JPH07126751A - Method for producing mirror-oriented silicon steel sheet with good coating adhesion - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain a high magnetic flux density grain-oriented electrical steel sheet with a mirror surface and good film adhesion. A high-strength coating can be applied to this with good adhesion, and ultra-low iron loss can be achieved. [Structure] Si: 2 to 4.8%, acid-soluble Al: 0.0
08-0.06%, N: 0.01% or less, B: 0.00
05-0.0060%, C: 0.0050-0.120
% Of the hot-rolled silicon steel strip is cold-rolled once or twice or more with intermediate annealing to obtain the final thickness, and then subjected to primary recrystallization annealing, and then, if necessary, during primary recrystallization annealing. The oxide layer on the surface of the produced steel sheet is removed, an annealing separator is applied, finish annealing is performed, and then a tension film is applied. [Effect] With a high magnetic flux density, a grain-oriented magnetic steel sheet having a mirror surface can be obtained. A tensile strength coating can be applied to this steel sheet with good adhesion, and ultra-low iron loss can be achieved. It can contribute to the reduction of energy loss and contribute greatly to society.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a grain-oriented silicon steel sheet (hereinafter referred to as grain-oriented electrical steel sheet) having a high magnetic flux density and an extremely low iron loss. In the secondary recrystallization process (finishing annealing process), a high magnetic flux density is obtained, and at the same time, the steel plate surface is mirror-finished by thermal etching without forming a forsterite film (hereinafter referred to as a glass film) on the steel plate surface. Complete the process, then
It aims to reduce the energy loss of electric power by providing magnetic materials with extremely low iron loss by performing processing such as magnetic domain subdivision and tension application.

[0002]

2. Description of the Related Art Grain-oriented electrical steel sheets are frequently used as magnetic iron cores for electric equipment and have been repeatedly improved in order to reduce energy loss. As a means for reducing the iron loss of grain-oriented electrical steel sheets, a method of irradiating a laser beam on the surface of the material after finish annealing to give local strain to thereby subdivide the magnetic domains to reduce the iron loss is disclosed in, for example, Japanese Patent Application Laid-Open No. 58-264
No. 05 publication. Further, since the local strain is removed by the stress relief annealing (strain relief annealing) that is usually performed after processing, the magnetic domain refining effect disappears. This remedy, that is, means for preventing the magnetic domain refining effect from disappearing even when stress-relief annealing is disclosed, for example, in Japanese Patent Application Laid-Open No. 62-8617. In order to further reduce the iron loss value, it is important to remove (smooth) the irregularities on the surface of the base metal that hinder the movement of magnetic domains near the surface of the steel sheet.

The highest level of smoothing is specular. As a method of smoothing (mirror-finishing) the material surface after finish annealing, there are chemical polishing, electrolytic polishing and the like disclosed in JP-A-64-83620. Furthermore, JP-A-3-11
Japanese Patent Publication No. 0627 discloses that an annealing separator is made of a substance that does not easily react with silica, such as alumina, so that a mirror-finished surface can be obtained simultaneously with secondary recrystallization. A tensile coating is applied to the mirror surface obtained by these methods to obtain a grain-oriented electrical steel sheet with low iron loss. In addition, a tension film | membrane here means the film | membrane which gives a tensile stress to a steel plate by producing | generating a substance different from the thermal expansion coefficient of a steel plate (small) on a steel plate.

[0004]

Conventionally, as a method of mirror-finishing (smoothing) the surface of a steel sheet, chemical or physical methods such as brush polishing, sandpaper polishing and grinding other than the above chemical polishing and electrolytic polishing are used. There is. However, these methods are suitable for producing small test pieces and small samples, but are accompanied by various difficulties for the surface mirror-finishing (smoothing) of industrially mass-produced metal strips and the like. The chemical method that is said to be the most smooth, that is, chemical polishing, environmental problems such as chemical concentration control and wastewater treatment, and the physical method, the surface with an industrially large area is smoothed by the same standard. It is extremely difficult to make it (mirrored).

The present invention eliminates these problems and provides a method of mirror-finishing or smoothing the surface of grain-oriented electrical steel sheet on an industrial production scale, and the obtained mirror surface is convenient for applying a tension coating. That is, it is an object of the present invention to provide a mirror surface (surface) capable of forming a tension film having good adhesion. The tension on the steel sheet can be obtained by applying a substance (tension coating) having a (small) coefficient of thermal expansion different from that of the steel sheet onto the steel sheet. This is because at this temperature, film formation or strain relief annealing during processing is performed at 600 to 1000 ° C.
Although the strain between the steel plate and the film is eliminated, after cooling, stress is generated in both due to the difference in thermal expansion coefficient. At this time, of course, strain is generated between the steel sheet and the substance (tensile coating) having a different (smaller) thermal expansion coefficient, and the bonding state between the steel sheet and the material (tensile coating) having a different (smaller) thermal expansion coefficient is poor. When (weak), the two are separated. Since it is necessary to apply a high tension to the steel sheet in order to obtain a low iron loss, the adhesion between the steel sheet and the tension film is becoming more and more important.

[0006]

A feature of the present invention is that a mirror surface or a smooth surface is obtained with a high magnetic flux density during finish annealing, and at the same time, this surface is advantageous for forming a tension film. Si: 2.0 to 4.8% by weight, acid-soluble Al:
0.008-0.06% by weight, N ≦ 0.010% by weight,
B: 0.0005 to 0.0060% by weight, C: 0.00
Using a silicon steel material consisting of 5 to 0.12% by weight, the balance Fe and unavoidable impurities, hot rolling, cold rolling, and primary recrystallization annealing are performed, and if necessary, the oxide layer is removed to remove the annealing separator. Apply and finish anneal. As a result, a grain-oriented electrical steel sheet with a high magnetic flux density is obtained, and at the same time, the glass (forsterite) coating is not formed on the surface of the steel sheet, but the secondary recrystallization is performed with the metal surface exposed. The surface can be specular, which is convenient for tension coating.

The specific means is Si: 2.0 to 4.8.
% By weight, acid-soluble Al: 0.008 to 0.06% by weight,
N ≦ 0.010% by weight, B: 0.0005 to 0.006
0% by weight, C: 0.005-0.12% by weight, balance Fe
And a silicon steel material consisting of unavoidable impurities is hot-rolled to form a silicon steel strip, which is annealed as needed, and then cold rolled once or twice with intermediate annealing to obtain a final plate thickness, Then, after performing the primary recrystallization annealing, if necessary, remove the oxide layer generated on the steel sheet surface during the primary recrystallization annealing, apply an annealing separator and perform finish annealing in a neutral or reducing atmosphere, then, It is to subdivide the magnetic domain and apply a tension film.

