JP2001115243A - Steel sheet excellent in magnetic property and producing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a steel sheet excellent in magnetic properties and to provide a method for producing the same. SOLUTION: In extra low carbon steel in which the contents of C and N are properly regulated, by controlling X expressed by X=4×Si(%)+5×Mn(%)+80×P(%)+2×Al(%) and Y expressed by Y=0.5×Si(%)+Al(%)-0.3×Mn(%)+0.4×P(%) to proper ranges, or adding suitable amounts of Ti and Nb and moreover optimizing annealing temperature, the steel sheet excellent in magnetic properties can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for adjusting a size
More particularly, the present invention relates to a steel sheet having a high density of high density and excellent magnetic properties and a method of manufacturing the same.

[0002]

2. Description of the Related Art A steel sheet used for a magnetic core of a rotating machine, a transformer or the like is required to have two characteristics of a small iron loss and a high magnetic flux density. To achieve this, it is important to integrate the <100> direction, which is the direction of easy magnetization, in the direction of the magnetic field. The normal direction of the steel plate surface is <hkl> and the rolling direction is <u
When vw>, the crystal orientation of the steel sheet can be expressed as ｛hkl｝ <uvw>. When a magnetic field is applied only in one direction in the plane of the sheet, a grain-oriented electrical steel sheet with a crystal orientation of {110} <001> is used, but the magnetic field is applied in two or more directions in the plane of the sheet. If it is added, it is desirable to set {100} <uvw>. For example, a steel sheet having {100} <011> is a suitable material.

Conventionally, various proposals have been made for techniques for obtaining a steel sheet having a crystal orientation of {100} <uvw>. For example, JP-A-1-108345, JP-A-1-252727, JP-A-1-319632, and JP-A-5-320768 all disclose techniques for obtaining {100} texture by utilizing transformation. Is disclosed. These steels are subjected to decarburizing annealing on a steel sheet containing relatively high C to form a decarburized layer on the surface, and the crystal grains having {100} texture formed in the decarburized layer in the subsequent second decarburizing annealing are formed. The growth of the thickness center layer is the basis of the technology. The {100} integration achieved by this technology is very high. However, in these methods, the total of the first and second annealing times is 2
It takes 5 minutes to 48 hours, resulting in an unrealistic process with extremely low productivity. On the other hand, JP-A-53-31
JP-A-515 and JP-A-53-31518 disclose that a {100} <uvw> texture can be developed even if the heating time in the γ region is relatively short. However, the $ 100 gained by this technology
The strength of｝ is about 3 at the maximum, and cannot be said to be a technology for dramatically improving magnetic properties.

[0004]

As described above, the conventional technique for obtaining a steel sheet having a texture of {100} <uvw> requires a complicated annealing process, or the manufacturing process is simple. However, there is a problem that the obtained {100} strength is insufficient. The present inventors have conducted intensive studies on the above-described technology, and found that a steel plate having a strong {100} texture, and even a {100} <011> texture by an extremely simple manufacturing process by strictly adjusting the chemical components. We have newly clarified what can be obtained. An object of the present invention is to drastically solve the problems of the prior art, and to provide a steel sheet having excellent magnetic properties and a method for manufacturing the same.

[0005]

Means for Solving the Problems The present inventors have proposed {100}
In order to obtain a steel sheet accumulated in a steel plate, when annealing in the α + γ region or γ single phase region, that is, after α → (α + γ) → α transformation,
Or, the influence of chemical components on texture formation after α → γ → α transformation was studied diligently. As a result, very strong {100} by limiting to specific chemical components
It has been clarified that a steel sheet having a texture can be obtained relatively easily.

