Title of invention: grain-oriented electrical steel sheet
Technical field
[0001]
　The present invention relates to a grain-oriented electrical steel sheet having excellent coating adhesion, which is used as an iron core material for transformers, generators and the like. In particular, the present invention relates to a grain-oriented electrical steel sheet having excellent bending property and excellent manufacturability of a wound core.
　The present application claims priority based on Japanese Patent Application No. 2018-010301 filed in Japan on January 25, 2018, and the content thereof is incorporated herein.
Background technology
[0002]
　The grain-oriented electrical steel sheet is a soft magnetic material and is used for an iron core of electric equipment such as a transformer. The grain-oriented electrical steel sheet is a steel sheet containing Si in an amount of about 7% by mass or less and in which crystal grains are highly integrated in the {110}<001> orientation by a Miller index. The characteristics to be satisfied by the grain-oriented electrical steel sheet include that energy loss when excited by alternating current, that is, iron loss is small.
[0003]
　In recent years, with increasing awareness of global environmental issues such as global warming, efficiency regulation of transformers using grain-oriented electrical steel sheets is being implemented. Conventionally, strict efficiency regulations are being enforced in applications where low-grade grain-oriented electrical steel sheets have been used, in particular, wound core transformers, and movement to use higher-grade grain-oriented electrical steel sheets is spreading. Therefore, there is an increasing demand for grain-oriented electrical steel sheets to reduce iron loss.
[0004]
　For the above-mentioned reason, the characteristics required for the grain-oriented electrical steel sheet used for the wound core include (A) low iron loss, and (B) a glass coating (referred to as a primary coating) in the strongly bent portion. In some cases) does not peel. Since the wound core is manufactured by winding a long steel plate in a coil shape, the steel plate has a small radius of curvature on the inner peripheral side and undergoes a strong bending process, and the primary coating film peels from the base steel plate. There is.
[0005]
　Regarding the above (A), in order to reduce the iron loss of the grain-oriented electrical steel sheet, orientation control of crystal grains is important, and an abnormal grain growth phenomenon called secondary recrystallization is used. In order to properly control the secondary recrystallization, the structure obtained by the primary recrystallization (secondary recrystallization structure) before the secondary recrystallization is formed accurately, and the fine precipitates or grains called inhibitors are formed. It is important to properly precipitate the field segregation element.
[0006]
　In the secondary recrystallization, the inhibitor suppresses the growth of crystal grains other than the {110}<001> orientation in the primary recrystallization structure, and has the function of preferentially growing the crystal grains in the {110}<001> orientation. As such, adjustment of the type and amount of inhibitor is particularly important.
[0007]
　Many studies have been disclosed regarding inhibitors. Among them, as a characteristic technique, there is a technique of utilizing B as an inhibitor. Patent Documents 1 and 2 and Non-Patent Document 1 disclose that solid solution B that functions as an inhibitor is effective in developing the {110}<001> orientation.
[0008]
　In Patent Documents 3 and 4, fine BN is formed by nitriding the material to which B is added in the steps after cold rolling, and the fine BN formed functions as an inhibitor. And contribute to the development of {110}<001> orientation.
[0009]
　In Patent Document 5, while suppressing the precipitation of BN in the hot rolling process as much as possible, the extremely fine BN is precipitated in the temperature rising process during the subsequent annealing, and the extremely fine BN thus precipitated. Functioning as an inhibitor is disclosed.
　Patent Documents 6 and 7 disclose a method of functioning as an inhibitor by controlling the precipitation morphology of B in the hot rolling step.
[0010]
　These documents disclose a technique of adding B as a steel component and utilizing it as an inhibitor. In these documents, due to the technology disclosed in the documents, since the {110}<001> orientation is highly developed after the secondary recrystallization, the hysteresis loss becomes small. Is disclosed. However, in these documents, there is no mention of coating adhesion (adhesion between the primary coating and the base steel sheet).
[0011]
　Regarding the above (B), Patent Document 8 contains C: 0.0050% or less, Si: 2.0 to 8.0%, and Mn: 0.005 to 3.0%, and Al≦ In a forsterite-coated grain-oriented electrical steel sheet having a composition controlled to 100 ppm, N≦50 ppm, S≦50 ppm, and Se≦50 ppm, a distance t ( There is disclosed a method for improving the adhesion of the forsterite coating by adjusting the distance t(Mg) between Sr) and the Mg peak position and satisfying t(Sr)≧t(Mg).
[0012]
　However, the grain-oriented electrical steel sheet described in Patent Document 8 does not contain an inhibitor component. Further, Patent Document 8 does not describe any deterioration in adhesion of the primary coating that occurs when an Al-based inhibitor is used.
　Further, Patent Document 8 discloses a method of improving the adhesion of a primary coating by combining a technique of using B as an inhibitor (a technique disclosed in Patent Documents 1 to 7) with a technique of using an Al-based inhibitor. Is not described at all.
[0013]
　Regarding the improvement of the coating adhesion of the grain-oriented electrical steel sheet based on an Al-based inhibitor, Patent Document 9 discloses that the content of Si: 2 to 7% in mass% is contained and the surface of the steel sheet is mainly composed of forsterite. A unidirectional electrical steel sheet using AlN as an inhibitor, having a primary coating, wherein the primary coating contains at least one element selected from Ca, Sr, or Ba, a rare earth metal element, and sulfur. Disclosed is a unidirectional electrical steel sheet excellent in coating adhesion, which is characterized by containing a sulfide compound containing.
