The present invention relates to a grain-oriented electrical steel sheet having excellent magnetic properties and film adhesion, an annealing separator used for producing grain-oriented electrical steel sheets, and a method for producing grain-oriented electrical steel sheets.
Background technology
[0002]
The grain-oriented electrical steel sheet is a steel sheet in which Si is contained in an amount of about 0.5 to 7% by mass and the crystal orientation is integrated in the {110} <001> orientation (goss orientation). A catastrophic grain growth phenomenon called secondary recrystallization is used to control the crystal orientation.
[0003]
The manufacturing method of grain-oriented electrical steel sheet is as follows. The slab is heated and hot-rolled to produce a hot-rolled steel sheet. Anneal the hot-rolled steel sheet as needed. Pickle the hot-rolled steel sheet. A cold-rolled steel sheet is manufactured by cold-rolling the hot-rolled steel sheet after pickling at a rolling ratio of 80% or more. Decarburization annealing is performed on the cold-rolled steel sheet to develop primary recrystallization. Finish annealing is performed on the cold-rolled steel sheet after decarburization annealing to develop secondary recrystallization. Through the above steps, grain-oriented electrical steel sheets are manufactured.
[0004]
After the above-mentioned decarburization annealing and before finish annealing, an annealing separator containing MgO as a main component is attached to the surface of the cold-rolled steel sheet. Usually, the method is carried out by applying an aqueous slurry containing an annealing separator component to a cold-rolled steel sheet and drying it. After winding the cold-rolled steel sheet to which the annealing separator is attached on a coil, finish annealing is performed. During finish annealing, MgO in the annealing separator reacts with SiO 2 in the internal oxide layer formed on the surface of the cold-rolled steel sheet during decarburization annealing, and the primary component is forsterite (Mg 2SiO 4). A coating is formed on the surface of the steel sheet. After the primary coating is formed, an insulating coating liquid composed of, for example, colloidal silica and phosphate is applied onto the primary coating to form an insulating coating (also referred to as a secondary coating). The primary coating and the insulating coating have a smaller coefficient of thermal expansion than the base steel sheet. Therefore, the primary coating, together with the insulating coating, applies tension to the base steel sheet to reduce iron loss. The primary coating further enhances the adhesion of the insulating coating to the base steel sheet. It is preferable that the primary coating has high adhesion to the base steel sheet.
[0005]
On the other hand, it is also effective to increase the magnetic flux density to reduce the hysteresis loss in order to reduce the iron loss of the grain-oriented electrical steel sheet.
[0006]
In order to increase the magnetic flux density of the grain-oriented electrical steel sheet, it is effective to integrate the crystal orientation of the base steel sheet in the Goss orientation. Techniques for enhancing the accumulation in the Goss direction are proposed in Patent Documents 1 to 3. In these patent documents, the base steel sheet contains a magnetic property improving element (Sn, Sb, Bi, Te, Pb, Se, etc.) that enhances the action of an inhibitor (precipitate that suppresses normal crystal grain growth). As a result, the accumulation of the crystal orientation in the Goss orientation is increased, and the magnetic flux density of the grain-oriented electrical steel sheet can be increased.
[0007]
However, since the base steel sheet / primary coating interface is formed so that the interface energy is as low as possible, the above-mentioned base steel plate / primary coating interface becomes flat. In particular, when the base steel sheet contains an element for improving magnetic properties, it tends to be flatter. When the base steel plate / primary coating interface becomes flatter, the fitting structure of the primary coating that creates the physical bonding force between the primary coating and the base steel plate is lost, resulting in the base steel plate of the primary coating. Adhesion is reduced.
[0008]
Patent Documents 4 and 5 disclose techniques for improving the adhesion of the primary coating to a steel sheet.
[0009]
In Patent Document 4, the slab component contains 0.001 to 0.1% by mass of Ce, and a primary film containing 0.01 to 1000 mg / m 2 of Ce is formed on the surface of the steel sheet. In Patent Document 5, the directional electromagnetic steel plate contains Si: 1.8 to 7% by mass, has a primary coating containing forsterite as a main component on the surface, and Ce, La, Pr, Nd in the primary coating. , Sc, Y with a basis weight of 0.001 to 1000 mg / m 2 per side, and one or more of Sr, Ca, Ba with a basis weight of 0 per side. It is characterized by containing 0.01 to 100 mg / m 2.
[0010]
Patent Document 5 discloses a manufacturing method including a series of steps of applying an annealing separator to the surface of a base steel sheet subjected to decarburization annealing, drying it, and performing finish annealing. One of Ce, La, Pr, Nd, Sc, Y oxides, hydroxides, sulfates or carbonates with an average particle size of 0.1 to 25 μm in a quenching separator containing MgO as a main component. Alternatively, a method for producing a directional electromagnetic steel plate having excellent magnetic properties and film adhesion, which comprises containing two or more kinds in a total amount in the range of 0.01 to 14% by mass with respect to MgO in terms of metal. It has been disclosed.
Prior art literature
Patent documents
[0011]
Patent Document 1: Japanese Patent Application Laid-Open No. 6-88171
Patent Document 2: Japanese Patent Application Laid-Open No. 8-269552
Patent Document 3: Japanese Unexamined Patent Publication No. 2005-290446
Patent Document 4: Japanese Unexamined Patent Publication No. 2008-127634
Patent Document 5: Japanese Unexamined Patent Publication No. 2012-214902
Outline of the invention
Problems to be solved by the invention
[0012]
Regarding the adhesion of the coating film, various studies have been made on end face peeling in shearing and surface peeling in bending, but it can be said that the optimum steel sheet and manufacturing method are presented by strictly distinguishing these. No. Since the peeling behavior due to shearing and bending is different, it is necessary for the electrical steel sheet to be used for the iron core manufacturing method with a high degree of bending in recent years to have adhesion so that the coating does not peel off when it is subjected to stricter bending than before. It has become.
When the annealing separator contains Y, La, Ce, Sr, Ca, and Ba to form a primary film containing Y, La, Ce, Sr, Ca, and Ba, there is a problem with the adhesion of the primary film to shearing. There are problems such as insufficient primary film adhesion to bending and deterioration of magnetic characteristics even if there is no such problem, and the primary film adhesion to bending (hereinafter simply referred to as "coating adhesion") is poor. A material is desired.
[0013]
An object of the present invention is to use a grain-oriented electrical steel sheet having excellent magnetic properties and excellent adhesion of a primary film to a base steel sheet, an annealing separator used for manufacturing grain-oriented electrical steel sheets, and grain-oriented electrical steel sheets. It is to provide a manufacturing method.
Means to solve problems
[0014]
The present invention controls and defines the structure of the interface between the primary coating of grain-oriented electrical steel sheets and the base steel sheet, and specifies the structure of the primary coating. Special terms are defined and used herein to describe this interface structure. First, these terms will be described.
In the present invention, the primary coating is divided into two regions in the plate thickness direction based on the shape features schematically shown in FIG. 1, and the structure in each region is defined. In the following description, in order to express the two regions, the terms "surface oxide layer (1)" are used for the surface side and "fitted oxide layer (2)" is used for the base steel plate side. The surface oxide layer (1) is a plate thickness in which a primary coating portion (hereinafter, this may be referred to as “surface oxide”) that covers the surface of the base steel sheet relatively uniformly is present. The area of ​​direction. The fitted oxide layer (2) is a region in the plate thickness direction in which a primary coating portion (hereinafter, this may be referred to as “fitted oxide”) that bites into the base steel sheet exists. The reference value H0 of the depth for dividing the two will be described later.
The structure of the interface between the primary coating and the base steel sheet, especially the characteristics of the shape, may be generally expressed using the term "root".
[0015]
The interface between the primary coating of the grain-oriented electrical steel sheet and the base steel sheet has an uneven shape in which the embedded oxide has entered the inside of the base steel sheet. When the penetration depth of the embedded oxide becomes deep and the number density (pieces / μm 3) of the number of oxide particles increases, the adhesion of the primary coating to the base steel sheet increases due to the so-called anchor effect.
[0016]
On the other hand, if the inlaid oxide penetrates too much into the base steel sheet, it becomes a factor that hinders the grain growth of the steel sheet during secondary recrystallization and the domain wall movement during magnetization, and the magnetic properties deteriorate.
[0017]
In addition, the primary coating has the effect of applying tension to the steel sheet and reducing iron loss. In order to increase the tension, the surface oxide layer (1) preferably has a high content of Mg 2SiO 4 having a small coefficient of linear expansion, and the surface oxide layer (1) is preferably thick.
[0018]
Based on the above general recognition, the present inventors have the magnetic properties of grain-oriented electrical steel sheets containing the magnetic property improving element, and the annealing separator containing Y, La, Ce and Ca, Sr, Ba. The adhesion of the primary coating formed using the above was investigated and examined. In the following description, one or more elements selected from the group consisting of Y, La, and Ce are grouped together, and one or more elements selected from the group consisting of "Y group elements", Ca, Sr, and Ba are grouped together. May be described as "Ca group element".
As a result, the present inventors obtained the following findings.
[0019]
When a primary film is formed by containing a Y group element and a Ca group element in an annealing separator, the film adhesion to shearing may be sufficient, but the film adhesion to bending may not be sufficient. .. Further, a steel sheet having poor film adhesion to bending is often not good in iron loss and magnetic flux density.
Hereinafter, when it is not necessary to clearly distinguish between the film adhesion to shearing and the film adhesion to bending, simply describe as "adhesion" and include the film adhesion to shearing and the film adhesion to bending. Used as an intention.
The present inventors further investigated the effects of Y group elements and Ca group elements in the annealing separator, and as a result, obtained the following findings.
[0020]
When the annealing separator contains Y group elements, the embedded oxide layer (2) becomes thick. This improves the film adhesion to shearing.
Further, when Ca group elements are contained in the annealing separator, if these elements are appropriately dispersed in the annealing separator, the number density of the embedded oxide layer (2) of the formed primary film increases. , Improves film adhesion to shearing. Further, when the size of the particles containing the Ca group element in the Ca group element enrichment region specified below in the primary film is an appropriate size with respect to the MgO particle size, the film adhesion to the bending process is high. Therefore, deterioration of magnetic characteristics can be suppressed. At this time, the thickness of the surface oxide layer (1) becomes uniform, and the amount of Mg 2SiO 4 phase increases. The improvement of the film adhesion to the bending process is that the thickness of the surface oxide layer (1) becomes uniform, and the local stress concentration in the region where the surface oxide layer (1) is thin during the bending process. Is considered to be the cause. Further, it is considered that the improvement of the magnetic characteristics is caused by an increase in the tension acting on the steel sheet due to the increase in the amount of Mg 2SiO 4-phase in the surface oxide layer (1).
Furthermore, it was clarified that the primary coating having such good characteristics is characterized not only by the shape of the interface unevenness but also by the presence form of Al in the vicinity of the interface of the primary coating. In addition, the characteristics of the annealing separator used to form such a primary film have been clarified.
The interface between the base steel plate and the primary coating has a complicated three-dimensional shape with irregularities as shown in FIG. The characteristics of the existence form of Al that have been clarified should be quantified as a "three-dimensional structure" in essence, but it is difficult to quantify because of the three-dimensional and complicated structure. Therefore, the present inventors have attempted to project information on the interface structure onto a plane parallel to the surface of the steel sheet as described later, and to define the characteristics of the interface in the "plane". Then, it was confirmed that the effect of the present invention can be evaluated and explained by the quantitative definition by this "feature on the projective plane".
[0021]
The features of the present invention obtained from these findings are as follows.
That is, if the primary coating mainly composed of Mg 2SiO 4 and the interface between the primary coating and the base steel sheet satisfy the characteristics shown in the following (1) to (4), the embedded oxide layer (2) and the surface oxide layer are satisfied. (1) becomes appropriate, and it becomes possible to achieve both adhesion of the primary coating to shearing and bending and iron loss characteristics.
(1) Number density of the number of Al-enriched regions D3: 0.020 to 0.180 / μm 2,
(2) (Area S5 of the region that is the embedded oxide layer region and the Al-enriched region) / (Area S3 of the Al-enriched region) ≧ 0.33 (33%),
(3) Distance obtained by subtracting H0 from the average value of the heights in the plate thickness direction of the region that is the embedded oxide layer region and the Al-concentrated region. Separation H5: 0.4 to 4.0 μm,
(4) (Total area of ​​inlaid oxide layer region S1) / (Observation area S0) ≧ 0.15 (15%).
Further, it is a primary film containing Y group elements and Ca group elements, and it is a preferable form to satisfy the following conditions (5) to (7).
(5) Total content of Y group elements: 0.1 to 6.0% by mass,
(6) Total content of Ca group elements: 0.1 to 6.0% by mass,
(7) Number density of Ca group element enrichment region D4: 0.008 / μm 2 or more.
[0022]
Then, the annealing separator containing MgO as a main component and Y group elements and Ca group elements capable of forming the above primary film can be specified under the following conditions (8) to (13).
(8) (0.253 [Y] +0.180 [La] +0.170 [Ce]) /0.454 [Mg] x 100 (%): 0.40 to 3.60%,
(9) (0.353 [Ca] +0.252 [Sr] +0.195 [Ba]) /0.454 [Mg] x 100 (%): 0.20 to 2.20%,
(10) Average particle size of MgO R1: 0.08 to 1.50 μm,
(11) Average particle size of particles containing Ca group elements in the annealing separator R2: 0.08 to 1.50 μm,
(12) (Average particle size R2) / (Average particle size R1) = 0.3 to 3.0,
[0023]
Further, the above conditions (8) to (12) are realized in the region of at least 3.0 μm from the surface of the base steel sheet in the layer of the annealing separator formed on the surface of the steel sheet immediately before finish annealing. Is preferable.
In addition, since the particles of the raw material powder containing Ca group elements tend to aggregate until they are applied and dried on the surface of the steel sheet, in the raw material powder,
(13) It is necessary to satisfy the number density of particles containing Ca group elements ≥ 25 billion / cm3.
[0024]
The gist of the present invention obtained from these findings is as follows.
