JPH0754044A - Manufacture of nonoriented silicon steel sheet extremely excellent in magnetic characteristics - Google Patents

Abstract

PURPOSE:To add the specified elements for the treatment to secure the cooling speed in the gamma treatment of nonorientd silicon steel having transformation and for the prevention of nitriding in the atmosphere of gamma region annealing. CONSTITUTION:In the manufacturing process of the nonoriented silicon steel containing <=2.5% Si, <=1.0% Al and Si+Al:2.5%, the gamma treatment in the hot rolling, the gamma treatment to manufacture the steel strip by solidifying the molten steel by the moving and updating surface of a cooling body (where the cooling speed in gamma-alpha transformation <=50 deg.C/s), and the gamma treatment of the hot-rolled steel strip obtained by the hot rolling are excuted respectively, and at least one of Sn, Sb, P, Cr, Ge, Te, As, Ni, Cu and Se to be selected from 0.10-0.8% Sn, Sb, Ge, Te, As or Cu, or 0.02-0.15% P, As for Se, or 0.05-1.5% Cr or Ni is added in the stage of the molten steel for each case. Addition of the elements prevents the nitriding in the gamma treatment, the recrystallization and the grain growth in the finish annealing is fully achieved, and extremely excellent flux density and core loss are obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a non-oriented silicon steel sheet (hereinafter referred to as a non-oriented electrical steel sheet) having a very high magnetic flux density and a low iron loss.

[0002]

2. Description of the Related Art In recent years, demands for quality improvement of non-oriented electrical steel sheets as electromagnetic steel sheets for small rotating machines have become stronger from the viewpoint of energy saving. Iron and steel manufacturers are also enthusiastically researching and developing the product in order to meet the demand, and industrially, a number of so-called low grade non-oriented electrical steel sheets specified in JIS are manufactured. In the production of this type of non-oriented electrical steel sheet, in order to obtain a low iron loss, it is necessary to melt high-purity steel, increase the silicon content, and sufficiently take the final annealing temperature time. Traditionally, these methods
As is well known, although iron loss is improved, magnetic flux density is generally reduced. To solve this problem, so-called self-annealing in so-called hot rolling, hot-rolled sheet annealing below the transformation point, and the like are performed. However, even with non-oriented electrical steel sheets manufactured using these measures, there has been a limit to the high efficiency (energy saving) that has been increasingly strongly demanded in recent years.

The inventors of the present invention have conducted extensive studies and, in a non-oriented electrical steel sheet having a transformation, in a step before final cold rolling, γ
Phase, and the cooling rate during the γ-α transformation during cooling is 50
C./sec or less (in the following description, the process of reducing the cooling rate during the .gamma. To .alpha. Transformation shown in the present invention at 50.degree. C./sec or less is referred to as .gamma. Treatment), and thus the assembly of the product sheets after the final annealing. It has been found that by controlling the structure, an extremely excellent non-oriented electrical steel sheet having a very high magnetic flux density and a good iron loss can be obtained.

However, when producing a non-oriented electrical steel sheet by this method, the atmosphere gas generally used is
It is cheap nitrogen. Even if nitrogen is not so-called nascent nitrogen, a steel material containing a large amount of silicon and aluminum such as a non-oriented electrical steel sheet is likely to be nitrided. For this reason,
γ treatment improves the texture as a whole and the magnetic flux density is remarkably improved, but nitrides such as AlN, Si ₃ N ₄ , TiN, and BN are formed on the surface (particularly the surface layer portion), which hinders grain growth during finish annealing. Therefore, in some cases, the improvement in iron loss did not occur as expected.

[0005]

From this point of view, the present invention provides a γ treatment method which does not cause surface nitriding even in a nitrogen atmosphere.