[0014]
　Patent Document 10 has a primary coating mainly composed of forsterite on the surface, and in mass%, C: 0.10% or less, Si: 1.8 to 7.0%, Mn: 0.02 to 0.30, the sum of one or two selected from S and Se: 0.001 to 0.04%, acid-soluble Al: 0.01 to 0.065%, N: 0.0030 to 0. In the grain-oriented electrical steel sheet consisting of 0150% and the balance Fe and unavoidable impurities, one of Ce, La, Pr, Nd, Sc, Y oxide, hydroxide, sulfate or carbonate in the primary coating. or two or more kinds, with basis weight substantial amounts of metal conversion, 0.1 ~ 10 mg / m per surface 2 contains, and, Ti and in basis weight, 1 ~ 800 mg / m per surface 2 , characterized in that it contains The grain-oriented electrical steel sheet having excellent coating adhesion is disclosed.
[0015]
　However, the techniques disclosed in Patent Documents 9 and 10 are techniques based on Al-based inhibitors, and the technique is combined with the technique of using B as an inhibitor (the technique disclosed in Patent Documents 1 to 7). Nothing is said about the use of the technique for improving the coating adhesion in the grain-oriented electrical steel sheets disclosed in Patent Documents 1 to 7.
　As described above, in the grain-oriented electrical steel sheet containing B as the base steel sheet, it is required that the iron loss is low and that the primary coating film has good adhesion.
Prior art documents
Patent literature
[0016]
Patent Document 1: U.S. Pat. No. 3,905,842
Patent Document 2: U.S. Patent No. 3,905,843 Pat
Patent Document 3: Japanese Patent Laid-Open 01-230721 discloses
Patent Document 4: Japanese Patent Laid-Open 01-283324 discloses
JP 5: Japanese Unexamined Patent Publication No. 10-140243
Patent Document 6: International Publication No. 2O11/007771
Patent Document 7: International Publication No. 2O11/007817
Patent Document 8: Japanese Unexamined
Patent Publication No. 2004-076146 Patent Document 9: Japanese Patent Laid-Open No. 2012-214902
Patent Document 10: International Publication No. 2008/062853
Summary of the invention
Problems to be Solved by the Invention
[0017]
　Among the above-mentioned problems, particularly regarding the adhesion of the primary coating, when the transformer (particularly, the wound core transformer) is manufactured, the primary coating peels off at the strongly bent portion on the inner peripheral side of the steel sheet. A solution is sought after. By solving the above problems, it is considered possible to industrially manufacture a highly efficient transformer.
[0018]
　The present invention has been made in view of the above problems, and provides a grain-oriented electrical steel sheet using BN as an inhibitor, which has low iron loss and excellent adhesion of a primary coating. With the goal.
Means for solving the problem
[0019]
　The present inventors have studied a method for improving the adhesion of the primary coating in the grain-oriented electrical steel sheet using BN as an inhibitor. As a result, it is important for the present inventors to control the precipitation morphology of B in the steel sheet while increasing the magnetic flux density by highly accumulating the crystal grains of {110}<001> orientation in the secondary recrystallization. I found out that there is.
[0020]
　Further, when the BN is used as an inhibitor, if the BN after the finish annealing is precipitated over the entire thickness of the steel sheet, the present inventors increase the hysteresis loss and it is difficult to reduce the iron loss, and the coating film It was found that the adhesion is also inferior.
[0021]
　The present inventors diligently studied a method for solving the above problems based on the above findings. As a result, the present inventors have found that in the grain-oriented electrical steel sheet after finish annealing, the above problem can be solved by precipitating B as fine BN in a predetermined number density inside the glass coating.
[0022]
　The present invention has been made based on the above findings, and the summary thereof is as follows.
[0023]
　(1) A grain-oriented electrical steel sheet according to one aspect of the present invention is formed of a base material steel sheet, a glass coating formed in contact with the base material steel sheet, a glass coating formed in contact with the glass coating, and a phosphate and a colloid. An insulating coating film containing silica as a main component, and the base steel sheet as a chemical component, in mass%, C: 0.085% or less, Si: 0.80 to 7.00%, Mn: 0. 0.05 to 1.00%, acid-soluble Al: 0.010 to 0.065%, N: 0.012% or less, Seq=S+0.406·Se: 0.015% or less, B: 0.0005 to 0 0.0080%, balance: Fe and impurities.
　In the glass coating, BN having an average particle diameter of 50 to 300 nm is a number density of 2×10 6 to 2×10 10 within a range of 5 μm in a depth direction from an interface between the glass coating and the base material steel plate. pieces / mm 3 exists, when measuring the emission intensity of the B in the glow discharge optical emission spectrometer from the surface of the insulating coating, the emission intensity of the B inside the glass film is larger than the emission intensity of the B inside the base material steel plate ..
[0024]
　(2) In the grain-oriented electrical steel sheet according to (1), the emission intensity of Al and Fe is further measured by the glow discharge emission analysis, and among the observed peaks of the emission intensity of Al, the side closer to the insulating coating. The emission peaks of Fe are defined as the first peak of Al and the second peak of Al in order from the side of the insulating coating, and the sputtering time at which the second peak of Al is observed is t(glass). when the intensity has a t a (Fe) sputtering time becomes constant, the t luminous intensity I B in (Glass) B_t (Glass) and the emission intensity I of B in the t (Fe) B_t (Fe) and May satisfy the following formula (1).
