JPH05320770A - Production of high magnetic flux density grain-oriented silicon steel sheet having no glass film - Google Patents

Abstract

PURPOSE:To manufacture a high magnetic flux density grain-oriented silicon steel sheet excellent in the capacity of core loss improving effect by magnetic domain subdividing by coating a steel sheet with a separation agent for annealing contg. an S compound of Li or the like by specified wt.pts. to MgO and added with chloride or the like of the same and thereafter executing annealing under specified conditions. CONSTITUTION:A silicon steel slab contg., by weight, 0.03 to 0.12% C, 2.5 to 4.5% Si or the like, and the balance Fe is subjected to hot rolling, annealing, rapid cooling, cold rolling, decarburizing annealing, the coating of a separation agent for annealing and final finish annealing, and heat flattening is executed to manufacture the objective grain-oriented silicon steel sheet; where it is coated with a separation agent for annealing contg. one or more kinds among S compounds of Li, Ca, Zn or the like by 5 to 20 wt.pts. to 100 wt.pts. of MgO and furthermore added with one or more kinds among the chloride, carbonate and nitrate of the elements by 2 to 20 wt.pts. As for the subsequent final annealing conditions, it is annealed in an atmosphere contg. <=25% N2 at the time of temp. raising to 700 to 1200 deg.C. In this way, the silicon steel sheet excellent in workabilities of cuttability, blanking properties or the like can be manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a grain-oriented electrical steel sheet having no glass coating (forsterite), which has excellent workability such as cutting property and punching property, and improves iron loss due to subdivision of magnetic domains. The present invention relates to a method of manufacturing a high magnetic flux density grain-oriented electrical steel sheet which is remarkably effective.

[0002]

2. Description of the Related Art Grain-oriented electrical steel sheets are generally used as soft magnetic materials, mainly as iron cores for transformers and other electric equipment, and are required to have good magnetic characteristics such as excitation characteristics and iron loss. In order to obtain good magnetic characteristics, it is important to highly align the <001> axis, which is the easy magnetization axis, with the rolling direction. Further, the plate thickness, crystal grain size, specific resistance, film and the like are also important because they have a great influence on the magnetic properties. The crystal orientation has been greatly improved by a method characterized by final cold rolling under high pressure using AlN and MnS as inhibitors, and at present, magnetic flux densities approaching theoretical values are being manufactured. It was

On the other hand, the use of grain-oriented electrical steel sheets in customers
When used, the coating properties and workability are important along with the magnetic properties.
It Normally, grain-oriented electrical steel sheets are formed during final finish annealing.
Surface treatment by a two-layer film consisting of a glass film and an insulating film
Has been done. Glass coating is decarburized with annealing separator MgO
SiO formed during annealing₂Forstella, a reaction product of
Ito (Mg₂SiO _Four) Is the main film. This
The ceramic film mainly composed of olsterite has a tensile effect.
Depending on the result, iron loss, magnetostriction, etc. are improved.
Depending on the condition, it may reduce the magnetic flux density or improve the iron loss.
Also has a significant effect. Furthermore, the film is hard and wears tools
It has strong properties, and it has slits and cuts when processing the magnetic steel sheet iron core.
Significantly adversely affects the durability of tools such as cutting and punching.
I'm sorry. For example, punching of grain-oriented electrical steel sheet with glass coating
When machining is performed, the mold wears out and the tool is struck several thousand times.
Due to the punching, the return of the punched sheet causes problems during use.
The more you twist it, the bigger it gets. Therefore, the mold must be polished or new.
Will need to be replaced. This improves work efficiency during iron core processing
As a result, the cost is lowered and the cost is increased.

From these problems, when a high-strength coating is applied by an insulating coating, magnetic domain subdivision processing is performed by other means, or conversely, the plate thickness is large and the iron loss characteristics cannot be expected to be improved due to the coating tension effect. In such a case, a grain-oriented electrical steel sheet having no glass coating is desired due to the above problems.
In particular, in recent years, as a technique for improving iron loss by subdividing magnetic domains, a technique for imparting local strain by optical, mechanical, or chemical means, or imparting linear or punctiform flaws to a steel plate surface has been developed. It has been found that, without the internal oxide layer of the film, such as the glass film, there is no pinning phenomenon of the domain wall during magnetization, and low iron loss can be obtained.

