RU2802217C1 - Isotropic electrical steel sheet - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention is related to sheets of anisotropic electrical steel used as a material for iron cores of transformers. The sheets have the following chemical composition, %wt.: 2.0-7.0 Si, 0-0.030 Nb, 0-0.030 V, 0-0.030 Mo, 0-0.030 Ta, 0-0.030 W, not more than 0.0050 C, 0-1.0 Mn, 0-0.0150 S, 0-0.0150 Se, 0-0.0650 Al, 0-0.0050 N, 0-0.40 Cu, 0-0.010 Bi, 0-0.080 B, 0-0.50 P, 0-0.0150 Ti, 0-0.10 Sn, 0-0.10 Sb, 0-0.30 Cr, 0-1.0 Ni, the rest is Fe and impurities. The sheet contains the texture aligned with the Goss orientation. The texture of the sheet has a low-angle boundary that separates the interior of the secondarily recrystallized grain and satisfies the boundary condition BAγ and which does not satisfy the boundary condition BB, the grain size RAα_C and grain size RAγ_C satisfy the condition RAγ_C <RAα_C, and grain size RAβ_C and grain size RAγ_C satisfy the condition RAγ_C <RAβ_C, where the boundary condition BAα defined as |α_2-α₁|≥ 0.5° and grain size RAα_C is defined as the average grain size obtained from the boundary condition BAα in transverse direction C, boundary condition BAβ defined as |β_2-β₁ |≥ 0.5° and grain size RAβ_C is defined as the average grain size obtained from the boundary condition BAβ in transverse direction C, boundary condition BAγ defined as |γ_2-γ₁ | ≥ 0.5° and grain size RAγ_C is defined as the average grain size obtained from the boundary condition BAγ in the transverse direction C, the boundary condition BB is defined as [(α₂ - α₁)² + (β₂ - β₁)² + (γ₂ - γ₁)²]^1/2 ≥ 2.0°α defined as the angle of deviation from ideal Goss orientation based on an axis of rotation parallel to the Z normal direction, β is defined as the angle of deviation from ideal Goss orientation based on an axis of rotation parallel to the transverse direction C, γ is defined as the angle of deviation from the ideal Goss orientation based on the axis of rotation parallel to the rolling direction L, (α₁ β₁ γ₁) and (α₂ β₂ γ₂) are the deviation angles of the crystallographic orientations measured at two measurement points that are adjacent on the sheet surface and that are spaced 1 mm apart.

EFFECT: sheet has an improved level of magnetostriction rate and excellent magnetic loss characteristics.

4 cl, 3 dwg, 33 tbl, 3 ex

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

[0001] The present invention relates to an anisotropic electrical steel sheet.

BACKGROUND OF THE INVENTION

[0002] The anisotropic electrical steel sheet includes 7 mass% or less Si and has a secondary recrystallized texture that lines up in the {110}<001> orientation (Goss orientation). Here, the {110}<001> orientation means that the {110} plane of the crystal is aligned parallel to the rolled surface, and the <001> axis of the crystal is aligned parallel to the rolling direction.

[0003] The magnetic characteristics of the anisotropic electrical steel sheet are significantly affected by the degree of alignment in the {110}<001> orientation. In particular, the relationship between the rolling direction of the steel sheet, which is the main magnetization direction when using the steel sheet, and the <001> crystal direction, which is the easy magnetization direction, is considered to be important. Thus, in recent years, a practical anisotropic electrical steel sheet is controlled so that the angle formed by the <001> direction of the crystal and the rolling direction is within about 5°.

[0004] The deviation between the actual crystallographic orientation of the anisotropic electrical steel sheet and the ideal {110}<001> orientation can be represented by three components, which are the deviation angle α from the normal direction Z, the deviation angle β from the transverse direction C, and the deviation angle γ from the rolling direction L.

[0005] Figure 1 is a diagram illustrating deflection angle α, deflection angle β, and deflection angle γ. As shown in Figure 1, the deflection angle α is the angle formed by the <001> direction of the crystal projected onto the rolled surface and the rolling direction L when viewed in the normal Z direction. The deflection angle β is the angle formed by the <001> direction of the crystal projected on the cross section L (the section whose normal direction is the transverse direction) and the rolling direction L when viewed in the transverse direction C (the sheet width direction). The deflection angle γ is the angle formed by the <110> direction of the crystal projected onto the cross section C (the section whose normal direction is the rolling direction) and the normal direction Z when viewed in the rolling direction L.

[0006] Among these deflection angles α, β, and γ, deflection angle β is known to affect magnetostriction. Here, magnetostriction is a phenomenon in which the shape of a magnetic material changes when a magnetic field is applied. Since magnetostriction causes vibration and noise, it is required to reduce the magnetostriction of an anisotropic electrical steel sheet used for a transformer core and the like.

[0007] For example, Patent Documents 1-3 disclose control of the deflection angle β. Patent Documents 4 and 5 disclose the control of the deflection angle α in addition to the deflection angle β. Patent Document 6 discloses a method for improving magnetic loss performance by further classifying the degree of crystallographic orientation alignment using deflection angle α, deflection angle β, and deflection angle γ as indicators.

[0008] Patent Documents 7-9 disclose not only simple control of absolute values and average values of deviation angles α, β, and γ, but also control of fluctuations (deviations) therewith. Patent Documents 10-12 disclose the addition of Nb, V, and the like. into a sheet of anisotropic electrical steel.

[0009] Patent Document 13 proposes a method for predicting transformer noise due to magnetostriction. This method for predicting transformer noise uses a value called the magnetostriction velocity level (Lva) by applying A-weighting to the frequency response of human hearing, in which the shape of an AC-driven magnetostrictive signal is time-differentiated and converted to velocity. Patent Document 14 discloses that transformer noise is reduced by lowering the level of magnetostriction velocity (Lva). For example, Patent Document 14 discloses a method in which a strain is linearly applied to the surface of a steel sheet, magnetic domains are reduced, the rate of magnetostriction is reduced, and thus the noise of an anisotropic electrical steel sheet transformer is reduced.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0010] Patent Document 1: Japanese Unexamined Patent Application First Publication No. 2001-294996

Patent Document 2: Japanese Unexamined Patent Application First Publication No. 2005-240102

Patent Document 3: Japanese Unexamined Patent Application First Publication No. 2015-206114

Patent Document 4: Japanese Unexamined Patent Application First Publication No. 2004-60026

Patent Document 5: International Publication of PCT Application No. WO2016/056501

Patent Document 6: Japanese Unexamined Patent Application First Publication No. 2007-314826

Patent Document 7: Japanese Unexamined Patent Application First Publication No. 2001-192785

Patent Document 8: Japanese Unexamined Patent Application First Publication No. 2005-240079

Patent Document 9: Japanese Unexamined Patent Application First Publication No. 2012-052229

Patent Document 10: Japanese Unexamined Patent Application First Publication No. S52-024116

Patent Document 11: Japanese Unexamined Patent Application First Publication No. H02-200732

Patent Document 12: Japanese Patent (Granted) Publication No. 4962516

Patent Document 13: Japanese Patent (Granted) Publication No. 3456742

Patent Document 14: Japanese Unexamined Patent Application First Publication No. 2017-128765.

SUMMARY OF THE INVENTION

SOLVED TECHNICAL PROBLEM

[0011] As a result of research conducted by the present inventors, it has been found that although the conventional methods disclosed in Patent Documents 1-9 control crystallographic orientation, this is not sufficient to reduce magnetostriction. In particular, it has been found that lowering the level of the magnetostriction velocity (Lva) may not be sufficient.

[0012] Moreover, since the traditional methods disclosed in Patent Documents 10-12 contain only Nb and V, this is not enough to reduce the level of the magnetostriction velocity (Lva).

[0013] In addition, Patent Documents 13 and 14 disclose the relationship between the level of the magnetostriction speed (Lva) and the noise of the transformer, but simply try to reduce the level of the magnetostriction speed (Lva) by processing (refining the magnetic domain) which is carried out after obtaining the anisotropic electrical steel sheet. . Patent Documents 13 and 14 do not control the texture of the steel sheet, and this is not enough to lower the level of the magnetostriction velocity (Lva).

[0014] The present invention has been made in view of such situations where an anisotropic electrical steel sheet capable of reducing transformer noise is required. The object of the present invention is to provide an anisotropic electrical steel sheet in which the level of magnetostriction velocity (Lva) is improved. In particular, it is an object of the present invention to provide an anisotropic electrical steel sheet in which the level of magnetostriction velocity (Lva) is in the range of a medium to high magnetic field (especially in a magnetic field excited to be approximately 1.7- 1.9 T) is improved in addition to excellent magnetic loss characteristics.

SOLUTION

[0015] Aspects of the present invention are as follows.

[0016] (1) An anisotropic electrical steel sheet according to one aspect of the present invention includes in its chemical composition, in wt.%, 2.0-7.0% Si, 0-0.030% Nb, 0-0.030% V, 0-0.030% Mo, 0-0.030% Ta, 0-0.030% W, 0-0.0050% C, 0-1.0% Mn, 0-0.0150% S, 0-0.0150% Se, 0-0.0650% Al, 0-0.0050% N, 0-0.40% Cu, 0-0.010% Bi, 0-0.080% B, 0-0.50% P, 0-0.0150% Ti, 0-0.10% Sn, 0-0.10% Sb, 0-0.30% Cr, 0-1.0% Ni, and the rest consisting of Fe and impurities, and

includes a texture aligned with the Goss orientation, characterized in that,

when α is defined as the angle of deviation from the ideal Goss orientation based on the rotation axis parallel to the normal direction Z, when β is defined as the angle of deviation from the ideal Goss orientation based on the rotation axis parallel to the transverse direction C, when γ is defined as the angle of deviation from the ideal Goss orientation based on an axis of rotation parallel to the rolling direction L, when (α ₁ β ₁ γ ₁ ) and (α ₂ β ₂ γ ₂ ) are crystallographic orientation deflection angles measured at two measurement points that are adjacent on the sheet surface and that have interval 1 mm when the boundary condition BAα is defined as |α ₂ - α ₁ | ≥ 0.5° and the grain size RAα _C is defined as the average grain size obtained from the boundary condition BAα in the transverse direction C when the boundary condition BAβ is defined as |β ₂ - β ₁ | ≥ 0.5° and the grain size RAβ _C is defined as the average grain size obtained from the boundary condition BAβ in the transverse direction C when the boundary condition BAγ is defined as |γ ₂ - γ ₁ | ≥ 0.5° and the grain size RAγ _C is defined as the average grain size obtained based on the boundary condition BAγ in the transverse direction C, and when 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°,

there is a boundary that satisfies the boundary condition BAγ and which does not satisfy the boundary condition BB, the grain size RAα _C and the grain size RAγ _C satisfy the condition RAγ _C < RAα _C , and the grain size RAβ _C and the grain size RAγ _C satisfy the condition RAγ _C < RAβ _C .

(2) In the anisotropic electrical steel sheet of (1), when the grain size RB _C is determined as the average grain size obtained based on the boundary condition BB in the lateral direction C, the grain size RAγ _C and the grain size RB _C can satisfy Condition 1, 10 ≤ RB _C /RAγ _C .

(3) In the anisotropic electrical steel sheet of (1) or (2), the grain size RB _C may be 15 mm or more.

(4) In the anisotropic electrical steel sheet of any one of (1) to (3), the grain size RAγ _C may be 40 mm or less.

EFFECTS OF THE INVENTION

[0017] In accordance with the above aspects of the present invention, it is possible to provide an anisotropic electrical steel sheet in which the level of magnetostriction velocity (Lva) is in the range of medium to high magnetic field (especially in a magnetic field excited to be approximately 1.7- 1.9 T) is improved in addition to excellent magnetic loss characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 is a diagram illustrating a deflection angle α, a deflection angle β, and a deflection angle γ.

Fig. 2 is a cross-sectional view of an anisotropic electrical steel sheet in accordance with one embodiment of the present invention.

Fig. 3 is a process flow diagram illustrating a method for producing an anisotropic electrical steel sheet in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0019] One preferred embodiment of the present invention will now be described in detail. However, the present invention is not limited to only the configuration disclosed in this embodiment, and various modifications are possible without departing from the aspect of the present invention. In addition, the limiting range described below includes its lower and upper limits. However, a value represented with a "greater than" or "less than" expression is not included in the limiting range. Unless otherwise indicated, "%" referring to the chemical composition is "% by weight".

[0020] In general, in order to reduce magnetostriction, the crystallographic orientation was controlled so that the deflection angle β became low (more specifically, that the maximum and average absolute value |β| of the deflection angle β became small). In addition, in order to reduce the magnetostriction, the crystallographic orientation was controlled so that the difference between the minimum and maximum of the magnetostriction (hereinafter referred to as "λp-p") became low.

[0021] However, the inventors of the present invention investigated the relationship between the crystallographic orientation of an electrical steel sheet used as a practical iron core material and its noise. As a result, it has been found that even when using an anisotropic electrical steel sheet in which the magnetostriction is improved as in the conventional technique, noise in a practical environment is not sufficiently reduced.

[0022] The authors of the present invention suggest that the reason for this is as follows. For noise in a practical environment, it is not enough to estimate only the magnetostriction λp-p, and it seems that the change in the shape of the magnetostrictive waveform excited by alternating current with time is important. Thus, the inventors of the present invention investigated the level of the magnetostriction velocity (Lva) in which the time variation of the magnetostrictive waveform can be evaluated.

[0023] In order to understand the magnetic characteristics in the medium to high magnetic field range, the present inventors analyzed the ratio of the magnetostriction velocity level (Lva) at excitation up to 1.7 T, where magnetic characteristics are usually measured, the magnetostriction velocity level (Lva) at excitation up to approximately 1.9 T, magnetostriction, magnetic losses, crystallographic orientation deviation angles, etc.

[0024] A magnetic field of 1.7 T corresponds to the magnetic induction calculated for a commonly used transformer (or magnetic induction to evaluate electrical steel sheet as a whole). Thus, the vibration of the iron core appears to be reduced and the noise of the transformer is reduced by lowering the level of the magnetostriction velocity (Lva) upon excitation to 1.7 T.

[0025] The 1.9 T magnetic field does not match the magnetic induction calculated for a commonly used transformer. However, in a practical environment, the magnetic flux does not flow uniformly in the steel sheet, but is locally concentrated in a certain area. Thus, there is a region in the steel sheet where a magnetic flux of approximately 1.9 T flows locally. It is traditionally known that excessive magnetostriction occurs in a magnetic field of 1.9 T, which affects the vibration of the iron core. Thus, the vibration of the iron core appears to be reduced and the noise of the transformer is reduced by lowering the level of the magnetostriction velocity (Lva) upon excitation to 1.9 T. In other words, in order to reduce the noise of the transformer in practice, it is important not only to reduce the level of the magnetostriction velocity (Lva) during excitation to 1.7 T, but also to reduce the level of the magnetostriction velocity (Lva) during excitation to 1.9 T.

[0026] The reason why transformer noise is reduced by lowering the magnetostriction velocity level (Lva) is presumably as follows.

[0027] Magnetostriction occurs when the transformer is energized. The aforementioned magnetostriction causes the iron core to vibrate. The vibration of the iron core in the transformer causes the air to vibrate, which causes noise. Sound pressure noise can be estimated from the amount of change per unit time (speed).

[0028] In addition, the characteristics of the sound that can be perceived by people are not always constant at all frequencies and can be expressed by auditory characteristics, called A-weighting. The actual shape of a magnetostrictive waveform is not a sinusoidal waveform, but a waveform in which different frequencies overlap. Thus, the magnetostrictive waveform is Fourier transformed, the amplitude at each frequency is obtained, which is multiplied by the A-weighting, and thus the magnetostriction velocity level (Lva) can be obtained, which is an indicator close to the auditory characteristics of a real person.

[0029] When the aforementioned level of the magnetostriction velocity (Lva) is reduced, it is possible to suppress the vibration of the iron core caused by the frequency that people perceive among the noise of the transformer. Thus, it appears that the noise of the transformer can be effectively reduced.

[0030] As a result of studies carried out by the inventors of the present invention, it was confirmed that when the level of magnetostriction velocity (Lva) in the magnetic field upon excitation decreases to approximately 1.7 T and 1.9 T (hereinafter referred to as the "range of medium and high magnetic field"), the noise of the transformer can be effectively reduced with excellent magnetic loss characteristics.

[0031] As a result of further research by the present inventors, it was found that in order to reduce the level of magnetostriction velocity (Lva) in the medium and high magnetic field range, it is important to control the deflection angle γ in the crystallographic orientation of the electrical steel sheet. In particular, it is important to control the relationship between the deflection angle γ and the deflection angle α and the relationship between the deflection angle γ and the deflection angle β. In other words, it has been found that by optimally controlling the aforementioned deflection angle ratios, the level of magnetostriction velocity (Lva) in the medium and high magnetic field range can be reduced, and as a result, transformer noise can be further reduced.

[0032] In the past, in the anisotropic electrical steel sheet, priority was given to the <001> orientation, which is the easy magnetization axis aligned with the rolling direction, and it was considered that the deflection angle γ caused by the rotation of the crystal around the rolling direction L has little effect on the magnetic characteristics . Thus, a typical anisotropic electrical steel sheet was produced under such conditions that a secondary recrystallized grain was nucleated with precise orientation control and grown to maintain a crystallographic orientation mainly with respect to the deflection angle α and the deflection angle β. In general, it has been thought that it is difficult to accurately control the deflection angle γ in addition to controlling the deflection angle α and the deflection angle β.

[0033] The inventors of the present invention attempted to grow the secondarily recrystallized grain not with the preservation of crystallographic orientation, but with a change in crystallographic orientation. As a result, the present inventors have found that in order to reduce the level of the magnetostriction velocity (Lva) in the medium and high magnetic field range, it is advantageous to sufficiently induce orientation changes (sub-boundaries) that are local and low-angle, and which are usually not recognized as a boundary. during the growth of the secondarily recrystallized grain, and to divide one secondarily recrystallized grain into small domains, in each of which the deviation angle β is slightly different.

[0034] In particular, it has been found that in addition to dividing one secondary recrystallized grain into small domains by a subboundary, it has been found important to control the relationship between the deflection angle γ and the deflection angle α and the relationship between the deflection angle γ and the deflection angle β. More specifically, when the sub-boundaries resulting from changes in the deflection angle γ are formed larger than the sub-boundaries resulting from changes in the deflection angle α and the deflection angle β with respect to the lateral direction C, the level of the magnetostriction velocity (Lva) in the medium and high magnetic field range can be improved in addition to excellent magnetic loss characteristics.

[0035] In addition, the inventors of the present invention have found that in order to control the aforementioned orientation changes, it is important to consider the factor of easily causing orientation changes themselves and the factor of periodically causing orientation changes within one grain. It has been found that in order to easily induce the orientation changes themselves, it is effective to start the secondary recrystallization at a lower temperature, for example by adjusting the size of the primary recrystallized grain or by using elements such as Nb. In addition, it has been found that orientation changes can be caused intermittently up to a higher temperature within one grain during secondary recrystallization using AlN and the like, which is a traditional inhibitor at an appropriate temperature and in an appropriate atmosphere.

[0036] Next, the anisotropic electrical steel sheet according to this embodiment will be described in detail.

[0037] In the anisotropic electrical steel sheet according to this embodiment of the present invention, the secondary recrystallized grain is subdivided into a plurality of domains, in each of which the deflection angle is slightly different. In particular, the anisotropic electrical steel sheet according to this embodiment includes a local low-angle boundary that separates the interior of the recrystallized grain, in addition to a relatively high-angle boundary that corresponds to the recrystallized grain boundary.

[0038] In addition, in the anisotropic electrical steel sheet according to this embodiment of the present invention, the ratio between the deflection angle γ and the deflection angle α and the ratio between the deflection angle γ and the deflection angle β are advantageously controlled in the transverse direction C.

[0039] In particular, the anisotropic electrical steel sheet according to this embodiment includes in its chemical composition, in wt.%, 2.0-7.0% Si, 0-0.030% Nb, 0-0.030% V, 0 -0.030% Mo, 0-0.030% Ta, 0-0.030% W, 0-0.0050% C, 0-1.0% Mn, 0-0.0150% S, 0-0.0150% Se, 0 -0.0650% Al, 0-0.0050% N, 0-0.40% Cu, 0-0.010% Bi, 0-0.080% B, 0-0.50% P, 0-0.0150% Ti , 0-0.10% Sn, 0-0.10% Sb, 0-0.30% Cr, 0-1.0% Ni, and the rest, consisting of Fe and impurities, and includes texture aligned with Goss orientation. When α is defined as the angle of deviation from the ideal Goss orientation based on the rotation axis parallel to the normal direction Z, when β is defined as the angle of deviation from the ideal Goss orientation based on the rotation axis parallel to the transverse direction C, when γ is defined as the angle of deviation from the ideal Goss orientation based on an axis of rotation parallel to the rolling direction L, when (α ₁ β ₁ γ ₁ ) and (α ₂ β ₂ γ ₂ ) are crystallographic orientation deflection angles measured at two measurement points that are adjacent on the sheet surface and that have interval 1 mm when the boundary condition BAα is defined as |α ₂ - α ₁ | ≥ 0.5° and the grain size RAα _C is defined as the average grain size obtained from the boundary condition BAα in the transverse direction C when the boundary condition BAβ is defined as |β ₂ - β| ≥ 0.5° and the grain size RAβ _C is defined as the average grain size obtained from the boundary condition BAβ in the transverse direction C when the boundary condition BAγ is defined as |γ ₂ - γ ₁ | ≥ 0.5° and the grain size RAγ _C is defined as the average grain size obtained based on the boundary condition BAγ in the transverse direction C, and when 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°, there is a boundary that satisfies the boundary condition BAγ and which does not satisfy the boundary condition BB, the grain size RAα _C and the grain size RAγ _C satisfy the condition RAγ _C < RAα _C , and the grain size RAβ _C and the grain size RAγ _C satisfy the condition RAγ _C < RAβ _C .