The grain-oriented electrical steel sheet according to the present invention comprises a group consisting of C: 0.0050% or less, Si: 2.5 to 4.5%, Mn: 0.02 to 0.2%, S and Se in mass%. One or more elements to be selected: 0.005% or less in total, sol. Al: 0.010% or less and N: 0.010% or less are contained, and the balance is formed on a base steel sheet having a chemical composition composed of Fe and impurities and Mg on the surface of the base steel sheet. It is provided with a primary coating containing 2SiO 4 as a main component, and the primary on the base steel plate side when the direction from the primary coating side to the base steel plate side is positive in the plate thickness direction of the steel plate. In the characteristic X-ray intensity and height correlation distribution diagram developed by projecting the height of the coating surface and the component information in the primary coating onto a surface parallel to the steel sheet surface, the surface height of the primary coating on the base steel plate side. With the median value set to H0, the primary coating existing on the base steel sheet side from H0 + 0.2 μm is the “fitted oxide layer region”, and the primary coating existing on the primary coating side from H0 + 0.2 μm is the “surface oxide”. The region is classified as "layer region", the maximum value of the characteristic X-ray intensity of Al is specified, and the region where the characteristic X-ray intensity of Al of 20% or more of the maximum value of the characteristic X-ray intensity of Al is obtained is "Al". When it is called "concentrated area"
The primary coating is
(1) Number density of the Al-enriched region D3: 0.020 to 0.180 / μm 2,
(2) (total area S5 of the inlaid oxide layer region and the Al-enriched region) / (total area S3 of the Al-enriched region) ≧ 33%,
(3) Distance H5: 0.4 to 4.0 μm, obtained by subtracting H0 from the average height in the plate thickness direction of the region that is the embedded oxide layer region and the Al-concentrated region.
(4) (total area S1 of the embedded oxide layer region) / (observation area S0) ≧ 15%
It is characterized by satisfying the above conditions.
[0025]
Further, in the directional electromagnetic steel plate, one or more elements whose primary coating is selected from the group consisting of Y, La, and Ce, and one or more elements selected from the group consisting of Ca, Sr, and Ba. In the characteristic X-ray intensity distribution map, the maximum value of the characteristic X-ray intensity of each of Ca, Sr, and Ba is specified, and 20% or more of the maximum value of the characteristic X-ray intensity of Ca is used. A region where the characteristic X-ray intensity is obtained, a region where the characteristic X-ray intensity of Sr is 20% or more of the maximum value of the characteristic X-ray intensity of Sr, and 20% of the maximum value of the characteristic X-ray intensity of Ba. When the above-mentioned region where the characteristic X-ray intensity of Ba is obtained is combined to form the "Ca group element enrichment region",
The primary coating is
(5) Ratio of the total content of one or more elements selected from the group consisting of Y, La, and Ce to the content of Mg 2SiO 4 in the primary coating: 0.1 to 6.0% by mass. ,
(6) Ratio of the total content of one or more elements selected from the group consisting of Ca, Sr, and Ba to the content of Mg 2SiO 4 in the primary coating: 0.1 to 6.0 mass. %,
(7) Number density of the Ca group element enrichment region D4: 0.008 / μm 2 or more
It is preferable that the condition of the above is satisfied.
[0026]
The annealing separator used in the production of the directional electromagnetic steel sheet according to the present invention is an annealing separator containing MgO as a main component, and is one or more elements selected from the group consisting of Y, La, and Ce, and The ratio (% by mass) of the content of Mg, Y, La, Ce, Ca, Sr, Ba to the content of MgO containing one or more elements selected from the group consisting of Ca, Sr, and Ba. Are expressed as [Mg], [Y], [La], [Ce], [Ca], [Sr], and [Ba], respectively.
(8) (0.253 [Y] +0.180 [La] +0.170 [Ce]) /0.454 [Mg]: 0.40 to 3.60,
(9) (0.353 [Ca] +0.252 [Sr] +0.195 [Ba]) /0.454 [Mg]: 0.20 to 2.20,
The filling,
(10) Average particle size of MgO R1: 0.08 to 1.50 μm,
(11) Average particle size R2 of particles containing one or more elements selected from the group consisting of Ca, Sr, and Ba: 0.08 to 1.50 μm,
(12) (The average particle size R2) / (The average particle size R1): 0.3 to 3.0,
(13) Number density of particles containing Ca group elements ≥ 25 billion / cm 3
It is characterized by satisfying the above conditions.
[0027]
Further, it is preferable that the annealing separator is characterized in that particles containing one or more elements selected from the group consisting of Y, La, and Ce further contain oxygen.
[0028]
The method for manufacturing grain-oriented electrical steel sheets according to the present invention is from C: 0.1% or less, Si: 2.5 to 4.5%, Mn: 0.02 to 0.2%, S and Se in mass%. One or more elements selected from the group: 0.005-0.07% in total, sol. A step of hot-rolling a slab containing Al: 0.005 to 0.05% and N: 0.001 to 0.030% and the balance of Fe and impurities to produce a hot-rolled steel sheet. A step of cold-rolling a hot-rolled steel sheet at a cold-rolling rate of 80% or more to manufacture a cold-rolled steel sheet, and a decarburizing annealing of the cold-rolled steel sheet to obtain a decarburized annealed sheet. A step of manufacturing, a step of applying an aqueous slurry to the surface of the decarburized annealed sheet and drying, and a step of performing finish annealing on the steel sheet after the aqueous slurry has been dried are provided, and after the drying. The substance that coats the surface of the steel sheet is the above-mentioned annealing separator.
[0029]
The method for manufacturing a grain-forming electrical steel sheet for manufacturing a grain-oriented electrical steel sheet according to the present invention is, in terms of mass%, C: 0.1% or less, Si: 2.5 to 4.5%, Mn: 0.02 to 0.2%, one or more elements selected from the group consisting of S and Se: 0.005-0.07% in total, sol. A process of hot-rolling a slab containing Al: 0.005 to 0.05% and N: 0.001 to 0.030% and the balance of Fe and impurities to produce a hot-rolled steel sheet. A step of cold-rolling a hot-rolled steel sheet at a cold-rolling rate of 80% or more to manufacture a cold-rolled steel sheet, and a decarburizing annealing of the cold-rolled steel sheet to obtain a decarburized annealed sheet. It comprises a step of manufacturing and a step of applying an aqueous slurry to the surface of the decarburized annealed sheet and drying it, and the substance covering the surface of the dried steel sheet is the above-mentioned annealing separator. ..
The invention's effect
[0030]
The grain-oriented electrical steel sheet according to the present invention has excellent magnetic properties and excellent adhesion to the base steel sheet of the primary coating. Further, the annealing separator according to the present invention is used in the manufacturing process of the grain-oriented electrical steel sheet of the present invention. Then, the grain-oriented electrical steel sheet of the present invention can be manufactured by the manufacturing method of the present invention using the annealing separator of the present invention.
A brief description of the drawing
[0031]
FIG. 1 is a schematic diagram of a 20 μm × 15 μm primary coating sample.
[Fig. 2] Fig. 2 is a diagram illustrating a Gaussian filter applied to height information data of a primary coating obtained by a laser microscope.
[Fig. 3] Fig. 3 is a schematic view showing the three-dimensional structure of the back surface of the peeled primary coating and the fitting portion.
FIG. 4 is a diagram illustrating a characteristic X-ray intensity and height correlation distribution diagram.
Embodiment for carrying out the invention
[0032]
Details will be described later, but in the present invention, in order to specify the structure of the interface between the primary coating of the directional electromagnetic steel sheet and the base steel sheet, the surface of the side of the primary coating that has been peeled off from the directional electromagnetic steel sheet and is in close contact with the base steel sheet. That is, observe the surface of the primary coating on the side that formed the interface between the primary coating and the base steel sheet. This observation surface is analyzed with a scanning confocal laser scanning microscope to obtain the unevenness distribution of the interface (information in the depth direction of the interface). Further, the observation surface is analyzed using SEM-EDS, and the concentration distribution of various elements present in the primary film is obtained from the characteristic X-ray intensity. Since the observation with each of these devices is performed in the direction perpendicular to the surface of the steel sheet from which the peeling source is obtained, the information obtained is the information (position, characteristic X-ray intensity) of the primary coating having a three-dimensional structure on the surface of the steel sheet. It is projected onto a parallel plane.
First, it should be noted that the following description of the interface in the present specification is based on the "features on the projective plane". For example, the "area" relating to the structure of the interface is the area obtained on the projection plane, and the region where the element exists is specified based on the characteristic X-ray intensity of the element obtained on the projection plane.
However, it has been confirmed that the information on the primary coating obtained on these projection planes can explain the features of the present invention without any inconvenience, and the present invention is described by the information on the primary coating on these projection planes. Needless to say, this does not defeat the significance of the present invention, which is considered to be an essential feature of the three-dimensional structure of the primary coating.
Further, in the present specification, unless otherwise specified, the notation "A to B" for the numerical values ​​A and B means "A or more and B or less". When a unit is attached only to the numerical value B in such a notation, the unit shall be applied to the numerical value A as well. Further, in the present specification, the "main component" means a component contained in a substance in an amount of 50% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more.
[0033]
Hereinafter, the grain-oriented electrical steel sheet according to the present invention, the annealing separator, and the manufacturing method of the present invention will be described in detail. In the present specification,% with respect to the content of an element means mass% unless otherwise specified.
[0034]
The grain-oriented electrical steel sheet according to the present invention includes a base steel sheet and a primary coating formed on the surface of the base steel sheet.
[0035]
[Base steel plate]
The chemical composition of the base steel sheet constituting the grain-oriented electrical steel sheet of the present invention contains the following elements. However, the feature of the present invention lies in the primary coating, and the base steel sheet does not need to be special.
[0036]
C: 0.0050% or less
Carbon (C) is an element effective for microstructure control until the decarburization annealing process is completed during the manufacturing process, but if the C content exceeds 0.0050%, the magnetic properties of the grain-oriented electrical steel sheet, which is the product plate, Decreases. Therefore, the C content is 0.0050% or less. The C content is preferably as low as possible. However, even if the C content is reduced to less than 0.0001%, the above effect does not change so much, only the manufacturing cost is incurred. Therefore, the preferred lower limit of the C content is 0.0001%.
[0037]
Si: 2.5-4.5%
Silicon (Si) increases the electrical resistance of steel and reduces eddy current loss. If the Si content is less than 2.5%, the above Not enough effect. On the other hand, if the Si content exceeds 4.5%, the cold workability of the steel deteriorates. Therefore, the Si content is 2.5-4.5%. The lower limit of the Si content is preferably 2.6%, more preferably 2.8%. The preferred upper limit of the Si content is 4.0%, more preferably 3.8%.
[0038]
Mn: 0.02-0.2%
Manganese (Mn) combines with S and Se to form MnS and MnSe during the manufacturing process. These precipitates function as inhibitors (inhibitors of normal grain growth) and cause secondary recrystallization in steel. Mn further enhances the hot workability of steel. If the Mn content is less than 0.02%, the above effect cannot be sufficiently obtained. On the other hand, if the Mn content exceeds 0.2%, secondary recrystallization does not occur and the magnetic properties of the steel deteriorate. Therefore, the Mn content is 0.02 to 0.2%. The preferred lower limit of the Mn content is 0.03%, more preferably 0.04%. The preferred upper limit of the Mn content is 0.13%, more preferably 0.10%.
[0039]
One or more elements selected from the group consisting of S and Se: 0.005% or less in total
Sulfur (S) and selenium (Se) combine with Mn to form MnS and MnSe that function as inhibitors during the manufacturing process. However, if the total content of these elements exceeds 0.005%, the remaining inhibitors will reduce the magnetic properties. Further, segregation of S and Se may cause surface defects in the grain-oriented electrical steel sheet. Therefore, in the grain-oriented electrical steel sheet, the total content of one or more elements selected from the group consisting of S and Se is 0.005% or less. It is preferable that the total S and Se contents in the grain-oriented electrical steel sheet are as low as possible. However, even if the total of the S content and the Se content in the grain-oriented electrical steel sheet is reduced to less than 0.0005%, only the manufacturing cost increases and the above effect does not change so much. Therefore, the preferable lower limit of the total content of one or more elements selected from the group consisting of S and Se in the grain-oriented electrical steel sheet is 0.0005%.
[0040]
Sol. Al: 0.010% or less
Aluminum (Al) combines with N to form AlN during the manufacturing process of grain-oriented electrical steel sheets, and functions as an inhibitor. However, sol. If the Al content exceeds 0.010%, the inhibitor remains excessively in the base steel sheet, so that the magnetic properties deteriorate. Therefore, sol. The Al content is 0.010% or less. sol. The preferred upper limit of the Al content is 0.004%, more preferably 0.003%. sol. It is preferable that the Al content is as low as possible. However, sol. Reducing the Al content to less than 0.0001% only increases the manufacturing cost and does not significantly change the above effect. Therefore, sol. In the grain-oriented electrical steel sheet. The preferable lower limit of the Al content is 0.0001%. In addition, in this specification, sol. Al means acid-soluble Al. Therefore, sol. The Al content is the content of acid-soluble Al.
It should be noted that Al, which is a feature of the primary coating of the present invention, is derived from the base steel sheet, as will be described later. For this reason, at first glance, the fact that the Al content of the base steel sheet is zero seems to contradict the presence of Al in the primary coating, but the concentration in the primary coating is "the base material in the process of being manufactured." It is "Al contained in the steel sheet", and in the directional electromagnetic steel sheet of the present invention, after the concentration of Al, which is a feature of the present invention, occurs, it is subjected to high temperature heat treatment, which is also called "purification annealing" in one process of finish annealing. Al of the base steel sheet is discharged to the outside of the system. Therefore, there is no contradiction between the fact that Al is not contained in the final base steel sheet and the presence of Al derived from the base steel sheet in the final primary coating.
[0041]
N: 0.010% or less
Nitrogen (N) combines with Al to form AlN during the manufacturing process of grain-oriented electrical steel sheets, and functions as an inhibitor. However, if the N content in the grain-oriented electrical steel sheet exceeds 0.01%, the inhibitor remains excessively in the grain-oriented electrical steel sheet, so that the magnetic properties deteriorate. Therefore, the N content is 0.01% or less. The preferred upper limit of the N content is 0.004%, more preferably 0.003%. The N content is preferably as low as possible. However, even if the total N content in the grain-oriented electrical steel sheet is reduced to less than 0.0001%, the manufacturing cost is only increased and the above effect does not change so much. Therefore, the preferable lower limit of the N content in the grain-oriented electrical steel sheet is 0.0001%.
[0042]
The balance of the chemical composition of the base steel sheet of the grain-oriented electrical steel sheet according to the present invention consists of Fe and impurities. Here, 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 remaining elements and the like that are permissible as long as they do not adversely affect the grain-oriented electrical steel sheet of the present invention.
[0043]

