JPH08143961A - Production of grain oriented silicon steel sheet extremely excellent in glass film and magnetic property - Google Patents

Abstract

PURPOSE: To produce a steel sheet excellent in glass film formation reactivity and having superior film characteristics and magnetic properties by combinedly adding chlorine compounds of specific melting point and alkali or alkaline earth metal compounds to MgO as a separation agent at annealing. CONSTITUTION: A hot rolled plate, containing, by weight, 0.030-0.100% C and 2.5-4.0% Si and also containing sulfide and/or nitride as inhibitor, is cold-rolled once or is cold-rolled two or more times while annealed between the cold rolling stages to the final sheet thickness. Then, decarburizing annealing is applied and an oxide film is formed on the surface. After the application of a separation agent at annealing, the cold rolled sheet is finish-annealed and subjected to insulating film treatment, by which the silicon steel sheet is produced. In this method, (Fe,Mn)-O in the oxide film after decarburizing annealing is regulated to (0.015 to 0.30)g/m<2> , and also a separation agent at annealing, containing, based on 100 pts.wt. of MgO, 0.015-0.12 pts.wt., as chlorine, of one or more kinds among chroline compounds of <=1000 deg.C melting point and 0.01-0.50 pts.wt. of one or more kinds among alkali metal compounds and/or alkaline earth metal compounds, is applied to the steel sheet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is directed to the production of grain-oriented electrical steel sheets by forming a glass coating having a uniform and excellent coating performance in the final finish annealing step and at the same time providing a grain-oriented magnetic 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 Si: 2.5-
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 as slurry 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 quality and amount of the oxide film formed on the surface of the steel sheet during decarburization annealing, MgO of the glass film forming agent used as the annealing separator, and the additives are inhibitors through the formation of the glass film. Influences the crystal orientation because it greatly affects the behavior of the crystal.

Further, the effect of iron loss improvement due to the tension effect of the glass coating is also greatly affected. 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.

[0006] The glass film forming reaction in the finish annealing is performed 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 at a high temperature near 1600 ° C. in a pure system, so that the properties of the oxide film (components,
Formation condition), control of finish annealing conditions (heat cycle,
In addition to the atmospheric gas), the properties of the annealing separator include the adjustment of impurities in the main component MgO, the particle size, the particle shape, the surface state, the activity, and the like. How to form a uniform glass film from a low temperature is an important key for obtaining an excellent glass film and good magnetic properties.

As described above, since the glass coating and the magnetic properties, which are important in determining the commercial value of the grain-oriented electrical steel sheet, are greatly influenced by the additives of the decarboxylation film and the annealing separator MgO, the oxidation The development and improvement of new additive materials that match the composition and amount of the film have become an important issue in the grain-oriented electrical steel sheet manufacturing technology. MgO used as an annealing separator is generally prepared by using MgCl ₂ or seawater as a raw material.
Mg (OH) ₂ crystals are prepared by reaction with Ca (OH) ₂ and then MgO is prepared by performing compression washing once for the purpose of adjusting the purity or by firing twice or more between washing and crystal adjustment.
The particle size is adjusted by crushing, classifying, etc., if necessary, to obtain a product.

Among the properties of MgO, the factors that influence the formation of glass film and the stability of the inhibitor and, in turn, the magnetic properties of MgO include the purity, particle size, and activity of MgO.
The adhesion to the steel sheet is the main one, and when this MgO is applied to the steel sheet, there are the degree of progress of hydration, the state of dispersion of particles in the water slurry, the amount applied, and the like. Therefore, in order to obtain a grain-oriented electrical steel sheet having an excellent glass coating and magnetic properties, it is important to optimize these conditions.

As mentioned above, MgO is usually suspended in water together with a small amount of an additive to be added as a reaction accelerator, if necessary, and applied to the steel sheet in the form of a slurry. As the additives, oxides, S compounds, B compounds and the like have been usually used as reaction accelerators for forming forsterite coatings.
At this time, depending on the MgO production conditions, for example, in the case of high activity, depending on the mixing and stirring conditions with water, MgO → MgO
As a result of a hydration reaction that becomes (OH) _2, and moisture is brought into the coil (between the plates), there is a problem that the dew point between the plates is increased and the atmosphere condition becomes nonuniform in the coil longitudinal direction and the width direction.

