JP2762095B2 - Method of manufacturing thin high magnetic flux density unidirectional electrical steel sheet with excellent product magnetic properties by single-stage cold rolling method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a thin, high magnetic flux density, unidirectional electromagnetic steel sheet excellent in product magnetic properties by a single-stage cold rolling method.

[Conventional technology]

The unidirectional electromagnetic steel plate is mainly used as a soft magnetic material as a magnetic core material of transformers and other electric devices, and must have good magnetic characteristics such as excitation characteristics and iron loss characteristics.

In order to obtain a steel sheet having excellent magnetic properties, it is necessary that the <001> axis, which is the axis of easy magnetization, be highly aligned in the rolling direction. In addition, the thickness, crystal grain size, specific resistance, surface coating, and the like greatly affect the magnetic properties.

The directionality of electromagnetic steel sheets has been greatly improved by the high-pressure single-stage cold-rolling process that makes AlN and MnS function as inhibitors, and the magnetic flux density is now being manufactured to about 96% of the theoretical value. I have.

On the other hand, in recent years, reflecting the soaring energy prices, transformer manufacturers
The focus on low iron loss magnetic materials has been further strengthened.

As low iron loss magnetic materials, amorphous alloys and 6.5% Si
The development of high Si materials such as alloys is also underway, but there are drawbacks in transformer materials such as price and workability.

On the other hand, it is known that the iron thickness of the electromagnetic steel sheet is greatly affected by the sheet thickness in addition to the Si content, and the iron loss is reduced when the sheet thickness of the product is reduced by chemical polishing or the like.

The present inventors have previously described in JP-A-58-217630,
A method for producing thin high magnetic flux density unidirectional electrical steel sheets by using a silicon steel slab containing acid-soluble Al, N, and Sn as a starting material by a one-stage cold rolling method under high pressure accompanied by hot-rolled sheet annealing was proposed.
With this method, thin high magnetic flux density unidirectional magnetic steel sheets with excellent iron loss, especially thin materials up to 0.225 mm in thickness, can be industrially manufactured at low cost. We were able to contribute to energy conservation, a challenge of the times.

However, the demands of the era for energy saving have been further strengthened since then, and it has become necessary to further improve the performance of the unidirectional electromagnetic steel plate, which is a material for transformers. In other words, it has become an urgent task to establish a low-cost and stable manufacturing method of a thin high-flux-density unidirectional electrical steel sheet having a sheet thickness of 0.175 mm or less, which has a lower iron loss than a sheet thickness of 0.225 mm.

[Problems to be solved by the invention]

According to the method described in JP-A-58-217630, 0.175 mm, 0.
Although it is possible to produce 150 mm material, if the plate thickness is 0.175 mm or less, as shown in Tables 8 and 11 of the above publication, secondary recrystallization is not complete, and in the case of industrial production, the process yield , And there was a problem in terms of the level and stability of the product magnetic properties.

The present invention uses a silicon steel slab containing acid-soluble Al, N, Sn as a starting material, and a product magnetic property cold-rolled to a sheet thickness of 0.12 to 0.17 mm by a one-stage cold rolling method under high pressure accompanied by hot-rolled sheet annealing. It is an object of the present invention to provide a method for stably producing a thin high magnetic flux density unidirectional electromagnetic steel sheet excellent in the above.

[Means for solving the problem]

The gist of the present invention is that a silicon steel slab containing acid-soluble Al, N, Sn is used as a starting material, and is cold-rolled to a sheet thickness of 0.12 to 0.17 mm by a one-stage cold rolling method under high pressure accompanied by hot-rolled sheet annealing. In the method for producing a thin unidirectional electromagnetic steel sheet, the slab containing N and acid-soluble Al, N: 0.0050 to 0.01
00%, acid soluble Al: {(27/14) × N (%) + 0.0035} ～
27 (27/14) × N (%) + 0.0100｝%, and the thickness of the hot-rolled sheet with a cold rolling reduction of 85 to 92%, and contains NasAlN in the hot-rolled sheet By performing hot rolling to control the amount to 0.0005 to 0.0020% and controlling the hydrated water percentage of magnesia in the annealing separator to 0.5 to 3.0%, the secondary recrystallization is complete and the product magnetic properties An object of the present invention is to enable stable production of an excellent thin high magnetic flux density unidirectional electromagnetic steel plate.

