The present invention relates to grain-oriented electrical steel sheets, a method for producing the same, and an annealing separator.
Background technology
[0002]
The grain-oriented electrical steel sheet is a steel sheet containing about 0.5 to 7% by mass of Si and having the crystal orientation integrated in the {110} <001> orientation (Goss orientation). The grain growth phenomenon due to secondary recrystallization is used to control the crystal orientation.
[0003]
The manufacturing method of grain-oriented electrical steel sheet is as follows. The slab is heated and hot-rolled to produce a hot-rolled steel sheet. Anneal the hot-rolled steel sheet as necessary. Pickle the hot-rolled steel sheet. A cold-rolled steel sheet is manufactured by cold-rolling a hot-rolled steel sheet after pickling at a cold-rolling rate of 80% or more. The cold-rolled steel sheet is decarburized and annealed to develop primary recrystallization. After decarburization annealing, the cold-rolled steel sheet is finish-annealed to develop secondary recrystallization. Through the above steps, grain-oriented electrical steel sheets are manufactured.
[0004]
After the above-mentioned decarburization annealing and before finish annealing, an aqueous slurry containing an annealing separator containing MgO as a main component is applied to the surface of the cold-rolled steel sheet and dried (baked). After winding the cold-rolled steel sheet on which the annealing separator has been baked onto a coil, finish annealing is performed. During finish annealing, MgO in the annealing separator reacts with SiO 2 in the internal oxide layer formed on the surface of the cold-rolled steel sheet during decarburization annealing, and contains forsterite (Mg 2SiO 4) as the main component. A primary coating is formed on the surface.
[0005]
After forming the primary coating, an insulating coating (also referred to as a secondary coating) composed of, for example, colloidal silica and phosphate is formed on the primary coating. The primary coating and insulating coating have a lower coefficient of thermal expansion than steel sheets. Therefore, the primary coating, together with the insulating coating, applies tension to the steel sheet to reduce iron loss. The primary coating further enhances the adhesion of the insulating coating to the steel sheet. Therefore, it is preferable that the primary coating has high adhesion to the steel sheet.
[0006]
On the other hand, in order to reduce the iron loss of grain-oriented electrical steel sheets, it is also effective to increase the magnetic flux density to reduce the hysteresis loss. In order to increase the magnetic flux density of the grain-oriented electrical steel sheet, it is effective to integrate the crystal orientation of the grain steel sheet in the Goss orientation. Techniques for enhancing the accumulation in the Goss direction are described in Patent Documents 1 to 3. In the techniques described in Patent Documents 1 to 3, magnetic property improving elements (Sn, Sb, Bi, Te, Pb, Se, etc.) that enhance the action of the inhibitor are added to the steel sheet. As a result, the accumulation in the Goss direction is increased, and the magnetic flux density can be increased.
[0007]
However, when the steel sheet contains an element for improving magnetic properties, a part of the primary film is aggregated, the interface between the steel sheet and the primary film is easily flattened, and the adhesion of the primary film to the steel sheet is lowered.
[0008]
Patent Documents 4 and 5 describe techniques for improving the adhesion of the primary coating to the steel sheet.
Patent Document 4 describes that by adding Ce, La, etc. to the annealing separator, Ce, La, etc. are contained in the primary coating in a basis weight of 0.001 to 1000 mg / m 2 per side.
Further, Patent Document 5 describes that the specific surface area of ​​the main agent MgO of the annealing separator is controlled, and at least one of Ca, Sr and Ba compounds is added to the annealing separator to improve the coating properties. ing.
Prior art literature
Patent documents
[0009]
Patent Document 1: Japanese Patent Application Laid-Open No. 6-88171
Patent Document 2: Japanese Patent Application Laid-Open No. 8-269552
Patent Document 3: Japanese Unexamined Patent Publication No. 2005-290446
Patent Document 4: Japanese Patent Application Laid-Open No. 2012-214902
Patent Document 5: Japanese Unexamined Patent Publication No. 11-302730
Outline of the invention
Problems to be solved by the invention
[0010]
As a result of diligent studies to further improve the performance of grain-oriented electrical steel sheets, the present inventors have included Ce or La in the tempering separator as described in Patent Document 4 in grain-oriented electrical steel sheets. Increasing the amount or increasing the content of Ca, Sr, or Ba in the baking separator as described in Patent Document 5 improves the film adhesion of the grain-oriented electrical steel sheet, but deteriorates the magnetic properties. It turns out that there are cases. It was also found that there is a region in the surface of the steel sheet that is inferior in film adhesion, and further improvement in film adhesion is required.
[0011]
An object of the present invention is to provide a grain-oriented electrical steel sheet having excellent adhesion to a steel sheet of a primary film, a method for producing the same, and an annealing separator, which improves the deterioration of film adhesion, has excellent magnetic properties, and has excellent adhesion to a steel sheet of a primary film. ..
Means to solve problems
[0012]
The present invention is as listed below.
(1) In mass%, C: 0.005% or less, Si: 2.5 to 4.5%, Mn: 0.050 to 1.000%, total of S and Se: 0.005% or less, sol .. A base steel sheet containing Al: 0.005% or less and N: 0.005% or less and having a chemical composition in which the balance is Fe and impurities, and Mg 2SiO 4 formed on the surface of the base steel sheet. A grain-oriented electrical steel sheet having a primary coating contained as a main component.
The peak position of the Al emission intensity obtained when elemental analysis by the glow discharge emission spectrometry method is performed from the surface of the primary coating in the plate thickness direction of the directional electromagnetic steel plate is from the surface of the primary coating in the plate thickness direction. It exists in the range of 2.0 to 12.0 μm and
The total circumference of the Al oxide at the peak position of the Al emission intensity is 0.20 to 1.00 μm / μm 2, and
A grain-oriented electrical steel sheet having a density of Al oxides of 0.02 to 0.20 / μm 2.
[0013]
(2) In mass%, C: 0.100% or less, Si: 2.5 to 4.5%, Mn: 0.050 to 1.000%, total of S and Se: 0.002 to 0.050 %, Sol. Cold-rolled steel sheet containing Al: 0.005 to 0.050% and N: 0.001 to 0.030% and having a chemical composition in which the balance is Fe and impurities at a cold rolling ratio of 80% or more. The cold rolling process of rolling to produce cold-rolled steel sheets,
The decarburization annealing process of decarburizing and annealing the cold-rolled steel sheet,
An aqueous slurry containing an annealing separator containing MgO as a main component is applied to the surface of the cold-rolled steel sheet after decarburization and annealing, and the aqueous slurry on the surface of the cold-rolled steel sheet is dried in a furnace at 400 to 1000 ° C. After that, the cold-rolled steel sheet includes a finish annealing step of performing finish annealing.
The quenching separator contains the MgO, one or more hydroxides, sulfates or carbonates of Ca, Sr or Ba, and one or more Ti compounds, Y compounds, La compounds or Ce compounds.
The particle size distribution of MgO is such that the content of particles having a particle size of 1.0 μm or less is 20 to 30% by mass and the content of particles having a particle size of 10 μm or more is 2 to 5% by mass with respect to the content of MgO. % And
The Ca, Sr or Ba hydroxide, sulfate or carbonate is contained in the range of 0.5 to 10.0% by mass in total with respect to the content of MgO, and is contained with respect to the content of MgO. The value obtained by dividing the content of the hydroxide, sulfate or carbonate of Ca by the molecular weight of the hydroxide, sulfate or carbonate of Ca, the hydroxide or sulfate of Sr with respect to the content of MgO. Alternatively, the content of the hydroxide, sulfate or carbonate of Ba is divided by the molecular weight of the hydroxide, sulfate or carbonate of Sr, and the content of the hydroxide, sulfate or carbonate of Ba with respect to the content of MgO. When the value divided by the molecular weight of the hydroxide, sulfate or carbonate of Ba is [Ca], [Sr], and [Ba], respectively, X / ([Ca] + [Sr] + [Ba]) Satisfies the range of 0.80 to 1.00,
The average particle size of the hydroxide, sulfate or carbonate of Ca, Sr or Ba is 1.0 to 10.0 μm, and the hydroxide, sulfate of Ca, Sr or Ba with respect to the median diameter of MgO. The average particle size ratio of salt or carbonate is 0.8-2.5 and
The production of the directional electromagnetic steel plate according to (1), wherein the content of the Ti compound, Y compound, La compound or Ce compound is 1.0 to 15.0% by mass in total with respect to the content of MgO. Method.
However, X means the highest value among [Ca], [Sr] or [Ba].
[0014]
(3) The average particle size of the hydroxide, sulfate or carbonate of the element having the highest content among the hydroxide, sulfate or carbonate of Ca, Sr or Ba is 1.0 to 10.0 μm. A method for manufacturing a directional electromagnetic steel plate according to (2).
[0015]
(4) The method for manufacturing a grain-oriented electrical steel sheet according to (2) or (3), wherein the hot-rolled steel sheet contains one or more of Sb, Sn or Cu in a total amount of 0.30% by mass or less.
[0016]
(5) The method for manufacturing a grain-oriented electrical steel sheet according to any one of (2) to (4), wherein the hot-rolled steel sheet contains one or more of Bi, Te or Pb in a total amount of 0.0300% by mass or less. ..
[0017]
(6) Annealing separator containing MgO as the main component.
It contains one or more hydroxides, sulfates or carbonates of Ca, Sr or Ba, and one or more Ti compounds, Y compounds, La compounds or Ce compounds.