Further, depending on the kind and amount of the additive, the quality of the glass film depends on the excess oxygen and the reaction promoting effect,
It has a great influence on the quantity. For this reason, in the heating process of finish annealing, non-uniform, excessive additional oxidation occurs, and scale,
Causes severe film defects such as gas marks, pinholes, and discoloration.

As a means for solving the problem caused by the high hydration, a method of high temperature calcination is generally adopted. As this method, for example, JP-A-55-7382
There is No. 3 publication. In the low-activity MgO obtained by increasing the firing temperature in this way, a decrease in hydration is obtained,
There is a drawback that activity (reactivity) and adhesion are 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 Examined Patent Publication No. 2-5820.
In the publication, one or two or more chlorides of Sb, Sr, Ti and Zr are added in an amount of 0.02 to 100 parts by weight of MgO.
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 components on the surface of the steel sheet with SiO ₂ and suppresses additional oxidation in the final annealing and promotes the reaction, resulting in excellent iron loss characteristics and glass coating. It is a thing. In addition, Japanese Patent Laid-Open No. 3-1
As a technique for improving the chloride addition technique described above, Japanese Patent No. 20376 discloses that if a metal chloride selected from Mg, Na, K and Ca is added to MgO, magnetic properties can be obtained without using antimony sulfate and sodium metasilicate together. It has been shown that an effect of improving the characteristics can be obtained.

[0014]

As described above, by improving the properties of MgO and the additive of the reaction accelerator, the glass film forming reaction is improved and the effect is obtained. However, the glass coating 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 technological improvements are desired. is there. Thus, the development of a low hydration, highly reactive annealing separator has been a long-standing goal of engineers involved in the production of grain-oriented electrical steel sheets.

The present inventors have conducted enormous research and experiments on a measure for improving the reactivity of the glass coating in order to reach the realization of an annealing separator having low hydration and high reactivity. As a result, under a constant condition of the amount of (Fe, Mn) -O of the decarboxylation film component, a chlorine compound and an alkali metal compound having a melting point in a certain range and //
It has also been found that the composite addition of an alkaline earth metal compound makes it possible to obtain a grain-oriented electrical steel sheet having excellent glass film forming reactivity and extremely excellent film properties and magnetic properties.

[0016]

SUMMARY OF THE INVENTION The present invention has the following features as a solution in the prior art of a decarburization annealing oxide film component and an additive to the annealing separating agent MgO in forming a glass film. C: 0.030 to 0.100 wt%, Si:
A hot-rolled sheet containing 2.5 to 4.0 wt% and at least one of sulfide and nitride as an inhibitor is annealed, if necessary, and is finished by cold rolling once or twice or more with sandwiching the annealing. After the plate thickness, decarburization annealing, forming an oxide film on the surface, finish annealing after applying an annealing separator, in the method for producing a grain-oriented electrical steel sheet comprising an insulating film treatment, in the decarburization annealing (Fe, Mn) -O of oxide film
^On a steel sheet annealed ^{(* 1)} in the range of 0.015 to 0.30 g / m ² , one or two or more chlorine compounds having a melting point of 1000 ° C. or less with respect to 100 parts by weight of MgO. An annealing separator containing 0.015 to 0.12 parts by weight of chlorine and 0.01 to 0.50 parts by weight of one or more kinds of alkali metal compounds and / or alkaline earth metal compounds is used. A method for producing a grain-oriented electrical steel sheet having extremely excellent glass coating performance and magnetic properties.

As a result, the inventors have succeeded in improving the MgO additive, which could not be realized by the conventional technique, and in particular, by developing the technique which exceeds the conventional chloride addition technique by the present inventors. That is, according to the present invention, the glass coating is uniform under a wide range of conditions at a lower cost, more reliably and effectively than the conventional improvement technique using the reaction promoting additive for MgO, and the magnetic characteristics are the entire surface of the coil. A good grain-oriented electrical steel sheet can be obtained over the entire length.