[0040] Although the anisotropic electrical steel sheet according to this embodiment of the present invention includes a boundary that satisfies the boundary condition BAγ and which does not satisfy the boundary condition BB, as explained above, there may be a boundary that satisfies the boundary condition BAα and which does not satisfies the BB boundary condition, as well as a boundary that satisfies the BAβ boundary condition and which does not satisfy the BB boundary condition.

[0041] In the following description, the boundary condition BAα, the boundary condition BAβ, and the boundary condition BAγ may be referred to simply as "the boundary condition BA". Similarly, the average grain size RAα _C , the average grain size RAβ _C and the average grain size RAγ _C may be referred to simply as "average grain size RA".

[0042] The boundary that satisfies the BB boundary condition substantially corresponds to the secondary recrystallized grain boundary that is observed in macro-etching of a conventional anisotropic electrical steel sheet. In addition to the boundary that satisfies the BB boundary condition, the anisotropic electrical steel sheet according to this embodiment includes, with a relatively high frequency, a boundary that satisfies the BAγ boundary condition and which does not satisfy the BB boundary condition. The boundary that satisfies the boundary condition BAγ and which does not satisfy the boundary condition BB corresponds to a local low-angle boundary that separates the interior of the secondarily recrystallized grain. In particular, in this embodiment, the secondary recrystallized grain becomes divided into small domains, in each of which the angle of deflection is slightly different.

[0043] A conventional anisotropic electrical steel sheet may include a recrystallized grain boundary that satisfies the BB boundary condition. In addition, a conventional anisotropic electrical steel sheet may include deflection angle shift in the secondary recrystallized grain. However, since in the conventional anisotropic electrical steel sheet, the deflection angle tends to continuously shift in the secondary recrystallized grain, the deflection angle shift in the conventional anisotropic electrical steel sheet hardly satisfies the boundary condition BAγ.

[0044] For example, in a conventional anisotropic electrical steel sheet, long-distance (“far”) deflection angle shift in the recrystallized grain can be detected, but short-distance (“near”) deflection angle shift in the recrystallized grain ( it is difficult to satisfy the boundary condition BAγ) because the local shift is small. On the other hand, in the anisotropic electrical steel sheet according to the present embodiment, the deflection angle locally shifts in a short distance, which means that its shift can be detected as a boundary. Specifically, the anisotropic electrical steel sheet according to this embodiment includes, with a relatively high frequency, a boundary that satisfies the boundary condition BAγ and which does not satisfy the boundary condition BB between two measurement points that are adjacent in the secondary recrystallized grain and that have an interval of 1 mm.

[0045] In the anisotropic electrical steel sheet according to the present embodiment, a boundary that separates the interior of the recrystallized grain is deliberately created by optimal manufacturing control as described later. In addition, in the anisotropic electrical steel sheet according to this embodiment, the secondary recrystallized grain is brought to a state where the grain is divided into small domains where each deflection angle is slightly different, and the relationship between the deflection angle γ and the deflection angle α and the relationship between the deflection angle γ and the deflection angle β is controlled in the lateral direction C. As a result, the level of the magnetostriction velocity (Lva) in the medium and high magnetic field range is favorably improved.

1. Crystallographic orientation

[0046] The following describes the crystallographic orientation notation in this embodiment. In this embodiment, the orientation {110}<001> is divided into two orientations: "actual orientation {110}<001>" and "ideal orientation {110}<001>". The reason for this is that in this embodiment, it is necessary to distinguish between the {110}<001> orientation representing the crystallographic orientation of the practical steel sheet and the {110}<001> orientation representing the academic crystallographic orientation.

[0047] As a rule, when measuring the crystallographic orientation of a practical steel sheet after recrystallization, the crystallographic orientation is determined without clearly distinguishing a misorientation of approximately ±2.5°. In a conventional anisotropic electrical steel sheet, the "{110}<001> orientation" is considered to be a range of orientations within approximately ±2.5° around the geometrically ideal {110}<001> orientation. On the other hand, in this embodiment, it is necessary to accurately distinguish a misorientation of ±2.5° or less.

[0048] Thus, although in this embodiment, the expression "orientation {110}<001> (Goss orientation)" is used as usual to express the actual orientation of the anisotropic electrical steel sheet, the expression is used to express the geometrically ideal orientation {110}<001> "ideal orientation {110}<001> (ideal Goss orientation)" to avoid confusion with the {110}<001> orientation used in regular publications.

[0049] For example, in this embodiment, the following explanation could be included: "the orientation {110}<001> of the anisotropic electrical steel sheet according to this embodiment deviates by 2° from the ideal orientation {110}<001>."

[0050] In addition, in this embodiment, the following four angles α, β, γ, and φ are used, which are related to the crystallographic orientation identified in the anisotropic electrical steel sheet.

[0051] Deviation angle α: Deviation angle from the ideal {110}<001> orientation around the Z normal direction, which is identified in the anisotropic electrical steel sheet.

Deviation angle β: Deviation angle from the ideal {110}<001> orientation around the lateral direction C, which is identified in the anisotropic electrical steel sheet.

Deviation angle γ: Deviation angle from the ideal {110}<001> orientation around the rolling direction L, which is identified in the anisotropic electrical steel sheet.

A diagram illustrating deflection angle α, deflection angle β, and deflection angle γ is shown in Figure 1.

[0052] Angle φ: An angle obtained as φ = [(α ₂ - α ₁ ) ² + (β ₂ - β ₁ ) ² + (γ ₂ - γ ₁ ) ² ] ^1/2 when (α ₁ β ₁ γ ₁ ) and (α ₂ β ₂ γ ₂ ) are crystallographic orientation deviation angles measured at two measurement points that are adjacent on the rolled surface of the anisotropic electrical steel sheet and that have an interval of 1 mm. The angle φ may be referred to as "three-dimensional misorientation".

2. Grain boundary of anisotropic electrical steel sheet

[0053] In the anisotropic electrical steel sheet according to this embodiment, the local change in orientation is used, in particular, to control the relationship between the deflection angle γ and the deflection angle α and the ratio between the deflection angle γ and the deflection angle β in the transverse direction C. Here, the aforementioned local change in orientation corresponds to the change in orientation that occurs during the growth of the secondarily recrystallized grain and which is usually not recognized as a boundary because the magnitude of this change is small. Hereinafter, the change in orientation that occurs, dividing one secondarily recrystallized grain into small domains, each of which has a slightly different deflection angle, may be referred to as "switching".

[0054] In addition, a boundary that separates one secondarily recrystallized grain may be referred to as a "subboundary", and a grain segmented by such a boundary, including a subboundary, may be referred to as a "subgrain". In addition, the boundary considering the misorientation of the deflection angle α (the boundary that satisfies the boundary condition BAα) may be referred to as "sub-boundary α", and the grain segmented using the sub-boundary α as the boundary may be referred to as "subgrain α". The boundary considering the misorientation of the deflection angle β (the boundary that satisfies the boundary condition BAβ) may be referred to as "sub-boundary β", and the grain segmented using the sub-boundary β as the boundary may be referred to as "sub-grain β". A boundary that takes into account the misorientation of the deflection angle γ (a boundary that satisfies the boundary condition BAγ) may be referred to as a “γ sub boundary”, and a grain segmented using a γ sub boundary as a boundary may be referred to as a “γ subgrain”.

[0055] In addition, hereinafter, the magnetostriction velocity level (Lva) in the medium and high magnetic field range, which is a characteristic related to this embodiment, may be referred to simply as the "magnetostriction velocity level".

[0056] It appears that the above switching has an orientation change of approximately 1° (less than 2°) and occurs during the growth of the secondarily recrystallized grain. Although the details are explained below in connection with the method of production, it is important to grow the secondarily recrystallized grain under conditions such that switching occurs easily. For example, it is important to initiate secondary recrystallization at a relatively low temperature by controlling the size of the primary recrystallized grain, and to maintain secondary recrystallization to a higher temperature by controlling the type and amount of inhibitor.

[0057] The reason why the deflection angle control affects the magnetic characteristics is not entirely clear, but is presumably considered as follows.

[0058] Typically, the magnetization occurs due to the movement of the 180-degree domain wall and the rotation of the magnetization from the direction of easy magnetization. It appears that the motion of the domain wall and the rotation of the magnetization, especially near the grain boundary, is affected by the continuity of the magnetic domain with the adjacent grain or the continuity of the magnetization direction, and that the misorientation with the adjacent grain affects the complexity of the magnetization. Since the switching is controlled in this embodiment, it appears that the switching (local reorientation) occurs at a relatively high frequency within one recrystallized grain, causes the relative misorientation with the adjacent grain to decrease, and thus increases the crystallographic orientation continuity in the anisotropic electrical steel sheet in in general.

[0059] In this embodiment, with regard to orientation change, including switching, multiple types of boundary conditions are defined. In this embodiment, it is important to define a "border" using these boundary conditions.

[0060] In a practically produced anisotropic electrical steel sheet, the deviation angle between the rolling direction and the <001> direction is controlled to be approximately 5° or less. In addition, the above adjustment is carried out in the anisotropic electrical steel sheet according to this embodiment. Thus, to define a "boundary" of an anisotropic electrical steel sheet, it is impossible to use the general definition of a grain boundary (border with a high angle of inclination), which is "a boundary at which the misorientation with the adjacent area is 15° or more." For example, in a conventional anisotropic electrical steel sheet, the grain boundary is manifested by macro-etching of the surface of the steel, and the misorientation between both sides of the grain boundary is generally about 2-3°.

[0061] In this embodiment, as described later, it is necessary to accurately determine the boundary between the crystals. Thus, no visual evaluation-based method such as macro-etching is used to measure the grain size.

[0062] In this embodiment, a measurement line including at least 500 measurement points at 1 mm intervals in the transverse direction is carried out to identify the boundary, and crystallographic orientations are measured. For example, crystallographic orientation can be measured using x-ray diffraction (Laue method). The Laue method consists in the fact that a steel sheet is irradiated with an X-ray beam and the diffraction spots are analyzed during transmission or reflection. By analyzing these diffraction spots, it is possible to identify the crystallographic orientation at the point irradiated by the X-ray. In addition, by changing the irradiated point and analyzing the diffraction spots in a plurality of points, it is possible to obtain a crystallographic orientation distribution from each irradiated point. The Laue method is the preferred method for identifying the crystallographic orientation of a metallographic structure in which the grains are coarse.

[0063] The number of measurement points for crystallographic orientation may be at least 500. Preferably, the number of measurement points is appropriately increased depending on the size of the secondarily recrystallized grain. For example, when the number of secondarily recrystallized grains occurring in the measurement line is less than 10 grains, in the case where the number of measurement points for crystallographic orientation identification is 500, it is preferable to extend the above measurement line by increasing the number of measurement points at 1 mm intervals so as to include 10 or more secondarily recrystallized grains into a measuring line.

[0064] Crystallographic orientations are identified at each measurement point at 1 mm intervals on the rolled surface, and then deflection angle α, deflection angle β, and deflection angle γ are identified at each measurement point. Based on the identified deflection angles at each measurement point, it is judged whether there is a boundary between two adjacent measurement points or not. In particular, it is judged whether or not two adjacent measurement points satisfy the boundary condition BA and/or the boundary condition BB.

[0065] In particular, when (α ₁ β ₁ γ ₁ ) and (α ₂ β ₂ γ ₂ ) are crystallographic orientation deviation angles measured at two adjacent measurement points, the boundary condition BAα is defined as |α ₂ - α ₁ | ≥ 0.5°, the boundary condition BAβ is defined as |β ₂ - β ₁ | ≥ 0.5°, the boundary condition BAγ is defined as |γ ₂ - γ 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°. In addition, it is judged whether or not there is a boundary between two adjacent measurement points that satisfies the boundary condition BA and/or the boundary condition BB.

[0066] A boundary that satisfies the BB boundary condition results in a three-dimensional misorientation (angle φ) of 2.0° or more between two points on either side of this boundary, and this boundary can be said to correspond to a conventional secondary recrystallized grain boundary, which manifested by macroetching.

[0067] In addition to the boundary that satisfies the boundary condition BB, the anisotropic electrical steel sheet according to this embodiment includes, with a relatively high frequency, a boundary directly related to "switching", namely, a boundary that satisfies the boundary condition BAγ and which is not satisfies the boundary condition BB. The boundary defined above corresponds to the boundary that divides one secondarily recrystallized grain into small domains, in each of which the deviation angle is slightly different.

[0068] The above boundaries can be determined by using data from various measurements. However, in view of the complexity of measurement and the discrepancy with the actual state caused by different data, it is preferable to determine the above boundaries using the deviation angles of crystallographic orientations obtained on the same measurement line (at least 500 measurement points with 1 mm interval on the rolled surface ).

[0069] The anisotropic electrical steel sheet according to this embodiment includes, at a relatively high frequency, a boundary that satisfies the BAγ boundary condition and which does not satisfy the BB boundary condition, in addition to having boundaries that satisfy the BB boundary condition. Thus, the secondarily recrystallized grain acquires such a state that it is divided into small domains, in each of which the deviation angle β is slightly different.

[0070] For example, in this embodiment, the secondary recrystallized grain is divided into small domains, where each deflection angle is slightly different, which means that it is preferable that the subboundary that separates one secondary recrystallized grain is switched on at a relatively high frequency compared to a conventional boundary secondarily. recrystallized grain.

[0071] In particular, when crystallographic orientations are measured at at least 500 measurement points at 1 mm intervals on a rolled surface, when deflection angles are identified at each measurement point, and when boundary conditions are applied to two adjacent measurement points, "a boundary that satisfies boundary condition BAγ" may be included at a frequency of 1.05 times or more compared to "a boundary that satisfies the boundary condition BB". In particular, when boundary conditions are applied as explained above, the quotient of the number of "boundaries that satisfy the boundary condition BAγ" by the number of "boundaries that satisfy the boundary condition BB" may be 1.05 or more. In this embodiment, when the above value is 1.05 or more, the anisotropic electrical steel sheet is considered to include "a boundary that satisfies the boundary condition BAγ and which does not satisfy the boundary condition BB".

[0072] The upper limit of the quotient of the number of "boundaries that satisfy the boundary condition BAγ" by the number of "boundaries that satisfy the boundary condition BB" is not particularly limited. For example, this value may be 80 or less, may be 40 or less, or may be 30 or less.

3. Grain boundary of anisotropic electrical steel sheet

[0073] In the anisotropic electrical steel sheet according to this embodiment, it is important to control the relationship between the deflection angle γ and the deflection angle α and the relationship between the deflection angle γ and the deflection angle β, in addition to dividing one secondary recrystallized grain into small domains by a subboundary. In particular, sub-boundaries resulting from changes in the deflection angle γ are formed more than sub-boundaries resulting from changes in the deflection angle α and the deflection angle β with respect to the transverse direction C.

[0074] In other words, when the grain size RAα _C is determined as the average grain size obtained based on the boundary condition BAα in the transverse direction C,

when the grain size RAβ _C is defined as the average grain size obtained from the boundary condition BAβ in the transverse direction C, and

when the grain size RAγ _C is defined as the average grain size obtained from the boundary condition BAγ in the transverse direction C,

the grain size RAα _C and the grain size RAγ _C satisfy the following expression (1), and

the grain size RAβ _C and the grain size RAγ _C satisfy the following expression (2).

RAγ _C < RAα _C ... (expression 1)

RAγ _C < RAβ _C ... (expression 2)

[0075] The fact that the anisotropic electrical steel sheet according to this embodiment satisfies expression (1) and expression (2) indicates that switching in deflection angle γ is more frequent than switching in deflection angle α and angle deviations β. It is believed that the structure of the magnetic domains of the steel sheet changes when more switching angle γ is introduced into the steel sheet than switching angle α and deflection angle β.

[0076] The detailed mechanism is not fully understood, but the following is contemplated. When a small change in orientation, such as switching over the deflection angle γ, occurs more than over the deflection angle α and the deflection angle β, the formation and disappearance of the closure domain can be suppressed without compromising the continuity of the 180-degree domain wall. As a result, the level of the magnetostriction velocity (Lva) can be reduced.

[0077] The ratio between grain size RAα _C and grain size RAγ _C preferably satisfies the condition RAγ _C /RAα _C ≤ 0.90, and more preferably satisfies the condition RAγ _C /RAα _C ≤ 0.80. The lower limit of the ratio RAγ _C /RAα _C is not particularly limited, but may be, for example, 0.20. Similarly, the ratio between grain size RAβ _C and grain size RAγ _C preferably satisfies the condition RAγ _C /RAβ _C ≤ 0.90, and more preferably satisfies the condition RAγ _C /RAβ _C ≤ 0.80. The lower limit of the ratio RAγ _C /RAβ _C is not particularly limited, but may be, for example, 0.20.

[0078] In addition, in the anisotropic electrical steel sheet according to the second embodiment of the present invention, it is preferable that the subgrain size based on the lateral deflection angle γ is smaller than the size of the secondary recrystallized grain in the lateral direction.

[0079] In particular, when the grain size RAγ _C is determined as the average grain size obtained based on the boundary condition BAγ in the transverse direction C, and

when the grain size RB _C is defined as the average grain size obtained from the boundary condition BB in the transverse direction C,

preferably, the grain size RAγ _C and the grain size RB _C satisfy the following expression (3).

1.10 ≤ RB _C /RAγ _C ... (expression 3)

[0080] The above sign characterizes the state of existence of "switching" in the transverse direction. In other words, the above feature characterizes a situation where, in a secondarily recrystallized grain having a grain boundary satisfying the condition that the angle φ is 2° or more, a grain having at least one boundary satisfying the condition that |γ ₂ - γ ₁ | is 0.5° or more, and the condition that the angle φ is less than 2° is included at a suitable frequency along the lateral direction. In this embodiment, the above switching situation is considered and evaluated using the above expression (3).

[0081] When the grain size RB _C is small, or when the grain size RAγ _C is large because the grain size RB _C is large but the switching is insufficient, the value of RB _C /RAγ _C becomes smaller than 1.10. When the value of RB _C /RAγ _C becomes less than 1.10, switching over the deflection angle γ may not be sufficient, and the level of the magnetostriction velocity may not be improved sufficiently. The value of RB _C /RAγ _C is preferably 1.30 or more, more preferably 1.50 or more, more preferably 2.0 or more, more preferably 3.0 or more, and even more preferably 5.0 or more.

[0082] The upper limit of the value of RB _C /RAγ _C is not particularly limited. When switching occurs sufficiently and the value of RB _C /RAγ _C becomes large, the crystallographic orientation continuity increases in the anisotropic electrical steel sheet as a whole, which is preferable for improving the magnetostriction rate level. On the other hand, switching causes residual defects in the crystal lattice of the grain. When switching occurs excessively, there is concern that the magnetic loss improvement effect may be reduced. Thus, the upper limit of the value of RB _C /RAγ _C can practically be 80. In particular, when magnetic losses must be taken into account, the upper limit of the value of RB _C /RAγ _C is preferably 40, and more preferably 30.

[0083] Here, there is a case where the value of RB _C /RAγ _C becomes less than 1.0. RB _C is the average grain size in the transverse direction, which is determined based on the boundary where the angle φ is 2° or more. On the other hand, RAγ _C is the average grain size in the transverse direction, which is determined based on the boundary, where |γ ₂ - γ ₁ | is 0.5° or more. Simply put, it appears that the boundary where the lower misorientation limit is lower is found more frequently. In other words, it appears that RB _C is always greater than RAγ _C and that the value of RB _C /RAγ _C is always 1.0 or more.

[0084] However, RB _C is the grain size that is obtained from the boundary based on the angle φ, and RAγ _C is the grain size that is obtained from the boundary based on the deflection angle γ. The determination of the grain boundaries to obtain grain sizes in relation to RB _C differs from the definition in relation to RAγ _C . Thus, the value of RB _C /RAγ _C may be less than 1.0.

[0085] For example, even when |γ ₂ - γ ₁ | is less than 0.5° (for example, 0°), provided that the deflection angle α and the deflection angle β are large, the angle φ becomes sufficiently large. In other words, there is a case where there is a boundary where the boundary condition BAγ is not satisfied, but the boundary condition BB is satisfied. As the above limit increases, the RB _C value decreases, and as a result, the RB _C /RAγ _C value may be less than 1.0. In this embodiment, each condition is controlled so that switching over the deflection angle γ occurs more frequently. When the switching control is insufficient and the departure from the desired state of this embodiment is large, there is no change in the deflection angle γ, and the value of RB _C /RAγ _C may be less than 1.0. In this embodiment, as mentioned above, it is preferable to sufficiently increase the frequency of occurrence of sub-boundary γ and control the value of RB _C /RAγ _C to be 1.10 or more.

