RU2791493C1 - Electrical steel sheet with oriented grain structure - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: the invention relates to metallurgy, namely to an electrical steel sheet with an oriented grain structure, and can be used as a core material for transformers and other electrical equipment. The electrical steel sheet with an oriented grain structure contains a main steel sheet, a glass film, which is located on the main steel sheet, and an insulating coating with tightness, which is located on the glass film. The chemical composition of the main steel sheet and glass film includes, by weight%: 0.010 or less C, 2.5-4.0 Si, 0.01-1.00 Mn, 0.010 or less N, 0.010 or less soluble Al, 0.005-0.030 insoluble Al, 0.05-0.20 Mg, 0.05-0.40 O, 0-0.020 Ti, 0.010 or less S, 0.030 or less P, 0-0.50 Sn, 0-0.50 Cr, 0-0.50 Cu, 0-0.0100 Bi, 0-0.020 Se, 0-0.50 Sb and a residue consisting of iron and impurities. The sheet has emission spectroscopy spectra of glow discharge of Al and Si, measured using emission spectroscopy of glow discharge from the surface of the glass film in the direction of depth, after removal of the insulating coating, where Ts is the start time of the analysis, from the surface of the glass film, T^Al _p is the time at which Al shows the maximum emission intensity, F(T^Al _p) is the intensity of the emission of Al at T^Al _p in relative units, F(T^Si _p) is the intensity of the emission of Al at T^Si _p. The following expressions are satisfied: 0,05 ≤ F(T^Si _p) / F(T^Al _p) ≤ 0,50 и 2,0 ≤ (T^Al _p - Ts) / (T^Si _p - Ts) ≤ 5,0.

EFFECT: ensuring the high adhesion of the glass film.

4 cl, 5 dwg, 6 tbl, 66 ex

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

[0001]

The present invention relates to a grain oriented electrical steel sheet.

Priority is claimed according to Japanese Patent Application: No. 2019-170881, filed September 19, 2019, the contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

[0002]

The grain-oriented electrical steel sheet includes 0.5 to 7 mass% Si, and its crystal orientation is controlled to be aligned with the {110}<001> direction (Goss orientation). Grain-oriented electrical steel sheet is used as a soft magnetic material for the iron core material of transformers and other electrical equipment.

[0003]

In most cases, the grain oriented electrical steel sheet includes a base steel sheet, a glass film, and a tension insulating coating. A glass film is formed on the base steel sheet, and a tension insulating coating is formed on the glass film. By means of the tensioned insulating coating and the glass film, the insulation between the steel sheets is increased, and thus the magnetic efficiency is improved.

[0004]

The glass film is an oxide which mainly includes forsterite (Mg ₂ SiO ₄ ) and contributes to the increase in tension and insulation. The glass film also helps to increase the adhesion of the insulating coating under tension to the base steel sheet. Accordingly, it is necessary to improve the adhesion of the glass film to the base steel sheet.

[0005]

Techniques for improving the adhesion of a glass film to a base steel sheet are disclosed in Japanese Unexamined Patent Application First Publication No. 2012-214902 (Patent Document 1), Japanese Unexamined Patent Application First Publication No. 2018-53346 (Patent Document 2), and Japanese Unexamined Patent Application First Publication No. Examined Patent Application First Publication No. H11-61356 (Patent Document 3).

[0006]

In the grain-oriented electrical steel sheet disclosed in Patent Document 1, which includes 1.8-7 mass% Si and which has on its surface a primary coating comprising mainly forsterite, at least one of Ce, La, Pr , Nd, Sc and Y are included in the Primary Coating and the coating weight is 0.001-1000 mg/m ² per side.

[0007]

In the grain-oriented electrical steel sheet disclosed in Patent Document 2, the cross-sectional void area ratio of the glass film formed between the insulating coating and the base steel sheet is 20% or less.

[0008]

In the grain-oriented electrical steel sheet disclosed in Patent Document 3, the Si peak intensity obtained by glow discharge emission spectroscopy on the oxide film surface is 1/2 or more of the Al peak intensity, and the depth from the oxide film surface to the position the Si peak is 1/10 or less relative to the depth from the surface of the oxide film to the position of the Al peak.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0009]

[Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2012-214902

[Patent Document 2] Japanese Unexamined Patent Application, First Publication No. 2018-53346

[Patent Document 3] Japanese Unexamined Patent Application, First Publication No. H11-61356

SUMMARY OF THE INVENTION

SOLVED TECHNICAL PROBLEM

[0010]

Although the adhesion of the glass film is increased in Patent Documents 1-3, the adhesion of the glass film can be improved by other features.

[0011]

The present invention has been made in view of the above situations. It is an object of the present invention to provide a grain-oriented electrical steel sheet excellent in glass film adhesion.

SOLUTION

[0012]

Aspects of the present invention are as follows.

(1) A grain-oriented electrical steel sheet according to one aspect of the present invention includes:

main steel sheet;

a glass film which is placed on the base steel sheet; And

insulating coating with tension, which is located on the glass film,

moreover, the average chemical composition of the base steel sheet and the glass film includes, in wt.%:

0.010% or less C;

2.5-4.0% Si,

0.01-1.00% Mn;

0.010% or less N;

0.010% or less soluble Al;

0.005-0.030% insoluble Al;

0.05-0.20% Mg;

0.05-0.40% O;

0-0.020% Ti;

0.010% or less S;

0.030% or less P;

0-0.50% Sn;

0-0.50%Cr;

0-0.50% Cu;

0-0.0100% Bi;

0-0.020% Se;

0-0.50% Sb; And

a residue consisting of iron and impurities, and

when the glow discharge emission spectroscopy spectra of Al and Si are measured by glow discharge emission spectroscopy from the surface of the glass film in the depth direction,

when Ts, which is the start time of the analysis, is considered as the surface of the glass film,

when T ^Al _p is considered as the time at which Al shows the maximum emission intensity,

when F(T ^Al _p ) is considered as the Al emission intensity at T ^Al _p ,

when T ^Si _p is considered as the time at which Si shows the maximum emission intensity,

when F(T ^Si _p ) is considered as the Al emission intensity at T ^Si _p ,

the values Ts, T ^Al _p , F(T ^Al _p ), T ^Si _p and F(T ^Si _p ) satisfy the expressions

0.05 ≤ F(T ^Si _p ) / F(T ^Al _p ) ≤ 0.50 and

2.0 ≤ (T ^Al _p - Ts) / (T ^Si _p - Ts) ≤ 5.0.

(2) In the grain-oriented electrical steel sheet according to (1)

the thickness of the base steel sheet may be 0.17 mm or more and less than 0.22 mm.

(3) In grain-oriented electrical steel sheet according to (1) or (2)

the average chemical composition may include, in wt.%, at least one element selected from:

0.01-0.50% Cr;

0.01-0.50% Sn;

0.01-0.50% Cu;

0.0010-0.0100% Bi;

0.001-0.020% Se; And

0.01-0.50% Sb.

(4) In a grain-oriented electrical steel sheet according to any one of paragraphs. (13),

when the glow discharge emission spectroscopy spectra of Al and Fe are measured by glow discharge emission spectroscopy from the surface of the glass film in the depth direction,

when T ^Al _p is considered as the time at which Al shows the maximum emission intensity,

when T ^Fe ₆₀ is considered as the time at which the Fe emission intensity becomes 60% compared to the saturation value of the Fe emission intensity, and

when T ^Fe ₉₀ is considered as the time at which the Fe emission intensity becomes 90% compared to the saturation value of the Fe emission intensity,

the values of T ^Al _p , T ^Fe ₆₀ and T ^Fe ₉₀ can satisfy the expression

T ^Fe ₆₀ ≤ T ^Al _p ≤ T ^Fe ₉₀ .

BENEFICIAL EFFECTS OF THE INVENTION

[0013]

According to the above-described aspects of the present invention, it is possible to provide a grain-oriented electrical steel sheet excellent in glass film adhesion.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]

Fig. 1 shows a perspective view of a grain-oriented electrical steel sheet according to one embodiment of the present invention.

Fig. 2 shows in perspective one modification of a grain-oriented electrical steel sheet according to an embodiment.

Fig. 3 is an illustration showing glow discharge emission spectroscopy spectra of Al and Si obtained by glow discharge emission spectroscopy.

Fig. 4 shows in perspective a state in which the insulating coating is tension-removed from the grain-oriented electrical steel sheet according to the embodiment.

Fig. 5 is a flowchart showing an example of manufacturing processes for grain-oriented electrical steel sheet according to the embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015]

Next, one preferred embodiment of the present invention will be described in detail. However, the present invention is not limited to only the configuration disclosed in this embodiment, and various modifications are possible without departing from the aspect of the present invention. In addition, the limiting range described below includes its lower limit and its upper limit. However, a value expressed as "greater than" or "less than" is not included in this range. Unless otherwise indicated, "%" referring to the chemical composition is "% by weight".

[0016]

The present inventors conducted a study to improve the adhesion of a glass film to a grain-oriented electrical steel sheet in which the chemical composition of the base steel sheet (average chemical composition of the base steel sheet and the glass film) includes, in wt%:

0.010% or less C;

2.5-4.0% Si,

0.01-1.00% Mn;

0.010% or less N;

0.010% or less soluble Al;

0.005-0.030% insoluble Al;

0.05-0.20% Mg;

0.05-0.40% O;

0-0.020% Ti;

0.010% or less S;

0.030% or less P;

0-0.50% Sn;

0-0.50%Cr;

0-0.50% Cu;

0-0.0100% Bi;

0-0.020% Se;

0-0.50% Sb; And

the remainder consisting of iron and impurities.

[0017]

As explained above, even in conventional techniques, the adhesion of a glass film to a grain-oriented electrical steel sheet is a problem to be solved. In conventional techniques, for example, the following approach has been used to improve glass film adhesion.

(A) Glass film adhesion is increased by adjusting the anneal separator.

(B) Glass film adhesion is increased by controlling the morphology of SiO ₂ formed on the surface of the base steel sheet before final annealing. In particular, the adhesion of the glass film is increased by controlling the morphology of SiO ₂ by controlling the conditions during the decarburization annealing process.

[0018]

On the other hand, the inventors of the present invention made a study to improve the adhesion of a glass film by a completely different approach compared to conventional techniques. As a result of the study, it was found that the adhesion of the glass film is improved by localizing the spinel (MgAl ₂ O ₄ ) near the interface with the main steel sheet in the glass film. The present inventors were the first to discover that glass film adhesion is improved by localizing the spinel near the interface.

[0019]

The localization of the spinel at the interface in the glass film can be confirmed by the following method using glow discharge emission spectroscopy. Specifically, the insulating coating with tension is removed, glow discharge emission spectroscopy is performed from the surface of the glass film in the depth direction, and then spectra showing Al emission intensity and Si emission intensity (Al GDS spectrum and Si GDS spectrum) are obtained. Ts, which is the start time of the analysis, is defined as the surface of the glass film, T ^Al _p is defined as the time at which Al shows the maximum emission intensity in the GDS spectrum, F(T ^Al _p ) is defined as the emission intensity of Al at time T ^Al _p , T ^Si _p is defined as the time at which Si shows the maximum emission intensity in the GDS spectrum, and F(T ^Si _p ) is defined as the Al emission intensity at time T ^Si _p (i.e., F(T ^Si _p ) is defined as the intensity emission of Al at the position of the peak of Si emission intensity). When the following expressions (1) and (2) are satisfied, it can be judged that the spinel is sufficiently localized in the glass film near the interface with the base steel sheet.

0.05≤F(T ^Si _p ) / F(T ^Al _p )≤0.50 (expression 1)

2.0≤(T ^Al _p - Ts) / (T ^Si _p - Ts) ≤5.0 (expression 2)

[0020]

The reason why the adhesion of the glass film in the grain-oriented electrical steel sheet is improved by localizing the spinel near the interface, in particular, by fulfilling expression (1) and expression (2), is currently unclear. However, the following reason is assumed. Fine irregularities are formed on the surface of the base steel sheet. When the spinel is localized in the glass film near the interface with the base steel sheet, the spinel is embedded in the concavities of the surface irregularities of the base steel sheet. Thus, the spinel appears to act as an anchor and the adhesion of the glass film to the base steel sheet is improved. A mechanism other than the above mechanism can increase the adhesion of the glass film to the base steel sheet. However, the following examples confirm that when expression (1) and expression (2) are satisfied, the adhesion of the glass film to the base steel sheet is increased.

[0021]

The grain-oriented electrical steel sheet according to the embodiment obtained based on the above has the following features.

[0022]

A grain-oriented electrical steel sheet according to an embodiment includes:

main steel sheet;

a glass film which is placed on the base steel sheet; And

insulating coating with tension, which is located on the glass film,

moreover, the average chemical composition of the base steel sheet and the glass film includes, in wt.%:

0.010% or less C;

2.5-4.0% Si,

0.01-1.00% Mn;

0.010% or less N;

0.010% or less soluble Al;

0.005-0.030% insoluble Al;

0.05-0.20% Mg;

0.05-0.40% O;

0-0.020% Ti;

0.010% or less S;

0.030% or less P;

0-0.50% Sn;

0-0.50%Cr;

0-0.50% Cu;

0-0.0100% Bi;

0-0.020% Se;

0-0.50% Sb; And

a residue consisting of iron and impurities, and

when the glow discharge emission spectroscopy spectra of Al and Si are measured by glow discharge emission spectroscopy from the surface of the glass film in the depth direction,

when Ts, which is the start time of the analysis, is considered as the surface of the glass film,

when T ^Al _p is considered as the time at which Al shows the maximum emission intensity,

when F(T ^Al _p ) is considered as the Al emission intensity at T ^Al _p ,

when T ^Si _p is considered as the time at which Si shows the maximum emission intensity,

when F(T ^Si _p ) is considered as the Al emission intensity at T ^Si _p ,

the values Ts, T ^Al _p , F(T ^Al _p ), T ^Si _p and F(T ^Si _p ) satisfy the expressions

0.05 ≤ F(T ^Si _p ) / F(T ^Al _p ) ≤ 0.50 and

2.0 ≤ (T ^Al _p - Ts) / (T ^Si _p - Ts) ≤ 5.0.

[0023]

In the glass film of the aforementioned grain-oriented electrical steel sheet, the spinel is sufficiently localized near the interface between the glass film and the base steel sheet. Thus, the adhesion of the glass film is improved.

[0024]

In addition, in the grain-oriented electrical steel sheet, the thickness of the base steel sheet may be 0.17 mm or more and less than 0.22 mm.

