The present invention relates to a method for manufacturing a grain-oriented electrical steel sheet, a steel sheet for finish annealing, an annealing separator, a grain-oriented electrical steel sheet, and a method for manufacturing a steel sheet for finish annealing.
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 cold-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. At the time of 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 containing forsterite (Mg 2SiO 4) as the main component. 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 (Cu, 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. In particular, the compressive stress generated by the bending process makes it easy to peel off, and the adhesion is significantly 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, total amount 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 the annealing separator containing MgO as the main component. A method for producing a directional electromagnetic steel plate having excellent magnetic properties and primary 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]
However, Patent Document 5 mentions the effect of reducing the end face peeling caused by shearing with respect to the adhesion of the primary coating, but regarding the peeling resistance to bending, bending of about several tens of mmφ is not possible. It is not evaluated as having a smaller degree of processing than shearing. Since the peeling behavior due to shearing and bending is different, it is more difficult than before to ensure the adhesion of the primary coating to the base steel sheet as an electromagnetic steel sheet used in the iron core manufacturing method with a high degree of bending in recent years. Adhesion is required so that the primary coating does not peel off when bending is performed, and even if the material has no problem in peeling resistance of the sheared end face, resistance to severe bending may not always be obtained.
In addition, gas such as nitrogen contained in the steel sheet is released in the process of purifying the steel sheet component in the subsequent stage of finish annealing. At this time, the primary coating slows down the permeation of the gas. At this time, if the gas permeation of the primary coating becomes too slow, the gas pressure becomes high at the interface between the primary coating and the base iron, and the primary coating may be blown off and destroyed. As a result, a dotted base metal exposed portion having a size that can be discerned with the naked eye appears on the surface of the steel sheet. If this dotted base metal exposed portion is generated at a high number density over a wide range of the steel sheet surface, it becomes a serious defect in terms of insulating property and appearance quality. Since the methods for improving the adhesion of the primary coating described above do not necessarily suppress the punctate defects, there is a demand for a control technique for the morphology of the primary coating in which the punctate defects do not occur.
[0013]
Regarding the adhesion of the primary coating, various studies have been made on end face peeling in shearing and surface peeling in bending, but it is said that the optimum steel sheet and manufacturing method that strictly distinguishes these are presented. I can't say. Since the peeling behavior and mechanism due to shearing and bending and the generation of high-pressure gas are different, the adhesion that the primary coating does not peel off when subjected to stricter bending than before when used in the iron core manufacturing method that requires bending, In addition, it is necessary to suppress primary coating defects caused by gas generation from the steel sheet. When the annealing separator contains Y, La, Ce, Sr, Ca, and Ba to form a primary coating containing Y, La, Ce, Sr, Ca, and Ba, the primary coating adheres to shearing. Even if there is no problem, if the primary film adhesion to bending is insufficient, or the primary film of the base steel sheet is destroyed by the gas generated from the steel sheet during finish annealing, defects occur in which the surface of the steel sheet is exposed in dots. There are issues such as cases. Therefore, as a highly reliable electrical steel sheet with no problem in insulation and appearance, it has primary film adhesion to bending (hereinafter, simply referred to as "coating adhesion"), and defects such as the base material being exposed in dots. Less material is desired.
[0014]
An object of the present invention is a grain-oriented electrical steel sheet having excellent magnetic properties and adhesion of a primary coating to a base steel sheet and having few defects in which the base material is exposed in dots, as well as a finish annealing steel sheet, an annealing separator, and a direction. It is an object of the present invention to provide a method for manufacturing a grain-oriented electrical steel sheet and a method for manufacturing a steel sheet for finish annealing.
Means to solve problems
[0015]
The present invention controls and defines the characteristics of 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.
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.
In this specification, the structure of the interface is defined by the morphological characteristics of the primary coating observed from the base steel plate side. Details will be described later together with the measurement method.
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".
[0016]
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.
[0017]
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.
[0018]
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) in the primary coating preferably has a high content of Mg 2SiO 4 having a small coefficient of linear expansion, and the surface oxide layer (1) should be thick. desirable.
[0019]
Based on the above general recognition, the present inventors have the magnetic properties of grain-oriented electrical steel sheets containing magnetic property improving elements, and annealing containing Y, La, Ce compounds and Ca, Sr, Ba compounds. The adhesion of the primary coating formed by using the separating agent was investigated and examined. As a result, the present inventors obtained the following findings.
Here, in the following description, one or more elements selected from the group consisting of Y, La, and Ce are collectively selected from the group consisting of "Y group elements", Ca, Sr, and Ba. Elements may be collectively referred to as "Ca group elements".
[0020]
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, if a large amount of the Y group element and the Ca group element are added at the same time in order to improve the film adhesion to the bending process, iron loss and magnetic flux density may decrease.
Further, even if the surface area of ​​the embedded oxide layer (2) is increased in order to control the morphology of the primary coating and improve the adhesion to the coating, the primary coating is blown off by the gas generated from the steel sheet during finish annealing. This may result in defects that expose the base metal in dots.
Hereinafter, when the term "adhesion" is simply used except where the film adhesion to shearing and the film adhesion to bending are clearly distinguished, the intention includes the film adhesion to shearing and the film adhesion to bending. May be used as.
In addition, when the term "dotted defects" is simply used thereafter, the primary coating may be blown off by the gas generated from the steel sheet during finish annealing, and the base steel sheet may be intentionally used as a defect exposed in dots.
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.
[0021]
When the annealing separator contains Y group elements, the embedded oxide layer (2) becomes thick. This improves the film adhesion to shearing.
Further, when the Ca group element is contained in the annealing separator, the number density of the embedded oxide layer (2) of the formed primary film increases, and the film adhesion to shearing is increased. Improves. Further, as the total content of the Ca group elements specified below in the primary film, the total content of the Ca group elements contained as impurities in the MgO raw material powder and the compound of the Ca group elements contained outside the MgO raw material powder are derived. When the content of the above is set to an appropriate ratio, the film adhesion to bending is improved, deterioration of magnetic properties is suppressed, and punctate defects are also suppressed. At this time, in the primary coating, the thickness of the surface oxide layer (1) becomes uniform, and the amount of Mg 2SiO 4 phase increases. Further, the fitted oxide layer (2) becomes longer not only in the plate thickness direction but also in the longitudinal width direction. To improve the film adhesion to bending, the thickness of the surface oxide layer (1) becomes uniform, and local stress concentration in the region where the surface oxide layer (1) is thin during bending. 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). In addition, the suppression of punctate defects not only increases the area of ​​the interface of the inlaid oxide layer (2), which is responsible for adhesion, but also increases the morphology of the oxide and creates a structure with many gas diffusion paths. It is considered that the cause is that the gas permeability of the embedded oxide layer (2) is improved.
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.
Since the interface between the base steel plate and the primary coating has a complicated three-dimensional shape with irregularities as shown in FIG. 1, an attempt was made to define the structural characteristics of the interface having this three-dimensional shape. The regulation should essentially quantify the "three-dimensional structure", but it was difficult because it was three-dimensional and had a 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".
[0022]
The features of the present invention obtained from these findings are as follows.
That is, in the case of forming a primary film containing Mg2 element and Ca group element by using an annealing separator containing MgO as the main element and Y group element and Ca group element as the main component. If the primary coating and the interface between the primary coating and the base steel plate satisfy the characteristics shown in the following (1) to (8), the forms of the embedded oxide layer (2) and the surface oxide layer (1) are appropriate. It is 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: 0.015 to 0.150 / 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) ≧ 0.30,
(3) Distance H5: 0.4 to 4.0 μm, obtained by subtracting H0 from the average height in the plate thickness direction in the region that is the embedded oxide layer region and the Al-concentrated region.
(4) (Total peripheral length L5 of the region that is the embedded oxide layer region and the Al-concentrated region) / (observation area S0): 0.020 to 0.500 μm / μm 2,
(5) (Area S1 of the embedded oxide layer region) / (Observation area S0) ≧ 0.15,
(6) Total content of Y group elements: 0.1 to 6.0% by mass,
(7) Total content of Ca group elements: 0.1 to 6.0% by mass,
(8) Number density of Ca group concentrated region D4: 0.005 to 2.000 / μm 2.
[0023]
Further, the finish annealing steel sheet for manufacturing the above-mentioned grain-oriented electrical steel sheet satisfies the following condition (9).
(9) Number density of particles containing Ca group elements in the Ca group element enrichment region of the quenching separator layer D42: 0.005 to 1.400 particles / μm 3.
[0024]
The primary coating and the annealing separator capable of forming the annealing separator layer satisfy the following conditions (10) to (17).
(10) (0.00562 [Y] +0.00360 [La] +0.00712 [Ce]) /0.0412 [Mg] x 100 (%): 0.20 to 1.60%,
(11) (1.40 [Ca] +1.18Sr + 1.12Ba) /1.66 [Mg] x 100: 0.20 to 1.80%,
(12) (0.0249 [Ca'] + 0.0114 [Sr'] + 0.0073 [Ba']) / 0.0412 [Mg'] x 100: 0.010 to 0.080%,
(13) (12) (10) / (11): 0.020 to 0.200,
