JP2917776B2 - Non-oriented electrical steel sheet for high frequency - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency non-oriented electrical steel sheet, and more particularly to a high frequency non-oriented electrical steel sheet having a low iron loss and a high magnetic flux density.

[0002]

2. Description of the Related Art In recent years, there has been a demand for higher efficiency of electric equipment from the viewpoint of energy saving, and electric equipment is often used in a high frequency range. For this reason, electromagnetic steel sheets used for iron cores of motors and the like are required to have excellent high-frequency magnetic properties.

[0003] However, when an electromagnetic steel sheet is magnetized in a high frequency range, iron loss increases sharply due to an increase in eddy current loss. For this reason, attempts have been made to reduce the eddy current loss by reducing the thickness of the steel sheet and increasing the specific resistance of the steel sheet. That is, conventionally, in the high frequency application, from the viewpoint of increasing the specific resistance, an electromagnetic steel sheet having a thickness of 0.1 to 0.25 mm, in which about 1.7 to 6.5% by weight of Si + Al is added, is used. ing.

For example, JP-A-3-223445 discloses that the Si + Al content is set to 2.0 to 4.0% and the plate thickness is set to 0.1%.
A non-oriented electrical steel sheet for high frequency applications having a thickness of about 0.25 mm is disclosed.

[0005]

By the way, motors used in automobiles for NC machine tools and grinders are driven at a high frequency, but have a frequency of 700-2000H.
about z. It is not only important for electromagnetic steel sheets used in such applications to improve efficiency by reducing iron loss, but also high magnetic flux density is required from the viewpoint of increasing torque. For such applications, the above-mentioned Si + Al is 1.7 to 6.
When a steel sheet containing about 5% is used, although a reduction in iron loss is achieved, a reduction in magnetic flux density due to a reduction in saturation magnetic flux density is inevitable, and the demand for higher torque by increasing the magnetic flux density can be satisfied. There is no situation.

The present invention has been made in view of such circumstances, and has as its object to provide a high-frequency non-oriented electrical steel sheet having a low iron loss and a high magnetic flux density in a high-frequency magnetization region.

[0007]

In order to prevent the magnetic flux density of the steel sheet from lowering, it is necessary to reduce the amounts of Si and Al in the steel sheet. This leads to an increase in total iron loss with an increase in loss.
As a result of repeated studies by the inventors of the present invention in order to achieve such contradictory characteristics, the following findings have been obtained.

When an electromagnetic steel sheet having a thickness of about 0.1 to 0.25 mm is magnetized at about 100 to 2000 Hz, the ratio of the hysteresis loss to the total iron loss is about 30 to 70%. Therefore, in order to reduce high-frequency iron loss in a thin magnetic steel sheet having a thickness of about 0.1 to 0.25 mm, it is considered effective to reduce hysteresis loss in addition to reducing eddy current loss.

In order to reduce the hysteresis loss, attention was paid to the magnetic flux distribution in the thickness direction during high-frequency magnetization. That is, when the steel sheet is magnetized at a high frequency, the distribution of the magnetic flux is not uniform in the thickness direction of the steel sheet but is concentrated on the surface layer due to the skin effect of the magnetic flux. Therefore, not only can the magnetic flux density be improved by controlling the texture of the surface layer of the steel sheet, but also the hysteresis loss can be reduced. Due to such hysteresis loss reduction effect,
In a thin magnetic steel sheet having a sheet thickness of about 0.1 to 0.25 mm, a magnetic steel sheet having a low iron loss in a high frequency region can be obtained even with a low Si and low Al magnetic steel sheet than conventional components. Improvement of saturation magnetic flux density due to low Al,
Not only low iron loss due to the formation of a specific texture,
They found that the magnetic flux density increased. The present invention has been made based on such findings of the present inventors.

That is, according to the present invention, C: 0.
005% or less, Si: more than 1.0% and 2.0% or less, A
l: 0.004% or less, or 0.1 to 0.5%;
005% or less, and the thickness t is 0.10 to 0.25 mm
It is necessary to adjust the hot-rolled sheet pressure regulation rate or annealing conditions.
More, in the plate plane (211), (222), (32
1), (332), (200), (110) and (31)
0) When the value of the ratio of the X-ray integrated reflection intensity to the theoretical intensity for each surface is P (hkl), the texture is such that the TP value represented by the following formula is 1.5 or less. From the respective surfaces in the thickness direction in a thickness direction of at least 30% of the thickness.

