JP2004197217A - Nonoriented electrical steel sheet excellent in circumferential magnetic property, and production method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonoriented electrical steel sheet in which circumferential magnetic properties inside the steel face can be improved. <P>SOLUTION: The electrical steel sheet is produced in such a manner that alloy components to be added and (Si, Al and Mn), the corelation in the contents of the alloy elements, impurity elements (C, S, N, Ti, V, Zr, Nb and As), the crystal grain size after hot rolled sheet annealing, and the draft in cold rolling are controlled for improving the circumferential magnetic properties inside the sheet face. Thus, the ä100} texture after finish annealing is developed, and, isotropically excellent magnetic properties inside the steel sheet face can be obtained when the steel sheet is used as an iron core material, particularly, in the case of an iron core of a rotating machine. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a non-oriented electrical steel sheet having excellent magnetic properties, which is used as a core material for electrical equipment, and particularly to a non-oriented electrical steel sheet having excellent magnetic properties all over the in-plane of a steel sheet, which is desirable as a rotating machine core material. An object of the present invention is to provide a grain-oriented electrical steel sheet and a method for manufacturing the same.

  In recent years, in the fields of electrical machinery, especially rotating machines, small and medium-sized transformers, and electrical components, in which non-oriented electrical steel sheets are used as the core material, global power and energy savings and global Thus, demands for higher efficiency and smaller size are increasing. Under such a social environment, improvement of the performance of non-oriented electrical steel sheets is naturally urgently required as an urgent issue.

  As is well known, a number of measures have been taken to improve the performance of non-oriented electrical steel sheets. Regarding reduction of iron loss, a method of increasing the content of Si, Al, or the like has been generally adopted from the viewpoint of reducing eddy current loss due to an increase in electric resistance. However, in this method, on the other hand, there is a problem that a decrease in magnetic flux density cannot be avoided.

  In addition to simply increasing the content of Si, Al, or the like, impurities such as C, S, N, or other high-purity steels or chemical treatment such as the addition of Ca described in Patent Document 1 are added. Iron loss has also been reduced by detoxification and the like. Further, measures in the manufacturing process such as devising finish annealing conditions as described in Patent Document 2 have been taken. On the other hand, for increasing the magnetic flux density, measures in the manufacturing process such as devising hot-rolled sheet annealing conditions and cold-rolling conditions as described in Patent Document 3, and Sn as described in Patent Document 4 Treatments such as improvement of primary recrystallization texture by addition of alloying elements such as Cu and Cu have been made.

  However, even though the magnetic properties of the non-oriented electrical steel sheet are improved by the above-described treatment, when the steel sheet is used for electric equipment as an iron core of a rotating machine or the like, usually the steel sheet rolling specified by JIS or the like is used. In addition to the average magnetic properties in the direction and in the direction perpendicular to the steel sheet plane, the steel sheet is required to have all-round magnetic properties in the plane of the steel sheet, that is, isotropically excellent magnetic properties in the plane. For this purpose, it is desirable to develop {100} texture of the non-oriented electrical steel sheet.

As a means for developing {100} texture in a non-oriented electrical steel sheet, as described in Patent Document 5, the rolling reduction of cold rolling is set to 85% or more, preferably 90% or more. In addition, there is a method in which the finish annealing is performed at 700 to 1200 ° C. for a long time of 2 minutes to 1 hour. However, performing such high-pressure cold rolling and long-time finish annealing reduces productivity and production cost. , And furthermore, there has been a problem with equipment restrictions, and it has not been put to practical use.
As described in Patent Literature 6 and Patent Literature 7, special production methods such as a rapid solidification method in which molten steel is solidified by a cooling body surface to be moved and renewed to form a thin strip have been developed, but due to equipment limitations. Problems and problems with stable productivity, etc., have not yet been put to practical use.
JP-A-3-126845 JP-A-61-231120 JP-A-4-325629 JP-A-5-140648 JP-B-51-942 JP-A-5-279740 JP-A-5-306438

  In view of the above, the present invention provides a non-oriented electrical steel sheet that develops {100} texture in a non-oriented electrical steel sheet and is excellent as a rotating machine core material and has excellent in-plane magnetic properties in the entire surface of the steel sheet and a method of manufacturing the same. Is provided.

