JP2001279398A - Nonoriented silicon steel sheet excellent in high frequency magnetic property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonoriented silicon steel sheet having excellent magnetic properties in a frequency region of >=1 kHz, and further >=10 kHz, and advantageously suited to a high frequency reactor. SOLUTION: In the nonoriented silicon steel sheet which has a composition containing 1.5-20 mass% Cr and 2.5-10 mass % Si, also containing C and N in amounts reduced, in total, to <=100 ppm, and having the balance iron with inevitable impurities, 111} inverse strength at least in the surface layer of the steel sheet is regulated to >=3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a non-oriented electrical steel sheet suitable for use in, for example, a high-frequency reactor, particularly 10 kHz
The present invention relates to a non-oriented electrical steel sheet having excellent magnetic properties in the above frequency range.

[0002]

2. Description of the Related Art In recent years, to protect and improve the global environment,
Momentum for energy saving is increasing. When attention is paid to electric equipment, products adopting an inverter method are increasing for higher efficiency and power saving, and the frequency thereof is shifting to a high frequency range every year for higher efficiency. Conventionally, a reactor has been used for the purpose of improving a power factor with the use of an inverter and a high frequency, but the use of a high frequency reactor for an inverter device has been increasing for the purpose of further preventing power supply pollution. These high-frequency reactors are 1kHz or more,
Furthermore, since it is used in the frequency range of 10 kHz or more, if a conventional high-frequency silicon steel sheet is used, heat generation becomes large and it is difficult to use it. I had no choice.

Here, in order to improve high-frequency iron loss,
It is important to increase the specific resistance of steel, and in general,
A method of increasing the Al content has been employed. However, Si and Al
When the content of is increased, the processability deteriorated, and it was difficult to manufacture by a usual method. As a technique for improving the manufacturability, a method of performing low-temperature and high-pressure reduction in hot rolling of a high silicon steel sheet described in JP-A-61-166923,
There is a method based on diffusion and infiltration treatment of Si described in JP-A-62-227078. However, none of these technologies improves the brittleness inherent in high-Si or high-Al steels, and the products manufactured thereby have extremely poor workability and are difficult to process into reactors. there were. Further, the former technique disclosed in Japanese Patent Application Laid-Open No. 61-166923 requires fine adjustment of the rolling structure to apparently improve the brittleness of the alloy, and strict control is required in the manufacturing process. Since it must be performed, it is difficult to produce industrially stably. On the other hand, the latter technique disclosed in JP-A-62-227078 uses a special diffusion infiltration method, which is extremely disadvantageous in terms of cost in the case of industrial production. It is disadvantageous for high-frequency iron loss because it becomes coarse.

[0004] In fact, a steel sheet containing 6.5 mass% of Si exists as a high Si material by diffusion and infiltration of Si, and is used as a reactor core for an inverter air conditioner, but its growth is about 5%. However, since punching and bending are difficult with a normal method, strip-shaped steel plates are laminated to produce a reactor core. If bending and punching are possible in the usual way, punched and laminated cores such as wound cores and EI cores can be manufactured,
Significantly contributes to the reduction of the processing cost.

A technique of adding Cr to increase the specific resistance of steel without increasing the amount of Si is disclosed in JP-A-11-22909.
No. 5 publication. However, the content of Si is not beyond the range of ordinary silicon steel sheets, and is intended for electric vehicle motor core materials,
The usable frequency range also corresponds to a frequency of less than 1 kHz, as in the case of conventional silicon steel sheets for high frequency applications, and sufficient high frequency magnetic characteristics have not been obtained as a material for high frequency reactors of 1 kHz or more.

[0006]

As described above, in the prior art, increasing the specific resistance until it can be used for a frequency application of 1 kHz or more has not been performed except for the use of Si and Al. At present, it has not been attempted to improve the brittleness inherent in the high Si, Al steel material itself, which has increased the specific resistance of the steel.

Accordingly, an object of the present invention is to propose a non-oriented electrical steel sheet that is advantageously adapted to a high-frequency reactor having excellent magnetic characteristics in a frequency range of 1 kHz or more, and even 10 kHz or more.

[0008]

Means for Solving the Problems The present inventors conducted research and development on Fe-Si alloys and Fe-Si-Al alloys in order to achieve both high specific resistance and good workability. The knowledge that coexistence is effective was obtained, and the result was proposed in JP-A-11-343544. That is, in the Fe-Si alloy and the Fe-Si-Al alloy, it has been thought that the toughness deteriorates as Cr is added. However, even if the content of Si is 3 mass% or more, C and N It has been found that, by sufficiently reducing the content of, and by containing Cr in a certain amount or more, rather high toughness can be obtained.