TP = [P (211) + P (222) + P (321) + P (332)] / [P (200) + P (110) + P (310)] Also, C: 0.005% by weight%. Hereinafter, Si: 1.0
% To 2.0% or less, Mn: 0.2 to 1.0%, P: 0.
2% or less, S: 0.01% or less, Al: 0.004% or less or 0.1 to 0.5%, N: 0.005% or less, and the thickness t is 0.10 to 0.25 mm And hot rolled sheet
By adjusting the pressure ratio or the annealing conditions , (211), (222), (321), (33)
2) When the value of the ratio of the integrated X-ray reflection intensity to the theoretical intensity for each of the (200), (110), and (310) planes is P (hkl), the TP value represented by the above equation And a non-oriented electrical steel sheet for high frequency use, characterized in that the steel sheet contains a texture having a thickness of not more than 1.5 in the thickness direction from each surface thereof in the thickness direction.

Further, in any of the above non-oriented electrical steel sheets for high frequency use, the average crystal grain size D in the steel sheet cross section is:
An object of the present invention is to provide a high-frequency non-oriented electrical steel sheet satisfying 0.1t ≦ D ≦ 0.7t.

Further, in any of the above non-oriented electrical steel sheets for high frequency use, at a frequency of 100 to 2000 Hz, B ₁₀ ≧ 1.54 T and W 15/400 ≦ 35 W / kg. It is intended to provide a conductive electrical steel sheet.

Hereinafter, the present invention will be described in detail.
(1) Reasons for limiting each component are as follows. In the following, all percentages are by weight.

Si: Si is an element effective for increasing the specific resistance of the steel sheet. In order for this effect to be sufficiently exerted in the frequency range assumed by the present invention, it must be contained in an amount exceeding 1.0%. is necessary. On the other hand, the saturation magnetic flux density decreases with the addition of Si, and if it exceeds 2.0%, the value becomes lower than the allowable range. Therefore, the amount of Si is 1.0
% To 2.0% or less.

Al: When Al is added in a small amount, it forms fine AlN and impairs magnetic characteristics. On the other hand, 0.1
%, The AlN becomes coarse, thereby not deteriorating magnetic properties and contributing to an increase in specific resistance.
If it is 0.5% or more, the magnetic flux density is reduced as in the case of Si. Therefore, the amount of Al is set to 0.004% or less or 0.1% or less.
It is specified in the range of 0.5%.

C: Since C has a problem of magnetic aging, it is specified to 0.005% or less where such a problem does not occur. N: When N is 0.005% or more, the magnetic properties are degraded.

Although the above are important components in the present invention, better characteristics can be obtained by defining Mn, S, and P shown below as follows. Mn: Mn is required to be 0.2% or more in order to prevent red hot brittleness during hot rolling, but if it exceeds 1.0%, the magnetic properties deteriorate. Therefore, the amount of Mn is 0.2-1.0
%.

S: Since S forms MnS or the like which degrades the magnetic properties, the upper limit is 0.01% which does not have such a possibility. P: P is an element necessary for improving the punching property of a steel sheet, but when added in excess of 0.2%, the magnetic flux density is reduced. Therefore, the P content is set to 0.2% or less.

It should be noted that addition of Sb, Sn, B, Cu, and Zr for improving the magnetic properties may not be any.
In addition, unavoidable impurity elements other than these elements are allowed in an amount that is contained in ordinary steel.

(2) Plate Thickness Next, the reason for limiting the plate thickness will be described. Reducing the thickness is very effective in reducing eddy current loss in a high frequency range. However, when the sheet thickness is less than 0.10 mm, not only cold rolling becomes difficult, but also the number of stacked steel sheets at the time of assembling the rotor of the motor and the stator is increased, and the production efficiency is reduced. On the other hand, if it exceeds 0.25 mm, eddy current loss increases, leading to an increase in iron loss. Therefore, the plate thickness was set to 0.10 to 0.25 mm.