The present invention is a steel plate which has been constructed based on such new knowledge and has a completely new and excellent magnetic property and a method of manufacturing the same. The gist of the present invention is as follows. (1) By weight%, C = 0.0008 to less than 0.0040%, Si = 3.5% or less, Mn = 3.0% or less, P = 0.15% or less, S = 0.015%, Al =
0.005 to 1.8%, N = 0.0040%, O = 0.0005 to 0.02% and X = 4 × Si (%) + 5 × Mn (%) + 80 × P (%) + 2 × Al (%) 4 ≤ Satisfies X ≦ 15, and Y = 0.5 × Si (%) + Al (%) −
0.3 × Mn (%) + 0.4 × P (%) When it contains Si, Al, Mn, P to satisfy Y ≤ 0.9, has a chemical composition consisting of the balance Fe and unavoidable impurities, at least steel plate ｛100 parallel to the plate surface measured by irradiating the outermost surface of the plate with X-rays
｝ Surface X-ray random intensity ratio exceeds 4.0, plate thickness 0.7 mm
A steel sheet having excellent magnetic properties, characterized in that:

(2) By weight%, C = 0.0008 to less than 0.0040%, Si = 3.5% or less, Mn = 3.0% or less, P = 0.15% or less, S = 0.
015% or less, Al = 0.005 to 1.8%, N = less than 0.0040%, O = 0.0005
~ 0.02%, Nb: 0.002-0.10%, and Y =
0.5 × Si (%) + Al (%)-0.3 × Mn (%) + 0.4 × P (%) Y
≦ 0.9, Si, Al, Mn, P are contained, and the balance Fe
And an X-ray random intensity ratio of {100} plane parallel to the plate surface when measured by irradiating at least the outermost surface of the plate with X-rays.
A steel sheet having excellent magnetic properties, characterized by having a thickness of more than 0 and a thickness of 0.7 mm or less.

(3) By weight%, C = 0.0008 to less than 0.0040%, Si = 3.5% or less, Mn = 3.0% or less, P = 0.15% or less, S = 0.
015% or less, Al = 0.005 to 1.8%, N = less than 0.0040%, O = 0.0005
~ 0.02% or less, Ti: 0.001 ~ 0.008% or Ti: 0.04 ~
0.3%, Y = 0.5 × Si (%) + Al (%)-
0.3 × Mn (%) + 0.4 × P (%) contains Si, Al, Mn, P to satisfy Y ≤ 0.9, has a chemical composition consisting of the balance Fe and unavoidable impurities, at least steel plate ｛100 parallel to the plate surface measured by irradiating the outermost surface of the plate with X-rays
｝ Surface X-ray random intensity ratio exceeds 4.0, plate thickness 0.7 mm
A steel sheet having excellent magnetic properties, characterized in that:

(4) C = 0.0008 to less than 0.0040%, Si = 3.5% or less, Mn = 3.0% or less, P = 0.15% or less, S = 0.
015% or less, Al = 0.005 to 1.8%, N = less than 0.0040%, O = 0.0005
~ 0.02%, Nb = 0.002-0.06%, Ti is Ti = 0.001-0.00
8% or Ti = 0.04 to 0.2%
= 0.5 × Si (%) + Al (%)-0.3 × Mn (%) + 0.4 × P (%)
Si, Al, Mn, P are contained so as to satisfy Y ≤ 0.9, and the balance Fe
And an X-ray random intensity ratio of {100} plane parallel to the plate surface measured by irradiating at least the outermost surface of the plate with X-rays and having a chemical composition of unavoidable impurities.
Ultra-thin steel sheet with excellent magnetic properties characterized by a sheet thickness of 0.7 mm or less.

(5) By weight%, B = 0.0002-0.0040%, V =
0.002 to 0.1%, W = 0.002 to 0.1%, Mo = 0.003 to 0.4%, Sn =
5. One or two or more of 0.002 to 0.3%, Cu = 0.005 to less than 0.3%, Cr = 0.005 to 0.4% and Ni = 0.005 to 0.3%. A steel sheet having excellent magnetic properties as described in the item. (6) A slab having the chemical composition according to any one of the above (1) to (5) is hot-rolled and kept at a temperature of ((Ac ₁ + Ac ₃ ) / 2) ° C. or more for less than 10 minutes. A method for producing a steel sheet having excellent magnetic properties.

(7) A slab having the chemical composition according to any one of the above (1) to (5) is hot-rolled, cold-rolled at a rolling reduction of 99% or less, and ((Ac ₁ + Ac ₃ ) / 2) A method for producing a steel sheet having excellent magnetic properties, characterized by heating at a temperature of not less than 10 ° C. for less than 10 minutes. (8) A slab having the chemical composition according to any one of the above (1) to (5) is hot-rolled and held in an α single phase region for 5 seconds to 10 minutes, and then ((Ac ₁ + Ac ₃₎ ) / 2) A method for producing a steel sheet having excellent magnetic properties, wherein the steel sheet is heated to a temperature of not less than ° C and held for less than 10 minutes.