　　I B_t (Glass) > I B_t　　　　　　　　　　　　　　　　(Fe) · · ·
　(1) The oriented electrical steel sheet according to (3) (1) or (2), the ratio of the major axis to the minor axis of the BN is 1. It may be 5 or less.
Effect of the invention
[0025]
　According to the present invention, it is possible to provide a grain-oriented electrical steel sheet using BN as an inhibitor, which has low iron loss and excellent adhesion of the primary coating.
Brief description of the drawings
[0026]
FIG. 1 is a graph showing the results of GDS analysis performed on the grain-oriented electrical steel sheet of the present invention.
MODE FOR CARRYING OUT THE INVENTION
[0027]
　The grain-oriented electrical steel sheet of the present invention (hereinafter sometimes referred to as “the present invention electrical steel sheet”) includes a base material steel sheet, a glass coating formed on the base material steel sheet, and a glass coating formed on the glass coating. An insulating coating formed mainly of phosphate and colloidal silica.
　The base steel sheet is, as a chemical component, in mass%,
　　C: 0.085% or less;
　　Si: 0.80 to 7.00%;
　　Mn: 0.05 to 1.00%;
　　Acid-soluble Al: 0. 010 to 0.065%;
　　N: 0.012% or less,
　　Seq=S+
　　0.406.Se : 0.015% or less, B: 0.0005 to 0.0080%
contained, balance: Fe and impurities ..
　On the surface layer of the glass coating, BN having an average particle diameter of 50 to 300 nm is present in a number density of 2×10 6 to 2×10 10 /mm 3 .
　When the emission intensity of B is measured from the surface of the insulating coating by glow discharge emission analysis, the emission intensity of B inside the glass coating is higher than the emission intensity of B inside the base steel sheet.
[0028]
　Further, in the electromagnetic steel sheet of the present invention, the emission intensity of Al and Fe was further measured by the glow discharge emission analysis, and among the observed peaks of the emission intensity of Al, the two peaks observed on the side of the insulating coating were the most observed. The peak was set to the first peak of Al and the second peak of Al in this order from the side of the insulating coating, and the sputtering time at which the second peak of Al was observed was set to t(glass), and the emission intensity of Fe became constant. when the sputtering time was set to t (Fe), wherein t B of the emission intensity I in (Glass) B_t (Glass) and the emission intensity I of B in the t (Fe) B_t (Fe) and the following formula (1) May be satisfied.
　　I B_t (Glass) > I B_t 　　　　　　　　　　　　　　　　(Fe) · · · (1)
　In the present invention electrical steel sheet, the ratio of the major axis to the minor axis of the BN may be 1.5 or less.
[0029]
　Hereinafter, the electromagnetic steel sheet of the present invention will be described.
[0030]
　 First, the reasons for limiting the ingredient composition of the base steel sheet of the electromagnetic steel sheet of the present invention will be described. Hereinafter,% means mass% unless otherwise specified.
[0031]
　C: 0.085% or less
　C is an element effective in controlling the primary recrystallization structure, but has an adverse effect on the magnetic properties, and is an element removed by decarburization annealing before finish annealing. If it exceeds 0.085%, the decarburization annealing time becomes long and the productivity decreases, which is not preferable. The C content is preferably 0.070% or less, more preferably 0.050% or less.
[0032]
　The lower limit includes 0%, but if C is reduced to less than 0.0001%, the manufacturing cost increases significantly. Therefore, 0.0001% is the practical lower limit for practical steel sheets.
[0033]
　Si: 0.80 to 7.00%
　Si is an element that increases the electric resistance of the steel sheet and improves the iron loss characteristics. If it is less than 0.80%, γ transformation occurs during finish annealing, and the crystal orientation of the steel sheet is impaired, which is not preferable. The amount of Si is preferably 1.50% or more, more preferably 2.50% or more.
[0034]
　On the other hand, if the Si content exceeds 7.00%, the workability deteriorates and cracks occur during rolling, so Si is set to 7.00% or less. It is preferably 5.50% or less, more preferably 4.50% or less.
[0035]
　Mn: 0.05 to 1.00%
　Mn is an element that prevents cracking during hot rolling and forms MnS and/or MnSe that functions as an inhibitor by combining with S and/or Se. If the amount of Mn is less than 0.05%, the effect of addition is not sufficiently exhibited, which is not preferable. The Mn content is preferably 0.07% or more, more preferably 0.09% or more.
[0036]
　On the other hand, if the amount of Mn exceeds 1.00%, the precipitation dispersion of MnS and/or MnSe becomes non-uniform, the desired secondary recrystallization structure cannot be obtained, and the magnetic flux density decreases, which is not preferable. The amount of Mn is preferably 0.80% or less, more preferably 0.60% or less.
[0037]
　Acid-soluble Al: 0.010 to 0.065%
　Acid-soluble Al is an element that combines with N to generate (Al,Si)N that functions as an inhibitor. If the amount of acid-soluble Al is less than 0.010%, the effect of addition is not sufficiently exhibited and the secondary recrystallization does not proceed sufficiently, which is not preferable. The amount of acid-soluble Al is preferably 0.015% or more, more preferably 0.020% or more.
