JP2001303216A - Silicon steel sheet excellent in high frequency magnetic property and its producing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicon steel sheet excellent in high frequency magnetic properties while avoiding the increase of cost in consideration of steel making, hot rolling, cold rolling and, further, steel sheet working and to provide its producing method. SOLUTION: This steel sheet has a composition containing >0.015 to 0.08% C, <=0.8% Si, 0.05 to 0.80% Mn and <=0.06% P, and in which, in the case ferrite grain size prescribed in JISG0552 is defined as (g), the relation in the inequality (1) of 6.77[%C]+15.0[%Si]+4.84[%Mn]+24.2[%P]+4.36>=g... (1) is satisfied, and as to its production, in hot rolling, coiling is performed at >=600 deg.C in such a manner that finishing temperature is controlled to the Ar3 transformation point or below, and, in finish annealing, recrystallization treatment is performed at 650 to 900 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic steel sheet used for a motor or the like, and more particularly to an electromagnetic steel sheet having excellent high-frequency magnetic characteristics and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, motors have been required to have high efficiency from the viewpoint of energy saving, and downsizing of motors has been demanded in order to reduce the weight and size of equipment. In order to reduce the size of the motor, it is necessary to improve the high-frequency magnetic properties of the steel sheet used for the iron core material of the motor.

[0003] Conventionally, to improve the high-frequency magnetic properties of steel sheets, S
Although the means of increasing the i content was common,
This measure has led to an increase in the cost of the steel sheet. For this reason, there is a demand for a method of improving high-frequency magnetic characteristics at a low cost without increasing the Si content. In the present invention, “high frequency” is a frequency higher than a commercial frequency and is a frequency used for a normal motor.
For example, a frequency of 1 kHz or more is a frequency in a range for a general-purpose small motor which has been particularly noticed recently.

[0004] There is an invention disclosed in JP-A-8-295935 as a method for producing a non-oriented electrical steel sheet having excellent magnetic properties. The present invention raises the iron loss by raising the finish rolling end temperature of hot rolling to a high temperature and gradually cooling down to winding as much as possible, and gradually cooling as much as possible in continuous annealing after cold rolling, A technique for improving magnetic flux density by increasing the crystal grain size is disclosed.

Japanese Patent Application Laid-Open No. 58-171527 discloses a method of manufacturing a low-grade electromagnetic steel sheet which can be manufactured at low cost. The present invention uses a material of C: 0.005 to 0.08% and raises the finish rolling end temperature in hot rolling to 640 to 86.
At 0 ° C., the magnetic flux density is improved and the N content is reduced to 80%.
It discloses a technique of improving iron loss by suppressing the iron loss to less than ppm.

On the other hand, Japanese Patent Application Laid-Open No. H10-140242 discloses a method of manufacturing a low-grade electromagnetic steel sheet in which C is set to 0.01% or more in order to reduce the steelmaking cost and manufacture the steel sheet at low cost. The present invention improves the ring magnetic properties by setting the hot rolling finish temperature in the γ region above the Ar ₃ transformation point at the C content at this level, and regulates the cooling rate after finish annealing to thereby achieve magnetic aging. It discloses that deterioration is suppressed.

Further, in order to reduce the processing cost of steel sheets,
There is a need for improved punchability. As a means for improving the punching property of the electromagnetic steel sheet, a method of increasing the hardness of the steel sheet, a method of dispersing precipitates such as MnS in the steel sheet, a method of providing a coating that improves the punching property, and the like are taken. I have.

[0008] Of these, in the invention of Japanese Patent Application Laid-Open No. 4-323320, it is proposed that the hardness of a steel sheet be Hv 135 or more in order to ensure punching property, caulking property and the like. As described above, in the electromagnetic steel sheet, many inventions pursuing excellent magnetic properties or inexpensiveness have been published as prior arts, but each has its own advantages and disadvantages, and both of the excellent magnetic properties and inexpensiveness can be sufficiently realized. No way to satisfy has been invented.

[0009]

With respect to the improvement of high-frequency magnetic characteristics, there is a problem that when a steel sheet is magnetized at a high frequency, the eddy current loss sharply increases and the iron loss becomes extremely large.

On the other hand, in conventional high-priced electrical steel sheets, an increase in the specific resistance due to the addition of high Si and high Al and a reduction in the eddy current loss in a high frequency region by reducing the thickness of the steel sheets have been attempted. .

