JPS6369916A - Production of thin low-iron loss grain oriented electrical steel sheet - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a high magnetic flux density unidirectional electrical steel sheet with excellent core loss properties for use in iron cores of transformers and the like.

[Conventional technology]

Unidirectional electrical steel sheets are mainly used as core materials for transformers and generators, and are characterized by low core loss and high magnetic flux density.
Nowadays, there is a demand for energy saving, and the market is demanding products with even lower iron loss.

In order to achieve low iron loss, two methods are generally used: increasing the Si content as much as possible to increase the specific resistance of the material to reduce eddy current loss, and reducing eddy current loss by reducing the thickness of the product board as much as possible. Are known. However, when increasing the 81 content and reducing the thickness of the product plate, secondary recrystallization during final annealing becomes unstable, making it difficult to stably obtain products with excellent magnetic properties of less than 0.25 mm on an industrial scale. Met. In order to perform secondary recrystallization stably, it is necessary to have a uniformly finely precipitated dispersed phase in the steel before finishing annealing, and to segregate grain boundary elements at the grain boundaries, so that the primary recrystallization It is important to suppress grain growth during recrystallization as much as possible and to preferentially grow secondary recrystallized grains with (110) (001) orientation in the subsequent final annealing. By the way, as the precipitated dispersed phase, MnS, MnS
e, CuxS, AIN, etc. are generally known, and these must be very fine particles with a size of about 100 to 1000 particles and uniformly dispersed. Also, grain boundary segregation elements include Sn, Sb, P.

Te, Mo, Se, etc. are known.

One of the reasons why secondary recrystallization becomes unstable when the product sheet thickness increases to 4 is that when obtaining a thinner product from the same hot-rolled sheet, a larger cold rolling reduction is applied, which causes disadvantages in terms of texture. This is what happens. As a solution to this cause,
One possible method is to reduce the thickness of the hot-rolled sheet according to the product thickness. However, making the hot-rolled sheet thinner inevitably lowers the hot-rolling finish temperature and promotes the precipitation of 8IN, MnS, etc., resulting in excessive precipitation size and deterioration of magnetic properties. has its limits.

As a means to solve the above problems, U.S. Patent Nos. 3 and 6
In No. 32,456, a hot rolled sheet is held at a temperature range of 1000 to 1200°C for 30 seconds to 10 minutes, annealed to precipitate AIN, and then annealed twice or more including intermediate annealing and final hard cold rolling. A method of cold rolling has been proposed.

[Problem that the invention seeks to solve]

The iron loss obtained by the method of U.S. Pat. This provides an industrially extremely stable manufacturing method.

[Means for solving problems]

[C] 0.015-0.090%, (S i) 2.0-
4.0%, [Mn] 0.03-0.12%, CS) 0
．． 020-0.040%, (Sol.

