RU2773359C1 - Sheet of electrical steel with an oriented grain structure, a method for manufacturing a sheet of electrical steel with an oriented grain structure and an annealing separator used for manufacturing a sheet of electrical steel with an oriented grain structure - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, namely to a sheet of electrical steel with an oriented grain structure. A sheet of electrical steel contains a basic steel sheet having a chemical composition containing, wt. %: C: no more than 0.005, Si: 2.5-4.5, Mn: 0.02-0.2, one or more elements selected from a group consisting of S and Se: in total no more than 0.005%, soluble Al: no more than 0.01, N: no more than 0.01, the rest is Fe and impurities, and the primary coating formed on the surface of the main steel sheet and containing Mg₂SiO₄ as the main component. The position of the peak intensity of the Al radiation obtained by performing elemental analysis by optical emission spectrometry of a glow discharge from the surface of the primary coating in the direction of the thickness of a sheet of electrical steel with an oriented grain structure is located within 2.0-12.0 mcm from the surface of the primary coating in the direction of thickness. The numerical density of Al oxides with dimensions of at least 0.2 mcm in diameter of a circle equivalent in area at the peak of the intensity of Al radiation is 0.03-0.2/mcm².

EFFECT: sheet has high magnetic properties and adhesion of the primary coating to the main steel sheet.

5 cl, 7 tbl, 2 ex

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

[0001]

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

BACKGROUND OF THE INVENTION

[0002]

The grain-oriented electrical steel sheet is a steel sheet containing, by mass %, Si 0.5 to 7% or so and having crystal orientations maintained respectively in {110}<001> orientations (Goss orientation). To maintain the orientation of the crystals, a phenomenon of catastrophic grain growth called secondary recrystallization is used.

[0003]

A method for manufacturing a grain-oriented electrical steel sheet is as follows: The slab is heated and subjected to hot rolling to obtain a hot-rolled steel sheet. The hot rolled steel sheet is annealed if necessary. Hot rolled steel sheet is subjected to pickling. The pickled hot-rolled steel sheet is subjected to cold rolling with a cold-rolling reduction ratio of at least 80% to obtain a cold-rolled steel sheet. The cold rolled steel sheet is subjected to decarburization annealing to cause primary recrystallization. The decarburized annealed cold rolled steel sheet is finish annealed to cause secondary recrystallization. Through the above process, a grain-oriented electrical steel sheet is produced.

[0004]

After the aforementioned decarburization annealing and before the finish annealing, the surface of the cold rolled steel sheet is coated with an aqueous slurry containing an annealing separator containing MgO as a main component and dried. The cold-rolled steel sheet with the annealing separator dried on it is wound into a roll and then subjected to finishing annealing. During finish annealing, MgO in the annealing separator and SiO ₂ in the inner oxide layer formed on the surface of the cold-rolled steel sheet during decarburization annealing react, whereby a primary coating is formed on the surface containing Mg ₂ SiO ₄ (forsterite) as the main component . After the formation of the primary coating, the primary coating is formed, for example, together with an insulating coating (also called "secondary coating"), consisting of colloidal silicon dioxide and phosphate. Primary coating and insulating coating have a lower coefficient of thermal expansion than steel sheet. For this reason, the primary coating together with the insulating coating imparts tension to the steel sheet, reducing steel losses. Moreover, the primary coating enhances the adhesion of the insulation coating to the steel sheet. Therefore, the adhesion of the Primary Coating to the steel sheet is preferably higher.

[0005]

On the other hand, reducing the steel loss of the grain-oriented electrical steel sheet effectively increases the magnetic flux density and reduces the hysteresis loss.

[0006]

To increase the magnetic flux density in a grain-oriented electrical steel sheet, an effective solution is to ensure that the crystal orientations of the base steel sheet correspond to the Goss orientation. A method for increasing the degree of integration in the Goss orientation is proposed in Patent Documents (PTL) 1-3. In these patent documents, the steel sheet contains elements that improve the magnetic properties, which enhance the action of inhibitors (Sn, Sb, Bi, Te, Pb, Se, etc.). Due to this, the degree of integration in the Goss orientation increases and the magnetic flux density can be increased.

[0007]

However, if the steel sheet contains magnetic enhancing elements, the Primary Coating portions will aggregate, and therefore, the interface between the Steel Sheet and the Primary Coating will flatten easily. In this case, the adhesion of the primary coating to the steel sheet will decrease.

[0008]

A method of increasing the adhesion of the primary coating to the steel sheet is described in PTL 4, 5, 6 and 7,

[0009]

In PTL 4, a slab is made with a Ce content of 0.001-0.1%, and a steel sheet surface is formed with a primary coating containing Ce at a concentration of 0.01-1000 mg/m ² . In PTL 5, in a grain-oriented electrical steel sheet containing Si: 1.8-7% and having a primary coating containing Mg ₂ SiO ₄ as a main component, the primary coating is provided containing Ce with a density of 0.001-1000 mg/ m ² per side.

[0010]

Document PTL 6 provides for the formation of a primary coating, characterized in that the primary coating contains one or more types of compounds of alkaline earth metals selected from Ca, Sr and Ba, and rare earth elements by incorporating an annealing separator containing MgO as a main component , compounds comprising a rare earth compound at a concentration of 0.1-10%, one or more types of alkaline earth metal compounds selected from Ca, Sr and Ba at a concentration of 0.1-10%, and a sulfur compound at a concentration of 0.01-5%.

[0011]

Document 7 provides for the formation of a primary coating, characterized by the content of compounds, including one or more elements selected from Ca, Sr and Ba, rare earth compounds at a concentration of 0.1-1.0% and sulfur.

[LIST OF LINKS]

[PATENT DOCUMENTS]

[0012]

[PTL 1] Japanese Unexamined Patent Publication No. 6-88171

[PTL 2] Japanese Unexamined Patent Publication No. 8-269552

[PTL 3] Japanese Unexamined Patent Publication No. 2005-290446

[PTL 4] Japanese Unexamined Patent Publication No. 2008-127634

[PTL 5] Japanese Unexamined Patent Publication No. 2012-214902

[PTL 6] W02008/062853

[PTL 7] Japanese Unexamined Patent Publication No. 2009-270129

SUMMARY OF THE INVENTION

[TECHNICAL PROBLEM]

[0013]

However, if the annealing separator is formulated with Y, La, Ce or other rare earth compounds to form a primary coating containing Y, La and Ce, the magnetic properties are sometimes degraded. In addition, if the particle number densities of Y, La, Ce or other rare earth compounds or Ca, Sr, Ba, or other additives in the starting powder material of the annealing separator are insufficient, there will sometimes be areas in which insufficient primary coating is formed, and the adhesion of the primary coating will decrease.

[0014]

An object of the present invention is to provide a grain oriented electrical steel sheet having very high magnetic properties and a very high primary coating adhesion to a base steel sheet, a method for manufacturing grain oriented electrical steel sheet, and an annealing cage used for manufacturing grain oriented electrical steel sheet. grain structure.

[SOLUTION]

[0015]

The grain-oriented electrical steel sheet according to the present invention contains a base steel sheet having a chemical composition containing, in mass%, C: not more than 0.005, Si: 2.5-4.5, Mn: 0.02- 0.2, one or more elements selected from the group consisting of S and Se: not more than 0.005 in total, soluble Al: not more than 0.01 and N: not more than 0.01, and containing a balance consisting of Fe and impurities , and a primary coating formed on the surface of the base steel sheet and containing Mg ₂ SiO ₄ as the main component, wherein the position of the Al emission intensity peak obtained by performing elemental analysis by glow discharge optical emission spectrometry from the surface of the primary coating in the electrical sheet thickness direction grain-oriented steel, is located within 2.0-12.0 µm from the surface of the primary coating in the thickness direction, and the numerical density of Al oxides with dimensions of at least 0, 2 μm in diameter equivalent to the area of the circle, at the peak position of the radiation intensity Al is 0.03-0.2/μm ² .

[0016]

The method for manufacturing a grain-oriented electrical steel sheet according to the present invention comprises a cold rolling process of a hot-rolled steel sheet containing, in wt %, C: not more than 0.1, Si: 2.5-4.5, Mn: 0 .02-0.2, one or more elements selected from the group consisting of S and Se: in the amount of 0.005-0.07, soluble Al: 0.005-0.05 and N: 0.001-0.030 and containing a residue consisting of Fe and impurities, with a cold rolling reduction ratio of not less than 80%, to make a cold-rolled steel sheet used as a main steel sheet, a cold-rolled steel sheet decarburization annealing process, a process for coating the surface of a cold-rolled steel sheet after decarburization annealing with an aqueous suspension containing an annealing separator, and drying the aqueous slurry on the surface of the cold-rolled steel sheet in an oven at 400-1000°C, and a process for performing finish annealing of the cold-rolled steel sheet after the aqueous slurry is dried on the. The annealing separator contains MgO, at least one or more types of metal compounds selected from the group consisting of Y, La and Ce, and at least one or more types of metal compounds selected from the group consisting of Ti, Zr and Hf, while when the content of MgO in the annealing separator is 100 wt. hours, the total content of metal compounds selected from the group consisting of Y, La and Ce, converted into oxides, is 0.5-8.0 wt. hours, the total content of metal compounds selected from the group consisting of Ti, Zr and Hf, converted into oxides, is 0.5-10.0 wt. hours, moreover, the total amount of the total content of metal compounds selected from the group consisting of Y, La and Ce, converted into oxides, and the total content of metal compounds selected from the group consisting of Ti, Zr and Hf, converted into oxides, is 2.0-14.0 wt. hours, and the ratio of the sum of the numbers of Ti, Zr and Hf atoms and the sum of the numbers of Y, La and Ce atoms contained in the annealing separator is 0.15-4.00, and the numerical density of the particles of metal compounds selected from the group consisting of Y, La and Ce, which are particles with a sphere equivalent in volume diameter of at least 0.1 μm, is at least 2000000000/g, and the particle number density of the metal compounds selected from the group consisting of Ti, Zr and Hf, which are particles with a diameter of a sphere equivalent in volume, not less than 0.1 μm, is not less than 2000000000/g.

[0017]

An annealing separator used to produce a grain-oriented electrical steel sheet according to the present invention contains MgO, at least one or more types of metal compounds selected from the group consisting of Y, La, and Ce, and at least , one or more types of metal compounds selected from the group consisting of Ti, Zr and Hf, while when the content of MgO in the annealing separator is 100 wt. hours (wt.%), the total content of metal compounds selected from the group consisting of Y, La and Ce, converted into oxides, is 0.5-8.0 wt. hours, the total content of metal compounds selected from the group consisting of Ti, Zr and Hf, converted into oxides, is 0.5-10.0 wt. hours, and the total amount of the total content of metal compounds selected from the group consisting of Y, La and Ce, converted into oxides, and the total content of metal compounds selected from the group consisting of Ti, Zr and Hf, converted into oxides, is 2.0-14.0 wt. hours, and the ratio of the sum of the numbers of atoms of Y, La and Ce to the sum of the numbers of atoms of Ti, Zr and Hf contained in the annealing separator is 0.15-4.00, and the numerical density of the particles of metal compounds selected from the group consisting of Y, La and Ce, which are particles with a sphere equivalent in volume diameter of at least 0.1 μm, is at least 2000000000/g, and the particle number density of the metal compounds selected from the group consisting of Ti, Zr and Hf, which are particles with a diameter of a sphere equivalent in volume, not less than 0.1 μm, is not less than 2000000000/g.

[BENEFICIAL EFFECTS OF THE INVENTION]

[0018]

The grain-oriented electrical steel sheet according to the present invention has very high magnetic properties and very high primary coating adhesion to the base steel sheet. The manufacturing method according to the present invention makes it possible to produce the aforementioned grain-oriented electrical steel sheet. The annealing separator according to the present invention is used in the above-described manufacturing method. This makes it possible to produce a grain-oriented electrical steel sheet.

DESCRIPTION OF EMBODIMENTS

[0019]

The inventors have investigated and studied the magnetic properties of a grain-oriented electrical steel sheet containing elements for improving the magnetic properties and improving the adhesion of primary coatings formed by introducing a Y compound, a La compound, and a Ce compound into an annealing separator. As a result, the inventors obtained the following information.

[0020]

At the interface between the primary coating and the steel sheet in the grain-oriented electrical steel sheet, there are fixing structures. In particular, near the interface between the Primary Coating and the steel sheet, the root portions of the Primary Coating extend into the inside of the steel sheet. The deeper the roots of the primary coating penetrate into the steel sheet, the higher the adhesion of the primary coating to the steel sheet. Moreover, the more dispersed the roots of the primary coating within the steel sheet (the more they are distributed), the higher the adhesion of the primary coating to the steel sheet.

[0021]

On the other hand, if the roots of the Primary Coating penetrate too deeply into the steel sheet, then the Roots of the Primary Coating will hinder secondary recrystallization in the Goss orientation. Therefore, the number of crystal grains with random orientations will increase in the surface layer. Moreover, the roots of the primary coating become factors that inhibit the movement of domain boundaries, and the magnetic properties deteriorate. Similarly, if the roots of the Primary Coating are excessively dispersed within the steel sheet, then the Roots of the Primary Coating will hinder secondary recrystallization in the Goss orientation, and crystal grains with random orientations will increase in the surface layer. Moreover, the roots of the primary coating become factors that inhibit the movement of domain boundaries, and the magnetic properties deteriorate.

[0022]

Based on the above obtained information, the inventors further investigated the condition of the roots of the Primary Coating, the magnetic properties of the grain oriented electrical steel sheet, and the adhesion of the Primary Coating.

[0023]

If the annealing separator is composed of a Y compound, a La compound, and a Ce compound to form a primary coating as explained above, the magnetic properties deteriorate. The reason is believed to be that the roots of the Primary Coating penetrate too deeply into the steel sheet and inhibit the movement of domain boundaries.

[0024]

Therefore, the inventors carried out experiments to reduce the content of Y compound, La compound, and Ce compound in an annealing separator containing MgO as a main component, and replace Ti compound, Zr compound, and Hf compound to form a primary coating, and performed experiments to increase density of the number density of the particles of these compounds in the annealing separator before preparing an aqueous suspension (in the original powder material). As a result, the inventors have found that the magnetic properties of the grain-oriented electrical steel sheet are sometimes improved, and the adhesion of the primary coating is also improved. The inventors further adjusted the contents of the Y compound, the La compound, and the Ce compound and the contents of the Ti compound, the Zr compound, and the Hf compound in the annealing separator containing mainly MgO to investigate the depth and dispersion state of the primary coating roots.

[0025]

Spinel-shaped Al oxide (MgAl ₂ O ₄ ) is the main component of the primary coating roots. The position, in depth from the surface, of the intensity peak of Al emission obtained by performing elemental analysis by glow discharge optical emission spectrometry (GDS (Glow Discharge Spectrometer)) from the surface of the electrical steel sheet with grain oriented in the thickness direction is considered to be (below , this position is called "D _Al position of the Al peak") indicates the position of existence of the spinel, that is, the position of the root portions of the primary coating. In addition, it is believed that the number density of Al oxides represented by spinel with a size of not less than 0.2 μm in the diameter of an area-equivalent circle, at the D _{Al position of the Al} peak, (hereinafter referred to as "ND number density of Al oxides") shows the state of dispersion root parts of the primary coating.

[0026]

The inventors have carried out further studies, and as a result, found that if the D _Al position of the Al peak is 2.0-12.0 µm, and the numerical density ND of Al oxides is 0.03-0.2/µm ² , then the root portions of the Primary Coating are suitable in length and suitable in dispersion state, and therefore very high magnetic properties and adhesion of the Primary Coating are achieved.

[0027]

The aforementioned suitable ranges of the position D _Al of the Al peak and the number density ND of the Al oxides can be obtained, as explained above, by setting the suitable ranges of the contents of Y, La and Ce compounds and the contents of Ti, Zr and Hf compounds in the annealing separator, as well as the number density of the particles of the compounds a metal selected from the group consisting of Ya, La and Ce, and a particle number density of metal compounds selected from the group consisting of Ti, Zr and Hf in the starting powder material before preparing the aqueous slurry of the annealing separator.

