JP4569281B2 - Annealing separator for grain-oriented electrical steel sheet, method for annealing grain-oriented electrical steel sheet, and method for producing grain-oriented electrical steel sheet - Google Patents

Description

  The present invention relates to an annealing separator that prevents seizure of grain-oriented electrical steel sheets during annealing, and an annealing method using the same. The present invention also relates to a method for producing a grain-oriented electrical steel sheet using the annealing separator. Here, the grain-oriented electrical steel sheet includes those having a forsterite film and those having no forsterite film, but the present invention relates to each manufacturing method.

  Electrical steel sheets are widely used as iron core materials for transformers and rotating machines. Among them, grain-oriented electrical steel sheets are steel sheets that have achieved particularly excellent low iron loss by highly accumulating crystal orientations in {110} <001> orientations called Goss orientations. Of the characteristics required for electrical steel sheets, iron loss characteristics are particularly important because they are directly linked to product energy loss.

  Moreover, punchability and bending workability are also important characteristics in electrical steel sheets. That is, when producing the iron core of a transformer or a rotary machine, the electromagnetic steel sheet is formed into a predetermined shape through processing such as punching, shearing and bending. Further, when the steel strip passes through a processing line for performing these processes, the steel plate is bent. Therefore, the above characteristics are important.

  In general, grain-oriented electrical steel sheets are manufactured by a process disclosed in paragraph [0005] of Patent Document 1. That is, the steel sheet obtained by rolling is subjected to recrystallization annealing, and then subjected to one batch annealing called finish annealing. Secondary annealing is promoted by this batch annealing, and goth-oriented crystal grains are accumulated.

By the way, in batch annealing, a steel plate is heated in a coil shape. However, since finish annealing for producing a grain-oriented electrical steel plate generally needs to be performed at a high temperature, the steel plates are seized in the coil. In order to prevent this seizure, a technique of applying an annealing separator mainly composed of MgO and forming a forsterite film during annealing is widely used. The forsterite film is considered to be formed by the reaction of MgO in the annealing separator and SiO ₂ in the oxide formed on the steel sheet surface (however, the film also contains Fe) )

  This forsterite film has good annealing separation performance and also has an advantageous surface for the properties of grain-oriented electrical steel sheets. For example, a hard coating (tensile film) can be applied with good adhesion on the forsterite film, and low iron loss can be achieved by applying tension to the steel sheet.

  On the other hand, since the forsterite film is a hard glass film, the grain-oriented electrical steel sheet having the forsterite film is inferior in both punchability and bending workability. That is, there is a problem that the die for punching is worn quickly or burr is generated on the shearing surface of the steel plate. Further, since peeling easily occurs during bending, for example, good bending peel resistance that does not peel even when subjected to processing such as bending after strain relief annealing is required.

To solve these problems,
(1) A method for producing a grain-oriented electrical steel sheet without forming a forsterite film itself, which is disadvantageous for workability, as a means of obtaining a grain-oriented electrical steel sheet having good workability (emphasizing workability),
(2) Emphasizing low iron loss and the like, and a method of forming a forsterite film having good bending peel resistance that does not peel even if subjected to processing such as bending after strain relief annealing has been proposed.

As the method of (1), there is a method of changing the components of the annealing separator, that is, a method of applying an annealing separator that does not contain MgO that reacts with SiO _{2 on the} surface of the steel sheet after recrystallization annealing and performing a final annealing. Has been tried.

  Here, as an annealing separation agent mainly composed of other than MgO, those disclosed in Patent Document 2, Patent Document 3 and Patent Document 4, which are mainly composed of alumina (powder), Patent Document 5 and Patents. A material mainly composed of alumina and / or silica disclosed in Document 6 is known. These annealing separators are applied electrostatically, or applied to the steel sheet as a suspension in water slurry or alcohol. However, since these annealing separators have poor adhesion to the steel sheet, the production line after the annealing separator application is easily peeled into the plate. As a result, 1) it is difficult to control the coating amount. 2) The yield of the annealing separator is poor. 3) There were problems such as generation of dust and concerns about line contamination.

  As an annealing separator having excellent adhesion to a steel plate, Patent Document 7 discloses an annealing separator mainly composed of a colloidal alumina aggregate in a feather-like form. However, this annealing separator has a problem in that it is difficult to uniformly apply it to the steel sheet. In addition, this annealing separator is inconvenient in operation because it requires a removal step by acid washing or alkali washing before further forming an insulating film.

  After all, in the past, once the forsterite film is formed, the costly and laborious method of removing the forsterite film by means such as pickling, chemical polishing or electrolytic polishing is the most practical method. Has been done.

  An attempt has been made to produce a grain-oriented electrical steel sheet with good workability without using an annealing separator. For example, Patent Document 8 proposes a technique for secondary recrystallization of goth-oriented crystal grains in a component system that does not contain an inhibitor-forming component, and this method lowers the finish annealing temperature and eliminates the need for an annealing separator. Yes. However, the finish annealing of the grain-oriented electrical steel sheet is not at a level that can completely prevent the steel sheet from being seized even at a low temperature, and has a problem from the viewpoint of stable production.

  On the other hand, as a method of (2), Patent Document 1 discloses a technique that achieves both magnetic properties and film properties by performing two batch annealings after continuous recrystallization annealing. That is, in the conventional technique, both the progress of secondary recrystallization and the formation of a forsterite film are realized in finish annealing. However, since the optimum annealing conditions do not match, the film characteristics deteriorate when attempting to improve the magnetic characteristics, and conversely, the magnetic characteristics deteriorate when attempting to improve the film characteristics. On the other hand, the technique disclosed in Patent Document 1 achieves the function of finish annealing by two batch annealings, promotes secondary recrystallization by the first batch annealing, and forms by the second batch annealing. It is intended to form a stellite film.

In this publication, if there is a concern about adhesion between steel plates during the first batch annealing, an annealing separator may be applied. However, if an annealing separator containing MgO as the main component is used for the first batch annealing after recrystallization annealing, the forsterite film formation in the second batch annealing will be adversely affected and good coating properties will be obtained. Becomes very difficult. Moreover, in the method of Patent Document 1, it is preferable to perform decarburization after the first batch annealing, but a coating such as a forsterite coating also has a disadvantage of inhibiting decarburization.
On the other hand, when the first batch annealing is performed without using the annealing separator mainly composed of MgO, the same problems as in (1) occur.
JP 2003-41323 A JP-A-6-136448 JP 7-118750 A Japanese Unexamined Patent Publication No. 5-156362 JP 11-61261 A Japanese Patent Laid-Open No. 8-134542 Japanese Patent Laid-Open No. 10-121142 JP 2000-129356 JP

  The present invention has been made in order to solve the above-mentioned problems, does not contain MgO, is excellent in the coating property to the steel sheet and the adhesion after coating, direction without causing dust problem and thereby line contamination An annealing separator capable of producing a heat-resistant electrical steel sheet and an annealing method using the same are proposed. Moreover, this invention proposes the manufacturing method of a grain-oriented electrical steel sheet suitable for the iron core material of a transformer or a rotary machine using the annealing separation agent. In particular, the present invention proposes a grain-oriented electrical steel sheet having excellent forsterite-coated film characteristics and a method for producing a grain-oriented electrical steel sheet having no forsterite-coated film and excellent workability.

Embodiments of the present invention include (1) an annealing separator for grain-oriented electrical steel sheets, (2) a method for annealing grain-oriented electrical steel sheets, (3) a method for producing grain-oriented electrical steel sheets having a forsterite coating, and (4) It is classified into the manufacturing method of the grain-oriented electrical steel sheet which does not have a stellite film.
(1) Annealing separator for grain-oriented electrical steel sheet The present invention contains an Al compound in the form of a solution or a colloidal solution, contains a compound that is stable at high temperatures, and further has a viscosity of 25 mPa · s or less. It is an annealing separator for heat-resistant electrical steel sheets.

  After the application of the annealing separator, it is preferable to perform a baking process for baking the annealing separator.

  Here, a compound that is stable at a high temperature means that the compound does not react or hardly react with the surface of the steel sheet or the oxide on the surface of the steel sheet during annealing, and the compound itself does not react or reacts. It is difficult to wake up. Specifically, at least one selected from the group of Si compounds, Sr compounds, Ca compounds, Zr compounds, Ti compounds and Ba compounds is exemplified. MgO alone is stable even at high temperatures, but reacts with oxides on the surface of the steel sheet, so it does not fall under “stable at high temperatures” here.

  Here, since the Al compound is in a solution state or a colloid solution state, it is a substance having a structural part (functional group or the like) having an affinity for a solution or a liquid forming the colloid solution (generally referred to as a solvent for convenience). . Therefore, it is a substance that is chemically different from, for example, alumina particles used in general slurries and suspensions. Needless to say, the existing form is different from the slurry or suspension.

  The solvent is preferably based on water. Further, the Al compound is at least one of an Al compound having a hydroxyl group and an organic acid group, and a dehydration reaction product (including some dehydration reaction products) of an Al compound having a hydroxyl group and an organic acid group. preferable. More preferably, the Al compound includes basic acetic acid Al, basic formic acid Al, basic hydrochloric acid Al, basic nitric acid Al, basic oxalic acid Al, basic sulfamic acid Al, basic lactic acid Al, and basic citric acid. One or a mixture of two or more selected from Al.

That is, the present invention further includes at least one compound selected from the group consisting of an Si compound, an Sr compound, a Ca compound, a Zr compound, a Ti compound, and a Ba compound, containing the Al compound in a solution or colloidal solution state. The grain-oriented electrical steel sheet, wherein the content of the Al compound is 40 to 95 mass% in a solid content ratio represented by the following formula (2), and the viscosity of the annealing separator is 25 mPa · s or less. It is an annealing separator.