AI) 0.010-0.065%, (N) 0.004
0 to 0.0100%, [Cu] 0.030.5%, (S
n) A silicon steel slab containing 0.03-0.5% balance iron and unavoidable impurities is hot-rolled, hot-rolled plate annealed, preliminary cold-rolled, intermediate annealed, and final hard reduction with a reduction rate of 81%-95%. In the method of producing a high magnetic flux density unidirectional electrical steel sheet by cold rolling to a final thickness of 0.25 m+s or less, decarburization annealing, and final finishing annealing, the hot rolled sheet annealing is performed at a temperature of 1080 to 1
In the cooling after being kept in the soaking temperature range of 200°C for 60 seconds or less, the residence time from the soaking temperature range to the temperature range of 900 to 980°C is 20 seconds or more and less than 500 seconds, and then the temperature is 10°C/10 seconds to room temperature. It is characterized by rapid cooling at a speed of more than seconds, and the size of AIN and other precipitates can be controlled at a higher rate than conventional methods, and the size of AIN and other precipitates can be effectively controlled as an inhibitor. Annealing the hot rolled sheet, preliminary cold rolling, intermediate annealing, and rolling reduction of 81 to 95
Based on the method of producing a high magnetic flux density unidirectional electrical steel sheet through decarburization annealing and final finish annealing, the final thickness is 0.2511I11 or less by final cold rolling with a strong reduction of %, hot rolled sheet annealing, preliminary cooling. For elongation and intermediate annealing, 100 to 1 is effective as an inhibitor of the size of AIN and other precipitates.
0,000 people, obtain an appropriate texture, and have good magnetic properties, for example, a product with a thickness of 0-
Iron loss W at 17n++n. As a result of studying a plate annealing method for manufacturing a product with a power of 0.80 W/kg or less, the
Compared to the method of holding in the temperature range of 0 to 1200'C for 30 seconds to 10 minutes, the soaking temperature range of 1080 to 1200'C is
9 from the soaking temperature range during cooling after being kept for less than 0 seconds
The method of setting the residence time to the temperature range of 00 to 980°C for 20 seconds to 500 seconds, and then rapidly cooling to room temperature at a rate of 10°C/second or more is effective for controlling the size of AIN as an inhibitor for 100 to 1,000 people. It was found that the method is superior in terms of controlling a high percentage of However, even if this method is used, there still exist AINs with a size exceeding 1000 people, and although their number is small, they account for a considerable proportion in terms of precipitation volume fraction. However, when the hot-rolled sheet is kept in the soaking temperature range of 1080 to 1200°C for less than 60 seconds and then cooled, the temperature rises to 900°C from the soaking temperature range.
Residence time up to a temperature range of ~980℃ for 20 seconds or more 500℃
If AIN is precipitated using a method of cooling within seconds and then rapidly cooling down to room temperature at a rate of 10°C/second or more, and then cold-rolled at a reduction rate of 10% or more, this 1000
A new finding is that AIN and other precipitates that are larger than a human can be crushed and refined to a size that is effective as an inhibitor.

The problem here is the intermediate annealing conditions. If intermediate annealing is performed at a high temperature, AIN and other precipitates refined by hot-rolled plate annealing and preliminary cold rolling will undergo Ostwald growth and become coarse. Therefore, the conditions for intermediate annealing must be 800 to 1100°C so that AIN and other precipitates do not become coarse and the rolled structure due to preliminary cold rolling recovers and recrystallizes. We found that it is important in combination with Nobu. In other words, from the viewpoint of recovery and recrystallization of the rolled structure by preliminary cold rolling, a temperature of 800°C or higher is required, but if the temperature exceeds 1100°C, the precipitates that have been made fine will become coarser, and the occurrence rate of 100 to 1000 particles will increase. However, the object of the present invention cannot be achieved.

The idea of the above-mentioned US Pat. No. 3,632,456 is to control the desired size of AIN only by hot-rolled sheet annealing. In contrast, the present invention provides hot rolled plate annealing,
The idea is to control the size of AIN and other precipitates through both pre-cold rolling and intermediate annealing, and by doing so, for the first time, products with good magnetic properties, such as a product with a thickness of 0.17 mm, can be produced.
Iron loss W at n+n.

They discovered a new method for manufacturing products with a power consumption of 0.80 W/kg or less.

Now, FIG. 1 shows an example of the results of an experiment conducted by the present inventor. Within the composition range according to the present invention [Ca2.075%
, [Si] 3.25%, [Mn] 0.080%, C3]
0.025%, (Sol, AI'10.025%, (N
30.0085%, [Cu] 0.07%, C3n) 0.
A hot-rolled plate with a thickness of 2.3 mm containing 12% was heated at 1130°C.
Sample A was held at 900°C for 50 seconds, then cooled to 900°C for 50 seconds, and then rapidly cooled to room temperature at 100″C/second, and this was cold rolled at a rolling reduction of 30%. This is the result of observing the precipitates of sample B and sample C cold-rolled at a rolling reduction of 45% using an electronic IR mirror.The photograph of sample A shows a composite precipitation of acicular AIN on spherical MnS in the center. Samples B and C
The photograph shows that acicular AIN was compositely precipitated in the central spherical MnS, but when 30% and 45% cold rolling was applied, the AIN was crushed and refined by cold rolling. This shows the situation.

Next, in Figure 2, the same hot-rolled plate as in the experiment in Figure 1 was used, and after holding it at 1130'C for 10 seconds,
After being cooled to 00°C and kept at 900°C for 50 seconds, it was rapidly cooled to room temperature at 100°C/second, pre-cold rolled with a reduction of 41%, and intermediate annealed at various temperatures. The product is made into a product by final cold rolling with a strong reduction rate of 0.170 am, decarburization annealing, final finish annealing, and final coating, and the iron loss W + 7 /
S. This figure shows the relationship between and various intermediate annealing conditions.

