JP4216488B2 - Oriented electrical steel sheet and manufacturing method thereof - Google Patents

Description

【００３１】
【表２】

【００３２】
【発明の効果】
本発明の方向性電磁鋼板は、皮膜張力とレーザーの照射エネルギーを、ε_0C、ε_0L、ε_17C 、ε_17L とλ₁₇が所定の範囲になるように調整して得られるものであり、トランスの低鉄損と低騒音を同時に達成することができる。
【図面の簡単な説明】
【図１】 消磁状態を基準とした、磁歪振動0-p 値の磁束密度による変化を示す図である。
【図２】 飽和磁束密度状態を基準とした、磁歪振動0-p 値の磁束密度による変化を示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a grain-oriented electrical steel sheet used for an iron core such as a transformer. More specifically, the present invention contributes not only to lowering iron loss of an iron core but also to lowering noise. The present invention relates to an electrical steel sheet and a method for producing the same.
[0002]
[Prior art]
In recent years, transformers and other electromagnetic application equipment have been required to reduce noise and vibration, and grain oriented electrical steel sheets used for transformer cores are suitable for low noise and low vibration as well as low iron loss. It has come to be required to be. It is said that there is magnetostriction of grain-oriented electrical steel sheets as one of the causes of transformer noise and vibration. Magnetostriction as used herein refers to vibrations observed in the rolling direction of a steel sheet when a grain-oriented electrical steel sheet is excited with an alternating current, and its magnitude is very small on the order of 10 ⁻⁶ . However, until now, it has not been clear what magnetostriction characteristics are effective in reducing the noise of the transformer.
[0003]
Until now, the strategy for reducing noise has been to reduce magnetostriction. It is known that magnetostriction can be reduced by increasing the degree of {110} <001> orientation of secondary recrystallized grains, but this is the same general method as when aiming at low iron loss. One proposal for a material that actively reduces magnetostriction is disclosed in JP-A-8-269562. Here, magnetostriction is reduced by intentionally leaving internal residual strain during annealing. However, in this method, since distortion remains, hysteresis loss increases and iron loss increases.
[0004]
As described above, no actual magnetostrictive properties have been presented as iron core materials for transformer noise reduction, and there are few proposals for materials that reduce magnetostrictive vibration. It is.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a grain-oriented electrical steel sheet that is most suitable for achieving both low iron loss and low noise of a transformer, that is, a grain-oriented electrical steel sheet having low iron loss and low noise, and a manufacturing method thereof. It is in.
[0006]
[Means for Solving the Problems]
The inventors investigated in detail the relationship between magnetostriction of grain-oriented electrical steel sheet and transformer noise, and as a result of studying various material factors that contribute to magnetostriction, the above-mentioned {110} <001 is determined as a factor that determines magnetostriction. > In addition to the degree of orientation integration, it is found that the tension of the insulating film and the application of minute distortion by laser irradiation are very important, and by appropriately controlling these factors, it has magnetostriction characteristics for low noise, In addition, a steel sheet with low iron loss could be developed.
[0007]
The gist of the present invention is as follows.
(1) Exciting the grain-oriented electrical steel sheet in the rolling direction at a frequency of 50 Hz, and the zero-peak value of the magnetostriction vibration in the rolling direction (0-p value: expansion / contraction value at a certain magnetic flux density based on the demagnetized state In the case of measuring with 0-p value ε ₀ when excited to the saturation magnetic flux density, there is no tension film and no laser is irradiated. Based on the value of the state, the absolute value ε _0C changed by the formation of the tension film and the absolute value ε _0L changed by irradiating the laser after the film formation,
ε _0C <2.0 × 10 ^-6
ε _0L <0.8 × 10 ^-6
In the value ε ₁₇ obtained by subtracting the 0-p value at the excitation magnetic flux density 1.7T from the 0-p value at the saturation magnetic flux density, the tension film does not exist and the value in the state where the laser is not irradiated is used as a reference. The absolute value ε _17C changed by the formation of the tension film and the absolute value ε _17L changed by irradiating the laser after the film formation,
ε _17C <1.0 × 10 ^-6
ε _17L <0.3 × 10 ^-6
Furthermore, the 0-p value λ _{17 at} excitation magnetic flux density 1.7T is
-0.5 × 10 ^-6 ≦ λ ₁₇ ≦ 0.5 × 10 ^-6
Is a grain-oriented electrical steel sheet.