Here, the solid content ratio of the Al compound = (solid content of the Al compound) / {(solid content of the Al compound) + (solid content of the at least one compound (sum))}. 2)
Here, the solid content of each compound is a value converted to the weight of each compound below.
Al compound: Al ₂ O ₃ , Si compound: SiO ₂ ,
Sr compound ... SrO, Ca compound ... CaO,
Zr compound ... ZrO ₂ , Ti compound ... TiO ₂ ,
Ba compound: BaO.

  Here, the annealing separator may contain at least one compound selected from the group consisting of the Si compound, Sr compound, Ca compound, Zr compound, Ti compound and Ba compound in a solution or colloidal solution state. Good.

In a particularly preferred aspect of the invention, the annealing separator is a value in which the Al compound and the Si compound are the main components, and the ratio of the Al compound and the Si compound is converted to Al ₂ O ₃ / (Al ₂ O ₃ + SiO ₂ ). It is an annealing separator for grain-oriented electrical steel sheets that has a viscosity of 40 to 95 mass%, a viscosity of 25 mPa · s or less, and a solution or a colloidal solution.

In the above invention, the annealing separator may further contain S or a compound containing S in an amount of 25 mass% or less in a solid content ratio obtained when baking is performed after the annealing separator is applied. The “S or S-containing compound” is preferably at least one selected from Sr sulfate, Mg sulfate, and Mg sulfide.
(2) An annealing method for grain-oriented electrical steel sheets.

The present invention relates to a method for annealing a grain-oriented electrical steel sheet by applying an annealing separator to a steel sheet and annealing the applied steel sheet, wherein the annealing separator is an annealing separator that does not contain MgO, and Al The compound is contained in the form of a solution or a colloidal solution, and further contains at least one compound selected from the group of Si compound, Sr compound, Ca compound, Zr compound, Ti compound and Ba compound, and the inclusion of the Al compound An annealing separator for grain-oriented electrical steel sheets, characterized in that the amount is 40 to 95 mass% in terms of the solid content ratio represented by the following formula (2), and the viscosity is 25 (mPa · s) or less.
Solid content ratio of Al compound = (solid content of Al compound) / {(solid content of Al compound) + (solid content of the at least one compound (sum))} Equation (2)
Here, the solid content of each compound is a value converted into the weight of each compound below:
Al compound: Al2O3, Si compound: SiO2,
Sr compound: SrO, Ca compound: CaO,
Zr compound: ZrO2, Ti compound: TiO2,
Ba compound: BaO.

  After the application of the annealing separator, it is preferable to perform a baking process for baking the annealing separator.

In addition, all of the suitable annealing separators described in (1) can be applied to the method for annealing the grain-oriented electrical steel sheet (2).
(3) Method for producing grain-oriented electrical steel sheet having forsterite film The present invention provides C: 0.08 mass% or less, Si: 2.0-8.0 mass%, Mn: 0.005-1.0 mass%. Slab made from molten steel containing,
A slab made of molten steel having a composition in which Al is reduced to 150 ppm or less and N, S, and Se are each reduced to 50 ppm or less, and the balance is Fe and inevitable impurities .
Alternatively, when using at least one of AlN, BN, MnSe, and MnS as an inhibitor, when using AlN, Al: 0.015-0.04 mass% and N: 0.005-0.015 mass%, In the case of using B: 0.001 to 0.006 mass% and N: 0.005 to 0.015 mass%, and in the case of using MnSe and / or MnS, at least one of Se and S is 0.005. a step of the steel sheet was rolled either slab slabs were prepared 0.06 mass% from the molten steel consisting of unrealized balance of Fe and unavoidable impurities (thin slab or the like including. the same applies hereinafter) to a final thickness, wherein A step of subjecting the steel plate to recrystallization annealing, and a first batch annealing step of subjecting the steel plate to batch annealing by the annealing method described in (1). Here, when the annealing separator applied before annealing in the first batch annealing step is referred to as a first annealing separator, the recrystallization annealing is performed by applying the first annealing separator. It is applied before or after the application of the first annealing separator and before the batch annealing, and the coating amount per one side of the first annealing separator. 0.005 to 5 g / m ^2, and then a step of subjecting the steel plate to continuous annealing, a second annealing agent containing MgO on the steel plate, and then subjecting the steel plate to batch annealing. It is a manufacturing method of the grain-oriented electrical steel sheet which has a process.

This grain-oriented electrical steel sheet is excellent in magnetic properties and coating properties of a forsterite coating.
(4) Method for producing grain-oriented electrical steel sheet having no forsterite coating The present invention is C: 0.08 mass% or less, Si: 2.0-8.0 mass%, Mn: 0.005-1.0 mass% a slab made from molten steel containing, 150 ppm of Al or less, N, slabs have a composition having reduced S, each of 50ppm or less Se, were prepared from molten steel balance consisting of Fe and unavoidable impurities,
Alternatively, when using at least one of AlN, BN, MnSe, and MnS as an inhibitor, when using AlN, Al: 0.015-0.04 mass% and N: 0.005-0.015 mass%, In the case of using B: 0.001 to 0.006 mass% and N: 0.005 to 0.015 mass%, and in the case of using MnSe and / or MnS, at least one of Se and S is 0.005. a step of a rolled to steel sheets of 0.06 mass% to a final thickness of any slab slabs made from molten steel consisting of unrealized balance of Fe and unavoidable impurities, the step of applying recrystallization annealing to the steel plate And a final annealing step in which batch annealing is performed on the steel sheet by the annealing method described in (1), wherein the recrystallization annealing is performed in the finishing process. Either before application of the annealing separator in the step of annealing, or after application of the annealing separator according to (1) and before the batch annealing, and wherein the 0.005~5g / ^{m 2} coating amount per one side of the annealing separator, a method for producing a grain-oriented electrical steel sheet.

  This grain-oriented electrical steel sheet is excellent in magnetic properties and workability.

Further, (3) and (4) In any of the invention, the steps the step, of the pre kiss Love and hot rolled to hot-rolled steel sheet and the steel sheet is rolled slab to the final thickness The step of performing hot-rolled sheet annealing to anneal the hot-rolled steel sheet as necessary, and the process of performing one cold rolling or two or more cold rolling sandwiching the intermediate annealing to obtain the final sheet thickness It is preferable to have.

A further preferred embodiment of the invention of (4) includes C: 0.08 mass% or less, Si: 2.0-8.0 mass%, Mn: 0.005-1.0 mass%, and when using AlN as an inhibitor Is Al: 0.015-0.04 mass% and N: 0.005-0.015 mass%, and when BN is used, B: 0.001-0.006 mass% and N: 0.005-0.015 mass% the, MnSe and / or in the case of using MnS Se, hot rolling heat the slab produced at least any one kind of 0.005～0.06Mass% from molten steel consisting of unrealized balance Fe and unavoidable impurities S A step of performing a cold rolling or an intermediate annealing twice or more and then a cold rolling of two or more times to obtain a final plate thickness, and a step of performing a recrystallization annealing. If, then comprising the step of subjecting the finish annealing in the annealing method described in (2), and the coating amount of the annealing separator to be applied before annealing in the final annealing as per one side 0.005~5g / m ² Or a method for producing a grain-oriented electrical steel sheet, or C: 0.08 mass% or less, Si: 2.0-8.0 mass%, Mn: 0.005-1.0 mass%, and Al 150 ppm or less and N, S, and steps that prolong Netsukan圧slabs produced from molten steel, each consisting of chromatic and balance of Fe and unavoidable impurities component composition was reduced to 50ppm or less Se, then one cold rolling or intermediate annealing And a step of performing cold rolling at least twice to sandwich the final thickness, a step of performing recrystallization annealing, and a step of performing final annealing by the annealing method described in (2), and The finish firing The coating amount of the annealing separator to be applied to one surface per 0.005~5g / m ² before the annealing in a manufacturing method of the grain-oriented electrical steel sheet.

In this preferred aspect of the invention, the annealing separator is mainly composed of an Al compound and a Si compound, and the ratio of the Al compound to the Si compound is converted to Al ₂ O ₃ / (Al ₂ O ₃ + SiO ₂ ). The value is 40 to 95 mass%, the viscosity is preferably 25 mPa · s or less, and the solution or colloidal solution is preferable.

  According to the present invention, an annealing separator that is excellent in applicability to a steel sheet and adhesion after application, can produce a grain-oriented electrical steel sheet without causing dust problems and resulting line contamination, and an annealing method using the same. Propose. Moreover, this invention can manufacture the grain-oriented electrical steel sheet suitable for the iron core material of a transformer or a rotary machine using the annealing separator. In particular, a grain-oriented electrical steel sheet having excellent forsterite-coated film characteristics and a grain-oriented electrical steel sheet having no forsterite-coated film and excellent workability can be produced. Furthermore, the production method of the present invention can ensure stable operation in the annealing separator coating process and the subsequent processes, achieves adhesion, and does not impede purification or decarburization. It also has excellent operability, such as no need for film removal.

  As a result of intensive research on an annealing separator excellent in coating properties and adhesion after coating, the inventors have first made an Al compound and a compound stable at high temperatures, and at least the Al compound is a solution. It has been found that the above problems can be solved by being in a state or a state of a colloidal solution. The present inventors also found a suitable viscosity of the annealing separator, a solid content ratio of the Al compound, and a suitable coating amount when applied to a steel sheet. In the following, the present invention will be described based on experiments that have led to success.

  mass%, C: 0.020%, Si: 3.30%, Mn: 0.070% and Sb: 400ppm, Al: 38ppm, N: 33ppm, S: 18ppm, Se: Less than 10ppm (below the analysis limit) A steel slab having a component composition was produced by continuous casting. Thereafter, the steel slab was subjected to one cold rolling or two or more cold rollings sandwiching intermediate annealing to obtain a final thickness. Next, the cold-rolled steel sheet was subjected to recrystallization annealing and finish annealing.

