The present invention relates to grain-oriented electrical steel sheets, a method for manufacturing grain-oriented electrical steel sheets, and an annealing separator used for manufacturing grain-oriented electrical steel sheets.
Background technology
[0002]
The grain-oriented electrical steel sheet is a steel sheet in which Si is contained in an amount of about 0.5 to 7% by mass and the crystal orientation is integrated in the {110} <001> orientation (goss orientation). A catastrophic grain growth phenomenon called secondary recrystallization is used to control the crystal orientation.
[0003]
The manufacturing method of grain-oriented electrical steel sheet is as follows. The slab is heated and hot-rolled to produce a hot-rolled steel sheet. Anneal the hot-rolled steel sheet as needed. Pickle the hot-rolled steel sheet. A cold-rolled steel sheet is manufactured by cold-rolling the hot-rolled steel sheet after pickling at a cold-rolling ratio of 80% or more. Decarburization annealing is performed on the cold-rolled steel sheet to develop primary recrystallization. Finish annealing is performed on the cold-rolled steel sheet after decarburization annealing to develop secondary recrystallization. Through the above steps, grain-oriented electrical steel sheets are manufactured.
[0004]
After the above-mentioned decarburization annealing and before finish annealing, an aqueous slurry containing an annealing separator containing MgO as a main component is applied on the surface of the cold-rolled steel sheet and dried. After winding the cold-rolled steel sheet with the annealing separator dried on a coil, finish annealing is performed. During finish annealing, MgO in the annealing separator reacts with SiO 2 in the internal oxide layer formed on the surface of the cold-rolled steel sheet during decarburization annealing, and contains forsterite (Mg 2SiO 4) as the main component. A primary coating is formed on the surface. 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 the insulating coating have a smaller coefficient of thermal expansion than the steel sheet. 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.
[0005]
On the other hand, it is also effective to increase the magnetic flux density to reduce the hysteresis loss in order to reduce the iron loss of the grain-oriented electrical steel sheet.
[0006]
In order to increase the magnetic flux density of the grain-oriented electrical steel sheet, it is effective to integrate the crystal orientation of the grain steel sheet in the Goss orientation. Techniques for enhancing the accumulation in the Goss direction are proposed in Patent Documents 1 to 3. In these patent documents, the steel sheet contains a magnetic property improving element (Sn, Sb, Bi, Te, Pb, Se, etc.) that enhances the action of the inhibitor. As a result, the accumulation in the Goss direction is increased, and the magnetic flux density can be increased.
[0007]
However, when the element for improving magnetic properties is contained, a part of the primary coating is aggregated, and the interface between the steel sheet and the primary coating tends to be flattened. In this case, the adhesion of the primary coating to the steel sheet is reduced.
[0008]
Patent Documents 4, 5, 6 and 7 disclose techniques for improving the adhesion of the primary coating to a steel sheet.
[0009]
In Patent Document 4, the slab contains 0.001 to 0.1% of Ce, and a primary film containing 0.01 to 1000 mg / m 2 of Ce is formed on the surface of the steel sheet. In Patent Document 5, in a grain-oriented electrical steel sheet containing Si: 1.8 to 7% and having a primary film containing forsterite as a main component on the surface, Ce is 0.001 per surface in the primary film in terms of basis weight. It contains ~ 1000 mg / m 2.
[0010]
In Patent Document 6, 0.1 to 10% of a rare earth metal element compound and one or more alkaline earth metal compounds selected from Ca, Sr or Ba are 0 in a quenching separator containing MgO as a main component. By containing a compound containing 1 to 10% and 0.01 to 5% of a sulfur compound, one or more alkaline earth metal compounds selected from Ca, Sr or Ba can be contained in the primary coating. It forms a primary film characterized by containing rare earth elements.
[0011]
Patent Document 7 is characterized by containing a compound containing one or more elements selected from Ca, Sr or Ba, a rare earth metal element compound of 0.1 to 1.0%, and sulfur. Form a primary coating.
Prior art literature
Patent documents
[0012]
Patent Document 1: Japanese Patent Application Laid-Open No. 6-88171
Patent Document 2: Japanese Patent Application Laid-Open No. 8-269552
Patent Document 3: Japanese Unexamined Patent Publication No. 2005-290446
Patent Document 4: Japanese Unexamined Patent Publication No. 2008-127634
Patent Document 5: Japanese Unexamined Patent Publication No. 2012-214902
Patent Document 6: International Publication No. 2008/062853
Patent Document 7: Japanese Unexamined Patent Publication No. 2009-270129
Outline of the invention
Problems to be solved by the invention
[0013]
However, when the annealing separator contains a rare earth element compound such as Y, La, or Ce to form a primary film containing Y, La, or Ce, the magnetic properties may deteriorate. Further, when preparing the quenching separator, if the number density of particles in the raw material powder of the rare earth element compound such as Y, La, Ce or the additive such as Ca, Sr, Ba is insufficient, the primary coating is formed. Areas of underdevelopment may occur, resulting in poor adhesion. Further, the grain-oriented electrical steel sheet may be required to have rust resistance, but the above-mentioned Patent Documents 1 to 4 do not describe the rust resistance.
[0014]
An object of the present invention is to obtain a grain-oriented electrical steel sheet, a method for manufacturing a grain-oriented electrical steel sheet, and a grain-oriented electrical steel sheet, which have excellent magnetic properties, excellent adhesion of a primary coating to a base steel sheet, and excellent rust resistance. It is to provide an annealed separator used in the production.
Means to solve problems
[0015]
The grain-oriented electrical steel sheet according to the present invention comprises a group consisting of C: 0.005% or less, Si: 2.5 to 4.5%, Mn: 0.02 to 0.2%, S and Se in mass%. One or more elements to be selected: 0.005% or less in total, sol. It contains Al: 0.01% or less and N: 0.01% or less, and the balance is a base steel plate having a chemical composition consisting of Fe and impurities, and is formed on the surface of the base steel plate, and is Mg 2SiO. A primary coating containing 4 as a main component is provided, and 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 determined. It is an Al oxide located within the range of 2.4 to 12.0 μm in the plate thickness direction from the surface of the primary coating, and is an Al oxide at the peak position of Al emission intensity, and has an area-based circle equivalent diameter of 0.2 μm or more. The number density of the Al oxides is 0.03 to 0.18 μm 2, and the cross-sectional area is 0. Of the plurality of Al oxides in the observation region of 30 μm × 50 μm at the peak position of the Al emission intensity. The total cross-sectional area of ​​the specific Al oxide of 4 to 10.0 μm 2 is 75.0% or more of the total cross-sectional area of ​​all Al oxides in the observation region.
[0016]
The method for manufacturing grain-oriented electrical steel sheets according to the present invention is from C: 0.1% or less, Si: 2.5 to 4.5%, Mn: 0.02 to 0.2%, S and Se in mass%. One or more elements selected from the group: 0.005-0.07% in total, sol. Cold at a cold rolling ratio of 80% or more with respect to a hot-rolled steel sheet containing Al: 0.005 to 0.05% and N: 0.001 to 0.030% and the balance being Fe and impurities. A process of manufacturing a cold-rolled steel sheet to be a base steel sheet by rolling, a process of performing decarburization annealing on the cold-rolled steel sheet, and a shrinking separator on the surface of the cold-rolled steel sheet after decarburization annealing. A step of applying the contained aqueous slurry and drying the aqueous slurry on the surface of the cold-rolled steel sheet in a furnace at 400 to 1000 ° C., and a step of performing finish annealing on the cold-rolled steel sheet after the aqueous slurry has been dried. And prepare. The quenching separator includes at least one metal compound selected from the group consisting of MgO, Y, La, and Ce, and at least one metal compound selected from the group consisting of Ti, Zr, and Hf. And one or more metal compounds selected from the group consisting of Ca, Sr, and Ba, and when the MgO content in the annealing separator is 100% by mass, the Y, La, The total content in terms of oxide of the compound selected from the group consisting of Ce is 0.8 to 8.0%, and the equivalent of the metal compound selected from the group consisting of Ti, Zr, and Hf is converted into oxide. The total content is 0.5 to 9.0%, and the total content in terms of sulfate of the metal compound selected from the group consisting of Ca, Sr, and Ba is 0.5 to 8.0%. The average particle size of the metal compound selected from the group consisting of Ca, Sr, and Ba is 12 μm or less, and the average particle size of the metal compound selected from the group consisting of Ca, Sr, and Ba is the Y. The ratio of the metal compound selected from the group consisting of La and Ce to the average particle size is 0.1 to 3.0, and the oxidation of the metal compound selected from the group consisting of Y, La and Ce. The total of the total content in terms of material and the total content in terms of oxide of the metal compound selected from the group consisting of Ti, Zr, and Hf is 2.0 to 12.5%, and the quenching separator. The ratio of the total number of Y, La, and Ce atoms to the total number of Ti, Zr, and Hf atoms contained in is 0.18 to 4.0, and further comprises the above Y, La, and Ce. It is a particle of a metal compound selected from the group, and has a number density of 0.1 μm or more with a volume-based equivalent sphere diameter of 2 billion pieces / g or more, and further, a group consisting of Ti, Zr, and Hf. Among the metal compounds selected from the above, the number density of particles having a volume-based equivalent sphere diameter of 0.1 μm or more is 2 billion / g or more, and further, from the group consisting of Ca, Sr, and Ba. The selected metal compound has a volume-based sphere-equivalent diameter of 0.1 μm or more and a particle number density of 2 billion / g or more.
