JPH0686628B2 - Manufacturing method of low-loss directional silicon steel ultra-thin ribbon - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a so-called directional silicon steel strip having an easy axis of magnetization [001] in the rolling direction of the steel strip.
In particular, the present invention relates to a method for producing an ultrathin steel strip having a high magnetic flux density and a very low iron loss and high orientation (high orientation) oriented silicon steel strip.

[Conventional technology]

For silicon steel strips with a silicon content of 4% by weight or less, a directional silicon steel strip having a Goss orientation, that is, a (110) [001] -oriented crystal grain texture, is currently produced by a combination of rolling and heat treatment. Widely used in power transformers, generators, saturable reactors, etc.

This directional silicon steel strip has a plate surface parallel to the (110) crystal plane and a rolling direction of [001],
Since the rolling direction coincides with the axial direction in which the magnetization is easy, the excitation characteristics in the rolling direction are extremely excellent and the iron loss is small. Further, by forming an oxide film on the surface and pulling the steel strip in the rolling direction, iron loss can be further reduced and at the same time low magnetostriction can be realized. Especially in the texture of (110) [001] orientation, the directional silicon steel strip in which the average deviation angle of the [001] axis with respect to the plate surface and rolling direction is suppressed to about 3 degrees is called high bee and has low loss. Known as transformer material.

At present, there are a double rolling method and a single rolling method as a method for producing the grain-oriented silicon steel strip. In the double rolling method, the steel ingot is thinned to a thickness of about 2 to 3 mm by hot rolling, and the final thickness is obtained by normalizing, primary cold rolling, intermediate annealing, secondary cold rolling, decarburizing annealing, and finishing annealing. Is a method of making a steel strip of about 0.3 mm. The single rolling method is a method of obtaining a steel strip having a final thickness similar to the above by subjecting a steel ingot to hot rolling, strong cold rolling, decarburization, and finish annealing.

[Problems to be solved by the invention]

However, with these methods, it is difficult to industrially produce a sheet having a final thickness of 0.2 mm or less. That is, it is extremely difficult to reduce the plate thickness during cold rolling to 0.2 mm or less due to mechanical and material restrictions of the rolling mill currently used. Further, excessive rolling of 0.2 mm or less results in a decrease in the degree of integration of Goss texture during secondary recrystallization and, conversely, an increase in iron loss value. That is, in general, when realizing a Goss texture, 1
In order to suppress the growth of secondary recrystallized grains, trace amounts of AlN, MnS, Mn
An inhibitor such as Se / Sb is added to the so-called molten metal in which silicon steel is melted, but the effect of this inhibitor becomes extremely weak when the plate thickness is thin.

On the other hand, the iron loss of grain-oriented silicon steel strip having Goss orientation decreases the eddy current effect as the sheet thickness decreases. Therefore, further reduce the sheet thickness to reduce the iron loss as much as possible. Is desired. However, in the current oriented silicon steel strip,
Since it is difficult to reduce the plate thickness to 0.2 mm or less as described above, it is not possible to obtain sufficiently satisfactory magnetic properties in terms of iron loss and magnetic flux density.

A rapid cooling solidification method is being developed as a method for obtaining a silicon steel strip having magnetic properties superior to those of the grain-oriented silicon steel strip.

This method is a very short method in which a high-concentration iron melt having a silicon content of, for example, 6% by weight or a melt of iron containing silicon and boron is thinly drawn by a water-cooled twin roll method or a single roll method. This is a method of cooling and solidifying in a time period to obtain a non-oriented crystalline or amorphous ultrathin band (about 0.04 to 0.08 mm).

However, this rapid cooling solidification method not only requires high control technology and eventually raises the production cost, but also requires the peripheral speed of the roll to be about 12 to 20 m / sec in order to rapidly cool the molten metal, For this reason, there are drawbacks such as equipment and space for processing the ultra-thin strip that is peeled off from the roll at high speed.

Conventionally, a method of manufacturing a steel sheet having a Goss structure as described in JP-A-55-131128 has been proposed.

This manufacturing method is a method of cold rolling a steel sheet having a Goss structure to generate primary crystals, and a method of performing annealing to generate tertiary recrystallization by subsequent heating, in the cold rolling. This is a method of reducing the thickness by 40 to 85%, heating to 700 to 900 ° C, and then annealing at 1300 to 1500 ° C.

