JPH0814015B2 - Non-oriented electrical steel sheet having excellent magnetic properties and surface properties and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a non-oriented electrical steel sheet having excellent magnetic properties, particularly magnetic flux density, and good surface properties, and a method for producing the same.

[Conventional technology]

Non-oriented electrical steel sheets used as iron core materials for motors, transformers, etc. are required to have low iron loss and high magnetic flux density in order to make these electric devices highly efficient and compact.

In order to improve the magnetic properties of the non-oriented electrical steel sheet,
It has been conventionally known that it is advantageous to sufficiently coarsen the ferrite crystal grain size of the material before cold rolling. From this point of view, the following techniques have been disclosed as a method for improving magnetic properties.

1) After hot rolling, a technique of performing high temperature winding and self-annealing with the heat of the steel strip (for example, Japanese Patent Publication No.57-4313).
No. 2).

2) A technique of introducing 3 to 30% plastic strain in a hot state into a steel strip that has been hot-rolled at a temperature higher than the Ar ₃ transformation temperature, and winding and self-annealing at a high temperature (for example, Japanese Patent Laid-Open No. Sho 60). −258414
issue).

3) A technique of annealing a steel strip that has been hot-rolled under specific conditions in which the rolling end temperature and the coiling temperature are controlled (for example, JP-A-58-204126).

4) A technique of performing mild skin pass rolling on the steel strip after hot rolling and then annealing (for example, Japanese Patent Publication No.
JP-A-63-186823, JP-A-1-139721).

5) A technique of performing pre-annealing on the steel strip after hot rolling, then performing light cold rolling and further reheating to anneal (for example, Japanese Patent Laid-Open No. 1-191741).

[Problems to be Solved by the Invention]

Among the various techniques described above, the technique of self-annealing by high-temperature winding disclosed in JP-B-57-43132 and JP-A-60-258414 is insufficient in crystal grain growth of a hot rolled sheet. In order to make the crystal grains sufficiently coarse, it is necessary to wind the steel sheet at an extremely high temperature. However, when such high-temperature winding is performed, there is a problem that the pickling property in the subsequent step is deteriorated, grain boundary oxidation is more likely to occur, and the surface quality of the final product is impaired.

Further, in the technique of performing hot-rolled sheet annealing disclosed in JP-A-58-204126, it is necessary to set the hot-rolling end temperature to a low temperature of 700 ° C. or lower, which causes a problem that the load of the rolling mill increases. is there. Further, this technique is intended to obtain coarse grains by the secondary recrystallization abnormal grain growth using the grain boundary energy as a driving force, with the hot rolled steel strip before annealing of the hot rolled sheet having a fine crystal structure. Therefore, the tissue formation is unstable, and it is difficult to stably control the optimal pre-cold pressure tissue.

On the other hand, in the technique of annealing after applying mild rolling to the hot rolled sheets of 4) and 5) above, abnormal grain growth using strain energy as a driving force occurs, so that only the above-mentioned hot rolled sheet annealing is performed. Coarsening is promoted as compared with the case of performing.

However, in the technology disclosed in Japanese Examined Patent Publication No. Sho 45-22211, grain growth is inferior because C and S are high, and even if rolling strain is applied before hot-rolled sheet annealing, the structure is controlled to an optimal pre-cold pressure structure. Difficult to do. Furthermore, since a large amount of S forms sulfides and significantly deteriorates the magnetic properties themselves, even if it is possible to control the structure before the optimum cold pressure, the magnetic properties of the final product cannot be sufficiently improved. .

Further, as disclosed in JP-A-63-186823, by simply adding skin pass rolling before annealing the hot-rolled sheet, the steel composition, the hot-rolled sheet annealing temperature according to the rolling reduction of the light rolling. If the technology is not properly controlled, a non-uniform microstructure will be created in which coarse secondary recrystallized grains that have abnormally grown due to strain induction and primary recrystallized grains that remain fine grain are mixed, resulting in a magnetic property of the final product. In some cases, the uniformity at each position in the coil may be deteriorated, or the secondary recrystallized grains may be remarkably coarsened, and the traces thereof may remain rough on the surface of the steel sheet after cold rolling to form waviness. Especially in the latter case, the magnetic properties are improved with the coarsening of the crystal grain size, but on the other hand, the undulations formed are increased and the space factor is reduced, so that the motor,
There is a serious problem in that electrical equipment such as a transformer cannot be made highly efficient and miniaturized.

