JPH08165525A - Production of grain-oriented silicon steel sheet excellent in good glass coating and extremely good in magnetic characteristic - Google Patents

Abstract

PURPOSE: To obtain a magnetic steel sheet excellent in uniform glass film and magnetic characteristic by coating separation agent containing a specific chlorinated compound in a specific quantity, at the time of producing a grain-oriented silicon steel sheet from a slab for silicon steel sheet. CONSTITUTION: The slab for grain-oriented silicon steel sheet containing 2.0-4.5wt.% Si is treated with a well-known method to make the cold-rolled sheet having the last sheet thickness, and the separation agent for annealing is coated, and after executing the last finish annealing, insulation coating agent is coated, and a heat flattening is executed to obtain the grain-oriented electrical steel sheet. In this method, the separation agent for annealing adjusting Cl in this agent to 0.01-0.06% by adding chlorinated compound of a element selected from among H, Li, Sr, Ti, Nb, Ta, Cr, Mo, W, Pb. Bi and B at the producing process and/or slurry adjusting step of this agent to MgO containing 0.05-1.2% S, is used at >=20m<2> /g in the coating process of the separation agent for annealing. Further, this separation agent for annealing is coated so that the chlorinated compound per 1m<2> of steel sheet becomes (4-48)×10<-4> g/m<2> as Cl.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the production of a grain-oriented electrical steel sheet by forming a glass coating film having a uniform and excellent coating performance in the final finishing annealing step and at the same time providing a grain-oriented electromagnetic material for obtaining excellent magnetic properties. The present invention relates to a method for manufacturing a steel plate.

[0002]

2. Description of the Related Art Usually, grain-oriented electrical steel sheets have Si2.5-
A raw material slab containing 4.0% is hot-rolled and annealed and cold-rolled once or twice with an intermediate annealing to obtain a final plate thickness. Then, in a continuous annealing furnace, H ₂ or N ₂ + H ₂
Decarburization annealing is performed by controlling P H ₂ O / P H ₂ in the atmosphere, and decarburization, primary recrystallization, and oxide layer forming treatment containing SiO ₂ as a main component are performed. After that, an annealing separating agent containing MgO as a main component is applied in a slurry form to a steel plate by a coating roll or the like, dried, wound on a coil, and finally finished annealed, and usually an insulating coating agent treatment and heat flattening are performed. The final product.

In this grain-oriented electrical steel sheet, a (110) <001> crystal having a <001> axis grows preferentially by high temperature secondary recrystallization, and Al dispersed as an inhibitor in the steel.
It is considered that the (110) <001> crystal grows preferentially because it erodes other crystals whose growth is suppressed by N, MnS, and the like. Therefore, in order to produce an excellent grain-oriented electrical steel sheet, Inhibitor A in steel is used.
It is important to control the dispersed state of 1N, MnS, etc. and their decomposition. In particular, in the final finish annealing, the inhibitor is affected by the oxide film on the surface of the steel sheet formed by the decarburization annealing, the annealing separator, the heat cycle in the final finishing annealing, and the atmospheric gas conditions.

Among these, the reactivity of MgO as a glass film forming agent used as an annealing separator has a great influence on the behavior of the inhibitor through the formation of the glass film. This is because the physical properties such as the purity, activity, and particle size of the MgO particles are changed in the decarboxylation film during the temperature rising process in the final annealing, the glass film formation reaction initiation temperature, the growth rate, and the atmospheric oxidation between the coil plates. This is because the stability of the inhibitor in steel is affected by the formation state of the glass film, etc.

The glass film forming reaction in the finish annealing is carried out by using MgO as an annealing separator and SiO formed by decarburizing annealing.
It reacts with the oxide film mainly composed of ₂ to form a forsterite film usually called a glass film (2MgO + SiO ₂ → Mg
₂ SiO ₄ ). At this time, A as an inhibitor in steel
When 1N is used, a compound having a spinel structure composed of Al ₂ O ₃ and MgO, SiO ₂ or the like is formed immediately below the forsterite coating.

