JP2021123768A - 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 having 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 and magnetic characteristics, including the steps of: heating a slab comprising a predetermined component composition 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 2

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, with the techniques disclosed in Patent Documents 4 to 6 above, 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. The problem of peeling from the steel sheet could not be solved, and a technique for improving the adhesion between the primary coating and the steel sheet was sought.

Therefore, the present invention has been made in view of the above problems and the like, and an object of the present invention is to provide a grain-oriented electrical steel sheet which can further improve the adhesion between the primary coating and the steel sheet. It is an object of the present invention to provide a manufacturing method and a grain-oriented electrical steel sheet as well as 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. After applying a slurry-like quenching separator containing MgO to the surface of the cold-rolled steel sheet after the primary recrystallizing step of subjecting the cold-rolled steel sheet to the primary recrystallizing annealing step and the primary recrystallizing annealing step. The ablation separating agent comprises a finish ablation step of applying a finish ablation and a flattening ablation step of applying an insulating film to the surface of a steel sheet after the finish ablation step and then applying a flattening annealing. Ti compound in mass% with respect to MgO contained in the agent, 0.3% or more and 10.0% or less in terms of Ti contained, and compound of rare earth metal, 0 in terms of rare earth metal contained .1% or more and 10% or less, the compound of B is 0.03% or more and 1.60% or less in terms of B contained, and one or more selected from the group consisting of Ca, Sr and Ba. It contains one or more alkaline earth metal compounds containing an alkaline earth metal element, and the content of the alkaline earth metal compound in terms of alkaline earth metal is A with respect to the content of MgO. (% by mass), when the content of the compound of B in terms of B is B (% by mass), the following formula (1) is satisfied, and the annealing separator is 0 ° C. or higher and 30 ° C. or lower. Provided is a method for producing a directional electromagnetic steel sheet, which is produced by stirring at a temperature of 5 minutes or more and 300 minutes or less.
B ≦ A ≦ (0.8 + 3 × B) ・ ・ ・ Equation (1)

Further, in order to solve the above problems, according to another 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: 0.01% 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% The following and N: 0.002% or more and 0.015% or less, and the balance containing Fe and impurities are heated to 1280 ° C. or higher and hot-rolled to obtain a hot-rolled steel sheet. In the hot-rolling process, the hot-rolled steel sheet is hot-rolled, and then cold-rolled once or cold-rolled two or more times with intermediate quenching in between to obtain a cold-rolled steel sheet. A slurry-like quenching separator containing MgO is applied to the surface of the cold-rolled steel sheet after the inter-rolling step, the primary recrystallizing step of applying the primary recrystallizing annealing to the cold-rolled steel sheet, and the primary recrystallizing baking step. The ablation separating agent comprises a finish ablation step of applying a finish ablation and a flattening ablation step of applying an insulating film to the surface of the steel sheet after the finish ablation step and then applying a flattening annealing. Rare earth metal containing a Ti compound in mass% and 0.3% or more and 10.0% or less in terms of Ti contained, and a rare earth metal compound with respect to MgO contained in the annealed separating agent. One or two selected from the group consisting of 0.1% or more and 10% or less in terms of conversion, compound B, and 0.03% or more and 1.60% or less in terms of B contained, Ca, Sr and Ba. It contains one or more kinds of alkaline earth metal compounds containing the above alkaline earth metal elements and sulfate, and is converted into alkaline earth metal of the alkaline earth metal compound with respect to the content of MgO. The amount was defined as A (mass%), the content of the compound B in terms of B was defined as B (mass%), and the content of the sulfate root (SO ₄ ) in ^{terms of 2-} converted was defined as C (mass%). Occasionally, both of the following formulas (2) and (3) are satisfied, and the annealed separator is produced by stirring 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. , A method for manufacturing a directional electromagnetic steel sheet is provided.
0 ≤ A <B ... Equation (2)
(3 × B) ≦ C ≦ (10 × B) ・ ・ ・ Equation (3)

The slab preferably contains Bi: 0.0005% or more and 0.0500% or less in mass%.

In terms of mass%, the slab has Cu: 0.01% or more and 0.30% or less, Sn: 0.01% or more and 0.30% or less, Ni: 0.01% or more and 0.30% or less, Cr: 0. It is preferable to further contain any one or more selected from the group consisting of 0.01% or more and 0.30% or less, or Sb: 0.01% or more and 0.30% or less.

With the above configuration, the quenching separator contains a Ti compound, a rare earth metal compound, and a B compound, and one or more alkaline earth metal elements selected from the group consisting of Ca, Sr, and Ba. By appropriately containing one or more kinds of alkaline earth metal compounds including, or such alkaline earth metal compounds and sulfates, it is possible to further improve the adhesion between the primary coating and the steel plate. Become.

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%, Mn: 0.01 to 0. A base steel sheet containing .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, and connected to the primary coating. _{In the thickness direction of the base steel sheet, an oxide containing MgAl 2} O ₄ as a main component is provided in a range of 0.5 μm or more and 5 μm or less from the boundary of the primary coating on the base steel sheet side. Directional electromagnetic steel sheets are provided.

In terms of mass%, the base steel sheet has Cu: 0.01% or more and 0.30% or less, Sn: 0.01% or more and 0.30% or less, Ni: 0.01% or more and 0.30% or less, Cr. : One or more selected from the group consisting of 0.01% or more and 0.30% or less, or Sb: 0.01% or more and 0.30% or less may be contained.

The magnetic flux density B8 value when a magnetic field of 800 A / m is applied at 50 Hz may be 1.920 T or more.

Further, in order to solve the above problems, according to another viewpoint of the present invention, the Ti compound is contained in an amount of 0.3% or more and 10.0% or less in terms of Ti in mass% with respect to MgO. , 0.1% or more and 10% or less of the rare earth metal compound contained, 0.03% or more and 1.60% or less of the compound of B, and Ca, Sr. And one or more alkaline earth metal compounds containing one or more alkaline earth metal elements selected from the group consisting of Ba, and the alkali with respect to the content of MgO. When the content of the earth metal compound in terms of alkaline earth metal is A (mass%) and the content of the compound B in terms of B is B (mass%), the following formula (1) is used. A satisfactory quenching separator is provided.
B ≦ A ≦ (0.8 + 3 × B) ・ ・ ・ Equation (1)

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 and 10.0% or less in terms of Ti in mass% with respect to MgO. , 0.1% or more and 10% or less of the rare earth metal compound contained, 0.03% or more and 1.60% or less of the compound of B, Ca, Sr and Ba Contains one or more alkaline earth metal compounds containing one or more alkaline earth metal elements selected from the group consisting of, and sulfates, with respect to the MgO content. , The content of the alkaline earth metal compound in terms of alkaline earth metal is A mass%, the content of the compound B in terms of B is B (mass%), and the sulfate root of sulfate (SO ₄ ) ² Provided is an annealed separator characterized by satisfying both the following formulas (2) and (3), where C (% by mass) is the content in terms of ^−.
0 ≤ A <B ... Equation (2)
(3 × B) ≦ C ≦ (10 × B) ・ ・ ・ Equation (3)

As described above, according to the present invention, it is possible to produce a directional electric steel sheet which is more excellent in adhesion between the primary coating and the steel sheet, and more preferably has a more excellent magnetic flux density.

It is a secondary electron image observed with a scanning electron microscope after the directional electromagnetic steel plate after finish annealing was subjected to tilt polishing with an inclination angle of 5 ° and electrolytic polishing. The B-equivalent content of the B compound in the quenching separator is taken on the horizontal axis, and the alkaline earth metal-equivalent content of the alkaline earth metal compound containing the alkaline earth metal element selected from the group consisting of Ca, Sr and Ba. Is a graph in which the results of the conditions B1 to B48, B50 and B51 shown in Tables 2A and 2B are plotted on the vertical axis.

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

As a result of diligent studies on a method for manufacturing grain-oriented electrical steel sheets, the present inventors have diligently studied a method for manufacturing grain-oriented electrical steel sheets in order to further improve the magnetic properties while further improving the adhesion between the primary coating of the grain-oriented electrical steel sheets and the steel sheets. We found the following findings.

Specifically, the present inventors have found that the adhesion between the primary coating and the steel sheet can be further improved by containing the Ti compound, the B compound and the rare earth metal compound in the annealing separator. 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 the molten steel contained Bi 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.