Here, before finishing annealing, an aqueous colloidal solution of silica sol (colloidal silica) (solid content concentration: 3.0 mass%) is used as the annealing separator, and the range of 0.1 to 3.0 g / m ² per side on the steel plate surface (both sides) Then, it was applied using a roll coater.

  After the application, the steel sheet was baked under the condition that the steel sheet reached a temperature of 250 ° C. and then allowed to cool. The adhesion amount of the annealing separator was determined from the difference in steel plate weight before coating and after baking treatment, and this was used as the coating amount of the annealing separator.

  In the final annealing, after holding in a nitrogen atmosphere at 850 ° C. for 30 hours, holding in an Ar atmosphere at 1000 ° C. for 5 hours.

  About the obtained steel plate, the test was done about three items, the applicability | paintability of an annealing separator, the adhesiveness of the annealing separator after drying, and the annealing separation effect at the time of final annealing.

Details of each performance evaluation method are as follows. The same applies to the evaluation methods in Experiments 2 and 3 and Examples described later.
-Application | coating property The steel plate after apply | coating an annealing separator was evaluated visually.

○: The whole steel plate is uniformly applied. △: It is applied to the whole but is uneven. ×: There are places where it is applied and not. ・ Adhesiveness after drying After baking the annealing separator, The steel plate was washed under running water for 10 seconds under a flow rate of about 1.0 m / s. Then, it drained with the ringer roll and it was made to dry on 200 degreeC * 10s conditions. Then, the steel plate weight was measured again and the adhesion amount of the annealing separator was calculated again. And the difference of the annealing separation agent adhesion amount before and after water washing was calculated | required, and this was made into peeling amount. Based on the obtained peeling amount, it evaluated as follows.

○: Peeling amount of annealing separator is 10% or less of coating amount △: Peeling amount of annealing separator is more than 10 to less than 80% of coating amount ×: Peeling amount of annealing separator is 80% or more of coating amount ・ Annealing Separation effect Annealing separator was applied and finish annealing was applied while applying a pressing load of 0.74 MPa. Thereafter, the baked steel sheet was peeled off with a tensile tester, and the strength required for peeling (peeling strength) was measured and evaluated as follows.

○: No seizure of steel sheet (peeling strength 10N or less)
Δ: Partial seizure of the steel sheet is observed (peel strength greater than 10N to less than 60N)
×: Steel sheet is completely seized (peel strength 60N or more)
Table 1 shows the test results.

  From Table 1, the annealing separator used in Experiment 1 was good in applicability and annealing separation effect, but the adhesion of the annealing separator to the steel sheet was insufficient under all conditions.

  From the above experiment 1, it was found that silica sol has an annealing separation effect during finish annealing, but has a problem in adhesion to a steel sheet as an annealing separation agent. Therefore, the inventors examined the effectiveness of using alumina sol as a film-forming component in order to use silica sol as an annealing separator and to improve adhesion to a steel plate.

<Experiment 2>
In the same manufacturing process as Experiment 1, on the steel sheet surface (both sides) before final annealing, an annealing separator (solid content concentration 2.0 mass%) composed of an aqueous colloidal solution mainly composed of alumina sol (colloidal alumina) and silica sol, It was applied using a roll coater at a coating amount of 0.5 g / m ² per side. Next, the steel sheet was baked at a temperature reached 250 ° C. and allowed to cool. Thereafter, as in Experiment 1, the sample was held in a nitrogen atmosphere at 850 ° C. for 30 hours, and then subjected to finish annealing at 1000 ° C. for 5 hours in an Ar atmosphere.

  With respect to the obtained steel sheet, the same evaluation method as in Experiment 1 was investigated for the three items of the applicability of the annealing separator, the adhesion of the annealing separator after drying, and the annealing separation effect during finish annealing.

The ratio of alumina sol to silica sol is in the range of 20-100 mass% in terms of Al ₂ O ₃ / (Al ₂ O ₃ + SiO ₂ ), and the viscosity of the annealing separator is varied in the range of 3.5 to 100 mPa · s. It was. The viscosity of the annealing separator was changed by using an alumina sol having a different viscosity. The viscosity of the alumina sol can be controlled by, for example, the shape of the sol particles and the solid content concentration. For example, when the outer shape of the sol particle is feathery, the viscosity is high, and when the sol particle is close to a spherical shape (or granular shape) or an ellipsoid (or a rod shape), the viscosity is low.

  Table 2 shows the experimental results when the ratio of alumina sol to silica sol is changed.

  From Table 2, those having a low alumina sol ratio had insufficient adhesion of the annealing separator. On the other hand, when the ratio of the alumina sol is too large, the film forming action becomes too strong, and it becomes difficult to uniformly apply to the steel sheet, resulting in poor appearance of the product. The annealing separation effect was good under all conditions.

  Table 3 shows experimental results in which the viscosity of the annealing separator was changed.

  From Table 3, when the viscosity increased, applicability to the steel sheet was remarkably deteriorated, and a coated part and a non-coated part were generated. Since the seizure of the steel sheet occurred in the uncoated part, it was found that it is necessary to control the viscosity in order to ensure good coating properties and to have an annealing separation effect.

<Experiment 3>
Next, in the same manufacturing process as in Experiment 1, a roll coater was used on the steel sheet surface (both sides) before final annealing, and an annealing separator (solid content concentration 2.5 mass%) comprising an aqueous colloidal solution mainly composed of alumina sol and silica sol. ) Was applied as each condition with a coating amount in the range of 0.001 to 6 g / m ² per side. The viscosity of the annealing separator was 2.5 mPa · s, and the ratio of alumina sol to silica sol was 75 mass% in terms of Al ₂ O ₃ / (Al ₂ O ₃ + SiO ₂ ).

  Next, the steel sheet was baked and allowed to cool at a temperature of 250 ° C. Thereafter, as in Experiment 1, the sample was held at 850 ° C. for 30 hours in a nitrogen atmosphere, and then subjected to finish annealing at 1000 ° C. for 5 hours and held in an Ar atmosphere.

  About the obtained steel plate, the same evaluation method as in Experiment 1 was used to investigate three items: the coating property of the annealing separator, the adhesion of the annealing separator after drying, and the annealing separation effect during finish annealing.

  Table 4 shows the experimental results when the coating amount was changed.

  From Table 4, when the coating amount was extremely small, the annealing separation effect was insufficient, and the steel sheet was seized. On the other hand, when the coating amount increases, the adhesion of the annealing separator to the steel sheet decreases. From the above, it is preferable to control the coating amount of the annealing separator in order to ensure good adhesion to the steel sheet and to have an annealing separation effect.

  Based on the above experimental results, a compound having excellent stability at high temperature annealing such as silica and an Al compound in a solution state or a colloidal solution state as a main component as an annealing separator, and a solid Al compound By prescribing the fraction and the viscosity, it was newly found that excellent coating properties and adhesion after coating were obtained, and the present invention was completed.

  Next, the annealing separator of the present invention, the method for annealing a grain-oriented electrical steel sheet, and the method for producing a grain-oriented electrical steel sheet will be described in detail.

  First, the reason for limiting the annealing separator will be described. The limitation is generally defined at the time of application to the steel sheet.

  As the main component of annealing separator, Al compound in solution or colloidal solution and high temperature stable compound, that is, excellent stability at high temperature, not reacting or hardly reacting during batch annealing, well known except MgO One or more compounds are used as the main component. The high temperature stable compound may be in a solution state or a colloidal solution state together with the Al compound. That is, the annealing separator may be a solution or a colloidal solution.

  Here, being in a solution state means a state in which the compound is dissolved in water or an organic solvent as a medium. The state of colloidal solution means that the particles of the compound having a size of about 100 nm or less are stably dispersed in the medium via a structural portion such as a functional group having affinity with the medium. Say. In either case, the liquids that serve as media are collectively referred to as solvents. A colloidal solution is similar to a solution because it is transparent with no apparent suspension, but when colloidal particles are present, it is confirmed by light scattering measurements.

  In addition, a main component points out composition components other than the below-mentioned auxiliary agent and additive. Therefore, the main component occupies about 65 mass% or more, preferably 75 mass% or more with respect to the entire annealing separator component (that is, a substance that forms a solute or colloid) after drying.

  There is no particular limitation on the liquid used as the solvent, and water or an organic solvent can be used. As the organic solvent, methanol, isopropanol, ethylene glycol and the like are generally used, but are not limited thereto. Those using water as a solvent are preferable from the viewpoints of cost and diversity of selection of the compounds. In this case, an organic solvent of about 50 mass% or less may be mixed with water for the purpose of adjusting liquid characteristics. In the above case where water is the main solvent, it is called a water-based annealing separator.

  Al compounds and the above-mentioned stable compounds at high temperatures rarely react with the base iron like MgO used in conventional annealing separators, so the punching process like forsterite coatings is significantly degraded. Do not form a coating. For this reason, it is very effective when supplying grain-oriented electrical steel sheets with excellent punchability.

  The use of two or more compounds as the main component of the annealing separator provides both a large annealing separation effect with a stable compound at high temperatures and a good film-forming effect with a solution or colloidal Al compound. Because. For the first time by combining these two, it functions effectively as an annealing separator for steel sheets, which is excellent in coating properties and adhesion to steel plates after coating, and is particularly required for annealing separators for grain-oriented electrical steel sheets. Satisfy the characteristics.

  The Al compound is limited to a compound that forms a colloid in a solvent such as water in order to ensure a film forming function. That is, since the Al compound has no film forming action unless it is in a colloidal state, adhesion cannot be obtained. For example, when alumina is applied as a slurry or suspension, no film is formed. The particle size of the Al compound colloid is preferably about 50 nm or less. There is no preferred particle size limit for the lower limit, and it is sufficiently effective even near the analysis limit.

