JP6891673B2 - Non-oriented electrical steel sheet and its manufacturing method - Google Patents

Description

The present invention relates to a non-oriented electrical steel sheet and a method for producing the same, and more particularly to a non-oriented electrical steel sheet having excellent iron loss and a method for producing the same, which is used as an iron core material of an electric device.

Non-oriented electrical steel sheets are used as iron core materials for various motors for heavy electrical equipment and home appliances. Non-oriented electrical steel sheets are commercially graded according to iron loss, and are used properly according to the design characteristics of motors and transformers.

In recent years, from the viewpoint of energy saving, there is a strong demand for further reduction of iron loss in non-oriented electrical steel sheets. In general, the presence of fine precipitates in a steel sheet hinders domain wall movement and deteriorates hysteresis loss. Therefore, conventionally, for the purpose of improving iron loss of non-oriented electrical steel sheets, control of sulfide precipitation in hot rolling, method of reducing sulfide by desulfurization, suppression of Cu sulfide precipitation by rapid cooling after finish annealing, etc. Method has been proposed.

For example, in Patent Document 1, a steel piece containing 0.2% or less of Cu is held in the range of 900 to 1100 ° C. for 30 minutes or more, then held at a high temperature of 1150 ° C., and then rolling is started and finished. A method of controlling the dispersed state of Cu sulfide to the magnetic properties of non-oriented electrical steel sheets, that is, a state preferable for iron loss and magnetic flux density by suppressing the cooling rate during hot rolling to 50 ° C./sec or less is disclosed. ing.

In Patent Document 2, CaSi is added to the molten steel by the time the casting is completed, the S content is controlled to 0.005% or less, the slab is heated at a temperature of 1000 ° C. or higher, and then hot-rolled to a specific temperature. A method of avoiding the formation of fine precipitates by winding the coil in the region is disclosed.

Further, Patent Document 3 discloses a technique for suppressing precipitation of Cu sulfide by rapidly cooling from a temperature range of 500 to 600 ° C. to 300 ° C. at a cooling rate of 10 to 50 ° C./sec after finish annealing. ing.

Patent Documents 4 to 7 disclose techniques expected to improve magnetic characteristics by controlling the cooling rate after finish annealing.

Japanese Unexamined Patent Publication No. 2010-174376 Japanese Unexamined Patent Publication No. 10-183244 Japanese Unexamined Patent Publication No. 09-302414 Japanese Unexamined Patent Publication No. 2011-006721 Japanese Unexamined Patent Publication No. 2006-144036 Japanese Unexamined Patent Publication No. 2003-113451 International Publication No. 2014/168136

CAMP-ISIJ Vol. 25 (2012), p1080 CAMP-ISIJ Vol. 22 (2009), p1284 Tetsu-to-Hagane (TETSU-2016-069) Tetsu-to-Hagane vol. 100 (2014), p1229 Tetsu-to-Hagane vol. 83 (1997), p479 Tetsu-to-Hagane vol. 92 (2006), p618 Analysis vol. 11 (2002), p639

However, the conventional methods described in Patent Documents 1 to 7 have the following problems. The method described in Patent Document 1 has problems in productivity such as an increase in rolling load due to a low slab heating temperature and difficulty in strict control of a cooling rate.

Further, although high-purity steel is indispensable in the method described in Patent Document 2, the formation of fine Cu sulfide by Cu mixed at an unavoidable level is unavoidable, so that there is a problem that the magnetic characteristics are rather deteriorated by Cu mixing. there were.

Further, Patent Document 3 discloses a method of rapidly cooling from a temperature range of 500 to 600 ° C. to 300 ° C. at a cooling rate of 10 to 50 ° C./sec, but Cu sulfide is 50 ° C./sec or more. It is known in Non-Patent Documents 1 and 2 that even at the cooling rate of the above, precipitation occurs during cooling. That is, it is difficult to completely suppress the precipitation of Cu sulfide by the technique of Patent Document 3 which cools at about 10 to 50 ° C./sec.

Further, in Patent Documents 4 to 6, it is possible to avoid the introduction of cooling strain into the steel sheet by the above-mentioned method and reduce the deterioration of iron loss, but it is not possible to control the precipitation state of Cu sulfide. The finely precipitated Cu sulfide adversely affects the magnetic properties.
Further, Patent Document 7 discloses a technique for controlling the precipitation form of Cu sulfide, but there is a problem that it becomes difficult to detoxify Cu sulfide when a precipitate other than Cu sulfide is present. ..

In view of the above problems, the present invention provides a non-oriented electrical steel sheet having excellent iron loss and a method for producing the same, without controlling the precipitation form of Cu sulfide and causing an increase in cost and a decrease in productivity. The purpose is.

In order to solve the above problems, the present invention has repeatedly studied the effects of steel sheet components and manufacturing conditions on the relationship between the dispersed state of sulfide and the magnetic properties. As a result, when a non-directional electromagnetic steel plate containing an oxide having a Cubic crystal structure ( _{one or more of SiO 2} , MgO, TiO, Mn ₂ O ₃ , and Al ₂ O _{3) is annealed under certain conditions.} In addition, it was recognized that the fine dispersion of Cu sulfide was suppressed and the magnetic properties were significantly improved. As a result of conducting a detailed investigation on the morphology and structure of the precipitates in the steel, this phenomenon is caused by the composite precipitation of Cu sulfide with the Cubic type oxide, thereby avoiding the single dispersion of (A) Cu sulfide. It was found that (B) Cu sulfide has good lattice consistency with the base metal. Further, when the lattice consistency between the oxide as the precipitation nucleus and the Cu sulfide is optimized, that is, when the crystal structure of (C) Cu sulfide is Hexagonal type, the composite precipitation with the Cubic type oxide occurs. I found that it could happen.