[0028]

In addition, the inventors investigated the ratio between the total wt.% content of C _RE compounds of Y, La and Ce, converted into oxides, when determining the content of MgO at 100% (explained later), and the total wt.% content of C _G4 compounds of Ti, Zr and Hf converted into oxides, when determining the MgO content of 100% (explained later) in an annealing separator containing mainly MgO, and the number density ND of Al oxides (/μm ² ) in the image representing the distribution of Al obtained by analysis by energy dispersive X-ray spectroscopy (EDS) in the region of the glow discharge spot, at the D _{Al position of the Al} peak. As a result, it was found that the ND number density of Al oxides can be controlled by correcting the contents of compounds of a metal selected from the group consisting of Y, La and Ce converted to oxides and compounds of a metal selected from the group consisting of Ti, Zr and Hf converted to oxides in an annealing separator.

[0029]

The inventors have made further studies and, as a result, found that, in the case of using an annealing separator containing MgO, at least one or more types of compounds of a metal selected from the group consisting of Y, La and Ce, and at least at least one or more types of metal compounds selected from the group consisting of Ti, Zr and Hf, while when the content of MgO is 100 wt. hours, the total content of metal compounds selected from the group consisting of Y, La and Ce, converted into oxides, is 0.5-8.0 wt. hours, the total content of metal compounds selected from the group consisting of Ti, Zr and Hf, converted into oxides, is 0.5-10.0 wt. hours, and the total amount of the total content of metal compounds selected from the group consisting of Y, La and Ce, converted into oxides, and the total content of metal compounds selected from the group consisting of Ti, Zr and Hf, converted into oxides, is 2.0-14.0 wt. hours, and the ratio of the sum of the numbers of Ti, Zr and Hf atoms and the sum of the numbers of Y, La and Ce atoms contained in the annealing separator is 0.15-4.00, and the use of a powder of metal compounds selected from the group consisting of Y , La and Ce, and a powder of metal compounds selected from the group consisting of Ti, Zr and Hf, with number densities of particles with particle sizes of at least 0.1 μm in the initial powder material before preparing an aqueous suspension of the annealing separator, respectively, at least 2000000000/g, even in a grain-oriented electrical steel sheet made from a hot-rolled steel sheet containing magnetic flux increasing elements (Sn, Sb, Bi, Te, Pb, etc.), the D _{Al position of the Al} peak falls in the range of 2.0-12.0 μm, and the numerical density ND of Al oxides with a size of at least 0.2 μm in a circle equivalent in diameter falls in the range of 0.03-0.2/μm ² , and very high magnetic properties and adhesion of the primary pok digging.

[0030]

The grain-oriented electrical steel sheet according to the present invention, made in view of the above obtained information, contains a base steel sheet having a chemical composition containing, in mass%, C: not more than 0.005, Si: 2.5-4, 5, Mn: 0.02-0.2, one or more elements selected from the group consisting of S and Se: not more than 0.005 in total, soluble Al: not more than 0.01, and N: not more than 0.01 , and containing a residue composed of Fe and impurities, and a primary coating formed on the surface of the base steel sheet and containing Mg ₂ SiO ₄ as a main component. The position of the peak intensity of Al radiation obtained by elemental analysis by glow discharge optical emission spectrometry from the surface of the primary coating in the thickness direction of the grain-oriented electrical steel sheet is located within 2.0-12.0 μm from the surface of the primary coating in the thickness direction , and the numerical density of Al oxides at the peak position of the Al emission intensity is 0.03-0.2/μm ² ,

[0031]

The method for manufacturing a grain-oriented electrical steel sheet according to the present invention comprises a cold rolling process of a hot-rolled steel sheet containing, in wt %, C: not more than 0.1, Si: 2.5-4.5, Mn: 0 .02-0.2, one or more elements selected from the group consisting of S and Se: 0.005-0.07 in total, soluble Al: 0.005-0.05, and N: 0.001-0.030, and containing a residue, consisting of Fe and impurities, with a cold rolling reduction ratio of not less than 80%, to make cold-rolled steel sheet used as the main steel sheet, the process of decarburization annealing of cold-rolled steel sheet, the process of coating the surface of cold-rolled steel sheet after decarburization annealing with water slurry containing annealing separator , and drying the aqueous slurry on the surface of the cold-rolled steel sheet in a furnace at 400-1000°C, and a process for performing finish annealing of the cold-rolled steel sheet after the aqueous slurry is high shena. The annealing separator contains MgO, at least one or more types of metal compounds selected from the group consisting of Y, La and Ce, and at least one or more types of metal compounds selected from the group consisting of Ti, Zr and Hf, while when the content of MgO in the annealing separator is 100 wt. hours, the total content of metal compounds selected from the group consisting of Y, La and Ce, converted into oxides, is 0.5-8.0 wt. hours, the total content of metal compounds selected from the group consisting of Ti, Zr and Hf, converted into oxides, is 0.5-10.0 wt. hours, moreover, the total amount of the total content of metal compounds selected from the group consisting of Y, La and Ce, converted into oxides, and the total content of metal compounds selected from the group consisting of Ti, Zr and Hf, converted into oxides, is 2.0-14.0 wt. hours, and the ratio of the sum of the numbers of Ti, Zr and Hf atoms and the sum of the numbers of Y, La and Ce atoms contained in the annealing separator is 0.15-4.00, and moreover, in the initial powder material before preparing an aqueous suspension of the annealing separator , number densities of particles of a metal compound selected from the group consisting of Y, La and Ce, and number densities of particles with a particle size of at least 0.1 μm of a metal compound selected from the group consisting of Ti, Zr and Hf, in the initial powder material are, respectively, not less than 2000000000/g. In this case, the particle sizes are the diameters of equivalent spheres, calculated by volume.

[0032]

The annealing separator may further comprise one or two or more types of metal compounds selected from the group consisting of Ca, Sr and Ba in the range of the ratio of the sum of the numbers of Ca, Sr and Ba atoms to the number of Mg atoms contained in the annealing separator is less than 0.025 ,

[0033]

In the above-described method for manufacturing a grain-oriented electrical steel sheet, the chemical composition of the hot-rolled steel sheet may further contain, instead of a portion of Fe, one or more elements selected from the group consisting of Cu, Sb, and Sn, for a total of not more than 0.6 %.

[0034]

In the above-described method for manufacturing a grain-oriented electrical steel sheet, the chemical composition of the hot-rolled steel sheet further contains, instead of a portion of Fe, one or more elements selected from the group consisting of Bi, Te, and Pb, a total of not more than 0.03% .

[0035]

The annealing separator according to the present invention is used to produce a grain oriented electrical steel sheet. The annealing separator contains MgO, at least one or more types of metal compounds selected from the group consisting of Y, La and Ce, and at least one or more types of metal compounds selected from the group consisting of Ti, Zr and Hf, while when the content of MgO in the annealing separator is 100 wt. hours, the total content of metal compounds selected from the group consisting of Y, La and Ce, converted into oxides, is 0.5-8.0 wt. hours, the total content of metal compounds selected from the group consisting of Ti, Zr and Hf, converted into oxides, is 0.5-10.0 wt. hours, moreover, the total amount of the total content of metal compounds selected from the group consisting of Y, La and Ce, converted into oxides, and the total content of metal compounds selected from the group consisting of Ti, Zr and Hf, converted into oxides, is 2.0-14.0 wt. hours, and the ratio of the sum of the numbers of Ti, Zr and Hf atoms and the sum of the numbers of Y, La and Ce atoms contained in the annealing separator is 0.15-4.00, and moreover, the numerical density of the particles of the metal compound selected from the group consisting of Y, La and Ce, with a particle size of at least 0.1 µm in the original powder material and the number density of particles of a metal compound selected from the group consisting of Ti, Zr and Hf, with a particle size of at least 0.1 µm in the original powder material before preparing an aqueous suspension of the annealing separator are, respectively, not less than 2000000000/g. In this case, the particle sizes are the diameters of equivalent spheres, calculated by volume.

[0036]

The annealing separator may further contain one or two or more types of metal compounds selected from the group consisting of Ca, Sr and Ba, in the range of the ratio of the sum of the numbers of Ca, Sr and Ba atoms to the number of Mg atoms contained in the annealing separator is less than 0.025 ,

[0037]

The grain-oriented electrical steel sheet, the manufacturing method of the grain-oriented electrical steel sheet, and the annealing separator used for manufacturing the grain-oriented electrical steel sheet according to the present invention will be described in detail below. In the present description, the designation "%", referring to the contents of the elements forming the steel sheet, will mean "wt.%", unless otherwise indicated. In addition, regarding the numerical values of A and B, the expression "A-B" must mean "not less than A and not more than B". In this expression, when the unit of measure is assigned only to the numerical value of B, that unit of measure must also be applied to the numerical value of A.

[0038]

Composition of Grain-Oriented Electrical Steel Sheet

A grain-oriented electrical steel sheet according to one aspect of the present invention comprises a base steel sheet and a primary coating formed on a surface of the base steel sheet.

[0039]

Chemical composition of base steel sheet

The chemical composition of the base steel sheet forming the aforementioned grain-oriented electrical steel sheet contains the following elements. Note that, as explained in the following manufacturing method, a base steel sheet is produced by cold rolling using a hot-rolled steel sheet having the following chemical composition.

[0040]

C: no more than 0.005%

Carbon (C) is an element effective for controlling the microstructure up to completion of the decarburization annealing in the manufacturing process, but if the content of C exceeds 0.005%, the magnetic properties of the grain-oriented electrical steel sheet in the final product sheet deteriorate. Therefore, the C content does not exceed 0.005%. The C content is preferably as low as possible. However, even when the C content is reduced to less than 0.0001%, the production cost rises sharply. The above effect changes very little. Therefore, the preferred lower limit of the C content is 0.0001%.

[0041]

Si: 2.5-4.5%

Silicon (Si) increases the electrical resistance of steel to reduce eddy current losses. If the Si content is less than 2.5%, the above effect is not sufficiently achieved. On the other hand, if the Si content exceeds 4.5%, the cold workability of the sheet decreases. Therefore, the Si content is 2.5-4.5%. The preferred lower limit of the Si content is 2.6%, more preferably 2.8%. The preferred upper limit of the Si content is 4.0%, more preferably 3.8%.

[0042]

Mn: 0.02-0.2%

Manganese (Mn) bonds with the S and Se described below during the fabrication process to form MnS and MnSe. These precipitates act as inhibitors (inhibitors of the normal growth of crystal grains) and cause secondary recrystallization in the steel. Mn further enhances the hot workability of the steel. If the Mn content is less than 0.02%, the above effect is not sufficiently achieved. On the other hand, if the Mn content exceeds 0.2%, secondary recrystallization does not occur and the magnetic properties of the steel deteriorate. Therefore, the Mn content is 0.02-0.2%. The preferred lower limit of the Mn content is 0.03%, more preferably 0.04%. The preferred upper limit of the Mn content is 0.13%, more preferably 0.10%.

[0043]

One or more elements selected from the group consisting of S and Se: not more than 0.005% in total

Sulfur (S) and selenium (Se) bind to Mn during the manufacturing process, forming MnS and MnSe acting as inhibitors. However, if the contents of these elements exceed 0.005% in total, the magnetic properties deteriorate due to residual inhibitors. In addition, due to the segregation of S and Se, surface defects are sometimes caused 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 does not exceed 0.005%. The total sum of the contents of S and Se in the grain-oriented electrical steel sheet is preferably as low as possible. However, even if the total sum of the S content and the Se content in the grain-oriented electrical steel sheet is reduced to less than 0.0005%, the production cost rises sharply. The above effect changes very little. Therefore, the preferred lower limit for the total content of one or more elements selected from the group consisting of S and Se in the grain oriented electrical steel sheet is 0.0005%.

[0044]

Soluble Al: no more than 0.01%

Aluminum (Al) bonds with N during the manufacturing process of grain oriented electrical steel sheet to form AlN acting as an inhibitor. However, if the content of soluble Al in the grain-oriented electrical steel sheet exceeds 0.01%, an excess of inhibitor remains in the steel sheet, so that the magnetic properties deteriorate. Therefore, the content of soluble Al does not exceed 0.01%. The preferred upper limit of soluble Al content is 0.004%, more preferably 0.003%. The soluble Al content is preferably as low as possible. However, even if the content of soluble Al in the grain-oriented electrical steel sheet is reduced to less than 0.0001%, the production cost rises sharply. The above effect changes very little. Therefore, the preferred lower limit of the content of soluble Al in the grain-oriented electrical steel sheet is 0.0001%. It should be noted that, in the present description, the term soluble Al means "acid-soluble Al". Therefore, the content of soluble Al is the content of acid-soluble Al.

[0045]

N: no more than 0.01%

Nitrogen (N) binds to Al during the manufacturing process of grain oriented electrical steel sheet to form AlN acting as an inhibitor. However, if the N content in the grain-oriented electrical steel sheet exceeds 0.01%, the inhibitor remains in excess in the grain-oriented electrical steel sheet, and the magnetic properties deteriorate. Therefore, the N content does not exceed 0.01%. 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 of the grain-oriented electrical steel sheet is reduced to less than 0.0001%, the production cost rises sharply. The above effect changes very little. Therefore, the preferred lower limit of the N content in the grain-oriented electrical steel sheet is 0.0001%.

[0046]

The rest of the chemical composition of the base steel sheet in the grain-oriented electrical steel sheet according to the present invention consists of Fe and impurities. In this case, "impurities" means the following elements that come from ore used as raw materials, scrap metal or production environment, etc., during the industrial production of the main steel plate, or which remain in the steel incompletely removed during the refining annealing, and the presence of which is allowed in a content that does not adversely affect the performance of the grain-oriented electrical steel sheet in accordance with the present invention.

[0047]

On the issue of impurities

In the composition of impurities in the base steel sheet of the grain-oriented electrical steel sheet according to the present invention, the total content of one or more elements selected from the group consisting of Cu, Sn and Sb, Bi, Te and Pb does not exceed 0.30 %.

[0048]

As for copper (Cu), tin (Sn), antimony (Sb), bismuth (Bi), tellurium (Te) and lead (Pb), the part of Cu, Sn and Sb, Bi, Te and Pb in the main steel sheet is output from a high temperature heat treatment system, also known as "refining annealing" of one finishing annealing process. These elements increase the selectivity of the secondary recrystallization orientation in finish annealing, with the effect of increasing the magnetic flux density, but while remaining in the base steel sheet after finishing annealing, cause an increase in steel loss like simple impurities. Therefore, the total content of one or more elements selected from the group consisting of Cu, Sn and Sb, Bi, Te and Pb does not exceed 0.30%. As explained above, these elements are impurities, and therefore the total content of these elements is preferably as low as possible.

[0049]

Primary oxide film

The grain-oriented electrical steel sheet according to the present invention, as described above, further comprises a primary coating. The primary coating is formed on the surface of the base steel sheet. The main component of the primary coating is Mg ₂ SiO ₄ (forsterite). In particular, the primary coating contains Mg ₂ SiO ₄ in a concentration of 50-90 wt.%.

[0050]

It should be noted that although the main component of the primary coating is Mg ₂ SiO ₄ as described above, but the primary coating contains at least one or more types of metal compound selected from the group consisting of Y, La and Ce, and at least one or more metal compound types selected from the group consisting of Ti, Zr and Hf. The total content of Y, La and Ce in the primary coating is 0.001-2.0 wt.%. In addition, the total content of Ti, Zr and Hf in the primary coating is 0.0015-6.0 wt.%.

[0051]

As described above, in the present invention, in a method for manufacturing a grain-oriented electrical steel sheet, an annealing separator is used, containing a metal compound selected from the group consisting of Y, La, and Ce, and a metal compound selected from the group consisting of Ti, Zr and Hf described above. Because of this, it is possible to improve the magnetic properties of the grain-oriented electrical steel sheet, and it is also possible to improve the adhesion of the primary coating coating. Due to the content of a metal compound selected from the group consisting of Y, La and Ce and a metal compound selected from the group consisting of Ti, Zr and Hf in the annealing separator, the Primary Coating also includes the aforementioned contents of Y, La and Ce and Ti , Zr and Hf.

[0052]

The content of Mg ₂ SiO ₄ in the primary coating can be measured in the following way. The grain-oriented electrical steel sheet is subjected to electrolysis to separate only the primary coating from the surface of the base steel sheet. Perform a quantitative analysis of Mg in the separated primary coating by inductively coupled plasma mass spectrometry (ICP-MS). The product of the obtained quantized value (wt.%) and the molecular weight of Mg ₂ SiO ₄ is divided by the atomic weight of Mg to find the equivalent content of Mg ₂ SiO ₄ .