[0038]
　On the other hand, when the amount of acid-soluble Al exceeds 0.065%, the precipitation dispersion of (Al,Si)N becomes non-uniform, the desired secondary recrystallization structure cannot be obtained, and the magnetic flux density decreases, which is preferable. Absent. The amount of acid-soluble Al is preferably 0.050% or less, more preferably 0.040% or less.
[0039]
　N: 0.012% or less
　Since there is a concern of iron loss deterioration due to nitride formation, the N content is 0.012% or less. The N content is preferably 0.010% or less, more preferably 0.009% or less.
[0040]
　As will be described later, N in the slab component is an element that combines with Al to form AlN that functions as an inhibitor. is there. The lower limit of the N content is not particularly limited, but if the N content is less than 0.004%, the formation of AlN becomes insufficient, which is not preferable. Therefore, the lower limit of the amount of N may be set to 0.004% or more. The N content is more preferably 0.006% or more, still more preferably 0.007% or more.
[0041]
　Seq=S+0.406·Se: 0.015% or less Although
　described later, in the slab component, S and Se are elements that combine with Mn to form MnS and/or MnSe functioning as an inhibitor. The addition amount is specified by Seq=S+0.406·Se in consideration of the atomic weight ratio of S and Se.
[0042]
　Seq is set to 0.015% or less because there is a concern of iron loss deterioration due to sulfide formation. Seq is preferably 0.013% or less, more preferably 0.011% or less.
　The lower limit of Seq is not particularly defined, but if Seq is less than 0.003%, the effect of addition is not sufficiently exhibited, so Seq may be set to 0.003% or more. Seq is more preferably 0.005% or more, still more preferably 0.007% or more.
[0043]
　B: 0.0005 to 0.0080%
　B is an element that combines with N and forms a complex precipitate with MnS or MnSe to form BN that functions as an inhibitor.
[0044]
　If the amount of B is less than 0.0005%, the effect of addition is not sufficiently exhibited, which is not preferable. The amount of B is preferably 0.0010% or more, more preferably 0.0015% or more. On the other hand, when the amount of B exceeds 0.0080%, the precipitation and dispersion of BN becomes non-uniform, the desired secondary recrystallization structure cannot be obtained, and the magnetic flux density decreases, which is not preferable. The amount of B is preferably 0.0060% or less, more preferably 0.0040% or less.
[0045]
　In the base steel sheet, the balance excluding the above elements is Fe and impurities. Impurities are elements that are inevitably mixed from the steel raw material and/or during the steelmaking process, and are allowed if they are contained in a range that does not impair the characteristics of the grain-oriented electrical steel sheet of the present invention. For example, as impurities, Cr: 0.30% or less, Cu: 0.40% or less, P: 0.50% or less, Ni: 1.00% or less, Sn: 0.30% or less, Sb: 0.30. % Or less and Bi: 0.01% or less, or one or more kinds may be contained.
[0046]
　 In the
　grain-oriented electrical steel sheet according to the present embodiment, the glass coating is formed in contact with the base material steel sheet. The glass film contains a complex oxide such as forsterite (Mg 2 SiO 4 ). The glass coating film is formed by a finish annealing treatment described below, in which an oxide layer containing silica as a main component reacts with an annealing separator containing magnesia as a main component.
[0047]
　 Average particle diameter of BN: 50 to 300
　nm When BN having a particle diameter of 50 to 300 nm is present inside the glass coating, the adhesion of the primary coating is improved. The reason for this is not clear, but the presence of BN inside the glass film (forsterite film) mainly composed of Mg 2 SiO 4 changes the morphology of the anchor part of the glass film (forsterite film), resulting in close contact. It is thought that the property will improve. Therefore, in this embodiment, the average particle diameter of BN is set to 50 to 300 nm.
　The glass coating has a three-dimensional fitting structure at the steel plate interface. The “inside of the glass film” means a range of 5 μm in the depth direction from the outermost surface of the glass film (that is, the interface between the glass film and the insulating film) toward the base material steel plate. Since the thickness of the glass coating is approximately 1 to 5 μm, the “inside of the glass coating” may include not only the glass coating but also the base steel sheet.
[0048]
　Since BN is re-precipitation after solid solution, it reduces the surface energy, and therefore the morphology is often spherical. Therefore, the BN morphology is preferably spherical. In the present embodiment, “spherical BN” refers to BN having a major axis/minor axis ratio of 1.5 or less.
[0049]
　BN having a particle size of more than 300 nm may be present, but if a large number of coarse BNs are present, the precipitation frequency of BN becomes low, and the effect of improving the coating adhesion cannot be sufficiently obtained. The diameter is 300 nm or less. The average particle size of BN is preferably 280 nm or less, more preferably 260 nm or less.
[0050]
　If the particle size of BN is less than 50 nm, the frequency of BN precipitation increases and iron loss increases, so the average particle size of BN is set to 50 nm or more. The average particle size of BN is preferably 80 nm or more.
[0051]
　Number density of BN: 2×10 6 to 2×10 10 pieces/mm 3
　Inside the glass coating, the number density of BN having an average particle diameter of 50 nm to 300 nm is 2×10 6 to 2×10 10 pieces/mm Set to 3 .
