JP6813014B2 - 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.

Non-oriented electrical steel sheets are a type of soft magnetic material widely used as iron core materials for motors and the like. In recent years, electric vehicles and hybrid vehicles have been put into practical use, motor drive systems have been developed, and motor drive frequencies tend to increase year by year. At present, it is common that the fundamental frequency is several hundred to several kHz, and the iron loss characteristic of the iron core in the high frequency range is becoming more important. Therefore, conventionally, the iron loss in the high frequency region has been reduced by adding an alloy element such as Si or Al or by reducing the plate thickness.

However, when the above alloying elements are added, a decrease in magnetic flux density is unavoidable. Further, in order to reduce the plate thickness, it is necessary to increase the cold rolling reduction rate. When the cold rolling reduction ratio is increased, the primary recrystallization texture is accumulated in the {111} direction, which is the stable rolling direction, resulting in a decrease in the magnetic flux density. A decrease in magnetic flux density causes an increase in copper loss of the motor, leading to a decrease in motor efficiency. Therefore, it is desired not only to reduce the iron loss in the high frequency range but also to improve the magnetic flux density.

As a method for producing a non-oriented electrical steel sheet having an excellent magnetic flux density, Patent Document 1 describes that 0.1 to 5% by mass of Co is added to steel having 4% by mass or less of Si. However, since Co is very expensive, there is a problem that the manufacturing cost is remarkably increased. Further, Patent Document 2 proposes a method in which Al is 0.017% by mass or less, N is 0.0030% by mass or less, and the particle size of the hot-spread annealed plate is controlled. However, this method requires warm rolling with a plate temperature of about 200 ° C, which increases costs due to equipment compatibility or process control due to production restrictions. It becomes a problem.

Japanese Unexamined Patent Publication No. 2000-129410 Japanese Unexamined Patent Publication No. 2001-316729

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a non-oriented electrical steel sheet having an excellent magnetic flux density while avoiding an increase in cost.

In order to solve the above problems, the inventors have made extensive studies focusing on the segregation elements Sn and Sb, which are effective for improving the texture. As a result, it was found that the magnetic flux density of the steel in which Al is reduced to a very small amount and Sn or Sb is added in a large amount is significantly improved by reducing B or As, and the effect is that the cold rolling reduction ratio is large. Further finding that it is so remarkable, we have come to newly discover the present invention.

Hereinafter, the experiments leading to the present invention will be described.
(Experiment 1)
In order to develop a non-directional electromagnetic steel plate with excellent magnetic flux density, the inventors refocused on Sn and Sb, which are effective in improving the texture, and investigated the effect of Al on the magnetic flux density improving effect of Sn.

C: 0.0020% by mass, Si: 2.70% by mass, Mn: 0.200% by mass, P: 0.020% by mass, S: 0.0020% by mass, Al: 0.3% by mass, N: 0.0020% by mass, As: 0.0020% by mass, and B : Al-added steel containing 0.00010% by mass, C: 0.0020% by mass, Si: 3.00% by mass, Mn: 0.200% by mass, P: 0.020% by mass, S: 0.0020% by mass, Al: 0.001% by mass, N: Based on two types of steel without Al added, which contained 0.0020% by mass, As: 0.0020% by mass, and B: 0.00010% by mass, Sn was added in the range of 0% to 0.26%. A steel ingot was used as a test material. These test materials are hot-rolled to obtain a hot-rolled plate with a plate thickness of 2.0 mm, then annealed at 1000 ° C for 30 seconds, and then cold-rolled at a reduction ratio of 82.5% to obtain a plate thickness. A 0.35 mm cold rolled plate was used. Thereafter, the oxygen potential PH ₂ O / PH ₂ is 0.0005 atmosphere _{(10% H 2 -90% N} 2 atmosphere, dew point -50 ° C.) subjected to finish annealing at 1000 ° C. × 10 seconds, the magnetic flux density B ₅₀ of the steel sheet Was measured with a 25 cm Epstein device.