[0053]

The total content of Y, La and Ce and the total content of Ti, Zr and Hf in the primary coating can be found in the following way. The grain-oriented electrical steel sheet is subjected to electrolysis to separate only the primary coating from the surface of the base steel sheet. Quantitative analysis of the contents of Y, La and Ce (wt.%) and the contents of Ti, Zr and Hf (wt.%) in the separated primary coating is performed by ICP-MS.

[0054]

Determining the peak position of Al emission intensity using GDS

In addition, in the grain-oriented electrical steel sheet according to the present invention, the position of the Al emission intensity peak obtained by performing elemental analysis by glow discharge optical emission spectrometry from the surface of the primary coating in the thickness direction of the grain-oriented electrical steel sheet is located within 2.0-12.0 µm from the surface of the primary coating in the thickness direction.

[0055]

In the grain-oriented electrical steel sheet, there are fixing structures at the interface between the primary coating and the steel sheet (base metal). In particular, the primary coating portions penetrate into the steel sheet from the surface of the steel sheet. Primary coating areas that penetrate inside the steel sheet from the surface of the steel sheet exhibit a so-called fixing effect (anchor effect) and increase the adhesion of the primary coating to the steel sheet. Further, the Primary Coating portions penetrating the interior of the steel sheet from the surface of the steel sheet will be referred to herein as "Primary Coating Roots".

[0056]

In areas in which the roots of the Primary Coating penetrate into the steel sheet, the main component of the Roots of the Primary Coating is spinel (MgAl ₂ O ₄ ), one type of Al oxide. The intensity peak of Al emission obtained by performing elemental analysis by glow discharge optical emission spectrometry indicates the position at which the spinel is present.

[0057]

The depth position of the Al emission intensity peak from the surface of the Primary Coating is referred to as the “D _{Al position of the Al} peak” (μm). The D _Al position of the Al peak less than 2.0 μm means that the spinel was formed at a position shallow (near) from the surface of the steel sheet, that is, the root portions of the Primary Coating are shallow. In this case, the adhesion of the primary coating is low. On the other hand, the D _Al position of the Al peak greater than 12.0 μm means that the root portions of the Primary Coating have spread excessively. The root portions of the Primary Coating have penetrated deep sections of the steel sheet. In this case, the roots of the primary coating inhibit the movement of domain boundaries, and the magnetic properties deteriorate.

[0058]

If the D _Al position of the Al peak is 2.0-12.0 µm, excellent magnetic properties can be maintained and the adhesion of the primary coating can be improved. The preferred lower limit of the D _Al position of the Al peak is 3.0 µm, more preferably 4.0 µm. The preferred upper limit of the D _Al position of the Al peak is 11.0 µm, more preferably 10.0 µm.

[0059]

The position D _Al of the Al peak can be measured by the following method. For elemental analysis, the known method of glow discharge optical emission spectrometry (GDS) is used. In particular, an Ar atmosphere is created in the space above the surface of the grain-oriented electrical steel sheet. A voltage is applied to the grain-oriented electrical steel sheet to cause generation of a glow discharge plasma, which is used to sputter a surface layer of the steel sheet, and is simultaneously analyzed in the thickness direction.

[0060]

The Al contained in the surface layer of the steel sheet is identified by the element-specific wavelength of the emission spectrum generated by excitation of atoms in the glow discharge plasma. In addition, the identified Al radiation intensity is displayed in the form of a graph in the depth direction. The _Al peak position D Al is found from the Al emission intensity plot.

[0061]

The position in depth from the surface of the primary coating during elemental analysis is calculated from the sputtering time. In particular, first, for a standard sample, the relationship between spray time and spray depth (referred to below as "sample results") is found. Sample results are used to convert spray time to spray depth. The converted sputter depth is defined as the depth position found by elemental analysis (Al analysis), (depth position from the Primary Coating surface). To perform GDS in the present invention, a commercial high frequency glow discharge optical emission spectrometry analysis apparatus can be used.

[0062]

Numerical density ND of Al oxides with dimensions of at least 0.2 μm in discharge spots

In addition, in the grain-oriented electrical steel sheet according to the present invention, the numerical density ND of Al oxides with a size of at least 0.2 μm in a diameter equivalent circle, at the position D _{Al of the Al} peak is 0.03-0.2 / µm ² .

[0063]

As stated above, the position D _Al of the Al peak corresponds to the region of the roots of the primary coating. In the root part of the primary coating there is a large amount of spinel with Al oxide (MgAl ₂ O ₄ ). Therefore, when determining the number density of Al oxides in any region at the D _Al position of the Al peak (for example, the lower portions of glow discharge discharge spots) as the number density ND of Al oxides, the number density ND of Al oxides becomes an indicator showing the dispersed state of the roots of the primary coating (spinels) in the surface layer of the steel sheet.

[0064]

If the numerical density ND of Al oxides is less than 0.03/μm ² , then the roots of the primary coating are not sufficiently formed. For this reason, the adhesion of the primary coating to the steel sheet is low. On the other hand, if the number density ND of the Al oxides exceeds 0.2/μm ² , the Primary Coating root portions spread excessively, and the Primary Coating root portions penetrate into deep portions within the steel sheet. In this case, the root portions of the primary coating prevent secondary recrystallization and movement of domain boundaries, and the magnetic properties deteriorate. Therefore, the numerical density ND of Al oxides is 0.03-0.2/μm ² . The preferred lower limit of ND number density of Al oxides is 0.035/μm ² , preferably 0.04/μm ² . The preferred upper limit of ND number density is 0.15/μm ² , preferably 0.1/μm ² .

[0065]

The number density ND of Al oxides can be found in the following way: A glow discharge optical emission spectrometry analysis apparatus is used for glow discharge up to the D _{Al position of the Al} peak. Any area of 36 µm × 50 µm (observed area) in the discharge spots at the D _Al position of the Al peak is analyzed for elements by an energy dispersive X-ray spectroscope (EDS) method to create a map representing the characteristic X-ray intensity distribution in the observed area and identify Al oxides. . In particular, the area in which the intensity of the characteristic X-ray emission O is, according to the analysis, not less than 50% with respect to the maximum intensity of the characteristic X-ray emission O in the observed area, is identified as an oxide. In the identified oxide regions, the region in which the intensity of the characteristic X-ray emission of Al is, according to the analysis, not less than 30% with respect to the maximum intensity of the characteristic X-ray emission of Al, is identified as Al oxide. The identified Al oxides are mainly spinel. Of the identified Al oxides, the number of Al oxides with dimensions of at least 0.2 μm in the diameter of an area-equivalent circle is counted, and the number density ND of Al oxides (/μm ² ) is found by the following formulas:

Diameter of area-equivalent circle=√(4/p⋅(area of regions identified as Al oxides (area per analysis point on a map representing the characteristic X-ray intensity distribution × number of analysis points corresponding to regions identified as Al oxides))

Area per analysis point on a map representing the characteristic X-ray intensity distribution = area of mapping area ÷ number of analysis points

ND=Number of identified Al oxides with an area-equivalent circle diameter of at least 0.2 µm/observed area

[0066]

If the total content of Y, La and Ce in the primary coating is 0.001-4.0%, and the total content of Ti, Hf, and Zr in the primary coating is 0.0005-8.0%, then the D _{Al position of the Al} peak becomes 2 ,0-12.0 µm, and the numerical density ND of Al oxides in position D _{Al of the Al} peak takes on the value of 0.03-0.2/µm ² ,

[0067]

Preparation method

Next, one example of a method for manufacturing a grain-oriented electrical steel sheet according to the present invention will be described.

One example of a method for manufacturing a grain-oriented electrical steel sheet comprises a cold rolling process, a decarburization annealing process, and a finish annealing process. Below is a description of the processes.

[0068]

cold rolling process

In the cold rolling process, the hot rolled steel sheet is cold rolled to produce a cold rolled steel sheet. Hot rolled steel sheet has the following chemical composition.

[0069]

C: no more than 0.1%,

If the C content in the hot-rolled steel sheet exceeds 0.1%, the time required for decarburization annealing increases. In this case, production costs increase and productivity decreases. Therefore, the content of C in the hot-rolled steel sheet does not exceed 0.1%. The preferred upper limit of the C content in the hot rolled steel sheet is 0.092%, more preferably 0.085%. The lower limit of the C content in the hot-rolled steel sheet is 0.005%, the preferred lower limit is 0.02%, and the more preferable lower limit is 0.04%.

[0070]

Si: 2.5-4.5%,

As explained in the section on the chemical composition of the grain-oriented electrical steel sheet in the finished product, Si increases the electrical resistance of the steel, but, when present in excess, reduces the cold workability. If the Si content of the hot rolled steel sheet is 2.5% to 4.5%, the Si content of the grain oriented electrical steel sheet becomes 2.5% to 4.5% after the finish annealing process. The preferred upper limit of the Si content in the hot rolled steel sheet is 4.0%, and the more preferable upper limit is 3.8%. The preferable lower limit of the Si content in the hot rolled steel sheet is 2.6%, and the more preferable lower limit is 2.8%.

[0071]

Mn: 0.02-0.2%

As explained in the section on the chemical composition of grain oriented electrical steel sheet in the final product, during the manufacturing process, Mn binds with S and Se to form precipitates that act as inhibitors. Mn further enhances the hot workability of the steel. If the Mn content of the hot-rolled steel sheet is 0.02-0.2%, the Mn content of the grain-oriented electrical steel sheet after the finish annealing process becomes 0.02-0.2%. The preferred upper limit of the Mn content in the hot rolled steel sheet is 0.13%, and the more preferable upper limit is 0.1%. The preferred lower limit of the Mn content in the hot rolled steel sheet is 0.03%, and the more preferable lower limit is 0.04%.

[0072]

One or more elements selected from the group consisting of S and Se: in the amount of 0.005-0.07%

During the fabrication process, sulfur (S) and selenium (Se) bond with Mn to form MnS and MnSe. Both MnS and MnSe act as inhibitors necessary to suppress the growth of crystal grains 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%, the above effect is hardly achieved. On the other hand, if the total content of one or more elements selected from the group consisting of S and Se exceeds 0.07%, during the manufacturing process, secondary recrystallization does not occur, and the magnetic properties of the steel deteriorate. Therefore, in the hot-rolled steel sheet, the total content of one or more elements selected from the group consisting of S and Se is 0.005-0.07%. The preferred lower limit for the total content of one or more elements selected from the group consisting of S and Se is 0.008%, more preferably 0.016%. The preferred upper limit for the total content of one or more elements selected from the group consisting of S and Se is 0.06%, more preferably 0.05%.

[0073]

Soluble Al: 0.005-0.05%

During the fabrication process, aluminum (Al) bonds with N to form AlN. AlN acts as an inhibitor. If the content of soluble Al in the hot-rolled steel sheet is less than 0.005%, the above effect is not achieved. On the other hand, if the content of soluble Al in the hot-rolled steel sheet exceeds 0.05%, AlN coarsens. In this case, the action of AlN as an inhibitor is hindered, and secondary recrystallization is sometimes not caused. Therefore, the content of soluble Al in the hot-rolled steel sheet is 0.005-0.05%. The preferred upper limit of the content of soluble Al in the hot rolled steel sheet is 0.04%, more preferably 0.035%. The preferred lower limit of the content of soluble Al in the hot rolled steel sheet is 0.01%, more preferably 0.015%.

[0074]

N: 0.001-0.030%

During the manufacturing process, nitrogen (N) binds to Al to form AlN, which acts as an inhibitor. If the N content in the hot-rolled steel sheet is less than 0.001%, the above effect is not achieved. On the other hand, if the content of N in the hot-rolled steel sheet exceeds 0.030%, AlN coarsens. In this case, the action of AlN as an inhibitor is hindered, and secondary recrystallization is sometimes not caused. Therefore, the N content in the hot-rolled steel sheet is 0.001-0.030%. The preferred upper limit of the N content in the hot rolled steel sheet is 0.012%, more preferably 0.010%. The preferred lower limit of the N content in the hot rolled steel sheet is 0.005%, more preferably 0.006%.

[0075]

The rest of the chemical composition of the hot-rolled steel sheet of the present invention consists of Fe and impurities. In this case, "impurities" means the following elements that come from the ore used as raw materials, scrap metal or production environment, etc., during the industrial production of hot-rolled steel sheet, or whose content is allowed within the limits that do not adversely effect on the hot-rolled steel sheet of the present embodiment.

[0076]

On the question of optional elements

The hot-rolled steel sheet according to the present invention may further contain, instead of a portion of Fe, one or more elements selected from the group consisting of Cu, Sn and Sb, not more than 0.6% in total. All of these elements are optional elements.

[0077]

One or more elements selected from the group consisting of Cu, Sn and Sb: 0-0.6% in total

Copper (Cu), tin (Sn) and antimony (Sb) are optional elements and are not required in the composition. When contained in the composition, all of them, Cu, Sn and Sb increase the magnetic flux density in the grain oriented electrical steel sheet. If Cu, Sn and Sb are contained even in a small amount, the above effect is obtained to some extent. However, if the contents of Cu, Sn, and Sb exceed 0.6% in total, it becomes difficult to form an inner oxide layer during the decarburization annealing. In this case, the formation of the primary coating is also delayed during the finish annealing, which occurs by reacting the MgO from the annealing separator with the SiO _{2 of} the inner oxide layer. As a result, the adhesion of the formed primary coating is reduced. In addition, after the refining annealing, Cu, Sn and Sb easily remain in the form of impurity elements. As a result, the magnetic properties deteriorate. Therefore, the content of one or more elements selected from the group consisting of Cu, Sn and Sb is 0-0.6% in total. The preferred lower limit for the total content of one or more elements selected from the group consisting of Cu, Sn and Sb is 0.005%, more preferably 0.007%. The preferred upper limit for the total content of one or more elements selected from the group consisting of Cu, Sn and Sb is 0.5%, more preferably 0.45%.

[0078]

The hot-rolled steel sheet according to the present invention may further contain, instead of a portion of Fe, one or more elements selected from the group consisting of Bi, Te, and Pb, not more than 0.03% in total. All of these elements are optional elements.

[0079]

One or more elements selected from the group consisting of Bi, Te and Pb: 0-0.03% in total

Bismuth (Bi), Tellurium (Te) and Lead (Pb) are optional elements and are not required in the composition. When contained in the composition, all of them, Bi, Te and Pb increase the magnetic flux density of the grain oriented electrical steel sheet. If these elements are contained even in a small amount, the above effect is obtained to some extent. However, if the total content of these elements exceeds 0.03%, then, during finishing annealing, these elements are segregated on the surface, and the interface between the primary coating and the steel sheet is flattened. In this case, the adhesion of the primary coating coating is reduced. Therefore, the total content of one or more elements selected from the group consisting of Bi, Te and Pb is 0-0.03%. The preferred lower limit value for the total content of one or more elements selected from the group consisting of Bi, Te and Pb is 0.0005%, more preferably 0.001%. The preferred upper limit for the total content of one or more elements selected from the group consisting of Bi, Te and Pb is 0.02%, more preferably 0.015%.

[0080]

A hot-rolled steel sheet having the above chemical composition is produced by a known method. One example of a method for manufacturing a hot rolled steel sheet is given below. A slab having the same chemical composition as the above-mentioned hot-rolled steel sheet is produced. The slab is made using a known refining process and a casting process. The slab is heated. The heating temperature of the slab is, for example, higher than 1280°C to not higher than 1350°C. The heated slab is subjected to hot rolling to produce a hot-rolled steel sheet.

[0081]

The produced hot-rolled steel sheet is subjected to cold rolling to produce a cold-rolled steel sheet of a base steel sheet. Cold rolling may be performed in only one pass, or may be performed in multiple passes. When performing cold rolling in multiple passes, after performing cold rolling, a softening annealing process is performed, and then cold rolling is performed. By performing cold rolling in one pass or multiple passes, a cold-rolled steel sheet having a final product thickness (final product thickness) is produced.

[0082]

The degree of reduction of cold rolling in one pass or several passes of cold rolling is not less than 80%. In this case, the cold rolling reduction ratio (%) is determined as follows:

Cold rolling reduction ratio (%)={1-(thickness of cold rolled steel sheet after final cold rolling)/(thickness of hot rolled steel sheet before start of initial cold rolling)}×100

[0083]

It should be noted that the preferred upper limit of the cold rolling reduction ratio is 95%. In addition, before cold rolling the hot-rolled steel sheet, the hot-rolled steel sheet may be subjected to heat treatment or possibly pickling.