  In the case of an aqueous annealing separator, the Al compound is preferably an aluminum compound having a hydroxyl group and an organic acid group and / or a dehydration reaction product thereof (partially dehydrated, the same applies hereinafter). More preferred is an aluminum compound comprising Al, a hydroxyl group and an organic acid group and / or a dehydration reaction product thereof. Specifically, for example, from basic aluminum acetate, basic aluminum formate, basic aluminum hydrochloride, basic aluminum nitrate, basic aluminum oxalate, basic aluminum sulfamate, basic aluminum lactate, basic aluminum citrate One kind selected or a mixture of two or more kinds selected from these may be mentioned.

Of these, basic aluminum acetate is represented by the molecular formula of Al _x (OH) _y (CH ₃ COO) _z , where x, y, and z are 1 or more, particularly Al ₂ (OH) ₅ (CH ₃ COO) is preferred. This can exist in a colloidal state of several nanometers from a dissolved state at a molecular level, and can be suitably used as a coating liquid raw material. Thermal analysis shows a large dehydration reaction peak at about 200 to 230 ° C., and heating forms a network between molecules by dehydration condensation to form a film. Some or all of the basic aluminum acetate or the like may undergo a dehydration reaction.

  In the case of using an organic solvent as the solvent, the same Al compound as that used in the case of the water-based annealing separator can be applied as a suitable Al compound.

Examples of compounds excluding MgO that are stable at high temperatures include Si compounds, Sr compounds, Ca compounds, Zr compounds, Ti compounds, and Ba compounds. Specific examples of the compound include oxides such as SiO ₂ , SrO, TiO ₂ , BaO, and CaO.

  In order to contain the above-described high-temperature stable compound as a solution or colloidal solution, for example, in the case of an aqueous annealing separator, it is preferable to use a compound that has been chemically changed to a form having a hydrophilic group such as a hydroxyl group. However, in the case of a compound that is stable at a high temperature, as another method, a state in which the surface is covered with a known hydrophilic substance in a solvent may be created. In the case of using an organic solvent as a solvent, it may be designed based on the same idea using a lipophilic group or the like.

The high temperature in the case of a compound that is stable at a high temperature refers to the annealing temperature, but for a grain-oriented electrical steel sheet, it is sufficient if it is stable at 1200 ° C., more preferably it is stable at 1300 ° C. At these temperatures, it is sufficient that the compound itself does not substantially react with a steel plate or an oxide or the like (SiO ₂ , FeO, Fe ₃ O ₄ , Fe ₂ SiO _4, etc.) on the surface of the steel plate.

Any of the above compounds can provide an effect of improving the applicability of the annealing separator by coexistence with the Al compound, and among these, the Si compound is particularly preferable from the viewpoint of applicability, annealing separation performance, and the like. As the Si compound, colloidal silica, that is, so-called colloidal silica is particularly suitable because of its high stability with alumina sol and relatively low cost. Colloidal silica is an inorganic colloid mainly composed of SiO ₂ and is often amorphous.

  In addition, although Al compounds such as alumina particles that are not solutions / colloidal solutions (referred to as non-colloidal Al compounds) are stable at high temperatures, the effect of improving the coating properties of solution / colloidal Al compounds is small. Therefore, although addition of the non-colloidal Al compound as a part of the main component itself is not prohibited, it is preferable to contain a compound that is stable at a high temperature other than the noncolloidal Al compound. Non-colloidal Al compounds are not considered in the calculation of the solid content ratio described later.

  The solid content ratio of the Al compound is preferably 40 to 95 mass% in terms of the solid content ratio represented by the following formula (1).

Solid content ratio of Al compound = (solid content of Al compound) / {(solid content of Al compound) + (solid content of the compound stable at high temperature (sum))} Equation (1)
However, the solid content of the Al compound is converted to Al ₂ O ₃ and the compound stable at the high temperature is converted to the main compound after baking. For example, in the case of silica sol, silica or SiO ₂ is the main compound, and in titania sol, titania or TiO ₂ is the main compound. In addition, even if it is a case where the baking process is not particularly provided, it is converted into the main compound produced when the baking process is performed.

When the solid content consists essentially of these compounds, formula (1) is replaced by formula (3).
Solid content ratio of Al compound = (solid content of Al compound) / (total solid content) ··· Formula (3)
Here, solid content points out the quantity contained in the annealing separator component after drying.

  When the solid content ratio of the Al compound is 40 mass% or less, the Al compound as a film-forming component becomes insufficient, and the adhesion of the annealing separator becomes insufficient. On the other hand, if the solid content ratio exceeds 95 mass%, the amount of highly reactive Al compound becomes too large and the coating solution is not stable. For this reason, a uniform film cannot be formed, and the appearance of the product becomes poor. The solid content ratio of the Al compound is preferably 50 mass%, more preferably 60 mass%, and even more preferably 70 mass% or more.

  When at least one compound selected from the group consisting of Si compound, Sr compound, Ca compound, Zr compound, Ti compound and Ba compound is used as the compound that is stable at high temperature, the solid content of the Al compound is represented by the following formula (2 ) Is replaced.

Solid content ratio of Al compound = (Solid content of Al compound) / {(Solid content of Al compound) + (Solid content of the at least one compound (sum))} Equation (2)
However, the solid content of each compound is preferably a value converted to the weight of each compound described below.

Al compound: Al ₂ O ₃ , Si compound: SiO ₂ ,
Sr compound ... SrO, Ca compound ... CaO,
Zr compound ... ZrO ₂ , Ti compound ... TiO ₂ ,
Ba compound: BaO.

When Si compound is adopted as a stable compound at high temperature, that is, when the solid content is mainly composed of Al compound and Si compound, the ratio of Al compound to Si compound is Al ₂ O ₃ / (Al ₂ O ₃ it is preferable that the 40～95Mass% at + value in terms of SiO _2).

  The viscosity of the annealing separator is specified to be 25 (mPa · s) or less. When the viscosity exceeds 25 (mPa · s), the applicability is remarkably deteriorated, which hinders uniform application of the annealing separator to the steel sheet. Moreover, as a result, the part which is not apply | coated generate | occur | produces and it becomes a cause by which adhesion | attachment of steel plates generate | occur | produces at the time of finish annealing. Note that. The viscosity in the present invention is a value obtained by measuring the viscosity of an annealing separator at a liquid temperature of 25 ° C. using an Ostwald viscometer.

  Even when a colloidal slurry is used instead of the colloidal solution, coating uniformity cannot be obtained. This is thought to be due to the fact that the viscosity does not match and the viscosity variation is large due to the aggregation of colloids in the slurry.

  Further, when S (a simple substance) or a compound containing S (hereinafter, both are collectively referred to as an S-containing compound) is added as an auxiliary agent to the above-described annealing separator, the grain-oriented electrical steel sheet is more stable and good. Magnetic characteristics can be imparted. The reason for this is not clear, but it is considered that the S-containing compound is decomposed during batch annealing, so that S enters the steel and segregates at the grain boundaries. That is, it is considered that the segregated S suppresses grain growth, and as a result, secondary recrystallization is stabilized.

  If the amount of segregated S is excessive, there is a possibility that secondary recrystallization failure occurs. When emphasizing avoidance of such a situation, the amount of the S-containing compound added is preferably about 25 mass% or less as a solid content ratio with respect to the annealing separator component after baking. In addition, even if it is a case where the baking process is not especially provided, it evaluates with the solid content ratio of the S containing compound produced | generated when a baking process is performed.

  The S-containing compound is not particularly limited, but inorganic S compounds such as sulfates (including sulfites) and metal sulfides are preferable. Specific examples include strontium sulfate, magnesium sulfate, and magnesium sulfide.

  Various methods such as roll coater, flow coater, spray, knife coater, etc., which are generally used in industry, can be applied as the method for applying the annealing separator.

  In addition, it is preferable that the annealing separator of this invention performs a baking process by heating after application | coating. As for the baking method, a method such as a hot air method, an infrared method, an induction heating method, or the like, which is usually performed, can be applied. The baking process conditions may be set in accordance with various circumstances, but usually a suitable temperature is about 150 to 400 ° C. and a suitable time is about 1 to 300 seconds.

  In addition, in order to further improve the performance such as the applicability of the annealing separator and the adhesion to the steel plate, additives such as a surfactant and a rust inhibitor may be blended. In order to maintain a sufficient annealing separation effect as an annealing separator, the content of the additive is preferably about 10 mass% or less with respect to the annealing separator component after drying.

  As the surfactant, any commercially available nonionic, anionic or cationic surfactant can be applied.

  As with the surfactant, the type of the rust inhibitor is not particularly limited, and a commercially available product can be applied.

  The annealing separator of the present invention is particularly suitable for application to grain-oriented electrical steel sheets, but does not prohibit application to other steel sheets.

  In addition, the annealing separator of the present invention is particularly effective when heating in a furnace while winding a steel strip in a coil shape, but can also be applied to the case where steel plates are stacked and heat-treated.

  Next, suitable conditions for producing the grain-oriented electrical steel sheet according to the present invention will be described below.

As the component composition of the product plate and the starting material (molten steel or steel slab), any component known to be suitable for the grain-oriented electrical steel sheet can be applied. Below, the reason for limitation of each component is demonstrated about the suitable molten steel component in a typical component system.
C: 0.08 mass% or less C, if its content exceeds 0.08 mass%, it is difficult to achieve C during the manufacturing process, so that it is difficult to achieve C to 50 massppm or less where magnetic aging does not occur. It is preferable that In particular, the lower limit is not necessary, but about 5 massppm is the limit of reduction industrially.
Si: 2.0-8.0mass%
Si is an element effective in increasing the electrical resistance of steel and improving iron loss. In order to obtain the effect, Si is preferably contained in an amount of 2.0 mass% or more. On the other hand, if it exceeds 8.0 mass%, the workability and magnetic flux density decrease, so the upper limit is preferably set to 8.0 mass%. Therefore, the preferable Si content is 2.0 to 8.0 mass%.
Mn: 0.005 to 1.0 mass%
Mn is an effective element for improving the hot workability, and is preferably added in an amount of 0.005 mass% or more. On the other hand, excess Mn reduces the magnetic flux density of the product plate. From this viewpoint, the preferable Mn content is 1.0 mass% or less. Therefore, the preferable Mn content is 0.005 to 1.0 mass%.