Here, the oxide layer formed on the surface of the steel sheet during the primary recrystallization annealing is removed to remove Al ₂ O ₃ , SiO ₂ , Zr.
An annealing separator containing at least one of O ₂ , BaO, CaO, SrO and forsterite as a main component is applied to the steel sheet, finish annealing is performed in a neutral or reducing atmosphere, and then a tension film is applied. After performing the primary recrystallization annealing, nitriding treatment with ammonia is performed to remove the oxide layer formed on the surface of the steel sheet during the primary recrystallization annealing.
₂ O ₃ , SiO ₂ , ZrO ₂ , BaO, CaO, SrO
And, an annealing separator containing one or more of forsterite as a main component is applied to the steel sheet, finish annealing is performed in a neutral or reducing atmosphere, and then a tension film is applied, primary recrystallization annealing. After performing the primary recrystallization annealing, an annealing separation agent containing a chlorine compound of Bi is applied without removing the oxide layer formed on the surface of the steel sheet, and finish annealing is performed in a neutral or reducing atmosphere, and then the tension coating is applied. After applying, after performing primary recrystallization annealing, nitriding treatment with ammonia was applied, and an annealing separator containing a chlorine compound of Bi was applied without removing the oxide layer formed on the surface of the steel sheet after primary recrystallization annealing. Finish annealing in a neutral or reducing atmosphere, then apply a tension film, and perform primary recrystallization annealing at a dew point of 40 ° C or less, and then, if necessary, prepare the steel sheet surface during primary recrystallization annealing. The oxide layer that is removed, the annealing separator was coated perform finish annealing in a neutral or reducing atmosphere,
After that, the magnetic domain is subdivided and a tension coating is applied to obtain a mirror-oriented silicon steel sheet having good coating adhesion.

Further, the amount of oxygen on the surface of the steel sheet after the removal of the oxide layer is 0.30 g / m ² or less per surface of the steel sheet, the method of removing the oxide layer on the surface of the steel sheet is pickling, and the pickling method Is pickled with an acid mixed with hydrofluoric acid, the tension film is composed of components mainly composed of silicate, phosphate and chromate, and the tension film is composed mainly of oxides of aluminum and boron. That is, it is effective for the purpose of the present invention to set N ₂ to 5% or more in the atmosphere at the time of finishing annealing.

The present invention will be described in detail below. The present inventors have investigated in detail the rate-determining process of inhibitor deterioration during finish annealing, and when Al is contained in the components of the hot-rolled steel sheet, the oxidation process of Al at the steel sheet interface is the largest factor, and the primary recrystallization annealing is performed. It was found that the oxide layer on the surface of the steel sheet, which occurs occasionally, is greatly involved in the deterioration of the inhibitor.

First, the case where the hot-rolled steel strip component contains Al will be described. The present inventors have conducted a detailed investigation on the rate-determining process of inhibitor deterioration during finish annealing. As a result, the largest factor is the oxidation process of Al at the steel sheet interface, and the oxide layer on the surface of the steel sheet that occurs during primary recrystallization annealing deteriorates the inhibitor. I was found to be heavily involved in.

Si: 3.3% by weight, acid-soluble Al: 0.
028% by weight, N: 0.008% by weight, Mn: 0.14
% By weight, S: 0.007% by weight, C: 0.05% by weight,
1 hot-rolled silicon steel strip consisting of the balance Fe and unavoidable impurities
0.23mm after cold-rolling after annealing at 100 ℃ for 2 minutes
Made thick These cold-rolled sheets were annealed at 800 ° C. for 2 minutes in an annealing furnace in a wet atmosphere to serve also as decarburization, and primary recrystallization was performed. Next, in order to stabilize the secondary recrystallization, nitriding treatment was performed in an ammonia atmosphere, and the total nitrogen amount was 180 pp.
m and strengthened the inhibitor.

Thereafter, as it is (oxygen amount per one side,
0.85 g / m ² ) and 0.5% hydrofluoric acid-5% sulfuric acid mixed solution for pickling (oxygen amount per one side: 0.04 g / m ² ).
m ² ) Al ₂ O ₃ is electrostatically applied to two kinds of materials, and 100%
Finish annealing was performed in an H ₂ atmosphere while maintaining a temperature rising rate of 15 ° C./Hr. Inhibitor during finish annealing (Al
N, (Al, Si) N, etc.), as shown in FIG. 1, the material having an oxide layer formed on the surface of the steel sheet during the primary recrystallization annealing showed a higher inhibitor content than the material having no oxide layer. It was found that the strength deteriorates quickly. That is, if the oxide layer formed on the surface of the steel sheet during the primary recrystallization annealing is removed, the strong inhibitor strength can be maintained up to a high temperature.

Acid-soluble Al in the steel sheet is
Oxygen is removed from the oxide layer mainly composed of SiO ₂ and Al ₂ O ₃
Etc. and precipitate in the oxide layer. Therefore, the acid-soluble Al in the steel sheet decreases. In FIG. 1, the acid-soluble Al concentration in steel is shown as the inhibitor strength.
Forms a compound (precipitate) such as AlN, (Al, Si) N and acts as an inhibitor.
It can be considered that the amount of 1 is an index showing the inhibitor strength.

Further, the inventors of the present invention have conducted a detailed investigation on the rate-determining process of inhibitor deterioration, and found that the amount of nitrogen in the steel and the amount of nitrogen in the annealing atmosphere are also influenced in addition to the oxidation of Al at the steel sheet interface. It was The amount of nitrogen in the annealing atmosphere increases the amount of nitrogen in the steel through the steel sheet interface, and the effect is the same as nitrogen contained in the steel from the beginning. Nitrogen in steel and nitrogen in the annealing atmosphere increase precipitates such as AlN and fix Al to form Al.
Oxidation of Al is suppressed in order to reduce the movement of Al to the steel sheet interface. Therefore, as for the amount of acid-soluble Al in steel during finish annealing, the higher the nitrogen partial pressure is, the less the deterioration is, and the stronger the inhibitor is at high temperature.

In order to obtain a high magnetic flux density, which is one of the gist of the present invention, it is preferable that the inhibitor be strong, but it is desirable that the inhibitor be strongly and constantly maintained. This is because only crystals with good orientation (GOSS grains) grow from the start to the end of secondary recrystallization, and if the inhibitor weakens from the start to the end of secondary recrystallization, grains with bad orientation grow and The magnetic flux density of the steel plate decreases.
The solubility of AlN, which is an inhibitor, naturally increases as the steel sheet temperature rises, and the inhibitor inevitably deteriorates. As a measure for this, it is desirable to increase the partial pressure of nitrogen as the temperature rises to increase the amount of nitrogen in the steel sheet and keep AlN as a precipitate constant.