[0008]
(2) ε _0C and ε _0L are
1.0 × 10 ^-6 ≤ ε _0C <3.0 × 10 ^-6
0.5 × 10 ^-6 ≤ ε _OL <1.0 × 10 ^-6
Ε _17C and ε _17L are
0.5 × 10 ^-6 ≤ ε _17C <1.5 × 10 ^-6
ε _17L <0.3 × 10 ^-6
The grain-oriented electrical steel sheet according to (1) above.
[0009]
(3) In the method for producing grain-oriented electrical steel sheets containing 1.0 to 4.0% by mass of Si, the tension on the total steel sheet by the primary film formed after finish annealing and the secondary film applied thereafter is 1 MPa or more and less than 8 MPa. A method for producing a grain-oriented electrical steel sheet, wherein the magnetostriction characteristics described in (1) are obtained by irradiating a laser so that the heat input per unit area of the steel sheet is 1 to ² mJ / mm ² .
[0010]
(4) In the method for producing a grain-oriented electrical steel sheet containing 1.0 to 4.0% by mass of Si, the tension on the total steel sheet by the primary film formed after finish annealing and the secondary film applied thereafter is 14 MPa or more, A method for producing a grain-oriented electrical steel sheet, wherein the magnetostriction characteristics described in (1) are obtained by laser irradiation so that the amount of heat input per unit area is 1.5 to 3 mJ / mm ² .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
The grain-oriented electrical steel sheet has three easy magnetization directions [100], [010], and [001]. Of these, the region that has been magnetized in a direction different from the magnetic field direction is oriented in the magnetic field direction when the magnetic field is applied. On the other hand, when the region facing the magnetic field direction faces another easy magnetization direction, expansion or contraction observed in the magnetic field application direction, that is, magnetostriction occurs.
[0012]
[110] In an ideal grain-oriented electrical steel sheet perfectly aligned in the <001> orientation, its magnetic domain structure is formed of a structure composed of a region magnetized only in the rolling direction, that is, only 180 ° magnetic domains. For this reason, magnetostriction does not occur in the magnetization process.
However, in practice, in order to reduce magnetostatic energy due to misalignment, a kind of reflux magnetic domain called a lancet magnetic domain exists in the steel sheet. In addition, a reflux magnetic domain also exists in the region where strain is introduced and in the end portion of the steel plate. The return magnetic domain has a region magnetized in the plate thickness direction. If this region decreases, the magnetostriction shows a positive (extension) change, and if it increases, it shows a negative (contraction) change.
[0013]
The magnetostriction 0-p value of grain-oriented electrical steel sheets that have no forsterite or tension insulation film and are not laser-irradiated is monotonous with the excitation magnetic flux density as shown in Fig. 1- (A). To increase. This is because, in the demagnetized state, the above-described lancet magnetic domains exist depending on the orientation integration degree, and the volume thereof is reduced with excitation.
[0014]
When a tensile insulating film is applied to the steel sheet, the magnetostriction once decreases as shown in 1- (B), but starts to increase at a high magnetic flux density of about 1.7 T or more. This is due to the following reason.
Due to the magnetoelastic effect, by applying tension to the steel sheet, the energy of the portion magnetized in the thickness direction is increased, so that the volume of the demagnetized lancet magnetic domain is reduced compared to the case without tension. When a magnetic field is applied to this, the 180 ° domain wall moves, but this increases the magnetostatic energy of the surface, so that the lancet domain increases to reduce the magnetostatic energy. Therefore, the steel sheet contracts in this magnetic field region. When the magnetic field is further strengthened and the 180 ° domain wall motion is completed, magnetization proceeds while the lancet magnetic domain disappears. At this time, the steel sheet extends.
