JPH05209224A - Production of nonoriented silicon steel sheet excellent in magnetic property - Google Patents

Abstract

PURPOSE:To produce a high grade nonoriented silicon steel sheet excellent in magnetic properties by subjecting a hot rolled plate of steel having a specific composition containing C, Si, Mn, and Al to process annealing at specific temp. and to final cold rolling at specific draft. CONSTITUTION:A hot rolled plate of a steel having a composition which contains, by weight, <=0.01% C, >=2.5% Si, 0.1-1.0% Mn, and >=0.1% Al and in which (Si+Al) is regulated to <=4% is rolled, in the as-hot-rolled state or after hot rolled plate annealing, to the final sheet thickness by means of two or more cold rollings while process-annealed between the cold rolling stages, followed by finish annealing. At this time, the process annealing before the above finish annealing is done at 740-880 deg.C and then descaling treatment is performed, if necessary. By this method, the nonoriented silicon steel sheet reduced in iron loss value and excellent in magnetic properties can be obtained with certainty.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of a non-oriented electrical steel sheet having excellent magnetic properties, and particularly to a method for producing a high-grade non-oriented electrical steel sheet having an extremely low iron loss value.

[0002]

2. Description of the Related Art Non-oriented electrical steel sheets are mainly used for electric machines such as rotating machines and iron cores of transformers. High grade non-oriented electrical steel sheets, which are less oriented than the grain-oriented electrical steel sheets, are widely used because they are prized. Regarding such non-oriented electrical steel sheets, JIS C 2552 specifies 50A270 as a material with low iron loss, but in order to further save energy of electric equipment, this 50A270 is required.
The reality is that materials with lower iron loss are desired.

Conventionally, as techniques for reducing iron loss of non-oriented electrical steel sheets, (1) increase Si or Al content, (2) reduce or detoxify impurities (C, S, O, etc.) in steel. ,
(3) Optimization of grain size after finish annealing, (4) Adjustment of cold rolling reduction, (5) Method of performing two or more cold rolling steps with intermediate annealing, etc. have been adopted. ..

Due to such efforts to reduce iron loss, 50
A270-class high-grade non-oriented electrical steel sheets can now be manufactured, and are now in practical use. However, the methods of (2), (3), and (4) above have limitations in order to manufacture materials with lower iron loss than those of the 50A270 class, and the method of (1) above is compared to these methods. It is effective to increase the amount of Si, Si or Al. However, in this method as well, if Si or Al is increased, cracking is likely to occur during cold rolling. Therefore, the (Si + Al) content is 4 wt%.
(Hereinafter, simply expressed as%)
If it exceeds this, there is a problem that normal cold rolling becomes difficult. This problem can be solved by performing cold rolling at 150 ° C or higher during cold rolling,
There was another problem that it was difficult to maintain heat with a normal cold rolling mill and stable rolling could not be performed.

On the other hand, as a means for reducing iron loss, the above-mentioned means
The method (5) is also effective, and the present invention relates to an improvement of this method. As for this method, the method described below has been proposed. For example, Japanese Examined Sho 56
-22931 discloses that S contained in the material is 0.005% or less,
Disclosed is a method in which O is 0.0025% or less, the reduction ratio of the second cold rolling performed after the intermediate annealing is 40 to 70%, and the finish annealing is performed at 900 to 1000 ° C. This method improves the magnetic properties by improving the texture by improving the composition of components and devising the second cold rolling reduction rate (under high pressure). Further, in Japanese Patent Laid-Open No. 53-66816, S contained in the material is 0.005% or less, O is 0.0025% or less, the first cold rolling reduction is 20% or more, and the intermediate annealing is 900 to 1050 ° C. ~ 15
The average grain size after intermediate annealing is
Adjust the thickness to 0.07 mm or more, and then finish by cold finishing rolling with a rolling reduction of 45 to 70% to obtain a finished thickness.
Disclosed is a method of performing finish annealing under conditions of ~ 15 minutes. In addition to the method disclosed in Japanese Patent Publication No. 56-22931, this method is a technology for improving the magnetic properties by controlling the grain size after intermediate annealing to improve the texture.
According to the above-mentioned respective prior art methods, 50A270 to 50A25
It was effective for manufacturing up to 0 class. However,
At the present time when improvements have been made by the methods (2), (3), and (4) above, a slight improvement in magnetic properties has been observed with this method alone compared to the method in which ordinary cold rolling to annealing is performed once each. Is simply
It wasn't a big improvement.