The particle size distribution of MgO is such that the content of particles having a particle size of 1.0 μm or less is 20 to 30% by mass and the content of particles having a particle size of 10 μm or more is 2 to 5% by mass with respect to the content of MgO. % And
The Ca, Sr or Ba hydroxide, sulfate or carbonate is contained in the range of 0.5 to 10.0% by mass in total with respect to the content of MgO, and is contained with respect to the content of MgO. The value obtained by dividing the content of the hydroxide, sulfate or carbonate of Ca by the molecular weight of the hydroxide, sulfate or carbonate of Ca, the hydroxide or sulfate of Sr with respect to the content of MgO. Alternatively, the content of the hydroxide, sulfate or carbonate of Ba is divided by the molecular weight of the hydroxide, sulfate or carbonate of Sr, and the content of the hydroxide, sulfate or carbonate of Ba with respect to the content of MgO. When the value divided by the molecular weight of the hydroxide, sulfate or carbonate of Ba is [Ca], [Sr], and [Ba], respectively, X / ([Ca] + [Sr] + [Ba]) Satisfies the range of 0.80 to 1.00,
The average particle size of the hydroxide, sulfate or carbonate of Ca, Sr or Ba is 1.0 to 10.0 μm, and the hydroxide, sulfate of Ca, Sr or Ba with respect to the median diameter of MgO. The average particle size ratio of salt or carbonate is 0.8-2.5 and
The content of the Ti compound, Y compound, La compound or Ce compound is 1.0 to 15.0% by mass in total with respect to the MgO, which is an annealing separator.
However, X means the highest value among [Ca], [Sr] or [Ba].
[0018]
(7) The average particle size of the hydroxide, sulfate or carbonate of the element having the highest content among the hydroxide, sulfate or carbonate of Ca, Sr or Ba is 1.0 to 10.0 μm. There is a quenching separator according to (6).
The invention's effect
[0019]
According to one aspect of the present invention, by reducing the diameter of the compound of Ca, Sr, or Ba, the root of the primary coating is formed before SiO 2 in the internal oxide layer aggregates and coarsens, and the primary coating is formed. It is possible to develop the fitting structure of the interface of the steel sheet. Therefore, according to one aspect of the present invention, it is possible to improve the deterioration of the film adhesion in the conventional technique, and to provide a grain-oriented electrical steel sheet having excellent magnetic properties and excellent adhesion of the primary film to the steel sheet.
Embodiment for carrying out the invention
[0020]
Hereinafter, the present invention will be described together with the principle thereof. In the description of the transition, "%" with respect to the chemical composition means "% by weight" unless otherwise noted. Further, unless otherwise specified, the notation "A to B" for the numerical values ​​A and B means "A or more and B or less". When a unit is attached only to the numerical value B in such a notation, the unit shall be applied to the numerical value A as well.
[0021]
1. 1. Directional electrical steel sheet
The grain-oriented electrical steel sheet according to one aspect of the present invention includes a base steel sheet and a primary coating formed on the surface of the base steel sheet containing forsterite (Mg 2SiO 4) as a main component. On the primary coating, for example, an insulating coating composed of colloidal silica and phosphate may be provided. Since both the primary coating and the insulating coating have a smaller coefficient of thermal expansion than the steel sheet, tension is applied to the steel sheet to reduce iron loss. If the adhesion of the primary coating is low, the secondary coating will peel off from the steel sheet together with the primary coating, so it is preferable that the adhesion of the primary coating to the steel sheet is high. ..
Here, the "main component" refers to a component contained in a substance in an amount of 50% by mass or more, and the main component is preferably contained in a substance in an amount of preferably 70% by mass or more, more preferably 90% by mass or more. ..
[0022]
1.1. Chemical composition of base steel sheet
The base steel sheet constituting the grain-oriented electrical steel sheet according to one aspect of the present invention contains the elements listed below. As will be described in Section 2 below, the base steel sheet is manufactured by cold rolling, decarburization annealing, and finish annealing on a hot-rolled steel sheet having a chemical composition described later. First, the essential elements will be explained.
[0023]
(1) C: 0.005% or less
C is an element effective for microstructure control until the completion of the decarburization annealing process in the manufacturing process. However, if the C content exceeds 0.005%, the magnetic properties of the grain-oriented electrical steel sheet, which is the product plate, deteriorate. Therefore, the C content is 0.005% or less, preferably 0.003% or less.
On the other hand, it is preferable that the C content is low, but even if the C content is reduced to less than 0.0001%, the effect of tissue control is saturated and the manufacturing cost is only increased. Therefore, the C content is preferably 0.0001% or more.
[0024]
(2) Si: 2.5-4.5%
Si increases the electrical resistance of steel and reduces eddy current loss. If the Si content is less than 2.5%, the effect of reducing eddy current loss cannot be sufficiently obtained. On the other hand, when the Si content exceeds 4.5%, the cold workability of the steel deteriorates. Therefore, the Si content is 2.5-4.5%. The Si content is preferably 2.7% or more, more preferably 2.8% or more. On the other hand, the Si content is preferably 4.2% or less, and more preferably 4.0% or less.
[0025]
(3) Mn: 0.050 to 1.000%
Mn combines with S and Se described later to form MnS and MnSe during the manufacturing process. These precipitates function as inhibitors (inhibitors of normal grain growth) and express secondary recrystallization in steel. Mn also enhances the hot workability of steel.
If the Mn content is less than 0.050%, these effects cannot be sufficiently obtained. On the other hand, when the Mn content exceeds 1.000%, secondary recrystallization does not occur and the magnetic properties of the steel deteriorate. Therefore, the Mn content is 0.050 to 1.000%. The Mn content is preferably 0.060% or more, and more preferably 0.065% or more. On the other hand, the Mn content is preferably 0.400% or less, and more preferably 0.200% or less.
[0026]
(4) Total of S and Se: 0.005% or less
S and Se combine with Mn in the manufacturing process to form MnS and MnSe that function as inhibitors. However, when the total S and Se contents exceed 0.005%, the remaining inhibitors may deteriorate the magnetic properties, and the segregation of S and Se may cause surface defects in the grain-oriented electrical steel sheet. .. Therefore, the total content of S and Se is 0.005% or less.
It is preferable that the total content of S and Se in the grain-oriented electrical steel sheet is as low as possible. However, even if the total content of S and Se in the grain-oriented electrical steel sheet is reduced to less than 0.0001%, the manufacturing cost is only increased. Therefore, the total content of S and Se in the grain-oriented electrical steel sheet is preferably 0.0001% or more.
[0027]
(5) sol. Al: 0.005% or less
Al combines with N during the manufacturing process of grain-oriented electrical steel sheets to form AlN that functions as an inhibitor. However, sol. When the Al content exceeds 0.005%, the inhibitor remains excessively in the base steel sheet, so that the magnetic properties deteriorate. Therefore, sol. The Al content is 0.005% or less.
Sol. The Al content is preferably 0.004% or less, more preferably 0.003% or less. sol. It is preferable that the Al content is as low as possible. However, sol. Reducing the Al content to less than 0.0001% only increases the manufacturing cost. Therefore, sol. In the grain-oriented electrical steel sheet. The Al content is preferably 0.0001% or more. In addition, in this specification, sol. Al means acid-soluble Al.
[0028]
(6) N: 0.005% or less
N binds to Al in the manufacturing process to form AlN that functions as an inhibitor. However, when the N content exceeds 0.005%, the inhibitor remains excessively in the grain-oriented electrical steel sheet and the magnetic properties deteriorate. Therefore, the N content is 0.005% or less.
The N content is preferably 0.004% or less, more preferably 0.003% or less. It is preferable that the N content is as low as possible. However, reducing the N content to less than 0.0001% only increases the manufacturing cost. Therefore, the N content is preferably 0.0001% or more.
[0029]
(7) Remaining: Fe and impurities
The balance of the chemical composition of the base steel sheet of the grain-oriented electrical steel sheet according to one aspect of the present invention is Fe and impurities. Here, impurities are those that are mixed in from ore, scrap, or the manufacturing environment as raw materials when the base steel sheet is industrially manufactured, and are not removed from the steel during finish annealing (not purified). It means the following elements remaining in steel, which are allowed to be contained in a content that does not adversely affect the action of the grain-oriented electrical steel sheet according to one aspect of the present invention.
[0030]
The total content of one or more of Sn, Sb, Cu, Bi, Te or Pb in the impurities in the base steel sheet of the directional electromagnetic steel sheet according to one aspect of the present invention is 0.03% or less.
All of these elements increase the magnetic flux density of the grain-oriented electrical steel sheet, but since they are removed from the base steel sheet by finish annealing, they are all impurities, and as mentioned above, the total is 0.03% or less.
[0031]
1.2. Primary coating
(1) Chemical composition
The grain-oriented electrical steel sheet according to one aspect of the present invention has a primary coating. The primary coating is formed on the surface of the base steel sheet. The main component of the primary coating is forsterite (Mg 2SiO 4).
[0032]
In the primary coating, SiO 2 in the internal oxide layer formed on the surface layer of the steel sheet in the decarburization annealing step and MgO, which is the main component of the annealing separator that is applied and dried on the steel sheet before finish annealing, are used for finish annealing. It is formed by reacting in.
[0033]
In one aspect of the present invention, in the production of a directional electromagnetic steel plate, one or more of Ti compound, Y compound, La compound or Ce compound is contained, and further, a hydroxide, sulfate or carbonate of Ca, Sr or Ba is contained. Use a quenching separator containing one or more salts. As a result, the magnetic properties of the grain-oriented electrical steel sheet can be enhanced, and the film adhesion of the primary coating can also be enhanced.
[0034]
(2) Peak position of Al emission intensity by glow discharge emission spectrometry (GDS method): Primary coating
Within the range of 2.0 to 12.0 μm in the plate thickness direction from the surface of
The peak position of Al emission intensity obtained when elemental analysis by glow discharge emission spectrometry is performed from the surface of the primary coating in the plate thickness direction of the directional electromagnetic steel plate is 2.0 to the plate thickness direction from the surface of the primary coating. It exists within the range of 12.0 μm.
[0035]
In grain-oriented electrical steel sheets, the interface between the primary coating and the steel sheet (bare metal) has an inset structure. Specifically, a part of the primary coating penetrates into the inside of the steel sheet from the surface of the steel sheet. A part of the primary coating that has entered the inside of the steel sheet from the surface of the steel sheet exerts a so-called anchor effect and enhances the adhesion of the primary coating to the steel sheet. Hereinafter, in the present specification, a part of the primary coating that enters the inside of the steel sheet from the surface of the steel sheet is defined as "the root of the primary coating".
[0036]
In the region where the roots of the primary coating penetrate deeply into the steel sheet, the main component of the roots of the primary coating is spinel (MgAl 2O 4), which is a kind of Al oxide. The peak of the Al emission intensity obtained when the elemental analysis by the glow discharge emission spectrometry is performed indicates the position of the spinel.
