JP2021123767A - Method for producing directional electromagnetic steel sheet and directional electromagnetic steel sheet, and annealing separation agent - Google Patents

Abstract

To provide a method for producing a directional electromagnetic steel sheet in which production costs are reduced and the steel sheet has excellent film adhesion and magnetic characteristics, and a directional electromagnetic steel sheet, and an annealing separation agent.SOLUTION: There is provided a method for producing a directional electromagnetic steel sheet having excellent film adhesion, including the steps of: heating a slab comprising a predetermined component composition and optionally Bi and a remainder made up by Fe and an impurity to 1280°C or higher and then subjecting the heated slab to a hot-rolling procedure to produce a hot-rolled steel sheet; subjecting the hot-rolled steel sheet to a hot-rolled sheet annealing procedure and then subjecting the resultant product to one round of cold rolling procedure or two or more rounds of cold-rolling procedures including intermediate annealing to produce a cold-rolled steel sheet; decarburization-annealing the resultant steel sheet; applying an annealing separation agent whose main component is MgO containing a Ti compound, a rare earth metal compound, a B compound, and a predetermined compound onto a surface of the decarburization-annealed cold-rolled steel sheet and then subjecting the resultant steel sheet to a final annealing procedure; and applying an insulation coating film onto the final annealed steel sheet and then subjecting the resultant steel sheet to a flattening annealing procedure.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing a grain-oriented electrical steel sheet, a grain-oriented electrical steel sheet, and an annealing separator.

The grain-oriented electrical steel sheet contains about 2% by mass to 5% by mass of Si, and the orientation of the crystal grains of the steel sheet is highly integrated in the {110} <001> orientation called the Goss orientation. The grain-oriented electrical steel sheet has excellent magnetic characteristics, and is used by being laminated as an iron core material of a static induction device such as a transformer, for example.

Various developments have been made for such grain-oriented electrical steel sheets in order to improve their magnetic properties. In particular, with the recent demand for energy saving, grain-oriented electrical steel sheets are required to further reduce iron loss. In order to reduce the iron loss of the grain-oriented electrical steel sheet, it is effective to increase the degree of integration of the crystal grains of the steel sheet in the Goss direction to improve the magnetic flux density and reduce the hysteresis loss.

Here, in the production of grain-oriented electrical steel sheets, the crystal orientation is controlled by utilizing a catastrophic grain growth phenomenon called secondary recrystallization. However, in order to appropriately control the crystal orientation in secondary recrystallization, it is important to improve the heat resistance of fine precipitates in steel called inhibitors.

Examples of the method for controlling the crystal orientation include a method in which the inhibitor is completely solid-solved when the steel piece is heated before hot rolling, and then finely precipitated in the hot rolling and subsequent annealing steps. Specifically, a method in which MnS and AlN as exemplified in the following Patent Document 1 are used as inhibitors and rolling with a reduction ratio exceeding 80% in the final cold rolling step, or a method exemplified in the following Patent Document 2 is exemplified. There is a method of performing two cold rolling steps using MnS and MnSe as inhibitors.

As a technique for further improving the magnetic flux density, for example, Patent Document 3 below discloses a technique for adding 100 to 5000 g / T Bi to molten steel. According to Patent Document 3 below, it is disclosed that the addition of Bi to molten steel improves the magnetic flux density in the final product plate. Further, when a grain-oriented electrical steel sheet having improved magnetic characteristics by applying tension to the steel sheet is laminated to form an iron core, the direction is aimed at improving the characteristics of the iron core by ensuring insulation between the steel sheets. A film is formed on the surface of the electrical steel sheet. _{In particular, the primary coating containing Mg 2} SiO ₄ (forsterite) as the main component, which is formed in the manufacturing process of grain-oriented electrical steel sheets, is mainly composed of aluminum phosphate, colloidal silica, etc. formed by further coating on the primary coating. It plays an important role in ensuring the adhesion between the steel sheet and the coating, including the insulating coating. The following Patent Documents 4 to 6 disclose a technique for improving the adhesion between the primary coating film and the steel sheet by compound-adding a compound of a rare earth metal and a compound of an alkaline earth metal to an annealing separator.

Tokukousho 40-15644 Special Publication No. 51-13469 Japanese Unexamined Patent Publication No. 6-88171 International Publication No. 2008/62853 International Publication No. 2006/1266660 Japanese Unexamined Patent Publication No. 2012-214902

In recent years, there has been a growing demand for miniaturization of transformer cores against the background of the need for space saving of substation equipment. In order to cope with this, especially in the wound iron core, the degree of bending of the product plate is increasing, and it is required to improve the adhesion between the primary coating and the steel plate. Further, it is necessary to process the product plate into an elongated shape also in the steel core, and it is required to improve the adhesion between the primary coating and the steel plate. Furthermore, with the progress of global transformer efficiency regulations, the demand for reducing iron loss of grain-oriented electrical steel sheets is increasing. As one of the countermeasures, the addition of Bi to molten steel is promising, but there is a problem that the adhesion between the primary coating and the steel sheet deteriorates due to the addition.

However, according to the techniques disclosed in Patent Documents 4 to 6, the primary coating is formed when the degree of bending or shearing of the product plate is increased or when the amount of Bi added to the molten steel is increased. In order to improve the problem of peeling from the steel sheet, it is necessary to add a large amount of rare earth metal to the annealing separator, so the problem of increased manufacturing cost cannot be solved, and the adhesion between the primary coating and the steel sheet is improved. There was a need for a technology that could be improved at low cost.

Therefore, the present invention has been made in view of the above problems and the like, and an object of the present invention is that it is possible to further improve the adhesion between the primary coating film and the steel sheet and suppress the manufacturing cost. It is an object of the present invention to provide a method for producing a grain-oriented electrical steel sheet, a grain-oriented electrical steel sheet, and an annealing separator.

In order to solve the above problems, according to a certain viewpoint of the present invention, in terms of mass%, C: 0.02% or more and 0.10% or less, Si: 2.5% or more and 4.5% or less, Mn: 0. 0.01% or more and 0.15% or less, one or two of S and Se: 0.001% or more and 0.050% or less in total, acid-soluble Al: 0.01% or more and 0.05% or less, and N: A slab containing 0.002% or more and 0.015% or less and the balance containing Fe and impurities is heated to 1280 ° C. or higher and hot-rolled to obtain a hot-rolled steel plate. A rolling step and a cold rolling step of forming a cold-rolled steel sheet by subjecting the hot-rolled steel sheet to hot-rolled sheet annealing and then performing one cold-rolling process or two or more cold-rolling operations sandwiching intermediate annealing. The cold-rolled steel sheet is subjected to a primary recrystallization annealing step, and the surface of the cold-rolled steel sheet after the primary recrystallization ablation step is coated with an annealing separator containing MgO, and then finish annealing. A finishing anneacing step of applying the above method and a flattening and annealing step of applying an insulating film to the surface of the steel sheet after the finishing ablation step and then performing flattening and annealing. With respect to the contained MgO, the Ti compound is contained in an amount of 0.3% or more and 10.0% or less in terms of Ti, and the compound of B is contained in an amount of 0.03% or more in terms of B. 1.60% or less, a compound of rare earth metal, 0.1% or more and 7.5% or less in terms of rare earth metal contained, one or more alkalis selected from the group consisting of Ca, Sr and Ba. One or more alkaline earth metal compounds containing an earth metal element are contained in an amount of 0.3% or more and 5.8% or less in terms of the contained alkaline earth metal, and the annealing separator is contained. The stirring conditions in the preparation of the water slurry are a temperature of 0 ° C. or higher and 30 ° C. or lower, a time of 5 minutes or longer and 300 minutes or shorter, and the amount of the ablation separating agent applied is 3.5 g / m ² or more and 10.0 g / m ² The residence time from 1000 ° C. to 1150 ° C. in the finish rolling is 10 hours or more and 100 hours or less, and the content of the Ti compound with respect to the content of MgO is A (mass%) in terms of Ti, and the rare earth Provided is a method for producing a directional electromagnetic steel sheet that satisfies the following formula (1), where B (% by mass) is the content of the metal compound in terms of rare earth metal.
0.4 ≤ (A + B) ≤ 12.0 ... Equation (1)

It is preferable that the slab further contains Bi: 0.0005% or more and 0.0500% or less in mass% instead of a part of Fe in the balance.

With the above configuration, by appropriately containing the rare earth metal compound, the Ti compound, and the B compound in the annealing separator, it is possible to further improve the adhesion between the primary coating and the steel sheet at low cost, and Bi in the molten steel. By adding the above, the heat resistance of the inhibitor can be strengthened and the magnetic flux density can be further improved.

Further, in order to solve the above problems, according to another viewpoint of the present invention, in terms of mass%, C: 0.005% or less, Si: 2.5 to 4.5%, and Mn: 0.01. Insulation with a base steel plate containing ~ 0.15% and the balance containing Fe and impurities, and _{a primary coating formed on the surface of the base steel plate and containing Mg 2} SiO ₄ as a main component. A directional electromagnetic steel plate provided with a coating film at a depth of 10 μm obtained by performing elemental analysis by a glow discharge emission analysis method from the surface of the primary coating film in the plate thickness direction of the directional electromagnetic steel plate. to the emission intensity, the peak intensity ratio I of maximum emission intensity in a depth range of 1 to 10 [mu] m, the peak intensity ratio I _Ti of Ti light emission intensity is 5 to 25, the sum of the peak intensity ratio of the emission intensity of the rare earth element the value _{I REM} is not less 2 to 8, the peak intensity ratio _{I Al} of Al luminous intensity is not less than 10, the peak intensity ratio _{I B} of B luminous intensity is not less 2.5 to 15, the peak of the S emission intensity Provided is a directional electromagnetic steel plate having a strength ratio _{IS of 2.5 or more and 10 or less.}

Further, in order to solve the above-mentioned problems, according to another viewpoint of the present invention, the Ti compound is contained in an amount of 0.3% or more in terms of Ti in terms of mass% with respect to MgO in the quenching separator. 0.0% or less, B compound contained 0.03% or more and 1.60% or less in terms of B, and rare earth metal compound contained 0.1% or more and 7.5% or less in terms of rare earth metal. , Ca, Sr and Ba, the alkaline earth metal equivalent containing one or more alkaline earth metal compounds containing one or more alkaline earth metal elements selected from the group consisting of, Ca, Sr and Ba. The content of the Ti compound with respect to the content of MgO is A (mass%) in terms of Ti, and the content of the compound of the rare earth metal in terms of the rare earth metal is contained in an amount of 0.3% or more and 5.8% or less. When the amount is B (% by mass), an annealing separator satisfying the following formula (1) is provided.
0.4 ≤ (A + B) ≤ 12.0 ... Equation (1)

As described above, according to the present invention, a method for manufacturing a directional electric steel sheet having a more excellent adhesion between the primary coating and a steel sheet, and more preferably a more excellent magnetic flux density, while suppressing an increase in manufacturing cost. And it is possible to provide directional electromagnetic steel sheets as well as annealing separators.

It is a graph which plotted the results shown in Table 1 with the Ti conversion content of the Ti compound in the annealing separator on the horizontal axis and the rare earth metal conversion content of the rare earth metal compound on the vertical axis.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present inventors have diligently studied a method for manufacturing grain-oriented electrical steel sheet in order to further improve the adhesion between the primary coating of the grain-oriented electrical steel sheet and the steel sheet and to reduce the manufacturing cost of the grain-oriented electrical steel sheet. As a result of the investigation, the following findings were found.

Specifically, the present inventors improve the adhesion between the primary coating film and the steel sheet by containing the Ti compound and the B compound in the annealing separator, even if the content of the rare earth metal compound is limited. I found that I could do it. Further, this adhesiveness improving effect is effective against the deterioration of the adhesiveness between the primary coating and the steel sheet, which was inevitably generated when Bi was added to the molten steel in order to enhance the heat resistance of the inhibitor and improve the magnetic flux density. Was confirmed to work very favorably. On the other hand, when any of the Ti compound, the B compound and the rare earth metal compound was not contained in the annealing separator, the adhesion between the primary coating film and the steel sheet was not improved.

