JPH08165521A - Production of grain-oriented silicon steel sheet extremely excellent in glass coating and magnetic characteristic - Google Patents

Abstract

PURPOSE: To obtain a magnetic steel sheet having uniform high tension glass coating and excellent in the magnetic characteristic by specifying the separation agent for annealing and the last finish annealing condition, at the time of producing the grain oriented silicon steel sheet from an electrical steel slab having a specific composition. CONSTITUTION: The silicon steel slab composed of, by wt.%, 0.010-0.0075 C, 2.0-4.5 Si, <=0.015 S, 0.01-0.035 acid soluble Al, <=0.012 N, 0.05-0.45 Mn and the balance Fe is heated at low temp., such as <=1280 deg.C. This slab is hot-rolled to make the final sheet thickness by cold-rolling at one time or two or more times inserting intermediate annealing, and decarburization-annealing and nitrogen annealing are executed, and after coating the separation agent for annealing, the finish annealing is executed and an insulation coating treatment is applied to obtain the grain-oriented silicon steel sheet. In this method, the separation agent for annealing containing 0.015-0.120wt. parts of as F, Cl, Br and I in one or more kinds of halogenide to 100wt. parts of NgO is coated, and after raising the temp. to 850-1100 deg.C the final finish annealing at <=12 deg.C/hr average raising temp. ratio, the high temp. finish annealing is executed.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention, in the production of grain-oriented electrical steel sheet, in the final finishing annealing step, forms an extremely uniform and excellent high-tensile glass coating over the entire surface of the coil and has good magnetic properties. The present invention relates to a manufacturing method for obtaining a grain-oriented electrical steel sheet.

[0002]

2. Description of the Related Art Usually, grain-oriented electrical steel sheets have a Si 2.0-
A raw material slab containing 4.5% is hot-rolled and annealed and cold-rolled once or twice with 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 manufacture an excellent grain-oriented electrical steel sheet, it is important to control the dispersed state of the inhibitor in the steel and control the decomposition thereof.
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.

The reaction of forming a glass film in the finish annealing is carried out by using MgO as an annealing separator and SiO formed by decarburization 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 system at a high temperature near 1600 ° C. Therefore, 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. Thus, for the glass coating and magnetic properties that are important in determining the commercial value of the grain-oriented electrical steel sheet, the effects of the additives for decarboxylation film and annealing separator and finish annealing conditions are large, The development of these process conditions that match the steel plate composition has become an important issue in the grain-oriented electrical steel sheet manufacturing technology.

As described above, MgO used in the glass film forming step 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, MgO
Depending on the production conditions, for example, in the case of high activity, a hydration reaction of MgO → Mg (OH) ₂ occurs depending on the mixing and stirring conditions with water, 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. Further, depending on the kind and amount of the additive, the quality and quantity of the glass film are greatly affected by the excess oxygen and the difference in the reaction promoting effect. For this reason, it is not uniform during the temperature rise process of finish annealing,
It causes excessive additional oxidation and causes severe film defects such as scales, gas marks, pinholes, and discoloration.

As a means for solving the problem due to the high hydration, generally, a method using MgO of high temperature firing is adopted. For example, Japanese Patent Application Laid-Open No. 55-73823 discloses this method. Low activity MgO obtained by increasing the firing temperature
However, there is a drawback in that the activity (reactivity) and the adhesion are reduced although the hydration property is reduced. In addition, as a technique for improving the glass film and the magnetism by the additive in the annealing separator, Japanese Patent Publication No.
No. 5820 discloses that one or two or more chlorides of Sb, Sr, Ti, and Zr are added in an amount of 0.
A method of adding 02 to 1.5 parts by weight has been proposed.