  In the production of grain-oriented electrical steel sheets, it is common to add an element that forms an inhibitor (inhibitor-forming component) in order to develop the Goth orientation during secondary recrystallization. However, in recent years, it has become known that it is possible to develop Goss orientation without using inhibitors by reducing impurity elements in steel.

To obtain a Goss orientation crystal grains by secondary recrystallization without using an inhibitor, 150Massppm the Al or less, N, S, you reduced below 50massppm for Se. Such components can be minimized desirable from the viewpoint of magnetic properties, for example, Al has to be lower than or equal to 100 mass ppm, good preferable. However, since it may be expensive to reduce such components, it is not a problem to remain within the above range. At present, the lower limit of the content limited from the reduction cost is about 10 massppm for any element.

  In contrast, when an inhibitor is used, these elements are added according to the inhibitor to be applied. For example, when using AlN as an inhibitor, Al: 0.015-0.04 mass% and N: 0.005-0.015 mass%, and when BN is used, B: 0.001-0.006 mass% and N: 0.005-0.015 mass%, MnSe and In the case of using MnS, it is general to add at least one of Se and S in an amount of 0.005 to 0.06 mass%.

  In addition, it is preferable to add about 0.005 to 0.1 mass% of Sb and / or Sn to the grain-oriented electrical steel sheet because the magnetic properties are further improved.

  In addition, there is no particular problem even if Ge, Mo, Te, and Bi are each contained at 0.1 mass% or less, P, Cu, and Cr are each contained at 0.2 mass% or less, and Ni is contained at 0.5 mass% or less. Further, the balance is preferably iron and inevitable impurities.

  From the molten steel having the above components, a slab having a normal size may be produced by a normal ingot forming method or a continuous casting method, or a thin slab having a thickness of 100 mm or less (so-called thin slab) is directly cast. It may be manufactured. The slab is reheated and hot-rolled by a normal method, but may be immediately hot-rolled without being heated after casting. In the case of a thin slab, hot rolling may be performed, or the hot rolling may be omitted and the process may proceed as it is.

  The hot-rolled steel sheet is then subjected to annealing (hot-rolled sheet annealing) as necessary. In particular, when a band structure is formed in hot rolling, it is preferable to perform hot-rolled sheet annealing in order to realize a primary recrystallized structure of sized particles and thus promote the development of secondary recrystallization. .

  In order to eliminate the band structure, the hot-rolled sheet annealing temperature is preferably 800 ° C. or higher. On the other hand, it is not preferable that the grain size is excessively coarsened by hot-rolled sheet annealing in order to realize a primary recrystallized structure of sized particles, and therefore the hot-rolled sheet annealing temperature is preferably set to 1100 ° C. or lower. Therefore, in order to highly develop a goth structure in the product plate, the hot-rolled sheet annealing temperature is preferably set to 800 ° C. or higher and 1100 ° C. or lower. In addition, the suitable annealing time of hot-rolled sheet annealing is 1 to 300 seconds.

  Then, after cold rolling one or more times to obtain a cold rolled steel sheet, recrystallization annealing is performed. In addition, when performing cold rolling twice or more, intermediate | middle annealing is inserted between each cold rolling. The intermediate annealing is preferably performed at 900 to 1200 ° C. for about 1 to 300 seconds.

  In order to further develop a goth structure, the cold rolling temperature may be raised to 100 ° C to 250 ° C. This is sometimes called warm rolling, but is treated as one type of cold rolling in the present application. For the same purpose, the aging treatment in the range of 100 to 250 ° C. may be performed once or a plurality of times during the cold rolling.

  The recrystallization annealing is preferably performed by continuous annealing mainly for the purpose of forming a primary recrystallization structure. The recrystallization annealing is performed in a wet atmosphere when decarburization is required, but may be performed in a dry atmosphere when decarburization is not required. Preferred recrystallization annealing conditions are 750 to 1100 ° C. and about 1 to 300 seconds.

  In addition, adjusting the C content in the steel sheet to 100-250 massppm in secondary recrystallization annealing (finish annealing or first batch annealing when finishing annealing is divided into two batch annealing) contains an inhibitor in particular. This is suitable for improving the magnetic flux density in the grain-oriented electrical steel sheet that does not. The adjustment of the C amount may be performed by recrystallization annealing or may be performed separately thereafter.

  For example, a technique for increasing the amount of Si by a siliconization method may be applied to a steel sheet after recrystallization annealing.

  The annealing separator of the present invention is applied before or after the recrystallization annealing.

  Since the conventional annealing separator has poor adhesion to the steel sheet, it has not been possible to apply the annealing separator before recrystallization annealing from the viewpoint of line contamination due to peeling during recrystallization annealing. This is the same even in the case of an annealing separator mainly composed of MgO, which requires heating for a long time to form a film. However, since the annealing separator of the present invention has good adhesion to the steel sheet and there is no concern about line contamination due to peeling, it can be applied either before or after recrystallization annealing.

In this step, the application amount of the annealing separator of the present invention is preferably 0.005 g / m ² or more in order to exert the effect of preventing the adhesion of the steel sheet. On the other hand, in order to ensure the adhesion of the annealing separator, it is preferable that the adhesion amount be 5 g / m ² or less. Therefore, the application amount of the annealing separator is preferably within the range of 0.005 to 5 g / m ² . The lower limit is more preferably 0.05 g / m ^2, and more preferable upper limit is 2 g / m ^2. In addition, although the suitable application quantity in manufacture of a grain-oriented electrical steel sheet is as above-mentioned, it can also be used outside the said suitable range according to each heat processing condition and required quality.

  The annealing separator may be applied to only one side or both sides of the steel plate, but it is preferable to apply the annealing separator to both sides to ensure the effect. Although it is not prohibited to change the composition or the like of the annealing separator on the front and back of the steel sheet, it is preferable to apply the same annealing separator on both sides in the process.

  When producing a grain oriented electrical steel sheet having no magnetic properties and workability without a forsterite coating, finish annealing is performed by batch annealing after recrystallization annealing and application of the annealing separator of the present invention. The purpose of finish annealing is the progress of secondary recrystallization and the reduction (purification) of impurities. As annealing conditions, known conditions for achieving this object can be applied. A preferable finish annealing temperature is about 750 to 1300 ° C., but the first half may be about 750 to 1000 ° C. and the second half may be about 900 to 1300 ° C. Here, secondary recrystallization is mainly promoted in the first half, and purification is mainly promoted in the second half. A preferable finish annealing time is about 1 to 300 hours in terms of holding time in the above temperature range.

  In the case of the conventional technique in which an annealing separator containing MgO as a main component is applied, a thick film is formed, so that the time required for purification is longer than in the case where no annealing separator is applied. However, the annealing separator of the present invention was observed to have the effect of not preventing purification, despite the fact that the Al compound was formed into a film.

  When finish annealing is performed while containing about 100 to 250 massppm for the purpose of improving magnetic properties, it is preferable to reduce C to 50 ppm or less at which magnetic aging does not occur after the completion of secondary recrystallization. As a method for reducing C, there are a method of decarburizing during finish annealing and a method of adding a decarburizing step after finish annealing. In order to decarburize during final annealing, high temperature annealing at 1000 ° C. or higher should be performed during final annealing, particularly in an atmosphere containing hydrogen in the latter half.

  On the other hand, the decarburization process added after finish annealing includes (1) annealing in an oxidizing atmosphere (decarburization annealing), (2) surface grinding to mechanically remove surface graphite, and (3) surface graphite. Electrolytic cleaning, chemical polishing, plasma irradiation, etc. for chemical removal are effective. The reason why decarburization by means (2) or (3) is possible is that C is precipitated as graphite on the steel sheet surface layer by the end of finish annealing, and decarburization in steel is completed. .

  As for the phenomenon in which graphite precipitates on the surface layer of the steel plate, for example, the following mechanism can be considered. C forms metastable cementite in steel, but forms graphite in an activated state with high surface energy. For this reason, C precipitates as graphite on the surface layer before cooling as cementite in the ground iron during cooling. By the way, if it estimates from the phase diagram with pure iron, the solubility of graphite is slightly lower than the solubility of cementite. Therefore, since the solid solution C in the surface layer is reduced to a concentration at which it is in equilibrium with the graphite, a concentration gradient of the solid solution C between the solid solution C in the surface layer and the ground iron is generated, and decarburization from the ground iron proceeds. I guess.

  However, when a dense or strong coating layer is formed on the surface during finish annealing (for example, when a conventional annealing separator mainly composed of MgO is applied), surface activation is inhibited, resulting in the surface layer of graphite steel sheet. Precipitation is also inhibited. However, although the coating formed by the annealing separator of the present invention is excellent in adhesion, the above decarburization method can be suitably used without affecting the precipitation of the steel sheet surface layer of graphite for unknown reasons.

  After finish annealing, it is effective to reduce the iron loss by applying tension to correct the shape by flattening annealing. By performing this flattening annealing in a humid atmosphere, decarburization may be performed at the same time (a kind of method (1) above).

  A technique for increasing the amount of Si by a siliconization method after finish annealing may be further applied. This technique is effective when it is desired to further reduce iron loss.

  When steel plates are laminated and used for an iron core or the like, it is effective to improve the iron loss of the laminated body by applying an insulating coating to the steel plate surface after flattening annealing. In order to ensure particularly good punchability, an organic coating containing a resin is desirable as the insulating coating. On the other hand, when emphasizing weldability, it is desirable to apply an inorganic coating as an insulating coating.