[0084]

Decarburizing Annealing Process

The steel sheet produced by the cold rolling process is subjected to decarburization annealing and, if necessary, nitriding annealing. The decarburization annealing is carried out in a known humid atmosphere containing hydrogen and nitrogen. Through decarburization annealing, the C concentration in the grain-oriented electrical steel sheet is reduced to no more than 50 ppm, which can eliminate magnetic aging. During decarburization annealing, primary recrystallization additionally occurs in the steel sheet, and the residual stress introduced by the cold rolling process is removed. In addition, during the decarburization annealing process, an inner oxide layer containing SiO ₂ as a main component is formed in the surface layer portion of the steel sheet. The annealing temperature for decarburization annealing is known. For example, the temperature is 750-950°C. The holding time at the annealing temperature is, for example, 1-5 minutes.

[0085]

Finishing annealing process

The steel sheet after the decarburization annealing process is subjected to a finishing annealing process. In the finishing annealing process, first, the surface of the steel sheet is coated with an aqueous slurry containing an annealing separator. The amount of coating is intended, for example, to cover 1 m ^{2 of} steel sheet with a density of 4-15 g/m ² or so per surface. The steel sheet coated with the aqueous suspension is put into a furnace at 400-1000°C and dried, then annealed (finish annealing).

[0086]

Aqueous suspension

An aqueous slurry is made by adding commercially pure water to an annealing separator, described later, and mixing. The ratio of annealing separator and commercial water can be adjusted to obtain the desired amount of coating during coating with a roller coater. For example, the ratio is preferably not less than 2 times and not more than 20 times. If the ratio of water to the annealing separator is less than 2 times, then the viscosity of the aqueous slurry will be too high, and the annealing separator cannot be evenly applied to the surface of the steel sheet, and therefore such a ratio is undesirable. If the ratio of water to annealing separator exceeds 20 times, then, in the subsequent drying process, the aqueous slurry will not dry sufficiently, and the water content remaining in the finish annealing will cause additional oxidation of the steel sheet, whereby the appearance of the primary coating will deteriorate, and so this ratio is undesirable.

[0087]

Annealing separator

In the present invention, the annealing separator used in the finishing annealing process contains magnesium oxide (MgO) and additives. MgO is the main component of the annealing separator. Here, "major component" means a component contained in an amount of at least 50 wt.% in some substance and preferably not less than 70 wt.%, preferably not less than 90 wt.%. The amount of the annealing separator applied to the steel sheet is, per side, for example, preferably not less than 2 g/m ² and not more than 10 g/m ² . If the amount of the annealing separator applied to the steel sheet is less than 2 g/m ² , the steel sheets will eventually stick to each other during finish annealing, and therefore such an amount is undesirable. If the amount of the annealing separator applied to the steel sheet exceeds 10 g/m ² , the production cost increases and therefore such an amount is undesirable.

The additives include at least one or more types of metal compounds selected from the group consisting of Y, La and Ce, and at least one or more types of metal compounds selected from the group consisting of Ti, Zr and Hf, while when the content of MgO in the annealing separator is 100 wt. hours, the total content of metal compounds selected from the group consisting of Y, La and Ce, converted into oxides, is 0.5-8.0 wt. including and the total content of metal compounds selected from the group consisting of Ti, Zr and Hf, converted into oxides, is 0.5-10.0 wt. including, in addition, the total amount of the total content of metal compounds selected from the group consisting of Y, La and Ce, converted to oxides, and the total content of metal compounds selected from the group consisting of Ti, Zr and Hf, converted to oxides , is 2.0-14.0 wt. hours, and, in addition, the ratio of the sum of the numbers of Ti, Zr and Hf atoms and the sum of the numbers of Y, La and Ce atoms contained in the annealing separator is 0.15-4.0. Next, additives in the annealing separator will be described in detail .

[0088]

Additives

The additives include at least one or more types of metal compounds selected from the group consisting of Y, La and Ce, and at least one or more types of metal compounds selected from the group consisting of Ti, Zr and hf. The contents of compounds of a metal selected from the group consisting of Y, La and Ce converted to oxides and the contents of compounds of a metal selected from the group consisting of Ti, Zr and Hf converted to oxides have the following meanings.

[0089]

Compounds of a metal selected from the group consisting of Y, La and Ce

Metal compounds selected from the group consisting of Ya, La and Ce ("Y, La and Ce compounds") are contained, converted to oxides, in a total concentration of 0.5-8.0 wt. hours, when determining the content of MgO as 100 wt. hours in the annealing separator. In the present description, some one type of Y, Ya and Ce compound contained in the annealing separator is referred to as M _RE . The W _RE content (in parts by weight) of the oxide-converted M _RE compound in the annealing separator has the following meaning.

W _RE =(amount of additive M _RE (wt. %))/(molecular weight M _RE )×((molecular weight Y ₂ O ₃ )×(number of Y atoms per molecule M _RE /2)+(molecular weight La ₂ O ₃ )×(number of La atoms per molecule M _RE /2)+(molecular weight of CeO ₂ )×(number of Ce atoms per molecule M _RE ))

In addition, with regard to M _RE , the ratio x _RE of the sum of the numbers of Y, La, and Ce atoms to the number of Mg atoms contained in the annealing separator has the following meaning.

x _RE =((number of Y atoms per molecule M _RE )+(number of La atoms per molecule M _RE )+(number of Ce atoms per molecule M _RE ))×(amount of additive M _RE (wt. parts)/ molecular weight M _RE )×(molecular weight MgO/100)

Therefore, the total content of C _RE compounds of Y, La and Ce, converted into oxides, when determining the content of MgO as 100 wt.h. in an annealing separator to which one or two or more of Y, La, and Ce compounds are added (referred to below as "the C _RE content of Y, La, and Ce compounds converted into oxides"), and the ratio X _RE of the sum of the numbers of Y atoms, La and Ce to the number of Mg atoms in the annealing separator (referred to below as "the relative content X _RE of Y, La and Ce atoms") are, respectively, the sum W _RE and the sum x _RE of metal compounds selected from the group consisting of Ya, La and Ce contained in the annealing separator.

[0090]

"Y, La and Ce compounds" are compounds in which one or more of Y, La and Ce atoms are contained in the compound molecule, and, for example, are oxides and hydroxides, carbonates, sulfates, and the like, of which part or all are converted to oxides by the drying and finishing annealing explained later. The Y, La and Ce compounds inhibit the aggregation of the Primary Coating. The Y, La and Ce compounds additionally act as oxygen release sources. For this reason, the growth of the root parts of the primary coating formed by finishing annealing is promoted. As a result, the adhesion of the primary coating to the steel sheet is improved. If the content of C _RE compounds Y, La and Ce, converted into oxides, is less than 0.5 wt. h., then the above effect is not achieved sufficiently. On the other hand, if the content of C _RE compounds of Y, La and Ce converted into oxides exceeds 8.0 wt. h., then the root parts of the primary coating are excessively distributed. In this case, the roots of the primary coating will inhibit the movement of the domain boundaries, and therefore the magnetic properties are degraded. If the content of C _RE compounds Y, La and Ce, converted into oxides, exceeds 8.0 wt. hours, then the content of MgO in the annealing separator is further reduced, and therefore the formation of Mg ₂ SiO ₄ is inhibited. That is, the reactivity is reduced. Therefore, the content of C _RE compounds of Y, La and Ce, converted into oxides, is 0.5-8.0 wt. hours (per 100 parts by weight MgO). The preferred lower limit of the content of C _RE compounds of Y, La and Ce, converted into oxides, equal to 0.8 wt. hours, preferably 1.2 wt. h. The preferred upper limit of the content of C _RE compounds of Y, La and Ce, converted into oxides, equal to 7.0 wt. hours, preferably 6.5 wt. h..

[0091]

Compounds of a metal selected from the group consisting of Ti, Zr and Hf

Metal compounds selected from the group consisting of Ti, Zr and Hf (“Ti, Zr and Hf compounds”) are contained, converted to oxides, in a total concentration of 0.5-10.0 wt. hours, when determining the content of MgO as 100 wt. hours in the annealing separator. In the present description, some one type of Ti, Zr and _Hf compound contained in the annealing separator is referred to as M _G4 .

W _G4 =(amount of addition of M _G4 (wt. parts))/(molecular weight of M _G4 )×((molecular weight of TiO ₂ )×(number of Ti atoms per molecule of M _G4 )+(molecular weight of ZrO ₂ )×( number of Zr atoms per molecule of M _G4 )+(molecular weight of HfO ₂ )×(number of Hf atoms per molecule of M _G4 ))

In addition, with regard to M _G4 , the ratio x _G4 of the sum of the numbers of Ti, Zr, and Hf atoms to the number of Mg atoms contained in the annealing separator has the following meaning.

x _G4 =((number of Ti atoms per molecule M _G4 )+(number of Zr atoms per molecule M _G4 )+(number of Hf atoms per molecule M _G4 ))×(amount of additive M _G4 (wt. parts)/ molecular weight M _G4 )×(molecular weight MgO/100)

Therefore, the total content of C _G4 compounds of Ti, Zr and Hf converted into oxides, when determining the content of MgO as 100 wt. h. in an annealing separator to which one or two or more of Ti, Zr and Hf compounds are added (referred to below as "C _G4 content of Ti, Zr and Hf compounds converted into oxides"), and the ratio X _G4 of the sum of the numbers of atoms Ti, Zr and Hf to the number of Mg atoms in the annealing separator (referred to below as "the relative content X _G4 of Ti, Zr and Hf atoms") are respectively the sum of W _G4 and the sum x _G4 of compounds of a metal selected from the group consisting of Ti, Zr and Hf contained in the annealing separator.

[0092]

"Ti, Zr and Hf compounds" are compounds in which one or more of Ti, Zr and Hf atoms are contained in the compound molecule, and, for example, are oxides and hydroxides, phosphates, etc., from which part or all of which is converted into oxides as a result of drying and finishing annealing explained later. The Ti, Zr and Hf compounds, when included in the annealing separator together with the Y, La and Ce compounds, react with a part of the Y, La and Ce compounds during the finish annealing to form complex oxides. If complex oxides are formed, then, compared to when only Y, La, and Ce compounds are contained, the oxygen generation capacity of the annealing separator can be improved. For this reason, by including Ti, Zr, and Hf compounds instead of Y, La, and Ce compounds, it is possible to suppress the deterioration of magnetic properties that accompanies the inclusion of an excess of Y, La, and Ce compounds, while promoting the growth of the roots of the primary coating and increasing adhesion of the primary coating to the steel sheet. If the content of C _G4 compounds of Ti, Zr and Hf, converted into oxides, is less than 0.5 wt. h., then the above effect is not achieved sufficiently. On the other hand, if the content of C _G4 compounds of Ti, Zr and Hf converted into oxides exceeds 10.0 wt. h., then the root parts of the primary coating are excessively spread, and the magnetic properties sometimes deteriorate. If the content of C _G4 compounds of Ti, Zr and Hf, converted into oxides, exceeds 10.0 wt. hours, then the content of MgO in the annealing separator is further reduced, and therefore the formation of Mg ₂ SiO ₄ is inhibited. That is, the reactivity is reduced. If the content of C _G4 compounds of Ti, Zr and Hf, converted into oxides, is 0.5-10.0 wt. hours, the deterioration of the magnetic properties and the decrease in reactivity can be suppressed, while the adhesion of the primary coating to the base steel sheet can be improved.

[0093]

The preferred lower limit of the relative X _G4 content of Ti, Zr and Hf atoms is 0.8 wt. hours, preferably 1.5 wt. h. The preferred upper limit of the relative content of X _G4 atoms Ti, Zr and Hf is equal to 8.0 wt. hours, preferably 7.5 wt. h.

[0094]

X ratio _RE /X _G4 in the annealing separator

The ratio of the sum of the numbers of Ti, Zr and Hf atoms and the sum of the numbers of Y, La and Ce atoms contained in the annealing separator (hereinafter referred to as "X _RE /X _G4 ") is in the range of 0.15-4.00. If X _RE /X _G4 is less than 0.15, then, during finishing annealing, the growth of the roots of the primary coating is not promoted. As a result, the adhesion of the primary coating to the steel sheet is reduced. On the other hand, even if X _RE /X _G4 exceeds 4.00, the adhesion is reduced. As a result, the adhesion of the primary coating to the steel sheet is reduced. If X _RE /X _G4 is 0.15-4.00, then the adhesion of the primary coating to the steel sheet is increased. The preferred lower limit of X _RE /X _G4 is 0.25, more preferably 0.50. The preferred upper limit of X _RE /X _G4 is 3.00, more preferably 2.50,

[0095]

N _RE and N _G4 in the annealing separator

The number density N _RE of particles with a particle size of at least 0.1 µm of the metal compounds selected from the group consisting of Y, La and Ce contained in the annealing separator, and the number density N _G4 of particles with a particle size of at least 0.1 µm of the compounds metal selected from the group consisting of Ti, Zr and Hf, respectively, are not less than 2000000000/g. The particle sizes of these metal compounds are found as the equivalent sphere diameter calculated by volume, and are found from the particle size distribution based on the number of particles obtained by measuring the starting powder material with a laser diffraction particle size distribution measuring device.

In this case, "particle size distribution based on the number of particles" represents the frequency of existence (%) relative to the total number of particles for particles in different groups after dividing into 30 or more groups of equal width on a logarithmic scale, with the particle size range having any a value in the range of 0.1-0.15 µm as the minimum size, and any value in the range of 2000-4000 µm as the maximum value. In this case, the representative size D of the particles in each group is found by the formula

D=10 ^∧ ((LogD _MAX +LogD _MIN )/2),

using the upper limit value D _MAX [µm] and the lower limit value D _MIN [µm] of the respective groups.

In addition, the weight w [g] of particles of each group in 100 particles of the starting powder material is found by the formula

w=f⋅d⋅(D ^∧ 3⋅π)/6,

using the frequency of existence "f" in relation to all particles, the representative size D [μm] of the particles, and the specific gravity "d" [g/μm ³ ] of the metal compound.

The sum W [g] of the "w" weights of all groups is the average weight of 100 particles of the initial powder material, and therefore the number of particles "n" [/g] in 1 g of the metal compound powder is found by the formula

n=100/W.

When finding the number density N _RE of particles with particle sizes of at least 0.1 μm of metal compounds selected from the group consisting of Y, La and Ce, calculate the number "n" of particles in 1 g of powders of metal compounds in the initial powder material, and the content "c" (%) of the respective metal compounds in suspension and the sum C (%) of all the contents of "c" is used to find the mentioned density according to the formula:

N _RE =∑(n⋅c/C).

The number density N _G4 of particles with a particle size of at least 0.1 μm of metal compounds selected from the group consisting of Ti, Zr and Hf, is found in a similar way.

If N _RE or N _G4 is less than 2000000000/g, then, at the time of finish annealing, the root growth effect of the primary coating becomes uneven, and there are regions in which root growth is insufficiently promoted. As a result, the adhesion of the Primary Coating to the steel sheet is not sufficiently achieved. If N _RE and N _G4 are not less than 2000000000/g, then the adhesion of the primary coating is increased. Y, La and Ce and Ti, Zr and Hf compounds, etc. emit oxygen during finishing annealing. Y, La and Ce compounds emit oxygen little by little from low temperature to high temperature. On the other hand, the Ti, Zr, and Hf compounds can be expected to emit oxygen for relatively short periods of time, but can be expected to promote oxygen evolution by the Y, La, and Ce compounds and continue to inhibit the aggregation of the inner oxide layer needed to form the coating. For this reason, by increasing the number densities of N _RE and N _G4 to build up the state of dispersion in the separator bed, it is assumed that oxygen evolution interaction can be effectively achieved. It should be noted that the particle size is the diameter of a sphere equivalent in volume.