(14) Average particle size of MgO R1: 0.1-2.8 μm,
(15) Average particle size R2 of particles containing Ca group elements in the Ca group element enrichment region: 0.2 to 3.0 μm,
(16) (Average particle size R2) / (Average particle size R1): 0.5 to 3.0.
[0025]
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 0.20%, 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. The surface of the primary coating of the steel plate is provided with a primary coating containing 2SiO 4 as a main component, and the direction from the primary coating side to the base steel plate side is positive in the plate thickness direction of the steel plate. Information on the unevenness is projected onto a surface parallel to the surface of the steel sheet and developed, and the median surface height of the primary coating on the base steel plate side is set to H0, and the primary existing on the base steel plate side from H0 + 0.2 μm. The coating is classified as a "fitted oxide layer region" and the primary coating existing on the primary coating side from H0 + 0.2 μm is classified as a "surface oxide layer region", and the information contained in the primary coating is parallel to the surface of the steel sheet. In the characteristic X-ray intensity and unevenness correlation distribution map developed by projecting onto a surface, the maximum value of the characteristic X-ray intensity of Al (aluminum) is specified, and Al of 20% or more of the maximum value of the characteristic X-ray intensity of the Al is specified. When the region where the characteristic X-ray intensity is obtained is defined as the "Al concentrated region", the primary coating film is formed.
(1) Number density of the Al-enriched region D3: 0.015 to 0.150 / 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) ≧ 0.30,
(3) Distance H5: 0.4 to 4.0 μm, obtained by subtracting H0 from the average value of the heights in the plate thickness direction of the inlaid oxide layer region and the Al-concentrated region.
(4) (Perimeter L5 of the region that is the embedded oxide layer region and the Al-concentrated region) / (observation area S0): 0.020 to 0.500 μm / μm 2,
(5) It is characterized in that the condition of (area S1 of the embedded oxide layer region) / (observation area S0) ≧ 0.15 is satisfied.
[0026]
Further, the directional electromagnetic steel plate contains 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 and unevenness correlation distribution map, the maximum value of the characteristic X-ray intensity of each of Ca, Sr, and Ba is specified, and the maximum value of the characteristic X-ray intensity of Ca is 20% or more. The region where the characteristic X-ray intensity of Ca is obtained, 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 is obtained, and the maximum value of the characteristic X-ray intensity of Ba. When combined with the region where the characteristic X-ray intensity of Ba of 20% or more can be obtained, it is referred to as the "Ca group element enrichment region".
(6) 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%,
(7) 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%, (8) The number density of the Ca group element enrichment region D4: 0.005 to 2.000 pieces / μm 2 is satisfied.
[0027]
Further, the grain steel for finish annealing for manufacturing the grain-oriented electrical steel sheet is C: 0.1% or less, Si: 2.5 to 4.5%, Mn: 0.02 to 0.20 in mass%. One or more elements selected from the group consisting of%, S and Se: 0.005-0.07% in total, sol. A base steel plate containing Al: 0.005 to 0.05% and N: 0.003 to 0.030% and having a chemical composition in which the balance is Fe and impurities, and on the surface of the base steel plate. In the characteristic X-ray intensity distribution map developed by projecting the information possessed by the annealing separation agent layer onto a plane parallel to the cross-sectional thickness direction, which is provided with an annealing separation agent layer containing MgO as a main component, which adheres to. A region where the maximum value of the characteristic X-ray intensity of each of Ca, Sr, and Ba is specified, and the characteristic X-ray intensity of Ca of 20% or more of the maximum value of the characteristic X-ray intensity of Ca is obtained, and the characteristic X of Sr. The region where the characteristic X-ray intensity of Sr of 20% or more of the maximum value of the line intensity is obtained and the region where the characteristic X-ray intensity of Ba of 20% or more of the maximum value of the characteristic X-ray intensity of Ba is obtained are combined. When the term "Ca group element enrichment region" is used, the quenching separator layer is (9) the Ca, Sr in the Ca group element enrichment region existing in the region 0 to 3.0 μm from the surface of the base metal plate. , The number density of particles containing one or more elements selected from the group consisting of Ba: 0.005 to 1.400 / μm 3.
[0028]
The annealing separator according to the present invention is an annealing separator containing MgO as a main component, and is composed of one or more elements selected from the group consisting of Y, La and Ce, and the group consisting of Ca, Sr and Ba. The content of Mg, Y, La, Ce, Ca, Sr, Ba contained in the annealing separator with respect to the content of MgO contained in the annealing separator containing one or more selected elements. When the ratio (%) is [Mg], [Y], [La], [Ce], [Ca], [Sr], and [Ba], respectively.
(10) (0.00562 [Y] +0.00360 [La] +0.00714 [Ce]) /0.0412 [Mg] × 100 (%): 0.20 to 1.60 (%),
(11) (0.0249 [Ca] +0.0114 [Sr] +0.0073 [Ba]) /0.0412 [Mg] × 100 (%): 0.20 to 1.80 (%),
The ratio (%) of the content of Mg, Ca, Sr, and Ba contained in the MgO raw material powder to the content of MgO in the MgO raw material powder contained in the annealing separator. When [Mg'], [Ca'], [Sr'], [Ba'] are used,
(12) (0.0249 [Ca'] + 0.0114 [Sr'] + 0.0073 [Ba']) / 0.0412 [Mg] x 100 (%): 0.010 to 0.080 (%), Meet, and more
(13) The above (0.0249 [Ca'] + 0.0114 [Sr'] with respect to the above (0.0249 [Ca] +0.0114 [Sr] +0.0073 [Ba]) /0.0412 [Mg] × 100. The ratio of +0.0073 [Ba']) /0.0412 [Mg'] × 100 is 0.200 to 0.020.
(14) The average particle size of MgO R1: 0.1 to 2.8 μm,
(15) Average particle size R2 of particles containing one or more elements selected from the group consisting of Ca, Sr, and Ba: 0.2 to 3.0 μm,
(16) (The average particle size R2) / (The average particle size R1): 0.5 to 3.0,
It is characterized by satisfying.
[0029]
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 0.20%, S and Se in mass%. One or more elements selected from the group: 0.005-0.07% in total, sol. A process of hot-rolling a slab containing Al: 0.005 to 0.05% and N: 0.003 to 0.030% and the balance of Fe and impurities to produce a hot-rolled steel sheet. A process for producing a cold-rolled steel sheet by cold-rolling the hot-rolled steel sheet at a cold-rolling rate of 80% or more. A step of performing decarburization annealing on the cold-rolled steel sheet to manufacture a decarburized annealed plate, a step of applying an aqueous slurry to the surface of the decarburized annealed plate and drying, and the step of drying the aqueous slurry. It comprises a step of performing finish annealing on the dried steel plate, and the aqueous slurry is characterized by containing the above-mentioned annealing separator.
[0030]
The method for producing a steel sheet for finish annealing is a group consisting of C: 0.1% or less, Si: 2.5 to 4.5%, Mn: 0.02 to 0.20%, S and Se in mass%. One or more elements selected from: 0.005-0.07% in total, sol. A step of hot-rolling a slab containing Al: 0.005 to 0.05% and N: 0.003 to 0.030% and the balance being Fe and impurities to produce a hot-rolled steel sheet. A step of cold-rolling the 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 plate and drying it, and the aqueous slurry contains the above-mentioned annealing separator.
The invention's effect
[0031]
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. The method for manufacturing grain-oriented electrical steel sheets according to the present invention can produce the above-mentioned grain-oriented electrical steel sheets. The annealing separator according to the present invention is applied to the above-mentioned manufacturing method, whereby the grain-oriented electrical steel sheet of the present invention can be manufactured. The finish annealing steel sheet according to the present invention is for manufacturing the grain-oriented electrical steel sheet of the present invention. The method for manufacturing a finish annealing steel sheet according to the present invention can manufacture the above-mentioned finish annealing steel sheet.
A brief description of the drawing
[0032]
FIG. 1 is a schematic diagram of a 20 μm × 15 μm primary coating sample.
FIG. 2 is a diagram illustrating a Gaussian filter applied to height information data 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 an unevenness correlation distribution diagram.
Embodiment for carrying out the invention
[0033]
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 (unevenness, 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 features obtained on these projective planes can satisfactorily define the features of the present invention, and the present invention shall be described by the information of the primary film on these projective planes. Needless to say, does not lose the significance of the present invention.
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.
[0034]
Hereinafter, a method for manufacturing grain-oriented electrical steel sheets and grain-oriented electrical steel sheets according to the present invention, a shrinking separator used for manufacturing grain-oriented electrical steel sheets, a finish-eversion steel sheet for manufacturing grain-oriented electrical steel sheets, and a finish-eversion steel sheet for manufacturing grain-oriented electrical steel sheets. The manufacturing method will be described in detail. In the present specification,% with respect to the content of an element means mass% unless otherwise specified.
[0035]
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.
[0036]
[Base steel plate]
The chemical composition of the base steel sheet constituting the above-mentioned grain-oriented electrical steel sheet 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. As will be described in the manufacturing method described later, the base steel sheet is manufactured by cold rolling using a hot-rolled steel sheet having a chemical composition described later, and components lost during finish annealing are contained. Therefore, the chemical composition of the base steel sheet constituting the directional electromagnetic steel sheet and the chemical composition of the hot-rolled steel sheet are significantly different.
[0037]
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%.
[0038]
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 effect cannot be sufficiently obtained. 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%.
[0039]
Mn: 0.02 to 0.20%
Manganese (Mn) combines with S and Se described later 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 0.20%, secondary recrystallization may not occur and the magnetic properties of the steel may deteriorate. Therefore, the Mn content is 0.02 to 0.20%. 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 0.1%.
[0040]
One or more elements selected from the group consisting of S and Se: 0.005% or less in total
The sulfur (S) content 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 0.0001%, 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 selected from the group consisting of S and Se in the grain-oriented electrical steel sheet is 0.0001%.
[0041]
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.
[0042]
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 0.010%, the inhibitor remains excessively in the grain-oriented electrical steel sheet, so that the magnetic properties deteriorate. Therefore, the N content is 0.010% 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%.
[0043]
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.
[0044]

