JP2002097558A - Non-oriented electrical steel sheet with excellent high frequency magnetic properties and punching workability - Google Patents

Abstract

(57) [Abstract] [Objective] To propose a method of improving the punching property to increase the space factor of non-oriented electrical steel sheets that have obtained excellent high-frequency magnetic properties by a Cr-containing component system. . [Constitution] Cr: 1.5 mass% or more and 20 mass% or less, Si: 2.
5 mass% or more and 10 mass% or less and S: 0.005 mass% or more and 0.
Containing not more than 03 mass%, reducing Cu to not more than 0.02 mass% and reducing C and N to 100 ppm or less in total.
Ingredient composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-oriented electrical steel sheet having excellent magnetic properties, and more particularly to a non-oriented electrical steel sheet having excellent magnetic properties when used at a frequency higher than the commercial frequency, and further having excellent punching workability. The present invention relates to a magnetic steel sheet.

[0002]

2. Description of the Related Art An Fe-Si alloy is known as a material having excellent soft magnetic properties, and is frequently used mainly as an electromagnetic steel sheet having a Si content of 3.5 mass% or less, mainly in various commercial frequency iron cores. However, when the operating frequency is higher than the commercial frequency, there is a disadvantage that the iron loss is increased in the magnetic steel sheet having the Si content of 3.5 mass% or less. Therefore, in order to improve the iron loss characteristics in a frequency range higher than the commercial frequency, a material having higher electric resistance is required.

[0003] Here, if the amount of Si in the steel is increased, the electric resistance increases, which is advantageous in reducing the iron loss in the high frequency range as described above. However, on the other hand, when the amount of Si is 3.5
If it exceeds mass%, the alloy becomes extremely hard and brittle, and the workability is inferior, so that production and processing by rolling become difficult. In particular, when the Si content exceeds 5.0 mass%, not only cold working but also warm working becomes impossible.

[0004] The workability of this high Si steel is improved to 6.5 mass%
As a technique for producing a steel sheet industrially even if it contains a certain amount of Si, a method by hot rolling under low temperature and high pressure disclosed in Japanese Patent Application Laid-Open No.
A method based on the diffusion and infiltration treatment of Si disclosed in Japanese Patent Laid-Open No. 2-227078 is typical.

[0005] However, the former Japanese Patent Application Laid-Open No. 61-166923.
The technology disclosed in the above publication requires fine adjustment of the rolling structure to apparently improve the brittleness of the alloy, and strict control is performed in the manufacturing process, so that it is possible to produce industrially stable products. Is estimated to be difficult. On the other hand, the latter
In the technique disclosed in Japanese Patent No. 227078, a special diffusion infiltration method is used, so that it is considered to be extremely disadvantageous in terms of cost when performing industrial production. Moreover, although there is a limit to further increasing the electric resistance in order to obtain good high-frequency magnetic characteristics, even if the amount of Si is increased by these methods,
It has to stay at the level of at most 80μΩcm. In particular, when the amount of Si is 3.5 mass% or less, which can be produced by a normal industrial rolling method, a specific resistance of only about 50 μΩcm was obtained. In addition, these Fe-Si alloys also have a problem of poor corrosion resistance in applications such as iron cores.

Further, Al has the effect of increasing the electric resistance in the same manner as Si from the viewpoint of magnetic properties, and does not deteriorate the workability as much as Si. It is known that the properties are improved. Al is Si
Although it is more expensive and has weaknesses such as a large decrease in magnetic flux density, for example, steel with a composition of Si: 3 mass% and Al: 0.7 mass% is more workable than steel with a composition of Si: 3.7 mass%. , Good cold rollability and almost the same magnetic properties.

However, in steel of Si: 3 mass% or more,
If the total amount of Si and Al is 4 mass% or more, cold rolling becomes impossible, and if the total amount of Si and Al exceeds 6 mass%, warm rolling becomes difficult. Moreover, also in this case, after all, only a specific resistance of less than 60 μΩcm was obtained industrially.