[0096]

Optional components of the annealing separator

The above-described annealing separator may further comprise, if necessary, one or two or more types of metal compounds selected from the group consisting of Ca, Sr and Ba (“Ca, Sr and Ba compounds”) with the ratio of the sum of the numbers of Ca, Sr atoms and Ba to the number of Mg atoms contained in the annealing separator is less than 0.025,

[0097]

When the content of metal compounds selected from the group consisting of Ca, Sr and Ba, Ca, Sr and Ba compounds is less than 0.025 in relation to the sum of the numbers of Ca, Sr and Ba atoms to the number of Mg atoms contained in the annealing separator. In the present specification, one type of Ca, Sr, or Ba compound in the annealing separator may be referred to as M _AM , and the ratio x _AM of the sum of the Ca, Sr, and Ba atoms of the M _AM compound to the number of Mg atoms contained in the annealing separator can be found from the following formula:

x _AM =((number of Ca atoms per molecule M _AM )+(number of Sr atoms per molecule M _AM )+(number of Ba atoms per molecule M _AM ))×(amount of additive M _AM (wt. parts)/ molecular weight M _AM )/(100/molecular weight MgO)

Therefore, the ratio x _AM of the sum of Ca, Sr, and Ba atoms to the number of Mg atoms contained in the annealing separator to which one or more types of Ca, Sr, and Ba compounds are added (referred to below as "the relative abundance X _AM of Ca, Sr, and Ba atoms ”) is the sum of the X _AM values of all types of added Ca, Sr and Ba compounds.

[0098]

The Ca, Sr and Ba compounds are, for example, oxides and hydroxides, sulfates, phosphates, borates and the like, of which some or all are converted to oxides by the drying and finish annealing explained later. Ca, Sr and Ba compounds lower the reaction temperature between MgO in the annealing separator and SiO ₂ in the surface layer of the steel sheet in finish annealing and promote the formation of Mg ₂ SiO ₄ , If at least one or more of Ca, Sr and Ba are contained even in a small concentration, the above effect is obtained to some extent. On the other hand, if the relative X _AM content of Ca, Sr, and Ba atoms is not less than 0.025, then the reaction of MgO and SiO ₂ , on the contrary, is suppressed, and the formation of Mg ₂ SiO ₄ is inhibited. That is, the reactivity is reduced. If the X _AM ratio of Ca, Sr, and Ba atoms is less than 0.025, the formation of Mg ₂ SiO ₄ is promoted upon finishing annealing.

[0099]

Manufacturing conditions during finishing annealing

The finishing annealing process is carried out under the following conditions, for example: Drying is performed before finishing annealing. First, the surface of the steel sheet is coated with an aqueous slurry of the annealing separator. The steel sheet with the annealing separator coated on the surface is placed in an oven maintained at 400-1000° C. and kept in the oven (dried). As a result, the annealing separator applied to the surface of the steel sheet is dried. The holding time is, for example, 10-90 seconds.

[0100]

After the annealing separator is dried, finish annealing is performed. In the finish annealing, the annealing temperature is set to, for example, 1150-1250°C, and the base steel sheet (cold-rolled steel sheet) is held. The holding time is, for example, 15-30 hours. The atmosphere inside the finish annealing furnace is a known atmosphere.

[0101]

In the grain-oriented electrical steel sheet manufactured according to the above-described manufacturing process, a primary coating containing Mg ₂ SiO ₄ as its main component is formed. In addition, the position D _Al of the Al peak is in the range of 2.0-12.0 µm from the surface of the Primary Coating. In addition, the numerical density ND of Al oxides is in the range of 0.03-0.2/μm ² .

[0102]

It should be noted that, due to the decarburization annealing process and the finish annealing process, the elements of the chemical composition of the hot-rolled steel sheet are removed to some extent from the steel constituents. Changing the composition (and process) during the finishing annealing process is sometimes referred to as "refining (annealing)". In addition to Sn, Sb, Bi, Te, and Pb used to control the crystal orientation, S, Al, N, and the like, which act as inhibitors, are largely removed. For this reason, compared with the chemical composition of the hot-rolled steel sheet, the contents of elements in the chemical composition of the base steel sheet in the grain-oriented electrical steel sheet become lower as described above. By using a hot-rolled steel sheet with the above-described chemical composition to carry out the above-described manufacturing method, it is possible to produce a grain-oriented electrical steel sheet containing a base steel sheet with the above-described chemical composition.

[0103]

Secondary Coating Process

In one example of a method for manufacturing a grain-oriented electrical steel sheet according to the present invention, after the finish annealing process, a secondary coating forming process may be additionally performed. In the secondary coating forming process, the surface of the grain-oriented electrical steel sheet is coated with an insulating coating substance mainly composed of colloidal silicon dioxide and phosphate after the temperature is lowered by finishing annealing, followed by hot drying. As a consequence, a secondary coating of high-strength insulating coating is formed on the primary coating.

[0104]

Machining process for splitting magnetic domains

The grain-oriented electrical steel sheet according to the present invention can be further subjected to a magnetic domain breaking treatment after a finishing annealing process or a secondary coating process. In the processing for breaking magnetic domains, the surface of a grain-oriented electrical steel sheet is treated with a scanning laser beam to break up magnetic domains or form grooves on the surface. In this case, it is possible to produce a grain-oriented electrical steel sheet with further improved magnetic properties.

EXAMPLES

[0105]

Below, using examples, aspects of the present invention will be specifically set forth. These examples are illustrative of the beneficial effects of the present invention and do not limit the present invention.

[0106]

Example 1

Production of Grain-Oriented Electrical Steel Sheet

Molten steels each having the chemical compositions shown in Table 1 were produced in a vacuum melting furnace. The resulting molten steel was used to make a slab by continuous casting.

[0107]

[Table 1]

TABLE 1

Steel type Chemical composition (units: wt.%, balance of Fe and impurities) C Si Mn S Se S+Se soluble Al N sn Sb Bi Te Pb A 0.080 3.3 0.080 0.022 - 0.022 0.025 0.008 - - - - - B 0.080 3.5 0.077 - 0.044 0.044 0.025 0.008 - - - - - C 0.080 3.2 0.080 0.019 0.003 0.022 0.025 0.008 0.1 - - - - D 0.080 3.3 0.080 0.018 0.003 0.022 0.026 0.008 - 0.08 - - - E 0.080 3.3 0.080 0.020 0.006 0.026 0.025 0.008 - - 0.0017 - - F 0.080 3.2 0.075 0.021 0.002 0.023 0.025 0.008 - - - 0.001 - G 0.080 3.3 0.080 0.019 0.003 0.022 0.025 0.008 - - - - 0.0012

[0108]

The slab was heated at 1350°C. The heated slab was subjected to hot rolling to produce a hot-rolled steel sheet having a thickness of 2.3 mm. The chemical composition of the hot rolled steel sheet was the same as that of the molten steel and is listed in Table 1,

[0109]

The hot-rolled steel sheet was subjected to an annealing treatment, then the hot-rolled steel sheet was subjected to pickling. The annealing processing conditions of the hot-rolled steel sheet and the pickling conditions of the hot-rolled steel sheet were set to be the same in each of the numbered tests.

[0110]

The pickled hot-rolled steel sheet was subjected to cold rolling to obtain a cold-rolled steel sheet having a thickness of 0.22 mm. In each of the numbered tests, the cold rolling reduction ratio was 90.4%.

[0111]

The cold-rolled steel sheet was annealed by performing primary recrystallization annealing, which is also a decarburization annealing. The annealing temperature at the primary recrystallization annealing was 900-1120° C. in each of the numbered tests. The holding time at the annealing temperature was 2 minutes.

[0112]

The cold-rolled steel sheet after primary recrystallization annealing was coated with an aqueous slurry and dried to apply an annealing separator with a coverage ratio of 5 g/m ² to one surface. It should be noted that an aqueous suspension was prepared by mixing an annealing separator (source powder material) and commercially pure water in a mixing ratio of 1:2. The annealing separator contained MgO and additives shown in Table 2. It should be noted that the content of C _RE for Y, La and Ce in the annealing separator shown in Table 2 means the total content of Y, La and Ce compounds converted into oxides, when determining MgO content as 100 wt.h. in the annealing separator. Similarly, the relative abundance X _RE of Y, La and Ce atoms shown in Table 2 means the ratio of the sum of the numbers of Y, La and Ce atoms to the number of Mg atoms contained in the annealing separator. Similarly, the content of C _G4 for Ti, Zr and Hf in the annealing separator shown in Table 2 means the total content of Ti, Zr and Hf converted into oxides, when the MgO content is defined as 100 parts by weight. in the annealing separator. Similarly, the relative content X _G4 of Ti, Zr and Hf atoms shown in Table 2 means the ratio of the sum of the numbers of Ti, Zr and Hf atoms to the number of Mg atoms contained in the annealing separator. Similarly, the number density N _RE for Y, La and Ce shown in Table 2 means the number density in the starting powder material for particles with particle sizes of at least 0.1 µm of a metal compound selected from the group consisting of Y, La and Ce, in an annealing separator until it becomes an aqueous suspension. Similarly, the number density N _G4 for Ti, Zr and Hf, shown in Table 2, means the number density in the starting powder material for particles with a particle size of at least 0.1 μm of a metal compound selected from the group consisting of Ti, Zr and Hf , in an annealing separator until it becomes an aqueous suspension. It should be noted that the particle size is the diameter of a sphere equivalent in volume.

[0113]

[Table 2]

TABLE 2 Test No. Hot rolled steel type
steel sheet Additives in the annealing separator (parts by weight per 100 parts by weight MgO) Notes Content
Y ₂ O ₃
((parts by weight per 100 parts by weight MgO) Content
_{La2O3 _}
(parts by weight per 100 parts by weight MgO) Content
CeO ₂
(parts by weight per 100 parts by weight MgO) Content
_TiO2
(parts by weight per 100 parts by weight MgO) Content
_ZrO2
(parts by weight per 100 parts by weight MgO) Content
_HfO2
(parts by weight per 100 parts by weight MgO) Content
C _RE for
Y, La, Ce
(parts by weight per 100 parts by weight MgO) Content
C _G4 for
Ti, Zr, Hf
(parts by weight per 100 parts by weight MgO) Total content
C _RE +C _G4
(parts by weight per 100 parts by weight MgO) X _RE
/X _G4 Number Density
N _RE for
Y, La, Ce
(100000000/g) Number Density
N _G4 for
Ti, Zr, Hf
(100000000/g) one A 0.00 0.00 0.00 1.50 0.00 0.00 0.00 1.50 1.50 0.00 - 30.8 Comparative approx. 2 A 0.00 0.00 0.00 0.00 1.00 0.50 0.00 1.50 1.50 0.00 - 35.5 Comparative approx. 3 A 0.00 0.00 0.00 0.50 0.00 1.20 0.00 1.70 1.70 0.00 - 31.8 Comparative approx. four A 0.20 0.00 0.00 0.00 1.60 0.00 0.20 1.60 1.80 0.14 41.5 32.5 Comparative approx. 5 A 0.00 0.30 0.00 0.00 1.60 0.00 0.30 1.60 1.90 0.14 63.2 35.4 Comparative approx. 6 A 0.15 0.00 0.05 1.00 0.00 0.50 0.20 1.50 1.70 0.11 52.1 32.6 Comparative approx. 7 A 0.15 0.15 0.00 1.00 0.00 0.50 0.30 1.50 1.80 0.15 42.9 52.0 Comparative approx. eight A 0.00 0.25 0.15 0.00 0.00 1.50 0.40 1.50 1.90 0.34 125.4 32.8 Comparative approx. 9 A 0.60 0.00 0.00 0.00 0.00 0.00 0.60 0.00 0.60 - 166.8 - Comparative approx. ten A 0.00 0.00 0.00 0.00 2.00 2.00 0.00 4.00 4.00 0.00 194.2 62.4 Comparative approx. eleven A 0.40 0.00 0.00 1.80 0.00 0.00 0.40 1.80 2.20 0.16 305.4 50.4 Comparative approx. 12 A 0.30 0.00 0.15 0.00 1.70 2.00 0.45 3.70 4.15 0.15 331.8 91.5 Comparative approx. 13 A 0.00 0.00 0.50 1.00 0.50 0.00 0.50 1.50 2.00 0.18 309.5 50.9 Note. fig. fourteen A 3.60 0.00 0.00 0.00 0.00 0.20 3.60 0.20 3.80 33.54 504.2 62.4 Comparative approx. fifteen A 3.20 0.00 1.20 0.30 0.10 0.00 4.40 0.40 4.80 7.73 508.6 60.3 Comparative approx. 16 A 0.00 0.00 0.00 4.00 0.00 0.00 0.00 4.00 4.00 0.00 - 184.5 Comparative approx. 17 A 0.00 0.33 0.00 0.00 4.00 0.00 0.33 4.00 4.33 0.06 708.4 193.5 Comparative approx. eighteen A 3.00 0.00 0.00 0.60 0.00 0.00 3.00 0.60 3.60 3.54 1065.5 192.5 Note. fig. 19 B 0.00 2.00 0.00 6.00 0.00 0.00 1.80 6.00 7.80 0.16 2042.5 184.5 Note. fig. twenty B 0.00 4.00 0.00 0.00 0.00 0.00 4.00 0.00 4.00 - 2049.5 - Comparative approx. 21 B 0.00 0.00 0.00 6.00 3.00 0.00 0.00 9.00 9.00 0.00 4066.5 305.4 Comparative approx. 22 B 1.20 1.20 0.00 11.00 0.00 0.00 2.40 11.00 13.40 0.13 4025.5 405.3 Comparative approx. 23 B 0.50 0.30 1.00 0.00 11.00 1.00 1.80 12.00 13.80 0.13 3099.8 606.2 Comparative approx. 24 B 0.00 0.00 6.00 0.80 0.00 0.00 6.00 0.80 6.80 3.48 1088.6 801.5 Note. fig. 25 B 6.20 0.00 0.00 0.00 0.00 2.80 6.20 2.80 9.00 4.13 2088.4 1624.2 Comparative approx. 26 B 0.00 0.00 7.50 0.70 0.00 0.00 7.50 0.70 8.20 4.97 2099.5 1929.5 Comparative approx. 27 B 0.00 0.00 7.00 0.00 1.20 0.00 7.00 1.20 8.20 4.18 3085.6 1355.5 Comparative approx. 28 B 0.00 0.00 6.00 0.00 0.00 0.00 6.00 0.00 6.00 - 3045.2 - Comparative approx. 29 B 3.00 3.00 0.00 4.00 0.00 2.00 6.00 6.00 12.00 0.76 5044.2 317.6 Note. fig. thirty B 0.00 3.00 3.00 2.00 0.00 5.00 6.00 7.00 13.00 0.73 7088.4 391.0 Note. fig. 31 B 5.00 0.00 5.00 3.00 3.00 0.00 10.00 6.00 16.00 1.18 68.5 405.5 Comparative approx. 32 B 0.00 0.00 9.00 2.00 2.00 0.00 9.00 4.00 13.00 1.27 67.2 55.5 Comparative approx. 33 B 0.00 3.20 0.00 2.00 3.00 5.50 3.20 10.50 13.70 0.26 55.4 103.5 Comparative approx. 34 B 1.20 0.00 0.00 0.30 0.00 0.00 1.20 0.30 1.50 2.83 59.0 219.6 Comparative approx. 35 B 0.70 0.00 0.00 4.20 0.00 0.00 0.70 4.20 4.90 0.12 60.2 405.5 Comparative approx. 36 B 0.60 0.00 0.00 0.00 0.00 8.00 0.60 8.00 8.60 0.14 61.8 992.5 Comparative approx. 37 B 0.00 0.00 2.00 6.50 0.00 0.00 2.00 6.50 8.50 0.14 63.2 1084.2 Comparative approx. 38 B 0.00 0.00 0.80 0.50 3.50 0.00 0.80 4.00 4.80 0.13 68.8 516.6 Comparative approx. 39 B 0.00 0.20 0.30 0.00 2.00 2.00 0.50 4.00 4.50 0.12 276.3 53.5 Comparative approx. 40 B 0.00 0.80 0.00 0.00 0.80 0.00 0.80 0.80 1.60 0.76 594.3 94.5 Comparative approx. 41 B 0.00 7.00 0.00 4.00 0.00 4.00 7.00 8.00 15.00 0.62 913.5 21.5 Comparative approx. 42 B 0.75 0.00 0.00 0.00 0.00 7.80 0.75 7.80 8.55 0.18 55.4 305.4 Note. fig. 43 B 0.00 0.00 3.50 9.80 0.00 0.00 3.50 9.80 13.30 0.17 102.5 40.6 Note. fig. 44 B 0.00 0.00 7.80 1.00 0.00 0.00 7.80 1.00 8.80 3.62 88.4 90.8 Note. fig. 45 C 3.20 0.00 0.00 0.50 2.00 0.00 3.20 2.50 5.70 1.26 203.5 21.5 Note. fig. 46 D 0.00 3.00 0.00 0.00 2.00 1.00 3.00 3.00 6.00 0.88 2044.5 1657.5 Note. fig. 47 E 0.00 0.00 4.00 2.00 0.00 3.00 4.00 5.00 9.00 0.59 20.9 21.5 Note. fig. 48 F 1.50 0.00 1.50 1.50 0.00 2.00 3.00 3.50 6.50 0.78 201.9 30.8 Note. fig. 49 G 0.00 1.50 3.00 2.80 3.00 0.00 4.50 5.80 10.30 0.45 4052.1 40.8 Note. fig. fifty A 2.50 0.00 0.00 0.00 1.50 0.00 2.50 1.50 4.00 0.38 19.0 62.6 Comparative approx. 51 B 1.20 0.00 1.20 0.00 1.80 0.00 2.40 1.80 4.20 0.81 18.4 71.6 Comparative approx. 52 A 0.00 2.00 0.00 1.20 0.00 1.80 2.00 3.00 5.00 0.24 17.3 79.6 Comparative approx. 53 B 1.50 0.00 1.40 1.80 1.20 0.00 2.90 3.00 5.90 0.93 16.8 54.9 Comparative approx. 54 A 0.00 4.20 0.00 5.00 0.00 0.00 4.20 5.00 9.20 0.72 66.8 17.5 Comparative approx. 55 B 0.00 1.50 1.90 0.00 0.00 4.50 3.40 4.50 7.90 0.20 302.4 16.2 Comparative approx. 56 A 1.80 0.00 0.00 1.80 3.20 0.00 1.80 5.00 6.80 0.82 4006.5 5.8 Comparative approx. 57 B 0.00 1.80 1.20 0.00 1.50 1.40 3.00 2.90 5.90 0.42 9811.5 12.5 Comparative approx.