As a result, the additive compound brings about the enrichment and densification of the oxide layer component on the surface of the steel sheet with SiO ₂ and suppresses the additional oxidation and the effect of accelerating the reaction in the finish annealing, so that the excellent iron loss characteristics and the glass coating film are obtained. Is what you get. Further, Japanese Patent Laid-Open No. 3-120376 discloses a technique for improving the chloride addition technique described above, which includes Mg, Na and K.
It is shown that addition of a metal chloride selected from Ca and Ca to MgO can improve the magnetic properties without using antimony sulfate and sodium metasilicate in combination. As described above, by improving the properties of these MgO and the additive of the reaction accelerator, the glass film forming reaction is improved and the effect is obtained.

Further, Japanese Patent Laid-Open No. 49-76719 discloses a technique for improving the quality of a grain-oriented electrical steel sheet by improving the finish annealing cycle. This is S
i: 4% or less, C: 0.06% or less, Sb: 0.005
˜0.100% and Al; 0.01˜0.05%, and 800-95 in final finish annealing.
The objective is to sufficiently develop the secondary recrystallization in the temperature range of 0 ° C. That is, the component material in the present invention having a low secondary recrystallization temperature is kept in a temperature range of 850 to 950 ° C., and after sufficiently secondary recrystallization, purification annealing is subsequently performed at a high temperature of 1180 ° C. or higher. , Due to this,
Improved magnetic properties have been 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 stable glass film forming technique in finish annealing has been a long-standing issue for engineers involved in the production of grain-oriented electrical steel sheets.

[0010]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
AlN or (Al, Si) N by the following low temperature slab heating
The present invention has been made for the purpose of providing a manufacturing method for obtaining a uniform glass coating of a high-temperature secondary recrystallization process material that utilizes benzene as an inhibitor, a high tensile strength, and an improvement in magnetic properties.

[0011]

As a steel component, the inventors of the present invention have used C: 0.010 to 0.075% by weight, Si:
2.0-4.5%, S; 0.015% or less, acid-soluble A
1; 0.010 to 0.035%, N; 0.012% or less, Mn; 0.05 to 0.45%, the balance being a magnetic steel slab consisting of Fe and unavoidable impurities at a low temperature of 1280 ° C. or less. After heating, it is hot-rolled and cold-rolled once or twice with intermediate annealing to obtain the final thickness, decarburized and nitrogen-annealed, after applying an annealing separator, finish annealing, insulation In a method for producing a grain-oriented electrical steel sheet consisting of coating treatment, decarburization annealing and application of an annealing separating agent to final finishing annealing conditions were studied in order to improve the glass coating forming reaction.

As a result, a material having a high secondary recrystallization temperature using AlN or (Al, Si) N as an inhibitor, such as the material to which the present invention is applied, is particularly different from the conventional grain-oriented electrical steel sheet. , It was discovered that functional separation of glass film formation and secondary recrystallization is possible. That is, in the active temperature range of the glass film forming reaction, after sufficient glass film formation was performed by the reactivity improvement of the annealing separator and the heat cycle effect, secondary recrystallization was performed, and it was extremely excellent. We have completed a technology that can achieve both glass coating and magnetic properties.

As an annealing separator for this purpose, MgO, a halogen compound and an alkali metal or an alkaline earth metal are formed on a steel sheet on which an oxide film containing SiO ₂ and firelite as an oxide film component is formed by decarburization annealing. The annealing separator added as needed is applied, and the temperature rise rate in the final finish annealing at 850 to 1100 ° C is 12 ° C / hr on average.
By annealing as described below, a grain coating is uniformly formed and excellent, and a grain-oriented electrical steel sheet having extremely good magnetic properties is obtained.