[0017]
The annealing separator used in the production of the directional electromagnetic steel sheet according to the present invention contains at least one metal compound selected from the group consisting of MgO, Y, La, and Ce, and a group consisting of Ti, Zr, and Hf. Contains at least one metal compound selected from the above and one or more metal compounds selected from the group consisting of Ca, Sr, and Ba, and the MgO content in the annealing separator is mass%. The total content of the compounds selected from the group consisting of Y, La, and Ce in terms of oxide is 0.8 to 8.0%, and the group consisting of Ti, Zr, and Hf. The total oxide content of the metal compound selected from the above is 0.5 to 9.0%, and the total content of the metal compound selected from the group consisting of Ca, Sr, and Ba is the sulfate equivalent. The amount is 0.5-8.0%. The average particle size of the metal compound selected from the group consisting of Ca, Sr and Ba is 12 μm or less, and the average particle size of the metal compound selected from the group consisting of Ca, Sr and Ba is Y. The ratio of the metal compound selected from the group consisting of La and Ce to the average particle size is 0.1 to 3.0, and the oxide conversion of the metal compound selected from the group consisting of Y, La and Ce. The total content of the above and the total content of the metal compound selected from the group consisting of Ti, Zr, and Hf in terms of oxide is 2.0 to 12.5%. The ratio of the total number of Y, La, and Ce atoms to the total number of Ti, Zr, and Hf atoms contained in the quenching separator is 0.18 to 4.0, and further, the Y, La, Particles of a metal compound selected from the group consisting of Ce, the number density of particles having a volume-based equivalent sphere diameter of 0.1 μm or more is 2 billion / g or more, and further, the Ti, Zr. , Hf, particles of a metal compound selected from the group consisting of, Hf, having a volume-based sphere equivalent diameter of 0.1 μm or more, and having a number density of 2 billion particles / g or more. It is a particle of a metal compound selected from the group consisting of Sr and Ba, and the number density of particles having a volume-based equivalent sphere diameter of 0.1 μm or more and a particle size of 0.1 μm or more is 2 billion / g or more.
The invention's effect
[0018]
The grain-oriented electrical steel sheet according to the present invention has excellent magnetic properties and excellent adhesion to the base steel sheet of the primary coating. The manufacturing method according to the present invention can manufacture the above-mentioned grain-oriented electrical steel sheet. The annealing separator according to the present invention is applied to the above-mentioned manufacturing method, whereby a grain-oriented electrical steel sheet can be manufactured.
Embodiment for carrying out the invention
[0019]
The present inventors investigated the magnetic properties of grain-oriented electrical steel sheets containing elements for improving magnetic properties, and the adhesion of primary coatings formed by containing Y compounds, La compounds, and Ce compounds in a quenching separator. Study was carried out. As a result, the inventor of the present invention Et al. Obtained the following findings.
[0020]
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.
[0021]
On the other hand, if the roots of the primary coating penetrate too deeply into the steel sheet, the roots of the primary coating prevent secondary recrystallization in the Goss orientation. Therefore, crystal grains with random orientation 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. Similarly, if the roots of the primary coating are excessively dispersed inside the steel sheet, the roots of the primary coating prevent the secondary recrystallization in the Goss orientation, so that the crystal grains in the random orientation 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.
[0022]
Based on the above findings, the present inventors further investigated the state of the root of the primary coating, the magnetic properties of the grain-oriented electrical steel sheet, and the adhesion of the primary coating.
[0023]
When the annealing separator contains Y, La, and Ce compounds to form a primary film, the magnetic properties deteriorate as described above. It is considered that this is because the roots of the primary coating penetrate too deeply into the inside of the steel sheet and hinder the movement of the domain wall.
[0024]
Therefore, the present inventors reduce the content of the Y, La, and Ce compounds in the annealing separator containing MgO as the main component, and contain Ti, Zr, and Hf compounds as alternatives to form a primary film. At the same time, we tried to increase the density of the number of particles of the compound in the quenching separator (raw material powder) before adjusting it to the aqueous slurry. As a result, it has been found that the magnetic properties of the grain-oriented electrical steel sheet may be improved and the adhesion of the primary coating may be improved.
[0025]
The present inventors further investigated the Y, La, Ce compounds and the Ti, Zr, Hf compounds in the annealing separator, and obtained the following findings. Since the unreacted Y, La, Ce compounds and Ti, Zr, Hf compounds are difficult to form a primary film, the primary film does not become dense. In this case, the primary coating cannot cover the entire surface of the steel sheet, and a part of the surface of the steel sheet is exposed. The more the surface of the steel sheet is exposed, the lower the rust resistance.
[0026]
Therefore, the present inventors further investigated an annealing separator mainly composed of MgO. As a result, the present inventors have contained Ca, Sr, and Ba compounds together with Y, La, Ce compounds, Ti, Zr, and Hf compounds in the annealing separator, and Y, La, Ce compounds in the annealing separator. By adjusting the oxide-equivalent content of Ti, Zr, and Hf compounds, and the sulfate-equivalent content of Ca, Sr, and Ba compounds, the depth of the roots of the primary coating can be adjusted. We have found that the state of dispersion can be adjusted. This point will be described in detail below.
[0027]
The main component of the root of the primary film is an Al oxide typified by spinel (MgAl 2O 4). The depth position from the surface of the peak of Al emission intensity obtained by performing elemental analysis based on the glow discharge emission spectrometry (GDS method) from the surface of the directional electromagnetic steel plate in the plate thickness direction (hereinafter referred to as Al peak). The position D Al) is considered to indicate the position of the spinel, that is, the position of the root of the primary coating. Further, the number density of Al oxides represented by spinels having a diameter equivalent to a circle based on the area at the Al peak position D Al and having a size of 0.2 μm or more (hereinafter referred to as Al oxide number density ND) is the primary coating. It is considered to indicate the dispersed state of the roots.
[0028]
If the following conditions (1) to (3) are satisfied, the root of the primary coating has an appropriate length and is in an appropriate dispersed state, so that excellent magnetic properties and adhesion of the primary coating can be obtained. .. Furthermore, since the primary coating becomes dense, it has excellent rust resistance.
(1) Al peak position D Al is 2.4 to 12.0 μm.
(2) The Al oxide number density ND is 0.03 to 0.18 / μm 2.
(3) Of the plurality of Al oxides in the observation region at the peak position of Al emission intensity, all of the total cross-sectional area of ​​the specific Al oxide having a cross-sectional area of ​​0.4 to 10.0 μm 2 in the observation region. The ratio of Al oxide to the total cross-sectional area (hereinafter referred to as the specific Al oxide area ratio RA AREA) is 75.0% or more.
[0029]
The above-mentioned appropriate ranges of the Al peak position D Al, the Al oxide number density ND, and the specific Al oxide area ratio RA AREA are the average particle size of the Y, La, and Ce compounds in the quenching separator, Y, La. , Ce compound in terms of oxide content, Ca, Sr, Ba compound in terms of sulfate, average particle size of Ca, Sr, Ba compound, and Ti, Zr, Hf compound in terms of oxide. From the group consisting of the number of particles of the metal compound selected from the group consisting of Y, La, and Ce in the raw material powder before adjusting the content and the quenching separator into the aqueous slurry, and the group consisting of Ti, Zr, Hf. It can be obtained by adjusting the number density of the particles of the selected metal compound and the number density of the particles of the metal compound selected from the group consisting of Ca, Sr, and Ba within an appropriate range.
[0030]
The inventors have described the oxide-equivalent content C RE (described later) of the Y, La, and Ce compounds and the oxide-equivalent content C G4 (described later) of the Ti, Zr, and Hf compounds in the MgO-based annealing separator. The ratio, an image showing the distribution of Al obtained by EDS analysis in the glow discharge scar region of Al peak position D Al, and the Al oxide number density ND (pieces / μm 2) in each image were investigated. As a result, it was found that the Al oxide number density ND was changed by adjusting the content of the Y, La and Ce compounds and the content of the Ti, Zr and Hf compounds in the quenching separator.
[0031]
Further, by adjusting the oxide-equivalent content of the Y, La, and Ce compounds and the oxide-equivalent content of the Ti, Zr, and Hf compounds in the annealing separator, the compounds are dispersed in the observation region. The size of the Al oxide also changes.
[0032]
Further, at the Al peak position D Al, the Al oxide having a cross-sectional area of ​​less than 0.4 μm 2 (hereinafter referred to as micro Al oxide) is the root of an extremely fine film or a film that has not reached the peak depth. It is the root of. The fine Al oxide is unlikely to contribute to the improvement of the adhesion of the primary film. Even with such a minute Al oxide, the film adhesion can be improved by increasing the number density. However, if the number density of the minute Al oxides increases, the primary film does not become dense. In this case, not only the rust resistance of the grain-oriented electrical steel sheet is deteriorated, but also the movement of the domain wall is hindered and the iron loss is reduced. On the other hand, Al oxides having a cross-sectional area of ​​more than 10.0 μm 2 (hereinafter referred to as coarse Al oxides) are aggregated and the adhesion is not effectively improved. Even if it is a coarse Al oxide, if the number density is increased, the film adhesion is improved. However, as the number density of the coarse Al oxide increases, the magnetic flux density decreases.