Based on such technology, the inventors have conducted intensive studies with the aim of further improving high-frequency magnetic characteristics, and as a result, have reduced the total amount of C and N.
It has been found that workability can be ensured by adding Mn.

At the same time, Fe—
Cr-Si alloys and Fe-Cr-Si-Al alloys, even in component systems having a specific resistance of 60 μΩcm or more, if the contents of C and N are sufficiently reduced, Cr having the same specific resistance It was also found that the workability was significantly improved as compared with alloys containing no.

In addition, it has been found that under the condition that eddy current loss is reduced, reduction of hysteresis loss is effective for further reducing iron loss, and it has been found that the hysteresis loss is greatly affected by texture. Was completed.

That is, the gist configuration of the present invention is as follows. (1) Cr: 1.5 mass% or more and 20 mass% or less and Si: 2.5 mass%
% And 10 mass% or less, and the total amount of C and N is 100%.
ppm or less, the balance being iron and unavoidable impurities, in a non-oriented electrical steel sheet, the {111} inverse strength of at least the surface layer of the steel sheet is 3 or more. Non-oriented electrical steel sheet with excellent and high space factor.

(2) Cr: 1.5 mass% or more and 20 mass% or less, S
i: 2.5 mass% or more and 10 mass% or less and Al: 5 mass% or less, reducing the total amount of C and N to 100 ppm or less,
The remainder is a non-oriented electrical steel sheet composed of iron and unavoidable impurities.
(1) A non-oriented electrical steel sheet excellent in high-frequency magnetic properties and having a high space factor, having an inverse strength of 3 or more.

(3) Cr: 1.5 mass% or more and 20 mass% or less;
Si: contains not less than 2.5 mass% and not more than 10 mass%, contains one or two of Mn and P at 1 mass% or less, reduces C and N to 100 ppm or less in total, and balances iron And a non-oriented electrical steel sheet having a component composition of unavoidable impurities, wherein {111} inverse strength in at least the surface layer of the steel sheet is 3 or more, and is excellent in high-frequency magnetic characteristics and high in space factor. Electrical steel sheet.

(4) Cr: 1.5 mass% or more and 20 mass% or less, S
i: Including 2.5 mass% or more and 10 mass% or less and Al: 5 mass% or less, containing either one or two of Mn and P at 1 mass% or less, and 100 ppm or less in total of C and N And the balance is iron and unavoidable impurities in a non-oriented electrical steel sheet, in which the {111} inverse strength at least at the surface layer of the steel sheet is 3 or more, and has excellent high-frequency magnetic characteristics. Non-oriented electrical steel sheet with high space factor.

(5) In any one of the above (1) to (4), the {111} inverse strength is 3 or more in the surface layer from the surface of the steel sheet to a depth of 1/5 of the sheet thickness. Non-oriented electrical steel sheet with excellent high frequency magnetic properties and high space factor.

Here, {111} inverse strength is
It means the ratio of the intensity of the X-ray reflection surface in the {111} orientation on the final product plate to that of the random texture.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The non-oriented electrical steel sheet of the present invention has a synergistic effect on the magnetic properties by increasing the specific resistance by including Cr together with Si. As a result, iron loss particularly in a high frequency range can be significantly reduced as compared with only Si or Al, or an alloy containing Si and Al.

Further, the material having a high specific resistance so far has a poor rolling property, and the thickness is reduced only to about 0.5 mm by the ordinary rolling method. It has also been said that simply reducing the thickness does not allow a sufficient reduction in iron loss due to hysteresis loss. However, as a result of the inventors' earnest research, as in the present invention, by controlling the components and purity,
The effect of the high-frequency iron loss characteristics when the thickness is reduced can be promoted.

Therefore, the non-oriented electrical steel sheet of the present invention
Because of its excellent magnetic properties in the frequency range of 1 kHz or more, it is most suitable as a reactor material for inverter air conditioners and reactors for photovoltaic power generation. And an efficient reactor product can be obtained.

Further, in the non-oriented electrical steel sheet according to the present invention, the texture of the steel sheet is regulated in order to improve the magnetic properties particularly in a frequency range of 10 kHz or more. That is, Fe- (1.
5-6) mass% Cr- (2-6) mass% Si-based alloy is melted and made into a steel ingot, and this steel ingot is cut out to a thickness of 60 mm.
The relationship between the {111} inverse strength of the texture of the surface layer and the high-frequency hysteresis loss of each steel sheet of a steel sheet heated to ℃ and rolled to a sheet thickness of 1.8 mm and then cold-rolled to a sheet thickness of 0.1 mm Is shown in FIG. The impurity content of the alloy is as follows: C: 10 to 80 ppm, P: 10 to 80 ppm
500 ppm, S: 10-100 ppm, N: 10-80 ppm, O: 10-
50 ppm, C + N: 20-200 ppm, and the specific resistance of the steel sheet was 60 μΩcm.