In any case, rather than simply reducing the iron loss in the high frequency range by simply increasing Si or Al, the alloy according to the new component system having essentially improved workability has a better magnetic property over the higher frequency range. In addition, it is desirable to ensure workability and to further satisfy corrosion resistance and low cost.

As means for improving the corrosion resistance of Fe-Si alloys, Japanese Patent Application Laid-Open Nos. 52-24117 and 61-27352 disclose the addition of a certain amount of Cr.
None of these alloys had magnetic properties exceeding conventional levels.

Therefore, the present inventors have proposed Fe-Si alloys and Fe-Si alloys.
-After researching and developing Al alloys to achieve both high specific resistance and good workability of the alloys, we obtained the knowledge that coexistence of Cr is effective, and It has been disclosed in JP-A-11-343544. That is,
Until now, Fe-Si alloys and Fe-Si-Al alloys
It has been thought that the toughness deteriorates with the addition of
Even if the content is 3 mass% or more, it is possible to obtain a rather high toughness by sufficiently reducing the content of C and N and then adding a certain amount or more of Cr.
It has been found that the iron loss can be reduced in a high frequency range due to an increase in electric resistance by being contained together with Al and Al. In particular, if the workability at the time of manufacturing is improved, it is possible to make the steel sheet thinner, so that further improvement in high-frequency magnetic characteristics can be expected.

[0011]

By the way, such a material having excellent high-frequency magnetic characteristics can be further reduced in eddy current loss at a high frequency by reducing the plate thickness, and the iron loss can be reduced. It is essentially advantageous that the thickness is sufficiently smaller than 0.30 mm, mainly 0.20 mm or 0.10 mm, which is sufficiently thinner than the usual non-oriented electrical steel sheets of 0.50 mm or 0.35 mm.

However, in this case, despite the fact that the high frequency magnetic properties of the material are sufficiently low, the punched material is laminated and actually used as a transformer or high frequency reactor core. Iron loss sometimes did not reach the expected level from the material. The present inventors examined the cause of the problem, and found that the cause was a problem in that the space factor when the layers were arranged was low, and the main cause was the shape after punching.

Accordingly, the present invention proposes a method for improving the punching property of a non-oriented electrical steel sheet having excellent high-frequency magnetic properties by using a Cr-containing component system in order to increase the space factor. The purpose is to:

[0014]

The inventors of the present invention have found that the reason why the punching property of a steel sheet is hindered is that the burrs of the steel sheet caused by die wear during punching are large. To control the amount of S, in addition to the addition of a small amount of S, iron ore as the main raw material, and other
(Si, FeCr, chromium ore, metallic chromium, etc.), which are found as extremely advantageous to reduce Cu, which is inevitably mixed because they are contained as impurities, and completed the present invention. .

That is, the gist of the present invention is as follows. (1) Cr: 1.5 mass% or more and 20 mass% or less, Si: 2.5 mass%
10 mass% or less and S: 0.005 mass% or more and 0.03 mass%
In addition to the following, Cu is reduced to 0.02 mass% or less, C and N are reduced to 100 ppm or less in total, and the balance is composed of iron and unavoidable impurities.
A non-oriented electrical steel sheet with excellent high-frequency magnetic properties and a high space factor, characterized by being Ωcm or more.

(2) Cr: 1.5 mass% to 20 mass%, S
i: 2.5 mass% or more and 10 mass% or less, S: 0.005 mass% or more and 0.03 mass% or less, and Al: 5 mass% or less.
A high frequency magnetic material characterized in that C and N are reduced to not more than 100 ppm in total, while the balance is composed of iron and unavoidable impurities, and the specific resistance is not less than 60 μΩcm. Non-oriented electrical steel sheet with excellent properties and high space factor.