The present invention has been made based on the above findings, and the following (1) to (8) are the gist of the present invention.
(1) That is, the non-directional electromagnetic steel plate according to one aspect of the present invention has a mass% of C: 0.0100% or less, Si: 0.10 to 5.00%, Mn: 0.010 to 2. 000%, Al: 0.10 to 3.00%, S: 0.0001 to 0.0300%, P: 0.0010 to 0.2000%, Cu: 0.005 to 2.000%, N: 0 It contains .0001 to 0.0150%, O: 0.0010 to 0.0200%, Mg: 0.0001 to 0.0100%, Ti: 0.0001 to 0.0100% , Zr: 0.0001. It contains 1 or 2 or more of ~ 0.0100%, has a chemical composition with the balance consisting of Fe and impurities, and has a composite precipitation of Cubic-type oxide and Cu sulfide in the crystal system, and has an average diameter of The number density of the composite precipitates having a diameter of 10 to 5000 nm is 0.001 to 10.000 pieces / μm ² .
_{(2) I 2θ =} which is the diffraction intensity of Cu sulfide having a Hexagonal structure appearing at 2θ = 46.8 ° obtained by X-ray diffraction on the electrolytic extraction residue of the non-directional electromagnetic steel plate according to (1) above. _{46.8 and I 2θ = 32.9,} which is the diffraction intensity of _{Mn 2} O ₃ having a Cubic structure appearing at 2θ = 32.9 °, may satisfy the condition of the following formula 1.
I _{2θ = 46.8} / I _{2θ = 32.9} ≧ 0.10 ... Equation 1
(3) The diffraction intensity of Cu sulfide having a Hexagonal structure appearing at 2θ = 46.8 ° obtained by X-ray diffraction on the electrolytic extraction residue of the non-directional electromagnetic steel plate according to (1) or (2) above. A certain I _{2θ = 46.8 , SiO 2} having a Cubic structure appearing at 2θ = 21.6 °, MgO having a Cubic structure appearing at 2θ = 42.9 °, and having a Cubic structure appearing at 2θ = 43.3 °. _{The diffraction intensity of each of Al 2} O ₃ having a Cubic structure appearing at TiO and 2θ = 45.9 ° may satisfy the condition of the following formula 2.
I _{2θ = 46.8} / (I _{2θ = 21.6} + I _{2θ = 42.9} + I _{2θ = 43.3} + I _{2θ = 45.9} ) ≧ 0.010 ... Equation 2
However, _SiO 2, 2θ = 42 with _{I 2θ = 21.6, I 2θ =} 42.9, I 2θ = 43.3, I 2θ = 45.9 , respectively, Cubic structure appearing at 2 [Theta] = 21.6 ° is the diffraction peak heights of the XRD of the _Al 2 _{O 3} having TiO, a Cubic structure appearing at 2 [Theta] = 45.9 ° with MgO, a Cubic structure appearing at 2 [Theta] = 43.3 ° having a Cubic structure appearing in .9 ° ..
(4) Cu sulfurization having a Cubic structure appearing at 2θ = 32.1 ° obtained by X-ray diffraction on the electrolytic extraction residue of the non-directional electromagnetic steel sheet according to any one of (1) to (3) above. I _2θ = _{32.1 , which is the diffraction intensity of an object, and I 2θ = 46.8} , which is the diffraction intensity of a Cu sulfide having a Hexagonal structure that appears at 2θ = 46.8 °, satisfy the condition of the following formula 3. You may.
I _{2θ = 46.8} / I _{2θ = 32.1} > 0.50 ... Equation 3
(5) The method for producing a non-directional electromagnetic steel sheet according to the present invention includes a hot-rolling step of hot-rolling a steel piece having the chemical composition described in (1) to obtain a hot-rolled steel sheet, and the hot-rolling step. A subsequent pickling step of pickling the hot-rolled steel sheet, a cold-rolling step of cold-rolling the hot-rolled steel sheet after the pickling step to obtain a cold-rolled steel sheet, and a finish of annealing the cold-rolled steel sheet. A method for producing a non-directional electromagnetic steel sheet having a annealing step. In the finishing annealing step, holding is performed at T1 (° C.) or higher shown in the following formula 4 for 10 seconds or more and 3600 seconds or less, and the finishing annealing step is performed. In cooling, the average cooling rate CR1 in the temperature range of T1 (° C.) or lower and T2 (° C.) or higher represented by the following formula 5 is set to less than 60 ° C./sec.
T1 (° C.) = 15000 / (12-log ₁₀ ([% Cu] ² × [% S]))-273 ... Equation 4
T2 (° C.) = 15000 / (12-log ₁₀ ([% Cu] ² × [% S]))-373 ... Equation 5
In the above formula, [% Cu] is the content of Cu in mass%, and [% S] is the content of S in mass%.
(6) The method for manufacturing a non-oriented electrical steel sheet according to (5) above is an average in a temperature range of T3 (° C.) or higher and T2 (° C.) or lower represented by the following formula 6 in the cooling of the finishing annealing step. The cooling rate CR2 may be 20 ° C./sec or higher.
T3 (° C.) = 15000 / (12-log ₁₀ ([% Cu] ² × [% S]))-473 ... Equation 6
In the above formula, [% Cu] is the content of Cu in mass%, and [% S] is the content of S in mass%.
(7) In the method for manufacturing a non-oriented electrical steel sheet according to (5) or (6) above, the steel piece heating temperature in the hot rolling step is set to T4 (° C.) or less according to the following formula 7 and according to the following formula 8. After hot rolling at T5 (° C.) or higher, the winding temperature of the hot rolled plate may be controlled to T6 (° C.) or lower according to the following formula 9.
T4 (° C.) = 15000 / (6-log ₁₀ ([% Mn] × [% O]))-273 ... Equation 7
T5 (° C.) = 14900 / (8-log ₁₀ ([% Mn] × [% S]))-473 ... Equation 8
T6 (° C.) = 14900 / (8-log ₁₀ ([% Mn] × [% S])) −573 ... Equation 9
In the above formula, [% Mn] is the content of Mn in mass%, [% O] is the content of O in mass%, and [% S] is the content of S in mass%. The quantity.
(8) In the method for producing a non-directional electromagnetic steel sheet according to any one of (5) to (7) above, the hot-rolled steel sheet is annealed between the hot-rolling step and the pickling step. A hot-rolled sheet annealing step may be provided.

According to the present invention, even if the non-oriented electrical steel sheet is not subjected to high purification, lowering of the slab heating temperature, optimization of hot rolling conditions, etc., it is possible to avoid single precipitation of fine Cu sulfide and also to avoid single precipitation of fine Cu sulfide. By controlling the precipitation form that has a positive effect on iron loss, it is possible to provide non-oriented electrical steel sheets having excellent iron loss.
According to the present invention, characteristics other than iron loss (magnetic flux density, workability, etc.) required for non-oriented electrical steel sheets can be ensured to be equal to or higher than those of conventional materials.

Hereinafter, the non-oriented electrical steel sheet according to the embodiment of the present invention (hereinafter, may be referred to as the non-oriented electrical steel sheet according to the present embodiment) and the manufacturing method thereof will be described in detail. The% of the content is all mass%.

<Chemical composition>
C: 0.0100% or less If a large amount of C is present, the iron loss is significantly deteriorated by magnetic aging. Therefore, the upper limit of the C content is set to 0.0100% or less. Although the lower limit includes 0%, it is preferable that C is mixed as a trump element at least 0.0001% or more. Considering the avoidance of magnetic aging, the C content is more preferably 0.0001 to 0.0070%. A more preferable C content is 0.0001 to 0.0050%.

Si: 0.10 to 5.00%
If the Si content is less than 0.10%, good iron loss cannot be obtained. Therefore, the lower limit of the Si content is set to 0.10% or more. On the other hand, if the Si content exceeds 5.00%, the brittleness deteriorates and it becomes difficult to pass the plate in the manufacturing process. Therefore, the upper limit of the Si content is set to 5.00% or less. From the viewpoint of magnetism and plate-through property, the Si content is preferably 2.00 to 4.00%, more preferably 2,500 to 3.50%.

Mn: 0.010-2.000%
Since Mn reacts with O to form Mn oxide, it is one of the important elements in the present invention. If a large amount of Mn is present in the steel, by MnS is precipitated, reduces the amount of precipitation of Cu 2 _S, the effect of the present invention can not be enjoyed. Therefore, the upper limit of the Mn content is set to 2.000% or less. On the other hand, if the Mn content is less than 0.010%, the steel sheet becomes embrittled during hot rolling. Therefore, the lower limit of the Mn content is set to 0.010% or more. Preferably, the Mn content is 0.050 to 1.500%, more preferably 0.100 to 1.000%.

Al: 0.10 to 3.00%
If the content of Al is high, the hardness of the steel sheet will increase as in Si, and it will be difficult to pass the sheet in the manufacturing process. Therefore, the upper limit of the Al content is set to 3.00% or less in consideration of productivity. Like Si, Al has the effect of increasing electrical resistance, so the lower limit is set to 0.10% or more. The Al content is preferably 0.25 to 2.00%, more preferably 0.30 to 1.50%.

P: 0.0010 to 0.2000%
P has the effect of increasing the hardness of the steel sheet and improving the punching property. However, if the content exceeds 0.2000%, the hardness of the steel sheet increases, so that the punching die wears faster and the manufacturing cost of the motor iron core increases. Moreover, since the steel plate becomes hard, it becomes difficult to pass the steel plate itself. Therefore, the upper limit of the P content is set to 0.2000% or less. On the other hand, a small amount of P has the effect of improving the magnetic flux density. In order to obtain these effects, the lower limit of the P content is set to 0.0010% or more. The preferred P content is 0.0010 to 0.1500%, more preferably 0.0010 to 0.1000%.