The relationship between the magnetic flux density B ₅₀ and the Sn amount is shown in FIG. The same result as the conventional knowledge was obtained that the magnetic flux density B ₅₀ increases as the Sn amount increases regardless of the presence or absence of Al addition, but when the Sn amount is 0.05% or more, the magnetic flux of the steel without Al addition is higher. It was found that the density was greatly improved. The reason why the increase in magnetic flux density B ₅₀ differs between the steel without Al added and the steel with Al added is not yet clear at this time, but the steel without Al added promotes the grain boundary segregation of Sn. It is presumed that it was folded.

(Experiment 2)
Furthermore, the inventors investigated the effect of the reduction rate on the effect of improving the magnetic flux density of Sn.
C: 0.0020% by mass, Si: 2.70% by mass, Mn: 0.200% by mass, P: 0.020% by mass, S: 0.0020% by mass, Al: 0.3% by mass, N: 0.0020% by mass, As: 0.0020% by mass, and B Al-added steel containing Sn: 0.15% by mass or 0.001% by mass in addition to 0.00010% by mass, C: 0.0025% by mass, Si: 3.00% by mass, Mn: 0.200% by mass, P: 0.020% by mass, S : 0.0020% by mass, Al: 0.001% by mass, N: 0.0020% by mass, As: 0.0020% by mass, and B: 0.00010% by mass, plus Al containing Sn: 0.15% by mass or 0.001% by mass. Using steel ingots of no steel as test materials, these were hot-rolled to a plate thickness of 2.0 mm, and then hot-rolled plate annealed at 1000 ° C. for 30 seconds.

Thereafter, to get the cold-rolled sheet of thickness 0.40~0.10mm to cold rolling at a reduction rate of 80% to 95%, then, the atmosphere oxygen potential PH ₂ O / PH ₂ is 0.0005 (10% H ₂ -90 Finish annealing was performed at 1000 ° C. × 10 seconds at% N ₂ atmosphere, dew point -50 ° C., and the magnetic flux density B _{50 of the} steel sheet was measured with a 25 cm Epstein device.

The relationship between the magnetic flux density B ₅₀ and the reduction rate is shown in FIG. The rate of increase of the magnetic flux density B ₅₀ value due to the addition of Sn does not change in the steel to which Al is added even if the reduction rate increases, but the magnetic flux density B ₅₀ value due to the addition of Sn does not change in the steel to which Al is not added. It was found that the rate of increase was high. That is, it can be seen that when Sn is added to the steel to which Al is not added, the reduction rate can be increased without lowering the magnetic flux density, in other words, the plate thickness can be reduced. The reason why the rate of increase of the magnetic flux density B ₅₀ value when the reduction rate is high differs between the steel without Al added and the steel with Al added is not clear at this time, but under high pressure. It is presumed that the reduction effect of Sn in the (111) orientation grain increased by the above was more remarkable in the steel to which Al was not added.

(Experiment 3)
Next, the inventors investigated the effect of a small amount of B on the effect of Sn to improve the magnetic flux density.
C: 0.0020% by mass, Si: 3.00% by mass, Mn: 0.200% by mass, P: 0.020% by mass, S: 0.0020% by mass, Al: 0.001% by mass, N: 0.0020% by mass, As: 0.0020% by mass, and Sn A steel ingot containing 0.15% by mass and added with B added in various changes in the range of 0.00002 to 0.00126% by mass was used as a test material, and these were hot-rolled to a plate thickness of 2.0 mm. Then, the hot-rolled plate was annealed at 1000 ° C. for 30 seconds. Then, it is cold-rolled at a reduction ratio of 82.5% or 90.0% to obtain a cold-rolled sheet with a plate thickness of 0.35 mm or 0.20 mm, respectively, and then an atmosphere (10) in which the oxygen potential PH ₂ O / PH ₂ is 0.0005. % H ₂ -90% N ₂ atmosphere, dew point -50 ° C.) subjected to finish annealing at 1000 ° C. × 10 seconds, the magnetic flux density B ₅₀ of the steel sheet were measured by the 25cm Epstein device.