Therefore, the development of a high magnetic flux density grain-oriented electrical steel sheet having no glass coating is important in view of the purpose of obtaining an ultra-low iron loss material and various conditions of use by customers, and the development needs are increasing. There is. A method for producing a grain-oriented electrical steel sheet having no glass coating is disclosed in, for example, JP-A-53-22113. This is because when decarburizing annealing, the thickness of the oxide film is 3 μm or less, fine particles of alumina containing 5 to 40% of hydrous silicate mineral powder are used as an annealing separating agent, and this is applied to a steel sheet and finish annealing is performed to form an oxide film. It is said that a thin glass film is formed by blending a hydrated silicate to form a glass film that is easy to peel off, and a glass film having a metallic luster can be obtained. A method for suppressing the formation of a glass film by an annealing separator is disclosed in JP-A-56-65983.
20 parts by weight of an additive for removing impurities in aluminum hydroxide,
There is disclosed a method in which an annealing separator containing 10 parts by weight of an inhibitor is applied to a steel sheet to form a thin glass film of 0.5 μm or less. Also, JP-A-62-215225
In the gazette, one of the inventors of the present invention added 1 part of alkali metal or alkaline earth metal to 100 parts by weight of MgO.
There has been proposed an annealing separator for grain-oriented electrical steel sheets, which is formed by adding 2 to 40 parts by weight of one or more kinds. According to this, the glass film is not formed by the etching action of the chloride in the annealing separator on the SiO ₂ layer, and the grain-oriented electrical steel sheet having good punchability is obtained.

[0006] These conventional techniques have a magnetic flux density of 1.88, which is usually called an orient core, in a grain-oriented electrical steel sheet.
It is a technology based on the following low grade materials, and a technology for stably obtaining a grain-oriented electrical steel sheet having a high magnetic flux density as intended in the present invention has not yet been developed.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides punchability,
It has excellent workability such as slitting and cutting properties, and also has an excellent effect of improving iron loss characteristics in magnetic domain refinement treatment. It is an inexpensive manufacturing method for a uniform magnetic film-less (glassless) and high magnetic flux density grain-oriented electrical steel sheet. Is made for the purpose of providing.

[0008]

The high magnetic flux density grain-oriented electrical steel sheet according to the present invention has, as a steel component, C: 0.0 by weight.
30-0.12%, Si: 2.5-4.5%, Mn:
0.03 to 0.20%, S: 0.01 to 0.06%, acid-soluble Al: 0.01 to 0.05%, N: 0.0030 to
A silicon steel slab containing 0.012% and the balance of Fe and unavoidable impurities is hot-rolled by a known method, annealed, quenched, then pickled, and once or twice with an intermediate annealing. The basic steps are cold rolling to a final plate thickness, decarburization annealing, application of an annealing separator, and finish annealing. The method of obtaining the high magnetic flux density grain-oriented electrical steel sheet having no glass coating of the present invention in such components and steps is characterized by the decarburization annealing to finish annealing steps.

The final cold rolled material is decarburized and annealed in a continuous annealing line. By this decarburization annealing, C in the steel is removed and primary recrystallization is performed, and at the same time, an oxide film containing SiO ₂ as a main component is formed on the surface of the steel sheet. The amount of oxidation of the steel sheet at that time is 900 ppm or less in [O] amount, and FeO / S
iO ₂ (where FeO is FeO in Fe ₂ SiO ₄ ) ≦
It is set to 0.25. Decarburization annealing is N ₂ at 800 to 875 ° C.
It is performed by controlling P _H2O / P _H2 in a + H ₂ atmosphere. After that, the hydrated water content as an annealing separator is 0.5 to 5.
0, Mg, 100 parts by weight, at least Li, K,
Na, Ca, Mg, Zn, Fe, Mn, Cu, Sn, S
0.5 to 20 parts by weight of one or more S compounds of r and Al, and 2 to 20 parts by weight of one or more of chlorides, carbonates, nitrates and the like of these elements are added. It is coated with an annealing separator, dried and wound into a coil.