[0037]
The depth position of the Al emission intensity peak from the surface of the primary coating is defined as the Al peak position D Al (μm). The Al peak position D Al of less than 2.0 μm means that the spinel is formed at a position shallow from the surface of the steel sheet, that is, the root of the primary coating is shallow. In this case, the adhesion of the primary coating is low. On the other hand, when the Al peak position D Al exceeds 12.0 μm, it means that the roots of the primary coating are overdeveloped, and the roots of the primary coating penetrate deep into the inner part of the steel sheet. In this case, the roots of the primary coating hinder the movement of the domain wall, and the magnetic properties deteriorate.
[0038]
When the Al peak position D Al is 2.0 to 12.0 μm, the adhesion of the primary coating can be improved while maintaining excellent magnetic characteristics. The Al peak position D Al is preferably 3.0 μm or more, and more preferably 4.0 μm or more. On the other hand, the Al peak position D Al is preferably 11.0 μm or less, and more preferably 10.0 μm or less.
[0039]
Al peak position D Al is measured by the following method. Elemental analysis is performed using a well-known glow discharge emission spectrometry method (GDS method). Specifically, an Ar atmosphere is created on the surface of the grain-oriented electrical steel sheet. A voltage is applied to the grain-oriented electrical steel sheet to generate glow plasma, and the surface layer of the steel sheet is sputtered and analyzed in the plate thickness direction. Al contained in the surface layer of the steel sheet is identified based on the emission spectrum wavelength peculiar to the element generated by exciting the atom in the glow plasma. Furthermore, the emission intensity of the identified Al is plotted in the depth direction. Based on the plotted Al emission intensity, the Al peak position D Al is obtained.
[0040]
The depth position from the surface of the primary coating in elemental analysis is calculated based on the spatter time. Specifically, the relationship between the spatter time and the spatter depth (hereinafter referred to as the sample result) is obtained in advance in the standard sample, and the spatter time is converted into the spatter depth using the sample result. The converted sputter depth is defined as the depth position (depth position from the surface of the primary coating) subjected to elemental analysis (Al analysis). In the GDS method in the present disclosure, a commercially available high frequency glow discharge emission spectrometer can be used.
[0041]
(3) Total circumference of Al oxide at the peak position of Al emission intensity: 0.20 to 1.00 μm / μm 2
In the directional electromagnetic steel plate according to one aspect of the present invention, the total circumference of the Al oxide at the Al peak position D Al is 0.20 to 1.00 μm / μm 2.
[0042]
As described above, the Al peak position D Al corresponds to the root portion of the primary coating. Spinel (MgAl 2O 4), which is an Al oxide, is abundantly present in the roots of the primary coating. Therefore, the sum of the circumferences of the Al oxide in an arbitrary region at the Al peak position D Al (for example, the bottom of the discharge mark of the glow discharge) is an index indicating the spread of the root (spinel) of the primary film.
[0043]
If the total circumference of the Al oxide is less than 0.20 μm / μm 2, the roots of the primary coating are not sufficiently formed. Therefore, the adhesion of the primary coating to the steel sheet is low. On the other hand, when the total circumference of the Al oxide exceeds 1.00 μm / μm 2, the roots of the primary coating are excessively developed and the roots of the primary coating penetrate deep into the inner part of the steel sheet. Roots inhibit secondary recrystallization and domain wall migration, resulting in reduced magnetic properties. Therefore, the total circumference of the Al oxide is 0.20 to 1.00 μm / μm 2.
[0044]
The total circumference of the Al oxide is preferably 0.25 μm / μm 2 or more, and more preferably 0.27 μm / μm 2 or more. On the other hand, the total circumference of the Al oxide is preferably 0.98 μm / μm 2 or less, and more preferably 0.95 μm / μm 2 or less.
[0045]
The total circumference of Al oxide can be obtained by the following method. Glow discharge is performed by the glow discharge emission spectrometer to the Al peak position D Al. Energy dispersive X-ray spectroscope (observation region) for any 36 μm × 50 μm region (observation region) of the discharge marks at the Al peak position D Al. Elemental analysis by EDS) is performed to identify Al oxides in the observation area. Specifically, the region in which the intensity of the characteristic X-ray of O of 50% or more is analyzed with respect to the maximum intensity of the characteristic X-ray of O in the observation region is specified as an oxide. In the region of the specified oxide, the region where the intensity of the specific X-ray of Al of 30% or more with respect to the maximum intensity of the specific X-ray of Al is analyzed is specified as the Al oxide. The identified Al oxide is predominantly spinel and may be other silicates containing various alkaline earth metals and Al in high concentrations. The circumference (μm) is calculated from the shape of the specified Al oxide in the analysis result of the EDS image data, and based on this, the total circumference of the Al oxide per unit area (μm 2) of the observation region (μm 2) is calculated. μm) (Unit: μm / μm 2) is calculated. As described above, the total circumference of Al oxide in the present disclosure means the total circumference of Al oxide per unit area of ​​the observation region.
[0046]
(4) Number of Al oxides Density: 0.02 to 0.20 / μm 2
In the directional electromagnetic steel plate according to one aspect of the present invention, the number density of Al oxides at the Al peak position D Al is 0.02 to 0.20 / μm 2.
[0047]
As described above, the Al peak position D Al corresponds to the root portion of the primary coating. Spinel (MgAl 2O 4), which is an Al oxide, is abundantly present in the roots of the primary coating. Therefore, if the number density of Al oxides in an arbitrary region at the Al peak position D Al (for example, the bottom of the discharge mark of the glow discharge) is defined as the Al oxide number density ND, the Al oxide number density ND is the primary coating. It is an index showing the dispersed state of the root (spinel) on the surface layer of the steel plate.
If the Al oxide number density ND is less than 0.02 / μm 2, the roots of the primary coating are not sufficiently formed, and the adhesion of the primary coating to the steel sheet is low. On the other hand, when the Al oxide number density ND exceeds 0.20 / μm 2, the roots of the primary coating are excessively developed and the roots of the primary coating penetrate deep into the inner part of the steel sheet, and the roots of the primary coating are formed. Since it inhibits secondary recrystallization and domain wall movement, the magnetic properties deteriorate. Therefore, the Al oxide number density ND is 0.02 to 0.20 / μm 2.
[0048]
The Al oxide number density ND is preferably 0.025 / μm 2 or more. On the other hand, the Al oxide number density ND is preferably 0.18 pieces / μm 2 or less, and more preferably 0.15 pieces / μm 2 or less.
[0049]
The Al oxide number density ND can be obtained by the following method. Glow discharge is performed by the glow discharge emission spectrometer to the Al peak position D Al. Elemental analysis using an energy dispersive X-ray spectroscope (EDS) is performed on an arbitrary 36 μm × 50 μm region (observation region) of the discharge marks at the Al peak position D Al, and the Al oxide in the observation region is performed. To identify.
[0050]
Specifically, the region in which the intensity of the characteristic X-ray of O of 50% or more is analyzed with respect to the maximum intensity of the characteristic X-ray of O in the observation region is specified as an oxide. In the specified oxide region, a region in which the intensity of the specific X-ray of Al of 30% or more with respect to the maximum intensity of the specific X-ray of Al is analyzed is specified as an Al oxide.
The identified Al oxide is mainly spinel, and may also be a silicate containing various alkaline earth metals and Al at high concentrations. The number of specified Al oxides is counted, and the Al oxide number density ND (pieces / μm 2) is obtained as ND = the number of specified Al oxides / the area of ​​the observation region.
[0051]
2. 2. Manufacturing method of grain-oriented electrical steel sheet
The above-mentioned grain-oriented electrical steel sheet can be manufactured, for example, by the method for manufacturing grain-oriented electrical steel sheet according to one aspect of the present invention.
The manufacturing method according to one aspect of the present invention includes a cold rolling step, a decarburization step, and a finish annealing step. Hereinafter, each step will be described in sequence.
[0052]
(1) Cold rolling process
In the cold rolling process, C: 0.100% or less, Si: 2.5 to 4.5%, Mn: 0.050 to 1.000%, one or more of S and Se: 0.002 to total. 0.050%, sol. Al: 0.005 to 0.050% and N: 0.001 to 0.030% are contained as essential elements, and one or more of Sb, Sn and Cu: 0.30% or less in total, and , Bi, Te and Pb or more: 80% or more in a hot-rolled steel sheet having a chemical composition containing one or both of 0.0300% or less in total as an optional element and the balance being Fe and impurities. Cold-rolled steel sheets are manufactured by cold-rolling at a cold-rolling rate. The reason for limiting the chemical composition of the hot-rolled steel sheet will be explained.
[0053]
(1-1) Chemical composition of hot-rolled steel sheet
First, the essential elements will be explained.
[0054]
(1-1-1) C: 0.100% or less
If the C content of the hot-rolled steel sheet exceeds 0.100%, the time required for decarburization annealing becomes long, the manufacturing cost increases, and the productivity also decreases. Therefore, the C content of the hot-rolled steel sheet is 0.100% or less. The C content of the hot-rolled steel sheet is preferably 0.080% or less, more preferably 0.070% or less.
[0055]
(1-1-2) Si: 2.5-4.5%
As explained in the section on the chemical composition of grain-oriented electrical steel sheets described above, Si increases the electrical resistance of steel, but if it is contained in excess, the cold workability deteriorates. When the Si content is 2.5 to 4.5%, the Si content of the grain-oriented electrical steel sheet after the finish annealing step is 2.5 to 4.5%.
[0056]
(1-1-3) Mn: 0.050 to 1.000%
As described in the section on the chemical composition of grain-oriented electrical steel sheets described above, Mn binds to S and Se during the manufacturing process to form a precipitate that functions as an inhibitor. Mn further enhances the hot workability of steel. When the Mn content of the hot-rolled steel sheet is 0.050 to 1.000%, the Mn content of the directional electromagnetic steel sheet after the finish annealing step is 0.050 to 1.000%.
[0057]
(1-1-4) Total of S and Se: 0.002 to 0.050%
In the manufacturing process, S and Se combine with Mn to form MnS and MnSe. Both MnS and MnSe function as inhibitors necessary for suppressing grain growth during secondary recrystallization.