  The present inventors have developed {100} texture by a combination of crystal structure control before cold rolling and cold rolling reduction in a normal production process of a non-oriented electrical steel sheet, and From the viewpoint of obtaining a non-oriented electrical steel sheet with excellent peripheral magnetic properties, we have conducted intensive studies. As a result, the magnetic flux density in the rolling direction of the steel sheet, the magnetic flux density difference from the vertical direction in the sheet surface, the magnetic flux density in the direction of 22.5 degrees in the sheet surface from the rolling direction, and the magnetic fluxes in the directions of 67.5 degrees and 45 degrees If the density B50 difference is controlled within a certain range, excellent iron loss characteristics can be obtained when used as a rotating machine core, and the manufacturing method is to increase the crystal grain size before cold rolling to a certain value or more. By doing so, it was clarified that it is possible to select the rolling reduction of the cold rolling appropriately and to improve the in-plane magnetic properties all around the plate by short-time continuous finish annealing.

The present invention has been made based on the above findings, and the gist is as follows.
(1) In mass%,
C: 0.002% or less, Si: 0.8% or more and 4.0% or less,
Al: 0.1% or more and 2.0% or less, Mn: 0.1% or more and 1.5% or less, and
Si + 2Al-Mn: 2% or more,
In the steel consisting of the balance of Fe and unavoidable impurity elements, the magnetic flux density B50 in the rolling direction is 1.69 T or more, the difference from the magnetic flux density B50 in the vertical direction in the plate surface is less than 0.03 T, and When the magnetic flux density B50 in the 22.5-degree direction is 1.65 T or more, the difference from the magnetic flux density B50 in the 67.5-degree direction is less than 0.04 T, and the difference from the magnetic flux density B50 in the 45-degree direction is 0. A non-oriented electrical steel sheet having excellent magnetic properties all around, which is less than 0.06T.
(2) In mass%,
Sn: 0.02 to 0.40%, Cu: 0.1 to 1.0%
The non-oriented electrical steel sheet according to the above (1), which comprises one or two of the following.

(3) In mass%,
C: 0.002% or less, Si: 0.8% or more and 4.0% or less,
Al: 0.1% or more and 2.0% or less, Mn: 0.1% or more and 1.5% or less, and
Si + 2Al-Mn: 2% or more,
In the method for producing a non-oriented electrical steel sheet, a steel comprising the balance of Fe and unavoidable impurity elements is subjected to hot rolling, hot-rolled sheet annealing, and finally to a final sheet thickness by one cold rolling, and then subjected to finish annealing. The average grain size after hot-rolled sheet annealing is 400 µm or more, cold rolling is performed at a rolling reduction of 80% to 90%, and finish annealing is performed at 800 ° C to 950 ° C for 10 seconds to 1 minute. A method for producing a non-oriented electrical steel sheet having excellent circumferential magnetic properties, characterized by:
(4) A non-directional steel having excellent all-round magnetic characteristics as described in (3), characterized by using steel in which each of S, N, and Ti as unavoidable impurities is 0.002% or less in mass%. Manufacturing method of conductive electrical steel sheet.
(5) The full-circumferential magnetism as described in (3) or (4) above, wherein the steel is used in which each of V, Zr, Nb, and As as inevitable impurities is 0.003% or less in mass%. A method for producing non-oriented electrical steel sheets with excellent properties.

  INDUSTRIAL APPLICABILITY As described above, according to the present invention, it is possible to provide a non-oriented electrical steel sheet having practically preferable characteristics as a rotating machine iron core material and excellent in in-plane magnetic properties in the entire surface of the steel sheet. In particular, it can sufficiently meet the requirements in the field of rotating machines and the like in which non-oriented electrical steel sheets are used as its core material, and its industrial value is extremely high.

Hereinafter, the present invention will be described in detail.
First, the reasons for limiting the steel components of the present invention will be described.
C is a harmful component that increases iron loss and causes magnetic aging. Therefore, the content of C is set to 0.002% or less.

  As described above, Si is a component having an effect of reducing iron loss by increasing eddy current loss by increasing electric resistance. To exhibit this effect, Si is contained at 0.8% or more. There is a need. On the other hand, when the content increases, as described above, the magnetic flux density decreases, and also causes an increase in hardness, deteriorates the punching workability, and also in the manufacturing process itself of the non-oriented electrical steel sheet, Since the workability such as cold rolling is lowered and the cost is increased, the content is set to 4.0% or less.

  Al is also a component having the effect of reducing iron loss by increasing electric resistance and reducing eddy current loss as in the case of Si, as described above. Has the effect of promoting the nature. In order to exhibit these effects, it is necessary to contain 0.1% or more. On the other hand, when the content increases, the magnetic flux density decreases, and the yield ratio decreases, thereby deteriorating the punching workability.