Further, Japanese Patent Application Laid-Open No. 1-139721 also discloses a technique of annealing after hot rolling a light rolled sheet, which is 1.0%.
The aim is to improve the texture and improve the magnetic properties by adding the above Mn and 0.1% or more of Ni together, and hot-rolled sheet annealing is the texture improving effect of this addition of Mn and Ni. Is a process for exhibiting, the structure of the present invention before cold rolling is optimized, magnetic properties,
It is not a technology aimed at improving both surface properties. Moreover, in this technique, since Mn and Ni added in large amounts both lower the α-γ transformation temperature and, at the same time, deteriorate the grain growth property, an optimum pre-cold rolling microstructure as intended by the present invention is obtained. Will be impossible.

Further, Japanese Patent Application Laid-Open No. 1-191741 discloses a technique of subjecting a hot-rolled steel strip to pre-annealing, light reduction rolling, and annealing, but this technique only coarsens the crystal grains before cold rolling. Therefore, there is a problem that the surface quality of the final product is inferior. That is, in this technique, since the crystal grains before cold rolling become too coarse, as described above, a rough surface-like trace is left on the surface of the steel sheet of the final product, large undulations are formed, and the space factor is reduced. Further, since the pre-annealing before the light reduction rolling is indispensable, there is a drawback that the manufacturing process and the manufacturing cost are increased.

In view of such problems of the conventional technology, the present invention has a high magnetic flux density, a low iron loss, and a roughened pattern on the surface of a steel sheet that causes a decrease in the space factor, and suppresses the formation of undulations, that is, An object of the present invention is to provide a non-oriented electrical steel sheet having excellent magnetic properties and surface properties and a method for producing the same.

[Means for solving the problem]

The present inventors have variously studied the relationship between the crystal structure of the material before cold rolling and the magnetic properties and the rough waviness formed after cold rolling, and as a result, of the steel with a reduced content of impurity elements By making the structure before cold rolling into a secondary recrystallized structure and controlling the average grain size of the secondary recrystallized grains and the volume ratio (secondary recrystallized percentage) occupied by the secondary recrystallized grains to within an appropriate range, It has been found that it is possible to improve the magnetic characteristics and suppress the increase of the waviness on the surface of the steel sheet. further,
Optimum cold rolling is achieved by subjecting the hot-rolled steel strip of a specific component to light reduction rolling with a specific reduction ratio, and then performing hot-rolled sheet annealing at a temperature regulated by the (Si + Al) content and the light reduction rolling reduction ratio. It has been clarified that a pre-rolling structure can be obtained and a non-oriented electrical steel sheet having good magnetic properties and surface properties as described above can be produced.

The present invention has been made on the basis of such findings, and is characterized in that, by weight%, C: 0.006% or less, Si: 0.1 to 1.0%, Al: 0.004% or less or 0.1 to 0.5%.
%, Mn: 0.1-1.0%, P: 0.01-0.15%, balance Fe
And unavoidable impurities such as S, N, O as impurities.
Of 0.025% or less, the average crystal grain size of the secondary recrystallized grains is 150 μm or more and less than 500 μm in the crystal structure of the material before cold rolling performed after hot-rolled sheet annealing, and the secondary recrystallized grains are Is a non-oriented electrical steel sheet having a volume ratio of 70% or more and a filtered center line waviness W _{CA of} the steel sheet surface of 1.0 μm or less and excellent magnetic properties and surface properties.

The features of the production method of the present invention are as follows.

