JP2001279399A - Nonoriented silicon steel sheet excellent in high frequency magnetic property and having superior rolling manufacturability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonoriented silicon steel sheet for high frequency reactor, having particularly excellent magnetic properties in a frequency region of >=1 kHz. SOLUTION: This steel sheet has a composition which consists of, by mass, 2.5-10% Si, 1.5-20 mass % Cr and the balance Fe with inevitable impurities and in which the contents of C and N among the inevitable impurities are controlled to <=0.005 mass %, respectively, and also the content of at least either one of Ti and Nb is controlled to <=0.005 mass % is.

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 high-frequency magnetic properties, and an object of the present invention is to propose a steel sheet which can be rolled well when the steel sheet is manufactured by rolling. .

[0002]

2. Description of the Related Art Non-oriented electrical steel sheets are known as magnetic materials, and are frequently used mainly in various types of iron cores for commercial frequencies. However, when the operating frequency is higher than the commercial frequency, a normal non-oriented electrical steel sheet having an Si content of 3.5 wt% or less has a disadvantage of increasing iron loss. For example, in recent years, in electrical equipment, products adopting an inverter system have been increasing for higher efficiency and power saving, and a high-frequency reactor is used for such inverter equipment. Since these high-frequency reactors are used in the frequency range of 1 kHz or more, and even 10 kHz or more, the conventional, ordinary non-oriented electrical steel sheet is used because heat generation becomes large. It was difficult.

[0003] In order to improve high frequency iron loss, it is important to increase the specific resistance of steel, and generally, a method of increasing the content of Si or Al has been adopted. However, when the contents of Si and Al are increased, the workability is deteriorated, and it is difficult to produce the same by a usual method. Techniques for improving the manufacturability include a method of hot rolling under high temperature and low pressure described in JP-A-61-166923 for a high silicon steel sheet,
There is a method based on the diffusion and infiltration treatment of Si described in Japanese Patent Application Laid-Open No. 2-227078. However, both technologies have high S
i, It did not essentially improve the brittleness inherent in Al steel, and the products produced therefrom had extremely poor workability and were difficult to process into reactor core. 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, similar to conventional silicon steel sheets for high frequency applications,
Sufficient high-frequency magnetic properties have not been obtained for materials used for high frequencies above 1 kHz.

[0006]

As described above, in the conventional high-frequency steel sheet, the content of Si and Al is increased in order to increase the specific resistance. However, the material itself of such high Si and Al steel is essential. Due to the inherent brittleness, it has been difficult to perform rolling at the time of production without causing various adverse effects.

In view of the above, the present invention has
By improving the brittleness of Si steel by improving brittleness during manufacturing, it can be manufactured by the normal rolling method, and has both high specific resistance and good punching and bending workability. The aim is to propose a non-oriented electrical steel sheet that is optimal for steel.

[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 of the alloys. , Cr
Have been found to be effective when they coexist, and the results are disclosed in JP-A-11-343544. That is, in the Fe-Si alloy and the Fe-Si-Al alloy, it has been thought that toughness deteriorates as Cr is added. However, even when the content of Si is 3 mass% or more, C and N
It has been found that, by sufficiently reducing the content of Cr and then adding a certain amount or more of Cr, rather high toughness can be obtained.

[0009] However, even in the case of such a steel sheet containing Cr, edge cracks may occur at the side edges of the rolled material during rolling production, which has been a factor of reducing the product yield. Then, the inventors proceeded with further research and development, and found that there is an appropriate range for the Cr content in relation to the Si content and the Al content, leading to the present invention.

The present invention is based on the above findings. That is, the present invention provides a method for producing Si: 2.5 to 10 mass% and C
r: contains 1.5 to 20 mass%, and contains C and N in a total amount of 0.01 m
ass% or less, the balance being Fe and unavoidable impurities, and Si content [Si] (mass%) and Cr content [Cr]
(mass%), satisfying the following relationship: 0.8 × [Si] ≦ [Cr] ≦ 3.0 × [Si], and having a specific resistance of 60 μΩcm or more. Non-oriented electrical steel sheet with excellent magnetic properties.