However, as is generally known, high Si
Addition, high Al addition increases the cost of steel refining,
Reducing the plate thickness increases the cost of manufacturing a steel plate, increasing the number of man-hours for punching, assembling a motor, etc., and increasing the price.

The iron loss improved by the method disclosed in JP-A-8-295935 is only a hysteresis loss, and no consideration is given to eddy current loss which is important when used at high frequencies. The cost increases due to the slow cooling of the sheet or cold rolled sheet.

In the invention of JP-A-58-171527, no consideration is given to high-frequency iron loss, so that the specific resistance of the steel sheet is too low, and the steel sheet has excellent magnetic properties at high frequencies as required today. Steel sheet cannot be obtained.

In the invention of Japanese Patent Application Laid-Open No. H10-140242, the upper limit of 0.3% of S is set as a range not disadvantageous economically.
Although the addition of i was recognized, the relationship with the required amount of Si added from the high-frequency magnetic properties was not clear, and the result was that the excessive addition of Si resulted in an increase in the cost of steel sheet production, and it had to be said to be incomplete. Was.

According to Japanese Patent Application Laid-Open No. Hei 4-323320, when the steel sheet hardness presented is such that a cutting step is included in the iron core manufacturing process, the life of the cutting tool becomes a problem. From a viewpoint, it was contrary to the purpose of manufacturing at low cost.

It is an object of the present invention to provide an electromagnetic steel sheet having improved magnetic properties in a high frequency range while avoiding a rise in cost in consideration of steel making, hot rolling, cold rolling, and steel sheet processing, and a method of manufacturing the same. It is to be.

[0017]

Means for Solving the Problems The present inventors have conducted various experiments and found that an electrical steel sheet having excellent high-frequency magnetic characteristics can be obtained by maintaining a certain relationship between the component value of the steel sheet and the ferrite grain size. The present invention has been found.

Here, the present invention is as follows (a) to (f). (A) In mass%, C: more than 0.015%, 0.08% or less Si: 0.8% or less Mn: 0.05% or more, 0.80% or less P: 0.06% or less When the ferrite crystal grain size specified in JIS G0552 is g, 6.77 [% C] +15.0 [% Si] +4.84 [% Mn] +24.2 [% P] + 4.36 ≧ g ……………… (1) An electromagnetic steel sheet excellent in high-frequency magnetic properties, characterized by satisfying the relationship of the above formula (1). (B) N and S as unavoidable impurities are respectively represented by mass%
The electromagnetic steel sheet according to the above (a), wherein N is limited to 0.007% or less and S: 0.010% or less. (C) Al: 0.05% or less and B: 0.
The electromagnetic steel sheet according to the above (a) or (b), further containing 0003 to 0.005%. (D) The electromagnetic steel sheet according to any one of the above (a) to (c), wherein the sheet thickness is 0.30 mm or more and 1.8 mm or less. (E) In mass%, C: more than 0.015%, 0.08% or less Si: 0.8% or less Mn: 0.05% or more, 0.80% or less P: 0.06% or less And, if necessary, Al: 0.05% or less and / or
Or B: When hot rolling, pickling, cold rolling, and then finish annealing are performed on a slab further containing 0.0003 to 0.005%, the finishing temperature is set to the Ar ₃ transformation point or lower in hot rolling. Winding is performed at 600 ° C or higher, and refining treatment at 650 ° C or higher and 900 ° C or lower is performed in finish annealing to obtain the ferrite crystal grain size specified in JIS G0552 as g, and 6.77 [% C] +15.0 [% Si] +4.84 [% Mn] +24.2 [% P] + 4.36 ≧ g (1) A method for producing an electrical steel sheet excellent in high-frequency magnetic characteristics, characterized by satisfying the relationship (1). (F) Following the finish annealing defined in (e) above, the lower limit is 3
A method for producing an electromagnetic steel sheet, comprising performing an overaging treatment at 00 ° C, an upper limit of 500 ° C, and a treatment time of 150 seconds or more. (G) A method for producing a magnetic steel sheet, comprising subjecting a cold-rolled steel sheet after the finish annealing specified in (e) to temper rolling at an elongation of 2% or less.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the reason why the addition amount of each alloy element is specified as described above in the present invention will be explained. In this specification, "%" means "mass%" unless otherwise specified.
It is.

C is more than 0.015% and 0.08% or less. A general magnetic steel sheet uses a so-called ultra-low carbon steel having a C of 0.01% or less to secure magnetic properties. However, in an application where economy is prioritized, the C is 0.015%. % Or less special production steps such as an increase in steelmaking cost or decarburization annealing are preferred, and it is difficult to obtain the desired inexpensive material by these methods. Therefore, in the present invention, the lower limit of C is 0.015
%.