In the present invention, the finish annealing condition is an important elemental technology next to the annealing separator. In the final finish annealing atmosphere, N _{2 is} 25% or less and N under the composition conditions of the present invention.
It is carried out in an atmosphere containing a combination of ₂ + H ₂ or other inert gas. That is, as an inhibitor as in the present invention,
In the process of treating the component system using AlN and MnS, the secondary recrystallization start temperature is 950 to 1000 ° C., which is higher than that of the conventional low magnetic flux density orient core, so that the inhibitor is more stable. Highly demanded.

Therefore, in the technique of suppressing or decomposing the formation of the glass film as in the present invention, the change of the precipitate due to the atmospheric gas is suppressed by the glass film as in the conventional grain-oriented electrical steel sheet, or conversely. Since the effect of preventing deinhibitor from the steel is weakened, it is very difficult to obtain a grain-oriented electrical steel sheet having a high magnetic flux density without a glass film.

The present inventors have conducted extensive research and experiments on the above problems that could not be solved by conventional techniques, and as a result, newly developed conditions for decarburization annealing, an annealing separator, and finish annealing. It was a solution. The grain-oriented electrical steel sheet having no glass coating thus obtained is subjected to insulation coating treatment and heat flattening at 800 to 900 ° C. in a continuous line. When an ultra-low iron loss material is to be obtained, a depth of 5 to 30 μm and an interval of 2 to 30 μm by laser, tooth profile roll, press roll, scribing, local etching, etc., before or after this heat flattening.
A linear or point-like strain or groove is introduced in a direction of 45 to 90 ° with respect to the rolling direction at -15 mm.

After that, various insulating coating agents are applied and baked according to the purpose of use in the consumer. For the purpose of imparting film tension as an insulating film agent, a phosphoric acid-colloidal silica type film agent as disclosed in JP-B-53-28375 is applied and baked. Also, when good workability is required, an organic coating agent or a semi-organic coating agent may be treated on the steel plate after heat flattening, or an organic coating agent may be applied after treating the inorganic coating agent. It is processed and baked.

Next, the reasons for limiting the construction technique in the present invention will be described. As the starting material in the present invention, C: 0.03 to
0.12%, Si: 2.5-4.5%, Mn: 0.03
~ 0.20%, S: 0.01 to 0.06%, acid-soluble A
1: 0.01 to 0.05%, N: 0.0030 to 0.0
A silicon steel material containing 120% and the balance Fe and unavoidable impurities is used.

When C is less than 0.03%, the structure after high temperature winding becomes coarse and linear fine grains are generated in the product, which is not preferable. On the other hand, if it exceeds 0.12%, decarburization annealing requires a long time, which is industrially disadvantageous. Si is 2.5%
If less than 4.5, iron loss is deteriorated as a magnetic property, and if it is 4.5 or less.
If it exceeds%, cold rolling becomes difficult.

Mn and S are inhibitor-forming elements for suppressing the normal grain growth of primary recrystallized grains, and if they deviate from the above ranges, the product characteristics will be deteriorated and secondary recrystallization will not occur, which is not preferable. Acid-soluble Al is a basic element for obtaining a high magnetic flux density, and if it deviates from the above range, a high magnetic flux density cannot be obtained.

When N is less than 0.0030%, the precipitation amount of AlN which is an inhibitor is insufficient, and when it exceeds 0.012%, blister is generated in the product, which is not preferable. Oxidation and decarburization of the steel sheet during decarburization annealing are normally 800-875 ° C.
In order to control P _H2O / P _H2 in N ₂ + H ₂ atmosphere,
D. This is done by changing P. In decarburization annealing, in addition to primary recrystallization and decarburization, steel sheet oxidation occurs. Although the amount and quality of the oxide film are important in the conventional glass film forming technique, they also play an important role in the method for preventing the formation of the glass film of the present invention.

In the present invention, the [O] content of the steel sheet is 900 ppm.
And FeO / SiO ₂ is 0.25 or less (however, FeO is FeO in Fe ₂ SiO ₄ ). This is because the formation of a trace amount film in the glass film formation process and the weakening reaction of the inhibitor such as N invasion from the atmospheric gas, denitrification, deoxidation S, etc. caused the [O] content (SiO ₂ content, Fe ₂
This is because it is affected by the amount of SiO ₄ and FeO / SiO ₂ ). If the amount of [O] exceeds 900 ppm, the amount of SiO ₂ and Fe ₂ SiO ₄ in the oxide film inevitably increases and the thickness of the oxide film increases, which is disadvantageous in suppressing the glass film and performing the decomposition reaction during the final finish annealing. become.