Further, the present invention provides a method for manufacturing a semiconductor device comprising: Si: 2.5 to 10 mass%;
Cr: 1.5 to 20 mass% and Al: 5 mass% or less.
And N are reduced to 0.01 mass% or less in total, the balance being Fe and unavoidable impurities, and the Si content [Si] (mass
%), Cr content [Cr] (mass%) and Al content [Al] (mass%
%), The following equation: 0.8 × ([Si] + 0.7 × [Al]) ≦ [Cr] ≦ 3.0 × ([Si] +0.
7 × [Al]) and a non-oriented electrical steel sheet having a specific resistance of 60 μΩcm or more and excellent rollability and excellent high-frequency magnetic properties.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Regarding the magnetic properties of a non-oriented electrical steel sheet according to the present invention, a synergistic effect on the increase of the specific resistance can be obtained by adding Cr simultaneously with Si or Si and Al. As a result, iron loss, especially in the high frequency
Only, or can be significantly reduced as compared to an alloy system 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 intensive studies by the inventors, as in the present invention, C and N, which are impurity components, are sufficiently reduced, and Cr is contained in a range having a predetermined relationship between Si and Al. By doing so, it is possible to achieve both excellent rolling manufacturability and excellent high-frequency iron loss characteristics.

Hereinafter, the present invention will be described in detail. First,
The reason for limiting the component composition range in the non-oriented electrical steel sheet of the present invention will be described. Although Si alone increases the specific resistance of steel, it also increases the specific resistance significantly due to the synergistic effect with Cr, and is an effective component for reducing iron loss especially in the frequency range of 1 kHz or more. . When the Si content is less than 2.5 mass%, the magnetic flux density is not sacrificed even if Cr and Al are used together.
It is not possible to obtain a specific resistance of 60 μΩcm or more.
Good high frequency magnetic properties cannot be obtained. On the other hand, if it exceeds 10 mass%, even if Cr is contained, the toughness that can be normally rolled cannot be secured, so the range of the Si content is 2.5 mass%.
Not less than 10 mass%, preferably not less than 2.5 mass%,
mass% or less, more preferably 3.5 mass% or more, 5 mass
% Or less.

Cr is a basic alloying component for greatly improving the specific resistance of steel by a synergistic effect with Si and Al, reducing iron loss in a high frequency range, and further improving corrosion resistance. In addition, when the Si content is 3.5 mass% or more, or even when the Si content is 3 mass% or more and the Al content is more than 0.5 mass%, it is extremely effective for obtaining toughness to the extent that ordinary rolling is possible. Yes, from that point of view more than 2 mass% is required. When the amount of Si or Al is smaller than the above case,
Although the workability can be secured even if the Cr content is further reduced, the effect of improving the workability due to the Cr content is exhibited, and the specific resistance of steel is reduced
In order to attain μΩcm or more, 1.5 mass% or more of Cr is essential. On the other hand, if it exceeds 20 mass%, the effect of improving toughness is saturated and the cost is increased. Therefore, the content range of Cr is 1.5 mass% or more and 20 mass% or less, preferably,
2 mass% or more and 10 mass% or less, more preferably 3 mass%
% And 7 mass% or less. The Cr content is Si
It is necessary to set it in a predetermined range in relation to the amount and the amount of Al.

C and N are preferably reduced as much as possible in order to degrade the toughness of the non-oriented electrical steel sheet for high frequency use, and the allowable amounts thereof are limited to those of Cr, Si and Al according to the present invention. 100 mass ppm in total to ensure high toughness
It is necessary to keep it below. Preferably, C and N are each suppressed to 0.005 mass% or less. C and N are each 0.00
By reducing the content by 5 mass% or less, a cold-rolling property can be secured without adding a C-fixing element such as Ti or Nb, and a steel sheet having excellent magnetic properties from a low frequency range to a high frequency range can be obtained. More preferably, each is 0.003 mass% or less. More preferably, each is 0.0015 mass% or less.
In particular, in order to improve the rollability, the reduction of C is effective. In particular, by setting the C content to 0.003 mass% or less, the rollability is remarkably improved.

Although Ti and Nb are effective elements for improving the workability of Cr steel, in the steel of the present invention in which C and N are reduced, the effect of improving the workability of Ti and Nb is not particularly necessary. Without, low ~
It is preferable to reduce the magnetic properties in the middle frequency range, and it is preferable to set each of them to 0.005 mass% or less.
Although the amount of impurities other than C, N, Ti and Nb is not particularly limited, it is important to limit the amount to the following ranges in order to maintain good magnetic properties and workability, similarly to general silicon steel. S is 0.005 mass% or less, preferably 0.002 mass% or less, and more preferably 0.001 mass% or less. O is 0.00
5 mass% or less, preferably 0.003 mass% or less, more preferably 0.0015 mass% or less. V is 0.005% or less, preferably 0.002% or less, more preferably 0.0015% or less.
% Or less is good. In addition, it is preferable to reduce La, Mg, and the like as much as possible.