If the total content of S and Se is less than 0.002%, it is difficult to obtain the effect of forming MnS and MnSe. On the other hand, when the total content of S and Se exceeds 0.050%, secondary recrystallization does not occur in the manufacturing process, and the magnetic properties of the steel deteriorate.
Therefore, the total content of S and Se is 0.002 to 0.050%. The total content of S and Se is preferably 0.040% or less, more preferably 0.030% or less.
[0058]
(1-1-5) sol. Al: 0.005 to 0.050%
During the manufacturing process, Al combines with N to form AlN. AlN functions as an inhibitor. sol. If the Al content is less than 0.005%, the effect of binding with N to form AlN cannot be obtained. On the other hand, the sol. When the Al content exceeds 0.050%, AlN becomes coarse, AlN becomes difficult to function as an inhibitor, and secondary recrystallization may not occur.
Therefore, the hot-rolled steel sheet sol. The Al content is 0.005 to 0.050%. sol. The Al content is preferably 0.040% or less, more preferably 0.030% or less. On the other hand, sol. The Al content is preferably 0.010% or more, and more preferably 0.020% or more.
[0059]
(1-1-6) N: 0.001 to 0.030%
During the manufacturing process, N binds to Al to form AlN that functions as an inhibitor. If the N content is less than 0.001%, this effect cannot be obtained. On the other hand, when the N content exceeds 0.030%, AlN becomes coarse, AlN becomes difficult to function as an inhibitor, and secondary recrystallization may not occur.
Therefore, the N content is 0.001 to 0.030%. The N content is preferably 0.012% or less, more preferably 0.010% or less. On the other hand, the N content is preferably 0.005% or more, and more preferably 0.006% or more.
[0060]
Next, arbitrary elements will be explained.
[0061]
(1-1-7) One or more of Sb, Sn or Cu: 0.30% or less in total
The hot-rolled steel sheet may further contain one or more of Sb, Sn or Cu as an optional element in a total of 0.30% or less.
Sb, Sn or Cu are optional elements that are contained as necessary, and may not be contained. When contained, Sb, Sn or Cu all increase the magnetic flux density of the grain-oriented electrical steel sheet. If even a small amount of Sb, Sn or Cu is contained, the magnetic flux density is increased.
However, when the total content of Sb, Sn or Cu exceeds 0.30%, it becomes difficult to form an internal oxide layer during decarburization annealing, and during finish annealing, MgO as an annealing separator and SiO 2 of the internal oxide layer are present. Since the formation of the primary film that progresses in reaction is delayed, the adhesion of the formed primary film is reduced.
Therefore, the total content of Sb, Sn or Cu is 0.00 to 0.30%. The total content of Sb, Sn or Cu is preferably 0.005% or more, more preferably 0.007% or more. On the other hand, the total content of Sb, Sn or Cu is preferably 0.25% or less, and more preferably 0.20% or less.
[0062]
(1-1-8) One or more of Bi, Te or Pb: 0.0300% or less in total
The hot-rolled steel sheet may further contain one or more of Bi, Te or Pb as an optional element in a total of 0.0300% or less.
Bi, Te and Pb are all optional elements and may not be contained. By containing at least one of these elements as much as possible, the magnetic flux density of the grain-oriented electrical steel sheet can be further increased.
However, if the total content of these elements exceeds 0.0300%, these elements segregate on the surface during finish annealing, and the interface between the primary coating and the steel sheet is flattened, resulting in a decrease in film adhesion of the primary coating. do.
Therefore, the total content of one or more of Bi, Te and Pb is 0.0000 to 0.0300%. The total content of one or more of Bi, Te and Pb is preferably 0.0005% or more, more preferably 0.0010% or more.
[0063]
(1-1-9) Remaining: Fe and impurities
The rest of the chemical composition of the hot-rolled steel sheet is Fe and impurities. Here, the impurities are mixed from ore, scrap, manufacturing environment, etc. as a raw material when the hot-rolled steel sheet is industrially manufactured, and are the directional electromagnetic steel sheets according to one aspect of the present invention. It means an acceptable substance as long as it does not adversely affect the action.
[0064]
(1-2) Manufacturing method of hot-rolled steel sheet
The hot-rolled steel sheet having the above-mentioned chemical composition is manufactured by a well-known method. An example of a method for manufacturing a hot-rolled steel sheet is as follows. Prepare a slab having the same chemical composition as the hot-rolled steel sheet described above. Slabs are manufactured through well-known refining and casting processes.
Heat the slab. The heating temperature of the slab is, for example, more than 1280 ° C and 1350 ° C or less. The heated slab is hot-rolled to produce a hot-rolled steel sheet.
[0065]
(1-3) Cold rolling conditions
Cold-roll the prepared hot-rolled steel sheet to manufacture a cold-rolled steel sheet, which is the base steel sheet. Cold rolling may be performed only once or may be performed a plurality of times. When cold rolling is performed a plurality of times, intermediate annealing is performed for the purpose of softening after cold rolling, and then cold rolling is performed. A cold-rolled steel sheet having a product plate thickness (plate thickness as a product) is manufactured by performing cold rolling once or a plurality of times.
The cold rolling ratio in one or more cold rolling is 80% or more. Here, the cold spread rate (%) is defined as follows.
Cold rolling ratio (%) = {1- (thickness of cold-rolled steel sheet after the last cold rolling) / (thickness of hot-rolled steel sheet before the start of the first cold rolling)} x 100
The cold spread rate is preferably 95% or less. In addition, cold pressure is applied to the hot-rolled steel sheet. The hot-rolled steel sheet may be heat-treated or pickled before rolling.
[0066]
(2) Decarburization annealing process
In the decarburization process, decarburization annealing is performed on the cold-rolled steel sheet obtained through the cold rolling process.
Decarburization annealing is performed on the steel sheet manufactured by the cold rolling process, and nitriding annealing is performed as necessary. Decarburization annealing is performed in a well-known hydrogen-nitrogen-containing moist atmosphere. Decarburization annealing reduces the C concentration of grain-oriented electrical steel sheets to 50 ppm or less.
In decarburization annealing, primary recrystallization develops on the steel sheet, and the processing strain introduced by the cold rolling process is released. Further, in the decarburization annealing step, an internal oxide layer containing SiO 2 as a main component is formed on the surface layer portion of the steel sheet. The annealing temperature in decarburization annealing is well known, for example, 750 to 950 ° C. The holding time at the annealing temperature is, for example, 1 to 5 minutes.
[0067]
(3) Finish annealing process
Finish annealing is performed on the steel sheet after the decarburization annealing process. In the finish annealing step, first, an aqueous slurry containing an annealing separator is applied to the surface of the cold-rolled steel sheet after decarburization and annealing, and the aqueous slurry on the surface of the cold-rolled steel sheet is dried in a furnace at 400 to 1000 ° C. .. Annealing (finish annealing) is performed on the steel sheet to which the aqueous slurry is applied and dried.
[0068]
(3-1) Aqueous slurry
The aqueous slurry is purified by adding water (typically industrial pure water) to the annealing separator described later and stirring. The ratio of the annealing separator and water may be determined so as to be the required coating amount when applied with a roll coater. For example, the ratio of water to the annealing separator is preferably 2 times or more and 20 times or less on a mass basis. .. When the ratio of water to the annealing separator is 2 times or more, the viscosity of the water slurry does not become too high, and the annealing separator can be uniformly applied to the surface of the steel sheet, which is preferable. When the ratio of water to the annealing separator is 20 times or less, the water slurry is not sufficiently dried in the subsequent drying step, and the water remaining in the finish annealing deteriorates the appearance of the primary coating due to the additional oxidation of the steel sheet. Is less likely to occur and is preferable.
[0069]
(3-2) Annealing separator according to one aspect of the present invention
The annealing separator according to one aspect of the present invention used in the finish annealing step contains MgO as a main component. The amount of the annealing separator adhered to the steel sheet is preferably 2 g / m 2 or more and 10 g / m 2 or less per one side, for example. When the amount of the annealing separator adhered to the steel sheet is 2 g / m 2 or more, it is preferable that the steel sheets are less likely to seize in the finish annealing. When the amount of the annealing separator adhered to the steel sheet is 10 g / m 2 or less, the production cost does not increase, which is preferable.
Hereinafter, the annealing separator according to one aspect of the present invention will be described. The particle size distribution of MgO, the median diameter of MgO, the hydroxide of Ca, Sr or Ba, the average particle size of sulfate or carbonate (that is, the volume average diameter MV) described in the present disclosure are determined by JIS Z8825 (2013). It is a volume-based value measured by the laser diffraction / scattering method according to the above. Therefore, the content of each of the particles having a particle size of 1.0 μm or less and the particles having a particle size of 10 μm or more of MgO is expressed by the mass-based value of the above-mentioned volume-based value.
[0070]
(3-2-1) Particle size distribution of MgO
MgO, which is the main component of the annealing separator, has the following particle size distribution. The content of particles having a particle size of 1.0 μm or less is 20 to 30% with respect to the content of MgO contained in the annealing separator, and the content of particles having a particle size of 10 μm or more is 2 to 5%. be.
[0071]
(3-2-2) Hydroxide, sulfate or carbonate of Ca, Sr, or Ba
The annealing separator contains one or more Ca, Sr, or Ba hydroxides, sulfates, or carbonates. The content of the hydroxide, sulfate or carbonate of Ca, Sr, or Ba is 0.5 to 10.0% in total with respect to the content of MgO contained in the quenching separator. The amount may be, for example, 1.0% or more, 1.5% or more, or 2.0% or more, for example, 9.5% or less, or 9.0% or less, or 8.5%. It may be as follows. Further, the value obtained by dividing the content of Ca hydroxide, sulfate or carbonate with respect to the content of MgO by the molecular weight of hydroxide, sulfate or carbonate of Ca, and the hydroxide of Sr with respect to the content of MgO. , Sulfate or carbonate content divided by the molecular weight of Sr hydroxide, sulfate or carbonate, and Ba hydroxide, sulfate or carbonate content relative to MgO content, Ba X / ([Ca] + [Sr] + [Ba]), where [Ca], [Sr], and [Ba] are the values ​​divided by the molecular weight of the hydroxide, sulfate, or carbonate. It satisfies the range of 0.80 to 1.00. However, X means the highest value among [Ca], [Sr] or [Ba]. X / ([Ca] + [Sr] + [Ba]) may be, for example, 0.85 or more, 0.90 or more, or 0.95 or more.