Although the detailed reason why such a phenomenon occurs is not clear, when the annealing separator contains a rare earth metal compound, a Ti compound and a B compound, the rare earth metal compound is decomposed and the rare earth metal element is decomposed in the process of raising the temperature of the finish annealing. Infiltrates into steel. In addition, the Ti compound and the B compound are also decomposed and Ti and B infiltrate into the steel. Rare earth metal elements, Ti and B, which have penetrated into steel, contribute to the complication of the interface structure between the primary coating and the steel sheet in the primary coating or at or near the interface between the primary coating and the steel sheet, and exert an anchor effect. It is inferred that. Here, the rare earth metal element and Ti form sulfide in the primary coating or at the interface between the primary coating and the steel sheet or in the vicinity thereof, but depending on the amount of sulfur in the primary coating or at the interface between the primary coating and the steel sheet or in the vicinity thereof. , Decomposition of rare earth metal compounds and Ti compounds is limited. Therefore, it is presumed that even if the annealing separator contains a large amount of rare earth metal compound, Ti compound and B compound, the effect commensurate with the content cannot be exhibited.

The present inventors have come up with the present invention by considering the above findings. One embodiment of the present invention is a method for manufacturing a grain-oriented electrical steel sheet having the following configuration.

By mass%, C: 0.02% or more and 0.10% or less, Si: 2.5% or more and 4.5% or less, Mn: 0.01% or more and 0.15% or less, one of S and Se Or 2 types: 0.001% or more and 0.050% or less in total, acid-soluble Al: 0.01% or more and 0.05% or less, and N: 0.002% or more and 0.015% or less, and the balance A slab containing Fe and impurities is heated to 1280 ° C. or higher and hot-rolled to obtain a hot-rolled steel sheet. A cold rolling step of making a cold-rolled steel sheet by performing one cold rolling or two or more cold rollings sandwiching an intermediate quenching process, and a primary recrystallizing annealing step of applying a primary recrystallizing annealing to the cold-rolled steel sheet. Insulation on the surface of the cold-rolled steel sheet after the primary re-crystal annealing step, the finish annealing step of applying a quenching separator containing MgO, and then the finish annealing, and the surface of the steel sheet after the finish annealing step. A flattening and annealing step in which a film is applied and then flattening and annealing is performed, and the annealing separating agent contains 0.5% of _{TiO 2 in mass% with respect to MgO contained in the annealing separating agent.} More than 10% or less, Ti compound is contained as A% in terms of Ti, 0.3% or more and 10.0% or less, and compound B is contained in 0.03% or more and 1.60% in terms of B. Hereinafter, one or more alkaline soils selected from the group consisting of 0.1% or more and 7.5% or less as B% of the rare earth metal compound contained, Ca, Sr and Ba. Preparation of an aqueous slurry of the annealing separator containing one or more alkaline earth metal compounds containing metal elements of 0.3% or more and 5.8% or less in terms of the contained alkaline earth metal. The stirring conditions in the above are a temperature of 0 ° C. or higher and 30 ° C. or lower, a time of 5 minutes or longer and 300 minutes or shorter, and the coating weight of the annealed separating agent per one side of the steel plate is 3.5 g / m ² or more and 10.0 g / m. ^A method for producing a directional electromagnetic steel sheet, which is 2 or less, has a residence time of 10 hours or more and 100 hours or less at 1000 ° C. to 1150 ° C. in the finish rolling, and satisfies the following formula (1).
0.4 ≤ (A + B) ≤ 12.0 ... Equation (1)

[Manufacturing method of grain-oriented electrical steel sheet]
Hereinafter, the method for manufacturing the grain-oriented electrical steel sheet according to the present embodiment will be specifically described.

(Chemical composition of slab)
First, prior to the description of each step of the method for manufacturing the grain-oriented electrical steel sheet according to the present embodiment, the component composition of the slab used for the grain-oriented electrical steel sheet according to the present embodiment will be described. In the following, unless otherwise specified, the notation "%" shall represent "mass%". In addition, the rest of the slab other than the elements described below contains Fe and impurities.

The content of C (carbon) is 0.02% or more and 0.10% or less. C has various roles, but when the C content is less than 0.02%, the crystal grain size becomes excessively large when the slab is heated, resulting in iron loss of the final grain-oriented electrical steel sheet. It is not preferable because it increases the value. On the other hand, when the C content is more than 0.10%, the decarburization time becomes long and the manufacturing cost increases during decarburization after cold rolling, which is not preferable. Further, when the C content is more than 0.10%, decarburization tends to be incomplete and magnetic aging may occur in the final grain-oriented electrical steel sheet, which is not preferable. Therefore, the content of C is 0.02% or more and 0.10% or less. The content of C is preferably 0.05% or more and 0.09% or less.

The content of Si (silicon) is 2.5% or more and 4.5% or less. Si reduces the eddy current loss, which is one of the causes of iron loss, by increasing the electrical resistance of the steel sheet. If the Si content is less than 2.5%, it becomes difficult to sufficiently suppress the eddy current loss of the final grain-oriented electrical steel sheet, which is not preferable. On the other hand, when the Si content is more than 4.5%, the workability of the grain-oriented electrical steel sheet is lowered, which is not preferable. Therefore, the Si content is 2.5% or more and 4.5% or less. The Si content is preferably 2.7% or more and 4.0% or less.

The content of Mn (manganese) is 0.01% or more and 0.15% or less. Mn forms MnS, MnSe, and the like, which are inhibitors that influence secondary recrystallization. If the Mn content is less than 0.01%, the absolute amounts of MnS and MnSe that cause secondary recrystallization are insufficient, which is not preferable. On the other hand, if the Mn content is more than 0.15%, it becomes difficult to dissolve Mn during slab heating, which is not preferable. Further, when the Mn content is more than 0.15%, the precipitation size of the particles of the inhibitors MnS and MnSe tends to be coarsened, and the optimum size distribution as the inhibitor is impaired, which is not preferable. Therefore, the Mn content is 0.01% or more and 0.15% or less. The Mn content is preferably 0.03% or more and 0.13% or less.

The total content of S (sulfur) and Se (selenium) is 0.001% or more and 0.050% or less. S and Se form an inhibitor together with Mn described above. Both S and Se may be contained in the slab, but at least one of them may be contained in the slab. If the total content of S and Se is out of the above range, a sufficient inhibitory effect cannot be obtained, which is not preferable. Therefore, the total content of S and Se is 0.001% or more and 0.050% or less. The total content of S and Se is preferably 0.001% or more and 0.040% or less.

The content of acid-soluble Al (acid-soluble aluminum) is 0.01% or more and 0.05% or less. The acid-soluble Al constitutes an inhibitor necessary for producing a grain-oriented electrical steel sheet having a high magnetic flux density. When the content of the acid-soluble Al is less than 0.01%, the acid-soluble Al is insufficient in quantity and the inhibitor strength is insufficient, which is not preferable. On the other hand, when the content of acid-soluble Al is more than 0.05%, AlN precipitated as an inhibitor is coarsened and the inhibitor strength is lowered, which is not preferable. Therefore, the content of acid-soluble Al is 0.01% or more and 0.05% or less. The content of acid-soluble Al is preferably 0.01% or more and 0.04% or less.

The content of N (nitrogen) is 0.002% or more and 0.015% or less. N forms an inhibitor, AlN, together with the acid-soluble Al described above. If the content of N is out of the above range, a sufficient inhibitory effect cannot be obtained, which is not preferable. Therefore, the content of N is set to 0.002% or more and 0.015% or less. The content of N is preferably 0.002% or more and 0.012% or less.

The effect of the present invention is particularly useful in a steel sheet that employs a manufacturing method in which a slab contains Bi.

Generally, when Bi (bismuth) is contained in the slab component, the adhesion between the primary coating and the steel sheet deteriorates. Although the details of this mechanism have not been clarified, it is presumed that the interface structure between the primary coating and the steel sheet is easily smoothed, the anchor effect is reduced, and the adhesion is likely to be deteriorated. However, when the present invention is applied, smoothing is suppressed even in Bi-containing steel, and the adhesion is further improved.

The Bi content in this case is preferably 0.0005% or more and 0.0500% or less. It is presumed that Bi has the effect of enhancing the heat resistance of the inhibitors MnS and AlN, raising the secondary recrystallization temperature, and improving the magnetic flux density. When the Bi content is 0.0005% or more and 0.0500% or less, the inhibitor heat resistance enhancing effect can be further obtained. If the Bi content is less than 0.0005%, a sufficient inhibitor heat resistance enhancing effect may not be obtained. When the Bi content is more than 0.0500%, the brittleness of the steel sheet in hot rolling deteriorates, making it difficult to pass the sheet, and the productivity may decrease. Therefore, the Bi content is preferably 0.0005% or more and 0.0500% or less. The Bi content is more preferably 0.0010% or more and 0.0200% or less. Since Bi is not essential in steel materials, the lower limit of the content is 0%.

The rest of the slab used for the grain-oriented electrical steel sheet according to the present embodiment contains Fe and impurities as described above. Here, the impurities are those mixed from ore, scrap, or the manufacturing environment as a raw material when the base steel sheet is industrially manufactured, or are not completely purified by purification annealing and are contained in the steel. It means the following elements and the like that remain and are allowed as long as they do not adversely affect the grain-oriented electrical steel sheet of the present invention.

A slab is formed by casting molten steel adjusted to the composition of the components described above. The slab casting method is not particularly limited. Further, in research and development, even if a steel ingot is formed in a vacuum melting furnace or the like, the same effect as when a slab is formed can be confirmed for the above components. Subsequently, each step of the method for manufacturing the grain-oriented electrical steel sheet according to the present embodiment will be described.

(Hot rolling process)
When the slab having the above composition is heated to 1280 ° C. or higher, the inhibitor component in the slab is solid-solved. If the heating temperature of the slab is less than 1280 ° C., it becomes difficult to sufficiently dissolve the inhibitor components such as MnS, MnSe, and AlN, which is not preferable. The upper limit of the heating temperature of the slab at this time is not particularly determined, but is preferably 1450 ° C. from the viewpoint of equipment protection. For example, the heating temperature of the slab is preferably 1300 ° C. or higher and 1450 ° C. or lower.

Next, the heated slab is hot-rolled and processed into a hot-rolled steel sheet. Hot rolling can be performed by a known method. The thickness of the hot-rolled steel sheet after processing is preferably 1.8 mm or more and 3.5 mm or less, for example. By setting the thickness of the hot-rolled steel sheet to 1.8 mm or more and 3.5 mm or less, secondary recrystallization can be further stabilized, and the finally obtained grain-oriented electrical steel sheet has excellent magnetic properties. It will be possible to maintain. On the other hand, when the thickness of the hot-rolled steel sheet is less than 1.8 mm, the temperature of the steel sheet after hot rolling becomes low and the amount of AlN precipitated in the steel sheet increases, so that secondary recrystallization becomes unstable. Therefore, the magnetic characteristics may deteriorate. When the thickness of the hot-rolled steel sheet exceeds 3.5 mm, the rolling load in the cold rolling process may increase.

(Cold rolling process)
Subsequently, the processed hot-rolled steel sheet is cold-rolled by being subjected to hot-rolled sheet annealing and then rolled by one cold rolling or a plurality of cold rollings sandwiching intermediate annealing. Processed into steel plate. Hot-rolled sheet annealing, cold rolling and intermediate annealing can be carried out by known methods. When rolling by cold rolling a plurality of times with intermediate annealing sandwiched between them, it is possible to omit the hot-rolled sheet annealing in the previous stage. However, when hot-rolled sheet is annealed, the shape of the steel sheet becomes better, so that the possibility of the steel sheet breaking during cold rolling can be reduced.

Further, the steel sheet may be heat-treated at about 300 ° C. or lower between the cold rolling passes, between the rolling roll stands, or during rolling. In such a case, the magnetic properties of the final grain-oriented electrical steel sheet can be improved. The hot-rolled steel sheet may be rolled by cold rolling three or more times, but since cold rolling a large number of times increases the manufacturing cost, the hot-rolled steel sheet is cold-rolled once or twice. It is preferably rolled by rolling. When the cold rolling is carried out by reverse rolling such as a Zendimia mill, the number of passes in each cold rolling is not particularly limited, but from the viewpoint of manufacturing cost, 9 times or less is preferable.