[0015]
In the curves 1- (A) and 1- (B) above, the magnetization saturation state is the same state in which the magnetization components other than the rolling direction have disappeared. Cheap.
FIG. 2 shows the dependence of the magnetostriction 0-p value on the magnetic flux density, assuming that the magnetostriction 0-p value during saturation magnetization is zero. In the case of a steel plate without a tension coating, as shown in 2- (A), the magnetostriction 0-p value decreases monotonously with a decrease in magnetic flux density. On the other hand, as shown in 2- (B), the steel sheet coated with a tensile film decreases once but increases after taking a minimum. In the demagnetized state of 2- (B), the steel sheet is stretched by ε _0C shown in the figure with respect to 2- (A).
[0016]
As for the minimum, first, the magnetic flux density taking the minimum depends on the orientation degree of the steel sheet in the [110] <001> direction, but as a result of the inventors' investigation, it is 1. It turned out to be about 7T. Therefore, at ε ₁₇ defined above, the minimum value of 2- (B) is extended by ε _{17C with} respect to 2- (A). These ε _0C and ε _17C can be freely controlled by changing the tension of the insulating coating.
[0017]
The inventors have also found that the magnetostriction characteristics can be freely controlled by further irradiating a laser after the formation of the tension film. This effect is shown below.
When 1- (B), the magnetostriction 0-p value after film formation in Fig. 1, is irradiated with laser, the magnetostriction 0-p value increases monotonously as shown in 1- (C). Change. This is presumably because the reflux magnetic domain is formed because the laser irradiation introduces strain in the steel sheet, and this reflux magnetic domain disappears upon excitation.
[0018]
FIG. 2 shows a case where the saturation magnetization state is used as a reference. Curve 2- (C) when laser irradiation is performed after film formation decreases with decreasing magnetic flux density, and in the degaussed state, the steel sheet contracts by ε _0L as shown in the figure compared to 2- (B). Become. In addition, ε ₁₇ defined in 1.7T contracts by ε _17L . These ε _0L and ε _17L can be freely controlled by changing the laser irradiation energy.
[0019]
Furthermore, as a result of intensive studies on the magnetostriction characteristics of grain-oriented electrical steel sheets in order to reduce noise such as transformers, it is important to reduce the magnetostriction amplitude. It was found that controlling the magnetostriction 0-p value λ ₁₇ at a predetermined density of 1.7 T to a predetermined magnitude is essential for reducing the noise of the device.
That is,
-0.5 × 10 ^-6 ≦ λ ₁₇ ≦ 0.5 × 10 ^-6
It is indispensable to control.
If λ ₁₇ is too small, the high-frequency component of the magnetostrictive vibration waveform increases, and if λ ₁₇ is too large, the magnetostriction amplitude increases, which contributes to an increase in transformer noise. Conceivable.
[0020]
In order to obtain a noise-free material, the film tension and laser irradiation energy are appropriately controlled, and the previous ε _0C , ε _0L , ε _17C , and ε _17L are
ε _0C <2.0 × 10 ^-6
ε _0L <0.8 × 10 ^-6
ε _17C <1.0 × 10 ^-6
ε _17L <0.3 × 10 ^-6
In addition, the 0-p value λ _{17 of the} excitation magnetic flux density 1.7T is
-0.5 × 10 ^-6 ≦ λ ₁₇ ≦ 0.5 × 10 ^-6
I found it necessary to satisfy.