Specifically, this method holds a steel sheet having a goth structure at 900 ° C. for 1 to 3 minutes after cold rolling, and then 100 ° C./hour (0.
The temperature is raised up to the annealing temperature (1300 to 1500 ° C.) over a few hours at a very slow heating rate (08 ° C./sec), and the annealing temperature is maintained for 0.5 to 1 hour.

However, according to the findings of the experiments conducted by the present inventors, heating at 700 to 900 ° C. after the cold rolling (110) [001]
The primary recrystallization having a texture grows, and then the temperature rises very slowly, so that the secondary recrystallized grains grow large.
At a high temperature of 00 to 1500 ° C, the tertiary recrystallized grains having (110) [001] texture grow, but as described above, the secondary recrystallized grains have already grown largely, and the annealing time Since they are short, they cannot all become tertiary recrystallized grains having a (110) [001] texture, and as a result, there are many crystal grains whose [001] orientation deviates from the rolling orientation, resulting in poor orientation and magnetic flux density. It is estimated to be a low silicon steel sheet.

The object of the present invention is to solve the above-mentioned problems of the prior art, to reduce the thickness of the steel strip, to increase the degree of (110) [001] orientation integration, to have low loss characteristics, and to improve productivity. It is an object of the present invention to provide a method for producing an ultra-thin ribbon of low-loss directional silicon steel, which has good processing cost and low cost. [Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention is directed to removing the surface coating of, for example, a commercially available grain-oriented silicon steel strip in which the texture of the crystal has a (110) [001] orientation. The first step of forming an intermediate ultra-thin steel strip having a (111) [112] orientation by cold rolling the oriented silicon steel strip material, and the intermediate ultra-thin steel strip after the first step, For example, by performing a high-temperature heat treatment in which the temperature is raised at a heating rate of 1.5 ° C / sec or more and kept in a temperature range of 1000 to 1400 ° C for 3 hours or more in a non-oxidizing atmosphere such as a reduced pressure or an inert gas atmosphere, , A second step of obtaining a low-loss directional silicon steel ultra-thin ribbon consisting of a texture of tertiary recrystallization having a (110) [001] orientation that is more highly integrated than the starting material. To do.

〔Example〕

The silicon content in the silicon steel strip used in the present invention is 2 to
It is advisable to use those regulated in the range of 8% by weight. Since a silicon steel strip containing silicon in an amount of about 2% by weight or more does not have a γ-transformation, it is possible to increase the grain size by high temperature annealing and to cause secondary and tertiary recrystallization to form a preferable texture. However, if the silicon content is less than 2% by weight, the above-mentioned features are not exhibited. On the other hand, when the content of silicon exceeds 8% by weight, the saturation magnetic flux density is about 1.7 T or less, which is not suitable as a magnetic material.
It is mechanically extremely fragile, which is not preferable. In particular, a silicon content of 2.5 to 4.0% by weight is preferable because it has excellent mechanical properties such as rolling and a saturation magnetic flux density of 1.95 T or more.

In silicon steel strip, for example, Mn, Al, S, Se, Sn, Sb, Mn
If necessary, S, MnSe / Sb, AlN and the like can be added in a total amount of up to 0.5% by weight. In addition, a small amount of Ni, Cu, Mo, W, Co, Cr or the like may be contained as an inevitable mixed element. Furthermore, the content of unavoidable impurities such as O, N, and C must be limited in accordance with the final quality of the desired ribbon.

As the grain-oriented silicon steel strip used in the present invention, a commercially available grain-oriented silicon steel strip can be used. As commercially available grain-oriented silicon steel strips, for example, those shown in Tables 1 and 2 below can be used.

For example, in Table 1, iron loss (W _17/50 ) is 1.33 to 2.00 W / kg or less and magnetic flux density (B ₈ ) is 1.68 to 1.79 T or more, or iron loss (W _17/50 ) is as shown in Table 2. Is 1.05 to 1.37 W / kg or less, magnetic flux density (B
Those having different characteristics such as ₈ ) of 1.89 or more can be used, and the magnetic characteristics are further improved by the present invention.

Commercially available grain-oriented silicon steel strips have sheet thicknesses of 0.30 mm (300 μm) and 0.35 mm (350 μm), as shown in the above table. Using these silicon steel strips as a raw material, the plate thickness is rolled to 150 μm or less by cold rolling. It suffices if this rolling rate is 50% or more, and the original purpose of cold rolling is that the deviation angle is large with respect to the rolling direction from the (110) [001] oriented directional silicon steel strip. It is to obtain an ultrathin intermediate having a (111) [112] orientation with crystal strain.