[Action]

Hereinafter, the circumstances that led to the present invention will be described based on experimental results.

(Experiment I) C: 0.080%, Si: 3.25%, Mn: 0.075%, S: 0.025%, Sn: 0.1
3%, N: 0.0040-0.0120%, acid-soluble Al: 0.0100-0.0500
%, Balance: Many slabs consisting essentially of Fe at 1370 ° C
It was heated for 60 minutes, extracted from the heating furnace, and hot rolled to a thickness of 1.4 mm. The hot rolling end temperature was 1,040 to 1,050 ° C. After the completion of hot rolling, the sample was cooled to 550 ° C. at a rate of about 70 ° C./sec, and then allowed to cool in the air. The N as AlN contained in the hot rolled sheet was 0.0010 to 0.0012%. Anneal the hot rolled sheet at 1100 ° C for 30 seconds, then 100 ° C
In water for cooling.

The annealed plate was pickled and cold rolled to a plate thickness of 0.15 mm. Then, in an atmosphere of 75% H ₂ , 25% N ₂ and a dew point of 65 ° C., at 850 ° C. for 150 hours.
A decarburization annealing for 2 seconds was performed. Next, annealed separating agent mainly composed of magnesia is mixed with water, stirred to form a slurry, the hydrated water content of magnesia in the slurry is set to 1.5%, the slurry is applied to a steel plate, and dried at a plate temperature of 200 ° C. did.
(Note that the hydration moisture content is measured by the following equation from the weight of powder after removing free water (m ₁ ) and the weight of powder after further heating at 1000 ° C. for 1 hour (m ₂ ). Was.

The hydrated water percentage according to the present invention is all measured by this method. ) Then, in _{85% H 2, 15% N} 2 atmosphere and heated to 1200 ° C. at a heating rate of 25 ° C. / time, then with H ₂ atmosphere, 1200
After soaking at 20 ° C. for 20 hours, the mixture was cooled, the annealing separating agent was removed, and the product was obtained by performing tension coating. Product magnetic flux density
B ₈ and iron loss W _15/50 were measured. Next, the coating and the glass coating were removed, and the macrostructure was observed. The relationship between the content of N and acid-soluble Al in the slab and the state of secondary recrystallization, B ₈ and W _15/50 is shown in FIGS. 1, 2 and 3, respectively.

In FIG. 1, the horizontal axis is the N content, and the vertical axis is the acid-soluble Al content. The secondary recrystallization status is indicated by the symbols ○, △, ×. In the region surrounded by the straight lines ab, bc, cd, and da in the figure, the secondary recrystallization was complete. The straight line ab is represented by the following equation.

Linear ab: acid-soluble Al (%) = (27/14) × N (%) + 0.0100 (%) That is, N: 0.0050 to 0.0120%, and acid-soluble Al: 0.010
When 0 to {(27/14) × N (%) + 0.0100}%, the secondary recrystallization was found to be complete.

In FIG. 2, the horizontal axis represents the N content, and the vertical axis represents the acid-soluble Al content. The values of B ₈ ○, △, indicating the sign of ×. In the figure, the straight line ab, bc, cd, the area defined by da, good B ₈ were obtained.

 The straight lines ab and cd are respectively represented by the following equations.

Linear ab: Acid-soluble Al (%) = (27/14) × N (%) + 0.0100 (%) Linear cd: Acid-soluble Al (%) = (27/14) × N (%) + 0.0035 ( %) That is, N: 0.0050 to 0.0100%, and acid-soluble Al: ｛(2
7/14) × N (%) + 0.0035｝ ～ ｛(27/14) × N (%)
When the Tasu0.0100}%, good B ₈ was found to be obtained.