  In particular, a process for removing the annealing separator is not necessary.

  When producing grain-oriented electrical steel sheets with excellent forsterite film properties and magnetic properties, after the recrystallization annealing and the application of the annealing separator of the present invention, the first batch annealing is performed to develop secondary recrystallization. Do. As the annealing conditions at this time, known annealing conditions in which secondary recrystallization proceeds can be applied. Preferred conditions are about 750-1100 ° C. for about 1-300 hours.

  Thereafter, a forsterite film is formed by the second batch annealing. As a preparation step, first, sub-scale formation is performed by continuous annealing. When the first batch annealing is performed with a predetermined amount of C contained for the purpose of improving the magnetic properties, it is preferable to simultaneously perform decarburization in the continuous annealing for forming the subscale. As the annealing conditions (time, temperature, atmosphere, etc.) of the continuous annealing, known annealing conditions can be applied so that the forsterite film can be easily and stably formed by the subsequent batch annealing. A preferable annealing temperature is about 750 to 1000 ° C., a preferable annealing time is about 1 to 300 seconds, and a preferable atmosphere is an oxidizing atmosphere composed of hydrogen gas and nitrogen gas.

  The step of removing the annealing separator of the present invention before the continuous annealing is unnecessary. That is, even if a forsterite film is applied on the annealing separator of the present invention, not only the adhesion of the forsterite film is good, but also the prevention of purification due to the presence of the annealing separator of the present invention occurs. Absent.

Next, an annealing separator mainly composed of MgO is applied to the surface of the steel sheet, and the second batch annealing is performed. Since the second batch annealing is performed for the purpose of forming a forsterite film and purifying impurities, known annealing conditions that can achieve these two purposes can be applied. A preferable annealing temperature is about 900 to 1300 ° C., and a preferable annealing time is about 1 to 300 hours. In addition, a well-known thing is applicable as an annealing separation agent which has MgO as a main component. For example, the solid content is preferably MgO: about 80 to 99 mass%, and if necessary, the remainder is one or more selected from TiO ₂ , SrSO ₄ , MgSO _{4 and the} like.

  After the second batch annealing, a technique for increasing the amount of Si by a silicon immersion method may be further applied.

  Finally, if necessary, a tension film is applied and baked. Further, the shape can be adjusted by flattening annealing, and further, flattening annealing that doubles the baking of the tension coating can be performed.

  The grain-oriented electrical steel sheet in the present invention means an electrical steel sheet that has developed secondary recrystallization. Therefore, not only the Goss direction but also the Cube direction ({100} <001> direction or [100] <011> direction) is secondary recrystallized. Accumulation in the Cube orientation can be performed by a known method, for example, by controlling the rolling texture, but the steps after the recrystallization annealing are roughly the same as the case where secondary recrystallization is accumulated in the Goth orientation. The same.

  A grain-oriented electrical steel sheet having excellent forsterite film properties and magnetic properties was produced by the following method.

  C: 0.020mass%, Si: 3.35mass%, Mn: 0.050mass% and Sb: 380 massppm, further containing Al: 320 massppm and N: 80 massppm as inhibitor forming components, the balance being from iron and inevitable impurities A steel slab was manufactured by a continuous casting method. The steel slab was heated to 1200 ° C. and then finished into a hot-rolled sheet having a thickness of 2.0 mm by hot rolling, and subjected to hot-rolled sheet annealing at 1050 ° C. for 60 seconds. Subsequently, a cold-rolled sheet having a thickness of 0.30 mm was finished by cold rolling, and recrystallization annealing was performed in a dry atmosphere with a dew point of −45 ° C. under conditions of 900 ° C. and 10 seconds.

  After the recrystallization annealing, the first batch annealing was performed. The annealing separator was applied according to Table 5 before or after recrystallization annealing. The annealing separator was applied using a roll coater, and then subjected to a baking treatment in which the ultimate temperature (plate temperature) of the steel plate was 250 ° C. and allowed to cool. Baking was performed by propane gas direct flame baking. The first batch annealing was performed under the condition of holding at 850 ° C. for 40 hours in a nitrogen atmosphere to complete the secondary recrystallization.

  After that, we investigated the applicability of the annealing separator, the adhesion of the annealing separator after drying, and the annealing separation effect after the first batch annealing. Furthermore, it gave and made the product board.

  In the subsequent steps, first, continuous annealing for forming a good subscale was performed, and then an annealing separator mainly composed of MgO was applied. Since the first batch annealing was performed with C remaining at 100 to 150 massppm, decarburization was also performed at the same time in the continuous annealing performed for forming the subscale. Continuous annealing was performed at 835 ° C. for 120 seconds in an oxidizing atmosphere with a dew point of 55 ° C.

Annealing separator for batch annealing second time MgO as solid content: 95ass%, TiO _2: was used containing 5 mass%. Next, the second batch annealing was carried out in a dry hydrogen atmosphere at 1200 ° C. for 5 hours.

  Finally, application and baking of a tension coating and strain relief annealing were performed. A tensile film containing phosphoric acid, chromic acid and colloidal silica was used and baked at a temperature of 800 ° C. The strain relief annealing was performed in a nitrogen atmosphere at 800 ° C. for 3 hours.

Table 5 shows the components of the annealing separator and the application conditions. An annealing separator mainly composed of SiO ₂ and Al ₂ O ₃ powders is applied in a water slurry except for No. 26, and No. 26 is suspended in alcohol to a solid content of 5 mass% and sprayed. It was applied with. The main component other than powder was diluted with water and applied as a colloidal solution, although the dilution ratio varied depending on the coating amount. 3 wt% of strontium sulfate, magnesium sulfate and magnesium sulfide added as auxiliary agents was added. Although solid content other than what was described in Table 5 was not added, 0.5 mass% or less of surfactant (nonionic) etc. was added suitably.

For the annealing separator used in the first batch annealing, Table 6 shows the order of the annealing separator coating process (classified before or after recrystallization annealing), the applicability of the annealing separator, and the annealing separator after drying. The adhesion and the annealing separation effect after the first batch annealing are shown.
In Nos. 14 and 19, since the viscosity of the annealing separator was outside the range of the present invention, the applicability was remarkably poor, and adhesion of the steel sheet occurred in the uncoated part. No. 15 did not contain a compound that was stable at high temperatures, and the amount of highly reactive Al compound was large, so the coating solution was not stable and a uniform film was not formed. As a result, the appearance was poor.

  Nos. 1 to 4 were insufficient in adhesion to the steel sheet because the main component of the annealing separator was outside the present invention. In No. 5, the coating amount of the annealing separator was insufficient, so that adhesion of the steel plate occurred during finish annealing. No. 17 had a large amount of peeling because the amount of annealing separator applied was too large.

  In Nos. 3, 4, 6, 7, 12, and 26, the annealing separation agent was applied in two orders, before and after recrystallization annealing. The annealing separator of the present invention has good annealing separation agent applicability, adhesion of the annealing separator after drying, and annealing separation effect after the first batch annealing, regardless of the order of the annealing separator application process. Obtained. In addition, No. 12 had little Al compound as a film-forming component, so although the adhesion of the annealing separator to the steel plate was slightly inferior, there was no problem in the annealing separation effect. In the comparative examples No. 3, 4 and 26, there was a difference in the annealing separation effect depending on the application order of the annealing separating agent. This is because, when applied before recrystallization annealing, these annealing separators, which have poor adhesion to the steel sheet, are peeled off during recrystallization annealing, and as a result, the annealing separator attached to the steel sheet during the first batch annealing. It is considered that the adhesion of the steel sheet occurred because the amount was reduced. On the other hand, what was applied after recrystallization annealing was considered that adhesion of the steel sheet did not occur because the amount of peeling was small and an amount necessary for preventing adhesion of the steel sheet remained on the steel sheet.

Table 7 shows the magnetic properties, forsterite film properties, and Al, C, N, and second after the second batch annealing when the sample applied with the annealing separator of the present invention is subjected to the subsequent process to obtain a product plate. S, Se content (the result of removing the coating on the steel sheet, ie, the steel sheet surface) is shown. Forsterite coating properties, the sample after strain relief annealing wrapped cylinder was evaluated by the minimum bend radius did not produce decapsulated. The magnetic properties were measured according to JIS C 2550 using a 30 × 300 mm Epstein test piece. B ₈ is the magnetic flux density (T) at a magnetizing force of 800 A / m, W _17/50 is the iron loss value (W / kg) at a frequency of 50 Hz and a maximum magnetic flux density of 1.7 T.

  When the annealing separator of the present invention is applied, both magnetic properties and forsterite film properties are achieved, and impurities are purified without problems. Further, when a compound containing S was added to the annealing separator as an auxiliary agent (Nos. 8, 10 and 11), further improvement in magnetic properties was observed.

  A grain-oriented electrical steel sheet having excellent forsterite film properties and magnetic properties was produced by the following method.

  C: 0.019 mass%, Si: 3.28 mass%, Mn: 0.073 mass% and Sb: 330 massppm, Al: 38 massppm, N: 30 massppm, S: 18 massppm, and Se: less than 10 massppm (analysis limit value) Steel slabs containing no inhibitor-forming components were produced by a continuous casting method. Here, the balance was iron and inevitable impurities. The steel slab was heated to 1200 ° C. and then finished into a hot-rolled sheet having a thickness of 2.0 mm by hot rolling, and subjected to hot-rolled sheet annealing at 1050 ° C. for 60 seconds.

  Next, it was finished into a cold-rolled sheet having a sheet thickness of 0.30 mm by cold rolling, and recrystallized and annealed in a dry atmosphere with a dew point of −45 ° C. under conditions of 900 ° C. and 10 seconds.