When the C content increases, the amount of carbide precipitation increases, and the hysteresis loss increases. An increase in the content of C causes an increase in the amount of carbide precipitation and an increase in the amount of solid solution C. As a result, the crystal grains become finer, and the hysteresis loss further increases. For this reason, C has been considered to be as low as possible.

However, since an increase in the C content also has the effect of increasing the specific resistance of the base material, it is preferable to use high-frequency iron loss, which is mainly composed of eddy current loss, to obtain good magnetic characteristics. Steel sheet can be obtained.

From the viewpoint of simply increasing the specific resistance of the base material, it is preferable that C is present in a solid solution state. However, if solid solution C remains in the product, it causes a problem of magnetic aging. In the present invention, C is precipitated as carbide as much as possible.

Further, this carbide serves as a starting point of a crack at the time of punching, and in order to improve the punchability by facilitating the propagation of the crack, C is also precipitated as a carbide as much as possible from this point. Better.

Therefore, it is desirable that C exceeds 0.015%. This makes it possible to obtain a steel sheet having excellent punching properties at low cost without taking other measures to improve the punching properties that would lead to an increase in cost.

As described above, the increase in the content of C can be positively utilized in obtaining a steel plate which is inexpensive and has excellent high-frequency iron loss.
However, if C exceeds 0.08%, adverse effects due to an increase in hysteresis loss due to the refinement of crystal grains are large.
The upper limit is set to 0.08%.

Si is an element effective in reducing high-frequency iron loss, and can be added up to 0.8% as necessary depending on the required high-frequency iron loss. Therefore, when Si is added, the upper limit is set to 0.8%. In order to keep the cost lower, the content is preferably set to 0.5% or less.

P is added for increasing the specific resistance of the base material or adjusting the hardness of the steel sheet. However, if the amount is too large, if the manufacturing process involves cutting, the life of the cutting die is deteriorated.
6% or less.

[0029] Mn contributes to increase the specific resistance of the base material and reduce high-frequency iron loss, but a large amount of Mn increases the hardness more than necessary and causes a problem in the life of the cutting die. Is not significant, the upper limit is set to 0.80%.

Further, in order to obtain a steel sheet excellent in economical efficiency, it is better to add a small amount of Mn which is an expensive alloy element.
It is desirable that the content be 0.5% or less. On the other hand, since Mn has a role of preventing hot embrittlement of steel during hot rolling by S,
It is desirable to add 0.05% or more.

S is an unavoidable impurity, and fine MnS
Since precipitates are formed to deteriorate the electromagnetic characteristics, it is desirable to reduce as much as possible. However, since the reduction leads to an increase in cost, a range in which the adverse effect of S is not remarkable is 0.01%.
It is preferably set to 0% or less. More preferably 0.0
08% or less.

Al is an impurity element which may be unavoidably mixed in from the beginning, but may be added for the purpose of deoxidation if necessary. Although Al also has the effect of increasing the specific resistance of the base material, the addition of Al, which is an expensive alloy element, causes an unnecessary increase in cost. Al (acid soluble A
l) It is preferable to add as an amount of 0.05%.

However, when Al is added, if it is precipitated as fine AlN, the magnetic properties are deteriorated. Therefore, it is desirable to add 0.0003 to 0.005% of B at the same time.

When the B content is less than 0.0003%, the effect of nitride coarsening by B is insufficient and the magnetic properties are poor.
If the content exceeds 005%, the magnetic properties may be degraded due to excess B.
%, 0.005%.

N is an unavoidable impurity, and the upper limit is made 0.007% in order to prevent harm caused by an increase in the amount of nitride precipitation.
It is preferable to make it difficult to precipitate. In addition, other unavoidable impurity elements (Cu, Ti, Nb, V, Cr, Ni, Mo, S
n, As, Sb, etc.), the effect of the present invention is not impaired at all.

In addition to the above ranges for each element,
Component parameter A and ferrite grain size g are A + 4.3
It is important to control the composition and control the structure of the steel sheet so as to satisfy the relationship of 6 ≧ g in order to obtain excellent magnetic properties at high frequencies. Here, the component parameter A is as follows: A = 6.77 [% C] +15.0 [% Si] +4.84
[% Mn] +24.2 [% P].