(Primary recrystallization annealing process)
Next, the cold-rolled steel sheet is decarburized and annealed. Rapid heating in the process of raising the temperature is also effective in improving the magnetic characteristics. This process is also referred to as primary recrystallization annealing, and in the case of rapid heating, it is preferably performed continuously with decarburization annealing. Decarburization annealing can be carried out by a known method, but is preferably carried out in a moist atmosphere containing hydrogen and nitrogen, for example, at a temperature of 900 ° C. or lower. In the step of primary recrystallization annealing, the cold-rolled steel sheet may be subjected to reduction annealing following decarburization annealing for the purpose of improving magnetic properties and coating properties.

(Annealing separator application process)
After that, an annealing separator containing MgO as a main component is applied to the cold-rolled steel sheet after the primary recrystallization annealing for the purpose of preventing seizure between the steel sheets in the subsequent finish annealing, forming a primary film, and controlling the secondary recrystallization behavior. Will be done. The "main component" here means a component contained in a certain substance in an amount of 50% by mass or more. For example, MgO is contained in an amount of 50.0% by mass or more with respect to the total mass of the materials constituting the annealing separator. The content of MgO is preferably 50.0% by mass or more and 99.27% by mass or less, and more preferably 70.0% by mass or more and 98. It is 5% by mass or less. In addition to MgO, the quenching separator may contain a Ti compound and a rare earth metal compound, and may further contain an alkaline earth metal compound, an Al compound, an Fe compound, a Si compound and the like. The annealing separator is contained in water and is applied and dried on the surface of a steel sheet in the state of a slurry, but it may be applied by an electrostatic coating method or the like. Here, the coating weight of the annealing separator per one side of the steel sheet greatly affects the manufacturing cost, especially when the annealing separator contains an expensive compound. The coating weight of the annealing separator per one side of the steel sheet shall be 3.5 g / m ² or more and 10.0 g / m ² or less. If it is less than 3.5 g / m ² , the steel plates will seize during the finish annealing, which is not preferable. If it exceeds 10.0 g / m ² , the manufacturing cost increases, which is not preferable. Coating weight per steel sheet side of the annealing separating agent, preferably, 3.7 g / ^{m 2} or more 9.5 g / ^{m 2} or less, more preferably, 4.0 g / ^{m 2} or more 9.0 g / ^{m 2} or less Is. In addition, the content of the annealing separator has a great influence on the adhesion between the primary coating and the steel sheet and the secondary recrystallization behavior. The content and effect of the content of the annealing separator are described below. Here, the content of each of the following compounds contained in the annealing separator is, unless otherwise specified, the mass% of the content with respect to 100% MgO, which is the main component of the annealing separator.

The quenching separator according to the present embodiment is, in addition to MgO, one or more alkaline earth metal elements selected from the group consisting of Ti compounds, rare earth metal compounds, B compounds, and Ca, Sr and Ba. Contains one or more alkaline earth metal compounds (hereinafter, may be simply referred to as "alkaline earth metal compounds") including.

In the method for producing grain-oriented electrical steel sheets according to the present embodiment, the content of the Ti compound in the annealing separator is 0.3% or more and 10.0% or less in terms of Ti. The Ti compound has a great influence on the adhesion between the primary coating and the steel sheet. When the content of the Ti compound is less than 0.3% in terms of Ti, the effect of improving the adhesion is not sufficient, and when the content of the Ti compound is more than 10.0% in terms of Ti, the finish is annealed. It is not preferable because Ti may be solidified in the steel sheet in the process and later form fine precipitates such as TiC in the steel to deteriorate the magnetism (magnetic aging). Therefore, the content of the Ti compound is set to 0.3% or more and 10.0% or less in terms of Ti. The content of the Ti compound is preferably 1.0% or more and 8.0% or less in terms of Ti.

In the annealing separator, the content of the rare earth metal compound is 0.1% or more and 7.5% or less in terms of rare earth metal. The rare earth metal compound releases oxygen during finish annealing to promote the formation of an inlaid structure between the primary coating and the steel sheet, thereby improving the adhesion between the primary coating and the steel sheet. However, when the content of the rare earth metal compound is less than 0.1%, the effect of improving the adhesion is not sufficient, and when the content of the rare earth metal compound is more than 7.5%, the production cost increases. Therefore, it is not preferable. Therefore, the content of the rare earth metal compound shall be 0.1% or more and 7.5% or less in terms of rare earth metal. The content of the rare earth metal compound is preferably 0.2% or more and 7.5% or less. The rare earth metal compound contained in the annealing separator includes one or more elements selected from the group consisting of rare earth elements. Rare earth metal compounds are not particularly limited, and oxides, sulfides, sulfates, silicates, phosphates, hydroxides, carbonates, boronides, chlorides and fluorides of various rare earth metal elements are not particularly limited. One or more of the above may be mixed. As the rare earth metal compound, it is more preferable to use a compound of La, Ce, and Y from the viewpoint of availability and cost.

Here, the species of the compound may be defined by a chemical formula, or may be a different kind of compound if the chemical formula is different. For the conversion value of the amount of rare earth metal contained, the ratio of the rare earth metal element contained in the compound is calculated from the chemical formula of the rare earth metal compound contained in the annealing separator using the atomic weight of each element, and this is calculated. It can be calculated by multiplying the content of the compound in the quenching separator. When two or more kinds of rare earth metals are contained, the values calculated from each of the relevant compounds may be added up. If the compositional ratio of each element in the chemical formula cannot be determined, measure the content of rare earth metals using an inductively coupled plasma mass spectrometry (ICP-MS) or other component analyzer. You may. Further, the converted values of Ti, B and alkaline earth metals may be calculated or measured in the same manner. Further, the identification of the compound species may be carried out by using a general device such as an X-ray diffractometer or a transmission electron microscope.

In the above annealing separator, the content of the B compound is 0.03% or more and 1.60% or less in terms of B. When the content of the B compound is less than 0.03% in terms of B, the effect of improving the adhesion is not sufficient, and when the content of the B compound is more than 1.60% in terms of B, the adhesion is not sufficient. It is not preferable because the effect of improvement is saturated and the cost increases. Therefore, the content of the B compound is 0.03% or more and 1.60% or less in terms of B. The content of the B compound is preferably 0.05% or more and 1.60% or less in terms of B.

In the above-mentioned quenching separator, the content of one or more alkaline earth metal compounds containing one or more alkaline earth metal elements selected from the group consisting of Ca, Sr and Ba is alkaline. It shall be 0.3% or more and 5.8% or less in terms of earth metal. Alkaline earth metal compounds are effective in further improving magnetic properties and film adhesion. When the content of the alkaline earth metal compound is less than 0.3% in terms of alkaline earth metal, the effect of improving magnetic properties and the effect of improving film adhesion cannot be sufficiently obtained, which is not preferable. When the content of the alkaline earth metal compound is more than 5.8% in terms of alkaline earth metal, the secondary recrystallization becomes unstable and the directional electromagnetic steel sheet is excited at 800 A / m at 50 Hz. It is not preferable because the B8 value, which is the magnetic flux density of the steel sheet, deteriorates. The magnetic properties of the grain-oriented electrical steel sheet, such as the magnetic flux density, can be measured by a known method. For example, the magnetic properties of grain-oriented electrical steel sheets are determined by a method based on the Epstein test specified in JIS C 2550: 2011, or a single plate magnetic property test method (Single Sheet Tester: SST) specified in JIS C 2556: 2015. Can be measured by using. In research and development, when steel ingots are formed in a vacuum melting furnace or the like, it becomes difficult to collect test pieces of the same size as those manufactured in the actual machine. In this case, for example, a test piece may be collected so as to have a width of 60 mm and a length of 300 mm, and measurement may be performed in accordance with the single plate magnetic property test method. Further, the obtained result may be multiplied by a correction coefficient so that a measurement value equivalent to that of the method based on the Epstein test can be obtained. In the present embodiment, the measurement is performed by a measurement method based on the single plate magnetic property test method.

The one or more alkaline earth metal compounds containing one or more alkaline earth metal elements selected from the group consisting of Ca, Sr and Ba are not particularly limited. but, for example, sulfates, carbonates, hydroxides, chlorides and oxides, and the like, _{specifically, CaSO 4 · 0.5H 2 O,} CaCO 3, SrSO 4, Sr (OH) 2, BaSO ₄ , SrCO _{3, and the} like can be mentioned.

The annealing separator may contain S (sulfur) in an amount of, for example, 0.01% or more and 5.00% or less. By containing S in the annealing separator, it is possible to improve the adhesion between the base steel sheet and the primary coating. Here, the content of S (sulfur) was defined as the sulfur-converted value of the content of the sulfur compound with respect to 100% MgO. Preferably, the S content is 0.03% or more and 3.50% or less. Since S is not essential in the annealing separator, the lower limit of the content is 0%.

The annealing separator according to the present embodiment contains at least MgO, Ti compound, rare earth metal compound, and B compound, but the rare earth metal compound has a large specific gravity, while the B compound has a small specific gravity, so that an aqueous slurry is prepared. In this case, it is necessary to stir so that precipitation and floating are suppressed and the mixture is uniformly mixed. The stirring in the preparation of the water slurry of the annealing separator is carried out at a temperature of 0 ° C. or higher and 30 ° C. or lower for a time of 5 minutes or more and 300 minutes or less. If the temperature of the water slurry is less than 0 ° C., ice is formed, uniform mixing becomes difficult, and a slurry in which the compounds contained in the annealing separator are uniformly dispersed cannot be obtained, which is not preferable. When the temperature of the water slurry is higher than 30 ° C., the viscosity of the slurry becomes high and the compounds contained in the slurry are not uniformly mixed, so that a slurry in which the compounds contained in the annealing separator are uniformly dispersed cannot be obtained. Not preferred. If the stirring time is less than 5 minutes, the additives are not sufficiently mixed and a slurry in which the compound contained in the annealing separator is uniformly dispersed cannot be obtained, which is not preferable. If the stirring time is more than 300 minutes, the productivity is lowered, which is not preferable. Stirring of the annealing separator in the preparation of the water slurry is carried out at a temperature of 0 ° C. or higher and 30 ° C. or lower for a time of 5 minutes or more and 300 minutes or less.

For example, the total mass of the materials constituting the annealing separator in the state of the water slurry is not particularly limited as long as it does not affect the workability of the coating process. For example, 5 mass with respect to the total mass of the annealing separator. It can be% or more and 30% by mass or less.

The particle size of the MgO, Ti compound, rare earth metal compound, and B compound contained in the annealing separator is not particularly limited as long as it can be uniformly dispersed in water, and is, for example, 0.1 μm or more and 50 μm or less. be. The particle size of the MgO, Ti compound, rare earth metal compound, and B compound contained in the annealing separator is preferably 0.5 μm or more and 25 μm or less. The particle size is, for example, an average particle size measured by a volume reference distribution using a laser diffraction type particle size distribution measuring device.

The stirrer used for stirring the slurry is not particularly limited as long as uniform mixing is possible, and a stirring tank having various shapes and a stirring blade can be appropriately combined. It goes without saying that a baffle plate may be provided inside the stirring tank in order to achieve uniform mixing.

By including the rare earth metal compound, the Ti compound and the B compound in the annealing separator, the adhesion between the primary coating and the steel sheet is improved. Although the details of this mechanism are not clear, when the annealing separator contains _a rare earth metal compound, a Ti compound and a B compound, the rare earth metal compound is decomposed and the rare earth metal element is contained in the steel in the process of raising the temperature of the finish annealing. By infiltrating, the Ti compound and B compound are also decomposed, and Ti and B infiltrate into the steel. It is presumed that it contributes to complication and exerts an anchor effect.

In the annealing separator, the contents of the Ti compound and the rare earth metal compound are contained so as to satisfy the following formula (1).

0.4 ≤ (A + B) ≤ 12.0 ... Equation (1)

Here, in the above formula (1), A (mass%) is the Ti conversion value of the content of the Ti compound with respect to 100% MgO, and B (mass%) is the Ti conversion value of the rare earth metal with respect to 100% MgO. It is a rare earth metal equivalent value of the content of the compound. When the annealing separator contains two or more kinds of rare earth metal compounds, the above B (%) is the total value of the converted values of each of the contained rare earth metal elements.

When the relationship between A and B is expressed by the formula (A + B) <0.4, the effect of improving the adhesion is not sufficient, and when it is expressed by the formula 12.0 <(A + B), the manufacturing cost. Is not preferable because it increases.