In the formation of this glass film, the reaction between MgO and SiO ₂ does not occur in a pure water system unless the temperature is close to 1600 ° C., and the properties of the oxide film (components, formation state) and finish annealing conditions are controlled ( Heat cycle, atmospheric gas) and how to control impurities such as particle size, particle shape, surface condition, and activity as properties of annealing separator, how to make uniform glass film formation from low temperature in finish annealing process. Is an important key for obtaining excellent glass coating and good magnetic properties. Since the influence of the annealing separator MgO on the glass coating and magnetic properties, which are important in determining the commercial value of grain-oriented electrical steel,
Improvement of O quality has become an important issue in the grain-oriented electrical steel sheet manufacturing technology.

The MgO used as the annealing separator is generally made of MgCl ₂ or seawater as a raw material, and firstly Ca
The Mg (OH) ₂ crystal is adjusted by the reaction with (OH) ₂ and is made into MgO once by compression washing or the like for the purpose of adjusting the purity or the like, or as MgO by firing twice or more between washing and crystal adjustment. Accordingly, the product is prepared by adjusting the particle size by crushing, classifying, etc. Among the properties of MgO, the factors that influence the formation of the glass film and the stability of the inhibitor and the magnetic properties in relation to this are mainly the purity of MgO, the particle size, the activity and the adhesion to the steel sheet. However, when it is applied to a steel sheet, there are a hydration progress degree, a dispersion state of particles in an aqueous slurry, an application amount, and the like. Therefore, it is important to optimize these conditions in order to obtain a grain-oriented electrical steel sheet having an excellent glass coating and magnetic properties.

As mentioned above, MgO is usually applied to a steel sheet in the form of a slurry by suspending it in water together with a small amount of an additive to be added as a reaction accelerator, if necessary. At this time, M
Depending on the production conditions of gO, for example, in the case of high activity, depending on the mixing and stirring conditions with water, a hydration reaction of MgO → Mg (OH) ₂ occurs, and as a result of bringing water into the coil (between plates), There is a problem that the dew point is increased and the atmosphere condition is made non-uniform in the coil longitudinal direction and width direction. For this reason, in the final annealing temperature rising process, non-uniform, excessive additional oxidation occurs, and scales, gas marks, pinholes,
Causes severe film defects such as discoloration. However, as a means for solving the problem due to the high hydration, a method by high temperature firing is generally adopted.

As a disclosure of this method, for example,
There is JP-A-55-73823. As described above, the low activity MgO obtained by increasing the firing temperature has a drawback that the activity (reactivity) and the adhesion are reduced although the hydration property is reduced. Further, JP-A-62-156226 proposes a method of activating the outermost surface layer of MgO particles. In this method, only the outermost surface layer of MgO burned at high temperature is treated in the gas phase to form a hydrated layer.
This has been shown to significantly improve the glass coating and magnetic properties.

Further, as a technique for improving the glass coating and the magnetism by the additive in the annealing separator, Japanese Patent Publication No. 2820/1985 has been proposed.
In the publication, 0.02 to 100 parts by weight of MgO: 100 parts by weight of one or more kinds of chlorides of Sb, Sr, Ti and Zr.
A method of adding 1.5 parts by weight has been proposed. As a result, the additive compound causes enrichment and densification of the oxide layer component on the surface of the steel sheet with SiO ₂ and suppresses additional oxidation and promotes the reaction during finish annealing, resulting in excellent iron loss characteristics and glass coating. Is. Moreover, JP-A-3-12
As disclosed in Japanese Patent Laid-Open No. 03766, if a metal chloride selected from Mg, Na, K and Ca is added to MgO as a technique for improving the chloride addition technique as described above, magnetic properties can be obtained without the combined use of antimony sulfate and sodium metasilicate. It is shown that the improvement effect of is obtained.