From this, it can be seen that good magnetic properties can be obtained in the temperature range of 800 to 1100'C. As a result of observing the gold A structure and the precipitated dispersed phase of the intermediate annealed sheet in this experiment, the present inventor found that when the temperature was lower than 800°C, the cold rolled structure remained and the primary recrystallized structure remained. It was found that the precipitates became coarser when the temperature was higher than 1100°C.

[Relationship with conventionally known technology]

■Special Publication No. 40-15644, Japanese Patent Publication No. 12672-1972
In Special Publication No. 40-15644, the thickness of the hot-rolled plate is 1
, 5111111 to 7 mm, and the rolling reduction in the final cold rolling process is 81 to 95%, and the rolling reduction in other cold rolling processes is in the range of 5 to 40%, so-called 2.
A method has been proposed in which cold rolling is performed more than once and annealing is performed one or more times. Furthermore, JP-A No. 59-126722 proposes a method in which a hot-rolled sheet is preliminary cold-rolled at a cold-rolling rate of 15-40%, then annealed and then final cold-rolled at a cold-rolling rate of 80-90%. There is. However, although hot-rolled sheet annealing is not described in these methods, hot-rolled sheet annealing is essential in the present invention, and is described in Japanese Patent Publication No. 40-15644,
It is understood that this technology is different from that of JP-A-59-126722.

■ JP-A-57-198214 JP-A-57-198214 describes a precipitation annealing method immediately before the final cold rolling from 800°C to 1080°C during the heating process.
In the cooling after warming up to the soaking temperature range of °C to 1200°C by 2 to 100℃ and keeping it in this soaking temperature range for less than 60 seconds, the temperature range from the soaking temperature range to 900 to 980℃ A method has been proposed in which the residence time is 20 seconds or more and 500 seconds or less, and then the temperature is rapidly cooled to room temperature at a rate of 10° C./second or more. The idea of this method is that by limiting the precipitation annealing method immediately before the final cold rolling, the precipitates of preferred size, especially A
This is to precipitate IN. And, JP-A-5
Even if the precipitates, especially AIN, are precipitated by the precipitation annealing method described immediately before the final cold rolling as in No. 7-198214, the AIN and other precipitates are refined by the final cold rolling. However, in the present invention, after limiting the annealing method for hot-rolled sheet annealing and controlling the AIN at a higher rate than conventionally for sizes of 100 to 1000 people, cold rolling is performed at a rate of 10%.
The preliminary cold rolling described above and the final cold rolling under heavy reduction were carried out twice, and the size of AIN and other precipitates was
100-10 at a much higher rate than the method of No. 214.
It was successfully controlled by 00 people,
In addition, JP-A No. 57-198214 has a product board thickness of 0.30.
This is a method proposed for mm thick products,
The present invention is understood to be a technology different from that of Japanese Patent Application Laid-Open No. 57-198214.

Each step of the method of the present invention will be specifically described below.

The steel of the present invention can be melted using known steelmaking methods such as converter, electric furnace, and open hearth.
Next scouring can be used together.

Next, to manufacture slabs, a continuous casting method is generally applied in many cases at present, but of course a conventional ingot-blending method can also be applied. The slab thus obtained is subjected to slab heating and hot rolling in a conventional manner. At this time, as shown in Japanese Patent Publication No. 59-37330, the center temperature of the slab as it is continuously cast by the continuous casting method is 1200℃~
It is more preferable to directly heat the slab at a temperature of 1,250 to 1,400 degrees Celsius while the temperature is at 600 degrees Celsius.As for the hot rolling conditions, as shown in JP-A-60-197819, the finishing front temperature is 1150-1250°C1 Finishing surface temperature 950-1050°C and winding temperature 500°C
It is more preferable to adopt a method of controlling the temperature in the range of ~600°C.The thickness of the plate after hot rolling is determined according to the cold rolling rate of the subsequent preliminary cold rolling and final cold rolling with heavy reduction, but it is not too thin. Normally it is 1.5 to 7 because the finishing front temperature is too low.
mm is advantageous. As mentioned above, hot-rolled sheet annealing, pre-cold rolling, and intermediate annealing are particularly important in order to obtain products with low iron loss. In the cooling after being maintained for less than 2 seconds, the residence time from the soaking temperature range to a temperature range of 900 to 980°C is 20 seconds to 500 seconds, and then the temperature is 10 seconds to room temperature.
The method involves rapid cooling at a rate of ℃/second or more, the rolling reduction ratio of preliminary cold rolling is 10 to 50%, and the intermediate annealing is 800%.
The annealing must be carried out at a temperature range of ~1100'C. The cold reduction rate of the subsequent final cold rolling with strong reduction is 81%.
Must be ~95%.