[0006]

That is, the present invention is as follows.
(1) A silicon steel slab containing Si ≦ 2.5% by weight, Al ≦ 1.0% by weight, and Si + 2Al: 2.5% by weight or less is melted by a usual method, then hot rolled, and once. In the method for producing a non-oriented silicon steel sheet obtained by subjecting this steel sheet to a finish annealing process by cold rolling to obtain a predetermined sheet thickness, Sn, Sb, P, Cr, Ge, T
Any one or two or more selected from e, As, Ni, Cu, and Se are replaced with Sn, Sb, Ge, Te, Cu.
Then, 0.01 to 0.8% by weight, P, As, Se
In this case, a steel material added with 0.02 to 0.15 wt% and Cr and Ni with 0.05 to 1.5 wt% is used, and the coiling temperature of the coil in hot rolling is set to Ar. ₃ or more,
A non-oriented silicon steel sheet having excellent magnetic properties, characterized in that the cooling rate (average cooling rate between Ar ₃ and Ar ₁ ) when it is cooled and transformed into α phase is 50 ° C./sec or less. Production method. And (2) Si ≦ 2.5% by weight, Al
Molten steel containing ≦ 1.0% by weight and containing Si + 2Al: 2.5% by weight or less is solidified by a moving and renewing surface of a cooling body to produce a steel strip, and then the steel strip is subjected to a predetermined rolling by cold rolling. In the manufacturing method of the non-oriented silicon steel sheet obtained through the step of finish annealing, the additional elements Sn, Sb, P, Cr, Ge, Te, As, N
Any one or two selected from i, Cu, and Se
For Sn, Sb, Ge, Te, Cu, three or more,
0.01 to 0.8% by weight, in P, As, Se,
0.02 to 0.15% by weight, for Cr and Ni,
Cooling rate during γ → α transformation (average cooling between Ar ₃ and Ar ₁ in the cooling process when directly manufacturing a steel strip by solidifying from molten steel using a steel material added by 0.05 to 1.5 wt% Speed) is 50 ° C./second or less, and (3) Si ≦ 2.5% by weight, Al ≦ 1.0% by weight. %, And Si + 2Al: 2.5% by weight or less of a silicon steel slab is melted and hot-rolled by an ordinary method, and the hot-rolled steel strip obtained is annealed, if necessary, once or In a method for producing a non-oriented silicon steel sheet obtained by performing a step of finish annealing by cold rolling two or more times with annealing between them to a predetermined sheet thickness, Sn, Sb, P, Cr,
Any one or two or more selected from Ge, Te, As, Ni, Cu, and Se are replaced with Sn, Sb, Ge, and T.
For e and Cu, 0.01 to 0.8 wt% P, A
For s and Se, 0.02 to 0.15% by weight, C
For r and Ni, a steel material added by 0.05 to 1.5 wt% is used, and it is heated to the γ region in the heat treatment before the final cold rolling, transformed into the γ phase, and then cooled. Method for producing a non-oriented silicon steel sheet with extremely excellent magnetic properties, characterized in that the cooling rate (average cooling rate between Ar ₃ and Ar ₁ ) at the time of retransforming into α phase is 50 ° C./sec or less Is.

The present invention will be described in detail below. First, the components and additive components usually contained in the steel of the present invention will be described. In order to improve mechanical properties, magnetism, rust resistance, etc., or for other purposes, one or two of Mn, Ni, and Cr are used.
The effect of the present invention is not essentially impaired even if the content of at least one species is increased.

(C) The low grade non-oriented electrical steel sheet is mainly used for small rotating machines, and from the viewpoint of stability of characteristics, does not cause deterioration of magnetic characteristics (magnetic aging) during use. However, since the carbide is sufficiently precipitated and aggregated by this γ treatment, the magnetic aging phenomenon is reduced.
For this purpose, it is not necessary to have extremely low carbon as is conventionally said, and it may be 0.0500% or less. (S) Sulfur is an element that is inevitably mixed during melting. It is desirable that the content be 0.0100% or less, but it can be rendered harmless by applying the γ treatment of the present invention,
It may be 0.020% or less.