As described above, by improving these MgO properties, the glass film forming reaction is improved and the effect is obtained. However, the film properties and magnetic properties may become unstable depending on the steel composition, decarburization annealing conditions, and final finish annealing conditions, which is not a sufficient technique yet, and further technical improvements are desired. .

[0012]

DISCLOSURE OF THE INVENTION The present inventors have carried out enormous research and experiments on a method for improving the reactivity of low hydrated MgO in order to achieve an annealing separator having low hydration and high reactivity. I examined it. As a result, when applying an annealing separator having a chlorine content adjusted to a predetermined amount by a chlorine compound in the manufacturing process of MgO having a small particle size and containing a predetermined amount of S and / or in a slurry preparation step, a chlorine basis weight per steel plate surface area is applied. It has been found that by applying the glass coating so that the amount thereof becomes a predetermined amount, the reactivity of the glass coating film is good, and a grain-oriented electrical steel sheet having extremely good coating properties and magnetic properties can be obtained.

[0013]

The present invention has the following features as a solution of MgO used in an annealing separator in the prior art. (1) A grain-oriented electrical steel sheet material containing Si 2.5 to 4.0% by weight (hereinafter abbreviated as%) is treated by a known method to obtain a cold-rolled sheet having a final thickness, and decarburized and annealed to obtain SiO ₂ main In the method for producing a grain-oriented electrical steel sheet, which comprises forming an oxide film of a component, applying an annealing separator, performing final finishing annealing, then applying an insulating film agent and performing heat flattening, wherein the annealing is performed. The specific surface area is 20m ^{2 in the} process of applying the separating agent.
/ G or more, the amount of S is 0.05 to 1.2% MgO in M
H, Li, Sr, Ti, Nb, Ta, Cr, Mo, in the manufacturing process of gO and / or the slurry preparation step of the annealing separator.
W, Pb, Bi, chlorine per steel sheet 1 m ² the adjusted annealing separator so as Cl amount to 0.01 to 0.06% of the chlorine compounds in the annealing separator with the addition of selected from among B Manufacture of grain-oriented electrical steel sheet having a uniform and excellent glass coating, which is characterized by being applied so that the amount of the compound is Cl in the range of ( ^{4 to} 48) × 10 ⁻⁴ g / m ^2. Method.

(2) In the method described in (1), P H ₂ of the atmospheric gas up to 800 ° C. at the time of temperature rise in finish annealing
A method for producing a grain-oriented electrical steel sheet, wherein a glass coating film is uniform and excellent in that O / P H ₂ is 0.25 or less and is excellent, and magnetic properties are extremely good. As a result, we have succeeded in improving the reactivity by the MgO surface hydration layer which could not be realized by the conventional technology, and succeeded in developing the technology that surpasses the conventional chloride addition technology. In other words, we succeeded in obtaining a grain-oriented electrical steel sheet in which the glass coating is uniform under a wide range of finish annealing conditions and the magnetic characteristics are good over the entire surface and the entire length of the coil.

In applying the present invention, as a starting material, a silicon steel slab containing Si 2.5 to 4.0% is hot-rolled by a known method, and cold-rolled once or twice with annealing.
Final plate thickness, followed by decarburization annealing to form SiO _{2 on the} surface
A so-called decarburized annealed plate having an oxide film containing as a main component is used. On this steel sheet, MgO whose chlorine content is adjusted to a minute amount by the specific chlorine or chlorine compound is uniformly finely dispersed as a slurry, and then applied on a continuous line with a coating roll or the like so that the amount of chlorine per surface area of the steel sheet is constant. Then, it is dried at a temperature of about 150 to 400 ° C. (plate temperature) and wound on a coil. At this time, the annealing separator MgO includes an oxide,
Boron compounds, sulfur compounds, nitrogen compounds, etc. are added and blended according to the steel composition and processing conditions.