[0025]

In addition, in the grain-oriented electrical steel sheet, the average chemical composition may include, in wt.%, at least one element selected from:

0.01-0.50% Cr;

0.01-0.50% Sn;

0.01-0.50% Cu;

0.0010-0.0100% Bi;

0.001-0.020% Se; And

0.01-0.50% Sb.

[0026]

In addition, in the grain-oriented electrical steel sheet,

when the glow discharge emission spectroscopy spectra of Al and Fe are measured by glow discharge emission spectroscopy from the surface of the glass film in the depth direction,

when T ^Al _p is considered as the time at which Al shows the maximum emission intensity,

when T ^Fe ₆₀ is considered as the time at which the Fe emission intensity becomes 60% compared to the saturation value of the Fe emission intensity, and

when T ^Fe ₉₀ is considered as the time at which the Fe emission intensity becomes 90% compared to the saturation value of the Fe emission intensity,

the values of T ^Al _p , T ^Fe ₆₀ and T ^Fe ₉₀ can satisfy the expression

T ^Fe ₆₀ ≤T ^Al _p ≤T ^Fe ₉₀ .

[0027]

Next, the grain-oriented electrical steel sheet according to the present embodiment will be described in detail.

[0028]

(Structure of Grain-Oriented Electrical Steel Sheet)

Fig. 1 shows a perspective view of a grain-oriented electrical steel sheet according to an embodiment. As shown in FIG. 1, the grain-oriented electrical steel sheet 1 according to the embodiment includes: a base steel sheet 10; glass film 11; and an insulating coating with tension 12. The glass film 11 is placed on the main steel sheet 10. In FIG. 1, a glass film 11 is placed on the surface of the base steel sheet 10 and is in direct contact with the surface of the base steel sheet 10. A tensioned insulating coating 12 is placed on the glass film 11. In FIG. 1, an insulating coating with tension 12 is placed on the surface of the glass film 11 and is in direct contact with the surface of the glass film 11.

[0029]

On FIG. 1, the tension coating 12 and the glass film 11 are formed on only one surface of the base steel sheet 10. However, as shown in FIG. 2, the tension coating 12 and the glass film 11 can be formed on both surfaces of the base steel sheet 10.

[0030]

(Average chemical composition of base steel sheet 10 and glass film 11)

The chemical composition of the base steel sheet 10 with the glass film 11 after removing the insulation coating with tension 12 (average chemical composition of the base steel sheet 10 and the glass film 11) is obtained by a known composition analysis method. For example, the composition analysis method is as follows.

[0031]

First, the insulating coating under tension 12 is removed from the grain oriented electrical steel sheet 1 . Specifically, the grain-oriented electrical steel sheet 1 is immersed in an aqueous solution of sodium hydroxide, which includes 30-50 mass% NaOH and 50-70 mass% H ₂ O, at a temperature of 80-90°C for 7-10 minutes. . The steel sheet after dipping (basic steel sheet 10 with glass film 11 after removing the insulation coating with tension 12) is washed with water. The steel sheet after washing is dried by blowing warm air for less than about 1 minute. by the above-described processing, the insulating coating under tension 12 is removed, and a base steel sheet 10 with a glass film 11 is obtained.

[0032]

The known compositional analysis method is performed on the base steel sheet 10 with the glass film 11 after removing the insulating coating with tension 12. In particular, the base steel sheet 10 with the glass film 11 is drilled and the resulting chips are collected. This chip dissolves in acid, resulting in a solution. Using this solution, elemental analysis of the chemical composition is performed using ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometer: Inductively Coupled Plasma Emission Spectrometry/Spectroscopy).

[0033]

The Si in the chemical composition of the base steel sheet 10 with the glass film 11 is analyzed by the method (silicon quantification method) defined in JIS G1212 (1997). In particular, when the above chips are dissolved in acid, silicon oxide precipitates. The precipitate (silica) is filtered with filter paper and its mass is measured in order to determine the Si content.

[0034]

The content of C and S is analyzed using a known method of combustion (measurement of absorption in the infrared region of the spectrum after combustion). Specifically, the aforementioned solution is combusted by high-frequency induction heating in an oxygen flow, and the carbon dioxide and sulfur dioxide generated are determined in order to determine the C content and the S content.

[0035]

The N content is analyzed by a known thermoconductometric method after melting in an inert gas flow. The O content is analyzed using a known method of non-dispersive absorption in the infrared region of the spectrum after melting in an inert gas flow.

[0036]

Using the above analytical methods, the chemical composition of the base steel sheet 10 with the glass film 11 (average chemical composition of the base steel sheet 10 and the glass film 11) can be obtained.

[0037]

The grain-oriented electrical steel sheet according to each embodiment includes in its chemical composition basic elements, optional elements as needed, and a balance of Fe and impurities. Hereinafter, unless expressly stated otherwise, "%" referring to chemical composition is "% by weight".

[0038]

0.010% or less C

Carbon (C) is an optional element. C is an essential element for the slab to improve the magnetic flux density. However, C is removed from the steel sheet in the production processes of the grain oriented electrical steel sheet. When more than 0.010% C remains in the average chemical composition, C forms cementite (Fe ₃ C) even if the content of other elements is within the range of the embodiment, and thus the magnetic loss in the grain-oriented electrical steel sheet deteriorates. Thus, the C content should be 0.010% or less. The upper limit of the C content is preferably 0.006%, and more preferably 0.003%. Preferably, the C content is as low as possible. Thus, the C content may be 0%. However, excessive reduction of the C content increases production costs. Thus, the lower limit of the C content is preferably more than 0%, and more preferably 0.001%.

[0039]

2.5 to 4.0% Si

Silicon (Si) is the main element. Si increases the electrical resistance (resistivity) of the steel material, and thereby reduces the magnetic loss in the grain-oriented electrical steel sheet. When the Si content is less than 2.5%, a phase transformation occurs in the steel at the time of final annealing even if the content of other elements is within the range of the embodiment, and as a result, secondary recrystallization does not proceed sufficiently. As a result, the above-described effect is insufficiently obtained. On the other hand, when the Si content is more than 4.0%, the steel sheet becomes brittle even if the content of other elements is within the range of the embodiment, and thus the passability during production deteriorates significantly. Thus, the Si content should be 2.5-4.0%. The lower limit of the Si content is preferably 2.8%, more preferably 3.0%, and even more preferably 3.2%. The upper limit of the Si content is preferably 3.7%, more preferably 3.6%, and even more preferably 3.5%.

[0040]

0.01 to 1.00% Mn

Mn (manganese) is the main element. Mn increases the resistivity of the grain-oriented electrical steel sheet and thereby reduces the magnetic loss. In addition, Mn enhances hot workability and thereby suppresses cracking during hot rolling. In addition, Mn binds to S and/or Se and thereby forms thin MnS and/or thin MnSe. Thin MnS and/or thin MnSe become nuclei for thin AlN to precipitate, which acts as an inhibitor. When the released amount of fine MnS and fine MnSe is sufficient, the amount of AlN becomes sufficient. When the content of Mn is less than 0.01%, a sufficient amount of fine MnS and fine MnSe is not released even if the content of other elements is within the range of the embodiment. On the other hand, when the content of Mn is more than 1.00%, the magnetic flux density and the magnetic loss in the grain-oriented electrical steel sheet deteriorate even if the content of other elements is within the range of the embodiment. Thus, the Mn content should be 0.01-1.00%. The lower limit of the Mn content is preferably 0.02%, more preferably 0.03%, and even more preferably 0.05%. The upper limit of the Mn content is preferably 0.70%, more preferably 0.50%, more preferably 0.30%, and even more preferably 0.10%.

[0041]

0.010% or less N

Nitrogen (N) is an optional element. N forms AlN, which acts as an inhibitor by binding to Al in grain oriented electrical steel sheet production processes. Thus, N is an essential element for a slab, which is a grain oriented electrical steel sheet material. However, N is removed from the steel sheet in the production processes of grain oriented electrical steel sheet. When the N content is more than 0.010% of the average chemical composition, bubbles (voids) tend to be excessively formed in the steel sheet even if the content of other elements is within the range of the embodiment. The bubbles cause defects in the coating, and the insulation of the grain oriented electrical steel sheet deteriorates. Thus, the N content should be 0.010% or less. The upper limit of the N content is preferably 0.008%, more preferably 0.006%, and even more preferably 0.004%. The N content may be 0%. However, it can be difficult to reduce the N content excessively. Thus, the lower limit of the N content is preferably 0.001%, and more preferably 0.002%.

[0042]

0.010% or less soluble Al

Acid-soluble aluminum (soluble Al) is an optional element. Soluble Al forms AlN, which acts as an inhibitor by binding to N in grain oriented electrical steel sheet manufacturing processes. However, when the soluble Al content is more than 0.010%, Al-based precipitates remain in the steel sheet even if the content of other elements is within the range of the embodiment. In this case, the magnetic loss in the grain-oriented electrical steel sheet deteriorates. Thus, the soluble Al content should be 0.010% or less. The upper limit of the soluble Al content is preferably 0.008%, and more preferably 0.006%. The content of soluble Al may be 0%. However, it may be difficult to reduce the Al content excessively. Thus, the lower limit of the Al content is preferably 0.001%, and more preferably 0.002%. In an embodiment, soluble Al means acid soluble Al, and thus soluble Al content means the amount of acid soluble Al.

[0043]

0.005-0.030% insoluble Al

Acid-insoluble aluminum (insoluble Al) is the main element. Insoluble Al is obtained mainly from spinel (MgAl ₂ O ₄ ) formed during the final annealing process, which will be described later. When the content of insoluble Al is less than 0.005%, the spinel is sufficiently incorporated into the glass film 11 even if the content of other elements is within the range of the embodiment, and therefore the adhesion of the glass film 11 becomes insufficient. On the other hand, when the content of insoluble Al is more than 0.030%, an excessive amount of spinel is formed even if the content of other elements is within the range of the embodiment. In this case, spinel is excessively contained not only at the interface between the glass film 11 and the base steel sheet 10, but also inside the glass film 11. When the spinel is excessively contained in the glass film 11, it causes cracks in the glass film 11, and the adhesion of the glass film 11 deteriorates. Thus, the content of insoluble Al should be 0.005-0.030%. The lower limit of insoluble Al content is preferably 0.006%, more preferably 0.007%, and even more preferably 0.010%. The upper limit of the content of insoluble Al is preferably 0.027%, more preferably 0.025%, and even more preferably 0.020%.

[0044]

The content of soluble Al and the content of insoluble Al can be obtained by the following method. The content of soluble Al is obtained by a method for quantitative determination of acid-soluble aluminum based on JIS G1257-10-2:2013 (determination of aluminum - determination of acid-soluble aluminum). In addition, the insoluble Al content is defined as the value obtained by subtracting the above-mentioned soluble Al content from the total Al content, which is obtained by the method for determining the total amount of aluminum based on JIS G1257-10-1:2013 (definition of aluminum - atomization in a flame after decomposition by acids).

[0045]

0.05-0.20% Mg

Magnesium (Mg) is a constituent element (main element) of the glass film. Thus, the Mg content can be 0.05-0.20%. The upper limit of the Mg content is preferably 0.18%, and more preferably 0.16%. The lower limit of the Mg content is preferably 0.08%, and more preferably 0.10%.

[0046]

0.05-0.40%O

Oxygen (O) is the constituent element (main element) of the glass film. Thus, the O content may be 0.05-0.40%. The upper limit of the O content is preferably 0.30%, and more preferably 0.25%. The lower limit of O content is preferably 0.10%, and more preferably 0.15%.

[0047]

0 to 0.020% Ti

Titanium (Ti) is an optional element. Ti promotes the formation of a glass film and preferably provides coating adhesion. Thus, the Ti content may be 0-0.020%. The upper limit of the Ti content is preferably 0.015%, and more preferably 0.010%. The Ti content may be 0%. However, the lower limit of the Ti content is preferably 0.001%, more preferably 0.003%, and even more preferably 0.005%.

[0048]

0.010% or less S

Sulfur (S) is an optional element. Sulfur forms thin MnS, which acts as an inhibitor by binding to Mn in manufacturing processes. Thus, S is an essential element for a slab. However, S is removed from the steel sheet in the production processes of grain oriented electrical steel sheet. When the content of S in the average chemical composition is more than 0.010%, MnS remains in the base steel sheet 10 even if the content of other elements is within the range of the embodiment, and thus the magnetic loss deteriorates. Thus, the S content should be 0.010% or less. The upper limit of the S content is preferably 0.008%, more preferably 0.006%, and even more preferably 0.004%. The S content may be 0%. However, it may be difficult to reduce the S content excessively. Thus, the lower limit of the S content is preferably 0.001%, and more preferably 0.002%.

[0049]

0.030% or less P

Phosphorus (P) is an optional element. P reduces the workability of the steel sheet during rolling. When the P content is more than 0.030%, the workability of the steel sheet is excessively reduced even if the content of other elements is within the range of the embodiment. Thus, the P content should be 0.030% or less. The upper limit of the P content is preferably 0.020%, and more preferably 0.010%. The P content may be 0%. However, it can be difficult to reduce the P content too much. Thus, the lower limit of the P content is preferably 0.001%. P improves the texture, and thereby the magnetic performance of the steel sheet is improved. In order to obtain these effects, the lower limit of the P content is preferably 0.002%, and more preferably 0.005%.

[0050]

The grain-oriented electrical steel sheet according to the embodiment may contain impurities in its average chemical composition. The impurities correspond to elements that are introduced during the industrial production of grain oriented electrical steel sheet from ores and scrap that are used as raw materials, from the environment of the production process, or that remain in the steel as a result of their incomplete removal by refining annealing. In addition, the impurities correspond to elements that are allowed in a range that does not adversely affect the grain-oriented electrical steel sheet of the embodiment.

[0051]

The grain-oriented electrical steel sheet according to the embodiment may include in its chemical composition at least one element selected from the group consisting of Cr, Sn, Cu, Bi, Se, and Sb instead of a portion of Fe which is the remainder.

[0052]

0 to 0.50%Cr

Chromium (Cr) is an optional element. Thus, the Cr content can be 0%. When Cr is contained, it improves the adhesion of the glass film 11 to the base steel sheet 10, as it does for Sn and Cu. In addition, Cr increases the degree of grain alignment to the Goss orientation. When a small amount of Cr is contained, this effect can be obtained. However, when the Cr content is more than 0.50%, Cr forms Cr oxides even if the content of other elements is within the range of the embodiment, and as a result, the magnetic performance of the grain-oriented electrical steel sheet 1 deteriorates. Thus, the Cr content can be from 0 to 0.50%. The upper limit of the Cr content is preferably 0.40%, more preferably 0.30%, even more preferably 0.20%, and most preferably 0.10%. The lower limit of the Cr content is preferably more than 0%, more preferably 0.01%, even more preferably 0.03%, and most preferably 0.05%.