  After the recrystallization annealing, the first batch annealing was performed. The annealing separator was applied before or after recrystallization annealing according to Table 8. The annealing separator was applied using a roll coater, and then baked at an ultimate temperature of 250 ° C. and allowed to cool. Baking was performed by propane direct-fire baking. The first batch annealing was performed under the condition of holding at 865 ° C. for 50 hours in a nitrogen atmosphere to complete the secondary recrystallization. The components of the annealing separator and the application conditions were the same as in Example 1 and the conditions corresponding to each No. shown in Table 5.

  Thereafter, the coating properties of the annealing separator, the adhesion of the annealing separator after drying, and the annealing separation effect after the first batch annealing were investigated, and the samples with good results were further subjected to subsequent steps, A product plate was used.

In the subsequent steps, first, continuous annealing for forming a good subscale was performed, and then an annealing separator mainly composed of MgO was applied. Since the first batch annealing was performed with C remaining at 100 to 150 massppm, decarburization was also performed at the same time in the continuous annealing performed for forming the subscale. Continuous annealing was performed at 850 ° C. for 80 seconds in an oxidizing atmosphere with a dew point of 60 ° C. Further, MgO annealing separator as solids: 92.5 mass%, TiO _2: was used containing 7.5 mass%.

  Next, a second batch annealing was performed. In the steel composition of this example, it is not necessary to perform high-temperature annealing near 1200 ° C. necessary for the purification of the inhibitor component, and it is sufficient that the forsterite film can be formed. Therefore, in the second batch annealing, the temperature was kept at 1100 ° C., which is lower than the conventional temperature, for 5 hours, and the atmosphere was dry hydrogen.

  Finally, application and baking of a tension coating and strain relief annealing were performed. A tensile film containing phosphoric acid, chromic acid and colloidal silica was used and baked at a temperature of 800 ° C. The strain relief annealing was performed in a nitrogen atmosphere at 800 ° C. for 3 hours. The components of the annealing separator and the coating conditions were the same as in Example 1 and the conditions corresponding to each No. shown in Table 5.

  Table 8 shows the order of the annealing separator application process (before or after recrystallization annealing), the applicability of the annealing separator, the adhesion of the annealing separator after drying, and the annealing separation effect after the first batch annealing. Similar to Example 1, for steel produced by the method of the present invention, regardless of the order of the annealing separator coating process, good annealing separator coating, adhesiveness of the annealing separator after drying, and An annealing separation effect after the second batch annealing is obtained. This shows that the annealing separator of the present invention is effective even when applied to a component system that does not contain an inhibitor.

  Table 9 shows the magnetic properties, forsterite film properties, and Al, C, N, S after the second batch annealing, when the sample applied with the annealing separator of the present invention is subjected to the subsequent steps to obtain a product plate. , Showing the Se content. The investigation method for each characteristic was the same as in Example 1.

  When an annealing separator within the scope of the present invention was applied, both magnetic properties and forsterite film properties were achieved, and the impurity concentration was at a level that was not problematic.

  A grain-oriented electrical steel sheet having no forsterite film and excellent in magnetic properties and workability was produced by the following method.

  C: 0.020 mass%, Si: 3.31 mass%, Mn: 0.060 mass%, and Sb: 450 massppm, and further, as an inhibitor forming component, Al: 300 massppm and N: 70 massppm, and the balance consists of iron and inevitable impurities A steel slab was produced by a continuous casting method. The steel slab was heated to 1200 ° C. and then finished into a hot-rolled sheet having a thickness of 1.8 mm by hot rolling, and subjected to hot-rolled sheet annealing at 950 ° C. for 60 seconds. Next, it was finished into a cold rolled sheet with a thickness of 0.27 mm by cold rolling, recrystallized under conditions of 880 ° C. and 10 s in a dry atmosphere with a dew point of −45 ° C., and then finish annealed.

The annealing separator was applied before or after recrystallization annealing according to Table 10. The application was performed using a roll coater, which was baked at an ultimate plate temperature of 250 ° C. and then allowed to cool. Baking was performed by propane direct-fire baking. In the final annealing, secondary recrystallization was performed by holding in an N ₂ atmosphere at 860 ° C. for 45 hours, and then purification was performed by holding in an H 2 atmosphere at 1200 ° C. for 5 hours. The components of the annealing separator and the application conditions were the same as in Example 1 and the conditions corresponding to each No. shown in Table 5.

  After that, the applicability of the annealing separator, the adhesion of the annealing separator after drying, and the annealing separation effect after finish annealing were investigated respectively. It was.

  In subsequent steps, an insulating coating was applied and baked, and strain relief annealing was performed. The insulating coating used was a chromate-based one containing a commonly used organic resin and baked at a temperature of 300 ° C. The strain relief annealing was performed in a nitrogen atmosphere at 750 ° C. for 2 hours.

  Table 10 shows the coating properties of the annealing separator, the adhesion of the annealing separator after drying, the annealing separation effect after finish annealing, the magnetic properties, the insulation coating properties, and the Al, C, N, S, and Se contents after finish annealing. Indicates. In Nos. 14 and 19, since the viscosity of the annealing separator was outside the range of the present invention, the applicability was remarkably poor, and adhesion of the steel sheet occurred in the uncoated part. No. 15 did not contain a compound that was stable at high temperatures, and the amount of highly reactive Al compound was large, so the coating solution was not stable and a uniform film was not formed. As a result, the appearance was poor.

  Nos. 1 to 4 were insufficient in adhesion to the steel sheet because the main component of the annealing separator was outside the present invention. In No. 5, the coating amount of the annealing separator was insufficient, so that adhesion of the steel plate occurred during finish annealing. No. 17 had a large amount of peeling because the amount of annealing separator applied was too large. No. 1-1, 4-1, 5, 14 and 19 could not be evaluated for magnetic properties and resistance to bending peeling due to the adhesion of steel sheets.

  In Nos. 1, 4, 6, 11 and 16, the annealing separator was applied in two ways, before and after the recrystallization annealing. The annealing separator of the present invention has good coating properties of the annealing separator, adhesion of the annealing separator after drying, and an annealing separation effect at the time of finish annealing regardless of the order of the annealing separator coating process. In the comparative examples No. 1 and No. 4, there was a difference in the annealing separation effect depending on the application order of the annealing separating agent. This is considered to be caused by the difference in the amount of the annealing separator adhering during finish annealing for the same reason as in Example 1.

  The application of the annealing separator according to the present invention is good coating properties of the annealing separator, adhesion of the annealing separator after drying, annealing separation effect after finish annealing, magnetic properties, insulating film properties and impurities of the iron It can be seen that this indicates purification. In addition, No. 12 had little Al compound as a film-forming component, so although the adhesion of the annealing separator to the steel plate was slightly inferior, there was no problem in the annealing separation effect. In particular, the film characteristics were better than those of the forsterite film shown in Examples 1 and 2. From this, it can be seen that the annealing separator of the present invention can be advantageously applied also to a grain-oriented electrical steel sheet using an inhibitor that requires purification by high-temperature annealing.

  A grain-oriented electrical steel sheet having no forsterite film and excellent in magnetic properties and workability was produced by the following method.

  C: 0.018 mass%, Si: 3.32 mass%, Mn: 0.070 mass%, and Sb: 300 massppm, and further Al: 40 massppm, N: 25 massppm, S: 15 massppm, and Se: Inhibitor formation suppressed to less than 10 massppm, respectively A steel slab containing no components was produced by a continuous casting method. Here, the balance was iron and inevitable impurities. The steel slab was heated to 1200 ° C. and then finished into a hot-rolled sheet having a thickness of 1.8 mm by hot rolling, and subjected to hot-rolled sheet annealing at 950 ° C. for 60 seconds. Next, it was finished into a cold-rolled sheet having a sheet thickness of 0.35 mm by cold rolling, recrystallized under a condition of 880 ° C. × 10 s in a dry atmosphere with a dew point of −45 ° C., and then finish annealing was performed.

The annealing separator was applied before or after recrystallization annealing according to Table 11. The application was performed using a roll coater, which was baked at an ultimate plate temperature of 250 ° C. and then allowed to cool. Baking was performed by propane direct-fire baking. In the final annealing, secondary recrystallization was performed by holding at 875 ° C. for 45 hours in an N ₂ atmosphere, and then holding at 1000 ° C. for 5 hours in an Ar atmosphere. After finish annealing, decarburization annealing was performed in an oxidizing atmosphere to reduce the amount of C in the ground iron.

  Thereafter, the components of the annealing separator and the coating conditions were the same as in Example 1 and the conditions corresponding to each No. shown in Table 5. After that, the applicability of the annealing separator, the adhesion of the annealing separator after drying, and the annealing separation effect after finish annealing were investigated respectively. It was.

  In subsequent steps, an insulating coating was applied and baked, and strain relief annealing was performed. The insulating coating used was a chromate-based one containing a commonly used organic resin and baked at a temperature of 300 ° C. The strain relief annealing was performed in a nitrogen atmosphere at 750 ° C. for 2 hours.

  Table 11 shows the coating properties of the annealing separator, the adhesion of the annealing separator after drying, the annealing separation effect after finish annealing, the magnetic properties, the insulation coating properties, and the Al, C, N, S, and Se contents after finish annealing. Indicates. Similar to Example 3, with the steel to which the annealing separator according to the present invention was applied, good results were obtained regardless of the order of the annealing separator coating process.

  A grain-oriented electrical steel sheet was produced by applying the annealing separator described in Table 12. The manufacturing process is as shown in Table 13, and the processes A and B (method by one finish annealing) are Example 3, and the processes C and D (method by two batch annealing) are the steel slabs of Example 1. And manufacturing conditions were applied. Regarding the annealing separator, the components other than the main components and the coating conditions were in accordance with Example 1. In addition, No. 6 was substantially not recognized by the light scattering method, and was judged to be substantially a solution.