(9) A slab having the chemical composition described in any one of (1) to (5) above is hot-rolled, cold-rolled at a rolling reduction of 99% or less, and subjected to an α single phase region. 10 seconds for more than 5 seconds
A method for producing a steel sheet having excellent magnetic properties, wherein the steel sheet is heated to a temperature of ((Ac ₁ + Ac ₃ ) / 2) ° C. or more after holding for not more than 10 minutes and held for less than 10 minutes.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. C is an important element in the present invention. That is,
Only by controlling the C content can a strong {100} texture be formed. The range is 0.0008 ~
Less than 0.0040%. The reason for this is not necessarily clear, but it is believed that a small amount of C segregated on the steel sheet surface during annealing promotes the formation of {100} texture on the steel sheet surface. If the amount of C is too small, the {100} texture will not be sufficiently developed. On the other hand, if the amount of C is too large, the amount of C segregated on the surface during the annealing step will be too large, and the strength of {100} will be rather lowered. Therefore,
0.0008% to less than 0.0040%. Further, in the present invention, C must be less than 0.0008-0.0040% before the annealing step in the α + γ region or the γ single phase region. If C exceeds 0.0040% before the annealing step, even if C
Even if less than 0.0040%, good texture cannot be obtained.
The content of C is preferably more than 0.0010% to less than 0.0030%.

Although Si is contained as an impurity, it is added as necessary, because it improves magnetic properties and increases mechanical strength at low cost. However, if Si is too much, it causes embrittlement, and the α → γ transformation point becomes too high, and the α + γ region and the γ region disappear, so the upper limit is 3.5%. The content of Si is preferably less than 2.0%. Mn
Although it is contained as an impurity, it is a solid solution strengthening element effective for increasing mechanical strength, and has the effect of reducing eddy current loss and lowering the α → γ transformation point. I do. However, if too much Mn is added, the structure becomes bainitic via γ → α transformation and the strength becomes too high, or the development of {100} texture is prevented, so the upper limit is set to 3.0%. . The Mn content is more preferably less than 2.0%.

[0015] P is contained as an impurity, but if the added amount exceeds 0.15%, cracks may occur during hot rolling or cold rolling. In addition, the α → γ transformation point increases. If the content of P is too large, a desired texture cannot be obtained, probably because of surface segregation. Therefore, the upper limit of the P content is set to 0.15
%. S is an impurity, and if it exceeds 0.015%, it causes hot cracking or deteriorates workability, so the upper limit is 0.015%.

Al is used not only for the preparation of deoxidation but also for improving the magnetic properties. However, the addition amount is 1.
If it exceeds 8%, the α → γ transformation point rises significantly, or α +
The upper limit is 1.8% because the γ region or the γ region disappears. A
The content of 1 is more preferably 0.01 to less than 1.0%. N is an impurity, and if it is too much, it segregates on the surface during the annealing process and prevents the formation of {100} texture, or Al or Ti
0.0040 because it forms nitrides and deteriorates magnetic properties
%. The N content is preferably less than 0.0025%. Although there is no particular lower limit for the N content, 0.0010% is a practical lower limit in consideration of steelmaking load.

O, like C, is an important element in the present invention. That is, if O is too much, it segregates on the steel sheet surface during annealing or forms an oxide to prevent the formation of {100} texture on the surface, so that the content is less than 0.02%. On the other hand, O
Has an effect of promoting the development of {100} texture when present in a trace amount, so the lower limit is made 0.0005%. The O content is preferably 0.0010 to less than 0.01%, more preferably 0.000 to less than 0.01%.
10 to less than 0.0030.