Further, according to the present invention, when the plate thickness exceeds 150 μm, (110) [00
It was confirmed that recrystallized grain growth in the 1] orientation is unlikely to occur. The reason for this is considered to be that if the plate thickness exceeds 150 μm, the surface energy becomes a driving force, and the plate thickness is too large for the (110) plane having the lowest surface energy to grow.

In order to prevent the metal from being oxidized during the heat treatment and deteriorating the magnetic properties, the heat treatment after cold rolling may be performed in an inert atmosphere such as nitrogen gas or argon gas, a hydrogen gas atmosphere, an inert gas and a hydrogen gas. Is performed in a mixed gas atmosphere, a reduced pressure atmosphere of various gases as described above, or a non-oxidizing atmosphere such as a simple reduced pressure atmosphere. In the case of the aforementioned simple decompression, the degree of vacuum may be, for example, about 2 × 10 ^{−4 to} 5 × 10 ⁻⁶ Torr.

The heating furnace for heat treatment may be a continuous type or a batch type.

Heat treatment temperature is about 1000-1400 ℃, heat treatment time is about 3〜
24 hours, preferably about 7 hours or more to secure the time required for crystal growth, and the heat treatment temperature rising rate is about 1.5 ° C./second or more, preferably about 3 ° C./second or more.

After the heat treatment, in order to prevent deterioration of mechanical properties and magnetic properties, cooling in the same non-oxidizing atmosphere as in the heat treatment of the second step can maintain the preferable texture obtained at high temperature. You can

Next, a specific example of the processing method according to the present invention will be described.

Directional silicon steel strip (Z6H manufactured by Nippon Steel) was used as a material. The characteristics and the like of this grain-oriented silicon steel strip are as follows.

First, this silicon steel strip is dipped in a mixed solution of concentrated sulfuric acid and hydrofluoric acid (concentrated sulfuric acid 3 to hydrofluoric acid 1) for 30 minutes, then washed with water, further pickled with a 10% nitric acid aqueous solution, and washed with water. The insulating film and oxide film formed on the surface of the strip are removed. This coating adheres to (110) [00] during annealing after cold rolling.
1] Inhibits the growth of recrystallized grains in the orientation.

Next, it is rolled to a size of 80 μm using a two-roll rolling mill with a diameter of 50 mm, and thereafter, each end is removed to cut it into a size of 20 mm in width and 100 mm in length to obtain a sample. As mentioned above,
Since a sample of 300 μm was rolled to 80 μm to make a sample, the rolling ratio of this sample is 73%.

The sample was then placed in a quartz tube and 1.3 × 10 ^-3 Pa (9.7
Heat treatment was performed under a high vacuum of 5 × 10 ⁻⁶ Torr) using an infrared concentrated heating furnace at a heating rate of 3 ° C./sec. Observation of the crystal grains after this heat treatment was performed using an X-ray Laue photograph, X-ray pole observation and an optical microscope, and magnetic characteristics were measured using a BH loop tracer.

As described above, by cold rolling to 80 μm, the texture of the crystal grains has a misorientation angle of 3 with respect to the rolling direction.
X is approximately (111) [112] azimuth, which is as large as 5.3 degrees.
It was confirmed by the line pole figure.

When the heat treatment condition after cold rolling is 300 ° C. for about 1 hour, the internal strain received during processing remains without being released.
As shown in the figure, the magnetic characteristics are poor. When the heat treatment temperature is further raised, the internal strain is released and recrystallization starts at around 500 ° C. These recrystallized grains (primary recrystallized grains) are (110) [00
1) The magnetic flux density is high because it has a texture of orientation,
The average crystal grain size has developed almost the same as the plate thickness (about 80 μm), and the coercive force (Hc) has not fallen sufficiently. Therefore, the iron loss value (1.7T) at 50 Hz is as large as about 2 W / kg, which is about twice the iron loss value of the grain-oriented silicon steel strip with a plate thickness of 300 μm. FIG. 2 is a BH loop characteristic diagram when heat-treated at 500 ° C. for 1 hour, and as described above, it can be seen that Hc is not sufficiently reduced by this heat-treatment.