The relationship between the magnetic flux density B ₅₀ , the amount B, and the cold rolling reduction rate is shown in FIG. It can be seen that the magnetic flux density decreases when the B content exceeds 0.00030 mass%. The reason why the effect of Sn is suppressed by the increase in the amount of B is not clear at this time, but it is considered that the segregation of B at the grain boundaries suppressed the segregation of Sn at the grain boundaries.
Since the above results were confirmed even when the As content exceeded 0.0050% by mass, it is also important to reduce the As content in order to obtain the Sn effect.

(Experiment 4)
Next, the adhesion of the insulating film after strain relief annealing was investigated for a steel having reduced Al and having an improved magnetic flux density by adding Sn.
C: 0.0020% by mass, Si: 3.00% by mass, Mn: 0.200% by mass, P: 0.020% by mass, S: 0.0020% by mass, Al: 0.0010% by mass, N: 0.0020% by mass, Sn: 0.10% by mass, B: A steel ingot containing 0.00010% by mass was used as a test material and hot-rolled to obtain a hot-rolled plate with a plate thickness of 2.0 mm. Then, after hot-rolling at 1000 ° C for 30 seconds, the rolling reduction ratio was 82.5%. Cold-rolled in Thereafter, the oxygen potential PH ₂ O / PH ₂ were subjected to finish annealing at 1000 ° C. × 10 seconds in an atmosphere which is _{0.0005 (10% H 2 -90%} N 2 atmosphere, dew point -50 ° C.).

At that time, cooling at 700 to 500 ° C. was performed in an atmosphere where the oxygen potential PH ₂ O / PH ₂ was 0.0001 to 0.005. Then, an insulating film was applied to the steel sheet, and strain annealing was performed at 750 ° C. for 2 hours in a 100 vol% N ₂ atmosphere, and the adhesion of the obtained steel sheet coating was investigated. Adhesion was evaluated by the peeling area (%) of the coating film after peeling the adhesive tape in the bent portion after bending at 90 ° of 50 mmφ. The conditions such as the material of the adhesive tape and the tape peeling speed conformed to JIS Z 0237.

The relationship between the oxygen potential during cooling and the film adhesion is shown in FIG. It can be seen that when the oxygen potential is less than 0.001, the film adhesion drops sharply. That is, good film adhesion can be obtained with an oxygen potential of 0.001 or more and a film peeling area of 10% or less. The reason why the film adhesion changes depending on the oxygen potential during finish annealing cooling has not been clarified at this time, but the following can be considered. The cause of the film peeling is considered to be the segregation of Sn at the interface between the film and the base iron due to strain annealing, and the formation of an oxide layer on the surface layer of the steel sheet by finish annealing suppressed the segregation of Sn at the interface. it is conceivable that.

The above-mentioned effect of improving the magnetic flux density was the same even when Sb was added instead of Sn. From these results, the magnetic flux density of steel with Al reduced to a very small amount and Sn or Sb added in a large amount is significantly improved by reducing B or As, and the effect is that the cold rolling reduction rate is large. It turned out to be so remarkable. However, if a large amount of Sn or Sb is added, the film adhesion after strain annealing becomes a problem. Therefore, in order to utilize strain annealing, it is preferable to adjust the oxygen potential by cooling the finish annealing.

The present invention has been made based on the above-mentioned novel findings, and has the following configurations.

1. 1. By mass%
C: 0.0050% or less,
Si: 6.00% or less,
Mn: 0.050% or more and 3.00% or less,
P: 0.10% or less,
S: 0.0050% or less,
N: 0.0050% or less,
Al: 0.0050% or less and B: 0.00030% or less, and in mass%,
A non-oriented electrical steel sheet containing Sn: 0.05% or more and 0.50% or less and / or Sb: 0.05% or more and 0.50% or less, and the balance having a component composition consisting of Fe and unavoidable impurities.