At the same time, it was found that the magnetic flux density may deteriorate if the annealing separator simply contains a Ti compound, a B compound and a rare earth metal compound. Therefore, the present inventors use one or more alkaline earth metal elements selected from the group consisting of Ca, Sr and Ba at the same time as the Ti compound, the B compound and the rare earth metal compound. By appropriately containing one or more kinds of alkaline earth metal compounds including, or such alkaline earth metal compounds and sulfates, the adhesion between the primary coating and the steel plate can be maintained without deteriorating the magnetic flux density. We found that it was possible to improve.

Although the detailed reason why such a phenomenon occurs is not clear, it is presumed that the inclusion of the annealing separator affects the behavior of the inhibitor strength in the secondary recrystallization process. That is, when the annealing separator contains a Ti compound, a B compound and a rare earth metal compound, nitriding of the steel sheet by N contained in the annealing atmosphere is promoted in the secondary recrystallization process, the secondary recrystallization becomes hyperstable, and the magnetic flux becomes magnetic. The density deteriorates. However, the quenching separator further contains one or more alkaline earth metal elements selected from the group consisting of Ca, Sr and Ba in addition to the Ti compound, the B compound and the rare earth metal compound. Deterioration of magnetic flux density is suppressed by appropriately containing seeds or two or more kinds of alkaline earth metal compounds, or such alkaline earth metal compounds and sulfates, and appropriately controlling the inhibitor strength in the plate thickness direction. It is presumed to be a compound.

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. A slab containing Fe and impurities in the balance was heated to 1280 ° C. or higher and hot-rolled to obtain a hot-rolled steel sheet, and the hot-rolled steel sheet was hot-rolled and annealed. After that, a cold rolling step of making a cold-rolled steel sheet by performing one cold-rolling or two or more cold-rolling sandwiching an intermediate quenching process and a primary re-crystallizing of the cold-rolled steel sheet by performing primary re-crystal annealing. A finish annealing step of applying a slurry-like annealing separator containing MgO to the surface of the cold-rolled steel sheet after the annealing step and the primary recrystallization annealing step, and then performing a finish annealing, and a steel sheet after the finish annealing step. Including a flattening and annealing step of applying an insulating film to the surface of the rolling mill and then flattening and rolling, the ablation separating agent is made of Ti in mass% with respect to MgO contained in the ablation separating agent. Contains a compound of 0.3% or more and 10.0% or less in terms of Ti contained, a compound of rare earth metal, and a compound of 0.1% or more and 10% or less in terms of contained rare earth metal, compound B. One or more alkaline soils containing one or more alkaline earth metal elements selected from the group consisting of 0.03% or more and 1.60% or less in terms of B, and Ca, Sr and Ba. It contains a metal-like compound, and the content of the alkaline earth metal compound in terms of alkaline earth metal is A (mass%) with respect to the content of MgO, and the content of the compound B in terms of B is When B (mass%) is satisfied, the following formula (1) is satisfied, and the annealed separator is produced by stirring 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. A method for manufacturing a directional electromagnetic steel sheet is provided.
B ≦ A ≦ (0.8 + 3 × B) ・ ・ ・ 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 sizes of the inhibitors MnS and MnSe tend to be coarse, 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. Further, the acid-soluble Al reacts with MgO 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 described later _{to form MgAl 2} O ₄ (spinel). 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 adopting a manufacturing method in which Bi (bismuth) is contained in a slab.

Generally, when Bi 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 becomes easy to smooth, the anchor effect decreases, and the adhesion deteriorates. However, when the present invention is applied, Bi Even with contained steel, smoothing is suppressed and problems related to adhesion can be solved. Since the slab contains Bi, the heat resistance of the inhibitor is enhanced, and good adhesion can be ensured even in a steel sheet having a further improved magnetic flux density.

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 always essential in steel materials, the lower limit of the content is 0%.

Further, the slab used for manufacturing the grain-oriented electrical steel sheet according to the present embodiment is any one of Cu, Sn, Ni, Cr, or Sb as an element for stabilizing secondary recrystallization in addition to the above-mentioned elements. One kind or two or more kinds may be further contained. When the slab contains the above elements, the iron loss value of the manufactured grain-oriented electrical steel sheet can be further reduced.

When the slab contains any one or more of these elements, the content of each of the contained elements is preferably 0.01% or more and 0.30% or less, respectively. When any one or more of Cu, Sn, Ni, Cr, or Sb is contained in the slab, the content of each of the elements is in the above range to stabilize the secondary recrystallization. The effect of making it can be obtained even more. If the content of each of these elements is less than 0.01%, it is difficult to obtain a sufficient effect of stabilizing secondary recrystallization, which is not preferable. On the other hand, when the content of each of these elements is more than 0.30%, the effect of stabilizing secondary recrystallization is saturated, which is not preferable from the viewpoint of suppressing an increase in production cost. Since these elements are not always essential in steel materials, the lower limit of the content is 0%.

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.

(Hot rolling process)
Subsequently, the slab having the above composition is heated to 1280 ° C. or higher to dissolve the inhibitor component in the slab. 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.

(Finishing annealing 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 based on the solid content contained in the annealing separator. The content of MgO is preferably 50.0% by mass or more and 99.3% by mass or less, and more preferably 70.0% by mass or more and 99.0% by mass with respect to the solid content contained in the annealing separator. % Or less. In addition to MgO, a Ti compound, a rare earth metal compound, an alkaline earth metal compound, and the like may be further contained, such as a sulfate, an Al compound, an Fe compound, and a Si compound. The annealing separator contains the compound in water, is applied to the surface of a steel sheet in the form of a slurry, and is dried. Here, 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 annealing separator according to this embodiment contains at least MgO, Ti compound, rare earth metal compound, and B compound. Further, the quenching separator according to the present embodiment is 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. (Hereinafter, it may be simply referred to as "alkaline earth metal compound".).

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 0.5% or more and 8.5% or less.

In the annealing separator, the content of the rare earth metal compound is 0.1% or more and 10% or less in terms of rare earth metal. The rare earth metal compound contained in the annealing separator contains one or more elements selected from the group consisting of rare earth elements. It is presumed that 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 10%, the annealing separator slurry is applied. It is not preferable because the property deteriorates. Therefore, the content of the rare earth metal compound shall be 0.1% or more and 10% or less in terms of rare earth metal. The content of the rare earth metal compound is preferably 0.2% or more and 8% or less in terms of rare earth metal. 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.

In the above annealing separator, the content of the B compound is 0.0.03% 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, It is not preferable because the effect of improving the adhesion is saturated and the cost increases. Therefore, the content of the B compound shall be 0.0.03% 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.

By including the Ti compound, the rare earth metal compound, and the B compound in the annealing separator, the adhesion between the primary coating and the steel sheet is improved. The details of this mechanism are not clear, but in the process of finish annealing, Ti compounds, rare earth metal compounds and B compounds are formed in the primary coating or at the interface between the primary coating and the steel sheet or in the vicinity thereof, so that Mg _{2 A state in which an oxide containing MgAl 2} O ₄ (spinel) as a main component is connected to the primary film on the base steel plate side of the primary film containing SiO _{4 as a main component, that is, a part of the oxide becomes a primary film.} It is presumed that the anchor effect is exhibited by arranging it in a fixed state. In the following, _{an oxide containing MgAl 2} O ₄ as a main component may be simply referred to as "Al oxide".

In the above quenching separator, the total 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 It is contained so as to satisfy the following formula (1).

B ≦ A ≦ (0.8 + 3 × B) ・ ・ ・ Equation (1)

Here, in the above formula (1), A (%) is an alkaline earth metal conversion value contained in the alkaline earth metal compound with respect to 100% MgO, and B (%) is a B compound with respect to 100% MgO. It is a B conversion value contained in. When the annealing separator contains two or more kinds of alkaline earth metal compounds, the above A (%) is the total value of the converted values of each of the contained alkaline earth metal elements. Further, the alkaline earth metal compound may contain one or more selected from the group consisting of sulfates, carbonates, hydroxides, chlorides and oxides. When the alkaline earth metal compound is one or more of sulfates, carbonates, hydroxides, chlorides and oxides, it is the contained alkaline earth metal equivalent value of the total content. 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. The conversion value of the amount of alkaline earth metal contained is the ratio of the alkaline earth metal element contained in the compound by using the atomic weight of each element from the chemical formula of the alkaline earth metal compound contained in the annealing separator. Can be calculated by multiplying this by the content of the compound in the quenching separator. When two or more kinds of alkaline earth metal compounds 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, use an inductively coupled plasma mass spectrometry (ICP-MS) component analyzer to determine the content of alkaline earth metal. You may measure. Further, the converted values of Ti, B and rare 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.