[0021]
If the film tension is reduced, ε _0C and ε _17C will decrease, but if it is too small, the deterioration of magnetostriction will increase when the steel sheet is stressed during transportation or assembly of the transformer, and iron loss will also increase. Since both deteriorate, it is preferable that both be larger than 0.1 × 10 ⁻⁶ . Moreover, since these values have upper limits depending on the orientation accumulation degree, they are defined to be smaller than 2.0 × 10 ⁻⁶ and 1.0 × 10 ⁻⁶ , respectively.
[0022]
As the laser irradiation energy increases, ε _0L and ε _17L increase. If the laser irradiation energy is too large, the magnetostrictive vibration amplitude will increase and the noise when assembled in the transformer will increase, so ε _0L is less than 0.8 × 10 ^-6 and ε _17L is less than 0.3 × 10 ^-6 Stipulated.
[0023]
The film tension can be controlled by adjusting the amount of forsterite film formed after finish annealing and the amount and components of the insulating film applied thereon. Laser irradiation can be performed using a CO ₂ laser or a YAG laser. From the viewpoint of reducing iron loss, it is desirable that the strain introduction region by the laser extends in a band shape perpendicular to the rolling direction of the steel sheet, and the strain band is introduced periodically in the rolling direction.
[0024]
It was also found that the required magnetostriction characteristics vary depending on the design magnetic flux density of the equipment. First, when the transformer design magnetic flux density is relatively low, it is important to reduce the harmonic noise of the transformer by smoothing the magnetostrictive vibration waveform of the steel sheet and reducing the vibration noise. It was found that the relatively weaker one is more effective. However, this method causes deterioration of iron loss. Therefore, it was possible to realize low magnetostriction and low iron loss by appropriately irradiating laser and performing magnetic domain control.
[0025]
The above electromagnetic steel sheet is manufactured by making the total tension of the forsterite film and insulating film 1 MPa or more and less than 8 MPa, and laser irradiation so that the heat input per unit area of the steel sheet is 1 to ² mJ / mm ^2. can do.
[0026]
If the tension of the insulation film is low, the magnetostriction deteriorates when the steel sheet is stressed during transportation or assembly of the transformer, and the iron loss also deteriorates. Further, if the tension is too strong, the waveform of the magnetostrictive vibration contains a lot of harmonic components, so it was set to less than 8 MPa.
Further, when the design magnetic flux density is high, it is important to increase the tension on the steel sheet as much as possible and to appropriately control the laser irradiation intensity according to the film tension. As a result, the magnetostriction λ ₁₇ can be controlled to the predetermined magnitude shown above, and the magnetostriction amplitude can be kept small from a low magnetic flux density to a high magnetic flux density.
[0027]
Specifically, ε _0C and ε _0L are
1.0 × 10 ^-6 ≤ ε _0C <3.0 × 10 ^-6
0.5 × 10 ^-6 ≤ ε _OL <1.0 × 10 ^-6
And ε _17C and ε _17L are
0.5 × 10 ^-6 ≤ ε _17C <1.5 × 10 ^-6
ε _17L <0.3 × 10 ^-6
And then
-0.5 × 10 ^-6 ≦ λ ₁₇ ≦ 0.5 × 10 ^-6
Control to be.
Specifically, it can be manufactured by irradiating laser so that the total steel sheet tension by primary and secondary coatings is 14 MPa or more and the heat input per unit area of the steel sheet is 1.5 to 3 mJ / mm ^2. it can.
[0028]
【Example】
(Example 1)
For a grain oriented electrical steel sheet with a thickness of 0.23 mm, which had been subjected to final annealing by a conventional method, the thickness of the forsterite film and the coating amount of the insulating tension film were controlled to change the film tension. Further, the irradiation pitch in the rolling direction was 5 mm, the irradiation pitch in the direction perpendicular to the rolling was 0.03 mm, the pulse energy was changed, and the steel plate was irradiated with laser. A YAG laser was used as the laser. Irradiation energy is expressed as energy introduced per area of the steel sheet. For the measurement of magnetostriction, a laser Doppler type magnetostriction measuring apparatus was used, and 10 sheets of each condition were subjected to the test. Table 1 shows the sample preparation conditions and the average magnetostriction measurement results of 10 sheets.