  Mn also has the effect of reducing iron loss by increasing eddy current loss by increasing electrical resistance. For this purpose, it is necessary to contain 0.1% or more. However, when the content increases, the crystal grain growth itself during annealing of the hot-rolled sheet decreases, so the content is set to 1.5% or less.

  In addition, it is necessary to satisfy the relationship of Si + 2Al-Mn: 2% or more between the above-mentioned alloy element components Si, Al, and Mn. This is because if Si + 2Al-Mn is less than 2%, a chemical component system in which α-γ transformation exists is present, and transformation occurs during annealing in the manufacturing process of a non-oriented electrical steel sheet, particularly during hot-rolled sheet annealing, which is a feature of the present invention. The formation of the {100} texture after the finish annealing is suppressed, and even if the rolling reduction of the subsequent cold rolling is controlled, the development of {100} texture is suppressed, This is because improvement in the circumferential magnetic properties is hindered.

  Sn is necessary because it has the effect of developing the primary recrystallized texture of the steel sheet into a desirable (100) or (110) texture for the magnetic properties and suppressing a (111) texture undesirable for the magnetic properties. Add according to. For this purpose, it is necessary to contain 0.02% or more. On the other hand, even if the content increases, the effect is saturated, and rather the crystal grain growth during annealing is suppressed, resulting in deterioration of magnetic properties. Therefore, the content is set to 0.40% or less.

  Cu, like Sn, has the effect of developing the primary recrystallization texture of the steel sheet to a desirable one in terms of magnetic properties. Therefore, Cu is added as necessary. In order to exhibit this effect, it is necessary to contain 0.1% or more. However, when the content increases, hot embrittlement is caused, and workability in hot rolling or the like in a manufacturing process of the non-oriented electrical steel sheet is reduced.

  S inhibits recrystallization and crystal grain growth after hot rolling due to fine precipitation of sulfides such as MnS, so that the crystal grain size becomes coarse after hot-rolled sheet annealing, and the hot-rolled sheet texture accompanying this Therefore, the content is set to 0.002% or less.

  N inhibits recrystallization and crystal grain growth after hot rolling due to fine precipitation of nitrides such as AlN and TiN, resulting in coarsening of crystal grain size after hot-rolled sheet annealing, and accompanying hot rolling. Since the plate texture is prevented from being randomized, the content is made 0.002% or less.

  Ti raises the recrystallization temperature and delays recrystallization and subsequent crystal grain growth during annealing in the process of manufacturing a non-oriented electrical steel sheet. In addition, the {111} texture that is not preferable for the magnetic properties of the non-oriented electrical steel sheet is developed. Further, in combination with the fine precipitation of TiN, TiC, etc., the coarsening of the crystal grain size after the annealing of the hot-rolled sheet and the accompanying randomization of the texture of the hot-rolled sheet are hindered. And

  V, Zr, and Nb inhibit recrystallization and crystal grain growth after hot rolling due to fine precipitation of carbides and nitrides such as VN and VC, and increase the crystal grain size after hot-rolled sheet annealing, and Since the randomization of the texture of the hot-rolled sheet is prevented, the content of each is set to 0.003% or less.

  As by itself does not form the above-mentioned fine precipitates within the steel composition range of the present invention. However, when As is contained, fine precipitation of sulfides such as MnS is promoted, and recrystallization and crystal grain growth after hot rolling are hindered. In addition, since the randomization of the texture of the hot-rolled sheet is prevented, the content is set to 0.003% or less. The components other than the above-mentioned components are Fe and unavoidable impurity elements.

Next, a description will be given of a characteristic of the present invention, that is, a relationship between a change in magnetic properties around the entire surface of the steel sheet in the plate surface and an iron loss when the steel sheet is used as a rotating machine core.
Using steel slabs of the components shown in Table 1, the hot rolling conditions, hot rolled sheet annealing conditions, cold rolling conditions, etc. were adjusted, and six types of 0.35 mm thick having the all-around magnetic properties shown in Table 2 Non-oriented electrical steel sheet was obtained. These non-oriented electrical steel sheets were processed into a four-pole motor core and laminated, and the motor core iron loss / material iron loss ratio, that is, BF (building factor) was measured. Table 3 shows the measurement results.