2. 2. The component composition further
By mass%
As: The non-oriented electrical steel sheet according to 1 above, which contains 0.0050% or less.

3. 3. The component composition further
By mass%
Ca: 0.0001% or more and 0.0300% or less,
REM: 0.0001% or more and 0.0300% or less and
Mg: The non-oriented electrical steel sheet according to 1 or 2 above, which contains one or more selected from 0.0001% or more and 0.0300% or less.

4. By mass%
C: 0.0050% or less,
Si: 6.00% or less,
Mn: 0.050% or more and 3.00% or less,
P: 0.10% or less,
S: 0.0050% or less,
N: 0.0050% or less,
Al: 0.0050% or less and B: 0.00030% or less, and in mass%,
A steel slab containing Sn: 0.05% or more and 0.50% or less and / or Sb: 0.05% or more and 0.50% or less and having a component composition consisting of Fe and unavoidable impurities is hot-rolled to obtain a hot-rolled steel sheet.
The hot-rolled steel sheet is pickled and
The hot-rolled steel sheet that has been pickled is cold-rolled once or two or more times with intermediate annealing sandwiched between them to obtain a cold-rolled steel sheet.
A method for producing a non-oriented electrical steel sheet, in which the cold-rolled steel sheet is finish-annealed and then coated.
A method for producing a non-oriented electrical steel sheet, characterized in that the rolling reduction in cold rolling immediately before finish annealing is 85% or more.

5. By mass%
C: 0.0050% or less,
Si: 6.00% or less,
Mn: 0.050% or more and 3.00% or less,
P: 0.10% or less,
S: 0.0050% or less,
N: 0.0050% or less,
Al: 0.0050% or less and B: 0.00030% or less, and in mass%,
A steel slab containing Sn: 0.05% or more and 0.50% or less and / or Sb: 0.05% or more and 0.50% or less and having a component composition consisting of Fe and unavoidable impurities is hot-rolled to obtain a hot-rolled steel sheet.
The hot-rolled steel sheet is pickled and
The hot-rolled steel sheet that has been pickled is cold-rolled once or two or more times with intermediate annealing sandwiched between them to obtain a cold-rolled steel sheet.
A method for producing a non-oriented electrical steel sheet, in which the cold-rolled steel sheet is finish-annealed and then coated.
The finish annealing is a non-directional electromagnetic wave in which cooling from 700 ° C. to 500 ° C. is performed over 1 to 300 seconds in an oxidizing atmosphere having an oxygen potential of PH ₂ O / PH ₂ of 0.0010 or more. Method of manufacturing steel plate.

6. By mass%
C: 0.0050% or less,
Si: 6.00% or less,
Mn: 0.050% or more and 3.00% or less,
P: 0.10% or less,
S: 0.0050% or less,
N: 0.0050% or less,
Al: 0.0050% or less and B: 0.00030% or less, and in mass%,
A steel slab containing Sn: 0.05% or more and 0.50% or less and / or Sb: 0.05% or more and 0.50% or less and having a component composition consisting of Fe and unavoidable impurities is hot-rolled to obtain a hot-rolled steel sheet.
The hot-rolled steel sheet is pickled and
The hot-rolled steel sheet that has been pickled is cold-rolled once or two or more times with intermediate annealing sandwiched between them to obtain a cold-rolled steel sheet.
A method for producing a non-oriented electrical steel sheet, in which the cold-rolled steel sheet is finish-annealed and then coated.
The rolling reduction in cold rolling immediately before the finish annealing is 85% or more.
The finish annealing is a non-directional electromagnetic wave in which cooling from 700 ° C. to 500 ° C. is performed over 1 to 300 seconds in an oxidizing atmosphere having an oxygen potential of PH ₂ O / PH ₂ of 0.0010 or more. Method of manufacturing steel plate.

7. The component composition further
By mass%
As: The method for producing a non-oriented electrical steel sheet according to any one of 4 to 6 above, which contains 0.0050% or less.