Copper (Cu), tin (Sn), antimony (Sb), bismuth (Bi), tellurium (Te) and lead (Pb) are base steel sheets by high-temperature heat treatment, which is also called "purification annealing" in one process of finish annealing. A part of Cu, Sn, Sb, Bi, Te and Pb in the system is discharged to the outside of the system. These elements exert the effect of increasing the orientation selectivity of the secondary recrystallization and improving the magnetic flux density in the finish annealing, but if they remain in the base steel sheet after the finish annealing is completed, they deteriorate the iron loss as mere impurities. Therefore, the total content of one or more elements selected from the group consisting of Cu, Sn, Sb, Bi, Te and Pb is preferably 0.30% or less. As described above, since these elements are impurities, it is preferable that the total content of these elements is as low as possible.
[0044]
[Primary coating]
The characteristics of the primary coating are the most important in the present invention. As mentioned above, this feature also has limitations in its measurement method. In the present invention, information on the interface between the primary coating and the base steel sheet is projected onto a plane parallel to the surface of the steel sheet, and is defined on that plane (hereinafter, may be simply referred to as “projective plane”). Understanding this measurement method is important for understanding the characteristics of the primary coating, so the measurement method will be described first.
[0045]

A directional electromagnetic steel sheet having a primary film formed on the surface is electrolyzed at a constant potential in an electrolytic solution so that only the base steel sheet is dissolved, and then the primary film is separated from the base steel sheet and used as an observation sample. In the electrolysis for sampling, since the base steel plate at the interface is selectively electrolyzed, it is not necessary to electrolyze all the base steel plates, and an appropriate electrolysis amount may be set. The amount of electrolysis is, for example, 80 C / cm 2. For the separation of the primary coating, a method of attaching the primary coating to the adhesive surface of a commercially available metal tape or the like, removing the base steel plate, and observing what remains on the tape side, or embedding with paraffin. There is a method of removing paraffin after letting it.
Hereinafter, this separated primary coating may be referred to as an "interface observation sample", and the surface on the side in close contact with the base steel plate of the primary coating to be observed may be referred to as an "observation surface".
[0046]
Next, observe the interface observation sample with various observation devices from the direction perpendicular to the surface of the steel sheet from which it was peeled off (the thickness direction of the grain-oriented electrical steel sheet). Therefore, the data obtained from each device is the information possessed by the interface observation sample expanded on the projection plane. The following description will be given on the premise of the data in this projective plane. That is, for example, the description "at the interface" describes the situation of the data in the projection plane. Here, in the plate thickness direction, the direction from the primary coating side to the base steel plate side is positive. The term "height" used below indicates that the direction from the primary coating side to the base steel plate side is high.
[0047]
The characteristic X-ray intensity analysis of Ca, Sr, Ba and Al is performed on the observation surface of the interface observation sample using SEM-EDS (model number: JSM-7900F, manufactured by JEOL Ltd.). At this time, the scanning step is set to 0.1 μm, a characteristic X-ray intensity distribution map of 200 × 150 pixels on the projection plane is obtained, and each observation area of ​​any 200 × 150 pixels is selected.
Further, a region that completely includes the observation region and is not in contact with each observation region subjected to the characteristic X-ray intensity analysis is a scanning confocal laser microscope (model number: VK9710, manufactured by KEYENCE CORPORATION). ), And obtain the unevenness data of the observation surface on the projection plane. At this time, the scanning step is set to 0.1 μm. The obtained data array of 200 × 150 pixels is smoothed once by a Gaussian filter (FIG. 2) having a size of 3 × 3. Further, the smoothed data array is automatically corrected for a quadric surface based on the center line in the width direction and the center line in the height direction, and the corrected data array is obtained. Here, when the scanning step for unevenness measurement is D μm, which is not 0.1 μm, the unevenness data array is reduced to a size of 0.1 / D times by bilinear complementation, and the interval between data points is pseudo. An uneven distribution of 1 μm is obtained.
FIG. 3 is a schematic view showing the three-dimensional structure of the back surface of the peeled primary coating and the fitting portion. H0 is the median surface height of the primary coating. H1 is an average value of the heights of the fitting portions existing at positions higher than H0. This position (H1-H0) is 0.40 to 2.00 μm in the present invention. FIG. 3 is projected onto a plane parallel to the surface of the steel plate, and the one is a projection plane having height unevenness distribution information. Then, from the unevenness distribution, a data array of 200 × 150 points at positions corresponding to each region of 200 × 150 pixels selected from the characteristic X-ray intensity distribution map is specified. That is, all the pixels have one unevenness data (height) for each region of 200 × 150 pixels of the digital image of the characteristic X-ray intensity distribution map.
Hereinafter, this is referred to as a characteristic X-ray intensity and height correlation distribution map, and a schematic diagram showing this is shown in FIG.
The method of identifying the morphology of the coating with the information obtained from this figure will be described.
[0048]
From the characteristic X-ray intensity and height correlation distribution map obtained in this way, the regions A0 to A5 described below are determined in the observation region by the following procedure.
In the schematic diagram of the characteristic X-ray intensity and the unevenness correlation distribution diagram shown in FIG. 4, all the observation regions in the outermost frame are indicated by A0. The region filled with dark gray is a region higher than the median value H0 of the unevenness. The inside of the frame shown by the light gray line is the region (fitted oxide region) A1 which is 0.2 μm higher than H0. The outside of the frame shown by the light gray line is the surface oxide layer region A2. Al (aluminum) enriched regions are represented by A3 (indicated by dots) and A5 (indicated by black). In particular, A5 indicates an Al (aluminum) enriched region existing in the inlaid oxide region (A1). The region of A4 (inside the frame of the dotted line) indicates the Ca group element enrichment region described below.
[0049]
The region A0 is the entire observation region, that is, a region of 20 μm × 15 μm, and all the pixels of the characteristic X-ray intensity and height correlation distribution diagram correspond to this region A0. Hereinafter, A0 may be described as an “observation area”.
[0050]
Region A1 and region A2 are classified based on the characteristic X-ray intensity and the height distribution of the height correlation distribution diagram.
In the present invention, the primary coating can be classified into two regions in the plate thickness direction, "fitted oxide layer (2)" and "surface oxide layer (1)", based on the position H0 in the steel plate thickness direction. , As described above (Fig. 1). The area A1 and the area A2 are areas in which this classification is developed on the projection plane.
H0 is the median value of the surface height of the primary coating of the height data of the characteristic X-ray intensity and the height correlation distribution map. Here, it is an arithmetic mean value of two height values ​​near the center of 200 × 150 pieces. The region having a height of H0 + 0.2 μm or more in the plate thickness direction is the “fitted oxide layer (2)”, and what is seen on the projection plane is the “fitted oxide layer region” A1. Similarly, the height is less than H0 + 0.2 μm in the plate thickness direction. The region is the “surface oxide layer (1)”, and the “surface oxide layer region” A2 on the projection plane.
[0051]
Region A3 and region A4 are classified based on the characteristic X-ray intensity and the height distribution of the height correlation distribution diagram.
In the distribution of the characteristic X-ray intensity of Al (aluminum) in the characteristic X-ray intensity and height correlation distribution diagram, the maximum value of the characteristic X-ray intensity of Al is specified, and 20% of the maximum value of the characteristic X-ray intensity of Al. The region where the above characteristic X-ray intensity of Al can be obtained is A3. Hereinafter, the region A3 will be referred to as an “Al enriched region”.
Further, in the characteristic X-ray intensity and height correlation distribution diagram, the characteristic X-ray intensity of each of Ca, Sr, and Ba is specified, and the characteristic X-ray intensity of Ca is 20% or more of the maximum value of the characteristic X-ray intensity of Ca. The obtained region, the region where the characteristic X-ray intensity of Sr of 20% or more of the maximum value of the characteristic X-ray intensity of Sr can be obtained, and the characteristic X-ray of Ba of 20% or more of the maximum value of the characteristic X-ray intensity of Ba. A4 is a region including a region where strength can be obtained. That is, the region A4 is a region in which the characteristic X-ray intensity of any of the elements Ca, Sr, and Ba is 20% or more of the maximum characteristic X-ray intensity of the element. Hereinafter, the region A4 will be referred to as a “Ca group element enrichment region”.
[0052]
Further, the region existing in the inlaid oxide layer region A1 and being the Al (aluminum) enriched region A3 is specified as A5. Hereinafter, the region A5 will be referred to as a “fitted Al (aluminum) region”.
[0053]
Next, in the above region, the number density (pieces / μm 2) of the number of each region, the total area of ​​each region (μm 2), and the position (height (μm)) in the plate thickness direction of each region are specified. Areas are required for areas A0, A1, A3, and A5, and the total area of ​​each is S0, S1, S3, and S5.
It is A3 and A4 that the number density of the number of regions is required. Let the number densities of the number of regions A3 and A4 be D3 and D4, respectively. In specifying the number density of the number of regions, when the pixels in 200 × 150 pixels are continuous vertically or horizontally, these are regarded as one region. Further, the region consisting of three or less pixels is regarded as noise and excluded, and the number of regions is specified. As for the area of ​​one pixel, since the scanning step at the time of measurement is 0.1 μm (more specifically 0.092 μm) as described above, the area of ​​the region = 0.1 μm × 0.1 μm (more specifically). 0.092 μm × 0.092 μm) × number of regions.
Needless to say, for example, in D3, for the area A3, the total number of areas measured by regarding the area where pixels are continuous in pixel units as one area is the area of ​​the observation area A0 (that is, S0 which is the total observation area). ) Divided by. D4 is also calculated by the same method.
It is the area A5 that requires the position of the area in the plate thickness direction. Let the position of the region A5 be H5. This position is specified with reference to H0, which is the boundary between the surface oxide layer (1) and the inlaid oxide layer (2). Specifically, it is a value obtained by subtracting H0 from the average value of the heights of all the pixels in the region A5. Since the region A5 is a region where the height in the characteristic X-ray intensity and the height correlation distribution map exists at a position of H0 + 0.2 μm or more, the average value of the heights of the pixels of the region A5 is always H0 + 0.2 μm or more. As a result, H5 has a value of 0.2 μm or more.
[0054]