(3) Cr: 1.5 mass% or more and 20 mass% or less, S
i: 2.5 mass% or more and 10 mass% or less and S: 0.005 mass%
Not less than 0.03 mass%, containing one or two of Mn and P at 1 mass% or less, and further containing Cu
A high frequency magnetic material characterized in that C and N are reduced to not more than 100 ppm in total, while the balance is composed of iron and unavoidable impurities, and the specific resistance is not less than 60 μΩcm. Non-oriented electrical steel sheet with excellent properties and high space factor.

(4) Cr: 1.5 mass% or more and 20 mass% or less, S
i: 2.5 mass% or more and 10 mass% or less, S: 0.005 mass% or more and 0.03 mass% or less, and Al: 5 mass% or less, containing one or two of Mn and P at 1 mass% or less. In addition, Cu is reduced to 0.02 mass% or less, C and N are reduced to 100 ppm or less in total, and the balance is composed of iron and unavoidable impurities.
A non-oriented electrical steel sheet with excellent high-frequency magnetic properties and a high space factor, characterized by being Ωcm or more.

(5) The non-oriented electrical steel sheet according to any one of the above (1) to (4), characterized in that the steel sheet has a thickness of 0.01 to 0.4 mm, and is excellent in high-frequency magnetic characteristics and high in space factor. .

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the results of an experiment leading to the non-oriented electrical steel sheet of the present invention will be described in detail. More specifically, a steel ingot (thickness: 220 mm 2) adjusted to have various component compositions in which the amount of S and the amount of Cu shown in Table 1 were variously changed was heated to 1200 ° C., and then hot-rolled to obtain a sheet thickness: 2.0 mm Hot rolled sheet. This hot-rolled sheet was subjected to hot-rolled sheet annealing at 850 ° C. for 1 hour, cold-rolled to form a cold-rolled sheet having a thickness of 0.20 mm, and then subjected to finish annealing at 800 ° C. for 30 seconds. . In the thus obtained sample, 20 parts by weight of Al (equivalent to Al metal), 30 parts by weight of H ₃ PO _4, 35 parts by weight of ethylene glycol and 35 parts by weight of acryl / styrene / epoxy resin with respect to 100 parts by weight of CrO ₃ : A processing solution containing 40 parts by weight was applied to a basis weight of 1.0 g / m ^2.
The coating was applied and baked at an ultimate plate temperature of 250 ° C. to form an insulating film. An oilless punching test (punching diameter: 10 mmφ) was performed on the magnetic steel sheet with the insulating coating, and the burr height of the steel sheet at the time of punching was measured by observing the punching cross section.

[0021]

[Table 1]

As shown in FIG. 1 for each steel type, the measurement results were obtained for steel type B containing a small amount of S and having a large amount of Cu.
Similarly, in steel type A containing a small amount of S and reducing the amount of Cu,
It can be seen that the burr height was reduced and the punching workability was significantly improved.

On the other hand, steel type C having a low S content and reduced Cu
Further, it can be seen that in the case of steel type C having the same S content and large Cu content, no remarkable effect was obtained compared to steel type A. That is, it became clear that the punching workability was improved due to the synergistic effect of the addition of a small amount of S and the reduction of Cu in the Fe-Cr-Si alloy.

The reason why the punching workability is improved by the synergistic effect of the addition of a small amount of S and the reduction of Cu in the Fe—Cr—Si alloy is not yet clear. Can be considered.

Generally, S in steel is mainly Mn
It is known to exist as a sulfide such as S.
Since such a sulfide deteriorates magnetic properties, it is preferable to reduce the sulfide as much as possible. However, from the viewpoint of punching workability, when such precipitates are present,
The precipitate becomes a starting point of destruction at the time of punching, and punching without plastic deformation becomes possible. That is, it is effective to add S in such a small amount as not to deteriorate the magnetic properties, in order to improve the punching workability.

However, when Cu is present in the steel, sulfide with Cu precipitates, and since this precipitate is very fine, it is considered that it does not act as a fracture starting point. It is important to effectively reduce the effect of adding a small amount of S by reducing the amount.