Al: 5 mass% or less Al is a component effective for significantly improving the specific resistance of steel by a synergistic effect with Cr and reducing iron loss in a high frequency range, like Si. In the present invention, Al can be contained as necessary. However, when the amount of Al exceeds 5 mass%, the cost is increased and, as in the present invention, the Si content is increased.
In a steel containing 2.5 mass% or more of steel, even if a large amount of Cr is contained, the toughness until normal rolling cannot be ensured, so the content of Al is set to 5 mass% or less. Although there is no particular limitation on the lower limit of Al, it may be contained in an amount of about 0.005 to 0.3 mass% for deoxidation and improvement of crystal grain growth.
Further, when Al is positively utilized for increasing the specific resistance, in a steel containing 2.5 mass% or more of Si as in the present invention, if Al is less than 0.5 mass%, the specific resistance is further increased. A sufficient effect cannot be obtained. Therefore, the Al content is preferably 0.05 mass% or more and 5 mass% or less, and more preferably 0.5 mass% or more and 3 mass% or less.

In the present invention, the Si content [Si] (mass
%) And the Cr content [Cr] (mass%) or the Si content [S
i] (mass%), Cr content [Cr] (mass%) and Al content [A
l] (mass%), the following equation: 0.8 × [Si] ≦ [Cr] ≦ 3.0 × [Si] 0.8 × ([Si] + 0.7 × [Al]) ≦ [Cr] ≦ 3.0 × ([Si] +0.
It is important to satisfy the relationship of 7 × [Al]). If Cr is included
Workability of Si steel and Al-containing steel can be improved, but Cr
Even in steel sheets that contain Cr, ear cracks may occur at the side edges of the rolled material during rolling production, and if Cr is added excessively compared to the amount of Si, the hysteresis loss increases, and on the contrary, high frequency magnetic characteristics There is a risk of causing deterioration. Therefore,
The Cr content needs to be contained in an appropriate amount with respect to the Si content and the Al content, and 0.8 × [Si] ≦ [Cr] ≦ 3.0 × [Si] or 0.8 × ([Si] + 0.7 × [ Al]) ≤ [Cr] ≤ 3.0 x ([Si]
By satisfying (+ 0.7 × [Al]), it is possible to achieve a high balance between rollability and high-frequency iron loss characteristics.

FIGS. 1 and 2 show the results of examining the rollability and high-frequency magnetic properties of steels having variously changed amounts of Cr, Si and Al. FIG. 1 relates to a steel not containing Al as a specific resistance improving component.
Relates to steel containing Al. This Figure 1,
From FIG. 2, it can be seen that when the above formula is satisfied, particularly, the rolling manufacturability and the high-frequency iron loss characteristics are excellent.

In the steel of the present invention, it is necessary to increase the specific resistance to achieve excellent high-frequency iron loss. If the specific resistance is lower than 60 μΩcm, a desired high-frequency iron loss cannot be obtained even if the sheet thickness is reduced. Therefore, in the present invention, the specific resistance is preferably set to 60 μΩcm or more.

In the steel sheet of the component according to the present invention, reducing the sheet thickness promotes the effect of improving the high-frequency iron loss characteristics. However, in order to obtain the effect of the reduction in thickness, the sheet thickness is set to 0.4 mm or less. It is effective to do. However, in order to make it thinner than 0.01 mm, not only the production cost becomes higher, but also extra care must be taken in handling the steel sheet, and the cost of product production becomes higher. mm or less is preferable. More preferably, it is 0.02 to 0.25 mm.

The non-oriented electrical steel sheet of the present invention can be manufactured by the following method. The raw material adjusted to the above-mentioned composition range is formed into a slab by continuous casting or ingot-bulking-rolling, or a thin slab is manufactured by using a thin slab continuous casting method. The obtained slab may be subjected to hot rolling after heating and holding, or may be subjected to hot rolling without heating while maintaining the sensible heat during continuous casting, as in the CC-DR method or the HCR method. it can.

In the subsequent hot rolling, the workability, that is, the rolling property in the next step of cold rolling or warm rolling can be improved by rolling as thinly as possible.
The thickness of the hot-rolled sheet for that is 3 mm or less, preferably 2.5 mm
Or less, more preferably 2.0 mm or less.

After the hot rolling, hot-rolled sheet annealing is performed as necessary. By performing the hot-rolled sheet annealing, the texture of the rolled material is improved, which advantageously works to improve the iron loss characteristics. The hot-rolled sheet annealing conditions include, for example, a temperature of 700 to 1100
C. for 1 second to 2 hours.