This rolling may be done by a normal method, but
It is more preferable to adopt a method of applying a thermal effect of about 100 to 300° C. for each pass as shown in No. 866. The cold-rolled sheet having the final thickness is subjected to decarburization annealing, and a known method such as annealing in wet hydrogen at 750 to 950° C. for about 2 to 15 minutes can be applied.

After decarburization annealing, final finish annealing is performed to induce secondary recrystallization. This annealing is usually done by applying an annealing layering agent containing magnesia as a main component to the steel plate, and then box-shaped annealing.
A method is used in which the temperature is raised to about 0° C. and maintained at that temperature for 10 to 30 hours, but any other known method may be used. An insulating coating is usually applied to the steel plate that has undergone final annealing, and any known coating can be applied as this coating. Of course, there is no need to apply a coating.

The conditions and reasons for limitations of the present invention will be explained below.

If [C] is less than the lower limit of 0.015%, secondary recrystallization becomes unstable, and the upper limit of 0.090% is from this [C]
This was limited because the larger the number, the longer it would take to prepare coal, which would be economically disadvantageous. If [Si] is less than the lower limit of 2%, good core loss cannot be obtained, and if it exceeds the upper limit of 4%, the cold rollability is significantly deteriorated. [Mn] is an element necessary to form MnS. If it is less than the lower limit of 0.03%, the absolute amount of MnS is insufficient, and if it exceeds the upper limit of 0.12%, the slab needs to be completely dissolved in MTIS. Industrialization becomes difficult because the heating temperature becomes too high. CS) is an element necessary to form AηS and CuxS. If the lower limit is less than 0.010%, the absolute amount of MnS and CuxS will be insufficient, and if the upper limit is 0.040%, the absolute amount of MnS and CuxS will be insufficient.
%, hot cracking occurs and desulfurization becomes difficult in final annealing.

(Sol, AI) is an element necessary to form AIN, and if the lower limit is o, oio%, the absolute amount of AIN is insufficient, and if it exceeds the upper limit, 0.065%, an appropriate dispersion state of AIN is obtained. I can't do it. [N] is an element necessary to form AIN, and if the absolute amount of N is less than the lower limit of 0.0040%040%, it is insufficient, and if it exceeds the upper limit of 0.0100%, a suitable dispersion state of AIN cannot be obtained. , [Cu] is an element that forms CuxS. If the lower limit is less than 0.03%, the absolute amount of CuxS will be insufficient, and if it exceeds the upper limit of 0.5%, the pickling properties and decarburization properties will deteriorate. Preferably it is less than o, oso%.

[Sn] segregates at grain boundaries and stabilizes secondary recrystallization, but if it is less than the lower limit of 0.03%, the amount of segregation is insufficient, and if the upper limit is 0.
．． 5% is due to economic reasons and deterioration of decarbonization.

Hot-rolled plate annealing is carried out in the soaking temperature range of 1080-1200℃.
9 from the soaking temperature range during cooling after being kept for less than 0 seconds
Residence time to temperature range of 00 to 980℃ 20 seconds or more5
If the soaking temperature is less than 1080°C, the effect of this annealing will be weak, whereas if it exceeds 1200°C, the annealing effect will be weak. The residence time of the zero-order primary cooling, which is less than 60 seconds for the same reason that the soaking time is unfavorable from the viewpoint of the metallographic structure as well as the size change of AIN is likely to occur, reduces the amount of AIN precipitated during the cooling process. The longer this time, the more the amount of precipitation increases and the secondary recrystallization becomes more stable. The reason why the upper limit is set to 500 seconds is that no improvement in magnetic properties is observed even if the time is longer than this, and it is also disadvantageous from an industrial standpoint. On the other hand, the reason why the lower limit was set to 20 seconds is that below this, the amount of precipitation is small, so secondary recrystallization becomes unstable and magnetic properties cannot be obtained. , when the temperature is higher than the upper limit of 980°C, coarsening of AIN tends to occur,
This is because if the temperature is below the lower limit of 900°C, the amount of AIN precipitated will decrease. From the temperature range of 900 to 980°C to room temperature, it must be forcibly quenched with water, etc. at a rate of 10°C/second or more; if the cooling rate is less than 10°C/second, an appropriate amount of solid solution (C), CN ) and good magnetic properties cannot be obtained.