[0072]
(3-2-3) Average particle size of hydroxide, sulfate or carbonate of Ca, Sr or Ba
The average particle size of the hydroxide, sulfate or carbonate of Ca, Sr or Ba is 1.0 to 10.0 μm in one embodiment. The average particle size may be, for example, 1.5 μm or more, 2.0 μm or more, or 2.5 μm or more, and may be, for example, 8.0 μm or less, 6.0 μm or less, or 5.0 μm or less. good. In one embodiment, it is preferable that the average particle size of the compound of the element having the highest content (that is, the content on a mass basis) among Ca, Sr or Ba is in the above range.
In one embodiment, among Ca hydroxides, Ca sulfates, Ca carbonates, Sr hydroxides, Sr sulfates, Sr carbonates, Ba hydroxides, Ba sulfates and Ba carbonates, it is contained in the quenching separator. The overall average particle size of the compound is within the above range.
[0073]
(3-2-4) Ratio of average particle size of Ca, Sr or Ba hydroxide, sulfate or carbonate to the median diameter of MgO
The ratio of the average particle size of the hydroxide, sulfate or carbonate of Ca, Sr or Ba to the median size of MgO (particle size corresponding to the median particle size distribution) is 0.8 to 2 in one embodiment. It is .5. The ratio may be, for example, 1.0 or more, 1.1 or more, and may be, for example, 2.3 or less, or 2.0 or less.
In one embodiment, Ca hydroxide, Ca sulfate, Ca carbonate, Sr hydroxide, Sr sulfate, Sr carbonate, Ba hydroxide, Ba sulfate and Ba carbonate with respect to the median diameter of MgO. Of these, the ratio of the average particle size of the compounds contained in the quenching separator is within the above range.
[0074]
The median diameter (ie, D 50 particle size) of MgO may be 1.50 μm or more, 1.80 μm or more, or 2.00 μm or more in one embodiment, and 5.00 μm or less, or 3. It may be 00 μm or less.
[0075]
(3-2-5) Ti compound, Y compound, La compound or Ce compound
The annealing separator contains at least one Ti compound, Y compound, La compound or Ce compound. The content of the Ti compound, the Y compound, the La compound or the Ce compound is 1.0 to 15.0% in total with respect to the content of MgO contained in the quenching separator. The amount may be, for example, 1.5% or more, 2.0% or more, or 2.5% or more, for example, 14.0% or less, 13.5% or less, or 13.0%. It may be as follows.
Here, the Ti compound, Y compound, La compound or Ce compound is preferably an oxide or a hydroxide.
[0076]
Explain the reason for these conditions. The interface between the primary coating of grain-oriented electrical steel sheet and the steel sheet has an inset structure. Specifically, in the vicinity of the interface between the primary coating and the steel sheet, the roots of the primary coating are stretched inside the steel sheet. The more the root of the primary coating penetrates into the steel sheet, the higher the adhesion of the primary coating to the steel sheet. Further, the more the roots of the primary coating are dispersed inside the steel sheet (the more stretched it is), the higher the adhesion of the primary coating to the steel sheet is.
[0077]
However, if the roots of the primary coating penetrate too deeply inside the steel sheet, or if the roots of the primary coating are excessively dispersed inside the steel sheet, the roots of the primary coating prevent secondary recrystallization in the Goss orientation and are in random orientation. Crystal grains increase in the surface layer. Further, the root of the primary coating becomes a factor that hinders the movement of the domain wall, and the magnetic characteristics deteriorate.
[0078]
The decrease in the adhesion of the primary coating in the conventional technique is due to the flattening of the interface structure between the steel sheet and the primary coating due to the aggregation of the roots of the primary coating. Therefore, the film adhesion has been improved by adding a compound such as Ce, La, or a compound of Ca, Sr, or Ba to the annealing separation agent.
[0079]
However, if a large amount of a compound such as Ce or La or a compound of Ca, Sr or Ba is added, the magnetic properties may deteriorate. Further, even if these compounds are added, the film adhesion may be different.
[0080] [0080]
As a result of diligent studies to improve the film adhesion, the present inventors have found that when a compound of Ca, Sr, or Ba is added in combination, the film formation is rather inhibited, and It was found that reducing the diameter of the Ca, Sr, or Ba compound is effective for improving the adhesion of the primary coating.
[0081]
In addition, MgO, which is the main component of the quenching separator, requires not only fine particles that contribute to the formation of the primary film, but also particles with a larger diameter that affect the shape of the steel plate after finish annealing. It is important to have a particle size distribution of, and in order to obtain the effect of improving the film adhesion by reducing the diameter of the Ca, Sr, or Ba compound, the median diameter of MgO and the Ca, Sr, or Ba compound are obtained. It turns out that the ratio of the average particle size of is important.
[0082]
Note that Patent Documents 4 and 5 do not describe or suggest that the diameter of the Ca, Sr, or Ba compound added to the annealing separator is reduced and the film adhesion is improved by controlling the particle size with MgO.
[0083]
Here, since the main component of the root of the primary coating is spinel (MgAl 2O 4), the Al emission intensity peak position in the plate thickness direction by the glow discharge emission analysis method (GDS method) is the position where the spinel exists, that is, the primary. Corresponds to the root depth of the capsule.
[0084]
Further, the element distribution at the Al emission intensity peak position corresponds to the element distribution at the root position of the primary coating, and the Al distribution state corresponds to the spinel dispersion state, that is, the distribution state of the roots of the primary coating.
[0085]
The present inventors investigated the structure of the primary coating of the directional electromagnetic steel plate obtained under the condition that the diameter of the compound of Ca, Sr, or Ba is different by the above method, and reduced the diameter of the compound of Ca, Sr, or Ba. We obtained a new finding that the total number density and circumference of Al oxides at the peak position of Al emission intensity increases, that is, the roots of the primary coating develop due to the reduction in the diameter of the Ca, Sr, or Ba compound. ..
[0086]
Ca, Sr, and Ba diffuse faster in SiO 2 than Mg. Therefore, when a compound of Ca, Sr, or Ba is added to the annealing separator, SiO 2 in the internal oxide layer reacts with these elements before agglomeration and coarsening, and a stable oxide with low oxygen potential in the inner layer. Is presumed to form.
[0087]
The formation of this stable oxide suppresses the flattening of the interface structure between the steel sheet and the primary coating, and the roots of the primary coating develop. The diameter of the Ca, Sr, or Ba compound is reduced and the particle size control with MgO, which is the main component of the annealing separator, is performed through an increase in the frequency of contact between SiO 2 on the surface of the steel sheet and the Ca, Sr, or Ba compound. It is presumed that it enhances the effect of forming the roots of the primary coating and contributes to the improvement of coating adhesion. When a compound of Ca, Sr, or Ba is added in combination, it is presumed that the state of adhesion to the steel sheet becomes non-uniform and the formation of the primary film is likely to be inhibited.
[0088]
That is, when the average particle size of the hydroxide, sulfate or carbonate of Ca, Sr, or Ba is less than 1.0 μm or more than 10 μm, the flattening of the interface structure between the steel sheet and the primary coating can be sufficiently suppressed. However, the roots of the primary capsule may not develop sufficiently. Therefore, it is desirable that the average particle size of the hydroxide, sulfate or carbonate of Ca, Sr, or Ba is 1.0 to 10.0 μm. In one aspect, Ca , Sr or Ba, the compound of the element having the highest content (that is, the content on a mass basis) preferably has an average particle size of 1.0 to 10.0 μm.
[0089]
The additive to the annealing separator also affects the inhibitor essential for the development of the Goss orientation by secondary recrystallization. Compounds of Ca, Sr, or Ba develop the roots of the primary coating through the formation of oxides on the surface. Changes in the formation behavior of oxides on the surface layer also have a large effect on the behavior of changes in inhibitors during finish annealing, and tend to destabilize magnetic properties.
[0090]
By compound addition with a Ti compound, Y compound, La compound or Ce compound, it is possible to achieve both improvement in film adhesion and excellent magnetic properties by reducing the diameter of the Ca, Sr, or Ba compound.
[0091]
If the total content of one or more of the hydroxides, sulfates or carbonates of Ca, Sr, or Ba is less than 0.5% of the content of MgO, the roots of the primary coating will not develop. The adhesion is inferior, and if it exceeds 10.0%, the formation of the primary film is suppressed, and as a result, the adhesion is also inferior.
[0092]
Further, when X / ([Ca] + [Sr] + [Ba]) (where X is the highest value among [Ca], [Sr], and [Ba]) is less than 0.80. The formation of the primary film becomes non-uniform, and the adhesion is also inferior.
[0093]
Further, if the total content of one or more of the Ti compound, Y compound, La compound or Ce compound is less than 1.0% with respect to the content of MgO, the roots of the primary coating do not develop and the adhesion is poor. Moreover, it is also inferior in magnetic properties, and when it exceeds 15.0%, the roots of the primary coating are formed, but the magnetic properties are inferior.
[0094]
MgO has a particle size distribution in which the content of particles having a particle size of 1.0 μm or less is 20 to 30% on a mass basis and the content of particles having a particle size of 10 μm or more is 2 to 5% on a mass basis. The ratio of the average particle size of the hydroxide, sulfate or carbonate of Ca, Sr or Ba to the diameter is 0.8 to 2.5.
[0095]
MgO, which is the main component of the annealing separator, requires fine particles that contribute to the formation of the primary film. If the content of particles having a particle size of 1.0 μm or less is less than 20%, the formation of the primary coating is insufficient, while if it exceeds 30%, the reactivity is excessively increased, and the shape of the steel sheet and workability at the time of coating are increased. Has an adverse effect on. Furthermore, it may adversely affect the magnetic properties and film adhesion. Further, when the number of coarse particles is small, the shape of the steel sheet is adversely affected, and when the amount is excessively large, the formation of the primary film is adversely affected. Therefore, the content of particles having a particle size of 10 μm or more is 2 to 5%.