(N) In the conventional method for manufacturing a non-oriented electrical steel sheet, if the content of nitrogen is large like sulfur, it is partially re-dissolved during heating of the slab during hot rolling, and AlN is hot rolled during hot rolling. A low iron loss could not be obtained in the product due to the formation of precipitates such as and the like, which hinders the growth of recrystallized grains during finish annealing and the pinning effect of domain wall movement during product sheet magnetization. However, the gamma treatment of the present invention can coarsen the precipitates to render them harmless, and at the molten steel stage, it may be 0.010% or less. (Si, Al) Si, Al is added to increase the specific resistance of the steel sheet and reduce eddy current loss, but carbon is 0.02
%, The transformation disappears when Si + Al exceeds 2.50%, so the content is set to 2.50% or less.

If the content of (Mn) Mn is less than 0.1%, the workability is deteriorated, and it is generally added to render S harmless. However, if it exceeds 2.0%, the magnetic flux density is significantly deteriorated. The maximum is 2.0%. (B) B can be added to render N harmless. Since the balance with the amount of N is necessary, the maximum amount is 0.005%. However, the need for addition is small due to the γ treatment.

The present invention further includes Sn, Sb, P, Cr and G.
At least one of grain boundary segregation elements such as e, Te, As, Ni, Cu, and Se is added to prevent nitriding during the γ process. (P, As, Se) P is also added to enhance the punching property of the steel sheet. If it is 0.2% by weight or less, there is no problem in terms of magnetic properties. However, it is 0.02 to 0.15% by weight in consideration of the effect and the cost. Further, since it is a grain boundary segregation element, it has an effect of preventing nitrogen absorption to some extent. A
If s and Se are less than 0.01% by weight, the nitriding prevention effect is small, and if more than 0.15% by weight, grain growth during finish annealing is significantly inhibited, and the original effect of the γ treatment is lost. Therefore, the content is 0.02 to 0.15% by weight.

(Sn, Sb, Ge, Te, Cu) Sn,
Sb, Ge, Te, and Cu have long been known as grain boundary segregation elements, and have been used to control the texture of thin steel sheets. However, the object of the present invention is to prevent nitriding during the γ treatment, and for this purpose, 0.01 to 0.8% by weight is used.
Is desirable. If it is less than 0.01% by weight, the effect of preventing nitriding is not obtained, and if it is more than 0.8% by weight, the cost is significantly increased and it causes a surface flaw during hot rolling. In particular, Cu defects are famous. Therefore, the content is 0.0
1 to 0.8% by weight.

(Cr, Ni) Cr and Ni are concentrated and unevenly distributed on the surface so as to be contained in stainless steel, and have an effect of protecting the metal. If it is less than 0.05% by weight, the effect is small.
Although the original purpose of preventing nitriding at the time of γ treatment can be achieved even if it is added in an amount of more than 1.5% by weight, the cost increases and it becomes another purpose material such as a rustproof non-oriented electrical steel sheet. Therefore, in the present invention, the amount is 0.05 to 1.5% by weight.

Next, the γ processing condition will be described. First, the case of hot rolling will be described. Conventionally, by controlling the hot rolling conditions of non-oriented electrical steels having phase transformation (hereinafter abbreviated as transformation steels), the hot rolled steel sheets can be individually treated with and without annealing after hot rolling. The grain size was controlled, but the γ → α transformation at high temperature after hot-rolling was not found to date. The reason is that it was considered not suitable for improving magnetism because the orientation of crystal grains becomes random by transformation (γ → α) during cooling and the crystal grain size of the hot rolled sheet becomes smaller. is there. However, the inventors of the present invention have conducted diligent research and as a result, by winding at a high temperature of Ar ₃ or higher and controlling the cooling rate during this transformation, the reason is not clear, but the assembly in the final product plate It has been found that the organization is improved. Therefore, even if the annealing conditions during the final annealing are higher than those in the conventional case and the time is lengthened to grow the grains to improve the iron loss, the magnetic flux density is not lowered and the iron loss is improved. Further, in the γ treatment, since the cooling rate after high temperature winding is slow, precipitation of impurities with small solubility in the α phase is sufficiently performed and agglomeration occurs, and grain growth during the final annealing is not hindered (decontamination of impurities). ) In many cases, non-oriented electrical steel with low iron loss and high magnetic flux density can be obtained even after final annealing under conventional conditions.