[0086] Meanwhile, in the anisotropic electrical steel sheet according to this embodiment, misorientation between two measurement points that are adjacent on the surface of the sheet and that have an interval of 1 mm is classified into cases 1 to 4 shown in Table 1. The above RB _C is determined based on the boundary satisfying case 1 and/or case 2 shown in Table 1, and the aforementioned RAγ _C is determined based on the boundary satisfying case 1 and/or case 3 shown in Table 1. For example, the deviation angles of crystallographic orientations are measured on a measurement line including at least 500 measurement points along the transverse direction, and RB _C is defined as the average length of the line segment (section) between the boundaries satisfying case 1 and/or case 2 on the measurement line. Similarly, with respect to the deflection angle γ, the grain size RAγ _C is defined as the average length of the segment (cut) of the line between the boundaries (in particular, sub-boundaries γ) satisfying case 1 and/or case 3 on the measurement line.

[0087] [Table 1]

Case 1 Case 2 Case 3 Case 4 Boundary condition BA 0.5° or more less than 0.5° 0.5° or more less than 0.5° Boundary condition BB 2.0° or more 2.0° or more less than 2.0° less than 2.0° border type "usual boundary of the secondarily recrystallized grain, which is traditionally observed" and "subboundary" "the usual boundary of a secondarily recrystallized grain, which is traditionally observed" "subboundary" "not a boundary, in particular, not the "usual secondary recrystallized grain boundary that is traditionally observed" and not the "β subboundary"

[0088] The reason why controlling the RB _C /RAγ _C value affects the level of the magnetostriction velocity (Lva) is not entirely clear, but is presumably considered as follows. It appears that when a small change in orientation occurs, such as switching over the deflection angle γ, the formation and disappearance of a closure domain is suppressed without compromising the continuity of the 180-degree domain wall.

[0089] In addition, in the anisotropic electrical steel sheet according to this embodiment, it is preferable that the grain size RB _C is 15 mm or more.

[0090] It appears that the switching occurs due to the accumulation of dislocations during the growth of the secondarily recrystallized grain. Thus, after one switch has occurred and before the next switch occurs, it is necessary for the secondarily recrystallized grain to grow to a certain size. When the grain size RB _C is smaller than 15 mm, switching may be difficult, and it may be difficult to sufficiently improve the level of the magnetostriction rate by switching. The RB _C grain size is preferably 22 mm or more, more preferably 30 mm or more, and even more preferably 40 mm or more.

[0091] The upper limit of grain size RB _C is not particularly limited. For example, in a typical production of anisotropic electrical steel sheet, since the grain having the {110}<001> orientation is formed due to secondary recrystallization growth by heating the coiled steel sheet after primary recrystallization, the secondary recrystallized grain may grow from the edge of the coil where the temperature rises earlier, towards the center of the roll, where the temperature rises later. In this production method, when the width of the roll is 1000 mm, for example, the upper limit of the grain size RB _C may be 500 mm, which is about half the width of the roll. Of course, in each embodiment, it is possible that the grain size RB _C is equal to the full width of the roll.

[0092] In addition, in the anisotropic electrical steel sheet according to this embodiment, it is preferable that the grain size RAγ _C is 40 mm or less.

[0093] Since such a state in which the grain size of RAγ _C is smaller means that the frequency of occurrence of switching in the lateral direction is higher, the grain size of RAγ _C is preferably 40 mm or less. The grain size RAγ _C is preferably 30 mm or less.

[0094] The lower limit of the grain size RAγ _C is not particularly limited. Since the crystallographic orientation measurement interval is 1 mm in this embodiment, the lower limit of the grain size RAγ _C may be 1 mm. However, in this embodiment, even when the grain size RAγ _C becomes smaller than 1 mm by making the crystallographic orientation measurement interval smaller than 1 mm, the aforementioned steel sheet is not excluded. Here, switching to some extent causes residual defects in the crystal lattice. When switching is excessive, there is concern that magnetic performance will be negatively affected. The lower limit of the grain size RAγ _C is preferably 5 mm in view of industrial feasibility.

[0095] In the anisotropic electrical steel sheet according to this embodiment, the grain size measurement result includes an uncertainty of 2 mm for each grain at most. Thus, when measuring grain size (when crystallographic orientations are measured at at least 500 measurement points at 1 mm intervals on the rolled surface), it is preferable that the above measurements are carried out under such conditions that there are a total of 5 or more measurement regions, and they are sufficient spaced from each other in a direction orthogonal to the in-plane grain size determination direction, in particular by regions where different grains can be measured. By calculating the average value for all grain sizes obtained from measurements in 5 or more areas in total, the above uncertainty can be reduced. For example, measurements can be made in 5 or more areas that are sufficiently spaced apart in the rolling direction to measure the aforementioned grain sizes, and then the average grain size can be determined from the orientation measurements at these 2500 or more measurement points in total.

4. Deviation angle from ideal orientation {110}<001>

[0096] In the steel sheet in which the switching explained above occurs sufficiently, the "deflection angle" tends to be adjusted within the characteristic range. However, in order to obtain the effects of this embodiment, in particular, it is not essential to control the crystallographic orientation to align in a certain direction, as in conventional orientation control, for example, to control the absolute value and standard deviation of the deflection angle so that it is small. For example, in the case where the crystallographic orientation is gradually changed by switching in the deflection angle, this embodiment is not prevented from reducing the absolute value of the deflection angle to a value close to zero. In addition, for example, in the case where the crystallographic orientation is gradually changed by switching over the deflection angle, this embodiment does not interfere with the fact that the crystallographic orientation itself converges with the particular orientation, whereby the standard deviation of the deflection angle is reduced to a value, close to zero.

[0097] In this embodiment, it should not be considered that "one secondarily recrystallized grain is considered as a single crystal, and the secondly recrystallized grain has a strictly uniform crystallographic orientation." In other words, in this embodiment, small changes in orientation, which are usually not recognized as a boundary, are included in one large secondarily recrystallized grain, and it is necessary to detect these small changes in orientation.

[0098] Thus, for example, it is preferable that the crystallographic orientation measurement points are distributed at equal intervals in a predetermined area, which is located so as to be independent of the grain boundaries (grain boundaries). In particular, it is preferable that the measurement points are distributed at equal intervals, i.e. vertical and horizontal intervals of 5 mm, in an area of dimensions L mm × M mm (however L, M > 100), which includes at least 20 or more grains on the surface steel, and crystallographic orientations are measured at each measurement point, and thus data from 500 or more points are obtained. When a measurement point corresponds to a grain boundary or some defect, the data from that point is not used. In addition, it is necessary to expand the above measurement area depending on the area necessary to determine the magnetic characteristics of the steel sheet being evaluated (for example, with respect to a real coil, these are the measurement areas of the magnetic characteristics that should be described in the steel inspection certificate).

[0099] The anisotropic electrical steel sheet according to the above embodiment may have an intermediate layer and an insulating coating on the steel sheet. Crystallographic orientation, boundary, average grain size, etc. can be determined based on uncoated steel sheet and the like. In other words, when the anisotropic electrical steel sheet as the measurement sample has a coating or the like on its surface, crystallographic orientation or the like. can be measured after removal of the coating, etc.

[0100] For example, to remove the insulating coating, the coated anisotropic electrical steel sheet may be immersed in a hot alkaline solution. In particular, it is possible to remove an insulating coating from an anisotropic electrical steel sheet by immersing the steel sheet in an aqueous sodium hydroxide solution containing 30-50 mass% NaOH and 50-70 mass% H ₂ O at a temperature of 80-90°C for 5 -10 minutes, rinsing it with water and then drying it. In addition, the immersion time in aqueous sodium hydroxide solution can be adjusted depending on the thickness of the insulation coating.

[0101] Further, for example, to remove the intermediate layer, the anisotropic electrical steel sheet from which the insulating coating has been removed may be immersed in hot hydrochloric acid. In particular, it is possible to remove the intermediate layer by first examining the preferred concentration of hydrochloric acid to remove the intermediate layer, immersing the steel sheet in hydrochloric acid with the above concentration, such as 30-40 mass% HCl, at 80-90°C for 1-5 minutes , washing it with water and then drying it. In most cases, the layer and coating are removed by selectively using a solution, for example, an alkaline solution is used to remove the insulation coating, and hydrochloric acid is used to remove the intermediate layer.

5. Chemical composition

[0102] The anisotropic electrical steel sheet according to this embodiment includes basic elements in its chemical composition, optional elements as needed, and the rest consists of Fe and impurities.

[0103] The anisotropic electrical steel sheet according to this embodiment includes 2.0-7.0% Si (silicon) in mass percent as the main elements (primary alloying elements).

[0104] The Si content is preferably 2.0-7.0% in order to control the crystallographic orientation, lining it up in the {110}<001> orientation.

[0105] In this embodiment, the anisotropic electrical steel sheet may include impurities in its chemical composition. Impurities correspond to elements that contaminate steel during its industrial production from ores and scrap used as raw materials for steel production, or from the environment of the production process. For example, the upper limit of the impurity content may be 5% in total.

[0106] In addition, in this embodiment, the anisotropic electrical steel sheet may include optional elements in addition to the main elements and impurities. For example, as a replacement for the part of Fe that makes up the rest, an anisotropic electrical steel sheet may include optional elements such as Nb, V, Mo, Ta, W, C, Mn, S, Se, Al, N, Cu, Bi, B , P, Ti, Sn, Sb, Cr or Ni. Optional elements can be included as needed. Thus, the lower limit of the content of the corresponding optional elements should not be limited, and this lower limit may be 0%. In addition, even if the optional elements may be included as impurities, the above-mentioned effects are not affected.

0-0.030% Nb (niobium)

0-0.030% V (vanadium)

0-0.030% Mo (molybdenum)

0-0.030% Ta (tantalum)

0-0.030% W (tungsten)

[0107] Nb, V, Mo, Ta, and W can be used as elements having effects specific in this embodiment. In the following description, at least one element selected from the group consisting of Nb, V, Mo, Ta, and W may be referred to generally as an "Nb group element".

[0108] The Nb group element favorably influences the switching appearance that is characteristic of the anisotropic electrical steel sheet according to this embodiment. In this case, the element of the Nb group affects the appearance of switching precisely in the production process. Thus, the Nb group element does not need to be included in the final product, which is the anisotropic electrical steel sheet according to this embodiment. For example, the Nb group element may tend to be vented out of the system when cleaned during the final annealing described below. In other words, even when the Nb group element is included in the slab and causes the switching occurrence frequency to increase during production, the Nb group element can be removed from the system by refining annealing. As mentioned above, the Nb group element may not be found in the chemical composition of the final product.

[0109] Thus, in this embodiment, with respect to the amount of the Nb group element in the chemical composition of the anisotropic electrical steel sheet, which is the final product, only its upper limit is controlled. The upper limit of the Nb group element can suitably be 0.030%. On the other hand, as mentioned above, even when the Nb group element is used in the production process, the amount of the Nb group element in the final product may be zero. Thus, the lower limit of the group element Nb is not specifically limited. The lower limit of an element of the group Nb, respectively, can be equal to zero.

[0110] In this embodiment of the present invention, it is preferable that the anisotropic electrical steel sheet include in its chemical composition at least one element selected from the group consisting of Nb, V, Mo, Ta and W, and that their number is 0, 0030-0.030 wt.% in total.

[0111] It is unlikely that the amount of the Nb group element increased during production. Thus, when an Nb group element is found in the chemical composition of the final product, the above situation implies that the switch is controlled by the Nb group element during the manufacturing process. For favorable control of switching during production, the total amount of the Nb group element in the final product is preferably 0.003% or more, and more preferably 0.005% or more. On the other hand, when the total amount of the Nb group element in the final product is more than 0.030%, the switching occurrence frequency is maintained, but the magnetic characteristics may deteriorate. Thus, the total amount of the Nb group element in the final product is preferably 0.030% or less. The features of the group element Nb are explained later in connection with the method of production.

0-0.0050% C (carbon)

0-1.0% Mn (manganese)

0-0.0150% S (sulfur)

0-0.0150% Se (selenium)

0-0.0650% Al (acid soluble aluminum)

0-0.0050% N (nitrogen)

0-0.40% Cu (copper)

0-0.010% Bi (bismuth)

0-0.080% B (boron)

0-0.50% P (phosphorus)

0-0.0150% Ti (titanium)

0-0.10% Sn (tin)

0-0.10% Sb (antimony)

0-0.30% Cr (chromium)

0-1.0% Ni (nickel)

[0112] Optional elements may be included as needed. Thus, the lower limit of the content of the corresponding optional elements should not be limited, and this lower limit may be 0%. The total amount of S and Se is preferably 0-0.0150%. The total amount of S and Se means that at least one of S and Se is included and its/their amount corresponds to the above total amount.

[0113] In the anisotropic electrical steel sheet, the chemical composition changes relatively strongly (the amount of alloying element decreases) in the decarburization annealing and refining annealing during secondary recrystallization. Depending on the specific element, it can be reduced by refining annealing to an undetectable level (1 ppm or less) using a typical analytical method. The above-mentioned chemical composition of the anisotropic electrical steel sheet according to this embodiment is the chemical composition of the final product. In most cases, the chemical composition of the final product differs from the chemical composition of the slab as the starting material.

[0114] The chemical composition of the anisotropic electrical steel sheet according to this embodiment can be measured using typical steel analytical methods. For example, the chemical composition of an anisotropic electrical steel sheet can be measured using an inductively coupled plasma atomic emission spectrometer: inductively coupled plasma emission spectrometry/spectroscopy (ICP-AES). In particular, it is possible to obtain the chemical composition by measuring with a Shimadzu ICPS-8100 meter or the like. under a condition based on a pre-prepared calibration curve using 35 mm square specimens taken from an anisotropic electrical steel sheet. However, acid-soluble Al can be measured with ICP-AES using the filtrate after heating and dissolving the sample in acid. In addition, the content of C and S can be measured by the method of absorption in the infrared region of the spectrum during combustion, and the content of N can be measured by a thermoconductometric method by melting in an inert gas flow.

[0115] The above chemical composition is the composition of the anisotropic electrical steel sheet. When an anisotropic electrical steel sheet used as a measurement sample has an insulating coating or the like on its surface, the chemical composition is measured after removing the coating or the like. the aforementioned ways.

6. Structure of layers, etc.

[0116] In the anisotropic electrical steel sheet according to this embodiment, the layer structure on the steel sheet, magnetic domain refinement processing, and the like. not specifically limited. In this embodiment, an optional coating can be formed on the steel sheet according to purpose, and magnetic domain pulverization treatment can be applied according to need.

[0117] In the anisotropic electrical steel sheet according to this embodiment of the present invention, the intermediate layer may be positioned in contact with the anisotropic electrical steel sheet, and the insulating coating may be positioned in contact with the intermediate layer.

[0118] Figure 2 is a sectional view of an anisotropic electrical steel sheet in accordance with a preferred embodiment of the present invention. As shown in Figure 2, when considering a section whose cutting plane is parallel to the thickness direction, the anisotropic electrical steel sheet 10 (silicon steel sheet) according to this embodiment may have an intermediate layer 20 that is in contact with the anisotropic electrical steel sheet 10 (silicon steel sheet), and an insulating coating 30 which is in contact with the intermediate layer 20.

[0119] For example, the aforementioned intermediate layer may be a layer mainly containing oxides, a layer mainly containing carbides, a layer mainly containing nitrides, a layer mainly containing borides, a layer mainly containing silicides, a layer mainly containing phosphides, a layer mainly containing sulfides, a layer mainly containing intermetallic compounds, and the like. These intermediate layers can be formed by redox controlled atmosphere heat treatment, chemical vapor deposition (CVD), physical vapor deposition (PVD), and the like.

[0120] In the anisotropic electrical steel sheet according to this embodiment of the present invention, the intermediate layer may be a forsterite film with an average thickness of 1-3 µm. In this case, the forsterite film corresponds to a layer containing mainly Mg ₂ SiO ₄ . The interface between the forsterite film and the anisotropic electrical steel sheet becomes such an interface that the forsterite film penetrates the steel sheet when considering the above section.

[0121] In the anisotropic electrical steel sheet according to this embodiment of the present invention, the intermediate layer may be an oxide layer with an average thickness of 2-500 nm. In this case, the oxide layer corresponds to a layer containing mainly SiO ₂ . The interface between the oxide layer and the anisotropic electrical steel sheet becomes a smooth interface when considering the above section.

[0122] In addition, the above-mentioned insulating coating may be an insulating coating which mainly includes phosphate and colloidal silica and whose average thickness is 0.1-10 µm, an insulating coating which mainly includes alumina sol and boric acid and whose average thickness is is 0.5-8 µm, etc.

[0123] In the anisotropic electrical steel sheet according to this embodiment of the present invention, the magnetic domain can be refined by at least one of applying local small deformation and forming a local groove. Local small deformation or local groove can be applied or formed by laser, plasma, mechanical methods, etching or other methods. For example, a local small strain or local groove can be applied or formed linearly or pointwise so that it extends in a direction intersecting the rolling direction on the rolled surface of the steel sheet and so that it has a spacing of 2-10 mm in the rolling direction.

7. Production method

[0124] Next, the production method of the anisotropic electrical steel sheet according to this embodiment of the present invention will be described.

[0125] The production method of the anisotropic electrical steel sheet according to this embodiment is not limited to the following method. The following production method is an example of the production of an anisotropic electrical steel sheet according to this embodiment.

[0126] Figure 3 is a flow chart illustrating a method for manufacturing an anisotropic electrical steel sheet according to this embodiment of the present invention. As shown in Figure 3, the production method of the anisotropic electrical steel sheet (silicon steel sheet) according to this embodiment includes a casting process, a hot rolling process, a hot strip annealing process, a cold rolling process, a decarburization annealing process, an annealing separator coating process. and the final annealing process.

[0127] In particular, the production method of the anisotropic electrical steel sheet (silicon steel sheet) may be as follows.

During the casting process, a slab is cast so that its chemical composition includes, in wt.%, from 2.0 to 7.0% Si, from 0 to 0.030% Nb, from 0 to 0.030% of V, from 0 to 0.030% Mo , 0 to 0.030% Ta, 0 to 0.030% W, 0 to 0.0850% C, 0 to 1.0% Mn, 0 to 0.0350% S, 0 to 0.0350% Se , 0 to 0.0650% Al, 0 to 0.0120% N, 0 to 0.40% Cu, 0 to 0.010% Bi, 0 to 0.080% B, 0 to 0.50% P , 0 to 0.0150% Ti, 0 to 0.10% Sn, 0 to 0.10% Sb, 0 to 0.30% Cr, 0 to 1.0% Ni, and the rest consists of Fe and impurities.

In the decarburization annealing process, the primary recrystallized grain size is adjusted to 23 µm or less.

In the final annealing process, when the total amount of Nb, V, Mo, Ta and W in the chemical composition of the slab is 0.0030-0.030%,

at the heating stage

PH ₂ O/PH ₂ in the range of 700-800°C is controlled at the level of 0.050-1.0,

at least one of the following conditions is satisfied: PH ₂ O/PH ₂ in the range of 900-950°C must be 0.010-0.10, PH ₂ O/PH ₂ in the range of 950-1000°C must be 0.005-0.070, and PH ₂ O/PH ₂ in the range of 1000-1050°C should be 0.0010-0.030, the holding time in the range of 850-950°C is controlled at the level of 120-600 minutes, the holding time in the range of 900-950°C is controlled at the level 400 minutes or less, and the holding time in the range of 950-1000°C is controlled at 100 minutes or more, or,

when the total amount of Nb, V, Mo, Ta and W in the chemical composition of the slab is not 0.0030-0.030%,

at the heating stage, PH ₂ O/PH ₂ in the range of 700-800°C is controlled at the level of 0.050-1.0, PH ₂ O/PH ₂ in the range of 900-950°C is controlled at the level of 0.010-0.10, PH ₂ O /PH ₂ in the range of 950-1000°C is controlled at the level of 0.005-0.070, PH ₂ O/PH ₂ in the range of 1000-1050°C is controlled at the level of 0.0010-0.030, the exposure time in the range of 850-950°C is controlled at level of 120-600 minutes, the holding time in the range of 900-950°C is controlled at 350 minutes or less, and the holding time in the range of 950-1000°C is controlled at 200 minutes or more.

[0128] The above ratio PH ₂ O/PH ₂ is called the degree of oxidation and is the ratio of the vapor partial pressure PH ₂ O to the hydrogen partial pressure PH ₂ in the gaseous atmosphere.

[0129] The "switch" according to this embodiment is mainly controlled by the easy orientation change (switch) inducing factor per se and the periodic orientation change (switch) inducing factor within one secondarily recrystallized grain.

[0130] In order to easily cause the switching itself, it is effective to start the secondary recrystallization from a lower temperature. For example, by controlling the size of the primary recrystallized grain or by using an Nb group element, it is possible to control the onset of secondary recrystallization at a lower temperature.

[0131] In order to periodically cause switching within one secondarily recrystallized grain, it is effective to cause the secondarily recrystallized grain to grow continuously from a lower temperature to a higher temperature. For example, by using AlN and the like, which are conventional inhibitors at a suitable temperature and in a suitable atmosphere, it is possible to make a second-recrystallized grain nucleate at a lower temperature, make the inhibitor's ability to be maintained continuously to a higher temperature, and periodically cause switching up to a higher temperature. temperature inside one secondarily recrystallized grain.