  The results are shown in Table 13, and all of the annealing separators of the present invention show excellent results. Among them, as a compound that is stable at high temperatures, the annealing separation effect when it contains a Si compound is high, and among these, it is preferable to use a Si compound alone as a compound that is stable at high temperatures. That is, Example 1 (No. 13 in Table 6) having the same coating amount and viscosity as No. 1 to 5 and 7 shown in Table 13 and using a colloidal solution-like Si compound (colloidal silica) alone. Example 3 (No. 13 in Table 10) showed the best characteristics and was better than the results of this example shown in Table 13.

  Each steel slab having the components shown in Table 14 was produced from molten steel by a continuous casting method, and a grain-oriented electrical steel sheet was produced according to the classification of Table 15 in the same manner as in Example 5. However, for No. 2, the amount of C before secondary recrystallization was not particularly adjusted, and therefore the decarburization treatment was omitted. For No. 1 and No. 7, recrystallization annealing was performed in an oxidizing atmosphere with a dew point of 30 ° C., and the amount of C before secondary recrystallization annealing was adjusted to 100 to 150 massppm.

  The annealing separator and coating conditions were in accordance with No. 13 in Table 5.

  The results are shown in Table 15. Although the magnetic properties depend on the components of the steel sheet, all of them realize the magnetic properties expected for each component.

  The annealing separator for grain-oriented electrical steel sheets according to the present invention has good applicability and adhesion to the steel sheet, and can ensure stable operation in the annealing separator coating process and subsequent processes. In addition, it has excellent operability such as that it achieves adhesion, does not impede purification and decarburization, and does not require a film removal operation.

  By applying this annealing separator to the production process of grain-oriented electrical steel sheets, the grain-oriented electrical steel sheets with excellent magnetic properties and forsterite coating properties and magnetic properties with no forsterite coating properties and excellent directionality with workability Manufacture of electrical steel sheets becomes possible easily.

Claims (17)

An annealing separator containing no MgO, comprising an Al compound in the form of a solution or a colloidal solution, and at least one selected from the group of Si compounds, Sr compounds, Ca compounds, Zr compounds, Ti compounds and Ba compounds It contains a seed compound, and the content of the Al compound is 40 to 95 mass% as a solid content ratio represented by the following formula (2), and the viscosity is 25 (mPa · s) or less. Annealing separator for grain-oriented electrical steel sheets.
Solid content ratio of Al compound = (solid content of Al compound) / {(solid content of Al compound) + (solid content of the at least one compound (sum))} Equation (2)
Here, the solid content of each compound is a value converted into the weight of each compound below:
Al compound: Al2O3, Si compound: SiO2,
Sr compound: SrO, Ca compound: CaO,
Zr compound: ZrO2, Ti compound: TiO2,
Ba compound: BaO. The annealing separator contains at least one compound selected from the group consisting of the Si compound, Sr compound, Ca compound, Zr compound, Ti compound and Ba compound in a solution or colloidal solution state. The annealing separator for grain-oriented electrical steel sheets according to claim 1. 3. The Al compound according to claim 1 or 2, wherein the Al compound is one or both of an Al compound having a hydroxyl group and an organic acid group and a dehydration reaction product of an Al compound having a hydroxyl group and an organic acid group. The annealing separating agent for grain-oriented electrical steel sheets described. The Al compound is selected from Al basic acetate, Al basic formate, Al basic hydrochloric acid, Al basic nitrate, Al basic oxalate, Al basic sulfamic acid, Al basic lactate and Al basic citrate. The annealing separator for grain-oriented electrical steel sheets according to claim 3, wherein the annealing separator is one or a mixture of two or more. The said annealing separator contains further 25 mass% or less by the solid content ratio calculated | required about the case where it baked, after apply | coating the said annealing separator, the compound containing S or S. An annealing separator for grain-oriented electrical steel sheets according to any of the above. The annealing separator for grain-oriented electrical steel sheets according to claim 5, wherein the S or the compound containing S is at least one selected from Sr sulfate, Mg sulfate and Mg sulfide. An annealing method for grain-oriented electrical steel sheets, in which an annealing separator is applied to a steel sheet and the applied steel sheet is annealed,
The annealing separator does not contain MgO, contains an Al compound in the form of a solution or a colloidal solution, and further, from the group of Si compound, Sr compound, Ca compound, Zr compound, Ti compound and Ba compound. It contains at least one selected compound, the content of the Al compound is 40 to 95 mass% in terms of solid content represented by the following formula (2), and the viscosity is 25 (mPa · s) or less. An annealing method for grain-oriented electrical steel sheets characterized by
Solid content ratio of Al compound = (Solid content of Al compound) / {(Solid content of Al compound) + (Solid content of the at least one compound (sum))} Equation (2)
Here, the solid content of each compound is a value converted into the weight of each compound below:
Al compound: Al ₂ O ₃ , Si compound: SiO ₂ ,
Sr compound: SrO, Ca compound: CaO,
Zr compound: ZrO ₂ , Ti compound: TiO ₂ ,
Ba compound: BaO. The annealing separator contains at least one compound selected from the group consisting of the Si compound, Sr compound, Ca compound, Zr compound, Ti compound and Ba compound in a solution or colloidal solution state. The method for annealing a grain-oriented electrical steel sheet according to claim 7 . 9. The Al compound according to claim 7 or 8, wherein the Al compound is one or both of an Al compound having a hydroxyl group and an organic acid group, and a dehydration reaction product of an Al compound having a hydroxyl group and an organic acid group. An annealing method of the grain-oriented electrical steel sheet described. The Al compound is selected from Al basic acetate, Al basic formate, Al basic hydrochloric acid, Al basic nitrate, Al basic oxalate, Al basic sulfamic acid, Al basic lactate and Al basic citrate. The method for annealing a grain-oriented electrical steel sheet according to claim 9, wherein the annealing method is one kind or a mixture of two or more kinds. The said annealing separator contains further 25 mass% or less by the solid content ratio calculated | required about the case where the compound containing S or S is further baked after apply | coating the said annealing separator. An annealing method for the grain-oriented electrical steel sheet according to any one of the above. The method for annealing a grain-oriented electrical steel sheet according to claim 11, wherein the S or the compound containing S is at least one selected from Sr sulfate, Mg sulfate and Mg sulfide. C: 0.08 mass% or less, Si: 2.0 to 8.0 mass%, Mn: 0.005 to 1.0 mass%, a slab produced from molten steel, Al 150 ppm or less, N, S, Se have a respective composition was reduced to 50ppm or less was prepared from the molten steel a balance of Fe and unavoidable impurities slabs,
Alternatively, when using at least one of AlN, BN, MnSe, and MnS as an inhibitor, when using AlN, Al: 0.015-0.04 mass% and N: 0.005-0.015 mass%, In the case of using B: 0.001 to 0.006 mass% and N: 0.005 to 0.015 mass%, and in the case of using MnSe and / or MnS, at least one of Se and S is 0.005. a step of the steel sheet was rolled to 0.06 mass% to a final thickness of any slab slabs made from molten steel consisting of unrealized balance of Fe and unavoidable impurities, the step of applying recrystallization annealing to the steel sheet, A first batch annealing step for performing batch annealing on the steel sheet by the method according to any one of claims 7 to 12, wherein: The annealing separator applied before annealing in the batch annealing step is referred to as a first annealing separator, and is the recrystallization annealing applied before the application of the first annealing separator? Or after the application of the first annealing separator and before the batch annealing, and the application amount per one side of the first annealing separator is 0.005. ˜5 g / m ^2, and thereafter, a step of subjecting the steel plate to continuous annealing, and a second batch annealing step of applying a second annealing separator containing MgO to the steel plate and then subjecting the steel plate to batch annealing. A method for producing a grain-oriented electrical steel sheet, comprising: C: 0.08 mass% or less, Si: 2.0 to 8.0 mass%, Mn: 0.005 to 1.0 mass%, a slab produced from molten steel, Al 150 ppm or less, N, S, Se have a respective composition was reduced to 50ppm or less, the slab was produced from molten steel balance consisting of Fe and unavoidable impurities or,, AlN, BN, when using at least one kind of MnSe and MnS as inhibitors, when using AlN Is Al: 0.015-0.04 mass% and N: 0.005-0.015 mass%, and when BN is used, B: 0.001-0.006 mass% and N: 0.005-0.015 mass% In the case of using MnSe and / or MnS, at least one of Se and S is set to 0.005 to 0.06 m. a step of the steel sheet was rolled to ass% to a final thickness of any slab slabs made from molten steel consisting of unrealized balance of Fe and unavoidable impurities, the step of applying recrystallization annealing to the steel sheet, the steel sheet A final annealing step for performing batch annealing by the method according to any one of claims 7 to 12, wherein the recrystallization annealing is performed before the application of the annealing separator in the final annealing step, Alternatively, either after application of the annealing separator and before the batch annealing, and an application amount per side of the annealing separator of 0.005 to 5 g / m ² A method for producing a grain-oriented electrical steel sheet, comprising: The step of rolling the slab to the final plate thickness to form a steel plate includes the step of hot rolling the slab to form a hot-rolled steel plate, and the step of subjecting the hot-rolled steel plate to annealing as necessary The directional electromagnetic wave according to claim 13 or 14, further comprising: a step of performing cold rolling once or two or more cold rolling sandwiching intermediate annealing to obtain a final plate thickness. A method of manufacturing a steel sheet. The method for producing a grain-oriented electrical steel sheet according to any one of claims 13 to 15, wherein the slab further contains 0.005 to 0.1 mass% of Sb and / or Sn in total. The slab further comprises Ge: 0.1 mass% or less, Mo: 0.1 mass% or less, Te: 0.1 mass% or less, Bi: 0.1 mass% or less, P: 0.2 mass% or less, Cu: 0.2 mass % Or less, Cr: 0.2 mass% or less, Ni: 0.5 mass% or less, any one kind or two kinds or more are contained, The directionality according to any one of claims 13-16 A method for producing electrical steel sheets.