S: 0.0001 to 0.0300%
The S content is directly related to the amount of sulfide. If the S content is excessive, S is present in the steel in a solid solution state, and the steel becomes embrittled during hot rolling. Therefore, the upper limit of the S content is set to 0.0300% or less. On the other hand, in the absence of S, Cu is finely precipitated as metallic Cu, hindering grain growth and causing deterioration of magnetic flux density. Therefore, the lower limit of the S content is set to 0.0001% or more. The Si content is preferably 0.0010 to 0.0100%, more preferably 0.0010 to 0.0050%.

Cu: 0.005-2.000%
Cu is a particularly important element in the present invention because it forms Cu sulfide. If the Cu content is too high, hot brittleness will occur. Therefore, the upper limit of the Cu content is set to 2.000% or less. On the other hand, if the amount of Cu is too small, other fine sulfides such as TiS are precipitated, which causes deterioration of iron loss. Therefore, it is necessary to set the lower limit of the Cu content to 0.005% or more. The Cu content is preferably 0.010 to 1.000%, more preferably 0.010 to 0.500%.

N: 0.0001 to 0.0150%
If N is excessive, the amount of nitride precipitated increases too much, which hinders the growth of crystal grains and deteriorates the magnetic flux density. Therefore, the upper limit of the N content is set to 0.0150% or less. A lower N is preferable if the strength increase due to the nitride is not expected. That is, the lower limit of N includes 0%, but the detection limit of N is 0.0001%. In consideration of this, the lower limit of N is set to 0.0001% or more. The N content is preferably 0.0001 to 0.0050%, more preferably 0.0001 to 0.0030%, for magnetic properties.

O: 0.0010 to 0.0200%
O is an important element in the present invention because it is directly related to the amount of Mn oxide precipitated. If the O content is excessive, a large number of fine oxides are formed, and the magnetic flux density is rather lowered. Therefore, the upper limit of the O content is set to 0.0200% or less. On the other hand, in order to precipitate the Mn oxide and enjoy the effects of the present invention, it is necessary to contain at least 0.0010% or more of O. Therefore, the lower limit of the O content is set to 0.0010% or more. The preferred O content is 0.0010 to 0.0150%, more preferably 0.0050 to 0.0100%.

The non-oriented electrical steel sheet according to the present embodiment may selectively contain one or more of Mg, Ti, and Zr in addition to the above-mentioned elements. When not contained, the lower limit of the content of these elements is 0%. Hereinafter, Mg, Ti, and Zr will be described.

Mg: 0 to 0.0100%
Since the Mg content is directly related to the precipitation amount of MgO, it is an element to be controlled in the present invention. If the amount of Mg is too large, fine MgS is formed in the steel, which hinders the growth of steel sheet grains and causes a decrease in magnetic flux density. Therefore, the upper limit is set to 0.0100% or less. Further, Mg may be contained in an amount of 0.0001% or more. The preferred range of Mg content is 0.0001 to 0.0060%, more preferably 0.0001 to 0.0030%.

Zr: 0-0.0100%
Zr is _{an element that forms ZrO 2} , and since it is possible to further exert the effects of the present invention, it is an element that can be selectively contained. If there is too much Zr, the hot brittleness will worsen. Therefore, the upper limit is set to 0.0100% or less. Further, Zr may be contained in an amount of 0.0001% or more. The preferred range of Zr content is 0.0001 to 0.0060%, more preferably 0.0001 to 0.0030%.

Ti: 0 to 0.0100%
When the Ti content is excessive, fine carbides are formed to suppress grain growth and reduce the magnetic flux density. Therefore, the upper limit of the Ti content is set to 0.0100% or less. Further, Ti may be contained in an amount of 0.0001% or more. The preferred Ti content is 0.0001 to 0.0060%, more preferably 0.0001 to 0.0030%.

The non-oriented electrical steel sheet according to this embodiment basically contains the above-mentioned chemical components and the balance is composed of Fe and impurities. However, Ca, W for the purpose of further improving the magnetic properties, improving the properties required for structural members such as strength, corrosion resistance and fatigue properties, improving castability and plate-passability, and improving productivity by using scraps, etc. , Mo, Nb, V, Sn, Bi, Sb, Ag, Te, Ce, Cr, Co, Ni, In, Se, Re, Os, Hf, Ta, Y, La, etc. It may be contained in the range of 5% or less. Moreover, even if these elements are mixed in the range of 0.5% or less in total, the effect of the present embodiment is not impaired.

<Composite precipitate>
Next, the crystal structure of the oxide, which is an important control factor in the non-oriented electrical steel sheet according to the present embodiment, will be described. It is difficult to completely eliminate the presence of Cu sulfide in a steel sheet. Therefore, in the non-oriented electrical steel sheet according to the present embodiment, the Cubic type oxide is used as a precipitation nucleus to control the Cu sulfide to be compositely precipitated, and a good iron loss is obtained. That is, in the non-directional electromagnetic steel plate according to the present embodiment, the number density (area density) per unit area of the composite precipitate containing Cu and O and having an average diameter of 10 to 5000 nm is 0.001. It is defined as 10.000 pieces / μm ^2. Preferably from 0.001 to 1.000 units / [mu] m ^2, more preferably 0.001 to 0.100 cells / [mu] m ^2, more preferably from 0.001 to 0.010 units / [mu] m ^2. The oxide serving as the precipitation nucleus may have a Cubic type crystal structure, and is, for example, Mn ₂ O ₃ , MgO, TIO, Al ₂ O ₃ , SiO ₂ . If the crystal structure is Cubic, the effect of the present invention can be enjoyed even if the chemical bond ratio of the cation and the anion is different. When the Cubic type oxide is not spherical and rectangular, the average value of the minor axis length and the major axis length is defined as the average diameter of the composite precipitate.

The above-mentioned observation of the composite precipitate containing Cu and O may be carried out by a transmission electron microscope (TEM) or a scanning electron microscope (SEM). The constituent elements of the precipitate can be identified by EDS analysis. Specifically, when EDS analysis is performed on the target precipitate, OKα rays are located at the energy 0.5 ± 0.2 keV position on the horizontal axis of the spectrum, and Cu is located at the position of 8.0 ± 0.2 keV. -Kα rays may be detected at the same time. Element identification may be performed by Lα ray or Kγ ray in addition to Kα ray. However, when the extracted replica is used as an observation sample of TEM-EDS, it is necessary to separate the signal of the mesh on which the Cu sulfide and the replica are placed, so the use of the Cu mesh must be avoided. Further, it is known that a small amount of Mn or Fe is dissolved in Cu sulfide, and even if an EDS signal derived from Mn, S or Fe is detected in the precipitate to be analyzed as a result of EDS analysis, the present invention It does not lose its effect. The origin of the EDS signal does not matter, such as Kα ray, Lα ray, and Kγ ray. Further, since Al-Mg-O and Al-Si-O form a composite oxide, a plurality of metal atoms are detected by EDS from the oxide, but the effect of the present invention is not lost.

The crystal structure of the oxide can be identified by transmission electron microscopy (TEM) observation and electron diffraction of the precipitate. In the composite precipitate, the crystal structure of Cu sulfide has a Hexagonal structure. However, although the crystal structure of the oxide can be identified by electron diffraction by TEM, the crystal structure of Cu sulfide cannot be identified. Have difficulty. This is because the diffraction intensity of the oxide, which is the precipitated nucleus, is strong, and the electron diffraction derived from Cu sulfide becomes unclear.