By manipulating the manufacturing conditions of the steel sheet to change the magnetic properties around the entire surface of the steel sheet, uniformity can be obtained in all directions in the steel sheet plane obtained when {100} <Ovw> texture develops. Even if the magnetic properties are not necessarily realized, the ratio of motor core iron loss to material iron loss, that is, BF (building factor) can be reduced, and a non-oriented electrical steel sheet which is practically preferable as a rotating machine iron core material can be obtained. I understand.
In particular, when the magnetic flux density B50 in the rolling direction is 1.69 T or more, the difference in magnetic flux density B50 from the vertical direction in the plate surface is less than 0.03 T, and the magnetic flux density B50 in the direction 22.5 degrees in the plate surface from the rolling direction is 1. The magnetic flux density B50 difference from the 67.5 degree direction at 65T or more is less than 0.04T, and the magnetic flux density B50 difference from the 45 degree direction is less than 0.06T. In No. 6, a non-oriented electrical steel sheet having a remarkably low BF and excellent as a motor core material is realized.

  As described above, the features of the present invention include the magnetic flux density in the rolling direction of the steel sheet, the difference in the magnetic flux density from the vertical direction in the sheet surface, the magnetic flux density in the direction of 22.5 degrees in the sheet surface from the rolling direction, and the direction of 67.5 degrees. By controlling the difference in magnetic flux density B50 from the 45 ° direction to a certain range, it is possible to provide a non-oriented electrical steel sheet having practically excellent iron loss characteristics when used as a rotating machine iron core.

In this case, the magnetic flux density B50 in the steel sheet rolling direction needs to be 1.69T or more. If it is less than 1.69T, the magnetic field used by the rotating machine must be reduced, and the BF increases to deteriorate the iron loss characteristics. The difference between the magnetic flux density B50 in the rolling direction of the steel sheet and the magnetic flux density B50 in the vertical direction in the plate surface must be less than 0.03T. With a difference of 0.03T or more, BF increases.
Further, the magnetic flux density B50 in the direction of 22.5 degrees in the plate surface from the rolling direction needs to be 1.65T or more. If it is less than 1.65 T, the magnetic field used by the rotating machine must be reduced, and BF increases to deteriorate iron loss characteristics.
The difference between the magnetic flux density B50 in the direction of 22.5 degrees in the plate surface from the rolling direction and the magnetic flux density B50 in the direction of 67.5 degrees is less than 0.04T, and the difference between the magnetic flux density B50 in the direction of 45 degrees is 0. 0.06T or less. When these differences are 0.04T or more and 0.06T or more, respectively, BF increases. In addition, if the steel has the chemical composition specified in the present invention, excellent all-round magnetic properties can be obtained under the following manufacturing conditions.

  Next, the effect of the combination of the crystal grain size after the hot-rolled sheet annealing and the rolling reduction of the cold rolling on the magnetic properties, which is a feature of the present invention, will be described. After hot rolling a steel slab having the components shown in Table 4 to a thickness of 2.8 mm, it was subjected to hot rolled sheet annealing under the annealing conditions shown in Table 5 to change the crystal grain size after hot rolled sheet annealing, Cold rolling reduction is also changed, and after finishing annealing at 900 ° C. for 30 seconds, different angles (rolling direction, 22.5 degree direction, 45 degree direction, 67.5 degree direction, direction perpendicular to the rolling direction) An Epstein sample was taken and magnetic properties (magnetic flux density: B50) were measured. Table 5 also shows the measurement results.

Improve the entire in-plane magnetic properties by short-time continuous annealing at 900 ° C for 30 seconds by combining the average grain size after cold rolling, that is, the average grain size after annealing of the hot rolled sheet, and the rolling reduction of the cold rolling. We can see that we can do it. In particular, the average grain size after annealing of the hot-rolled sheet was coarsened to 400 μm or more, and the rolling reduction of the cold rolling was controlled to 85%. In No. 5, a non-oriented electrical steel sheet having remarkably high B50 (average value over the entire circumference) and excellent magnetic properties over the entire circumference can be obtained. In this case, by increasing the average crystal grain size after the hot-rolled sheet annealing to 400 μm or more, randomization of the hot-rolled sheet texture is also promoted, and after the hot-rolled sheet annealing, that is, the average before cold rolling. The coarsening of the crystal grain size and the random texture promote the development of {100} texture after finish annealing due to the synergistic effect of the rolling reduction control of the cold rolling, and the remarkable magnetic properties all around the sheet surface It is presumed to have contributed to the improvement.
As described above, the feature of the present invention is that the combination of the crystal grain size after the hot-rolled sheet annealing and the rolling reduction of the cold rolling makes it possible to perform the short-time continuous finish annealing and the excellent non-directionality of the in-plane magnetic properties all around the sheet surface. Manufacture of electrical steel sheets.