[0053]

0 to 0.50% Sn

Tin (Sn) is an optional element. Thus, the Sn content can be 0%. When Sn is contained, it improves the adhesion of the glass film 11 to the base steel sheet 10, as it does for Cr and Cu. When a small amount of Sn is contained, this effect can be obtained. However, when the content of Sn is more than 0.50%, the secondary recrystallization becomes unstable during the production of the grain-oriented electrical steel sheet 1 even if the content of other elements is within the range of the embodiment, and as a result, the magnetic characteristics of the electrical steel sheet 1 with oriented grain structure deteriorate. Thus, the content of Sn can be from 0 to 0.50%. The lower limit of the Sn content is preferably greater than 0%, more preferably 0.01%, even more preferably 0.02%, and most preferably 0.03%.

[0054]

0 to 0.50% Cu

Copper (Cu) is an optional element. Thus, the Cu content can be 0%. When Cu is contained, it improves the adhesion of the glass film 11 to the base steel sheet 10, as is the case for Cr and Sn. When a small amount of Cu is contained, this effect can be obtained. However, when the content of Cu is more than 0.50%, the hot workability at the time of production of the grain-oriented electrical steel sheet 1 deteriorates even if the content of other elements is within the range of the embodiment. Thus, the Cu content can be from 0 to 0.50%. The lower limit of the Cu content is preferably greater than 0%, more preferably 0.01%, even more preferably 0.03%, and most preferably 0.05%. The upper limit of the Cu content is preferably 0.40%, more preferably 0.30%, even more preferably 0.20%, and most preferably 0.10%.

[0055]

0 to 0.0100% Bi

Bismuth (Bi) is an optional element. Thus, the content of Bi can be 0%. When Bi is contained, it acts as an inhibitor as well as Se and Sb, and thus the secondary recrystallization is made stable during the production of grain-oriented electrical steel sheet 1. As a result, the magnetic characteristics of the grain-oriented electrical steel sheet 1 are improved. When a small amount of Bi is contained, this effect can be obtained. However, when the Bi content is more than 0.0100%, the adhesion of the glass film 11 to the base steel sheet 10 deteriorates even if the content of other elements is within the range of the embodiment. Thus, the content of Bi can be from 0 to 0.0100%. The lower limit of the Bi content is preferably more than 0%, more preferably 0.0010%, and even more preferably 0.0020%. The upper limit of the Bi content is preferably 0.0090%, more preferably 0.0070%, and even more preferably 0.0050%.

[0056]

0 to 0.020% Se

Selenium (Se) is an optional element. Thus, the Se content can be 0%. When Se is contained, it acts as an inhibitor as well as Bi and Sb, and thus the secondary recrystallization is made stable during the production of the grain-oriented electrical steel sheet 1. As a result, the magnetic characteristics of the grain-oriented electrical steel sheet 1 are improved. When a small amount of Se is contained, this effect can be obtained. However, when the Se content is more than 0.020%, the adhesion of the glass film 11 to the base steel sheet 10 deteriorates even if the content of other elements is within the range of the embodiment. Thus, the Se content can be from 0 to 0.020%. The lower limit of the Se content is preferably more than 0%, more preferably 0.001%, even more preferably 0.003%, and most preferably 0.005%. The upper limit of the Se content is preferably 0.015%, more preferably 0.010%, and even more preferably 0.008%.

[0057]

0 to 0.50% Sb

Antimony (Sb) is an optional element. Thus, the Sb content can be 0%. When Sb is contained, it acts as an inhibitor as well as Bi and Se, and thus the secondary recrystallization is made stable during the production of grain-oriented electrical steel sheet 1. As a result, the magnetic characteristics of the grain-oriented electrical steel sheet 1 are improved. When a small amount of Sb is contained, this effect can be obtained. However, when the content of Sb is more than 0.50%, the adhesion of the glass film 11 to the base steel sheet 10 deteriorates even if the content of other elements is within the range of the embodiment. Thus, the Sb content can be from 0 to 0.50%. The lower limit of the Sb content is preferably greater than 0%, more preferably 0.01%, even more preferably 0.03%, and most preferably 0.05%. The upper limit of the Sb content is preferably 0.40%, more preferably 0.30%, even more preferably 0.20%, and most preferably 0.10%.

[0058]

In addition, in the grain-oriented electrical steel sheet 1 according to the embodiment, it is preferable that the average chemical composition includes, in wt %, at least one element selected from the group consisting of:

0.01-0.50% Cr;

0.01-0.50% Sn;

0.01-0.50% Cu;

0.0010-0.0100% Bi;

0.001-0.020% Se; And

0.01-0.50% Sb.

[0059]

As explained above, Cr, Sn and Cu favorably influence the adhesion of the glass film 11. Thus, the average chemical composition may also contain at least one element selected from the group consisting of: 0.01-0.50% Cr; 0.01-0.50% Sn and 0.01-0.50% Cu. In addition, as explained above, Bi, Se, and Sb favorably affect the magnetic characteristics of the grain-oriented electrical steel sheet 1. Thus, the average chemical composition may also contain at least one element selected from the group consisting of: 0.0010-0.0100% Bi; 0.001-0.020% Se and 0.01-0.50% Sb.

[0060]

(Glass film 11)

A glass film 11 is formed on the base steel sheet 10. The glass film 11 mainly includes forsterite (Mg ₂ SiO ₄ ). In order to confirm the existence of the glass film 11 in the grain-oriented electrical steel sheet of the embodiment, X-ray diffraction can be performed on the surface after removing the insulating coating with tension 12 by the above method, and the obtained X-ray diffraction spectrum can be compared with a PDF (file powder diffraction). Forsterite (Mg ₂ SiO ₄ ) can be identified as JCPDS No. 34-189. In the embodiment, when the main constituent phase in the above X-ray diffraction spectrum is forsterite, the grain-oriented electrical steel sheet 1 is considered to include a glass film 11.

[0061]

For example, the amount of forsterite in the glass film 11 may be 60.0 mass% or more.

[0062]

The thickness of the glass film 11 is not particularly limited. The lower limit of the thickness of the glass film 11 is preferably 1.0 µm, and more preferably 2.0 µm. The upper limit of the thickness of the glass film 11 is preferably 5.0 µm, and more preferably 4.0 µm.

[0063]

(Insulating cover with tension 12)

A tension insulating coating 12 is formed on the glass film 11. A tension insulating coating 12 is formed as an outer layer for the grain oriented electrical steel sheet 1 to ensure electrical insulation between the grain oriented electrical steel sheets 1 which are laminated to each other, when a plurality of grain-oriented electrical steel sheets 1 are used after their lamination.

[0064]

In order to confirm the presence of an insulating coating with a tension of 12 in the grain oriented electrical steel sheet of the embodiment, a SEM-EDS quantitative analysis of the outer layer of the grain oriented electrical steel sheet 1 can be performed to confirm the chemical composition. For example, when the SEM-EDS quantitative analysis results satisfy the Fe content of less than 80 at.%, the P content of 5 at.% or more, the Si content of less than 20 at.%, the O content of 50 at.% or more, and the Mg content of 10 at. % or less, excluding measurement noise, the grain-oriented electrical steel sheet 1 is considered to include an insulating coating with a tension of 12.

[0065]

For example, a 12 tension insulation coating is formed by applying an insulation coating solution including at least one of inorganic substances such as metal chromate, metal phosphate, colloidal silica, polytetrafluoroethylene, a Zr compound, and a Ti compound, and baking it. The insulation coating solution may mainly comprise a phosphate compound. For example, the insulation coating solution may include a phosphate compound in an amount of 80% by weight or more.

[0066]

In addition to the phosphate compound, the 12 tension coating solution may include at least one substance selected from the group consisting of colloidal silica and polytetrafluoroethylene. For example, the phosphate compound is sodium phosphate, aluminum phosphate, magnesium phosphate, and the like.

[0067]

The thickness of the insulation coating with tension 12 is not particularly limited. The lower limit of the thickness of the glass film 12 is preferably 0.1 µm, and more preferably 0.5 µm. The upper limit of the thickness of the glass film 12 is preferably 10.0 µm, and more preferably 5.0 µm.

[0068]

(Degree of localization of spinel (MgAl ₂ O ₄ ) in glass film 11)

In the grain-oriented electrical steel sheet 1 according to the embodiment, spinel (MgAl ₂ O ₄ ) is localized near the interface with the base steel sheet 10 in the glass film 11. Specifically, glow discharge emission spectroscopy is conducted from the surface of the glass film 11 in the depth direction after removal an insulating coating with a tension of 12, and spectra showing the emission intensity of Al and the emission intensity of Si (GDS spectrum of Al and GDS spectrum of Si) are measured. Ts, which is the start time of the analysis, is defined as the surface of the glass film, T ^Al _p is defined as the time at which Al shows the maximum emission intensity in the GDS spectrum, F(T ^Al _p ) is defined as the emission intensity of Al at time T ^Al _p ( in particular, the maximum Al emission intensity), T ^Si _p is defined as the time at which Si shows the maximum emission intensity in the GDS spectrum, and F(T ^Si _p ) is defined as the Al emission intensity at time T ^Si _p (i.e. F(T ^Si _p ) is defined as the Al emission intensity at the peak position of the Si emission intensity). Ts, T ^Al _p , F(T ^Al _p ), T ^Si _p and F(T ^Si _p ) satisfy expression (1) and expression (2).

0.05 ≤ F(T ^Si _p ) / F(T ^Al _p ) ≤ 0.50 (expression 1)

2.0 ≤ (T ^Al _p - Ts) / (T ^Si _p - Ts) ≤ 5.0 (expression 2)

[0069]

Next, expression (1) and expression (2) are explained.

[0070]

(Expression (1))

In the grain-oriented electrical steel sheet 1 according to the embodiment, spinel (MgAl ₂ O ₄ ) is distributed in the glass film 11 in its thickness direction, and the distribution of the spinel has a peak near the boundary with the base steel sheet 10 in the glass film 11. In particular, GDS the Al spectrum has a peak near the boundary with the base steel sheet 10 in the glass film 11. In the grain-oriented electrical steel sheet 1 of the embodiment, since the peak of the Al GDS spectrum near the boundary between the glass film 11 and the base steel sheet 10 becomes sharp, it is believed that the spinel is localized near the boundary between the glass film 11 and the main steel sheet 10.

[0071]

Fig. 3 shows the emission spectra of Al and Si (GDS spectra of Al and Si) in the case where Ts, which is the analysis start time, is considered as the surface of the glass film 11, the analysis time (in seconds) is plotted on the horizontal axis, and the intensity is plotted on the vertical axis. emissions (GDS intensity) (in arbitrary units). Time Ts, time T ^Al _p , emission intensity F(T ^Al _p ), time T ^Si _p , and emission intensity F(T ^Si _p ) shown in FIG. 3 are defined as follows.

[0072]

Analysis start time Ts

In the glow discharge emission spectrum, the time Ts, which is the start time of the analysis, is defined as the surface of the glass film 11.

[0073]

_Time ^TAlp

Glow discharge emission spectroscopy is carried out from the surface of the glass film 11 in the depth direction after removing the insulating coating with tension 12 from the grain oriented electrical steel sheet 1, and an Al emission spectrum (Al GDS spectrum) is measured showing the relationship between analysis time and emission intensity Al, when Ts, which is the start time of the analysis, is considered as the surface of the glass film 11. In this document, the analysis time corresponds to the depth from the surface of the glass film 11. For the obtained GDS spectrum of Al, the maximum value of the emission intensity and the time corresponding to this maximum value are confirmed. The confirmed time is defined as the time T ^Al _p . Specifically, the time T ^Al _p corresponds to a depth position (depth position from the surface of the glass film 11) at which the Al concentration (GDS Al intensity) has a peak.

[0074]

Emission intensity F(T ^Al _p )

The maximum value of the Al emission intensity in the Al spectrum (Al GDS spectrum), namely the maximum Al emission intensity at time T ^Al _p , is defined as F(T ^Al _p ).

[0075]

Time T ^Si _p

Glow discharge emission spectroscopy is carried out from the surface of the glass film 11 in the depth direction after removing the insulating coating with tension 12 from the grain oriented electrical steel sheet 1, and the Si emission spectrum (GDS spectrum Si) showing the relationship between analysis time and emission intensity is measured. Si when Ts being the analysis start time is considered as the surface of the glass film 11. As explained above, the analysis time corresponds to the depth from the surface of the glass film 11. For the obtained GDS spectrum of Si, the maximum value of the emission intensity and the time corresponding to this maximum value are confirmed . The confirmed time is defined as the time T ^Si _p . Specifically, the time T ^Si _p corresponds to a depth position (depth position from the surface of the glass film 11) at which the Si concentration (GDS Si intensity) has a peak.

[0076]

Emission intensity F(T ^Si _p )

The Al emission intensity at time T ^Si _p in the Al spectrum (Al GDS spectrum) is defined as F(T ^Si _p ).

[0077]

The main component of the glass film 11 is forsterite (Mg ₂ SiO ₄ ). Thus, the GDS spectrum of Si has a peak at the center of the glass film 11 in the depth direction. In particular, the time T ^Si _p corresponds to the position of the center of the glass film 11 in the depth direction. In other words, F(T ^Si _p ) represents the concentration of Al at the position of the center of the glass film 11 in the depth direction.

[0078]

It is determined that F1=F(T ^Si _p ) / F(T ^Al _p ). F1 is the ratio of the maximum Al concentration (F(T ^Al _p )) in the glass film 11 to the typical Al concentration F(T ^Si _p )) in the region not containing the Al concentration peak position in the glass film 11. F1 is an index showing the degree of spinel localization in the glass coating 11.

[0079]

When F1 is less than 0.05, an excessive amount of spinel is formed near the interface with the base steel sheet 10 in the glass film 11. The spinel that is localized near the interface with the base steel sheet 10 increases coating adhesion. However, when the amount of localized spinel is excessive, the smoothness of the interface between the glass film 11 and the base steel sheet 10 deteriorates (in other words, the roughness increases). As a result, even when the value of F2 to be explained below satisfies the expression (2), the magnetic performance deteriorates.

[0080]

On the other hand, when F1 is more than 0.50, the spinel is not present near the border with the main steel sheet 10 in the glass film 11, but inside the glass film 11. Alternatively, although the spinel is present near the border with the main steel sheet 10 in the glass film 11, the amount of spinel formed is insufficient. In this case, the adhesion of the coating of the glass film 11 to the base steel sheet 10 deteriorates.