[0033]
In the observation region, when the Al oxide is dispersed at 0.03 to 0.18 / μm 2, the area is 0.4 to 10, which is a size that can contribute to the improvement of adhesion. When the total area of ​​0 μm 2 Al oxide (hereinafter referred to as specific Al oxide) occupies 75% or more of the total area of ​​all Al oxides, the depth positions where the specific Al oxide exists are aligned. It means that it is. This means that in the primary coating, the size of the Al oxide is uniform (that is, there are many specific Al oxides), and the primary coating is dense. Therefore, the rust resistance of the grain-oriented electrical steel sheet is improved, and good magnetic properties and good film adhesion can be obtained.
[0034]
The above-mentioned primary coating can be formed by using the following annealing separator. The quenching separator suitable for the directional electromagnetic steel sheet of the present invention contains MgO, Y, La, Ce compounds, Ti, Zr, Hf compounds, and Ca, Sr, Ba compounds in the annealing separator. When the MgO content is 100% by mass, the total oxide content of the Y, La, and Ce compounds is 0.8 to 8.0%, which is the oxide equivalent of the Ti, Zr, and Hf compounds. The total content is 0.5 to 9.0%, and the total content of Ca, Sr, and Ba compounds in terms of sulfate is 0.5 to 8.0%. In the quenching separator, the average particle size of the Ca, Sr, Ba compound is 12 μm or less, and the ratio of the average particle size of the Ca, Sr, Ba compound to the average particle size of the Y, La, Ce compound is 0.1 to 3. It is 0.0, and the total of the total content of the Y, La, and Ce compounds in terms of oxide and the total content of the Ti, Zr, and Hf compounds in terms of oxide is 2.0 to 12.5%, and is annealed. The ratio of the total number of Y, La, and Ce atoms to the total number of Ti, Zr, and Hf atoms contained in the separating agent is 0.18 to 4.0, and the quenching separating agent is used as an aqueous slurry. In the raw material powder before preparation, the number density of particles having a particle size of 0.1 μm or more of the metal compound selected from the group consisting of Y, La, and Ce is selected from the group consisting of Ti, Zr, and Hf. The number density of the particles of the metal compound having a particle size of 0.1 μm or more and the number density of the particles having a particle size of 0.1 μm or more of the metal compound selected from the group consisting of Ca, Sr, and Ba are 2 billion / g or more. Is. If this quenching separator is used, even if it is a directional electromagnetic steel plate manufactured from a hot-rolled steel plate containing magnetic flux density improving elements (Sn, Sb, Bi, Te, Pb, etc.), the Al peak position in the primary coating D Al is 2.4 to 12.0 μm, and the number density ND of Al oxides having a size equivalent to 0.2 μm or more based on the area is 0.03 to 0.18 / μm 2. In the observation region of 30 μm × 50 μm at the peak position of Al emission intensity, the specific Al oxide area ratio RA AREA is 75.0% or more. As a result, excellent magnetic properties, adhesion of the primary coating, and excellent rust resistance can be obtained.
[0035]
The grain-oriented electrical steel sheet according to the present invention completed based on the above findings has a mass% of C: 0.005% or less, Si: 2.5 to 4.5%, Mn: 0.02 to 0.2%. One or more elements selected from the group consisting of, S and Se: 0.005% or less in total, sol. It contains Al: 0.01% or less and N: 0.01% or less, and the balance is formed on the surface of the base steel sheet having a chemical composition consisting of Fe and impurities and the surface of the base steel sheet, and is Mg 2SiO. It is provided with a primary coating containing 4 as a main component. 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 2.4 to the plate thickness direction from the surface of the primary coating. Arranged within the range of 12.0 μm, the number density of Al oxides at the peak position of Al emission intensity is 0.03 to 0.18 / μm 2, and 30 μm × 50 μm at the peak position of Al emission intensity. Of the plurality of Al oxides in the observation region, the total cross-sectional area of ​​the specific Al oxide having a cross-sectional area of ​​0.4 to 10.0 μm 2 is 75 of the total cross-sectional area of ​​all Al oxides in the observation region. It is 0.0% or more.
[0036]
The method for manufacturing grain-oriented electrical steel sheets according to the present invention is from C: 0.1% or less, Si: 2.5 to 4.5%, Mn: 0.02 to 0.2%, S and Se in mass%. One or more elements selected from the group: 0.005-0.07% in total, sol. Cold at a cold rolling ratio of 80% or more with respect to a hot-rolled steel sheet containing Al: 0.005 to 0.05% and N: 0.001 to 0.030% and the balance being Fe and impurities. A process of manufacturing a cold-rolled steel sheet to be a base steel sheet by rolling, a process of performing decarburization annealing on the cold-rolled steel sheet, and a shrinking separator on the surface of the cold-rolled steel sheet after decarburization annealing. A step of applying the contained aqueous slurry and drying the aqueous slurry on the surface of the cold-rolled steel sheet in a furnace at 400 to 1000 ° C., and a step of performing finish annealing on the cold-rolled steel sheet after the aqueous slurry has been dried. And prepare. The annealing separation agent contains at least one metal compound selected from the group consisting of MgO, Y, La, and Ce, and at least one metal compound selected from the group consisting of Ti, Zr, and Hf. Select from the above group consisting of Ca, Sr, and Ba.When the MgO content in the quenching separator is 100% by mass%, the compound selected from the group consisting of Y, La, and Ce is converted into an oxide. The total content is 0.8 to 8.0%, and the total content in terms of oxide of the metal compound selected from the group consisting of Ti, Zr and Hf is 0.5 to 9.0%. The total content of the metal compound selected from the group consisting of Ca, Sr and Ba in terms of sulfate is 0.5 to 8.0%, and the metal compound selected from the group consisting of Ca, Sr and Ba. The average particle size of the metal compound selected from the group consisting of Ca, Sr, and Ba is 12 μm or less, and the average particle size of the metal compound selected from the group consisting of Ca, Sr, and Ba is relative to the average particle size of the metal compound selected from the group consisting of Y, La, and Ce. The ratio is 0.1 to 3.0, and the total content of the metal compound selected from the group consisting of Y, La, and Ce in terms of oxide and the metal selected from the group consisting of Ti, Zr, and Hf. The total content of the compound in terms of oxide is 2.0 to 12.5%, and the total number of Ti, Zr, and Hf atoms contained in the quenching separator is the sum of the Y, La, and Ce atoms. The sum ratio of the numbers is 0.18 to 4.0, and further, the grains of the metal compound selected from the group consisting of Y, La, and Ce in the raw material powder before adjusting the quenching separator into an aqueous slurry. The number density of particles having a diameter of 0.1 μm or more, the number density of particles having a particle size of 0.1 μm or more of a metal compound selected from the group consisting of Ti, Zr, and Hf, and the number density of particles selected from the group consisting of Ca, Sr, and Ba. The number density of particles having a particle size of 0.1 μm or more of the metal compound is 2 billion pieces / g or more, respectively. However, the particle size is the equivalent diameter of a sphere on a volume basis.
[0037]
In the method for producing a directional electromagnetic steel sheet, the chemical composition of the hot-rolled steel sheet further comprises 0. It may contain 6% or less.
[0038]
In the method for producing a directional electromagnetic steel sheet, the chemical composition of the hot-rolled steel sheet further comprises 0. It may contain 03% or less.
[0039]
The annealing separator according to the present invention is used in the production of grain-oriented electrical steel sheets. The quenching separator includes at least one metal compound selected from the group consisting of MgO, Y, La, and Ce, and at least one metal compound selected from the group consisting of Ti, Zr, and Hf. And, when at least one metal compound selected from the group consisting of Ca, Sr, and Ba is contained, and the MgO content in the quenching separator is 100% by mass, Y, La, Ce. The total oxide content of the compound selected from the group consisting of is 0.8 to 8.0%, and the total content of the metal compound selected from the group consisting of Ti, Zr, and Hf is 0.8 to 8.0%. The amount is 0.5 to 9.0%, and the total content of the metal compound selected from the group consisting of Ca, Sr, and Ba in terms of sulfate is 0.5 to 8.0%, and Ca, The average particle size of the metal compound selected from the group consisting of Sr and Ba is 12 μm or less, and the average particle size of the metal compound selected from the group consisting of Ca, Sr and Ba consists of Y, La and Ce. The ratio of the metal compound selected from the group to the average particle size is 0.1 to 3.0, and the total content of the metal compound selected from the group consisting of Y, La, and Ce in terms of oxide and Ti. , Zr, and Hf are selected from the group, and the total content of the metal compound in terms of oxide is 2.0 to 12.5%, and the Ti, Zr, and Hf atoms contained in the annealing separator. The ratio of the total number of Y, La, and Ce atoms to the total number of Y, La, and Ce atoms is 0.18 to 4.0, and further, Y, La in the raw material powder before the quenching separator is adjusted to the aqueous slurry. , The number density of particles of the metal compound having a particle size of 0.1 μm or more selected from the group consisting of Ce, and the number density of particles having a particle size of 0.1 μm or more of the metal compound selected from the group consisting of Ti, Zr, Hf. , And the number density of the particles of the metal compound having a particle size of 0.1 μm or more selected from the group consisting of Ca, Sr, and Ba is 2 billion / g or more, respectively.
[0040]
Hereinafter, the method for manufacturing grain-oriented electrical steel sheets and grain-oriented electrical steel sheets according to the present invention, and the annealing separator used for manufacturing grain-oriented electrical steel sheets will be described in detail. In the present specification,% with respect to the content of an element means mass% unless otherwise specified. Further, regarding the numerical values ​​A and B, the notation "A to 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.