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 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.
[0045]
[Primary coating]
The characteristics of the primary coating structure 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 a "projective plane"). Understanding this measurement method is important for understanding the characteristics of the primary coating. Therefore, the measurement method will be described first.
[0046]

A directional electromagnetic steel sheet having a primary coating 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 coating 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 (80 C / cm 2) per 1 cm 2 of the steel sheet area. When separating the primary coating, a method of observing what remains on the tape side by attaching the primary coating to the adhesive surface of a commercially available metal tape or the like and then removing the base steel plate, or paraffin is used. There is a method of removing paraffin after embedding with.
Hereinafter, this separated 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".
[0047]
Next, observe the interface observation sample with various observation devices from the direction perpendicular to the original steel sheet surface (direction of the grain thickness 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.
[0048]
The observation surface of the interface observation sample is analyzed with a scanning confocal laser microscope (model number: VK9710, manufactured by KEYENCE) in a region of 20 μm × 15 μm or more, and the unevenness data of the interface on the projection plane is obtained. At this time, the scanning step is set to 0.1 μm or less. Smoothing with a Gaussian filter (FIG. 2) having a size of 3 × 3 is performed once on the obtained uneven data of 30,000 (200 × 150) or more. Furthermore, the uneven data after smoothing is automatically corrected for the quadric surface based on the center line in the width direction and the center line in the height direction, and this data is expanded on the projection plane to 200 pieces x 150. Obtain the final unevenness distribution map of the pieces.
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. A projection of FIG. 3 on a plane parallel to the surface of the steel sheet is a projection plane having height unevenness distribution information.
Further, in the above observation region, characteristic X-ray intensity analysis of Ca, Sr, Ba and Al is performed using SEM-EDS (model number: JSM-7900F, manufactured by JEOL Ltd.). At this time, the scanning step is set to 0.1 μm or less, and a characteristic X-ray intensity distribution map of 200 × 150 pixels on the projection plane is obtained. At this time, based on the resolution of the characteristic X-ray intensity distribution map, the region of 200 × 150 pixels or more overlaps with the unevenness distribution map. That is, for each pixel in the region of 200 × 150 pixels or more of the digital image of the characteristic X-ray intensity distribution map, the height data of the unevenness distribution map in the corresponding region corresponds to at least one point (preferably all points). To be able to. Hereinafter, this is referred to as a characteristic X-ray intensity and unevenness correlation distribution diagram, and a schematic diagram showing this is shown in FIG. A method for identifying the morphology of the coating using the information obtained from this figure will be described.
[0049]
From the characteristic X-ray intensity and the unevenness correlation distribution map obtained in this way, the regions A0 to A5 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.
[0050]
The region A0 is the entire observation region, that is, a region of at least 20 μm × 15 μm or more, and all the pixels of the characteristic X-ray and the unevenness correlation distribution diagram correspond to this region A0. Hereinafter, A0 may be described as an “observation area”.
[0051]
Region A1 and region A2 are classified based on the characteristic X-ray intensity and the unevenness correlation distribution map.
In the present invention, it is not possible to classify the primary coating into two regions in the thickness direction with reference to the position H0 in the thickness direction of the steel sheet, "fitted oxide layer (2)" and "surface oxide layer (1)". As mentioned above. Regions A1 and A2 are regions in which this classification is developed on the projection plane.
H0 is the median value of the height data of the characteristic X-ray intensity and the unevenness 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 is the “fitted oxide layer (2)”, and what is seen on the projection plane is the “fitted oxide layer region” A1. Similarly, the region having a height of less than H0 + 0.2 μm is the “surface oxide layer (1)”, and the “surface oxide layer region” A2 on the projection plane.
[0052]
Region A3 and region A4 are classified based on the characteristic X-ray intensity and the unevenness correlation distribution map.
In the characteristic X-ray intensity and unevenness correlation distribution diagram, the maximum value of the characteristic X-ray intensity of Al (aluminum) is specified, and the region where the intensity of 20% or more of the maximum value of the characteristic X-ray intensity of Al is obtained is A3. be. Hereinafter, the region A3 will be referred to as an “Al enriched region”.
Further, in the characteristic X-ray intensity and the unevenness 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 of 20% or more of the maximum value of the characteristic X-ray intensity of Ca is obtained. The 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 the characteristic X-ray intensity of Ba which is 20% or more of the maximum value of the characteristic X-ray intensity of Ba. The area including the area where is obtained is A4. 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, A4 will be referred to as a “Ca group element enrichment region”.
[0053]
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”.
[0054]
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 respective areas are 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 A3 and A4 regions be D3 and D4, respectively. In specifying the number density of the number of regions, the region in which the pixels are continuous vertically or horizontally in pixel units is regarded as one region, and the region consisting of four or more pixels is further specified to calculate the number. Since the area of ​​one pixel is the scanning step 0.1 μm (more specifically 0.092 μm) at the time of measurement 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 unevenness 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, which is a result. In addition, H5 has a value of 0.2 μm or more.
[0055]

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 there is a major feature in the Al distribution near the interface between the primary coating and the base steel sheet, and this feature is mainly the "fitted oxide layer (2)". First, the characteristics of the embedded oxide layer (2) will be described, and then the characteristics of the entire primary coating will be described.
The present invention is characterized in that D3: 0.015 to 0.150 / 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, among the Al-enriched regions, the peripheral length L5 of the region that is the fitted oxide layer region, that is, the region that is the fitted oxide layer region A1 and the Al (aluminum) concentrated region A3 (fitted Al region A5). The ratio to the observed area, L5 / S0, is in the range of 0.020 to 0.500 μm / μm 2. If this ratio is less than 0.02 μm / μm 2, the effect of improving the film adhesion to bending cannot be obtained. Further, if it exceeds 0.500 μm / μm 2, the iron loss characteristic is deteriorated. Here, the peripheral length L5 is the total peripheral length of the fitted Al region A5, and the peripheral length of the fitted Al region A5 is the peripheral length of continuous pixels forming one fitted Al region A5.
Further, the position H5 in the plate thickness direction of the fitted Al region 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, when it exceeds 4.0 μm, the inlaid oxide extends too much in the plate thickness direction, so that the peripheral length decreases, the gas release property is not improved, and punctate defects occur.
[0056]
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 having a strong tendency to form an oxide, 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, in the surface oxide formed by the reaction of the annealing separator, when a part of the surface oxide is replaced with MgAl 2O 4, Mg 2SiO 4 is reduced, the amount thereof decreases, the linear expansion coefficient increases, and the magnetic characteristics The thickness of the surface oxide layer (1) mainly composed of Mg 2SiO 4 becomes non-uniform. To avoid this, Al may be oxidized inside the steel sheet to prevent it from reaching the surface oxide layer (1). That is, the present invention has a structure in which an Al-based oxide is formed at the tip position of the inlaid oxide deeply penetrated into the mother steel sheet, thereby improving the magnetic properties and the film adhesion to the bending process. It is considered that both have been achieved.
The specified value indicating this is H5, and in the present invention, H5 is formed at a position separated from H0 by 0.4 μm or more, that is, the fitted Al region is 0.4 μm or more from H0 on the inner side of the steel sheet (tip side of the fitted oxide). It is considered that the above structure is achieved by setting the peripheral length L5 of the fitted Al region per observation area to 0.02 μm or more.
And the fact that such an inlaid Al region A5 is at the tip of the inlaid oxide also leads to the fact that D3 becomes a numerical value within an appropriate range. That is, if the number density of the fitted Al region A5 is small, D3 is low. Further, even if a situation occurs in which the density of the fitted Al region becomes excessively high temporarily, the distance between the adjacent fitted Al regions A5 is short. Therefore, as the primary coating grows, they coalesce, and finally D3 is unlikely to become an excessively high value.
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 (1), so that S5 / S3 is inevitably a high value. Become.
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 is used as an oxide. It is reasonable to think that it exists.
[0057]

In the primary coating of the present invention, the shape of the embedded oxide layer (2) cannot be said to have a remarkable external feature, but the above-mentioned characteristic Al distribution is that of the embedded oxide layer (2). Since the phenomenon in the tip region is utilized, 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. 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. Details will be described later, but in such a situation, it becomes difficult to form the above-mentioned characteristic Al distribution.
[0058]

The primary coating of the present invention contains forsterite (Mg 2SiO 4) as a main component. More specifically, the primary coating contains 50-95 mass% Mg 2SiO 4. The rest are generally known oxides such as MgAl 2O 4 and sulfides such as MnS.
[0059]
Further, in the primary coating of the present invention, the total amount of Y group elements is 0.1 to 6.00% by mass and the total amount of Ca group elements is 0.1 to 0.1 to the content of Mg 2SiO 4 in the primary coating. It is preferably contained in an amount of 6.00% by mass.
[0060]
Details will be described later, but in order to realize the above-mentioned oxidation status of Al, it is preferable to use an annealing separator containing a Y group element. 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 film is less than 0.1% by mass, it cannot be said that the Y group elements are sufficiently contained in the annealing separator, and the film adhesion to the bending process is not improved. If it exceeds 6.00% by mass, the thickness of the embedded oxide layer (2) becomes too thick, and the oxide hinders the movement of the domain wall during magnetization, so that the adverse effect on the magnetic properties becomes remarkable.
Similarly, in order to realize the above-mentioned oxidation state of Al, 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, it cannot be said that the content of Ca group elements in the annealing separator is sufficient, and the film adhesion in bending cannot be improved. If it exceeds 6.00% by mass, the number density of the embedded oxide layer (2) becomes too high and the adjacent embedded oxides are united and integrated, resulting in a decrease in the number density of the embedded oxides. Since the characteristic Al distribution cannot be obtained, the film adhesion in bending cannot be improved.
[0061]
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.
Furthermore, in the same manner, each of Ca, Ba, Sr and Y, La, Ce is quantitatively analyzed by the same method as described above, and the obtained content value (mass%) is calculated in the same manner as described above. 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 Y, La, and Ce was defined as "Y group element content".
[0062]
Further, in the primary coating of the present invention, it is preferable that the "number density of Ca group element enrichment region A4" D4 on the projection plane is 0.005 pieces / 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 A4 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 thought that there is. 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.
If D4 is less than 0.005 / 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 may not be obtained.
The upper limit is not set in particular, but if D4 is too high, the frequency of formation of the impregnated oxide particles formed in connection with this will be excessively high, and the adjacent impregnated oxides will coalesce and integrate with each other. As described above, it inhibits the formation of a typical Al distribution. Therefore, D4 ​​is preferably 2.000 pieces / μm 2 or less.
[0063]
[Production method]
An example of a method for manufacturing a grain-oriented electrical steel sheet according to the present invention will be described.
An example of a method for manufacturing a directional electromagnetic steel plate is a steelmaking process, a hot rolling process, a hot rolling plate annealing process, a cold rolling process, a decarburization annealing process, a finish annealing process, a flattening annealing process, and a film seizure. It is equipped with a process and a magnetic zone control process. 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. What is characteristic of the method of the present invention is the state of the steel sheet surface containing the annealing separator in the steel sheet before finish annealing for controlling the structure of the primary coating.
[0064]