Further, in the present invention, when Ti or Nb is not contained, Si, Mn, P and Al are converted to X = 4 × Si (%) + 5
X expressed by × Mn (%) + 80 × P (%) + 2 × Al (%) is 4 ≦ X
It is necessary that it be contained so as to satisfy ≦ 15. When Ti and / or Nb is contained, there is no need to limit X. The above-mentioned limitation on X is based on the fact that the addition amount of Si, Mn, P and Al is systematically changed in a steel sheet containing no Ti and Nb and a steel sheet containing Ti and Nb, so that the chemical composition and the steel sheet surface are reduced by 100%.基 づ く Based on the result of investigation on the relationship with X-ray intensity. That is, by controlling X within a predetermined range, it is only possible to reduce the {100}
｝ The formation of texture is remarkably promoted. It is not always clear why there is a proper range for X, but S
It is presumed that i, Mn, P and Al have some influence on the crystal orientation dependence of surface energy. A more preferable range of X is 5 ≦ X ≦ 12. Also, Si, Al, M
n and P are Y = 0.5 x Si (%) + Al (%)-0.3 x Mn (%) + 0.4 x P
(%), It is necessary to contain Y so as to satisfy Y ≦ 0.9. If Y exceeds 0.9, the transformation point rises significantly, making it difficult to utilize the α → γ → α transformation which forms the basis of the present invention. Although the reason is not clear, if Y exceeds 0.9, the {100} texture will not develop even if α → γ → α transformation is performed.

Nb is an important element in the present invention, and it has been clarified that, by adding an appropriate amount of Nb as needed, a {100} texture at least in the surface layer portion of the sheet thickness is remarkably developed. In order to exhibit this effect, Nb must be added in an amount of 0.002% or more. Also, 0.10%
If added in excess of {100}, the {100} strength will rather decrease, so this is the upper limit. The N content is preferably 0.
01 to 0.06%.

Ti also has a similar effect to Nb. The addition amount of Ti is set to 0.001% to 0.008% or 0.04 to 0.3%. Ti is 0.00
If it is more than 8 and less than 0.04%, TiN precipitates finely, and the magnetic properties deteriorate. If Ti is less than 0.001%, the effect of the addition is not remarkable, and if it exceeds 0.3%, the development of {100} texture is suppressed. When Ti and Nb are added as a composite, 0.001 to 0.008% or 0.04 to 0.2% of Ti and 0.
Add in the range of 002 to 0.06%. The reasons for limiting the contents of Ti and Nb are the same as in the case of single addition. If Ti and Nb contents are too large, the development of {100} texture will be hindered.
Preferably, it is less than 0.1%.

B, V, W, Mo, Sn, C
u, Cr, Ni are B = 0.0002 to 0.0040%, V = 0.002 to 0.1%, W =
0.002-0.1%, Mo = 0.003-0.4%, Sn = 0.002-0.3%, Cu =
It may be contained in the range of 0.005 to less than 0.3%, Cr = 0.005 to 0.4%, and Ni = 0.005 to 0.3%. This is because even if these elements are added within the above range, the magnetic properties are not particularly deteriorated.

In the steel sheet of the present invention, the X-ray random intensity ratio of at least the {100} plane parallel to the sheet surface on the outermost surface of the steel sheet is more than 4.0. Its thickness is 0.7mm or less. If the plate thickness exceeds 0.7 mm, a crystal orientation other than {100} is likely to be generated at the center of the plate thickness, and the magnetic properties deteriorate. The plate thickness is preferably 0.
6 mm or less. The lower limit of the sheet thickness is not particularly required, but is preferably 0.15 mm or more in order to obtain a good texture.

The measurement of the surface intensity by X-rays may be carried out according to the method described in, for example, the New Version of Curity X-Ray Diffraction Theory (published in 1986, translated by Gentaro Matsumura, Agne Co., Ltd.), pp. 290-292. The sample adjustment for X-ray measurement is performed as follows.
When measuring the {100} X-ray intensity at the outermost surface of the steel sheet, it is assumed that the surface of the steel sheet obtained by the present invention is free of scale and rust. In the case where dirt or surface coating has been applied, measurement is performed after removing these by an appropriate method.
If it is difficult to measure the {100} strength of the outermost surface of the steel sheet from the viewpoint of roughness or segregation, reduce the thickness by less than 1/4 of the sheet thickness from the steel sheet surface. Is also good. The thickness reduction is performed as follows. After grinding by mechanical polishing or chemical polishing, etc. and finishing to a mirror surface by buffing, distortion is removed by electrolytic polishing or chemical polishing, and at the same time, adjustment is made so that the ground surface becomes a predetermined measurement surface.