[0029]
Furthermore, three-phase three-legged iron cores of 750 mm x 750 mm were prepared from the steel plates under the respective conditions, and noise was measured. The width of the steel sheet was 150 mm and the number of stacked sheets was 180 sheets. When the film tension was 0, an insulating film that did not generate tension was applied. The results are shown in Table 2. By using the steel plate of the present invention, the noise reduction of the transformer was realized. Although the iron loss of the iron core is also shown in the table, good iron loss is obtained in the present invention.
[0030]
[Table 1]

[0031]
[Table 2]

[0032]
【The invention's effect】
The grain-oriented electrical steel sheet of the present invention is obtained by adjusting the film tension and laser irradiation energy so that ε _0C , ε _0L , ε _17C , ε _17L and λ ₁₇ are in a predetermined range. Low iron loss and low noise can be achieved at the same time.
[Brief description of the drawings]
FIG. 1 is a diagram showing a change in magnetostriction vibration 0-p value with a magnetic flux density based on a demagnetized state.
FIG. 2 is a diagram showing a change in magnetostriction vibration 0-p value with a magnetic flux density based on a saturation magnetic flux density state.

Claims (4)

When a grain-oriented electrical steel sheet is excited in the rolling direction at a frequency of 50 Hz and the zero-peak value (0-p value) of magnetostriction vibration in the rolling direction is measured, the 0-p value when excited to the saturation magnetic flux density ε ₀ The absolute value ε _0C changed by the formation of the tension film and the absolute value changed by irradiating the laser after the film formation with respect to the value in the state where the tension film does not exist and the laser is not irradiated. The value ε _0L is
ε _0C <2.0 × 10 ^-6
ε _0L <0.8 × 10 ^-6
In the value ε ₁₇ obtained by subtracting the 0-p value at the excitation magnetic flux density 1.7T from the 0-p value at the saturation magnetic flux density, the tension film is not present and the value in the state where the laser is not irradiated is used as a reference. The absolute value ε _17C changed by the formation of the tension film and the absolute value ε _17L changed by irradiating the laser after the film formation,
ε _17C <1.0 × 10 ^-6
ε _17L <0.3 × 10 ^-6
Furthermore, the 0-p value λ _{17 at} excitation magnetic flux density 1.7T is
-0.5 × 10 ^-6 ≦ λ ₁₇ ≦ 0.5 × 10 ^-6
Is a grain-oriented electrical steel sheet. ε _0C and ε _0L are
1.0 × 10 ^-6 ≤ ε _0C <3.0 × 10 ^-6
0.5 × 10 ^-6 ≤ ε _OL <1.0 × 10 ^-6
Ε _17C and ε _17L are
0.5 × 10 ^-6 ≤ ε _17C <1.5 × 10 ^-6
ε _17L <0.3 × 10 ^-6
The grain-oriented electrical steel sheet according to claim 1, wherein In the manufacturing method of grain-oriented electrical steel sheet containing 1.0 to 4.0% by mass of Si, the total tension on the steel sheet by the primary film formed after finish annealing and the secondary film applied thereafter is 1 MPa or more and 8 MPa or less. 2. A method for producing a grain-oriented electrical steel sheet according to claim 1, wherein the magnetostrictive property according to claim 1 is obtained by irradiating a laser so that a heat input per unit area is 1 to ² mJ / mm ² . In the method for producing a grain-oriented electrical steel sheet containing 1.0 to 4.0% by mass of Si, the total area of the steel sheet by the primary film formed after finish annealing and the secondary film applied after that is 14 MPa or more, and the unit area of the steel sheet 2. A method for producing a grain-oriented electrical steel sheet according to claim 1, wherein the magnetostrictive property according to claim 1 is obtained by irradiating a laser so that the amount of heat input per unit is 1.5 to 3 mJ / mm ² .

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