The following describes the characteristic primary coating of the present invention. The primary coating of the present invention contains Mg 2SiO 4 as a main component, but the Al distribution near the interface between the primary coating and the base steel sheet is characterized by a large feature, which will be described first.
The present invention is characterized in that D3: 0.020 to 0.180 / μm 2 for the above D3, which is the number density of the Al-enriched region A3 in the vicinity of the interface. If D3 is out of this range, the effect of improving the film adhesion to the bending process cannot be obtained.
Further, the ratio of the area of ​​the fitted Al region A5 existing in the fitted oxide layer region A1 to the Al concentrated region A3, that is, S5 / S3 is characterized in that S5 / S3 ≧ 0.33 (33%). do. If this ratio is less than 0.33, the effect of improving the film adhesion to the bending process cannot be obtained.
Further, the position H5 in the plate thickness direction of the fitting Al region A5 is H5: 0.4 to 4.0 μm. If this value is less than 0.4 μm, the effect of improving the film adhesion to bending cannot be obtained. Further, the state where the value of H5 exceeds 4.0 μm means that the embedded oxide layer (2) itself is excessively thick, and the oxide hinders the domain wall movement during magnetization, so that the magnetic characteristics are affected. Negative effects will be seen.
[0055]
The reason why the above Al distribution affects the bending workability is not clear, but it is considered as follows.
Since Al is an element with a strong tendency to form oxides, Al is selectively oxidized on the surface of the steel sheet during finish annealing, and Al diffuses from the inside of the base steel sheet toward the surface. At this time, when a part of Mg 2SiO 4 is reduced in the surface oxide to form MgAl 2O 4, the final film tension is lowered and the magnetic characteristics are deteriorated, and the surface oxide mainly composed of Mg 2SiO 4 is deteriorated. The thickness of the layer (1) becomes non-uniform. To avoid this, the solution may be to oxidize Al inside the steel sheet to prevent it from reaching the surface oxide layer (1). That is, Al may be oxidized and fixed in the tip region of the inlaid oxide that has penetrated deeply into the base steel sheet.
The present invention has a structure in which Al is concentrated in the tip region of the embedded oxide layer (2). In the present invention, the state of Al in the Al-concentrated region A3 is not specified at all, but considering that the main component of the primary coating is Mg 2SiO 4, Al in the above A3 exists as an oxide. It is considered that it is appropriate to think that the above situation is exhibited, and that the improvement of the magnetic characteristics and the improvement of the film adhesion to the bending process can be achieved at the same time.
If the specified value representing this situation is H5, H5 is 0.4 μm or more, that is, the fitted Al region A5 is 0.4 μm or more away from H0 on the inner side of the steel sheet (tip side of the fitted oxide), the above state is satisfied. It is believed that it has been achieved.
And the fact that such an fitted Al region is at the tip of the fitted oxide layer (2) also leads to the fact that D3 has a numerical value within an appropriate range. That is, if the number density of the fitted Al region A5 is low and Al reaches the entire interface, D3 is low. Further, even if a situation occurs in which the density of the fitted Al region A5 temporarily becomes excessively high, the distance between the adjacent fitted Al regions A5 becomes short, so that they are united as the primary coating grows. In the end, D3 is unlikely to be excessively high. Therefore, the appropriate range of D3 is 0.020 to 0.180 pieces / μm 2.
Further, if the appropriate fitted Al region A5 as described above is formed, Al diffused from the inside of the steel sheet does not reach the surface oxide layer, so that S5 / S3 inevitably has a high value, and in the present invention. It is considered that the specified 0.33 is the lower limit.
[0056]

In the primary coating of the present invention, it cannot be said that the embedded oxide has a remarkable external feature, but the above-mentioned characteristic Al distribution utilizes the phenomenon in the tip region of the embedded oxide layer (2). Therefore, it is difficult to form a characteristic Al distribution if the inlaid oxide itself does not exist.
Therefore, the area ratio of the inlaid oxide layer region on the projection plane is specified as the existence of the inlaid oxide. It should be noted that the numerical range itself of this regulation is such that it can be observed even in a grain-oriented electrical steel sheet having excellent film adhesion in general shearing, but it is important as a necessary condition for obtaining a characteristic Al distribution. It can be said that.
In the present invention, it is necessary that (area S1 of the embedded oxide layer region) / (observation area S0) ≧ 0.15 (15%). If this value is less than 0.15, the number density of the number of insert oxides is very low, or the number density is to some extent, even if each insert oxide is formed in a reasonable area. Even if it is the value of, the area of ​​each inlaid oxide is small. In both cases, the distance between the embedded oxides is relatively wide. In such a situation, Al diffused from the inside of the steel sheet reaches the surface oxide layer region, which makes it difficult to form the above-mentioned characteristic Al distribution.
[0057]

The primary coating of the present invention contains Mg 2SiO 4 as a main component. More specifically, the primary coating contains 50-95 mass% Mg 2SiO 4. The rest are mainly generally known oxides such as MgAl 2O4 and sulfides of Mn and alkaline earth metals.
[0058]
Further, the primary coating of the present invention contains a total of 0.1 to 6.0% by mass of Y group elements and a total of 0.1 Ca group elements with respect to the content of Mg 2SiO 4 in the primary coating. It is preferably contained in an amount of about 6.0% by mass.
Details will be described later, but in order to realize the above-mentioned Al distribution, it is preferable to use an annealing separator containing Y group elements. In this case, the Y group elements will remain in the primary film after finish annealing. If the total content of the Y group elements in the primary coating is less than 0.1% by mass, the coating adhesion to bending is not improved. If it exceeds 6.0% by mass, the thickness of the embedded oxide layer (2) becomes too thick, so that the adverse effect on the magnetic properties becomes remarkable.
[0059]
Similarly, in order to realize the above-mentioned Al distribution, it is preferable to use an annealing separator containing Ca group elements. In this case, Ca group elements will remain in the primary film after finish annealing.
If the total content of Ca group elements in the primary coating is less than 0.1% by mass, the coating adhesion in bending cannot be improved. If it exceeds 6.0% by mass, the number density of the oxide particles in the inlaid oxide layer (2) becomes too high, and the adjacent inlaid oxides are united and integrated, resulting in the number of inlaid oxide particles. Not only the density is lowered, but also the characteristic Al distribution cannot be obtained, and the film adhesion in the bending process cannot be improved.
[0060]
The Mg 2SiO 4 content in the primary coating is quantitatively analyzed by inductively coupled plasma mass spectrometry (ICP-MS) using the primary coating separated from the electromagnetic steel plate by the above method as a sample. The product of the obtained quantitative value (% by mass) and the molecular weight of Mg 2SiO 4 divided by twice the atomic weight of Mg is defined as the content of Mg 2SiO 4.
Further, similarly, each of Ca, Ba, Sr and La, Y, Ce is quantitatively analyzed by the same method as above, and the same calculation as above is performed for the obtained content value (mass%). The content of these elements was calculated. The total content of the obtained Ca, Ba, and Sr was defined as "Ca group element content", and the total content of the obtained La, Y, and Ce was defined as "Y group element content".
[0061]
Further, when the primary coating of the present invention contains Ca group elements, the "number density of Ca group element enriched regions" D4 on the projection plane is 0.008 elements / μm 2 or more. Although the details will be described later, it is considered that the Ca group elements contained in the annealing separator play an important role in controlling the number density of the embedded oxide in the process of forming the primary film. The number density D4 of the Ca group element enrichment region in the primary film defined here represents a form in which the Ca group element that acted on the formation of the embedded oxide remains in the primary film in the process of forming the primary film. it is conceivable that. When D4 becomes high, Ca group elements are uniformly supplied to the embedded oxide, so that D3, which is the number density of Al-based oxides, becomes high, and at the same time, the progress of the embedded oxide into the mother steel material is promoted.
When D4 is less than 0.008 / μm 2, not only the number density of the embedded oxide particles cannot be sufficiently obtained and the adhesion is not improved, but also the above-mentioned characteristic Al distribution cannot be obtained.
If D4 is too high, the frequency of formation of the impregnated oxide particles formed in connection with this will also be excessively high, and the adjacent impregnated oxides will coalesce and integrate with each other as in the case where D3 is excessively high. Therefore, it inhibits the formation of the characteristic Al distribution. Therefore, D4 ​​is 2.000 pieces / It is μm 2 or less.
[0062]
[Production method]
An example of a method for manufacturing a grain-oriented electrical steel sheet according to the present invention will be described.
Examples of manufacturing methods for directional electromagnetic steel sheets include a steelmaking process, a hot-rolling process, a hot-rolled plate annealing process, a cold-rolling process, a decarburization annealing process, an annealing separator layer forming process, and a finishing annealing process. Equipped with. Hereinafter, each step will be described. The processing conditions for each of the following steps do not deviate from the general range and do not need to be special. Characteristic in the method of the present invention is an annealing separator that coats the surface of the steel sheet before finish annealing to control the structure of the primary coating.
[0063]

In the steelmaking process, molten steel is melted by a normal method such as a converter, and a well-known refining process and casting process are carried out to produce a slab having the following chemical composition. Some of the elements contained in the slab are discharged from the steel in the decarburization annealing and finish annealing steps described later. In particular, C for controlling primary recrystallization and S, Al, N and the like functioning as inhibitors are largely removed. Therefore, the chemical composition of the slab is different from the chemical composition of the steel sheet of the final product.
[0064]
C: 0.005 to 0.100% by mass,
If the C content exceeds 0.100% by mass, the time required for decarburization annealing becomes long. In this case, the manufacturing cost is high and the productivity is also lowered. Therefore, the C content in the slab is 0.100% by mass or less. The preferred upper limit of the C content in the slab is 0.092% by mass, more preferably 0.085% by mass. Further, if the C content is less than 0.005% by mass, the dispersed state of precipitates such as MnS, MnSe and AlN and the steel plate grain structure after decarburization annealing cannot be uniformly obtained, and Goss after secondary recrystallization. It may worsen the degree of azimuth integration. Therefore, the lower limit of the C content in the slab is 0.005% by mass. The preferred lower limit of the C content in the slab is 0.020% by mass, more preferably 0.040% by mass.
[0065]
Si: 2.5-4.5% by mass,
As explained in the section on chemical composition of grain-oriented electrical steel sheets, which is a product, Si increases the electrical resistance of steel, but if it is present in excess, cold workability deteriorates. When the Si content in the slab is 2.5 to 4.5% by mass, the Si content of the grain-oriented electrical steel sheet after the finish annealing step is 2.5 to 4.5% by mass. The preferred upper limit of the Si content in the slab is 4.0%, more preferably 3.8% by mass. The preferable lower limit of the Si content in the slab is 2.6% by mass, more preferably 2.8% by mass.
[0066]
Mn: 0.02 to 0.20% by mass
As explained in the item of chemical composition of grain-oriented electrical steel sheet which is a product, Mn combines with S and Se to form a precipitate and functions as an inhibitor in the manufacturing process. Mn further enhances the hot workability of steel. When the Mn content in the slab is 0.02 to 0.20% by mass, the Mn content of the directional electromagnetic steel sheet after the finish annealing step is 0.02 to 0.20% by mass. The preferred upper limit of the Mn content in the slab is 0.13% by mass, more preferably 0.10% by mass. The preferred lower limit of the Mn content in the slab is 0.03% by mass, more preferably 0.04% by mass.
[0067]
One or more elements selected from the group consisting of S and Se: 0.005 to 0.070% by mass in total
During the manufacturing process, sulfur (S) and selenium (Se) combine with Mn to form MnS and MnSe. Both MnS and MnSe function as inhibitors necessary for suppressing grain growth during secondary recrystallization. If the total content of one or more elements selected from the group consisting of S and Se is less than 0.005% by mass, it is difficult to obtain the above effect. On the other hand, if the total content of one or more elements selected from the group consisting of S and Se exceeds 0.070% by mass, secondary recrystallization does not occur during the manufacturing process and the magnetic properties of the steel deteriorate. do. Therefore, in the slab, the total content of one or more elements selected from the group consisting of S and Se is 0.005 to 0.070% by mass. The preferable lower limit of the total content of one or more elements selected from the group consisting of S and Se is 0.008% by mass, more preferably 0.016% by mass. The preferred upper limit of the total content of one or more elements selected from the group consisting of S and Se is 0.060% by mass, more preferably 0.050% by mass.
[0068]
Sol. Al: 0.005 to 0.050% by mass
During the manufacturing process, aluminum (Al) combines with N to form AlN. AlN functions as an inhibitor. Sol. In the slab. If the Al content is less than 0.005% by mass, the above effect cannot be obtained. On the other hand, sol. In the slab. If the Al content exceeds 0.050% by mass, AlN becomes coarse. In this case, AlN becomes difficult to function as an inhibitor, and secondary recrystallization may not occur. Therefore, sol. In the slab. The Al content is 0.005 to 0.050% by mass. Sol. In the slab. The upper limit of the Al content is preferably 0.040% by mass, more preferably 0.035% by mass. Sol. In the slab. The lower limit of the Al content is preferably 0.010% by mass, more preferably 0.015% by mass.
[0069]
N: 0.001 to 0.030% by mass
During the manufacturing process, nitrogen (N) combines with Al to form AlN, which functions as an inhibitor. If the N content in the slab is less than 0.001% by mass, the above effect cannot be obtained. On the other hand, if the N content in the slab exceeds 0.030% by mass, AlN becomes coarse. In this case, AlN becomes difficult to function as an inhibitor, and secondary recrystallization may not occur. Therefore, the N content in the slab is 0.001 to 0.030% by mass. The preferred upper limit of the N content in the slab is 0.012% by mass, more preferably 0.010% by mass. The preferred lower limit of the N content in the slab is 0.005% by mass, more preferably 0.006% by mass.
[0070]
The balance of the chemical composition in the slab of the present invention consists of Fe and impurities. Here, the impurities are those that are mixed from the ore as a raw material, scrap, or the manufacturing environment when the slab is industrially manufactured, and are allowed as long as they do not adversely affect the slab of the present embodiment. Means something.
[0071]