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. Each element of the chemical composition of the slab is removed to some extent from the components in the steel in the finishing annealing step described later. In particular, S, Al, N and the like that function as inhibitors are largely removed. Therefore, the chemical composition of the slab described here is different from the chemical composition of the steel plate of the final product.
[0065]
C: 0.1% mass or less,
If the C content exceeds 0.1%, the time required for decarburization annealing becomes longer. In this case, the manufacturing cost is high and the productivity is also lowered. Therefore, the C content in the slab is 0.1% 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 lower limit of the C content in the slab is preferably 0.02% by mass, more preferably 0.04% by mass.
[0066]
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% by mass, and the more preferable upper limit is 3.8% by mass. The preferable lower limit of the Si content in the slab is 2.6%, and the more preferable lower limit is 2.8% by mass.
[0067]
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 0.05 to 0.20% by mass. The preferred upper limit of the Mn content in the slab is 0.13% by mass, and the more preferable upper limit is 0.10% by mass. The preferable lower limit of the Mn content in the slab is 0.03% by mass, and the more preferable lower limit is 0.04% by mass.
[0068]
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 selected from the group consisting of S and Se is 0.008% by mass, and more preferably 0.016% by mass. The preferred upper limit of the total content of one or more selected from the group consisting of S and Se is 0.060% by mass, more preferably 0.050% by mass.
[0069]
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.
[0070]
N: 0.0030-0.0300% 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 0.0030% by mass, the above effect cannot be obtained. On the other hand, if the N content in the slab exceeds 0.0300% 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 0.0030 to 0.0300% by mass. The preferred upper limit of the N content in the slab is 0.0200% by mass, more preferably 0.0150% by mass. The preferred lower limit of the N content in the slab is 0.0040% by mass, more preferably 0.0060% by mass.
[0071]
The balance of the chemical composition in the slab of the present invention consists of Fe and impurities. Here, impurities are industrial slabs. It means a substance that is mixed from ore as a raw material, scrap, or a production environment, etc., and is permitted as long as it does not adversely affect the slab of the present embodiment.
[0072]

Further, the slab according to the present invention may contain at least one selected from the group consisting of Cu, Sn and Sb in a total of 0.60% by mass or less instead of a part of Fe. All of these elements are arbitrary elements.
[0073]
One or more elements selected from the group consisting of Cu, Sn and Sb: 0 to 0.60% by mass in total
Copper (Cu), tin (Sn) and antimony (Sb) are all optional elements and may not be contained. When contained, 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 0.6% 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, Cu, Sn, and Sb are likely to remain as impurity elements after purification annealing. 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 0.6% 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.
[0074]
The slab according to the present invention may further contain at least one selected from the group consisting of Bi, Te and Pb in a total of 0.030% by mass or less instead of a part of Fe. All of these elements are arbitrary elements.
[0075]
One or more elements selected from the group consisting of Bi, Te and Pb: 0 to 0.030% 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 selected from the group consisting of Bi, Te and Pb for this purpose is 0.0005%, more preferably 0.001% 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 0.005% by mass or less in order to secure the film adhesion. Since the effect of the present invention improves the film adhesion by changing the structure of the embedded oxide, it is also 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 an excessive amount, the decrease in adhesion cannot be avoided even with the effect of the present invention, so the upper limit is 0.030% by mass. The preferred upper limit is 0.020% and the more preferred upper limit is 0.015% by mass.
[0076]

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. The conditions for hot-rolled sheet annealing are, for example, 900 to 1100 ° C. for 3 to 5 minutes.
[0077]

In the cold-rolled process, cold-rolled steel sheets are cold-rolled to manufacture cold-rolled steel sheets.
[0078]
Cold-rolled the prepared hot-rolled steel sheet to manufacture a cold-rolled steel sheet, which is the 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).
[0079]
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
[0080] [0080]
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.
[0081]

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 decarburization annealing, primary recrystallization is further developed in the steel sheet structure, and the processing strain introduced by the cold rolling step 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. The annealing temperature in the decarburization annealing step is well known, for example, 750 to 950 ° C. The holding time at the annealing temperature is, for example, 1 to 5 minutes.
[0082]

In the present invention, the "annealing separator" refers to a substance formed to impart an anti-seizure function during finish annealing to the surface of the above-mentioned decarburized annealing plate for performing finish annealing. Further, the layer of the annealing separator formed on the surface of the decarburized annealing plate is called an "annealing separator layer".
In this step, an aqueous slurry containing a compound or the like constituting the annealing separator is prepared. The aqueous slurry is prepared by adding an element constituting the annealing separator described later as a compound or the like to pure water and stirring the slurry. 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. (no change in crystal structure such as recrystallization occurs). What remains on the surface of the steel sheet at this point is the annealing separator in the present invention, and the state in which the annealing separator adheres to the surface of the steel sheet before finish annealing is called an annealing separator layer.
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.
[0083]

After drying the annealing separator, perform finish annealing. In the finish annealing, the annealing temperature is set to 1150 to 1250 ° C., and the base steel sheet (cold-rolled steel sheet) is heated evenly. 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)".
[0084]
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. At this time, by applying the annealing separator described later, the interface structure between the base steel sheet and the primary coating material satisfies the provisions of the present invention, and the coating adhesion is improved.
[0085]
By the decarburization annealing step and the finish annealing step, each element of the chemical composition of the hot-rolled steel sheet is removed from the components in the steel to some extent. In particular, S, Al, N and the like that function as inhibitors are largely removed. Therefore, the element content in the chemical composition of the base steel sheet of the grain-oriented electrical steel sheet is lower than that of the chemical composition of the hot-rolled steel sheet as described above. If the above-mentioned manufacturing method is carried out using the hot-rolled steel sheet having the above-mentioned chemical composition, a grain-oriented electrical steel sheet having the above-mentioned base material steel sheet having the above-mentioned chemical composition can be manufactured.
[0086]

In an example of the method for manufacturing a grain-oriented electrical steel sheet according to the present invention, an insulating film forming step may be further carried out after the finish annealing step. In the insulating film forming step, an insulating coating agent mainly composed of colloidal silica and phosphate is applied to the surface of the directional electromagnetic steel plate after the temperature of the finish annealing is lowered, and then baking is performed. As a result, an insulating film, which is a tension film, is formed on the primary film.
[0087]

The directional electromagnetic steel sheet according to the present invention may further undergo a well-known magnetic domain subdivision treatment step after cold rolling, decarburization annealing, finish annealing step, insulation film forming step, and the like. In the magnetic domain subdivision processing step, the surface of the grain-oriented electrical steel sheet is irradiated with a laser beam having a magnetic domain subdivision effect, or a groove is formed on the surface. In this case, a grain-oriented electrical steel sheet having further excellent magnetic characteristics can be manufactured.
[0088]
[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.
[0089]