If the rolling reduction ratio in preliminary cold rolling is less than 10%, AIN and other precipitates cannot be crushed or refined by cold rolling. When it exceeds 50%, the texture becomes inappropriate and the magnetic flux density decreases significantly. In intermediate annealing, if the temperature is less than 800°C, the cold rolled structure obtained by preliminary cold rolling will not be recovered or recrystallized. When the temperature exceeds 1100°C, it is sufficient for recovery and recrystallization of the cold-rolled structure, but A I N and other precipitates undergo Ostwald growth and become coarse. Note that the holding time also affects recrystallization and the size of AIN and other precipitates;
0 seconds is preferable.

Even if the cold reduction rate of the final cold rolling with strong reduction is less than 81%, it is still 9.
Even if it exceeds 5%, the texture becomes inappropriate, resulting in instability in secondary recrystallization.

In addition, the product board thickness was limited to 0.25mra or less because
This is to obtain a low iron loss unidirectional electrical steel sheet in response to recent demand needs.

In addition, the starting materials include Mo, B, P, Ni, Bi, and Sb.
.

It is also possible to further reduce iron loss by containing one or more types of As.

〔Example〕

[Example 1] [C] 0.079%, [:5i) 3.24%, [Mn)
0.081%, [S) 0.025%, [Sol, ^1]
0.027%, [N] 0.0080%, [Cu] 0.0
7%, (1350 slabs containing 30.12% Sn)
After heating at ℃ for 2.5 hours, hot rolling was performed to form a hot coil with a thickness of 2.01. Hot rolled plate annealing and intermediate annealing were performed under the conditions shown in Table 1, and preliminary cold rolling was performed at a rolling reduction of 33%. 1.35 at
The final cold rolling with strong reduction was performed at a rolling reduction ratio of 87% to give a plate thickness of 0.170 mm+. The resulting cold-rolled sheet was heated with 25% hydrogen and 75% nitrogen, with a dew point of 1
After holding at 840°C for 200 seconds in an atmosphere of 3°C to perform charcoal annealing, and then applying an annealing separator, holding at 1200°C in a hydrogen stream for 20 hours to perform final annealing, and then applying a coating liquid. It was made into a product. Hot rolled sheet annealing, intermediate annealing conditions and magnetic properties of the obtained product (magnetic flux density 810
, Iron loss W, . ) are shown in Table 1. From this, it can be seen that the inventive example has better magnetic properties than the comparative example.

Below margin [Example 2] (C) 0.081%, (S i) 3.30%, CMn:
10.075%, [S] 0.025%, (Sol, Δl
) 0.026%, [:N) 0.0081%, [Cu] 0
．． 13 slabs containing 0.07% and 0.13% [Sn].
After heating at 50° C. for 3 hours, hot rolling was performed to obtain hot coils of various thicknesses. Subsequently, hot rolled sheet annealing was performed by holding the temperature at 1130°C for 10 seconds, then cooling it to 900°C for 50 seconds,
After holding at 900°C for 50 seconds, rapidly cool to room temperature at 100°C/second. During preliminary cold rolling, the rolling reduction ratio was changed according to the thickness of the hot coil, and the thickness of all sheets after preliminary cold rolling was 1°55III.
It was set as Il. Subsequently, intermediate annealing was performed by holding the temperature at 950°C for 100 seconds and then rapidly cooling it to room temperature at a rate of 100°C/second, and final cold rolling with heavy reduction was performed at a reduction rate of 86% to reduce the plate thickness to 0.220°C.
mm. Thereafter, the obtained cold-rolled sheet was decarburized by holding it at 840°C for 180 seconds in an atmosphere of 25% hydrogen, 75% nitrogen, and a dew point of 43°C, and then, after applying an annealing separator, it was placed in a hydrogen stream. Final annealing was performed by holding at 1200° C. for 20 hours, and a coating liquid was applied to produce a product. The plate thickness of the hot coil, the rolling reduction of the preliminary cold rolling, and the magnetic properties of the obtained product (magnetic flux density B1°, iron loss W,...) are shown in Table 2. From this, the rolling reduction ratio of preliminary cold rolling is 10 to 50.
%, it can be seen that the material of the present invention has better magnetic properties than the comparative material.