[0041]
[Structure of grain-oriented electrical steel sheet]
The grain-oriented electrical steel sheet according to the present invention includes a base steel sheet and a primary coating formed on the surface of the base steel sheet.
[0042]
[Chemical composition of base steel sheet]
The chemical composition of the base steel sheet constituting the above-mentioned grain-oriented electrical steel sheet contains the following elements. As will be described in the manufacturing method described later, the base steel sheet is manufactured by performing cold rolling using a hot-rolled steel sheet having a chemical composition described later.
[0043]
C: 0.005% or less
Carbon (C) is an element effective for microstructure control until the decarburization annealing process is completed during the manufacturing process, but if the C content exceeds 0.005%, the magnetic properties of the grain-oriented electrical steel sheet, which is the product plate, Decreases. Therefore, the C content is 0.005% or less. The C content is preferably as low as possible. However, even if the C content is reduced to less than 0.0001%, the above effect does not change so much, only the manufacturing cost is incurred. Therefore, the preferred lower limit of the C content is 0.0001%.
[0044]
Si: 2.5-4.5%
Silicon (Si) increases the electrical resistance of steel and reduces eddy current loss. If the Si content is less than 2.5%, the above effect cannot be sufficiently obtained. On the other hand, if the Si content exceeds 4.5%, the cold workability of the steel deteriorates. Therefore, the Si content is 2.5-4.5%. The lower limit of the Si content is preferably 2.6%, more preferably 2.8%. The preferred upper limit of the Si content is 4.0%, more preferably 3.8%.
[0045]
Mn: 0.02-0.2%
Manganese (Mn) combines with S and Se described later to form MnS and MnSe during the manufacturing process. These precipitates function as inhibitors (inhibitors of normal grain growth) and cause secondary recrystallization in steel. Mn further enhances the hot workability of steel. If the Mn content is less than 0.02%, the above effect cannot be sufficiently obtained. On the other hand, if the Mn content exceeds 0.2%, secondary recrystallization does not occur and the magnetic properties of the steel deteriorate. Therefore, the Mn content is 0.02 to 0.2%. The preferred lower limit of the Mn content is 0.03%, more preferably 0.04%. The preferred upper limit of the Mn content is 0.13%, more preferably 0.10%.
[0046]
One or more elements selected from the group consisting of S and Se: 0.005% or less in total
Sulfur (S) and selenium (Se) combine with Mn to form MnS and MnSe that function as inhibitors during the manufacturing process. However, if the total content of these elements exceeds 0.005%, the remaining inhibitors will reduce the magnetic properties. Further, segregation of S and Se may cause surface defects in the grain-oriented electrical steel sheet. Therefore, in the grain-oriented electrical steel sheet, the total content of one or more selected from the group consisting of S and Se is 0.005% or less. It is preferable that the total S and Se contents in the grain-oriented electrical steel sheet are as low as possible. However, even if the total of the S content and the Se content in the grain-oriented electrical steel sheet is reduced to less than 0.0005%, only the manufacturing cost increases and the above effect does not change so much. Therefore, the preferable lower limit of the total content of one or more selected from the group consisting of S and Se in the grain-oriented electrical steel sheet is 0.0005%.
[0047]
Sol. Al: 0.01% or less
Aluminum (Al) combines with N to form AlN during the manufacturing process of grain-oriented electrical steel sheets, and functions as an inhibitor. However, sol. If the Al content exceeds 0.01%, the inhibitor remains excessively in the steel sheet, so that the magnetic properties deteriorate. Therefore, sol. The Al content is 0.01% or less. sol. The preferred upper limit of the Al content is 0.004%, more preferably 0.003%. sol. It is preferable that the Al content is as low as possible. However, sol. Reducing the Al content to less than 0.0001% only increases the manufacturing cost and does not significantly change the above effect. Therefore, sol. In the grain-oriented electrical steel sheet. The preferable lower limit of the Al content is 0.0001%. In addition, in this specification, sol. Al means acid-soluble Al. Therefore, sol. The Al content is the content of acid-soluble Al.
[0048]
N: 0.01% or less
Nitrogen (N) combines with Al to form AlN during the manufacturing process of grain-oriented electrical steel sheets, and functions as an inhibitor. However, if the N content in the grain-oriented electrical steel sheet exceeds 0.01%, the inhibitor remains excessively in the grain-oriented electrical steel sheet, so that the magnetic properties deteriorate. Therefore, the N content is 0.01% or less. The preferred upper limit of the N content is 0.004%, more preferably 0.003%. The N content is preferably as low as possible. However, even if the total N content in the grain-oriented electrical steel sheet is reduced to less than 0.0001%, the manufacturing cost is only increased and the above effect does not change so much. Therefore, the preferable lower limit of the N content in the grain-oriented electrical steel sheet is 0.0001%.
[0049]
The balance of the chemical composition of the base steel sheet of the grain-oriented electrical steel sheet according to the present invention consists of Fe and impurities. Here, impurities are those mixed from ore, scrap, or the manufacturing environment as a raw material when the base steel sheet is industrially manufactured, or are not completely purified by purification annealing and are contained in the steel. It means the following remaining elements and the like that are permissible as long as they do not adversely affect the grain-oriented electrical steel sheet of the present invention.
[0050]
[About impurities]
In the impurities in the base steel sheet of the directional electromagnetic steel sheet according to the present invention, the total content of one or more selected from the group consisting of Cu, Sn, Sb, Bi, Te and Pb is 0.30% or less.
[0051]
Copper (Cu), tin (Sn), antimony (Sb), bismuth (Bi), tellurium (Te) and lead (Pb) are base steel sheets by high-temperature heat treatment, which is also called "purification annealing" in one process of finish annealing. A part of Cu, Sn, Sb, Bi, Te and Pb in the system is discharged to the outside of the system. These elements exert the effect of increasing the orientation selectivity of secondary recrystallization and improving the magnetic flux density in the finish annealing, but if they remain in the grain-oriented electrical steel sheet after the finish annealing is completed, they deteriorate the iron loss as mere impurities. .. Therefore, the total content of one or more elements selected from the group consisting of Cu, Sn, Sb, Bi, Te and Pb is 0.30% or less. As described above, since these elements are impurities, it is preferable that the total content of these elements is as low as possible.
[0052]
[Primary coating]
The grain-oriented electrical steel sheet according to the present invention further includes a primary coating as described above. 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). More specifically, the primary coating contains 50-90% by mass of Mg 2SiO 4.
[0053]
The main component of the primary coating is Mg 2SiO 4 as described above, but the primary coating also contains Ce, Zr and Ca. The Ce content in the primary coating is 0.001 to 8.0%. The Zr content in the primary coating is 0.0005 to 4.0%. The Ca content in the primary coating is 0.0005 to 4.0%.
[0054]
As described above, in the present invention, in the method for producing grain-oriented electrical steel sheets, the Ti, Zr, Hf compounds and the Ca, Sr, Ba compounds are combined with the Y, La, and Ce compounds described above.Use an annealed separator containing. As a result, the magnetic properties of the grain-oriented electrical steel sheet can be enhanced, and the film adhesion and rust resistance of the primary coating can be enhanced. Since the annealing separator contains Y, La, Ce compounds, Ti, Zr, Hf compounds and Ca, Sr, Ba compounds, the primary coating also contains the above-mentioned contents of Y, La, Ce, Ti, Zr, Contains Hf, Ca, Sr and Ba.
[0055]
The Mg 2SiO 4 content in the primary coating can be measured by the following method. The grain-oriented electrical steel sheet is electrolyzed to separate the primary coating unit from the surface of the base steel sheet. Mg in the separated primary film is quantitatively analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The product of the obtained quantitative value (mass%) and the molecular weight of Mg 2SiO 4 is divided by the atomic weight of Mg to obtain the content of Mg 2SiO 4 equivalent.
[0056]
The Y, La, Ce, Ti, Zr, Hf, Ca, Sr and Ba contents in the primary coating can be measured by the following method. The grain-oriented electrical steel sheet is electrolyzed to separate the primary coating unit from the surface of the base steel sheet. Quantitative analysis of Y, La, Ce content (mass%), Ti, Zr, Hf content (mass%) and Ca, Sr, Ba content (mass%) in the separated primary film by ICP-MS. ..
[0057]
[Peak position of Al emission intensity by GDS method]
Further, in the directional electromagnetic steel plate according to the present invention, the peak position of the Al emission intensity obtained when elemental analysis by the glow discharge emission spectrometry is performed in the plate thickness direction of the directional electromagnetic steel plate from the surface of the primary coating is the primary coating. It is arranged within the range of 2.4 to 12.0 μm in the plate thickness direction from the surface.
[0058]
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 has entered the inside of the steel sheet from the surface of the steel sheet is defined as "the root of the primary coating".
[0059]
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.
[0060]
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). Al peak position D When Al is less than 2.4 μm, it means that the spinel is formed at a shallow (low) position from the surface of the steel sheet. This means that the roots of the primary coating are 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, the roots of the primary coating are excessively developed, and the roots of the primary coating have penetrated to the deep part inside the steel sheet. In this case, the root of the primary coating inhibits the domain wall movement. As a result, the magnetic properties deteriorate.
[0061]
Al peak position D When Al is 2.4 to 12.0 μm, it is possible to improve the adhesion of the film while maintaining excellent magnetic properties. The lower limit of Al peak position D Al is preferably 3.0 μm, more preferably 4.0 μm. Al peak position D The preferable upper limit of Al is 11.0 μm, and more preferably 10.0 μm.