FIG. 3 is an iron loss characteristic diagram. In FIG. 3, a curve A is a characteristic curve of a heat-treated piece at 700 ° C. for about 1 hour, and a curve B is a characteristic curve of a grain-oriented silicon steel strip that is not heat-treated. As is clear from this figure, those having a texture of primary recrystallization have a high iron loss value.

FIG. 4 is a diagram showing the relationship between heat treatment temperature (heat treatment time of 1 hour) and magnetic properties. In the figure, curve C is a characteristic curve showing the relation between heat treatment temperature and coercive force, and curve D is the heat treatment temperature and magnetic flux density. It is a characteristic curve showing a relation with. As is clear from this figure, the coercive force (Hc) sharply decreases and the magnetic flux density (B ₈ ) sharply increases from around 500 ° C. where primary recrystallized grains appear.

In order to further improve the magnetic properties, it is necessary to increase the degree of integration in the rolling direction in the crystal structure of (110) [001] orientation and to increase the crystal grains to reduce the coercive force (Hc).

Since the (110) [001] texture appeared due to the primary recrystallization as described above, it was considered to increase the crystal grain size. However, when the heat treatment temperature is raised to grow the crystal grains, secondary recrystallization occurs and the secondary recrystallized grains having a grain size of 0.5 to 0.7 mm, which is about 10 times the primary recrystallized grains, are covered. It ends up becoming a non-Goss organization. Fig. 5 is a characteristic diagram showing the relationship between the heat treatment temperature (heat treatment time of 1 hour) and the grain size of the crystal grains. As is clear from this figure, the grain size is sharp when the heat treatment temperature is in the range of about 1000 to 1100 ℃. You can see that it is getting bigger.

The texture of the secondary recrystallized grains is not only the texture of (110) [001] orientation, but (110) [001] and (120) [0]
01] direction, (111) [110] direction and (111) [100]
Various crystal orientations such as orientations are mixed. The magnetic characteristics of this are smaller than those of the primary recrystallized grain structure because the crystal grain size is large, but the coercive force (Hc) value is small, but the deviation between the rolling direction of the sample and the easy axis of magnetization is large. Therefore, the magnetic flux density is reduced. Dunn's paper [Acta. Met .; 1 , (19)
53), 163.], the secondary recrystallized grains are (120) [00
It has been reported that three types of 1], (111) [110], and (100) and (111) intermediate planes appear. The difference between the present invention and Dunn's paper is that the presence of secondary recrystallized grains of (110) [001] is recognized, and this is the nucleus of the third recrystallization, which is important in the present invention. It is a point.

The rate of temperature rise during the heat treatment suppresses the growth of crystal grains obtained in the primary and secondary recrystallization processes, keeps the grain size as small as possible, and is highly integrated in the subsequent tertiary recrystallization growth process ( 11
0) In order to promote generation of [001] -oriented crystal grains, it is desirable to increase the temperature rising rate as much as possible.

FIG. 6 is a characteristic diagram showing the relationship between the temperature rising rate and the appearance rate of the third-order recrystallized structure. As is clear from this figure, when the heating rate is about 1.5 ° C / sec or more, the appearance rate of the third-order recrystallized structure is high, and especially when the heating rate is about 3 ° C / sec or more (110)
The fact that the [001] orientation is accumulated within 2.5 degrees with respect to the rolling direction and forms a nearly 100% tertiary recrystallized structure,
It was confirmed by X-ray Laue photograph and optical microscope observation.
This result was also confirmed when the atmosphere was hydrogen, or a mixed atmosphere of hydrogen and nitrogen, or hydrogen and argon.

FIG. 7 is a characteristic diagram showing the relationship between heat treatment temperature (heat treatment time of 1 hour) and magnetic characteristics. Curve E is a characteristic curve showing the relation between heat treatment temperature and coercive force (Hc), and curve F is the heat treatment temperature and magnetic flux. 6 is a characteristic curve showing a relationship with the density (B ₈ ). As is clear from this figure, the higher the temperature (for example, 1000 to 1350
℃) Coercive force (Hc) decreases, but magnetic flux density (B ₈ ) also tends to decrease gradually.