[0132] In other words, in order to favorably induce switching, it is effective to suppress the nucleation of secondary recrystallized grain at a higher temperature, and to cause secondary recrystallized grain nucleated at a lower temperature to preferably grow up to a higher temperature.

[0133] For the switching control that is a feature of this embodiment, the above factors are important. As for the production conditions other than those described above, a conventional known method for producing an anisotropic electrical steel sheet can be applied. For example, the conventional known method may be a production method using MnS and AlN as an inhibitor, which are formed by high-temperature heating of a slab, a production method using AlN, which is formed by low-temperature heating of a slab, and subsequent nitriding, as an inhibitor, and the like. For the switching that is a feature of this embodiment, any manufacturing method can be applied. This embodiment is not limited to any particular production method. Next, the switching control method by the nitriding production method is explained as an example.

(casting process)

[0134] In the casting process, a slab is obtained. For example, a method for obtaining a slab is as follows. Molten steel is obtained (steel is smelted). The slab is made from this molten steel. The slab can be obtained by continuous casting. An ingot can be made using molten steel, and then a slab can be produced by blooming the ingot. The thickness of the slab is not specifically limited. The thickness of the slab may be, for example, 150-350 mm. The thickness of the slab is preferably 220 to 280 mm. A slab with a thickness of 10-70 mm can be used, which is a so-called thin slab. When using a thin slab, it is possible to omit the rough rolling before the final rolling in the hot rolling process.

[0135] As the chemical composition of the slab, the chemical composition of the slab used for the production of the conventional anisotropic electrical steel sheet can be used. For example, the chemical composition of a slab may include the following elements.

0-0.0850%C

[0136] Carbon (C) is an element effective for controlling the primary recrystallization pattern in the manufacturing process. However, when the C content in the final product is excessive, the magnetic performance is adversely affected. Thus, the content of C in the slab can be 0-0.0850%. The upper limit of the C content is preferably 0.0750%. The steel is decarburized and refined at C in the decarburization annealing process and the final annealing process to be described below, and then the C content becomes 0.0050% or less after the final annealing process. When C is included, the lower limit of the C content may be more than 0% and may be 0.0010% in terms of industrial production capacity.

2.0-7.0% Si

[0137] Silicon (Si) is an element that increases the electrical resistance of the anisotropic electrical steel sheet and thereby reduces the magnetic loss. When the Si content is less than 2.0%, austenite transformation occurs during final annealing and the crystallographic orientation of the anisotropic electrical steel sheet deteriorates. On the other hand, when the Si content is more than 7.0%, cold workability deteriorates and cracks may be generated during cold rolling. The lower limit of the Si content is preferably 2.50%, and more preferably 3.0%. The upper limit of the Si content is preferably 4.50%, and more preferably 4.0%.

0-1.0%Mn

[0138] Manganese (Mn) when bound to S and/or Se forms MnS and/or MnSe, which act as an inhibitor. The Mn content may be 0-1.0%. When Mn is included and the Mn content is 0.05-1.0%, secondary recrystallization becomes stable, which is preferable. In this embodiment, the Nb group element nitride may perform part of the function of the inhibitor. In this case, the intensity of the MnS and/or MnSe inhibitor is generally poorly controlled. Thus, the upper limit of the Mn content is preferably 0.50%, and more preferably 0.20%.

0-0.0350% S

0-0.0350% Se

[0139] Sulfur (S) and selenium (Se) when bound to Mn form MnS and/or MnSe, which act as an inhibitor. The S content may be 0-0.0350% and the Se content may be 0-0.0350%. When at least one of S and Se is included, and when the total amount of S and Se is 0.0030-0.0350%, the secondary recrystallization becomes stable, which is preferable. In this embodiment, the Nb group element nitride may perform part of the function of the inhibitor. In this case, the intensity of the MnS and/or MnSe inhibitor is generally poorly controlled. Thus, the upper limit of the total amount of S and Se is preferably 0.0250%, and more preferably 0.010%. When S and/or Se remain in the steel after the final annealing, a bond is formed and thus the magnetic loss deteriorates. Thus, it is preferable to reduce the content of S and Se as much as possible by cleaning during the final annealing.

[0140] Here, the phrase "the total amount of S and Se is 0.0030-0.0350%" means that only one of S or Se is included in the chemical composition of the slab, and their total amount is 0.0030-0.0350% , or that both of S and Se are included in the chemical composition of the slab, and their total amount is 0.00300-0.0350%.

0-0.0650% Al

[0141] Aluminum (Al) when bound to N forms (Al,Si)N, which acts as an inhibitor. The Al content may be 0-0.0650%. When Al is included and the Al content is 0.010-0.0650%, the AlN inhibitor generated in the nitriding described below widens the secondary recrystallization temperature range, and the secondary recrystallization becomes stable, especially in the higher temperature range, which is preferable. The lower limit of the Al content is preferably 0.020%, and more preferably 0.0250%. The upper limit of the Al content is preferably 0.040%, and more preferably 0.030% from the viewpoint of secondary recrystallization stability.

0-0.0120% N

[0142] Nitrogen (N) binds to Al and acts as an inhibitor. The N content may be 0-0.0120%. Its lower limit can be 0% because it is possible to incorporate N through nitriding in the middle part of the production process. When N is included in the composition and the N content is more than 0.0120%, bubbles, which are a kind of defects, may form in the steel sheet. The upper limit of the N content is preferably 0.010%, and more preferably 0.0090%. The steel is refined by N in the final annealing process, and then the N content becomes 0.0050% or less after the final annealing process.

0-0.030%Nb

0-0.030% V

0-0.030% Mo

0-0.030% Ta

0-0.030%W

[0143] Nb, V, Mo, Ta and W are elements of the Nb group. Nb content can be 0 to 0.030%, V content can be 0 to 0.030%, Mo content can be 0 to 0.030%, Ta content can be 0 to 0.030%, and W content can be 0 to 0.030% .

[0144] In addition, it is preferable that the slab includes, as an element of the Nb group, at least one element selected from the group consisting of Nb, V, Mo, Ta and W, and that their amount is 0.0030-0.030 wt.%.

[0145] When using the Nb group element for switching control, and when the total amount of the Nb group element in the slab is 0.030% or less (preferably 0.0030% or more and 0.030% or less), secondary recrystallization starts at an appropriate time. In addition, the orientation of the resulting secondary recrystallized grain becomes very favorable, the switching that is a feature of this embodiment tends to occur in the subsequent growth stage, and as a result, the microstructure is adjusted to be favorable for the magnetization characteristics.

[0146] By including the Nb group element, the primary recrystallized grain size after the decarburization annealing becomes fine compared to the absence of the Nb group element. It appears that the refinement of the primary recrystallized grain occurs as a result of the bonding effect of precipitates such as carbides, carbonitrides and nitrides, the curing action of solid dissolved elements, and the like. In particular, the above effect is preferably obtained by including Nb and Ta.

[0147] By refining the size of the primary recrystallized grain due to the Nb group element, the driving force of the secondary recrystallization is increased, and then the secondary recrystallization starts from a lower temperature compared to conventional methods. In addition, since precipitates produced from the Nb group element dissolve at a relatively lower temperature compared to conventional inhibitors such as AlN, secondary recrystallization starts at a lower temperature in the final annealing heating step than conventional methods. Secondary recrystallization starts at a lower temperature and thereby ensures the occurrence of the switch that is a feature of this embodiment. The mechanism for this is described below.

[0148] In the case where the precipitate obtained from the Nb group element is used as an inhibitor for secondary recrystallization, since the carbides and carbonitrides of the Nb group element become unstable in a lower temperature range than the temperature range in which secondary recrystallization can occur , it seems that the effect of controlling the initial temperature of secondary recrystallization in order to lower it is small. Thus, in order to favorably control the initial temperature of secondary recrystallization to lower it, it is preferable that Nb group element nitrides (or high nitrogen carbonitrides) which are stable up to a temperature range in which secondary recrystallization can occur are used.

[0149] While using Nb-group element-derived precipitates (preferably nitrides) that control the initial temperature of secondary recrystallization to lower it, and conventional inhibitors such as AlN, (Al,Si)N, etc., which are stable up to a higher temperature even after the start of the secondary recrystallization, it is possible to expand the temperature range in which the grain having the {110}<001> orientation, which is the secondary recrystallization grain, is preferably grown. Thus, switching is induced over a wide temperature range from a lower temperature to a higher temperature, which means that orientation selectivity operates over a wide temperature range. As a result, it becomes possible to increase the occurrence frequency of the subboundary in the final product, and thus effectively increase the degree of alignment along the {110}<001> orientation of the secondarily recrystallized grains constituting the anisotropic electrical steel sheet.

[0150] Here, in the case where the primary recrystallized grain is subject to grinding due to the bonding effect of carbides, carbonitrides, and the like. an Nb group element, it is preferable to control the C content in the slab so that it is ⁵⁰ ppm or more when cast. However, since nitrides are preferable as an inhibitor for secondary recrystallization over carbides and carbonitrides, it is preferable that the carbides and carbonitrides of the Nb group element are sufficiently dissolved in the steel after primary recrystallization is completed by reducing the C content by decarburization annealing to 30 ^ppm or less. , preferably 20 ^ppm or less, n more preferably 10 ^ppm or less. In the case where most of the Nb group element is put into solid solution in the decarburization annealing, it is possible to control the Nb group element nitrides (inhibitors) so that they are morphologically favorable for this embodiment (have a morphology that facilitates secondary recrystallization) in subsequent nitriding.

[0151] The total amount of the Nb group element is preferably 0.0040% or more, and more preferably 0.0050% or more. The total amount of the Nb group element is preferably 0.020% or less, and more preferably 0.010% or less.

[0152] In the chemical composition of the slab, the rest consists of Fe and impurities. The aforementioned impurities correspond to elements coming from the raw materials or from the production environment during the industrial production of the slab. In addition, the aforementioned impurities mean elements that do not significantly affect the effects of this embodiment.

[0153] In addition to solving production problems, considering the effect on magnetic characteristics and improving the function of inhibitors by forming compounds, the slab may include known optional elements as a replacement for the Fe part. For example, the optional elements could be the following elements.

0-0.40% Cu

0-0.010% Bi

0-0.080% B

0-0.50% P

0-0.0150% Ti

0-0.10% Sn

0-0.10%Sb

0-0.30%Cr

0-1.0% Ni

[0154] Optional elements may be included as needed. Thus, the lower limit of the content of the corresponding optional elements should not be limited, and this lower limit may be 0%.

(Hot rolling process)

[0155] In the hot rolling process, the slab is heated to a predetermined temperature (for example, 1100-1400°C), and then subjected to hot rolling to obtain a hot-rolled steel sheet. In the hot rolling process, for example, the silicon steel material (slab) after the casting process is heated, subjected to rough rolling, and then finish rolling to obtain a hot-rolled steel sheet with a predetermined thickness, for example, 1.8 to 3.5 mm. After completion of the final rolling, the hot-rolled steel sheet is coiled at a predetermined temperature.

[0156] Since the intensity of an inhibitor such as MnS is not necessarily required, from the viewpoint of productivity, it is preferable that the heating temperature of the slab is 1100-1280°C.

(Hot strip annealing process)

[0157] In the hot strip annealing process, the hot rolled steel sheet after the hot rolling process is annealed under predetermined conditions (for example, 750-1200° C. for 30 seconds to 10 minutes) to obtain a hot strip annealed sheet.

[0158] Meanwhile, in the case of a high-temperature slab heating process, the morphology of precipitates such as AlN is finally controlled in the hot-rolled strip annealing process. Thus, during the annealing process of the hot-rolled strip, precipitates are uniformly and finely dispersed, and thus the primary recrystallized grain size becomes fine during subsequent processing. In addition, in addition to controlling the inhibitor morphology during the annealing process of the hot-rolled strip, it is effective to combine the above-mentioned control during the hot rolling process, the steel sheet surface control before final annealing, the atmosphere control during final annealing, and the like.

(cold rolling process)

[0159] In the cold rolling process, the hot strip annealed sheet after the hot strip annealing process is cold rolled one or more times (two times or more) with annealing (intermediate annealing) (for example, 80-95% of the full reduction in cold rolling) to obtain a cold rolled steel sheet with a thickness of, for example, 0.10 to 0.50 mm.

(Decarburization Annealing Process)

[0160] In the decarburization annealing process, the cold-rolled steel sheet after the cold rolling process is subjected to decarburization annealing (for example, at 700-900°C for 1-3 minutes) to obtain a decarburization-annealed steel sheet that is primary recrystallized. By carrying out the decarburization annealing of the cold-rolled steel sheet, carbon C contained in the cold-rolled steel sheet is removed. In order to remove the "C" contained in the cold rolled steel sheet, it is preferable that the decarburization annealing be carried out in a humid atmosphere.

[0161] In the method for producing the anisotropic electrical steel sheet according to this embodiment, it is preferable to control the primary recrystallized grain size in the decarburized annealed steel sheet to be 23 µm or less. By refining the size of the primary recrystallized grain, it is possible to favorably control the initial temperature of the secondary recrystallization in order to lower it.

[0162] For example, by controlling the hot rolling or annealing conditions of the hot rolled strip, or by adjusting the decarburization annealing temperature to be lower as necessary, the primary recrystallized grain size can be reduced. In addition, due to the bonding effect of carbides, carbonitrides and the like. element of the Nb group, which is included in the composition of the slab, it is possible to reduce the size of the primary recrystallized grain.

[0163] Meanwhile, since the degree of oxidation caused by the decarburization annealing and the state of the surface oxidized layer affect the formation of the intermediate layer (glass film), the conditions can be appropriately adjusted using a conventional method to obtain the effects of this embodiment.

[0164] Although the element of the Nb group may be included in the composition as those elements that promote switching, the element of the Nb group is included in this process in such a state as carbides, carbonitrides, solid dissolved elements, etc., and affects the size refinement primarily recrystallized grain. The primary recrystallized grain size is preferably 21 µm or less, more preferably 20 µm or less, and even more preferably 18 µm or less. The primary recrystallized grain size may be 8 µm or more, and may be 12 µm or more.

(Nitriding)

[0165] Nitriding is carried out in order to control the intensity of the inhibitor for secondary recrystallization. In nitriding, the nitrogen content of the steel sheet can be increased to 40-300 ^ppm at a suitable time from the start of the decarburization annealing to the start of the secondary recrystallization in the final annealing. For example, nitriding can be annealing a steel sheet in an atmosphere containing a gas having nitriding power such as ammonia, finishing annealing a decarburization-annealed steel sheet with an annealing separator containing a powder having nitriding power such as MnN, etc. P.

[0166] When the slab includes an Nb group element in the above range, the Nb group element nitrides formed during nitriding act as an inhibitor whose ability to inhibit grain growth disappears at a relatively lower temperature, which means that secondary recrystallization starts from a lower temperature by compared to conventional methods. It appears that nitrides are effective in selecting the nucleation of a secondarily recrystallized grain, and thereby achieve a high magnetic induction. In addition, nitriding produces AlN, which acts as an inhibitor whose ability to inhibit grain growth is retained up to relatively higher temperatures. In order to obtain these effects, the nitrogen content after nitriding is preferably 130-250 ^ppm , and more preferably 150-200 ^ppm .

(The process of applying the annealing separator)

[0167] In the process of applying the annealing separator, the steel sheet subjected to the decarburization annealing is coated with the annealing separator. For example, as the annealing separator, an annealing separator mainly containing MgO, an annealing separator mainly containing alumina, and the like can be used.

[0168] Meanwhile, when an annealing separator mainly containing MgO is used, a forsterite film (layer mainly containing Mg ₂ SiO ₄ ) tends to form as an intermediate layer during final annealing. When an annealing separator mainly containing alumina is used, an oxide layer (a layer mainly containing SiO ₂ ) tends to form during the final annealing as an intermediate layer. These intermediate layers can be removed if necessary.

[0169] The steel sheet subjected to the decarburization annealing after application of the annealing separator is coiled and finally annealed in a subsequent final annealing process.

(final annealing process)

[0170] In the final annealing process, the steel sheet subjected to the decarburization annealing after application of the annealing separator is finally annealed so that secondary recrystallization occurs. In this process, the secondary recrystallization proceeds under such conditions that the growth of the primary recrystallized grain is inhibited by the inhibitor. Thereby, grains having the {110}<001> orientation are preferentially grown, and the magnetic induction is dramatically improved.

[0171] The final anneal is important for switching control, which is a feature of this embodiment. In this embodiment, the deflection angle α, the deflection angle β, or the deflection angle γ is controlled based on the following seven conditions (A) to (G) in the final annealing.

[0172] Here, when explaining the final annealing process, "the total amount of the Nb group element" is the total amount of the Nb group element contained in the steel sheet immediately before the final annealing (in the decarburized annealed steel sheet). In particular, the chemical composition of the steel sheet immediately before the final annealing affects the final annealing conditions, and the chemical composition after the final annealing or after the refining annealing (for example, the chemical composition of the anisotropic electrical steel sheet (finally annealed sheet)) is not relevant.

[0173] (A) In the heating step of the final annealing, when PA is defined as PH ₂ O/PH ₂ with respect to the atmosphere in the temperature range of 700-800°C,

PA: 0.050 to 1.000.

(B) In the heating step of the final annealing, when PB is defined as PH ₂ O/PH ₂ in relation to the atmosphere in the temperature range of 900-950°C,

PB: 0.010 to 0.100.

(C) In the heating step of the final annealing, when PC is defined as PH ₂ O/PH ₂ in relation to the atmosphere in the temperature range of 950-1000°C,

PC: 0.005 to 0.070.

(D) In the heating step of the final annealing, when PD is defined as PH ₂ O/PH ₂ in relation to the atmosphere in the temperature range of 1000-1050°C,

PD: 0.0010 to 0.030.

(E) In the heating stage of the final annealing, when TE is defined as the holding time in the temperature range of 850-950°C,

TE: 120 to 600 minutes.

(F) In the heating stage of the final annealing, when TF is defined as the holding time in the temperature range of 900-950°C,

TF: 400 minutes or less when the total amount of the Nb group element is within 0.003-0.030%, and

TF: 350 minutes or less when the total number of group element Nb is outside the above range.

(G) In the heating stage of the final annealing, when TG is defined as the holding time (total holding time) in the temperature range of 950-1000°C,

TG: 100 minutes or more when the total Nb group element is within 0.003-0.030%, and

TG: 200 minutes or more when the total amount of group element Nb is outside the above range.

[0174] Meanwhile, when the total amount of the Nb group element is within 0.003-0.030%, condition (A) can be satisfied, at least one of conditions (B) and (D) can be satisfied, and conditions (E) can be satisfied , (F) and (G).

[0175] When the total number of the group element Nb is outside the above range, all of these seven conditions (A)-(G) can be satisfied.

[0176] As for the conditions (B) and (D), when the Nb group element is contained within the above range, due to the return and recrystallization suppression effect that is caused by the Nb group element, the two factors are "starting secondary recrystallization from a lower temperature" and "maintaining secondary recrystallization to a higher temperature" are powerful enough. As a result, the control conditions for obtaining the effects of this embodiment are softened.

[0177] PA is preferably 0.10 or more, and more preferably 0.30 or more. PA is preferably 1.0 or less, and more preferably 0.60 or less.

PB is preferably 0.040 or more, and preferably 0.070 or less.

PC is preferably 0.020 or more, and preferably 0.050 or less.

The PD is preferably 0.005 or more, and preferably 0.020 or less.

The TE is preferably 180 minutes or more, and more preferably 240 minutes or more, and preferably 480 minutes or less, and more preferably 360 minutes or less.

[0178] When the total amount of the Nb group element is in the range of 0.003-0.030%, TF is preferably 350 minutes or less, and more preferably 300 minutes or less. When the total amount of the Nb group element is outside the above range, TF is preferably 300 minutes or less, and more preferably 240 minutes or less.

[0179] When the total amount of the Nb group element is in the range of 0.003-0.030%, TG is preferably 200 minutes or more, and more preferably 300 minutes or more, and preferably 900 minutes or less, and more preferably 600 minutes or less . When the total amount of the Nb group element is outside the above range, TG is preferably 360 minutes or more, and more preferably 600 minutes or more, and preferably 1500 minutes or less, and more preferably 900 minutes or less.

[0180] The details of the switching occurrence mechanism are currently unclear. However, as a result of observing the behavior of the secondary recrystallization and considering the operating conditions for favorable switching control, it seems that two factors are important: "starting the secondary recrystallization at a lower temperature" and "maintaining the secondary recrystallization to a higher temperature".

[0181] The reasons for the above conditions (A)-(G) are explained based on these two factors. In the following description, the mechanism includes some assumption.

[0182] Condition (A) is a condition for a temperature range that is well below the temperature at which secondary recrystallization occurs. Condition (A) does not directly affect the phenomena recognized as secondary recrystallization. However, the above temperature range corresponds to the temperature at which the surface of the steel sheet is oxidized by water which is introduced from the annealing separator deposited on the surface of the steel sheet. In other words, the above temperature range affects the formation of the primary layer (intermediate layer). Condition (A) is important to control the formation of the primary layer and thus to enable the subsequent "maintenance of the secondary recrystallization to a higher temperature". By controlling the atmosphere in the aforementioned temperature range in accordance with the above condition, the primary layer becomes dense, and therefore acts as a barrier to prevent the release of inhibitor constituent elements (for example, Al, N, etc.) from the system at the stage where secondary recrystallization. Thereby, it becomes possible to maintain the secondary recrystallization to a higher temperature and sufficiently cause the switching.