[0062]
Al peak position D Al can be measured by the following method. Elemental analysis is performed using a well-known glow discharge emission spectrometry (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.
[0063]
Al is identified in the surface layer of the steel sheet based on the emission spectrum wavelength peculiar to the element generated by exciting atoms in glow plasma. In addition, 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.
[0064]
The depth position from the surface of the primary coating in elemental analysis can be 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. The sample results are used to convert the sputter time to sputter depth. 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 invention, a commercially available high frequency glow discharge emission spectrometer can be used.
[0065]
[Number density ND of Al oxides with a size of 0.2 μm or more in discharge marks]
Further, in the directional electromagnetic steel plate according to the present invention, the number density ND of Al oxides having a diameter equivalent to a circle at the Al peak position D Al and having a size of 0.2 μm or more is 0.03 to 0.18 / μm 2. Is.
[0066]
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, when 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 primary. It is an index showing the dispersed state of the root (spinel) of the coating film on the surface layer of the steel plate.
[0067]
When the Al oxide number density ND is less than 0.03 / 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 Al oxide number density ND exceeds 0.18 / μm 2, the roots of the primary coating are excessively developed, and the roots of the primary coating have penetrated to the deep part inside the steel sheet. In this case, the roots of the primary coating inhibit secondary recrystallization and domain wall movement, and the magnetic properties deteriorate. Therefore, the Al oxide number density ND is 0.03 to 0.18 / μm 2. The preferable lower limit of the Al oxide number density ND is 0.035 pieces / μm 2, and more preferably 0.04 pieces / μm 2. The preferred upper limit of the number density ND is 0.15 pieces / μm 2, and more preferably 0.1 pieces / μm 2.
[0068]
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. Al peak position D Of the discharge marks at Al, an arbitrary 30 μm × 50 μm region (observation region) is subjected to elemental analysis using an energy dispersive X-ray spectroscope (EDS), and the characteristic X of the observation region is performed. Create a map showing the distribution of line intensity and identify Al oxides. 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 oxygen (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 predominantly spinel and may be other silicates containing various alkaline earth metals and Al in high concentrations. Among the specified Al oxides, the number of Al oxides having a diameter equivalent to a circle based on the area and having a size of 0.2 μm or more is counted, and the Al oxide number density ND (pieces / μm 2) is obtained by the following formula. ..
Circle equivalent diameter = √ (4 / π ・ (Area of ​​region specified as Al oxide (area per analysis point in the map showing distribution of characteristic X-ray intensity x area specified as Al oxide) Analysis score))
Area per analysis point = observation area area ÷ number of analysis points in the map showing the distribution of characteristic X-ray intensity
ND = number of specified Al oxides with a circle equivalent diameter of 0.2 μm or more / area of ​​the observation area
[0069]
The Ce content in the primary coating is 0.001 to 8.0%, the Zr content in the primary coating is 0.0005 to 4.0%, and the Ca content in the primary coating is 0.0005 to 0.0005. If it is 4.0%, the Al peak position D Al is 2.4 to 12.0 μm, and the number density ND of Al oxides at the Al peak position D Al is 0.03 to 0.18 / μm 2. Become.
[0070]
[Specific Al oxide area ratio RA AREA]
Further, in the directional electromagnetic steel plate according to the present invention, the total of the specific Al oxides having an area of ​​0.4 to 10.0 μm 2 among the plurality of Al oxides in the observation region of 30 μm × 50 μm at the Al peak position D Al. The ratio of the area to the total area of ​​all Al oxides in the observation area (specific Al oxide area ratio RA AREA) is 75.0% or more. The area of ​​the observation region may be, for example, an arbitrary region of 30 μm × 50 μm, and may be arbitrarily selected at the Al peak position D Al.
[0071]
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 specific Al oxide area ratio RA AREA shows the dispersed state of the roots (Al oxide) of the primary film, similar to the Al oxide number density ND.
[0072]
In the observation region of 30 μm × 50 μm, the total area of ​​the Al oxide having an area of ​​0.4 to 10.0 μm 2 among the plurality of Al oxides is 75. The total area of ​​all the Al oxides in the observation region. When it is 0% or more, it means that the depth positions of the specific Al oxides that can contribute to the improvement of adhesion are aligned. This means that the size of the Al oxide particles in the obtained primary coating is almost uniform, and the primary coating is dense.
[0073]
If the specific Al oxide area ratio RA AREA is too low, the primary coating will not be dense and the rust resistance will decrease. Therefore, the specific Al oxide area ratio RA AREA is 75.0% or more. The preferred specific Al oxide area ratio RA AREA is 84.0% or more, and more preferably 90.0% or more.
[0074]
In the above observation region, if the area of ​​the Al oxide is less than 0.4 μm 2, it has not sufficiently grown as the root of the primary coating. On the other hand, if the area of ​​the Al oxide exceeds 10.0 μm 2, the roots of the primary coating will develop excessively. As a result, the primary coating is not dense and the rust resistance is lowered.
[0075]
The specific Al oxide area ratio RA AREA can be obtained by the following method. Glow discharge is performed by the glow discharge emission spectrometer to the Al peak position D Al. Al peak position D Of the discharge marks at Al, an arbitrary region (observation region) of 30 μm × 50 μm is subjected to elemental analysis by an energy dispersive X-ray spectroscope (EDS), and Al in the observation region. Identify the oxide. 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 oxygen (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 predominantly spinel and may be other silicates containing various alkaline earth metals and Al in high concentrations. Based on the measurement results, a distribution map of Al oxide in the observation region is created. The area of ​​the observation region may be, for example, 30 μm × 50 μm, and may be selected at an arbitrary Al peak position D Al.
[0076]
Calculate the area of ​​each Al oxide in the created distribution map (observation area). Based on the calculation result, an Al oxide having an area of ​​0.4 to 10.0 μm 2 in the distribution map is recognized as a specific Al oxide. Obtain the total area of ​​the certified specific Al oxide. Further, the total area of ​​all Al oxides in the distribution map is obtained, and the specific Al oxide area ratio RA AREA is obtained based on the following equation.
[0077]
Specific Al oxide area ratio RA AREA = total area of ​​specific Al oxide in the observation area / total area of ​​all Al oxides in the observation area x 100
[0078]
[Production method]
An example of a method for manufacturing a grain-oriented electrical steel sheet according to the present invention will be described.
An example of a method for manufacturing grain-oriented electrical steel sheets includes a cold-rolling process, a decarburization annealing process, and a finish annealing process.Elu. Hereinafter, each step will be described.
[0079]
[Cold rolling process]
In the cold-rolled process, cold-rolled steel sheets are cold-rolled to manufacture cold-rolled steel sheets. The hot-rolled steel sheet contains the following chemical composition.
[0080] [0080]
C: 0.1% or less,
If the C content in the hot-rolled steel sheet exceeds 0.1%, the time required for decarburization annealing becomes longer. In this case, the manufacturing cost is high and the productivity is also lowered. Therefore, the C content of the hot-rolled steel sheet is 0.1% or less. The preferred upper limit of the C content of the hot-rolled steel sheet is 0.092%, more preferably 0.085%. The lower limit of the C content of the hot-rolled steel sheet is 0.005%, preferably 0.02%, and more preferably 0.04%.
[0081]
Si: 2.5-4.5%,
As explained in the section on chemical composition of grain-oriented electrical steel sheets, which is a product, Si increases the electrical resistance of steel, but if it is contained in excess, cold workability decreases. When the Si content of the hot-rolled steel sheet is 2.5 to 4.0%, the Si content of the grain-oriented electrical steel sheet after the finish annealing step is 2.5 to 4.5%. The upper limit of the Si content of the hot-rolled steel sheet is 4.0%, more preferably 3.8%. The lower limit of the Si content of the hot-rolled steel sheet is 2.6%, more preferably 2.8%.
[0082]
Mn: 0.02-0.2%
As explained in the item of chemical composition of grain-oriented electrical steel sheet which is a product, Mn combines with S and Se to form a precipitate and functions as an inhibitor in the manufacturing process. Mn further enhances the hot workability of steel. When the Mn content of the hot-rolled steel sheet is 0.02 to 0.2%, the Mn content of the directional electromagnetic steel sheet after the finish annealing step is 0.02 to 0.2%. The preferred upper limit of the Mn content of the hot-rolled steel sheet is 0.13%, more preferably 0.1%. The preferred lower limit of the Mn content of the hot-rolled steel sheet is 0.03%, more preferably 0.04%.
[0083]
One or more elements selected from the group consisting of S and Se: 0.005 to 0.07% in total Sulfur (S) and selenium (Se) combine with Mn during the manufacturing process to form MnS and MnSe. To form. Both MnS and MnSe function as inhibitors necessary for suppressing grain growth during secondary recrystallization. If the total content of one or more elements selected from the group consisting of S and Se is less than 0.005%, it is difficult to obtain the above effect. On the other hand, if the total content of one or more elements selected from the group consisting of S and Se exceeds 0.07%, secondary recrystallization does not occur during the manufacturing process and the magnetic properties of the steel deteriorate. .. Therefore, the total content of one or more elements selected from the group consisting of S and Se in the hot-rolled steel sheet is 0.005 to 0.07%. The preferred lower limit of the total content of one or more elements selected from the group consisting of S and Se is 0.008%, more preferably 0.016%. The preferred upper limit of the total content of one or more elements selected from the group consisting of S and Se is 0.06%, more preferably 0.05%.