(3) Texture The texture of the steel sheet surface is measured by measuring the X-ray diffraction pattern based on the reflection method using an X-ray diffractometer after reducing the thickness of the steel sheet to a target thickness. 211), (222), (32)
1), (332), (200), (110) and (31)
From the X-ray integrated reflection intensity I of the 0) plane, a P value defined by the following equation (1) is obtained, and from this P value, a TP value expressed by the equation (2) is obtained. I do.

P (hkl) = 7 × [I / I ₀ (hkl)] / [ΣI / I ₀ (hkl)] I (hkl): X-ray integrated intensity on (hkl) plane I ₀ (hkl): ( theoretical strength on hkl) plane (1) TP = [P (211) + P (222) + P (321) + P (332)] / [P (200) + P (110) + P (310)] (2) That is, (211), (222), (321), and (332) that do not include the <100> direction that is the easy axis of magnetization.
Including the sum of the P values of the surface and the <100> direction (200);
The lower the TP value, which is the ratio of the sum of the P values of the (110) and (310) planes, to the better the texture in the magnetic properties of the steel sheet.

When a steel sheet is magnetized at a high frequency,
Due to the skin effect of the magnetic flux, the distribution of the magnetic flux is not uniform in the thickness direction of the steel sheet but is concentrated on the surface layer. For example, at 100 Hz, about 70% of the magnetic flux concentrates on a portion within 30% of the plate thickness from each surface. This tendency becomes more pronounced as the frequency increases. At 1000 Hz, 80 to 90% of the magnetic flux concentrates on a portion within 30% of the plate thickness from the surface. From this, it is understood that, when a favorable texture is formed in the surface portion of the steel sheet, the magnetic flux density can be improved and the hysteresis loss can be reduced efficiently.

Here, the method of forming the desired texture is not particularly limited. However, in the present invention, since it is important to control the texture of the surface layer portion of the steel sheet, after the pressure is applied to the hot-rolled sheet, It is preferable to apply a method of performing hot-rolled sheet annealing. In this method, the depth of the desired texture of the surface layer portion of the steel sheet can be arbitrarily adjusted by adjusting the pressure regulation rate or the annealing temperature.

In the present invention, based on the above, it is required that a texture such that the above-mentioned TP value is 1.5 or less is included in the thickness direction from each surface in the thickness direction by 30% or more of the thickness. The reason will be described below.

FIG. 1 shows a steel type A (C: 0.040%, S
i: 1.05%, Mn: 0.22%, P: 0.10%,
S: 0.004%, Al: tr, N: 0.0031
%), Steel type B (C: 0.031%, Si: 1.90%,
Mn: 0.60%, P: 0.03%, S: 0.004
%, Al: 0.40%, N: 0.0030%),
Hot rolled sheet pressure control-For electrical steel sheets manufactured using a normal process that does not perform annealing, and for hot rolled sheet pressure control-for an electrical steel sheet whose texture is controlled by adjusting the annealing conditions, it is a diagram showing the relation between TP value and the magnetic flux density B ₁₀ of definitive to 30% of the depth. In addition, the steel sheet manufactured by the normal process without performing the hot-rolled sheet pressure-annealing using the steel type A has a sheet thickness t.
= 0.20 mm, average grain diameter D = 50 μm, and the sheet thickness t = 0.20 m after hot-rolled sheet pressure-annealing
m, average crystal grain size D = 48 μm. A steel sheet manufactured by a normal process using steel type B has a thickness t = 0.20.
mm, the crystal grain size D = 60 μm, and the sheet thickness t = 0.20 mm and the crystal grain size D =
It was 56 μm. Here, the texture was evaluated by the TP value at a depth of 30% of the sheet thickness from the steel sheet surface,
At a frequency of 100 to 2000 Hz, 70 to 90% of the magnetic flux is concentrated in a region within 30% of the plate thickness from the surface of the steel plate. Further, the reason to evaluate the flux density B _10, the frequency 1
Often excitation magnetic flux density of the equipment used in 00~2000Hz are used in relatively high magnetic flux density of about 1.5T, yet high frequency, because the B ₁₀ is substantially equivalent to it.