The annealing separator represents the ratio of each content of Y, La, Ce, and Mg to the content of MgO in the annealing separator in%, and is expressed as [Y], [La], [Ce], and [Mg]. do. The annealing separator uses these elements as the following formula:
(0.00562 [Y] +0.00360 [La] +0.00712 [Ce]) /0.0412 [Mg] x 100 (%): 0.20 to 1.60 (%)
Meet.
Here, each coefficient of the above formula contains the Y, La, Ce, and Mg atoms present in the quenching separator as the respective stable oxides Y 2O 3, La 2O 3, Ce 2O 3, and MgO. It is a coefficient for finding the abundance ratio, and is calculated as follows.
Y coefficient: 1 / Y atomic weight / 2 = 1 / 88.9 / 2 = 0.00562
La coefficient: 1 / La atomic weight / 2 = 1 / 138.9 / 2 = 0.00360
Ce coefficient: 1 / Ce atomic weight = 1 / 140.1 = 0.00714
Coefficient of Mg: 1 / Mg atomic weight = 1 / 24.3 = 0.0412
[0090]
(0.00562 [Y] +0.00360 [La] +0.00714 [Ce]) /0.0412 [Mg] × 100 is the total of the Y group elements in the annealing separator converted as stable oxides of each element. It is a ratio (percentage) between the content obtained and MgO, which is a main constituent element 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. In the following, (0.00562 [Y] +0.00360 [La] +0.00714 [Ce]) /0.0412 [Mg] × 100 will be described as CY.
[0091]
It should be noted that the Y group element needs to be contained as a compound containing oxygen or a compound that is oxidized during finish annealing and changes to a compound containing oxygen.
The compounds of the Y group elements are, for example, oxides, or hydroxides, carbonates, sulfates, etc., which are partially or wholly converted into oxides by the baking treatment (drying treatment) and finish baking treatment described later.
[0092]
The annealing separator to which the compound of the Y group element is added develops the roots of the primary film due to the oxygen release effect described later. As a result, the adhesion of the primary coating to the base steel sheet is improved. If the CY is less than 0.20%, the above effect cannot be sufficiently obtained. On the other hand, if the CY exceeds 1.60%, the roots of the primary coating are excessively developed and the magnetic properties are deteriorated. Therefore, CY is 0.20 to 1.60%. The preferred lower limit of CY is 0.40%, more preferably 0.50%. The preferred upper limit is 1.40%, more preferably 1.30%.
[0093] The reason why the adhesion can be improved by controlling the content of the Y group element is not completely clear, but it is considered as follows. That is, the oxygen-containing Y group elements release oxygen during the finish annealing, maintain the oxygen partial pressure between the steel plates of the coil during the finish annealing, and develop the embedded oxide layer (2) of the primary coating. Hereinafter, the relationship between oxygen release and the development of the inlaid oxide layer (2) will be described in detail.
The inlaid oxide layer is composed of Mg 2SiO 4 formed by the reaction between MgO in the annealing separator and SiO 2 inside the base steel sheet. That is, in order to obtain a fitting structure having severe unevenness, it is necessary that SiO 2, which is an oxide in the steel sheet, originally has severe unevenness. Since SiO 2 having such an interface has high interfacial energy, it is unstable during finish annealing performed at a high temperature. Therefore, during the finish annealing, the SiO 2 formed inside the base steel sheet is once decomposed and diffused as Si and O in the base steel sheet to be flattened. Furthermore, since the finish annealing is carried out in a hydrogen atmosphere, the oxygen supply to the base steel sheet is small. In addition, the formation of an Al-based oxide, which is a more stable oxide than SiO 2, reduces oxygen in the base steel sheet, and SiO 2 becomes more and more unstable. As a result, the decomposition of SiO 2 existing inside the base steel sheet becomes more remarkable than the depth formed by the Al-based oxide, and SiO 2 becomes more and more flattened through diffusion after decomposition, and the inlaid oxide layer of the primary coating ( 2) is also flattened.
Here, the Y group elements containing oxygen contained in the annealing separator release oxygen, so that the oxygen partial pressure between the steel plates of the coil during finish annealing increases. Due to the increase in oxygen partial pressure between the steel plates, oxygen is supplied to the base steel plate, and the flattening of the internally oxidized SiO 2 is delayed. Delaying the flattening of SiO 2 during finish annealing means that Mg 2SiO 4 having severe irregularities is formed. Mg 2SiO 4 is more stable than SiO 2, and the morphological change due to subsequent finish annealing is small. As a result, the unevenness of the inlaid oxide layer (2) of the primary film becomes severe.
[0094]

In the present invention, the total content of Ca group elements contained in the annealing separator, the total content of Ca group elements contained as impurities in the MgO raw material powder contained in the annealing separator, and the ratio of these contents are specified. do.
The annealing separator represents the ratio of each content of Ca, Sr, Ba and Mg to the content of MgO contained in the annealing separator in%, and represents [Ca], [Sr], [Ba], [Mg]. ]. The annealing separator uses these elements as the following formula:
(0.0249 [Ca] +0.0114 [Sr] +0.0073 [Ba]) /0.0412 [Mg] x 100 (%) = 0.20 to 1.80 (%) is satisfied.
Further, the annealing separator has Ca, Sr, Ba, and Mg contents contained in the MgO raw material powder as opposed to the MgO content in the MgO raw material powder contained in the annealing separating agent [Ca'], [Sr']. Let it be [Ba'] and [Mg']. The annealing separator uses these elements as the following formula:
(0.0249 [Ca'] + 0.0114 [Sr'] + 0.0073 [Ba']) / 0.0412 [Mg'] × 100 (%): 0.010 to 0.080 (%) is satisfied.
Further, the total content of Ca group elements contained in the quenching separator and the total content of Ca group elements in the MgO raw material powder contained in the annealing separator are (Ca of the MgO raw material powder contained in the annealing separator). The relationship of (total content of group elements) / (total content of Ca group elements contained in the quenching separator): 0.020 to 0.200 is satisfied.
Here, each coefficient of the above formula contains Ca, Ba, Sr, and Mg atoms present in the quenching separator or the MgO raw material powder as the respective stable oxides CaO, BaO, SrO, and MgO. It can be calculated as follows with the coefficient calculated to compare the substance amount ratios.
Ca coefficient: 1 / Ca atomic weight = 1 / 40.1 = 0.0249
Coefficient of Sr: 1 / Sr atomic weight = 1 / 87.6 = 0.0114
Coefficient of Ba: 1 / Ba atomic weight = 1 / 137.3 = 0.0073
Coefficient of Mg: 1 / Mg atomic weight = 1 / 24.3 = 0.0412
[0095]
(0.0249 [Ca] +0.0114 [Sr] +0.0073 [Ba]) /0.0412 [Mg] × 100 (%) uses Ca group elements in the annealing separator as stable oxides of each element. It is the ratio (percentage) of the converted total content and MgO, which is the main constituent element 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. In the following, the total abundance ratio of Ca group elements contained in the quenching separator (0.0249 [Ca] +0.0114 [Sr] +0.0073 [Ba]) /0.0412 [Mg] x 100 (%) is CC. , Total abundance ratio of Ca group elements contained as impurities in MgO raw material powder contained in the quenching separator (0.0249 [Ca'] + 0.0114 [Sr'] + 0.0073 [Ba']) / 0. 0412 [Mg'] x 100 (%) is described as CC'.
The Ca group elements are, for example, oxides, or hydroxides, carbonates, sulfates, etc., which are partially or wholly converted into oxides by the baking treatment (drying treatment) and finish annealing treatment described later.
[0096]
The Ca group elements diffuse in the primary coating during finish annealing, reach the interface on the mother steel plate side of the primary coating, and react with SiO 2 existing in the surface region of the mother steel plate, which is the starting point for forming the primary coating, to form an inlaid oxide. I think it will make it easier to form. That is, it is considered that the number density of the number of embedded oxide regions is increased.
The reason for showing such an effect is not clear, but it is thought to be as follows.
The base steel sheet is oxidized by decarburization annealing, and SiO 2 is formed in the surface layer region thereof. The phenomenon that the embedded oxide, which is a part of the primary coating mainly composed of Mg 2SiO 4, grows inside the base steel sheet of the embedded oxide, that is, the thickness of the embedded oxide layer (2) increases, is a major element of the annealing separator. This is the phenomenon itself in which Mg contained as is diffused toward the inner side of the base steel plate of SiO 2 and the Mg 2SiO 4 is formed there. At the same time, in the Al-concentrated region characterized by the present invention, it is considered that Al diffused from the inside of the steel sheet reacts with Mg 2SiO 4 and is concentrated in that region. That is, the more Mg 2SiO 4 is formed on the inner side of the mother steel sheet, the more the Al-concentrated region is also formed on the inner side of the mother steel sheet.
The Ca group element has the same function as Mg and forms a composite oxide of the oxide of the Ca group element and the oxide of Si. When this composite oxide reacts with Al, it is considered that Al is concentrated in the reaction region. Comparing the diffusion rates of Mg and Ca group elements in SiO 2, the Ca group elements are faster, and when the Ca group elements are present in the quenching separator, the composite oxide of SiO 2 and Ca group elements becomes It is 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 increases the speed at which the embedded oxide advances inside the steel plate. In this way, the annealing separator containing the Ca group element not only increases the thickness of the inlaid oxide layer (2), but also increases the Al concentration position in it, that is, H5. Become. Therefore, it is necessary that the Ca group element becomes a compound containing an oxide or oxygen already before the preparation of the aqueous slurry or after the drying step and is dispersed in the annealing separator.
Further, when the Ca group element is contained as an impurity in the MgO raw material powder, the reactivity with SiO 2 is enhanced as the raw material powder MgO, and it functions as a relatively stable Ca group element source even in the latter stage of annealing, and is contained in the primary coating. The primary film oxide can be stabilized by supplying a Ca group element source to the. In this case, the unstable SiO 2 can be replaced with a stable oxide film such as CaMgSi 2O 6 at an early stage, and CaMgSi 2O 6 is stabilized as a Ca group element source that does not limit the supply path of Mg. As a result, the morphology can be maintained until CaMgSi 2O 6 is replaced with Mg 2SiO 4. However, when the impurity Ca group element in MgO becomes excessively large, the amount of Ca supplied becomes excessive with respect to Mg, and Mg for forming CaMgSi 2O 6 necessary for maintaining the morphology of the primary coating in a complicated manner is formed. The supply of group elements is reduced with respect to Ca group elements, and the formation of more stable MgSi 2O4 is delayed. The primary coating morphology cannot be maintained. As a result, punctate defects increase. Similarly, when the impurity Ca group element in MgO is excessively small, even if the Ca group element-containing additive added to the outside of the MgO raw material powder supplies a sufficient Ca group element, the supply of Mg is relatively relative. The decrease delays the formation of more stable MgSi 2O 4, and increases punctate defects for the same reason. The total abundance ratio of Ca group elements in the annealing separator that can balance the supply amounts of Mg and Ca is CC = 0.20 to 1.80, CC'= 0.010 to 0.080, and CC'/ CC. = 0.020 to 0.200.
[0097]
If the CC is less than 0.20, the above effect cannot be sufficiently obtained. On the other hand, if the CC exceeds 1.80, the inlaid oxide layer may become excessively thick and the magnetic properties may deteriorate. When the CC is 0.20 to 1.80, it is possible to improve the adhesion of the primary coating to the base steel sheet while suppressing the deterioration of the magnetic characteristics.
Further, when CC'is less than 0.010 or more than 0.080, or CC'/ CC is less than 0.020 or more than 0.200, punctate defects occur. Therefore, the range of CC'of the present invention is 0.010 to 0.080, and the range of CC'/ CC is 0.020 to 0.200.
[0098]