The coil thus treated is subjected to final finishing annealing in a batch type or continuous type furnace 11
A high temperature treatment such as 50 to 1200 ° C. × 20 Hr and a long time treatment are performed, and the glass film formation, the secondary recrystallization and the purification are simultaneously performed. In the grain-oriented electrical steel sheet, the time, amount, state of formation and the like of the glass coating at this time are the inhibitor A.
As a result of influencing the decomposition rate of 1N, MnS, etc., and affecting the quality, tension or purification reaction of the glass coating, the glass coating characteristics and magnetic characteristics of the product are influenced.

The coil treated with glass in this manner after forming a glass film is washed with water to remove the excess annealing separator in a continuous line, lightly pickled and then coated with an insulating film agent.
Heat flattening is performed to combine the baking, shape correction, and strain relief annealing to obtain the final product. At this time, grain-oriented electrical steel sheets have a large effect of improving iron loss due to coating tension, magnetostriction, etc., especially in high magnetic flux density materials, so in order to further reinforce the tension effect of the glass coating formed by finish annealing, insulating coating component A tensioning type is applied as the above.

As the tension coating agent, 130 to 200 parts by weight of one or more phosphates such as Al, Mg and Ca and chromic acid and chromate are added to 100 parts by weight of colloidal silica in solid content. It is preferable to use one or two or more dichromates as CrO _{3 in an amount} of 12 to 40 parts by weight in order to obtain a high-strength coating economically. After this, when further improving iron loss, laser, tooth profile roll, etching,
The magnetic domain subdivision processing is performed by controlling the intervals and depths in a linear shape or in a dot shape in a direction substantially perpendicular to the rolling direction by local plating or the like, and processing strains, flaws, plating layers and the like.

Next, the reasons for limitation of the present invention will be described. First, as MgO applied to the present invention, the specific surface area of MgO is 20 m ² / g or more as measured by the BET method.
In the present invention, the amount of chlorine due to the chlorine compound has the main effect of improving the reactivity, but the area of the particles is also important in relation to the MgO particle size, porosity, particle shape and the like. 20 m ² / g
When the amount is less than the above, it is difficult to obtain a remarkable effect of improving reactivity even with the component adjusting technique of the present invention. The larger the specific surface area is, the more preferable it is, but it is inevitable that the change with time in the use stage of MgO cannot be avoided, and it is difficult to suppress the increase of hydrated water in the slurry preparation stage.

In this connection, the composition according to the invention comprises 10
If it is 0 m ² / g or more, peroxide-like shimofuri, gas marks, scales, etc., which are considered to be overreacted, may occur, so the preferred range is 20 to 100 m ² / g.
Secondly, the amount of S in MgO is limited because it affects the magnetic properties and the glass coating properties. S penetrates into the surface of the steel sheet during the temperature rise in finish annealing, thereby suppressing the penetration of excess N from the atmosphere and preventing the occurrence of pinhole-like film defects during denitrification.

Further, it prevents the removal of S from sulfides such as MnS and brings about the reinforcing effect of the inhibitor. 0.05%
If it is less than the above, the effect of such excess nitrogen cannot be prevented. Further, it is limited because it does not bring about the reinforcing effect of the inhibitor. On the other hand, if it exceeds 1.2%, the effect against them is obtained, but the etching effect of the glass film due to excessive S at high temperature occurs, and in an extreme case, the effect of MnS is excessively strengthened to cause secondary recrystallization. May be generated and fine particles may be generated, and both magnetic properties and coating properties deteriorate rather than being limited.

When the amount of chlorine is to be adjusted in the MgO production process, the chlorine compounds added as the chlorine source are H and L.
i, Sr, Ti, Nb, Ta, Cr, Mo, W, Pb,
As a firing condition, one or more chlorine compounds selected from Bi and B are added, and the chlorine compound after final firing has a chlorine content of 0.010 to 0.06%. The temperature, the time, the atmosphere, the amount of the raw material charged in the furnace, the stirring conditions in the firing stage, etc. are controlled.