8. The component composition further
By mass%
Ca: 0.0001% or more and 0.0300% or less,
REM: 0.0001% or more and 0.0300% or less and
The method for producing a non-oriented electrical steel sheet according to any one of 4 to 7 above, which contains one or more selected from Mg: 0.0001% or more and 0.0300% or less.

According to the present invention, it is possible to provide a non-oriented electrical steel sheet having an excellent magnetic flux density while avoiding an increase in cost.

It is a figure which shows the relationship between the Sn amount and the magnetic flux density B ₅₀ of a finished annealed sheet. It is a figure which shows the relationship between the cold rolling reduction rate and the magnetic flux density B ₅₀ of a finished annealed sheet. It is a figure which shows the relationship between the amount B and the cold rolling rolling reduction | magnetic flux density B ₅₀ of a finished annealed sheet. It is a figure which shows the relationship between the oxygen potential PH ₂ O / PH ₂ at the time of finish annealing cooling and the peeling area of the coating film of a strain-removing annealing plate.

Hereinafter, the non-oriented electrical steel sheet according to the embodiment of the present invention will be described. First, the reasons for limiting the composition of steel will be described. In the present specification, "%" representing the content of each component element means "mass%" unless otherwise specified.

C: 0.0050% or less C is limited to 0.0050% or less because it causes magnetic aging in the product board. Preferably, it is 0.0040% or less.

Si: 6.00% or less
Si is an element that increases the intrinsic resistance of steel and is effective in reducing iron loss. If it is added in excess of 6.00%, it becomes extremely brittle and difficult to cold-roll, so the upper limit is 6.00%. It is preferably in the range of 1.00% or more and 5.00% or less.

Mn: 0.050% or more and 3.00% or less
Since Mn is an element effective in preventing red-hot brittleness during hot rolling, it must be contained in an amount of 0.050% or more. However, if it exceeds 3.00%, the cold rollability is lowered and the magnetic flux density is lowered, so the upper limit is set to 3.00%. It is preferably in the range of 0.100% or more and 2.00% or less.

P: 0.100% or less P is an element that is effective in adjusting hardness and improving punching workability because it has excellent solid solution strengthening ability. If it exceeds 0.100%, embrittlement becomes remarkable, so the upper limit is 0.100%. It is preferably 0.050% or less.

S: 0.0050% or less S is a harmful element that produces sulfide and increases iron loss, so the upper limit is 0.0050%. It is preferably 0.0040% or less.

N: 0.0050% or less N is a harmful element that produces nitrides and increases iron loss, so the upper limit is 0.0050%. It is preferably 0.0040% or less.

Al: 0.0050% or less
Al is one of the important elements in the present invention. If the content exceeds 0.0050%, the effect of improving the magnetic flux density due to the addition of Sn or Sb described above cannot be obtained, so the upper limit is set to 0.0050%. It is preferably 0.0030% or less.

B: 0.00030% or less B is one of the important elements in the present invention. If the content exceeds 0.00030%, the effect of improving the magnetic flux density due to the addition of Sn or Sb described above cannot be obtained, so the upper limit is set to 0.00030%. It is preferably 0.00010% or less.

Sn: 0.05% or more and 0.50% or less and / or Sb: 0.05% or more and 0.50% or less
Sn and Sb are one of the important elements in the present invention. In order to obtain the effect of improving the magnetic flux density according to the present invention, it is necessary to contain 0.05% or more. However, if it exceeds 0.50%, embrittlement becomes remarkable, so the upper limit is set to 0.50%. It is preferably 0.05% or more and 0.20% or less.

The basic components of the present invention have been described above. The balance other than the above components is Fe and unavoidable impurities, but the following elements can be appropriately contained in addition to the above components, if necessary.

As: 0.0050% or less
If As is contained in excess of 0.0050%, the effect of improving the magnetic flux density due to the addition of Sn or Sb described above cannot be obtained, so the upper limit is set to 0.0050%. It is preferably 0.0030% or less.