[0183] Condition (B) is a condition for a temperature range that corresponds to a recrystallization nucleation step in secondary recrystallization. By controlling the atmosphere in the aforementioned temperature range according to the above condition, the secondarily recrystallized grain grows at a rate-limited dissolution of the inhibitor in the grain growth step. It appears that condition (B) promotes the dissolution of the inhibitor near the surface of the steel sheet in particular and affects the increase in secondary recrystallization nuclei. For example, it is known that primary recrystallized grains having a preferred crystallographic orientation for secondary recrystallization are sufficiently present near the surface of the steel sheet. In this embodiment, by reducing the intensity of the inhibitor only near the surface of the steel sheet in the temperature range of 900-950°C, the subsequent secondary recrystallization appears to start earlier (at a lower temperature) during the heating step. In addition, in the above case, since the secondary recrystallized grains are sufficiently formed, it appears that the switching frequency increases in the initial growth stage of the secondary recrystallized grains.

[0184] Conditions (C) and (D) are conditions for a temperature range in which secondary recrystallization starts and grain grows. Conditions (C) and (D) affect the control of the intensity of the inhibitor at the stage of growth of the secondarily recrystallized grain. By controlling the atmosphere in the above temperature range to meet the above conditions, the secondarily recrystallized grain grows at a rate-limited dissolution of the inhibitor in each temperature range. Although the details of this are described later, due to these conditions, dislocations are effectively accumulated in front of the grain boundary, which is located in the direction of growth of the secondarily recrystallized grain. Thereby, it becomes possible to increase the switching occurrence frequency and maintain the switching occurrence. As explained above, the temperature range is divided into two ranges, namely, according to conditions (C) and (D) for controlling the atmosphere, because the suitable atmosphere differs depending on the temperature range.

[0185] In the production method according to this embodiment, when an Nb group element is used, it is possible to obtain an anisotropic electrical steel sheet satisfying the switching conditions according to this embodiment since at least one of conditions (B) to (D ). In other words, by controlling with increasing the switching frequency in the initial stage of secondary recrystallization, the secondary recrystallized grain is grown while maintaining the disorientation caused by switching, this effect is maintained until the final stage, and as a result, the switching frequency is increased. Alternatively, even when switching does not occur sufficiently in the initial secondary recrystallization stage, it is possible to eventually increase the switching frequency, causing a sufficient amount of dislocations to accumulate in the grain growth direction in the secondary recrystallization growth stage, and thereby again causing switching. It is not necessary to explain that it is preferable that all conditions (B) to (D) be satisfied even when an Nb group element is used. In other words, it is optimal to increase the switching frequency in the initial stage of secondary recrystallization and again cause switching even in the middle and final stages of secondary recrystallization.

[0186] Condition (E) is a condition for a temperature range that corresponds to the nucleation stage and the grain growth stage of secondary recrystallization. Exposure in this temperature range is important for the favorable course of secondary recrystallization. However, when such holding time is excessive, the primary recrystallized grain tends to grow. For example, when the size of the primary recrystallized grain becomes excessively large, dislocations do not tend to accumulate (dislocations almost do not accumulate in front of the grain boundary, which is located in the growth direction of the secondary recrystallized grain), and hence the driving force causing switching becomes insufficient. When the holding time in the above temperature range is controlled to 600 minutes or less, it is possible to grow the secondary recrystallized grain at the initial stage under such conditions that the growth of the primary recrystallized grain is suppressed. Thus, it is possible to increase the selectivity of a particular deflection angle. In this embodiment, the secondary recrystallization start temperature is made lower by grinding the primary recrystallized grain or using an Nb group element, and thus switching is caused and maintained sufficiently.

[0187] The condition (F) is a condition for a temperature range that corresponds to the nucleation stage and the grain growth stage of secondary recrystallization, and is a condition that contributes to switching over the deflection angle α. Holding within this temperature range influences the occurrence and continuation of the switching. When the holding time is long, the primary recrystallized grain tends to grow. It is possible to reduce the switching over the deflection angle α by adjusting the holding time in a suitable range.

[0188] The condition (G) is a factor controlling the direction of elongation of the sub-boundary (in particular, the sub-boundary γ) in the plane of the steel sheet where the switching occurs. With sufficient exposure in the range of 950-1000°C, it is possible to increase the switching frequency in the transverse direction. It appears that the morphology (eg location and shape) of the precipitates, including the inhibitor in the steel, changes during exposure to the above temperature range. When the holding time is adjusted in a suitable range, switching over the sub-boundary (in particular, sub-boundary γ) in the lateral direction can be increased.

[0189] Because the finish annealed steel sheet has already been hot and cold rolled, the location and shape of the precipitates (particularly MnS) in the steel are anisotropic in the plane of the steel sheet and may tend to be uneven in the rolling direction. The details are not clear, but it appears that holding in the above temperature range changes the rolling direction unevenness of the morphology of the above precipitates and influences the direction in which the subboundary tends to elongate in the plane of the steel sheet during the growth of the secondarily recrystallized grain. More specifically, when the steel sheet is held at a relatively lower temperature such as 950-1000° C., uneven precipitation morphology in the steel develops in the rolling direction. Thereby, the tendency for the elongation of the sub-boundary in the transverse direction is reduced, and the tendency for the elongation of the sub-boundary in the rolling direction is increased. As a result, it appears that the frequency of detecting a sub-boundary (in particular, a γ sub-boundary) in the transverse direction increases.

[0190] Meanwhile, when the total amount of the Nb group element is 0.003-0.030%, the occurrence frequency of the subboundary is itself high, which means that the effects of this embodiment can be obtained even when the holding time TG is insufficient.

(Insulation coating forming process)

[0191] In the insulating coating forming process, an insulating coating is formed on the anisotropic electrical steel sheet after the final annealing process. On the steel sheet after final annealing, an insulating coating which mainly includes phosphate and colloidal silica, an insulating coating which mainly includes alumina sol and boric acid, and the like can be formed.

[0192] For example, a coating solution (comprising phosphoric acid or phosphate, chromic anhydride or chromate, and colloidal silica) is applied to the steel sheet after final annealing and calcined (for example, at 350-1150°C for 5-300 seconds) to form an insulating coatings.

[0193] Alternatively, a coating solution including an alumina sol and boric acid is applied to the steel sheet after final annealing and calcined (eg, at 750-1350°C for 10-100 seconds) to form an insulating coating.

[0194] The manufacturing method according to this embodiment may further include, as necessary, a magnetic domain grinding process.

(Magnetic domain grinding process)

[0195] In the magnetic domain pulverization process, the magnetic domain of the anisotropic electrical steel sheet is pulverized. For example, local small deformations may be applied, or local grooves may be formed in a known manner, such as laser, plasma, mechanical methods, etching, and the like. on a sheet of anisotropic electrical steel. The aforementioned magnetic domain grinding treatment does not impair the effects of this embodiment.

[0196] In this case, the above-mentioned local small deformations and local grooves become a point of inhomogeneity when measuring the crystallographic orientation and grain size determined in this embodiment. Thus, when the crystallographic orientation is measured, it is preferable that the measurement points do not overlap with local small strains and local grooves. In addition, when the grain size is calculated, local small deformations and local grooves are not recognized as a boundary.

(Switch appearance mechanism)

[0197] The switching described in this embodiment occurs during the growth of the secondarily recrystallized grain. This phenomenon is influenced by various control conditions, such as the chemical composition of the material (slab), the production of inhibitor before the growth of the secondary recrystallized grain, and the control of the size of the primary recrystallized grain. Thus, in order to control the switching, it is necessary to control not only one condition, but also a plurality of conditions, comprehensively and inseparably.

[0198] Switching appears to be due to boundary energy and surface energy between adjacent grains.

[0199] With regard to the aforementioned boundary energy, when two misorientation grains are adjacent, the boundary energy increases. Thus, it appears that during the growth of a secondarily recrystallized grain, the switching occurs in such a way as to reduce the boundary energy, in particular, to be close to the same particular direction.

[0200] In addition, with regard to the above-mentioned surface energy, even when the orientation deviates slightly from the {110} plane, which has a high crystal symmetry, the surface energy increases. Thus, it seems that during the growth of the secondarily recrystallized grain, the switching occurs in such a way as to reduce the surface energy, in particular, to reduce the deflection angle by approaching the {110} plane orientation.

[0201] However, in a normal situation, these energies do not provide a driving force that causes changes in orientation, and therefore, when the secondary recrystallized grain grows, no switching occurs. In a normal situation, a secondarily recrystallized grain grows with the same misorientation or deflection angle. For example, in the case where the secondary recrystallized grain grows in the normal situation, the switching is not caused, and the deflection angle corresponds to the angle obtained due to the orientation unevenness at the origin of the secondary recrystallized grain. In other words, the deflection angle almost does not change at the stage of growth of the secondarily recrystallized grain.

[0202] On the other hand, in the anisotropic electrical steel sheet according to this embodiment, in the case where the secondary recrystallization is forced to start from a lower temperature and when the growth of the secondary recrystallized grain is forced to be maintained at a higher temperature for a long time, switching sufficiently induced. The reason for this is not entirely clear, but appears to be due to relatively high density dislocations that remain in the region of the growing recrystallized grain tip, i.e., in the region adjacent to the primary recrystallized grain, to eliminate geometric misorientation during the growth of the sec- ondary recrystallized grain. . The aforementioned residual dislocations appear to correspond to the switching and subboundary that are features of this embodiment.

[0203] Because in this embodiment, the secondary recrystallization starts at a lower temperature compared to conventional methods, dislocation annihilation is delayed, dislocations collect and accumulate in front of the grain boundary, which is located in the growth direction of the secondary recrystallized grain, and then the dislocation density increases. Thus, the atoms tend to rearrange in the region of the top of the growing recrystallized grain, and as a result, it appears that the switching occurs in such a way as to reduce the misorientation with the adjacent recrystallized grain, i.e., to reduce the interfacial energy or surface energy.

[0204] Switching leaves behind a subboundary having a specific orientation relationship in the grain. Meanwhile, in the case where another SR grain is nucleated and the growing SR grain reaches the nucleated SR grain before the switch occurs, grain growth stops and thereafter the switch itself does not occur. Thus, in this embodiment, it is advantageous to control the frequency of new recrystallized grain nucleation to decrease in the recrystallized grain growth step, and it is advantageous to control grain growth to a state where only the already existing recrystallized grain continues to grow. In this embodiment, it is preferable to simultaneously use an inhibitor that lowers the secondary recrystallization start temperature and an inhibitor that is stable to a relatively higher temperature.

Examples

[0205] Next, the effects of an aspect of the present invention are described in detail with reference to the following examples. However, the conditions in the examples are exemplary conditions used to confirm the operation and effects of the present invention, so the present invention is not limited to these exemplary conditions. The present invention may use various types of conditions, as long as these conditions do not depart from the scope of protection of the present invention and allow the object of the present invention to be achieved.

(Example 1)

[0206] Using slabs with the chemical composition shown in Table 1A as materials, anisotropic electrical steel sheets (silicon steel sheets) with the chemical composition shown in Table 2A were produced. These chemical compositions were measured using the above methods. In Table 1A and Table 2A, "-" means that this element was not used, the control of this element was not performed, which means that its content was not measured. In addition, in Table 1A and Table 2A, values with a “<” sign mean that although the control of this element was performed and its content was measured, the measured value was not obtained with sufficient reliability (the measurement result was below the detection limit).

[0207] [Table 1A]

Steel type The chemical composition of the slab (steel billet) (wt.%, the rest is Fe and impurities) C Si Mn S Al N Cu Bi Nb V Mo Ta W A1 0.070 3.26 0.07 0.025 0.026 0.008 0.07 - - - - - - A2 0.070 3.26 0.07 0.025 0.026 0.008 0.07 - 0.007 - - - - B1 0.070 3.26 0.07 0.025 0.025 0.008 0.07 0.002 - - - - - B2 0.070 3.26 0.07 0.025 0.025 0.008 0.07 0.002 0.007 - - - - C1 0.060 3.35 0.10 0.006 0.026 0.008 0.02 - - - - - - C2 0.060 3.35 0.10 0.006 0.026 0.008 0.02 - 0.001 - - - - C3 0.060 3.35 0.10 0.006 0.026 0.008 0.02 - 0.003 - - - - C4 0.060 3.35 0.10 0.006 0.026 0.008 0.02 - 0.005 - - - - C5 0.060 3.35 0.10 0.006 0.026 0.008 0.02 - 0.010 - - - - C6 0.060 3.35 0.10 0.006 0.026 0.008 0.02 - 0.020 - - - - C7 0.060 3.35 0.10 0.006 0.026 0.008 0.02 - 0.030 - - - - C8 0.060 3.35 0.10 0.006 0.026 0.008 0.02 - 0.050 - - - - D1 0.060 3.45 0.10 0.006 0.028 0.008 0.20 - 0.002 - - - - D2 0.060 3.45 0.10 0.006 0.028 0.008 0.20 - 0.007 - - - - E 0.060 3.45 0.10 0.006 0.027 0.008 0.20 - - 0.007 - - - F 0.060 3.45 0.10 0.006 0.027 0.008 0.20 - - - 0.020 - - G 0.060 3.45 0.10 0.006 0.027 0.008 0.20 - 0.005 - - 0.003 - H 0.060 3.45 0.10 0.006 0.027 0.008 0.20 - - - - 0.010 - I 0.060 3.45 0.10 0.006 0.027 0.008 0.20 - - - - - 0.010 J 0.060 3.45 0.10 0.006 0.027 0.008 0.20 - 0.004 0.003 0.010 - - K 0.060 3.45 0.10 0.006 0.027 0.008 0.20 - 0.005 0.003 - 0.003 -

[0208] [Table 2A]

Steel type Chemical composition of anisotropic electrical steel sheet (wt.%, the rest is Fe and impurities) C Si Mn S Al N Cu Bi Nb V Mo Ta W A1 0.001 3.15 0.07 <0.002 <0.004 <0.002 0.07 - - - - - - A2 0.001 3.15 0.07 <0.002 <0.004 <0.002 0.07 - 0.005 - - - - B1 0.001 3.15 0.07 <0.002 <0.004 <0.002 0.07 <0.001 - - - - - B2 0.001 3.15 0.07 <0.002 <0.004 <0.002 0.07 <0.001 0.005 - - - - C1 0.001 3.30 0.10 <0.002 <0.004 <0.002 0.02 - - - - - - C2 0.001 3.30 0.10 <0.002 <0.004 <0.002 0.02 - 0.001 - - - - C3 0.001 3.30 0.10 <0.002 <0.004 <0.002 0.02 - 0.003 - - - - C4 0.001 3.30 0.10 <0.002 <0.004 <0.002 0.02 - 0.003 - - - - C5 0.001 3.30 0.10 <0.002 <0.004 <0.002 0.02 - 0.007 - - - - C6 0.002 3.30 0.10 <0.002 <0.004 <0.002 0.02 - 0.018 - - - - C7 0.004 3.30 0.10 <0.002 <0.004 <0.002 0.02 - 0.028 - - - - C8 0.006 3.30 0.10 <0.002 <0.004 <0.002 0.02 - 0.048 - - - - D1 0.001 3.34 0.10 <0.002 <0.004 <0.002 0.20 - 0.002 - - - - D2 0.001 3.34 0.10 <0.002 <0.004 <0.002 0.20 - 0.006 - - - - E 0.001 3.30 0.10 <0.002 <0.004 <0.002 0.20 - - 0.006 - - - F 0.001 3.34 0.10 <0.002 <0.004 <0.002 0.20 - - - 0.020 - - G 0.001 3.34 0.10 <0.002 <0.004 <0.002 0.20 - 0.004 - - 0.001 - H 0.001 3.34 0.10 <0.002 <0.004 <0.002 0.20 - - - - 0.010 - I 0.001 3.34 0.10 <0.002 <0.004 <0.002 0.20 - - - - - 0.010 J 0.001 3.34 0.10 <0.002 <0.004 <0.002 0.20 - 0.003 0.001 0.003 - - K 0.001 3.34 0.10 <0.002 <0.004 <0.002 0.20 - 0.003 0.001 - 0.002 -

[0209] Anisotropic electrical steel sheets were produced under the production conditions shown in Tables 3A-12A. Specifically, after casting the slabs, hot rolling, hot strip annealing, cold rolling, and decarburization annealing were carried out. For some steel sheets, after decarburization annealing, nitriding was carried out in a mixed atmosphere of hydrogen, nitrogen, and ammonia.

[0210] An annealing separator that mainly included MgO was applied to the steel sheets, and then a final annealing was performed. In the final final annealing step, the steel sheets were held at 1200° C. for 20 hours in a hydrogen atmosphere (refining annealing) and then cooled.

[0211] [Table 3A]

No. Steel type Production conditions hot rolling Hot strip annealing cold rolling Decarburizing annealing Heating temperature
°C End rolling temperature
°C Roll temperature
°C Sheet thickness
mm Temperature
°C Time
seconds Sheet thickness
mm Cold rolling reduction % Primary recrystallized grain size
micron Nitrogen content after nitriding
^ppm 1 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 220 2 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 250 3 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 300 4 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 160 5 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 220 6 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 220 7 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 220 8 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 220 9 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 220 10 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 160 eleven C1 1150 900 540 2.8 1100 180 0.26 90.7 22 220 12 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 220 13 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 220 14 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 220 15 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 220 16 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 220 17 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 220 18 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 220 19 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 220 20 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 220

[0212] [Table 4A]

No. Steel type Production conditions hot rolling Hot strip annealing cold rolling Decarburizing annealing Heating temperature
°C End rolling temperature
°C Roll temperature
°C Sheet thickness
mm Temperature
°C Time
seconds Sheet thickness
mm Reduction in cold rolling
% Primary recrystallized grain size
micron Nitrogen content after nitriding
^ppm 21 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 220 22 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 300 23 C1 1150 900 540 2.8 1100 180 0.26 90.7 22 300 24 D1 1150 900 540 2.8 1100 180 0.26 90.7 23 220 25 D1 1150 900 540 2.8 1100 180 0.26 90.7 23 220 26 D1 1150 900 540 2.8 1100 180 0.26 90.7 23 220 27 D1 1150 900 540 2.8 1100 180 0.26 90.7 23 220 28 D1 1150 900 540 2.8 1100 180 0.26 90.7 23 220 29 D1 1150 900 540 2.8 1100 180 0.26 90.7 23 220 thirty D1 1150 900 540 2.8 1100 180 0.26 90.7 23 220 31 D1 1150 900 540 2.8 1100 180 0.26 90.7 23 220 32 D1 1150 900 540 2.8 1100 180 0.26 90.7 23 220 33 D1 1150 900 540 2.8 1100 180 0.26 90.7 23 220 34 D1 1150 900 540 2.8 1100 180 0.26 90.7 23 220 35 D2 1150 900 540 2.8 1100 180 0.26 90.7 17 220 36 D2 1150 900 540 2.8 1100 180 0.26 90.7 17 220 37 D2 1150 900 540 2.8 1100 180 0.26 90.7 17 220 38 D2 1150 900 540 2.8 1100 180 0.26 90.7 17 220 39 D2 1150 900 540 2.8 1100 180 0.26 90.7 17 220 40 D2 1150 900 540 2.8 1100 180 0.26 90.7 17 220

[0213] [Table 5A]

No. Steel type Production conditions hot rolling Hot strip annealing cold rolling Decarburizing annealing Heating temperature
°C End rolling temperature
°C Roll temperature
°C Sheet thickness
mm Temperature
°C Time
seconds Sheet thickness
mm Reduction in cold rolling
% Primary recrystallized grain size
micron Nitrogen content after nitriding
^ppm 41 D2 1150 900 540 2.8 1100 180 0.26 90.7 17 190 42 D2 1150 900 540 2.8 1100 180 0.26 90.7 17 160 43 D2 1150 900 540 2.8 1100 180 0.26 90.7 17 220 44 D2 1150 900 540 2.8 1100 180 0.26 90.7 17 220 45 D2 1150 900 540 2.8 1100 180 0.26 90.7 17 180 46 D2 1150 900 540 2.8 1100 180 0.26 90.7 17 180 47 D2 1150 900 540 2.8 1100 180 0.26 90.7 17 210 48 C1 1150 900 540 2.8 1100 180 0.26 90.7 23 210 49 C2 1150 900 540 2.8 1100 180 0.26 90.7 24 210 50 C3 1150 900 540 2.8 1100 180 0.26 90.7 20 210 51 C4 1150 900 540 2.8 1100 180 0.26 90.7 17 210 52 C5 1150 900 540 2.8 1100 180 0.26 90.7 16 210 53 C6 1150 900 540 2.8 1100 180 0.26 90.7 15 210 54 C7 1150 900 540 2.8 1100 180 0.26 90.7 13 210 55 C8 1150 900 540 2.8 1100 180 0.26 90.7 12 210 56 D1 1150 900 540 2.8 1100 180 0.26 90.7 24 220 57 D2 1150 900 540 2.8 1100 180 0.26 90.7 17 220 58 E 1150 900 540 2.8 1100 180 0.26 90.7 22 220 59 F 1150 900 540 2.8 1100 180 0.26 90.7 19 220 60 G 1150 900 540 2.8 1100 180 0.26 90.7 15 220