In general, when the content of an element such as C is large,
Crystal grains tend to be small. That is, g tends to increase, and the magnetic characteristics deteriorate. However, a steel sheet having good magnetic properties can be obtained by controlling the steel sheet structure and adjusting g so as to satisfy the relationship of component parameter A and A + 4.36 ≧ g.

It is already generally known that when an impurity element is added to steel, the specific resistance of the steel increases. As the specific resistance of the steel increases, the high-frequency iron loss of the steel sheet decreases. However, as described above, when C and other elements are added to steel, the ferrite grain size decreases, that is,
The grain size increases, and the high-frequency iron loss of the steel sheet increases. That is, the content of the impurity element to be added to the steel is not necessarily increased or decreased steadily, and a balance with the ferrite grain size is important. The above (1)
The relationship between the expressions is obtained by experiments, and the physical reason is not necessarily clear. However, the coefficient of the term of each element in the above expression (1) is such that when a certain ferrite grain size is obtained, the high frequency iron loss is reduced. This is considered to indicate the balance of the component values of each element necessary to maintain the values.

The plate thickness can be selected according to the desired iron loss level and the number of man-hours allowable in the motor manufacturing process.
The thinner the plate, the smaller the eddy current loss can be reduced. However, for inexpensive small motors, the cost increase in the motor manufacturing process cannot be ignored if the plate thickness is less than 0.30 mm. In view of this, it is hard to say that the steel plate is an inexpensive steel plate aimed at by the present invention.

On the other hand, as the sheet thickness increases, the ratio of the eddy current loss to the total iron loss becomes relatively large. When the sheet thickness exceeds 1.8 mm, the magnetic properties are controlled even if the composition is adjusted and the steel sheet structure is controlled so as to satisfy the above equation. May be inferior.

Therefore, in a preferred embodiment of the present invention, the range of the plate thickness is set to 0.30 mm or more and 1.8 mm or less. Preferably 0.5 m for lower cost and excellent magnetic properties
It is preferable that the thickness be not less than m and not more than 1.6 mm.

After the slab having the steel composition adjusted as described above is hot-rolled, pickled, cold-rolled, and further subjected to finish annealing, the hot-rolling finish temperature is Ar _3.
It is below the transformation point.

When the finishing temperature exceeds the transformation point of Ar ₃ , after passing through the transformation point after rolling, the structure becomes free of distortion and the driving force for crystal grain growth is greatly reduced.
The hot rolled sheet structure becomes fine.

When the structure of the hot-rolled sheet becomes fine, the crystal grains obtained after cold rolling and annealing tend to become fine, and it becomes difficult to obtain necessary magnetic properties. Increasing the annealing temperature to grow crystal grains to compensate for this is not only disadvantageous in terms of cost, but also forms many (111) structures disadvantageous to the magnetic properties generated near the grain boundaries, and There is also a possibility that the characteristics are deteriorated.

In order to make the hot-rolled sheet structure as coarse as possible, the finishing temperature is preferably as high as possible below the transformation point. However, passing the transformation point immediately before the final finishing stand causes instability of rolling, and is therefore preferable. It is preferable that the temperature immediately before the final finishing stand is Ar ₃ -10 ° C. or less.

In the case of performing low-temperature finish rolling at a temperature lower than the Ar ₃ transformation point as in the present invention, the slab is heated to a relatively low temperature such as 1000 to 1250 ° C. However, the lower the heating temperature, the larger the temperature difference between the contact portion (skid mark) between the skid and the slab of the heating furnace and the non-contact portion tends to be. Therefore, it is preferable that the steel sheet (rough bar) before the finish rolling is kept at a temperature or reheated as necessary. As a result, the finishing temperature is set to A over the entire length of the coil.
The temperature can be controlled as high as possible below the r ₃ transformation point, and uniform and excellent magnetic properties can be obtained.

The winding temperature after finish rolling is set to 600 ° C. or higher in order to obtain sufficient crystal grain growth during air cooling after winding. The rolling reduction of the cold rolling is not particularly limited because there is no significant difference in the magnetic properties obtained as long as it is within a range that does not hinder normal operation. 90%.

The lower limit of the finish annealing is set to 650 ° C. in order to obtain complete recrystallization. If the temperature is lower than this, strain remains in the tissue, so that the magnetic properties rapidly deteriorate. In order to grow crystal grains, it is preferable to perform finish annealing at a higher temperature. However, the higher the annealing temperature, the more disadvantageous in cost. Therefore, the allowable upper limit for obtaining an inexpensive steel sheet is 900 ° C.