The slab according to the present invention may further contain at least 0.60% by mass of one or more elements selected from the group consisting of Cu, Sn and Sb instead of a part of Fe. Further, the slab according to the present invention may further contain 0.02% by mass or less in total of one or more elements selected from the group consisting of Ca, Ba and Sr instead of a part of Fe. All of these elements are arbitrary elements.
[0072]
One or more elements selected from the group consisting of Cu, Sn and Sb: 0 to 0.6% by mass in total
Cu (copper), tin (Sn) and antimony (Sb) are all optional elements and may not be contained. In the case of the contained slab component, Cu, Sn and Sb all increase the magnetic flux density of the grain-oriented electrical steel sheet. If Cu, Sn and Sb are contained even in a small amount, the above effect can be obtained to some extent. However, if the total contents of Cu, Sn and Sb exceed 0.60% by mass, it becomes difficult to form an internal oxide layer during decarburization annealing. In this case, during finish annealing, MgO as an annealing separator and SiO 2 in the internal oxide layer react to delay the progress of primary film formation. As a result, the adhesion of the primary coating is reduced. Further, after purification annealing, Sn and Sb are likely to remain as impurity elements. As a result, the magnetic properties deteriorate. Therefore, the total content of one or more elements selected from the group consisting of Cu, Sn and Sb is 0 to 0.60% by mass. The preferable lower limit of the total content of one or more elements selected from the group consisting of Cu, Sn and Sb is 0.005% by mass, more preferably 0.007% by mass. The preferred upper limit of the total content of one or more elements selected from the group consisting of Cu, Sn and Sb is 0.50% by mass, more preferably 0.45% by mass.
[0073]
The slab according to the present invention may further contain 0.030% by mass or less in total of one or more elements selected from the group consisting of Bi, Te and Pb instead of a part of Fe. All of these elements are arbitrary elements.
[0074]
One or more elements selected from the group consisting of Bi, Te and Pb: 0 to 0.030% by mass in total
Bismuth (Bi), tellurium (Te) and lead (Pb) are all optional elements, but they are notable elements in the present invention from the following viewpoints.
These elements increase the magnetic flux density of grain-oriented electrical steel sheets. The preferable lower limit of the total content of one or more elements selected from the group consisting of Bi, Te and Pb for this purpose is 0.0005% by mass, more preferably 0.0010% by mass.
On the other hand, if these elements segregate on the surface during finish annealing, the embedded oxide layer (2) does not become thick and the film adhesion of the primary film deteriorates. Therefore, although it has the effect of increasing the magnetic flux density, the addition amount has to be limited to about 0.030% by mass or less in order to secure the film adhesion. Since the effect of the present invention is to improve the film adhesion by changing the structure of the embedded oxide, it is particularly effective when a production method containing these elements is applied. When the present invention is applied, good film adhesion can be ensured even if these elements are 0.010% by mass or more, and further 0.015% by mass or more. However, if it is contained in excess, the decrease in adhesion cannot be avoided even with the effect of the present invention, and if it cannot be completely discharged to the outside of the system due to purification during finish annealing and remains in the base steel sheet, it has magnetic properties. The upper limit is 0.0300% by mass in order to deteriorate. The preferred upper limit is 0.0200% by mass, and the more preferable upper limit is 0.0150% by mass.
[0075]

Heat the slab with the above chemical composition. The heating temperature of the slab is, for example, more than 1280 ° C to 1350 ° C. Hot rolling is performed on the heated slab to produce a hot-rolled steel sheet. The hot-rolled steel sheet may be annealed if necessary.
[0076]

In the cold-rolled process, cold-rolled steel sheets are cold-rolled to manufacture cold-rolled steel sheets.
[0077]
The prepared hot-rolled steel sheet is cold-rolled to manufacture a cold-rolled steel sheet, which is a base steel sheet. Cold rolling may be carried out only once or may be carried out a plurality of times. When cold rolling is carried out a plurality of times, cold rolling is carried out, intermediate annealing for the purpose of softening is carried out, and then cold rolling is further carried out. Cold rolling is carried out once or a plurality of times to produce a cold-rolled steel sheet having a product plate thickness (plate thickness as a product).
[0078]
The cold rolling ratio in one or more cold rollings is 80% or more. Here, the cold spread rate (%) is defined as follows.
Cold rolling ratio (%) = (1-Thickness of cold-rolled steel sheet after the last cold rolling / Thickness of hot-rolled steel sheet before the start of the first cold rolling) x 100
[0079]
The preferable upper limit of the cold spread rate is 95%. Further, the hot-rolled steel sheet may be heat-treated or pickled before the hot-rolled steel sheet is cold-rolled.
[0080] [0080]

Decarburization annealing is performed on the cold-rolled steel sheet manufactured by the cold-rolling process, and nitriding annealing is performed as necessary. Decarburization annealing is performed in a well-known hydrogen-nitrogen-containing moist atmosphere. By decarburization annealing, the C concentration of grain-oriented electrical steel sheets is reduced to 50 ppm or less, which can suppress magnetic aging deterioration. In the decarburization annealing process, primary recrystallization occurs at the same time, and the processing strain introduced by cold spreading is released. Further, in the decarburization annealing step, an internal oxide layer containing SiO 2 as a main component is formed on the surface layer portion of the base steel sheet. The SiO 2 formed here reacts with MgO in the aqueous slurry containing the annealing separator applied thereafter during the finish annealing to form a primary film whose morphology is controlled in the present invention. Decarburization annealing process The conditions are well known, for example, the maximum temperature reached is 750 to 950 ° C. The holding time at the temperature is, for example, 1 to 5 minutes.
[0081]

In the present invention, the "annealing separator" refers to a substance that covers the surface of the above-mentioned decarburized annealing plate for which finish annealing is performed for the main purpose of preventing seizure of the steel sheet during finish annealing.
In this step, an aqueous slurry containing a compound or the like constituting the annealing separator is prepared. The aqueous slurry is prepared by mixing and stirring a compound or the like containing an element constituting an annealing separator with water. This slurry is applied to the surface of the decarburized annealed plate by a roll coater or a spray. The surface slurry is dried by inserting the steel sheet coated with the slurry into a furnace kept at 400 to 1000 ° C. and holding it for 10 to 90 seconds. At this time, the temperature of the steel sheet itself rises only to about 400 ° C. Therefore, no significant change in crystal structure such as grain growth occurs in the steel sheet, and in the slurry, water evaporates and is discharged, and some of the contained elements react with water to form an oxygen-containing compound. do. Here, the decarburized annealing plate coated with the annealing separator is called a finishing annealing steel sheet.
Basically, the annealing separator that finally covers the surface of the steel sheet before finish annealing can be considered to be a simple mixture of various compounds used as the raw material.
[0082]

After drying the annealing separator, perform finish annealing. In the finish annealing, the annealing temperature is set to 1150 to 1250 ° C., and the decarburized annealing plate coated with the annealing separator is annealed. The soaking time is, for example, 15 to 30 hours. The atmosphere inside the furnace in the finish annealing is a well-known atmosphere. In the final step of the finish annealing step, in particular, some of the elements such as S, Al, and N that function as inhibitors are discharged to the outside of the system. This process is sometimes called "purification (annealing)".
[0083]
In the grain-oriented electrical steel sheet manufactured by the above manufacturing process, a primary film containing Mg 2SiO 4 as a main component is formed on the surface. At this time, by applying the annealing separator described later, the grain-oriented electrical steel sheet of the present invention is obtained in which the interface structure between the base steel sheet and the primary film satisfies the provisions of the invention, and the film adhesion is improved.
[0084]

The grain-oriented electrical steel sheet according to the present invention may further be subjected to an insulating film forming step after the finish annealing step. In the insulating film forming step, a well-known insulating coating agent mainly composed of colloidal silica and phosphate is applied to the surface of the directional electromagnetic steel plate after finish annealing, and then baking is performed. These treatments do not hinder the effect of the present invention, and an insulating film having a function of applying tension to the steel sheet is formed on the primary film.
[0085]

The grain-oriented electrical steel sheet according to the present invention may further undergo a well-known magnetic domain subdivision treatment step after cold spreading, decarburization annealing, finish annealing, or after forming an insulating film. In the magnetic domain subdivision processing step, strain is applied to the surface of the grain-oriented electrical steel sheet by laser irradiation or rolling with a roll with a convex portion, or grooves are formed on the surface by laser irradiation or etching. These treatments do not hinder the effects of the present invention and can be expected to improve the magnetic properties.
[0086]
[Annealing separator]
The annealing separator of the present invention contains magnesium oxide (MgO) as a main component, and further comprises one or more elements (Y group elements) selected from the group consisting of Y, La, and Ce, and Ca, Sr, and Ba. It contains one or more elements (Ca group elements) selected from the group.
[0087]

The ratio of each content of Y, La, Ce, and Mg to the content of MgO in the annealing separator is expressed in mass%, and is expressed as [Y], [La], [Ce], and [Mg]. The annealing separator uses these elements as the following formula:
(0.253 [Y] +0.180 [La] +0.170 [Ce]) /0.454 [Mg] = 0.40 to 0.360
It is contained within the range that satisfies.
In the following, (0.253 [Y] +0.180 [La] +0.170 [Ce]) /0.454 [Mg] may be described as CY.
Here, it is considered that each coefficient of the above formula contains Y, La, and Ce atoms present in the quenching separator as Y 2O 3, La 2O 3, CeO 2, and MgO, which are the respective stable oxides. It can be calculated as follows with the coefficient calculated by.
Y coefficient: Y 2O 3 molecular weight / Y 2O 3 density / Y atomic weight / 2 = 225.8 / 5.01 / 88.9 / 2 = 0.253
La coefficient: La 2O 3 molecular weight / La 2O 3 density / La atomic weight / 2 = 325.8 / 6.51 / 138.9 / 2 = 0.180
Ce coefficient: CeO 2 molecular weight / CeO 2 density / Ce atomic weight = 172.1 / 7.22 / 140.1 = 0.170
Mg coefficient: MgO molecular weight / MgO density / Mg atomic weight = 40.3 / 3.65 / 24.3 = 0.454
[0088]
CY is the volume ratio of the Y group elements in the annealing separator as stable oxides of each element, the total content, and MgO, which is the main constituent substance in the annealing separator. In other words, it can be said to be an index showing the magnitude of the influence of the Y group elements on Mg in the oxide.
[0089]
The particles containing the Y group element can contain the Y group element as a simple substance, an alloy, or a compound, but as a substance containing oxygen or a substance that is oxidized during finish annealing and changes to a compound containing oxygen. It is preferable to contain it. The oxygen-containing compound is, for example, an oxide, a hydroxide, a carbonate, a sulfate, or the like. This may be mixed as a raw material, or may be changed to a compound containing oxygen in the drying process of the above-mentioned annealing separation agent layer forming step, for example.
[0090]
When the annealing separator contains Y group elements, the embedded oxide layer (2) becomes thicker, and the adhesion of the primary coating to the base steel sheet is enhanced. If the CY is less than 0.40, this effect cannot be sufficiently obtained. On the other hand, when the CY exceeds 0.360, the embedded oxide layer (2) becomes excessively thick and the magnetic characteristics deteriorate. Therefore, the CY is 0.40 to 3.60. The preferred lower limit of CY is 0.80, more preferably 1.20. The preferred upper limit is 3.20, more preferably 2.80.
[0091]
The reason why the thickness of the embedded oxide layer (2) can be controlled by controlling the content of the Y group element is not clear, but it is considered as follows.
In the initial (relatively low temperature) process of finish annealing, the Y group element contains oxygen by reacting with oxygen in the annealing separator, not only when it is a compound containing oxygen as an annealing separator, but also when it is not. It exists as a compound. Then, in the mid-term process in which the primary film is formed (the formation of Mg 2SiO 4 starts), the compound decomposes and releases oxygen.
In order for the inlaid oxide layer (2) to penetrate the inside of the base steel sheet, a sufficient amount of Mg is diffused from the annealing separator side into SiO 2 at the deep position of the internal oxide layer formed by decarburization annealing. Although it needs to be supplied, since the finish annealing is carried out in a high temperature and hydrogen atmosphere, if oxygen is insufficient, SiO 2 becomes unstable and decomposes.
At this time, the Y group element compound containing oxygen decomposes and releases oxygen, which delays the decomposition of SiO 2 and can maintain the formation of SiO 2 until Mg arrives. Mg 2SiO 4 is a stable oxide even in a high temperature and hydrogen atmosphere of finish annealing, and as a result, a thick inlaid oxide layer (2) is formed.
[0092]