[0114]

The cold-rolled steel sheet, on the surface of which the aqueous slurry was applied, was placed, in each of the numbered tests, in an oven at 900° C. for 10 seconds to dry the aqueous slurry. After drying, finishing annealing was performed. At the finish anneal, in each of the numbered tests, the sheet was held at 1200° C. for 20 hours. Through the above-described manufacturing process, a grain-oriented electrical steel sheet containing a base steel sheet and a primary coating was produced.

[0115]

Measurement of the number density of particles in the initial powder material

The starting powder material was measured to obtain particle size distribution data by quantity using a laser diffraction particle size distribution measurement device (Model: SALD-3000, Shimadzu Corporation). The number of particles in 1 g was calculated.

[0116]

Analysis of the Chemical Composition of the Base Steel Sheet in Grain-Oriented Electrical Steel Sheet

Base steel sheets of the produced grain oriented electrical steel sheets in test No. 1-57 were subjected to alkali cleaning and mild pickling to remove the primary coating and the outermost layer of the steel sheet, and then examined by spark optical emission spectrometry and atomic absorption spectrometry to determine the chemical compositions. The found chemical compositions are shown in Table 3.

[0117]

[Table 3]

TABLE 3 Test No. Chemical composition (units: wt.%, balance of Fe and impurities) C Si Mn S Se S+Se soluble Al N sn Sb Bi Te Pb one 0.0005 3.3 0.077 0.001 <0.0005 <0.0015 0.002 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 2 0.0005 3.3 0.078 0.001 <0.0005 <0.0015 0.001 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 3 0.0005 3.3 0.077 0.001 <0.0005 <0.0015 0.002 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 four 0.0005 3.2 0.079 0.001 <0.0005 <0.0015 0.001 0.003 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 5 0.0005 3.3 0.077 0.001 <0.0005 <0.0015 0.001 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 6 0.0005 3.3 0.078 0.001 <0.0005 <0.0015 0.001 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 7 0.0005 3.3 0.078 0.001 <0.0005 <0.0015 0.002 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 eight 0.0005 3.2 0.076 0.001 <0.0005 <0.0015 0.001 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 9 0.0005 3.2 0.077 0.001 <0.0005 <0.0015 0.002 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 ten 0.0005 3.2 0.076 0.001 <0.0005 <0.0015 0.003 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 eleven 0.0005 3.3 0.077 0.001 <0.0005 <0.0015 0.002 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 12 0.0005 3.3 0.077 0.001 <0.0005 <0.0015 0.002 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 13 0.0005 3.2 0.077 0.001 <0.0005 <0.0015 0.003 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 fourteen 0.0005 3.3 0.08 0.001 <0.0005 <0.0015 0.002 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 fifteen 0.0005 3.3 0.077 0.001 <0.0005 <0.0015 0.002 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 16 0.0005 3.3 0.076 0.001 <0.0005 <0.0015 0.002 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 17 0.0005 3.2 0.079 0.001 <0.0005 <0.0015 0.003 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 eighteen 0.0005 3.3 0.077 0.001 <0.0005 <0.0015 0.002 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 19 0.0005 3.4 0.079 0.001 <0.0005 <0.0015 0.003 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 twenty 0.0005 3.5 0.080 0.001 <0.0005 <0.0015 0.002 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 21 0.0005 3.5 0.079 0.001 <0.0005 <0.0015 0.002 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 22 0.0005 3.4 0.077 <0.0005 0.001 <0.0015 0.003 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 23 0.0005 3.5 0.077 <0.0005 0.001 <0.0015 0.003 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 24 0.0005 3.4 0.074 <0.0005 0.001 <0.0015 0.002 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 25 0.0005 3.4 0.074 <0.0005 0.001 <0.0015 0.002 0.003 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 26 0.0005 3.4 0.075 <0.0005 0.001 <0.0015 0.003 0.003 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 27 0.0005 3.3 0.077 <0.0005 0.001 <0.0015 0.003 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 28 0.0005 3.4 0.075 <0.0005 0.001 <0.0015 0.002 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 29 0.0005 3.4 0.075 <0.0005 0.001 <0.0015 0.002 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 thirty 0.0005 3.5 0.077 <0.0005 0.001 <0.0015 0.002 0.003 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 31 0.0005 3.5 0.075 <0.0005 0.001 <0.0015 0.003 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 32 0.0005 3.4 0.076 <0.0005 0.001 <0.0015 0.002 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 33 0.0005 3.4 0.074 <0.0005 0.001 <0.0015 0.003 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 34 0.0005 3.4 0.073 <0.0005 0.001 <0.0015 0.003 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 35 0.0005 3.4 0.077 <0.0005 0.001 <0.0015 0.003 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 36 0.0005 3.4 0.075 <0.0005 0.001 <0.0015 0.002 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 37 0.0005 3.5 0.075 <0.0005 0.001 <0.0015 0.003 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 38 0.0005 3.5 0.078 <0.0005 0.001 <0.0015 0.002 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 39 0.0005 3.3 0.077 <0.0005 0.001 <0.0015 0.002 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 40 0.0005 3.4 0.076 <0.0005 0.001 <0.0015 0.002 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 41 0.0005 3.4 0.075 <0.0005 0.001 <0.0015 0.002 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 42 0.0005 3.4 0.077 <0.0005 0.001 <0.0015 0.003 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 43 0.0005 3.5 0.075 <0.0005 0.001 <0.0015 0.002 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 44 0.0005 3.3 0.077 <0.0005 0.001 <0.0015 0.003 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 45 0.0005 3.2 0.077 0.001 0.001 0.002 0.002 0.002 0.0200 <0.0005 <0.0005 <0.0005 <0.0005 46 0.0005 3.3 0.080 0.001 0.001 0.002 0.002 0.001 <0.0005 0.0010 <0.0005 <0.0005 <0.0005 47 0.0005 3.3 0.076 0.001 0.001 0.002 0.003 0.002 <0.0005 <0.0005 0.0008 <0.0005 <0.0005 48 0.0005 3.2 0.072 0.001 0.001 0.002 0.002 0.002 <0.0005 <0.0005 <0.0005 0.0005 <0.0005 49 0.0005 3.3 0.080 0.001 0.001 0.002 0.002 0.002 <0.0005 <0.0005 <0.0005 <0.0005 0.0005 fifty 0.0005 3.5 0.079 0.001 <0.0005 <0.0015 0.002 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 51 0.0005 3.4 0.077 <0.0005 0.001 <0.0015 0.002 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 52 0.0005 3.3 0.079 0.001 <0.0005 <0.0015 0.002 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 53 0.0005 3.4 0.077 <0.0005 0.001 <0.0015 0.003 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 54 0.0005 3.3 0.079 0.001 <0.0005 <0.0015 0.003 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 55 0.0005 3.4 0.077 <0.0005 0.001 <0.0015 0.003 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 56 0.0005 3.5 0.079 0.001 <0.0005 <0.0015 0.002 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 57 0.0005 3.3 0.077 <0.0005 0.001 <0.0015 0.003 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005

[0118]

Evaluation tests

Position measurement test D _Al peak Al

To find the position D _Al of the Al peak in each grain-oriented electrical steel sheet in the numbered tests, the following measurement method was used. In particular, a surface layer of a grain-oriented electrical steel sheet was examined by performing elemental analysis using the GDS method. Elemental analysis was carried out to a depth of 100 μm from the surface of a sheet of electrical steel with an oriented grain structure (in the surface layer). Al contained in different depth positions in the surface layer was identified. The emission intensity of the identified Al was plotted in the direction of depth from the surface. The position of the D _Al peak of Al was determined from the constructed graph of the Al emission intensity. The found position D _Al of the Al peak is shown in Table 4.

[0119]

[Table 4]

TABLE 4 Test No. Annealing Separator Additives Primary Coating Evaluation test Notes Content
C _RE for
Y, La, Ce
(parts by weight per 100 parts by weight MgO) Content
C _G4 for
Ti, Zr, Hf
(parts by weight per 100 parts by weight MgO) General
content
C _RE +C _G4
(parts by weight per 100 parts by weight MgO) X _RE
/X _G4 Number Density
N _RE for
Y, La, Ce
(100000000/g) Number Density
N _G4 for
Ti, Zr, Hf
(100000000/g) _DAl
(µm) ND
(/ µm ² ) Content
Y, La, Ce
(%) Content
Ti, Zr, Hf
(%) Magnetization Adhesion one 0.00 1.50 1.5000 0.00 - 30.8 1.4 0.021 0.000 0.066 Good Unsatisfactory. Comp. approx. 2 0.00 1.50 1.5000 0.00 - 35.5 1.5 0.022 0.000 0.057 Good Unsatisfactory. Comp. approx. 3 0.00 1.70 1.7000 0.00 - 31.8 1.4 0.024 0.000 0.054 Good Unsatisfactory. Comp. approx. four 0.20 1.60 1.8000 0.14 41.5 32.5 1.8 0.026 0.013 0.045 Good Unsatisfactory. Comp. approx. 5 0.30 1.60 1.9000 0.14 63.2 35.4 1.7 0.022 0.013 0.022 Good Unsatisfactory. Comp. approx. 6 0.20 1.50 1.7000 0.11 52.1 32.6 1.7 0.024 0.020 0.054 Good Unsatisfactory. Comp. approx. 7 0.30 1.50 1.8000 0.15 42.9 52.0 1.5 0.025 0.037 0.037 Good Unsatisfactory. Comp. approx. eight 0.40 1.50 1.9000 0.34 125.4 32.8 1.4 0.026 0.015 0.038 Good Unsatisfactory. Comp. approx. 9 0.60 0.00 0.6000 - 166.8 - 1.6 0.022 0.033 0.000 Good Unsatisfactory. Comp. approx. ten 0.00 4.00 4.0000 0.00 194.2 62.4 1.3 0.019 0.000 0.080 Good Unsatisfactory. Comp. approx. eleven 0.40 1.80 2.2000 0.16 305.4 50.4 1.8 0.031 0.023 0.042 Good Satisfactory Comp. approx. 12 0.45 3.70 4.1500 0.15 331.8 91.5 1.9 0.034 0.022 0.088 Good Satisfactory Comp. approx. 13 0.50 1.50 2.0000 0.18 309.5 50.9 2.4 0.036 0.043 0.038 Good Good Note. fig. fourteen 3.60 0.20 3.8000 33.54 504.2 62.4 2.1 0.017 0.158 0.005 Good Satisfactory Comp. approx. fifteen 4.40 0.40 4.8000 7.73 508.6 60.3 2.5 0.022 0.221 0.009 Good Satisfactory Comp. approx. 16 0.00 4.00 4.0000 0.00 - 184.5 1.3 0.028 0.000 0.111 Good Unsatisfactory. Comp. approx. 17 0.33 4.00 4.3300 0.06 708.4 193.5 1.9 0.022 0.035 0.102 Good Unsatisfactory. Comp. approx. eighteen 3.00 0.60 3.6000 3.54 1065.5 192.5 4.2 0.051 0.158 0.033 Good Good Note. fig. 19 1.80 6.00 7.8000 0.16 2042.5 184.5 3.3 0.034 0.171 0.137 Good Good Note. fig. twenty 4.00 0.00 4.0000 - 2049.5 - 5.6 0.028 0.203 0.000 Satisfactory Satisfactory Comp. approx. 21 0.00 9.00 9.0000 0.00 4066.5 305.4 1.2 0.027 0.000 0.199 Good Unsatisfactory. Comp. approx. 22 2.40 11.00 13.4000 0.13 4025.5 405.3 1.9 0.054 0.089 0.315 Good Satisfactory Comp. approx. 23 1.80 12.00 13.8000 0.13 3099.8 606.2 1.9 0.054 0.089 0.311 Good Satisfactory Comp. approx. 24 6.00 0.80 6.8000 3.48 1088.6 801.5 4.3 0.088 0.229 0.033 Good Good Note. fig. 25 6.20 2.80 9.0000 4.13 2088.4 1624.2 6 0.025 0.322 0.088 Good Satisfactory Comp. approx. 26 7.50 0.70 8.2000 4.97 2099.5 1929.5 6.8 0.028 0.517 0.028 Good Satisfactory Comp. approx. 27 7.00 1.20 8.2000 4.18 3085.6 1355.5 3.5 0.022 0.515 0.027 Good Satisfactory Comp. approx. 28 6.00 0.00 6.0000 - 3045.2 - 7.2 0.006 0.330 0.000 Good Satisfactory Comp. approx. 29 6.00 6.00 12.0000 0.76 5044.2 317.6 6.8 0.120 0.333 0.169 Good Good Note. fig. thirty 6.00 7.00 13.0000 0.73 7088.4 391.0 8.2 0.131 0.364 0.144 Good Good Note. fig. 31 10.00 6.00 16.0000 1.18 68.5 405.5 12.4 0.211 0.623 0.150 Unsatisfactory. Good Comp. approx. 32 9.00 4.00 13.0000 1.27 67.2 55.5 13.1 0.149 0.544 0.077 Unsatisfactory. Good Comp. approx. 33 3.20 10.50 13.7000 0.26 55.4 103.5 8.8 0.235 0.244 0.255 Unsatisfactory. Good Comp. approx. 34 1.20 0.30 1.5000 2.83 59.0 219.6 3.2 0.027 0.064 0.014 Good Satisfactory Comp. approx. 35 0.70 4.20 4.9000 0.12 60.2 405.5 1.9 0.038 0.073 0.128 Good Satisfactory Comp. approx. 36 0.60 8.00 8.6000 0.14 61.8 992.5 1.9 0.032 0.044 0.268 Good Satisfactory Comp. approx. 37 2.00 6.50 8.5000 0.14 63.2 1084.2 1.8 0.035 0.075 0.150 Good Satisfactory Comp. approx. 38 0.80 4.00 4.8000 0.13 68.8 516.6 1.5 0.040 0.052 0.155 Good Satisfactory Comp. approx. 39 0.50 4.00 4.5000 0.12 276.3 53.5 1.4 0.033 0.044 0.134 Good Satisfactory Comp. approx. 40 0.80 0.80 1.6000 0.76 594.3 94.5 1.9 0.021 0.029 0.013 Good Unsatisfactory. Comp. approx. 41 7.00 8.00 15.0000 0.62 913.5 21.5 12.5 0.244 0.423 0.255 Unsatisfactory. Good Comp. approx. 42 0.75 7.80 8.5500 0.18 55.4 305.4 2.4 0.065 0.028 0.238 Good Good Note. fig. 43 3.50 9.80 13.3000 0.17 102.5 40.6 8.2 0.122 0.227 0.241 Good Good Note. fig. 44 7.80 1.00 8.8000 3.62 88.4 90.8 8.5 0.035 0.422 0.112 Good Good Note. fig. 45 3.20 2.50 5.7000 1.26 203.5 21.5 2.1 0.032 0.152 0.064 Good Good Note. fig. 46 3.00 3.00 6.0000 0.88 2044.5 1657.5 2.4 0.036 0.096 0.082 Good Good Note. fig. 47 4.00 5.00 9.0000 0.59 20.9 21.5 2.6 0.032 0.120 0.102 Good Good Note. fig. 48 3.00 3.50 6.5000 0.78 201.9 30.8 2.3 0.037 0.070 0.082 Good Good Note. fig. 49 4.50 5.80 10.3000 0.45 4052.1 40.8 2.3 0.038 0.172 0.188 Good Good Note. fig. fifty 2.50 1.50 4.00 0.38 19.0 62.6 1.1 0.014 0.052 0.142 Good Satisfactory Comp. approx. 51 2.40 1.80 4.20 0.81 18.4 71.6 1.3 0.018 0.042 0.166 Good Satisfactory Comp. approx. 52 2.00 3.00 5.00 0.24 17.3 79.6 1.4 0.012 0.039 0.172 Good Satisfactory Comp. approx. 53 2.90 3.00 5.90 0.93 16.8 54.9 1.4 0.011 0.033 0.167 Good Satisfactory Comp. approx. 54 4.20 5.00 9.20 0.72 66.8 17.5 2.2 0.008 0.045 0.177 Good Satisfactory Comp. approx. 55 3.40 4.50 7.90 0.20 302.4 16.2 2.4 0.006 0.048 0.172 Good Satisfactory Comp. approx. 56 1.80 5.00 6.80 0.82 4006.5 5.8 2.1 0.004 0.028 0.153 Good Satisfactory Comp. approx. 57 3.00 2.90 5.90 0.42 9811.5 12.5 2.2 0.008 0.044 0.187 Good Satisfactory Comp. approx.