The crystal structure of Cu sulfide can be identified by X-ray diffraction (XRD). Generally, X-ray diffraction uses Cu-Kα rays as a probe. In the non-directional electromagnetic steel sheet according to the present embodiment, for example, a Cu sulfide having a Hexagonal structure that appears at 2θ = 46.8 ° when X-ray diffraction (XRD) is performed on the electrolytic extraction residue of the steel sheet. and _{I 2 [Theta] = 46.8} is a diffraction intensity, and _{I 2 [Theta] = 32.9} which is the diffraction intensity _Mn 2 _{O 3} having a Cubic structure appearing at 2 [Theta] = 32.9 °, satisfies the following formula 1 It is preferable to control as such. There are a plurality of metal oxides such as MgO, SiO ₂ , and Al ₂ O _{3 , but Mn 2} O ₃ has the best crystal consistency with Cu sulfide and is easy to complex precipitate. There is a limit to the amount of Cu sulfide that can be compound-precipitated with respect to the amount of Mn oxide, and if it exceeds that amount, Cu sulfide may be finely precipitated independently. Therefore, _{the upper limit of I 2θ = 46.8} / I _{2θ = 32.9} is more preferably 10.00 or less. A more preferable range of I _{2θ = 46.8} / I _{2θ = 32.9} is 0.50 or more and 10.00 or less.

I _{2θ = 46.8} / I _{2θ = 32.9} ≧ 0.10 ... Equation 1

Further, in the non-oriented electrical steel sheet according to the present embodiment, SiO ₂ having a Cubic structure appearing at 2θ = 21.6 ° and Cubic structure appearing at 2θ = 42.9 ° as oxides other than Mn oxide. and MgO having a TiO having a Cubic structure appearing at 2 [Theta] = 43.3 °, the _Al 2 _{O 3} having Cubic structure appearing at 2 [Theta] = 45.9 °, controlled to so as to satisfy the condition of the following formula 2 May be good. The crystal structure of Cu sulfide capable of complex precipitation with a Cubic type oxide is a hexagonal structure. This is due to the good lattice consistency between the Cubic type oxide and the Hexagonal type Cu sulfide. _{That is, the greater the diffraction intensity of I 2θ = 46.8,} which is the diffraction intensity of Hexagonal-type Cu sulfide, the more the Cu sulfide is complex-precipitated. Therefore, basically, I _{2θ = 46.8} / (I). _{The larger 2θ = 21.6} + I _{2θ = 42.9} + I _{2θ = 43.3} + I _{2θ = 45.9} ), the more the invention effect can be obtained. Therefore, although there is no upper limit to this value, there is a limit to the amount of Cu sulfide that can be compound-precipitated with respect to the amount of any oxide, and if it exceeds that value, Cu sulfide may be finely precipitated independently. There is. Therefore, _{the upper limit of I 2θ = 46.8} / (I _{2θ = 21.6} + I _{2θ = 42.9} + I _{2θ = 43.3} + I _{2θ = 45.9} ) is preferably 1.000 or less. More preferable ranges of I _{2θ = 46.8} / (I _{2θ = 21.6} + I _{2θ = 42.9} + I _{2θ = 43.3} + I _{2θ = 45.9} ) are 0.100 or more and 1.000 or less. To do.

I _{2θ = 46.8} / (I _{2θ = 21.6} + I _{2θ = 42.9} + I _{2θ = 43.3} + I _{2θ = 45.9} ) ≧ 0.010 ... Equation 2

Further, the present inventors have found that the Cu sulfide structure in steel has a Cubic structure in addition to the Hexagonal structure. Since the Cubic-type Cu sulfide does not complexly precipitate with the Cubic-type oxide, in the non-directional electromagnetic steel plate according to the present embodiment, the Cu sulfide having a Cubic structure is compared with the Cu sulfide having a Hexagonal structure. It is preferable that the abundance thereof is small. _{Therefore, I 2θ = 32.1} , which is the diffraction intensity of the Cu sulfide having a Cubic structure appearing at 2θ = 32.1 °, and the diffraction intensity of the Cu sulfide having a Hexagonal structure appearing at 2θ = 46.8 °. It is preferable that I _{2θ = 46.8} satisfies the condition of the following equation 3. Since the effect of the present invention can be enjoyed as the amount of Cu sulfide in the Cubic structure is small, and because _{there is an optimum balance in I 2θ = 46.8} / I _{2θ = 32.1} , the preferable range is 10.00 or more. It is 50.00 or less.

I _{2θ = 46.8} / I _{2θ = 32.1} > 0.50 ... Equation 3

In XRD diffraction, a diffraction peak is observed at a specific 2θ position according to the crystal structure of the sample. However, the crystal lattice of the precipitate in the steel material fluctuates due to various factors such as Fe solid solution to the precipitate and lattice consistency with the ground iron matrix. Along with this, the value of 2θ in which diffraction appears includes at least ± 3 ° within the margin of error. The identification of the crystal structure may be collated using JCPDS-CARD, which is a database of crystal lattices, but for Cu sulfide (Hexagonal), there are 23-958, 26-1116, and 46-119536-0379. On the other hand, Cu sulfides (Cubic) include JCPDS-CARD: 00-012-0174, 00-024-0061, 023-0962, 053-0522, 33-0491, 33-0492, 070-9133 and the like. 31-0825 for Mn ₂ O ₃ , 27-0605 for SiO ₂ , 04-0829 for MgO, 10-0425 for Al ₂ O ₃ , 08-0117 for TiO, 01-075-1090 for MnO It can be identified by.

In particular, in the case of Cu sulfide, Cu ₉ Fe ₉ S ₁₆ (JCPDS: 00-027-0165) and Cu ₅ FeS ₄ (JCPDS: 024-0050, 089-2620) are partially replaced by Fe and S. Precipitates such as CuFe ₂ S ₃ (JCPDS: 027-0166) and CuFeS ₂ (JCPDS: 075-0253, 041-1404) are formed, and such Cu-Fe-S compounds are also crystalline. Is a Cubic structure, and if a diffraction peak is observed at 2θ = 32.1 ° ± 3 °, it can be defined as _{I 2θ = 32.1.} In the above error range, when two or more diffraction peaks are present for each of Cu sulfide (Cubic) and Cu sulfide (Hexagonal), Cu sulfide (Cubic) is a Cu sulfide (Cubic). The sum of the peak intensities may be I _{2θ = 32.1} , and the Cu sulfide (Hexagonal) may be the sum of the peak intensities of the Cu sulfide (Hexagonal) as I _{2θ = 46.8} .

In addition to the above, the effect of the present invention can naturally be enjoyed as long as the precipitate is within the error range of 2θ ± 3 °. However, it is necessary to determine whether or not a precipitate having such a crystal structure actually exists by observing with an electron microscope or the like, EDS elemental analysis, and electron diffraction. This is because it is not always the case that there is no completely different precipitate having a diffraction peak at the same 2θ position.

In general, the XRD diffraction intensity is the height from the background to the peak of the spectrum. Ideally, the background intensity is low enough that it does not need to be removed, but if the diffraction intensity from the precipitate is weak, the background intensity may be relatively high. In such a case, it is necessary to remove the background by using XRD analysis software as described in Non-Patent Documents 3 and 4. The XRD diffraction intensity (peak intensity) in the present embodiment may also be obtained by removing the background using software in the same manner.

<Manufacturing method>
Next, a method for manufacturing the non-oriented electrical steel sheet according to the present embodiment will be described.
The non-oriented electrical steel sheet according to the present embodiment is melted in a converter in the same manner as a normal electrical steel sheet so as to have the above-mentioned composition, and is hot-rolled and hot-rolled and annealed on continuously cast steel pieces. , Can be manufactured by cold rolling, finish annealing, etc.

In the non-oriented electrical steel sheet according to the present embodiment, Cu sulfide and Cubic type oxide are compositely precipitated to obtain the effect of improving iron loss. In general, Cu sulfide has a high precipitation rate, and even if it is solid-solved by finish annealing, it is finely reprecipitated by itself during subsequent cooling, which adversely affects iron loss. However, if a Cubic-type oxide is present at the start of cooling, the Cu sulfide is complex-precipitated with the Cubic-type oxide as a nucleus during cooling. As a result, fine precipitation of Cu sulfide can be suppressed. Therefore, the Cubic-type oxide is precipitated before the pre-step of the finish annealing step, and in the finish-annealing step, the Cu sulfide is solid-dissolved and the cooling rate is controlled to control the Cubic-type oxide at the start of cooling. And Cu sulfide can be compound-precipitated.