In the method for producing grain-oriented electrical steel sheets according to the present embodiment, the contents of the Ti compound, the B compound and the rare earth metal compound in the annealing separator are preferably 0.4 ≦ in order to more reliably exhibit the above effects. The equation (A + B) ≦ 10.0 is satisfied.

When the annealing separator contains a Ti compound, a B compound and a rare earth metal compound at the same time, the present inventors remarkably improve the adhesion between the primary coating film and the steel sheet, but even if a large amount is contained, the content is commensurate with the content. It was found that the effect could not be exhibited. Although this mechanism is not always clear, the Ti compound, the B compound and the rare earth metal compound contained in the annealing separator influence each other in the heating process of the finish annealing and limit their decomposition with each other. It is inferred that. As a result of detailed analysis of the primary coating after finish annealing, the present inventors have found that the content of rare earth metal elements contained in the primary coating decreases as the content of the Ti compound increases. ..

The rare earth metal compound contained in the annealing separator is decomposed in the process of finishing annealing temperature rise, and the decomposed rare earth metal element forms oxides and sulfides in the primary coating or at the interface between the primary coating and the steel sheet or in the vicinity thereof. do. Here, when the Ti compound and the B compound are simultaneously contained in the annealing separator, the Ti compound and the B compound are decomposed earlier than the rare earth metal compound in the finishing annealing temperature rise process, and the decomposed Ti is the primary coating. It is considered that oxides, sulfides and nitrides are formed at or near the interface between the medium or primary coating and the steel plate. It is presumed that by complicating the interface structure between the primary coating and the steel sheet in this process, it contributes to improving the adhesion between the primary coating and the steel sheet. Here, it is considered that B promotes the diffusion of Ti in the primary coating, thereby complicating the interface structure between the primary coating and the steel sheet, and contributing to the improvement of the adhesion between the primary coating and the steel sheet. On the other hand, if the rare earth metal element and Ti compete with each other in the sulfide formation reaction, it is presumed that the decomposition of the rare earth metal compound is limited if Ti diffuses in the primary coating prior to the rare earth metal element. In the annealing separator, the rare earth metal compound remaining without decomposition does not contribute to the improvement of adhesion, and thus only increases the production cost.

(Finishing annealing process)
Subsequently, the above-mentioned annealing separator is applied to the cold-rolled steel sheet after primary recrystallization annealing, and then finish annealing is performed for the purpose of forming a primary film and secondary recrystallization. In the finish annealing, for example, a coiled steel sheet is retained in a range of 10 hours or more and 100 hours or less at a temperature of 1000 ° C. to 1150 ° C. using a batch type heating furnace or the like. If the residence time is less than 10 hours, the Ti compound, the B compound and the rare earth metal compound contained in the annealing separator are not sufficiently decomposed, which is not preferable. If the residence time exceeds 100 hours, the manufacturing cost increases, which is not preferable. Here, the coiled steel sheet may be held at a specific temperature. Further, in order to further reduce the iron loss value of the final grain-oriented electrical steel sheet, a purification treatment may be performed in which the coiled steel sheet is heated to a temperature of about 1200 ° C. and then held.

The average heating rate in the process of raising the temperature of the finish annealing is not particularly limited, and general finish annealing conditions can be used. For example, the average heating rate in the heating process of the finish annealing including the secondary recrystallization annealing is preferably 5 ° C./h to 100 ° C./h from the viewpoint of productivity and general equipment restrictions. Further, the temperature raising process of the finish annealing may be performed by another known heat pattern.

The atmospheric gas composition in the finish annealing is not particularly limited. In the process of secondary recrystallization, a mixed gas of nitrogen and hydrogen may be used. It may be a dry atmosphere or a moist atmosphere. The atmosphere gas composition of the purified annealing may be dry hydrogen gas. Based on the above techniques, the present inventors strictly control the contents of Ti compound, B compound and rare earth metal compound in the annealing separator, and strictly control the residence time of the finishing annealing step from 1000 ° C. to 1150 ° C. By controlling, we succeeded in significantly improving the adhesion between the primary coating and the steel sheet at low cost.

(Flatration annealing process)
Subsequently, after finish annealing, an insulating film containing, for example, aluminum phosphate or colloidal silica as a main component is applied to the surface of the steel sheet for the purpose of imparting insulation and / or tension to the steel sheet. After that, flattening annealing is performed for the purpose of baking the insulating film and flattening the steel sheet shape by finish annealing. The components of the insulating coating are not particularly limited as long as the steel sheet is provided with insulating properties and / or tension. Further, the flattening annealing can be carried out by a known method. Needless to say, in the present embodiment, magnetic domain control processing may be applied to the grain-oriented electrical steel sheet depending on the purpose of the customer.

By the above steps, the final grain-oriented electrical steel sheet can be manufactured. According to the manufacturing method according to the present embodiment, a grain-oriented electrical steel sheet having excellent magnetic characteristics and excellent adhesion between the primary coating and the steel sheet is manufactured while suppressing an increase in manufacturing cost.

When the grain-oriented electrical steel sheet thus obtained is processed into a transformer, for example, in a wound iron core transformer, it is wound into a predetermined size and then shape-corrected by a mold or the like. Here, in particular, processing having a very small radius of curvature is performed on the inner peripheral side of the iron core. In order to sufficiently prevent the primary coating and the steel sheet from peeling even in such processing, the coating peeling area ratio is preferably 10% or less, more preferably 5% or less in a bending process adhesion test of 10 mmφ. That is good.

Here, the 10 mmφ bending adhesion test (10 mmφ bending test) is a bending test performed by installing a sample steel sheet in a testing machine using a cylindrical mandrel bending tester, and the surface of the sample steel sheet after the bending test. It is carried out by observing. The film peeling area ratio is the ratio of the area of the region where the primary coating is peeled to the total area of the sample steel sheet.

[Directional magnetic steel sheet]
The grain-oriented electrical steel sheet according to the present embodiment is formed on the surface of the base steel sheet and the base steel sheet containing a predetermined component, and has _{a primary coating containing Mg 2} SiO ₄ as a main component, an insulating coating, and the like. Is provided.

[Component composition of base steel sheet]
In the grain-oriented electrical steel sheet according to the present embodiment, in order to increase the magnetic flux density and reduce the iron loss, the content of the following elements in the component composition contained in the base steel sheet of the grain-oriented electrical steel sheet is controlled. This is very important. Unless otherwise specified, the notation "%" shall represent "mass%".

C is an element effective for structure control until the completion of the decarburization annealing step in the manufacturing process. However, when the C content is more than 0.0050%, magnetic aging is caused and the magnetic properties are deteriorated. Therefore, the C content is 0.0050% or less. On the other hand, it is preferable that the C content is low, but even if the C content is reduced to less than 0.0001%, the effect of tissue control is saturated and the production cost is increased. Therefore, the C content may be 0.0001% or more. The C content is more preferably 0.0001% or more and 0.0030% or less.

Si reduces the eddy current loss that forms part of the iron loss by increasing the electrical resistance of the steel sheet. Si is contained in the base steel sheet in the range of 2.5% or more and 4.5% or less in mass%. When the Si content is less than 2.5%, it becomes difficult to suppress the eddy current loss of the grain-oriented electrical steel sheet, which is not preferable. When the Si content is more than 4.5%, the workability of the grain-oriented electrical steel sheet is lowered, which is not preferable. The Si content is more preferably 2.7% or more and 4.0% or less.

Mn forms MnS and MnSe, which are inhibitors that influence secondary recrystallization. Mn is contained in the base steel sheet in the range of 0.01% or more and 0.15% or less in mass%. When the Mn content is less than 0.01%, the base steel sheet is not preferable because the absolute amounts of MnS and MnSe that cause secondary recrystallization are insufficient. When the Mn content is more than 0.15%, it becomes difficult for the base steel sheet to dissolve Mn during slab heating, and the precipitation size of the inhibitor becomes coarse, so that the optimum size distribution of the inhibitor is obtained. It is not preferable because it is damaged. The Mn content is more preferably 0.03% or more and 0.13% or less.

The balance of the chemical composition of the base steel sheet of the grain-oriented electrical steel sheet according to the present invention contains Fe and impurities. Here, the impurities are those mixed from ore, scrap, or the manufacturing environment as a raw material when the base steel sheet is industrially manufactured, or are not completely purified by purification annealing and are contained in the steel. It means the following elements and the like that remain and are allowed as long as they do not adversely affect the grain-oriented electrical steel sheet of the present invention.

[Primary coating]
In addition, the present inventors have determined _{the adhesion between the primary coating and the steel sheet containing Mg 2} SiO ₄ as the main component, and the amount of rare earth metal elements, Ti, etc. remaining in the primary coating or at the interface between the primary coating and the steel sheet or in the vicinity thereof. I found that there is a close relationship with. That is, in the directional electromagnetic steel plate according to the present invention, a position having a depth of 10 μm obtained when elemental analysis is performed by the glow discharge emission analysis method (GDS method) in the thickness direction of the directional electromagnetic steel plate from the surface of the primary coating. for the peak intensity ratio I of maximum emission intensity in the range corresponding to the light intensity, the depth 1~10μm in, the peak intensity ratio I _Ti of Ti light emission intensity is 5 to 25, the peak intensity of the rare earth metal element emitting intensity ratio I _REM is at 2 to 8, the peak intensity ratio _{I Al} of Al luminous intensity is not less than 10, the peak intensity ratio _{I B} of B emission intensity is 2.5 or more and 15 or less, a peak intensity ratio of the S emission intensity _IS is 2.5 or more and 10 or less. The depth referred to here refers to the distance from the surface of the primary coating film in the thickness direction of the grain-oriented electrical steel sheet.

Here, the depth of elemental analysis is calculated from the sputtering time by measuring the depth of the sputtering marks formed on the surface of the sample after performing, for example, a glow discharge emission analysis for 200 seconds on the standard sample in advance. can do. First, as the peak intensity, the maximum value of the emission intensity at a depth of 1 to 10 μm is measured when, for example, a glow discharge emission analysis for 200 seconds is performed. Here, the peak intensity ratio is a value obtained by dividing the peak intensity measured by the above method by, for example, the emission intensity at a depth of 10 μm obtained by performing glow discharge emission analysis for 200 seconds. By evaluating using the peak intensity ratio, it is possible to suppress measurement variations between samples. In the GDS method of the present invention, a commercially available high-frequency glow discharge emission analyzer can be used. Further, this measurement may be carried out after removing the insulating film by immersing the steel sheet after coating and baking the insulating film in a high-temperature alkaline solution or the like and washing with water. Further, when the depth of the sputtering mark in the glow discharge emission analysis for 200 seconds is less than 10 μm, the sputtering time may be lengthened.

_{The peak intensity ratio I Ti} of the Ti emission intensity at a depth of 1 to 10 μm is 5 or more and 25 or less. Ti remains when the Ti compound in the annealing separator decomposes during finish annealing to form oxides, sulfides, nitrides, etc. in the primary coating or at the interface between the primary coating and the steel sheet or in the vicinity thereof. .. It is presumed that the peak intensity ratio I _Ti of the Ti emission intensity strongly reflects the degree of decomposition of the Ti compound in the annealing separator and the degree of diffusion of Ti in the primary coating. When the peak intensity ratio I _Ti is less than 5, the decomposition of the Ti compound and the diffusion of Ti in the primary coating are not sufficient, and the effect of improving the adhesion by the rare earth metal compound cannot be sufficiently replaced, so that the adhesion can be improved. This is not preferable because it increases the manufacturing cost. On the other hand, when the peak intensity ratio I _Ti is more than 25, the Ti content of the annealing separator is excessive, which is not preferable from the viewpoint of manufacturing cost. _{The peak intensity ratio I Ti} of the Ti emission intensity at a depth of 1 to 10 μm is preferably 5.2 or more and 22.0 or less, and more preferably 5.5 or more and 20.0 or less.