However, the nitrogen partial pressure must not be too high in order to obtain a mirror surface, which is one of the gist of the present invention. Secondary recrystallization at a constant temperature at which the solubility of AlN does not change, that is, the inhibitor strength does not change, is extremely effective in that the inhibitor is secondarily recrystallized at a constant strength. As mentioned above, AlN
The solubility of Al does not change if it is maintained at a constant temperature, but the acid-soluble Al takes oxygen from the oxygen in the atmosphere or from the oxide of the element that has a lower oxygen affinity than Al on the surface of the steel sheet.
It becomes l ₂ O ₃ and decreases, and the inhibitor deteriorates. Therefore, also in this case, it is necessary to raise the nitrogen partial pressure to suppress the dissolution of AlN and suppress the decrease of the acid-soluble Al.

The steel composition in the present invention is Si: 2.0-
4.8 wt%, acid-soluble Al and N are added as inhibitor constituent elements. Si is important in increasing the electric resistance and reducing the iron loss, but if it exceeds 4.8%, it tends to crack during cold rolling. On the other hand, if it is less than 2.0%, there is a problem in that the electric resistance is low and the iron loss is lowered. Next, the inhibitor constituent elements will be described. Acid-soluble Al is important as an inhibitor constituent element, and combines with nitrogen, silicon, etc. to form a precipitate such as AlN, (Al, Si) N, etc., and plays a role of an inhibitor. From the aspect of inhibitor strength, that is, the range in which the magnetic flux density is high, 0.008 to
It is 0.06% by weight. If nitrogen exceeds 0.010% by weight, holes called blisters occur in the steel sheet, so
This range is optimal.

Others Mn, S, Se, Sb, B, Sn,
Bi, Nb, Ti, P, Mo, Cu and the like are used as auxiliary elements. Here, it is considered that B forms a nitride such as BN and strengthens the inhibitor.
0 to 0.0060% by weight is suitable. B is 0.000
If it is less than 5% by weight, the effect of improving coating adhesion is insufficient,
If it exceeds 0.0060% by weight, the inhibitor becomes too strong and the magnetic flux density (B ₈ ) does not improve, but rather decreases. Suitable carbon content is 0.005 to 0.120% by weight. If it is less than 0.0050% by weight, the secondary recrystallization is unstable, and if it exceeds 0.120% by weight, the decarburization annealing (primary recrystallization annealing) time becomes too long, which is not practical. C is 0.
It is preferably 085% by weight or less.

The present inventors have investigated in detail the relationship between the amount of surface layer removed after the primary recrystallization annealing and the magnetic characteristics. Generally, the primary recrystallization annealing is performed in a wet atmosphere for decarburizing the steel sheet, so that an oxide layer is formed on the surface of the steel sheet. Since hydrogen is added to the wet atmosphere at this time so as not to oxidize iron, only elements having a higher oxygen affinity (larger) than iron in steel are oxidized. In silicon steel, since the amount of Si is extremely large as compared with other additive elements, the main oxide layer formed on the surface is silica (SiO ₂ ).

When the inventors analyzed the composition of the oxide on the surface of the primary recrystallization annealed plate, 90% or more was silica. Further, when the distribution in the depth direction was analyzed by a technique such as polishing, an X-ray microanalyzer, and an electron microscope, it was found that the depth from the surface to 1 to 3 μm was reached. Here, it seems that Si in the steel becomes silica (SiO ₂ ) and is dispersed in iron. That is, according to the analysis result of the X-ray microanalyzer, the presence of Si, O and Fe is recognized in this region.

The inventors changed the amount of the surface layer removed by pickling after nitriding such a primary recrystallized steel sheet with ammonia. After that, an annealing separator having Al ₂ O ₃ (alumina) as a main component is applied to the steel sheet and dried, and the temperature is raised to 1200 ° C. at a heating rate of 15 ° C./Hr in a 100% nitrogen atmosphere, and 1200 ° C. After the arrival, the final annealing was carried out by switching the hydrogen to 100% and holding it for 20 hours. After finishing annealing, the magnetic domain was subdivided by laser beam irradiation, and then tension coating was performed to observe the surface and examine the magnetic properties. The results are shown in Table 1.

The steel composition is Si: 3.25% by weight, acid-soluble Al: 0.029% by weight, N: 0.008% by weight,
Mn: 0.13% by weight, S: 0.007% by weight, C:
It is a material consisting of 0.06% by weight, the balance being Fe and inevitable impurities. Furthermore, for pickling, a mixed solution of sulfuric acid-hydrofluoric acid was used, and pickling was performed at normal temperature for different pickling times, and the oxygen content of the pickled steel sheet was analyzed. This was expressed as the amount of oxygen per steel plate surface area (one side).

[0024]

[Table 1]

The oxygen content of the steel sheet is 0.30 g / m ² (one side)
It can be seen below that the surface is mirror-finished and the magnetic properties are improved. However, if the oxygen content of the steel sheet exceeds 0.30 g / m ² (one side), the improvement of magnetic properties is insufficient. Further, when the oxygen content of the steel sheet is less than 0.03 g / m ² (one side), the magnetic properties seem to be slightly inferior. Therefore, the optimum amount of oxygen in the steel sheet is 0.30 g / m ² (one side) or less, and the range of the best magnetic properties is 0.30 g / m ² (one side) less than 0.04 g
/ M ² (one side) or more. Steel sheet oxygen content 0.03g /
It is understood that the magnetic properties deteriorate below m ² (one side) because the pickling is excessive and the surface of the steel sheet is roughened (the roughness is increased), which deteriorates the magnetic properties, that is, the degree of the mirror surface. Excessive pickling is also not good from the viewpoint of production, that is, the product weight is reduced.

The optimum values for the oxygen content and magnetic properties of the steel sheet are due to the reaction between the annealing separator and SiO ₂ (silica), which is the main constituent of oxygen in the steel sheet. For example, alumina is used as the annealing separator. At this time, if the oxygen content of the steel sheet is large, a large amount of mullite (Al ₂ O ₃ .SiO ₂ ) or the like is generated on the surface of the steel sheet, which hinders mirroring. In Table 1, the oxygen content of the steel sheet is 0.3
For the material exceeding 0 g / m ² (one side), the material after finish annealing is smooth, but milky white and not a perfect mirror surface. The results of observing this with an electron microscope (SEM) are shown in FIGS. 2 and 3.