One or more selected from Ca: 0.0001% or more and 0.0300% or less, REM: 0.0001% or more and 0.0300% or less, and Mg: 0.0001% or more and 0.0300% or less.
Ca, REM and Mg are all effective elements for reducing iron loss because they fix S and suppress fine precipitation of sulfide. In order to obtain this effect, it is necessary to add 0.0001% or more of each. However, even if it is added in excess of 0.0300%, the above effect is saturated. Therefore, when one or more selected from Ca, REM, and Mg are added, the range is 0.0001% or more and 0.0300% or less, respectively.

Next, the manufacturing conditions of the grain-oriented electrical steel sheet according to the present invention will be described.
As the non-oriented electrical steel sheet of the present invention, as long as the steel material used for the production thereof has the contents of Al, Sn, Sb and B within the above range, a known method for producing the non-oriented electrical steel sheet can be used. Can be manufactured using. For example, steel adjusted to the above-mentioned predetermined composition composition by the following method, that is, a refining process of a converter or an electric furnace, is melted, secondarily refined by a degassing facility or the like, and continuously cast to obtain a steel slab. After that, a method can be adopted in which hot rolling is performed, hot rolled sheet is annealed if necessary, pickling, cold rolling, finish annealing, and further strain relief annealing.
However, as will be described later, it is preferable to adjust the rolling reduction in cold rolling immediately before finish annealing in order to reduce the plate thickness, and it is possible to adjust the oxygen potential of the cooling atmosphere of finish annealing in order to improve film adhesion. preferable.

Here, the thickness of the steel sheet (hot-rolled sheet) after the hot rolling is preferably 1.0 to 5.0 mm. This is because if it is less than 1.0 mm, rolling troubles in hot rolling increase, while if it exceeds 5.0 mm, the cold rolling reduction ratio becomes too high and the texture deteriorates.

Further, hot-rolled plate annealing can be performed as needed. When annealing a hot-rolled plate, the soaking temperature is preferably in the range of 900 to 1200 ° C. If the temperature is lower than 900 ° C, the effect of hot-rolled sheet annealing is not sufficiently obtained, and the magnetic characteristics are not improved. On the other hand, if the temperature exceeds 1200 ° C, the cost is disadvantageous and surface defects due to scale are caused. Because it occurs. The soaking time is preferably 1 to 300 sec. This is because if it is less than 1 sec, the effect of hot-rolled sheet annealing cannot be sufficiently obtained, and if it exceeds 300 sec, the effect is saturated.
If the hot-rolled plate is not annealed, self-annealing can also be performed. Self-annealing is annealing by heat held inside the hot-rolled coil after hot-rolling.

Further, the cold rolling applied to the hot-rolled plate or the hot-rolled annealed plate is preferably performed once or twice or more with an intermediate annealing sandwiched between them. In particular, for the final cold rolling, the effect of improving the magnetic flux density is enhanced by performing warm rolling in which the plate temperature is rolled at a temperature of about 200 ° C. Therefore, if there is a problem in terms of cost due to equipment and production restrictions, warm rolling is preferable.
Further, the rolling reduction in cold rolling immediately before finish annealing is preferably 85% or more.

The plate thickness (final plate thickness) of the cold-rolled plate is preferably in the range of 0.1 to 1.0 mm. This is because if it is less than 0.1 mm, the productivity decreases, while if it exceeds 1.0 mm, the effect of reducing iron loss is small. In particular, in the present invention, the plate thickness can be reduced without reducing the magnetic flux density, so that the final plate thickness is preferably 0.3 mm or less.

The finish annealing applied to the cold-rolled plate having the final plate thickness is preferably a soaking process at a temperature of 700 to 1200 ° C. for 1 to 300 seconds in a continuous annealing furnace. If the soaking temperature is less than 700 ° C., recrystallization does not proceed sufficiently and it is difficult to obtain good magnetic characteristics, and the plate shape correction effect in continuous annealing cannot be sufficiently obtained. On the other hand, if the temperature exceeds 1200 ° C., the crystal grains become coarse and the toughness decreases.