The peak intensity ratio IREM of the rare earth metal element (REM) emission intensity at a depth of 1 to 10 _μm is 2 or more and 8 or less. The rare earth metal element (REM) is that the rare earth metal compound in the annealing separator decomposes during finish annealing to form oxides, sulfides, etc. in the primary coating or at the interface between the primary coating and the steel sheet or in the vicinity thereof. Remains in. Accordingly, the peak intensity ratio I _REM of rare earth metal element (REM) emission intensity is estimated to reflect the degree of diffusion of the rare earth metal degradation degree and primary in the coating of the rare earth metal compound in the annealing separator. When the peak intensity ratio _IREM is less than 2, the effect of improving the adhesion is not sufficient, which is not preferable. On the other hand, when the peak intensity ratio _IREM is more than 8, the content of the rare earth metal compound of the annealing separator is excessive, which is not preferable from the viewpoint of manufacturing cost. Here, when the annealing separator contains two or more rare earth metal compounds, the sum of the peak intensity ratios of the rare earth metal elements is taken as _IREM . The peak intensity ratio IREM of the rare earth metal element (REM) emission intensity at a depth of 1 to 10 _μm is preferably 2.1 or more and 7.8 or less, and more preferably 2.2 or more and 7.6 or less. ..

_{The peak intensity ratio I Al} of the Al emission intensity at a depth of 1 to 10 μm is 10 or more. Al is acid-soluble is contained in the base material steel plate Al (acid-soluble aluminum), in the final annealing, to react with MgO in the interfacial and near the primary film in or primary coating and the steel sheet mainly MgAl ₂ O It remains by forming _{4 (spinel).} When MgAl ₂ O ₄ (spinel) is dispersed in the primary coating or at the interface between the primary coating and the steel sheet or in the vicinity thereof, it is considered that the adhesion is inferior because the anchor effect is not sufficient. Here, when MgAl ₂ O ₄ (spinel) is dispersed and present, the peak intensity ratio I _Al is lowered. When the peak intensity ratio I _Al is less than 10, the effect of improving the adhesion is not sufficient, which is not preferable. On the other hand, _{the upper limit of the peak intensity ratio I Al} is not particularly limited, but is formed in the primary coating or at or near the interface between the primary coating and the steel sheet due to the acid-soluble Al (acid-soluble aluminum) content of the slab. Since the amount of Mg Al ₂ O ₄ (spinel) is limited, it may be 150, for example. _{The peak intensity ratio I Al} of the Al emission intensity at a depth of 1 to 10 μm is preferably 15 or more and 135 or less, and more preferably 25 or more and 125 or less.

Peak intensity ratio _{I B} of B emission intensity at depth 1~10μm is 2.5 or more and 15 or less. B remains when the B compound in the annealing separator decomposes during finish annealing to form a nitride or the like in the primary coating or at the interface between the primary coating and the steel sheet or in the vicinity thereof. Accordingly, the peak intensity ratio I _B of B emission intensity is estimated to reflect the degree of diffusion of B degradation degree and primary in the coating of the B compound in the annealing separator. When the peak intensity ratio I _B is less than 2.5, because diffusion of B in the decomposition and in the primary coating of the B compound is not sufficient, the diffusion promoting effect of Ti in the primary film is not sufficient, the adhesion due to the rare earth metal compound It is not preferable because the effect of improving the property cannot be sufficiently replaced and the manufacturing cost increases to improve the adhesion. On the other hand, if the peak intensity ratio I _B is greater than 15, since B compound content of annealing separator is excessive, undesirable in view of manufacturing cost. Peak intensity ratio _{I B} of B emission intensity at depth 1~10μm will preferably be 2.6 to 12.0, more preferably 2.7 to 10.0.

Peak intensity ratio _{I S} of S emission intensity at depth 1~10μm is 2.5 to 10. S remains when the sulfide contained in the annealing separator and the S contained in the slab form a sulfide in the primary coating or at the interface between the primary coating and the steel sheet or in the vicinity thereof during the finish annealing. Here, when the quenching separator contains a Ti compound or a rare earth metal compound, Ti and the rare earth metal element have a strong affinity with S, so that a sulfide of Ti and the rare earth metal element is formed. Accordingly, the peak intensity ratio I _S of S emission intensity is estimated to reflect the degree of diffusion of the degradation degree and primary in the coating of a Ti compound or a rare earth metal compound in the annealing separator. When the peak intensity ratio _IS is less than 2.5, the decomposition of the Ti compound and the rare earth metal compound and the diffusion in the primary coating are not sufficient, and the effect of improving the adhesion cannot be sufficiently ensured, which is not preferable. On the other hand, if the peak intensity ratio I _S is greater than 10, since the content of Ti compound content and / or rare earth metal compound annealing separator is excessive, at a depth of 1~10μm not preferable from the viewpoint of production cost peak intensity ratio _{I S} of S emission intensity is preferably a 2.6 to 9.5, more preferably 2.6 to 9.0.

As described above, the primary coating film is formed on the surface of the base steel sheet _{and contains Mg 2} SiO ₄ as a main component. The content of Mg ₂ SiO _{4 in} the primary coating is preferably 50% by mass or more, more preferably 70% by mass or more, based on the oxide forming the primary coating. From the viewpoint of primary film adhesion and insulating properties, _{the content of Mg 2} SiO ₄ formed on the surface of the base steel sheet is preferably large, and therefore the upper limit is not particularly set. As the component contained in the primary coating, for example, an Al compound, a sulfide, an Fe compound and the like may be contained.

The main component of the primary coating can be measured, for example, on a steel sheet after finish annealing by using an energy dispersive X-ray analyzer or a fluorescent X-ray analyzer attached to a scanning electron microscope. Specifically, after the steel plate after finish annealing is washed with water, gold vapor deposition is applied to the surface, and an area of ^{about 0.005 mm 2 is measured using an energy dispersive X-ray analyzer attached to a scanning electron microscope.} Quantitative analysis can be performed to measure the main components of the primary coating. When the quantitative analysis result shows that the Mg concentration is 17% by mass or more and the Si concentration is 11% by mass or more, it can be determined that the primary coating contains 50% by mass or more of _{Mg 2} SiO _4. The steel sheet after coating and baking the insulating film may be immersed in a high-temperature alkaline solution or the like to remove the insulating film, washed with water, and then analyzed.

[Insulation film]
As described above, the insulating coating contains aluminum phosphate, colloidal silica, or the like as a main component. However, the components of the insulating coating are not particularly limited as long as the steel sheet is provided with insulating properties and / or a predetermined tension.

The amount of the insulating film applied is not particularly limited as long as the steel sheet is provided with insulating properties and / or a predetermined tension, and can be appropriately adjusted.

The grain-oriented electrical steel sheet according to the present embodiment has been described above. Although the steel plate thickness is not particularly specified in the present invention, it goes without saying that the thinner the steel plate, the lower the eddy current loss, which is preferable. The grain-oriented electrical steel sheet according to the present embodiment can be manufactured by the method for manufacturing grain-oriented electrical steel sheet of the present embodiment described above. However, the method is not limited to that method.

Hereinafter, the method for manufacturing the grain-oriented electrical steel sheet, the grain-oriented electrical steel sheet, and the annealing separator according to the embodiment of the present invention will be described in more detail with reference to Examples. The examples shown below are merely examples of the method for manufacturing grain-oriented electrical steel sheets according to the present embodiment, the grain-oriented electrical steel sheets, and the annealing separator, and the production of grain-oriented electrical steel sheets according to the present embodiment. The method and the grain-oriented electrical steel sheet, and the annealing separator are not limited to the examples shown below.

(Example 1)
First, in terms of mass%, C: 0.08%, Si: 3.3%, Mn: 0.08%, S: 0.024%, acid-soluble Al: 0.03%, N: 0.008%. Steel ingot A containing Fe and the balance of impurities, and by mass%, C: 0.08%, Si: 3.3%, Mn: 0.08%, S: 0.025%, acid-soluble Al. A steel ingot B containing 0.03%, N: 0.008%, and Bi: 0.02% was prepared, and the balance was Fe and impurities. The ingot was annealed at 1350 ° C. for 1 hour and then hot-rolled to obtain a hot-rolled steel sheet having a thickness of 2.3 mm. The obtained hot-rolled steel sheet was annealed at a maximum temperature of 1100 ° C. for 140 seconds, pickled and then cold-rolled to obtain a cold-rolled steel sheet having a thickness of 0.23 mm.

Subsequently, the obtained cold-rolled steel sheet was subjected to primary recrystallization annealing in a wet hydrogen atmosphere at 850 ° C. for 180 seconds. Next, after applying an annealing separator containing MgO to the surface of the steel sheet after primary recrystallization annealing, a batch heating furnace is used so that the residence time in the range of 1000 ° C. to 1150 ° C. is 10 hours. The temperature was raised at a heating rate of 15 ° C./h and held at a temperature of 1200 ° C. for 30 hours for finish annealing, and the steel sheet after finish annealing was washed with water. Here, contents of the annealing separating agent, in mass%, with respect to _{MgO100%, CaSO 4 · 0.5H 0.55} % to ₂ O in Ca terms, the balance and inevitable impurities, the conditions shown in Table 1 It was assumed that the compound of was contained. The stirring conditions of the annealing separator were 60 minutes at 5 ° C. after adding the compounds under the conditions shown in Table 1. The coating weight of the annealing separator per one side of the steel sheet was 8.0 g / m ² . Then, an insulating film containing aluminum phosphate and colloidal silica as main components was applied to the surface of the steel sheet, and then flattening annealing was performed for the purpose of baking the insulating film and flattening the steel sheet. This flattening annealing was carried out at 850 ° C. for 40 seconds.

After shearing, strain-removing and annealing the sample of the directional electromagnetic steel plate obtained above, a sample having a sample size of 60 mm × 300 mm is subjected to the single plate measurement method described in JIS C2556: 2015. The magnetic flux density B8 value of the directional electromagnetic steel plate (sample after strain relief annealing) according to each of the examples of the present invention and the comparative example was measured. Here, the B8 value is the magnetic flux density of the grain-oriented electrical steel sheet when the grain-oriented electrical steel sheet is excited at 800 A / m at 50 Hz. In the example of the present invention, the average value of five samples was taken as the B8 value. The sample was cut out from the grain-oriented electrical steel sheet after strain-removal annealing so that the longitudinal direction of the grain-oriented electrical steel sheet before shearing and the longitudinal direction of the sample coincided with each other.

Further, the sample was sheared to a width of 30 mm and subjected to a bending test of 10 mmφ. Here, three test pieces are subjected to a bending test, the area of the peeled portion is measured, and the ratio of the area of the peeled portion to the total area is defined as the peeled area ratio for each sample, and the peeled area between the samples is taken as the peeling area ratio. The average value of the rate was calculated.

Further, in the grain-oriented electrical steel sheet after the final step, after removing the insulating film and the primary film, the C, Si, and Mn contents of the base steel sheet were analyzed. The C content was analyzed by a carbon analyzer, and the Si and Mn contents were analyzed by inductively coupled plasma emission spectroscopy.

Further, after the cross section of the directional electromagnetic steel plate after the final step was mirror-polished, the presence or absence of the primary coating and the insulating coating was confirmed by using the energy dispersive X-ray analyzer attached to the scanning electron microscope. In addition, the analysis of the components of the primary coating was measured by the following method. That is, after the steel plate after finish annealing is washed with water, gold vapor deposition is applied to the surface, and ^{an area of about 0.005 mm 2} is quantitatively analyzed by measurement using an energy dispersive X-ray analyzer attached to a scanning electron microscope. When the Mg concentration was 17% by mass or more and the Si concentration was 11% by mass or more, it was determined that _{the main component of the primary coating was Mg 2} SiO _4. In this method, there are concerns that Fe in the lower part of the primary coating is detected and the measurement error is large, but this method is also sufficient for determining the main component. The steel sheet after coating and baking the insulating film may be immersed in a high-temperature alkaline solution or the like to remove the insulating film, washed with water, and then analyzed. Further, the method for analyzing the primary coating is not limited to the above method, and for example, a fluorescent X-ray analysis method may be used.

Further, after removing the insulating film by immersing the steel sheet after applying and baking the insulating film in a high-temperature alkaline solution, a glow discharge emission analysis method is performed from the surface of the primary film in the thickness direction of the directional electromagnetic steel sheet. Elemental analysis was performed by the GDS method). Here, the value obtained by dividing the maximum value of the emission intensity at a depth of 1 to 10 μm by the emission intensity at a depth of 10 μm is defined as the peak intensity ratio, and the peak intensity ratio of Ti emission intensity is _Ti , and the peak intensity ratio of the rare earth metal element emission intensity. I _REM, was measured Al peak intensity ratio _{I Al} of emission intensity, the peak intensity ratio _{I S} of the peak intensity ratio _{I B} and S emission intensity of B emission intensity. The depth of elemental analysis is determined by performing glow discharge emission analysis for 200 seconds on a standard sample in advance, and then measuring the depth of the sputter marks formed on the sample surface to determine the spatter time and the depth of the spatter marks. Calculated based on.