Next, the reasons for limiting the manufacturing conditions will be described. The slab to be subjected to hot rolling is not particularly limited. That is, it may be any one manufactured with a continuous cast slab or a thin slab caster (thin slab CC). It is also suitable for processes such as continuous casting-direct rolling (CC-DR) in which hot rolling is performed immediately after casting. After the rough rolling in the hot rolling, the sheet bars may be joined and the hot finish rolling may be continuously performed. When a cast slab is obtained from the thin slab CC, it may be directly subjected to cold rolling or annealing without subjecting it to hot rolling.

The heating temperature of the hot rolling is not particularly limited, but is set to 900 ° C. or more to reduce the deformation resistance during hot rolling, and 1350 ° C. or less to suppress excessive generation of surface scale. Is preferred. The finishing temperature of hot rolling is not particularly limited. That is, ordinary Ar ₃
It may be carried out in a γ-phase single-phase region at or above the transformation temperature, or in an α + γ2-phase region or an α-single-phase region below Ar ₃ points. In any case, lubrication may be performed.

[0026] Cold rolling may or may not be performed.
However, in reality, it is difficult to reduce the sheet thickness to 0.7 mm or less by hot rolling or thin slab CC, or to obtain preferable surface properties. Therefore, it is preferable to perform cold rolling at a rolling reduction of 30% or more. If the rolling reduction exceeds 99%, the rolling load becomes too high, and it is necessary to perform intermediate annealing or the like, which lowers the productivity. Therefore, the upper limit is set.

The annealing conditions are important in the present invention.
That is, the sharp {100} texture that is a feature of the present invention is formed through the α → γ (or α + γ) transformation that occurs during heating during annealing and the γ (or α + γ) → α transformation that occurs during cooling. Therefore, the annealing temperature is set to ((Ac ₁ + Ac ₃ ) /
2) Must be at least ° C. ((Ac ₁ + Ac ₃ ) / 2) ℃
If the temperature is lower than α → γ transformation rate is not enough,
｝ The texture development is insufficient. In order to further develop the {100} texture, it is preferable that the annealing temperature be equal to or higher than the Ac ₃ transformation temperature. Also, by annealing at such a temperature, the amount of carbides that degrade the magnetic properties can be reduced. That is, when a steel sheet contains carbide-forming elements such as Ti and Nb, it is easy to form before or during annealing, but these carbides are α + γ
There is an effect of decomposing in the region or γ region. The upper limit of the annealing temperature is not particularly limited. However, if the annealing temperature is too high, the sheet may break in the annealing line or the surface properties of the product may be deteriorated. The annealing time is less than 10 minutes, preferably less than 5 minutes, and more preferably less than 2 minutes from the viewpoint of productivity. Although the lower limit of the annealing time is not particularly limited, it is preferable that the annealing time is maintained for 1 second or more in order to stably obtain the desired α and γ tissue fractions. In addition, before annealing at a temperature of ((Ac ₁ + Ac ₃ ) / 2) ° C. or more, if heating and holding are performed in an α single phase region for 5 seconds to 10 minutes, {100} texture can be further developed. it can. If the time is less than 5 seconds, this effect is not sufficient, and if the time exceeds 10 minutes, no particular effect is obtained, and the productivity is reduced. 10 seconds to less than 2 minutes is a more preferred range.

The atmosphere of the annealing is not particularly limited, but nitrogen, hydrogen,
Alternatively, a mixed gas of nitrogen and hydrogen is suitable. The dew point is preferably set to 10 ° C. or less. The cooling condition after annealing is not particularly limited, but is preferably in the range of 10 to 40 ° C./s in order to increase the {100} texture. Cooling rate is 40 ℃
/ s, the driving force of the γ → α transformation increases, resulting in γ
→ It is considered that many α grains with orientations other than {100} nucleate on the steel sheet surface during α transformation and the degree of accumulation of {100} decreases. On the other hand, when the cooling rate is less than 10 ° C / s, crystal grains having a crystal orientation other than {100} formed inside the steel sheet (other than the outermost surface) grow, resulting in a weaker degree of integration of {100} In addition to those containing Ti and Nb
TiC and NbC precipitate during cooling, resulting in poor magnetic properties.

After annealing, it may be subjected to skin pass rolling or leveling for shape correction or the like. The surface is preferably coated with an insulating coating. Next, the present invention will be described with reference to examples.