[0120]

Test for measuring the number density ND of Al oxides

For each of the grain-oriented electrical steel sheets in the numbered tests, the number density ND of Al oxides (/µm ² ) at the D _{Al position of the Al} peak was found by the following method. Using a device for analysis by optical emission spectrometry, a glow discharge was performed to a depth up to the position D _{Al of the Al} peak. Any 36 µm×50 µm region (observed region) in the discharge spots at the D _Al position of the Al peak was analyzed for elements using an energy dispersive X-ray spectroscope (EDS) to identify Al oxides in the observed region. Sediments in the observed area containing Al and O were identified as Al oxides. The number of atoms of identified Al oxides was counted, and the number density ND of Al oxides (/µm ² ) was found by the following formula:

ND=Number of atoms of identified Al oxides/area of observed region.

The found number density ND of Al oxides is shown in Table 4.

[0121]

Test for measuring the contents of Y, La and Ce and the contents of Ti, Zr and Hf in the primary oxide film

Measurement to determine the contents of Y, La and Ce (wt.%) and the contents of Ti, Zr and Hf (wt.%) in the primary coating of each of the grain-oriented electrical steel sheets in numbered tests was performed in the following way. Specifically, the grain-oriented electrical steel sheet was subjected to electrolysis to separate only the primary coating from the surface of the base steel sheet. Performed a quantitative analysis of Mg in the separated primary coating by ICP-MS. The product of the obtained quantized value (wt.%) and the molecular weight of Mg ₂ SiO ₄ was divided by the atomic weight of Mg to find the equivalent content of Mg ₂ SiO ₄ . The measurement of Y, La and Ce and Ti, Zr and Hf in the primary coating was performed in the following way. The grain-oriented electrical steel sheet was subjected to electrolysis to separate only the primary coating from the surface of the base steel sheet. The contents of Y, La and Ce (wt.%) and the contents of Ti, Zr and Hf (wt.%) in the separated primary coating was found by quantitative analysis by ICP-MS. The contents of Y, La and Ce and the contents of Ti, Zr and Hf obtained in the measurement are shown in Table 4.

[0122]

Evaluation test for magnetic properties

The magnetic properties of each of the grain-oriented electrical steel sheets in the numbered tests were evaluated by the following method. Specifically, from each of the grain-oriented electrical steel sheets, a sample with a length of 300 mm in the rolling direction and a width of 60 mm was taken in numbered tests. The sample was subjected to a magnetic field of 800 A/m to determine the magnetic flux density B8. Table 4 presents the test results. In Table 4, a sample with a magnetic flux density of not less than 1.92T was rated "good", with a density of not less than 1.88T and lower than 1.92T was rated "satisfactory", and with a density lower than 1 ,88 Tl was rated "unsatisfactory". If the magnetic flux density was not lower than 1.92 T (that is, if "good" is indicated in Table 4), then the magnetic properties were considered to be very high.

[0123]

Evaluation test to determine adhesion

Primary coating adhesion of each of the grain-oriented electrical steel sheets in numbered tests was evaluated by the following method. Specifically, from each of the grain-oriented electrical steel sheets, a sample with a length of 60 mm in the rolling direction and a width of 15 mm was taken in numbered tests. The specimen was subjected to a bending test with a radius of curvature of 10 mm. The bending test was performed using a bending strength testing machine (from TP Giken) mounted on the sample so that the axial direction of the cylinder was consistent with the width direction of the sample. The surface of the sample after the bending test was examined and the total area of the areas in which the primary coating remained without delamination was determined. The preservation ratio of the primary coating was determined by the following formula.

Primary coating retention ratio = total area of areas in which the primary coating remains without delamination / sample surface area × 100.

[0124]

Table 4 presents the test results. A sample with a primary coating retention ratio of at least 90% was rated "good", with a ratio of at least 70% and less than 90% was rated "satisfactory", and with a ratio of less than 70% was rated "unsatisfactory". If the retention ratio of the Primary Coating had a value of at least 90% (that is, "good" in Table 4), the adhesion of the Primary Coating to the base steel sheet was considered to be very high.

[0125]

Test results

Table 4 presents the test results. As can be seen from Tables 2 and 4, in Test Nos. 13, 18, 19, 24, 29, 30 and 42-49, the annealing separator components were suitable. In particular, in these numbered tests, the total C _RE content of Y, La and Ce compounds converted to oxides (C _RE content of Y, La and Ce compounds converted to oxides), when determining the content of MgO as 100 wt.h. (100 wt.%) in the annealing separator was in the range of 0.5-8.0 wt. hours , and the total content of C _G4 compounds of Ti, Zr and Hf, converted into oxides, (the content of C _G4 compounds of Ti, Zr and Hf, converted into oxides), when determining the content of MgO as 100 wt. h (wt.%) in the annealing separator was in the range of 0.5-10.0%. In addition, the sum (C _RE +C _G4 ) of the contents of Y, La and Ce compounds converted to oxides and the contents of Ti, Zr and Hf compounds converted to oxides was in the range of 2.0 to 14.0 wt. In addition, the ratio (X _RE /X _G4 ) of the sum of the numbers of Y, La and Ce atoms to the sum of the numbers of Ti, Zr and Hf atoms contained in the annealing separator was in the range of 0.15-4.00. For this reason, the D _Al position of the Al peak was in the range of 2.0-12.0 µm, and the number density ND of Al oxides was 0.03-0.2/µm ² . As a result, in the tests indicated by these numbers, the primary coating exhibited very high adhesion. In addition, it exhibited very high magnetic properties.

[0126]

In addition, in particular, test Nos. 13, 29, 30 and 45-49 contained at least two types of metal compounds selected from the group consisting of Ti, Zr and Hf. The primary coating exhibited exceptionally high adhesion and exceptionally high magnetic properties were exhibited.

[0127]

On the other hand, in trials Nos. 1, 2, 3, 4, 5 and 6, the content of C _RE compounds of Y, La and Ce converted into oxides was too low, and in addition, the sum (C _RE +C _G4 ) the content of Y, La and Ce compounds converted into oxides and the content of Ti, Zr and Hf compounds converted into oxides, and the ratio (X _RE /X _G4 ) of the sum of the numbers of Y, La and Ce atoms to the sum of the numbers of Ti, Zr atoms and Hf were also too small. For this reason, the position D _Al of the Al peak and the number density ND of Al oxides were too small. As a result, the adhesion of the primary coating was poor.

[0128]

In Test Nos. 7 and 8, the _{CRE content of Y, La and Ce compounds converted to oxides was too low, and the sum (C RE +} C _G4 ) of the content of Y, La and Ce compounds converted to oxides and the content of compounds Ti, Zr and Hf converted into oxides was also too small. For this reason, the position D _Al of the Al peak was too small, and the numerical density ND of the Al oxides was too low. As a result, the adhesion of the primary coating was poor.

[0129]

Tests Nos. 9, 20 and 28 contained none of the Ti, Hf and Zr compounds. For this reason, the number density ND of Al oxides was too low. As a result, the adhesion of the primary coating was low.

[0130]

Tests Nos. 10, 16 and 21 also contained none of the Y, La and Ce compounds. For this reason, the position D _Al of the Al peak was too small, and the numerical density ND of the Al oxides was too low. As a result, the adhesion of the primary coating was poor.

[0131]

In trials Nos. 11 and 12, the content of C _RE compounds of Y, La and Ce converted to oxides was low. For this reason, the D _{Al position of the Al} peak was too small. As a result, the adhesion of the primary coating was poor.

[0132]

In trials Nos. 14 and 15, the C _G4 content of Ti, Zr and Hf compounds converted to oxides was too low, and the ratio (X _RE /X _G4 ) of the sum of the numbers of Y, La and Ce atoms to the sum of the numbers of Ti, Zr atoms and Hf was high. For this reason, the number density ND of Al oxides was too low. As a result, the adhesion of the primary coating was poor.

[0133]

In test No. 17, the content of C _RE compounds of Y, La and Ce converted into oxides was too low, and the ratio (X _RE /X _G4 ) of the sum of the numbers of Y, La and Ce atoms to the sum of the numbers of Ti, Zr and Hf atoms was too low. For this reason, the position D _Al of the Al peak was too small, and the numerical density ND of the Al oxides was too low. As a result, the adhesion of the primary coating was poor.

[0134]

In Test Nos. 22 and 23, the C _G4 content of Ti, Zr, and Hf compounds converted to oxides was too high, and the ratio (X _RE /X _G4 ) of the sum of the numbers of Y, La, and Ce atoms to the sum of the numbers of Ti, Zr atoms and Hf was too low. For this reason, the D _{Al position of the Al} peak was too small. As a result, the adhesion of the primary coating was poor.

[0135]

In trials Nos. 25, 26 and 27, the ratio (X _RE /X _G4 ) of the sum of the numbers of Y, La and Ce atoms to the sum of the numbers of Ti, Zr and Hf atoms was too high. For this reason, the number density ND of Al oxides was too low. As a result, the adhesion of the primary coating was poor.

[0136]

In test No. 31, the sum (C _RE +C _G4 ) of the C _RE content of Y, La and Ce compounds converted to oxides and the content of Ti, Zr and Hf compounds converted to oxides was too high. For this reason, the position D _Al of the Al peak was too high, and the numerical density ND of the Al oxides was too high. As a result, the magnetic properties were low.

[0137]

In test No. 32, the content of C _RE compounds of Y, La and Ce, converted into oxides, was too high. For this reason, the D _{Al position of the Al} peak was too high. As a result, the magnetic properties were low.

[0138]

In test No. 33, the content of C _G4 oxide-converted Ti, Zr and Hf compounds was too high. For this reason, the number density ND of Al oxides was too high. As a result, the magnetic properties were low.

[0139]

In test No. 34, the content of C _G4 oxide-converted Ti, Zr and Hf compounds was too low. For this reason, the number density ND of Al oxides was too low. As a result, the adhesion of the primary coating was poor.

[0140]

In trials Nos. 35, 36, 37, 38 and 39, the ratio (X _RE /X _G4 ) of the sum of the numbers of Y, La and Ce atoms to the sum of the numbers of Ti, Zr and Hf atoms was too low. For this reason, the D _{Al position of the Al} peak was too small. As a result, the adhesion of the primary coating was poor.

[0141]

In test No. 40, the sum (C _RE +C _G4 ) of the content of Y, La and Ce compounds converted to oxides and the content of Ti, Zr and Hf compounds converted to oxides was too low. For this reason, the position D _Al of the Al peak was too small, and the number density ND of the Al oxides was too low. As a result, the adhesion of the primary coating was poor.

[0142]

In test No. 41, the sum (C _RE +C _G4 ) of the content of Y, La and Ce compounds converted to oxides and the content of Ti, Zr and Hf compounds converted to oxides was too large. For this reason, the position D _Al of the Al peak was too high, and the numerical density ND of the Al oxides was too high. As a result, the magnetic properties were low.

[0143]

In Test Nos. 50-53, the particle number density of the Y, La, and Ce compounds was too low in the starting powder material of the annealing separator. For this reason, the position D _Al of the Al peak was too small, and the number density ND of the Al oxides was too low. As a result, the adhesion of the primary coating was poor.

[0144]

In Test Nos. 54-57, the particle number density of the Ti, Zr and Hf compounds was too low in the starting powder material of the annealing separator. For this reason, the number density ND of Al oxides was too low. As a result, the adhesion of the primary coating was low.

[0145]

Example 2

Production of Grain-Oriented Electrical Steel Sheet

Similar to Example 1, each of the cold-rolled steel sheets made from molten steel with the chemical compositions shown in Table 1, after primary recrystallization annealing in Test Nos. 58-70, was coated with an aqueous slurry and dried to apply an annealing separator on one side with a coverage factor of 5 g/m ² . It should be noted that an aqueous suspension was prepared by mixing an annealing separator and commercially pure water in a mixing ratio of 1:2. Annealing separator contained MgO, additives shown in table 5, and when determining the MgO content as 100 wt.h. (wt.%), 2.5 wt.h CeO ₂ , 4.0 wt.h ZrO ₂ and 2.0 wt.h TiO ₂ . It should be noted that, the content of C _RE for Y, La and Ce in the annealing separator shown in Table 5 means the total content of Y, La and Ce compounds converted into oxides, when determining the content of MgO as 100 wt.h (wt.% ) in the annealing separator. Similarly, the relative abundance X _RE of Y, La and Ce atoms shown in Table 5 means the ratio of the sum of the numbers of Y, La and Ce atoms to the number of Mg atoms contained in the annealing separator. Similarly, the content of C _G4 for Ti, Zr and Hf in the annealing separator shown in Table 5 means the total content of Ti, Zr and Hf compounds converted to oxides, when determining the content of MgO as 100 wt.h (wt.%) in annealing separator. Similarly, the relative content X _G4 of Ti, Zr and Hf atoms shown in Table 5 means the ratio of the sum of the numbers of Ti, Zr and Hf atoms to the number of Mg atoms contained in the annealing separator. In addition, similarly, the relative X _AM content of Ca, Sr, and Ba atoms shown in Table 5 means the ratio of the sum of the numbers of Ca, Sr, and Ba atoms to the number of Mg atoms contained in the annealing separator.