Next, the actual situation will be described. Since this treatment is carried out by hot rolling, a material having a low transformation point (Ar ₃ ) is preferred, but if the transformation temperature (Ar ₃ ) is high, the winding device (reel) should be placed immediately after the hot rolling finishing stand. It can be realized by installing it. However, in order to achieve the average cooling rate of 50 ° C./second or less, it can be achieved by installing a heat insulating cover after winding and installing a weak heating device. In this case, a gas such as nitrogen is injected into the cover in order to improve the pickling property in the subsequent process. The holding temperature time is γ
It is a temperature (Ar ₃ or more) which becomes a phase, but this differs depending on the composition of the steel. The actual condition is 9 at Ar ₃ points + 50 ° C or higher.
About 0 seconds is sufficient. Also, the actual cooling rate is Ar
It is sufficient to cool the Ar ₁ range from ₃ points at an average of 50 ° C./sec or less. In order to prevent nitriding at this time, additional elements such as P, As, Se, Sn, Sb, Ge, Te, Cn,
It contains at least one of Cr and Ni.
Further, not only the continuous hot rolling method, but also the reversible hot rolling method (for example, hot rolling using a Steckel mill) is possible as long as the above-mentioned heat history can be secured.

Next, description will be made on the case where the moving and renewing surface of the cooling body is used for solidification. Conventionally, when hot-rolled sheets of transformation steel are transformed by reheating, the orientation of crystal grains becomes random and the crystal grain size decreases during cooling transformation (γ → α), which is suitable for improving magnetism. I was told that it was not possible and I couldn't look back. This also applies to the case where a steel strip is produced directly from molten steel. However, the present inventors
As a result of diligent research, it was found that controlling the cooling rate during this transformation significantly improves the texture in the final product sheet, although the reason is not clear. Therefore, even if the annealing conditions during the final annealing are higher than those in the conventional case and the time is lengthened to grow the grains to improve the iron loss, the magnetic flux density is not lowered and the iron loss is improved. In addition, as described above, since the cooling rate is slow in the γ treatment in this case, the precipitation of impurities with a small solubility in the α phase is sufficiently performed, and the grain growth during the final annealing is not hindered (decontamination of impurities). Non-oriented electrical steel sheets with low iron loss and high magnetic flux density can be obtained even after final annealing under conventional conditions. That is, when the present invention adopts the method of solidifying molten steel on the surface of a moving cooling body, this γ treatment is performed by a steel strip (3.5 to 0.5) obtained directly from molten steel.
mm) for controlling the cooling rate, and as a means for gradually cooling the steel strip between Ar ₃ and Ar _1, as in the case described above, a heating device is installed, a heat retention device is installed, or Ar ₃ +
A method of winding and retaining heat at a high temperature of 50 ° C. or higher is considered. In the present invention, the additional element is useful for preventing nitriding when nitrogen is used as the atmospheric gas at this time.

Further, it is technically possible to perform rapid cooling to room temperature and then heating to the γ range to perform controlled cooling, although there is a cost disadvantage.