When the amount of chlorine is adjusted in the stage of adjusting the slurry after firing MgO, H, Li, Sr, Ti, N
One or more chlorine compounds of b, Ta, Cr, Mo, W, Pb, Bi and B are added per 100 parts by weight of MgO.
The mixture is stirred and dispersed at the same time as other additives so that the chlorine content in the annealing separator is 0.01 to 0.06% to form a slurry.
Chlorine compounds are dissolved and dispersed in the slurry of raw material crystals, and M
It can be uniformly mixed and dispersed on the surface of the gO raw material crystal. Usually Mg
In the case of producing MgO by adding a chlorine compound as in the present invention in the production stage of O, M in the final product is
In gO, the form of chlorine compounds is
It is difficult to specify the morphology because it changes at the dispersion or firing stage, but it is considered that the morphology is mainly as follows.

That is, (1) the chlorine dispersed in the firing step is M
MgO / C deposited (vapor deposited) so as to cover the gO crystal surface
L-shaped, (2) MgO having a form such as Mg (OH) _2−x · Cl _x as a substitution product of the outermost hydrated layer of MgO, (3) MgCl by reacting with MgO as a main component ₂ ), those which are diffused and distributed on the surface or inside of the MgO crystal in the form of the chlorine compound of (4) group.

These chlorine compounds produce a remarkable effect of improving the glass film forming reaction with the SiO ₂ layer in the finish annealing process. When the raw material slurry to which the chlorine compound is added is dried and the chlorine compound is added in the firing or slurry preparation stage, a good glass film forming effect can be obtained in any case, but these addition ranges are within the range of MgO products. C
It is 0.010 to 0.060% as l. 0.010
If it is less than%, the reactivity improving effect is remarkably lowered even in MgO having a CAA value and a particle diameter within the range of the present invention, the glass film formation is delayed, and sufficient film thickness, adhesion and uniformity cannot be obtained. Or, deterioration of magnetism occurs. on the other hand,
If it exceeds 0.060%, decomposition and destruction of the glass coating after formation of the glass coating due to excess chlorine compound occur, resulting in non-uniformity of the glass coating, deterioration of surface sealability, and deterioration of coating tension and adhesion. The most preferable range of Cl is 0.015 to 0.050%. Within this range, good glass coating and magnetic properties can be stably obtained over a wide range of finish annealing conditions.

Next, when the annealing separator containing chlorine or a chlorine compound of the present invention is used, it is important to control the chlorine compound and the amount of chlorine adhering to the steel sheet, and (4 to 48) × 1
Limited to 0 ^-4 g / m ² . If it is less than 0.0004 g / m ² , the effect of promoting the reaction of MgO with the decarboxylated film SiO ₂ is not sufficiently performed. In this case, the thickness of the glass coating becomes thin or becomes non-uniform, and the sealing effect of the glass coating in the reaction process decreases. For this reason, the effect of improving the glass coating and magnetic properties becomes extremely small. On the other hand, 0.0048
If it exceeds g / m ² , the surplus chlorine compound or chlorine in the glass film formation may cause the glass film to become thin or non-uniform due to the etching of the glass film or base iron interface in the high temperature range of finish annealing, resulting in the film appearance. However, there is a problem that the adhesion or the magnetic properties are impaired, so that it is limited.

Depending on the metal element constituting the chlorine compound,
Although the glass coating performance and the magnetic properties are slightly affected by the difference in the melting point, decomposition temperature, etc. of the chlorine compound, good results are obtained within the scope of the present invention. As a method of controlling the chlorine amount on the surface of the steel sheet, there are an amount of MgO attached to the steel sheet surface, a mixing ratio with MgO, and the like. It is preferable to change the coating amount according to the ratio of MgO and chlorine compound.
In this case, the amount of MgO attached is preferably 4.0 to 8.0 g / m ² .