In the present embodiment, the holding temperature, holding time, and cooling in a predetermined temperature range (between T1 to T2 (° C.) below) in the finish annealing step are performed under the conditions shown below. Further, in order to further improve the magnetic characteristics, it is preferable to carry out the hot-rolling step, the coil winding after the hot-rolling step, and the hot-rolled plate annealing step after the hot-rolling step and before the pickling step under the conditions shown below.
In the present embodiment, the pickling after the hot rolling process is not particularly limited. Further, the cold rolling is not particularly limited, and the iron loss improving effect can be enjoyed regardless of the cold rolling method such as cold rolling or warm rolling twice or more and the cold rolling reduction rate. Further, in addition to these steps, a step of forming an insulating film, a step of decarburizing, etc. may be performed.

(Finishing annealing process)
In the finishing annealing step, T1 (° C.) described in the following formula 4 and T2 (° C.) described in the following formula 5 and T3 (° C.) described in the following formula 6 have important meanings. The following T1 (° C.) is the solid dissolution temperature of Cu sulfide, the following T2 (° C.) is the lower limit temperature at which Hexagonal type Cu sulfide is precipitated and the upper limit temperature at which Cubic type Cu sulfide is precipitated, and the following T3 (° C.) ) Is the lower limit temperature at which Cubic type Cu sulfide is precipitated.

T1 (° C.) = 15000 / (12-log ₁₀ ([% Cu] ² × [% S]))-273 ... Equation 4
T2 (° C.) = 15000 / (12-log ₁₀ ([% Cu] ² × [% S]))-373 ... Equation 5
T3 (° C.) = 15000 / (12-log ₁₀ ([% Cu] ² × [% S]))-473 ... Equation 6

In the finish annealing step, by holding the Cu sulfide at the above-mentioned T1 (° C.) or higher, which is the solid solution temperature thereof, it is possible to dissolve the entire amount of the Cu sulfide. If the holding temperature is less than T1 (° C.), Cu sulfide cannot be dissolved as a solid solution. The holding temperature is preferably equal to or lower than the solid solution temperature of the oxide. _{The solid solution temperature of Mn 2} O ₃ , MgO, TiO, Al ₂ O ₃ , and SiO ₂ related to the present invention is high, and is generally 1250 ° C. or higher. Therefore, the holding temperature is T1 ° C. or higher and 1250 ° C. or lower, which is a preferable range for magnetism. A more preferable holding temperature for magnetism is (T1 + 200) ° C. or higher and 1100 ° C. or lower.

The holding time in the finish annealing step is 10 seconds or more and 3600 seconds or less. If the holding time is less than 10 seconds, the solid solution of Cu sulfide does not proceed sufficiently. On the other hand, if the holding time exceeds 3600 seconds, other fine sulfides such as TiS having a slow precipitation rate are generated, which adversely affects the improvement of iron loss. The preferred holding time in the finish annealing step is 20 seconds or more and 200 seconds or less.

Controlling the cooling rate in the finish annealing step is also an important control factor in the present invention. Since Cu sulfide has a high precipitation rate, it precipitates during the cooling step after finish annealing. However, it is known that there is a temperature range in which Cu sulfide forms a Hexagonal type crystal structure and a temperature range in which a Cubic type crystal structure is formed. Hexagonal-type Cu sulfide is compound-precipitated with the above-mentioned Cubic-type oxide. That is, as a cooling step after finish annealing, it is important to slow down the cooling rate in the temperature range where Cu sulfide (Hexagonal) is precipitated to secure a longer staying time in the temperature range. That is, the average cooling rate CR1 (° C./sec) between T1 and T2 (° C.) is controlled to be less than 60 ° C./sec. The smaller the average cooling rate CR1 between T1 and T2 (° C.), the greater the effect of the present invention, but natural air cooling is realistic in actual manufacturing, and in that case, the average cooling rate is limited to 0.01 ° C./sec. Is. Therefore, the lower limit of the average cooling rate CR1 between T1 and T2 (° C.) is preferably 0.01 ° C./sec or more. The preferred range of the average cooling rate CR1 is 0.01 ° C./sec or more and 40 ° C./sec or less.

Further, Cu sulfide having a Cubic type crystal structure precipitates in the temperature range between T2 and T3 (° C.). Therefore, in the present embodiment, the iron loss may be further improved by increasing the cooling rate in the precipitation temperature range of Cu sulfide having a Cubic type crystal structure and shortening the residence time in the temperature range. Specifically, rapid cooling may be performed so that the average cooling rate CR2 (° C./sec) in the temperature range between T2 and T3 (° C.) is 20 ° C./sec or more. However, the larger the average cooling rate CR2 (° C./sec), the higher the effect of the present invention, but considering the influence of the cooling strain introduced into the steel sheet, the upper limit of the average cooling rate CR2 (° C./sec) is 200. It is necessary to control to ℃ / sec or less. The preferred range of the average cooling rate CR2 (° C./sec) is 50 ° C./sec or more and 100 ° C./sec or less.

(Hot rolling process)
In this embodiment, since the oxide is used as a precipitation nucleus, it is preferable to precipitate as much Cubic-type oxide as possible before the pre-process of the finish annealing step. In particular, it is preferable to precipitate a large amount of Mn oxide having good lattice consistency with Cu sulfide to avoid precipitation of Mn sulfide. For that purpose, first, in the hot rolling step, the heating temperature of the steel piece is T4 (° C.) or less, which is the solid solution temperature of Mn oxide, and the temperature at which fine MnS is solid solution, according to the following formula 8. It is preferable to control and maintain T5 (° C.) or higher. The complete solid solution temperature of MnS is about T5 + 200 ° C., but since coarse MnS in the steel piece has almost no adverse effect on magnetism, the present invention is made by setting the heating temperature of the steel piece to T5 (° C.) or higher. You can enjoy the effect of.

T4 (° C.) = 15000 / (6-log ₁₀ ([% Mn] × [% O]))-273 ... Equation 7
T5 (° C.) = 14900 / (8-log ₁₀ ([% Mn] × [% S]))-473 ... Equation 8

In the hot rolling step, the holding time for heating the steel pieces is preferably 1200 seconds or more in order to completely dissolve MnS. If the holding time is less than 1200 seconds, MnS does not dissolve sufficiently. On the other hand, the upper limit of the holding time for heating the steel piece is preferably 18,000 seconds or less from the viewpoint of productivity. A more preferable holding time for heating the steel piece is 2400 seconds or more and 10000 seconds or less.

Further, since precipitation of MnS is to inhibit the precipitation of Cu 2 _S, T6 (℃) of formula 9 wherein a coil coiling temperature after hot rolling process is a precipitation minimum temperature of MnS may be less. Since the winding temperature is defined by the heating temperature of the steel piece and the cooling rate of the hot-rolled coil, if the temperature is controlled to 500 ° C. or lower, the temperature unevenness in the coil becomes large, which is not preferable from the viewpoint of magnetism. Therefore, the control range of the coil winding temperature is preferably 500 ° C. or higher and T6 (° C.) or lower. A more preferable upper limit is T3 (° C.) or lower.