The present invention has the following features as a solution of the prior art in decarburization annealing, annealing separator, and final finishing annealing in the glass film formation and secondary recrystallization process. (1) C by weight%; 0.010 to 0.075%; Si;
2.0-4.5%, S; 0.015% or less, acid-soluble A
1; 0.010 to 0.035%, N; 0.012% or less, Mn; 0.05 to 0.45%, the balance being a magnetic steel slab consisting of Fe and unavoidable impurities at a low temperature of 1280 ° C. or less. After heating, it is hot-rolled and cold-rolled once or twice or more with intermediate annealing sandwiched to obtain the final plate thickness, decarburization annealing and nitriding annealing, after applying an annealing separator, finish annealing, insulation In a method for producing a grain-oriented electrical steel sheet comprising coating treatment, one, two or more halogen compounds are added as F, Cl, B to 100 parts by weight of MgO as an annealing separator.
An annealing separator containing 0.015 to 0.120 parts by weight as r and I is applied, and the average temperature rising rate in the region of 850 to 1100 ° C of the final finish annealing is increased to 12 ° C / Hr or less, followed by high temperature finish annealing. A method of manufacturing a grain-coated electrical steel sheet having excellent glass properties and magnetic properties, which is characterized by:

(2) In the manufacturing method described in (1),
The halogen substances added to the annealing separator MgO are F, Cl,
With respect to 0.015 to 0.012 parts by weight as Br, I,
A method for producing a grain coating and a grain-oriented electrical steel sheet having extremely excellent magnetic properties, which comprises adding one or more of an alkali metal compound and an alkaline earth metal compound in an amount of 0.010 to 0.50 parts by weight. (3) In the manufacturing method according to (1) or (2), 5 to 5 in the temperature range of 850 to 1100 ° C of finish annealing.
Characterized by maintaining a constant temperature in the range of 20 hours,
A method of manufacturing grain-oriented electrical steel sheets with extremely excellent glass coating and magnetic properties. As a result, under a wide range of manufacturing conditions that could not be realized by conventional technology, the glass coating is uniform over the entire surface and width of the coil, high tension and adhesion are excellent, and further high magnetic flux density and low iron loss directionality are obtained. To be

In applying the present invention, the above-mentioned component slab is used as a starting material, and the slab is heated at a low temperature of 1280 ° C. or lower, hot rolled, annealed, and cold rolled to obtain a final plate thickness. After decarburization annealing, SiO ₂ is formed on the surface to form an oxide film containing firelite as a main component, and then nitriding treatment is performed to adjust. MgO100 is used as an annealing separator on this steel sheet.
One part or two or more kinds of halogen element compounds are added to parts by weight of F,
Cl, Br, I as 0.010 to 0.120 parts by weight and, if necessary, a substance containing an alkali metal or alkaline earth metal compound and other oxides are uniformly dispersed in pure water as a slurry, It is applied in a fixed amount with a coating roll or the like and wound on a coil.

Then, as the final finish annealing, the temperature range from 850 to 1100 ° C. at the time of heating is 12 at an average heating rate.
After gradually heating or soaking at a constant temperature so that the temperature becomes ℃ / Hr, heat treatment at a high temperature of 1150 to 1200 ° C. × 20 Hr for a long time is performed to form a glass film, secondary recrystallization, and purification. The coil after the glass coating formed in this manner is removed by washing the surplus annealing separator in a continuous line with water, followed by light pickling, and then the insulating coating is applied,
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 time, amount and state of formation of the glass coating at this time affect the decomposition rate of the inhibitors AlN, MnS, etc., and the quality, tension or purification reaction of the glass coating. As a result, it affects the glass coating properties and magnetic properties of the product. At this time, in the grain-oriented electrical steel sheet, especially in the high magnetic flux density material, the iron loss due to the coating tension, the effect of improving the magnetostriction, etc. is great, so in order to further reinforce the tension effect of the glass coating formed by finish annealing, insulation A tension-imparting type is applied as the coating component.

The tension-imparting and insulating coating agent is Al, M for 100 parts by weight of colloidal silica in solid content.
One or two or more phosphates such as g and Ca are added to 130 to 20
It is preferable to use 0 part by weight and one or more of chromic acid, chromate, and dichromate as CrO _{3 in an amount} of 12 to 40 parts by weight to economically obtain a high-strength coating. is there. After this, if it is desired to further improve the iron loss, before or after the finish annealing, laser, tooth profile rolls, etching, local plating, etc. are used to form linear or dotted intervals and depths in a direction substantially perpendicular to the rolling direction. Control
The magnetic domain subdivision processing is performed by processing the strain, the flaw, the plating layer and the like.