In the overaging treatment subsequent to the finish annealing, by precipitating solute C in the steel, magnetic aging due to precipitation of fine carbides during use as a product is suppressed, and the steel sheet is adjusted to a hardness suitable for processing. I do.

If the overaging temperature is lower than 300 ° C., sufficient activation energy for carbide precipitation cannot be obtained.
Aging treatment is insufficient and solute C remains, resulting in a problem of increased steel sheet hardness and magnetic aging.
The temperature is preferably set to 0 ° C.

On the other hand, at a temperature exceeding 500 ° C., since the driving force for carbide precipitation is small, solute C remains and the same problem as described above occurs, so the upper limit is 500 ° C.
It is preferred that

Further, when the overaging treatment time is shorter than 150 seconds, a large amount of solid solution C may remain.
It is desirable to set it to 50 seconds or more. In addition, if coarse carbides are precipitated by the overaging treatment specified as described above, these become the starting points of cracks, and furthermore, the cracks are easily propagated, so that the punching properties are good, and other measures for the punching properties are intentionally taken. This does not cause deterioration of magnetic characteristics or increase in cost.

The temper rolling after the finish annealing, especially the temper rolling after the above-mentioned overaging treatment, may be carried out as necessary for the purpose of securing the shape of the steel sheet. In that case, however, the hysteresis due to the introduction of strain is required. The elongation is preferably set to 2% or less in order to minimize loss and deterioration of magnetic flux density.

[0054]

EXAMPLES Slabs of steel compositions A to Q shown in Table 1 (Ar ₃ points 8
00 ° C. or higher) at a heating temperature of 1200 ° C. and a finishing temperature of 780
After hot-rolling to a thickness of 3.8 mm at 650 ° C. and winding at 650 ° C., after pickling, it was cold-rolled to 1.0 mm and 780 ° C.
And then overaged at 400 ° C. for 360 seconds, followed by temper rolling of 1.2%. Table 1 shows the results of conducting an electromagnetic test and a hardness test at a high frequency on the steel sheet thus manufactured.

[0055]

[Table 1] The high frequency electromagnetic test was performed by the following method. First, a ring test piece having an outer diameter of 45 mm and an inner diameter of 33 mm was cut out from a steel sheet, five sheets were laminated, and the iron loss (W5 / 2000) was measured at a high frequency of 2000 Hz. As a steel sheet having excellent high-frequency magnetic properties, a steel sheet having a thickness of 1.0 mm and having a W5 / 2000 of 640 W / kg or less in the measurement under these conditions is within the scope of the present invention.

The hardness Hv of the steel sheet is measured according to JISZ2244.
And the test force was measured at 49N. As for the hardness whose tool life becomes a problem when the machining includes a cutting step, those having an Hv of 130 or more are out of the scope of the present invention because deterioration of the machinability is inevitable.

As shown in Table 1, a steel composition having a composition outside the upper and lower limits of the composition specified in the range of the present invention has a large iron loss at a high frequency and cannot obtain excellent magnetic properties,
It can be seen that the workability is inferior due to the high hardness of the steel sheet.

Next, in order to obtain a steel sheet of 1.0 mm from the slabs of the steel compositions A to J in Table 1 in the same manner as described above,
The finishing temperature of hot rolling, the winding temperature, and the temperature of finishing annealing were variously changed to create crystal grain sizes. The results of high-frequency iron loss measurement and ferrite crystal grain size measurement specified in JIS G 0552 were performed on each steel sheet. As shown in FIG.

As shown in FIG. 1, the crystal grain size is A +
In a steel sheet satisfying 4.36 ≧ g, high-frequency iron loss is kept small even if the content of alloying elements is small. Conversely, it can be seen that even if the crystal grain size is large, if the component is contained so as to satisfy the above expression, excellent high-frequency iron loss is exhibited.

Table 2 shows that a slab of steel composition C or E was heated to a thickness of 2.3 mm, 3.8 mm, and 4.5 mm at a heating temperature of 1180 ° C., a finishing temperature of 800 ° C., and a winding temperature of 630 ° C. After rolling and pickling, the plate thickness is 0.5 mm and 1.0 m, respectively.
m, 1.6 mm, cold-rolled, finish-annealed at 780 ° C., subsequently overaged at 400 ° C. for 300 seconds, and then subjected to 1.2% temper rolling to produce a steel sheet as described above. It shows the result of performing a similar high-frequency electromagnetic test.