FIG. 2 shows that the amount of oxygen in the steel sheet is 0.7 by pickling.
It is the result of observing the surface of the grain-oriented electrical steel sheet, which was annealed by applying alumina as an annealing separator to a material of ² g / m ² (one side) and then finish-annealed, by SEM. FIG. 4 shows the results of SEM observation of the surface of the grain-oriented electrical steel sheet obtained by applying alumina as an annealing separator on a material having an oxygen content of 0.17 g / m ² (one side) by pickling and finish annealing. A material with a steel sheet oxygen content of 0.72 g / m ² (one side) has much more fine particles on the steel sheet surface than a material with a steel sheet oxygen content of 0.17 g / m ² (one side). And elemental analysis of this with a microanalyzer or the like reveals elements such as Al and Si. Therefore, in order to prevent the formation of a reaction product with SiO ₂ , it is necessary to reduce the oxygen content of the steel sheet, but this also suppresses the deterioration of the inhibitor as described above.

Therefore, the better the smaller the value, the more another problem, that is, the problem that the surface of the steel sheet is roughened, occurs and the optimum value exists.
The state of the surface referred to as a mirror surface here satisfies the following conditions. That is, when it has a metallic luster in appearance, has little diffuse reflection of light and has no cloudiness, and magnetically, when the magnetic flux density (B ₈ ) is high,
When the magnetic domain is subdivided and the tensile tension is applied, a low iron loss is exhibited, and foreign substances other than metals such as oxides and nitrides are not present on the surface of the steel sheet. Furthermore, what is called a smooth surface (mirror surface) is a surface which is so-called dull, which has a metallic color but has a dull gloss. When the surface profile is measured with a surface roughness meter, the profile of the surface referred to as a mirror surface is smooth, the profile of the surface referred to as a smooth surface is rough, and the roughness is further increased on the surface where the metallic luster is lost.

Further, the inventors of the present invention examined a steel sheet containing B in the steel and found that the addition of B allows the tension film to be applied to the mirror surface conveniently (with good adhesion). The inventors changed the amount of B in steel and investigated the state. S
i: 3.30 wt%, acid-soluble Al: 0.028 wt%, N: 0.008 wt%, Mn: 0.13 wt%,
S: 0.008% by weight, C: 0.06% by weight, B:
Less than 0.0002% by weight, 0.0005% by weight,
0.0014% by weight, 0.0060% by weight, 0.0
A material consisting of 110% by weight, balance Fe and unavoidable impurities was annealed in a temperature range of 1200 ° C. for 80 seconds to improve the magnetic flux density using a hot rolled steel sheet.

Then, the cold rolling rate of these hot rolled steel sheets was:
It was cold rolled to a plate thickness of 0.225 mm at 89%. The material after cold rolling usually has a dew point of 60 ° C in order to remove carbon in steel.
Primary recrystallization annealing was carried out at a temperature of 810 ° C. in a humid atmosphere. At this time, along with decarburization and primary recrystallization,
An oxide layer was formed. After nitriding such a primary recrystallized steel sheet with ammonia, the surface layer was removed by pickling. The oxygen content of the steel sheet after pickling was 0.10 g / m per side.
^{Was 2} . Then, an annealing separator having Al ₂ O ₃ (alumina) as a main component is applied to the steel sheet and dried, and 100% nitrogen is applied.
In the atmosphere, the temperature was raised to 1200 ° C. at a temperature rising rate of 15 ° C./Hr, and after reaching 1200 ° C., the hydrogen was switched to 100% and the final annealing was carried out for 20 hours.

After the finish annealing, the obtained mirror-finished steel sheet was washed with water to remove the annealing separator, and used as a material for the next step. A commercially available alumina sol (solid component: 10% by weight): 100 parts by weight and metaboric acid: 2.5 parts by weight were sufficiently mixed and diluted with distilled water to obtain a coating solution. This was applied to the above steel plate with a roll coater, dried and gelled. The coating amount of coating solution is 3 g / m ^{2 as} dry weight.
(Per one side). This steel plate at 1000 ℃, 5
Baking was performed for 5 minutes in an atmosphere of hydrogen: 5% -nitrogen: 95%.

The coating film on the surface of the obtained steel sheet was peeled off and chemical analysis revealed that Al and B were the main components. Further, when X-ray diffraction was performed, a diffraction line corresponding to the Al-B-O composite oxide was obtained. Regarding the adhesion of the coating,
The following experiment was conducted. That is, the coated steel plate is 100
The film was wrapped around a mmφ roll bar and bent by an angle of 180 degrees, and the peeling state of the coating film on the inner surface (folded inside) was examined, and the area where the coating film was not peeled was displayed in% (hereinafter referred to as the adhesion test). Therefore, in the adhesion test, the smaller the peeled area, the better.

Although this test method does not have a sufficient physical explanation, it is used frequently because it corresponds relatively well to the peeling state of the coating film during the processing (slitting, punching, stress relief annealing, bending during iron core production, etc.) of electromagnetic steel sheets. Has been done. Table 2 shows the results of the adhesion test together with the magnetic properties. The magnetic properties are the result of performing magnetic subdivision processing with a laser after coating.

[0034]

[Table 2]

The amount of B in steel is 0.000 in terms of adhesion.
If it is 5% by weight or more, it is improved, but if B: more than 0.0060% by weight, the magnetic flux density (B ₈ ) is lowered and it is not effective. Although the Al-B oxide coating is shown in the above coating example, similar results were obtained with the phosphoric acid-chromic coating as shown in the examples. The B content in the hot rolled steel sheet is less than 0.0002% by weight () and 0.001.
The results of GDS analysis of the surface after 4% by weight () of finish annealing are shown in FIGS. 4 and 5. The vertical axis of both figures shows the existence intensity of each atom, and the horizontal axis shows the depth from the outermost surface, and 1 second is about 3
It is said to be equivalent to 00 to 400 angstroms.

The concentration of Si on the outermost surface is higher than that of Si, and considering the distribution of oxygen, this is SiO ₂ (silica).
Is judged. The mechanism by which the coating adheres well when there is a large amount of silica on the outermost surface of the steel sheet is not clear, but S that emerges from the steel
It is considered that i is oxidized corresponding to the unevenness on the metal surface and at the molecular level to form a SiO ₂ (silica) film having good adhesion, and the tension film formed on this silica is silica / It is considered that glass is formed at the interface of the tension film and adheres well.

In general, the mechanism of Si concentration on the outermost surface is SiO ₂ (silica) because Si in steel is oxidized on the outermost surface.
Therefore, it is explained that Si in the steel on the outermost surface is reduced and Si diffuses from the inside of the steel. B into steel
Addition promotes this phenomenon, but the reason is not clear.