  The average crystal grain size after hot-rolled sheet annealing needs to be 400 μm or more. When the average crystal grain size of the hot-rolled sheet is less than 400 mm, it is not possible to improve the in-plane magnetic properties all over the sheet even if the rolling reduction of the cold rolling is controlled. Incidentally, if the impurity element content of the steel specified in the present invention, the hot rolling sheet annealing conditions, that is, the annealing temperature and time, by appropriately selecting within the normal manufacturing process range of non-oriented electrical steel sheet, heat The average crystal grain size after the strip annealing can be 400 μm or more.

  The rolling reduction of the cold rolling is 80% or more and 90% or less. If it is less than 80%, the anisotropy of the magnetic properties increases, and the magnetic properties all around the plate surface are not improved. On the other hand, if it exceeds 90%, although the anisotropy of the magnetic properties decreases, the {111} texture unfavorable for the magnetic properties of the non-oriented electrical steel sheet develops, and the magnetic flux density decreases.

  The finish annealing is performed at 800 ° C. to 950 ° C. for 10 seconds to 1 minute. If the temperature is lower than 800 ° C., the anisotropy of the magnetic properties increases, and the magnetic properties all around the plate surface are not improved. On the other hand, when the temperature exceeds 950 ° C., although the anisotropy of the magnetic properties decreases, the {111} texture unfavorable for the magnetic properties of the non-oriented electrical steel sheet develops, and the magnetic flux density decreases. If the time is less than 10 seconds, the sizing properties of the crystal grains are poor, leading to a decrease in magnetic flux density and an increase in iron loss. On the other hand, if it exceeds 1 minute, the effect is saturated, and a decrease in productivity and an increase in manufacturing cost are also caused.

  Incidentally, steel having a chemical composition characterized by the present invention is melted in a converter or an electric furnace or the like, and after being cast into a slab by slab rolling after continuous casting or ingot casting, after the above-described hot rolling and thereafter. Processing is performed.

Next, examples of the present invention will be described.
(Example 1)
A 0.50 mm thick non-oriented electrical steel sheet containing the components shown in Table 6 and having the magnetic properties shown in Table 7 was processed and laminated on an 8-pole motor core, and the ratio of motor core iron loss / material iron loss was obtained. That is, BF (building factor) was measured. Table 7 also shows the measurement results.

In Table 7, No. of the comparative example. 11 and 12 have predetermined circumferential magnetic properties, that is, the magnetic flux density B50 in the rolling direction is 1.69T or more, the difference in magnetic flux density B50 from the vertical direction in the plate is less than 0.03T, Any of the conditions in which the magnetic flux density B50 in the 22.5 degree direction is 1.65 T or more and the magnetic flux density B50 difference in the 67.5 degree direction is less than 0.04 T, and the magnetic flux density B50 difference in the 45 degree direction is less than 0.06 T Is not satisfied, the BF is large.
In addition, in Comparative Example No. 14, 15, and 16 do not satisfy the predetermined all-round magnetic characteristics, and thus have a large BF. In particular, since Si + 2Al-Mn is less than 2%, it is difficult to develop {100} <Ovw> texture, which promotes an increase in BF.
On the other hand, in the example of the present invention, no. No. 13 satisfies a predetermined magnetic property around the entire circumference, so that the core loss is low and the BF is extremely low.
Thus, according to the present invention, it can be seen that a non-oriented electrical steel sheet having excellent magnetic properties all around which excellent iron loss properties can be obtained when used as a rotating machine core.

(Example 2)
A non-oriented electrical steel sheet having a thickness of 0.35 mm and containing the components shown in Table 8 and having the magnetic properties shown in Table 9 was processed and laminated on a 4-pole motor core, and the ratio of motor core iron loss to material iron loss was obtained. That is, BF (building factor) was measured. Table 9 also shows the measurement results.

In Table 9, No. of the comparative example. Reference numerals 21 to 24 denote predetermined circumferential magnetic properties, that is, the magnetic flux density B50 in the rolling direction is 1.69 T or more, the difference in magnetic flux density B50 from the vertical direction in the plate is less than 0.03 T, Any of the conditions in which the magnetic flux density B50 in the 22.5 degree direction is 1.65 T or more and the magnetic flux density B50 difference in the 67.5 degree direction is less than 0.04 T, and the magnetic flux density B50 difference in the 45 degree direction is less than 0.06 T Is not satisfied, the BF is large.
On the other hand, in the example of the present invention, no. No. 25 satisfies a predetermined magnetic property around the entire circumference, so that the BF is extremely low.
It can be seen that the present invention can provide a non-oriented electrical steel sheet having excellent magnetic properties all around, which provides excellent iron loss properties when used as a rotating machine core.