That is, SiO ₂ remains just below the surface of the product, which weakens the workability improving effect and makes it difficult to obtain a uniform mirrorless glassless state. Furthermore, the formation of an excessive SiO ₂ film is caused by the inhibitor Al in the steel before the initiation of secondary recrystallization.
Since the decomposition reaction of N and the like is promoted, secondary recrystallized grains having a favorable orientation cannot be obtained. However, there is a problem that it takes a long time to decarburize if the amount of [O] is extremely suppressed. A preferred range is 400 to 700 ppm in [O] amount.

FeO / SiO ₂ in the oxide film is 0.2
It is defined as 5 or less. If it exceeds 0.25, the reactivity of the MgO and the SiO ₂ layer in the first half of the finish annealing increases and the amount of forsterite formed increases, so that even with the technique of the present invention, it is difficult to achieve uniform glasslessness. FeO / SiO
By defining ₂ ≦ 0.25, a uniform mirror surface condition can be obtained by the annealing separator of the present invention and finish annealing.

Next, as MgO used for the annealing separator, one having a hydration water content of 0.5 to 5.0% is applied. In the technology for achieving both glasslessness and high magnetic flux density according to the present invention, the effect of stabilizing an inhibitor by forming a small amount of film during the finish annealing temperature rising process is important, so the range is limited to this range. If the water content of hydration is less than 0.5%, the reactivity of the MgO grains will be extremely reduced, and a thin forsterite layer cannot be formed in the previous stage during the temperature rise of the finish annealing. Due to the destabilization, the magnetic flux density is lowered and a high magnetic flux density cannot be obtained. On the other hand, if it exceeds 5.0%, the dew point between the steel sheets is increased during the finish annealing temperature rise, and additional oxidation occurs in the former stage during the temperature rise, making it difficult to form a uniform glassless state.

The MgO-based annealing separator is at least Li, based on 100 parts by weight of MgO.
K, Na, Ca, Mg, Zn, Fe, Mn, Cu, S
0.5% of one or two or more S compounds of n, Cr and Al
.About.20 parts by weight, and 2 to 20 parts by weight of chlorides, carbonates, and nitrates of these elements are added. In the present invention, the point is that at least this S compound coexists in a certain amount. That is,
As shown in FIG. 1, when SnCl ₂ alone is added, N penetrates into the steel, but when an S compound is added, S penetrates into the steel in the temperature rising process of the finish annealing, which causes the penetration of N from the atmospheric gas. Produces a suppressive effect. As a result, the problem that a high magnetic flux density material could not be obtained even if glassless was achieved by adding chloride etc. to MgO, which has been proposed hitherto, was solved all at once by the synergistic effect with the finish annealing condition described later. It was possible.

The S compound is added in an amount of 0.5 to 20 parts by weight in the form of sulfide, polysulfide, sulfate or the like. 0.5
If it is less than the weight part, the amount of S diffused into the steel is insufficient and N
_{2 It is} not possible to suppress the influence on the precipitation state of AlN due to the penetration of N into the steel when annealed in a containing atmosphere. On the other hand, if it exceeds 20 parts by weight, it is not preferable because it adversely affects the etching of grain boundaries and the purification due to excessive S.

The chloride, carbonate and nitrate added at the same time are 2 to 20 parts by weight. These compounds are present on the surface of MgO and on the steel sheet oxide film to lower the reaction temperature of MgO and SiO ₂ , and then Fe in the film layer is etched to decompose the film layer and become glassless. If the amount is less than 2 parts by weight, the film forming reaction in the first stage and the etching decomposition reaction in the second stage are insufficient, and the glassless reaction becomes insufficient. If it exceeds 20 parts by weight, etching of grain boundaries and roughening of the steel sheet occur as in the case of the S compound, which is not preferable.