As is apparent from FIG. 1, when the {111} inverse strength is 3 or more, the hysteresis loss is remarkably improved.

Here, the {111} texture has a smaller hysteresis loss in the low magnetic field region and in the high frequency region as shown in FIG. Works advantageously for the improvement of the magnetic properties. The reason for this is not clear, but is considered as follows. In other words, the {100} texture of a silicon steel sheet takes a 180-degree magnetic domain structure during the magnetization process in a low magnetic field,
Hysteresis loss due to domain wall motion occurs,
The {111} texture forms
This is because the hysteresis loss is smaller than that in the case of {100} texture, because a process by magnetization rotation is performed without generating a 180-degree magnetic domain.

The dependence of the magnetic permeability on the magnetizing force H also shows a good correlation as compared with the texture in other orientations, and is therefore particularly suitable as a material for a high-frequency reactor.
This is because, as a material, linearity of the magnetic permeability with respect to the magnetizing force H is one factor of the reactor characteristics.
This is because even if the current of the circuit changes, the reactor characteristics need to be stable with the amount of current.

The non-oriented electrical steel sheet according to the present invention will be described first with reference to the reasons for limiting each component range of the component composition. Cr: 1.5 mass% or more and 20.0 mass% or less Cr is a basic element that greatly improves electric resistance by a synergistic effect with Si and / or Al, reduces iron loss in a high frequency range, and further improves corrosion resistance. Alloy component, especially 3.
When containing 5 mass% or more of Si, or 3 mass% or more
Even if it contains Si and more than 1 mass% of Al,
It is extremely effective for obtaining toughness to the extent that it can be warm-rolled, and from that viewpoint, 2 mass% or more is required. When the amount of Si or Al is smaller than the above range, the amount of Cr is 2 mass%.
%, The workability can be ensured, but in order to exhibit the effect of improving the workability of Cr and to make the specific resistance of the alloy 60 μΩcm or more, Cr of 1.5 mass% or more is essential. On the other hand, if the Cr content exceeds 20 mass%, the effect of improving the toughness is saturated and the cost is increased. Therefore, the Cr content is specified to be 1.5 mass% to 20 mass%, preferably 10 mass% or less.

Si: not less than 2.5 mass% and not more than 10 mass% Si is a component effective for significantly increasing electric resistance by a synergistic effect with Cr and reducing iron loss in a high frequency range. However, when the amount of Si is less than 2.5 mass%, even if Cr and Al are used together, a specific resistance of 60 μΩcm or more cannot be obtained without sacrificing much the magnetic flux density. On the other hand, if the content exceeds 10 mass%, the toughness until warm rolling cannot be ensured even when Cr is contained, so that the Si content is 2.5 mass% or more and 10 mass% or less, preferably 7 mass% or less, more preferably 3.5 mass% or less. % Or more 7
mass% or less.

Al: not more than 5 mass% Al, like Si, is a component that is effective in significantly improving electrical resistance by synergistic effect with Cr and reducing iron loss in a high frequency range. Therefore, Al can be contained in the present invention as needed.
However, if the amount of Al exceeds 5 mass%, the cost is increased, and the toughness until warm rolling cannot be ensured even with the inclusion of Cr. Therefore, it is necessary to contain Al at 5 mass% or less. On the other hand, the lower limit of Al does not have to be particularly limited.
When Al is contained in an amount of about 005 to 0.3 mass% and Al is positively used for increasing the electric resistance, it is preferable to contain Al in a range of 0.5 mass% or more. Therefore, Al
The content is preferably 0.005 mass% or more, more preferably 0.5 mass% or more and 3 mass% or less.

C and N: 100 ppm or less in total amount C and N must be reduced as much as possible in order to degrade the toughness of the Fe—Cr—Si based alloy.
In order to ensure high toughness under the amounts of Si, Al and Al, it is important to keep the total amount to 100 ppm or less. Preferably, each of C and N is 50 ppm or less, more preferably
30 ppm or less.

The amount of impurities other than C and N is not particularly limited. For example, S is 20 ppm or less, preferably 10 ppm or less, more preferably 5 ppm or less, and O is 50 ppm or less, preferably 30 ppm or less, more preferably Is recommended to be regulated to 15 ppm or less, or to 120 ppm or less, preferably 50 ppm or less in total of impurities C + S + N + O.