The reasons for limitation of the present invention are as follows. If the content of C is less than 0.010%, the secondary recrystallization becomes unstable. Further, even when the secondary recrystallization is performed, the variation of the magnetic properties of the product becomes large, so that it is limited. On the other hand, C
If the content of Al exceeds 0.075%, it will be disadvantageous in forming an oxide film in decarburization annealing, and the annealing time will be prolonged and productivity will be impaired. The content of Si is 2.
If it is less than 0%, it is difficult to obtain a product with low iron loss, while
If it exceeds 4.5%, cracks and fractures frequently occur during cold rolling, which makes stable cold rolling work difficult.

One of the characteristics of the component system of the starting material of the present invention is that S is 0.015% or less, preferably 0.010%.
There is a point to. Conventional publicly known technology, for example, Japanese Patent Publication No. 40-
In the technology disclosed in Japanese Patent No. 15644, Japanese Patent Publication No. 47-25250, or US Pat. No. 1,965,559, S is indispensable as an element for forming MnS, which is a precipitate necessary for causing secondary recrystallization. It was However, MnS is not particularly required in the present invention using (Al, Si) N as the inhibitor. Rather, an increase in MnS is not preferable in terms of magnetic properties.
Therefore, in the present invention, the S content is 0.015% or less.

Al combines with N to form AlN,
In the present invention, it is indispensable to nitride the steel sheet to form (Al, Si) N after the post-process, that is, after the primary recrystallization in the decarburization annealing, so a certain amount of Al is required. Therefore, 0.010 to 0.03 as acid-soluble Al
5% is included. If it is lower or higher than this range, the present invention cannot be satisfied. If N exceeds 0.012%, a steel plate called a blister tends to swell. On the other hand, if the amount is too small, it becomes difficult to adjust the primary recrystallized grain size during decarburization annealing, and as a result, excellent magnetic properties cannot be obtained, so the lower limit is about 0.002%.

If the content of Mn is too small, less than 0.050%, or too much, 0.45%, the present invention cannot be satisfied. The preferred range is 0.070-0.
25%. In the present invention, in addition to the above elements, S is used for the purpose of controlling the grain size of secondary recrystallized grains and controlling the oxidation amount of decarburization annealing.
You may add and use n, Sb, Cr, etc.

Next, as the annealing separating agent which is the first feature of the present invention for improving the glass coating, one or more halogen element compounds are added to F, C based on 100 parts by weight of MgO.
It is 0.015 to 0.12 parts by weight in terms of 1, Br, I. These halogen compounds have an important role in the glass film formation and the secondary recrystallization when the temperature of finish annealing is increased, matching with the finish annealing cycle described later. The halogen compound drastically lowers the melting point in the reaction between MgO and SiO ₂ , and increases the reaction initiation and progress rate at lower temperatures. Most of these added halogen element compounds can be easily dissolved and dispersed in the slurry. From the slurry preparation to the coating and drying step, these become the original halogen compound, the reaction product with other additives, the substitution material for the hydrated layer on the surface of MgO, etc., and the surface of MgO or other additives or the steel sheet. It evenly covers the oxide film, and has the effect of promoting film formation.

The amount of the halogen element compound added is MgO10.
The total amount of halogen elements is 0.01 with respect to 0 parts by weight.
If it is less than 5%, this accelerating effect is not seen and the improvement of the coating properties cannot be obtained. On the other hand, if it exceeds 0.12 parts by weight, an early glass film formation phenomenon due to the lowering of the melting point is observed, but excessive F, C
Due to l, Br, I, etc., the thickness of the glass coating becomes non-uniform, and in extreme cases, etching / decomposition reaction may occur and the glassless state may be exhibited.
The preferred range of addition is 0.027 to 0.050%,
Within this range, excellent glass coating and good magnetic properties can be obtained extremely stably even if other conditions change.