[0084]
Sol. Al: 0.005 to 0.05%
During the manufacturing process, aluminum (Al) combines with N to form AlN. AlN functions as an inhibitor. Sol. In hot-rolled steel sheet. If the Al content is less than 0.01%, the above effect cannot be obtained. On the other hand, sol. If the Al content exceeds 0.05%, AlN becomes coarse. In this case, AlN becomes difficult to function as an inhibitor, and secondary recrystallization may not occur. Therefore, the sol. The Al content is 0.005 to 0.05%. Sol. In hot-rolled steel sheet. The preferred upper limit of the Al content is 0.04%, more preferably 0.035%. Sol. In hot-rolled steel sheet. The lower limit of the Al content is preferably 0.01%, more preferably 0.015%.
[0085]
N: 0.001 to 0.030%
During the manufacturing process, nitrogen (N) combines with Al to form AlN, which functions as an inhibitor. If the N content in the hot-rolled steel sheet is less than 0.001%, the above effect cannot be obtained. On the other hand, if the N content in the hot-rolled steel sheet exceeds 0.030%, AlN becomes coarse. In this case, AlN becomes difficult to function as an inhibitor, and secondary recrystallization may not occur. Therefore, the N content in the hot-rolled steel sheet is 0.001 to 0.030%. The preferable upper limit of the N content in the hot-rolled steel sheet is 0.012%, more preferably 0.010%. The preferable lower limit of the N content in the hot-rolled steel sheet is 0.005%, more preferably 0.006%.
[0086]
The balance of the chemical composition of the hot-rolled steel sheet of the present invention consists of 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 adversely affect the hot-rolled steel sheet of the present embodiment. Means something that is acceptable to the extent that it does not exist.
[0087]
[About arbitrary elements]
The hot-rolled steel sheet according to the present invention may further contain at least 0.6% of one or more elements selected from the group consisting of Cu, Sn and Sb instead of a part of Fe. All of these elements are arbitrary elements.
[0088]
One or more elements selected from the group consisting of Cu, Sn and Sb: 0 to 0.6% in total
Copper (Cu), tin (Sn) and antimony (Sb) are all optional elements and may not be contained. When contained, Cu, Sn and Sb all increase the magnetic flux density of grain-oriented electrical steel sheets. If Cu, Sn and Sb are contained even in a small amount, the above effect can be obtained to some extent. However, if the total contents of Cu, Sn and Sb exceed 0.6%, it becomes difficult to form an internal oxide layer during decarburization annealing. In this case, during finish annealing, MgO as an annealing separator and SiO 2 in the internal oxide layer react to delay the progress of primary film formation. As a result, the adhesion of the primary film is reduced. Further, Cu, Sn, and Sb are likely to remain as impurity elements after purification annealing. As a result, the magnetic properties deteriorate. Therefore, the total content of one or more elements selected from the group consisting of Cu, Sn and Sb is 0 to 0.6%. The preferred lower limit of the total content of one or more elements selected from the group consisting of Cu, Sn and Sb is 0.005%, more preferably 0.007%. The preferred upper limit of the total content of one or more elements selected from the group consisting of Sn and Sb is 0.5%, more preferably 0.45%.
[0089]
The hot-rolled steel sheet according to the present invention may further contain 0.03% or less in total of one or more elements selected from the group consisting of Bi, Te and Pb instead of a part of Fe. All of these elements are arbitrary elements.
[0090]
One or more elements selected from the group consisting of Bi, Te and Pb: 0 to 0.03% in total
Bismuth (Bi), tellurium (Te) and lead (Pb) are all optional elements and may not be contained. When contained, Bi, Te and Pb all increase the magnetic flux density of the directional electromagnetic steel plate. If any of these elements are contained, this effect can be obtained to some extent. However, if the total content of these elements exceeds 0.03%, these elements segregate on the surface during finish annealing, and the interface between the primary coating and the steel sheet becomes flat. In this case, the film adhesion of the primary film is reduced. Therefore, the total content of one or more elements selected from the group consisting of Bi, Te and Pb is 0 to 0.03%. The preferred lower limit of the total content of one or more elements selected from the group consisting of Bi, Te and Pb is 0.0005%, more preferably 0.001%. The preferred upper limit of the total content of one or more elements selected from the group consisting of Bi, Te and Pb is 0.02%, more preferably 0.015%.
[0091]
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 by performing well-known refining and casting processes. Heat the slab. The heating temperature of the slab is, for example, more than 1280 ° C to 1350 ° C. Hot rolling is performed on the heated slab to produce a hot-rolled steel sheet.
[0092]
The prepared hot-rolled steel sheet is cold-rolled to manufacture a cold-rolled steel sheet, which is a base steel sheet. Cold rolling may be carried out only once or may be carried out a plurality of times. When cold rolling is carried out a plurality of times, cold rolling is carried out, intermediate annealing for the purpose of softening is carried out, and then cold rolling is carried out. Cold rolling is carried out once or a plurality of times to produce a cold-rolled steel sheet having a product plate thickness (plate thickness as a product).
[0093]
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
[0094]
The preferable upper limit of the cold spread rate is 95%. Further, the hot-rolled steel sheet may be heat-treated or pickled before the hot-rolled steel sheet is cold-rolled.
[0095]
[Decarburization annealing 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. By decarburization annealing, the C concentration of grain-oriented electrical steel sheets is reduced to 50 ppm or less, which can suppress magnetic aging deterioration. In decarburization annealing, primary recrystallization is further developed in the steel sheet, and the processing strain introduced by the cold spreading 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.
[0096]
[Finishing annealing process]
Perform a finish annealing process on the steel sheet after the decarburization annealing process. In the finishing annealing step, first, an aqueous slurry containing an annealing separator is applied to the surface of the steel sheet. Then, annealing (finish annealing) is performed on the steel sheet coated with the aqueous slurry.
[0097]
[About aqueous slurry]
The aqueous slurry is purified by adding industrial pure water to the annealing separator described later and stirring. The ratio of the annealing separator to the industrial pure water may be determined so as to be a required coating amount when coated with a roll coater, and is preferably 2 times or more and 20 times or less, for example. If the ratio of water to the annealing separator is less than twice, the viscosity of the water slurry becomes too high and the annealing separator cannot be uniformly applied to the surface of the steel sheet, which is not preferable. When the ratio of water to the annealing separator is more than 20 times, the water slurry is not sufficiently dried in the subsequent drying step, and the water remaining in the finish annealing further oxidizes the steel sheet, resulting in deterioration of the appearance of the primary coating film. Therefore, it is not preferable.
[0098]
[About annealing separator]
In the present invention, the annealing separator used in the finishing annealing step contains magnesium oxide (MgO) and an additive. MgO is the main component of the annealing separator, and the "main component" means a component contained in a certain substance in an amount of 50% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more. 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 less than 2 g / m 2, it is not preferable because the steel sheets are seized with each other in the finish annealing. If the amount of the annealing separator adhered to the steel sheet exceeds 10 g / m 2, the manufacturing cost increases, which is not preferable. The annealing separating agent may be applied by electrostatic application or the like instead of application by an aqueous slurry.
Additives include at least one metal compound selected from the group consisting of Y, La, and Ce, at least one metal compound selected from the group consisting of Ti, Zr, and Hf, and Ca. Gold selected from the group consisting of Sr and Ba When the MgO content in the quenching separator is 100% by mass% containing at least one compound of the genus, the total oxide conversion of the compounds selected from the group consisting of Y, La, and Ce. The content is 0.8 to 8.0%, and the total oxide-equivalent content of the metal compound selected from the group consisting of Ti, Zr, and Hf is 0.5 to 9.0%, and Ca. , Sr, and Ba, the total content of the metal compound selected from the group in terms of sulfate is 0.5 to 8.0%. In the quenching separator, the average particle size of the metal compound selected from the group consisting of Ca, Sr, and Ba is 12 μm or less, and the average grain of the metal compound selected from the group consisting of Ca, Sr, and Ba is 12 μm or less. The ratio of the metal compound selected from the group consisting of the diameters Y, La, and Ce to the average particle size is 0.1 to 3.0, and the metal compound selected from the group consisting of Y, La, and Ce. The total of the total content of the metal compound selected from the group consisting of Ti, Zr, and Hf in terms of oxide is 2.0 to 12.5%. The ratio of the total number of Y, La, and Ce atoms to the total number of Ti, Zr, and Hf atoms contained in the quenching separator is 0.18 to 4.0.
[0099]
[Additive]
The additive contains a Y, La, Ce compound, a Ti, Zr, Hf compound and a Ca, Sr, Ba compound. The contents of Y, La, Ce compound, Ti, Zr, Hf compound and Ca, Sr, Ba compound are as follows.
[0100]
[Metal compound selected from the group consisting of Y, La, Ce]
The metal compounds (referred to as Y, La, Ce compounds) selected from the group consisting of Y, La and Ce have a total of 0. It contains 8 to 8.0%. Here, one kind of Y, La, and Ce compounds contained in the annealing separator is defined as M RE, and the oxide-equivalent content W RE (% by mass) of M RE in the annealing separator is as follows. It is as follows.