1 mass% or less of one or both of Mn and P can be further increased by further adding Mn and P to the Fe—Cr—Si alloy. . By the addition of these components, a further reduction in iron loss can be achieved without impairing the spirit of the present invention. However, if these components are added in a large amount, the cost is increased. Therefore, the upper limit of each added amount is 1 mass%. More preferably, each is 0.5 mass% or less.

In the present invention, the addition of a conventionally known alloy component for the purpose of further improving the magnetic properties, corrosion resistance, workability, etc. does not impair the effects of the present invention. It is also possible to include components. Representative examples of those components are listed below.

That is, Ni of 5 mass% or less is a component for improving corrosion resistance, lowers the ductile-brittle transition temperature, improves workability, and easily makes crystal grains fine.
It is effective in suppressing eddy current loss and reducing high frequency iron loss.
Cu of 1 mass% or less has the same effect as Ni. 5 mass%
The following Mo and W improve corrosion resistance. La of less than 1 mass%,
V or Nb, Ti or Y or Zr of 0.1 mass% or less, and B of 0.1 mass% or less have an effect of increasing toughness and improving workability.
Co of 5 mass% or less improves the magnetic flux density and is effective in reducing iron loss. Sb and Sn of 0.1 mass% or less improve the texture and are effective in reducing iron loss.

Further, in the non-oriented electrical steel sheet of the present invention,
Regarding the texture, at least the surface
As described above, it is important to set the 1｝ inverse strength to 3 or more. Specifically, the surface layer portion of the steel sheet having the {111} inverse strength of 3 or more extends from the surface to a depth of at least １ ／ of the sheet thickness. That is, the improvement of the hysteresis loss in the high-frequency range due to the texture increases as the surface is closer to the steel sheet surface.
By regulating the texture in the surface layer up to a depth of / 5, the above-described effect can be obtained.

In order to obtain the desired texture in the present invention, the annealing conditions, the rolling reduction during rolling, and the like may be appropriately adjusted, or if necessary, normalization may be performed. For example, the electromagnetic steel hot rolled sheet obtained by the ordinary process is subjected to one or a plurality of cold or warm rollings sandwiching the intermediate annealing with a single pass of a tandem rolling mill or a Zenzimer rolling mill. , When finishing to a specified thickness of 0.30mm or less, the total rolling reduction in the final pass of each rolling is 65%
Or an intermediate annealing in the range of 700 to 1000 ° C.
s ~ 10min or normalization if necessary 700 ~
By performing in the range of 1000 ° C. for 1 s to 1 h, {11
1) A steel sheet having an inverse strength of 3 or more is obtained.

Incidentally, in order to produce a highly workable Fe—Cr—Si alloy thin plate excellent in the magnetic material of the present invention, as a raw material, high purity electrolytic iron, electrolytic chromium having a purity of 99.9 mass% or more,
It is preferable to use metal Si and metal Al. When Mn and P are added, they also use high-purity raw materials. Alternatively, in the case of manufacturing by the converter method, care must be taken to sufficiently refine to a predetermined purity and not to be contaminated in a later step. At the time of melting, it is preferable to use, for example, a vacuum melting furnace of high vacuum (a pressure of 10 ⁻³ Torr or less) in addition to the converter method.

Next, in hot rolling, by rolling as thin as possible, workability in the next step of cold rolling or warm rolling, ie, rollability, can be improved. This is based on the new finding that in the case of the Fe-Cr-Si-based alloy composition of the present invention, the surface portion of the hot-rolled sheet has higher toughness than the central portion and has excellent workability. is there. The thickness of the hot rolled sheet for that purpose is 3 mm or less, preferably 2.
5 mm or less, more preferably 2.0 mm or less.

Since the toughness of the hot-rolled sheet is improved, the sheet can be further rolled hot or cold to obtain a thin sheet having a thickness of not more than 0.4 mm. 0.30
mm or less. Then, in this rolling step, an intended texture is obtained by controlling the annealing conditions and the rolling reduction.

By the way, it is well known that, in general, when the plate thickness is reduced, eddy current loss is advantageously suppressed particularly at high frequencies, resulting in low iron loss. However, materials with high electrical resistance have been poorly rollable so far, and 0.5 mm
It was only reduced to the extent. It has also been said that simply reducing the thickness does not allow a sufficient reduction in iron loss due to hysteresis loss. In this regard, in the present invention, it has been found that by selecting the component system and the purity, the effect of the high-frequency iron loss characteristics when the thickness is reduced can be promoted. In order to obtain such an effect of thickness reduction, it is effective to make the plate thickness 0.4 mm or less. However, to make it thinner than 0.01mm,
Due to cost and industrial implications, the range of thickness is 0.01
0.30.30 mm, preferably 0.03 to 0.30 mm.