After the finish annealing, the steel sheet is preferably coated with an insulating film on the surface of the steel sheet in order to increase the interlayer resistance and reduce the iron loss. In particular, when it is desired to ensure good punching performance, it is desirable to apply a semi-organic insulating film containing a resin.

The non-oriented electrical steel sheet covered with an insulating film may be used after being further subjected to strain annealing, or may be used as it is without being subjected to strain annealing. Further, after the punching process, the strain removing annealing may be performed. However, when used after strain relief annealing, adhesion of the film becomes a problem, so cooling at 700 to 500 ° C in the above finish annealing step takes 1 to 300 seconds in an atmosphere with an oxygen potential of 0.0010 or more. It is preferable to carry out. The cooling time is set to 1 to 300 seconds because the oxidation of the surface layer of the steel sheet is not sufficiently promoted if it is less than 1 second, while the productivity is lowered if it exceeds 300 seconds. When PH ₂ O / PH ₂ exceeds 5, an oxidation unevenness called a gas mark occurs on the surface of the steel sheet, which impairs the appearance as a commercial product. Therefore, the upper limit is preferably about 5. The strain-removing annealing is generally performed at 750 ° C. for about 2 hours.

(Example 1)
No. 1 having the component composition shown in Table 1 in the refining process of converter-vacuum degassing treatment. Steels 1 to 48 were melted and made into slabs by a continuous casting method, and then the slabs were heated at 1140 ° C. for 1 hour and hot-rolled to a plate thickness of 2.0 mm. Subsequently, the hot-rolled plate was annealed at 1000 ° C. for 30 seconds. Then, the steel sheet was pickled and cold-rolled at the reduction ratio shown in Table 1. Thereafter, the oxygen potential PH ₂ O / PH ₂ were subjected to finish annealing at 1000 ° C. × 10 seconds in an atmosphere which is _{0.0005 (10% H 2 -90%} N 2 atmosphere, dew point -50 ° C.). At that time, cooling at 700 to 500 ° C. was performed under the conditions shown in Table 1, and an insulating film was applied to the steel sheet to obtain a non-oriented electrical steel sheet. Then, strain annealing was performed at 750 ° C. for 2 hours in a 100 vol% N ₂ atmosphere.

The iron loss W _15/50 and the magnetic flux density B ₅₀ of the finished annealed plate obtained as described above were measured, and the adhesion of the coating of the obtained strain-removing annealed plate was investigated. The magnetic characteristics were evaluated by collecting an Epstein test piece of 30 mm x 280 mm with a 25 cm Epstein device, and the adhesion was evaluated by bending 90 ° of 50 mmφ and the peeling area (%) of the film after peeling the adhesive tape in the bent part. ). The conditions such as the material of the adhesive tape and the tape peeling speed conformed to JIS Z 0237. The results are also shown in Table 1.

(Example 2)
No. 1 having the component composition shown in Table 2 in the refining process of converter-vacuum degassing treatment. Steels 49 to 67 were melted and made into slabs by a continuous casting method, and then the slabs were heated at 1140 ° C. for 1 hour and hot-rolled to a plate thickness of 2.0 mm. Subsequently, the hot-rolled plate was subjected to a winding treatment corresponding to self-annealing at 650 ° C. for 1 hour. Then, the steel sheet was pickled and cold-rolled at the reduction ratio shown in Table 2. Thereafter, the oxygen potential PH ₂ O / PH ₂ were subjected to finish annealing at 1000 ° C. × 10 seconds in an atmosphere which is _{0.0005 (10% H 2 -90%} N 2 atmosphere, dew point -50 ° C.). At that time, cooling at 700 to 500 ° C. was performed under the conditions shown in Table 2, and an insulating film was applied to the steel sheet to obtain a non-oriented electrical steel sheet. Then, strain annealing was performed at 750 ° C. for 2 hours in a 100 vol% N ₂ atmosphere.