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. , for example, sulfate, carbonate, hydroxide, include chlorides and oxides, _{specifically, CaSO 4 · 0.5H 2 O,} CaCO 3, SrSO 4, Sr (OH) 2, BaSO 4 , SrCO _{3 and the} like.

When A <B, the magnetic flux density (B8) value of the grain-oriented steel sheet is deteriorated when the grain-oriented electrical steel sheet is excited at 800 A / m at 50 Hz, which is not preferable. On the other hand, when (0.8 + 3 × B) <A, the secondary recrystallization becomes unstable and the B8 value deteriorates, which is not preferable.

In the method for producing grain-oriented electrical steel sheets according to the present embodiment, in order to more reliably exhibit the above effects, the total content of the alkaline earth metal compounds in the annealing separator is preferably B ≦ A ≦ (0. 6 + 3 × B).

The present inventors have found that when the annealing separator contains a Ti compound, a B compound and a rare earth metal compound, the adhesion between the primary coating film and the steel sheet is remarkably improved, and at the same time, the B8 value is deteriorated. This mechanism is not always clear, but in the secondary recrystallization process, nitriding of the steel sheet by N contained in the atmosphere gas of finish annealing progresses, the secondary recrystallization becomes overstable, and the B8 value deteriorates. It is presumed that it will be done. Here, an appropriate amount 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 in the annealing separator. When it is contained, it is presumed that a barrier layer is formed near the interface between the primary coating and the steel sheet in the secondary recrystallization process, suppresses nitridement of the steel sheet by the atmosphere gas of finish annealing, and prevents deterioration of the B8 value.

MgO, which is the main component of the annealing separator, is also an alkaline earth metal compound, but Mg ²⁺ ions diffuse slowly in silica, which is the main component of the decarbonation film, so they are finished in the secondary recrystallization process. It is presumed that the effect of suppressing the nitriding of the annealed atmospheric gas to the steel sheet is not recognized. Therefore, the Mg compound is not considered in the total content of the alkaline earth metal compounds specified in B above.

As described above, Ca contained in 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. If there is an A <B relationship between the total content A (%) in terms of Sr and Ba and the B conversion value B (%) contained in the B compound, the secondary recrystallization is hyperstable. This is not preferable because the B8 value deteriorates. However, the present inventors have set the total content A (%) and the B conversion value B (%) contained in the B compound by containing a predetermined amount of sulfate in the annealing separator. It has been found that even when there is a relationship of A <B, it is possible to produce a grain-oriented electrical steel sheet having excellent magnetic properties and adhesion between the primary coating and the steel sheet.

That is, in detail, the present inventors have one or more kinds of the above-mentioned quenching separator containing one kind or two or more kinds of alkaline earth metal elements selected from the group consisting of Ca, Sr and Ba. When the content of the alkaline earth metal compound is A% in terms of alkaline earth metal, the B conversion value of the B compound is B%, and the relationship between A and B is A <B. Even so, when the relationship of (3 × B) ≦ C ≦ (10 × B) is established, where the content of sulfate _{is C% in terms of sulfate root (SO 4} ) ^{2-conversion, the magnetic properties and} , It has been found that a directional electromagnetic steel plate having excellent adhesion between the primary coating and the steel plate can be produced. In this case, the total content of the alkaline earth metal compound defined in B above satisfies both the relationships represented by the following formulas (2) and (3).

0 ≤ A <B ... Equation (2)
(3 × B) ≦ C ≦ (10 × B) ・ ・ ・ Equation (3)

The above formula (2) includes the case where the value of A is zero, but as shown in the following examples, the value of A is zero (that is, the alkaline earth metal compound is not contained). ) Even in this case, if the sulfate content C satisfies the relationship of the above formula (3), a directional electromagnetic steel sheet having excellent both magnetic properties and adhesion between the primary coating and the steel sheet is produced. be able to.

Also relates to the content C of the sulfate in the formula (3), but the present invention is not particularly limited counterions SO ₄ ^2-ions, present in the annealing separator, generates SO ₄ ^2-ions The anneal compound is the subject of consideration when considering the content C.

In the above formula (3), when C <(3 × B), the B8 value deteriorates, which is not preferable. On the other hand, when (10 × B) <C, the secondary recrystallization may become unstable and the B8 value may deteriorate, which is not preferable.

In addition, it contains one or more alkaline earth metal elements selected from the group consisting of Ca, Sr and Ba contained in the annealing separator so as to satisfy the above formula (2) and the above formula (3). One or more alkaline earth metal compounds are selected from the group consisting of Ca, Sr and Ba contained in the quenching separator so as to satisfy the above formula (1). Similar to one or more alkaline earth metal compounds containing earth metal elements. That is, it contains one or more alkaline earth metal elements selected from the group consisting of Ca, Sr and Ba contained in the quenching separator so as to satisfy the above formula (2) and the above formula (3). One or more kinds of alkaline earth metal compounds are not particularly limited, and examples thereof include sulfates, carbonates, hydroxides, chlorides and oxides, and specifically, CaSO. ₄ · 0.5H _{2 O,} it may be mentioned _{CaCO 3, SrSO 4, Sr (} OH) 2, BaSO 4, SrCO 3 , and the like.

When an appropriate amount of sulfate is contained in the annealing separator, the sulfate decomposes in the secondary recrystallization process, sulfur invades the steel sheet, and sulfides such as MnS are formed in the steel. It is presumed that the effect of improving the inhibitor strength near the surface layer can be obtained. Even if the nitriding of the steel sheet by the atmospheric gas for finish annealing progresses with A <B, the invasion of sulfur from the annealing separator into the steel sheet is appropriately controlled to form MnS near the surface layer, which is secondary. It is presumed that the balance of the inhibitor strength in the plate thickness direction in the recrystallization process is appropriately maintained to prevent the deterioration of the B8 value. Even when (10 × B) <C, good magnetic characteristics may be obtained if the above formula (1) is satisfied. The mechanism is not always clear, but if the annealing separator contains an appropriate amount of alkaline earth metal, the amount of sulfur infiltration may be reduced. Inferred alkaline earth metal, to diffuse the silica which is a main component of decarboxylation film as cation, as a counter ion, and it easily oxygen ions are selected than SO ₄ ^2-ion is partly Will be done.

The annealing separator according to the present embodiment is a slurry containing at least MgO, Ti compound, a rare earth metal compound, and a B compound, and these are dispersed in water. The rare earth metal compound has a large specific gravity, while the B compound. Has a small specific gravity. Therefore, when producing a slurry-like annealing separator, it is necessary to suppress precipitation and floating and stir so that the mixture is uniformly mixed. In order to prepare a slurry-like annealing separator, stirring is carried out at a temperature of 0 ° C. or higher and 30 ° C. or lower for a time of 5 minutes or longer and 300 minutes or shorter. If the temperature of the 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 slurry is more than 30 ° C., the viscosity of the slurry becomes high and the compounds contained in the slurry are not uniformly mixed, and the slurry in which the compounds contained in the annealing separator are uniformly dispersed cannot be obtained, which is preferable. No. If the stirring time is less than 5 minutes, the compounds contained in the slurry are not sufficiently mixed, and a slurry in which the compounds contained in the annealing separator are 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. Therefore, stirring in the preparation of the slurry-like annealing separator in which the compound is dispersed in water is carried out at a temperature of 0 ° C. or higher and 30 ° C. or lower for a time of 5 minutes or longer and 300 minutes or shorter.

The total mass of MgO, Ti compound, rare earth metal compound, and B compound contained in the slurry-like annealing separator is preferably 3% or more and 50% or less with respect to the total mass of the slurry-like annealing separator. .. When the total mass of MgO, Ti compound, rare earth metal compound, and B compound contained in the annealing separator is 3% or more and 50% or less with respect to the total mass of the annealing separator, the compound is uniformly stirred. It is dispersed in water to obtain an annealed separator in a uniformly dispersed state.

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.

Subsequently, finish annealing is performed for the purpose of primary film formation, Al oxide formation and secondary recrystallization. For finish annealing, for example, it is preferable to heat the coiled steel sheet at a temperature of 800 ° C. to 1000 ° C. over 10 hours or more by using a batch type heating furnace or the like. It may also 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.

In the above finish annealing, _{it is connected to a primary coating containing Mg 2} SiO ₄ as a main component, and in the thickness direction of the base steel plate, from the tip position of the primary coating on the base steel plate side to 0.5 μm or more and 5 μm or less. An oxide containing MgAl ₂ O ₄ as a main component is formed in the range of.

(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 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 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.

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.