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 contained in the quenching separator is expressed in% and is referred to as [Ti], [Zr], [Hf], and [Mg]. The annealing separator uses these elements as the following formula:
(0.0209 [Ti] +0.0110 [Zr] +0.0056 [Hf]) /0.0412 [Mg] x 100 (%) ≤ 5.0 (%)
Meet.
Here, it is considered that each coefficient of the above formula contains Ti, Zr, and Hf existing in the quenching separator as the respective stable oxides, TIO 2, ZrO 2, HfO 2, and MgO, respectively. It can be calculated as follows with the coefficient calculated by the existence ratio.
Ti coefficient: 1 / Ti atomic weight = 1 / 47.9 = 0.0209
Zr coefficient: 1 / Zr atomic weight = 1 / 91.2 = 0.0110
Coefficient of Hf: 1 / Hf atomic weight = 1 / 178.5 = 0.0056
Coefficient of Mg: 1 / Mg atomic weight = 1 / 24.3 = 0.0412
[0099]
(0.0209 [Ti] +0.0110 [Zr] +0.0056 [Hf]) /0.0412 [Mg] × 100 (%) uses the Ti group elements in the quenching separator as stable oxides of each element. It is the ratio (percentage) of the converted total content and MgO, which is the main constituent element in the quenching separator. In other words, it can be said to be an index showing the magnitude of the influence of Ti group elements on Mg in oxides. In the following, (0.0209 [Ti] +0.0110 [Zr] +0.0056 [Hf]) /0.0412 [Mg] × 100 (%) will be described as CT. The Ti group elements can be contained as simple substances, alloys, or compounds. The compounds are, for example, sulfates, carbonates, hydroxides and the like.
[0100]
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 5.0, the effect is saturated, so 5.0 is set as the upper limit.
[0101]
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.
[0102]
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.
[0103]

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.
[0104]
In the annealing separator of the present invention, the average particle size of MgO is 0.1 to 2.8 μm. Hereinafter, the average particle size of MgO is described as R1.
If R1 is less than 0.1 μm, MgO is too active, seizure occurs between the coil plates after finish annealing, and the characteristics as an annealing separator deteriorate.
If R1 exceeds 2.8 μm, MgO is too inactive and the formation of the primary film is delayed. Therefore, R1 is 0.1 to 2.8 μm.
R1 and R2 are measured as follows. That is, the raw material powder is measured by a laser diffraction / scattering method based on JIS Z8825 (2013) using a laser diffraction / scattering type particle size distribution measuring device to obtain a volume-based 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 of each element is obtained.
[0105]
The annealing separator of the present invention has an average particle size of particles containing Ca group elements of 0.2 to 3.0 μm. Hereinafter, the average particle size of the particles containing the Ca group element is described as R2.
If R2 is less than 0.2 μm, Ca is too active, and the amount of Ca group elements supplied to the primary film being formed becomes too large with respect to the amount of Mg supplied. Therefore, when the reaction between Mg and Si is delayed, the formation of Mg 2SiO 4 is rather delayed, and the adhesion of the primary film is deteriorated.
When R2 exceeds 3.0 μm, the formation of Mg 2SiO 4 is delayed due to the loss of contact between MgO and SiO 2, and the adhesion of the primary coating deteriorates.
The measurement method of R2 will be described later.
[0106]
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 a representative particle of the entire measurement target in the particle size distribution. For example, if the abundance ratio of coarse particles having a very low abundance frequency changes slightly, the average particle size obtained is characterized by a large variation because the ratio of the coarse particles to the whole by weight is large.
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 controlled by the particle size of the particles having a high frequency of existence as described later, and the provision of the invention needs to be based on the average particle size based on the number of particles, not the weight.
[0107]
Further, in the annealing separator of the present invention, the ratio of R2 to R1, that is, R2 / R1 is in the range of 0.5 to 3.0.
When R2 / R1 is less than 0.5, the area ratio (S1 / S0) of the embedded oxide layer of the formed primary film decreases, and the film adhesion deteriorates. It is preferably 0.6 or more, more preferably 0.8 or more.
On the other hand, when R2 / R1 exceeds 3.0, the area ratio (S1 / S0) of the embedded oxide of the formed primary film decreases, and the film adhesion deteriorates. It is preferably 2.6 or less, more preferably 2.2 or less.
[0108]
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.
In general, 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 becomes less than 0.5, 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. .. If the formation of the primary film by finish annealing progresses in this situation, the supply of Mg is delayed in the region where only the Ca group elements are in contact with the base steel sheet, so that the formation of the primary film is delayed and the film adhesion becomes inferior. ..
Similarly, when R2 / R1 exceeds 3.0, the dispersion of Ca group elements becomes sparse with respect to MgO, so that the supply of Ca is delayed and the film adhesion of the formed primary film becomes inferior.
This means that a compound of Ca group elements exists between MgO and the steel sheet, which hinders the supply of Mg to the base steel sheet. That is, the region where MgO is not in contact with the base steel sheet is simply a void if the Ca group element compound is not relatively fine, but the base material is that the Ca group element compound is relatively fine. It means that it changes to a region that hinders the supply of Mg to the steel sheet. As a result, there is a significant difference in the supply of Mg to the base steel sheet in the region where MgO is in contact with the base steel sheet and in the region where it is not in contact with the base steel sheet, and the development of the primary coating becomes non-uniform. Therefore, the number density of the inlaid oxide becomes excessive, which becomes a factor of impairing the magnetic properties.
Similarly, even if a Ca group element having an excessively large particle size is added with respect to the particle size of MgO, the range in which the Ca group element can be supplied decreases. Therefore, in the end, the supply of the Ca group element is biased and excessive. The number density of the roots of the primary coating becomes overcrowded at the place supplied to.
On the other hand, if R2 / R1 is in an appropriate range, the number density of the Ca group element compounds dispersed in the quenching separator layer near the steel plate increases, so that the Ca group element compounds are not simply refined and added in large quantities. The supply of Ca, Sr, and Ba to the base steel plate becomes uniform, and as a result, the number density of the embedded oxide can be made uniform.
[0109]
[Annealed separator layer]
The present invention defines the structure of the annealing separator layer in a state of being attached to the surface of the steel sheet immediately before the finish annealing after the above-mentioned annealing separator layer forming step.
In the annealing separator layer of the present invention, the number density of particles containing Ca group elements in the Ca group concentrated region existing in the region 0 to 3.0 μm from the surface of the base steel plate is 0.003 to 1.400 particles /. It is μm 2. In the following, this "number density of particles containing Ca group elements in the Ca group enrichment region" will be referred to as D42. Controlling D42 within the above range improves the adhesion of the primary coating after finish annealing.
[0110]
When D42 is in the above range, the reason why the adhesion of the primary coating is improved is not completely clear, but it is considered as follows. The Ca group elements contained in the annealing separator diffuse in the primary coating formed during finish annealing toward the base steel plate side, and the base metal plate side of the primary coating, that is, the base metal side at the tip of the embedded oxide. As mentioned above, it is considered that it forms a composite oxide with Al supplied from the above and acts to keep Al at the tip of the inlaid oxide. In order to make this effect even more remarkable, the position of the Ca group element in the annealing separator layer is important, and the Ca group element is located on the base steel plate side, that is, in the region of 0 to 3.0 μm from the surface of the base steel plate. It is convenient to have a enriched area. Also, as mentioned above, the contact with the base steel sheet should not have a local bias, and the appropriate elemental dispersion state in the annealing separator for this purpose is the Ca group concentration region of the primary film to be formed. It is considered to correlate with the number density.
[0111]
D42 can be obtained by the following method.
The cross section obtained by CP processing the annealing separator layer on the surface of the finished annealed steel sheet after drying together with the finished annealed steel sheet is analyzed by EDS-SEM to obtain the characteristic X-ray intensity distribution of Ca group elements. That is, the obtained characteristic X-ray intensity distribution map is a distribution map developed by projecting the information possessed by the annealing separator onto a plane parallel to the cross section of the finishing annealing steel sheet in the plate thickness direction. In the characteristic X-ray intensity distribution map of Ca group elements, the boundary line between the steel plate surface and the annealing separator layer should be as parallel as possible to the upper and lower pieces of the observation area, and the annealing separator layer should be outside from the lower end of the observation field. Acquire with a field of view that does not protrude. Hereinafter, the direction orthogonal to the observation width direction and the observation width direction of the steel sheet surface and the annealing separator layer is referred to as an observation height direction. The scanning step of the characteristic X-ray intensity distribution map shall be the same in the observation width direction and the observation height direction, and the length shall be 0.1 μ or less. Further, the observation width direction is at least 20 μm or more in length. That is, the characteristic X-ray intensity distribution map is decomposed into at least 200 pixels in the observation width direction. Here, in the characteristic X-ray intensity distribution of the obtained Ca group elements, the characteristic X-ray intensity of each 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 line intensity can be obtained, a region where Sr characteristic X-ray intensity of 20% or more of the maximum value of Sr characteristic X-ray intensity can be obtained, and Ba of 20% or more of the maximum value of Ba characteristic X-ray intensity. Together with the region where the characteristic X-ray intensity can be obtained, it is referred to as the "Ca group element enriched region in the annealed separation layer". Further, a region in which each pixel of the Ca group element enrichment region is continuous in the vertical and horizontal directions in pixel units is regarded as one region, and a region composed of four or more pixels is determined to be a particle. Further, the coordinates of the center of gravity of each Ca group element enrichment region in the observation region are obtained by image analysis. Then, the number N1 of the particles having the center of gravity at a height of 3 μm in the plate thickness direction from the surface of the base steel plate is counted. The average value R2 of the equivalent circle diameter (√ ((area of ​​1 pixel) × (number of pixels of continuum) × 4 / π)) of the particles containing the Ca group element in the Ca group element enrichment region is calculated. The obtained N1 and the R2 obtained as described above, the length of the observation region, the length of the observation region in the observation width direction (the length of the observation region in the direction orthogonal to the plate thickness direction in the above cross section (width of the steel plate for finish annealing). From the length of the observation region in the direction)) Lμm, D42 = N1 / (3 × L × R2) (pieces / μm 3) can be obtained.
[0112]
The average particle size (for example, R1) of the compound dispersed in the quenching separator layer is substantially the same as the average particle size obtained from the particle size distribution of the elemental raw material powder added when preparing as an aqueous slurry. I know. Therefore, the average particle size of each compound can be obtained from the average particle size of the raw material powder by using the same method as the calculation method of R1. It is not necessary to limit the method of controlling the diameter of the compound particles containing each element in the raw material powder to a specific range, and it is possible to produce a powder having a desired particle size distribution by preparing firing conditions and classifying. It is not difficult for a person who manufactures raw material powder.
[0113]
By using such Ca group compound powder and MgO powder as raw materials for the aqueous slurry, the number density of the Ca group concentrated region can be appropriately adjusted in the region of 0 to 3.0 μm from the surface of the base steel sheet in the quenching separator layer. Can be controlled to.
Example
[0114]
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 applied to a steel sheet before finish annealing and a primary film formed thereby, which play 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.
[0115]
[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. A slab was manufactured by a continuous casting method using the manufactured molten steel.
[0116]
[table 1]