In FIG. 3, the horizontal axis represents the N content, and the vertical axis represents the acid-soluble Al content. The value of W _15/50 is indicated by the symbols ○, Δ, ×. In the region surrounded by the straight lines ab, bc, cd, and da in the figure, good _{W15 / 50} was obtained.

 The straight lines ab and cd are respectively represented by the following equations.

Linear ab: Acid-soluble Al (%) = (27/14) × N (%) + 0.0100 (%) Linear cd: Acid-soluble Al (%) = (27/14) × N (%) + 0.0035 ( %) That is, N: 0.0050 to 0.0100%, and acid-soluble Al: ｛(2
7/14) × N (%) + 0.0035｝ ～ ｛(27/14) × N (%)
It was found that good W _15/50 was obtained at + 0.0100%.

From the results of FIGS. 1, 2 and 3, N: 0.0050 to 0.01
At 00%, acid soluble Al: {(27/14) × N (%) + 0.0035}
When 明 ら か に (27/14) × N (%) + 0.0100%, the secondary recrystallization was complete, and it was found that both B ₈ and W _15/50 gave good products.

Although the secondary recrystallization is complete, B ₈ is low in the region where W _15/50 is defective. That is, low Al, high N
On the side, secondary recrystallization is stable, but the directionality is poor and a good iron loss value is hardly obtained.

Here, (27/14) × N (%) corresponds to the Al content required when all the N contained in the steel becomes AlN. In this method, which utilizes AlN as the main inhibitor, the secondary recrystallization phenomenon that affects the magnetic flux density and iron loss value of the product is (27/14)
It is understood that it is strongly influenced by the acid-soluble Al content based on × N (%).

(Experiment II) C: 0.082%, Si: 3.25%, Mn: 0.070%, S: 0.025%, Sn: 0.14
%, N: 0.0085%, acid soluble Al: 0.0240%, balance: substantially
Many silicon steel slabs made of Fe were heated at 1370 ° C. for 60 minutes, extracted from a heating furnace, and hot rolled to various sheet thicknesses of 0.75 to 3.0 mm. In this case, before the rolling, during the rolling and after the rolling, various cooling conditions were changed, and the amount of N as AlN of the hot-rolled sheet was 0.0001 to 0.0036.
%. Here, AlN is the analytical value of the total thickness of the plate,
The analysis method used the bromine methanol method (related to the present invention).
All analysis of AlN is by bromine methanol method). These hot rolled sheets were treated in the same manner as in Experiment I to obtain products.

Next, the magnetic flux density B ₈ and the iron loss W _15/50 of the product were measured.
Next, the coating and the glass coating were removed, and the macrostructure was observed. The relationship between the N as AlN of the hot rolled sheet, the reduction ratio of the cold rolling and the secondary recrystallization condition, B ₈ and W _15/50 are shown in FIGS. 4 and 5, respectively.
FIG. 6 and FIG.

In FIG. 4, the horizontal axis represents the Na as AlN content, and the vertical axis represents the cold rolling reduction. The status of secondary recrystallization is indicated by the symbols ○, △, ×. In the region surrounded by the straight lines ab, bc, cd, and da in the figure, the secondary recrystallization was complete. That is, N as A
lN: 0.0001 to 0.0020%, cold rolling reduction: 80 to 92%
The secondary recrystallization proved to be complete.

In FIG. 5, the horizontal axis represents the Na as AlN content, and the vertical axis represents the cold rolling reduction. The values of B ₈ ○, △, indicating the sign of ×. Good B in the area surrounded by ab, bc, cd, and da in FIG.
₈ was obtained. That is, N as AlN: 0.0005 to 0.0020%,
Cold rolling reduction ratio: good B ₈ at 85% -92% that is obtained revealed.