In such rolling for reducing the thickness,
Because the workability of the material is excellent, it is not always necessary to secure the rollability by annealing the hot-rolled sheet as in the past, or intermediate annealing during cold rolling or warm rolling, especially in the past. , Improving work efficiency by omitting hot-rolled sheet annealing and intermediate annealing,
Energy saving and cost reduction can be achieved. Subsequent annealing and surface finishing can be performed by the same steps as those for a normal electromagnetic steel sheet or an electromagnetic stainless steel sheet.

[0040]

EXAMPLE A steel slab having the composition shown in Table 1 was hot-rolled to various thicknesses, and then cold-rolled and annealed according to the conditions shown in Table 2 to a predetermined thickness.
Finish annealing was performed at ℃ to obtain a product plate.

From the product plate thus obtained, the product thus obtained was cut into an Epstein sample, and JIS C 2550
Table 3 shows the results of measuring the magnetism according to (1992). The measurement of the hysteresis loss is the same as described above.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

[Table 3]

From Tables 1 to 3, it can be seen that Nos. 1, 2, 4 and 5 with steel types A and C in which Cr is out of the range of the invention have the effect of reducing the hysteresis loss even when the {111} inverse strength is in the range of the invention. It can be seen that the magnetic properties were not improved. Cr is steel type D within the scope of the invention and {111}.
No. 7 whose inverse strength is within the range of the invention is {111}
Hysteresis loss was reduced and iron loss was also lower than No. 6 having a low inverse strength. That is, it can be seen that the effect of improving the iron loss in the low magnetic field and high frequency range by the {111} texture is remarkable in the Cr-containing component system.

[0046]

The non-oriented electrical steel sheet of the present invention has excellent high frequency iron loss and magnetic flux density, is particularly suitable for high frequency applications, and has a great industrial value.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between {111} inverse intensity and hysteresis loss.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaaki Kono 1-chome, Kawasaki-dori, Mizushima, Kurashiki-shi, Okayama Pref. Chome (without address) Kawasaki Steel Corporation Mizushima Works (72) Inventor Atsuto Honda 1-chome, Mizushima Kawasaki-dori, Kurashiki City, Okayama Prefecture (without address) Kawasaki Steel Corporation Mizushima Works F-term (reference) AA19 NN01 NN06

Claims (5)

[Claims] (1) Cr: 1.5 mass% to 20 mass% and Si:
A non-oriented electrical steel sheet containing 2.5 mass% or more and 10 mass% or less, reducing the total amount of C and N to 100 ppm or less, and the balance being iron and unavoidable impurities. A non-oriented electrical steel sheet having excellent {111} inverse strength of 3 or more and having excellent high-frequency magnetic properties and a high space factor. (2) Cr: 1.5 mass% to 20 mass%, Si: 2.
Non-oriented electrical steel sheets containing 5 mass% or more and 10 mass% or less and Al: 5 mass% or less, reducing the total amount of C and N to 100 ppm or less, with the balance being iron and unavoidable impurities. A non-oriented electrical steel sheet having excellent high-frequency magnetic properties and a high space factor, characterized in that {111} inverse strength in at least the surface layer of the steel sheet is 3 or more. 3. Cr: 1.5 mass% or more and 20 mass% or less and Si:
Containing not less than 2.5 mass% and not more than 10 mass%, containing either one or two of Mn and P at 1 mass% or less;
And N are reduced to 100 ppm or less in total, and the balance is non-oriented electrical steel sheet composed of iron and unavoidable impurities, and the {111} inverse strength of at least the surface layer of the steel sheet is 3 or more. Non-oriented electrical steel sheet with excellent high-frequency magnetic characteristics and high space factor. (4) Cr: 1.5 mass% to 20 mass%, Si: 2.
Contains 5 mass% or more and 10 mass% or less and Al: 5 mass% or less, and each of one or two of Mn and P is 1 ma
ss% or less, C and N are reduced to 100 ppm or less in total, and the balance is iron and unavoidable impurities. A non-oriented electrical steel sheet having excellent high-frequency magnetic properties and a high space factor, having a strength of 3 or more. 5. The high frequency magnetic characteristic according to claim 1, wherein {111} inverse strength is 3 or more in a surface layer from the surface of the steel sheet to a depth of 1/5 of the thickness of the steel sheet. Non-oriented electrical steel sheet with excellent and high space factor.