Further, there is also a method disclosed in Japanese Patent Laid-Open No. 58-23410. This technology uses the material Si
2.5% or more, Al 1% or more, and cold rolling reduction before finish annealing 55 to 87%, finish annealing 1050 ° C or more, 3 seconds
This is a method performed under the condition of ~ 60sec. However, in the case of this method, although it is intended to fix N by Al and detoxify it and reduce internal oxidation by high temperature short time annealing, this treatment alone does not dramatically improve the texture. Also, at the current level of annealing technology, although some internal oxidation is certainly observed during annealing, magnetic deterioration is very slight. Therefore, also in the case of this method, the texture improving effect, which is more than the method of performing cold rolling to annealing twice, cannot be expected.

Next, there is a method proposed in JP-A-58-23411. This technology applies intermediate annealing from 950 to 1100.
℃, 20 ~ less than 120 sec, the final cold rolling reduction rate of 35 ~
This is a method in which 45% is used and finish annealing is performed under the conditions of 950 to 1100 ° C and 3 to 60 seconds. However, in the case of this method, the magnetic properties are improved by the combination of the intermediate annealing condition and the final cold rolling reduction ratio and the prevention of the internal oxynitride layer by the high temperature short time annealing, but in the test conducted by the inventors, According to this method, Japanese Patent Publication No. 56-22931 or Japanese Patent Laid-Open No. 53-
It was not possible to obtain the results of magnetic characteristics exceeding the method of 66816. Therefore, it is considered that the combination of intermediate annealing and final cold rolling reduction is not necessarily appropriate.

Further, there is a method proposed in JP-A-59-74225. This technology uses S for material of 15ppm or less and O for
20ppm or less, N 25ppm or less, intermediate annealing 950 ~ 10
This method is performed at 50 ° C for 2 to 15 minutes and the cold rolling reduction of the second time is 70% or more. The impurities are further reduced than any of the above methods, and the intermediate annealing suitable for the material and the second time By finding the cold rolling reduction ratio of, the improvement of the texture and the improvement of magnetic properties are aimed at. However, even with this method,
This is aimed at the development of the A250 class, and it is a difficult method to stably manufacture materials with lower iron loss than 50A250.

The above-mentioned respective prior arts described above are characterized by a combination of both, in which the intermediate annealing is performed at a higher temperature of 900 to 1100 ° C. and the second cold rolling reduction is performed at 35% or more. It is believed that there is. Other cases include Shoko Sho
In the example described in Japanese Patent Laid-Open No. 56-22931, an example of intermediate annealing 900 ° C. × 5 minutes, second cold rolling reduction of 9.1% and finish annealing 1000 ° C. × 5 minutes is shown. This is to reduce the cold rolling reduction of the second time to around 10% and use strain energy to promote grain growth during finish annealing and improve magnetic properties. The texture is randomized, and it is not possible to obtain a magnetic property superior to 50A250.

[0010]

SUMMARY OF THE INVENTION The object of the present invention is to improve the magnetic property improving effect further in the above-mentioned method of repeating cold rolling to annealing twice or more, so that the iron loss value is more than that of the conventional product having the same composition. Another object of the present invention is to propose a new manufacturing method for high-grade non-oriented electrical steel sheet.

By the way, the inventors have found that cold rolling is easy (Si
+ Al): 4% or less of non-oriented electrical steel sheet, as a result of earnest studies to further improve the iron loss thereof, the result of cold annealing and annealing treatment repeated twice or more, finish annealing While performing the previous intermediate annealing at a relatively low temperature,
It was found that if the final cold rolling was carried out by light reduction rolling, the iron loss could be further reduced, and further, in addition to the implementation of this method, a descaling treatment should be performed once after the intermediate annealing. Then, it was found that the iron loss can be further reduced, and the first and second methods of the present invention were conceived.

That is, the first method of the present invention is C: 0.
01 wt% or less, Si: 2.5 wt% or more, Mn: 0.1 to 1.0 wt%,
A hot-rolled steel sheet having a composition containing Al: 0.1 wt% or more and Si + Al: 4 wt% or less is directly or after hot-rolled sheet annealed, and then cold-rolled twice or more with intermediate annealing. When manufacturing a non-oriented electrical steel sheet by rolling to the final plate thickness and then performing finish annealing, intermediate annealing before finish annealing is performed in the temperature range of 740 to 880 ° C, and final cold rolling is performed at a reduction ratio of 1 to 1. This is a method for producing a non-oriented electrical steel sheet having excellent magnetic properties, which is characterized by being performed at 10%.