　If the number density of BN is less than 2×10 6 pieces/mm 3 , the dispersion of BN in the glass coating becomes insufficient and the effect of improving coating adhesion cannot be sufficiently obtained, which is not preferable. The number density of BN is preferably 3×10 6 pieces/mm 3 or more.
　The upper limit of the number density of BN is 2×10 10 pieces/mm 3 from the viewpoint of iron loss deterioration .
[0052]
　The number density of BN is measured by washing the grain-oriented electrical steel sheet (product) with sodium hydroxide, removing the insulating coating on the steel sheet surface, and observing the steel sheet surface with FE-SEM. The number density can be measured by photographing 10 fields of view in the plate width direction of 4 μm×plate thickness direction of 2 μm and counting the number of BNs.
[0053]
　Luminous intensity of B by GDS I B : luminous intensity of B inside glass film is larger than the emission intensity of the B inside the base steel sheet
　in the distribution of the thickness direction of the steel sheet B, the interior of the B concentration (strength of glass film ) Is lower than the B concentration (strength) inside the base material steel sheet, BN is not deposited inside the glass coating, or even if it is deposited, it is in a small amount and the coating adhesion becomes poor. Further, if fine BN is present in the base steel sheet, iron loss increases.
[0054]
　For the grain-oriented electrical steel sheet according to the present embodiment, when the emission intensity of B is measured from the surface of the insulating coating by glow discharge emission analysis, the emission intensity of B inside the glass coating is the emission intensity of B inside the base steel sheet. Greater than. As a result, the grain-oriented electrical steel sheet according to this embodiment can achieve low iron loss and excellent coating adhesion.
[0055]
　More specifically, for the grain-oriented electrical steel sheet according to the present embodiment, the emission intensity of Al and Fe is measured from the surface of the insulating coating by glow discharge emission analysis in addition to the emission intensity of B. When the sputter time from the start of measurement to the inside of the glass film is t(glass) and the sputter time from the start of measurement to the inside of the base steel sheet is t(Fe), B at time t(glass) The emission intensity IB_t(glass) of B and the emission intensity IB_t (Fe) of B at time t(Fe) satisfy the following formula (1): a sufficient amount of BN is deposited inside the glass film. It means that Therefore, by satisfying the above formula (1), it is possible to realize low iron loss and suitable coating adhesion.
　I B_t (Glass) > I B_t 　　　　　　　　　　　　　　　　(Fe) · · · (1)
[0056]
　In some cases, the sputtering time until reaching the glass film can be judged by the time at which the Mg peak occurs in the GDS measurement. This is because the glass coating is mainly composed of forsterite (Mg 2 SiO 4 ). Therefore, the depth position where the glass coating exists corresponds to the depth position (sputtering time) where the Mg peak exists. However, since the glass coating differs depending on the manufacturing conditions, the time (position) at which the Mg peak occurs may change. Therefore, in the present embodiment, it is preferable to determine the depth position of the glass film by the peak of Al. Al originates from spinel (MgAl 2 O 4 ) that precipitates at the interface between the glass coating and the base steel sheet, and the most reliable indication of reaching the glass coating is that Al present at the interface between the glass coating and the steel sheet. It is to be defined by the time when it reaches. This tendency can be identified by GDS measurement. It is assumed that when the emission intensity of Fe, Al, Mg, and B is measured by GDS, the time point at which the second peak of Al occurs is t(glass), and at that time point, it has reached the inside of the glass film.
　Further, t(Fe), which is the sputtering time until reaching the inside of the base steel sheet, can be defined as the time during which the strength of Fe becomes constant. The fact that the strength of Fe is constant means that the depth position is surely located inside the base material steel plate.
[0057]
　FIG. 1 is a graph showing the results of GDS analysis performed on the grain-oriented electrical steel sheet of the present invention. As shown in FIG. 1, when the grain-oriented electrical steel sheet according to this embodiment is subjected to GDS analysis from the surface of the insulating coating, two Al peaks are formed in the insulating coating and in the glass coating. Here, the peak of Al generated in the insulating coating is called the first peak of Al, and the peak of Al generated in the glass coating is called the second peak of Al. As described above, in the present embodiment, the time point at which the emission intensity of Al becomes maximum at the second peak of Al is defined as t(glass). In the example shown in FIG. 1, 106 seconds is t(glass).
　As shown in FIG. 1, when the Mg peak rises (depth position, around 25 seconds in FIG. 1) is the interface between the insulating film and the glass film, the time when the Mg emission intensity becomes 0 ( The depth position, around 150 seconds in FIG. 1) is the interface between the glass coating and the base steel sheet. Here, the emission intensity of Mg is slightly detected during the sputtering time of 0 to 25 seconds, but it is considered that this is due to the Mg diffused in the insulating film, so the depth position is not the glass film. It is judged that it corresponds to an insulating film.
　Further, in the present embodiment, the time when the intensity of Fe becomes constant is defined as t(Fe). In the example shown in FIG. 1, 325 seconds is t(Fe). In addition, "the intensity of Fe becomes constant" means not the time when the intensity of Fe starts to become constant but the time when the intensity of Fe becomes constant and becomes stable. For example, in the present embodiment, “the intensity of Fe has become constant” is determined by whether the emission intensity of Fe within 50 seconds falls within the change of 0.5. The time point at the end of the 50 seconds is t(Fe).
[0058]
　In order to properly control the grain size, precipitation frequency, and existing position of BN, it is necessary to appropriately control the cooling rate in the purification annealing after the finish annealing. This point will be described later.