In the application of the present invention, Si: 2.5-4.0% and MnS and / or AlN are used as starting materials.
The silicon steel slab containing the above is hot-rolled by a known method, and cold-rolled once or twice or more by sandwiching annealing to obtain a final plate thickness, and then decarburization-annealed to make the surface of the steel sheet mainly composed of SiO ₂ . As (Fe, Mn) -O component 0.015 to 0.30 g
A so-called decarburized annealed plate having a fixed amount of / m ² is used.

If necessary, other additives such as oxides are added to 100 parts by weight of MgO, and the chlorine compound having a melting point of 1000 ° C. or less, which is a feature of the present invention, is used as chlorine. 0.015 to 0.12 parts by weight and one or more kinds of alkali metal and / or alkaline earth metal compounds added in an amount of 0.01 to 0.50 parts by weight of the annealing separator added in pure water to uniformly stir After being finely dispersed and made into a slurry, a certain amount is applied to the surface of the steel sheet by a coating roll or the like in a continuous line, dried at a temperature of about 150 to 400 ° C. (sheet temperature), and wound into a coil.

At this time, the annealing separator MgO contains, in addition to the chlorine compound, an oxide, as a reaction promoting auxiliary agent for forming a glass film, a dew point adjusting agent between plates, and an inhibitor strengthening auxiliary agent.
Boron compounds, sulfur compounds, nitrogen compounds, etc. are added in combination according to the steel composition and processing conditions. The coil thus treated is subjected to a final finish annealing at a high temperature such as 1150 to 1200 ° C. × 20 hr for a long time in a batch type or continuous type furnace to form a glass film, secondary recrystallization and purification. Are done at the same time.

The coil thus treated with the glass coating film has the surplus annealing separator removed by washing with water in a continuous line, lightly pickled, and then coated with an insulating coating agent.
Heat flattening is performed to combine the baking, shape correction, and strain relief annealing to obtain the final product. In the grain-oriented electrical steel sheet, the formation timing, the formation amount, the formation state, etc. of the glass coating at this time affect the decomposition rate of the inhibitors AlN, MnS, etc., and affect the quality, tension or purification reaction of the glass coating. As a result, the glass coating properties and magnetic properties of the product are affected.

At this time, in the grain-oriented electrical steel sheet, especially in the high magnetic flux density material, since the effect of improving iron loss, magnetostriction, etc. by the film tension is great, in order to further reinforce the tensile effect of the glass film formed by finish annealing. In addition, a tension-imparting type is applied as an insulating coating component. As the coating agent for imparting tension and insulation, one or two phosphates such as Al, Mg, and Ca are used per 100 parts by weight of solid colloidal silica.
It is economical to use a mixture of 130 to 200 parts by weight of one or more kinds and 12 to 40 parts by weight of one or more kinds of chromic acid, chromate and dichromate as CrO ₃ in an economical manner. It is suitable for obtaining.

After that, if it is desired to further improve the iron loss, before or after the finish annealing, a linear or dotted space is formed in the direction substantially perpendicular to the rolling direction by laser, tooth profile roll, etching, local plating, or the like. And the depth is controlled, and the strain, flaw, plating layer, etc. are processed to subdivide the magnetic domain.

Next, the reasons for limitation of the present invention will be described. First, as a condition of the decarburizing plate of the grain-oriented electrical steel sheet applied to the present invention, the oxide film component is (Fe, Mn) -O 0.015.
The range is from 0.30 g / m ² . (Fe, Mn) -O
The components are mainly Fe ₂ SiO ₄ , FeS on the surface layer of the steel sheet surface.
It exists in the form of iO ₃ , Mn ₂ SiO ₄ , and MnSiO ₃ . This (Fe, Mn) -O-based oxide has a slight accelerating effect in the forsterite film formation reaction, and also affects the atmospheric gas permeability of the oxide film.

These contribute to the improvement of the reactivity between MgO and SiO ₂ synergistically with the chloride, alkali metal, alkaline earth metal and the like of the present invention. A value (Fe, Mn) -O obtained by quantifying the total amount of these oxide films with Fe and Mn.
If the amount is less than 0.015 g / m ² , the effect of improving the stability of the glass coating cannot be sufficiently obtained even if the technique of adding a chlorine compound and an alkali and / or an alkali metal compound of the present invention is used.