The second method of the present invention is C: 0.01.
wt% or less, Si: 2.5 wt% or more, Mn: 0.1 to 1.0 wt%, A
l: 0.1% by weight or more and Si + Al: 4% by weight or less, hot-rolled steel sheet having a composition that is annealed as it is or after hot-rolled sheet is annealed. When manufacturing a non-oriented electrical steel sheet by rolling to the final plate thickness and then performing finish annealing, intermediate annealing before finish annealing is performed in the temperature range of 740 to 880 ° C, and after performing descaling treatment, This is a method for producing a non-oriented electrical steel sheet having excellent magnetic properties, characterized in that the final cold rolling is performed at a reduction rate of 1 to 10%.

[0014]

Next, the reason why the present invention is configured as described above will be described based on the results of experiments conducted by the inventors.
In this experiment, C: 0.003%, Si: 3.23%, Mn: 0.19%,
P: 0.016%, S: 0.0013%, Al: 0.61%, N: 0.0015
%, O: 0.0011%, a steel slab consisting of balance Fe and unavoidable impurities was made into a hot-rolled sheet with a thickness of 2 mm by a normal hot-rolling process, and this hot-rolled sheet was annealed under the condition of 1000 ° C × 30 sec, Intermediate plate thickness (0.5 to 0.588 m
m) The obtained cold-rolled sheet, (700 ~ 1000 ℃) × 15sec
15% after the second cold rolling after the intermediate annealing under the conditions
The plate thickness is set to 0.5 mm and 10
Finish annealing was carried out at 00 ℃ × 15sec. The results are shown in Figure 1 and Figure 2.
Shown in.

FIG. 1 shows the effect of iron loss (W 15/50) when the temperature of the intermediate annealing is changed and the cold rolling reduction of the second time is kept constant at 5%. For comparison, the one-time method (without intermediate annealing and the second cold rolling; other conditions are the same as above) and the two-time method (first cold rolling reduction: 50
%, Intermediate annealing: 1000 ℃ × 15sec, Second cold rolling reduction:
50%, other conditions are the same as above. The results of () are also shown in the figure. As can be clearly seen from this figure, the intermediate annealing temperature is 740 to 880 ° C, and a large decrease in iron loss is recognized as compared with the comparative method.

FIG. 2 shows that the intermediate annealing temperature is kept constant at 800 ° C.
It is a result when changing the reduction rate of the 2nd cold rolling between 0-15%. As in the case of FIG. 1, the results of the one-time method and the comparative two-time method are also shown. Here, the data of the reduction ratio of the second cold rolling is 0%, the sheet thickness is 0.5 mm in the first cold rolling.
The results are obtained when the final annealing is performed after the intermediate annealing. As can be seen from this figure, when the reduction ratio in the second cold rolling is 1 to 10%, a significant decrease in iron loss is recognized as compared with the comparative method. That is, the intermediate annealing is set to 740 to 880 ° C, and the reduction ratio of the second cold rolling is set to 1 to
It can be seen that the treatment example of the combination of 10% significantly reduces the iron loss.

Next, the present inventors conducted the following experiment in order to further improve the iron loss reduction by the final rolling in addition to the above-mentioned intermediate annealing at a relatively low temperature. In this experiment, C: 0.003%, Si: 3.23%, Mn: 0.19%,
P: 0.016%, S: 0.0013%, Al: 0.61%, N: 0.0015
%, O: 0.0011%, a steel slab consisting of balance Fe and unavoidable impurities was made into a hot-rolled sheet with a thickness of 2 mm by a normal hot-rolling process, and this hot-rolled sheet was annealed under the condition of 1000 ° C × 30 sec, Intermediate plate thickness (0.5 to 0.588 m
m) The obtained cold-rolled sheet, (700 ~ 1000 ℃) × 15sec
After the intermediate annealing under the conditions of No. 3, both surfaces were polished with a No. 320 polishing belt and descaled. 2 in succession
By performing the cold rolling for the second time at a reduction rate of 15% or less,
The plate thickness was 0.5 mm, and finish annealing was performed at 1000 ° C for 15 seconds.
The results are shown in FIGS.