From FIG. 1, when TP ≦ 1.5, the magnetic flux density becomes higher than that of the conventional material by 0.03 T or more, and it is confirmed that the magnetic flux density is clearly improved. Next, the influence of the frequency on the iron loss reduction effect by controlling the texture will be described. Here, steel type C (C: 0.037
%, Si: 1.10%, Mn: 0.18%, P: 0.1
1%, S: 0.005%, Al: 0.30%, N: 0.
0035%), steel type D (C: 0.045%, Si: 1.
50%, Mn: 0.25%, P: 0.09%, S: 0.
(004%, Al: 0.20%, N: 0.0030%), an electrical steel sheet manufactured using a normal process in which hot-rolled sheet pressure-annealing is not performed, and hot-rolled sheet pressure-annealing conditions. Of the iron loss W15 at each frequency with respect to the magnetic steel sheet of the present invention in which a texture having a TP value of 1.5 or less is included from the surface layer in the thickness direction by 30% or more of the thickness. I asked. As the material of the present invention, t =
0.2 mm, average crystal grain size D = 31 μm, TP ≦ 1.5
Depth of 0.082 mm (x / t = 41%), steel type D
T = 0.1 mm, average crystal grain size D = 23 μ
m, TP ≦ 1.5 region depth 0.035 mm (x / t =
35%). As a conventional material, t = 0.2 mm for steel type C and average crystal grain size D = 30 μm
m, TP at a depth of 30% of the plate thickness from the steel plate surface = 2.
7. For steel type D, t = 0.1 mm, average grain size D
= 21 μm, T at a depth of 30% of the sheet thickness from the steel sheet surface
The one with P = 2.6 was used. FIG. 2 is a plot of the ratio of W15 of the material of the present invention to W15 of the conventional material versus frequency.

From FIG. 2, it can be seen that the frequency is 100 to 2000H.
It can be seen that the effect of improving iron loss is large in the region of z, but the effect of improving iron loss is relatively small below 100 Hz and above 2000 Hz. At less than 100 Hz, the skin effect of the magnetic flux is small, so that
Adjusting the texture at a relatively low level has little effect.
If the frequency exceeds 0 Hz, the ratio of the hysteresis loss to the total iron loss becomes small, so that even if the hysteresis loss is reduced by adjusting the texture, the effect on the total iron loss is small. As can be seen from FIG. 2, in the frequency range of 100 to 2000 Hz, the value of the ratio of W15 of the material of the present invention to W15 of the conventional material is almost constant, and the effect of improving the iron loss by adjusting the texture is this. It can be seen that the frequency does not depend on the frequency in the range. From the above, it is understood that the electromagnetic steel sheet of the present invention is preferably used at 100 to 2000 Hz.

FIG. 3 shows the above steel type A (plate thickness t = 0.20).
mm, average crystal grain size D = 60 μm) and steel type E (C:
0.036%, Si: 1.40%, Mn: 0.17%,
P: 0.13%, S: 0.003%, Al: 0.40
%, N: 0.0040%, plate thickness t = 0.20 mm, average crystal grain size D = 41 μm), the depth from the steel plate surface in the region of TP ≦ 1.5, the magnetic flux density B _10, and the iron loss W 15 / 100
FIG. Here, the depth of the region of TP ≦ 1.5 is obtained by measuring the texture of the plate surface by X-ray diffraction while reducing the thickness from the surface of the steel plate in the plate thickness direction.
Was used. Here, the frequency is 100H
The reason why the iron loss at z was ascertained is based on the results shown in FIG.

[0031] From this Figure 3, the magnetic flux density B ₁₀ and core loss W15
In all cases, it was confirmed that up to 30% of the area of TP ≦ 1.5 rapidly increased as the area from the steel sheet surface entered, and that the area of TP ≦ 1.5 did not change significantly even when the area of TP ≦ 1.5 became deeper. Is done. This is, as mentioned above, 100 Hz
In this case, about 70% of the magnetic flux is concentrated from the surface of the steel sheet to the thickness of the steel sheet. The skin effect of the magnetic flux density becomes more remarkable as the frequency increases, and the magnetic flux concentrates more on the surface layer.
A value of 1.5 is sufficient.