[0096]
In MgO having such a particle size distribution, the median diameter is equal on the large side and the small side, and the average particle size of the hydroxide, sulfate or carbonate of Ca, Sr or Ba which is an additive to the quenching separator. Is equivalent, which leads to an increase in the frequency of contact between the surface of the steel plate after applying and baking the quenching separator and the compound of Ca, Sr, or Ba. The median diameter reflects the size of the representative particles in the particle group (ie, the particles at a cumulative volume of 50%), while the average particle size reflects the size of the entire particle present in the particle group. Since the contact frequency between the surface of the steel plate and the compound of Ca, Sr, or Ba can depend on the surface area of ​​the compound of Ca, Sr, or Ba, the control of the average particle size of the compound of Ca, Sr, or Ba is controlled. It may be advantageous to increase the contact frequency. The powder of the additive forms secondary particles that are aggregated with each other, and considering the particle size of the secondary particles, the hydroxide, sulfate or carbonate of Ca, Sr or Ba with respect to the median diameter of MgO. When the ratio of the average particle size to the average particle size is 0.8 to 2.5, the effect of forming the root of the primary film is enhanced, and the film adhesion is improved.
[0097]
Here, among the hydroxides, sulfates or carbonates of Ca, Sr, or Ba, the hydroxides of Sr, the hydroxides of Ba and the carbonates are not inferior to the effects of the invention, but are altered during handling. Since it is easy to handle, care must be taken in management, and there is a concern that productivity may be hindered. Therefore, unless there is a particular reason, there is no need to use them.
[0098]
The control of the particle size distribution in the quenching separator is not limited to, for example, MgO having a desired particle size distribution and a hydroxide, sulfate or carbonate (1) of Ca, Sr, or Ba having a desired particle size distribution. It may be realized by mixing a seed or a mixture of two or more kinds) and a liquid medium (for example, water) by a means known to those skilled in the art. In one embodiment, the values ​​disclosed in the present disclosure regarding the particle size distribution may be the values ​​of the particles used in the preparation of the annealing separator.
[0099]
(3-2-6) Manufacturing conditions for the finish annealing process
The finish annealing process is performed under the following conditions, for example. Perform the baking process before finish annealing. First, the surface of the steel sheet is coated with an annealed separator of an aqueous slurry. A steel sheet coated with an annealing separator on the surface is placed in a furnace kept at 400 to 1000 ° C. and held (annealing treatment). As a result, the annealing separator applied to the surface of the steel sheet dries. The holding time is, for example, 10 to 90 seconds.
[0100]
After the annealing separator is dried, finish annealing is performed. In the finish annealing, the annealing temperature is set to, for example, 1150 to 1250 ° C., and the base steel sheet (the steel sheet coated with the annealing separator and dried) is heated evenly. The soaking time is, for example, 15 to 30 hours. The atmosphere inside the furnace in finish annealing is a well-known atmosphere.
[0101]
In the grain-oriented electrical steel sheet manufactured by the above manufacturing process, a primary film containing Mg 2SiO 4 as a main component is formed. The Al peak position D Al exists in the range of 2.0 to 12.0 μm in the plate thickness direction from the surface of the primary coating. The total circumference of the Al oxide at the Al peak position D Al is 0.20 to 1.00 μm / μm 2. Further, the Al oxide number density ND is 0.02 to 0.20 / μm 2.
[0102]
By the decarburization annealing process and the finish annealing process, each element of the chemical composition of the hot-rolled steel sheet is removed from the components in the steel to some extent. In particular, S, Al, N and the like that function as inhibitors are significantly removed in the finish annealing step. Therefore, the element content in the chemical composition of the base steel sheet of the grain-oriented electrical steel sheet is lower than the chemical composition of the hot-rolled steel sheet as described above. If the above-mentioned manufacturing method is performed using the hot-rolled steel sheet having the above-mentioned chemical composition, a grain-oriented electrical steel sheet having the above-mentioned base steel sheet having the chemical composition can be manufactured.
[0103]
(4) Secondary film formation process
In an example of the method for manufacturing grain-oriented electrical steel sheets according to one aspect of the present invention, a secondary film forming step may be further performed after the finish annealing step. In the secondary film forming step, an insulating coating agent mainly composed of colloidal silica and phosphate is applied to the surface of the directional electromagnetic steel plate after the temperature of finish annealing is lowered, and then baked. As a result, a secondary coating, which is a tension insulating coating, is formed on the primary coating.
[0104]
(5) Magnetic domain subdivision processing process
The grain-oriented electrical steel sheet according to one aspect of the present invention may be further subjected to a magnetic domain subdivision treatment step after a finish annealing step or a secondary film forming step. In the magnetic domain subdivision processing step, the surface of the grain-oriented electrical steel sheet is irradiated with a laser beam having a magnetic domain subdivision effect, or a groove is formed on the surface. In this case, a grain-oriented electrical steel sheet having further excellent magnetic characteristics can be manufactured.
Example
[0105]
The present invention will be described in more detail by way of examples.
The molten steel having the chemical composition shown in Table 1 was manufactured in a vacuum melting furnace. A slab was manufactured using the manufactured molten steel. The slab was heated at 1350 ° C. for 1 hour, and the heated slab was hot-rolled to produce a hot-rolled steel sheet having a plate thickness of 2.3 mm. The chemical composition of the hot-rolled steel sheet was the same as that of the molten steel, as shown in Table 1. It is shown that "-" in Tables 1 and 2 is not contained.
[0106]
[table 1]

[0107]
[Table 2]

[0108]
The hot-rolled steel sheet was annealed at 1100 ° C. for 120 seconds, and then the hot-rolled steel sheet was pickled. The annealing treatment conditions and pickling conditions for the hot-rolled steel sheets were the same for all hot-rolled steel sheets. The hot-rolled steel sheet after pickling was cold-rolled to produce a cold-rolled steel sheet having a plate thickness of 0.22 mm. The cold-rolled ratio was 90.4% for all the cold-rolled steel sheets.
[0109]
Primary recrystallization annealing was performed on the cold-rolled steel sheet, which also served as decarburization annealing. The annealing temperature in the primary recrystallization annealing was 850 ° C. for all the cold-rolled steel sheets, and the holding time at the annealing temperature was 2 minutes.
[0110]
An aqueous slurry was applied to the cold-rolled steel sheet after primary recrystallization annealing. The aqueous slurry was prepared by mixing the annealing separator and water in a mixing ratio of 1: 7 on a mass basis. Table 2 summarizes the conditions for the annealing separator. The underline in Table 2 indicates that it is outside the scope of one aspect of the present invention. The content (%) shown in Table 2 is mass% with respect to the content of MgO contained in the annealing separator.
[0111]
In Table 2, the following five types (A) to (E) having different particle size distributions were used as the particles of MgO which is the main component of the annealing separator. Each particle size distribution is
(A) The content of particles having a particle size of 1.0 μm or less is 25% by mass, the content of particles having a particle size of 10 μm or more is 4% by mass, and the D 20 particle size is 0.9 μm with respect to the total content of MgO. D 30 particle size is 1.1 μm, D 50 particle size (median diameter) is 2.25 μm,
(B) The content of particles having a particle size of 1.0 μm or less is 10% by mass, the content of particles having a particle size of 10 μm or more is 4% by mass, and the D 20 particle size is 1.5 μm with respect to the total content of MgO. D 30 particle size is 1.8 μm, D 50 particle size (median diameter) is 4.56 μm,
(C) The content of particles having a particle size of 1.0 μm or less is 35% by mass, the content of particles having a particle size of 10 μm or more is 4% by mass, and the D 20 particle size is 0.5 μm with respect to the total content of MgO. D 30 particle size is 0.7 μm, D 50 particle size (median diameter) is 1.81 μm,
(D) The content of particles having a particle size of 1.0 μm or less is 25% by mass, the content of particles having a particle size of 10 μm or more is 1% by mass, and the particle size of D 20 is 0.9 μm, based on the total content of MgO. D 30 particle size is 1.1 μm, D 50 particle size (median diameter) is 2.08 μm,
(E) The content of particles having a particle size of 1.0 μm or less is 25% by mass, the content of particles having a particle size of 10 μm or more is 8% by mass, and the D 20 particle size is 0.9 μm with respect to the total content of MgO. D 30 particle size is 1.1 μm, D 50 particle size (median diameter) is 4.00 μm,
Is.
[0112]
[Table 3]

[0113]
[Table 4]

[0114]
The cold-rolled steel sheet coated with the aqueous slurry was baked at 900 ° C. for 10 seconds at any test number to dry the aqueous slurry. Here, the amount of the annealing separator applied to the dried steel sheet was 5 g / m 2 per side.
After baking, finish annealing was performed. In the finish annealing treatment, the test numbers were kept at 1200 ° C. for 20 hours. Through the above manufacturing process, a grain-oriented electrical steel sheet having a base steel sheet and a primary coating was manufactured.
[0115]
[Chemical composition analysis of the base steel sheet of grain-oriented electrical steel sheet]
The primary film of the manufactured grain-oriented electrical steel sheets of test numbers 1 to 48 was removed with sulfuric acid and nitric acid to obtain a base steel sheet. The chemical composition of the base steel sheet was determined by the spark discharge emission analysis method and the atomic absorption spectroscopy. The obtained chemical composition is shown in Table 3. Here, in each of the test numbers 1 to 48, the total content of Sn, Sb, Cu, Bi, Te, and Pb was 0.03% or less. The underline in Table 3 indicates that it is outside the scope of one aspect of the present invention.
[0116]
[Table 5]

[0117]
[Table 6]

[0118]
[Evaluation test]
[Al peak position D Al measurement test]
For the grain-oriented electrical steel sheet of each test number, the Al peak position D Al was determined by the following measurement method. Specifically, elemental analysis using the GDS method was performed on the surface layer of the grain-oriented electrical steel sheet under the conditions described later, and the depth from the surface of the grain-oriented electrical steel sheet was performed in an arbitrarily selected observation region of 36 μm × 50 μm. Elemental analysis was performed in the range of 100 μm in the direction (surface layer), and Al contained at each depth position in the surface layer was identified. The emission intensity of the identified Al was plotted in the depth direction from the surface.