As described above, the presence of the S compound as the annealing separator and the coexistence of chloride, carbonate, nitrate and the like are indispensable, and a glassless product having a high magnetic flux density cannot be obtained regardless of which is missing. The finish annealing conditions are such that the temperature rising process from 700 ° C. to 1200 ° C. is limited to an atmospheric gas of N ₂ 25% or less. In the present invention, since AlN is used as the main inhibitor, when N invades in the glassless reaction process, the precipitation state of the inhibitor AlN is affected or the magnetic flux density is lowered. 700-1200 in the temperature rising process
It is 7 that the temperature range between ° C is defined as an atmosphere gas containing 25% or less of N _2.
This is because N does not penetrate into the steel sheet and additional oxidation does not occur up to 00 ° C. If the N ₂ content exceeds 25%, this effect is large, so the content is limited. The most preferable condition is H ₂ atmosphere 100%, but if N _{2 is} 10% or less, extremely good magnetism can be stably obtained.

The steel sheet after finish annealing is subjected to a laser, tooth profile roll, press, scribing, before or after coating with an insulating film agent and baking.
A linear flaw is provided by local etching or the like. The condition of linear flaw depends on the usage condition in the customer. A large strain iron core that is not subjected to strain relief annealing during use is subjected to local strain imparting treatment by a laser or the like. On the other hand, when a strain relief annealing step is used during use, such as a wound core, the state of linear flaws is important, and the linear flaws have a depth of 5 to 30 μm and an interval of 2 to 2 μm.
It is applied in a direction of 45 to 90 ° with respect to the rolling direction at 15 μm. The width of the linear flaw is not specified, but it is better to be as narrow as possible. If the flaw depth is less than 5 μm, the effect of improving the iron loss value after annealing is small, and if it exceeds 30 μm, the magnetic flux density decreases, which is disadvantageous when considering the characteristics in a high magnetic field.

After that, as the insulating film agent to be baked, an inorganic film material, an organic film material, or a semi-organic film agent is processed according to the application. In the case where a tension effect and heat resistance are required, a coating agent containing colloidal silica and phosphate as a main component or a treatment agent containing only phosphoric acid is applied and baked. In the case where processability is required, resins such as acrylic, styrene, vinyl acetate, epoxy, popal, melamine, etc. and their cross-linked products, copolymers, etc. and inorganic substances such as chromate, phosphate etc. The semi-organic film formed from the mixture is used by being subjected to one or more baking treatments.

The mechanism for obtaining the high magnetic flux density grain-oriented electrical steel sheet having no glass coating according to the present invention is considered as follows. In the present invention, an oxide film having an appropriate amount of oxidation and components formed during decarburization annealing and low hydrated MgO
First, a thin film layer of the glass film is formed by the S compound added to the above and another glass film formation inhibitor in the pre-heating region of the finish annealing temperature rise, and a film layer is formed to prevent weakening of the inhibitor by the deinhibitor or the atmosphere. .. Next, after the temperature is raised, the glass film is decomposed and peeled by the chemical etching of Fe in the film layer, and the thermal etching is simultaneously generated during the subsequent high temperature soaking, whereby glassless and mirror-finished are obtained. During this period, the glass thin film formation and the effect of the S compound and the synergistic effect of controlling the amount of N _{2 in the} atmospheric gas do not cause the intrusion of N into the steel, the inhibitor is kept stable up to the secondary recrystallization region, and the high magnetic flux density is obtained. The secondary recrystallized grains of are obtained.

It is believed that the completion of the glassless reaction in the finish annealing process brings about a mirror-finished surface and further improves the iron loss. Further, in the magnetic domain refining process to be subsequently performed, since the material of the present invention does not have the pinning phenomenon of the domain wall movement because it does not have the internal oxide layer of the glass coating, it has an extremely low iron loss in combination with the high magnetic velocity density and the mirror effect. Is considered to be obtained.