The 10 mmφ bending adhesion test (10 mmφ bending test) is a bending test performed by installing a sample steel sheet on the testing machine using a cylindrical mandrel bending tester, and observing the surface of the sample steel sheet after the bending test. It is carried out by. 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 a base steel sheet and a base steel sheet containing a predetermined component, and includes _{a primary coating containing Mg 2} SiO ₄ as a main component. ..

[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%. 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. When the Mn content is more than 0.15%, it becomes difficult to dissolve Mn during slab heating, and the precipitation size of the inhibitor becomes coarse, which impairs the optimum size distribution of the inhibitor, which is not preferable. 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.

Further, the base steel sheet of the grain-oriented electrical steel sheet according to the present embodiment contains any one or more of Cu, Sn, Ni, Cr, and Sb as an element for stabilizing secondary recrystallization. You may. When the base steel sheet contains the above elements, the iron loss value can be further reduced, so that better magnetic properties can be obtained.

When the base steel sheet contains any one or more of these elements, the content of each of the contained elements may be 0.01% or more and 0.30% or less in mass%. .. When any one or more of Cu, Sn, Ni, Cr, and Sb are contained in the base steel sheet, the content of each of the elements is within the above range to cause secondary recrystallization. The effect of stabilizing can be further obtained. If the content of each of these elements is less than 0.01%, it may be difficult to sufficiently obtain the effect of stabilizing secondary recrystallization. When the content of each of these elements exceeds 0.30%, the effect of stabilizing secondary recrystallization may be saturated, which is preferable from the viewpoint of suppressing an increase in the manufacturing cost of grain-oriented electrical steel sheets. No. Since these elements are not always essential in steel materials, the lower limit of the content is 0%.

[Primary coating]
Further, the present inventors have _{found that there is a close relationship between the adhesion between the primary coating containing Mg 2} SiO ₄ as a main component and the steel sheet and the presence state of the Al oxide connected to the primary coating. That is, in the directional electromagnetic steel sheet according to the present invention _{, an Al oxide containing MgAl 2} O ₄ (spinel) as a main component is 0.5 μm on the base steel sheet side of the primary coating containing _{Mg 2} SiO _{4 as a main component.} It is arranged in a state of being connected to the primary coating in a range of 5 μm or less.

In grain-oriented electrical steel sheets, the interface between the primary coating and the steel sheet (bare metal) has an inset structure. Specifically, a part of the primary coating penetrates into the inside of the steel sheet from the surface of the steel sheet. A part of the primary coating that has entered the inside of the steel sheet from the surface of the steel sheet exerts a so-called anchor effect to improve the adhesion of the primary coating to the steel sheet. Oxides have penetrated further to the steel sheet side than the primary coating mainly composed of Mg ₂ SiO _4. The main component of the oxide in the region where the oxide penetrates deeper into the steel sheet than the primary coating mainly composed of Mg ₂ SiO _{4 is Mg Al 2} O ₄ (spinel), which is a kind of Al oxide. It is presumed that the peak of Al emission intensity obtained when the elemental analysis by the glow discharge emission analysis method is performed reflects the existence position of _{MgAl 2} O _4.

However, under the condition that the annealing separator of the present invention contains a Ti compound, a rare earth metal compound, and a B compound, although the adhesion between the primary coating and the steel sheet is remarkably improved, the primary coating of the Al emission intensity peak is described above. The depth position (Al peak position) from the surface did not change much. As a result of detailed investigation of the vicinity of the interface between the primary coating and the base iron, the present inventors have found that the annealing separator exists on the base steel plate side of the primary coating under the condition that the Ti compound, the rare earth metal compound, and the B compound are contained. For the _{first time, it was clarified that the Al oxide containing Mg Al 2} O ₄ as a main component is firmly linked to the primary film. It is presumed that the Al oxide linked to these primary coatings exists like spikes to further enhance the anchor effect.

In order to investigate the existence state of Al oxide in detail, for example, it is effective to magnify and observe a minute region by polishing a steel sheet having a primary coating at a slight inclination (inclination polishing). .. The present inventors have succeeded in observing the vicinity of the interface between the primary coating and the base metal in detail at an angle of about 4 ° from the surface of the steel sheet and polishing it at an angle of about 15 times. Further, when the sample after the inclined polishing was electrolytically polished with a charge amount of ^{about 0.33 C / mm 2 on} the polished surface on which the base iron was exposed, the _{primary containing Mg 2} SiO ₄ as a main component was obtained. We succeeded in selectively electrolytically removing the base iron on the base steel plate side of the coating. It was confirmed by confocal laser scanning microscope observation that the depth of electrolytic removal of the base steel on the base steel plate side of the primary coating was about 5 μm. As the electrolytic solution, No. 1 of Table 2 in the following known document 1 is used. Six conditions were used: 4% MS + 5% TET: 4% methyl salicylate + 1% salicylic acid + 1% TMAC + 5% TET + methyl. Here, TMAC is tetramethylammonium chloride, TET is triethylenetetramine, and MS is methyl salicylate.

Known Document 1: Iron and Steel Tetsu-to-Hagane Vol. 104 (2018) No. 11, P634

Here, when the region where the base iron on the base steel plate side was selectively removed from the primary coating was observed in detail with a scanning electron microscope, the quenching separator did not contain the Ti compound, the rare earth metal compound, and the B compound at the same time. Under the conditions, almost only ground iron was observed, whereas under the conditions containing Ti compounds, rare earth metal compounds, and B compounds, _{many Al oxides containing MgAl 2} O ₄ (spinel) as the main component were observed. rice field. FIG. 1 shows a scanning electron microscope image. FIG. 1 is a secondary electron image obtained by tilt-polishing a directional electromagnetic steel plate after finish annealing with an inclination angle of 5 °, electrolytic polishing, and then observing with a scanning electron microscope. Under the condition that the annealing separator contained Ti compound, rare earth metal compound, and B compound, Al oxide was observed even though the base iron was electrolyzed to a depth of about 5 μm because Al oxide was the primary. It is presumed that it exists because it is firmly connected to the coating film. On the other hand, the reason why Al oxide was hardly observed under the condition that Ti compound, rare earth metal compound, and B compound were not contained at the same time was that Al oxide was not present in connection with the primary coating, or the connection was weak. Therefore, it is presumed that it was discharged or blown off during the electrolysis and the cleaning / drying process after the electrolysis. It is presumed that the Al oxide present in connection with the primary coating exerts a spike effect and further improves the adhesion between the primary coating and the base iron. The oxide component was investigated using an energy dispersive X-ray analyzer attached to the scanning electron microscope.

The _{range of existence of the Al oxide containing Mg Al 2} O ₄ as the main component in the thickness direction of the base steel sheet, which exists in a state of being connected to the base steel sheet side of the primary coating containing _{Mg 2} SiO _{4 as the main component, is} The range is from the boundary (tip position) on the base steel plate side of the primary coating to 0.5 μm or more and 5.0 μm or less. When the existence range of Al oxide in the thickness direction of the base steel sheet is less than 0.5 μm from the boundary on the base steel sheet side of the primary coating, the spike effect is not sufficient, so that a sufficient coating adhesion improving effect can be obtained. Not preferable. When the abundance range of the Al oxide in the thickness direction of the base steel sheet extends over 5.0 μm from the boundary of the primary coating on the base steel plate side, not only the effect of improving the film adhesion is saturated, but also the effect on the annealing separator is applied. It is not preferable because it requires a large amount of the Ti compound, the rare earth metal compound, and the B compound to be added, which increases the cost. The range of existence of the Al oxide is preferably a range of 0.5 μm or more and 4.5 μm or less from the boundary of the primary coating on the base steel sheet side in the thickness direction of the base steel sheet, and more preferably 0. It is 5 μm or more and 4.0 μm or less.

Here, _{the boundary (tip position) on the base steel plate side of the primary coating containing Mg 2} SiO ₄ as a main component is shown in the secondary electron image obtained by observing the sample after inclined polishing / electrolytic polishing with a scanning electron microscope. The position was set so that the amount of primary coating existing on the line drawn parallel to the surface was 50%. Similarly, the position of Al oxide is the amount of Al oxide present on the line drawn parallel to the surface in the secondary electron image of the sample after tilt polishing and electrolysis observed with a scanning electron microscope. Was set to a region of 10% or more, and the position where the amount of Al oxide was 10% was defined as the boundary on the base steel plate side of Al oxide. At the position where the amount of the primary coating is 50%, the amount of Al oxide is 10% or more. Therefore, the range of existence of Al oxide is the boundary on the base material steel plate side of the primary coating measured by the secondary electron image. The length from to the boundary on the steel plate side of the base metal of Al oxide was used as the value of the depth converted from the tilt polishing angle.