(1) C: 0.006% or less, Si: 0.1 to 1.0%, A by weight%
l: 0.004% or less or 0.1 to 0.5%, Mn: 0.1 to 1.0%, P: 0.
After pickling a hot-rolled steel strip containing 01 to 0.15%, the balance Fe and unavoidable impurities, and the total amount of S, N, O as impurities being 0.025% or less, the rolling reduction ε (%) is Light reduction cold rolling in the range of 3 to 12% is performed, and then the following conditions (1) determined by the (Si + Al) content and the light reduction rolling reduction ratio ε,
(2) When 3% ≦ ε ≦ 10% 50 (Si + Al) -10ε + 770 ≦ T ≦ 50 (Si + Al) + 5ε + 810 …… (1) When 10% <ε ≦ 12% 50 (Si + Al) + 670 ≦ T ≦ 50 (Si + Al) + 5ε + 810 ……
(2) However, the cooling is continuously performed by performing hot-rolled sheet annealing for 30 minutes to 12 hours at a temperature T (° C) that satisfies the Si ... Si content (wt%) Al ... Al content (wt%). The average grain size of secondary recrystallized grains in the crystal structure of the material before hot rolling is 150 μm
After less than 500 μm and a volume ratio of secondary recrystallized grains of 70% or more, cold rolling is performed to a predetermined plate thickness and continuous annealing is performed at a temperature equal to or higher than the recrystallization temperature. A method for producing a non-oriented electrical steel sheet having excellent magnetic properties and surface properties, which comprises obtaining a steel sheet having a filtered centerline waviness W _CA of 1.0 μm or less.

(2) A hot-rolled steel strip having the same composition as in (1) above,
In the same steps as in (1), pickling, cold rolling under light pressure, hot-rolled sheet annealing, cold rolling, continuous annealing, shearing or punching, and then strain relief annealing, steel sheet surface A method for producing a non-oriented electrical steel sheet having excellent magnetic properties and surface properties, which comprises obtaining a steel sheet having a filtered centerline waviness W _CA of 1.0 μm or less.

(3) A hot-rolled steel strip having the same composition as in (1) above,
In the same process as (1), pickling, cold rolling under light pressure, hot-rolled sheet annealing, cold rolling, continuous annealing, then 3-15%
A method for producing a non-oriented electrical steel sheet having excellent magnetic properties and surface properties, which is characterized in that a sheet having a filtered center line waviness W _CA of 1.0 μm or less is obtained by performing skin pass rolling with the reduction ratio of 1.

[Action]

Hereinafter, details of the present invention and reasons for limiting the configuration will be described.

 First, the reasons for limiting the steel components will be described.

C is 0.006% or less in order to prevent deterioration of magnetic properties due to magnetic aging and to suppress deterioration of grain growth during annealing.

Si is effective in reducing penetration loss, but if it is less than 0.1%, its effect is not sufficient, and if it exceeds 1.0%, the magnetic flux density decreases, and the high magnetic flux density that is the object of the present invention is obtained. I can't. For the above reasons, Si is 0.1 to 1.0%.

Al, like Si, is an element effective in reducing iron loss, but may form AlN together with N in steel to deteriorate grain growth during annealing and deteriorate magnetic properties. In order to eliminate this adverse effect of AlN, it is necessary to limit the amount of Al to a low level or increase the amount of addition to coarsen AlN. In the former case, the Al content may be 0.004% or less, and in the latter case, the AlN particles can be coarsened if the Al content is 0.1% or more. However, the addition exceeding 0.5% brings about a decrease in magnetic flux density. For the above reasons, Al is set to 0.004% or less or 0.1 to 0.5%.

Mn, like Si and Al, is effective in increasing the specific resistance and reducing iron loss, and at the same time it is necessary to eliminate the adverse effects on magnetic properties and grain growth by converting S in steel to MnS to precipitate and coarsen it. However, if less than 0.1%, the effect cannot be sufficiently obtained, and if it exceeds 1.0%, the α-γ transformation temperature decreases,
Austenite is easily generated during hot-rolled sheet annealing, and solid solution Mn in steel deteriorates grain growth during hot-rolled sheet annealing, making it impossible to obtain an optimum crystal structure before cold rolling. For the above reasons, Mn is 0.1-1.0%.