FIG. 1 showing an example in which the descaling process is not performed,
As can be seen from comparison with the results of FIG. 2, the iron loss is generally low when the descaling treatment is performed, and it is understood that the effect of the descaling treatment after the intermediate annealing is large.

The reason why the magnetic properties are improved when the above-mentioned method of the present invention is carried out has not been completely clarified yet, but firstly, "appropriate intermediate annealing temperature before finish annealing" and " It is presumed that this is due to the result that the texture after finishing annealing is improved by the selected combination of "appropriate reduction ratio of final cold rolling". That is, according to the present invention,
The grain size is controlled by intermediate annealing before finish annealing at a relatively low temperature, while the reduction ratio of final cold rolling is reduced. It is considered that the way of entering changes, and therefore the texture after finish annealing is improved.

Secondly, by performing the descaling treatment before the final cold rolling, the state of the steel sheet surface is changed, which greatly influences how the working strain enters during the subsequent final cold rolling. It is considered to change the texture after finish annealing in a better direction.

In this regard, in the conventional method of repeating cold rolling to annealing twice (or more), setting the reduction ratio of the final cold rolling to about 10% or less randomizes the texture. It has been recognized that this is only a method for measuring grain growth during finish annealing by utilizing the strain energy of cold rolling before finish annealing. On the other hand, the inventors of the present invention, from the above experimental results, to control the grain size in advance by performing intermediate annealing before finish annealing at a relatively low temperature, and if the final cold rolling is performed under a light pressure. In addition, it has been newly found that the texture can be greatly improved and further reduction of iron loss can be achieved.

Furthermore, the combination of the descaling treatment after the intermediate annealing and the relatively low temperature intermediate annealing and the final cold rolling under a light reduction work more effectively for improving the texture. This is an unknown knowledge.

Next, the reason for limiting the composition of the raw material components of the present invention as described above will be described. C: 0.01% or less C is a component harmful to iron loss, so 0.01% or less. Desirably 0.001% or less is also good from the viewpoint of magnetic aging.

Si: 2.5% or more Si is a useful element that increases specific resistance and decreases iron loss,
This invention is intended for high-grade non-oriented electrical steel sheets, so 2.
5% or more.

Al: 0.1% or more Al, like Si, is a useful element that increases the specific resistance and decreases the iron loss, but if the content is less than 0.1%, AlN is finely precipitated and the iron loss is adversely affected. Since it is given, it should be 0.1% or more.

Si + Al: 4% or less Both Si and Al are elements useful for improving iron loss as described above, but if the total amount exceeds 4%, cold ductility deteriorates as described above, so 4%. Below.

Mn: 0.1-1.0% Mn is at least to prevent cracking during hot rolling.
Although 0.1% is included, if it exceeds 1.0%, only the cost increases and there is no other effect, so 1% was made the upper limit.

P does not have a great influence on the magnetic properties and is not particularly limited.

Impurity elements such as S, O, and N deteriorate the magnetic characteristics, so it is preferable that they be contained as little as possible.

Next, the method for manufacturing the non-oriented electrical steel sheet according to the present invention will be specifically described. Converter-molten steel of the composition defined in the present invention melted through a degasser, a continuous casting or ingot-a slab by slab rolling, and then subjected to heating and hot rolling to a hot rolled sheet To do.
This hot rolled sheet is subjected to hot rolled sheet annealing prior to cold rolling,
Then, after descaling, the final sheet thickness is obtained by cold rolling two or more times with intermediate annealing sandwiched, and then subjected to finish annealing.

In the above process, the thickness of the hot rolled sheet is usually 2.0 to
Although it is 2.3 mm, it does not particularly affect the effects of the present invention, and thus is not particularly limited. Hot-rolled sheet annealing (900-11
(00 ° C) × (5 sec. To 1 minute) is suitable. This treatment has already been adopted in the production of high-grade non-oriented electrical steel sheets and is effective in improving the texture. The method of the present invention can improve the magnetic properties even when the hot-rolled sheet annealing is not performed, but the hot-rolled sheet annealing is necessary in order to manufacture an electromagnetic steel sheet having a lower iron loss. Although the above example is premised on continuous hot-rolled sheet annealing, it goes without saying that the same effect can be obtained by batch annealing.