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.

The primary coating may contain, for example, an Al compound, a sulfide, an Fe compound, or the like.

The main component of the primary coating is, for example, in a directional electromagnetic steel plate after the final step, after the cross section is mirror-polished, an energy dispersive X-ray analyzer or a fluorescent X-ray analyzer attached to a scanning electron microscope is used. Can be measured. 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.

[Insulation film]
As described above, the insulating coating contains aluminum phosphate, colloidal silica, or the like as a main component. However, as described above, 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.

In the grain-oriented electrical steel sheet according to the present embodiment, it is preferable that the magnetic flux density B8 value is further controlled. Specifically, in the grain-oriented electrical steel sheet according to the present embodiment, the magnetic flux density B8 value is preferably 1.920 T or more, and more preferably 1.930 T or more. Here, the magnetic flux density B8 value is the magnetic flux density when a magnetic field of 800 A / m is applied to the grain-oriented electrical steel sheet at 50 Hz. When the magnetic flux density B8 value is less than 1.920 T, the iron loss value (particularly, hysteresis loss) of the grain-oriented electrical steel sheet may become large. The upper limit of the magnetic flux density B8 value is not particularly limited, but in reality, it may be 2.0T, for example. 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, for the magnetic properties of grain-oriented electrical steel sheets, a method based on the Epstein test specified in JIS C2550: 2011, or a single-plate magnetic property test method (Single Sheet Tester: SST) specified in JIS C2556: 2015 is used. It can be measured by. 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 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: 3.2%, Mn: 0.08%, S: 0.025%, acid-soluble Al: 0.03%, N: 0.008%, Steel ingot A containing Bi: 0.02% and the balance consisting of Fe and impurities, and by mass%, C: 0.08%, Si: 3.2%, Mn: 0.08%, S: 0 A steel ingot R containing .025%, acid-soluble Al: 0.03%, and N: 0.008% 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, the temperature is raised at a heating rate of 15 ° C./h using a batch heating furnace to a temperature of 1200 ° C. Then, it was held for 30 hours and annealed for finishing. Then, the steel sheet after finishing annealing was washed with water. Here, the content of the annealing separator was 100% MgO _{, 2% of CeO 2} in terms of Ce, the balance was unavoidable impurities, and the compounds under the conditions shown in Tables 1A and 1B were contained. The stirring conditions of the annealing separator were 30 minutes at 5 ° C. after adding the compounds under the conditions shown in Tables 1A and 1B. 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 and annealing the sample of the grain-oriented electrical steel sheet obtained above, the 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 grain-oriented electrical steel (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.

Here, when the ingot contains Bi, it is determined that the condition that the magnetic flux density B8 value of the grain-oriented electrical steel sheet is 1.920 T or more and the peeling area ratio of the 10 mmφ bending test is 10% or less is good. , It was determined that the condition that the magnetic flux density B8 value of the grain-oriented electrical steel sheet was less than 1.920 T or the peeling area ratio of the 10 mmφ bending test was more than 10% was not possible. Further, when the ingot does not contain Bi, it is judged that the condition that the magnetic flux density B8 value of the grain-oriented electrical steel sheet is 1.910T or more and the peeling area ratio of the 10 mmφ bending test is 5% or less is good. , It was determined that the condition that the magnetic flux density B8 value of the grain-oriented electrical steel sheet was less than 1.910T or the peeling area ratio of the 10 mmφ bending test was more than 5% was not possible.

Further, after the cross section of the directional electromagnetic steel plate after the final step was mirror-polished, the presence or absence of a primary coating was confirmed using an energy dispersive X-ray analyzer attached to a 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.

The production conditions and measurement results of the above examples of the present invention and comparative examples are shown in Tables 1A and 1B. Conditions A1 to A31 shown in Tables 1A and 1B are examples using steel ingot A, and conditions R1 to R16 are examples using steel ingot R.

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.

With reference to the results in Tables 1A and 1B, it was found that the grain-oriented electrical steel sheets satisfying the conditions of the present embodiment were judged to be good.

(Example 2)
First, in terms of mass%, C: 0.08%, Si: 3.3%, Mn: 0.08%, S: 0.004%, Se: 0.018%, acid-soluble Al: 0.03%, A steel ingot containing N: 0.009% and Bi: 0.03%, the balance of which was composed of the components shown in Tables 2A and 2B below, Fe and impurities was prepared. The ingot was annealed at 1380 ° 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 is raised at a heating rate of 15 ° C./h using a batch heating furnace to a temperature of 1200 ° C. Then, it was held for 30 hours and annealed for finishing. Then, the steel sheet after finishing annealing was washed with water. Here, the content of the annealing separator is 100% MgO _{, 2% of Ce (OH) 4} in terms of Ce, the balance is unavoidable impurities, and the compounds under the conditions shown in Tables 2A and 2B are contained. bottom. The stirring conditions of the annealing separator were 20 minutes at 10 ° C. after adding the compounds under the conditions shown in Tables 2A and 2B. Then, after applying an insulating film containing aluminum phosphate and colloidal silica as main components on the surface of the steel sheet, flattening annealing for the purpose of baking the insulating film and flattening the steel sheet was performed at 850 ° C. for 40 seconds. provided.

After shearing and annealing the sample of the directional electromagnetic steel plate obtained above, the 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 according to each of the examples of the present invention and the comparative example was measured. 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. In this example, as in Example 1, the average value of the five samples was taken as the B8 value. In addition, the magnetic aging characteristics were evaluated by the following method. That is, the sample after shearing, strain removal and annealing is subjected to magnetic domain control processing, and the iron loss W _{17/50 of the grain-oriented electrical steel sheet is subjected to the single plate measurement method described in JIS C2556: 2015.} (W / kg) was measured, and when the relationship of the following formula (A) was established, it was determined to be magnetic aging. Here, T is the thickness (mm) of the sample of the grain-oriented electrical steel sheet. Note that W _17/50 is an iron loss obtained by exciting a grain-oriented electrical steel sheet to 1.7 T at 50 Hz, and the average value of five samples is W _{17/50 as in Example 1.} And said. The magnetic domain control process was performed by laser irradiation. The direction of laser irradiation was a direction perpendicular to the longitudinal direction of the directional electromagnetic steel plate (that is, a direction perpendicular to the longitudinal direction of the sample), and the laser irradiation interval P was 4 mm. The laser irradiation energy density Ua was set to 2.0 mJ / mm ² .
W _17/50 > (-2.5 x B8) + (1.25 x T) +5.4 ... Equation (A)

Further, the sample was sheared to a width of 30 mm and subjected to a bending test of 10 mmφ. Here, three test pieces were subjected to a bending test to obtain an average value of the peeled area ratio. The peeled area ratio was calculated by the same method as in Example 1.

The presence or absence of the primary coating and the component analysis of the primary coating on the grain-oriented electrical steel sheet after the final step were carried out in the same manner as in Example 1.

Here, it was judged that the condition that the magnetic flux density B8 value of the grain-oriented electrical steel sheet was 1.920 T or more and the peeling area ratio of the 10 mmφ bending test was 10% or less was good. Further, when the magnetic flux density B8 value of the grain-oriented electrical steel sheet is less than 1.920 T, when the peeling area ratio of the 10 mmφ bending test is more than 10%, or when the relationship of the formula (A) is established with respect to the magnetic aging characteristics. The condition of any of the above was judged to be impossible (prescription).

The production conditions and measurement results of the above examples of the present invention and comparative examples are shown in Tables 2A and 2B.

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.

With reference to the results in Tables 2A and 2B, it was found that the grain-oriented electrical steel sheets satisfying the conditions of the present embodiment were judged to be good.

Here, paying attention to the amount of B compound and the amount of alkaline earth metal compound of the quenching separator, the B conversion value B (%) of the B compound content is taken on the horizontal axis and selected from the group consisting of Ca, Sr and Ba. Conditions B1 to B48, B50, B51 on a plane in which the content of the alkaline earth metal compound containing the alkaline earth metal element is taken on the vertical axis as A% in terms of the contained Ca, Sr and Ba. These contents were plotted for. The graph obtained by the above is shown in FIG. In FIG. 2, an example having a magnetic flux density of 1.920 T or more is plotted with round dots, and an example having a magnetic flux density of less than 1.920 T is indicated by ×. The conditions B49 and B52 are not shown in FIG. 2 because the Ti compound equivalent content does not satisfy the conditions of the present embodiment.