(Example 3)
The steel having the composition shown in Table 10 was hot-rolled to a thickness of 1.5 mm, 2.7 mm, and 4.2 mm, and then hot-rolled at 1000 ° C. for 2 minutes, and cooled to a thickness of 0.35 mm. After the cold rolling, finish annealing was performed at 850 ° C. for 30 seconds. Thereafter, Epstein samples were sampled at different angles (rolling direction, 22.5 degree direction, 45 degree direction, 67.5 degree direction, direction perpendicular to the rolling direction), and the magnetic properties were measured. Table 11 shows the measurement results. The average value of the magnetic properties over the entire circumference was determined by (rolling direction + 2.22.2 ° direction + 2.45 ° direction + 2.67.5 ° direction + perpendicular to rolling direction) / 8.
According to the present invention, it can be seen that it is possible to manufacture a non-oriented electrical steel sheet having excellent in-plane magnetic properties all over the surface.

(Example 4)
The steel having the components shown in Table 12 was hot-rolled to a thickness of 3.3 mm, and then subjected to hot-rolled sheet annealing at 1020 ° C. for 2 minutes, and then cold-rolled to a thickness of 0.50 mm (reduction ratio of cold rolling: 84). 8.8%), and then subjected to finish annealing at 930 ° C. for 40 seconds, and then Epstein according to the angles (rolling direction, 22.5 ° direction, 45 ° direction, 67.5 ° direction, perpendicular to the rolling direction). A sample was taken and the magnetic properties were measured. Table 13 shows the measurement results. The average value of the magnetic properties over the entire circumference was determined by (rolling direction + 2.22.2 ° direction + 2.45 ° direction + 2.67.5 ° direction + perpendicular to rolling direction) / 8.
According to the present invention, it can be seen that a non-oriented electrical steel sheet having excellent in-plane magnetic properties all over the plate surface can be obtained.

Claims (5)

In mass%,
C: 0.002% or less, Si: 0.8% or more and 4.0% or less,
Al: 0.1% or more and 2.0% or less, Mn: 0.1% or more and 1.5% or less, and
Si + 2Al-Mn: 2% or more,
In the steel consisting of the balance of Fe and unavoidable impurity elements, the magnetic flux density B50 in the rolling direction is 1.69 T or more, the difference from the magnetic flux density B50 in the vertical direction in the plate surface is less than 0.03 T, and When the magnetic flux density B50 in the 22.5-degree direction is 1.65 T or more, the difference from the magnetic flux density B50 in the 67.5-degree direction is less than 0.04 T, and the difference from the magnetic flux density B50 in the 45-degree direction is 0. A non-oriented electrical steel sheet having excellent magnetic properties all around, which is less than 0.06T. In mass%,
Sn: 0.02 to 0.40%, Cu: 0.1 to 1.0%
The non-oriented electrical steel sheet according to claim 1, wherein the non-oriented electrical steel sheet has one or two of the following. In mass%,
C: 0.002% or less, Si: 0.8% or more and 4.0% or less,
Al: 0.1% or more and 2.0% or less, Mn: 0.1% or more and 1.5% or less, and
Si + 2Al-Mn: 2% or more,
In the method for producing a non-oriented electrical steel sheet, a steel comprising the balance of Fe and unavoidable impurity elements is subjected to hot rolling, hot-rolled sheet annealing, and finally to a final sheet thickness by one cold rolling, and then subjected to finish annealing. The average grain size after hot-rolled sheet annealing is 400 µm or more, cold rolling is performed at a rolling reduction of 80% to 90%, and finish annealing is performed at 800 ° C to 950 ° C for 10 seconds to 1 minute. A method for producing a non-oriented electrical steel sheet having excellent circumferential magnetic properties, characterized by: 4. The non-oriented electrical steel sheet according to claim 3, wherein the steel is used in which the amount of S, N, and Ti as inevitable impurities is 0.002% or less by mass. Production method. 5. A non-directional steel having excellent all-round magnetic characteristics according to claim 3 or 4, wherein steel is used in which each of V, Zr, Nb, and As as unavoidable impurities is 0.003% or less by mass%. Manufacturing method of conductive electrical steel sheet.