On the other hand, if it exceeds 0.30 g / m ² , there is a problem that the oxide film itself is porous and the sealing property is weakened. Further, the addition of the chlorine compound of the present invention and an alkali and / or an alkaline earth metal causes pinhole-like metallic luster spots, scales, gas marks, etc. as a glass film defect peculiar to peroxide, and the deinhibitor peroxidizes. Phenomenon is limited because it is accelerated by a phenomenon, which causes a decrease in magnetic flux density and defective iron loss.

Next, as an additive to be applied, Mg
O: 0.015 in terms of chlorine content based on 100 parts by weight of one or more chlorine compounds having a melting point of 1000 ° C. or less
.About.0.12 parts by weight and 0.01 to 0.5 parts by weight of one or more kinds of alkali metals and / or alkaline earth metals are added in combination. First, in the present invention, the melting point of the chlorine compound is 1
The limit is 000 ℃ because most chlorine compounds are MgO
It dissolves in the slurry due to its high water solubility, and evenly adheres to the surface of MgO and other additives or the surface of the steel sheet during coating and drying. In this case, as described above, the metal chloride, hydrochloric acid, and a substitute for the hydrated layer adhere to the MgO surface. In the case of chlorides, the melting point, decomposition temperature, etc. cause a difference in the effect of promoting glass film formation, so that the application conditions are limited.

A compound having a melting point of more than 1000 ° C. is decomposed / disappeared depending on the atmospheric gas and temperature before contributing to the glass film forming reaction. Therefore, the effect of improving the reactivity is weakened, the improvement of the glass film is not observed, and the protective effect of the inhibitor due to the improvement of the sealing property is extremely weakened, so that it is limited. In the case of a chlorine compound having a melting point of less than 1000 ° C., the reaction of MgO and SiO ₂ is significantly enhanced by the presence of the molten glass layer on the decarboxylated film, and AlN,
As a result of the inhibitors such as MnS being kept stable from low temperatures, good magnetic flux density and iron loss characteristics can be obtained.

Examples of the chlorine compound include LiC
1, CuCl, CaCl ₂ , BaCl ₂ , MnCl ₂ ,
MoCl ₂ , FeCl ₂ , CoCl ₂ , ZnCl ₂ , C
dCl ₂ , SnCl ₂ , BiCl _{3 and the} like are effective, and the effect is remarkably excellent when used in combination with an alkali and / or alkaline earth metal compound.

The amount of this chlorine compound added is MgO: 10.
0,05 parts by weight converted to chlorine 0.015 to 0.200
Parts by weight. If the amount is less than 0.015 parts by weight, the effect of lowering the melting point of the chlorine compound is insufficient even when an alkali metal substance or the like is used in combination, and sufficient glass film thickness and uniformity and the surface sealing effect of the film cannot be obtained. On the other hand, when the chlorine content exceeds 0.2 parts by weight, the early melting effect of the glass film can be obtained by the melting point lowering effect, but the combined action of the excess chlorine content and the alkali metal substance causes the etching of the glass film in the high temperature range of the final annealing.・ Decomposition and reduction reactions occur. For this reason, thinning and nonuniformity of gas marks occur, resulting in poor adhesion, poor insulation, and low film tension.

Next, the alkali metal and / or alkaline earth metal added together with the chlorine compound is 0.01 to 0.5 part by weight per 100 parts by weight of MgO. In the present invention,
The alkali metal or alkaline earth metal has an important role in keeping the chlorine compound stable from the time of addition to the high temperature of the glass film formation of finish annealing.

That is, most of the added chlorine compounds are easily dissolved in the water slurry in the slurry. In addition, a part thereof becomes an oxy compound, hydrochloric acid, etc. and exists in the slurry. At the time of coating and drying, these generate a new chlorine compound, or become hydrochloric acid, a hydrated layer-substituting substance, etc. to uniformly cover the surface of MgO and adhere to the steel plate surface. At this time, when the coil is applied and dried, or disappears early in the temperature rising process of finish annealing, the function is lost.