Since good magnetic properties cannot be obtained with the secondary recrystallization texture, the heat treatment conditions for the secondary recrystallization texture were further investigated. First is the heat treatment temperature,
At a high temperature of about 1000 to 1400 ° C., crystal grains are obtained as shown in FIG. 5 and coercive force (Hc) is reduced as shown in FIG.
It was set to about 00 to 1400 ° C. Next, regarding the heat treatment time, since the heat treatment time up to now was a short time of about 1 hour, it is considered that the growth of crystal grains is insufficient, and heat treatment for a longer time (for example, 3 to 24 hours) is performed. investigated. By heat-treating at such a high temperature (about 1000 to 1400 ° C) for a long time (about 3 to 24 hours), (110) [001] in secondary recrystallized grains in which various crystal orientations are mixed. ] The crystal grains of the direction grow by eating other secondary recrystallized grains around, and finally (11
0) The entire surface was covered with [001] crystal grains. By heat-treating at high temperature for a long time in this way, a texture of a tertiary recrystallized structure is formed, and the size of the crystal grain reaches a large size of about 5 to 20 mm. ] The axis deviation angle is within 2.5 degrees.

When observing the state of the growth of the third-order recrystallized structure from the viewpoint of magnetic characteristics, it changes as shown in FIG. In this experiment, the heat treatment temperature was set to 1200 ° C. and the heat treatment time was variously changed. The curve G in the figure shows a characteristic curve showing the relationship between the heat treatment time and the coercive force (Hc), and the curve H shows the heat treatment time and the magnetic flux density ( It is a characteristic curve showing a relationship with B ₈ ).

As is clear from this figure, a remarkable change appears that the coercive force (Hc) increases with the heat treatment time up to about 2 hours after the start of heat treatment at a high temperature, reaches a peak around 2 hours, and then begins to decline. From around that time, the growth of the third recrystallized structure in the (110) [001] orientation began,
The magnetic flux density (B ₈ ) rises sharply after 3 hours,
Good magnetic properties can be obtained. Although not shown in the figure, Hc of 1.6 A / m was finally obtained after heat treatment at 1200 ° C for 8 hours.
At (= 20 mOe), B ₈ is 1.95 T, and a highly oriented grain oriented silicon steel ultra-thin strip with good magnetic properties can be obtained.

Fig. 9 shows the BH loop characteristics of the sample that was heat-treated at 1200 ° C for 8 hours, and it was shown in Figs. 1 and 2 because the third-order recrystallized grains having the (110) [001] orientation were sufficiently developed. It has a very sharp BH loop characteristic compared to the one.

After the heat treatment at a high temperature for a long time to form the third recrystallized structure, the third structure is cooled in the non-oxidizing atmosphere without changing the crystal structure.

Further, FIG. 10 is a characteristic diagram showing the iron loss value with respect to each magnetic flux density of the highly oriented grain-oriented silicon steel ultrathin ribbon having the third-order recrystallized structure. A curve I in the figure is an iron loss value curve of the third recrystallized structure formed by the heat treatment as described above, and a curve J is a directional silicon steel ultrathin ribbon having the third recrystallized structure. After that, after applying a film forming agent such as a magnesium salt such as magnesium chloride or an oxide of silicon to the surface of the steel strip, it is heated to about 1000 ° C, and as a result, the steel strip is 1 to 4 kg /. It is an iron loss value curve when a tension of mm ² is applied.

As is clear from this figure, the highly oriented grain-oriented silicon steel ultra-thin ribbons having a tertiary recrystallized structure according to the example of the present invention have an iron loss value lower than that shown in FIG. It was able to drop extremely. By applying tension to this highly oriented grain-oriented silicon steel ultra-thin strip in the rolling direction, the iron loss value can be reduced to almost the same level as the amorphous one obtained by the rapid cooling solidification method described above. it can.

In the above embodiment, the case where the heat treatment is performed at 1200 ° C. for 7 to 8 hours has been described, but it has been confirmed by experiments that similar magnetic characteristics can be obtained even if the heat treatment is performed at 1150 ° C. for 9 to 24 hours.

〔The invention's effect〕

The following Table 3 shows the properties of the low loss and highly oriented oriented silicon steel ultrathin strip obtained by the production method according to the present invention, and the product properties of the oriented silicon steel strip obtained by the conventional method and It is a table which compares and shows a magnetic characteristic.

As is clear from this table, the low-loss, highly-oriented directional silicon steel ultra-thin ribbon according to the present invention has a higher magnetic flux density, a smaller coercive force, and a lower iron loss than other materials. The characteristics are remarkably improved.

As described above, the present invention is applied to the high temperature heat treatment temperature (1000 to 1400).
Temperature rise rate of 1.5 ℃ / sec or more (5400 ℃)
/ Hr) or more), and the holding time at the high temperature heat treatment temperature is as long as 3 hours or more.