The ratio of each content of Ca, Sr, Ba, and Mg to the content of MgO in the annealing separator is expressed in mass%, and is referred to as [Ca], [Sr], [Ba], and [Mg]. The annealing separator uses these elements as the following formula:
(0.353 [Ca] +0.252 [Sr] +0.195 [Ba]) /0.454 [Mg] ≈ 0.20 to 2.20
Contains only the amount that satisfies.
In the following, (0.353 [Ca] +0.252 [Sr] +0.195 [Ba]) /0.454 [Mg] may be described as CC.
Here, each coefficient of the above formula is calculated assuming that the Ca, Ba, Sr, and Mg atoms present in the quenching separator are contained as the respective stable oxides, CaO, BaO, SrO, and MgO. It can be calculated as follows with the coefficient.
Ca coefficient: CaO molecular weight / CaO density / Ca atomic weight = 56.1 / 3.96 / 40.1 = 0.353
Coefficient of Sr: SrO molecular weight / SrO density / Sr atomic weight = 103.6 / 3.96 / 87.6 = 0.252
Coefficient of Ba: BaO molecular weight / BaO density / Ba atomic weight = 153.3 / 4.7 / 137.3 = 0.195
Mg coefficient: MgO molecular weight / MgO density / Mg atomic weight = 40.3 / 3.65 / 24.3 = 0.454
[0093]
CC is the volume ratio of the total content of Ca group elements in the annealing separator converted as stable oxides of each element and MgO, which is the main constituent substance in the annealing separator. In other words, it can be said to be an index showing the magnitude of the influence of Ca group elements on Mg in oxides.
The particles containing the Ca group element can contain the Ca group element as a simple substance, an alloy, or a compound, but as a compound containing oxygen or a substance that is oxidized during finish annealing and changes to a compound containing oxygen. It is preferable to contain it. The oxygen-containing compound is, for example, an oxide, a hydroxide, a carbonate, a sulfate, or the like. This may be mixed as a raw material, or may be changed to a compound containing oxygen in the drying process of the above-mentioned annealing separation agent layer forming step, for example.
[0094]
It is considered that the Ca group element reacts with SiO 2 existing in the surface region of the mother steel sheet as the starting point of forming the primary film to facilitate the formation of the embedded oxide, that is, to increase the number density of the embedded oxide layer region. There is.
The reason for showing such an effect is not clear, but it is thought to be as follows.
As described above, in order to form the inlaid oxide layer (2), it is necessary to react SiO 2 formed in a region deep from the surface of the base steel sheet with Mg supplied from the annealing separator. be.
The Ca group element has the same function as Mg, but when comparing the diffusion rates of Mg in SiO 2 and the Ca group element, the Ca group element is faster, so that the Ca group element is present in the quenching separator. The composite oxide of SiO 2 and Ca group elements was formed in the inner region of the mother steel plate earlier than Mg 2SiO 4, which is a composite oxide of SiO 2 and Mg, and the inlaid oxide proceeded to the inside of the steel plate at an earlier stage. To stabilize with. At this point, the inlaid oxide is mainly a composite oxide of Ca and Si, but after that, Mg that arrives later forms a more stable oxide than Ca, so the oxide composition gradually changes and finally. In the end, it will be replaced with Mg 2SiO 4, which is the main constituent of the primary coating. In this way, the annealing separator containing the Ca group element increases the number density of the embedded oxide layer region of the primary coating.
It is considered that the Ca group elements discharged from the oxide by substitution with Mg combine with S in the base steel sheet to form sulfide. In this process, Ca finally remaining in the primary coating is observed as the Ca group element contained in the primary coating and the number density D4 of the Ca group element enrichment region.
[0095]
If the CC is less than 0.20, the above effect cannot be sufficiently obtained. On the other hand, if the CC exceeds 2.20, the number density becomes excessively high in the initial process of inlaid oxide formation, which hinders the movement of the domain wall and deteriorates the iron loss. When the CC is 0.20 to 2.20, it is possible to improve the adhesion of the primary coating to the base steel sheet while suppressing the deterioration of iron loss.
[0096]

The annealing separator may further contain Ti, Zr, and Hf, if necessary. Hereinafter, one or more elements selected from the group consisting of Ti, Zr, and Hf may be referred to as "Ti group elements".
The ratio of each content of Ti, Zr, Hf, and Mg to the content of MgO in the quenching separator is expressed in mass%, and is referred to as [Ti], [Zr], [Hf], and [Mg]. The annealing separator uses these elements as the following formula:
(0.370 [Ti] +0.238 [Zr] +0 .. 122 [Hf]) /0.454 [Mg] <6.50
Contains only the amount that satisfies.
In the following, (0.370 [Ti] +0.238 [Zr] +0.122 [Hf]) /0.454 [Mg] may be described as CT.
Here, it is considered that each coefficient of the above formula contains the Ti, Zr, Hf, and Mg atoms present in the quenching separator as the respective stable oxides, TIO 2, ZrO 2, HfO 2, and MgO. It can be calculated as follows with the coefficient calculated by.
Ti coefficient: (TIO 2 molecular weight / TIM 2 density / Ti atomic weight) = 79.9 / 4.506 / 47.9 = 0.370
Zr coefficient: (ZrO 2 molecular weight / ZrO 2 density / Zr atomic weight) = 91.2 / 5.68 / 123.2 = 0.238
Coefficient of Hf: (HfO 2 molecular weight / HfO 2 density / Hf atomic weight) = 210.5 / 9.68 / 178.5 = 0.122
Mg coefficient: MgO molecular weight / Mg atomic weight = 40.3 / 24.3 = 0.454
[0097]
CT is the volume ratio of the total content of Ca group elements in the annealing separator converted as stable oxides of each element and MgO, which is the main constituent substance in the annealing separator. In other words, it can be said to be an index showing the magnitude of the influence of Ca group elements on Mg in oxides.
Particles containing Ti group elements can contain Ti group elements as simple substances, alloys, or compounds. The compounds are, for example, sulfates, carbonates, hydroxides and the like.
[0098]
The Ti group elements promote the reaction between MgO in the annealing separator and SiO 2 on the surface layer of the mother steel sheet formed by decarburization annealing in the finish annealing, and promote the formation of Mg 2SiO 4. On the other hand, if the CT exceeds 6.50, the effect is saturated and there is a possibility of causing deterioration of iron loss due to the development of an excessive film.
[0099]
Further, the annealing separator may contain an element known to have a known effect as long as the effect of the present invention is not impaired.
[0100]
The above CY, CC, and CT values ​​are obtained from the content of each group element and the content of Mg in the annealing separator.
[0101]

The annealing separator of the present invention contains the above-mentioned various elements, but they exist in a mixed state as various compounds as well as elemental metals.
The present invention makes some provisions regarding this mixed situation.
[0102]
In the annealing separator of the present invention, the average particle size of MgO is 0.08 to 1.50 μm. Hereinafter, the average particle size of MgO is described as R1. If R1 is less than 0.08 μm, it becomes impossible to sufficiently avoid coil contact between the coil plates during finish annealing, and the function as an annealing separator is impaired, so that seizure occurs between the coil plates. When R1 exceeds 1.50 μm, the contact area between MgO and SiO 2 during the formation of the primary film decreases, and since MgO itself is inactive, the reaction is difficult to occur and the formation of the primary film is delayed, resulting in poor film adhesion. Become inferior.
[0103]
The annealing separator of the present invention has an average particle size of particles containing Ca group elements of 0.08 to 1.50 μm. Hereinafter, the average particle size of the particles containing the Ca group element is described as R2.
If R2 is less than 0.08 μm, the Ca group element is active, so the supply amount of the Ca group element to the primary film being formed becomes too large with respect to the supply amount of Mg. Therefore, the formation of Mg 2SiO 4 is hindered, and the adhesion of the primary coating deteriorates.
Further, when R2 is as large as more than 1.50 μm, the contact frequency between MgO and SiO 2 decreases, and the supply of Mg to the primary film being formed becomes insufficient. Therefore, the formation of Mg 2SiO 4 is delayed, and the adhesion of the primary coating is deteriorated.
[0104]
Further, in the annealing separator of the present invention, the ratio of R2 to R1, that is, R2 / R1 is in the range of 0.3 to 3.0.
When R2 / R1 is less than 0.3, the region (S3 / S5) which is the fitting Al region A5 of the formed primary film is lowered, and the film adhesion is deteriorated. Therefore, the lower limit of R2 / R1 is preferably 0.5 or more, more preferably 0.8 or more.
On the other hand, when R2 / R1 exceeds 3.0, the number density D3 of the Al-concentrated region of the formed primary film is lowered to less than 0.020, and the film adhesion is deteriorated. Therefore, the upper limit of R2 / R1 is preferably 2.6 or less, more preferably 2.2 or less.
[0105]
The reason why the film adhesion is improved by the above R1, R2 and R2 / R1 is not clear, but it is considered as follows.
Generally, the smaller the powder, the easier it is to aggregate, and when powder compounds with significantly different particle sizes are mixed, fine compounds aggregate. Considering the mixing situation of MgO and Ca group element, the compound of Ca group element is excessively fine, and when R2 / R1 is less than 0.3, the compound of Ca group element aggregates. When such a mixture is adhered to the surface of the base steel sheet, in the contact state with the base steel sheet, the region where only the Ca group element is in contact with the base steel plate exists as a region having a considerable size. .. Similarly, when R2 / R1 exceeds 3.0, MgO aggregates, and a region where there is almost no contact between the Ca group element and the base steel sheet exists as a region having a considerable size.
If the formation of the primary film by finish annealing progresses in this situation, there will be a large difference in the formation rate of the embedded oxide between the region where only the Ca group element is in contact with the base steel sheet and the region where only MgO is in contact. The interface has a very non-uniform structure. Such non-uniformity reduces the adhesion of the coating film due to stress concentration during bending.
[0106]
The method for measuring the specified value regarding the above-mentioned "elemental dispersion of the annealing separator" will be described below.
R1 and R2 are measured as follows. That is, the raw material powder is measured by the laser diffraction / scattering method based on JIS Z8825 (2013) using a laser diffraction / scattering type particle size distribution measuring device (LA-700 manufactured by HORIBA, Ltd.), and the volume is measured. Obtain a reference particle size distribution. Further, this is converted into a particle size distribution based on the number of particles, and finally the average particle size based on the number of particles is obtained for each raw material powder.
[0107]
It should be noted that R1 and R2 specified in the present invention are values ​​calculated based on the number of particles.
Generally, the average particle size of particles is often specified by weight. In the weight standard, in a powder having a non-uniform particle size, the abundance ratio of particles in a specific particle size range is expressed as a ratio to the total weight. This weight-based average particle size cannot be representative of the entire measurement target in the particle size distribution, for example, when the abundance ratio of coarse particles with very low abundance frequency changes slightly, the coarse particles become Since the weight accounts for a large proportion of the total weight, the average particle size obtained is characterized by large fluctuations.
On the other hand, since the average particle size based on the number of particles specified in the present invention is based on the number of particles classified by size, the average particle size of the whole is not significantly changed if the number of particles of a specific size does not change significantly. Does not fluctuate significantly. That is, the value reflects the particle size of the particles having a high abundance frequency. In other words, this value has a strong correlation with the number of particles per unit volume.
The effect of the present invention is that, as described above, in the element dispersion in the annealing separator, particularly in the dispersion of Ca group elements, the region where the Ca group elements are concentrated in the formed primary film occupies an unreasonably large area. It is exhibited by being present in an appropriate size in the annealing separator so that it does not occur. Therefore, although the frequency is low, the particle size must be specified not by weight but by the average particle size based on the number of particles so that the influence of coarse particles can be eliminated.
[0108]
The characteristics of the elemental dispersion provided by the quenching separator are as described above. Among them, in order to control the dispersed state of the Ca group elements in the formed primary film, the number density of particles in the raw material powder is appropriate. It needs to be something like that. This situation can be realized by satisfying the number density of Ca group element-containing particles in the raw material powder ≥ 25 billion particles / cm3. For the raw material powder containing Ca group elements used in the annealing separator of the present invention, in consideration of the above range, use a raw material whose particle size distribution is controlled to stay within a fine range among commercially available products. ..
The number density of the particles in the raw material powder was measured using a laser diffraction type particle size distribution measuring device (LA-700) manufactured by Horiba.
Example
[0109]
Hereinafter, embodiments of the present invention will be specifically described with reference to examples. These examples are examples for confirming the effect of the present invention, and do not limit the present invention.
The present invention relates to an annealing separator that coats a steel sheet before finish annealing and a primary film formed thereby, which plays an important role in forming a primary film, and the base steel sheet does not need to be special. Therefore, in this embodiment, the steel sheet is manufactured under constant conditions (hot-rolling, cold-rolling, annealing conditions, etc.) that are not directly related to the effect of the invention. First, the common conditions of all the examples will be described, and then the results of examining the effects of the invention by changing the conditions related to the formation of the primary film in Examples 1 and 2 will be described.
[0110]
[Manufacturing of grain-oriented electrical steel sheets]
The molten steel having the chemical composition shown in Table 1 was manufactured in a vacuum melting furnace, and a slab was manufactured by a continuous casting method.
[0111]
[table 1]