Based on the above results, the present invention requires that a texture having a TP value of 1.5 or less be included in each of the surfaces in a thickness direction of 30% or more of the thickness. (4) Grain Size FIG. 4 is a view showing the effect of the ratio D / t between the crystal grain size and the thickness of the magnetic steel sheet produced using the steel type B and the steel type C on the iron loss W15 / 400. is there. Here, the steel sheet manufactured using the steel type B is t = 0.15 mm, and the steel sheet manufactured using the steel type C at a depth of 0.05 mm or more from the steel sheet surface in the region of TP ≦ 1.5 is t = 0.15 mm. The depth from the steel plate surface in the region of 2 mm and TP ≦ 1.5 was 0.07 mm or more.

As shown in FIG. 4, D / t is 0.1 to
0.7, that is, the crystal grain size D is 0.1 t to 0.7.
Iron loss is further reduced in the range of t. This is because when the crystal grain size D is in the range of 0.1 t to 0.7 t, a desired texture is appropriately developed in the surface layer portion of the steel sheet, but when the crystal grain size D is less than 0.1 t, the desired texture is desired. Even if the texture of is obtained, the hysteresis loss increases because the grain boundaries hinder the domain wall movement. Conversely, when the crystal grain size D exceeds 0.7 t, the hysteresis loss decreases but the eddy current loss increases. This is because iron loss increases.

From the above, the crystal grain size D is 0.1t ≦
The range of D ≦ 0.7t is preferred. Next, a method for producing the non-oriented electrical steel sheet of the present invention will be described. In the present invention, it is important to control the texture of the surface layer of the steel sheet, it is necessary to adjust the texture of the surface layer of the steel sheet using an appropriate method, but there is no limitation on the method, Any technique other than the hot rolling pressure-annealing process described above can be used.

As for the other steps, a commonly used process may be used. That is, regarding steelmaking, molten steel blown in a converter may be degassed and adjusted to a predetermined component. Hot rolling may be performed under ordinary conditions. The cold rolling may be performed once or may be performed two or more times with intermediate annealing therebetween, as long as the desired thickness is finally obtained. For the final annealing, ordinary annealing may be used. By controlling the final annealing conditions, it becomes possible to obtain a desired crystal grain size.

For example, in a 1.4% Si-0.4% Al steel, the hot-rolled sheet pressure regulation is 7.0%, the hot-rolled sheet annealing condition is 850 ° C. × 3 hours, and the sheet is cold-rolled. 0.2m thick
Then, the final annealing is performed at 850 ° C. for 2 minutes to obtain a desired texture. In the present invention, there is no problem in obtaining the texture of the present invention by adding Sb, Sn, B, Cu, Zr, or the like.

[0037]

EXAMPLE A steel material having the composition of steel types 1 to 13 shown in Table 1 was hot-rolled to a thickness of 2.0 mm and then pickled, and then hot-rolled sheet pressure conditions and hot-rolled sheet annealing shown in Table 2 were performed. Hot rolled sheet pressure regulation
Annealing was performed. These steel sheets are successively provided with a thickness of 0.1 to 0.1.
The sample was cold-rolled to 25 mm and subjected to final annealing under the conditions shown in Table 2. The hot-rolled sheet annealing was performed in a 100% H ₂ atmosphere, and the final annealing was performed in a 25% H ₂ -75% N ₂ atmosphere.

The magnetic properties were measured by taking ring test pieces having an outer diameter of 45 mm and an inner diameter of 33 mm from each steel sheet, measuring these test pieces at a frequency of 400 Hz, and further measuring the crystal grain size.

Each steel plate thickness, average crystal grain size, TP ≦ 1.5
Table 3 shows the depth from the surface of the steel sheet and the magnetic properties in the region indicated by. In Table 1, the compositions of steel types 1 to 10 are within the range of the present invention, and the compositions of steel types 11 to 13 are outside the range of the present invention. The numbers 1 to 29 in Tables 2 and 3 indicate the numbers of the steel sheets produced by subjecting these steel types to hot-rolled sheet pressure-annealing treatment under various conditions.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

[Table 3]

Numbers 1, 2, 4, 7 to 9, 11, and 13 each having a steel composition, a plate thickness, and a domain depth having a texture such that the TP value is 1.5 or less satisfy the present invention. , 15
-20 and 23-25 all have low iron loss and high magnetic flux density in the high frequency range, and were confirmed to be excellent as non-oriented electrical steel sheets for high frequency use.