P is effective for hardness adjustment to reduce iron loss and improve punchability, but if it is less than 0.01%, the effect is not sufficiently obtained, while if it exceeds 0.15%, the steel sheet becomes brittle and the magnetic properties , The grain growth property is deteriorated. Therefore, P is 0.01
~ 0.15%

S, N and O form sulfides, nitrides and oxides, respectively, and inhibit grain growth during annealing. Further, if these precipitates and inclusions are fine and dispersed in a large amount, the magnetic properties themselves are significantly deteriorated, so it is necessary to regulate the total amount of S, N, O to 0.025% or less. Each of these elements alone
S: 0.007% or less, N: 0.003% or less, O: 0.015% are desirable, and it is preferable to reduce them as much as possible.

 Next, the reasons for limiting the configurations other than steel components will be described.

Steel C in Table 1 was hot-rolled according to the usual method, and this steel sheet was pickled and then lightly rolled at a reduction rate of 10%.
Before cold rolling, the hot-rolled sheet is annealed for 2 hours at various temperatures from 675 to 925 ℃, and the volume ratio of secondary recrystallized grains is 100% and the average grain size of secondary recrystallized grains is different. Created the material. Further, for comparison, with respect to the same steel type, a material as hot-rolled without light reduction rolling and hot-rolled sheet annealing was also prepared. Cold rolling these steel plates to a plate thickness of 0.5 mm,
After continuous annealing at a temperature of 800 ° C and a soaking time of 90 seconds, the magnetic properties and the waviness of the steel sheet surface were measured.

Figure 1 shows the results and shows the relationship between the average grain size of the secondary recrystallized grains of the material before cold rolling, the magnetic flux density B ₅₀ and the filtered centerline waviness W _CA of the steel sheet surface. It is a thing. As is clear from the figure, the magnetic flux density increases and the waviness increases as the average grain size of the secondary recrystallized grains increases, but the average grain size is 150 μm or more and less than 500 μm (preferably 40 μm or less).
If it is less than 0 μm), it has been found that it has a high magnetic flux density and can suppress the twisting. Further, it is recognized that the waviness on the surface of the steel sheet tends to be remarkably large when the average particle diameter is 500 μm or more. If the waviness W _CA is 1.0 μm or less, the degree of adverse effect on the space factor of the steel sheet is small. Therefore, in the present invention based on the above results, the waviness W _CA is 1.0 μm.
The average grain size of the secondary recrystallized grains before cold rolling (cold rolling performed after hot-rolled sheet annealing) to finish to a prescribed plate thickness is defined as 150 μm or more and less than 500 μm did.

Next, the influence of the volume ratio of the secondary recrystallized grains in the crystal structure of the material before cold rolling was examined. Steel C in Table 1
Is hot-rolled according to a usual method, and the steel sheet is pickled 1 to
Light reduction rolling with various reduction rates of 12%, and further 750 ℃
The hot-rolled sheet was annealed at a temperature of 2 hours for 2 hours to prepare pre-cold-rolling materials with secondary recrystallized grains having an average grain size of 150 μm or more and less than 500 μm and different volume fractions of the secondary recrystallized grains. . These steel sheets are cold-rolled to a thickness of 0.5 mm at a temperature of 800
The magnetic properties were measured after continuous annealing at ℃ and soaking time of 90 seconds.

Fig. 2 shows the result, which is 2 of the material before cold rolling.
It shows the relationship between the volume ratio of secondary recrystallized grains and the magnetic flux density B ₅₀ . As is clear from the figure, even if the average grain size of the secondary recrystallized grains is controlled within an appropriate range, the effect of improving the magnetic flux density is small if the volume ratio of the secondary recrystallized grains is low. Further, if the volume ratio of the secondary recrystallized grains in the pre-cold rolling structure is low, the magnetic properties vary greatly depending on the position inside the coil of the final product, and the uniformity of the magnetic properties is impaired. Also,
When the average particle size of the secondary recrystallized grains is 500 μm or more, the waviness cannot be sufficiently reduced even if the volume ratio of the secondary recrystallized grains is lowered, and both the magnetic properties and the surface properties are reduced. I couldn't keep it good.

From the above, according to the present invention, a sufficient effect of improving the magnetic flux density can be obtained, and the secondary recrystallization of the material before cold rolling is performed as a condition for maintaining the uniformity of the magnetic properties and keeping the surface quality good. The average particle size of the particles is 150 μm or more and less than 500 μm, 2
The volume ratio of the secondary recrystallized grains was defined as 70% or more.