This is because if the amount is less than 4 g / m ² , the melting point of the chlorine compound is large, and the tendency of the coil edge to seize is stronger than that of the conventional technique in which no chlorine compound is added. On the other hand, if the deposition amount exceeds 8 g / m ² , the reaction of the film interface with the chlorine compound will accelerate and the water content from MgO itself will increase, resulting in a total peroxidized state and oxidation of the inhibitors in the steel sheet during the temperature rising process. It may affect the magnetic properties and deteriorate the magnetic properties. Therefore, it is desirable to control the amount of chlorine on the surface of the steel sheet by controlling within this range.

Next, PH ₂ at the time of temperature rise in finish annealing
O / P H ₂ is preferably 0.25 or less. This occurs additional oxidation of the oxide film of the P H ₂ O / P H ₂ is increased when the surface of the steel sheet during heating, SiO ₂ content is increased, or glass film becomes extremely thick, localized to the glass film This is because thickness unevenness is likely to occur. As a result, variations in film characteristics and magnetic characteristics are likely to occur. The P H ₂ O / P H ₂ control conditions are controlled by the hydrated water content of MgO, the applied amount of the annealing separator, the amount of atmospheric gas, the coil winding pressure, and the like.

[0030]

【Example】

[Example 1] C: 0.078% by weight, Si: 3.2
5%, Mn: 0.063%, S: 0.024%, Al:
0.027%, N: 0.0078%, Cu: 0.06
%, Sn: 0.010%, the balance being a high magnetic flux density grain-oriented electrical steel sheet material consisting of iron and inevitable impurities, hot rolled, annealed and cold rolled by known methods to give a final sheet thickness of 0.023 mm.
Then, decarburization annealing was performed in a wet atmosphere of N ₂ 25% + H ₂ 75% and a dew point of 67 ° C. Then, shown in Table 1,
A chlorine compound was added to the Mg (OH) ₂ slurry before firing to adjust the components, and then the S amount and chlorine amount of MgO having a specific surface area of 35 m ² / g and firing were changed to produce MgO.

5% TiO ₂ and Na ₂ B ₄ O were added to this MgO.
₇ Annealing agent with 0.3% was applied and the amount of application was changed so that the weight after drying was 5 g / m ^2, and it was applied to a steel sheet and wound as a coil after drying to a final temperature of 1200 ° C x 20 hours. Finish annealing was performed. After this, 3 as an insulating film agent
A coating agent consisting of 70 ml of 0% colloidal silica and 50 ml of 50% aluminum phosphate was applied so that the weight after drying and baking would be 5 g / m ² , and 85 in a continuous furnace.
Heat flattening treatment was performed at 0 ° C. for 30 seconds to obtain a final product. Table 2 shows the results of the glass film formation conditions, insulating film properties, and magnetic properties in this test.

[0032]

[Table 1]

[0033]

[Table 2]

As a result, in the case of using the annealing separator which was fired after adding the chlorine compound as in the present invention, the gloss was good and a thick glass film was uniformly formed. Very good results were obtained for both the coating properties and the magnetic properties. On the other hand, in the case of Comparative Example 1 containing no chlorine compound of Comparative Example, the glass film was extremely thin, resulting in poor film properties and magnetic properties. Further, in Comparative Example 2 containing a large amount of chlorine compounds, unevenness of the glass coating film occurred,
Both the coating properties and the magnetic properties were considerably inferior to those of the present invention. Further, even in the present invention range of chlorine content, when the S content is small, the glass coating is good, but the magnetism is slightly inferior, and when the S content is higher than the present invention range, the glass coating is thin and the magnetic properties are high. It was also inferior.

[Example 2] C: 0.057% by weight,
Si: 3.30%, Mn: 0.10%, Al: 0.03
0%, S: 0.0075%, N: 0.0078%, S
n: 0.05%, the rest of which is a grain-oriented electrical steel sheet slab consisting of Fe and inevitable impurities, which is heated at a low temperature of 1150 ° C. by a known method, hot rolled, and annealed and cold rolled to give a final sheet thickness of 0.23.
mm. This coil was N ₂ 2 in a continuous annealing line.
8% in a wet atmosphere with 5% + H ₂ 75% and a dew point of 65 ° C.
Decarburization annealing at 30 ° C for 110 seconds, and then N ₂ 25% + H ₂ 75% + NH so that the N content in the steel becomes 200 ppm.
Nitriding was performed at 750 ° C. for 30 seconds in the dry atmosphere of ₃ .