By the way, JP-A-8-246052 discloses that
A technique has been disclosed in which strain during punching is reduced by coarsely depositing MnS. This technology uses MnS by adding S and applying an appropriate manufacturing process.
To improve the punchability by coarsening
In a -Cr-Si alloy, the effect cannot be obtained only by adding S as described above, and it is essential to reduce Cu. Therefore, it is difficult to improve the punchability by simply applying this technique to an Fe—Cr—Si based alloy.

Hereinafter, the reasons for limiting each component range of the non-oriented electrical steel sheet of the present invention will be described. 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 toughness is saturated and the cost is increased. Therefore, the content of Cr is specified to be 1.5 mass% or more and 20 mass% or less, 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: 5 mass% or less Al, like Si, is a component that is effective for significantly improving electric resistance by a 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 need to be particularly limited.
When about 5 to 0.3 mass% is contained, and when Al is used positively for increasing the electric resistance, it is preferable to contain Al in a range of 0.5 mass% or more. Therefore, Al is 0.
The content is preferably 005 mass% or more, more preferably 0.5 mass% or more and 3 mass% or less.

It is important to add a small amount of S in order to improve the punching workability. That is, if the content of S is less than 0.005 mass%, the effect of improving the punching workability is small, while if the content exceeds 0.03 mass%, the hot workability is significantly deteriorated. mass% and 0.03 mass%.

Cu must be reduced to 0.02 mass% or less in order to obtain the effect of adding a small amount of S for improving the punching workability. Further, by reducing the content to 0.01 mass% or less, it is advantageous in improving the punching workability.

C and N: 100 ppm or less in total amount C and N must be reduced as much as possible in order to deteriorate 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, the total amount of C and N is 60 ppm or less, more preferably 30 ppm.
ppm or less, and further, the C content is 30 ppm or less, more preferably 10 ppm or less, and the N content is 80 ppm or less, more preferably 20 ppm or less.
It should be less than ppm.

Although the amount of impurities other than C and N is not particularly limited, O is 50 ppm or less, preferably 30 pp.
m or less, more preferably 15 ppm or less, or impurities C
It is recommended to regulate the total amount of + N + O to 100 ppm or less, preferably 50 ppm or less.

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.
Mo or W of 5 mass% or less improves corrosion resistance. La, V or Nb of 1 mass% or less, Ti, Y or Zr of 0.1 mass% or less, 0.1 mas
B of s% or less has 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. 0.1 mass% or less of Sb and Sn
Is effective in improving the texture and eventually reducing iron loss.

Incidentally, the non-oriented electrical steel sheet of the present invention can be manufactured by the following method. That is, the alloy material adjusted to the above-described component composition range is made into a slab by continuous casting or ingot-bulking rolling. In addition, a thin slab can be manufactured by using a thin slab continuous casting method. The obtained slab is subjected to hot rolling after heating and holding, or continuous casting such as a method of directly feeding and rolling after continuous casting (CC-DR method) or a method of keeping heat after continuous casting (HCR method). While maintaining the sensible heat at the time, it is subjected to hot rolling without heating.

Next, in hot rolling, by rolling as thin as possible, workability in the next step of cold rolling or warm rolling, that is, 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 form a thin sheet having a thickness of 0.4 mm or less. It is well known that reducing the thickness generally reduces eddy current loss advantageously, especially at high frequencies, and reduces iron loss. However, materials having high electric resistance have poor rollability so far, and the thickness has been reduced to only about 0.5 mm by a normal 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. 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 0.01 mm,
Due to industrial unreasonability, the range of plate thickness is 0.01 to 0.40 mm,
Preferably, it is defined as 0.03 to 0.30 mm.

In such rolling for thickness reduction,
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.