W RE = (MRE added amount (mass%)) / (MRE molecular weight) × ((Y2O3 molecular weight) × (Y atom number per MRE1 molecule / 2) + (La 2O3 molecular weight) × (Number of La atoms per M RE 1 molecule / 2) + (Molecular weight of CeO 2) × (Number of Ce atoms per M RE 1 molecule))
For the M RE, the ratio x RE of the total number of Y, La, and Ce atoms to the number of Mg atoms contained in the annealing separator is as follows.
x RE = ((the number of Y atoms per M RE molecule) + (the number of La atoms per M RE molecule) + (the number of Ce atoms per M RE molecule)) x (the amount of M RE added (mass%) ) / M RE molecular weight) × (MgO molecular weight / 100)
Therefore, the total content of Y, La, and Ce compounds in terms of oxides when the MgO content is 100% by mass in the annealing separator to which one or more Y, La, Ce compounds are added. Ratio of the total number of Y, La, Ce atoms to the number of Mg atoms in C RE (hereinafter referred to as oxide-equivalent content C RE of Y, La, Ce compound) and quenching separator X RE (hereinafter, Y, The abundance ratios of La and Ce atoms (referred to as X RE) are the sum of W RE and the sum of x RE of each of the metal compound species selected from the group consisting of Y, La and Ce contained in the quenching separator, respectively. Is.
[0101]
The Y, La, and Ce compounds are, for example, oxides, or hydroxides, carbonates, sulfates, etc., which are partially or wholly converted into oxides by the drying treatment and finish annealing treatment described later. The Y, La, and Ce compounds suppress the aggregation of the primary coating. The Y, La, and Ce compounds also serve as oxygen release sources. Therefore, the growth of the roots of the primary coating formed by finish annealing is promoted, and the oxide of the coating becomes dense. As a result, the adhesion of the primary coating to the steel sheet is improved, and the rust resistance is further improved. If the oxide equivalent content C RE is less than 0.8%, the above effect cannot be sufficiently obtained. On the other hand, if the oxide equivalent content C RE exceeds 8.0%, the roots of the primary coating are excessively developed. In this case, the roots of the primary coating hinder the movement of the domain wall, so that the magnetic properties deteriorate. If the oxide equivalent content C RE exceeds 8.0%, the MgO content in the annealing separator is further lowered, so that the formation of forsterite is suppressed. That is, the reactivity is reduced. Therefore, the oxide equivalent content C RE is 0.8 to 8.0%. The preferable lower limit of the oxide equivalent content CRE is 1.0%, and more preferably 2.0%. The preferred upper limit of the oxide equivalent content CRE is 6.0%, more preferably 4.5%.
[0102]
[Metal compound selected from the group consisting of Ti, Zr, Hf]
Metal compounds (referred to as Ti, Zr, Hf compounds) selected from the group consisting of Ti, Zr, and Hf have a total of 0. It contains 5 to 9.0%. Here, one kind of Ti, Zr, Hf compound contained in the annealing separator is defined as MG4, and the oxide-equivalent content WG4 (mass%) of MG4 in the annealing separator is as follows. It is as follows.
W G4 = (Molecular weight of MG4 added (% by mass)) / (Molecular weight of MG4) × ((Molecular weight of TiO 2) × (Number of Ti atoms per MG41 molecule) + (Molecular weight of ZrO2) × (MG41) Number of Zr atoms per molecule) + (Molecular weight of HfO 2) × (Number of Hf atoms per MG41 molecule))
Further, for the MG4, the ratio of the total sum of Ti, Zr, and Hf atoms to the number of Mg atoms contained in the annealing separator x G4 is as follows.
x G4 = ((the number of Ti atoms per MG41 molecule) + (the number of Zr atoms per MG41 molecule) + (the number of Hf atoms per MG41 molecule)) x (the amount of MG4 added (mass%) ) / M G4 molecular weight) × (MgO molecular weight / 100)
Therefore, the total content of Ti, Zr, Hf compounds in terms of oxide when the MgO content is 100% by mass in the annealing separator to which one or more Ti, Zr, Hf compounds are added. C G4 (hereinafter referred to as oxide-equivalent content of Ti, Zr, Hf compound C G4) and the ratio of the total sum of Ti, Zr, Hf atoms to the number of Mg atoms in the quenching separator X G4 (hereinafter, Ti, Zr). , Hf atom abundance ratio X G4) is the sum of WG4 and x G4 of each metal compound selected from the group consisting of Ti, Zr, and Hf contained in the quenching separator, respectively. ..
[0103]
The Ti, Zr, and Hf compounds are, for example, oxides and hydroxides, carbonates, sulfates, etc., which are partially or wholly converted into oxides by the drying treatment and finish annealing treatment described later. When the Ti, Zr and Hf compounds are contained in the annealing separator together with the Y, La and Ce compounds, they react with a part of the Y, La and Ce compounds during finish annealing to form a composite oxide. If the composite oxide is formed, the oxygen release capacity of the annealing separator can be increased as compared with the case where the Y, La, and Ce compounds are contained alone. Therefore, by containing the Ti, Zr, and Hf compounds instead of the Y, La, and Ce compounds, the deterioration of the magnetic properties due to the excessive inclusion of the Y, La, and Ce compounds is suppressed, and the roots of the primary coating are contained. It can promote growth and improve the adhesion of the primary coating to the steel sheet. If the oxide equivalent content C G4 is less than 0.5%, the above effect cannot be sufficiently obtained. On the other hand, when the oxide equivalent content C G4 exceeds 9.0%, the MgO content in the annealing separator becomes low, so that the formation of forsterite is suppressed. That is, the reactivity is lowered and the amount of surface oxide is reduced, and as a result, the rust resistance is deteriorated. Furthermore, if the oxide equivalent content C G4 exceeds 9.0%, the magnetic properties may deteriorate. When the oxide equivalent content C G4 is 0.5 to 9.0%, it is possible to improve the adhesion of the primary coating to the base steel sheet while suppressing the deterioration of the rust resistance and the magnetic characteristics. ..
[0104]
The preferable lower limit of the oxide equivalent content C G4 is 1.0%, and more preferably 2.0%. The preferred upper limit of the oxide equivalent content C G4 is 8.0%, more preferably 7.5%.
[0105]
[Oxide-equivalent content of Y, La, Ce compounds C RE and total content of Oxide-equivalent content of Ti, Zr, Hf compounds C G4]
The total content of the oxide-equivalent content C RE of the Y, La, and Ce compounds and the oxide-equivalent content C G4 of the Ti, Zr, and Hf compounds is 2.0 to 12.5%. If the total content is less than 2.0%, the roots of the primary coating do not grow sufficiently, and the adhesion of the temporary coating to the steel sheet is lowered. On the other hand, if the total content exceeds 12.5%, the roots of the primary coating are excessively developed and the magnetic properties are deteriorated. Therefore, the total content of the oxide-equivalent content C RE of the Y, La, and Ce compounds and the oxide-equivalent content C G4 of the Ti, Zr, and Hf compounds is 2.0 to 12.5%. The preferred lower limit of the total content is 3.0%, and the preferred upper limit is 11.0%.
[0106]
[Metal compound selected from the group consisting of Ca, Sr, and Ba]
The metal compounds (referred to as Ca, Sr, Ba compounds) selected from the group consisting of Ca, Sr, and Ba have a total of 0. It contains 5 to 8.0%. Here, when one kind of Ca, Sr, Ba compound in the annealing separator is defined as MAE, the content of MAE in sulfate equivalent is defined as 100% of MgO content in the annealing separator. The WAE is as follows.
W AE = mass% of M AE / molecular weight of M AE × ((number of atoms of Ca per M AE molecule) × (4 molecular weight of CaSO) + (number of atoms of Sr per molecule of M AE) × (4 molecular weight of SrSO) + (Number of atoms of Ba per MAE molecule) × (BaSO 4 molecular weight))
Therefore, the total content of Ca, Sr, Ba compounds in terms of sulfate when the MgO content is 100% by mass in the annealing separator to which one or more Ca, Sr, Ba compounds are added. CAE (hereinafter referred to as oxide-equivalent content CAE of Ca, Sr, and Ba compounds) is the sum of WG4.
[0107]
Ca, Sr, Ba compounds are, for example, sulfates, hydroxides, carbonates and the like. Since Ca, Sr, and Ba ions diffuse rapidly in the coating film, the addition of the Ca, Sr, and Ba compounds increases the formation rate of the coating film, makes the coating film denser, and improves rust resistance. If the sulfate equivalent content CAE is less than 0.5%, the above effect cannot be sufficiently obtained. On the other hand, if the sulfate equivalent content CAE exceeds 8.0%, the roots of the primary coating may be excessively developed and the magnetic properties may be deteriorated. If the sulfate equivalent content CAE exceeds 8.0%, the oxide inside the steel sheet becomes too dense, and degassing from the steel sheet in the subsequent stage of finish annealing causes minute defects in the coating sheet, resulting in rust resistance. The sex deteriorates. When the sulfate equivalent content CAE is 0.5 to 8.0%, it is possible to improve the adhesion of the primary coating to the base steel sheet while suppressing the deterioration of the magnetic properties, and the directional electromagnetic wave. The rust resistance of the steel sheet can be improved.