In addition, the filtered center line waviness W on the steel plate surface of the final product
As mentioned above, the _CA uses 1.0% to prevent the space factor from decreasing.
It was defined as μm or less.

 Next, the manufacturing method of the present invention will be described.

In the present invention, the continuously cast slab having the above-mentioned chemical composition is hot-rolled under the conditions usually used, pickled and then cold-rolled under light pressure. The reduction ratio of this light reduction rolling is 3
If it is less than%, the amount of strain accumulated inside the steel sheet is small, so that the volume ratio occupied by the secondary recrystallized grains that undergo strain-induced grain growth during hot-rolled sheet annealing cannot be made 70% or more. On the other hand, the reduction rate is
If it exceeds 12%, the amount of accumulated strain is too large, so the grain size after hot-rolled sheet annealing becomes small, and it becomes difficult to set the average grain size to 150 μm or more. For the above reasons, the range of the reduction rate of light reduction rolling of hot-rolled sheet is defined as 3 to 12%.

In the subsequent hot-rolled sheet annealing, the optimum crystal structure as described above cannot be obtained unless the annealing temperature is controlled within an appropriate range determined by the light reduction rolling reduction ε (%) and the (Si + Al) content. .

Five kinds of steels having different (Si + Al) contents shown in Table 1 are hot-rolled according to a usual method, pickled, and lightly rolled at a reduction rate of 1 to 13%, and uniformly heated at a temperature of 675 to 925 ° C for 2 hours. The hot rolled sheet was annealed and the crystal structure was investigated. FIG. 3 shows the relationship between the reduction ratio ε (%) of light reduction rolling and the optimum range of hot-rolled sheet annealing temperature (° C.) for steel C in Table 1.
As is clear from the figure, the average grain size of the secondary recrystallized grains is 15
The range of the hot-rolled sheet annealing temperature T (° C.) for obtaining an optimum pre-cold rolling structure in which the volume ratio occupied by the secondary recrystallized grains is 0 μm or more and less than 500 μm and 70% or more is 3 ≦ ε ( %) ≦ 10 −10ε + 800 ≦ T (° C) ≦ 5ε + 840 10 ≦ ε (%) ≦ 12 700 ≦ T (° C) ≦ 5ε + 840. Fig. 4 shows the case of (Si +
It shows the relationship between the Al) content (wt%) and the optimum range of the hot-rolled sheet annealing temperature T (° C), and the hot-rolled sheet annealing temperature T (° C for obtaining the optimum pre-cold rolling structure described above is shown. The range of () is 50 (Si + Al) + 700 ≦ T (° C.) ≦ 50 (Si + Al) +845.

By similar investigations on other steel grades, the hot rolled sheet annealing temperature T (° C) defined by the light reduction rolling reduction ε (%)
It has been revealed that the optimum range of is changed in proportion to the (Si + Al) content (wt%). Therefore, in the present invention, the hot-rolled sheet annealing temperature T (° C.) is a range in which the relationship between the above-mentioned reduction ratio ε and the relationship between (Si + Al) content is combined,
That is, when 3 ≦ ε (%) ≦ 10, 50 (Si + Al) -10ε + 770 ≦ T ≦ 50 (Si + Al) + 5ε + 810 10 <ε (%) ≦ 12, 50 (Si + Al) +670 ≦ T ≦ 50 (Si + Al) + 5ε + 810 However, it is defined as Si ... Si content (wt%) Al ... Al content (wt%).

If the soaking time of hot-rolled sheet annealing is secured for 30 minutes or more, grain growth is almost completed and a sufficient effect of improving the magnetic properties can be obtained. Therefore, the lower limit was defined as 30 minutes. On the other hand, even if annealing is performed for a long time exceeding 12 hours, the effect does not improve significantly, resulting in a decrease in production capacity and an increase in energy consumption, which is economically disadvantageous, so the upper limit is specified as 12 hours. did.