[0146]

[Table 5]

TABLE 5

Test No. Steel Type of Hot Rolled Steel Sheet Additives in the annealing separator Notes Content
C _RE for
Y, La, Ce
(parts by weight per 100 parts by weight MgO) Content
C _G4 for
Ti, Zr, Hf
(parts by weight per 100 parts by weight MgO) Total content
C _RE +C _G4 Relative content of X _RE
for Y, La, Ce Relative content X _G4
for Ti, Zr, Hf X _RE / X _G4 Number Density
N _RE for
Y, La, Ce(100000000/g) Number Density
N _G4 for
Ti, Zr, Hf
(100000000/g) Content
_CaSO4
(parts by weight per 100 parts by weight MgO) Content
_SrSO4
(parts by weight per 100 parts by weight MgO) Content
BaSO ₄ (parts by weight per 100 parts by weight MgO) _XAM 58 A 2.50 6.00 8.5000 0.0059 0.0232 0.25 405.3 304.2 3.30 0.00 0.00 0.010 Note. fig. 59 A 2.50 6.00 8.5000 0.0059 0.0232 0.25 405.3 304.2 0.00 4.40 0.00 0.010 Note. fig. 60 A 2.50 6.00 8.5000 0.0059 0.0232 0.25 405.3 304.2 0.00 0.00 5.50 0.010 Note. fig. 61 A 2.50 6.00 8.5000 0.0059 0.0232 0.25 405.3 304.2 8.50 0.00 0.00 0.025 Compar. approx. 62 B 2.50 6.00 8.5000 0.0059 0.0232 0.25 2093.5 304.2 6.00 0.00 0.00 0.018 Note. fig. 63 B 2.50 6.00 8.5000 0.0059 0.0232 0.25 2093.5 304.2 0.00 8.00 0.00 0.018 Note. fig. 64 B 2.50 6.00 8.5000 0.0059 0.0232 0.25 2093.5 304.2 0.15 0.00 10.00 0.018 Note. fig. 65 B 2.50 6.00 8.5000 0.0059 0.0232 0.25 2093.5 5013.2 0.00 6.00 8.00 0.027 Compar. approx. 66 C 2.50 6.00 8.5000 0.0059 0.0232 0.25 2093.5 5013.2 3.50 0.00 0.00 0.010 Note. fig. 67 D 2.50 6.00 8.5000 0.0059 0.0232 0.25 2093.5 5013.2 0.00 3.50 0.00 0.008 Note. fig. 68 E 2.50 6.00 8.5000 0.0059 0.0232 0.25 2093.5 5013.2 0.00 0.00 4.00 0.007 Note. fig. 69 F 2.50 6.00 8.5000 0.0059 0.0232 0.25 405.3 5013.2 0.00 0.00 4.00 0.007 Note. fig. 70 G 2.50 6.00 8.5000 0.0059 0.0232 0.25 405.3 5013.2 0.00 0.00 4.00 0.007 Note. fig.

[0147]

The cold-rolled steel sheet, on the surface of which the aqueous slurry was applied, was placed, in each of the numbered tests, in an oven at 900° C. for 10 seconds to dry the aqueous slurry. After drying, finishing annealing was performed. At the finish anneal, in each of the numbered tests, the sheet was held at 1200° C. for 20 hours. Through the above-described manufacturing process, a grain-oriented electrical steel sheet containing a base steel sheet and a primary coating was produced.

[0148]

Analysis of the Chemical Composition of the Base Steel Sheet in Grain-Oriented Electrical Steel Sheet

The base steel sheets of the produced grain-oriented electrical steel sheets in Test Nos. 58-70 were examined by spark optical emission spectrometry and atomic absorption spectrometry to determine the chemical compositions of the base steel sheets. The found chemical compositions are shown in Table 6.

[0149]

[Table 6]

TABLE 6

Test No. Chemical composition (units: wt.%, balance of Fe and impurities) C Si Mn S Se S+Se soluble Al N sn Sb Bi Te Pb 58 0.0005 3.3 0.077 0.001 <0.0005 <0.0015 0.002 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 59 0.0005 3.3 0.076 0.001 <0.0005 <0.0015 0.002 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 60 0.0005 3.2 0.077 0.001 <0.0005 <0.0015 0.002 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 61 0.0005 3.3 0.079 0.001 <0.0005 <0.0015 0.002 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 62 0.0005 3.4 0.077 <0.0005 0.001 <0.0015 0.003 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 63 0.0005 3.3 0.075 <0.0005 0.001 <0.0015 0.002 0.001 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 64 0.0005 3.3 0.072 <0.0005 0.001 <0.0015 0.002 0.002 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 65 0.0005 3.3 0.074 <0.0005 0.001 <0.0015 0.002 0.003 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 66 0.0005 3.2 0.077 0.001 0.001 0.002 0.002 0.001 0.0200 <0.0005 <0.0005 <0.0005 <0.0005 67 0.0005 3.2 0.072 0.001 0.001 0.002 0.002 0.001 <0.0005 0.0010 <0.0005 <0.0005 <0.0005 68 0.0005 3.3 0.076 0.001 0.001 0.002 0.002 0.002 <0.0005 <0.0005 0.0008 <0.0005 <0.0005 69 0.0005 3.3 0.078 0.001 0.001 0.002 0.002 0.002 <0.0005 <0.0005 <0.0005 0.0005 <0.0005 70 0.0005 3.2 0.077 0.001 0.001 0.002 0.003 0.002 <0.0005 <0.0005 <0.0005 <0.0005 0.0005

[0150]

Coating Evaluation Test

For each grain oriented electrical steel sheet, in numbered tests, similarly to Example 1, the D _{Al position of the Al} peak, the number density ND of Al oxides (/μm ² ) at the D _{Al position of the Al} peak, and the contents of Y, La, and Ce and Ti, Zr and Hf contents in the primary coating. The position D _Al of the Al peak, the numerical density ND of Al oxides, and the contents of Y, La and Ce and the contents of Ti, Zr and Hf in the primary coating obtained by measurement are shown in Table 7.

[0151]

[Table 7]

TABLE 7

Test No. Additives in the annealing separator Primary Coating Evaluation test Notes General
content
C _RE +C _G4 Relative content
X _RE
Y, La, Ce Relative content
X _G4
Ti, Zr, Hf X _RE
/X _{G4 XAM} Number Density
N _RE for
Y, La, Ce
(100000000/g) Number Density
N _G4 for
Ti, Zr, Hf
(100000000/g) D _Al
(µm) ND
(/ µm ² ) Content
Y, La, Ce
(%) Content
Ti, Zr, Hf
(%) Magnetization Adhesion 58 8.5000 0.0059 0.0232 0.25 0.010 405.3 304.2 5.2 0.035 0.131 0.122 Good Good Note. fig. 59 8.5000 0.0059 0.0232 0.25 0.010 405.3 304.2 5.8 0.032 0.107 0.141 Good Good Note. fig. 60 8.5000 0.0059 0.0232 0.25 0.010 405.3 304.2 5.4 0.038 0.116 0.139 Good Good Note. fig. 61 8.5000 0.0059 0.0232 0.25 0.025 405.3 304.2 1.9 0.031 0.116 0.129 Good Satisfactorily Comp. approx.. 62 8.5000 0.0059 0.0232 0.25 0.018 2093.5 304.2 3.2 0.042 0.108 0.132 Good Good Note. fig. 63 8.5000 0.0059 0.0232 0.25 0.018 2093.5 304.2 2.9 0.036 0.104 0.148 Good Good Note. fig. 64 8.5000 0.0059 0.0232 0.25 0.018 2093.5 304.2 3.7 0.038 0.107 0.145 Good Good Note. fig. 65 8.5000 0.0059 0.0232 0.25 0.027 2093.5 5013.2 1.8 0.031 0.108 0.129 Good Satisfactorily Comp. approx.. 66 8.5000 0.0059 0.0232 0.25 0.010 2093.5 5013.2 4.2 0.032 0.117 0.132 Good Good Note. fig. 67 8.5000 0.0059 0.0232 0.25 0.008 2093.5 5013.2 4.6 0.040 0.108 0.145 Good Good Note. fig. 68 8.5000 0.0059 0.0232 0.25 0.007 2093.5 5013.2 4.8 0.034 0.110 0.144 Good Good Note. fig. 69 8.5000 0.0059 0.0232 0.25 0.007 405.3 5013.2 4.8 0.035 0.110 0.144 Good Good Note. fig. 70 8.5000 0.0059 0.0232 0.25 0.007 405.3 5013.2 4.8 0.033 0.110 0.144 Good Good Note. fig.

[0152]

Evaluation test for magnetic properties

The magnetic properties of each of the grain-oriented electrical steel sheets in the numbered tests were evaluated using the same method as in Example 1. Table 7 shows the test results. Just as in Example 1, in Table 7, a sample with a magnetic flux density of not less than 1.92 T was rated "good", with a density of not less than 1.88 T and lower than 1.92 T was rated "satisfactory" , and with a density lower than 1.88 T was rated "unsatisfactory". If the magnetic flux density was not lower than 1.92 T (that is, if "good" is indicated in Table 4), then the magnetic properties were considered to be very high.

[0153]

Evaluation test to determine adhesion

Primary coating adhesion of each of the grain-oriented electrical steel sheets in numbered tests was evaluated using the same method as in Example 1. Table 7 presents the test results. Similar to Example 1, in Table 7, a sample with a primary coating retention ratio of at least 90% is shown as "good", with a ratio of at least 70% and less than 90% is shown as "satisfactory", and with a ratio of less than 70% is shown as "unsatisfactory". If the Primary Coating retention ratio was not less than 90% (that is, shown as "good" in Table 7), it was considered that the adhesion of the Primary Coating to the base steel sheet was very high.

[0154]

Test results

Table 7 presents the test results. As can be seen from Tables 5 and 7, in Test Nos. 58-60, 62-64 and 66-70, the annealing separator components were suitable. In particular, the total content of C _RE compounds of Y, La and Ce, converted into oxides, (content of C _RE compounds of Y, La and Ce, converted into oxides) when determining the content of MgO as 100 wt.h. (wt.%) in the annealing separator was in the range of 0.5-8.0 wt. hours, and the total content of C _G4 compounds of Ti, Zr and Hf, converted into oxides, (the content of C _G4 compounds of Ti, Zr and Hf, converted into oxides) when determining the content of MgO as 100 wt. hours (wt.%) in the annealing separator was in the range of 0.5-10.0 wt.h. In addition, the sum (C _RE +C _G4 ) of the contents of Y, La and Ce compounds converted to oxides and the contents of Ti, Zr and Hf compounds converted to oxides was in the range of 2.0 to 14.0 parts by weight. In addition, the ratio (X _RE /X _G4 ) of the sum of the numbers of Y, La, and Ce atoms to the sum of the numbers of Ti, Zr, and Hf atoms contained in the annealing separator was in the range of 0.15-4.00, and furthermore , the ratio (X _AM ) of the sum of the numbers of Ca, Sr, and Ba atoms to the number of Mg atoms contained in the annealing separator was lower than 0.025. For this reason, the D _{Al position of the Al} peak was in the range of 2.0-12.0 μm, and the numerical density ND of Al oxides was 0.03-0.2/μm ² . As a result, in the tests indicated by these numbers, the primary coating exhibited very high adhesion. In addition, it exhibited very high magnetic properties.

[0155]

On the other hand, in Test Nos. 61 and 65, the ratio (X _AM ) of the sum of the numbers of Ca, Sr, and Ba atoms to the number of Mg atoms contained in the annealing separator was not lower than 0.025. For this reason, the D _{Al position of the Al} peak was too small. As a result, the adhesion of the primary coating was poor.

[0156]

The embodiments of the present invention have been described above. However, the above described embodiments are merely illustrative of the use of the present invention. Therefore, the present invention is not limited to the above-described embodiments, and can be applied by suitably modifying the above-described embodiments within the scope without departing from the gist of the invention.

Claims (50)

1. A grain-oriented electrical steel sheet containing basic steel sheet having a chemical composition containing, in wt.%: C: no more than 0.005, Si: 2.5-4.5 Mn: 0.02-0.2 one or more elements selected from the group consisting of S and Se: not more than 0.005 in total, soluble Al: not more than 0.01, and N: no more than 0.01 and containing a residue consisting of Fe and impurities, and primary coating formed on the surface of the base steel sheet and containing Mg ₂ SiO ₄ as a main component, while the position of the Al radiation intensity peak obtained by performing elemental analysis by glow discharge optical emission spectrometry from the surface of the primary coating in the direction of the thickness of the grain-oriented electrical steel sheet is located within 2.0-12.0 μm from the surface of the primary coating in the thickness direction , and the numerical density of Al oxides with dimensions of at least 0.2 μm in diameter equivalent to the area of the circle, in the peak position of the Al radiation intensity is 0.03-0.2/μm ² . 2. A method for manufacturing a grain-oriented electrical steel sheet according to claim 1, comprising cold rolling process of hot-rolled steel sheet containing, in wt.%: C: no more than 0.1, Si: 2.5-4.5 Mn: 0.02-0.2 one or more elements selected from the group consisting of S and Se: in the amount of 0.005-0.07, soluble Al: 0.005-0.05, and N: 0.001-0.030 and if necessary, one or more elements selected from the group consisting of Cu, Sb and Sn, not more than 0.6 in total, optionally one or more elements selected from the group consisting of Bi, Te and Pb, in total not more than 0.03, and the rest is Fe and impurities, with a cold rolling reduction ratio of at least 80% to produce cold rolled steel sheet, decarburization annealing process of cold rolled steel sheet, a process of coating the surface of the cold-rolled steel sheet after decarburization annealing with an aqueous slurry containing an annealing separator and drying the aqueous slurry on the surface of the cold-rolled steel sheet in a furnace at 400-1000°C, and a process for performing finish annealing of a cold-rolled steel sheet after the aqueous slurry is dried, wherein annealing separator contains MgO at least one or more types of metal compounds selected from the group consisting of Y, La and Ce, and at least one or more types of metal compounds selected from the group consisting of Ti, Zr and Hf, moreover, when the content of MgO in the annealing separator is 100 parts by mass, the total content of metal compounds selected from the group consisting of Y, La and Ce converted into oxides is 0.5 to 8.0 parts by mass, and the total content of metal compounds selected from the group consisting of Ti, Zr and Hf converted into oxides is 0.5-10.0 parts by weight, in addition, the total amount of the total content of metal compounds selected from the group consisting of Y, La and Ce converted to oxides and the total content of metal compounds selected from the group consisting of Ti, Zr and Hf converted to oxides is 2 0-14.0 wt.h., in addition, the ratio of the sum of the numbers of Ti, Zr and Hf atoms and the sum of the numbers of Y, La and Ce atoms contained in the annealing separator is 0.15-4.00, in addition, the particle number density of the metal compound particles selected from the group consisting of Y, La and Ce, which are particles with a diameter of a sphere equivalent in volume of not less than 0.1 μm, is not less than 2000000000/g, and, moreover, the particle number density of the metal compound particles selected from the group consisting of Ti, Zr and Hf, which are particles with a sphere equivalent in volume diameter of at least 0.1 μm, is at least 2000000000/g. 3. The method for manufacturing a grain-oriented electrical steel sheet according to claim 2, wherein in the method for manufacturing a grain-oriented electrical steel sheet the annealing separator further comprises at least one or more types of metal compound selected from the group consisting of Ca, Sr and Ba, and the ratio of the sum of the numbers of Ca, Sr and Ba atoms to the number of Mg atoms contained in the annealing separator is less than 0.025. 4. The annealing separator used to produce the grain-oriented electrical steel sheet according to claim 1, wherein the annealing separator comprises MgO at least one or more types of metal compounds selected from the group consisting of Y, La and Ce, and, at least one or more types of metal compounds selected from the group consisting of Ti, Zr and Hf, moreover, when the content of MgO in the annealing separator is 100 wt. h., the total content of metal compounds selected from the group consisting of Y, La and Ce, converted into oxides, is 0.5-8.0 wt.h., and the total content of metal compounds selected from the group consisting of Ti , Zr and Hf, converted into oxides, is 0.5-10.0 wt.h., in addition, the total amount of the total content of metal compounds selected from the group consisting of Y, La and Ce converted to oxides and the total content of metal compounds selected from the group consisting of Ti, Zr and Hf converted to oxides is 2 0-14.0 wt.h., in addition, the ratio of the sum of the numbers of Y, La and Ce atoms to the sum of the numbers of Ti, Zr and Hf atoms contained in the annealing separator is 0.15-4.00, in addition, the particle number density of the metal compound particles selected from the group consisting of Y, La and Ce, which are particles with a diameter of a sphere equivalent in volume of not less than 0.1 μm, is not less than 2000000000/g, and, in addition, the particle number density of the metal compounds selected from the group consisting of Ti, Zr and Hf, which are particles with a diameter equivalent in volume to a sphere of not less than 0.1 μm, is not less than 2000000000/g. 5. The annealing separator according to claim 4, while, in the annealing separator, the annealing separator further comprises at least one or more types of metal compound selected from the group consisting of Ca, Sr and Ba, and the ratio of the sum of the numbers of Ca, Sr and Ba atoms to the number of Mg atoms contained in the annealing separator is less than 0.025.