When an alkali metal or alkaline earth metal element compound is added together with the halogen element compound,
One or two or more of them are based on 100 parts by weight of MgO,
0.01 to 0.50 parts by weight is preferable. The halogen element compound must be kept stable until the time of forming the glass film during the process of slurry preparation-coating / drying-finish annealing. Alkali metal and alkaline earth element compounds selectively combine with halogen elements in the coating and drying stages according to their solubility, and evenly cover the surface of MgO particles, other additive particles or the steel sheet oxide film to form a glass film. Keeps stable until time. As a result, the glass film forming reaction by the halogen element compound can be improved very effectively.

If the amount of the alkali metal or alkaline earth metal compound added is less than 0.01 part by weight, sufficient stabilization of the halogen compound cannot be obtained. On the other hand, if it exceeds 0.50 parts by weight, the glass coating film may deteriorate due to the etching action of the glass coating film in the high temperature region caused by the excess alkali or alkaline earth metal.

Next, the heat cycle of finish annealing, which is the second important factor in the film forming process, is the heating process 850-1.
The average heating rate at 100 ° C. is 12 ° C./hr or less. In the component material of the present invention, the secondary recrystallization temperature is the conventional grain-oriented electrical steel sheet using MnS as the inhibitor, or the Al
It is considerably higher than the high magnetic flux density grain-oriented electrical steel sheet using N and MnS, and it is approximately 1 depending on other process conditions.
It occurs at high temperatures above 100 ° C. Therefore, the feature of the finish annealing of the present invention is that the glass film formation is sufficiently developed in the region of 850 to 1100 ° C. before the secondary recrystallization.

The lower limit in this case is 850 ° C.
If the temperature is lower than 50 ° C, the formation of the glass film hardly progresses, and if the low temperature region is heated at a low speed and left to stay for a long time, the reduction of the oxide film on the surface progresses before the start of the glass film formation, which rather adversely affects the glass film formation. This is because. 850-
The average temperature of 1100 ° C is 12
The heating may be carried out at a temperature of ℃ / Hr or less, or may be carried out at a constant temperature.

If the average heating rate exceeds 12 ° C./Hr, it is difficult to obtain a stable effect because the time required for growing the glass film is insufficient. Considering on-site manufacturing, the preferable condition is 8
A method of maintaining a constant temperature in the range of 50 to 1100 ° C. for 5 to 20 hours is a preferable condition for obtaining a product with a large coil and a uniform glass film. In this case, the glass coating is formed uniformly and densely, and thereafter, the glass coating is released from between the coil plates, and the additional oxidation due to the moisture and oxygen of the atmospheric gas is extremely effectively suppressed.

Further, this tight coating layer also suppresses the invasion of nitrogen from the atmospheric gas in the high temperature region and, conversely, the deinhibitor, thereby keeping the inhibitor stable up to the secondary recrystallization region.
The effect of improving the secondary recrystallization orientation is also obtained. The temperature rising rate below 850 ° C. and above 1100 ° C. in this temperature rising process is not particularly limited, but conditions such as 15 to 30 ° C./Hr are preferable in view of productivity and soaking degree of the coil.

[0032]

【Example】

[Example 1] C: 0.055% by weight%, Si: 3.3
0%, Mn; 0.130%, Si; 0.0080%, A
1; 0.028%, N; 0.072%, Sn; 0.04
% Of the steel ingot was heated to 1150 ° C. and hot rolled into a 2.3 mm hot rolled sheet. The steel sheet was annealed at 1120 ° C., pickled and cold rolled to a final sheet thickness of 0.23 mm. _{Then, N 2 25% + H 2} 75% in a continuous annealing line, decarburization annealing of 840 ° C. × 110 seconds in a wet atmosphere having a dew point of 67 ° C. and N ₂ 25%
+ H ₂ 75% + NH _{3 in} a dry atmosphere at 750 ° C x 3
The nitriding treatment was performed so that the amount of [N] in the steel for 0 seconds was 200 ppm. Then, as shown in Table 1, MgO100
6 g by weight of an annealing separator slurry containing a compound of a halogen element added to 5 parts by weight of TiO _{2 and} 5 parts by weight of TiO _2.
The coating was applied at a rate of / m ² , dried and wound on a coil.