After that, cold rolling is performed to a predetermined plate thickness according to an ordinary method and continuous annealing is performed. However, in the case of a full-process product, continuous annealing needs to be performed at a temperature equal to or higher than the recrystallization temperature in order to reduce iron loss. Also, in the case of semi-processed products that are subjected to stress relief annealing after shearing / punching by the user, grain growth during stress relief annealing can reduce iron loss, so the conditions for continuous annealing after cold rolling are There is no particular limitation.

In the case of semi-processed products that are subjected to final skin pass rolling, this skin pass rolling further reduces the waviness on the surface of the steel sheet, improving the surface texture and, at the same time, facilitating grain growth during stress relief annealing by the user. , Iron loss is further reduced. However, if the reduction rate of this skin pass rolling is less than 3%, its effect is not sufficient, and if it exceeds 15%, the texture changes and the magnetic properties deteriorate, so the reduction rate is in the range of 3 to 15%. Need to be limited to.

〔Example〕

The five types of steel shown in Table 1 were continuously cast into slabs with a thickness of 220 mm, and hot rolled steel strips with a thickness of 2.0 mm were finished by ordinary hot rolling. The steel strip is pickled by a usual method and then the rolling reduction
It was lightly rolled in the range of 15% or less and annealed at various temperatures of 725 to 900 ° C for a soaking time of 2 to 10 hours. Further, this steel strip was cold-rolled to a predetermined plate thickness and continuously annealed in the range of 700 to 850 ° C, and the magnetic properties and the filtered centerline waviness of the steel plate surface were measured. For some steel plates, i) after shearing the Epstein sample and subjecting it to strain relief annealing at 750 ° C x 2 hr, or ii) after final skin pass rolling, shearing and subjecting to strain relief annealing, The magnetic properties were measured. These results are shown in Table 2 together with specific manufacturing conditions.

The plate thickness after cold rolling is 0.5 mm for those without final skin pass rolling, and the finish for cold rolling is for those with skin pass rolling to be 0.5 mm after final skin pass rolling. The thickness was adjusted. For the skin-pass-rolled product, the waviness was measured after the skin-pass rolling.

According to Table 2, the magnetic properties and surface properties are inferior in the comparative example, but the magnetic properties and surface properties are good in the present invention.

[Brief description of drawings]

Fig. 1 is a graph showing the relationship between the average grain size of the material before cold rolling, the magnetic flux density B _{50 of the} final product and the filtered centerline waviness W _CA of the steel plate surface, and Fig. 2 is the graph of the material before cold rolling. Fig. 3 is a graph showing the relationship between the volume ratio of secondary recrystallized grains and the magnetic flux density B ₅₀ of the final product. Fig. 3 is a graph showing the optimum range of the annealing temperature of hot-rolled sheet in relation to the light rolling reduction. FIG. 4 is a graph showing the optimum range of the hot-rolled sheet annealing temperature in relation to the (Si + Al) content.

Claims (4)