As shown in FIG. 2, the B conversion value B (%) of the B compound content in the annealing separator of the electromagnetic steel sheet having a magnetic flux density of 1.920 T or more and at least one of Ca, Sr and Ba in the annealing separator. The relationship of the following formula (101) specified in the conditions according to the present embodiment is between the content of the compound containing one kind and the conversion value A (%) by the contained Ca, Sr and Ba. Was found to hold.

B ≦ A ≦ (0.8 + 3 × B) (However, 0.03 ≦ B ≦ 1.60) ・ ・ Equation (101)

(Example 3)
First, in terms of mass%, C: 0.08%, Si: 3.4%, Mn: 0.08%, S: 0.027%, acid-soluble Al: 0.03%, N: 0.008%, Ingot C containing Bi: 0.01% and the balance consisting of Fe and impurities, and by mass%, C: 0.08%, Si: 3.4%, Mn: 0.08%, S: 0 A steel ingot S containing .027%, acid-soluble Al: 0.03%, and N: 0.008% 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, the temperature is raised at a heating rate of 15 ° C./h using a batch heating furnace to a temperature of 1200 ° C. Then, it was held for 30 hours and annealed for finishing. Then, the steel sheet after finishing annealing was washed with water. Here, the content of the annealing separator was assumed to contain La ₂ O ₃ at 2% in terms of La with respect to 100% MgO, the balance containing unavoidable impurities, and compounds under the conditions shown in Tables 3A and 3B. .. The stirring conditions of the annealing separator were 200 minutes at 5 ° C. after adding the compounds under the conditions shown in Tables 3A and 3B. Then, after applying an insulating film containing aluminum phosphate and colloidal silica as main components on the surface of the steel sheet, flattening annealing for the purpose of baking the insulating film and flattening the steel sheet was performed at 850 ° C. for 40 seconds. provided.

After shearing and annealing the sample of the directional electromagnetic steel plate obtained above, the 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 according to each of the examples of the present invention and the comparative example was measured. In this example, as in Example 1, the average value of the 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 were subjected to a bending test to obtain an average value of the peeled area ratio. The peeled area ratio was calculated by the same method as in Example 1.

The presence or absence of the primary coating and the component analysis of the primary coating on the grain-oriented electrical steel sheet after the final step were carried out in the same manner as in Example 1.

Here, when the ingot contains Bi, it is determined that the condition that the magnetic flux density B8 value of the grain-oriented electrical steel sheet is 1.920 T or more and the peeling area ratio of the 10 mmφ bending test is 10% or less is good. , It was determined that the condition that the magnetic flux density B8 value of the grain-oriented electrical steel sheet was less than 1.920 T or the peeling area ratio of the 10 mmφ bending test was more than 10% was not possible. Further, when the ingot does not contain Bi, it is judged that the condition that the magnetic flux density B8 value of the grain-oriented electrical steel sheet is 1.910T or more and the peeling area ratio of the 10 mmφ bending test is 5% or less is good. , It was determined that the condition that the magnetic flux density B8 value of the grain-oriented electrical steel sheet was less than 1.910T or the peeling area ratio of the 10 mmφ bending test was more than 5% was not possible.

The production conditions and measurement results of the above examples of the present invention and comparative examples are shown in Tables 3A and 3B. Conditions C1 to C24 shown in Table 1 are examples using steel ingot C, and conditions S1 to S8 are examples using steel ingot S.

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.

With reference to the results in Tables 3A and 3B, it was found that the grain-oriented electrical steel sheets satisfying the conditions of the present embodiment had better judgment.

Here, the B conversion value B (%) of the B compound content in the annealing separator and one or more alkaline earth metal elements selected from the group consisting of Ca, Sr and Ba are added to the annealing separator. Converted value A (%) by Ca, Sr and Ba contained as the content of one or more alkaline earth metal compounds including, and sulfate root (SO ₄ ) as the content of sulfate in the annealing separator. It was found that there is a relationship between the following equations (102) and (103) defined in the conditions according to the present embodiment with the ^{2-conversion C (%).}

0 ≤ A <B (where 0.03 ≤ B ≤ 1.60) ... Equation (102)
(3 × B) ≦ C ≦ (10 × B) (However, 0.03 ≦ B ≦ 1.60) ・ ・ Equation (103)
As described above, by the method for producing a grain-oriented electrical steel sheet according to the present embodiment, which satisfies the formulas (102) and (103), a grain-oriented electrical steel sheet having a higher magnetic flux density and excellent adhesion between the primary coating and the steel sheet can be obtained. It turned out that it was possible to manufacture.

(Example 4)
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 consisting of the components shown in Table 4 and 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 is raised at a heating rate of 15 ° C./h using a batch heating furnace to a temperature of 1200 ° C. Then, it was held for 30 hours and annealed for finishing. Then, the steel sheet after finishing annealing was washed with water. Here, contents of the annealing separating agent, relative _MgO100%, 2.0% and Y 2 _{O 3} with Y _terms, CaSO 4 · 0.5H 1.66% to ₂ O in Ca terms, the balance being unavoidable It was assumed that the target impurities and the compounds under the conditions shown in Table 4 were contained. The stirring conditions of the annealing separator were 200 minutes at 30 ° C. after adding the compounds under the conditions shown in Table 4. 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 at 850 ° C. for 40 seconds for the purpose of baking the insulating film and flattening the steel sheet. ..

After shearing and annealing the sample of the directional electromagnetic steel plate obtained above, the 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 according to each of the examples of the present invention and the comparative example was measured. In this example, as in Example 1, the average value of the 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 were subjected to a bending test to obtain an average value of the peeled area ratio. The peeled area ratio was calculated by the same method as in Example 1.

The presence or absence of the primary coating and the component analysis of the primary coating on the grain-oriented electrical steel sheet after the final step were carried out in the same manner as in Example 1.

Further, in the grain-oriented electrical steel sheet after the final step, after removing the insulating film and the primary film, the components of the base steel sheet were analyzed. The contents of Si, Mn, Cu, Sn, Ni, Cr and Sb were analyzed by inductively coupled plasma emission spectroscopy. The C content was measured using a carbon / sulfur analyzer. The N content was measured using an oxygen / nitrogen analyzer.

Here, it was judged that the condition that the magnetic flux density B8 value of the grain-oriented electrical steel sheet was 1.920 T or more and the peeling area ratio of the 10 mmφ bending test was 10% or less was good. Further, it was determined that the condition that the magnetic flux density B8 value of the grain-oriented electrical steel sheet was less than 1.920 T or the peeling area ratio of the 10 mmφ bending test was more than 10% was not possible.

Table 4 shows the manufacturing conditions and measurement results of the above-mentioned examples of the present invention and comparative examples, and Table 5 shows the components of the base steel sheet of the grain-oriented electrical steel sheet after the final process.

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.

Referring to the results of Tables 4 and 5, when the formula (101) is satisfied, Cu: 0.01% or more and 0.30% or less, Sn: 0.01% or more and 0.30% or less, Ni in mass%. : 0.01% or more and 0.30% or less, Cr: 0.01% or more and 0.30% or less, or Sb: 0.01% or more and 0.30% or less, whichever one or more is further contained. Even so, it was found that the directional electromagnetic steel plate satisfying the conditions of the present embodiment was judged to be good.

(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 consisting of the components shown in Table 6 and 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 is raised at a heating rate of 15 ° C./h using a batch heating furnace to a temperature of 1200 ° C. Then, it was held for 30 hours and annealed for finishing. Then, the steel sheet after finishing annealing was washed with water. Here, contents of the annealing separating agent, relative MgO100%, 4% of CeO 2 with Ce terms, the MgSO 4 (SO 4) 2- in terms of 4.0%, the balance and inevitable impurities, Table It was assumed that the compound under the conditions shown in 6 was included. The stirring conditions of the annealing separator were 50 minutes at 10 ° C. after adding the compounds under the conditions shown in Table 6. 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 at 850 ° C. for 40 seconds for the purpose of baking the insulating film and flattening the steel sheet. ..

After shearing and annealing the sample of the directional electromagnetic steel plate obtained above, the 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 according to each of the examples of the present invention and the comparative example was measured. In this example, as in Example 1, the average value of the 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 were subjected to a bending test to obtain an average value of the peeled area ratio. The peeled area ratio was calculated by the same method as in Example 1.

The presence or absence of the primary coating and the component analysis of the primary coating on the grain-oriented electrical steel sheet after the final step were carried out in the same manner as in Example 1.