Then, final finishing annealing was carried out at 1200 ° C. × 20 hours, and at this time, as shown in FIG. 1, the annealing was performed by changing the heating rate at the time of heating. Then, a coating agent consisting of 70 ml of 30% colloidal silica and 50 ml of 50% aluminum phosphate was applied as an insulating film agent so that the weight after drying and baking would be 5 g / m ^2, and it was applied in a continuous furnace at 850 ° C. for 30 seconds. Was subjected to heat flattening treatment to obtain the final product. Table 2 shows the results of the glass film formation conditions, insulating film properties, and magnetic properties in this test.

[0034]

[Table 1]

[0035]

[Table 2]

As a result of this test, when a halogen element compound was added as an annealing separator as in the present invention and gradual heating at 850 ° C. or higher according to FIGS. 1A and 1B was performed as finish annealing, In each case, a uniform and glossy thick glass film was uniformly formed, a glass film excellent in film tension and adhesion was formed, and very good magnetic properties were obtained. Especially, the cycle of FIG. 1 (B) was good. On the other hand, when a halogen compound was not added to the annealing separator of the comparative material, the glass coating and the magnetic properties tended to be considerably inferior to those of the present invention, particularly in the cycle shown in FIG. 1 (C).

[Example 2] C by weight%; 0.058%,
Si; 3.25%, Mn; 0.14%, Al; 0.03
0%, S; 0.0075%, N; 0.0075%, S
n: 0.05% grain-oriented electrical steel sheet slab was treated in the same manner as in Example 1 to give a final sheet thickness of 0.23 mm,
Decarburization annealing and nitriding annealing are performed, and the amount of [N] in the steel is 180 ppm
As the starting material. To this steel sheet, M as an annealing separator
5 parts by weight of TiO ₂ and Na ₂ B based on 100 parts by weight of gO
_As shown in Table 3, a slurry in which a halogen element compound was added to 0.3 parts by weight of ₄ O ₇ was applied, dried, and wound on a coil.

Then, FIGS. 2A, 2B, 2C,
As shown in (D), the holding temperature at the time of raising the temperature of the finish annealing was changed, and after annealing, the insulating coating treatment and the heat flattening treatment were performed to obtain the final product. The results of the glass coating and magnetic properties in this test are shown in Table 4.

[0039]

[Table 3]

[0040]

[Table 4]

As a result of this test, as in the present invention, a halogen element compound was added to the annealing separator, and the heat cycle of finish annealing was maintained at 950 to 1100 ° C. for a certain period of time (A), (B), ( In the case of C), both are uniform over the entire surface of the glass-coated coil and have excellent coating tension and adhesion,
The magnetic properties were also good. On the other hand, in the case of the comparative example in which the soaking holding temperature of finish annealing is low even when the same annealing separator is used in the present invention, the formation of the glass film is insufficient as compared with the present invention, and the film characteristics, magnetic properties Both the characteristics were inferior.
Further, even if the temperature rising condition of finish annealing is the cycle of the present invention, when the halogen element compound is not used as an additive, the glass coating is inferior to the present invention in thickness, uniformity and the like,
The magnetic properties were also poor.

[Example 3] The same slab as in Example 2 was treated in the same manner, and 100% by weight of MgO, 5 parts by weight of TiO ₂ and 0.3 part by weight of Na ₂ B ₄ O ₇ were applied to the steel sheet after nitriding. As shown in Table 5, the annealing separating agent added by changing the kind of the halogen compound is applied, dried, and then subjected to the final finishing annealing, and heat treatment is performed by the temperature rising cycle of FIGS. 1 (A) and 2 (A). I went. Then, in the same manner as in Examples 1 and 2, treatment with an insulating coating agent and heat flattening were performed to obtain a final product. Table 6 shows the results of the coating properties and magnetic properties in this test.