Table 1 shows the production conditions and measurement results of the above examples of the present invention and comparative examples. When Bi was not contained in the steel ingot, the condition that the peeling area ratio of the 10 mmφ bending test was 5% or less was judged to be good, and the condition that the peeling area ratio of the 10 mmφ bending test was more than 5% was disabled. When Bi was contained in the steel ingot, the condition that the peeling area ratio of the 10 mmφ bending test was 10% or less was judged to be good, and the condition that the peeling area ratio of the 10 mmφ bending test was more than 10% was judged to be unacceptable. Further, although the peeling area ratio of the 10 mmφ bending test is 10% or less, it is not possible when the effect of improving the film adhesion is saturated even if the annealing separating agent conditions are changed and the effect commensurate with the manufacturing cost cannot be obtained. It was determined to be saturated). Conditions A1 to A7 shown in Table 1 are examples using steel ingot A, and conditions B1 to B28 are examples using steel ingot B.

The base steel sheet in the obtained grain-oriented electrical steel sheet contained 0.0015% of C, 3.2% of Si, and 0.08% of Mn in mass%. Further, the grain-oriented electrical steel sheet satisfying the conditions of the present embodiment has a primary coating and an insulating coating, and as _{a result of Mg 2} SiO ₄ analysis in the primary coating, the Mg concentration is 35% by mass or more and the Si concentration. Was 13% by mass, and _{contained Mg 2} SiO ₄ as a main component.

With reference to the results in Table 1, it was found that the grain-oriented electrical steel sheets satisfying the conditions of the present embodiment were judged to be good. Further, when the content of the Ti compound in the annealing separator is more than 10.0% in terms of Ti, the content of the rare earth metal compound in the annealing separator is more than 7.5% in terms of rare earth metal, or Ti. When the sum of the Ti conversion value A (mass%) of the compound content and the rare earth metal conversion value B (mass%) of the rare earth metal compound content exceeds 12.0%, the effect of improving the adhesion is saturated. It turns out that it only increases the manufacturing cost. Further, when the condition of the present embodiment is satisfied, the Ti emission intensity at a depth of 1 to 10 μm obtained when elemental analysis is performed by the glow discharge emission analysis method from the surface of the primary coating in the plate thickness direction of the directional electromagnetic steel plate. The peak intensity ratio I _{Ti is 5 or more and 25 or less, the total value IREM} of the peak intensity ratio of the emission intensity of rare earth elements is 2 or more and 8 or less, and the peak intensity ratio I _Al of the Al emission intensity is 10 or more. peak intensity ratio _{I B} of B emission intensity is 2.5 to 15, it was found that the peak intensity ratio _{I S} of S emission intensity is 2.5 to 10. Regarding the conditions A1, A3, B1, B7, B13, B19, and B24, _{although CeO 2} was not added to the annealing separator, due to the impurities of rare earth elements inevitably contained in the steel ingot or the annealing separator, The GDS peak for the rare earth element was detected, and the peak intensity ratio _IREM of the emission intensity of the rare earth element was calculated. Further, under the conditions A1, A2, B1 to B6, although the B compound was not added to the annealing separator, the GDS peak for B was detected by B inevitably contained in the ingot or the annealing separator. The peak intensity ratio IB of the emission intensity of _B was calculated.

Here, in the example in which the steel ingot B is used, when the B compound is contained in the annealing separator at 0.03% or more and 1.60% or less in terms of B, the Ti compound content is set to the Ti conversion value A ( %) Is taken on the horizontal axis, and the rare earth metal conversion value B (%) is taken on the vertical axis as the content of the rare earth metal compound, and a graph in which the results shown in Table 1 are plotted is shown in FIG. As shown in FIG. 1, when the example of the present invention is plotted with round dots and the comparative example is plotted at intersections, the content A (%) of the Ti compound in the annealing separator and the content of the rare earth metal compound in the annealing separator are plotted. It was found that the relationship of the following formula (101) specified in the conditions according to the present embodiment was established with the rare earth metal conversion value B (%) contained as.

0.4 ≤ (A + B) ≤ 12.0 ... Equation (101)

In this way, by controlling the content of the Ti compound and the content of the rare earth metal compound so as to satisfy the formula (101), a directional electric steel sheet having better adhesion between the primary coating and the steel sheet is remarkably produced. It was found that it is possible to manufacture without increasing the manufacturing cost.

(Example 2)
First, in terms of mass%, C: 0.09%, Si: 3.3%, Mn: 0.08%, S: 0.024%, acid-soluble Al: 0.03%, N: 0.009%, A steel ingot containing Bi: 0.02% and having the balance of Fe and impurities was prepared. The ingot was annealed at 1350 ° C. for 1 hour and then hot-rolled to obtain a hot-rolled steel sheet having a thickness of 2.3 mm. The obtained hot-rolled steel sheet was annealed at a maximum temperature of 1100 ° C. for 140 seconds, pickled and then cold-rolled to obtain a cold-rolled steel sheet having a thickness of 0.23 mm.

Subsequently, the obtained cold-rolled steel sheet was subjected to primary recrystallization annealing in a wet hydrogen atmosphere at 850 ° C. for 180 seconds. Next, after applying an annealing separator containing MgO to the surface of the steel sheet after primary recrystallization annealing, a batch heating furnace is used so that the residence time in the range of 1000 ° C. to 1150 ° C. is 10 hours. The temperature was raised at a heating rate of 15 ° C./h and held at a temperature of 1200 ° C. for 30 hours for finish annealing, and the steel sheet after finish annealing was washed with water. Here, the content of the annealing separator is 100% by mass _{, 0.55% of CaCO 3} in terms of Ca with respect to 100% of MgO, the balance is unavoidable impurities, and the compound under the conditions shown in Table 2 is contained. bottom. The stirring conditions of the annealing separator were 60 minutes at 10 ° C. after adding the compounds under the conditions shown in Table 2. The coating weight of the annealing separator per one side of the steel sheet was set to the conditions shown in Table 2. Then, an insulating film containing aluminum phosphate and colloidal silica as main components was applied to the surface of the steel sheet, and then flattening annealing was performed for the purpose of baking the insulating film and flattening the steel sheet. This flattening annealing was carried out at 850 ° C. for 40 seconds.

After shearing, strain-removing and annealing the sample of the directional electromagnetic steel plate obtained above, a sample having a sample size of 60 mm × 300 mm is subjected to the single plate measurement method described in JIS C2556: 2015. The magnetic flux density B8 value of the directional electromagnetic steel plate (sample after strain relief annealing) according to each of the examples of the present invention and the comparative example was measured. Here, the B8 value is the magnetic flux density of the grain-oriented electrical steel sheet when the grain-oriented electrical steel sheet is excited at 800 A / m at 50 Hz. In the example of the present invention, the average value of five samples was taken as the B8 value. The sample was cut out from the grain-oriented electrical steel sheet after strain-removal annealing so that the longitudinal direction of the grain-oriented electrical steel sheet before shearing and the longitudinal direction of the sample coincided with each other.

Further, the sample was sheared to a width of 30 mm and subjected to a bending test of 10 mmφ. Here, three test pieces are subjected to a bending test, the area of the peeled portion is measured, and the ratio of the area of the peeled portion to the total area is defined as the peeled area ratio for each sample, and the peeled area between the samples is taken as the peeling area ratio. The average value of the rate was calculated.

Further, the components of the base steel sheet in the obtained grain-oriented electrical steel sheet were carried out in the same manner as in Example 1.

Further, in the grain-oriented electrical steel sheet after the final step, the presence or absence of the primary coating and the insulating coating and the components of the primary coating were analyzed by the same method as in Example 1.

Further, after removing the insulating film by immersing the steel sheet after applying and baking the insulating film in a high-temperature alkaline solution, a glow discharge emission analysis method is performed in the direction of the thickness of the directional electromagnetic steel sheet from the surface of the primary film. Elemental analysis by the GDS method) was performed in the same manner as in Example 1.

Table 2 shows the production conditions and measurement results of the above examples of the present invention and comparative examples. The condition that the peeling area ratio of the 10 mmφ bending test was 10% or less was judged to be good. The condition that the peeling area ratio of the 10 mmφ bending test was more than 10% or the condition that the peeling test could not be performed was judged to be impossible. Further, although the peeling area ratio of the 10 mmφ bending test is 10% or less, it is not possible when the effect of improving the film adhesion is saturated even if the annealing separating agent conditions are changed and the effect commensurate with the manufacturing cost cannot be obtained. It was determined to be saturated).

The base steel sheet in the obtained grain-oriented electrical steel sheet contained 0.0016% of C, 3.2% of Si, and 0.08% of Mn in mass%. Further, the grain-oriented electrical steel sheet satisfying the conditions of the present embodiment has a primary coating and an insulating coating, and as _{a result of Mg 2} SiO ₄ analysis in the primary coating, the Mg concentration is 35% by mass or more and the Si concentration. Was 13% by mass, and _{contained Mg 2} SiO ₄ as a main component.

With reference to the results in Table 2, it was found that the grain-oriented electrical steel sheets satisfying the conditions of the present embodiment were judged to be good. Under conditions C1 to C4, seizure occurred. Further, it was found that when the coating weight of the annealing separator per one side of the steel sheet ^{was more than 10.0 g / m 2} , the effect of improving the adhesion was saturated and the manufacturing cost was only increased. Further, when the condition of the present embodiment is satisfied, the Ti emission intensity at a depth of 1 to 10 μm obtained when elemental analysis is performed by the glow discharge emission analysis method from the surface of the primary coating in the plate thickness direction of the directional electromagnetic steel plate. The peak intensity ratio I _{Ti is 5 or more and 25 or less, the total value IREM} of the peak intensity ratio of the emission intensity of rare earth elements is 2 or more and 8 or less, and the peak intensity ratio I _Al of the Al emission intensity is 10 or more. peak intensity ratio _{I B} of B emission intensity is 2.5 to 15, it was found that the peak intensity ratio _{I S} of S emission intensity is 2.5 to 10.

(Example 3)
First, in terms of mass%, C: 0.08%, Si: 3.2%, Mn: 0.08%, S: 0.024%, acid-soluble Al: 0.03%, N: 0.008%, A steel ingot containing Bi: 0.03% and having the balance of Fe and impurities was prepared. The ingot was annealed at 1350 ° C. for 1 hour and then hot-rolled to obtain a hot-rolled steel sheet having a thickness of 2.3 mm. The obtained hot-rolled steel sheet was annealed at a maximum temperature of 1100 ° C. for 140 seconds, pickled and then cold-rolled to obtain a cold-rolled steel sheet having a thickness of 0.23 mm.

Subsequently, the obtained cold-rolled steel sheet was subjected to primary recrystallization annealing in a wet hydrogen atmosphere at 850 ° C. for 180 seconds. Next, after applying an annealing separator containing MgO to the surface of the steel sheet after primary recrystallization annealing, the temperature rises to the high temperature holding temperature shown in Table 3 at a heating rate of 30 ° C./h using a batch heating furnace. It was warm. After holding for the time shown in Table 3 at each high temperature holding temperature, the temperature is raised to a temperature of 1200 ° C. at a heating rate of 30 ° C./h, held for 30 hours to perform finish annealing, and the steel sheet after finish annealing is washed with water. bottom. Here, contents of the annealing separating agent, in mass%, with respect to MgO100%, 0.48% and SrSO ₄ with Sr terms, and shall include the balance and inevitable impurities, the compound of the conditions shown in Table 3 bottom. The stirring conditions of the annealing separator were 40 minutes at 30 ° C. after adding the compounds under the conditions shown in Table 3. The coating weight of the annealing separator per one side of the steel sheet was 6.0 g / m ² . Then, an insulating film containing aluminum phosphate and colloidal silica as main components was applied to the surface of the steel sheet, and then flattening annealing was performed for the purpose of baking the insulating film and flattening the steel sheet. This flattening annealing was carried out at 850 ° C. for 40 seconds.