This is because the (111) [112] texture by cold rolling is changed to the primary recrystallization, secondary recrystallization, and tertiary recrystallization by the subsequent heat treatment, and the desired highly oriented (110) [001] texture is obtained. In order to obtain a tertiary recrystallization having a structure, it is necessary to quickly pass through the low temperature region in order to increase the size of the primary recrystallization and secondary recrystallization grains that appear in the low temperature region and not to grow stable grains. Based on the experimental results shown in FIG. 6 and the like, the heating rate was set to 1.5 ° C./sec or more.

Next, 1 of (110) [001] remaining in the secondary recrystallization group
In order to make the third recrystallized grains grow large by using the second recrystallized grains as nuclei, it is necessary to extend the holding time at 1000 to 1400 ° C. to 3 hours or more. The present invention is a highly oriented silicon steel electrode having a high magnetic flux density, a small coercive force, and a low iron loss due to the correlation between the temperature rising rate, the holding time at the high temperature heat treatment temperature, and the control of the plate thickness by cold rolling. A ribbon can be obtained.

If the silicon steel strip of the present invention is used in, for example, a transformer or the like, it is possible to reduce the size of the product and increase the efficiency thereof, and it is possible to have various uses. Further, it is possible to use an ordinary grain-oriented silicon steel strip that is commercially available as a raw material, and further, since the treatment method is simple, it is possible to provide a highly oriented silicon steel ultra-thin strip with good productivity and low treatment cost. be able to.

[Brief description of drawings]

1 and 2 are BH loop characteristic diagrams, FIG. 3 is an iron loss characteristic diagram, FIG. 4 is a characteristic diagram showing the relationship between heat treatment temperature and magnetic characteristic, and FIG. 5 is heat treatment temperature and crystal grain size. 6 is a characteristic diagram showing the relationship between the heating rate and the appearance rate of the third-order recrystallized structure, FIG. 7 is a characteristic diagram showing the relationship between heat treatment temperature and magnetic characteristics, and FIG. Fig. 9 is a characteristic diagram showing the relationship between heat treatment time and magnetic properties. Fig. 9 is a BH loop characteristic diagram.
Figure 0 is an iron loss characteristic diagram.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiyoshi Kojima 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-55-131128 (JP, A) JP-A-61-217526 (JP, A)

Claims (7)

[Claims] 1. A thickness of a unidirectional silicon steel strip material having a (110) [001] crystal grain texture is cold-rolled.
A first step for producing an intermediate ultrathin ribbon having a (111) [112] texture of 150 μm or less, and a heating rate of 1.5 ° C./sec or more in the non-oxidizing atmosphere of the intermediate ultrathin ribbon after the first step. 1000 to 1400
By performing heat treatment for 3 hours or more in the temperature range of ℃, the average grain size was highly integrated with more than 5 mm (1
10) A method for producing an ultra-thin ribbon of low-loss directional silicon steel, which comprises passing through a second step of obtaining an ultra-thin ribbon composed of a texture of tertiary recrystallized grains having a [001] orientation. 2. In the claim (1),
The method for producing a low-loss directional silicon steel ultra-thin strip, wherein the content of silicon in the directional silicon steel strip material is 2 to 8% by weight. 3. Claims (1) or (2)
In the paragraph, in the low-loss direction silicon steel ultra-thin ribbon, the average deviation angle of the (001) axis with respect to the rolling direction of the low-loss direction silicon steel ultra-thin ribbon has a high orientation within 2.5 degrees. Manufacturing method. 4. Claims (1) or (2)
5. The method for producing an ultra-thin ribbon of low loss directional silicon steel according to the item 1, wherein the non-oxidizing atmosphere is an inert gas or a hydrogen gas, or a mixed atmosphere of an inert gas and a hydrogen gas. 5. In the claim (4),
A method for producing a low-loss directional silicon steel ultra-thin ribbon, characterized in that the non-oxidizing atmosphere of the gas is depressurized. 6. Claims (1) or (2)
The method for producing a low-loss directional silicon steel ultrathin ribbon as described in the item 1, wherein the non-oxidizing atmosphere is a reduced pressure atmosphere. 7. Claims (1) or (2)
In the item, the ultrathin steel strip is cooled after the second step,
Next, a method for producing a low-loss directional silicon steel ultra-thin strip characterized in that a coating film-forming agent is applied to the surface of the ultra-thin steel strip and heated to form a film.