[0042]

EXAMPLE A steel slab having the composition shown in Table 1 (220 mm
Was reheated to 1100 ° C and hot-rolled to a sheet thickness of 2.3 mm. After the surface of the hot-rolled sheet was treated by shot blasting, it was preheated to 200 ° C without intermediate annealing to 0.20 mm.
And warm rolling to 0.10 mm. Then, at 800 ° C
After annealing for 60 seconds at 100 parts by weight of CrO ₃ , A1: 20 parts by weight (in terms of Al metal), H ₃ PO ₄ : 30 parts by weight,
A treatment liquid containing 35 parts by weight of ethylene glycol and 40 parts by weight of acryl / styrene / epoxy resin was applied and baked at a basis weight of 1.0 g / m ² and an ultimate plate temperature of 250 ° C. to form an insulating film.

From the product plate thus obtained, a ring-shaped test piece having an outer diameter of 30 mm and an inner diameter of 20 mm was cut out, and an iron loss value at a frequency of 10 kHz and a magnetic flux density of 0.1 T was measured with a BH analyzer. Furthermore, a test piece having a width of 30 mm and a length of 280 mm was cut out from a product plate, and the specific resistance was measured by a four-terminal method.

The burr height was measured by performing an oilless punching test (punching diameter: 10 mmφ) and observing the 500,000th punching cross section. As shown in the above measurement results for each steel type in Table 3, it can be seen that the electromagnetic steel sheet according to the present invention is excellent in both high-frequency magnetic properties and punching workability.

[0045]

[Table 2]

[0046]

[Table 3]

[0047]

According to the present invention, the conventional Si content of 6.5 mass
% Of high-frequency magnetic properties equivalent to or higher than that of Fe-Si alloys and Fe-Al alloys in addition to good workability. Can be advantageously improved.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the number of times of punching for various steel types and the burr height of a steel plate.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaaki Kono 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Pref. Chome (without address) Kawasaki Steel Corporation Mizushima Works (72) Inventor Masaki Kono 1-chome, Mizushima Kawasaki-dori, Kurashiki-shi, Okayama Prefecture (without address) Kawasaki Steel Corporation Mizushima Works F-term (reference) CA04 NN01 NN06 NN15

Claims (5)

[Claims] (1) Cr: 1.5 mass% to 20 mass%, Si: 2.5 mass% to 10 mass%, and S: 0.005 mass% to 0.03 mass%. Cu is reduced to 0.02 mass% or less. C
And N are reduced to 100 ppm or less in total, and the balance is composed of iron and unavoidable impurities, and the specific resistance is 60 μΩcm or more. Grain-oriented electrical steel sheets. (2) Cr: 1.5 mass% to 20 mass%, Si: 2.5 mass% to 10 mass%, S: 0.005 mass% to 0.03 mass%, and Al: 5 mass% or less, Cu: 0.02 mass% % Or less, and C
And N are reduced to 100 ppm or less in total, and the balance is composed of iron and unavoidable impurities, and the specific resistance is 60 μΩcm or more. Grain-oriented electrical steel sheets. 3. An alloy containing Cr: 1.5 mass% to 20 mass%, Si: 2.5 mass% to 10 mass% and S: 0.005 mass% to 0.03 mass%, and one or two of Mn and P Each contains 1 mass% or less, further reduces Cu to 0.02 mass% or less, reduces C and N to a total amount of 100 ppm or less, and the remainder is composed of iron and inevitable impurities.
A non-oriented electrical steel sheet having excellent high-frequency magnetic properties and a high space factor, having a specific resistance of 60 μΩcm or more. 4. Cr: 1.5 mass% to 20 mass%, Si: 2.5 mass% to 10 mass%, S: 0.005 mass% to 0.03 mass%, and Al: 5 mass% or less. One or two of them at 1 mass% or less, further reducing Cu to 0.02 mass% or less, reducing C and N to 100 ppm or less in total, and the balance of iron and unavoidable impurities. Ingredient composition,
A non-oriented electrical steel sheet having excellent high-frequency magnetic properties and a high space factor, having a specific resistance of 60 μΩcm or more. 5. The method according to claim 1, wherein
Non-oriented electrical steel sheet with excellent high-frequency magnetic properties and high space factor, characterized in that the thickness of the steel sheet is 0.01 to 0.4 mm.