Further, the case of annealing the steel strip obtained by ordinary hot rolling before the final cold rolling will be described. As described above, by performing a process of controlling the cooling rate at the time of transformation on the hot rolled sheet of the transformation steel, the annealing condition at the time of the final annealing has a higher temperature than that of the conventional one, and the time is made longer to cause grain growth. Alternatively, non-oriented electrical steel with low iron loss and high magnetic flux density can be obtained even after final annealing under conventional conditions. In the present invention, such excellent characteristics can be achieved by carrying out this γ treatment in the annealing step before the final cold rolling. This γ treatment may be performed in either a continuous annealing furnace or a box-type annealing furnace. When performing γ treatment in a continuous annealing furnace, in order to achieve an average cooling rate of 50 ° C./sec or less, for example, a high magnetic flux density unidirectional electrical steel sheet defined in JP-A-57-198214. Annealing conditions (hereinafter referred to as two-step soaking) may be applied. The soaking condition is the temperature at which the γ phase is obtained (Ac ₃ or higher), which differs depending on the composition of the steel. As a practical annealing condition, 90 seconds at Ac ₃ point + 50 ° C. or higher is sufficient. Also, the cooling rate is actually Ar ₃
From the point, it is sufficient to cool the Ar ₁ range at an average of 50 ° C./sec or less. The additive element of the present invention is useful for preventing nitriding when nitrogen is used as the atmospheric gas at this time.

As described above, the characteristic of the γ treatment is that it regulates the cooling rate from the γ phase. However, since the solid solubility of nitrogen in the γ region is large and the cooling rate is considerably low, there is no further effect. Since the grain-oriented electrical steel sheet contains a large amount of silicon and aluminum, nitriding with liquefied nitrogen is quite easy even if not so-called nascent nitrogen. And AlN, S
Since nitrides such as i ₃ N ₄ , TiN, and BN are formed particularly in the surface layer portion to hinder grain growth during finish annealing, the improvement in iron loss as expected may not occur. The inventors have conducted intensive research and development and conducted Sn, Sb, P, Cr, G
Grain boundary segregating elements such as e, Te, As, Ni, Cu, Se are added, and a nitriding prevention layer is formed by the interface (surface) segregation of these elements, and the nitriding prevention at the time of γ treatment is successful. Is.

[0020]

【Example】

[Example 1] A slab of the components shown in Table 1 (a silicon slab consisting of the balance Fe and unavoidable impurities) was heated by a usual method to a hot rolling thickness of 2.5 mm, and the hot rolling was completed at 1050 to 950 ° C. Then, the film is wound at 1000 to 900 ° C., and for convenience, the average cooling rate between 1000 and 850 ° C. is 500 ° C./sec (quenching in normal temperature water) 50 ° C./sec (forced air cooling) 10 ° C./sec (air cooling) 1 C./sec. (Using heat insulation cover) Cooling was performed at each cooling rate of 0.07.degree. C./sec. (Weakly heated in heat insulation cover). After that, pickling is applied to 0.5
Cold rolled to a thickness of 0 mm. The cold-rolled steel sheet was degreased and annealed at 850 ° C. (materials 1 and 2) and 800 ° C. (materials 3 and 4) for 30 seconds in a continuous annealing furnace. Then, the magnetic characteristics (average of L + C) were measured. Table 2 shows these values.
Shown in. Table 3 shows the comparative method (γ between 1000 and 850 ° C.
→ No cooling adjustment at α transformation point) a) No hot-rolled sheet annealing, b) Self-annealed material retained for 2 hours after hot-rolling at 800 ° C, and c) Continuous heat of a) material at 925 ° C for 150 seconds. The measured values of the rolled sheet annealed material are shown for comparison.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

As described above, when the method of the present invention is used, Sn, S and S
By adding b, P, Cr, and As, nitriding is suppressed, and it is possible to manufacture a non-oriented electrical steel sheet having excellent magnetic flux density and iron loss. In addition, regarding the materials 1 and 2, 1000-85 after hot rolling
1 (a) and 1 (b) show examples of photographs of the metal structure after the final annealing although the average cooling rate of 0 ° C. was 0.07 ° C./sec. It can be seen that the addition of Sb causes a remarkable difference in the crystal grain size, particularly in the surface layer.