[Claims] 1. C: 0.006% or less by weight%, Si: 0.1 to 1.0
%, Al: 0.004% or less or 0.1 to 0.5%, Mn: 0.1 to 1.0
%, P: 0.01 to 0.15%, the balance Fe and unavoidable impurities, the total amount of S, N, O as impurities is 0.025% or less, before cold rolling performed after hot-rolled sheet annealing. In the crystal structure of the material, the average grain size of secondary recrystallized grains is 15
Filter center line waviness W of the steel plate surface, which is 0 μm or more and less than 500 μm, and the volume ratio of secondary recrystallized grains is 70% or more
A non-oriented electrical steel sheet with a _CA of 1.0 μm or less and excellent magnetic properties and surface properties. 2. By weight%, C: 0.006% or less, Si: 0.1 to 1.0
%, Al: 0.004% or less or 0.1 to 0.5%, Mn: 0.1 to 1.0
%, P: 0.01 to 0.15%, the balance Fe and unavoidable impurities, the total amount of S, N, O as impurities is 0.025% or less after pickling, the rolling reduction ε (%) Is 3 ~
Lightly cold rolling in the range of 12% and then (Si + A
l) The following conditions (1) and (2) determined by the content and rolling reduction ε of 3% ≦ ε ≦ 10% 50 (Si + Al) -10ε + 770 ≦ T ≦ 50 (Si + Al) + 5ε + 810 …… (1) When 10% <ε ≦ 12% 50 (Si + Al) + 670 ≦ T ≦ 50 (Si + Al) + 5ε + 810 ……
(2) However, the cooling is continuously performed by annealing the hot-rolled sheet for 30 minutes to 12 hours at a temperature T (° C) that satisfies the Si ... Si content (wt%) Al ... Al content (wt%). The average grain size of secondary recrystallized grains in the crystal structure of the material before hot rolling is 150μ
m or more and less than 500 μm, and after the process of making the volume ratio of the secondary recrystallized grains 70% or more, cold rolling to a predetermined plate thickness and continuous annealing at a temperature equal to or higher than the recrystallization temperature,
A method for producing a non-oriented electrical steel sheet having excellent magnetic properties and surface properties, which comprises obtaining a steel sheet having a filtered centerline waviness W _CA of 1.0 μm or less on the surface of the steel sheet. 3. By weight%, C: 0.006% or less, Si: 0.1 to 1.0
%, Al: 0.004% or less or 0.1 to 0.5%, Mn: 0.1 to 1.0
%, P: 0.01 to 0.15%, the balance Fe and unavoidable impurities, the total amount of S, N, O as impurities is 0.025% or less after pickling, the rolling reduction ε (%) Is 3 ~
Lightly cold rolling in the range of 12% and then (Si + A
l) The following conditions (1) and (2) determined by the content and rolling reduction ε of 3% ≦ ε ≦ 10% 50 (Si + Al) -10ε + 770 ≦ T ≦ 50 (Si + Al) + 5ε + 810 …… (1) When 10% <ε ≦ 12% 50 (Si + Al) + 670 ≦ T ≦ 50 (Si + Al) + 5ε + 810 ……
(2) However, the cooling is continuously performed by annealing the hot-rolled sheet for 30 minutes to 12 hours at a temperature T (° C) that satisfies the Si ... Si content (wt%) Al ... Al content (wt%). The average grain size of secondary recrystallized grains in the crystal structure of the material before hot rolling is 150μ
m and less than 500 μm and the volume ratio of secondary recrystallized grains to 70% or more, followed by cold rolling to a predetermined plate thickness, continuous annealing, and shearing or punching A method for producing a non-oriented electrical steel sheet having excellent magnetic properties and surface properties, which is characterized in that strain-relief annealing is subsequently performed to obtain a steel sheet having a filtered centerline waviness W _CA of 1.0 μm or less on the steel sheet surface. 4. By weight%, C: 0.006% or less, Si: 0.1 to 1.0
%, Al: 0.004% or less or 0.1 to 0.5%, Mn: 0.1 to 1.0
%, P: 0.01 to 0.15%, the balance Fe and unavoidable impurities, and the total reduction of S, N and O as impurities is 0.025% or less. (%) Is 3 ~
Lightly cold rolling in the range of 12% and then (Si + A
l) The following conditions (1) and (2) determined by the content and light rolling reduction ε: 3% ≦ ε ≦ 10% 50 (Si + Al) -10ε + 770 ≦ T ≦ 50 (Si + Al) + 5ε +810 ……
(1) When 10% <ε ≦ 12% 50 (Si + Al) + 670 ≦ T ≦ 50 (Si + Al) + 5ε + 810 ……
(2) However, the cooling is continuously performed by annealing the hot-rolled sheet for 30 minutes to 12 hours at a temperature T (° C) that satisfies the Si ... Si content (wt%) Al ... Al content (wt%). The average grain size of secondary recrystallized grains in the crystal structure of the material before hot rolling is 150μ
m to less than 500 μm and the volume ratio of the secondary recrystallized grains to 70% or more, cold rolling to a predetermined plate thickness, then continuous annealing, then 3% to 15% A method for producing a non-oriented electrical steel sheet having excellent magnetic properties and surface properties, which comprises performing a skin pass rolling with a reduction ratio to obtain a steel sheet having a filtered centerline waviness W _CA of 1.0 μm or less on the steel sheet surface.