[0030]

EXAMPLES Example 1 C: 0.070% by weight, Si: 3.22%, Mn:
0.060%, S: 0.025%, Al: 0.030
%, N: 0.0080%, hot-rolled material for high magnetic flux density grain-oriented electrical steel sheet consisting of balance Fe and unavoidable impurities,
It was pickled and cold rolled to a final plate thickness of 0.225 mm. This steel sheet was provided with N ₂ 25% + H ₂ 75%, D.I. 850 in P65 ℃
Decarburization annealing was performed at 90 ° C for 90 seconds to obtain a test material. The amount of oxidation of the steel sheet at this time was 800 ppm as [O]. The annealing separator having the composition shown in Table 1 was applied to this steel sheet, and
Final finishing annealing was performed under the atmosphere conditions shown in (A), (B), and (C). Then, a linear flaw is applied to this steel plate by a press having a tooth width of 50 μm at a depth of 15 μm and an interval of 5 mm in a direction perpendicular to the rolling direction, and then as an insulating film agent, 20% colloidal silica 100 ml + 50% Mg (H ₂ PO ₄ ) ₂ 25 ml +
A solution consisting of 25 ml of 50% Al (H ₂ PO ₄ ) ₃ +5 g of CrO ₃ was applied so that the weight after baking was 6 g / m ² , and heat flattening treatment and baking treatment were performed at 850 ° C. for 30 seconds. Table 2 shows the film properties and magnetic properties of the steel sheet surface at this time.

As a result, all of the products according to the present invention did not form a glass film on almost the entire surface and exhibited metallic luster, and the punchability was good. Further, the magnetic characteristics were very good due to (A) and (B) having a low N ₂ partial pressure in the temperature rising atmosphere. However, in the case where the N ₂ partial pressure is high (C), the magnetic flux density is remarkably reduced, and in the case where the S compound is not contained as the annealing separator, the magnetic flux density is considerably low even in the finish annealing atmospheres (A) and (B). It was a result.

[0032]

[Table 1]

[0033]

[Table 2]

Example 2 The same material coil as in Example 1 was treated in the same manner to obtain a cold rolled sheet having a final sheet thickness of 0.29 mm. Then N ₂ 25% +
H _{2 at} 75% D.I. Change P, (1) oxygen amount 450p
pm, (2) 700 ppm, (3) 950 ppm and decarburized and annealed. Thereafter, the annealing separator having the composition shown in Table 3 was applied to this steel sheet, and the final annealing was performed in the cycle shown in FIG. 2 (B). Next, 100 ml of 20% colloidal silica + 50 ml of Al (H ₂ PO ₄ ) ₃ 50 ml + C
A coating agent consisting of 5 g of rO _{3 was} used in a weight of 6 after baking.
The coating was applied so as to be g / m ² , and baking treatment was performed at 830 ° C. for 30 seconds. After that, the steel sheet is subjected to distortion treatment in a direction perpendicular to the rolling direction with an interval of 5 mm, an irradiation width of 0.2 mm and a depth of 2 μm to obtain a product, and an acrylic resin base is used in another line for corrosion resistance and workability improvement. The semi-organic film was coated with 0.3 g / m ^{2 by} weight after baking, and baked at 300 ° C. Table 4 shows the film properties and magnetic properties of the products.

As a result, with the annealing separator of the present invention, the glass film was not uniformly formed under the conditions of [O] amounts of 400 and 700 ppm, and the punchability and magnetic properties were remarkably good. However, even when the annealing separator used in the present invention was used, a slightly thin glass film was formed under the condition that the amount of [O] was 950 ppm, and the punchability and magnetic properties were considerably poor. When the annealing separator was a comparative example, a glass film was formed and the punchability was remarkably poor, and both magnetism and glasslessness were not compatible.

[0036]

[Table 3]

[0037]

[Table 4]

Example 3 The same material coil as in Example 1 was treated in the same manner to obtain a cold rolled sheet having a final sheet thickness of 0.225 mm. Then N ₂ 25% + H
₂ 75%, D. Decarburization annealing was performed at P62 ° C. The amount of steel plate [O] at this time was 700 ppm. The annealing separator having the composition shown in Table 5 was applied to this steel sheet, and the final annealing was performed as shown in FIG.
It carried out on the conditions shown in. Using a tooth profile roll on this steel plate,
Spacing 5 mm, width 30 μm, depth 1 in the direction perpendicular to the rolling direction
Apply a linear flaw of 5 μm, then apply 20
% Colloidal silica 100 ml + 50% Al (H ₂ PO
₄ ) A solution consisting of 60 ml of ₃ + 7 g of CrO ₃ was applied so that the weight after baking would be 6 g / m ² , and the temperature was 880 ° C × 30.
Baking and distortion removal processing were performed for 2 seconds. Table 6 shows the surface condition and magnetic property results of the steel plate in this experiment.