Usually, the primary recrystallization annealing is carried out in a wet atmosphere in order to remove carbon: C in the steel, so that an oxide layer is formed on the surface of the steel sheet. As described above, when a material that does not form forsterite, such as alumina, is used as an annealing separating agent and finish annealing is performed to obtain a mirror-finished grain-oriented electrical steel sheet, this oxide layer deteriorates the mirror-finish degree. Further, it deteriorates the inhibitor and reduces the magnetic flux density (B ₈ ). As mentioned above, removal of the oxide layer was proposed as a solution. If there is no C in the cold rolled steel sheet, it is not necessary to perform the primary recrystallization annealing in a wet atmosphere. However, if C: less than 0.005% by weight, secondary recrystallization becomes unstable, and high magnetic flux density cannot be obtained even when secondary recrystallization is performed. So some carbon:
C is required in hot rolled steel.

The inventors of the present invention have investigated in detail the decarburization state of the material which has been mirror-finished during the finish annealing, and have found that it has been decarburized in the purification process. This is because while ordinary finish annealing using magnesia as an annealing separator produces a forsterite coating on the steel sheet surface and suppresses decarburization, there is no coating on the steel sheet surface, so the elements in the steel can be purified smoothly. It seems to progress. This is not limited to C,
Purification of S, N, etc. (reduction of element concentration in steel) is also performed smoothly.

In the case of carbon, it was found that decarbonization of several hundred ppm was performed before and after finish annealing. Therefore, even if several hundred ppm of carbon remains after the primary recrystallization annealing, several ppm after the final annealing.
Of carbon, which is an amount that does not cause problems such as aging of the steel sheet. As a result, during primary recrystallization annealing, it is not necessary to reduce (decarburize) carbon to a few ppm, the atmosphere dew point of the annealing can be lowered, and the oxide layer generated in the annealing step can be minimized. In such a case, a mirror-oriented grain-oriented electrical steel sheet can be obtained by applying an annealing separator and finish annealing without applying a means for removing an oxide film such as pickling.

In this case, naturally, it is advantageous that the carbon of the cold rolled sheet is low in carbon, and it is desirable to use a low carbon hot rolled silicon steel strip. The dew point of the annealing atmosphere during the primary recrystallization annealing is 40 ° C.
In the case of silicon steel, the temperature below is defined as an internal oxide layer is formed at a dew point of more than 40 ° C and the oxygen content of the steel sheet is rapidly increased, but a silica layer is formed on the surface at a dew point of 40 ° C or less to cause internal oxidation (steel sheet). Oxidation of internal Si) does not occur and the oxygen content of the steel sheet is suppressed. The inventors have annealed a 6 mil cold rolled sheet containing each amount of carbon at 830 ° C. for 90 seconds at each dew point, and measured the amount of carbon after decarburization annealing (primary recrystallization annealing) and after finish annealing. The results are shown in Table 3.

Thus, even if decarburization annealing (primary recrystallization annealing) is performed at a low dew point, the amount of carbon after finish annealing is reduced. On the other hand, the amount of oxygen increases with an increase in dew point, and the dew point during decarburization annealing (primary recrystallization annealing) is + 40 ° C. as a dew point that gives the amount of oxygen that can remain after pickling: 0.30 g / m ² or less. Below.

[0043]

[Table 3]

After the primary recrystallization annealing (decarburization annealing), the steel sheet from which the oxide layer has been removed by pickling or the steel sheet annealed by lowering the dew point of the primary recrystallization annealing (decarburization annealing) is annealed and separated. Agents are Al ₂ O ₃ (alumina), Si
O ₂ (silica), ZrO ₂ (zirconia), BaO (barrier), CaO (calcia), SrO (strontium oxide) and forsterite (Mg ₂ SiO ₄ ) are used as main components, and these may be used alone or You may mix and use 2 or more types. Further, addition of a small amount of a rust preventive or the like to these main components does not cause any problem. The method for applying the annealing separator to the steel sheet may be any of electrostatic coating, water slurry coating, organic solvent slurry coating, powder spray coating, etc., but in the case of water slurry coating, a substance that easily reacts with water, that is, CaO, BaO and SrO are inconvenient.

Further, in the case of using a chlorine compound of Bi for mirror-finishing, an ordinary annealing separator mainly composed of MgO: 100
BiOCl (bismuth oxychloride), BiCl
A chlorine compound of Bi such as ₃ (bismuth chloride) and BiCl may be added as a chlorine component in an amount of 0.2 to 15 parts by weight. It is presumed that iron: Fe becomes FeCl _{2 by} the etching action of chlorine, evaporates, and SiO ₂ (silica) is also exfoliated (scattered) with it, and the oxide layer of the steel sheet disappears.

Other implementation conditions will be described below.
The oxide layer formed on the surface of the steel sheet during the primary recrystallization annealing affects the following two during the finish annealing. That is, as described above, the inhibitor strength is weakened, a sufficient magnetic flux density cannot be obtained, the surface smoothness of the product is insufficient, the magnetic characteristics are adversely affected, and the ultimate magnetic characteristics are difficult to be obtained. Therefore, in order to obtain the ultimate magnetic characteristics, it is desirable to remove the oxide layer formed on the surface of the steel sheet during the primary recrystallization annealing or to keep the oxygen content below a certain value. As a method of removing, mechanical polishing, for example, brush polishing, sandpaper polishing, grinding, etc. are effective for this purpose, but various industrial difficulties are involved.

The present inventors have found that the method by pickling is extremely easy and effective. This is because a continuous pickling line for hot-rolled steel strips or steel plates has already been put to practical use. As the pickling solution (pickling solution), mineral acids such as hydrochloric acid, sulfuric acid and nitric acid are effective, but the oxide layer formed on the surface of the steel sheet is mainly an oxide mainly composed of SiO _2. It is difficult to pickle with only mineral acids such as hydrochloric acid, sulfuric acid and nitric acid. When hydrofluoric acid is mixed with these acids, the oxide layer can be removed very efficiently, that is, at high speed. In addition,
It is also effective to combine physical methods such as pickling and mechanical polishing such as brush polishing. Furthermore, in order to suppress the amount of oxygen, the dew point at the time of primary recrystallization is set to 40 ° C. or lower, so that the step of removing the oxide layer can be omitted.

Further, it is effective to strengthen the inhibitor by performing a nitriding treatment with ammonia after the primary recrystallization annealing and before the finish annealing. This is because the inhibitor strength at the completion of primary recrystallization is not sufficient for secondary recrystallization,
It is also utilized when the partial pressure of nitrogen during finish annealing is increased to strengthen the inhibitor, or even when deterioration is prevented, sufficient inhibitor cannot be secured during secondary recrystallization. Improve.