In FIG. 6, the horizontal axis represents the Na as AlN content, and the vertical axis represents the cold rolling reduction. The value of W _15/50 is indicated by the symbols ○, Δ, ×. In the figure, in a region surrounded by ab, bc, cd, and da, good W _15/50 was obtained, that is, N as AlN: 0.00
Good W when 05-0.0020%, cold rolling reduction 85-92%
It became clear that _15/50 could be obtained.

From the results of FIGS. 4, 5 and 6, N as AlN: 0.0005
～0.0020%, secondary recrystallization when the cold rolling reduction ratio 85% -92% is perfect, B _8, W _15/50 both good product was found to be obtained.

Although the secondary recrystallization is complete, B ₈ is low in the region where W _15/50 is defective.

From the results of Experiments I and II, silicon steel slabs containing acid-soluble Al, N, and Sn were used as starting materials, and were cold rolled to a sheet thickness of 0.12 to 0.17 mm by one-stage cold rolling under high pressure with hot-rolled sheet annealing. In the method of manufacturing a thin unidirectional magnetic steel sheet, the slab containing N and acid-soluble Al, N: 0.0050 to 0.0100
%, Acid soluble Al: {(27/14) × N (%) + 0.0035} ～
27 (27/14) × N (%) + 0.0100｝%, and the thickness of the hot-rolled sheet with a cold rolling reduction of 85 to 92%, and contains NasAlN in the hot-rolled sheet By conducting hot rolling to control the amount to 0.0005% to 0.0020%, it becomes clear that stable production of thin high magnetic flux density unidirectional electrical steel sheets with perfect secondary recrystallization and excellent product magnetic properties is possible. Was.

It is not always clear why secondary recrystallization is good and a product with excellent magnetic properties can be obtained by performing hot rolling in which the N as AlN content in the hot rolled sheet is controlled to 0.0005 to 0.0020%. Absent.

When manufacturing a thin high magnetic flux density unidirectional magnetic steel sheet with a cold-rolled sheet thickness of 0.17 mm or less by the single-stage cold rolling method, compared to the case of manufacturing a thick product or multi-stage cold rolling method, the hot-rolled sheet It is conceivable that the structure and the state of precipitates after annealing have a stronger influence on the product properties.

On the other hand, the N as AlN content in the hot-rolled sheet is considered to have a slight effect on the structural change of the steel sheet and the behavior of precipitates during hot-rolled sheet annealing, and the N as AlN content in the hot-rolled sheet is 0.00
In the case of 05 to 0.0020%, the properties of the steel sheet after hot-rolled sheet annealing, which is the most advantageous for the product properties, will be obtained.

The content of NasAlN in the hot-rolled sheet was 0.0005-0.0020%
There are slab heating conditions, rough rolling conditions, finish rolling conditions, cooling conditions after finish rolling, etc.
Any of them may be used.

(Experiment III) C: 0.075%, Si: 3.25%, Mn: 0.070%, S: 0.026%, acid-soluble Al: 0.0255%, N: 0.0085%, Sn: 0.15%, balance: substantially
A silicon steel slab made of Fe was treated in the same manner as in Experiment I except for the condition of the annealing separator to obtain a product.

Regarding the annealing separator, the type of magnesia and stirring conditions with water were variously changed, and the hydrated water content of magnesia in the slurry was 0.1 to 6.0%.

 The iron loss value and magnetic flux density of the product were measured.

FIG. 7 shows the relationship between the hydrated water percentage, the iron loss value and the magnetic flux density. In FIG. 7, the horizontal axis represents the hydrated water content of magnesia in the slurry, and the vertical axis represents the iron loss value and the magnetic flux density.

As is clear from FIG. 7, good iron loss values and magnetic flux densities were obtained in the range of the hydrated water content of 0.5 to 3.0%.

The glass coatings of the samples in this experiment were all good.