Furthermore, the components of the ingot and the components of the base steel sheet after removing the insulating coating and the primary coating on the grain-oriented electrical steel sheet after the final process were analyzed. The contents of Si, Mn, Cu, Sn, Ni, Cr and Sb were analyzed by inductively coupled plasma emission spectroscopy. The C content was measured using a carbon / sulfur analyzer. The N content was measured using an oxygen / nitrogen analyzer.

Here, it was judged that the condition that the magnetic flux density B8 value of the grain-oriented electrical steel sheet was 1.920 T or more and the peeling area ratio of the 10 mmφ bending test was 10% or less was good. Further, it was determined that the condition that the magnetic flux density B8 value of the grain-oriented electrical steel sheet was less than 1.920 T or the peeling area ratio of the 10 mmφ bending test was more than 10% was not possible.

Table 6 shows the manufacturing conditions and measurement results of the above-mentioned examples of the present invention and comparative examples, and Table 7 shows the components of the base steel sheet of the grain-oriented electrical steel sheet after the final process.

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.

With reference to the results in Tables 6 and 7, when the formulas (102) and (103) are satisfied, Cu: 0.01% or more and 0.30% or less, Sn: 0.01% or more and 0. 30% or less, Ni: 0.01% or more and 0.30% or less, Cr: 0.01% or more and 0.30% or less, or Sb: 0.01% or more and 0.30% or less, any one or 2 It was found that the directional electromagnetic steel plate satisfying the conditions of the present embodiment was judged to be better even if it contained more seeds or more.

(Example 6)
The samples shown in Table 8 are selected from Examples 1, 3, 4, and 5 and exist in a state of being connected to the base steel plate side of the primary coating containing _{Mg 2} SiO _{4 as a main component.} The range of existence of Al oxide containing _{Mg Al 2} O _{4 as a main component was investigated.} The tilt polishing angle of the sample was set to an angle of about 4 ° from the surface of the steel sheet, magnified about 15 times, and the vicinity of the interface between the primary coating and the base metal was observed in detail. Further, the sample after the inclined polishing was electrolytically polished with a charge amount of ^{about 0.33 C / mm 2 on the polished surface where the base iron was exposed.} As the electrolytic solution, 4% MS + 5% TET: 4% methyl salicylate + 1% salicylic acid + 1% TMAC + 5% TET + Methyl was used. Here, TMAC: tetramethylammonium chloride and TET: triethylenetetramine were used. Here, it was confirmed by confocal laser scanning microscope observation that the depth of electrolytic removal of the base iron on the base steel plate side from the primary coating containing _{Mg 2} SiO _{4 as a main component was about 5 μm.}

Subsequently, the region where the base iron on the base steel plate side was selectively removed from the primary coating was observed in detail with a scanning electron microscope. Here, the _{boundary on the base steel plate side of the primary coating containing Mg 2} SiO ₄ as a main component is drawn parallel to the surface in the secondary electron image of the sample after tilt polishing and electrolysis observed with a scanning electron microscope. The position was set so that the amount of primary coating existing on the vertical line was less than 50%. Similarly, the presence position of Al oxide is such that the amount of Al oxide present on the line drawn parallel to the surface in the secondary electron image obtained by observing the sample after tilt polishing and electrolysis with a scanning electron microscope is 10. The region was defined as% or more, and the position where the amount of Al oxide was 10% was defined as the boundary on the base steel plate side of Al oxide. The range of existence of Al oxide is the depth obtained by converting the length from the boundary on the base steel plate side of the primary coating to the boundary on the base steel plate side of the Al oxide measured by the secondary electron image, converted from the tilt polishing angle. It was set as the value of. The oxide components were investigated using an energy dispersive X-ray analyzer attached to the scanning electron microscope.

Table 8 shows the range of existence of Al oxide containing Mg _{Al 2} O ₄ (spinel) as a main component, which is present in a state of being connected to the base steel plate side of the primary coating containing _{Mg 2} SiO _{4 as a main component.} It was found that when the abundance range of the Al oxide is in the range from the boundary of the primary coating on the base steel plate side to 0.5 μm or more and 5.0 μm or less on the base steel plate side, the film adhesion is good.

(Example 7)
First, in terms of mass%, C: 0.08%, S: 0.025%, acid-soluble Al: 0.03%, N: 0.008%, Bi: 0.02% are contained, and the balance is shown in Table 9. A steel ingot consisting of Si and Mn having the contents shown in the above, and 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 plate thickness of 23 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 is raised at a heating rate of 15 ° C./h using a batch heating furnace to a temperature of 1200 ° C. Then, it was held for 30 hours and annealed for finishing. Then, the steel sheet after finishing annealing was washed with water. Here, contents of the annealing separating agent, relative _{MgO100%, CaSO 4 · 0.5H 1.10} % or 1.66% to ₂ O in Ca terms, 2.0% CeO ₂ with Ce terms, The balance was assumed to contain unavoidable impurities and compounds under the conditions shown in Table 9. The stirring conditions of the annealing separator were 20 minutes at 5 ° C. after adding the compounds under the conditions shown in Table 9. The amount of the annealing separator applied after drying was 7 g / m ² per one side of the steel sheet. 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 and annealing the sample of the directional electromagnetic steel plate obtained above, the 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 according to each of the examples of the present invention and the comparative example was measured. In this example, as in Example 1, the average value of the five samples was taken as the B8 value.

Further, the sample was sheared to a width of 30 mm and subjected to a bending test of 10 mmφ. Here, three test pieces were subjected to a bending test to obtain an average value of the peeled area ratio. The peeled area ratio was calculated by the same method as in Example 1.

The presence or absence of the primary coating and the component analysis of the primary coating on the grain-oriented electrical steel sheet after the final step were carried out in the same manner as in Example 1.

Further, in the grain-oriented electrical steel sheet after the final step, after removing the insulating film and the primary film, the components of the base steel sheet were analyzed. The contents of Si and Mn were analyzed by inductively coupled plasma emission spectroscopy. The C content was measured using a carbon / sulfur analyzer. The range of existence of the Al oxide _{containing Mg Al 2} O ₄ as the main component, which exists in a state of being connected to the base steel plate side of the primary coating containing _{Mg 2} SiO _{4 as the main component, is the same as that described in Example 6.} Investigated by the method.

Here, it was judged that the condition that the magnetic flux density B8 value of the grain-oriented electrical steel sheet was 1.920 T or more and the peeling area ratio of the 10 mmφ bending test was 10% or less was good. Further, it was determined that the condition that the magnetic flux density B8 value of the grain-oriented electrical steel sheet was less than 1.920 T or the peeling area ratio of the 10 mmφ bending test was more than 10% was not possible.

Table 9 shows the production conditions and measurement results of the above examples of the present invention and comparative examples.

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.

Table 9 shows the range of existence of Al oxide containing _{MgAl 2} O ₄ (spinel) as a main component, which exists in a state of being connected to the base steel plate side of the primary coating containing _{Mg 2} SiO _{4 as a main component.} rice field. When the abundance range of the Al oxide is 0.5 μm or more and 5.0 μm or less from the boundary of the primary coating on the base steel plate side to the base steel plate side, the film adhesion is good and the directionality that satisfies the condition of the present embodiment is achieved. It was found that the electromagnetic steel sheet had a good judgment.

(Example 8)
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, the temperature is raised at a heating rate of 15 ° C./h using a batch heating furnace to a temperature of 1200 ° C. Then, it was held for 30 hours and annealed for finishing. Then, the steel sheet after finishing annealing was washed with water. Here, the content of the annealing separator was 100% MgO _{, 5.0% of CeO 2} in terms of Ce, the balance was unavoidable impurities, and the compounds under the conditions shown in Table 10 were contained. The stirring conditions of the annealing separator were 30 minutes at 15 ° C. after adding the compounds under the conditions shown in Table 10. Then, after applying an insulating film containing aluminum phosphate and colloidal silica as main components on the surface of the steel sheet, flattening annealing for the purpose of baking the insulating film and flattening the steel sheet was performed at 850 ° C. for 40 seconds. provided.

After shearing and annealing the sample of the directional electromagnetic steel plate obtained above, the 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 according to each of the examples of the present invention and the comparative example was measured. In this example, as in Example 1, the average value of the 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 were subjected to a bending test to obtain an average value of the peeled area ratio. The peeled area ratio was calculated by the same method as in Example 1.

The presence or absence of the primary coating and the component analysis of the primary coating on the grain-oriented electrical steel sheet after the final step were carried out in the same manner as in Example 1.