[0081]

When F1 is 0.05-0.50, in other words, when F1 satisfies the expression (1), a suitable amount of spinel is present near the interface with the base steel sheet 10 in the glass film 11. Thus, as long as the expression (2) is satisfied, the adhesion of the coating glass film 11 to the base steel sheet 10 is improved.

[0082]

(Expression (2))

It is determined that F2=(T ^Al _p - Ts) / (T ^Si _p - Ts). As shown in FIG. 3, F2 is the ratio between the Al concentration peak position and the Si concentration peak position (in particular, the position of the center of the glass film 11 in the depth direction). F2 is an index showing the localized position of the spinel in the glass film 11.

[0083]

When F2 is less than 2.0, the peak position of the Al concentration is located inside the glass film 11 rather than near the interface with the base steel sheet 10 in the glass film 11. In particular, the spinel is not localized near the interface with the base steel sheet 10, but is present in the glass film 11. In this case, F1 also exceeds the upper limit of the expression (1), and as a result, the adhesion of the glass film 11 to the base steel sheet 10 deteriorates. On the other hand, when F2 is more than 5.0, the amount of glass film 11 formed is insufficient compared to the amount of spinel formed. In other words, the glass film 11 becomes thinner. In this case, even when F1 satisfies the expression (1), the tension of the glass film 11, which is required to refine the magnetic domains, decreases. As a result, the magnetic loss deteriorates and the adhesion of the coating also deteriorates.

[0084]

At present, the detailed reason why the adhesion of the glass film 11 to the base steel sheet 10 is improved when a suitable amount of spinel is formed near the boundary with the base steel sheet 10 in the glass film 11 is unclear. However, the following reason is assumed. Fine irregularities are formed on the surface of the base steel sheet 10. When the spinel is localized in the glass film 11 near the interface with the main steel sheet 10, the spinel is embedded in the concavities of the surface irregularities of the main steel sheet 10. Thus, the spinel appears to act as an anchor, and the adhesion of the glass film 11 to the main steel sheet 10 improves. A mechanism other than the above mechanism may increase the adhesion of the glass film 11 to the base steel sheet 10. However, the following examples confirm that when F1 satisfies the expression (1) and F2 satisfies the expression (2), the adhesion of the glass film 11 to the base steel sheet 10 increases.

[0085]

(Method of obtaining F1 and F2)

The values of F1 and F2 can be obtained in the following way. First, from the central region of the grain-oriented electrical steel sheet 1 in the transverse direction TD, a sample is taken, the size of which is 30 mm in the rolling direction RD, 40 mm in the transverse direction TD, and the thickness is equal to the thickness of the grain-oriented electrical steel sheet 1. The insulating coating with tension 12 is removed from the above sample. Specifically, the grain-oriented electrical steel sheet 1 is immersed in an aqueous solution of sodium hydroxide, which includes 30-50 mass% NaOH and 50-70 mass% H ₂ O, at a temperature of 80-90°C for 7-10 minutes. . The steel sheet after dipping (basic steel sheet 10 with glass film 11 after removing the insulation coating with tension 12) is washed with water. The steel sheet after washing is dried by blowing warm air for about less than 1 minute. With the above processing, a sample with a base steel sheet 10 and a glass film 11, and without a tension insulating coating 12, shown in FIG. 4.

[0086]

Glow discharge emission spectroscopy (GDS) is conducted from the surface of the sample glass film 11 in the depth direction, and emission spectra (GDS spectra) of Al and Si are measured. In particular, using a high-frequency glow discharge emission spectroscope (GD-ODS), the GDS spectra of Al and Si in the depth direction on the glass film 11 are measured under the condition of supplying electricity with a power of 30 W to the sample as a cathode in an argon atmosphere (Ar pressure: 3 hPa). The measurement area is 4mm φ, the measurement time is 100s, and the measurement interval is 0.02s.

[0087]

Preferably, the F1 and F2 values are obtained after smoothing the measured GDS spectrum. For example, a simple moving average method can be used as a GDS spectrum smoothing method.

[0088]

From the resulting GDS spectrum of Al TAlp, T ^Al _p values are measured, i.e. the time at which the maximum Al emission intensity is observed, and F(T ^Al _p ), i.e. Al emission intensity at time T ^Al _p .

[0089]

In addition, the value of T ^Si _p is measured from the obtained GDS spectrum of Si, i.e. the time at which the maximum Si emission intensity is observed. After that, the value of F(T ^Si _p ) is measured from the GDS spectrum of Al, i.e. Al emission intensity at time T ^Si _p . The analysis starts at time Ts. Using the time Ts, T ^Al _p , F(T ^Al _p ), T ^Si _p , F(T ^Si _p ), F1 and F2 are obtained.

[0090]

In the grain-oriented electrical steel sheet 1 according to the embodiment, the F1 value satisfies the expression (1) and the F2 value satisfies the expression (2). Thus, a suitable amount of spinel is localized near the interface with the base steel sheet 10 in the glass film 11, and as a result, the adhesion of the glass film 11 to the base steel sheet 10 is increased.

[0091]

When F1 satisfies expression (1) and F2 satisfies expression (2), it can be judged that the spinel is localized near the interface with the main steel sheet 10 in the glass film 11.

[0092]

In addition, it can be judged whether the spinel is localized near the interface with the base steel sheet 10 in the glass film 11 by the following feature.

[0093]

When the spectra of Al and Fe are measured by glow discharge emission spectroscopy from the surface of the glass film in the depth direction,

when T ^Al _p is considered as the time at which Al shows the maximum emission intensity,

when T ^Fe ₆₀ is considered as the time at which the Fe emission intensity becomes 60% compared to the saturation value of the Fe emission intensity, and

when T ^Fe ₉₀ is considered as the time at which the Fe emission intensity becomes 90% compared to the saturation value of the Fe emission intensity,

the values of T ^Al _p , T ^Fe ₆₀ and T ^Fe ₉₀ can satisfy the expression

T ^Fe ₆₀ ≤T ^Al _p ≤T ^Fe ₉₀ (expression 3)

[0094]

When expression (3) is satisfied in addition to expression (1) and expression (2), it can be judged that the spinel is localized near the border with the main steel sheet 10 in the glass film 11, which is preferable. The above "Fe emission intensity saturation value" can be considered, for example, as the Fe emission intensity 100 s after the start of the glow discharge emission spectroscopy measurement.

[0095]

(Mode of production)

Next, the production method of grain-oriented electrical steel sheet according to the embodiment will be explained as an example. In the grain-oriented electrical steel sheet 1 of the embodiment, if the above features are present, the production method is not particularly limited. The following production method is an example of the production of the grain-oriented electrical steel sheet 1 according to the embodiment, and is a preferred example of the production of the grain-oriented electrical steel sheet 1 according to the embodiment.

[0096]

(Sequence of production processes)

Fig. 5 is a flowchart showing a production method of grain-oriented electrical steel sheet 1 according to the embodiment. As shown in FIG. 5, the production method includes: (S1) slab hot rolling process; (S2) hot rolling steel sheet annealing process; (S3) cold rolling process (S30) one or more times of the steel sheet after annealing the hot rolled steel sheet; (S4) a process for decarburizing annealing the steel sheet (cold rolled steel sheet) after cold rolling; (S5) a process of applying the annealing separator to the surface of the steel sheet after the decarburization annealing; (S6) a final annealing process of the steel sheet after applying the annealing separator to form a glass film; and (S7) a process of forming an insulating coating under tension for the steel sheet after the final annealing. Next, each process S1 to S7 is explained.

[0097]

(Process (S1) hot rolling)

In the hot rolling process (S1), the prepared slab is subjected to hot rolling to produce a hot-rolled steel sheet. The chemical composition of the slab is controlled so that the average chemical composition of the base steel sheet 10 and the glass film 11 of the grain-oriented electrical steel sheet 1 satisfies the above-described chemical composition. The content of Al in the slab should be 0.01 mass% or more. When the Al content of the slab is less than 0.01 mass%, the spinel is not sufficiently formed in the glass film 11. The slab can be produced by a known method. For example, molten steel is produced (smelted). Using molten steel, the slab is formed by continuous casting.

[0098]

The prepared slab is hot rolled in a hot rolling mill, resulting in a hot rolled steel sheet. First, the steel billet is heated. For example, the slab is placed in a known heating furnace or a known holding furnace and heated. The heating temperature of the slab is preferably 1100 to 1450°C. The lower limit of the slab heating temperature is preferably 1300°C. The upper limit of the slab heating temperature is preferably 1400°C.

[0099]

The heated slab is hot rolled in a hot rolling mill, resulting in a hot rolled steel sheet. The hot rolling mill includes a rough rolling mill and a finishing mill downstream of the rough rolling mill. The rough rolling mill includes one or more rough rolling stands arranged in a row. Each rough rolling stand has a plurality of rolls arranged one above the other. The rough rolling stand may be of the reversible type. In the case of several rough rolling stands, the rough rolling mill may be of the tandem or reverse type. The finishing rolling mill includes finishing rolling stands arranged in a row. Each finishing stand has several rolls arranged one above the other. The heated slab is rolled in a rough rolling mill and then in a finishing mill, and thus a hot rolled steel sheet is obtained.

[0100]

The thickness of the hot-rolled steel sheet produced by hot rolling is not particularly limited, and may be a known thickness. For example, the thickness of the hot rolled steel sheet may be 2.0-3.0 mm.

[0101]

(Process (S2) annealing of hot-rolled steel sheet)

The hot-rolled steel sheet annealing process (S2) is optional and may not be performed. When annealing of the hot-rolled steel sheet is performed, in the hot-rolled steel sheet annealing process (S2), the hot-rolled steel sheet obtained by the hot-rolling process (S1) is annealed to obtain a steel sheet after annealing the hot-rolled steel sheet. When annealing is performed on the hot-rolled steel sheet, recrystallization occurs in the steel structure, and as a result, the magnetic characteristics are improved.

[0102]

The annealing process (S2) of the hot-rolled steel sheet can be performed by a known method. The method for heating the hot-rolled steel sheet is not particularly limited, and may be a known method. For example, the annealing heating temperature is preferably 900-1200°C, and the holding time at the annealing temperature is preferably 10-300 seconds. When the hot-rolled steel sheet annealing process (S2) is performed, pickling of the hot-rolled steel sheet may be performed after the hot-rolled steel sheet annealing process (S2) and before the cold rolling process (S3).

[0103]

(Cold rolling process (S3))

In the cold rolling process (S3), the produced steel sheet (hot-rolled steel sheet or steel sheet after annealing of the hot-rolled steel sheet) is subjected to cold rolling (S30) one or more times. Cold rolling (S30) is performed using a cold rolling mill. For example, the cold rolling mill is a tandem type mill that includes a plurality of cold rolling stands arranged in a row, and each cold rolling stand includes a plurality of cold rolling rolls. The cold rolling mill may be a reversible cold rolling stand.

[0104]

In the cold rolling process (S3), cold rolling (S30) may be performed one or more times. When cold rolling is performed several times, intermediate softening annealing of the steel sheet may be performed after cold rolling using a cold rolling mill. In this case, after intermediate annealing, subsequent cold rolling is performed. In other words, intermediate annealing may be carried out between cold rolling passes.

[0105]

The intermediate annealing between cold rolling and the next cold rolling can be carried out under known conditions. For example, the intermediate annealing temperature is preferably 950-1200°C, and the holding time at the annealing temperature is preferably 30-1800 seconds. The stress introduced into the steel sheet by the previous cold rolling is reduced by intermediate annealing (the steel sheet is softened), and then the next cold rolling is performed.

[0106]

In the case where cold rolling is performed several times without intermediate annealing, it may be difficult to ensure uniform characteristics in the produced grain-oriented electrical steel sheet. On the other hand, in the case where cold rolling is performed several times with intermediate annealing between cold rolling passes, the magnetic flux density in the produced grain-oriented electrical steel sheet 1 may decrease. Thus, the number of cold rolling and intermediate annealing operations are determined in accordance with the characteristics required for the produced grain oriented electrical steel sheet 1 and the production cost thereof.

[0107]

As explained above, the cold rolling may be performed once.

[0108]

The cumulative reduction in single or multiple cold rolling is preferably 80-95%. In this document, the cumulative cold rolling reduction is defined as follows.

Cold rolling reduction (%)=((Steel plate thickness before first cold rolling - Cold rolled steel plate thickness after finish cold rolling) / Steel plate thickness before first cold rolling) × 100

[0109]

When cold rolling is carried out only once in the cold rolling process, the aforementioned cold rolling reduction is one-time cold rolling reduction. When the total cold rolling reduction is 80% or more, recrystallization nuclei (Goss nuclei) having a Goss orientation ({110} <001> orientation) can be sufficiently formed. In addition, when the total cold rolling reduction is 95% or less, the secondary recrystallization can be made stable during the final annealing process (S6) to be explained below. The steel sheet produced by the cold rolling process is wound into coil form.

[0110]

Generally, the thickness of the cold rolled steel sheet (thickness after the cold rolling process (S3)) is different from the thickness of the grain oriented electrical steel sheet 1 which is the final product (product thicknesses including the glass film 11 and the insulating coating under tension 12).

[0111]

In order to further improve the magnetic characteristics, an aging treatment may be performed in the cold rolling process (S3). Aging treatment is optional. In the case where the aging treatment is performed, the aging treatment (annealing) is performed between cold rolling passes (S30). Specifically, the aging treatment is carried out after the cold rolling (S30), and then the next cold rolling (S30) is carried out after the aging treatment. The aging treatment may be performed under known conditions. For example, a heat treatment as an aging treatment is performed for 60 seconds or more at a temperature of 100 to 500°C for the steel sheet after cold rolling (S30). In this case, a favorable secondary recrystallization structure aligned in the Goss orientation can be finally obtained.

[0112]

(Process (S4) decarburization annealing)

In the decarburization annealing process (S4), the steel sheet (cold-rolled steel sheet) after the cold rolling process (S3) is subjected to decarburization annealing, and thereby primary recrystallization is performed.

[0113]

The decarburization annealing process (S4) includes a heating step (S41), a decarburization step (S42), and a cooling step (S43). In the heating step (S41), the steel sheet is heated to a decarburization annealing temperature Ta. In the decarburization step (S42), the steel sheet which is heated to the decarburization annealing temperature Ta is decarburized, and thereby primary recrystallization is performed. In the cooling step (S43), the steel sheet after the decarburization step (S42) is cooled in a known manner. Next, each stage is described in detail.