The iron loss W _15/50 and the magnetic flux density B ₅₀ of the finished annealed plate obtained as described above were measured, and the adhesion of the coating of the obtained strain-removing annealed plate was investigated. The magnetic characteristics were evaluated by collecting an Epstein test piece of 30 mm x 280 mm with a 25 cm Epstein device, and the adhesion was evaluated by bending 90 ° of 50 mmφ and the peeling area (%) of the film after peeling the adhesive tape in the bent part. ). The conditions such as the material of the adhesive tape and the tape peeling speed conformed to JIS Z 0237. The results are also shown in Table 2.

From Tables 1 and 2, it is possible to obtain a non-oriented electrical steel sheet having excellent magnetic properties by controlling the composition of the steel material and the cold rolling rolling reduction ratio within the range of the present invention, while avoiding a significant cost increase. Understand.

Claims (3)

By mass%
C: 0.0050% or less,
Si: 0.99% or more and 3.05% or less,
Mn: 0.050% or more and 3.00% or less,
P: 0.10% or less,
S: 0.0050% or less,
N: 0.0050% or less,
Al: 0.0009% or less and B: 0.00030% or less, and in mass%,
Sn: 0.05% or more and 0.50% or less and / or Sb: 0.05% or more and 0.50% or less
further,
By mass%
Ca: 0.0001% or more and 0.0300% or less,
REM: 0.0001% or more and 0.0300% or less and
Mg: A steel slab containing one or two or more selected from 0.0001% or more and 0.0300% or less and having a component composition consisting of Fe and unavoidable impurities is hot-rolled to obtain a hot-rolled steel sheet.
The hot-rolled steel sheet is pickled and
The hot-rolled steel sheet that has been pickled is cold-rolled once or two or more times with intermediate annealing sandwiched between them to obtain a cold-rolled steel sheet.
A method for producing a non-oriented electrical steel sheet, in which the cold-rolled steel sheet is finish-annealed and then coated.
The finish annealing is a non-directional electromagnetic wave in which cooling from 700 ° C. to 500 ° C. is performed over 1 to 300 seconds in an oxidizing atmosphere having an oxygen potential of PH ₂ O / PH ₂ of 0.0010 or more. Method of manufacturing steel plate. By mass%
C: 0.0050% or less,
Si: 0.99% or more and 3.05% or less
Mn: 0.050% or more and 3.00% or less,
P: 0.10% or less,
S: 0.0050% or less,
N: 0.0050% or less,
Al: 0.0009% or less and B: 0.00030% or less, and in mass%,
Sn: 0.05% or more and 0.50% or less and / or Sb: 0.05% or more and 0.50% or less
further,
By mass%
Ca: 0.0001% or more and 0.0300% or less,
REM: 0.0001% or more and 0.0300% or less and
Mg: A steel slab containing one or two or more selected from 0.0001% or more and 0.0300% or less and having a component composition consisting of Fe and unavoidable impurities is hot-rolled to obtain a hot-rolled steel sheet.
The hot-rolled steel sheet is pickled and
The hot-rolled steel sheet that has been pickled is cold-rolled once or two or more times with intermediate annealing sandwiched between them to obtain a cold-rolled steel sheet.
A method for producing a non-oriented electrical steel sheet, in which the cold-rolled steel sheet is finish-annealed and then coated.
The rolling reduction in cold rolling immediately before the finish annealing is 85% or more.
The finish annealing is a non-directional electromagnetic wave in which cooling from 700 ° C. to 500 ° C. is performed over 1 to 300 seconds in an oxidizing atmosphere having an oxygen potential of PH ₂ O / PH ₂ of 0.0010 or more. Method of manufacturing steel plate. The component composition further
By mass%
The method for producing a non-oriented electrical steel sheet according to claim 1 or 2 , wherein As: contains 0.0050% or less.