Here, it was judged that the condition that the magnetic flux density B8 value of the grain-oriented electrical steel sheet was 1.920 T or more and the peeling area ratio of the 10 mmφ bending test was 10% or less was good. Further, it was determined that the condition that the magnetic flux density B8 value of the grain-oriented electrical steel sheet was less than 1.920 T or the peeling area ratio of the 10 mmφ bending test was more than 10% was not possible.

Table 10 shows the production conditions and measurement results of the above examples of the present invention and comparative examples.

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.

With reference to the results in Table 10, it was found that the grain-oriented electrical steel sheet satisfying the conditions of the present embodiment, which was manufactured by performing cold rolling twice at the time of its manufacture, had a good judgment.

(Example 9)
First, in terms of mass%, C: 0.08%, Si: 3.2%, Mn: 0.08%, S: 0.023%, 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 subjected to primary cold rolling 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 is raised at a heating rate of 15 ° C./h using a batch heating furnace to a temperature of 1200 ° C. Then, it was held for 30 hours and annealed for finishing. Then, the steel sheet after finishing annealing was washed with water. Here, contents of the annealing separating agent, relative MgO100%, 3.0% of TiO ₂ in terms of Ti, _5.0% of CeO ₂ with Ce _terms, the H 3 BO ₃ in terms of B 0.61 _%, 1.1% in Ca converted CaSO 4 · 0.5H ₂ O, the balance was assumed to contain inevitable impurities. The stirring conditions for the annealing separator were the conditions shown in Table 11. Then, after applying an insulating film containing aluminum phosphate and colloidal silica as main components on the surface of the steel sheet, flattening annealing for the purpose of baking the insulating film and flattening the steel sheet was performed at 850 ° C. for 40 seconds. provided.

After shearing and annealing the sample of the directional electromagnetic steel plate obtained above, the 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 according to each of the examples of the present invention and the comparative example was measured. In this example, as in Example 1, the average value of the 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 were subjected to a bending test to obtain an average value of the peeled area ratio. The peeled area ratio was calculated by the same method as in Example 1.

The presence or absence of the primary coating and the component analysis of the primary coating on the grain-oriented electrical steel sheet after the final step were carried out in the same manner as in Example 1.

Here, it was judged that the condition that the magnetic flux density B8 value of the grain-oriented electrical steel sheet was 1.920 T or more and the peeling area ratio of the 10 mmφ bending test was 10% or less was good. Further, it was determined that the condition that the magnetic flux density B8 value of the grain-oriented electrical steel sheet was less than 1.920 T or the peeling area ratio of the 10 mmφ bending test was more than 10% was not possible.

Table 11 shows the production conditions and measurement results of the above examples of the present invention and comparative examples.

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.

With reference to the results in Table 11, the conditions of the present embodiment in which the stirring in the preparation of the annealing separator was produced at 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 at the time of manufacture thereof are satisfied. It was found that the directional electromagnetic steel sheet had a good judgment.

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 (9)

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 hot-rolling step of heating a slab containing Fe and impurities to a temperature of 1280 ° C. or higher and hot-rolling the slab 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 a slurry-like 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 is in mass% with respect to MgO contained in the annealing separator.
The Ti compound is contained in an amount of 0.3% or more and 10.0% or less in terms of Ti.
Rare earth metal compounds, 0.1% or more and 10% or less in terms of rare earth metals contained,
The compound of B contains 0.03% or more and 1.60% or less in terms of B contained, and one or more alkaline earth metal elements selected from the group consisting of Ca, Sr and Ba. Contains seeds or two or more alkaline earth metal compounds,
With respect to the content of MgO, the content of the alkaline earth metal compound in terms of alkaline earth metal was defined as A (mass%), and the content of the compound B in terms of B was defined as B (mass%). Sometimes, the following equation (1) is satisfied,
The annealing separator is a method for producing a grain-oriented electrical steel sheet, which is produced by stirring at a temperature of 0 ° C. or higher and 30 ° C. or lower for a time of 5 minutes or longer and 300 minutes or lower.
B ≦ A ≦ (0.8 + 3 × B) ・ ・ ・ Equation (1) 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 hot-rolling step of heating a slab containing Fe and impurities to a temperature of 1280 ° C. or higher and hot-rolling the slab 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 a slurry-like 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 is in mass% with respect to MgO contained in the annealing separator.
The Ti compound is contained in an amount of 0.3% or more and 10.0% or less in terms of Ti.
Rare earth metal compounds, 0.1% or more and 10% or less in terms of rare earth metals contained,
The compound of B is contained in an amount of 0.03% or more and 1.60% or less in terms of B,
Contains one or more alkaline earth metal compounds, including one or more alkaline earth metal elements selected from the group consisting of Ca, Sr and Ba, and sulfates.
The alkaline earth metal equivalent amount of the alkaline earth metal compound with respect to the MgO content is A (mass%), the B equivalent content of the compound B is B (mass%), and the sulfate root of the sulfate (sulfate). SO ₄ ) When ^{the content in 2-} converted form is C (mass%), both the following formulas (2) and (3) are satisfied.
The annealing separator is a method for producing a grain-oriented electrical steel sheet, which is produced by stirring at a temperature of 0 ° C. or higher and 30 ° C. or lower for a time of 5 minutes or longer and 300 minutes or lower.
0 ≤ A <B ... Equation (2)
(3 × B) ≦ C ≦ (10 × B) ・ ・ ・ Equation (3) The method for producing a grain-oriented electrical steel sheet according to claim 1 or 2, wherein the slab contains Bi: 0.0005% or more and 0.0500% or less in mass%. The slab is by mass%
Cu: 0.01% or more and 0.30% or less,
Sn: 0.01% or more and 0.30% or less,
Ni: 0.01% or more and 0.30% or less,
Cr: 0.01% or more and 0.30% or less, or
Sb: The method for producing a grain-oriented electrical steel sheet according to any one of claims 1 to 3, which contains one or more selected from the group consisting of 0.01% or more and 0.30% or less. By mass%, C: 0.005% or less,
Si: 2.5-4.5%,
Mn: Containing 0.01-0.15%,
Base steel sheet with the balance containing Fe and impurities,
A primary coating formed on the surface of the base steel sheet and _{containing Mg 2} SiO ₄ as a main component, and
_{An oxide containing MgAl 2} O ₄ as a main component in a range of 0.5 μm or more and 5 μm or less from the boundary of the primary coating on the base steel plate side in the thickness direction of the base steel plate connected to the primary coating. And, with directional electromagnetic steel sheet. The base steel sheet is Cu: 0.01% or more and 0.30% or less in mass%.
Sn: 0.01% or more and 0.30% or less,
Ni: 0.01% or more and 0.30% or less,
Cr: 0.01% or more and 0.30% or less, or
Sb: The grain-oriented electrical steel sheet according to claim 5, which contains one or more selected from the group consisting of 0.01% or more and 0.30% or less. The grain-oriented electrical steel sheet according to claim 5 or 6, wherein the magnetic flux density B8 value when a magnetic field of 800 A / m is applied at a frequency of 50 Hz is 1.920 T or more. By mass% with respect to MgO,
The Ti compound is contained in an amount of 0.3% or more and 10.0% or less in terms of Ti.
Rare earth metal compounds, 0.1% or more and 10% or less in terms of rare earth metals contained,
The compound of B is contained in 0.03% or more and 1.60% or less in terms of B, and
Contains one or more alkaline earth metal compounds, including one or more alkaline earth metal elements selected from the group consisting of Ca, Sr and Ba.
With respect to the content of MgO, the content of the alkaline earth metal compound in terms of alkaline earth metal was defined as B (mass%), and the content of the compound of B in terms of B was defined as B (mass%). Occasionally, a quenching separator that satisfies the following formula (1).
B ≦ A ≦ (0.8 + 3 × B) ・ ・ ・ Equation (1) By mass% with respect to MgO,
The Ti compound is contained in an amount of 0.3% or more and 10.0% or less in terms of Ti.
Rare earth metal compounds, 0.1% or more and 10% or less in terms of rare earth metals contained,
The compound of B is contained in an amount of 0.03% or more and 1.60% or less in terms of B,
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, and one or more alkaline earth metal compounds, and
Contains sulfate,
With respect to the content of MgO, the content of the alkaline earth metal compound in terms of alkaline earth metal is A (mass%), the content of the compound of B in terms of B is B (mass%), and sulfuric acid. Sulfate root of salt (SO ₄ ) When ^{the content in 2-} converted form is C (mass%), it is characterized by satisfying both the following formulas (2) and (3). Agent.
0 ≤ A <B ... Equation (2)
(3 × B) ≦ C ≦ (10 × B) ・ ・ ・ Equation (3)

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