[0214] [Table 6A]

No. Steel type Production conditions hot rolling Hot strip annealing cold rolling Decarburizing annealing Heating temperature
°C End rolling temperature
°C Roll temperature
°C Sheet thickness
mm Temperature
°C Time
seconds Sheet thickness
mm Reduction in cold rolling
% Primary recrystallized grain size
micron Nitrogen content after nitriding
^ppm 61 H 1150 900 540 2.8 1100 180 0.26 90.7 15 220 62 I 1150 900 540 2.8 1100 180 0.26 90.7 23 220 63 J 1150 900 540 2.8 1100 180 0.26 90.7 17 220 64 K 1150 900 540 2.8 1100 180 0.26 90.7 15 220 65 A1 1400 1100 540 2.6 1100 180 0.26 90.0 9 - 66 A1 1400 1100 540 2.6 1100 180 0.26 90.0 9 - 67 A1 1400 1100 540 2.6 1100 180 0.26 90.0 9 - 68 A1 1400 1100 540 2.6 1100 180 0.26 90.0 9 - 69 A1 1400 1100 540 2.6 1100 180 0.26 90.0 9 - 70 A1 1400 1100 540 2.6 1100 180 0.26 90.0 9 - 71 A1 1400 1100 540 2.6 1100 180 0.26 90.0 9 - 72 A1 1400 1100 540 2.6 1100 180 0.26 90.0 9 - 73 A1 1400 1100 540 2.6 1100 180 0.26 90.0 9 - 74 A2 1400 1100 540 2.6 1100 180 0.26 90.0 7 - 75 A2 1400 1100 540 2.6 1100 180 0.26 90.0 7 - 76 A2 1400 1100 540 2.6 1100 180 0.26 90.0 7 - 77 A2 1400 1100 540 2.6 1100 180 0.26 90.0 7 - 78 A2 1400 1100 540 2.6 1100 180 0.26 90.0 7 - 79 A2 1400 1100 540 2.6 1100 180 0.26 90.0 7 - 80 A2 1400 1100 540 2.6 1100 180 0.26 90.0 7 -

[0215] [Table 7A]

No. Steel type Production conditions hot rolling Hot strip annealing cold rolling Decarburizing annealing Heating temperature
°C End rolling temperature
°C Roll temperature
°C Sheet thickness
mm Temperature
°C Time
seconds Sheet thickness
mm Reduction in cold rolling
% Primary recrystallized grain size
micron Nitrogen content after nitriding
^ppm 81 A2 1400 1100 540 2.6 1100 180 0.26 90.0 7 - 82 A2 1400 1100 540 2.6 1100 180 0.26 90.0 7 - 83 B1 1350 1100 540 2.6 1100 180 0.26 90.0 10 - 84 B1 1350 1100 540 2.6 1100 180 0.26 90.0 10 - 85 B1 1350 1100 540 2.6 1100 180 0.26 90.0 10 - 86 B1 1350 1100 540 2.6 1100 180 0.26 90.0 10 - 87 B1 1350 1100 540 2.6 1100 180 0.26 90.0 10 - 88 B1 1350 1100 540 2.6 1100 180 0.26 90.0 10 - 89 B1 1350 1100 540 2.6 1100 180 0.26 90.0 10 - 90 B1 1350 1100 540 2.6 1100 180 0.26 90.0 10 - 91 B1 1350 1100 540 2.6 1100 180 0.26 90.0 10 - 92 B1 1350 1100 540 2.6 1100 180 0.26 90.0 10 - 93 B2 1350 1100 540 2.6 1100 180 0.26 90.0 8 - 94 B2 1350 1100 540 2.6 1100 180 0.26 90.0 8 - 95 B2 1350 1100 540 2.6 1100 180 0.26 90.0 8 - 96 B2 1350 1100 540 2.6 1100 180 0.26 90.0 8 - 97 B2 1350 1100 540 2.6 1100 180 0.26 90.0 8 - 98 B2 1350 1100 540 2.6 1100 180 0.26 90.0 8 - 99 B2 1350 1100 540 2.6 1100 180 0.26 90.0 8 - 100 B2 1350 1100 540 2.6 1100 180 0.26 90.0 8 -

[0216] [Table 8A]

No. Steel type Production conditions final annealing PA PB PC PD TE
minutes TF
minutes TG
minutes 1 C1 0.020 0.005 0.003 0.0007 150 180 300 2 C1 0.050 0.010 0.003 0.0007 150 180 300 3 C1 0.050 0.010 0.003 0.0007 150 180 300 4 C1 0.050 0.010 0.003 0.0007 150 180 300 5 C1 0.050 0.010 0.003 0.0007 150 180 300 6 C1 0.050 0.005 0.003 0.0007 210 180 300 7 C1 0.020 0.020 0.020 0.010 210 180 90 8 C1 0.100 0.005 0.005 0.0007 150 180 300 9 C1 0.050 0.020 0.005 0.010 210 180 300 10 C1 0.050 0.010 0.050 0.010 210 180 300 eleven C1 0.050 0.005 0.003 0.0007 210 180 300 12 C1 0.050 0.010 0.003 0.0007 150 180 300 13 C1 0.020 0.010 0.003 0.0007 210 180 300 14 C1 0.050 0.010 0.005 0.001 210 180 300 15 C1 0.050 0.010 0.005 0.001 210 180 300 16 C1 0.050 0.010 0.020 0.001 210 180 300 17 C1 0.050 0.010 0.005 0.005 210 180 300 18 C1 0.050 0.010 0.030 0.001 210 180 300 19 C1 0.050 0.010 0.030 0.005 210 180 300 20 C1 0.050 0.010 0.030 0.010 210 180 300

[0217] [Table 9A]

No. Steel type Production conditions final annealing PA PB PC PD TE
minutes TF
minutes TG
minutes 21 C1 0.050 0.010 0.010 0.020 210 180 300 22 C1 0.050 0.010 0.010 0.005 150 360 600 23 C1 0.050 0.010 0.010 0.005 210 180 600 24 D1 0.020 0.010 0.005 0.050 210 180 300 25 D1 0.050 0.010 0.005 0.001 210 180 300 26 D1 0.200 0.010 0.005 0.001 210 180 300 27 D1 0.300 0.010 0.005 0.001 210 180 300 28 D1 0.400 0.010 0.005 0.001 300 180 300 29 D1 0.400 0.010 0.005 0.001 150 180 300 thirty D1 0.400 0.010 0.005 0.001 150 180 300 31 D1 0.600 0.010 0.005 0.001 300 180 300 32 D1 1,000 0.010 0.005 0.001 210 180 300 33 D1 1,000 0.010 0.005 0.001 210 180 300 34 D1 5,000 0.010 0.005 0.001 210 180 300 35 D2 0.020 0.010 0.005 0.001 90 180 300 36 D2 0.030 0.005 0.005 0.001 150 420 300 37 D2 0.050 0.005 0.003 0.001 150 180 300 38 D2 0.300 0.040 0.003 0.001 150 360 300 39 D2 0.300 0.040 0.005 0.001 300 180 300 40 D2 0.300 0.040 0.005 0.001 600 180 300

[0218] [Table 10A]

No. Steel type Production conditions final annealing PA PB PC PD TE
minutes TF
minutes TG
minutes 41 D2 0.300 0.040 0.005 0.001 600 180 300 42 D2 0.300 0.040 0.005 0.001 600 180 300 43 D2 0.300 0.030 0.005 0.001 300 180 300 44 D2 0.200 0.030 0.005 0.001 600 360 300 45 D2 0.400 0.040 0.005 0.001 600 180 300 46 D2 0.500 0.050 0.005 0.001 600 180 300 47 D2 1,000 0.010 0.003 0.0007 150 180 300 48 C1 0.200 0.005 0.005 0.0007 150 180 300 49 C2 0.200 0.005 0.005 0.0007 150 180 300 50 C3 0.200 0.005 0.005 0.0007 150 180 300 51 C4 0.200 0.005 0.005 0.0007 150 180 300 52 C5 0.200 0.005 0.005 0.0007 150 180 300 53 C6 0.200 0.005 0.005 0.0007 150 180 300 54 C7 0.200 0.005 0.005 0.0007 150 180 300 55 C8 0.200 0.005 0.005 0.0007 150 360 300 56 D1 0.050 0.005 0.003 0.003 150 360 300 57 D2 0.050 0.005 0.003 0.003 150 180 300 58 E 0.050 0.005 0.003 0.003 150 360 300 59 F 0.050 0.005 0.003 0.003 150 180 300 60 G 0.050 0.005 0.003 0.003 150 180 300

[0219] [Table 11A]

No. Steel type Production conditions final annealing PA PB PC PD TE
minutes TF
minutes TG
minutes 61 H 0.050 0.005 0.003 0.003 150 180 300 62 I 0.050 0.005 0.003 0.003 150 360 300 63 J 0.050 0.005 0.003 0.003 150 180 300 64 K 0.050 0.005 0.003 0.003 150 180 300 65 A1 0.050 0.010 0.003 0.0007 150 180 300 66 A1 0.050 0.018 0.003 0.0007 150 180 300 67 A1 0.050 0.025 0.003 0.003 150 180 300 68 A1 0.400 0.150 0.003 0.0007 300 180 300 69 A1 0.400 0.018 0.015 0.003 300 180 300 70 A1 0.050 0.018 0.015 0.003 600 180 300 71 A1 0.050 0.025 0.015 0.003 300 180 300 72 A1 0.050 0.025 0.015 0.003 600 180 300 73 A1 0.050 0.025 0.015 0.003 600 180 300 74 A2 0.050 0.010 0.003 0.0007 150 180 300 75 A2 0.050 0.018 0.003 0.0007 150 180 300 76 A2 0.050 0.025 0.015 0.003 150 180 300 77 A2 0.400 0.005 0.003 0.0007 300 180 300 78 A2 0.400 0.018 0.003 0.0007 300 180 300 79 A2 0.050 0.018 0.003 0.0007 600 180 300 80 A2 0.050 0.025 0.015 0.003 300 180 300

[0220] [Table 12A]

No. Steel type Production conditions final annealing PA PB PC PD TE
minutes TF
minutes TG
minutes 81 A2 0.050 0.025 0.015 0.003 600 180 300 82 A2 0.050 0.025 0.015 0.003 600 180 300 83 B1 0.100 0.010 0.010 0.003 300 180 300 84 B1 0.100 0.010 0.010 0.005 600 180 300 85 B1 1,000 0.010 0.010 0.005 300 180 300 86 B1 1,000 0.010 0.010 0.003 300 180 300 87 B1 0.400 0.040 0.040 0.003 600 180 300 88 B1 0.010 0.025 0.015 0.003 900 180 300 89 B1 1,000 0.025 0.015 0.003 90 180 300 90 B1 1,000 0.250 0.150 0.075 900 180 300 91 B1 0.020 0.010 0.003 0.0007 150 180 300 92 B1 1,000 0.010 0.003 0.0007 150 180 1800 93 B2 0.100 0.010 0.010 0.003 300 180 300 94 B2 0.100 0.010 0.010 0.005 600 180 300 95 B2 1,000 0.010 0.010 0.005 300 180 300 96 B2 1,000 0.010 0.010 0.003 300 180 300 97 B2 0.400 0.040 0.040 0.003 600 180 300 98 B2 0.010 0.025 0.015 0.003 900 180 300 99 B2 1,000 0.025 0.015 0.003 90 180 300 100 B2 1,000 0.025 0.150 0.075 900 180 300

[0221] A coating solution for forming an insulating coating, mainly including phosphate and colloidal silica and including chromium, was applied to the primary layer (intermediate layer) formed on the surface of the produced anisotropic electrical steel sheets (finally annealed sheets). The above steel sheets were heated and kept in an atmosphere of 75 vol% hydrogen and 25 vol% nitrogen, cooled, and thereby formed an insulating coating.

[0222] The produced anisotropic electrical steel sheets had an intermediate layer that was placed in contact with the anisotropic electrical steel sheet (silicon steel sheet), and an insulating coating that was located in contact with the intermediate layer when viewed in a section whose cutting plane is parallel to thickness direction. The intermediate layer was a forsterite film with an average thickness of 2 µm, and the insulating coating mainly included phosphate and colloidal silica and had an average thickness of 1 µm.

[0223] Various characteristics of the resulting anisotropic electrical steel sheet were evaluated. The evaluation results are presented in Tables 13A-22A.

(1) Crystallographic orientation of anisotropic electrical steel sheet

[0224] The crystallographic orientation of the anisotropic electrical steel sheet was measured by the above method. The deviation angle was identified by the crystallographic orientation at each measurement point, and the boundary between two adjacent measurement points was identified based on the aforementioned deviation angles. When evaluating the boundary condition using two measurement points with a spacing of 1 mm, and when the value obtained by dividing the "number of boundaries satisfying the boundary condition BAγ" by the "number of boundaries satisfying the boundary condition BB" is 1.05 or more, the steel the sheet is considered to include "a boundary that satisfies the boundary condition BAγ and which does not satisfy the boundary condition BB", and such a steel sheet is shown in the tables as having a "switching boundary". Here, "the number of boundaries satisfying the boundary condition BAγ" corresponds to the boundary of case 1 and/or case 3 in the above Table 1, and "the number of boundaries satisfying the boundary condition BB" corresponds to the boundary of case 1 and/or case 2. The average grain size was calculated based on the above identified boundaries.

(2) Magnetic characteristics of anisotropic electrical steel

[0225] The magnetic characteristics of the anisotropic electrical steel were measured using a single sheet tester (SST) by the method of JIS C 2556:2015.

[0226] As magnetic characteristics, the magnetic loss W _17/50 (W/kg), which is defined as the specific power loss per unit mass (1 kg) of the steel sheet, was measured under the conditions of alternating current with a frequency of 50 Hz and a magnetic field induction of 1, 7 T In addition, the magnetic induction B ₈ (T) in the rolling direction of the steel sheet was measured under the condition that the steel sheet was excited at 800 A/m.

[0227] In addition, as magnetic characteristics, the magnetostriction λp-p generated in the steel sheet at 1.7 T (difference between the minimum and maximum of the magnetostriction at 1.7 T) was measured under conditions of alternating current at a frequency of 50 Hz and a drive magnetic induction of 1 .7 T Specifically, using the maximum length L _max and the minimum length L _min of the test piece (steel sheet) under the above driving condition, and using the length L ₀ of the test piece at a magnetic induction of 0 T, the magnetostriction λp-p at 1.7 T was calculated based on the formula λp −p at 1.7 T = (L _max − L _min )/L ₀ .

[0228] Similarly, the magnetostriction λp-p generated in the steel sheet at 1.9T (difference between the minimum and maximum of the magnetostriction at 1.9T) was measured under conditions of alternating current at a frequency of 50Hz and an excitation magnetic induction of 1.9T.

[0229] From the values of the magnetic characteristics, the magnetostriction rate level at 1.7 T (Lva at 1.7 T) and the magnetostriction rate level at 1.9 T (Lva at 1.9 T) were calculated. The magnetostriction waveform with two or more cycles and the waveform obtained at a sampling frequency of 6.4 kHz were subjected to Fourier transform, the magnetostriction λ at each frequency (fi) (0-3.2 kHz) was obtained, and thereby was calculated the level of magnetostriction velocity Lva (in dB) using the following expression (5).

[0230] Lva = 20 × log ₁₀ [{ ρc × { Ʃ ( 2 ^1/2 π × fi × λ(fi) × α(fi)) ² } ^1/2 } / P ₀ ] ... (expression 4 )

[0231] Here

ρ: Density of air (kg/m ³ )

c: Sound speed (m/s)

P ₀ : Minimum pressure at which a person can hear a sound with a frequency of 1 kHz (Pa)

fi: Frequency (Hz)

λ(fi): Magnetostriction at each frequency, Fourier transformable

α(fi): A-weighting at frequency fi

π: Pi (the ratio of a circle's circumference to its diameter)

[0232] In order to obtain Lva at 1.7 T and Lva at 1.9 T, the following values were substituted.

ρ=1.185 (kg/ ^m3 )

c=346.3 (m/s)

P ₀ \u003d 2 × 10 ^-5 (Pa)

[0233] [Table 13A]

No. Steel type Production results border, size The presence of a switching boundary RAα _C
micron RAβ _C
micron RAγ _C
micron RB _C
micron RAγ _C /RAα _C RAγ _C /RAβ _C RB _C /RAγ _C 1 C1 No 25.0 24.5 24.8 23.6 0.990 1.013 0.951 2 C1 No 30.2 30.0 30.1 28.4 0.995 1.003 0.943 3 C1 No 36.0 35.3 35.5 35.1 0.987 1.007 0.987 4 C1 No 20.9 21.9 21.7 19.7 1.039 0.994 0.905 5 C1 No 26.6 26.6 26.7 24.7 1.004 1.004 0.925 6 C1 No 25.8 25.9 25.9 24.1 1.005 1.001 0.930 7 C1 No 25.7 25.6 25.7 25.3 1.002 1.003 0.984 8 C1 No 28.3 28.6 28.6 27.0 1.008 1,000 0.947 9 C1 There is 22.0 22.3 19.8 21.2 0.902 0.890 1.070 10 C1 There is 18.8 18.4 17.9 19.5 0.948 0.972 1.091 eleven C1 No 26.1 26.6 26.3 24.1 1.008 0.986 0.917 12 C1 No 25.8 26.1 26.2 24.1 1.018 1.006 0.920 13 C1 No 24.8 24.9 25.1 23.3 1.010 1.007 0.931 14 C1 There is 22.3 22.5 20.2 23.9 0.906 0.898 1.182 15 C1 There is 23.1 22.6 21.8 23.7 0.944 0.963 1.090 16 C1 There is 22.4 21.8 20.8 23.6 0.930 0.956 1.133 17 C1 There is 22.3 22.5 20.1 22.7 0.903 0.895 1.125 18 C1 There is 21.9 21.8 20.5 24.1 0.933 0.940 1.177 19 C1 There is 22.2 22.3 20.0 24.1 0.904 0.899 1.204 20 C1 There is 22.2 22.5 21.1 25.3 0.951 0.934 1,200

[0234] [Table 14A]

No. Steel type Production results border, size The presence of a switching boundary RAα _C
micron RAβ _C
micron RAγ _C
micron RB _C
micron RAγ _C /RAα _C RAγ _C /RAβ _C RB _C /RAγ _C 21 C1 There is 21.1 21.8 19.2 24.6 0.907 0.877 1.285 22 C1 No 35.3 35.1 35.2 33.0 0.997 1.003 0.937 23 C1 There is 30.0 30.3 28.4 33.0 0.948 0.936 1.161 24 D1 No 25.8 25.4 26.1 25.1 1.008 1.024 0.964 25 D1 There is 22.4 22.3 21.5 24.4 0.961 0.968 1.134 26 D1 There is 23.4 22.6 22.2 25.6 0.949 0.983 1.151 27 D1 There is 22.8 22.7 20.7 25.6 0.905 0.911 1.239 28 D1 There is 21.6 20.7 19.6 26.0 0.906 0.947 1.326 29 D1 There is 20.3 20.9 19.2 25.3 0.943 0.920 1.321 thirty D1 There is 20.9 21.4 20.3 25.7 0.973 0.950 1.268 31 D1 There is 20.6 21.1 19.3 24.8 0.939 0.918 1.285 32 D1 There is 20.9 21.1 19.5 22.7 0.930 0.923 1.164 33 D1 There is 19.2 19.0 17.4 22.2 0.907 0.919 1.272 34 D1 No 18.8 18.0 18.6 17.7 0.990 1.030 0.950 35 D2 No 21.0 21.2 21.3 20.9 1.017 1.008 0.982 36 D2 There is 16.7 17.5 17.4 25.2 1.047 0.995 1.443 37 D2 There is 17.5 17.0 15.7 25.2 0.896 0.921 1.612 38 D2 There is 17.2 17.6 15.5 25.0 0.905 0.882 1.609 39 D2 There is 14.7 14.9 13.0 26.1 0.886 0.876 2.009 40 D2 There is 13.1 13.8 12.0 24.5 0.916 0.871 2.038

[0235] [Table 15A]