[0030]

EXAMPLES (Example 1) Steel having the composition shown in Table 1 was melted and hot-rolled to form a steel strip having a thickness of 3.0 mm. After pickling,
Cold-rolled at a rolling reduction of about 83% to give a cold-rolled sheet having a thickness of 0.5 mm, and then heated at an average heating rate of 30 ° C./s.
After annealing in the single phase region for 100 seconds, the sample was cooled from the annealing temperature to 300 ° C at an average cooling rate of 20 ° C / s. A ring-shaped sample (inner diameter 33 mm, outer diameter 45 mm) was sampled from the obtained steel sheet, and the magnetic properties were evaluated. The magnetic properties were evaluated based on the magnetic flux density (B50) when an external magnetic field of 5000 A / m was applied and the iron loss (W15 / 50) when magnetized to 1.5 T in an AC magnetic field of 50 Hz. Furthermore, the X-ray random intensity ratio of the {100} plane was measured on the steel sheet surface, the center of the thickness, and the plane whose thickness was reduced by 1/4 from the outermost surface of the steel sheet.

The results are shown in Table 2. As is clear from this, a steel sheet having excellent magnetic properties can be obtained by optimizing the components in steel, the values of X and Y, and the amounts of Ti and Nb.

[0032]

[Table 1]

[0033]

[Table 2]

(Example 2) Steels A-4, C-2 and
The annealing temperature was changed in the temperature range from α single phase to γ single phase using C-9 cold rolled steel sheet. The heating and cooling conditions at this time are the same as in the first embodiment. In the same manner as in Example 1, the surface strength was measured by X-rays and the magnetic properties were evaluated.

Table 3 shows the results. As is clear from this, when the annealing temperature was not in the proper range, the {100} plane strength was low, and the magnetic properties were poor. On the other hand, when annealing was performed in an appropriate temperature range, a steel sheet having excellent magnetic properties could be obtained.

[0036]

[Table 3]

Example 3 Steels A-4 and C-2 shown in Table 1 and
Using a C-9 cold rolled steel plate, the effect of holding in the α single phase region was investigated. In other words, once the 85
After being kept at 0 ° C. for 60 seconds, it was heated at a heating rate of 30 ° C./s in the γ single phase region for 100 seconds. The cooling conditions are the same as in the first embodiment. In the same manner as in Example 1, the surface strength was measured by X-rays and the magnetic properties were evaluated.

The results are shown in Table 4. As is evident from this, the addition of retention in the α
The 0-plane strength could be increased, and as a result, the magnetic properties could be further improved.

[0039]

[Table 4]

[0040]

As described above, according to the present invention, a steel sheet having excellent magnetic properties can be obtained easily and inexpensively. Therefore, when the steel sheet is used for a motor, a generator, a transformer, etc., energy loss is reduced, and the earth environment is reduced. It can contribute to conservation.

Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court II (Reference) H01F 1/16 H01F 1/16 A (72) Inventor Kenichi Murakami 1-1 Hibata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka Japan F-term (reference) at Yawata Works 4K033 AA02 CA01 CA02 CA05 CA06 CA07 CA10 FA04 HA03 HA04 JA07 RA04 SA03 5E041 AA11 AA19 CA02 CA04 HB05 HB07 HB11 NN06 NN11 NN17 NN18

Claims (9)