After the hot rolling or, if necessary, after the annealing of the hot-rolled sheet, the hot-rolled scale is removed by pickling or shot blasting, and then cold rolling or warm rolling is performed.
Since the toughness of the hot-rolled sheet is improved by adjusting the material components and the purity, the hot-rolled sheet can be further rolled hot or cold to obtain a thin sheet having a thickness of 0.4 mm or less. Further, in the steel of the present invention, since the Cr content is adjusted so as to be in a predetermined range in relation to the Si content and the Al content, defects such as edge cracks occur during cold rolling or warm rolling. Nothing.

The above-described cold rolling and warm rolling are performed by one rolling or two or more rollings including intermediate annealing.
Performing the intermediate annealing has an advantageous effect on the improvement of the magnetic properties through the improvement of the texture of the rolled material. Further, the workability of the cold rolling and the warm rolling can be improved. The condition of the intermediate annealing is, for example, at a temperature of 600 to 1100 ° C for a time of 1 second to 10
Minute range. Here, the temperature of the warm rolling is preferably set as low as possible from the viewpoint of cost, and is preferably set to a temperature of about 300 ° C. or less.

After cold rolling and warm rolling, finish annealing is performed, and an insulating coating is further formed to obtain a product. The conditions for the finish annealing and the conditions for forming the insulating coating may be the same as those commonly used for ordinary electromagnetic steel sheets and electromagnetic stainless steel sheets. Further adjusting the material components and / or
Alternatively, by controlling the temperature conditions of the finish annealing, the average crystal grain size can be reduced to 100 μm or less.

[0029]

EXAMPLE A steel containing the composition shown in Table 1 and the balance consisting of Fe and unavoidable impurities was melted and made into a slab by continuous casting. Insert into heating furnace for heating, and plate thickness by hot rolling
A 2.0 mm hot rolled sheet was used. After removing the scale of these hot-rolled sheets, cold rolling was performed to a sheet thickness of 0.35 mm, and the temperature was 800 ° C.
For 10 seconds in a mixed atmosphere of hydrogen and nitrogen. These steel sheets were further cold-rolled to a thickness of 0.1 mm, and subjected to a final annealing at 820 ° C. for 10 seconds in a hydrogen / nitrogen mixed atmosphere to provide an insulating coating. The obtained product was cut into Epstein samples, and the magnetism was measured according to JIS C 2550 (1975). The results are shown in Table 2 together with the rollability during rolling. The rollability was evaluated as ◎ for good rollability, Δ for cracks at one or more places per 5 m, and x for unbreakable rolls.

[0030]

[Table 1]

[0031]

[Table 2]

From the results shown in Table 2, the relationship between the amount of Cr and the amounts of Si and Al is 0.8 × [Si] ≦ [Cr] ≦ 3.0 × [Si] or
0.8 x ([Si] + 0.7 x [Al]) ≤ [Cr] ≤ 3.0 x ([Si] + 0.
It can be seen that the example satisfying 7 × [Al]) has both excellent high-frequency magnetic properties and rollability.

[0033]

As described above, the non-oriented electrical steel sheet of the present invention has both excellent high-frequency magnetic properties and rollability, and can easily and stably produce excellent products. The value is great.

[Brief description of the drawings]

FIG. 1 is a graph showing the effect of the relationship between the amount of Cr and the amount of Si on rolling manufacturability.

FIG. 2 is a graph showing the effect of the relationship between the Cr content, the Si content, and the Al content on rolling manufacturability.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuka Komori 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) NN01 NN15

Claims (2)

[Claims] (1) Si: 2.5 to 10% by mass and Cr: 1.5 to 20% by mass
%, The total amount of C and N is reduced to 0.01 mass% or less, the balance is composed of Fe and unavoidable impurities, and the Si content [Si] (mass%) and the Cr content [Cr] ( mass%), which satisfies the following relationship: 0.8 × [Si] ≤ [Cr] ≤ 3.0 × [Si] and has a specific resistance of 60 µΩcm or more. Non-oriented electrical steel sheet with excellent properties. 2. Si: 2.5 to 10% by mass, Cr: 1.5 to 20% by mass
And Al: contains 5 mass% or less, and contains C and N in a total amount of 0.1%.
01 mass% or less, the balance is composed of Fe and unavoidable impurities, and the Si content [Si] (mass%) and the Cr content [Cr]
(mass%) and the Al content [Al] (mass%), the following equation: 0.8 × ([Si] + 0.7 × [Al]) ≦ [Cr] ≦ 3.0 × ([Si] +0.
A non-oriented electrical steel sheet that satisfies the relationship of 7 × [Al]) and has a specific resistance of 60 μΩcm or more and has good rollability and excellent high-frequency magnetic properties.