No. Steel type Production results border, size The presence of a switching boundary RAα _C
micron RAβ _C
micron RAγ _C
micron RB _C
micron RAγ _C /RAα _C RAγ _C /RAβ _C RB _C /RAγ _C 41 D2 There is 13.7 13.1 12.1 25.3 0.884 0.928 2.086 42 D2 There is 13.7 13.9 12.2 24.7 0.893 0.882 2.019 43 D2 There is 14.3 14.3 12.9 25.5 0.904 0.903 1.969 44 D2 There is 14.9 15.6 13.8 25.7 0.923 0.885 1.864 45 D2 There is 14.0 14.3 13.4 26.6 0.958 0.933 1.988 46 D2 There is 13.9 13.9 12.9 27.1 0.926 0.926 2.107 47 D2 There is 17.2 17.1 14.7 25.3 0.860 0.860 1.713 48 C1 No 16.3 16.7 16.5 14.8 1.013 0.987 0.898 49 C2 No 17.0 17.9 17.7 16.3 1.043 0.988 0.920 50 C3 There is 19.6 19.2 18.3 24.3 0.933 0.955 1.329 51 C4 There is 17.9 17.6 15.3 25.1 0.858 0.871 1.641 52 C5 There is 17.4 17.3 15.6 25.0 0.895 0.901 1.601 53 C6 There is 18.0 17.8 16.4 26.1 0.914 0.923 1.588 54 C7 There is 19.5 19.3 18.4 25.1 0.947 0.955 1.362 55 C8 No 17.0 16.1 16.9 14.4 0.994 1.048 0.853 56 D1 No 16.9 17.1 17.0 15.6 1.008 0.996 0.915 57 D2 There is 16.8 16.7 15.8 23.7 0.941 0.948 1.494 58 E There is 18.9 18.7 18.2 23.9 0.967 0.973 1.313 59 F There is 16.9 17.1 15.2 24.2 0.898 0.890 1.596 60 G There is 16.5 16.9 15.2 22.9 0.917 0.898 1.511

[0236] [Table 16A]

No. Steel type Production results border, size The presence of a switching boundary RAα _C
micron RAβ _C
micron RAγ _C
micron RB _C
micron RAγ _C /RAα _C RAγ _C /RAβ _C RB _C /RAγ _C 61 H There is 17.9 17.5 17.0 25.2 0.946 0.972 1.486 62 I There is 19.7 19.0 17.4 23.5 0.885 0.916 1.351 63 J There is 16.9 17.0 14.9 25.4 0.884 0.877 1.698 64 K There is 17.5 17.0 15.8 24.1 0.903 0.932 1.521 65 A1 No 15.0 15.7 15.1 13.5 1.005 0.958 0.897 66 A1 No 15.6 15.9 15.7 13.6 1.005 0.986 0.867 67 A1 No 15.5 15.8 15.8 14.5 1.019 0.995 0.922 68 A1 No 18.6 17.6 18.3 17.7 0.983 1.037 0.969 69 A1 There is 31.5 31.3 29.0 32.5 0.923 0.926 1.119 70 A1 There is 28.1 28.2 26.2 32.6 0.933 0.930 1.245 71 A1 There is 29.7 30.0 28.8 36.3 0.970 0.960 1.260 72 A1 There is 31.4 31.7 30.9 39.9 0.986 0.975 1.288 73 A1 There is 31.1 31.8 30.0 40.8 0.965 0.944 1.358 74 A2 There is 18.2 17.4 15.6 25.4 0.860 0.896 1.629 75 A2 There is 16.9 17.2 15.5 24.9 0.916 0.897 1.610 76 A2 There is 17.2 17.2 16.4 25.3 0.955 0.956 1.541 77 A2 There is 17.9 17.2 17.4 25.0 0.974 1.015 1.432 78 A2 There is 16.1 15.8 15.0 26.6 0.932 0.948 1.776 79 A2 There is 16.5 16.4 14.1 26.0 0.853 0.856 1.847 80 A2 There is 15.5 15.0 13.9 24.2 0.897 0.928 1.743

[0237] [Table 17A]

No. Steel type Production results border, size The presence of a switching boundary RAα _C
micron RAβ _C
micron RAγ _C
micron RB _C
micron RAγ _C /RAα _C RAγ _C /RAβ _C RB _C /RAγ _C 81 A2 There is 15.5 14.9 14.5 24.1 0.939 0.977 1.661 82 A2 There is 15.0 15.7 13.2 25.0 0.883 0.841 1.894 83 B1 There is 32.0 32.2 30.3 41.4 0.949 0.940 1.366 84 B1 There is 37.4 37.3 36.3 55.2 0.972 0.973 1.520 85 B1 There is 35.3 34.7 33.0 47.9 0.933 0.950 1.452 86 B1 There is 32.1 32.7 31.8 40.8 0.990 0.971 1.284 87 B1 There is 41.1 40.5 39.6 64.5 0.964 0.977 1.631 88 B1 No 22.3 22.1 22.8 22.4 1.020 1.031 0.982 89 B1 No 20.5 20.8 20.7 21.0 1.006 0.993 1.016 90 B1 No 22.1 21.9 22.4 23.1 1.011 1.021 1.031 91 B1 No 16.1 15.8 16.0 13.4 0.991 1.010 0.834 92 B1 No 21.8 21.7 22.3 22.9 1.023 1.029 1.025 93 B2 There is 15.1 15.1 14.4 24.3 0.949 0.951 1.694 94 B2 There is 15.1 14.9 12.3 26.3 0.815 0.829 2.133 95 B2 There is 14.8 15.2 14.1 26.4 0.953 0.927 1.869 96 B2 There is 15.3 15.4 13.2 24.6 0.863 0.856 1.863 97 B2 There is 14.4 13.5 12.7 26.3 0.879 0.937 2.077 98 B2 There is 16.6 17.1 16.9 26.0 1.017 0.989 1.589 99 B2 There is 16.7 16.4 16.6 24.1 0.997 1.015 1,450 100 B2 There is 16.2 16.4 16.6 25.2 1.026 1.013 1.517

[0238] [Table 18A]

No. Steel type Assessment results Note Magnetic characteristics _B8
Tl Lva at 1.7 T
dB Lva at 1.9 T
dB W _17/50
W/kg 1 C1 1.912 52.870 63.970 0.890 Comparative Example 2 C1 1.921 52.919 62.479 0.868 Comparative Example 3 C1 1.927 52,400 60,950 0.852 Comparative Example 4 C1 1.902 53.964 60.469 0.902 Comparative Example 5 C1 1.912 52.942 60.308 0.880 Comparative Example 6 C1 1.916 53.189 60.551 0.882 Comparative Example 7 C1 1.927 53.420 64.241 0.871 Comparative Example 8 C1 1.922 52.907 61.163 0.875 Comparative Example 9 C1 1.918 48.868 54.818 0.873 Example according to the invention 10 C1 1.911 48.630 54.467 0.895 Example according to the invention eleven C1 1.918 53.631 61.684 0.883 Comparative Example 12 C1 1.918 52.849 63.338 0.883 Comparative Example 13 C1 1.914 53.548 61.568 0.880 Comparative Example 14 C1 1.919 48.885 55.675 0.874 Example according to the invention 15 C1 1.920 48.819 55.599 0.874 Example according to the invention 16 C1 1.920 49.048 57.515 0.875 Example according to the invention 17 C1 1.917 48.876 54.352 0.875 Example according to the invention 18 C1 1.925 48.741 53.831 0.867 Example according to the invention 19 C1 1.917 48.413 57.205 0.875 Example according to the invention 20 C1 1.922 48.270 56.171 0.867 Example according to the invention

[0239] [Table 19A]

No. Steel type Assessment results Note Magnetic characteristics _B8
Tl Lva at 1.7 T
dB Lva at 1.9 T
dB W _17/50
W/kg 21 C1 1.928 48.193 54.028 0.861 Example according to the invention 22 C1 1.943 52.583 59.529 0.852 Comparative Example 23 C1 1.944 46.996 53.576 0.844 Example according to the invention 24 D1 1.914 53.470 64.058 0.860 Comparative Example 25 D1 1.910 48.562 53.872 0.854 Example according to the invention 26 D1 1.914 48.150 56.385 0.847 Example according to the invention 27 D1 1.919 48.698 55.984 0.842 Example according to the invention 28 D1 1.928 47.924 55,400 0.834 Example according to the invention 29 D1 1.927 47.941 56.279 0.831 Example according to the invention thirty D1 1.924 48.869 56.911 0.835 Example according to the invention 31 D1 1.921 48.176 57.786 0.834 Example according to the invention 32 D1 1.918 48.892 58.483 0.847 Example according to the invention 33 D1 1.915 48.728 56.249 0.853 Example according to the invention 34 D1 1.912 53.423 61.554 0.861 Comparative Example 35 D2 1.935 53.003 61.923 0.848 Comparative Example 36 D2 1.945 51.660 59.842 0.835 Comparative Example 37 D2 1.944 47.048 54.294 0.835 Example according to the invention 38 D2 1.953 46.394 53.917 0.811 Example according to the invention 39 D2 1.961 46.040 54.456 0.794 Example according to the invention 40 D2 1.968 46.187 53.786 0.790 Example according to the invention

[0240] [Table 20A]

No. Steel type Assessment results Note Magnetic characteristics _B8
Tl Lva at 1.7 T
dB Lva at 1.9 T
dB W _17/50
W/kg 41 D2 1.959 47.011 53.675 0.800 Example according to the invention 42 D2 1.956 46.797 52.171 0.811 Example according to the invention 43 D2 1.955 46.427 55.097 0.802 Example according to the invention 44 D2 1.964 46.097 56.365 0.802 Example according to the invention 45 D2 1,960 46.833 57.021 0.800 Example according to the invention 46 D2 1.959 46.413 53.808 0.800 Example according to the invention 47 D2 1.948 46.503 54.223 0.819 Example according to the invention 48 C1 1.913 52.885 59.619 0.875 Comparative Example 49 C2 1.924 52.803 60.862 0.877 Comparative Example 50 C3 1.928 47.983 53.845 0.839 Example according to the invention 51 C4 1.941 47.349 54.234 0.813 Example according to the invention 52 C5 1,950 47.405 52.646 0.816 Example according to the invention 53 C6 1.942 47.462 56.775 0.815 Example according to the invention 54 C7 1.931 48.124 54.268 0.850 Example according to the invention 55 C8 1.929 52.838 60.776 0.886 Comparative Example 56 D1 1.916 52.964 60.335 0.885 Comparative Example 57 D2 1.948 47.013 52.403 0.834 Example according to the invention 58 E 1.928 48.307 54.254 0.854 Example according to the invention 59 F 1.945 47.510 57.034 0.835 Example according to the invention 60 G 1.947 46.751 56.297 0.833 Example according to the invention

[0241] [Table 21A]

No. Steel type Assessment results Note Magnetic characteristics _B8
Tl Lva at 1.7 T
dB Lva at 1.9 T
dB W _17/50
W/kg 61 H 1.948 46.710 54.552 0.833 Example according to the invention 62 I 1.924 48.770 54.005 0.854 Example according to the invention 63 J 1.945 46.908 56.559 0.836 Example according to the invention 64 K 1.945 47.569 53.944 0.835 Example according to the invention 65 A1 1.921 52.637 59.403 0.878 Comparative Example 66 A1 1.928 52.330 63.049 0.878 Comparative Example 67 A1 1.931 52.821 60.743 0.871 Comparative Example 68 A1 1.939 52.458 61.984 0.862 Comparative Example 69 A1 1.937 48.072 57.806 0.852 Example according to the invention 70 A1 1,940 47.397 54.210 0.858 Example according to the invention 71 A1 1.942 48.020 56.311 0.857 Example according to the invention 72 A1 1.939 47.601 56.890 0.851 Example according to the invention 73 A1 1.938 47.728 56.701 0.850 Example according to the invention 74 A2 1.951 47.195 55.297 0.827 Example according to the invention 75 A2 1,950 46.548 53,880 0.828 Example according to the invention 76 A2 1.952 47.292 54,200 0.820 Example according to the invention 77 A2 1.961 51.605 59.163 0.811 Comparative Example 78 A2 1.963 46.364 54.974 0.802 Example according to the invention 79 A2 1.957 46.796 55.994 0.811 Example according to the invention 80 A2 1.959 46.569 54.162 0.808 Example according to the invention

[0242] [Table 22A]

No. Steel type Assessment results Note Magnetic characteristics _B8
Tl Lva at 1.7 T
dB Lva at 1.9 T
dB W _17/50
W/kg 81 A2 1.965 46.055 53.396 0.803 Example according to the invention 82 A2 1.962 46.075 52.727 0.802 Example according to the invention 83 B1 1.944 47.156 53.019 0.849 Example according to the invention 84 B1 1.949 47.578 54,530 0.836 Example according to the invention 85 B1 1.947 47.601 54.158 0.845 Example according to the invention 86 B1 1.941 48.017 56.157 0.848 Example according to the invention 87 B1 1.948 47.374 55.448 0.831 Example according to the invention 88 B1 1.936 52.104 60.526 0.859 Comparative Example 89 B1 1.927 52.688 59.264 0.863 Comparative Example 90 B1 1.937 52.323 63.436 0.859 Comparative Example 91 B1 1.928 52.444 62.242 0.882 Comparative Example 92 B1 1.921 53.014 62.980 0.880 Comparative Example 93 B2 1.959 45,800 53.370 0.802 Example according to the invention 94 B2 1.965 46.023 52.537 0.791 Example according to the invention 95 B2 1.967 46.015 55,860 0.797 Example according to the invention 96 B2 1.966 46.643 52.418 0.800 Example according to the invention 97 B2 1.972 45.422 51.674 0.785 Example according to the invention 98 B2 1.955 51.084 58.775 0.810 Comparative Example 99 B2 1.957 50.841 58.201 0.814 Comparative Example 100 B2 1.955 50.533 61.518 0.809 Comparative Example

[0243] The characteristics of the anisotropic electrical steel sheet vary greatly depending on the chemical composition and production method. Thus, it is necessary to compare and analyze the performance evaluation results of steel sheets whose chemical compositions and production methods are suitably classified. In the following, the performance evaluation results are explained by classifying the anisotropic electrical steel sheets according to some characteristics with respect to chemical compositions and production methods.

(Examples produced with low temperature slab heating process)

[0244] Nos. 1 to 64 were examples produced by a process in which the heating temperature of the slab was reduced, nitriding was carried out after primary recrystallization, and thereby a major inhibitor for secondary recrystallization was formed.

(Examples Nos. 1-23)

[0245] Nos. 1-23 were examples in which a steel type without an Nb group element was used, and the conditions PA, PB, PC, PD, TE, TF, and TG were mainly changed during final annealing.

[0246] In Nos. 1-23, when the W _17/50 value was 0.900 W/kg or less, the Lva value at 1.7 T was 50.0 dB or less, the Lva value at 1.9 T was 58.0 dB or less, and the magnetic loss characteristics and the rate of magnetostriction were judged to be acceptable.

[0247] In the examples of the invention among Nos. 1 to 23, the secondary recrystallized grain was divided into small domains by a subboundary, and the ratio between the deflection angle γ and the deflection angle α and the ratio between the deflection angle γ and the deflection angle β were favorably controlled. Thus, these examples showed excellent magnetic loss characteristics and an excellent level of magnetostriction rate. On the other hand, in the Comparative Examples, although the deflection angle slightly and continuously shifted in the secondary recrystallized grain, the secondary recrystallized grain was not divided into small domains by a subboundary, and the deflection angle ratio α/β/γ was not favorably controlled. Thus, these examples did not show excellent magnetic loss performance and excellent magnetostriction rate.

[0248] Wherein, No. 3 was a comparative example in which the inhibitor intensity was increased by adjusting the N content after nitriding to 300 ^ppm . Generally, although increasing the nitrogen content by nitriding leads to a decrease in productivity, it also leads to an increase in inhibitor intensity and thus to an increase in B ₈ . In #3, the value of B ₈ increased. However, in no. 3, the final annealing conditions were not preferable, which means that the level of the magnetostriction rate was insufficient. On the other hand, No. 10 was an example of the invention in which the N content after nitriding was adjusted to 160 ^ppm . In No. 10, although the value of B ₈ was not particularly high, the final annealing conditions were preferred, which means that the magnetostriction rate level became a preferable low value.

[0249] Nos. 22 and 23 were examples in which nitriding was carried out sufficiently and secondary recrystallization was maintained up to a higher temperature by increasing TF. In these examples, the value of B ₈ has increased. However, of these, in No. 22, the TF value was excessively high, which means that the level of the magnetostriction velocity was insufficient. On the other hand, in No. 23, the value of TF was favorably controlled, which means that the level of the magnetostriction velocity acquired a preferable low value.

(Examples Nos. 24-34)

[0250] Nos. 24 to 34 were examples in which a steel type including 0.002% Nb was used as the slab, and the conditions PA and TE were mainly changed during the final annealing.

[0251] In Nos. 24-34, when the W _17/50 value was 0.855 W/kg or less, the Lva value at 1.7 T was 49.0 dB or less, the Lva value at 1.9 T was 59.0 dB or less, and the magnetic loss characteristics and the rate of magnetostriction were judged to be acceptable.

[0252] In the examples of the invention among Nos. 24 to 34, the secondary recrystallized grain was divided into small domains by a subboundary, and the ratio between the deflection angle γ and the deflection angle α and the ratio between the deflection angle γ and the deflection angle β were favorably controlled. Thus, these examples showed excellent magnetic loss characteristics and an excellent level of magnetostriction rate. On the other hand, in the Comparative Examples, although the deflection angle slightly and continuously shifted in the secondary recrystallized grain, the secondary recrystallized grain was not divided into small domains by a subboundary, and the deflection angle ratio α/β/γ was not favorably controlled. Thus, these examples did not show excellent magnetic loss performance and excellent magnetostriction rate.

(Examples Nos. 35-47)

[0253] Nos. 35-47 were examples in which a steel type including 0.007% Nb was used as the slab.

[0254] In Nos. 35-47, when the W _17/50 value was 0.835 W/kg or less, the Lva value at 1.7 T was 48.0 dB or less, the Lva value at 1.9 T was 58.0 dB or less, and the magnetic loss characteristics and the rate of magnetostriction were judged to be acceptable.

[0255] In the examples of the invention among Nos. 35-47, the secondary recrystallized grain was divided into small domains by a subboundary, and the ratio between the deflection angle γ and the deflection angle α and the ratio between the deflection angle γ and the deflection angle β were favorably controlled. Thus, these examples showed excellent magnetic loss characteristics and an excellent level of magnetostriction rate. On the other hand, in the Comparative Examples, although the deflection angle slightly and continuously shifted in the secondary recrystallized grain, the secondary recrystallized grain was not divided into small domains by a subboundary, and the deflection angle ratio α/β/γ was not favorably controlled. Thus, these examples did not show excellent magnetic loss performance and excellent magnetostriction rate.

[0256] Meanwhile, Nos. 35-47 contained a preferable amount of Nb in the slab compared to the above-mentioned Nos. 1-34, which means that the magnetostriction rate level acquired a preferable low value. In addition, the value of B ₈ has increased. As described above, by using the Nb-containing slab and controlling the final annealing conditions, the magnetic characteristics and the magnetostriction characteristics were favorably affected.

(Examples Nos. 48-55)

[0257] Nos. 48-55 were examples in which the TE value was controlled at less than 200 minutes, and the influence of the Nb content was particularly pronounced.

[0258] In Nos. 48-55, when the W _17/50 value was 0.850 W/kg or less, the Lva value at 1.7 T was 49.0 dB or less, the Lva value at 1.9 T was 57.0 dB or less, and the magnetic loss characteristics and the rate of magnetostriction were judged to be acceptable.

[0259] In the examples of the invention among Nos. 48-55, the secondary recrystallized grain was divided into small domains by a subboundary, and the ratio between the deflection angle γ and the deflection angle α and the ratio between the deflection angle γ and the deflection angle β were favorably controlled. Thus, these examples showed excellent magnetic loss characteristics and an excellent level of magnetostriction rate. On the other hand, in the Comparative Examples, although the deflection angle slightly and continuously shifted in the secondary recrystallized grain, the secondary recrystallized grain was not divided into small domains by a subboundary, and the deflection angle ratio α/β/γ was not favorably controlled. Thus, these examples did not show excellent magnetic loss performance and excellent magnetostriction rate.

[0260] As shown in Nos. 48-55, provided that the slab contained 0.0030-0.030 wt.% Nb, switching favorably occurred at the time of final annealing, which means that the magnetostriction rate level improved even when the TE time was short.

(Examples Nos. 56-64)

[0261] Nos. 56-64 were examples in which the TE value was controlled at less than 200 minutes, and the influence of the amount of the Nb group element was confirmed.

[0262] In Nos. 56-64, when the W _17/50 value was 0.86 W/kg or less, the Lva value at 1.7 T was 49.0 dB or less, the Lva value at 1.9 T was 58 .0 dB or less, and the magnetic loss characteristics and magnetostriction rate level were judged to be acceptable.

[0263] In the examples of the invention among Nos. 56-64, the secondary recrystallized grain was divided into small domains by a subboundary, and the ratio between the deflection angle γ and the deflection angle α and the ratio between the deflection angle γ and the deflection angle β were favorably controlled. Thus, these examples showed excellent magnetic loss characteristics and an excellent level of magnetostriction rate. On the other hand, in the Comparative Examples, although the deflection angle slightly and continuously shifted in the secondary recrystallized grain, the secondary recrystallized grain was not divided into small domains by a subboundary, and the deflection angle ratio α/β/γ was not favorably controlled. Thus, these examples did not show excellent magnetic loss performance and excellent magnetostriction rate.

[0264] As shown in Nos. 56-64, provided that the slab contained a predetermined amount of an Nb group element excluding Nb, switching favorably occurred at the time of final annealing, which means that the level of magnetostriction rate improved even when the TE time was short. .

(Examples produced with high temperature slab heating process)

[0265] Nos. 65-100 were examples produced by a process in which the heating temperature of the slab was increased, MnS was sufficiently dissolved during the heating of the slab and re-precipitated during the subsequent process, and the re-precipitated MnS was used as the main inhibitor.