Experiments I and II were conducted when either or both of Cu and Sb were added to the material components shown in Experiments I, II and III.
Experiments similar to II and Experiment III were performed and similar results were obtained.

(Experiment IV) C: 0.083%, Si: 3.25%, Mn: 0.076%, S: 0.025%, Sn: 0.14
%, N: 0.0085%, acid-soluble Al: 0.0235%, Cu: no additive and
0.01 to 0.20%, balance: Many silicon steel slabs substantially made of Fe were subjected to hot rolling and subsequent steps in the same manner as in Experiment I to obtain products. FIG. 8 shows the relationship between the Cu content and the iron loss value. As is clear from FIG. 8, improvement in iron loss characteristics was observed in the range of Cu: 0.03 to 0.08%.

(Experiment V) C: 0.080%, Si: 3.23%, Mn: 0.075%, S: 0.025%, Sn: 0.13
%, N: 0.0085%, acid-soluble Al: 0.0230%, Sb: no additive and
0.001 to 0.050%, balance: For many silicon steel slabs substantially composed of Fe, the processes after hot rolling were processed in the same manner as in Experiment I to obtain products. FIG. 9 shows the relationship between the Sb content and iron loss. As is evident from FIG. 9, improvement in iron loss characteristics was observed in the range of Sb: 0.005 to 0.035%.

Next, the reasons for limiting the components of the silicon steel slab and the processing conditions in the manufacturing process in the present invention will be described.

C is 0.060 to 0.120%. Less than 0.060%, or
If it exceeds 0.120%, secondary recrystallization becomes unstable.

Si is 2.9-4.5%. If it is less than 2.9%, a good (low) iron loss value cannot be obtained, and if it exceeds 4.5%, workability (easiness of cold rolling) deteriorates.

Mn is set to 0.050 to 0.090%. Less than 0.050%, or
If it exceeds 0.090%, secondary recrystallization becomes unstable.

One or both of S and Se is set to 0.020 to 0.060%. If less than 0.020%, secondary recrystallization becomes unstable, and 0.060%
%, The iron loss value becomes poor.

In addition, when S and Se are added in combination, particularly excellent product magnetic properties can be obtained.

Sn is 0.05 to 0.25%. If it is less than 0.05%, the secondary recrystallization becomes unstable, and if it exceeds 0.25%, the workability deteriorates.

In slab heating, high-temperature heating is necessary to sufficiently dissolve sulfides and nitrides, and heating at 1300 ° C. or more is desirable.

The reason for annealing the hot rolled sheet at 1030 to 1200 ° C within 10 minutes is as follows.
Good product magnetic properties cannot be obtained below 1030 ° C, 1200 ° C
If more than 2, secondary recrystallization becomes unstable, and even if annealing is performed for more than 10 minutes, improvement in product magnetic properties cannot be expected, which is economically disadvantageous.

Rapid cooling after annealing. Good product magnetic properties cannot be obtained unless quenched.

The one-stage cold rolling method is preferable because the production cost is significantly lower than the two-stage cold rolling method.

The sheet thickness after cold rolling is 0.12 to 0.17 mm. If it is less than 0.12 mm, the secondary recrystallization tends to be unstable, and if it exceeds 0.17 mm, the expected iron loss value cannot be obtained.

In addition, holding at 200 to 300 ° C. for 1 to 5 minutes during the cold rolling is effective for improving the product magnetic properties.

During high temperature finish annealing, at least 1000 ° C during heating
Until then, an atmosphere containing nitrogen is used. If it does not contain nitrogen,
Secondary recrystallization becomes unstable.