[0114]

(Step (S41) heating)

In the heating step, first, the steel sheet after the cold rolling process (S3) is placed in a heat treatment furnace. In the decarburization annealing furnace according to the embodiment, for example, a cold rolled steel sheet is heated to the decarburization annealing temperature in a controlled manner by high frequency induction heating or electric heating. The atmosphere during the heating step may be a dry nitrogen atmosphere or a dry mixed nitrogen and hydrogen atmosphere, and may have an oxidation state (PH ₂ O/PH ₂ ) of 0.1 or less. When the oxidation state in the heating step is more than 0.1, iron-based oxides tend to nucleate. The Fe-based oxides, which are nucleated during the heating step, grow during the decarburization annealing. When these oxides are present at the final anneal, the growth of forsterite (Mg ₂ SiO ₄ ) is suppressed. Although the reason for this is unclear, Fe-based oxides have the function of suppressing the solid phase reaction between SiO ₂ and MgO. As a result, the Mg ₂ SiO ₄ becomes thinner, and the spinel tends not to localize near the interface with the base steel sheet 10 in the glass film 11. In particular, spinel (MgAl ₂ O ₄ ) tends to be present in Mg ₂ SiO ₄ .

[0115]

In addition, although not particularly limited, the heating rate may be 2000°C/s or less, and the attainable temperature may be 700-1000°C. Here, the temperature reached is different from the decarburization annealing temperature Ta in the decarburization step.

[0116]

(Step (S42) decarburization)

In the decarburization step (S42) of the decarburization annealing process (S4), the steel sheet after the heating step (S41) is held at the decarburization annealing temperature Ta to conduct decarburization annealing. As a result, primary recrystallization occurs. The atmosphere during the decarburization step may be a known atmosphere, such as a humid mixed atmosphere of nitrogen and hydrogen. When performing decarburization annealing, carbon is removed from the steel sheet and primary recrystallization occurs. The production conditions in the decarburization step are as follows.

[0117]

Decarburizing annealing temperature Ta: 800-950°C

As explained above, the decarburization annealing temperature Ta corresponds to the temperature of the decarburization annealing furnace, and corresponds to the temperature of the steel sheet during the decarburization annealing. When the decarburization annealing temperature Ta is less than 800° C., the grains of the steel sheet after primary recrystallization become too fine. In this case, secondary recrystallization during the final annealing process (S6) does not occur sufficiently. On the other hand, when the decarburization annealing temperature Ta is over 950° C., the grains of the steel sheet after primary recrystallization become too coarse. In this case, the secondary recrystallization during the final annealing process (S6) also occurs insufficiently. When the decarburization annealing temperature Ta is 800-950° C., the grains of the steel sheet after primary recrystallization are of a suitable size, and secondary recrystallization occurs sufficiently during the final annealing process (S6).

[0118]

The holding time at the decarburization annealing temperature Ta in the decarburization step (S42) is not particularly limited. For example, the holding time at the decarburization annealing temperature Ta may be 15-150 seconds.

[0119]

(Step (S43) cooling)

In the cooling step (S43), the steel sheet after the decarburization step (S42) is cooled in a known manner. The cooling method may be air-cooled, water-cooled, or the like. Preferably, the steel sheet is air-cooled after the decarburization step. In the decarburization annealing process (S4), the steel sheet is subjected to decarburization annealing by performing the above steps.

[0120]

(Process (S5) for applying the annealing separator)

The steel sheet after the decarburization annealing process (S4) is subjected to an annealing separator application process (S5). In the process (S5) of applying the annealing separator, the annealing separator is applied to the surface of the steel sheet. Specifically, an aqueous slurry including an annealing separator is applied to the surface of the steel sheet. An aqueous slurry is prepared by adding water to the annealing separator and mixing them. The annealing separator includes magnesium oxide (MgO). Preferably, MgO is the main component of the annealing separator. Here, "main component" means that the content of MgO in the annealing separator is 80.0 mass% or more. The annealing separator may include known additives in addition to MgO. For example, the annealing separator may include a Ti compound.

[0121]

In the process (S5) of applying the annealing separator, an aqueous slurry including the annealing separator is applied to the surface of the steel sheet. The steel sheet after applying the annealing separator on its surface is wound into a roll. The steel sheet after coiling is subjected to a final annealing process (S6).

[0122]

The sintering treatment may be carried out after winding up the steel sheet, on the surface of which the aqueous suspension including the annealing separator is applied, and before the final annealing process (S6). In the baking processing, the coiled steel sheet is placed and kept in an oven at a temperature of 400-1000°C (baking processing). As a result, the annealing separator applied to the steel sheet is dried. For example, the dwell time may be 10-90 seconds. The coiled steel sheet coated with the annealing separator can be subjected to a final annealing process without performing a baking treatment.

[0123]

(Final annealing process (S6))

The steel sheet after the annealing separator application process (S5) is subjected to the final annealing process (S6), and thereby secondary recrystallization is performed. In addition, in the final annealing process, two annealing steps (low-temperature annealing step (S61) and high-temperature annealing step (S62)) are performed. As a result, a glass film 11 is formed, which mainly includes forsterite, and a suitable amount of spinel is localized near the interface with the base steel sheet 10 in the glass film 11. These two annealing steps (low temperature annealing step (S61) and elevated temperature) are carried out in a heat treatment furnace. Next, the low temperature annealing step (S61) and the elevated temperature annealing step (S62) are explained.

[0124]

(Step (S61) of annealing at a reduced temperature)

The reduced temperature annealing step (S61) forms a glass film 11. In the reduced temperature annealing step (S61), the first coiled steel sheet is placed in a heat treatment furnace and heated to the reduced temperature annealing temperature T1. The steel sheet is held at the temperature T1 for the holding time t1. The atmosphere in the furnace during the low temperature annealing step (S61) may be a mixed atmosphere of nitrogen and hydrogen.

[0125]

The low temperature annealing temperature T1 (°C) and the holding time t1 in the low temperature annealing step (S61) are as follows.

Low temperature annealing temperature T1: 910-1000°C

Holding time t1 at 910-1000°C: 50-120 hours

[0126]

(Reduced temperature annealing temperature T1)

910-1000°C is a temperature range in which forsterite (Mg ₂ SiO ₄ ) is formed, which is the main component of the glass film 11.

[0127]

When the low temperature annealing temperature T1 is less than 910° C., alumina is formed (4Al+3SiO ₂ → 2Al ₂ O ₃ +3Si) before forsterite (2MgO+SiO ₂ → Mg ₂ SiO ₄ ) is formed. As a result, after the step (S62) of annealing at an elevated temperature, the spinel is not included near the boundary with the base steel sheet 10 in the glass film 11, but inside the glass film 11. Thus, F1 does not satisfy the upper limit of expression (1), and/or F2 does not satisfies the lower limit of expression (2).

[0128]

When the low temperature annealing temperature T1 is more than 1000° C., forsterite is insufficiently formed and the glass film 11 becomes thinner. Thus, although F1 satisfies expression (1), F2 does not satisfy the upper limit of expression (2). As a result, the tension of the glass film 11, which is required to refine the magnetic domains, is reduced. Thus, the magnetic loss deteriorates and the adhesion of the coating also deteriorates.

[0129]

(Holding time t1 at temperature T1 annealing at low temperature)

When the low temperature annealing temperature T1 is suitable, specifically 910-1000°C, and when the holding time t1 at the temperature T1 is less than 50 hours, forsterite is not sufficiently formed and the glass film 11 becomes thinner. Thus, although F1 satisfies expression (1), F2 does not satisfy the upper limit of expression (2). As a result, the insulation deteriorates.

[0130]

When the low temperature annealing temperature T1 is suitable, and when the holding time t1 is more than 120 hours, forsterite is generated in an excessive amount, and Mg is consumed in forming forsterite. In this case, there is not enough Mg to form the spinel (MgAl ₂ O ₄ ), and the spinel is formed insufficiently. Thus, although F2 satisfies expression (2), F1 does not satisfy the upper limit of expression (1).

[0131]

Considering that the low temperature annealing temperature T1 is appropriate, the holding time t1 at the temperature T1 should be 50-120 hours.

[0132]

When the low temperature annealing temperature T1 is 910-1000°C, and when the holding time t1 at the temperature T1 is 50-120 hours, forsterite is formed and grows sufficiently, and the glass film 11 thickens sufficiently. As a result, if the conditions explained below are satisfied in the elevated temperature annealing step (S62), the spinel is localized near the interface with the base steel sheet 10 in the glass film 11, F1 satisfies expression (1), and F2 satisfies expression (2).

[0133]

Here, in the low temperature annealing step (S61), it is sufficient to hold the steel sheet for a holding time t1 in a temperature range of 910-1000°C. In other words, if the holding time t1 in the temperature range of 910-1000°C is 50-120 hours, the temperature during the holding time t1 may be constant, may increase, or may decrease.

[0134]

(Step (S62) annealing at elevated temperature)

The high temperature annealing step (S62) is to form a spinel in the glass film 11 that is formed in the low temperature annealing step (S61) and localize the spinel near the interface with the base steel sheet 10. Specifically, after the annealing step (S61) is carried out at the lower temperature, the steel sheet is further heated to the elevated temperature annealing temperature T2. The heating rate is not particularly limited. The steel sheet is held at the temperature T2 for the holding time t2, which is explained below. The elevated temperature annealing step may be carried out in the same heat treatment furnace as the low temperature annealing step or in a different heat treatment furnace. The atmosphere in the furnace during the elevated temperature annealing step may be a nitrogen atmosphere.

[0135]

The elevated temperature annealing temperature T2 (°C) and the holding time t2 at the temperature T2 are as follows.

Temperature T2 annealing at elevated temperature: 1100-1300°C

Holding time t2 at temperature T2: 20-80 hours

[0136]

(Elevated temperature annealing temperature T2)

1100-1300°C is the temperature range in which the spinel is formed. The glass film 11 is sufficiently formed by the low temperature annealing step. Thus, when the steel sheet is kept in the temperature range of 1100-1300°C during the elevated temperature annealing step, Al contained in the base steel sheet 10 dissipates near the interface between the glass film 11 and the base steel sheet 10 and reacts with forsterite. As a result, spinel is formed. The spinel is formed near the border with the base steel sheet 10 in the glass film 11 during the elevated temperature annealing step, and thus the spinel is localized near this border.

[0137]

When the elevated temperature annealing temperature T2 is less than 1100° C., the spinel is insufficiently formed. In this case, although F2 satisfies expression (2), F1 does not satisfy the upper limit of expression (1).

[0138]

When the elevated temperature annealing temperature T2 exceeds 1300° C., excessive spinel is formed. In this case, although F2 satisfies expression (2), F1 does not satisfy the lower limit of expression (1).

[0139]

Thus, the elevated temperature annealing temperature T2 should be 1100-1300°C.

[0140]

(Holding time t2 at 1100-1300°C)

When the holding time t2 at 1100-1300°C is less than 20 hours, the spinel is not sufficiently formed. In this case, although F2 satisfies expression (2), F1 does not satisfy the upper limit of expression (1).

[0141]

When the holding time t2 at 1100-1300°C is more than 80 hours, excessive spinel is formed. In this case, although F2 satisfies expression (2), F1 does not satisfy the lower limit of expression (1).

[0142]

Thus, the holding time t2 at a temperature of 1100-1300°C should be 20-80 hours.

[0143]

When the elevated temperature annealing temperature T2 is 1100-1300°C, and when the holding time t2 at the temperature T2 is 20-80 hours, the spinel sufficiently grows near the boundary with the base steel sheet 10 in the glass film 11, and thus the spinel is localized around this border. Thus, F1 satisfies expression (1) and F2 satisfies expression (2).

[0144]

Here, in the elevated temperature annealing step (S62), the steel sheet may be held for a holding time t2 at a temperature T2 that is constant, or may be held for a holding time t2 in a temperature range of 1100-1300°C. If the holding time t2 in the temperature range 1100-1300°C is 20-80 hours, the temperature during the holding time t2 may be constant, may increase or may decrease.

[0145]

Preferably, the cleaning annealing step is performed after the elevated temperature annealing step (S62) and before the insulating coating forming process (S7). By performing the cleaning annealing step, the magnetic characteristics are further improved. In the hydrogen atmosphere cleaning annealing step, the annealing temperature may be 1000-1300°C, and the holding time may be 10 hours or more. When the cleaning annealing step is performed, each element of the chemical composition of the base steel sheet 10 is removed from the steel composition to some extent. In particular, residual elements such as S, Al and N, which affect the magnetic loss, are removed to a large extent.

[0146]

(Process (S7) of forming an insulating coating)

In the production method of the grain-oriented electrical steel sheet 1 according to the embodiment, the insulating coating forming process (S7) is carried out after the final annealing process (S6). In the insulating coating forming process (S7), an insulating coating solution that mainly includes colloidal silica and phosphate is applied to the surface (glass film 11) of the grain-oriented electrical steel sheet 1 after cooling in the final annealing process (S6), and baked. As a result, an insulating coating with a tension of 12 is formed on the glass film.

[0147]

The tension insulating coating 12 formed on the surface of the steel sheet is not particularly limited as long as it functions as a tension insulating coating on the grain oriented electrical steel sheet 1 . A known tensioned insulating coating may be used. For example, the tensile insulation coating may be a composite insulation coating that includes primarily inorganic materials and further includes organic materials. For example, the composite insulation coating may be an insulation coating that mainly includes at least one of inorganic substances such as metal chromate, metal phosphate, colloidal silica, a Zr compound, and a Ti compound, and includes dispersed fine organic polymer particles. In particular, the tensile insulation coating may use a metal phosphate, a Zr-based binder, a Ti-based binder, or their carbonate or ammonium salts. In addition, the flattening annealing to correct the shape of the sheet can be carried out after the process (S7) of forming the insulating coating. By performing the leveling annealing of the steel sheet, the magnetic loss can be further improved.

[0148]

In the grain-oriented electrical steel sheet 1 which is produced by the above processes, F1 satisfies the expression (1), F2 satisfies the expression (2), and the spinel is localized near the boundary with the base steel sheet 10 in the glass film 11. As a result, the adhesion of the glass film 11 to the base steel sheet 10 is improved.

[0149]

In particular, in order to produce the grain-oriented electrical steel sheet 1 according to the embodiment, it is important that the above-described production method satisfies the following conditions. The Al content of the slab should be 0.01 mass% or more in the hot rolling process (S1), the oxidation state (PH ₂ O/PH ₂ ) should be 0.1 or less in the heating step (S41) of the decarburization process (S4). annealing, and the annealing conditions must be controlled in the low temperature annealing step (S61) and the high temperature annealing step (S62) of the final annealing process (S6).

[0150]

(Other production processes)

In the grain-oriented electrical steel sheet 1 according to the embodiment, the nitriding process may be performed after the decarburization annealing process (S4) and before the annealing separator deposition process (S5). In the nitriding process, the steel sheet after the decarburization annealing process (S4) is subjected to a nitriding treatment to obtain a nitrided steel sheet. The nitriding treatment can be carried out under known conditions. For example, preferred conditions for nitriding treatment are as follows.