In order to secure an inhibitor necessary for the progress of secondary recrystallization, nitrogen gas was added to the annealing atmosphere at a temperature of 5 at the time of heating.
% Or more and 95% or less is desirable, but hydrogen gas 10
0% is fine. If the nitrogen gas content is less than 5%, the effect of strengthening the inhibitor or preventing deterioration is small. If nitride is not the inhibitor, the effect of nitrogen partial pressure is weak.

The neutral or reducing atmosphere means
It refers to a gas composition which is neutral or reductive with respect to the redox of silicon, which is one kind or a mixture of two or more kinds of inert gases such as nitrogen, oxygen, water, hydrogen and argon. Generally, nitrogen and hydrogen gas are used in the finish annealing of the electromagnetic steel sheet, and therefore the combination of these gases is 0% to 100%. There is no problem even if an inert gas such as argon or helium is mixed with the combination of both gases in order to adjust the nitrogen partial pressure. A neutral or reducing atmosphere is used to prevent reduction of Al in steel and to oxidize silicon in steel to not form SiO ₂ on the surface.
This is because it does not increase.

After the completion of the secondary recrystallization, the hydrogen concentration was increased to 120% in order to completely purify and mirror-finish the surface of the steel sheet.
Holding at around 0 ° C for several hours is extremely effective.
The higher the rate of temperature rise to the temperature at which secondary recrystallization is possible in the finish annealing, the more favorable the less inhibitor deterioration. When the temperature rising rate is less than 15 ° C./Hr, the inhibitor was remarkably deteriorated, and the inhibitor required for the secondary recrystallization was not sufficiently secured, and sufficient secondary recrystallization was not obtained.

From the viewpoint of obtaining a high magnetic flux density, which is one of the gist of the present invention, a heating rate of 50 ° C./Hr or more is desirable. The coating solution used as the coating solution for forming the tension film is a phosphoric acid-chromic acid type solution, for example, JP-A-61-41.
First phosphate as disclosed in Japanese Patent No. 778: 100 parts by weight, ultrafine particles of colloidal silica having a particle size of 8 nm (80 angstroms) or less are used as SiO ₂ , and 20 to ₈ are used.
There are solutions such as 0 parts by weight and 10 to 48 parts by weight of at least one of chromic anhydride and chromate as CrO ₃ , and here, coating containing silicic acid (SiO ₂ ), phosphoric acid and chromic acid. It refers to a solution and is not particularly limited.

The coating component is generally amorphous,
It is believed that silicic acid, phosphoric acid, and chromic acid form a complex salt. The effect of the mirror-oriented electrical steel sheet of the present invention is also effective in a solution containing no chromic acid, for example, a solution containing colloidal silica and phosphate described in JP-B-57-9631. In particular, a tension coating formed from a solution containing alumina sol and boric acid as a main component exerts a high tensile strength on the steel sheet in terms of thermal expansion and Young's modulus, and therefore has a remarkable iron loss reducing effect.

The embodiments of the present invention will be described below. Si:
2.0-4.8% by weight, B: 0.0005-0.006
0% by weight, C: 0.005 to 0.12% by weight, acid-soluble Al: 0.008 to 0.06% by weight, other Mn, S,
Se, Sb, P, Sn, Bi, Nb, Ti, Mo, Cu
The molten steel added with one or two or more of these is subjected to a normal process or continuous casting to obtain a hot rolled steel sheet or a hot rolled steel strip. This hot rolled steel sheet or hot rolled steel strip is 75
Annealing for improving the magnetic flux density is performed in a temperature range of 0 to 1200 ° C. for 30 seconds to 30 minutes. Subsequently, these hot rolled steel sheets or hot rolled steel strips are cold rolled.

The cold rolling is carried out at a final cold rolling rate of 80% or more, as disclosed in Japanese Patent Publication No. 40-15644. The material after cold rolling is subjected to primary recrystallization annealing in a temperature range of 750 to 900 ° C. in a wet atmosphere to remove carbon in steel. At this time, an oxide layer is formed on the surface of the steel sheet along with decarburization and primary recrystallization. This oxide layer forms a so-called internal oxide layer, depending on the degree of water content (usually represented by dew point) in a wet atmosphere, that is, a water-containing atmosphere, in which SiO ₂ mainly exists as an oxide. To do. Note that 80 to 90% or more of the oxygen content of the oxide formed during the primary recrystallization annealing is in the form of SiO ₂ .

It is extremely effective to improve the magnetic flux density by subjecting the steel sheet to a nitriding treatment with ammonia for strengthening the inhibitor. Further, the oxide layer on the surface of the steel sheet or steel strip after the primary recrystallization is removed. The oxide film can be removed by a physical or chemical method as described above, but is generally pickled. A primary recrystallized steel sheet is produced in which the dew point of the primary recrystallization annealing (decarburization annealing) is annealed at 40 ° C. or lower and the amount of the oxide layer on the surface of the steel sheet is suppressed within a certain range.

Each of these and the primary recrystallized plate are finished by applying an annealing separator mainly composed of MgO containing a chlorine compound of Bi and an annealing separator which does not form forsterite such as Al ₂ O _{3 and the} like. Placed in an annealing furnace. The atmosphere at the time of raising the temperature in the finish annealing is neutral or reducing, and it is no problem to mix an inert gas such as argon or helium for adjusting the partial pressure of nitrogen. After the secondary recrystallization is completed, 100% hydrogen is used for high temperature (about 12
00 ° C) is maintained. After finishing annealing, a magnetic domain subdivision process such as laser beam irradiation is performed, and a tension film application process is further performed.

[0058]

【Example】

Example 1 Si: 3.25% by weight, acid-soluble Al: 0.028% by weight, N: 0.008% by weight, Mn: 0.13% by weight,
S: 0.008% by weight, B: 0.0002% by weight or less, 0.0014% by weight, C: 0.05% by weight, silicon hot-rolled steel strip made of balance Fe and unavoidable impurities is 110
After annealing at 0 ° C. for 2 minutes, it was cold rolled to a thickness of 0.225 mm. These cold-rolled sheets were annealed at 820 ° C. for 2 minutes in an annealing furnace in a wet atmosphere for double decarburization, and primary recrystallization was performed. Then, it was pickled with a 0.5% hydrofluoric acid-5% sulfuric acid mixed solution. The amount of oxygen of the steel sheet after the pickling is 0.11 g /
It was m ² (per side).