T6 (° C.) = 14900 / (8-log ₁₀ ([% Mn] × [% S])) −573 ... Equation 9

(Hot rolled plate annealing process)
By annealing the hot-rolled sheet before cold rolling, it is possible to make the temperature deviation and the variation in the dispersion state of the precipitates uniform in the hot rolling and improve the iron loss. Since the effect of the present invention can be further exhibited by solid-solving the undissolved fine MnS and precipitating the Mn oxide, it is preferable for magnetism to keep the temperature above T5 (° C.) in the hot-rolled plate annealing step. _{The solid solution temperature of Mn 2} O ₃ , MgO, TiO, Al ₂ O ₃ , and SiO ₂ related to the present invention is generally 1250 ° C. or higher. Therefore, in order to avoid dissolution of the oxide, it is preferable to set the holding temperature in the hot rolled sheet annealing step to 1250 ° C. or lower. More preferably for magnetism, it is held at T5 + 100-1250 ° C.

Further, in the cooling after annealing the hot-rolled plate, the cooling rate in the temperature range of T5 (° C.) or lower and T1 (° C.) or higher, which is the precipitation temperature range of MnS, is controlled to 20 ° C./sec or more, and Mn sulfurization is performed. It is preferable to avoid precipitation of substances. More preferable cooling rates are 50 ° C./sec or more and 100 ° C./sec or less.

The holding time in the hot-rolled sheet annealing step is not particularly specified, but the effect of hot-rolled sheet annealing can be sufficiently obtained by setting it to 10 seconds or more and 3600 seconds or less. On the other hand, if the holding time exceeds 3600 seconds, other fine sulfides such as TiS having a slow precipitation rate are generated, which adversely affects the improvement of iron loss. More preferable holding time is 20 seconds or more and 200 seconds or less.

Hereinafter, the technical contents of the present invention will be further described with reference to examples of the present invention. The conditions in the examples shown below are one condition example adopted for confirming the feasibility and effect of the present invention, and the present invention is not limited to this one condition example. Further, the present invention can adopt various conditions as long as the gist of the present invention is not deviated and the object of the present invention is achieved. The underline in the table used in the following description indicates that it is outside the scope of the present invention.

<Example 1>
The ingots of the components shown in Table 1 (Steel Nos. A1 to A27, Steel Nos. a1 to a15) are vacuum-melted, heated to 1200 ° C. and held for 3600 seconds, and then heated so that the winding temperature becomes 700 ° C. After rolling for a while, a hot-rolled steel sheet having a plate thickness of 2.0 mm was obtained. Then, it was pickled and cold-rolled at a reduction ratio of 75% to obtain a cold-rolled steel sheet having a plate thickness of 0.50 mm. Subsequently, finish annealing was performed at 1000 ° C. for 30 seconds. In the cooling after finish annealing, the average cooling rate CR1 between T1 to T2 (° C.) was set to 30 ° C./sec, and the average cooling rate CR2 between T2 to T3 (° C.) was set to 18 ° C./sec. In addition, steel No. A24 is a reference example.

Table 2 shows the observation results of the precipitates and the magnetic characteristics (magnetic flux density and iron loss). Of the observed Cu sulfides, when the number ratio of Cu sulfides complex-precipitated with the oxide is 50% or more, it is indicated by "○" in the "precipitation form" column in the table, and 50%. If it is less than, it is indicated by "x". The deposit was observed by etching a cross section perpendicular to the rolling direction of the steel sheet, observing by SEM observation, and identifying by EDS analysis. At that time, 10 visual fields of ^{100 μm 2 were observed.} The total number of composite precipitates with an average diameter of 10 to 5000 nm including O and Cu observed ^{divided by 1000 (100 μm 2} × 10 field of view) is divided by the number density of composite precipitates (pieces / μm ² ). That is, the surface density was used. In addition, what is described as "-" in the table indicates that it has not been evaluated.

Regarding the magnetic characteristics, VG: very excellent, G: excellent, F: effective, B: evaluated as the conventional level, and those evaluated as B were rejected according to the iron loss. The magnetic characteristics were evaluated according to JIS C 2550: 2000. Strain removal annealing has not been carried out. For iron loss, W _15/50 (W / kg) was evaluated. W _15/50 is the iron loss when the frequency is 50 Hz and the maximum magnetic flux density is 1.5 T. The magnetic flux density was evaluated using _{B 50.} B ₅₀ indicates the magnetic flux density at a magnetic field strength of 5000 A / m. The minimum target value of B ₅₀ was set to 1.50 T or more, which is equivalent to that of the conventional material, and those less than 1.50 T were rejected. The iron loss evaluation criteria for the sample were as follows.

VG (VeryGood): W _15/50 (W / kg) <3.00
G (Good): 3.00 ≤ W _15/50 (W / kg) ≤ 3.40
F (Fair): 3.40 <W _15/50 (W / kg) ≤ 4.50
B (Bad): 4.50 <W _15/50 (W / kg)

No. in Table 2 B1 to B27 are all invention steels, and the magnetic flux densities satisfy the target values, and the iron loss evaluation is "G", which is a good result. In addition, No. B24 is a reference example.
Comparative steel No. The average diameter of b2 and b6 is 10 to 5000 nm, the number density (area density) of the composite precipitate of Cu sulfide and oxide exceeds the invention range, and the iron loss exceeds 4.50 W / kg. Since it was a bad value, the evaluation was set to "B" and it was judged to be unacceptable.
No. In b8, b11 and b15, the magnetic flux density B ₅₀ was less than 1.50 T in the first place, and since it did not reach the target value, it was judged to be unacceptable, and the precipitate was not observed.
No. In b5, b12, and b14, the number ratio of Cu sulfide that was complex-precipitated with the Cubic-type oxide was less than 50% among the observed Cu sulfides, and the composite precipitate of Cu sulfide and oxide was formed. Was not obtained, and the iron loss showed a bad value exceeding 4.50 W / kg. Therefore, the evaluation was set to "B" and it was judged to be unacceptable.
No. Since b1 showed magnetic aging, it was judged to be unacceptable.
No. b3, b4, b7, b9, b10, and b13 were judged to be unacceptable because hot rolling or cold rolling was difficult.

<Example 2>
No. shown in Table 1. The ingots of the components shown in A14, A15, A18 to A21, and A23 to A27 are vacuum-dissolved, the ingot is heated at 1100 ° C., held at each temperature for 4500 seconds, and then the winding temperature becomes 480 ° C. Hot-rolled to obtain a hot-rolled steel sheet having a plate thickness of 2.0 mm. Then, it was pickled and cold-rolled at a reduction ratio of 75% to obtain a cold-rolled steel sheet having a plate thickness of 0.50 mm. Subsequently, finish annealing was performed at 950 ° C. for 60 seconds. In cooling, the average cooling rate CR1 between T1 and T2 (° C.) was set to 38 ° C./sec. The average cooling rate CR2 between T2 and T3 (° C.) was set to 30 ° C./sec.

Table 3 shows the X-ray diffraction results, the precipitation morphology of the precipitates, and the evaluation results of the magnetic characteristics (magnetic flux density and iron loss). The same evaluation as in Example 1 was carried out for the observation of the precipitate and the measurement of the magnetic characteristics. For X-ray diffraction, a sample in which only inclusions were collected by a filter by the general extraction residue method described in Non-Patent Documents 5 to 7 was used as an analysis sample. The XRD measurement was performed by wide-angle X-ray diffraction using the CuKα ray described in Non-Patent Documents 4 to 6 as a probe. “I _CuS / I _Mn2O3 ” in _{Table 3 indicates I 2θ = 46.8} / I _{2θ = 32.9} .

No. C1 to C7, C9 to C11 are both Ri invention example der, No. C8 is Ru Reference Example der. No. In C7 to C11, the number density of the composite precipitate is within a preferable range (0.001 to 1.000 pieces / μm ² ), and _{the value of “I CuS} / I _Mn2O3 ” is controlled to 0.10 or more. Therefore, a particularly good iron loss was obtained.

