size RB L and is, 1.10 ≦ RB L ÷ RA L meet,
oriented electrical steel sheet according to claim 1, characterized in that.
[Claim 3]
　The boundary conditions the average crystal grain size of the perpendicular to the rolling direction C particle size RA obtained based on BA C is defined as,
　the direction perpendicular to the rolling direction C the average crystal grain size of the particle diameter RB of determined based on the boundary conditions BB C when defining the,
　the particle size RA C and the particle diameter RB C and is, 1.10 ≦ RB C ÷ RA C meet,
oriented electrical steel sheet according to claim 1 or claim 2, characterized in that ..
[Claim 4]
　The average crystal grain size in the rolling direction L obtained based on the boundary conditions BA particle size RA L is defined as,
　the average crystal grain size of the perpendicular to the rolling direction C obtained based on the boundary conditions BA particle size RA C and when defining,
　the particle size RA L and the grain size RA C and is, 1.15 ≦ RA C ÷ RA L meet,
that directionality according to any one of claims 1 to 3, wherein Electromagnetic steel plate.
[Claim 5]
　The average crystal grain size in the rolling direction L obtained based on the boundary conditions BB particle size RB L is defined as,
　the average crystal grain size of the perpendicular to the rolling direction C obtained based on the boundary conditions BB particle size RB C and when defining,
　the particle diameter RB L and the grain size RB C and is, 1.50 ≦ RB C ÷ RB L meet,
that directionality according to any one of claims 1 to 4, wherein Electromagnetic steel plate.
[Claim 6]
　Wherein an average crystal grain size of the rolling direction L obtained based on the boundary conditions BA particle size RA L is defined as,
　the particle diameter RB of the average crystal grain size in the rolling direction L obtained based on the boundary conditions BB L defined as and,
　the average crystal grain size of the perpendicular to the rolling direction C obtained based on the boundary conditions BA particle size RA C is defined as,
　the particle diameter of the average crystal grain size of the perpendicular to the rolling direction C obtained based on the boundary conditions BB RB C when defining the,
　the particle size RA L and the grain size RA C and the particle diameter RB L and the grain size RB C and
　is, (RB C × RA L ) ÷ (RB L × RA C ) <1
The directional electromagnetic steel sheet according to any one of claims 1 to 5, wherein the directional electromagnetic steel sheet satisfies .0 .
[Claim 7]
　The average crystal grain size in the rolling direction L obtained based on the boundary conditions BB particle size RB L is defined as,
　the average crystal grain size of the perpendicular to the rolling direction C obtained based on the boundary conditions BB particle size RB C and when defining,
　the particle diameter RB L and the diameter RB C is at 22mm or more,
the grain-oriented electrical steel sheet according to any one of claims 1 to 6, characterized in that.
[Claim 8]
　The average crystal grain size in the rolling direction L obtained based on the boundary conditions BA particle size RA L is defined as,
　the average crystal grain size of the perpendicular to the rolling direction C obtained based on the boundary conditions BA particle size RA C and when defining,
　the particle size RA L is at 30mm or less, the particle size RA C is 400mm or less,
the grain-oriented electrical steel sheet according to any one of claims 1 to 7, characterized in that.
[Claim 9]
　The directional electromagnetic steel according to any one of claims 1 to 8, wherein the standard deviation σ (| β |) of the absolute value of the deviation angle β is 0 ° or more and 1.70 ° or less. Steel plate.
[Claim 10]

Claims 1 to 9 　include, as the chemical composition, at least one selected from the group consisting of Nb, V, Mo, Ta, and W in a total amount of 0.0030 to 0.030% by mass. The grain-oriented electrical steel sheet according to any one of the above.
[Claim 11]
　The grain-oriented electrical steel sheet according to any one of claims 1 to 10, wherein the magnetic domain is subdivided by at least one of applying local microstrain or forming a local groove.
[Claim 12]
　The invention according to any one of claims 1 to 11, further comprising an intermediate layer arranged in contact with the grain-oriented electrical steel sheet and an insulating film arranged in contact with the intermediate layer. Directional electrical steel sheet.
[Claim 13]
　The grain-oriented electrical steel sheet according to claim 12, wherein the intermediate layer is a forsterite film having an average thickness of 1 to 3 μm.
[Claim 14]
　The grain-oriented electrical steel sheet according to claim 12, wherein the intermediate layer is an oxide film having an average thickness of 2 to 500 nm.