The temperature of the intermediate annealing before the finish annealing is 740-88.
It shall be in the range of 0 ° C. A holding time of 5 seconds to 1 minute is suitable. Other intermediate annealing conditions are not particularly limited, but (900 to 1050 ° C.) × (5 sec. To 1 minute) is suitable.

Then, descaling is performed before the final cold rolling after the intermediate annealing. As a method for this descaling treatment, pickling, shot blasting, surface grinding, etc. are generally used, but other methods may be used as long as descaling is possible.

The final annealing is (900-1100 ° C) x (5
sec. ~ 1 minute) is appropriate. After finishing annealing, a coating is generally applied for the purpose of insulation and corrosion resistance.

[0035]

【Example】

Example 1 C: 0.002%, Si: 3.35%, Mn: 0.23%, P: 0.013
%, S: 0.0011%, Al: 0.62%, N: 0.0017%, O: 0.
A slab containing 0010% and the balance being substantially Fe composition was formed into a hot-rolled sheet with a thickness of 2 mm by a normal hot rolling process, and the hot-rolled sheet was annealed under the conditions shown in Table 1, No. , Descaling, cold rolling, intermediate annealing, cold rolling, finish annealing, sheet thickness
The product is 0.5 mm. The results are also shown in Table 1. It can be seen that the combination example of the intermediate annealing of 740 to 880 ° C and the reduction ratio of 2% in the second cold rolling reduces the iron loss.

Example 2 C: 0.003%, Si: 3.07%, Mn: 0.15%, P: 0.010
%, S: 0.0015%, Al: 0.41%, N: 0.0018%, O: 0.
A slab containing 0010% and the balance of substantially Fe is formed into a hot-rolled sheet having a thickness of 2 mm by a normal hot rolling process, and the hot-rolled sheet is annealed under the conditions shown in Table 1 and No. , Descaling, cold rolling, intermediate annealing, cold rolling, finish annealing, and plate thickness 0.
35mm product. The results are also shown in Table 1. It can be seen that the combination example of the intermediate annealing of 740 to 880 ° C. and the reduction ratio of the second cold rolling of 8% reduces the iron loss.

Example 3 C: 0.003%, Si: 2.61%, Mn: 0.17%, P: 0.017
%, S: 0.0018%, Al: 0.28%, N: 0.0019%, O: 0.
A slab containing 0012% and the balance substantially consisting of Fe is formed into a hot-rolled sheet having a thickness of 2.3 mm by an ordinary hot rolling process.
Hot-rolled sheet annealing, descaling under the conditions shown in Table 1, Nos. 15 to 20,
Cold rolled, intermediate annealed, cold rolled, finish annealed, sheet thickness
The product is 0.5 mm. The results are also shown in Table 1. It can be seen that the combination of the intermediate annealing of 780 ° C and the reduction ratio of 1 to 10% in the second cold rolling reduces the iron loss.

Example 4 A slab having the same composition as in Example 1 was subjected to a normal hot rolling process to obtain 2.3.
A hot rolled sheet having a thickness of mm was annealed under the condition of 1000 ° C. × 30 sec, descaled, and treated under the following conditions. 1st cold rolling reduction = 50% 1st intermediate annealing condition = 970 ° C x 30sec 2nd cold rolling reduction = 54.7% 2nd intermediate annealing condition = 800 ° C x 10sec 3rd cold rolling reduction = 4% Finish annealing condition = 1000 ° C. × 20 sec As a result, a value of W15 / 50 = 2.24 W / kg was obtained.

[0039]

[Table 1]

Example 5 C: 0.002%, Si: 3.35%, Mn: 0.23%, P: 0.013
%, S: 0.0011%, Al: 0.62%, N: 0.0017%, O: 0.
A slab containing 0010% and the balance being substantially Fe composition was formed into a hot-rolled sheet with a thickness of 2 mm by a normal hot rolling process, and the hot-rolled sheet was annealed under the conditions shown in Table 1, No. , Descaling, cold rolling, intermediate annealing, descaling by pickling, cold rolling,
Finish annealing was sequentially performed to obtain a product with a plate thickness of 0.5 mm. The results are also shown in Table 2. As is clear from the results shown in Table 2, in the combination example in which the intermediate annealing was performed at 740 to 880 ° C, the descaling treatment was performed after the intermediate annealing, and the reduction ratio of the second cold rolling was 2%, the iron loss It can be seen that the further reduction has been realized.