<Example 3>
Steel No. shown in Table 1. The ingot containing the components A7, A11, A18 to A27 is vacuum-melted, heated at 1200 ° C., held at each temperature for 3600 seconds, and then hot-rolled so that the winding temperature becomes 750 ° C. A hot-rolled plate having a plate thickness of 2.0 mm was obtained. Then, it was pickled and cold-rolled at a reduction ratio of 75% to obtain a cold-rolled steel sheet having a plate thickness of 0.50 mm. Subsequently, finish annealing was performed at 950 ° C. for 60 seconds. In the cooling after finish annealing, the average cooling rate CR1 between T1 and T2 (° C.) was 42 ° C./sec, and the average cooling rate CR2 between T2 and T3 (° C.) was 25 ° C./sec.

Table 4 shows the X-ray diffraction results, the precipitation morphology of the precipitates, and the evaluation results of the magnetic characteristics (magnetic flux density and iron loss). The same evaluations as in Example 1 and Example 2 were performed for X-ray diffraction, measurement of magnetic properties, and measurement of precipitates. “I _CuS / I _Mn2O3 ” in _{Table 4 indicates I 2θ = 46.8} / I _{2θ = 32.9} , and “I _{CuS (Hex)} / I _Oxide ” indicates I _{2θ = 46.8} / (I). _{2θ = 21.6} + I _{2θ = 42.9} + I _{2θ = 43.3} + I _{2θ = 45.9} ).

No. D1~ D8, D10~ D12 Both Inventive Example der Ri, No. D9 is Ru Reference Example der but, No. D9 to D11 are outside the range where the number density of the composite precipitate is preferable (0.001 to 1.000 pieces / μm ² _{), and the value of I CuS} / I _Mn2O3 is less than 0.10. Compared with D1 to D8 and D12 in which the number density of the composite precipitate is within the preferable range (0.001 to 1.000 pieces / μm ² ) and _{the value of I CuS} / I _{Mn2O3 is 0.10 or more.} The iron loss was a little inferior. No. In D7, _{the value of I CuS (Hex)} / I _Oxide was less than 0.010, but the value of I _CuS / I _Mn2O3 was 0.10 or more, so the iron loss was "G", which was relatively good. It was a good result.

<Example 4>
Steel No. shown in Table 1. Ingots containing the components A15 to A23 and A27 are vacuum-melted, heated at 1200 ° C. and held for 3600 seconds, then hot-rolled to a winding temperature of 580 ° C. and hot-rolled to a plate thickness of 2.0 mm. It was made into a board. The hot-rolled plate was annealed at 1100 ° C. for 50 seconds. Then, all the hot-rolled sheets were pickled and cold-rolled at a reduction ratio of 75% to obtain a cold-rolled steel sheet having a plate thickness of 0.50 mm, and finish annealing was performed at 1000 ° C. for 40 seconds. In cooling, the average cooling rate CR1 between T1 to T2 (° C.) was set to 32 ° C./sec. The average cooling rate CR2 between T2 and T3 (° C.) was set to 55 ° C./sec.

Table 5 shows the X-ray diffraction results, the precipitation morphology of the precipitates, and the evaluation results of the magnetic characteristics (magnetic flux density and iron loss). The same evaluations as in Example 1 and Example 2 were performed for X-ray diffraction, measurement of magnetic properties, and measurement of precipitates. In Table 5, "I _CuS / I _Mn2O3 " indicates I _{2θ = 46.8} / I _{2θ = 32.9} , and "I _{CuS (Hex)} / I _Oxide " indicates I _{2θ = 46.8} /. (I _{2θ = 21.6} + I _{2θ = 42.9} + I _{2θ = 43.3} + I _{2θ = 45.9} ), and "I _{CuS (Hex)} / I _{CuS (Cub)} " is I _{2θ = 46.8.} / I _{2θ = 32.1} .

No. Each of E1 to E10 is an example of the invention, and the holding time of hot-rolled sheet annealing is controlled within a more preferable range (20 to 200 seconds). No. E2 to E7 and No. Since E9~E10 is the number density is preferably in the range of complex precipitates (0.001 to 1.000 cells / [mu] m ²⁾ or more preferred range (0.001 to 0.100 pieces / μm ^2), core loss It was a good value of "VG". No. In E1, _{the value of I CuS (Hex)} / I _Oxide was less than 0.010, but the number density of the composite precipitate was within the more preferable range (0.001 to 0.100 / μm ² ). Due to the control, the iron loss was a good value of "VG". No. The I _{CuS (Hex)} / I _{CuS (Cub)} of E8 was 0.50 or less, but the iron loss was as good as "VG" because the number density of the composite precipitates was controlled within a more preferable range. It was a value.

<Example 5>
Steel No. shown in Table 1. The ingot containing the components A15 and A27 is vacuum-melted, heated to 1200 ° C. and held for 3600 seconds, and then hot-rolled so that the winding temperature becomes 490 ° C. And said. Then, it was pickled and cold-rolled at a reduction ratio of 75% to obtain a cold-rolled steel sheet having a plate thickness of 0.50 mm. Then, finish annealing was performed under the conditions shown in Table 6.

Table 6 shows the X-ray diffraction results, the precipitation morphology of the precipitates, and the evaluation results of the magnetic characteristics (magnetic flux density and iron loss). The same evaluations as in Example 1 and Example 2 were performed for X-ray diffraction, measurement of magnetic properties, and measurement of precipitates.

No. F1 to F14 are all examples of the invention. Control the holding temperature, holding time, cooling rate CR1 (° C./sec) between T1 to T2 (° C.) and average cooling rate CR2 (° C./sec) between T3 and T2 (° C.) in the finish annealing step within a more preferable range. No. F13 and F14 had a relatively good iron loss of "G". No. In F1 to F3, F5, F9 and F10, CR2 is less than 20 ° C./sec, but since the holding temperature, holding time and cooling rate CR1 in the finishing annealing step are all controlled within the scope of the present invention, iron It was confirmed that the loss was "F" and the effect of the present invention could be enjoyed.

On the other hand, No. All of f1 to f3 are comparative examples, and since any of the holding temperature, holding time, and average cooling rate CR1 between T1 to T2 (° C.) during finish annealing was outside the range of the present invention, Cu sulfide was produced. It does not precipitate in combination with the Cubic type oxide, and the iron loss shows a bad value exceeding 4.50 W / kg, and the iron loss evaluation is "B".

<Example 6>
Steel No. shown in Table 1. An ingot having components A13 to A17, A19, A20, and A22 to A27 was melted in a vacuum, and the ingot was heated and held under the conditions shown in Table 7 and then hot-rolled to obtain a hot-rolled steel sheet having a plate thickness of 2.0 mm. did. Then, it was pickled and cold-rolled at a reduction ratio of 75% to obtain a cold-rolled steel sheet having a plate thickness of 0.50 mm. Then, finish annealing was performed under the conditions shown in Table 7.

Table 7 shows the X-ray diffraction results, the precipitation morphology of the precipitates, and the evaluation results of the magnetic characteristics (magnetic flux density and iron loss). The same evaluations as in Example 1 and Example 2 were performed for X-ray diffraction, measurement of magnetic properties, and measurement of precipitates.

No. G1~ G22, G24~ G26 Both Ri invention example der, No. G23 is Ru Reference Example der. No. G21 to G26 control the cooling rate CR1 between T1 to T2 (° C.) and the average cooling rate CR2 between T3 and T2 (° C.) within a preferable range. However, No. G25 was outside the range (500 to T6 ° C.) where the take-up temperature in hot rolling was preferable. Therefore, No. In G21 to G24 and G26, the iron loss evaluation was a good value of "VG", while No. The iron loss evaluation of G25 remained at "G".
No. Since G6 and G9 had an average cooling rate CR2 between T3 and T2 (° C.) or a winding temperature in hot rolling outside the preferable range (500 to T6 (° C.)), the iron loss evaluation was "F". .. No. The average cooling rate CR2 of G4 and G5 was less than 20 ° C./sec, but the holding temperature of steel piece heating in the hot rolling process was controlled within a more preferable range (2400 to 10000 seconds), so the iron loss evaluation was ". It was a relatively good result with "G".