As a result, in the case where the addition amount of CaCl ₂ was changed to MgSO ₄ , CaC of the present invention 2 and 3 was added.
With l _{2 of} 7 and 15 g, glasslessness was uniform and the magnetism was good. However, with the addition amount of 30 g in Comparative Example 1, the surface was roughened and the magnetism was deteriorated. Also, MnS
In the cases of 4 to 6 in which the addition amounts of O ₄ and CaS were changed, uniform glassless progressed and magnetism was good in all cases.
6 was good.

On the other hand, when the S compound alone was used as the additive, no glassless reaction was observed. When only the chloride and carbonate were used, the glassless reaction was sufficient, but the magnetism was very poor.

[0041]

[Table 5]

[0042]

[Table 6]

[0043]

According to the present invention, the amount of oxidation in decarburization annealing is set to a specific amount, the additive S compound of the annealing separator is used in combination with chloride, nitrate, carbonate, etc., and the atmosphere gas at the time of finish annealing. Since the glass film is not formed by controlling the amount of N _{2 in the} inside, a high magnetic flux density grain-oriented electrical steel sheet having good iron core workability and excellent iron loss improving effect by magnetic domain refinement can be obtained.

[Brief description of drawings]

1 (A) and 1 (B) are the steel sheets in the case where the final finishing annealing condition is N ₂ 10% + H ₂ 90% in the atmosphere after the temperature rising and 700 ° C. (FIG. 2 (B) type). It is a figure showing N and S in relation to an annealing separation agent composition.

2 (A), (B), and (C) are diagrams showing a thermal cycle and an atmospheric condition in finish annealing. (A) and (B) are examples in which the atmosphere after 700 ° C. when raising the temperature under the atmospheric conditions of the present invention is N ₂ 25% or less, and (C) is the atmosphere in the comparative example when raising the temperature is N ₂ 30%. This is an example of the case.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location C23C 22/00 A (72) Inventor Masao Ono 1-1 No. 1 Hibatacho, Tobata-ku, Kitakyushu, Fukuoka New Nippon Steel Co., Ltd., Yawata Works

Claims (4)

[Claims] 1. C: 0.03 to 0.12% by weight, S
i: 2.5 to 4.5%, Mn: 0.03 to 0.20%,
S: 0.01 to 0.06%, acid-soluble Al: 0.01 to
0.05%, including N: 0.0030 to 0.012%,
Hot rolling a silicon steel slab consisting of the balance Fe and unavoidable impurities, annealing and quenching treatment before the final cold rolling step, cold rolling to a final plate thickness, decarburization annealing, and applying an annealing separator, In a method for producing a grain-oriented electrical steel sheet, comprising performing final finish annealing and heat flattening, at least Li, K, Na, Ca, Mg, Z relative to 100 parts by weight of MgO.
One or two or more S compounds of n, Fe, Mn, Cu, Sn, Sr, and Al are contained in an amount of 0.5 to 20 parts by weight, and further, one or two of chlorides, carbonates, and nitrates of the above elements. A glass characterized by applying an annealing separator containing 2 to 20 parts by weight of the above seeds and then annealing as a final finishing annealing condition at an elevated temperature of 700 ° C. to 1200 ° C. in an atmosphere of N ₂ 25% or less. A method for producing a high magnetic flux density grain-oriented electrical steel sheet having no coating. 2. The method according to claim 1, wherein, before or after the heat flattening treatment, a linear or dotted flaw is 45 to 90 in the rolling direction by laser, tooth roll, press, scribe, local etching or the like. A method for manufacturing an ultra-low iron loss high magnetic flux density grain-oriented electrical steel sheet having no glass coating, which is characterized by performing an insulating coating treatment after application in the direction of °. 3. The oxygen basis weight in decarburization annealing is 900 p.
pm or less and FeO / SiO ₂ ≦ 0.25 in the oxide film
3. The method for producing a high magnetic flux density grain-oriented electrical steel sheet having no glass coating according to claim 1 or 2. 4. The high magnetic flux density directional electromagnetic wave having no glass film according to claim 1 or 2, wherein the hydrated water content of MgO used as the annealing separator is 0.5 to 5.0%. Steel plate manufacturing method.