[0043]

[Table 5]

[0044]

[Table 6]

As a result of this test, a halogen element compound was added to the annealing separator and finish annealing was performed as shown in FIGS.
When the cycle of (A) was performed, the uniformity, tension, and adhesion of the glass coating were good, and in particular in the case of FIG. 2 (A) where the glass coating was held for a certain time, extremely good results were obtained. Was given. On the other hand, in the comparative example in which the halogen separating compound is not mixed with the annealing separator, the coating film at the edge part is not uniform and there is a part where the base iron can be seen through. The result is considerably inferior to the invention.

[0046]

According to the present invention, AlN, (Al, Si) N
In the glass film forming treatment of the low temperature slab heating material utilizing as an inhibitor, after adding the halogen compound into the annealing separator and finish annealing temperature rising process 850 to 1100 ° C. Heat up,
By carrying out purification annealing at 1200 ° C., the glass film forming reaction and the secondary recrystallization are separated and produced, and a grain coating and a grain-oriented electrical steel sheet excellent in magnetic properties are obtained. In the present invention, the reaction melting point lowering and accelerating effect of the glass element formation of the above-mentioned halogen element compound and the reaction accelerating effect by the heat cycle of finish annealing are extremely functionally matched, uniform before secondary recrystallization, and excellent in high tension. The development of a glass coating takes place.

[Brief description of drawings]

1 (A), (B) and (C) are charts showing heat cycles of finish annealing in Examples 1 and 3. FIG.

2 (A), (B), (C) and (D) are charts showing heat cycles of finish annealing in Example 2. FIG.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location C23C 22/00 A H01F 1/16 (72) Inventor Kenichi Yatsushiro 1--1 Hibahata-cho, Tobata-ku, Kitakyushu No. Nippon Steel Yawata Works (72) Inventor Katsuro Kuroki 46-59 Nakahara, Tobata-ku, Kitakyushu City In-house Nippon Steel Plant Design Co., Ltd. (72) Osamu Tanaka 46- Nakahara, Tobata-ku, Kitakyushu City 59 Nittetsu Plant Design Co., Ltd.

Claims (3)

[Claims] 1. C by weight%; 0.010 to 0.075
%, Si; 2.0 to 4.5%, S; 0.015% or less, acid-soluble Al; 0.010 to 0.035%, N; 0.012% or less, Mn; 0.05 to 0 .45%, the balance is Fe and the unavoidable impurities are electromagnetic steel slabs, which are slab-heated at a low temperature of 1280 ° C. or lower, and then hot-rolled, and cold-rolled once or twice with intermediate annealing interposed between them to obtain the final plate. In a method for producing a grain-oriented electrical steel sheet, which comprises thickening, decarburizing annealing and nitrogen annealing, applying an annealing separator, finishing annealing, and performing an insulating coating treatment, Mg as an annealing separator is used.
0.015 to 0.12, based on 100 parts by weight of O, one or more halogen compounds as F, Cl, Br, I
Apply 8 parts by weight of annealing separator,
A method for producing a glass coating and a grain-oriented electrical steel sheet having extremely excellent magnetic properties, which comprises heating at an average temperature rise rate of 50 to 1100 ° C. of 12 ° C./Hr or less and then performing high temperature finish annealing. 2. The halogen substance added to the annealing separator MgO is 0.015 to 0.012 as F, Cl, Br, I.
2. The glass film according to claim 1, which has an extremely high magnetic property, wherein one or more of an alkali metal compound and an alkaline earth metal compound are added in an amount of 0.010 to 0.50 parts by weight with respect to parts by weight. Excellent grain-oriented electrical steel sheet manufacturing method. 3. The glass coating according to claim 1 or 2, which is maintained at a constant temperature in the range of 5 to 20 Hr in the temperature range of 850 to 1100 ° C. of finish annealing, and the directional electromagnetic having extremely excellent magnetic properties. Steel plate manufacturing method.