[0112]
Each slab of Table 1 heated at 1350 ° C. was hot-rolled to produce a hot-rolled steel sheet having a plate thickness of 2.3 mm. In molten steel No. 5, since the content of Si in the molten steel was too high, cracks occurred during hot rolling, and the hot-rolled steel sheet could not be manufactured.
[0113]
The obtained hot-rolled steel sheet was annealed and pickled. Annealing of hot-rolled plates was carried out at 1100 ° C. for 5 minutes.
[0114]
The hot-rolled steel sheet after pickling was cold-rolled to produce a cold-rolled steel sheet having a plate thickness of 0.22 mm. The cold spread rate is 90.4%.
[0115]
Primary recrystallization annealing was performed on the cold-rolled steel sheet, which also served as decarburization annealing. The maximum ultimate temperature was 750 to 950 ° C., and the holding time at the maximum ultimate temperature was 2 minutes.
[0116]
Subsequently, the aqueous slurry was applied to the decarburized annealed plate and held in a furnace at 900 ° C. for 10 seconds to dry the aqueous slurry. The aqueous slurry contains a raw material for the annealing separator.
In the preparation of an aqueous slurry containing a compound or the like constituting a quenching separator, when a compound containing a Ca group element is used as a component of the annealing separator, the number density of Ca group element-containing particles ≥ 25 billion / cm. Compounds were used when 3 was satisfied and when 3 was not satisfied. The number density of the Ca group-containing particles is calculated by measuring the particle size distribution of the raw material powder containing all the Ca group-containing particles used as the raw material powder of the aqueous slurry using a laser folding particle size distribution measuring device. When a raw material powder containing two or more types of Ca group-containing particles is used, the respective ratios are mixed and measured so as to be the same as the ratio in the slurry.
[0117]
Furthermore, finish annealing was carried out at 1200 ° C. for 20 hours. Through the above manufacturing process, a grain-oriented electrical steel sheet composed of a base steel sheet and a primary coating was manufactured. Table 2 shows the chemical composition of the base steel sheet of the manufactured grain-oriented electrical steel sheet.
In molten steel No. 3, the content of C was too high, and the value of iron loss after secondary recrystallization was extremely deteriorated, which was outside the scope of the present invention. Since the molten steel No. 4 contained too little Si and did not undergo secondary recrystallization, the values ​​of the magnetic flux density B8 and the iron loss were extremely deteriorated, which was outside the scope of the present invention.
In molten steel numbers 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15, Mn, S, Se, Sol. Since the content of Al or N was out of the range of an appropriate amount for forming the precipitate required for the expression of secondary recrystallization and the secondary recrystallization did not occur, as a result, the values ​​of the magnetic flux density B8 and the iron loss Was extremely deteriorated and was out of the scope of the present invention.
In molten steel No. 17, the Cu content was too high, and the film adhesion was extremely inferior, which was outside the scope of the present invention.
In molten steel No. 21, the Sn content was too high, and the film adhesion was inferior, which was outside the scope of the present invention.
In molten steel No. 25, the total content of Bi, Te and Pb was too high, and the film adhesion was inferior, which was outside the scope of the present invention.
[0118]
In the above manufacturing, as with general grain-oriented electrical steel sheets, the composition of the base steel sheet was different from that of the slab, which was the material, due to decarburization annealing and finish annealing (purification annealing) It will be different.
[0119]
[Table 2]

[0120]
[Characteristic evaluation]
In the steel sheet numbers 1, 2, 16, 18, 19, 20, 22, 23, 24, and 25 in which the components of the steel sheet fall within the scope of the present invention, the magnetic properties of the manufactured grain-oriented electrical steel sheet and the adhesion of the primary coating are determined. , Evaluated as test numbers 1-44.
[0121]

A sample having a length of 300 mm and a width of 60 mm in the rolling direction was taken from the grain-oriented electrical steel sheet of each test number and excited at 800 A / m to determine the magnetic flux density B8. Further, after baking an insulating film mainly composed of colloidal silica and phosphate, iron loss W 17/50 when excited at a maximum magnetic flux density of 1.7 T and a frequency of 50 Hz was measured. A grain-oriented electrical steel sheet having a magnetic flux density B8 of 1.92 T or more and W 17/50 of 0.85 W / kg or less was considered to have excellent magnetic characteristics. In addition, this reference value considers the composition (mainly Si: 3.25 mass%) and the thickness (the mother steel plate is 0.22 mm) of the steel plate of this Example. It goes without saying that the pass / fail standard values ​​differ depending on the steel sheet composition and plate thickness.
[0122]

A sample of 60 mm in length × 15 mm in width in the rolling direction was taken from the grain-oriented electrical steel sheet of each test number, and a bending test was carried out with a curvature of 10 mm. The bending test was carried out by using a cylindrical mandrel bending tester and installing it on the sample so that the axial direction of the cylinder coincided with the width direction of the sample. The surface of the sample after the bending test was observed, and the length of the machined area peeled portion in the rolling direction was measured at 13 levels every 1 mm from the width direction position of 1 mm from the edge, and the maximum length LS was specified. .. Then, the ratio of LS to the total length L (about 15.7 mm) of the processed portion is calculated, and the adhesion length percentage = (L-LS) / L × 100 (%) (primary film residual ratio). It was evaluated that 90% or more had excellent film adhesion.
[0123]

A sample with a length of 10 mm and a width of 10 mm in the rolling direction was taken from the directional electromagnetic steel sheet of each test number, electrolyzed at a constant potential in an electrolytic solution so that only the base steel sheet was dissolved, and the primary film was peeled off to form the primary film. The structure and composition were investigated. The peeling method and the measuring method were in accordance with the above-mentioned means, and the electrolytic solution component used was 10% acetylacetone-1% tetramethylammonium chloride-methanol, which was a non-aqueous solvent system, and the electrolytic amount was 80 C / cm 2. Finally, the following values ​​were obtained.
(1) Number density of Al enriched region: D3
(2) Area of ​​the region that is the inlaid oxide layer region and the Al-concentrated region: S5
(3) Area of ​​Al-enriched region: S3
(4) Distance from the reference value H0 of the boundary between the surface oxide layer and the embedded oxide layer in the region that is the embedded oxide layer region and the Al-concentrated region: H5.
(5) Area of ​​inlaid oxide layer region: S1
(6) Total content of Y group elements
(7) Total content of Ca group elements
(8) Number density of Ca group enrichment region: D4
(9) Observation area: S0
[0124]

The raw material powder of the annealing separator for the aqueous slurry was measured according to the above-mentioned means, and the following values ​​were obtained.
(11) (0.253 [Y] +0.180 [La] +0.170 [Ce]) /0.454 [Mg]: CY
(12) (0.353 [Ca] +0.252 [Sr] +0.195 [Ba]) /0.454 [Mg]: CC
(13) Average particle size of MgO: R1
(14) Average particle size of Ca group element-containing particles: R2
(15) Number density of particles containing Ca group elements ≥ 25 billion / cm 3
[0125]

The aqueous slurry to be applied to the steel plate after decarburization and annealing was adjusted by mixing MgO, Y group element-containing compounds and Ca group element-containing compounds with water so that the content of each group element was as shown in Table 3. At this time, the compound species and the contents (CY, CC) of each group element were changed.
[0126]
[Table 3]

[0127]
Table 4 shows the results. When the residual ratio of the primary coating was 90% or more, it was judged that the adhesion of the primary coating to the mother steel sheet was excellent. Further, if the magnetic flux density B8 is 1.92 or more and the iron loss W17 / 50 after laser irradiation is 0.85 or less, it is judged that the magnetic characteristics are excellent. It can be seen that those satisfying the provisions of the present invention can obtain good characteristics. With reference to Table 3, in Test Nos. 1-28, the chemical composition was appropriate and the conditions (CC, CY, R1, R2, R2 / R1) in the annealing separator were appropriate. As a result, the area ratio S1 / S0 of the fitted oxide layer (2) is 0.15 or more, the region S5 / S3 which is the fitted Al region A5 is 0.33 or more, and the distance H5 is 0.4 or more. The number density D3 in the Al-enriched region was 0.020 or more, which was within the range of the present invention. As a result, in the grain-oriented electrical steel sheets having these test numbers, the magnetic flux density B8 was 1.92T or more, and excellent magnetic characteristics were obtained. Furthermore, the residual ratio of the primary film was 90% or more, showing excellent adhesion. Furthermore, the appearance of the primary coating was also good.
[0128]
On the other hand, in test numbers 29 and 40, the total volume ratio CC of Ca group elements was too small, the morphology of the primary coating did not develop, S1 / S0 was less than 1.5, S5 / S3 was less than 0.33, and D3 was. It became 0.020. As a result, the residual rate of the primary film was 84% ​​and 56%, respectively, and the film adhesion was inferior.
[0129]
In test number 30, the total volume ratio CC of Ca group elements was too large, the morphology of the primary coating was too developed, and D3 exceeded 0.180 / μm 2. As a result, the iron loss W17 / 50 was 0.852 W / kg, and the magnetic characteristics were inferior.
[0130]
In test numbers 31 and 41, the total volume ratio CY of the Y group elements was too small, the thickness of the primary coating became thin, and H5 was less than 0.40 μm. As a result, the residual rates of the primary film were 62% and 58%, respectively, and the film adhesion was inferior.
[0131]
In test number 32, the total volume ratio CY of the Y group elements was too large, the thickness of the primary coating became too thick, and H5 exceeded 4.0 μm. As a result, the magnetic flux density B8 was 1.913T, and the magnetic characteristics were inferior.
[0132]
In test number 33, R2 was too small, the supply of Ca group elements and Mg was biased, and S1 / S0 was less than 0.15. As a result, the residual ratio of the primary film was 72%, and the film adhesion was inferior.
[0133]
In test number 34, R2 was too large, the supply of Ca group elements and Mg was biased, and as a result of Ca group elements, S1 / S0 was less than 0.15. As a result, the residual ratio of the primary film was 84%, and the film adhesion was inferior.
[0134]
In test number 35, R1 was too small and seizure occurred between the boards.
[0135]
In test number 36, R1 was too large and the supply of Mg to the coating was delayed. As a result, S1 / S0, S5 / S3, H5 and D3 were all below the reference value. As a result, the residual ratio of the primary film was 52%, and the film adhesion was inferior.
[0136]
In test number 37, R2 / R1 was too small, and the supply of Mg to Ca was delayed. As a result, S5 / S3 fell below the reference value. As a result, the residual ratio of the primary film was 88%, and the film adhesion was inferior.
[0137]
In test number 38, R2 / R1 was too large, and the supply of Ca to Mg was delayed. As a result, D3 was below the reference value. As a result, the residual ratio of the primary film was 89%, and the film adhesion was inferior.
[0138]
In test numbers 39 and 42, both CC and CY were too small, and as a result, sufficient development of the morphology of the primary coating was not obtained. As a result, S1 / S0 was less than 0.15, S5 / S3 was less than 0.33, H5 was less than 0.40, D3 was less than 0.020, and the primary coating residual rates were 31% and 14%, respectively. The film adhesion was inferior.
[0139]
In test number 43, there were too many Bi, Te, and Pb steel components. As a result, the deterioration of the primary coating became remarkable, and the effect of the coating morphology development by the additive to the annealing separator was insufficient. As a result, S1 / S0 was less than 0.15, H5 was less than 0.40, D3 was less than 0.020, the primary film residual rate was 10%, and the film adhesion was inferior.
In test number 44, the number density of Ca group element-containing particles in the raw material powder was low. As a result, S5 was less than 0.33, the primary film residual rate was 78%, and the film adhesion was inferior.
[0140]
[Table 4]