[0117]
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.
[0118]
The obtained hot-rolled steel sheet was annealed, and then the hot-rolled steel sheet was pickled. Annealing of hot-rolled plates was carried out at 1100 ° C. for 5 minutes.
[0119]
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 It is 90.4%.
[0120]
Primary recrystallization annealing was performed on the cold-rolled steel sheet, which also served as decarburization annealing. The annealing temperature in the primary recrystallization annealing was 750 to 950 ° C., and the holding time at the annealing temperature was 2 minutes.
[0121]
An aqueous slurry prepared by mixing the annealing separator of the components in Table 2 with pure water was applied to the front and back surfaces of the cold-rolled steel sheet after primary recrystallization annealing.
[0122]
[Table 2]

[0123]
The decarburized annealed plate coated with the aqueous slurry was held in a furnace at 900 ° C. for 10 seconds to dry the aqueous slurry.
A sample is taken from the finish baking steel sheet obtained in this step, and the sample is selected from the group consisting of Ca, Sr, and Ba in the Ca group element enrichment region existing in the region of 0 to 3.0 μm from the surface of the base steel plate. The number density D42 of the particles containing one or more of the following elements was measured. The values ​​are shown in Table 2.
[0124]
Furthermore, finish annealing was carried out at 1200 ° C. for 20 hours. Through the above manufacturing process, a grain-oriented electrical steel sheet having a base steel sheet and a primary coating was manufactured.
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 recrystallize secondarily, the value of the magnetic flux density B8 deteriorated extremely and was out of the scope of the present invention.
In molten steel numbers 6 to 17, 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, the value of the magnetic flux density B8 was extremely deteriorated. It was out of the scope of the invention.
In molten steel No. 19, 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. 23, 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. 27, 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.
[0125]
In the above manufacturing, the composition of the base steel sheet is different from that of the slab which was the material by performing decarburization annealing and finish annealing (purification annealing) as in the case of general grain-oriented electrical steel sheet. Table 3 shows the chemical composition of the base steel sheet of the manufactured grain-oriented electrical steel sheet.
[0126]
[Table 3]

[0127]
[Characteristic evaluation]
In steel sheet numbers 1, 2, 16, 18, 19, 20, 21, 22, 24, 25, 26, and 27, the components of the steel sheet fall within the scope of the present invention, the magnetic properties and primary of the manufactured grain-oriented electrical steel sheet. The adhesion of the coating was evaluated. The magnetic properties of the manufactured grain-oriented electrical steel sheets and the adhesion of the primary coating were evaluated as test numbers 1 to 52.
[0128]

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 W17 / 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 W17 / 50 of 0.75 W / kg or less was considered to have excellent magnetic characteristics.
[0129]

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 total area of ​​the area where the primary coating remained without peeling was determined. The residual ratio of the primary coating was determined by the following formula.
Primary film residual rate = total area of ​​area where the primary film remains without peeling / sample surface area x 100
It was said that 90% or more of the primary film residual rate was excellent in film adhesion.

A sample having a length of 1 m and a width of 1 m in the rolling direction was taken from the grain-oriented electrical steel sheet of each test number, and the frequency of occurrence of point-like defects NP (Number Density of Pole) was determined visually. When the number of punctate defects in 1 m 2 was 5 or less, it was considered that the punctate defects were suppressed.
[0130]

A sample having a length of 300 mm and a width of 60 mm in the rolling direction was collected 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 D3 in the Al enriched region
(2) Area S5 of the region that is the embedded oxide layer region and the Al-concentrated region.
(3) Area of ​​Al enriched area S3
(4) Distance H5 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.
(5) Total content of Y group elements
(6) Total content of Ca group elements
(7) Number density D4 of Ca group enrichment region
(8) Area of ​​the embedded oxide layer region S1
(9) Observation area S0
[0131]

A sample was cut out from the steel plate in which the aqueous slurry before finish annealing was dried, and the annealing separator layer was observed according to the above method.
(10) Number density D42 of Ca group concentrated region in the annealed separator layer
Got
[0132]

The following values ​​were obtained from the raw material powder of the annealing separator of the aqueous slurry according to the above-mentioned means.
(11) Total abundance ratio of Y group elements CY (0.00562 [Y] +0.00360 [La] +0.00714 [Ce]) /0.0412 [Mg] x 100 (%)
(12) Ca group element content CC (0.0249 [Ca] +0.0114 [Sr] +0.0073 [Ba]) /0.0412 [Mg] x 100 (%)
(13) Average particle size R1 of MgO
(14) Average particle size R2 of Ca group element-containing particles
Further, only MgO, which is an annealing separator, was separated to obtain the following values.
(16) Impurity Ca group element amount in MgO CC'(0.0249 [Ca'] +0.0114 [Sr'] +0.0073 [Ba']) /0.0412 × 100 (%)
(17) Ratio of impurities in MgO to the total amount of Ca group elements in the annealing separator CC'/ CC (16) / (12)
Note that RCA, RSr, and RBa are average values ​​of the equivalent circle diameters of Ca, Sr, and Ba.
[0133]

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 2. At this time, the abundance ratio (CY, CC) of the compound species and each group element was changed.
[0134]
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. It can be seen that those satisfying the provisions of the present invention can obtain good characteristics. Further, when the magnetic flux density B8 was 1.92 or more and the amount of punctate defects generated was 5 pieces / m 2 or less, it was judged that the effect was effective in suppressing the punctate defects. It can be seen that the punctate defects are suppressed in those satisfying the provisions of the present invention. With reference to Table 4, in test numbers 35 to 51, the chemical composition is appropriate and the conditions in the annealing separator (CC, CC', CC' / CC, CY, R1, R2, R2 / R1). Was appropriate. As a result, the area ratio S1 / S0 of the fitted oxide layer is 0.15 or more, the region S5 / S3 which is the fitted Al region A5 is 0.30 or more, the distance H5 is 0.4 or more, and Al. The number density D3 in the concentrated region was 0.020 or more, which was within the scope of the present invention. As a result, in the grain-oriented electrical steel sheets having these test numbers, the magnetic flux density B8 was 1.93T or more, and excellent magnetic characteristics were obtained. Further, the residual ratio of the primary coating was 90% or more, the number of punctate defects NP was 5 / m 2 or less, and excellent primary coating characteristics were exhibited.
[0135]
On the other hand, in test numbers 1 to 3, the total abundance ratio CC of Ca group elements was too small, the morphology of the primary coating did not develop, S1 / S0 was less than 0.18, S5 / S3 was less than 0.30, and D3 was. It was less than 0.005. As a result, the primary film residual rates were 82%, 84% and 76%, respectively, and the film adhesion was inferior.
[0136]
In test numbers 4 to 6, the total abundance ratio CC of Ca group elements was too large, the morphology of the primary coating was too developed, and D3 exceeded 0.150 / μm 2. As a result, the iron loss W17 / 50 exceeded 0.75, and the magnetic characteristics became inferior.
[0137]
In test numbers 7 to 9, the total abundance ratio CC'of Ca group elements in MgO was too small, and in test numbers 13 to 15, CC'/ CC was too low, so the development of the morphology of the primary coating was insufficient. L5 / S0 was less than 0.020 μm / μm 2. As a result, punctate defects of 5 pieces / m 2 or more were generated, the punctate defects were inferior, the primary film residual rate was less than 90%, and the adhesion was inferior.
[0138]
In test numbers 10 to 12, the total abundance ratio CC'of Ca group elements in MgO was too large, and in test numbers 16 to 18, CC'/ CC was too high, so that the morphology of the primary coating developed too much. , L5 / S0 exceeded 0.500 μm / μm 2. As a result, the iron loss W17 / 50 exceeded 0.75, and the magnetic characteristics became inferior.
[0139]
In test numbers 19 to 21, the total abundance ratio CY of the Y group elements was too small, so that the development of the morphology of the primary coating was insufficient and H5 was below 0.4. As a result, the residual ratio of the primary film was 90% or less, and the adhesion was deteriorated.
[0140]
In test numbers 22 to 24, the total abundance ratio CY of the Y group elements was too large, so that the morphology of the primary coating developed too much, and H5 exceeded 4.0. As a result, the magnetic flux density was 1.93T or less.
[0141]
In test number 25, the average particle size R1 based on the number of MgO was too small, so that the plate was seized during finish annealing.
[0142]
In test number 26, R1 was too large, and the supply of Mg to the primary coating was delayed. As a result, S1 / S0, S5 / S3, L5 / S0, and H5 were all below the reference values. As a result, the residual ratio of the primary film was 42%, and the film adhesion was inferior.
[0143]
In test numbers 27, 29, and 31, 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 less than 90%, and the film adhesion was inferior.
[0144]
In test numbers 28, 30, and 32, R2 was too large, the supply of Ca group elements and Mg was biased, S1 / S0 was less than 0.15, and D3 was less than 0.015. As a result, the residual ratio of the primary film was less than 90%, and the film adhesion was inferior.
[0145]
In test number 33, R1 and R2 were within the range, but R2 / R1 exceeded 3.0. As a result, the residual ratio of the primary film was less than 90%, and the film adhesion was inferior.
[0146]
In test number 34, R1 and R2 were within the range, but R2 / R1 was below 0.3. As a result, punctate defects of 5 pieces / m 2 or more were generated, the punctate defects were inferior, the primary film residual rate was less than 90%, and the film adhesion was inferior.
[0147]
In Test No. 52, the annealing separator was within the range, but the content of Bi, Te, and Pb in the molten steel component exceeded 0.03%. As a result, the residual ratio of the primary film was less than 90%, and the film adhesion was inferior.
[0148]
[Table 4]