Example 2 A molten steel having the components shown in Table 4 (a silicon slab consisting of the balance Fe and unavoidable impurities) was solidified on the surface of a moving cooling body to directly obtain a steel strip of 2.5 mm. There was cooled between Ar ₁ -50 ° C. under the following conditions from Ar ₃ + 50 ℃. Average cooling rate: 500 ° C / sec (cooling with normal temperature water) 50 ° C / sec (air cooling) 10 ° C / sec (use a heat-retaining cover when cooling without winding) 1 ° C / sec (winding at Ar ₃ + 50 ° C or higher) Cool as it is) 0.07 ℃ / sec (Wind at Ar ₃ + 50 ℃ or higher and cool with a heat insulation cover)

Then, it was pickled and cold-rolled to a thickness of 0.50 mm. The cold-rolled steel sheet was degreased and annealed at 850 ° C. (materials 1 and 2) and 800 ° C. (materials 3 and 4) for 30 seconds in a continuous annealing furnace. After that, the magnetic characteristics (L +
The average of C) was measured. These values are shown in Table 5. Table 6 is a comparison method similar to Table 3 a) without hot-rolled sheet annealing,
The following are the measured values of b) a so-called self-annealed material that is held for 2 hours after hot rolling at 800 ° C., and c) a material that is continuously hot-rolled at 925 ° C. for 150 seconds.

[0027]

[Table 4]

[0028]

[Table 5]

[0029]

[Table 6]

As described above, when the method of the present invention is used, although the γ treatment condition and the final annealing condition are the same, P, C
By adding r, Te, Ni, Cu, Se, the magnetic flux density,
It is possible to manufacture non-oriented electrical steel sheets with excellent iron loss. Further, for the materials 1 and 2, although the average cooling rate of 1.0 ° C./sec from Ar ₃ + 50 ° C. to Ar ₁ −50 ° C. was adopted after casting, a metallographic photograph after final annealing is shown in FIG.
It shows in (b). Although the γ treatment condition and the final annealing condition are the same, the addition of Cr causes a remarkable difference in the crystal grain size, particularly in the surface layer.

[Example 3] A slab having the components shown in Table 7 (a silicon slab consisting of the balance Fe and inevitable impurities) was heated by a usual method to a thickness of 2.5 mm, and then condition 1) hot-rolled sheet annealing was performed. Continuously performed at 1100 ° C for 2 minutes, and for convenience, average cooling rate between 1000 and 850 ° C is 500 ° C / sec (quenched in normal temperature water) 50 ° C / sec (air cooling) 10 ° C / sec (two-stage soaking) ) It cooled at each cooling rate of 1 degree-C / sec (two-step soaking). Condition 2) After annealing at 1100 ° C. for 10 minutes by box annealing, it was cooled in a furnace after being cut off. In this case, the cooling rate was 0.07 ° C./sec. Then, it was pickled and cold-rolled to a thickness of 0.50 mm. The cold-rolled steel sheet is degreased and then in a continuous annealing furnace at 850 ° C (materials 1 and 2) and 800 ° C (materials 3).
Annealed in 4) for 30 seconds. Then, the magnetic characteristics (average of L + C) were measured. These values are shown in Table 8. Table 9 is a comparative method similar to Table 3, in which a) a hot rolled sheet is not annealed, b) a so-called self-annealed material that is held for 2 hours after hot rolling at 800 ° C.,
c) The measured values of the material obtained by continuously hot-rolling the a) material at 925 ° C. for 150 seconds are shown for comparison.

[0032]

[Table 7]

[0033]

[Table 8]

[0034]

[Table 9]

As described above, when the method of the present invention is used, Sn, S and S
By adding b, P, Cr, Ge, and Te, it is possible to manufacture a non-oriented electrical steel sheet having excellent magnetic flux density and iron loss.
3 (a) and 3 (b) are photographs of the metallographic structure after the final annealing when the average cooling rate of 1000 to 850 [deg.] C. for the materials 1 and 2 was 10 [deg.] C./sec. Although the γ treatment condition and the final annealing condition are the same, the addition of Ge causes a remarkable difference in the crystal grain size, particularly in the surface layer.