[0151]

Nitriding temperature: 700-850°C

Atmosphere in a nitriding treatment furnace (nitriding atmosphere): an atmosphere including a gas with nitriding capability such as hydrogen, nitrogen, and ammonia.

[0152]

When the nitriding temperature is 700° C. or more, or when the nitriding temperature is 850° C. or less, nitrogen tends to infiltrate the steel sheet during nitriding. In this case, the amount of nitrogen in the steel sheet becomes sufficient in the nitriding process. Thus, thin AlN is sufficiently obtained just before the secondary recrystallization. As a result, secondary recrystallization preferably occurs during the final annealing process (S6). The holding time at the nitriding temperature during the nitriding process is not particularly limited, and may be 10 to 60 seconds.

[0153]

(Magnetic domain grinding process)

In the grain-oriented electrical steel sheet 1 according to the embodiment, the magnetic domain refining process can be performed as needed after the final annealing process (S6) or the insulating coating forming process (S7). In the magnetic domain grinding process, laser irradiation is performed or grooves are formed on the surface of the grain-oriented electrical steel sheet 1 . In this case, it is possible to produce a grain-oriented electrical steel sheet 1 which has further improved magnetic characteristics.

Examples

[0154]

Next, the effects of one aspect of the present invention are described in detail with reference to the following examples. However, the conditions in the examples are exemplary conditions used to confirm the operation and effects of the present invention, so the present invention is not limited to these exemplary conditions. The present invention may use various types of conditions, as long as these conditions do not deviate from the scope of the present invention and allow the object of the present invention to be achieved.

[0155]

(Production of grain oriented electrical steel sheet of each test)

A slab was produced, including in its chemical composition, in wt.%, 0.03-0.10% C; 3.0-3.5% Si; 0.2-0.3% soluble Al; 0.02-0.90% Mn; 0.005-0.03% N; 0.005-0.03S; 0.005-0.03% P; as well as the remainder of Fe and impurities.

[0156]

This slab was subjected to a hot rolling process. Specifically, the slab was heated to 1350°C, hot-rolled, and thereby a hot-rolled steel sheet with a thickness of 2.3 mm was produced. The hot rolled steel sheet after the hot rolling process was subjected to a hot rolled steel sheet annealing process under such conditions that the annealing temperature was 900-1200°C and the holding time was 10-300 seconds. Thereafter, a cold rolling process was carried out, and as a result, a cold-rolled steel sheet (base steel sheet) with a thickness of 0.19-0.23 mm was obtained.

[0157]

This cold rolled steel sheet was subjected to a decarburization annealing process. In the decarburization annealing process, the decarburization annealing temperature Ta was 800-950°C, and the holding time at the decarburization annealing temperature Ta was 100 s. After the decarburization annealing process, an annealing separator which mainly included magnesium oxide (MgO) and which included a Ti compound was applied as needed to the surface of the steel sheet, and then a final annealing process was performed.

[0158]

An insulating coating solution, which mainly included colloidal silica and phosphate, was deposited on a surface (glass film) of a grain-oriented electrical steel sheet after cooling in a final annealing process, and baked. By the above processes, a grain oriented electrical steel sheet of each test was produced.

[0159]

Production conditions and production results are shown in Tables 1-6. In these tables, "-" in the chemical composition means that this element was not used, the control of this element was not carried out, and thus its content was not measured. In addition, "-" in the production conditions and evaluation results means that no control or evaluation was carried out.

[0160]

As shown in Tables 4-6, Test Nos. 1-56, 58, 59, and 63-66 were subjected to both a low temperature annealing step and an elevated temperature annealing step in the final annealing process. On the other hand, Test Nos. 57 and 60-62 were not subjected to a low temperature annealing step, although an elevated temperature annealing step was carried out.

[0161]

In addition, as shown in Tables 4 to 6, in Tests Nos. 1 to 59 and 61 to 66, the cold rolled steel sheet was heated in a controlled manner in the heating step of the decarburization annealing process. On the other hand, in Test No. 60, the heating step (S41) of the decarburization annealing process was not performed (heating conditions of the cold-rolled steel sheet were not controlled). Specifically, in this test, the cold-rolled steel sheet was placed in a heat treatment furnace for the decarburization step (S42) and heated to the decarburization annealing temperature Ta.

[0162]

In addition, although not shown in the tables, in Test Nos. 1 to 62, 65, and 66, the Al content of the slab was 0.01 mass% or more. On the other hand, in Test Nos. 63 and 64, the Al content of the slab was less than 0.01 mass%.

[0163]

The grain-oriented electrical steel sheet that was produced by the above-described production method was evaluated as follows.

[0164]

(Analysis of the chemical composition of the base steel sheet with glass film after removing the insulating coating under tension from the grain oriented electrical steel sheet)

For each test of the grain-oriented electrical steel sheet, the chemical composition of the base steel sheet with glass film after stripping the insulating coating under tension (average chemical composition of the base steel sheet and glass film) was analyzed in the following way.

[0165]

First, the insulating coating was tension-removed from the grain-oriented electrical steel sheet by the method explained above. Specifically, a grain-oriented electrical steel sheet was immersed in an aqueous sodium hydroxide solution that included 30-50 wt% NaOH and 50-70 wt% H ₂ O at a temperature of 80-90°C for 7-10 minutes. The steel sheet after dipping (basic steel sheet with glass film after removing the insulating coating under tension) was washed with water. The steel sheet after washing was dried by blowing warm air for less than about 1 minute. By the above-described processing, the tension-insulating coating was removed, and a base steel sheet with a glass film was obtained.

[0166]

The known compositional analysis method was performed on a base steel sheet with a glass film after the insulating coating was removed under tension. Specifically, the base steel sheet with the glass film was drilled with a drill and the resulting chips were collected. These shavings were dissolved in acid, resulting in a solution. Using this solution, elemental analysis of the chemical composition was performed using ICP-AES.

[0167]

Si in the chemical composition of the glass film base steel sheet was analyzed by the method (silicon quantification method) defined in JIS G1212 (1997). In particular, when the above chips were dissolved in acid, silicon oxide precipitated out. This precipitate (silica) was filtered with filter paper and its mass was measured in order to determine the Si content.

[0168]

The content of C and S was analyzed using a known method of combustion (measurement of absorption in the infrared region of the spectrum after combustion). Specifically, the aforementioned solution was combusted by high-frequency induction heating in an oxygen flow, and the carbon dioxide and sulfur dioxide produced were determined in order to determine the C content and the S content.

[0169]

The N content was analyzed using a known thermoconductometric method after melting in an inert gas flow. The O content was analyzed using the known method of non-dispersive absorption in the infrared region of the spectrum after melting in an inert gas flow.

[0170]

The chemical composition of the base steel sheet with glass film (average chemical composition of the base steel sheet and the glass film) which was measured by the above analytical methods is shown in Tables 1-3.

[0171]

(F1 value measurement)

From the central region of the grain oriented electrical steel sheet of each test in the transverse direction TD, a sample was taken, the size of which was 30 mm in the rolling direction RD, 40 mm in the transverse direction TD, and the thickness was equal to that of the grain oriented electrical steel sheet. The insulating coating was removed under tension from the above sample. Specifically, a grain-oriented electrical steel sheet was immersed in an aqueous sodium hydroxide solution that included 30-50 wt% NaOH and 50-70 wt% H ₂ O at a temperature of 80-90°C for 7-10 minutes. The steel sheet was washed with water after immersion. The steel sheet after washing was dried by blowing warm air for less than about 1 minute. With the above processing, a sample was obtained with a base steel sheet and a glass film, and without a tension insulating coating.

[0172]

Glow discharge emission spectroscopy was carried out from the sample glass film surface in the depth direction, and the GDS spectra of Al, Si, and Fe were measured. In particular, using a high-frequency glow-discharge emission spectroscope (GD-ODS, GDA750 manufactured by Rigaku), the GDS spectra of Al, Si, and Fe in the depth direction on a glass film were measured under the condition of supplying 30 W of electricity to the sample as a cathode in the atmosphere. argon (pressure Ar: 3 hPa). The measurement area was 4 mm φ, the measurement time was 100 s, and the measurement interval was 0.02 s.

[0173]

The resulting GDS spectrum was smoothed by a simple moving average method.

[0174]

From the obtained GDS spectrum of Al, the time T ^Al _p and the value of F(T ^Al _p ) were measured. Similarly, the time T ^Si _p was measured from the obtained GDS spectrum of Si, and the value F(T ^Si _p ) representing the emission intensity of Al at time T ^Si _p was measured from the GDS spectrum of Al. The analysis started at time Ts. Using the time Ts, the values of T ^Al _p , F(T ^Al _p ), T ^Si _p , F(T ^Si _p ), F1 and F2 were obtained. The resulting F1 and F2 values are shown in Tables 4-6.

[0175]

Although not shown in the table, the time T ^Fe ₆₀ and the time T ^Fe ₉₀ were measured from the obtained GDS spectrum of Fe.

[0176]

(Measurement of magnetic flux density B8 and magnetic losses W _17/50 )

Near the center region of each test sheet of grain-oriented electrical steel in the transverse direction, a sample was taken, the size of which was 60 mm in width and 300 mm in length. The sample length was parallel to the rolling direction. Using the sample taken, the magnetic flux density B8 was measured based on the Single Sheet Tester (SST) method of JIS C 2556 (2011). In particular, the magnetic flux density (T) was measured when the sample was excited with a magnetizing force of 800 A/m. The measurement results are shown in Tables 4-6. When the magnetic flux density B8 was 1.90 T or more, it was considered acceptable.

[0177]

In addition, using this sample, the magnetic loss W _17/50 (W/kg) was measured under the condition of an AC frequency of 50 Hz and a maximum magnetic flux density of 1.7 T based on JIS C 2556 (2011). The measurement results are shown in Tables 4-6. When the magnetic loss W _17/50 was less than 0.85 W/kg, this was considered acceptable.

[0178]

(Glass Film Adhesion Evaluation)

From the central region of the grain-oriented electrical steel sheet of each test in the transverse direction, a sample was taken, the size of which was 80 mm in the rolling direction and 30 mm in the transverse direction. The sample taken was bent around a cylinder with a diameter of 20 mm by 180°. After that, the bent sample returned to its original flat state. After returning to the original flat state, the total area of the undelaminated glass film was measured. Using the measured total area of the glass film, the proportion of the remaining glass film (area %) was obtained using the following expression.

Fraction of glass film remaining (area %)=Total area of undelaminated glass film/Total sample area × 100

Here, the total sample area was 80 mm × 30 mm.

[0179]

Based on the area fraction of the remaining glass film, the adhesion of the glass film was evaluated as follows.

Very good: the area ratio of the remaining glass film was 90% or more.

Good: The area ratio of the remaining glass film was 85% or more and less than 90%.

Satisfactory: The area ratio of the remaining glass film was 80% or more and less than 85%.

Poor: Less than 80% area of remaining glass film.

The evaluation results are shown in Tables 4-6. When the area ratio of the remaining glass film was very good, good and satisfactory, it was considered acceptable.

[0180]

In those tests where the B8 magnetic flux density was less than 1.90 T or the magnetic loss W _17/50 was 0.85 W/kg or more, the magnetic performance was judged to be unacceptable, and the glass film adhesion was not evaluated.

[0181]

(Evaluation results)

As shown in Tables 1-6, in Tests Nos. 1-50, the average chemical composition was suitable, and the production conditions were also suitable. As a result, the magnetic characteristics and adhesion of the glass film were excellent. In addition, although not shown in the tables, in tests Nos. 1-50, the GDS spectrum satisfies the conditions T ^Fe ₆₀ ≤ T ^Al _p ≤ T ^Fe ₉₀ (T ^Si _p ≤ T ^Al _p ≤ T ^Fe ₉₀ ).

[0182]

Among tests Nos. 1-50, the F1 value of tests Nos. 18-25 and 39-50 was lower than that of tests Nos. 1-17 and 26-38, and was in the range of 0.05-0.30. As a result, the adhesion score of the glass film in Tests Nos. 18-25 and 39-50 was good or very good, and was better than the score (Fair) in Tests Nos. 1-17 and 26-38.

[0183]

Among tests Nos. 18-25 and 39-50, the F1 value of tests Nos. 22-25 and 44-50 was in the range of 0.05-0.12, and the F1 value of tests Nos. 18-21 and 39-43 was in the range 0.13-0.30. As a result, the glass film adhesion score in Tests Nos. 22-25 and 44-50 was very good, and was better than the (good) score in Tests Nos. 18-21 and 39-43.

[0184]

On the other hand, in Test Nos. 51-66, at least one of the average chemical composition and production conditions was not preferred. As a result, the magnetic characteristics and/or adhesion of the glass film were not satisfactory.

[0185]

In test No. 51, the holding time t1 at temperature T1 (T1=910-1000°C) for low temperature annealing was excessively short in the low temperature annealing step of the final annealing process. Thus, although the value of F1 satisfied the expression (1), the value of F2 did not satisfy the upper limit of the expression (2). As a result, the magnetic loss W _17/50 was 0.85 W/kg or more, and thus the magnetic performance was not satisfactory.

[0186]

In Test No. 52, the holding time t1 at temperature T1 (T1=910-1000°C) for low temperature annealing was excessively long in the low temperature annealing step of the final annealing process. Thus, although the value of F2 satisfied the expression (2), the value of F1 did not satisfy the upper limit of the expression (1). As a result, the adhesion of the glass film was poor, i. the adhesion of the glass film to the base steel sheet was insufficient.

[0187]

In Test No. 53, the high temperature annealing temperature T2 was excessively low in the high temperature annealing step of the final annealing process. Thus, although the value of F2 satisfied the expression (2), the value of F1 did not satisfy the upper limit of the expression (1). As a result, the adhesion of the glass film was poor, i. the adhesion of the glass film to the base steel sheet was insufficient.

[0188]

In Test No. 54, the elevated temperature annealing temperature T2 was excessively high in the elevated temperature annealing step of the final annealing process. Thus, the value of F1 did not satisfy the lower limit of expression (1). As a result, the magnetic loss W _17/50 was 0.85 W/kg or more, and thus the magnetic performance was not satisfactory.

[0189]

In Test No. 55, the holding time t2 at temperature T2 (T2=1100-1300°C) for annealing at elevated temperature was excessively short. Thus, the value of F1 did not satisfy the upper limit of expression (1). As a result, the adhesion of the glass film was poor, i. the adhesion of the glass film to the base steel sheet was insufficient.