After shearing, strain-removing and annealing the sample of the directional electromagnetic steel plate obtained above, a sample having a sample size of 60 mm × 300 mm is subjected to the single plate measurement method described in JIS C2556: 2015. The magnetic flux density B8 value of the directional electromagnetic steel plate (sample after strain relief annealing) according to each of the examples of the present invention and the comparative example was measured. Here, the B8 value is the magnetic flux density of the grain-oriented electrical steel sheet when the grain-oriented electrical steel sheet is excited at 800 A / m at 50 Hz. In the example of the present invention, the average value of five samples was taken as the B8 value. The sample was cut out from the grain-oriented electrical steel sheet after strain removal and annealing so that the longitudinal direction of the grain-oriented electrical steel sheet before shearing and the longitudinal direction of the sample coincided with each other.

Further, the sample was sheared to a width of 30 mm and subjected to a bending test of 10 mmφ. Here, three test pieces are subjected to a bending test, the area of the peeled portion is measured, and the ratio of the area of the peeled portion to the total area is defined as the peeled area ratio for each sample, and the peeled area between the samples is taken as the peeling area ratio. The average value of the rate was calculated.

Further, the components of the base steel sheet in the obtained grain-oriented electrical steel sheet were carried out in the same manner as in Example 1.

Further, in the grain-oriented electrical steel sheet after the final step, the presence or absence of the primary coating and the insulating coating and the components of the primary coating were analyzed by the same method as in Example 1.

Further, after removing the insulating film by immersing the steel sheet after applying and baking the insulating film in a high-temperature alkaline solution, a glow discharge emission analysis method is performed in the direction of the thickness of the directional electromagnetic steel sheet from the surface of the primary film. Elemental analysis by the GDS method) was performed in the same manner as in Example 1.

Table 3 shows the production conditions and measurement results of the above examples of the present invention and comparative examples. The condition that the peeling area ratio of the 10 mmφ bending test was 10% or less was judged to be good. The condition that the peeling area ratio of the 10 mmφ bending test exceeds 10% was judged to be impossible.

The base steel sheet in the obtained grain-oriented electrical steel sheet contained 0.0015% of C, 3.1% of Si, and 0.08% of Mn in mass%. Further, the grain-oriented electrical steel sheet satisfying the conditions of the present embodiment has a primary coating and an insulating coating, and as _{a result of Mg 2} SiO ₄ analysis in the primary coating, the Mg concentration is 35% by mass or more and the Si concentration. Was 13% by mass, and _{contained Mg 2} SiO ₄ as a main component.

With reference to the results in Table 3, it was found that the grain-oriented electrical steel sheets satisfying the conditions of the present embodiment were judged to be good. Further, if the judgment is good, the peak intensity ratio of the Ti emission intensity at a depth of 1 to 10 μm obtained when elemental analysis is performed by the glow discharge emission analysis method from the surface of the primary coating to the thickness direction of the directional electromagnetic steel plate. I _Ti is 5 to 25, sum _{I REM} of the peak intensity ratio of the emission intensity of the rare earth element is 2 to 8, the peak intensity ratio _{I Al} of Al luminous intensity is not less than 10, B luminous intensity is the peak intensity ratio _{I B} is 2.5 to 15, it was found that the peak intensity ratio _{I S} of S emission intensity is 2.5 to 10.

(Example 4)
First, in terms of mass%, C: 0.08%, S: 0.024%, acid-soluble Al: 0.03%, N: 0.008%, Bi: 0.02% are contained, and the balance is shown in Table 4. A steel ingot composed of Si and Mn having the contents shown in the above, Fe and impurities was prepared. The ingot was annealed at 1350 ° C. for 1 hour and then hot-rolled to obtain a hot-rolled steel sheet having a thickness of 2.3 mm. The obtained hot-rolled steel sheet was annealed at a maximum temperature of 1100 ° C. for 140 seconds, pickled and then cold-rolled to obtain a cold-rolled steel sheet having a thickness of 0.23 mm.

Subsequently, the obtained cold-rolled steel sheet was subjected to primary recrystallization annealing in a wet hydrogen atmosphere at 850 ° C. for 180 seconds. Next, after applying an annealing separator containing MgO to the surface of the steel sheet after primary recrystallization annealing, a batch heating furnace is used so that the residence time in the range of 1000 ° C. to 1150 ° C. is 10 hours. The temperature was raised at a heating rate of 15 ° C./h and held at a temperature of 1200 ° C. for 30 hours for finish annealing, and the steel sheet after finish annealing was washed with water. Here, the content of the annealing separator contains CaCO ₃ and BaSO ₄ at 0.69% in terms of alkaline earth metal with respect to MgO 100%, the balance is unavoidable impurities, and the compounds under the conditions shown in Table 4 are contained. I made it. The stirring conditions of the annealing separator were 20 minutes at 5 ° C. after adding the compounds under the conditions shown in Table 4. The coating weight of the annealing separator per one side of the steel sheet was 6.0 g / m ² . Then, an insulating film containing aluminum phosphate and colloidal silica as main components was applied to the surface of the steel sheet, and then flattening annealing was performed for the purpose of baking the insulating film and flattening the steel sheet. This flattening annealing was carried out at 850 ° C. for 40 seconds.

After shearing, strain-removing and annealing the sample of the directional electromagnetic steel plate obtained above, a sample having a sample size of 60 mm × 300 mm is subjected to the single plate measurement method described in JIS C2556: 2015. The magnetic flux density B8 value of the directional electromagnetic steel plate (sample after strain relief annealing) according to each of the examples of the present invention and the comparative example was measured. Here, the B8 value is the magnetic flux density of the grain-oriented electrical steel sheet when the grain-oriented electrical steel sheet is excited at 800 A / m at 50 Hz. In the example of the present invention, the average value of five samples was taken as the B8 value. The sample was cut out from the grain-oriented electrical steel sheet after strain removal and annealing so that the longitudinal direction of the grain-oriented electrical steel sheet before shearing and the longitudinal direction of the sample coincided with each other.

Further, the sample was sheared to a width of 30 mm and subjected to a bending test of 10 mmφ. Here, three test pieces are subjected to a bending test, the area of the peeled portion is measured, and the ratio of the area of the peeled portion to the total area is defined as the peeled area ratio for each sample, and the peeled area between the samples is taken as the peeling area ratio. The average value of the rate was calculated.

Further, the components of the base steel sheet in the obtained grain-oriented electrical steel sheet were carried out in the same manner as in Example 1.

Further, in the grain-oriented electrical steel sheet after the final step, the presence or absence of the primary coating and the insulating coating and the components of the primary coating were analyzed by the same method as in Example 1.

Further, after removing the insulating film by immersing the steel sheet after applying and baking the insulating film in a high-temperature alkaline solution, a glow discharge emission analysis method is performed in the direction of the thickness of the directional electromagnetic steel sheet from the surface of the primary film. Elemental analysis by the GDS method) was performed in the same manner as in Example 1.

Table 4 shows the production conditions and measurement results of the above examples of the present invention and comparative examples. The condition that the B8 value was 1.85T or more and the peeling area ratio of the 10mmφ bending test was 10% or less was judged to be good. If the B8 value is less than 1.85T and the peeling area ratio of the 10mmφ bending test is more than 10%, or if the peeling test cannot be performed, it is judged to be impossible.

The base steel sheet in the obtained grain-oriented electrical steel sheet contained 0.0016% of C in mass%. Further, the grain-oriented electrical steel sheet satisfying the conditions of the present embodiment has a primary coating and an insulating coating, and as _{a result of Mg 2} SiO ₄ analysis in the primary coating, the Mg concentration is 35% by mass or more and the Si concentration. Was 13% by mass, and _{contained Mg 2} SiO ₄ as a main component.

With reference to the results in Table 4, it was found that the grain-oriented electrical steel sheets satisfying the conditions of the present embodiment were judged to be good. Further, when the judgment is good, the base steel sheet in the grain-oriented electrical steel sheet contains 2.5% or more and 4.5% or less of Si and 0.01% or more and 0.15% or less of Mn in mass%. It turned out that there was. _{Further, the peak intensity ratio I Ti} of the Ti emission intensity at a depth of 1 to 10 μm obtained by performing elemental analysis by the glow discharge emission analysis method from the surface of the primary coating in the thickness direction of the directional electromagnetic steel plate is 5 or more and 25. or less, the total value I _REM of the peak intensity ratio of the emission intensity of the rare earth element is 2 to 8, the peak intensity ratio I _Al of Al luminous intensity is not less than 10, the peak intensity of the B light emission intensity ratio I _B There is 2.5 to 15, it was found that the peak intensity ratio _{I S} of S emission intensity is 2.5 to 10.

(Example 5)
First, in terms of mass%, C: 0.08%, Si: 3.3%, Mn: 0.08%, S: 0.025%, acid-soluble Al: 0.03%, N: 0.008%, A steel ingot containing Bi: 0.02% and having the balance of Fe and impurities was prepared. The ingot was annealed at 1350 ° C. for 1 hour and then hot-rolled to obtain a hot-rolled steel sheet having a thickness of 2.3 mm. The obtained hot-rolled steel sheet was annealed at a maximum temperature of 1050 ° C. for 140 seconds, pickled, and then subjected to primary cold rolling to obtain a primary cold rolled sheet having a plate thickness of 1.8 mm. The obtained primary cold-rolled sheet was annealed at a maximum temperature of 1100 ° C. for 140 seconds, pickled, and then secondary cold-rolled to obtain a cold-rolled steel sheet having a plate thickness of 0.23 mm.

Subsequently, the obtained cold-rolled steel sheet was subjected to primary recrystallization annealing in a wet hydrogen atmosphere at 850 ° C. for 180 seconds. Next, after applying an annealing separator containing MgO to the surface of the steel sheet after primary recrystallization annealing, a batch heating furnace is used so that the residence time in the range of 1000 ° C. to 1150 ° C. is 10 hours. The temperature was raised at a heating rate of 15 ° C./h and held at a temperature of 1200 ° C. for 30 hours for finish annealing, and the steel sheet after finish annealing was washed with water. Here, contents of the annealing separating agent, in mass%, with respect to _{MgO100%, CaSO 4 · 0.5H 0.55} % to ₂ O in Ca terms, the balance and inevitable impurities, the conditions shown in Table 5 It was assumed that the compound of was contained. The stirring conditions of the annealing separator were 40 minutes at 10 ° C. after adding the compounds under the conditions shown in Table 5. The coating weight of the annealing separator per one side of the steel sheet was 8.0 g / m ² . Then, an insulating film containing aluminum phosphate and colloidal silica as main components was applied to the surface of the steel sheet, and then flattening annealing was performed for the purpose of baking the insulating film and flattening the steel sheet. This flattening annealing was carried out at 850 ° C. for 40 seconds.

After shearing, strain-removing and annealing the sample of the directional electromagnetic steel plate obtained above, a sample having a sample size of 60 mm × 300 mm is subjected to the single plate measurement method described in JIS C2556: 2015. The magnetic flux density B8 value of the directional electromagnetic steel plate (sample after strain relief annealing) according to each of the examples of the present invention and the comparative example was measured. Here, the B8 value is the magnetic flux density of the grain-oriented electrical steel sheet when the grain-oriented electrical steel sheet is excited at 800 A / m at 50 Hz. In the example of the present invention, the average value of five samples was taken as the B8 value. The sample was cut out from the grain-oriented electrical steel sheet after strain removal and annealing so that the longitudinal direction of the grain-oriented electrical steel sheet before shearing and the longitudinal direction of the sample coincided with each other.

Further, the sample was sheared to a width of 30 mm and subjected to a bending test of 10 mmφ. Here, three test pieces are subjected to a bending test, the area of the peeled portion is measured, and the ratio of the area of the peeled portion to the total area is defined as the peeled area ratio for each sample, and the peeled area between the samples is taken as the peeling area ratio. The average value of the rate was calculated.

Further, the components of the base steel sheet in the obtained grain-oriented electrical steel sheet were carried out in the same manner as in Example 1.

Further, in the grain-oriented electrical steel sheet after the final step, the presence or absence of the primary coating and the insulating coating and the components of the primary coating were analyzed by the same method as in Example 1.

Further, after removing the insulating film by immersing the steel sheet after applying and baking the insulating film in a high-temperature alkaline solution, a glow discharge emission analysis method is performed in the direction of the thickness of the directional electromagnetic steel sheet from the surface of the primary film. Elemental analysis by the GDS method) was performed in the same manner as in Example 1.