Example 6 C: 0.003%, Si: 3.07%, Mn: 0.15%, P: 0.010
%, S: 0.0015%, Al: 0.41%, N: 0.0018%, O: 0.
A slab containing 0010% and the balance substantially consisting of Fe was formed into a hot-rolled sheet having a thickness of 2 mm by a normal hot rolling process, and the same conditions as those shown in Table 1 and Nos. 8 to 14 were used. Hot-rolled sheet annealing, descaling, cold rolling, intermediate annealing, descaling with No. 120 polishing belt, cold rolling, and finish annealing were carried out in order to obtain a sheet thickness of 0.35 mm. The results are also shown in Table 2. As is clear from the results shown in Table 2, the intermediate annealing
It can be seen that in the combination example in which the descaling treatment was performed after the intermediate annealing at 740 to 880 ° C. and the reduction ratio of the second cold rolling was 8%, the iron loss was further reduced.

Example 7 C: 0.003%, Si: 2.61%, Mn: 0.17%, P: 0.017
%, S: 0.0018%, Al: 0.28%, N: 0.0019%, O: 0.
A slab containing 0012% and the balance substantially consisting of Fe is formed into a hot-rolled sheet having a thickness of 2.3 mm by an ordinary hot rolling process.
Hot-rolled sheet annealing, descaling under the conditions shown in Table 1, Nos. 15 to 20,
Cold rolling, intermediate annealing, descaling by shot blasting, cold rolling, and finish annealing were carried out in order to obtain a product with a plate thickness of 0.5 mm. The results are also shown in Table 2. As is clear from the results shown in Table 2, in the combination example in which the intermediate annealing was performed at 780 ° C., the intermediate annealing was followed by descaling, and the reduction ratio of the second cold rolling was 1 to 10%, It can be seen that the iron loss has been reduced.

Example 8 A slab having the same composition as in Example 5 was subjected to a normal hot rolling process to obtain 2.3.
A hot rolled sheet having a thickness of mm was annealed under the condition of 1000 ° C. × 30 sec, descaled, and treated under the following conditions. 1st cold rolling reduction = 50% 1st intermediate annealing condition = 970 ° C x 30sec 2nd cold rolling reduction = 54.7% 2nd intermediate annealing condition = 800 ° C x 10sec Descaling condition = No. 60 polishing belt 3rd cooling Rolling reduction = 4% Finish annealing condition = 1000 ° C x 20 sec As a result, iron loss W15 / 50 = 2.20 W / kg was obtained.

[0044]

[Table 2]

[0045]

As described above, according to the present invention, when producing a non-oriented electrical steel sheet having excellent magnetic properties, intermediate annealing is carried out before finish annealing at a relatively low temperature of 740 to 880 ° C,
Further, in addition to such intermediate annealing, descaling is further performed, and then, in the final cold rolling, a light reduction rolling with a reduction rate of 1 to 10% is performed. Furthermore, it is possible to surely obtain a non-oriented electrical steel sheet with low iron loss.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the intermediate annealing temperature and the iron loss in the method without the descaling treatment.

FIG. 2 is a graph showing the relationship between the second cold rolling reduction rate and the iron loss in the method without the descaling treatment.

FIG. 3 is a graph showing the relationship between intermediate annealing temperature and iron loss in the method of performing descaling treatment after intermediate annealing.

[Fig. 4] Fig. 4 is a view showing a method of performing descaling treatment after intermediate annealing.
The graph which shows the relationship between the cold rolling reduction of the 1st time and iron loss.

Claims (2)

[Claims] 1. A hot-rolled steel sheet having a composition containing C: 0.01 wt% or less, Si: 2.5 wt% or more, Mn: 0.1 to 1.0 wt%, Al: 0.1 wt% or more, and containing Si + Al: 4 wt% or less. As it is, or after hot-rolled sheet annealing, rolled to a final sheet thickness by two or more cold rolling steps with intermediate annealing.
After that, when manufacturing a non-oriented electrical steel sheet by performing finish annealing, the intermediate annealing before finish annealing is performed at 740 to 880.
A method for producing a non-oriented electrical steel sheet having excellent magnetic properties, which comprises performing the final cold rolling at a rolling reduction of 1 to 10% in a temperature range of ℃. 2. The manufacturing method according to claim 1, wherein descaling treatment is performed after the intermediate annealing, and then final cold rolling is performed.