[0190]

In test No. 56, the holding time t2 at temperature T2 (T2=1100-1300°C) for annealing at elevated temperature was excessively long. Thus, the value of F1 did not satisfy the lower limit of expression (1). As a result, the magnetic loss W _17/50 was 0.85 W/kg or more, and thus the magnetic performance was not satisfactory.

[0191]

In test no. 57, the annealing step at a reduced temperature was not carried out. Thus, although the value of F1 satisfied the expression (1), the value of F2 did not satisfy the upper limit of the expression (2). As a result, the magnetic loss W _17/50 was 0.85 W/kg or more, and thus the magnetic performance was not satisfactory.

[0192]

In Test No. 58, the low temperature annealing temperature T1 was excessively low in the low temperature annealing step. Thus, the value of F1 did not satisfy the upper limit of expression (1), and the value of F2 did not satisfy the lower limit of expression (2). As a result, the magnetic flux density B8 was less than 1.90 T, the magnetic loss W _17/50 was 0.85 W/kg or more, and thus the magnetic performance was unsatisfactory.

[0193]

In Test No. 59, the low temperature annealing temperature T1 was excessively high in the low temperature annealing step. Thus, although the value of F1 satisfied the expression (1), the value of F2 did not satisfy the upper limit of the expression (2). As a result, the magnetic loss W _17/50 was 0.85 W/kg or more, and thus the magnetic performance was not satisfactory.

[0194]

In Test No. 60, the heating step of the decarburization annealing process was not carried out (heating conditions of the cold-rolled steel sheet were not controlled). As a result, the magnetic loss W _17/50 was 0.85 W/kg or more, and thus the magnetic performance was not satisfactory.

[0195]

In Test No. 61, the oxidation state (PH ₂ O/PH ₂ ) was greater than 0.1 in the heating step of the decarburization annealing process. As a result, the magnetic flux density B8 was less than 1.90 T, the magnetic loss W _17/50 was 0.85 W/kg or more, and thus the magnetic performance was unsatisfactory.

[0196]

In Test No. 62, the oxidation state (PH ₂ O/PH ₂ ) was greater than 0.1 in the heating step of the decarburization annealing process. As a result, the magnetic flux density B8 was less than 1.90 T, the magnetic loss W _17/50 was 0.85 W/kg or more, and thus the magnetic performance was unsatisfactory.

[0197]

In Test No. 63, the oxidation state (PH ₂ O/PH ₂ ) was greater than 0.1 in the heating step of the decarburization annealing process, the low temperature annealing temperature T1 was excessively low in the low temperature annealing step, and the holding time t2 was excessively short at the stage of annealing at elevated temperature. In addition, since the content of Al in the slab was less than 0.01 mass%, the content of insoluble Al was less than 0.005 mass% in the average chemical composition of the base steel sheet and the glass film in the grain-oriented electrical steel sheet. As a result, the magnetic flux density B8 was less than 1.90 T, the magnetic loss W _17/50 was 0.85 W/kg or more, and thus the magnetic performance was unsatisfactory.

[0198]

In Test No. 64, the oxidation state (PH ₂ O/PH ₂ ) was greater than 0.1 in the heating step of the decarburization annealing process, the low temperature annealing temperature T1 was excessively low in the low temperature annealing step, and the holding time t2 was excessively short at the stage of annealing at elevated temperature. In addition, since the content of Al in the slab was less than 0.01 mass%, the content of insoluble Al was less than 0.005 mass% in the average chemical composition of the base steel sheet and the glass film in the grain-oriented electrical steel sheet. As a result, the magnetic flux density B8 was less than 1.90 T, the magnetic loss W _17/50 was 0.85 W/kg or more, and thus the magnetic performance was unsatisfactory.

[0199]

In Test No. 65, the oxidation state (PH ₂ O/PH ₂ ) was greater than 0.1 in the heating step of the decarburization annealing process. As a result, the magnetic loss W _17/50 was 0.85 W/kg or more, and thus the magnetic performance was not satisfactory.

[0200]

In Test No. 66, the low temperature annealing temperature T1 was excessively low in the low temperature annealing step. As a result, the magnetic flux density B8 was less than 1.90 T, the magnetic loss W _17/50 was 0.85 W/kg or more, and thus the magnetic performance was unsatisfactory.

[0201]

[Table 1] No. TEST PRODUCTION RESULTS AVERAGE CHEMICAL COMPOSITION (in wt.%, WITH RESIDUE FROM Fe AND IMPURITIES) C Si Mn N soluble Al insoluble Al mg O Ti S P sn Cr Cu Bi Se Sb 1 0.008 3.3 0.02 0.008 0.002 0.012 0.07 0.09 - 0.007 0.013 - - - - - - 2 0.003 2.9 0.02 0.007 0.005 0.012 0.07 0.09 0.016 0.007 0.012 - - - - - - 3 0.002 3.9 0.02 0.007 0.003 0.011 0.10 0.16 0.017 0.007 0.010 - - - - - - 4 0.003 3.3 0.80 0.007 0.010 0.013 0.11 0.18 0.018 0.008 0.015 - - - - - - 5 0.002 3.3 0.80 0.008 0.006 0.006 0.11 0.16 0.018 0.008 0.013 - - - - - - 6 0.003 3.2 0.80 0.008 0.003 0.028 0.10 0.17 0.015 0.007 0.016 - - - - - - 7 0.001 3.2 0.75 0.009 0.006 0.014 0.12 0.18 0.016 0.007 0.018 - - - - - - 8 0.003 3.2 0.02 0.007 0.004 0.011 0.11 0.16 0.015 0.007 0.019 - - - - - - 9 0.002 3.2 0.90 0.007 0.006 0.022 0.10 0.18 0.017 0.008 0.017 - - - - - - 10 0.002 3.2 0.60 0.007 0.007 0.023 0.12 0.18 0.017 0.009 0.016 - - - - - - eleven 0.003 3.3 0.04 0.007 0.005 0.022 0.12 0.16 0.018 0.007 0.014 - - - - - - 12 0.001 3.3 0.40 0.007 0.005 0.022 0.11 0.16 0.017 0.007 0.017 - - - - - - 13 0.001 3.3 0.08 0.005 0.006 0.019 0.11 0.16 0.016 0.004 0.005 - - - - - - 14 0.002 3.3 0.05 0.003 0.005 0.019 0.10 0.17 0.015 0.004 0.005 - 0.40 - - - - 15 0.001 3.4 0.05 0.006 0.002 0.015 0.11 0.16 0.018 0.006 0.003 0.45 - - - - - 16 0.003 3.3 0.15 0.003 0.003 0.016 0.12 0.18 0.016 0.005 0.004 - - 0.02 - - - 17 0.003 3.2 0.15 0.006 0.002 0.015 0.11 0.18 0.016 0.006 0.007 - - - - - - 18 0.002 3.4 0.08 0.005 0.001 0.018 0.11 0.16 0.003 0.006 0.006 0.30 0.15 - - - - 19 0.002 3.5 0.05 0.003 0.003 0.015 0.12 0.17 0.003 0.004 0.008 0.10 0.05 0.07 0.0003 - - 20 0.001 3.5 0.08 0.004 0.004 0.015 0.11 0.17 0.004 0.004 0.005 0.05 0.10 - - - - 21 0.002 3.5 0.20 0.004 0.003 0.017 0.10 0.18 0.004 0.004 0.006 0.02 - 0.05 0.0080 - - 22 0.001 3.3 0.08 0.006 0.002 0.018 0.11 0.17 0.007 0.003 0.007 0.05 0.02 0.10 - - -

[0202]

[Table 2] No. TEST PRODUCTION RESULTS AVERAGE CHEMICAL COMPOSITION (in wt.%, WITH RESIDUE FROM Fe AND IMPURITIES) C Si Mn N soluble Al insoluble Al mg O Ti S P sn Cr Cu Bi Se Sb 23 0.001 3.5 0.20 0.005 0.005 0.017 0.10 0.17 0.006 0.004 0.005 0.02 0.02 0.02 - 0.005 0.05 24 0.002 3.5 0.30 0.004 0.003 0.017 0.11 0.16 0.007 0.004 0.008 0.02 0.01 0.50 - 0.005 0.05 25 0.001 3.5 0.30 0.005 0.005 0.017 0.10 0.19 0.005 0.004 0.007 0.02 0.01 0.10 0.0012 0.005 0.05 26 0.001 3.4 0.03 0.006 0.002 0.018 0.19 0.35 - 0.005 0.015 - - - - - - 27 0.002 3.0 0.03 0.006 0.002 0.015 0.18 0.26 0.019 0.006 0.014 - - - - - - 28 0.002 3.9 0.03 0.006 0.001 0.013 0.13 0.23 0.016 0.009 0.011 - - - - - - 29 0.002 3.3 0.75 0.008 0.003 0.005 0.14 0.19 0.018 0.009 0.015 - - - - - - thirty 0.002 3.2 0.74 0.007 0.002 0.008 0.14 0.18 0.017 0.009 0.018 - - - - - - 31 0.002 3.1 0.79 0.007 0.002 0.029 0.15 0.19 0.018 0.009 0.014 - - - - - - 32 0.002 3.3 0.76 0.008 0.002 0.013 0.13 0.19 0.018 0.008 0.013 - - - - - - 33 0.001 3.2 0.04 0.008 0.001 0.011 0.13 0.18 0.002 0.008 0.017 - - - - - - 34 0.002 3.3 0.88 0.008 0.001 0.025 0.12 0.16 0.001 0.009 0.015 - - - - - - 35 0.002 3.2 0.59 0.006 0.002 0.024 0.16 0.21 0.002 0.009 0.013 - - - - - - 36 0.001 3.2 0.03 0.007 0.002 0.024 0.11 0.22 0.002 0.008 0.015 - - - - - - 37 0.001 3.3 0.38 0.008 0.003 0.022 0.13 0.18 0.001 0.008 0.016 - - - - - - 38 0.001 3.2 0.09 0.006 0.003 0.022 0.12 0.22 0.001 0.006 0.006 - - - - - - 39 0.001 3.2 0.06 0.004 0.002 0.020 0.12 0.19 0.004 0.006 0.004 - 0.41 - - - - 40 0.001 3.4 0.06 0.005 0.002 0.016 0.12 0.18 0.004 0.007 0.004 0.43 - - - - - 41 0.001 3.2 0.16 0.005 0.002 0.016 0.11 0.16 0.011 0.007 0.004 - - 0.01 - - - 42 0.002 3.2 0.17 0.006 0.002 0.016 0.15 0.19 0.013 0.007 0.006 - - - - - - 43 0.002 3.3 0.09 0.006 0.002 0.016 0.15 0.18 0.013 0.007 0.006 0.28 0.17 - - - - 44 0.002 3.4 0.06 0.004 0.003 0.016 0.11 0.22 0.005 0.006 0.006 0.09 0.06 0.05 0.0002 - -

[0203]

[Table 3] TEST
No. PRODUCTION RESULTS AVERAGE CHEMICAL COMPOSITION (in wt.%, WITH RESIDUE FROM Fe AND IMPURITIES) C Si Mn N soluble Al insoluble Al mg O Ti S P sn Cr Cu Bi Se Sb 45 0.001 3.5 0.07 0.003 0.001 0.018 0.13 0.19 0.006 0.006 0.005 0.06 0.09 - - - - 46 0.001 3.4 0.22 0.003 0.002 0.018 0.10 0.18 0.006 0.007 0.006 0.03 - 0.05 0.0050 - - 47 0.001 3.2 0.09 0.005 0.002 0.017 0.12 0.22 0.005 0.005 0.005 0.06 0.01 0.08 - - - 48 0.001 3.2 0.21 0.007 0.002 0.018 0.13 0.21 0.007 0.005 0.006 0.01 0.01 0.01 - 0.003 0.07 49 0.002 3.3 0.28 0.003 0.001 0.016 0.12 0.19 0.008 0.006 0.006 0.01 0.03 0.45 - 0.003 0.07 50 0.001 3.4 0.28 0.003 0.002 0.018 0.13 0.20 0.008 0.004 0.008 0.01 0.02 0.08 0.0011 0.003 0.05 51 0.008 3.3 0.02 0.008 0.002 0.012 0.09 0.15 0.005 0.007 0.013 - - - - - - 52 0.003 2.9 0.02 0.007 0.005 0.012 0.13 0.21 0.006 0.007 0.012 - - - - - - 53 0.003 2.9 0.02 0.007 0.005 0.012 0.11 0.18 0.006 0.007 0.012 - - - - - - 54 0.008 3.3 0.02 0.008 0.002 0.012 0.12 0.16 0.005 0.007 0.013 - - - - - - 55 0.003 2.9 0.02 0.007 0.005 0.012 0.13 0.23 0.007 0.007 0.012 - - - - - - 56 0.008 3.3 0.02 0.008 0.002 0.012 0.12 0.20 0.005 0.007 0.013 - - - - - - 57 0.003 2.9 0.02 0.007 0.005 0.012 0.08 0.15 0.006 0.007 0.012 - - - - - - 58 0.008 3.3 0.02 0.008 0.002 0.012 0.09 0.16 0.008 0.007 0.013 - - - - - - 59 0.003 2.9 0.02 0.007 0.005 0.012 0.08 0.14 0.008 0.007 0.012 - - - - - - 60 0.001 3.3 0.08 0.005 0.002 0.010 0.10 0.13 0.006 0.005 0.010 0.10 - 0.08 - - - 61 0.001 3.3 0.08 0.005 0.002 0.009 0.10 0.14 0.005 0.005 0.010 0.10 - 0.08 - - - 62 0.001 3.3 0.08 0.005 0.002 0.009 0.09 0.13 0.007 0.005 0.010 0.10 - 0.08 - - - 63 0.001 3.2 0.07 0.0005 0.0001 0.004 0.11 0.01 0.009 0.0004 0.030 0.03 0.05 - - 0.0001 0.02 64 0.001 3.2 0.05 0.0004 0.0002 0.003 0.11 0.01 0.008 0.0005 0.010 0.01 0.01 - - 0.0002 0.01 65 0.008 3.3 0.02 0.008 0.002 0.012 0.08 0.15 0.007 0.007 0.013 - - - - - - 66 0.008 3.3 0.02 0.008 0.002 0.012 0.08 0.12 0.008 0.007 0.013 - - - - - -

[0204]