The following margins [Effects of the invention] As detailed above, hot rolled sheet annealing, preliminary cold rolling, intermediate annealing, and final cold rolling with strong reduction at a reduction rate of 81 to 95% result in zero
．． In the method of manufacturing a high magnetic flux density unidirectional electromagnetic shoulder plate with a final plate thickness of 25 mm or less by decarburization annealing and final finish annealing, specify specific conditions for hot-rolled plate annealing, preliminary cold rolling, and intermediate annealing. As a result, it is possible to obtain a product with extremely low iron loss, and its industrial effects are extremely large.

[Brief explanation of the drawing]

Figure 1 shows that after holding the hot rolled sheet at 1130°C for 10 seconds,
Sample A, which was cooled to 900°C for 50 seconds, kept at 900°C for 50 seconds, and then rapidly cooled to room temperature at 100°C/second;
Samples B and 4 were cold-rolled at a rolling reduction of 30%.
These are the results of observing the precipitates of sample C cold-rolled at a rolling reduction of 5% using an electron M microscope. FIG. 2 is a diagram showing the relationship between intermediate annealing temperature and magnetic properties. , '1, -89 Figure 1 0.2pm 211 Procedural amendment (spontaneous) October 2, 1985 Commissioner of the Japan Patent Office Black 1) Ming A 1, Indication of the case 1985 Patent Application No. 210733 2 , Name of the invention: Method for manufacturing thin, low iron loss unidirectional electrical steel sheet 3, Person making the amendment 4: Agent address: 8-10 Toranomon-chome, Minato-ku, Tokyo 105 (5 others) 5. Subject of the amendment Drawing (Figure 2) 6. Contents of amendment The drawing (Figure 2) will be amended as shown in the attached sheet. 7. Inventory drawing of attached documents (Figure 2) 1 copy 2nd procedural amendment (method) January/Date 1985 Commissioner of the Patent Office Black 1) Akio Yu 1. Indication of the case 1985 patent Application No. 210733 2, Name of the invention Method for manufacturing thin, low core loss unidirectional electrical steel sheet 3, Relationship with the case of the person making the amendment Name of patent applicant (665) Nippon Steel Corporation 4, Agent address 〒 105 Toranomon-chome 8-10-5, Minato-ku, Tokyo
Date of amendment order: November 25, 1985 (Delivery port) 6. Column 7 of "Brief explanation of drawings" of the specification subject to amendment, "Results" of page 24, line 16 of the statement of contents of amendment. Later, I will add ``Photographs of metallurgical microstructure showing .''

Claims (1)

[Claims] (1) [C] 0.015-0.090%, [Si] 2.
0-4.0%, [Mn] 0.03-0.12%, [S]
0.010-0.040%, [sol. Al〕0.01
0-0.065%, [N] 0.0040-0.0100
%, [Cu] 0.03~0.5%, [Sn] 0.03~
A silicon steel slab containing 0.5% balance iron and unavoidable impurities is hot rolled, hot rolled sheet annealed, preliminary cold rolled, intermediate annealed and
0.0 by final cold rolling with a reduction rate of 81% to 95%.
In the method of manufacturing high magnetic flux density unidirectional electrical steel sheets with a final plate thickness of 25 mm or less, decarburization annealing, and final finish annealing, the hot rolled plate annealing is kept in the soaking temperature range of 1080 to 1200 ° C for less than 60 seconds. In cooling after cooling, the residence time from the soaking temperature range to the temperature range of 900 to 980°C is 20
The rolling process is performed for at least 500 seconds, and then rapidly cooled to room temperature at a rate of at least 10°C/sec.
A method for producing a thin, low core loss, unidirectional electrical steel sheet, characterized in that annealing is performed in a temperature range of 1100°C.