(GDS elemental analysis conditions)
Equipment: High frequency gloss -Discharge emission spectrometer (manufactured by RIGAKU, model number "GDA750"
Ar gas pressure: 3 hPa
Anode diameter: 6 mmφ
Power: 20W
Measurement time: 30 to 100 seconds
The Al peak position D Al was determined based on the plotted Al emission intensity graph. The obtained Al peak position D Al is shown in Table 3.
[0119]
[Al oxide circumference total measurement test]
For the total circumference of the Al oxide, glow discharge is performed to the Al peak position D Al by the glow discharge emission analyzer under the same conditions as in the above [Al peak position D Al measurement test], and the Glow discharge is performed at the Al peak position D Al. Elemental analysis was performed on an arbitrary 36 μm × 50 μm region (observation region) of the discharge marks by an energy dispersion type X-ray spectroscope (EDS) under the conditions described below. Identify the Al oxide in the observation region (the region where the intensity of the characteristic X-ray of O of 50% or more is analyzed with respect to the maximum intensity of the characteristic X-ray of O in the observation region is specified as the oxide and specified. In the region of the specified oxide, the region where the intensity of the specific X-ray of Al of 30% or more is analyzed with respect to the maximum intensity of the specific X-ray of Al is specified as the Al oxide), and the specified Al oxidation. The total circumference of the object (μm / μm 2) was calculated.
(EDS elemental analysis conditions)
Device: Scanning electron microscope (manufactured by JEOL Ltd., model number "JSM-6610LA")
EDS detector: JED-2300
Acceleration voltage: 15kV
Irradiation current: 11.32057nA
Input count: 30,000 cps or more
Measurement time: 1000 seconds or more
Table 3 shows the total circumference of the obtained Al oxides.
[0120]
[Al oxide number density ND measurement test]
For the grain-oriented electrical steel sheet of each test number, the Al oxide number density ND (pieces / μm 2) at the Al peak position D Al was determined by the following method. Under the same conditions as in the above [Al peak position D Al measurement test], glow discharge was performed to the Al peak position D Al by the glow discharge emission analyzer. Energy dispersive X-ray spectroscopy for an arbitrary 36 μm × 50 μm region (observation region) at the Al peak position D Al under the same conditions as in the above [Al oxide circumference total length measurement test]. Elemental analysis was performed using a vessel (EDS). Identify the Al oxide in the observation region (the region where the intensity of the characteristic X-ray of O of 50% or more is analyzed with respect to the maximum intensity of the characteristic X-ray of O in the observation region is specified as the oxide and specified. In the region of the specified oxide, the region where the intensity of the specific X-ray of Al of 30% or more is analyzed with respect to the maximum intensity of the specific X-ray of Al is specified as the Al oxide), and the specified Al oxidation. The number of objects was counted, and the number of Al oxides density ND (pieces / μm 2) was obtained as ND = the number of specified Al oxides / the area of ​​the observation region. The obtained Al oxide number density ND is shown in Table 3.
[0121]
[Magnetic characterization test]
The magnetic properties of the grain-oriented electrical steel sheets of each test number were evaluated by the following method. Specifically, a sample having a length of 300 mm and a width of 60 mm in the rolling direction was taken from the grain-oriented electrical steel sheet of each test number. A magnetic flux density B8 was obtained by applying a magnetic field of 800 A / m to the sample using a single-plate magnetic measuring instrument. Table 3 shows the test results. In Table 3, when the magnetic flux density is 1.92T or more, it is "excellent", when it is 1.90T to less than 1.92T, it is "good", when it is 1.88T to less than 1.90T, it is "possible", and when it is less than 1.88T, it is "bad". Shown in. If the magnetic flux density is 1.90T or more (that is, if it is "good" in Table 3), the magnetic characteristics are excellent, and if it is 1.92T or more (that is, if it is "excellent" in Table 3), it is particularly magnetic. It was judged that the characteristics were excellent.
[0122]
[Adhesion evaluation test]
The adhesion of the primary coating of grain-oriented electrical steel sheets of each test number was evaluated by the following method. Specifically, a sample having a length of 60 mm and a width of 15 mm in the rolling direction was taken from the grain-oriented electrical steel sheet of each test number. A bending test was performed on the sample with a curvature of 10 mm. The bending test was performed by using a cylindrical mandrel bending tester (manufactured by TP Giken Co., Ltd.) and installing it on the sample so that the axial direction of the cylinder coincided with the width direction of the sample. The surface of the sample after the bending test was observed, and the total area of ​​the area where the primary coating remained without peeling was determined. Specifically, the sample after the bending test was returned to a flat state, and the surface appearance was taken in by a scanner (manufactured by EPSON, model number "ES-H7200"). The obtained image was binarized with software built into the scanner, and the area of ​​the residual primary coating on the sample surface was measured. Then, the primary film residual rate was determined by assuming that the primary film residual rate = the total area of ​​the region where the primary film remains without peeling / the area of ​​the bent portion in the sample × 100.
Table 3 shows the test results. A primary film residual rate of 90% or more was indicated as "good", 70 to less than 90% was indicated as "possible", and less than 70% was indicated as "poor". If the residual ratio of the primary coating is 90% or more (that is, if it is "good" in Table 3), it is judged that the adhesion of the primary coating to the base steel sheet is excellent.
[0123]
[Test results]
Table 3 shows the test results.
In the examples of the present invention of Test Nos. 1 to 21, the chemical composition of the annealing separator satisfies the chemical composition defined in one aspect of the present invention. Specifically, as the particle size distribution of MgO of the annealing separator, the content of particles having a particle size of 1.0 μm or less is 20 to 30%, the content of particles having a particle size of 10 μm or more is 2 to 5%, and Ca. , Sr or Ba, the content of hydroxide, sulfate or carbonate is in the range of 0.5 to 10.0% in total with respect to the content of MgO, and X / ([Ca] + [ Sr] + [Ba]) satisfies the range of 0.80 to 1.00, and the average particle size of the hydroxide, sulfate or carbonate of Ca, Sr or Ba is 1.0 to 10.0 μm. , The ratio of the average particle size of the hydroxide, sulfate or carbonate of Ca, Sr or Ba to the median diameter of MgO is 0.8 to 2.5, and further, Ti compound, Y compound, La compound or Ce. The content of the compound is 1.0 to 15.0% in total with respect to the content of MgO.
Therefore, the peak position of the Al emission intensity obtained when elemental analysis by the glow discharge emission analysis method is performed from the surface of the primary coating in the plate thickness direction of the directional electromagnetic steel plate is 2 in the plate thickness direction from the surface of the primary coating. It exists in the range of 0.0 to 12.0 μm, the total circumference of Al oxides at the peak position of Al emission intensity is 0.20 to 1.00 μm / μm 2, and the number density of Al oxides. Was 0.02 to 0.20 / μm 2.
As a result, in test numbers 1 to 21, the primary coating showed excellent adhesion and excellent magnetic properties. Test numbers 2 to 21 in which the hot-rolled steel sheet contained Sb, Sn, Cu, Bi, Te, and Pb were particularly excellent in magnetic properties as compared with test number 1.
[0124]
On the other hand, the comparative examples of Test Nos. 22 to 48 did not satisfy the conditions of one aspect of the present invention, and therefore, one or both of the adhesiveness and the magnetic properties of the primary coating were not good.
[0125]
In test numbers 22 to 24, the total content of Ca, Sr, and Ba compounds exceeded the upper limit specified in one aspect of the present invention. Therefore, the sum of the circumferences of the Al peak position D Al and the Al oxide was low, and as a result, the adhesion of the primary coating was low.
[0126]
In test numbers 25 to 27, the total content of Ca, Sr, and Ba compounds was below the lower limit specified in one aspect of the present invention. Therefore, the total circumference of the Al oxides and the number density of the Al oxides are low, and as a result, the adhesion of the primary film is low. In addition, the magnetic characteristics were also inferior.
[0127]
In test number 28, the total content of the Ti compound, the Y compound, the La compound, and the Ce compound was below the lower limit specified in one aspect of the present invention. Therefore, the Al peak position D Al, the total circumference of the Al oxides, and the number density of the Al oxides were low, and as a result, the adhesion of the primary coating was low.
[0128]
In test number 29, X / ([Ca] + [Sr] + [Ba]) is below the lower limit defined in one embodiment of the present invention, the Al peak position D Al, the sum of the circumferences of the Al oxide, and Al oxidation. The number density of objects was low. As a result, the adhesion of the primary coating was low. In addition, the magnetic characteristics were also inferior.
[0129]
In test number 30, the average particle size of the Sr compound exceeded the upper limit specified in one aspect of the present invention, and the ratio of MgO to the median diameter also exceeded the upper limit specified in one aspect of the present invention. As a result, the total circumference of the Al oxide was low, and the adhesion of the primary coating was low.
[0130]
In test number 31, the total content of Ti compound, Y compound, La compound, and Ce compound exceeded the upper limit specified in one aspect of the present invention. Therefore, the Al peak position D Al, the total circumference of Al oxides, and the number density of Al oxides are higher than the upper limit of one aspect of the present invention, and as a result, the magnetic properties are inferior.
[0131]
In test number 32, the average particle size of the Ca compound exceeded the upper limit specified in one aspect of the present invention, and the ratio of MgO to the median diameter also exceeded the upper limit specified in one aspect of the present invention. Further, the total content of the Ti compound, the Y compound, the La compound and the Ce compound exceeded the upper limit specified in one aspect of the present invention. Therefore, the Al peak position D Al, the sum of the circumferences of the Al oxides, and the number density of the Al oxides were higher than the upper limit of one aspect of the present invention, and the magnetic properties were inferior.
[0132]
In test number 33, the average particle size of the Sr compound was below the lower limit specified in one aspect of the present invention, and the ratio of MgO to the median diameter was also below the lower limit specified in one aspect of the present invention. Therefore, the total circumference of the Al oxide and the number density of the Al oxide are lower than the lower limit of one aspect of the present invention, and the adhesion is inferior. In addition, the magnetic characteristics were also inferior.