[Claims] (1) C = 0.0008 to less than 0.0040% by weight,
= 3.5% or less, Mn = 3.0% or less, P = 0.15% or less, S = 0.015%, Al = 0.005-1.8%, N = 0.0040%, O = 0.0005-0.02
%, And X = 4 × Si (%) + 5 × Mn (%) + 80
When XP (%) + 2 × Al (%), 4 ≦ X ≦ 15 is satisfied, and Y
= 0.5 × Si (%) + Al (%)-0.3 × Mn (%) + 0.4 × P (%) Y
≦ 0.9, Si, Al, Mn, P are contained, and the balance Fe
And an X-ray random intensity ratio of {100} plane parallel to the plate surface measured by irradiating at least the outermost surface of the plate with X-rays and having a chemical composition of unavoidable impurities.
Ultra-thin steel sheet with excellent magnetic properties characterized by a thickness of 0.7 mm or less. 2. C = 0.0008 to less than 0.0040% by weight, Si
= 3.5% or less, Mn = 3.0% or less, P = 0.15% or less, S = 0.015% or less, Al = 0.005 to 1.8%, N = 0.0040%, O = 0.0005 to 0.02
%, Nb: 0.002 to 0.10%, and further Y = 0.5 × Si
(%) + Al (%)-0.3 × Mn (%) + 0.4 × P (%) Y ≤0.9
Contains Si, Al, Mn, and P, and has a chemical composition consisting of the balance of Fe and unavoidable impurities. A steel sheet having excellent magnetic properties, characterized by having an X-ray random intensity ratio of a {100} plane parallel to that of the steel sheet exceeding 4.0 and a sheet thickness of 0.7 mm or less. 3. The method according to claim 1, wherein C = 0.0008 to less than 0.0040% by weight.
= 3.5% or less, Mn = 3.0% or less, P = 0.15% or less, S = 0.015% or less, Al = 0.005 to 1.8%, N = 0.0040%, O = 0.0005 to 0.02
%, Ti: 0.001 to 0.008% or Ti: 0.04 to 0.3%, and further Y = 0.5 × Si (%) + Al (%)-0.3 ×
When Mn (%) + 0.4 × P (%), Si,
Al, Mn, P, has a chemical composition consisting of the balance Fe and unavoidable impurities, and at least X
A steel sheet having excellent magnetic properties, characterized in that the X-ray random intensity ratio of the {100} plane parallel to the sheet surface as measured by irradiation with X-rays is more than 4.0 and the sheet thickness is 0.7 mm or less. 4. C = 0.0008 to less than 0.0040% by weight, Si
= 3.5% or less, Mn = 3.0% or less, P = 0.15% or less, S = 0.015% or less, Al = 0.005 to 1.8%, N = 0.0040%, O = 0.0005 to 0.02
%, Nb = 0.002-0.06%, Ti is contained so that Ti = 0.001-0.008% or Ti = 0.04-0.2%, and further Y = 0.5 ×
When Si (%) + Al (%)-0.3 × Mn (%) + 0.4 × P (%), Y ≤ 0.
9 contains Si, Al, Mn, and P, and has a chemical composition consisting of the balance of Fe and unavoidable impurities. A steel sheet having excellent magnetic properties, characterized by having an X-ray random intensity ratio of a {100} plane parallel to that of the steel sheet exceeding 4.0 and a sheet thickness of 0.7 mm or less. 5. B = 0.0002 to 0.0040%, V = 0.00% by weight
2 to 0.1%, W = 0.002 to 0.1%, Mo = 0.003 to 0.4%, Sn = 0.002
~ 0.3%, Cu = 0.005 ~ less than 0.3%, Cr = 0.005 ~ 0.4% and Ni
5. The steel sheet having excellent magnetic properties according to claim 1, comprising one or more of 0.005 to 0.3%. 6. 6. A slab having the chemical composition according to any one of claims 1 to 5, which is hot-rolled to obtain ((Ac ₁ + Ac ₃ ) / 2).
A method for producing a steel sheet having excellent magnetic properties, wherein the steel sheet is maintained at a temperature of not less than 10 ° C. for less than 10 minutes. 7. A slab having the chemical composition according to any one of claims 1 to 5, which is hot-rolled, cold-rolled at a rolling reduction of 99% or less, and ((Ac ₁ + Ac ₃ ) / 2) 10 ° C or higher
A method for producing a steel sheet having excellent magnetic properties, wherein the steel sheet is heated for less than one minute. 8. A slab having the chemical composition according to any one of claims 1 to 5, which is hot-rolled and held in an α single phase region for 5 seconds to 10 minutes, and then ((Ac ₁ + Ac ₃ ) / 2) A method for producing a steel sheet having excellent magnetic properties, wherein the steel sheet is heated to a temperature of not less than ° C and held for less than 10 minutes. 9. A slab having the chemical composition according to any one of claims 1 to 5, which is hot-rolled, cold-rolled at a rolling reduction of 99% or less, and at least 5 seconds in the α single phase region. After holding for 10 minutes or less, heat to a temperature of ((Ac ₁ + Ac ₃ ) / 2) ° C. or more,
A method for producing a steel sheet having excellent magnetic properties, wherein the steel sheet is held for less than 10 minutes.