[0108]
The average particle size PSAE of the Ca, Sr, and Ba compounds is 12 μm or less. If the average particle size PSAE of the Ca, Sr, and Ba compounds exceeds 12 μm, the formation of the film is not accelerated, and the film adhesion is improved by the effect of the combined addition of the Y, La, Ce compound and the Ti, Zr, Hf compound. However, the film does not become dense and rust resistance is difficult to improve. Therefore, the average particle size PS AE is 12 μm or less. The preferred upper limit of the average particle size PSAE is 8 μm, more preferably 6 μm. The lower limit of the average particle size PSAE is not particularly limited, but is, for example, 0.01 μm or more in terms of industrial production.
[0109]
The average particle size PS RE measures Y, La, and Ce compound powders by a laser diffraction / scattering method based on JIS Z8825 (2013) using a laser diffraction / scattering type particle size distribution measuring device. Thereby, the average particle size PS RE can be obtained. Similarly, the average particle size PS AE is Ca, Sr, B. The a compound powder is measured by a laser diffraction / scattering method based on JIS Z8825 (2013) using a laser diffraction / scattering type particle size distribution measuring device. Thereby, the average particle size PSAE can be obtained.
[0110]
As described above, since Ca, Sr, and Ba ions diffuse rapidly in the primary coating, the addition of the Ca, Sr, and Ba compounds increases the formation rate of the primary coating. Further, by reducing the diameter of the Ca, Sr, and Ba compounds, the formation rate of the primary film is further increased. By controlling the particle size ratio of the Y, La, Ce compound having the oxygen releasing ability and the Ca, Sr, Ba compound to a specific range, the formation of the primary film is further performed rather than simply reducing the diameter of the Ca, Sr, Ba compound. It is promoted and the size of the oxide particles, which are the constituent units of the primary coating, becomes uniform and fine, and a dense coating can be obtained. As a result, the exposure of the surface of the steel sheet is reduced, and the rust resistance of the grain-oriented electrical steel sheet is improved. From this point of view, the ratio of the average particle size of the Ca, Sr, and Ba compounds to the average particle size of the Y, La, and Ce compounds (average particle size ratio RAAE / RE) is 0.1 to 3.0. When the average particle size ratio RA AE / RE is less than 0.1, the oxygen release ability for the decomposition of Ca, Sr, and Ba compounds is insufficient, and the diffusion flux into the coating film of Ca, Sr, and Ba becomes small. The above effect cannot be obtained. When the ratio of the average particle size of the Ca, Sr, Ba compound to the average particle size of the Y, La, Ce compound (average particle size ratio RAAE / RE) exceeds 3.0, the Ca, Sr, Ba Since the diffusion site is limited, the diffusion flux into the coating film of Ca, Sr, and Ba becomes small, so that the above effect cannot be obtained.

The scope of the claims
[Claim 1]
It is a grain-oriented electrical steel sheet
By mass%,
C: 0.005% or less,
Si: 2.5-4.5%,
Mn: 0.02-0.2%,
One or more elements selected from the group consisting of S and Se: 0.005% or less in total,
Sol. Al: 0.01% or less, and
N: 0.01% or less
A base steel sheet containing a chemical composition containing Fe and impurities, and the balance
It is formed on the surface of the base steel sheet and has a primary coating containing Mg 2SiO 4 as a main component.
The peak position of the Al emission intensity obtained when elemental analysis by the glow discharge emission spectrometry is performed from the surface of the primary coating in the plate thickness direction of the grain-oriented electrical steel sheet is in the plate thickness direction from the surface of the primary coating. Arranged within the range of 2.4 to 12.0 μm,
It is an Al oxide at the peak position of the Al emission intensity, and the number density of the Al oxide having a diameter equivalent to a circle based on an area of ​​0.2 μm or more is 0.03 to 0.18 / μm 2. ,
Of the plurality of Al oxides in the observation region of 30 μm × 50 μm at the peak position of the Al emission intensity, the total cross-sectional area of ​​the specific Al oxide having a cross-sectional area of ​​0.4 to 10.0 μm 2 is the observation region. A directional electromagnetic steel plate that is 75.0% or more of the total cross-sectional area of ​​all Al oxides inside.
[Claim 2]
By mass%,
C: 0.1% or less,
Si: 2.5-4.5%,
Mn: 0.02-0.2%,
One or more elements selected from the group consisting of S and Se: 0.005 to 0.07% in total,
Sol. Al: 0.005 to 0.05% and
N: 0.001 to 0.030%
A process of manufacturing a cold-rolled steel sheet by cold-rolling a hot-rolled steel sheet containing Fe and impurities at a cold-rolling ratio of 80% or more.
The process of decarburizing and annealing the cold-rolled steel sheet and
A step of applying an aqueous slurry containing an annealing separator to the surface of the cold-rolled steel sheet after decarburization and annealing, and drying the aqueous slurry on the surface of the cold-rolled steel sheet in a furnace at 400 to 1000 ° C.
It is provided with a step of performing finish annealing on the cold-rolled steel sheet after the aqueous slurry has been dried.
The annealing separator is
With MgO
At least one compound selected from the group consisting of Y, La, and Ce,
At least one metal compound selected from the group consisting of Ti, Zr, and Hf,
Containing at least one metal compound selected from the group consisting of Ca, Sr, and Ba,
When the MgO content in the annealing separator is 100% by mass, the total oxide-equivalent content of the compound selected from the group consisting of Y, La, and Ce is 0.8 to 8.0. %, And the total content of the metal compound selected from the group consisting of Ti, Zr, and Hf in terms of oxide is 0.5 to 9.0%, and from the group consisting of Ca, Sr, and Ba. The total content of the selected metal compound in terms of sulfate is 0.5 to 8.0%.
The average particle size of the metal compound selected from the group consisting of Ca, Sr, and Ba is 12 μm or less.
The ratio of the average particle size of the metal compound selected from the group consisting of Ca, Sr and Ba to the average particle size of the metal compound selected from the group consisting of Y, La and Ce is 0.1 to 3. 0,
The total content of the metal compound selected from the group consisting of Y, La and Ce in terms of oxide and the total content of the compound of the metal selected from the group consisting of Ti, Zr and Hf in terms of oxide. The total with the amount is 2.0 to 12.5%,
The ratio of the total number of Y, La, and Ce atoms to the total number of Ti, Zr, and Hf atoms contained in the annealing separator is 0.18 to 4.0.
Furthermore, the number density of particles of a metal compound selected from the group consisting of Y, La, and Ce, which have a volume-based equivalent sphere diameter of 0.1 μm or more, is 2 billion / g or more. ,
Furthermore, the number density of particles of a metal compound selected from the group consisting of Ti, Zr, and Hf and having a volume-based equivalent sphere diameter of 0.1 μm or more is 2 billion / g or more. ,
Furthermore, the number density of particles of a metal compound selected from the group consisting of Ca, Sr, and Ba, which has a volume-based equivalent sphere diameter of 0.1 μm or more, is 2 billion / g or more. , Manufacturing method of directional electromagnetic steel plate.
[Claim 3]
The method for manufacturing grain-oriented electrical steel sheets according to claim 2.
The chemical composition of the hot-rolled steel sheet is further replaced with a part of Fe.
A method for manufacturing grain-oriented electrical steel sheets, which contains 0.6% or less in total of one or more elements selected from the group consisting of Cu, Sb and Sn.
[Claim 4]
The method for manufacturing grain-oriented electrical steel sheets according to claim 2 or 3.
The chemical composition of the hot-rolled steel sheet is further replaced with a part of Fe.
A method for manufacturing grain-oriented electrical steel sheets, which contains 0.03% or less in total of one or more elements selected from the group consisting of Bi, Te and Pb.
[Claim 5]
Annealing separator used in the manufacture of grain-oriented electrical steel sheets
With MgO
At least one metal compound selected from the group consisting of Y, La, and Ce,
At least one metal compound selected from the group consisting of Ti, Zr, and Hf,
Containing at least one metal compound selected from the group consisting of Ca, Sr, and Ba,
When the MgO content in the annealing separator is 100% by mass, the total oxide-equivalent content of the compound selected from the group consisting of Y, La, and Ce is 0.8 to 8.0. %, And the total content of the metal compound selected from the group consisting of Ti, Zr, and Hf in terms of oxide is 0.5 to 9.0%, and from the group consisting of Ca, Sr, and Ba. The total content of the selected metal compound in terms of sulfate is 0.5 to 8.0%.
The average particle size of the metal compound selected from the group consisting of Ca, Sr, and Ba is 12 μm or less.
The ratio of the average particle size of the metal compound selected from the group consisting of Ca, Sr and Ba to the average particle size of the metal compound selected from the group consisting of Y, La and Ce is 0.1 to 3. 0,
The total content of the metal compound selected from the group consisting of Y, La and Ce in terms of oxide and the total content of the compound of the metal selected from the group consisting of Ti, Zr and Hf in terms of oxide. The total with the amount is 2.0 to 12.5%,
The ratio of the total number of Y, La, and Ce atoms to the total number of Ti, Zr, and Hf atoms contained in the annealing separator is 0.18 to 4.0.
Furthermore, the number density of particles of a metal compound selected from the group consisting of Y, La, and Ce, which have a volume-based equivalent sphere diameter of 0.1 μm or more, is 2 billion / g or more. ,
Furthermore, the number density of particles of a metal compound selected from the group consisting of Ti, Zr, and Hf and having a volume-based equivalent sphere diameter of 0.1 μm or more is 2 billion / g or more. ,
Furthermore, the number density of particles of a metal compound selected from the group consisting of Ca, Sr, and Ba, which has a volume-based equivalent sphere diameter of 0.1 μm or more, is 2 billion / g or more. , Annealing separator.