[0059]
　 In the
　grain-oriented electrical steel sheet according to the present embodiment, an insulating coating formed on and in contact with the glass coating and mainly composed of phosphate and colloidal silica is formed.
[0060]
　Next, a manufacturing method for manufacturing the grain-oriented electrical steel sheet according to the present embodiment will be described.
[0061]
　 As
　a silicon steel slab component of the electromagnetic steel sheet of the present invention, C: 0.085% or less, Si: 0.80 to 7.00%, Mn: 0.05 to 1.00% by mass%. Acid-soluble Al: 0.010 to 0.065%, N: 0.004 to 0.012%, S: 0.01% or less, B: 0.0005 to 0.0080%.
[0062]
　C: 0.085% or less
　C is an element effective in controlling the primary recrystallization structure, but has an adverse effect on the magnetic properties, and is an element removed by decarburization annealing before finish annealing. If it exceeds 0.085%, the decarburization annealing time becomes long and the productivity decreases, so C is made 0.085% or less. It is preferably 0.070% or less, more preferably 0.050% or less.
[0063]
　The lower limit includes 0%, but if C is reduced to less than 0.0001%, the manufacturing cost increases significantly. Therefore, 0.0001% is the practical lower limit for practical steel sheets. In the grain-oriented electrical steel sheet, decarburization annealing usually reduces the amount to about 0.001% or less.
[0064]
　Si: 0.80 to 7.00%
　Si is an element that increases the electric resistance of the steel sheet and improves the iron loss characteristics. If it is less than 0.80%, γ-transformation occurs during finish annealing and the crystal orientation of the steel sheet is impaired, so Si is set to 0.80% or more. It is preferably 1.50% or more, more preferably 2.50% or more.
[0065]
　On the other hand, if it exceeds 7.00%, workability deteriorates and cracks occur during rolling, so Si is set to 7.00% or less. It is preferably 5.50% or less, more preferably 4.50% or less.
[0066]
　Mn: 0.05 to 1.00%
　Mn is an element that prevents cracking during hot rolling and forms MnS that functions as an inhibitor by combining with S and/or Se. If it is less than 0.05%, the effect of addition is not sufficiently exhibited, so Mn is made 0.05% or more. It is preferably 0.07% or more, more preferably 0.09% or more.
[0067]
　On the other hand, if it exceeds 1.00%, the precipitation dispersion of MnS becomes non-uniform, the desired secondary recrystallization structure cannot be obtained, and the magnetic flux density decreases, so Mn is made 1.00% or less. It is preferably 0.80% or less, more preferably 0.06% or less.
[0068]
　Acid-soluble Al: 0.010 to 0.065%
　Acid-soluble Al is an element that combines with N to generate (Al,Si)N that functions as an inhibitor. If it is less than 0.010%, the effect of addition is not sufficiently exhibited and the secondary recrystallization does not proceed sufficiently, so the acid-soluble Al is made 0.010% or more. It is preferably 0.015% or more, more preferably 0.020% or more.
[0069]
　On the other hand, if it exceeds 0.065%, the precipitation dispersion of (Al,Si)N becomes non-uniform, the desired secondary recrystallization structure cannot be obtained, and the magnetic flux density decreases, so that the acid-soluble Al is less than 0.1%. It is set to 065% or less. It is preferably 0.050% or less, more preferably 0.040% or less.
[0070]
　N: 0.004 to 0.012%
　N is an element that combines with Al to form AlN that functions as an inhibitor. On the other hand, during cold rolling, blisters (holes) are formed in the steel sheet. It is also an element to do. If it is less than 0.004%, the formation of AlN is insufficient, so N is made 0.004% or more. It is preferably 0.006% or more, more preferably 0.007% or more.
[0071]
　On the other hand, if it exceeds 0.012%, blisters (holes) may be generated in the steel sheet during cold rolling, so N is made 0.012% or less. It is preferably 0.010% or less, more preferably 0.009% or less.
[0072]
　S: 0.01% or less
　S is an element that combines with Mn to form MnS that functions as an inhibitor.
[0073]
　When S is 0.01% or more, the precipitation and dispersion of MnS becomes non-uniform after purification, the desired secondary recrystallization structure cannot be obtained, the magnetic flux density decreases, the hysteresis loss deteriorates, and MnS after purification. Remain, and the hysteresis loss deteriorates.
The lower limit is not particularly set, but is preferably 0.003% or more. More preferably, it is 0.007% or more.
[0074]
　B: 0.0005 to 0.0080%
　B is an element that combines with N and forms a complex precipitate with MnS to form BN that functions as an inhibitor.
[0075]
　If it is less than 0.0005%, the effect of addition is not sufficiently exhibited, so B is made 0.0005% or more. It is preferably 0.0010% or more, more preferably 0.0015% or more. On the other hand, if it exceeds 0.0080%, the precipitation dispersion of BN becomes non-uniform, the desired secondary recrystallization structure cannot be obtained, and the magnetic flux density decreases, so B is made 0.0080% or less. It is preferably 0.0060% or less, more preferably 0.0040% or less.
[0076]
　In the silicon steel slab, the balance other than the above elements is Fe and inevitable impurities. The unavoidable impurities are elements that are inevitably mixed from the steel raw material and/or in the steelmaking process, and are elements that are allowed within a range that does not impair the characteristics of the electrical steel sheet of the present invention.