<Example 7>
Steel No. shown in Table 1. The ingots having the components A12 to A27 were melted in vacuum, and the ingots were heated and held under the conditions shown in Table 8 and then hot-rolled to obtain a hot-rolled steel sheet having a plate thickness of 2.0 mm. Then, the hot-rolled sheet was annealed under the conditions shown in Table 8, then pickled and cold-rolled at a reduction rate of 75% to obtain a cold-rolled steel sheet having a plate thickness of 0.50 mm. The cold-rolled steel sheet was subjected to finish annealing under the conditions shown in Table 8.

Table 8 shows the X-ray diffraction results, the precipitation morphology of the precipitates, and the evaluation results of the magnetic characteristics (magnetic flux density and iron loss). The same evaluations as in Example 1 and Example 2 were performed for X-ray diffraction, measurement of magnetic properties, and measurement of precipitates.

No. H1~ H16, H18~ H20 Both Ri invention example der, No. H17 is Ru Reference Example der. No. In H4, H8 to H14, and H18 to H20, the steel piece heating time (holding time) in hot rolling, and the holding time in the hot-rolled sheet annealing step and the finish annealing step are controlled within a more preferable range. In addition to this, the cooling rate CR1 between T1 to T2 (° C.) in the finish annealing step is within the range of the present invention, and the average cooling rate CR2 between T3 and T2 (° C.) is controlled within a preferable range. The loss evaluation was particularly good as "VG".
No. For H2, H3, H5 to H7, and H15 to H17, any one of the steel piece heating temperature, the steel piece heating time (holding time), and the winding temperature in hot rolling was out of the preferable range. Therefore, the iron loss evaluation was limited to "G".
No. For H1, the steel piece heating temperature in hot rolling and the average cooling rate CR2 between T3 and T2 (° C.) in the finish annealing step were out of the preferable ranges. Therefore, the iron loss evaluation was "F".

Claims (8)

By mass%
C: 0.0100% or less,
Si: 0.10 to 5.00%,
Mn: 0.010-2.000%,
Al: 0.10 to 3.00%,
S: 0.0001 to 0.0300%,
P: 0.0010 to 0.2000%,
Cu: 0.005-2.000%,
N: 0.0001 to 0.0150%,
O: Contains 0.0010 to 0.0200% and
Mg: 0.0001 to 0.0100%,
Ti: 0.0001 to 0.0100% ,
Zr: 0.0001 to 0.0100%
Contains one or more of
The balance has a chemical composition of Fe and impurities, the crystal system is a composite precipitate of a Cubic-type oxide and Cu sulfide, and the number density of the composite precipitate having an average diameter of 10 to 5000 nm is 0.001 to 0.001. A non-directional electromagnetic steel plate characterized by 10.000 pieces / μm ^2. _{I 2θ = 46.8} , which is the diffraction intensity of Cu sulfide having a hexagonal structure that appears at 2θ = 46.8 °, and the Cubic structure that appears at 2θ = 32.9 °, which are obtained by X-ray diffraction on the electrolytic extraction residue. The non-directional electromagnetic steel plate according to claim 1, wherein the diffraction intensity of Mn ₂ O _{3 having I 2θ = 32.9 satisfies the condition of the following formula 1.}
I _{2θ = 46.8} / I _{2θ = 32.9} ≧ 0.10 ... Equation 1 _{I 2θ = 46.8} , which is the diffraction intensity of Cu sulfide having a hexagonal structure that appears at 2θ = 46.8 °, and the Cubic structure that appears at 2θ = 21.6 °, which are obtained by X-ray diffraction on the electrolytic extraction residue. _SiO 2, MgO having a Cubic structure appearing at 2θ = 42.9 °, TiO with Cubic structure appearing at 2θ = 43.3 °, 2θ = 45.9 each _Al 2 _{O 3} having a Cubic structure appearing in ° with The non-directional electromagnetic steel sheet according to claim 1 or 2, wherein the diffraction strength of the above satisfies the condition of the following formula 2.
I _{2θ = 46.8} / (I _{2θ = 21.6} + I _{2θ = 42.9} + I _{2θ = 43.3} + I _{2θ = 45.9} ) ≧ 0.010 ... Equation 2 _{I 2θ = 32.1} , which is the diffraction intensity of Cu sulfide having a Cubic structure that appears at 2θ = 32.1 °, and the Hexagonal structure that appears at 2θ = 46.8 °, which are obtained by X-ray diffraction on the electrolytic extraction residue. The non-directional electromagnetic steel plate according to any one of claims 1 to 3, wherein the diffraction intensity of the Cu sulfide having I _{2θ = 46.8 satisfies the condition of the following formula 3.} ..
I _{2θ = 46.8} / I _{2θ = 32.1} > 0.50 ... Equation 3 A hot-rolling step of hot-rolling a steel piece having the chemical composition according to claim 1 to obtain a hot-rolled steel sheet,
A pickling step of pickling the hot-rolled steel sheet after the hot-rolling step, and a pickling step.
A cold-rolling step of cold-rolling the hot-rolled steel sheet after the pickling step to obtain a cold-rolled steel sheet, and a cold-rolling step.
A method for producing a non-oriented electrical steel sheet, which comprises a finishing annealing step of annealing the cold-rolled steel sheet.
In the finish annealing step, holding is performed at T1 (° C.) or higher represented by the following formula 4 for 10 seconds or longer and 3600 seconds or lower.
Claims 1 to 1, characterized in that, in the cooling of the finishing annealing step, the average cooling rate CR1 in the temperature range of T1 (° C.) or lower and T2 (° C.) or higher represented by the following formula 5 is set to less than 60 ° C./sec. The method for manufacturing a non-directional electromagnetic steel plate according to any one of claims 4.
T1 (° C.) = 15000 / (12-log ₁₀ ([% Cu] ² × [% S]))-273 ... Equation 4
T2 (° C.) = 15000 / (12-log ₁₀ ([% Cu] ² × [% S]))-373 ... Equation 5
In the above formula, [% Cu] is the content of Cu in mass%, and [% S] is the content of S in mass%. According to claim 5, in the cooling of the finishing annealing step, the average cooling rate CR2 in the temperature range of T3 (° C.) or higher and T2 (° C.) or lower represented by the following formula 6 is set to 20 ° C./sec or more. The method for manufacturing a non-directional electromagnetic steel plate according to the description.
T3 (° C.) = 15000 / (12-log ₁₀ ([% Cu] ² × [% S]))-473 ... Equation 6
In the above formula, [% Cu] is the content of Cu in mass%, and [% S] is the content of S in mass%. The steel piece heating temperature in the hot rolling step is set to T4 (° C.) or lower according to the following formula 7 and T5 (° C.) or higher according to the following formula 8, and after hot rolling, the winding temperature of the hot rolled plate is set to the following formula 9 The method for producing a non-oriented electrical steel sheet according to claim 5 or 6, wherein the control is performed at T6 (° C.) or lower.
T4 (° C.) = 15000 / (6-log ₁₀ ([% Mn] × [% O]))-273 ... Equation 7
T5 (° C.) = 14900 / (8-log ₁₀ ([% Mn] × [% S]))-473 ... Equation 8
T6 (° C.) = 14900 / (8-log ₁₀ ([% Mn] × [% S])) −573 ... Equation 9
In the above formula, [% Mn] is the content of Mn in mass%, [% O] is the content of O in mass%, and [% S] is the content of S in mass%. The quantity. The non-directional according to any one of claims 5 to 7, wherein a hot-rolled sheet annealing step for annealing the hot-rolled steel sheet is provided between the hot-rolling step and the pickling step. Manufacturing method of sex electromagnetic steel sheet.