[0036]

As described above, according to the present invention,
By preventing nitriding during the γ treatment, it is possible to obtain a non-oriented electrical steel sheet having extremely excellent magnetic flux density and iron loss.

[Brief description of drawings]

FIG. 1 (a) is a micrograph showing a metal structure of a material 1 in Example 1 and (b) the same material 2 in a γ-processed product at the time of hot rolling and winding.

FIG. 2 (a) is a material 1 in Example 2 and FIG. 2 (b) is the same material 2 and shows a metallographic structure of a product γ-processed in a cooling process immediately after solidification of a material rapidly cooled by a moving and renewing cooling body surface. The micrograph shown.

3 (a) is a material 1 in Example 3 and FIG. 3 (b) is the same material 2 in the cooling process of the heat treatment before the final cold rolling.
The micrograph which shows the metallographic structure of the processed product.

Claims (3)

[Claims] 1. A silicon steel slab containing Si ≦ 2.5% by weight, Al ≦ 1.0% by weight, and Si + 2Al: 2.5% by weight or less is melted by a usual method and then hot rolled, In a method for producing a non-oriented silicon steel sheet obtained by performing a step of finish annealing this steel sheet with a predetermined thickness by one cold rolling, Sn, Sb, P, Cr, G
Any one or two or more selected from e, Te, As, Ni, Cu, and Se are replaced with Sn, Sb, Ge, and T.
For e and Cu, 0.01 to 0.8 wt% P, A
For s and Se, 0.02 to 0.15% by weight, C
For r and Ni, add 0.05 to 1.5% by weight,
The coiling temperature in hot rolling is set to Ar ₃ or higher, and the cooling rate (Ar ₃ to A
The average cooling rate between r ₁ ) is 50 ° C./sec or less, and a method for producing a non-oriented silicon steel sheet having extremely excellent magnetic properties. 2. A steel strip is obtained by solidifying molten steel containing Si ≦ 2.5% by weight, Al ≦ 1.0% by weight and Si + 2Al: 2.5% by weight or less by a moving and renewing surface of a cooling body. In the method for producing a non-oriented silicon steel sheet, which is produced through a process of producing and then cold rolling the steel strip to a predetermined plate thickness and finish annealing, Sn, as an additional element,
Sb, P, Cr, Ge, Te, As, Ni, Cu, Se
Any one or two or more selected from among
For n, Sb, Ge, Te, Cu, 0.01-
0.8 wt%, P, As, Se, 0.02-
0.15% by weight, for Cr and Ni, 0.05-
Addition of 1.5% by weight, solidification from molten steel, cooling rate during γ → α transformation in the cooling process when directly manufacturing a steel strip (average cooling rate between Ar ₃ and Ar ₁ ) is 50 ° C / sec or less A method for producing a non-oriented silicon steel sheet having extremely excellent magnetic properties, characterized by: 3. A silicon steel slab containing Si ≦ 2.5% by weight, Al ≦ 1.0% by weight and Si + 2Al: 2.5% by weight or less is melted and hot rolled by a usual method. Non-oriented silicon obtained through a step of annealing the obtained hot-rolled steel strip as needed and performing a final annealing by one or two or more cold rollings with annealing sandwiched to a predetermined plate thickness. In the method for manufacturing a steel sheet, Sn, Sb, P, C as additional elements are further added.
Any one or two or more selected from r, Ge, Te, As, Ni, Cu, and Se are replaced with Sn, Sb, and G.
In the case of e, Te and Cu, 0.01 to 0.8% by weight,
In P, As and Se, 0.02 to 0.15 wt% is added, and in Cr and Ni, 0.05 to 1.5 wt% is added. In the heat treatment before the final cold rolling, heating to the γ range,
The magnetic properties are characterized by a cooling rate (average cooling rate between Ar ₃ and Ar ₁ ) of 50 ° C./sec or less when transformed into the γ phase and then cooled and retransformed into the α phase. An excellent non-oriented silicon steel sheet manufacturing method.