[0077]
　Further, the silicon steel slab does not impair the magnetic properties of the electromagnetic steel sheet of the present invention and can improve other properties, Cr: 0.30% or less, Cu: 0.40% or less, P: 0.50% Hereinafter, one or more of Ni: 1.00% or less, Sn: 0.30% or less, Sb: 0.30% or less, and Bi: 0.01% or less may be contained.
[0078]
　
　Molten steel having the above-mentioned composition of components, which has been melted in a converter or an electric furnace and which has been subjected to vacuum degassing treatment as required, is continuously cast or ingot-cast and slab-rolled to form the present invention. Obtain a slab of silicon steel (silicon slab). The silicon steel slab is usually a slab having a thickness of 150 to 350 mm, preferably 220 to 280 mm, but may be a thin slab of 30 to 70 mm. In the case of a thin slab, there is an advantage that it is not necessary to perform rough working to an intermediate thickness when manufacturing a hot rolled sheet.
[0079]
　 The silicon steel slab is heated to 1250° C. or lower and subjected to hot rolling. When the heating temperature exceeds 1250° C., the amount of molten scale increases, and MnS and/or MnSe are completely solid-solved and finely precipitated in the subsequent steps to obtain a desired primary recrystallized grain size. It is not preferable because the decarburization annealing temperature needs to be 900° C. or higher. In addition, the finely precipitated inhibitor is prone to Ostwald growth during decarburization annealing, and as a result, the uniformity (grain sizeability) of primary recrystallized grains is deteriorated. As a result, the secondary recrystallization becomes unstable and the magnetic properties are significantly deteriorated, which is not preferable. The heating temperature is more preferably 1200°C or lower.
[0080]
　The lower limit of the heating temperature is not particularly limited, but the heating temperature is preferably 1100° C. or higher in order to secure the workability of the silicon steel slab.
[0081]
　
　A silicon steel slab heated to 1250° C. or less is subjected to hot rolling to form a hot rolled sheet. The hot-rolled sheet is heated to 1000 to 1150°C (first stage temperature) for recrystallization, and subsequently, heated to 850 to 1100°C (second stage temperature), which is lower than the first stage temperature, to be annealed. The non-uniform structure generated during rolling is made uniform. The hot-rolled sheet annealing is preferably performed once or more in order to make the history of hot-rolling uniform before the hot-rolled sheet is subjected to final cold rolling.
[0082]
　In hot-rolled sheet annealing, the first stage temperature greatly affects the precipitation of the inhibitor in the subsequent steps. If the first stage temperature exceeds 1150° C., the inhibitor finely precipitates in the subsequent steps, and the decarburization annealing temperature for obtaining the desired primary recrystallized grain size needs to be 900° C. or higher, which is not preferable. The first stage temperature is more preferably 1120°C or lower.
[0083]
　On the other hand, if the first stage temperature is lower than 1000° C., recrystallization becomes insufficient, and uniformization of the structure of the hot rolled sheet cannot be achieved, which is not preferable. The first stage temperature is more preferably 1030°C or higher.
[0084]
　When the second stage temperature exceeds 1100° C., the inhibitor is finely precipitated in the subsequent steps, which is not preferable, as in the case of the first stage temperature. On the other hand, if the second stage temperature is lower than 850° C., the γ phase is not generated, and the homogenization of the hot rolled sheet structure cannot be achieved, which is not preferable. The second stage temperature is more preferably 880°C or higher.
[0085]
　 The
　steel sheet subjected to the hot-rolled sheet annealing is subjected to one cold rolling or two or more cold rolling steps sandwiching the intermediate annealing to obtain the steel sheet having the final thickness. The cold rolling may be performed at room temperature or may be performed by warming the steel sheet to a temperature higher than room temperature, for example, about 200°C.
[0086]
　
　The steel sheet having the final thickness is subjected to decarburization annealing in a wet atmosphere for the purpose of removing C in the steel sheet and controlling the primary recrystallized grain size to a desired grain size. For example, it is preferable to perform decarburization annealing at a temperature of 770 to 950° C. for a time such that the primary recrystallized grain size becomes 15 μm or more.
[0087]
　If the decarburization annealing temperature is lower than 770° C., the desired crystal grain size cannot be obtained, which is not preferable. The decarburization annealing temperature is more preferably 800°C or higher. On the other hand, if the decarburization annealing temperature exceeds 950° C., the crystal grain size exceeds the desired crystal grain size, which is not preferable. The decarburization annealing temperature is more preferably 920°C or lower.
[0088]
　 The
　steel sheet subjected to decarburization annealing is subjected to nitriding treatment so that the N content of the steel sheet is 40 to 1000 ppm before finish annealing. When the N content of the steel sheet after the nitriding treatment is less than 40 ppm, AlN is not sufficiently precipitated and AlN does not function as an inhibitor, which is not preferable. The N content of the steel sheet after the nitriding treatment is more preferably 80 ppm or more.
[0089]
　On the other hand, if the N content of the steel sheet exceeds 1000 ppm, excessive AlN is present even after the completion of secondary recrystallization in the next finish annealing, and iron loss increases, which is not preferable. The N content of the steel sheet after the nitriding treatment is more preferably 970 ppm or less.