However, when a water-soluble alkali or alkaline earth metal compound coexists as in the present invention,
When the unstable chlorine ionized in the slurry is applied and dried, it preferentially binds to the alkali or alkaline earth metal to form a compound according to the solubility of the alkali or alkaline earth metal in the water. It will remain stable on the surface of the steel sheet until the time of forming the glass film by high temperature annealing. For this reason, the reaction initiation and reaction promotion effect at an early stage when the temperature of finish annealing is increased are exerted more strongly.

As the alkali metal or alkaline earth metal compound, a water-soluble substance such as hydroxide, borate, sulfate, nitrate or silicate is used. If the addition amount is less than 0.01 parts by weight with respect to 100 parts by weight of MgO,
The stabilizing effect due to the fixation of chlorine cannot be obtained. on the other hand,
If the amount exceeds 0.5 parts by weight, excessive alkali metal or alkaline earth metal compound causes etching or reduction reaction at high temperature, which may cause problems of glass film defects and magnetic defects similar to the case where the chlorine compound is added. Limited to cause.

[0035]

【Example】

[Example 1] C: 0.078 and Si: 3.3 by weight%
5, Mn: 0.060, S: 0.024, Al: 0.0
25, N: 0.0080, Cu: 0.06, Sn: 0.
012, the rest was a high magnetic flux density grain-oriented electrical steel sheet material consisting of iron and unavoidable impurities, hot rolled, annealed and cold rolled by a known method to give a final sheet thickness of 0.023 mm. Then N ₂ 25
% + H ₂ 75%, decarburization annealing was performed in a wet atmosphere with a dew point of 67 ° C. (Fe, M in the surface oxide film of this steel plate
The amount of n) -O was 0.15 g / m ² .

Then, as shown in Table 1, MgO: 10
0 parts by weight and 5 parts by weight of TiO ₂ were coated with an annealing separator slurry containing a combination of a metal chloride, an alkali metal and an alkaline earth metal compound at a rate of 6 g / m ² by dry weight, and dried. Then, it was wound into a coil. Then 12
After final finishing annealing at 00 ℃ × 20Hr, a coating agent consisting of 70 ml of 30% colloidal silica and 50 ml of 50% aluminum phosphate as an insulating coating agent is applied so that the weight after drying and baking is 5 g / m ^2. Then, heat flattening treatment was performed at 850 ° C. for 30 seconds in a continuous furnace 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.

[0037]

[Table 1]

[0038]

[Table 2]

As a result, in the case where the metal chloride and the alkali or alkaline earth metal compound are added together as in the present invention, a thick and glossy glass film is uniformly formed, and the film tension and adhesion are improved. A glass film having excellent properties was formed, and the magnetic properties were very good.
On the other hand, with the chlorine compound of Comparative Example alone, the glass coating tended to be thin, and the adhesion of the glass coating was poor and the magnetic properties were slightly inferior to those of the present invention. Further, when only the alkali metal compound was used, the state of film formation was further poor, and the magnetic properties were considerably inferior to those of the present invention.

[Example 2] C: 0.058, S by weight%
i: 3.30, Mn: 0.12, Al: 0.030,
S: 0.0075, N: 0.0078, Sn: 0.0
5. A grain-oriented electrical steel sheet slab consisting of the balance Fe and unavoidable impurities was heated at a low temperature of 1150 ° C. by a known method, then hot rolled, and annealed and cold rolled to a final sheet thickness of 0.23 mm. This coil was subjected to N ₂ 25% + H ₂ 7 in a continuous annealing line.
Dew point was changed in a wet atmosphere with 5% dew point of 68 ° C., decarburization annealing was performed at 830 ° C. for 110 seconds, and (F
e, Mn) -O different decarburization annealed sheets were obtained. Succeedingly, N ₂ 25% + H ₂ 7
Nitriding treatment was performed at 750 ° C. for 30 seconds in a dry atmosphere of 5% + NH ₃ .

As shown in Table 3, MgO: 10 was added to this steel sheet.
To 0 parts by weight, TiO _2: 5 parts by weight and the metal annealing separator slurry chloride and alkali metal and alkaline earth metal compounds added in combination is applied at a rate of 6 g / m ² on a dry weight after, after drying I wound it up in a coil. Then, Example 1
In the same manner as above, final annealing and insulation coating treatment were performed to obtain the final product. The results of the glass coating properties and magnetic properties of the products in this test are shown in Table 4. In addition, in FIG. 1, (Fe, M
The relationship between the amount of n) -O, the amount of Cl in MgO, and the glass film characteristics is shown. A good glass coating is formed within the scope of the present invention.