Al ₂ O ₃ (alumina) was electrostatically applied to these two materials, and the temperature was increased to 1200 ° C. with 75% N ₂ -25.
In a% H ₂ atmosphere, the temperature was raised while maintaining the temperature rising rate of 15 ° C./Hr, and after reaching 1200 ° C., 100% hydrogen was obtained and the temperature was maintained for 20 hours. After the finish annealing was finished, it was washed with water and irradiated with a laser beam to subdivide the magnetic domains. On this steel plate, colloidal silica (SiO ₂ : 20% by weight aqueous dispersion):
100 parts by weight, aluminum phosphate (Al (H ₂ P
O ₄ ) 3: 50% by weight aqueous solution): 75 parts by weight, sulfate:
A coating solution of 10 parts by weight and 100 parts by weight of water was applied at a dry weight of 4 g / m ^{2 and} baked at 600 ° C. for 2 minutes.
The characteristics of the obtained product are shown in Table 4.

[0060]

[Table 4]

Example 2 In order to stabilize the secondary recrystallization after the primary recrystallization annealing in Example 1, a nitriding treatment was performed in an ammonia atmosphere, the total nitrogen content was set to 200 ppm, and the inhibitor was strengthened. Then, the same treatment as in Example 1 was performed. The characteristics of the obtained product are as shown in Table 5. The symbol of the amount of B in the hot-rolled steel sheet is the same as in Example 1.

[0062]

[Table 5]

Example 3 Si: 3.30% by weight, acid-soluble Al: 0.029% by weight, N: 0.008% by weight, Mn: 0.14% by weight,
S: 0.008% by weight, B: 0.0015% by weight, C:
A hot-rolled silicon steel strip consisting of 0.05% by weight, balance Fe and unavoidable impurities was annealed at 1100 ° C. for 2 minutes and then cold-rolled to a thickness of 0.155 mm. These cold-rolled sheets were annealed at 820 ° C. for 2 minutes in an annealing furnace in a wet atmosphere for double decarburization, and primary recrystallization was performed. Next, in order to stabilize the secondary recrystallization, nitriding treatment is performed in an ammonia atmosphere,
The total amount of nitrogen was set to 230ppm and the inhibitor was strengthened.

After that, it was pickled with a mixed solution of 0.5% hydrofluoric acid and 5% sulfuric acid. Oxygen content of the steel sheet by the pickling is 0.09g
/ M ² (per surface). A for these two materials
electrostatically coated with l ₂ O ₃ (alumina), up to 1200 ° C., in a 100% H ₂ atmosphere, up to 1200 ° C., 75%
The temperature was raised in an N ₂ -25% H ₂ atmosphere while maintaining the temperature rising rate of 15 ° C./Hr, and after reaching 1200 ° C., 100% hydrogen was obtained and the temperature was maintained for 20 hours. After the finish annealing was finished, it was washed with water and irradiated with a laser beam to subdivide the magnetic domains.

Alumina sol (solid component: 1
0% by weight aqueous solution): 100 parts by weight, metaboric acid: 5 parts by weight, and FeOOH submicron fine powder: 0.1 parts by weight are thoroughly mixed and diluted with distilled water to form a coating solution,
This was applied at a dry weight of 3.5 g / m ^{2 and} baked at 1000 ° C. for 2 minutes. The characteristics of the obtained product are as shown in Table 6. It can be seen that mixing nitrogen in the finish annealing atmosphere improves the magnetic flux density (B ₈ ) and reduces the iron loss.

[0066]

[Table 6]

Example 4 Si: 3.25% by weight, acid-soluble Al: 0.028% by weight, N: 0.008% by weight, Mn: 0.14% by weight,
S: 0.008% by weight, B: 0.0003% by weight or less, 0.0014% by weight, C: 0.055% by weight, silicon hot-rolled steel strip consisting of balance Fe and unavoidable impurities 11
After annealing at 00 ° C. for 2 minutes, it was cold rolled to a thickness of 0.225 mm.

These cold-rolled sheets were annealed at 820 ° C. for 2 minutes in an annealing furnace in a wet atmosphere to also serve as decarburization, and primary recrystallization was performed. For these two materials, MgO (magnesia): 100 parts, BiOCl (bismuth oxychloride):
An annealing separator consisting of 3 parts was applied and dried in a water slurry state, and the temperature was raised to 1200 ° C. in a 75% N ₂ -25% H ₂ atmosphere while maintaining a temperature rising rate of 15 ° C./Hr.
After reaching 0 ° C, the temperature was adjusted to 100% hydrogen and the temperature was maintained for 20 hours.

After finishing annealing, washing was performed and irradiation with a laser beam was performed to subdivide magnetic domains. On this steel plate, colloidal silica (SiO ₂ : 20% by weight aqueous dispersion): 100
Parts by weight, aluminum phosphate (Al (H ₂ PO ₄ ) 3:
50% by weight aqueous solution): 75 parts by weight, sulfate: 10 parts, and water: 100 parts by weight of a coating solution of 4 g / dry weight.
m ^{2 was} applied and baked at 600 ° C. for 2 minutes. The characteristics of the obtained product are shown in Table 7.

[0070]

[Table 7]

Example 5 Si: 3.25% by weight, acid-soluble Al: 0.029% by weight, N: 0.008% by weight, Mn: 0.13% by weight,
S: 0.008% by weight, B: 0.0003% by weight or less, 0.0026% by weight, C: 0.05% by weight, the hot-rolled silicon steel strip made of balance Fe and unavoidable impurities is 110
After annealing at 0 ° C. for 2 minutes, it was cold rolled to a thickness of 0.225 mm.

These cold-rolled sheets had a dew point of 0 ° C. and a hydrogen content of 75%.
It was annealed at 820 ° C. for 2 minutes in the annealing furnace having the atmosphere described above to perform primary recrystallization. These two materials in Al ₂ O ₃ (alumina) was applied electrostatically, to 1200 ℃, 75% N ₂ -25
In a% H ₂ atmosphere, the temperature was raised while maintaining the temperature rising rate of 15 ° C./Hr, and after reaching 1200 ° C., 100% hydrogen was obtained and the temperature was maintained for 20 hours.

After finishing annealing, washing was carried out and irradiation with a laser beam was carried out to subdivide the magnetic domains. On this steel plate, colloidal silica (SiO ₂ : 20% by weight aqueous dispersion): 100
Parts by weight, aluminum phosphate (Al (H ₂ PO ₄ ) 3:
50 wt% aqueous solution): 75 parts by weight, sulfate: 10 parts, and water: 100 parts by weight.
It was applied at g / m ^{2 and} baked at 700 ° C. for 2 minutes. The characteristics of the obtained product are as shown in Table 8.

[0074]

[Table 8]

[0075]

According to the present invention, a grain-oriented electrical steel sheet having a high magnetic flux density and small irregularities on the surface of the steel sheet (which is a mirror surface) which is a factor that obstructs magnetic properties can be easily obtained, and magnetic domains for laser beam irradiation treatment or the like can be obtained. A magnetic material with extremely low iron loss was provided by the tension coating treatment with fine segmentation and good adhesion. In the production of this grain-oriented electrical steel sheet, since the mirror finishing treatment of the steel sheet is performed in a normal finish annealing furnace, it is extremely easy,
The industrial value is enormous.