[0266] Nos. 83-100 in the above-mentioned Nos. 65-100 were examples in which Bi was included in the slab, which means that the value of B ₈ increased.

[0267] In Nos. 65-82, when the W _17/50 value was 0.860 W/kg or less, the Lva value at 1.7 T was 49.0 dB or less, the Lva value at 1.9 T was 58.0 dB or less, and the magnetic loss characteristics and the rate of magnetostriction were judged to be acceptable.

[0268] In Nos. 83-100, when the W _17/50 value was 0.850 W/kg or less, the Lva value at 1.7 T was 49.0 dB or less, the Lva value at 1.9 T was 56.5 dB or less, and the magnetic loss characteristics and the rate of magnetostriction were judged to be acceptable.

[0269] In the examples of the invention among Nos. 65-100, the secondary recrystallized grain was divided into small domains by a subboundary, and the ratio between the deflection angle γ and the deflection angle α and the ratio between the deflection angle γ and the deflection angle β were favorably controlled. Thus, these examples showed excellent magnetic loss characteristics and an excellent level of magnetostriction rate. On the other hand, in the Comparative Examples, although the deflection angle slightly and continuously shifted in the secondary recrystallized grain, the secondary recrystallized grain was not divided into small domains by a subboundary, and the deflection angle ratio α/β/γ was not favorably controlled. Thus, these examples did not show excellent magnetic loss performance and excellent magnetostriction rate.

[0270] As shown in Nos. 65-100, while the final annealing conditions were suitably controlled, the switching favorably occurred at the time of final annealing, which means that the level of the magnetostriction rate improved even in the process of high-temperature heating of the slab. In addition, as with the low-temperature slab heating process, by using the Nb-containing slab and controlling the final annealing conditions, magnetic characteristics and magnetostriction characteristics were favorably affected.

(Example 2)

[0271] Using the No. 97 and No. 98 anisotropic electrical steel sheets shown in the above Example 1, the magnetic domain refinement effect was investigated. In particular, local small deformations were applied or local grooves were formed by any method, such as laser, plasma, mechanical methods, etching, and the like, on No. 97 and No. 98 anisotropic electrical steel sheets.

[0272] The results of the assessment are presented in Tables 1B and 2B. It can be seen from these tables that in no way did the characteristics of the steel sheet change and the magnetic characteristics did not deteriorate for the anisotropic electrical steel sheet in which the magnetic domain refinement was carried out.

[0273] [Table 1B]

No. Steel type Magnetic domain grinding method Production results The presence of a switching boundary RAα _C
micron RAβ _C
micron RAγ _C
micron RB _C
micron RAγ _C /RAα _C RAγ _C /RAβ _C RB _C /RAγ _C 97 B2 - There is 14.4 13.5 12.7 26.3 0.879 0.937 2.077 98 B2 - There is 16.6 17.1 16.9 26.0 1.017 0.989 1.589 97-2 B2 laser There is 14.4 13.5 12.7 26.3 0.879 0.937 2.077 98-2 B2 laser There is 16.6 17.1 16.9 26.0 1.017 0.989 1.589 97-3 B2 plasma There is 14.4 13.5 12.7 26.3 0.879 0.937 2.077 98-3 B2 plasma There is 16.6 17.1 16.9 26.0 1.017 0.989 1.589 97-4 B2 mechanical deformation There is 14.4 13.5 12.7 26.3 0.879 0.937 2.077 98-4 B2 mechanical deformation There is 16.6 17.1 16.9 26.0 1.017 0.989 1.589 97-5 B2 etching There is 14.4 13.5 12.7 26.3 0.879 0.937 2.077 98-5 B2 etching There is 16.6 17.1 16.9 26.0 1.017 0.989 1.589

[0274] [Table 2B]

Steel type Magnetic domain grinding method Assessment results Note No. _B8
Tl Lva at 1.7 T
dB Lva at 1.9 T
dB W _17/50
W/kg 97 B2 - 1.972 45.422 51.674 0.785 Example according to the invention 98 B2 - 1.955 51.084 58.775 0.810 Comparative Example 97-2 B2 Laser 1.969 49.029 56.778 0.695 Example according to the invention 98-2 B2 Laser 1.952 54.431 66.620 0.730 Comparative Example 97-3 B2 Plasma 1.969 49.819 56.780 0.705 Example according to the invention 98-3 B2 Plasma 1.951 54.241 66.483 0.740 Comparative Example 97-4 B2 mechanical deformation 1.944 47.342 54.603 0.735 Example according to the invention 98-4 B2 mechanical deformation 1.927 52.130 64.455 0.760 Comparative Example 97-5 B2 Etching 1.949 46.852 54.705 0.725 Example according to the invention 98-5 B2 Etching 1.932 51.926 63.776 0.750 Comparative Example

[0275] (Example 3)

Using slabs with the chemical composition shown in Tables 1C and 2C as materials, anisotropic electrical steel sheets with the chemical composition shown in Tables 3C and 4C were produced. The methods for measuring the chemical composition and the notation in the tables are the same as in Example 1 above.

[0276] [Table 1C]

Steel type The chemical composition of the slab (steel billet) (wt.%, the rest is Fe and impurities) C Si Mn S Al N Cu Bi Nb V Mo X1 0.080 3.26 0.07 0.018 0.026 0.008 0.07 - - - - X2 0.080 3.26 0.07 0.006 0.026 0.008 0.07 - - - - X3 0.060 3.35 0.10 0.006 0.026 0.008 0.02 - - - - X4 0.060 3.35 0.10 0.006 0.026 0.008 0.02 - - - - X5 0.060 3.35 0.10 0.006 0.026 0.008 0.02 - - - - X6 0.060 3.35 0.10 0.006 0.026 0.008 0.02 - - - - X7 0.060 3.35 0.10 0.006 0.026 0.008 0.02 - - - - X8 0.060 3.35 0.10 0.006 0.026 0.008 0.02 - - - - X9 0.060 3.45 0.10 0.006 0.028 0.008 0.20 - 0.007 - - X10 0.060 3.35 0.10 0.006 0.026 0.008 0.02 - - - - X11 0.060 3.35 0.10 0.006 0.026 0.008 0.02 - - - - X12 0.070 3.26 0.07 0.025 0.025 0.008 0.07 0.002 - - -

[0277] [Table 2C]

Steel type The chemical composition of the slab (steel billet) (wt.%, the rest is Fe and impurities) Ta W Se B P Ti sn Sb Cr Ni X1 - - 0.018 - - - - - - - X2 - - 0.020 - - - - - - - X3 - - - 0.002 - - - - - - X4 - - - - 0.011 - - - - - X5 - - - - - 0.007 - - - - X6 - - - - - - 0.050 - - - X7 - - - - - - - 0.025 - - X8 - - - - - - - - 0.100 - X9 - - - - 0.021 0.001 0.060 - 0.110 0.020 X10 - - - - - - - - - 0.100 X11 - - - - - - - - - - X12 - - - - - - - - - -

[0278] [Table 3C]

Steel type Chemical composition of anisotropic electrical steel sheet (wt.%, the rest is Fe and impurities) C Si Mn S Al N Cu Bi Nb V Mo X1 0.001 3.15 0.07 <0.002 <0.004 <0.002 0.07 - - - - X2 0.001 3.15 0.07 <0.002 <0.004 <0.002 0.07 - - - - X3 0.001 3.30 0.10 <0.002 <0.004 <0.002 0.02 - - - - X4 0.001 3.30 0.10 <0.002 <0.004 <0.002 0.02 - - - - X5 0.001 3.30 0.10 <0.002 <0.004 <0.002 0.02 - - - - X6 0.001 3.30 0.10 <0.002 <0.004 <0.002 0.02 - - - - X7 0.001 3.30 0.10 <0.002 <0.004 <0.002 0.02 - - - - X8 0.001 3.30 0.10 <0.002 <0.004 <0.002 0.02 - - - - X9 0.001 3.34 0.10 <0.002 <0.004 <0.002 0.20 - 0.006 - - X10 0.001 3.30 0.10 <0.002 <0.004 <0.002 0.02 - - - - X11 0.001 3.30 0.10 <0.002 <0.004 <0.002 0.02 - - - - X12 0.001 3.15 0.07 <0.002 <0.004 <0.002 0.07 <0.001 - - -

[0279] [Table 4C]

Steel type Chemical composition of anisotropic electrical steel sheet (wt.%, the rest is Fe and impurities) Ta W Se B P Ti sn Sb Cr Ni X1 - - <0.002 - - - - - - - X2 - - <0.002 - - - - - - - X3 - - - 0.002 - - - - - - X4 - - - - 0.011 - - - - - X5 - - - - - 0.007 - - - - X6 - - - - - - 0.050 - - - X7 - - - - - - - 0.025 - - X8 - - - - - - - - 0.100 - X9 - - - - 0.020 0.001 0.060 - 0.110 0.020 X10 - - - - - - - - - 0.100 X11 - - - - - - - - - - X12 - - - - - - - - - -

[0280] Anisotropic electrical steel sheets were produced under the production conditions shown in Tables 5C and 6C. Production conditions not shown in the tables were the same as in Example 1 above.

[0281] In these examples, with the exception of No. 1011, an annealing separator that mainly included MgO was applied to the steel sheets, and then a final annealing was performed. On the other hand, in No. 1011, an annealing separator which mainly included alumina was applied to steel sheets, and then final annealing was carried out.

[0282] [Table 5C]

No. Steel type Production conditions hot rolling Hot strip annealing cold rolling Decarburizing annealing Heating temperature
°C End rolling temperature
°C Roll temperature
°C Sheet thickness
mm Temperature
°C Time
seconds Sheet thickness
mm Reduction in cold rolling
% Primary recrystallized grain size
micron Nitrogen content after nitriding
^ppm 1001 X1 1400 1100 540 2.6 1100 180 0.26 90.0 9 - 1002 X2 1400 1100 540 2.6 1100 180 0.26 90.0 9 - 1003 X3 1150 900 540 2.8 1100 180 0.26 90.7 22 160 1004 X4 1150 900 540 2.8 1100 180 0.26 90.7 22 160 1005 X5 1150 900 540 2.8 1100 180 0.26 90.7 22 160 1006 X6 1150 900 540 2.8 1100 180 0.26 90.7 22 160 1007 X7 1150 900 540 2.8 1100 180 0.26 90.7 22 160 1008 X8 1150 900 540 2.8 1100 180 0.26 90.7 22 160 1009 X9 1150 900 540 2.8 1100 180 0.26 90.7 17 220 1010 X10 1150 900 540 2.8 1100 180 0.26 90.7 22 160 1011 X11 1150 900 540 2.8 1100 180 0.26 90.7 22 160 1012 X12 1350 1100 540 2.6 1100 180 0.26 90.0 10 - 1013 X11 1150 900 540 2.8 1060 180 0.26 90.7 24 160 1014 X11 1150 900 540 2.8 1100 180 0.26 90.7 22 160 1015 X11 1150 900 540 2.8 1100 180 0.26 90.7 22 160 1016 X11 1150 900 540 2.8 1100 180 0.26 90.7 22 160 1017 X11 1150 900 540 2.8 1100 180 0.26 90.7 22 160 1018 X11 1150 900 540 2.8 1100 180 0.26 90.7 22 160

[0283] [Table 6C]

No. Steel type Production conditions final annealing PA PB PC PD TE
minutes TF
minutes TG
minutes 1001 X1 0.400 0.018 0.015 0.003 300 180 300 1002 X2 0.400 0.018 0.015 0.003 300 180 300 1003 X3 0.050 0.010 0.050 0.010 210 180 300 1004 X4 0.050 0.010 0.050 0.010 210 180 300 1005 X5 0.050 0.010 0.050 0.010 210 180 300 1006 X6 0.050 0.010 0.050 0.010 210 180 300 1007 X7 0.050 0.010 0.050 0.010 210 180 300 1008 X8 0.050 0.010 0.050 0.010 210 180 300 1009 X9 0.050 0.010 0.050 0.010 210 180 300 1010 X10 0.050 0.010 0.050 0.010 210 180 300 1011 X11 0.050 0.010 0.050 0.010 210 180 300 1012 X12 0.400 0.040 0.040 0.003 450 180 400 1013 X11 0.050 0.010 0.050 0.010 210 180 300 1014 X11 0.040 0.010 0.050 0.010 210 180 300 1015 X11 0.050 0.005 0.050 0.010 210 180 300 1016 X11 0.050 0.010 0.050 0.0007 210 180 300 1017 X11 0.050 0.010 0.050 0.010 210 180 120 1018 X11 *1 0.010 0.050 0.010 210 180 300

In the above table, "*1" means that "PH ₂ O/PH ₂ at 700-750°C was controlled at 0.2, and PH ₂ O/PH ₂ at 750-800°C was controlled at 0.03".

[0284] An insulating coating, which was the same as in the above Example 1, was formed on the surface of the produced anisotropic electrical steel sheets (finally annealed sheets).

[0285] The produced anisotropic electrical steel sheets had an intermediate layer that was placed in contact with the anisotropic electrical steel sheet (silicon steel sheet), and an insulating coating that was located in contact with the intermediate layer when viewed in a section whose cutting plane is parallel to thickness direction.

[0286] In these anisotropic electrical steel sheets, except for No. 1011, the intermediate layer was a forsterite film with an average thickness of 1.5 µm, and the insulating coating mainly included phosphate and colloidal silica and had an average thickness of 2 µm. On the other hand, in the No. 1011 anisotropic electrical steel sheet, the intermediate layer was an oxide layer (which mainly included SiO ₂ ) with an average thickness of 20 nm, and the insulating coating mainly included phosphate and colloidal silica and had an average thickness of 2 μm.

[0287] Various characteristics of the resulting anisotropic electrical steel sheet were evaluated. The evaluation methods were the same as in Example 1 above. The evaluation results are shown in Tables 7C and 8C.

[0288] [Table 7C]

No. Steel type Production results border, size The presence of a switching boundary RAα _C
micron RAβ _C
micron RAγ _C
micron RB _C
micron RAγ _C /RAα _C RAγ _C /RAβ _C RB _C /RAγ _C 1001 X1 There is 32.5 32.1 29.9 33.0 0.921 0.930 1.103 1002 X2 There is 32.1 30.5 29.5 32.5 0.920 0.967 1.101 1003 X3 There is 19.2 18.5 18.0 19.7 0.938 0.973 1.094 1004 X4 There is 18.5 18.4 18.1 19.6 0.978 0.984 1.083 1005 X5 There is 18.9 18.3 17.9 19.7 0.945 0.976 1.103 1006 X6 There is 18.8 18.3 18.0 19.6 0.956 0.984 1.089 1007 X7 There is 18.6 18.1 17.8 19.6 0.957 0.983 1.101 1008 X8 There is 18.7 19.2 18.0 19.5 0.961 0.938 1.081 1009 X9 There is 27.4 17.2 14.8 30.3 0.896 0.921 1.612 1010 X10 There is 18.6 18.2 17.7 19.7 0.954 0.976 1.111 1011 X11 There is 19.0 18.3 17.7 19.6 0.929 0.967 1.107 1012 X12 There is 51.5 48.2 42.6 58.3 0.826 0.882 1.369 1013 X11 No 18.3 18.6 18.5 19.7 1.013 0.994 1.062 1014 X11 No 19.6 20.1 19.8 19.6 1.006 0.982 0.995 1015 X11 No 19.8 19.4 19.5 19.8 0.985 1.006 1.015 1016 X11 No 18.5 18.1 18.3 19.2 0.994 1.013 1.047 1017 X11 No 17.8 18.4 17.9 18.9 1.005 0.974 1.058 1018 X11 No 18.2 17.6 17.8 18.6 0.976 1.007 1.049

[0289] [Table 8C]

No. Steel type Assessment results Note Magnetic characteristics _B8
Tl Lva at 1.7 T
dB Lva at 1.9 T
dB W _17/50
W/kg 1001 X1 1.948 47.521 56.632 0.832 Example according to the invention 1002 X2 1.942 47.733 57.341 0.852 Example according to the invention 1003 X3 1.922 48.574 57.236 0.866 Example according to the invention 1004 X4 1.913 48.532 54.521 0.886 Example according to the invention 1005 X5 1.921 48.650 54.156 0.881 Example according to the invention 1006 X6 1.915 48.432 53,850 0.882 Example according to the invention 1007 X7 1.917 48.877 53.720 0.881 Example according to the invention 1008 X8 1.920 48.125 54.270 0.885 Example according to the invention 1009 X9 1.945 46.823 54.181 0.832 Example according to the invention 1010 X10 1.916 48.524 55.120 0.867 Example according to the invention 1011 X11 1.948 47.054 53.897 0.924 Example according to the invention 1012 X12 1.953 47.813 56.346 0.828 Example according to the invention 1013 X11 1.908 53.597 63.468 0.883 Comparative Example 1014 X11 1.910 53.257 63.821 0.879 Comparative Example 1015 X11 1.909 53.564 62.845 0.881 Comparative Example 1016 X11 1.906 53.865 62.230 0.893 Comparative Example 1017 X11 1.908 53.438 63.245 0.886 Comparative Example 1018 X11 1.905 53.814 63.751 0.892 Comparative Example

[0290] In Nos. 1001-1018, when the W _17/50 value was 0.925 W/kg or less, the Lva value at 1.7 T was 50.0 dB or less, the Lva value at 1.9 T was 58.0 dB or less, and the magnetic loss characteristics and the rate of magnetostriction were judged to be acceptable.

[0291] In the examples of the invention among Nos. 1001-1018, the secondary recrystallized grain was divided into small domains by a subboundary, and the ratio between the deflection angle γ and the deflection angle α and the ratio between the deflection angle γ and the deflection angle β were favorably controlled. Thus, these examples showed excellent magnetic loss characteristics and an excellent level of magnetostriction rate. On the other hand, in the Comparative Examples, although the deflection angle slightly and continuously shifted in the secondary recrystallized grain, the secondary recrystallized grain was not divided into small domains by a subboundary, and the deflection angle ratio α/β/γ was not favorably controlled. Thus, these examples did not show excellent magnetic loss performance and excellent magnetostriction rate.

INDUSTRIAL APPLICABILITY

[0292] In accordance with the above aspects of the present invention, it is possible to provide an anisotropic electrical steel sheet in which the level of magnetostriction velocity (Lva) is in the range of medium to strong magnetic field (especially in a magnetic field excited so that it is approximately 1.7- 1.9 T) is improved in addition to excellent magnetic loss characteristics. Accordingly, the present invention has significant industrial applicability.

LIST OF REFERENCES

[0293] 10 - Anisotropic electrical steel sheet (silicon steel sheet)

20 - Intermediate layer

30 - Insulating coating.

Claims (40)

1. Sheet of anisotropic electrical steel, including in its chemical composition, in wt.%, 2.0-7.0% Si, 0-0.030% Nb, 0-0.030%V, 0-0.030% Mo, 0-0.030% Ta, 0-0.030% W, not more than 0.0050% C, 0-1.0% Mn, 0-0.0150% S, 0-0.0150% Se, 0-0.0650% Al, 0-0.0050% N, 0-0.40% Cu, 0-0.010% Bi, 0-0.080%B, 0-0.50%P, 0-0.0150% Ti, 0-0.10% Sn, 0-0.10% Sb, 0-0.30%Cr, 0-1.0% Ni and the rest, consisting of Fe and impurities, and containing a texture aligned with the Goss orientation, characterized in that when α is defined as the angle of deviation from ideal Goss orientation based on an axis of rotation parallel to the Z normal direction, when β is defined as the angle of deviation from ideal Goss orientation based on an axis of rotation parallel to the transverse direction C, when γ is defined as the angle of deviation from the ideal Goss orientation based on an axis of rotation parallel to the rolling direction L, when (α ₁ β ₁ γ ₁ ) and (α ₂ β ₂ γ ₂ ) are the deviation angles of the crystallographic orientations measured at two measurement points that are adjacent on the sheet surface and that have a 1 mm interval, when the boundary condition BAα is defined as |α ₂ - α ₁ | ≥ 0.5° and the grain size RAα _C is defined as the average grain size obtained from the boundary condition BAα in the transverse direction C, when the boundary condition BAβ is defined as |β ₂ - β ₁ | ≥ 0.5° and the grain size RAβ _C is defined as the average grain size obtained from the boundary condition BAβ in the transverse direction C, when the boundary condition BAγ is defined as |γ ₂ - γ ₁ | ≥ 0.5° and the grain size RAγ _C is defined as the average grain size obtained from the boundary condition BAγ in the transverse direction C, and when 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°, there is a low-angle boundary that separates the interior of the secondarily recrystallized grain and satisfies the boundary condition BAγ and which does not satisfy the boundary condition BB, grain size RAα _C and grain size RAγ _C satisfy the condition RAγ _C < RAα _C , and grain size RAβ _C and grain size RAγ _C satisfy the condition RAγ _C < RAβ _C . 2. Sheet of anisotropic electrical steel according to claim. 1, in which when the grain size RB _C is defined as the average grain size obtained from the boundary condition BB in the transverse direction C, grain size RAγ _C and grain size RB _C satisfy the condition 1.10 ≤ RB _C / RAγ _C . 3. The anisotropic electrical steel sheet according to claim 2, wherein the grain size RB _C is 15 mm or more. 4. Sheet of anisotropic electrical steel according to any one of paragraphs. 1-3, in which the grain size RAγ _C is 40 mm or less.

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