[0141]

The aqueous slurry to be applied to the steel plate after decarburization and annealing is mixed with water so that the content of each group element is as shown in Table 5 by mixing MgO, Y group element-containing compound, Ca group element-containing compound and Ti group-containing compound. It was adjusted. At this time, the compound species and the contents (CY, CC, CT) of each group element were changed.
[0142]
[Table 5]

[0143]
Table 6 shows the results. When the residual ratio of the primary coating was 90% or more, it was judged that the adhesion of the primary coating to the mother steel sheet was excellent. It can be seen that those satisfying the provisions of the present invention can obtain good characteristics. Further, if the magnetic flux density B8 is 1.92 or more and the iron loss W17 / 50 after laser irradiation is 0.85 or less, it is judged that the magnetic characteristics are excellent. It can be seen that those satisfying the provisions of the present invention can obtain good characteristics. With reference to Table 5, in test numbers 45-61, the chemical composition was appropriate and the conditions in the annealing separator (CC, CY, R1, R2, R2 / R1) were appropriate. As a result, the area ratio S1 / S0 of the fitted oxide layer (2) is 0.15 or more, the region S5 / S3 which is the fitted Al region A5 is 0.33 or more, and the distance H5 is 0.4 or more. The number density D3 in the Al-enriched region was 0.020 or more, which was within the range of the present invention. As a result, in the grain-oriented electrical steel sheets having these test numbers, the magnetic flux density B8 was 1.92T or more, and excellent magnetic characteristics were obtained. Furthermore, the residual ratio of the primary film was 90% or more, showing excellent adhesion.
[0144]
On the other hand, in test number 62, both CC and CY were too small, and as a result, the development of the morphology of the primary coating could not be sufficiently obtained. As a result, S1 / S0 was less than 0.15, S5 / S3 was less than 0.33, H5 was less than 0.40, D3 was less than 0.020, and the primary film residual rate was 42%, and the film adhesion was inferior. Met.
[0145]
In test number 63, R2 / R1 was too small, and the supply of Mg to Ca was delayed. As a result, S5 / S3 fell below the reference value. As a result, the residual ratio of the primary film was 72%, and the film adhesion was inferior.
[0146]
In test number 64, R2 / R1 was too large, and the supply of Ca to Mg was delayed. As a result, D3 was below the reference value. As a result, the residual ratio of the primary film was 71%, and the film adhesion was inferior.
[0147]
In test number 65, the total content CC of Ca group elements was too high, the morphology of the primary coating was too developed, and D3 exceeded 0.180 / μm 2. As a result, the iron loss 17/50 was 0.853 W / kg, and the magnetic characteristics were inferior.
[0148]
In test number 66, the total content CY of the Y group elements was too large, the thickness of the primary coating became too thick, and H5 exceeded 4.0 μm. As a result, the magnetic flux density B8 was 1.911T, and the magnetic characteristics were inferior.
[0149]
In test numbers 67 and 69, the total content CC of Ca group elements was too small, the morphology of the primary coating did not develop, S1 / S0 was less than 1.5, S5 / S3 was less than 0.33, and D3 was 0. It was less than 020. As a result, the residual rate of the primary film was 82% and 78%, respectively, and the film adhesion was inferior.
[0150]
In test numbers 68 and 70, the total content CY of the Y group elements was too small, the thickness of the primary coating became thin, and H5 was less than 0.40 μm. As a result, the residual rates of the primary film were 69% and 71%, respectively, and the film adhesion was inferior.
[0151]
In test numbers 71 and 72, the total volume ratio CT of Ti group elements was too large, and D3 exceeded 0.180 elements / μm 2. As a result, the iron loss W17 / 50 was 0.861 and 0.855 W / kg, respectively, and the magnetic characteristics were inferior.
[0152]
In test number 73, R2 was too small, the supply of Ca group elements and Mg was biased, and S1 / S0 was less than 0.15. As a result, the residual ratio of the primary film was 69%, and the film adhesion was inferior.
[0153]
In test number 74, R2 is largeThe supply of Ca group elements and Mg was biased, and as a result of Ca group elements, S1 / S0 was less than 0.15. As a result, the residual ratio of the primary film was 78%, and the film adhesion was inferior.
[0154]
In test number 75, R1 was too small and seizure occurred between the boards.
[0155]
In test number 76, R1 was too large and the supply of Mg to the coating was delayed. As a result, S1 / S0, S5 / S3, H5 and D3 were all below the reference value. As a result, the residual ratio of the primary film was 84%, and the film adhesion was inferior.
[0156]
In test number 77, there were too many arbitrary elements and steel components Bi, Te, and Pb in the steel. As a result, the deterioration of the primary coating became remarkable, and the effect of the coating morphology development by the additive to the annealing separator was insufficient. As a result, S1 / S0 was less than 0.15, H5 was less than 0.40, D3 was less than 0.020, the primary film residual rate was 10%, and the film adhesion was inferior.
In test number 78, the number density of Ca group element-containing particles was too low. As a result, S5 was less than 0.33, the primary film residual rate was 84%, and the film adhesion was inferior.
[0157]
[Table 6]

[0158]
The embodiment of the present invention has been described above. However, the embodiments described above are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and the above-mentioned embodiment can be appropriately modified and carried out within a range not deviating from the gist thereof.
Code description
[0159]
1 Surface oxide layer
2 Inserted oxide layer
3 Deepest fitting position
A0 All observation areas
A1 Inlaid oxide region
A2 Surface oxide layer area
A3 Al (aluminum) enriched area
A4 Ca group element enrichment region
A5 Al (aluminum) enriched region existing in the embedded oxide region
The scope of the claims
[Claim 1]
By mass%,
C: 0.0050% or less,
Si: 2.5-4.5%,
Mn: 0.02 to 0.20%,
One or more elements selected from the group consisting of S and Se: 0.005% or less in total,
Sol. Al: 0.010% or less, and
N: 0.010% or less,
And the balance is a base steel sheet having a chemical composition consisting of Fe and impurities.
It is formed on the surface of the base steel sheet and has a primary coating containing Mg 2SiO 4 as a main component.
The height of the surface of the primary coating on the base steel plate side and the components in the primary coating when the direction from the primary coating side to the base steel plate side is positive in the plate thickness direction of the base steel plate. In the characteristic X-ray intensity and height correlation distribution map developed by projecting information onto a plane parallel to the surface of the steel sheet,
Assuming that the median surface height of the primary coating is H0, the primary coating existing on the base steel plate side from H0 + 0.2 μm exists in the “fitted oxide layer region” and on the primary coating side from H0 + 0.2 μm. The primary coating is defined as a "surface oxide layer region", and
When the maximum value of the characteristic X-ray intensity of Al is specified and the region where the characteristic X-ray intensity of Al of 20% or more of the maximum value of the characteristic X-ray intensity of Al is obtained is defined as the "Al enriched region".
The primary coating is
(1) Number density of the Al-enriched region D3: 0.020 to 0.180 / μm 2,
(2) (total area S5 of the inlaid oxide layer region and the Al-enriched region) / (total area S3 of the Al-enriched region) ≧ 33%,
(3) Distance H5: 0.4 to 4.0 μm, obtained by subtracting H0 from the average height in the plate thickness direction of the region that is the embedded oxide layer region and the Al-concentrated region.
(4) (total area S1 of the embedded oxide layer region) / (observation area S0) ≧ 15%,
A grain-oriented electrical steel sheet characterized by satisfying the above conditions.
[Claim 2]
The primary coating contains one or more elements selected from the group consisting of Y, La, and Ce, and one or more elements selected from the group consisting of Ca, Sr, and Ba, and
In the characteristic X-ray intensity and height correlation distribution diagram, the maximum value of each characteristic X-ray intensity of Ca, Sr, and Ba is specified, and the characteristic X of Ca is 20% or more of the maximum value of the characteristic X-ray intensity of Ca. A region where the line intensity is obtained, a region where the characteristic X-ray intensity of Sr is 20% or more of the maximum value of the characteristic X-ray intensity of Sr, and a region where the characteristic X-ray intensity of Ba is 20% or more of the maximum value of the characteristic X-ray intensity of Ba. When the region where the characteristic X-ray intensity of Ba is obtained is combined to form the "Ca group element enrichment region",
The primary coating is
(5) Ratio of the total content of one or more elements selected from the group consisting of Y, La, and Ce to the content of Mg 2SiO 4 in the primary coating: 0.1 to 6.0% by mass. ,
(6) Ratio of the total content of one or more elements selected from the group consisting of Ca, Sr, and Ba to the content of Mg 2SiO 4 in the primary coating: 0.1 to 6.0% by mass. ,
(7) Number density of the Ca group element enrichment region D4: 0.008 / μm 2 or more,
The grain-oriented electrical steel sheet according to claim 1, which is characterized by satisfying the above-mentioned conditions.
[Claim 3]
An annealing separator containing MgO as the main component,
Contains one or more elements selected from the group consisting of Y, La, and Ce, and one or more elements selected from the group consisting of Ca, Sr, and Ba.
The ratio (mass%) of the content of Mg, Y, La, Ce, Ca, Sr, and Ba to the content of MgO is [Mg], [Y], [La], [Ce], [Ca], respectively. , [Sr], [Ba],
(8) (0.253 [Y] +0.180 [La] +0.170 [Ce]) /0.454 [Mg]: 0.40 to 3.60,
(9) (0.353 [Ca] +0.252 [Sr] +0.195 [Ba]) /0.454 [Mg]: 0.20 to 2.20,
The filling,
Moreover,
(10) Average particle size of MgO R1: 0.08 to 1.50 μm,
(11) Average particle size R2 of particles containing one or more elements selected from the group consisting of Ca, Sr, and Ba in the Ca group element enrichment region: 0.08 to 1.50 μm,
(12) (The average particle size R2) / (The average particle size R1): 0.3 to 3.0,
(13) Number density of particles containing Ca group elements ≥ 25 billion / cm 3,
An annealing separator characterized by satisfying the above conditions.
[Claim 4]
The annealing separator according to claim 3, wherein the particles containing one or more elements selected from the group consisting of Y, La, and Ce further contain oxygen.
[Claim 5]
The annealing separator according to claim 3, further containing one or more elements selected from the group consisting of Ti, Zr, and Hf.
[Claim 6]
By mass%,
C: 0.100% or less,
Si: 2.5-4.5%,
Mn: 0.02 to 0.20%,
One or more elements selected from the group consisting of S and Se: 0.005 to 0.070% in total,
Sol. Al: 0.005 to 0.050%, and
N: 0.001 to 0.030%,
A process of hot-rolling a slab containing Fe and impurities as the balance to produce a hot-rolled steel sheet.
The process of cold-rolling the hot-rolled steel sheet at a cold-rolling rate of 80% or more to manufacture the cold-rolled steel sheet,
The process of manufacturing a decarburized annealed sheet by performing decarburization annealing on the cold-rolled steel sheet,
The process of applying an aqueous slurry to the surface of the decarburized annealed plate and drying it,
It is provided with a step of performing finish annealing on the steel sheet after the aqueous slurry has been dried.
A method for producing a grain-oriented electrical steel sheet, wherein the aqueous slurry contains the annealing separation agent according to any one of claims 3 to 5.
[Claim 7]
The directional electromagnetic steel sheet according to claim 6, further containing 0.030% or less of one or more elements selected from the group consisting of Bi, Te and Pb in place of a part of Fe. Production method.
[Claim 8]
The directional electromagnetic steel according to claim 6 or 7, further containing at least 0.60% of one or more elements selected from the group consisting of Cu, Sn and Sb in place of a part of the Fe. Manufacturing method of steel plate.
[Claim 9]
By mass%,
C: 0.100% or less,
Si: 2.5-4.5%,
Mn: 0.02 to 0.20%,
One or more elements selected from the group consisting of S and Se: 0.005 to 0.070% in total,
Sol. Al: 0.005 to 0.050%, and
N: 0.001 to 0.030%,
A process of hot-rolling a slab containing Fe and impurities as the balance to produce a hot-rolled steel sheet.
The process of cold-rolling the hot-rolled steel sheet at a cold-rolling rate of 80% or more to manufacture the cold-rolled steel sheet,
The process of manufacturing a decarburized annealed sheet by performing decarburization annealing on the cold-rolled steel sheet,
A step of applying an aqueous slurry to the surface of the decarburized annealed plate and drying it is provided.
A method for producing a grain-forming electrical steel sheet for producing a grain-oriented electrical steel sheet, wherein the aqueous slurry contains the annealing separator according to any one of claims 3 to 5.
[Claim 10]
The finish annealing steel sheet according to claim 9, which contains 0.030% or less in total of one or more elements selected from the group consisting of Bi, Te and Pb in place of a part of the Fe. Production method.
[Claim 11]
The finish annealing according to claim 9 or 10, further comprising at least 0.60% of one or more elements selected from the group consisting of Cu, Sn and Sb in place of a part of the Fe. Steel sheet manufacturing method.