〔Example〕

Example 1 C: 0.080%, Si: 3.25%, Mn: 0.076%, S: no additive, 0.015%,
0.025%, Se: not added, 0.015%, 0.025%, Sn: 0.13%, N: 0.00
45%, 0.0085%, 0.0110%, acid-soluble Al: 0.0150%, 0.0170
%, 0.0230%, 0.0260%, 0.0300%, Cu: No additive, 0.07%, S
b: No addition, 0.020%, balance: Many silicon steel slabs substantially consisting of Fe were heated at 1360 ° C for 60 minutes, extracted from the heating furnace, and each plate of 0.92mm, 1.00mm, 1.31mm, 2.43mm It was hot rolled thick. In this case, the cooling conditions before, during, and after the rolling were variously changed. The N as AlN content of the hot rolled sheet is 0.0002 to 0.00
35%.

Anneal the hot rolled sheet at 1120 ° C for 60 seconds, then air cool and 100 ° C
Was cooled by immersion in water. Pickling the plate after annealing
Cold rolled to 0.12mm and 0.17mm. Next, decarburization annealing was performed at 850 ° C. for 150 seconds in an atmosphere of 75% H ₂ , 25% N ₂ and a dew point of 65 ° C. Next, an annealing separator containing magnesia as a main component was applied with the hydrated water content of magnesia being 1.5%, and 85% H ₂ , 15
% N ₂ atmosphere, heated to 1200 ° C. at a temperature rise rate of 25 ° C./hour, then, in H ₂ atmosphere, soaked at 1200 ° C. for 20 hours, then cooled, the annealing separating agent was removed, and tension coating was performed. To obtain the product. The magnetic flux density B ₈ and iron loss W _15/50 of the product were measured. Next, the coating and the glass coating were removed, and the macrostructure was observed. Table 1 shows the results. First
As is clear from the table, N of the slab, acid-soluble Al content,
Only when the N as AlN content and the cold rolling reduction of the hot-rolled sheet were the conditions of the present invention, a product in which secondary recrystallization was perfect and B ₈ and W _15/50 were excellent was obtained.

Further, when the contents of Cu and Sb were in the range of the present invention, more excellent product magnetic properties were obtained.

Example 2 Silicon steel slabs of the four components A, B, C and D shown in Table 2 were treated in the same manner as in Example 1 except for the hydrated water content of magnesia to obtain a product. Hydration of magnesia is 0.2%, 1.
8% and 5.0%.

It was measured product iron loss value (W _15/50) and flux density (B _8). Table 3 shows the results. As is evident from Table 3, excellent (low) iron loss values and excellent (high) magnetic flux density are exhibited only when the hydrated water content of magnesia is in the range of the present invention.

[Effect of the Invention] Since the present invention is configured as described above, it is acid-soluble.
Using a silicon steel slab containing Al, N and Sn as a starting material, a sheet thickness of 0.12 to 0.17
In the method of manufacturing thin unidirectional electrical steel sheets cold rolled to a thickness of 0.2 mm, secondary recrystallization is complete and thin high magnetic flux density unidirectional electrical steel sheets with excellent product magnetic properties can be manufactured stably. Was.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the N content (horizontal axis) and the acid-soluble Al content (vertical axis) of a slab and the state of secondary recrystallization (indicated by ，, ×, etc.). FIG. 2 is a diagram showing the relationship between the N content (horizontal axis) and the acid-soluble Al content (vertical axis) of the slab and the magnetic flux density B ₈ (indicated by ，, ×, etc.) of the product. Fig. 3 shows the N content (horizontal axis) and the acid-soluble Al content (vertical axis) of the slab and the iron loss W _{15/50 of the} product (indicated by ○, ×, etc.).
FIG. FIG. 4 is a diagram showing the relationship between the N as AlN content (horizontal axis) and the cold rolling reduction (vertical axis) of the hot rolled sheet and the state of secondary recrystallization (indicated by ○, ×, etc.). FIG. 5 is a diagram showing the relationship between the N as AlN content (horizontal axis) and the cold rolling reduction (vertical axis) of the hot-rolled sheet and the magnetic flux density B ₈ (indicated by ，, ×, etc.) of the product. FIG. 6 is a diagram showing the relationship between N as AlN (horizontal axis) and cold rolling reduction (vertical axis) of a hot-rolled sheet and iron loss W _15/50 (indicated by ○, ×, etc.) of a product. FIG. 7 is a graph showing the relationship between the hydrated water content of magnesia in the annealing separator (horizontal axis), the iron loss value of the product, and the magnetic flux density (vertical axis). FIG. 8 is a diagram showing the relationship between the Cu content of the slab (horizontal axis) and the amount of change in iron loss W _15/50 of the product due to the addition of Cu (vertical axis). FIG. 9 is a diagram showing the relationship between the Sb content of the slab (horizontal axis) and the amount of change in the iron loss W _15/50 of the product due to the addition of Sb (vertical axis).