Table 5 shows the production conditions and measurement results of the above examples of the present invention and comparative examples. The condition that the peeling area ratio of the 10 mmφ bending test was 10% or less was judged to be good. The condition that the peeling area ratio of the 10 mmφ bending test exceeds 10% was judged to be impossible. Further, although the peeling area ratio of the 10 mmφ bending test is 10% or less, it is not possible when the effect of improving the film adhesion is saturated even if the annealing separating agent conditions are changed and the effect commensurate with the manufacturing cost cannot be obtained. It was determined to be saturated).

The base steel sheet in the obtained grain-oriented electrical steel sheet contained 0.0014% of C, 3.2% of Si, and 0.08% of Mn in mass%. Further, the grain-oriented electrical steel sheet satisfying the conditions of the present embodiment has a primary coating and an insulating coating, and as _{a result of Mg 2} SiO ₄ analysis in the primary coating, the Mg concentration is 35% by mass or more and the Si concentration. Was 13% by mass, and _{contained Mg 2} SiO ₄ as a main component.

With reference to the results in Table 5, it was found that the grain-oriented electrical steel sheets satisfying the conditions of the present embodiment were judged to be good. Further, when the total of the Ti conversion value A (mass%) of the Ti compound content and the rare earth metal conversion value B (mass%) of the rare earth metal compound content exceeds 12.0%, the effect of improving the adhesion is saturated. It turns out that it only increases the manufacturing cost. Further, when the condition of the present embodiment is satisfied, the Ti emission intensity at a depth of 1 to 10 μm obtained when elemental analysis is performed by the glow discharge emission analysis method from the surface of the primary coating in the plate thickness direction of the directional electromagnetic steel plate. The peak intensity ratio I _{Ti is 5 or more and 25 or less, the total value IREM} of the peak intensity ratio of the emission intensity of rare earth elements is 2 or more and 8 or less, and the peak intensity ratio I _Al of the Al emission intensity is 10 or more. peak intensity ratio _{I B} of B emission intensity is 2.5 to 15, it was found that the peak intensity ratio _{I S} of S emission intensity is 2.5 to 10.

(Example 6)
First, in terms of mass%, C: 0.08%, Si: 3.2%, Mn: 0.08%, S: 0.024%, acid-soluble Al: 0.03%, N: 0.008%, A steel ingot containing Bi: 0.03% and having the balance of Fe and impurities was prepared. The ingot was annealed at 1350 ° C. for 1 hour and then hot-rolled to obtain a hot-rolled steel sheet having a thickness of 2.3 mm. The obtained hot-rolled steel sheet was annealed at a maximum temperature of 1100 ° C. for 140 seconds, pickled and then cold-rolled to obtain a cold-rolled steel sheet having a thickness of 0.23 mm.

Subsequently, the obtained cold-rolled steel sheet was subjected to primary recrystallization annealing in a wet hydrogen atmosphere at 850 ° C. for 180 seconds. Next, after applying an annealing separator containing MgO to the surface of the steel sheet after primary recrystallization annealing, a batch heating furnace is used so that the residence time in the range of 1000 ° C. to 1150 ° C. is 10 hours. The temperature was raised at a heating rate of 15 ° C./h and held at a temperature of 1200 ° C. for 30 hours for finish annealing, and the steel sheet after finish annealing was washed with water. Here, as for the content of the annealing separator, TiO ₂ is converted to 4.2% in Ti, Ce (OH) ₄ is converted to 2.04% in Ce conversion, and H ₃ BO ₃ is converted to B in terms of MgO 100%. It was assumed that 0.61% and SrSO ₄ were 0.95% in terms of Sr, and the balance contained unavoidable impurities. The stirring conditions for the annealing separator were the conditions shown in Table 6. The coating weight of the annealing separator per one side of the steel sheet was 7.0 g / m ² . Then, an insulating film containing aluminum phosphate and colloidal silica as main components was applied to the surface of the steel sheet, and then flattening annealing was performed for the purpose of baking the insulating film and flattening the steel sheet. This flattening annealing was carried out at 850 ° C. for 40 seconds.

After shearing, strain-removing and annealing the sample of the directional electromagnetic steel plate obtained above, a sample having a sample size of 60 mm × 300 mm is subjected to the single plate measurement method described in JIS C2556: 2015. The magnetic flux density B8 value of the directional electromagnetic steel plate (sample after strain relief annealing) according to each of the examples of the present invention and the comparative example was measured. Here, the B8 value is the magnetic flux density of the grain-oriented electrical steel sheet when the grain-oriented electrical steel sheet is excited at 800 A / m at 50 Hz. In the example of the present invention, the average value of five samples was taken as the B8 value. The sample was cut out from the grain-oriented electrical steel sheet after strain removal and annealing so that the longitudinal direction of the grain-oriented electrical steel sheet before shearing and the longitudinal direction of the sample coincided with each other.

Further, the sample was sheared to a width of 30 mm and subjected to a bending test of 10 mmφ. Here, three test pieces are subjected to a bending test, the area of the peeled portion is measured, and the ratio of the area of the peeled portion to the total area is defined as the peeled area ratio for each sample, and the peeled area between the samples is taken as the peeling area ratio. The average value of the rate was calculated.

Further, the components of the base steel sheet in the obtained grain-oriented electrical steel sheet were carried out in the same manner as in Example 1.

Further, in the grain-oriented electrical steel sheet after the final step, the presence or absence of the primary coating and the insulating coating and the components of the primary coating were analyzed by the same method as in Example 1.

Further, after removing the insulating film by immersing the steel sheet after applying and baking the insulating film in a high-temperature alkaline solution, a glow discharge emission analysis method is performed in the direction of the thickness of the directional electromagnetic steel sheet from the surface of the primary film. Elemental analysis by the GDS method) was performed in the same manner as in Example 1.

Table 3 shows the production conditions and measurement results of the above examples of the present invention and comparative examples. The condition that the peeling area ratio of the 10 mmφ bending test was 10% or less was judged to be good. The condition that the peeling area ratio of the 10 mmφ bending test exceeds 10% was judged to be impossible.

The base steel sheet in the obtained grain-oriented electrical steel sheet contained 0.0016% of C, 3.2% of Si, and 0.08% of Mn in mass%. Further, the grain-oriented electrical steel sheet satisfying the conditions of the present embodiment has a primary coating and an insulating coating, and as _{a result of Mg 2} SiO ₄ analysis in the primary coating, the Mg concentration is 35% by mass or more and the Si concentration. Was 13% by mass, and _{contained Mg 2} SiO ₄ as a main component.

With reference to the results in Table 6, it was found that the grain-oriented electrical steel sheets satisfying the conditions of the present embodiment were judged to be good. Further, if the judgment is good, the peak intensity ratio of the Ti emission intensity at a depth of 1 to 10 μm obtained when elemental analysis is performed by the glow discharge emission analysis method from the surface of the primary coating to the thickness direction of the directional electromagnetic steel plate. I _Ti is 5 to 25, sum _{I REM} of the peak intensity ratio of the emission intensity of the rare earth element is 2 to 8, the peak intensity ratio _{I Al} of Al luminous intensity is not less than 10, B luminous intensity is the peak intensity ratio _{I B} is 2.5 to 15, it was found that the peak intensity ratio _{I S} of S emission intensity is 2.5 to 10.
The grain-oriented electrical steel sheet satisfying the conditions of the present embodiment has a primary coating, and as _{a result of Mg 2} SiO ₄ analysis in the primary coating, the Mg concentration is 35% by mass or more and the Si concentration is 13% by mass. Yes, the primary coating _{contained Mg 2} SiO ₄ as a main component.

Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to such examples. It is clear that a person having ordinary knowledge in the field of technology to which the present invention belongs can come up with various modifications or modifications within the scope of the technical ideas described in the claims. , These are also naturally understood to belong to the technical scope of the present invention.

Claims (4)

By mass%, C: 0.02% or more and 0.10% or less,
Si: 2.5% or more and 4.5% or less,
Mn: 0.01% or more and 0.15% or less,
One or two of S and Se: 0.001% or more and 0.050% or less in total,
Acid-soluble Al: 0.01% or more and 0.05% or less, and
N: 0.002% or more and 0.015% or less,
A slab containing Fe and impurities in the balance is heated to 1280 ° C. or higher and hot-rolled to obtain a hot-rolled steel sheet.
A cold-rolling step of forming a cold-rolled steel sheet by subjecting the hot-rolled steel sheet to hot-rolled sheet annealing and then performing one cold-rolling or two or more cold-rolling sandwiching an intermediate annealing.
A primary recrystallization annealing step of applying primary recrystallization annealing to the cold-rolled steel sheet, and
A finish annealing step of applying an annealing separator containing MgO to the surface of the cold-rolled steel sheet after the primary recrystallization annealing step and then performing a finish annealing.
A flattening annealing step of applying an insulating film to the surface of the steel sheet after the finishing annealing step and then performing flattening annealing is included.
The annealing separator contains a Ti compound in an amount of 0.3% or more and 10.0% or less in terms of Ti contained in MgO contained in the annealing separator.
The compound of B is contained in an amount of 0.03% or more and 1.60% or less in terms of B,
Rare earth metal compounds, 0.1% or more and 7.5% or less in terms of contained rare earth metals,
One or more alkaline earth metal compounds containing one or more alkaline earth metal elements selected from the group consisting of Ca, Sr and Ba, in terms of the contained alkaline earth metal. Contains 0.3% or more and 5.8% or less,
The stirring conditions in the preparation of the water slurry of the annealing separator are a temperature of 0 ° C. or higher and 30 ° C. or lower, and a time of 5 minutes or longer and 300 minutes or shorter.
The amount of the annealing separator applied to one side of the cold-rolled steel sheet is 3.5 g / m ² or more and 10.0 g / m ² or less.
The residence time in the finish annealing from 1000 ° C. to 1150 ° C. is 10 hours or more and 100 hours or less.
When the content of the Ti compound with respect to the content of MgO is A (mass%) in terms of Ti, and the content of the compound of the rare earth metal in terms of rare earth metal is B (mass%), the following formula is used. A method for manufacturing a directional electromagnetic steel sheet that satisfies (1).
0.4 ≤ (A + B) ≤ 12.0 ... Equation (1) The method for producing a grain-oriented electrical steel sheet according to claim 1, wherein the slab further contains Bi: 0.0005% or more and 0.0500% or less in mass%. By mass%, C: 0.0050% or less,
Si: 2.5-4.5%, and
Mn: 0.01-0.15%,
A base steel sheet containing Fe and impurities in the balance, and
A primary coating formed on the surface of the base steel sheet and _{containing Mg 2} SiO ₄ as a main component, and
A grain-oriented electrical steel sheet provided with an insulating coating.
In the range of 1 to 10 μm with respect to the emission intensity at a depth of 10 μm obtained by performing elemental analysis by the glow discharge emission analysis method from the surface of the primary coating in the plate thickness direction of the directional electromagnetic steel plate. Regarding the peak intensity ratio I of the maximum emission intensity
Peak intensity ratio of Ti emission intensity I _Ti is 5 or more and 25 or less.
_{The peak intensity ratio IREM} of the emission intensity of rare earth elements is 2 or more and 8 or less.
Al emission intensity peak intensity ratio I _Al is 10 or more,
Peak intensity ratio _{I B} of B emission intensity is 2.5 to 15,
Peak intensity ratio _{I S} of S emission intensity is 2.5 to 10, the grain-oriented electrical steel sheet. The Ti compound in mass% with respect to MgO in the annealing separator is contained in an amount of 0.3% or more and 10.0% or less in terms of Ti.
The compound of B is contained in an amount of 0.03% or more and 1.60% or less in terms of B,
Rare earth metal compounds, 0.1% or more and 7.5% or less in terms of contained rare earth metals,
One or more alkaline earth metal compounds containing one or more alkaline earth metal elements selected from the group consisting of Ca, Sr and Ba, in terms of the contained alkaline earth metal. Contains 0.3% or more and 5.8% or less,
When the content of the Ti compound with respect to the content of MgO is A (mass%) in terms of Ti, and the content of the compound of the rare earth metal in terms of rare earth metal is B (mass%), the following formula is used. An annealing separator that satisfies (1).
0.4 ≤ (A + B) ≤ 12.0 ... Equation (1)

Images