As shown in Table 3, the CAA40
Second, an annealing separator containing 5 parts by weight of TiO ₂ and a chlorine compound was applied to 100 parts by weight of MgO having a particle diameter of 10 μm or less and 75% by weight by changing the coating amount of the slurry on the steel sheet, and the coil was dried and wound on a coil. It was Then, as in Example 1, final annealing and insulation coating treatment were performed to obtain a final product. The results of the glass coating properties and magnetic properties of the products in this test are shown in Table 4.

[0037]

[Table 3]

[0038]

[Table 4]

As a result of this test, when the chloride-added annealing separator of the present invention was applied, the addition amount was 0.06% or less, and the chlorine application amount to the steel sheet was 0.001225-0.0.
In the case of the present invention range of 0300 g / m ² , good glass coating and magnetic properties were obtained in all cases. However, even when the chlorine content is in the range of the present invention, when the amount of the annealing separator applied is large, that is, when the chlorine content of the steel plate surface is larger than that of the present invention, metallic spot-like unevenness occurs in the glass coating, resulting in poor adhesion. Results in poor magnetic properties. When no chlorine compound was added, the glass coating was extremely thin, resulting in very poor magnetic properties.

[0040]

INDUSTRIAL APPLICABILITY According to the present invention, the reactivity in forming a fine MgO glass film is improved by adjusting the amount of chlorine to a specific range with a chlorine compound in the MgO production process or the slurry preparation step. Furthermore, by controlling the amount of chlorine adhering to the steel plate surface to an appropriate amount, a grain-oriented electrical steel sheet having a glass coating and magnetic properties equivalent to or better than those of conventional grain-oriented electrical steel sheets by the improvement technology of chlorine compound addition. Can be provided.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Nozomi Ishibashi 1-1, Tobata-cho, Tobata-ku, Kitakyushu City In-house, Hachiman Works, Nippon Steel Co., Ltd. No. 1 Nippon Steel Yawata Works (72) Inventor Toru Tanaka 46-59, Nakahara, Tobata-ku, Kitakyushu City Nippon Steel Plant Design Co., Ltd.

Claims (2)

[Claims] 1. A grain-oriented electrical steel sheet material containing Si in an amount of 2.5 to 4.0% by weight is treated by a known method to obtain a cold-rolled sheet having a final thickness, and decarburized and annealed to form an oxide film containing SiO _{2 as a} main component. After forming, applying the annealing separator, after performing the final finish annealing,
In the method for producing a grain-oriented electrical steel sheet, which comprises applying an insulating coating agent and performing heat flattening, in the step of applying the annealing separator, the specific surface area is 20 m ² / g or more, S
In the manufacturing process and / or the slurry preparation step of the annealing separator, H, Li, Sr, T was added to the MgO content of 0.05 to 1.2%.
Cl in the annealing separator by adding a chlorine compound selected from i, Nb, Ta, Cr, Mo, W, Pb, Bi and B
Was adjusted to 0.01 to 0.06% so that the amount of chlorine compounds per 1 m ² of the steel plate was Cl in the range of ( ^{4 to} 48) × 10 ⁻⁴ g / m ^2. A method for producing a grain-oriented electrical steel sheet having a uniform and excellent glass coating characterized by being applied and having extremely good magnetic properties. 2. The glass film according to claim 1, wherein the glass film is annealed with the P H ₂ O / P H ₂ of the atmospheric gas up to 800 ° C. during the finish annealing being set to 0.25 or less. , A method of manufacturing a grain-oriented electrical steel sheet having extremely good magnetic properties.