[0133]
In test numbers 34 to 36, the particles having a particle size of 1.0 μm or less in the particle size distribution of MgO were below the lower limit specified in one aspect of the present invention. In Test No. 35, the average particle size of the Ca compound further exceeded the upper limit specified in one aspect of the present invention, and the ratio of MgO to the median diameter also exceeded the upper limit specified in one aspect of the present invention. Further, in Test No. 36, the average particle size of the Sr compound was lower than the lower limit specified in one aspect of the present invention, and the ratio of MgO to the median diameter was also lower than the lower limit specified in one aspect of the present invention. Therefore, in test numbers 34 to 36, the Al peak position D Al, the total circumference of the Al oxides, and the number density of the Al oxides were below the lower limit defined in one aspect of the present invention, and the adhesion was inferior.
[0134]
In test numbers 37 to 39, particles having a particle size of 1.0 μm or less exceeded the upper limit specified in one aspect of the present invention in the particle size distribution of MgO. In Test No. 38, the average particle size of the Ca compound further exceeded the upper limit specified in one aspect of the present invention, and the ratio of MgO to the median diameter also exceeded the upper limit specified in the present invention. Further, in Test No. 39, the average particle size of the Sr compound was lower than the lower limit specified in one aspect of the present invention, and the ratio of MgO to the median diameter was also lower than the lower limit specified in one aspect of the present invention. Therefore, in test numbers 37 to 39, the Al peak position D Al, the total circumference of Al oxides, and the number density of Al oxides were lower than the lower limit defined in one aspect of the present invention, and the adhesion was inferior.
[0135]
In test numbers 40 to 42, in the particle size distribution of MgO, particles having a particle size of 10 μm or more were below the lower limit specified in one aspect of the present invention. In Test No. 41, the average particle size of the Ca compound further exceeded the upper limit specified in one aspect of the present invention, and the ratio of MgO to the median diameter also exceeded the upper limit specified in one aspect of the present invention. Further, in Test No. 42, the average particle size of the Sr compound was lower than the lower limit specified in one aspect of the present invention, and the ratio of MgO to the median diameter was also lower than the lower limit specified in one aspect of the present invention. Therefore, in test numbers 40 to 42, the Al peak position D Al, the total circumference of the Al oxides, and the number density of the Al oxides were lower than the lower limit defined in one aspect of the present invention, and the adhesion was inferior.
[0136]
In test numbers 43 to 45, in the particle size distribution of MgO, particles having a particle size of 10 μm or more exceeded the upper limit specified in one aspect of the present invention. In Test No. 44, the average particle size of the Ca compound further exceeded the upper limit specified in one aspect of the present invention, and the ratio of MgO to the median diameter also exceeded the upper limit specified in one aspect of the present invention. Further, in test number 45, the average particle size of the Sr compound is below the lower limit defined in one aspect of the present invention. The ratio of MgO to the median diameter was also below the lower limit specified in one aspect of the present invention. Therefore, in test numbers 43 to 45, the Al peak position D Al, the total circumference of Al oxides, and the number density of Al oxides were lower than the lower limit defined in one aspect of the present invention, and the adhesion was inferior.
[0137]
Test numbers 46 to 48 differ only in the ratio of the average particle size of Ca, Sr, or Ba to the median diameter of MgO for each of test numbers 5, 15, and 21, respectively. In test number 46, the ratio of the average particle size of Ca to the median diameter of MgO, in test number 47, the ratio of the average particle size of Sr to the median diameter of MgO, and in test number 48, the average particle size of Ba and the median diameter of MgO. The ratio to the median diameter exceeded the upper limit specified in one aspect of the present invention. Therefore, in test numbers 46 to 48, the Al peak position D Al, the total circumference of Al oxides, and the number density of Al oxides were lower than the lower limit defined in one aspect of the present invention, and the adhesion was inferior.
The scope of the claims
[Claim 1]
In mass%, C: 0.005% or less, Si: 2.5 to 4.5%, Mn: 0.050 to 1.000%, total of S and Se: 0.005% or less, sol. A base steel sheet containing Al: 0.005% or less and N: 0.005% or less and having a chemical composition in which the balance is Fe and impurities, and Mg 2SiO 4 formed on the surface of the base steel sheet. A grain-oriented electrical steel sheet having a primary coating contained as a main component.
The peak position of the Al emission intensity obtained when elemental analysis by the glow discharge emission spectrometry method is performed from the surface of the primary coating in the plate thickness direction of the directional electromagnetic steel plate is from the surface of the primary coating in the plate thickness direction. It exists in the range of 2.0 to 12.0 μm and
The total circumference of the Al oxide at the peak position of the Al emission intensity is 0.20 to 1.00 μm / μm 2, and
A grain-oriented electrical steel sheet having a density of Al oxides of 0.02 to 0.20 / μm 2.
[Claim 2]
By mass%, C: 0.100% or less, Si: 2.5 to 4.5%, Mn: 0.050 to 1.000%, total of S and Se: 0.002 to 0.050%, sol .. Cold-rolled steel sheet containing Al: 0.005 to 0.050% and N: 0.001 to 0.030% and having a chemical composition in which the balance is Fe and impurities at a cold rolling ratio of 80% or more. The cold rolling process of rolling to produce cold-rolled steel sheets,
The decarburization annealing process of decarburizing and annealing the cold-rolled steel sheet,
An aqueous slurry containing an annealing separator containing MgO as a main component is applied to the surface of the cold-rolled steel sheet after decarburization and annealing, and the aqueous slurry on the surface of the cold-rolled steel sheet is dried in a furnace at 400 to 1000 ° C. After that, the cold-rolled steel sheet includes a finish annealing step of performing finish annealing.
The quenching separator contains the MgO, one or more hydroxides, sulfates or carbonates of Ca, Sr or Ba, and one or more Ti compounds, Y compounds, La compounds or Ce compounds.
The particle size distribution of MgO is such that the content of particles having a particle size of 1.0 μm or less is 20 to 30% by mass and the content of particles having a particle size of 10 μm or more is 2 to 5% by mass with respect to the content of MgO. % And
The Ca, Sr or Ba hydroxide, sulfate or carbonate is contained in the range of 0.5 to 10.0% by mass in total with respect to the content of MgO, and is contained with respect to the content of MgO. The value obtained by dividing the content of the hydroxide, sulfate or carbonate of Ca by the molecular weight of the hydroxide, sulfate or carbonate of Ca, the hydroxide or sulfate of Sr with respect to the content of MgO. Alternatively, the content of the hydroxide, sulfate or carbonate of Ba is divided by the molecular weight of the hydroxide, sulfate or carbonate of Sr, and the content of the hydroxide, sulfate or carbonate of Ba with respect to the content of MgO. When the value divided by the molecular weight of the hydroxide, sulfate or carbonate of Ba is [Ca], [Sr], and [Ba], respectively, X / ([Ca] + [Sr] + [Ba]) Satisfies the range of 0.80 to 1.00,
The average particle size of the hydroxide, sulfate or carbonate of Ca, Sr or Ba is 1.0 to 10.0 μm, and the hydroxide, sulfate of Ca, Sr or Ba with respect to the median diameter of MgO. The average particle size ratio of salt or carbonate is 0.8-2.5 and
The production of the directional electromagnetic steel plate according to claim 1, wherein the content of the Ti compound, the Y compound, the La compound or the Ce compound is 1.0 to 15.0% by mass in total with respect to the content of the MgO. Method.
However, X means the highest value among [Ca], [Sr] or [Ba].
[Claim 3]
Claimed that the average particle size of the hydroxide, sulfate or carbonate of the element having the highest content among the hydroxide, sulfate or carbonate of Ca, Sr or Ba is 1.0 to 10.0 μm. Item 2. The method for manufacturing a directional electromagnetic steel plate according to Item 2.
[Claim 4]
The method for manufacturing a grain-oriented electrical steel sheet according to claim 2 or 3, wherein the hot-rolled steel sheet contains one or more of Sb, Sn or Cu in a total amount of 0.30% by mass or less.
[Claim 5]
The method for manufacturing a grain-oriented electrical steel sheet according to any one of claims 2 to 4, wherein the hot-rolled steel sheet contains one or more of Bi, Te or Pb in a total amount of 0.0300% by mass or less.
[Claim 6]
An annealing separator containing MgO as the main component,
It contains one or more hydroxides, sulfates or carbonates of Ca, Sr or Ba, and one or more Ti compounds, Y compounds, La compounds or Ce compounds.
The particle size distribution of MgO is such that the content of particles having a particle size of 1.0 μm or less is 20 to 30% by mass and the content of particles having a particle size of 10 μm or more is 2 to 5% by mass with respect to the content of MgO. % And
The Ca, Sr or Ba hydroxide, sulfate or carbonate is contained in the range of 0.5 to 10.0% by mass in total with respect to the content of MgO, and is contained with respect to the content of MgO. The value obtained by dividing the content of the hydroxide, sulfate or carbonate of Ca by the molecular weight of the hydroxide, sulfate or carbonate of Ca, the hydroxide or sulfate of Sr with respect to the content of MgO. Alternatively, the content of the hydroxide, sulfate or carbonate of Ba is divided by the molecular weight of the hydroxide, sulfate or carbonate of Sr, and the content of the hydroxide, sulfate or carbonate of Ba with respect to the content of MgO. When the value divided by the molecular weight of the hydroxide, sulfate or carbonate of Ba is [Ca], [Sr], and [Ba], respectively, X / ([Ca] + [Sr] + [Ba]) Satisfies the range of 0.80 to 1.00,
The average particle size of the hydroxide, sulfate or carbonate of Ca, Sr or Ba is 1.0 to 10.0 μm, and the hydroxide, sulfate of Ca, Sr or Ba with respect to the median diameter of MgO. The average particle size ratio of salt or carbonate is 0.8-2.5 and
The content of the Ti compound, Y compound, La compound or Ce compound is 1.0 to 15.0% by mass in total with respect to the content of MgO.
However, X means the highest value among [Ca], [Sr] or [Ba].
[Claim 7]
Claimed that the average particle size of the hydroxide, sulfate or carbonate of the element having the highest content among the hydroxide, sulfate or carbonate of Ca, Sr or Ba is 1.0 to 10.0 μm. Item 6. The quenching separator according to Item 6.