Claims (2)

(57) [Claims] (1) C: 0.060 to 0.120%, Si: 2.9 to 4.5% by weight
%, Mn: 0.050 to 0.090%, either or both of S and Se:
A silicon steel slab containing 0.020-0.060%, Sn: 0.05-0.25% and acid-soluble Al, N, the balance being Fe and unavoidable impurities is heated at a high temperature, hot-rolled, and the hot-rolled sheet is heated to 1030-1200 ° C. Annealed within a temperature range within 10 minutes, quenched after annealing, then cold rolled, the thickness after cold rolling was set to 0.12 to 0.17 mm, decarburized annealing in a humid atmosphere containing hydrogen, mainly magnesia At least 1000 ° C during the temperature rise
Until then, a high-temperature finish annealing using an atmosphere containing nitrogen, and a method of manufacturing a thin unidirectional electrical steel sheet to be subjected to tension coating, wherein the silicon steel slab contains N and acid-soluble Al
About, N: 0.0050-0.0100%, acid-soluble Al: ｛(27/1
4) × N (%) + 0.0035｝ ～ ｛(27/14) × N (%) + 0.
0100% and the thickness of the hot-rolled sheet having a cold rolling reduction of 85 to 92%, and the content of NasAlN in the hot-rolled sheet is 0.00
Thin and excellent product magnetic properties by single-stage cold-rolling, characterized in that hot rolling is controlled to 05-0.0020% and hydrated moisture of magnesia in the annealing separator is controlled to 0.5-3.0%. A method for producing a high magnetic flux density unidirectional electromagnetic steel plate. 2. C: 0.060 to 0.120% by weight, Si: 2.9 to 4.5% by weight
%, Mn: 0.050 to 0.090%, either or both of S and Se:
0.020 to 0.060%, Sn: 0.05 to 0.25%, Cu: 0.03 to 0.08% or
Sb: One or both of 0.005 to 0.035% and an acid-soluble Al, N, and a silicon steel slab comprising the balance Fe and unavoidable impurities is heated at a high temperature, hot-rolled, and the hot-rolled sheet is heated to 1030 to
Annealed within a temperature range of 1200 ° C within 10 minutes, quenched after annealing,
Next, cold rolling, the thickness after cold rolling to 0.12 to 0.17 mm, decarburizing annealing in a humid atmosphere containing hydrogen, applying an annealing separator mainly composed of magnesia, at least during the temperature rise
Up to 1000 ° C., perform high-temperature finish annealing using an atmosphere containing nitrogen, and in a method for producing a thin unidirectional electromagnetic steel sheet for performing tension coating, the N and acid-soluble Al contained in the silicon steel slab, N: 0.0050 to 0.0100%, acid soluble Al:
｛(27/14) × N (%) + 0.0035｝ ～ ｛(27/14) × N
(%) + 0.0100%, and cold rolling reduction is 85-92%
The hot-rolled sheet has a thickness, and the hot-rolled sheet is subjected to hot-rolling to control the N as AlN content to 0.0005 to 0.0020%, and
A method for producing a thin high magnetic flux density unidirectional electromagnetic steel sheet having excellent magnetic properties of a product by a one-stage cold rolling method, wherein a hydrated water content of magnesia in an annealing separator is controlled to 0.5 to 3.0%.