[0061]

[Table 2] The sheet thickness is selected according to the required iron loss level, that is, the iron loss level greatly differs depending on the sheet thickness.
As a steel sheet having excellent high-frequency magnetic properties, W5 / 2000 is measured under the above conditions,
0W / kg or less, 640W / kg when the thickness is 1.0mm
Hereinafter, those having a plate thickness of 1.6 mm and 1500 W / kg or less are within the scope of the present invention.

Table 3 shows that slabs of steel compositions A and F were 1200
° C, hot-rolled, cold-rolled, finish-annealed, overaged, and temper-rolled under the conditions in Table 3
mm steel plate, high-frequency iron loss as described above,
It is the result of measuring the hardness of the steel sheet and the grain size of the ferrite crystal.

[0063]

[Table 3] The finishing temperature of hot rolling is 850 ° C. at the Ar ₃ transformation point of steel composition F.
Steel No. exceeding No. 13 or steel No. with a winding temperature of less than 600 ° C. In the case of No. 14, fine grains are not obtained, and a target high-frequency iron loss cannot be obtained. The steel No. whose finish annealing temperature did not reach 650 ° C. In No. 15, an unrecrystallized structure remains, and iron loss is deteriorated.

In the case of steel No. 3 which is out of the range of the present invention, the temperature or time of the overaging treatment is different. Nos. 16 to 18 are excellent in high-frequency magnetic properties, but the steel plate hardness is too high. Steel No. with too high elongation in temper rolling. No. 19 has deteriorated magnetic characteristics.

On the other hand, steel N within the scope of the present invention
o. Nos. 1 to 12 have target characteristics in both high-frequency magnetic characteristics and steel plate hardness.

[0066]

According to the present invention, an electrical steel sheet having good high-frequency magnetic characteristics can be obtained by keeping the content of the components and the crystal grain size of the product in a certain relationship regardless of the costly means.

[Brief description of the drawings]

FIG. 1: Ferrite grain size g and component parameter A
It is a figure which shows the relationship between iron loss W5 / 2000.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H01F 1/16 H01F 1/16 A F term (Reference) 4K033 AA01 CA06 CA08 CA09 FA03 FA10 KA00 RA03 SA03 5E041 AA02 AA11 AA19 CA04 HB05 HB07 HB11 NN01 NN17 NN18

Claims (7)

[Claims] 1. In mass%, C: more than 0.015%, 0.08% or less Si: 0.8% or less Mn: 0.05% or more, 0.80% or less P: 0.06% or less And the ferrite grain size specified in JIS G0552 is g, 6.77 [% C] +15.0 [% Si] +4.84 [% Mn] +24.2 [% P] + 4.36 ≧ g ... (1) An electromagnetic steel sheet excellent in high-frequency magnetic properties, characterized by satisfying the relationship of the above formula (1). 2. N and S as unavoidable impurities are respectively expressed by mass%, N: 0.007% or less, and S: 0.0
The electrical steel sheet according to claim 1, wherein the electrical steel sheet is limited to 10% or less. 3. The magnetic steel sheet according to claim 1, further comprising Al: 0.05% or less and B: 0.0003 to 0.005% by mass%. 4. The magnetic steel sheet according to claim 1, wherein the sheet thickness is 0.30 mm or more and 1.8 mm or less. 5. In mass%, C: more than 0.015%, 0.08% or less Si: 0.8% or less Mn: 0.05% or more, 0.80% or less P: 0.06% or less And, if necessary, Al: 0.05% or less and / or
Or B: When hot rolling, pickling, cold rolling, and then finish annealing are performed on a slab further containing 0.0003 to 0.005%, the finishing temperature is set to the Ar ₃ transformation point or lower in hot rolling. Winding is performed at 600 ° C or higher, and refining treatment at 650 ° C or higher and 900 ° C or lower is performed in finish annealing to obtain a ferrite crystal grain size specified in JIS G0552 as g of 6.77 [% C] +15.0 [ % Si] +4.84 [% Mn] +24.2 [% P] + 4.36 ≧ g (1) Excellent in high-frequency magnetic characteristics characterized by satisfying the relationship (1) above Manufacturing method of electrical steel sheet. 6. A method for producing an electrical steel sheet, comprising performing, after the finish annealing defined in claim 5, an overaging treatment at a lower limit of 300 ° C. and an upper limit of 500 ° C. for a treatment time of 150 seconds or more. 7. A method for producing a magnetic steel sheet, comprising subjecting a cold-rolled steel sheet after the finish annealing defined in claim 5 to temper rolling at an elongation of 2% or less.