[Table 4] No. TEST PRODUCTION CONDITIONS PRODUCTION RESULTS ASSESSMENT RESULTS NOTE THICKNESS AFTER COLD ROLLING,
mm HEATING STAGE OF DECARBONIZING ANNEALING ANNEALING STAGE AT LOW TEMPERATURE ANNEALING STAGE AT HIGH TEMPERATURE F1 F2 MAGNETIC CHARACTERISTICS COATING ADHESION HEATING RATE, °C/s REACHABLE TEMPERATURE,
°C PH20/PH2,
- TEMPERATURE T1,
°C HOLDING TIME t1,
hour TEMPERATURE T2,
°C HOLDING TIME t2,
hour MAGNETIC FLUX B8,
Tl MAGNETIC LOSS W17/50,
W/kg 1 0.22 600 750 0.05 930 60 1100 20 0.48 2.4 1.92 0.75 Satisfactory INVENTION EXAMPLE 2 0.22 600 750 0.05 930 60 1100 20 0.47 2.3 1.94 0.78 Satisfactory INVENTION EXAMPLE 3 0.22 1000 850 0.05 950 60 1100 20 0.47 2.1 1.91 0.73 Satisfactory INVENTION EXAMPLE 4 0.22 1000 850 0.05 950 60 1100 20 0.45 2.3 1.92 0.78 Satisfactory INVENTION EXAMPLE 5 0.22 1000 900 0.05 950 60 1100 20 0.46 4.1 1.91 0.78 Satisfactory INVENTION EXAMPLE 6 0.22 1300 900 0.05 950 80 1100 thirty 0.35 2.1 1.92 0.77 Satisfactory INVENTION EXAMPLE 7 0.22 1300 820 0.05 950 80 1100 thirty 0.42 4.8 1.93 0.73 Satisfactory INVENTION EXAMPLE 8 0.22 500 820 0.05 950 80 1100 thirty 0.38 2.2 1.93 0.73 Satisfactory INVENTION EXAMPLE 9 0.22 500 820 0.05 970 80 1250 thirty 0.39 4.5 1.94 0.72 Satisfactory INVENTION EXAMPLE 10 0.22 1500 950 0.05 970 80 1250 thirty 0.41 4.9 1.92 0.73 Satisfactory INVENTION EXAMPLE eleven 0.22 1500 950 0.05 970 80 1250 thirty 0.38 2.1 1.93 0.76 Satisfactory INVENTION EXAMPLE 12 0.22 1000 950 0.05 970 85 1250 60 0.48 2.2 1.95 0.71 Satisfactory INVENTION EXAMPLE 13 0.22 1800 1000 0.05 970 85 1250 60 0.36 2.3 1.93 0.73 Satisfactory INVENTION EXAMPLE 14 0.22 1800 1000 0.05 970 85 1250 60 0.33 2.4 1.94 0.72 Satisfactory INVENTION EXAMPLE 15 0.22 1000 950 0.05 970 85 1290 60 0.38 2.3 1.92 0.78 Satisfactory INVENTION EXAMPLE 16 0.22 1000 930 0.05 970 85 1290 60 0.41 2.3 1.93 0.75 Satisfactory INVENTION EXAMPLE 17 0.22 400 930 0.05 970 85 1290 60 0.47 2.3 1.93 0.72 Satisfactory INVENTION EXAMPLE 18 0.22 400 830 0.02 990 90 1290 80 0.29 3.4 1.93 0.72 Good INVENTION EXAMPLE 19 0.22 1000 750 0.02 990 90 1290 80 0.28 3.3 1.95 0.70 Good INVENTION EXAMPLE 20 0.22 1000 780 0.02 990 90 1290 80 0.28 3.4 1.92 0.78 Good INVENTION EXAMPLE 21 0.22 200 700 0.02 990 100 1290 80 0.15 3.5 1.92 0.79 Good INVENTION EXAMPLE 22 0.22 200 700 0.01 990 100 1290 80 0.08 4.2 1.91 0.81 Very good INVENTION EXAMPLE

[0205]

[Table 5] No. TEST PRODUCTION CONDITIONS PRODUCTION RESULTS ASSESSMENT RESULTS NOTE THICKNESS AFTER COLD ROLLING,
mm HEATING STAGE OF DECARBONIZING ANNEALING ANNEALING STAGE AT LOW TEMPERATURE ANNEALING STAGE AT HIGH TEMPERATURE F1 F2 MAGNETIC CHARACTERISTICS COATING ADHESION HEATING RATE, °C/s REACHABLE TEMPERATURE,
°C PH20/PH2,
- TEMPERATURE T1,
°C HOLDING TIME t1,
hour TEMPERATURE T2,
°C HOLDING TIME t2,
hour MAGNETIC FLUX B8,
Tl MAGNETIC LOSS W17/50,
W/kg 23 0.22 200 700 0.01 990 100 1290 80 0.06 4.1 1.95 0.71 Very good INVENTION EXAMPLE 24 0.22 500 990 0.01 990 100 1290 80 0.08 4.0 1.95 0.72 Very good INVENTION EXAMPLE 25 0.22 500 990 0.01 990 100 1290 80 0.09 2.1 1.96 0.70 Very good INVENTION EXAMPLE 26 0.19 800 850 0.08 930 60 1100 20 0.42 2.4 1.91 0.72 Satisfactory INVENTION EXAMPLE 27 0.19 800 850 0.08 930 60 1100 20 0.28 2.8 1.95 0.66 Satisfactory INVENTION EXAMPLE 28 0.19 1000 850 0.08 950 60 1100 20 0.28 2.7 1.94 0.67 Satisfactory INVENTION EXAMPLE 29 0.19 1000 800 0.08 950 60 1100 20 0.33 2.7 1.92 0.69 Satisfactory INVENTION EXAMPLE thirty 0.19 1500 950 0.05 950 60 1100 20 0.45 2.6 1.93 0.69 Satisfactory INVENTION EXAMPLE 31 0.19 1500 950 0.05 950 80 1100 thirty 0.38 2.8 1.95 0.66 Satisfactory INVENTION EXAMPLE 32 0.19 1600 950 0.05 950 80 1100 thirty 0.47 2.9 1.92 0.71 Satisfactory INVENTION EXAMPLE 33 0.19 1600 950 0.09 950 80 1100 thirty 0.32 2.1 1.91 0.73 Satisfactory INVENTION EXAMPLE 34 0.19 1200 820 0.09 970 80 1250 thirty 0.42 2.2 1.92 0.72 Satisfactory INVENTION EXAMPLE 35 0.19 1200 820 0.09 970 80 1250 thirty 0.40 2.3 1.93 0.71 Satisfactory INVENTION EXAMPLE 36 0.19 100 780 0.09 970 80 1250 thirty 0.45 2.4 1.93 0.74 Satisfactory INVENTION EXAMPLE 37 0.19 100 780 0.09 970 85 1250 60 0.36 2.9 1.92 0.73 Satisfactory INVENTION EXAMPLE 38 0.19 100 780 0.09 970 85 1250 60 0.32 2.7 1.91 0.74 Satisfactory INVENTION EXAMPLE 39 0.19 400 820 0.05 970 85 1250 60 0.28 3.4 1.91 0.75 Good INVENTION EXAMPLE 40 0.19 400 820 0.05 970 85 1290 60 0.27 3.4 1.93 0.69 Good INVENTION EXAMPLE 41 0.19 400 820 0.05 970 85 1290 60 0.25 3.3 1.93 0.71 Good INVENTION EXAMPLE 42 0.19 700 820 0.05 970 85 1290 60 0.15 3.6 1.95 0.68 Good INVENTION EXAMPLE 43 0.19 700 820 0.05 990 90 1290 80 0.14 3.6 1.95 0.67 Good INVENTION EXAMPLE 44 0.19 700 820 0.01 990 90 1290 80 0.10 4.1 1.96 0.66 Very good INVENTION EXAMPLE

[0206]

[Table 6] TEST
No. PRODUCTION CONDITIONS PRODUCTION RESULTS ASSESSMENT RESULTS NOTE THICKNESS AFTER COLD ROLLING,
mm HEATING STAGE OF DECARBONIZING ANNEALING ANNEALING STAGE AT LOW TEMPERATURE ANNEALING STAGE AT HIGH TEMPERATURE F1 F2 MAGNETIC CHARACTERISTICS COATING ADHESION HEATING RATE, °C/s REACHABLE TEMPERATURE,
°C PH20/PH2,
- TEMPERATURE T1,
°C HOLDING TIME t1,
hour TEMPERATURE T2,
°C HOLDING TIME t2,
hour MAGNETIC FLUX B8,
Tl MAGNETIC LOSS W17/50,
W/kg 45 0.19 1000 860 0.01 990 90 1290 80 0.08 3.8 1.93 0.68 Very good INVENTION EXAMPLE 46 0.19 1000 860 0.01 990 100 1290 80 0.09 3.8 1.92 0.68 Very good INVENTION EXAMPLE 47 0.19 1000 860 0.01 990 100 1290 80 0.07 3.9 1.94 0.68 Very good INVENTION EXAMPLE 48 0.19 1000 860 0.01 990 100 1290 80 0.06 4.2 1.95 0.66 Very good INVENTION EXAMPLE 49 0.19 1000 860 0.01 990 100 1290 80 0.05 3.7 1.94 0.66 Very good INVENTION EXAMPLE 50 0.19 1000 860 0.01 990 100 1290 80 0.06 3.5 1.96 0.65 Very good INVENTION EXAMPLE 51 0.22 1500 860 0.05 950 40 1200 40 0.08 5.5 1.92 0.95 - COMPARATIVE EXAMPLE 52 0.22 1500 770 0.05 950 150 1200 40 0.73 2.3 1.91 0.72 bad COMPARATIVE EXAMPLE 53 0.22 1500 770 0.05 950 80 1000 40 0.65 4.1 1.90 0.74 bad COMPARATIVE EXAMPLE 54 0.22 1500 770 0.05 950 80 1320 40 0.02 3.3 1.91 0.98 - COMPARATIVE EXAMPLE 55 0.22 800 800 0.08 950 90 1200 10 0.59 2.8 1.90 0.75 bad COMPARATIVE EXAMPLE 56 0.22 800 800 0.08 950 90 1200 90 0.04 3.5 1.90 0.94 - COMPARATIVE EXAMPLE 57 0.22 800 800 0.08 - - 1200 40 0.15 5.6 1.91 0.86 - COMPARATIVE EXAMPLE 58 0.22 800 800 0.08 870 60 1200 60 0.55 1.3 1.65 1.25 - COMPARATIVE EXAMPLE 59 0.22 800 800 0.08 1020 60 1250 60 0.12 5.5 1.92 0.89 - COMPARATIVE EXAMPLE 60 0.22 - - - - - 1200 24 0.65 3.2 1.91 0.87 - COMPARATIVE EXAMPLE 61 0.22 480 850 0.2 - - 1200 24 0.62 3.3 1.89 0.87 - COMPARATIVE EXAMPLE 62 0.22 480 850 0.3 - - 1200 24 0.63 3.3 1.87 0.88 - COMPARATIVE EXAMPLE 63 0.23 20 840 0.3 900 50 1200 10 0.95 3.0 1.88 0.89 - COMPARATIVE EXAMPLE 64 0.23 150 840 0.3 900 50 1200 10 0.93 3.5 1.87 0.91 - COMPARATIVE EXAMPLE 65 0.22 1000 820 0.2 930 60 1100 20 0.55 1.5 1.90 0.95 - COMPARATIVE EXAMPLE 66 0.22 1000 820 0.1 900 60 1200 60 0.53 1.5 1.68 1.21 - COMPARATIVE EXAMPLE

INDUSTRIAL APPLICABILITY

[0207]

According to the above-described aspects of the present invention, it is possible to provide a grain-oriented electrical steel sheet excellent in glass film adhesion. Accordingly, the present invention has significant industrial applicability.

LIST OF REFERENCES

[0208]

1 - Grain-oriented electrical steel sheet

10 - Main steel sheet

11 - Glass film

12 - Insulating coating with tension

Claims (48)

1. Grain-oriented electrical steel sheet, comprising: main steel sheet; a glass film which is placed on the base steel sheet; And insulating coating with tension, which is located on the glass film, moreover, the chemical composition of the main steel sheet and the glass film includes, wt.%: 0.010 or less C; 2.5-4.0 Si; 0.01-1.00 Mn; 0.010 or less N; 0.010 or less soluble Al; 0.005-0.030 insoluble Al; 0.05-0.20 Mg; 0.05-0.40 O; 0-0.020 Ti; 0.010 or less S; 0.030 or less P; 0-0.50 Sn; 0-0.50Cr; 0-0.50 Cu; 0-0.0100 Bi; 0-0.020 Se; 0-0.50 Sb; And a residue consisting of iron and impurities, and having glow discharge emission spectroscopy spectra of Al and Si measured by glow discharge emission spectroscopy from the surface of the glass film in the depth direction, after removal of the insulating coating, when Ts is the start time of the analysis, from the surface of the glass film, T ^Al _p - time at which Al shows the maximum emission intensity, s, F(T ^Al _p ) - Al emission intensity at T ^Al _p , in relative units, T ^Si _p - time at which Si shows the maximum emission intensity, s, F(T ^Si _p ) - Al emission intensity at T ^Si _p , in relative units, while the values of Ts, T ^Al _p , F(T ^Al _p ), T ^Si _p and F(T ^Si _p ) satisfy the expressions: 0.05 ≤ F(T ^Si _p ) / F(T ^Al _p ) ≤ 0.50 and 2.0 ≤ (T ^Al _p - Ts) / (T ^Si _p - Ts) ≤ 5.0. 2. Grain-oriented electrical steel sheet according to claim 1, characterized in that the thickness of the base steel sheet is 0.17 mm or more and less than 0.22 mm. 3. A grain-oriented electrical steel sheet according to claim 1 or 2, characterized in that the chemical composition of the base steel sheet and the glass film includes at least one element selected from, wt.%: 0.01-0.50Cr; 0.01-0.50 Sn; 0.01-0.50 Cu; 0.0010-0.0100 Bi; 0.001-0.020Se; And 0.01-0.50 Sb. 4. A sheet of electrical steel with a grain-oriented structure according to any one of paragraphs. 1-3, characterized in that the glow discharge emission spectroscopy spectra of Al and Fe are measured by glow discharge emission spectroscopy from the surface of the glass film in the depth direction, when T ^Al _p is the time at which Al shows the maximum emission intensity, s, T ^Fe ₆₀ - the time at which the Fe emission intensity becomes equal to 60% compared to the saturation value of the Fe emission intensity, s, T ^Fe ₉₀ - the time at which the Fe emission intensity becomes equal to 90% compared to the saturation value of the Fe emission intensity, s, the values of T ^Al _p , T ^Fe ₆₀ and T ^Fe ₉₀ satisfy the expression T ^Fe ₆₀ ≤ T ^Al _p ≤ T ^Fe ₉₀ .

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