On the other hand, at least one of the composition, the region depth of TP ≦ 1.5, and the plate thicknesses of Nos. 3, 5,
It was confirmed that 10, 12, 14, 21, 27 to 29 have a high iron loss or a low magnetic flux density.

[0045]

According to the present invention, there is provided a high-frequency non-directional electromagnetic steel having a low iron loss and a high magnetic flux density in a high-frequency magnetization region by adjusting the composition, the thickness, and the texture of the surface layer of the steel sheet. Is done.

[Brief description of the drawings]

FIG. 1 shows a steel sheet surface of an electrical steel sheet manufactured using a normal process in which hot-rolled sheet pressure-annealing is not performed, and an electrical steel sheet in which texture is controlled by adjusting hot-rolled sheet pressure-annealing conditions. Value and magnetic flux density B ₁₀ at a depth of 30% of the plate thickness
FIG.

FIG. 2 is a diagram in which the ratio of W15 of the material of the present invention to W15 of the conventional material is plotted against frequency.

Figure 3 is a graph showing a relation between the depth and the magnetic flux density B ₁₀ and core loss W15 / 100 from the steel sheet surface area of the TP ≦ 1.5.

FIG. 4 shows the iron loss W15 of the ratio D / t between the crystal grain size and the thickness of the steel sheet.
The figure which shows the effect on / 400.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tomoyoshi Ohkita 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Inside Nippon Kokan Co., Ltd. (56) References JP-A-5-140646 (JP, A) JP-A-2-310316 (JP, A) JP-A-2-141530 (JP, A) JP-A-4-107216 (JP, A) JP-A-4-325629 (JP, A) A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C22C 38/00 303 C22C 38/06 H01F 1/16

Claims (4)

(57) [Claims] (1) C: 0.005% or less in weight%, S
i: 1.0% to 2.0% or less, Al: 0.004% or less or 0.1 to 0.5%, N: 0.005% or less, and the sheet thickness t is 0.10 to 0.5%. 25mm, hot rolled sheet
By adjusting the pressure ratio or the annealing conditions , (211), (222), (321), (33)
2) When the value of the ratio of the integrated X-ray reflection intensity to the theoretical intensity for each of the (200), (110), and (310) planes is P (hkl), TP is represented by the following equation.
A non-oriented high-frequency electrical steel sheet for high frequency use, comprising a texture having a value of 1.5 or less in the thickness direction from each surface thereof in the thickness direction. TP = [P (211) + P (222) + P (321) + P (332)] / [P (200) + P (110) + P (310)] 2. In% by weight, C: 0.005% or less, S
i: more than 1.0% and 2.0% or less, Mn: 0.2 to 1.0
%, P: 0.2% or less, S: 0.01% or less, Al:
0.004% or less or 0.1 to 0.5%, N: 0.00
5% or less, the sheet thickness t is 0.10 to 0.25 mm, and by adjusting the pressure regulation rate of the hot rolled sheet or the annealing condition.
Ri, the plate plane in the (211), (222), (32
1), (332), (200), (110) and (31)
0) When the value of the ratio of the X-ray integrated reflection intensity to the theoretical intensity for each surface is P (hkl), the texture is such that the TP value represented by the following formula is 1.5 or less. From the respective surfaces in the thickness direction in a thickness direction of at least 30% of the thickness. TP = [P (211) + P (222) + P (321) + P (332)] / [P (200) + P (110) + P (310)] 3. The steel sheet having an average grain size D in a cross section of 0.1%.
2. The structure according to claim 1, wherein t ≦ D ≦ 0.7t is satisfied.
Or the non-oriented electrical steel sheet for high frequency waves according to 2. 4. At a frequency of 100 to 2000 Hz,
4. The high frequency non-oriented electrical steel sheet according to claim 1, wherein B ₁₀ ≧ 1.54T and W _15/400 ≦ 35 W / kg.