[0149]

The aqueous slurry to be applied to the steel plate after decarburization and quenching is mixed with MgO, Ti group element-containing compound, Y group element total-containing compound and Ca group element-containing compound with water so that the element content of each group is as shown in Table 5. Mixed and adjusted. At this time, the abundance ratio (CY, CC, CT) of the compound species and each group element was changed.
[0150]
[Table 5]

[0151]
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. Other criteria also cite Example 1. NS. With reference to Table 6, it can be seen that those satisfying the provisions of the present invention can obtain good characteristics.
[0152]
On the other hand, in test numbers 53 and 56, the total abundance ratio CT of Ti group elements was too large, and Ti-based inclusions were formed in the steel during finish annealing and remained unpurified. As a result, the iron loss W17 / 50 deteriorated.
[0153]
In test number 54, the total abundance ratio CC of Ca group elements was too large, the morphology of the primary coating was too developed, and D3 exceeded 0.150 / μm 2. As a result, the iron loss W17 / 50 exceeded 0.75, and the magnetic characteristics became inferior.
[0154]
In test number 55, the total abundance ratio CY of the Y group elements was too large, so the morphology of the primary coating was overdeveloped, and H5 exceeded 4.0. As a result, the magnetic flux density was 1.93T or less.
[0155]
In test number 57, the total abundance ratio CC of Ca group elements was too small, so the development of the morphology of the primary coating was insufficient, and S5 / S3 was below 0.3. As a result, the residual ratio of the primary film was 90% or less, and the adhesion was deteriorated.
[0156]
In test number 58, the total abundance ratio CY of the Y group elements was too small, so that the development of the morphology of the primary coating was insufficient and H5 was below 0.4. As a result, the residual ratio of the primary film was 90% or less, and the adhesion was deteriorated.
[0157]
In test number 59, R1 and R2 were within the range, but R2 / R1 exceeded 3.0.
As a result, punctate defects of 5 pieces / m 2 or more occurred, the punctate defects became inferior, the primary film residual rate was less than 90%, and the adhesion became inferior.
[0158]
In test number 60, R1 and R2 were within the range, but R2 / R1 was below 0.3. As a result, punctate defects of 5 pieces / m 2 or more were generated, the punctate defects were inferior, the primary film residual rate was less than 90%, and the adhesion was inferior.
[0159]
[Table 6]

[0160]
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
[0161]
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.
In the plate thickness direction of the base steel plate, information on the unevenness of the surface of the primary coating when the direction from the primary coating side to the base steel plate side is positive is projected onto a surface parallel to the steel plate surface and developed. death,
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
In the characteristic X-ray intensity and unevenness correlation distribution diagram developed by projecting the component information in the primary coating onto a plane parallel to the surface of the steel plate, the maximum value of the characteristic X-ray intensity of Al is specified, and the characteristic X-ray of Al is specified. When the region where the characteristic X-ray intensity of Al of 20% or more of the maximum intensity is obtained is defined as the "Al enrichment region",
The primary coating is
(1) Number density of the Al-enriched region D3: 0.015 to 0.150 / μm 2,
(2) (Area S5 of the region that is the embedded oxide layer region and the Al-concentrated region) / (Area S3 of the Al-concentrated region) ≧ 0.30,
(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) (Perimeter L5 of the region that is the embedded oxide layer region and the Al-concentrated region) / (observation area S0): 0.020 to 0.500 μm / μm 2,
(5) (Area S1 of the embedded oxide layer region) / (Observation area S0) ≧ 0.15,
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 the unevenness correlation distribution diagram, the maximum value of the characteristic X-ray intensity of each of Ca, Sr, and Ba is specified, and the characteristic X-ray of Ca of 20% or more of the maximum value of the characteristic X-ray intensity of Ca. A region where the 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 Ba of 20% or more of the maximum value of the characteristic X-ray intensity of Ba. When combined with the region where the characteristic X-ray intensity is obtained, it is defined as the "Ca group element enrichment region".
(6) 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%,
(7) 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%,
(8) Number density of the Ca group element enrichment region D4: 0.005 to 2.000 / μm 2,
The grain-oriented electrical steel sheet according to claim 1, which is characterized by satisfying the above-mentioned conditions.
[Claim 3]
By mass%,
C: 0.1% 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 0.07% in total,
Sol. Al: 0.005 to 0.050%, and
N: 0.003 to 0.0300%
A base steel sheet having a chemical composition containing Fe and impurities as a balance, and a base steel sheet containing
It is provided with an annealing separator layer containing MgO as a main component, which adheres to the surface of the base steel sheet.
In the characteristic X-ray intensity and unevenness correlation distribution diagram developed by projecting the information possessed by the quenching separator layer onto a plane parallel to the plate thickness direction cross section of the base steel plate, the characteristic X-ray intensity of each of Ca, Sr, and Ba. The region where the characteristic X-ray intensity of Ca of 20% or more of the maximum value of the characteristic X-ray intensity of Ca is obtained by specifying the maximum value of Ca, and the Sr of 20% or more of the maximum value of the characteristic X-ray intensity of Sr. The region where the characteristic X-ray intensity of Ba is obtained and the region where the characteristic X-ray intensity of Ba of 20% or more of the maximum value of the characteristic X-ray intensity of Ba is obtained are collectively referred to as a "Ca group element enrichment region". When
The annealing separator layer is
(9) Number of particles containing one or more elements selected from the group consisting of Ca, Sr, and Ba in the Ca group element enrichment region existing in the region of 0 to 3.0 μm from the surface of the base metal plate. Density D42: 0.005 to 1.400 pieces / μm 3,
A steel sheet for finish annealing for manufacturing grain-oriented electrical steel sheets, which is characterized by satisfying.
[Claim 4]
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 (%) of the content of Mg, Y, La, Ce, Ca, Sr, and Ba contained in the annealing separator to the content of MgO is [Mg], [Y], [La], [La], respectively. When [Ce], [Ca], [Sr], [Ba] are used,
(10) (0.00562 [Y] +0.00360 [La] +0.00714 [Ce]) /0.0412 [Mg] x 100 (%): 0.20 to 1.60 (%),
(11) (0.0249 [Ca] +0.0114 [Sr] +0.0073 [Ba]) /0.0412 [Mg] x 100 (%): 0.20 to 1.80 (%),
The filling,
The ratio (%) of the content of Mg, Ca, Sr, and Ba contained in the MgO raw material powder to the content of MgO in the MgO raw material powder contained in the annealing separator is [Mg', respectively. ], [Ca'], [Sr'], [Ba'],
(12) (0.0249 [Ca'] + 0.0114 [Sr'] + 0.0073 [Ba']) / 0.0412 [Mg'] x 100 (%): 0.010 to 0.080 (%) ,
The filling,
Further, (13) the above (0.0249 [Ca'] + 0.0114 [Sr] with respect to the above (0.0249 [Ca] + 0.0114 [Sr] + 0.0073 [Ba]) / 0.0412 [Mg] × 100. ´] +0.0073 [Ba ′]) /0.0412 [Mg ′] × 100 ratio is 0.200 to 0.020.
Furthermore, (14) the average particle size of the MgO R1: 0.1 to 2.8 μm,
(15) Average particle size of particles containing one or more elements selected from the group consisting of Ca, Sr, and Ba in the annealing separator R2: 0.2 to 3.0 μm,
(16) (The average particle size R2) / (The average particle size R1): 0.5 to 3.0,
An annealed separator characterized by satisfying.
[Claim 5]
The annealing separator according to claim 4, further containing one or more elements selected from the group consisting of Ti, Zr, and Hf.
[Claim 6]
By mass%,
C: 0.1% 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 0.07% in total,
Sol. Al: 0.005 to 0.05% and
N: 0.003 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 claim 4 or 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: 0.1% 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 0.07% in total,
Sol. Al: 0.005 to 0.05% and
N: 0.003 to 0.030%
A process of hot-rolling a slab containing Fe and impurities in 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 finish annealing steel sheet for producing a grain-oriented electrical steel sheet, wherein the aqueous slurry contains the annealing separation agent according to claim 4 or 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]
Instead of a part of Fe, select from the group consisting of Cu, Sn and Sb. The method for producing a steel sheet for finish annealing according to claim 9 or 10, which contains at least 0.60% of one or more selected elements in total.