[Brief description of drawings]

FIG. 1 is a graph showing changes in an inhibitor (acid-soluble Al) of a steel sheet during finish annealing.

FIG. 2 Alumina is applied as an annealing separator to a material having an oxygen content of 0.72 g / m ² (one side) by pickling,
The photograph which observed the surface of the grain-oriented electrical steel sheet which carried out finish annealing with the SEM (scanning electron microscope).

FIG. 3 Alumina is applied as an annealing separator to a material having an oxygen content of 0.17 g / m ² (one side) by pickling,
The photograph which observed the surface of the grain-oriented electrical steel sheet which carried out finish annealing with the SEM (scanning electron microscope).

FIG. 4 is a graph showing the results of surface GDS analysis after finish annealing in which the B content in the hot rolled steel sheet is less than 0.0002% by weight.

FIG. 5 is a graph showing the results of surface GDS analysis after finish annealing in which the amount of B in the hot rolled steel sheet is 0.0014% by weight.

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[Procedure amendment]

[Submission date] November 4, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

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[Figure 3]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location C22C 38/02 (72) Inventor Yozo Suga 20-1 Shintomi, Futtsu City Nippon Steel Corporation Technology Inside the Development Headquarters (72) Inventor Hiroaki Masui 20-1 Shintomi, Futtsu City Nippon Steel Co., Ltd. Technical Development Headquarters (72) Inventor Katsuro Kuroki 1-1 Hibatacho, Tobata-ku, Kitakyushu Nippon Steel Co., Ltd. Yawata Works (72) Inventor Shuichi Yamazaki 20-1 Shintomi, Futtsu City Nippon Steel Co., Ltd. Technical Development Headquarters (72) Inventor Hiroyasu Fujii 20-1 Shintomi Futtsu City Nippon Steel Co., Ltd. Technical development In headquarters

Claims (12)

[Claims] 1. Si: 2.0 to 4.8% by weight, acid-soluble Al: 0.008 to 0.06% by weight, N ≦ 0.010% by weight, B: 0.0005 to 0.0060% by weight , C: 0.005 to 0.12% by weight, a silicon steel material consisting of the balance Fe and unavoidable impurities is hot-rolled to form a silicon steel strip, which is annealed if necessary and then sandwiched once or in between. After performing cold rolling two or more times to obtain the final plate thickness and then performing primary recrystallization annealing, the oxide layer formed on the surface of the steel sheet during primary recrystallization annealing is removed as necessary, and an annealing separator is applied. A method for producing a mirror-oriented silicon steel sheet having good coating adhesion, which comprises performing finish annealing in a neutral or reducing atmosphere and then applying a tension coating. 2. A silicon steel material is hot-rolled into a silicon steel strip, which is annealed as required, and then cold-rolled once or twice or more with intermediate annealing to obtain a final plate thickness. After performing the primary recrystallization annealing, the oxide layer formed on the surface of the steel sheet during the primary recrystallization annealing is removed to remove Al ₂ O ₃ , SiO ₂ , ZrO.
₂ , 1 of BaO, CaO, SrO and forsterite
2. A coating film according to claim 1, characterized in that an annealing separator having two or more kinds as a main component is applied to the steel sheet, finish annealing is performed in a neutral or reducing atmosphere, and then a tension coating film is applied. A method for manufacturing a mirror-oriented silicon steel sheet having good adhesion. 3. A silicon steel material is hot-rolled into a silicon steel strip, which is annealed as required, and then cold-rolled once or twice or more with intermediate annealing to obtain a final sheet thickness, and then, After performing the primary recrystallization annealing, nitriding treatment with ammonia is performed to remove the oxide layer generated on the surface of the steel sheet during the primary recrystallization annealing, and Al ₂ O ₃ , SiO ₂ , ZrO ₂ , BaO, Ca
A feature that an annealing separator containing at least one of O, SrO and forsterite as a main component is applied to the steel sheet, finish annealing is performed in a neutral or reducing atmosphere, and then a tension film is applied. The method for producing a mirror-oriented silicon steel sheet having good coating adhesion according to claim 1. 4. A silicon steel material is hot-rolled into a silicon steel strip, which is annealed as required, and then cold-rolled once or twice or more with intermediate annealing to obtain a final plate thickness, and then, The primary recrystallization annealing is performed, then an annealing separator containing a chlorine compound of Bi is applied, finish annealing is performed in a neutral or reducing atmosphere, and then a tension film is applied. A method for producing a mirror-oriented silicon steel sheet having good coating adhesion. 5. A silicon steel material is hot-rolled into a silicon steel strip, which is annealed as required, and then cold-rolled once or twice or more with intermediate annealing to obtain a final sheet thickness, and then, After performing primary recrystallization annealing, nitriding treatment with ammonia is performed, and then an annealing separator containing a chlorine compound of Bi is applied, finish annealing is performed in a neutral or reducing atmosphere, and then a tension film is applied. The method for producing a mirror-oriented silicon steel sheet having good coating adhesion according to claim 1. 6. The method for producing a specular grain oriented silicon steel sheet with good coating adhesion according to claim 1, wherein the dew point during primary recrystallization annealing is 40 ° C. or lower. 7. The mirror surface direction with good coating adhesion according to claim 1, wherein the amount of oxygen on the surface of the steel sheet after removal of the oxide layer is 0.30 g / m ² or less per one surface of the steel sheet. For manufacturing a high-quality silicon steel sheet. 8. The method for producing a mirror-oriented silicon steel sheet with good coating adhesion according to claim 1, 2, 3 or 7, wherein the method for removing the oxide layer on the surface of the steel sheet is pickling. 9. The mirror directionality with good film adhesion according to claim 1, 2, 3 or 7, wherein the method for removing the oxide layer on the surface of the steel sheet is pickling with an acid mixed with hydrofluoric acid. Manufacturing method of silicon steel sheet. 10. A mirror surface direction with good film adhesion according to any one of claims 1 to 9, characterized in that a tension film composed of components mainly composed of silicate, phosphate and chromate is provided. For manufacturing a high-quality silicon steel sheet. 11. A mirror-oriented silicon steel sheet with good coating adhesion according to claim 1, wherein a tension coating composed of a component mainly composed of aluminum and boron oxide is provided. Production method. 12. N ₂ in an atmosphere at the time of temperature increase during finish annealing.
% Or more, The method for producing a mirror-oriented silicon steel sheet having good coating adhesion according to any one of claims 1 to 11.