[0042]

[Table 3]

[0043]

[Table 4]

As a result of this test, when a constant amount of (Fe, Mn) -O in the oxide film was used and a chloride, an alkali metal and an alkaline earth metal compound were added in a complex manner as in the present invention, both were found. The uniformity, tension, and adhesion of the glass coating were good, and the magnetic properties were also very excellent. On the other hand, even when the chlorine compound and the alkali metal compound of the comparative example are in the range of the present invention, the comparative examples having a large amount of (Fe, Mn) -O have a non-uniform glass coating, resulting in poor adhesion and poor magnetic properties. It was Further, in the comparative examples in which the amount of (Fe, Mn) -O in the decarboxylated film is more than the range of the present invention, the glass film exhibits peroxide-like defects, and the magnetic properties are considerably inferior to those of the present invention. became.

[0045]

As in the present invention, the melting point is 1000 ° C.
By adding the following chlorine compound together with the alkali metal and / or alkaline earth metal compound, the chlorine compound having a low melting point can be stably maintained on the steel sheet from the coating drying to the glass film forming period in finish annealing. In addition, fine particles of MgO and a trace amount of hydrated substances, chlorine and alkali metal, alkaline earth metal reactants and mixed substances are bound as binders between particles of MgO and other additives to form a steel plate. Improves adhesion and further promotes forsterite film formation. As a result, as shown in FIG. 1, the compound effect of the chloride and the alkali metal compound is added so that the component effect of the oxide film is further exerted and the forsterite film of fine particle crystals is uniformly formed. As a result, a glass coating having excellent adhesion and coating tension is obtained.

Further, as a result of the glass film formation being uniformly performed from the early stage during the temperature rise of the finish annealing, the invasion of N gas or the like from the steel plate atmosphere gas into the steel is suppressed, while the additional oxidation of the steel sheet during annealing is prevented. It forms a high-quality, high-quality glass film that suppresses, is uniform, and does not harm the magnetism. At this time, the improvement of the sealing effect at the film interface is suppressed by denitrification and de-sulfurization due to decomposition of the inhibitors AlN, MnS, etc., and by suppressing the invasion and oxidation of nitrogen from the atmospheric gas, it is stabilized up to a high temperature. It is considered that the iron loss is improved in combination with the effect of improving the glass film tension.

[Brief description of drawings]

FIG. 1 The same material as in Example 2 was applied by changing the composition of the oxide film of a decarburized annealed plate and annealed to the material annealed by changing the additive of an annealing separator, and the formation state of the glass film was evaluated. It is a chart.

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Osamu Tanaka 46-59 Nakahara, Tobata-ku, Kitakyushu City Nittetsu Plant Design Co., Ltd.

Claims (1)

[Claims] 1. C: 0.030 to 0.100 wt%, S
i: A hot rolled sheet containing 2.5 to 4.0 wt% and at least one of a sulfide and a nitride as an inhibitor is made into a final sheet thickness by performing cold rolling once or twice or more with annealing sandwiched therebetween. In the method for producing a grain-oriented electrical steel sheet, which comprises decarburizing and annealing, forming an oxide film on the surface, applying an annealing separator, finishing annealing, and then performing an insulating film treatment, the oxide film after decarburizing and annealing ( Fe, Mn) -O 0.015
0.30 g / m ² and MgO: 10 on the steel plate.
With respect to 0 part by weight, one or more chlorine compounds having a melting point of 1000 ° C. or less are used as chlorine in an amount of 0.015 to 0.
0.01 to 0.50 of 12 parts by weight and one or more of alkali metal compounds and / or alkaline earth metal compounds.
A method for producing a grain coating and a grain-oriented electrical steel sheet having excellent magnetic properties, characterized by applying an annealing separator contained in an amount of 1 part by weight. However, (Fe, Mn) -O: the amount (g / m ² ) calculated as a value per unit area of the steel sheet by electrolytically stripping the oxide film on the steel sheet surface, quantifying Fe and Mn.