[0090]
　
　Subsequently, the annealing separation agent is applied to the steel sheet subjected to the nitriding treatment and subjected to finish annealing. As the annealing separator, a usual annealing separator is used.
[0091]
　
　[Secondary Recrystallization Annealing]
　Among the finishing annealings, in the secondary recrystallization annealing, since the inhibitor is strengthened by BN, the heating rate in the temperature range of 1000 to 1100°C is 15°C/hour or less. preferable. It is more preferably 10° C./hour or less. Instead of controlling the heating rate, the steel sheet may be kept in the temperature range of 1000 to 1100° C. for 10 hours or more.
[0092]
　[Purification annealing] The
　steel sheet that has been subjected to the secondary recrystallization annealing is subjected to the purification annealing after the secondary recrystallization annealing. It is preferable to subject the steel sheet after secondary recrystallization to purification annealing because the precipitates used as inhibitors are rendered harmless and the hysteresis loss in the final magnetic properties is reduced. The atmosphere of the purification annealing is not particularly limited, but for example, a hydrogen atmosphere can be mentioned. Further, the purification annealing is performed at a temperature of about 1200° C. for 10 to 30 hours. The temperature of the purification annealing is not particularly limited as long as it is about 1200°C, but from the viewpoint of productivity, 1180°C to 1220°C is preferable. If the temperature is 1180° C. or lower, the time required for the diffusion of the element becomes long, so that long-time annealing is required. At 1220°C or higher, maintenance (durability) of the annealing furnace becomes difficult.
[0093]
　[Cooling condition]
　After the purification annealing, the steel sheet is cooled under a predetermined cooling condition (cooling rate).
　In order to control the average particle diameter of BN to 50 to 300 nm, the temperature lowering rate in the temperature range of 1200 to 1000° C. is set to less than 50° C./hour. Further, the temperature lowering rate in the temperature range of 1000 to 600° C. is less than 30° C./hour.
[0094]
　The reason for setting such a cooling rate is as follows.
[0095]
　BN becomes a solid solution B and a solid solution N in a high temperature range, and N that cannot be solid solution is released into the atmosphere during the temperature decrease. On the other hand, B, which cannot be solid-dissolved during the temperature decrease, is not released to the outside of the system and precipitates as a B compound, for example, BN, Fe 2 B, and Fe 3 B in the glass coating or inside the base material steel plate . When solid solution N is not sufficiently present inside the base steel sheet, BN does not precipitate, and Fe 2 B or Fe 3 B precipitates.
[0096]
　If the cooling rate is appropriate during cooling from the high temperature range, the solid solution N is released to the outside of the system, Fe 2 B or Fe 3 B precipitates inside the base steel sheet , and further the precipitated Fe 2 B or Fe 3 B is Ostwald-grown and coarsens. The solid solution B in the glass coating combines with N in the atmosphere to deposit fine BN inside the glass coating.
[0097]
　If the cooling rate is high, the solid solution N is not released to the outside of the system, BN is finely precipitated inside the steel sheet, and Fe 2 B or Fe 3 B is finely precipitated without Ostwald growth. Even under such conditions, the solid solution B in the glass coating bonds with N in the atmosphere, and fine BN precipitates in the glass coating. However, finely precipitated BN inside the base steel sheet increases the hysteresis loss and causes an increase in iron loss of the final product.
[0098]
　If the rate of temperature decrease is less than 10° C./hour, the productivity is greatly affected. Therefore, the rate of temperature decrease is preferably 10° C./hour or more. Therefore, the temperature lowering rate in the temperature range of 1200 to 1000° C. is preferably 10 to 50° C./hour, and the temperature lowering rate in the temperature range of 1000 to 600° C. is preferably 10 to 30° C./hour.
[0099]
　The cooling atmosphere is preferably H 2 100% when cooling a temperature range of at least 1200° C. to 600° C., and N 2 100% when cooling a temperature range lower than that.
　When the atmosphere for cooling the temperature range of 1200° C. to 600° C. is N 2 100%, the steel sheet is nitrided during cooling, which causes deterioration of hysteresis loss due to formation of nitrides, which is not preferable. It is also possible to use Ar instead of H 2 as the atmosphere for cooling the temperature range of 1200° C. to 600° C., but this is not preferable from the viewpoint of cost.
[0100]
　 The
　grain-oriented electrical steel sheet after finish annealing may be subjected to magnetic domain refining treatment. By the magnetic domain refining treatment, grooves are formed on the surface of the steel sheet, the magnetic domain width is reduced, and as a result, iron loss can be reduced, which is preferable. The specific method of the magnetic domain subdivision treatment is not particularly limited, and examples thereof include laser irradiation, electron beam irradiation, etching, and a groove forming method using a gear.
　The magnetic domain refining treatment is preferably performed after finish annealing, but may be performed before finish annealing or after forming the insulating coating.
[0101]
　 An
　insulating coating forming solution is applied to the surface of the steel sheet after secondary recrystallization or the surface of the steel sheet after purification annealing, and baked to form an insulating coating. The type of insulating coating is not particularly limited, and conventionally known insulating coatings are suitable. For example, there is an insulating coating formed by applying an aqueous coating solution containing phosphate and colloidal silica.
[0102]
　As the phosphate, for example, phosphates such as Ca, Al and Sr are preferable, and among them, aluminum phosphate is more preferable. The type of colloidal silica is not particularly limited, and its particle size (number average particle size) can be appropriately selected, but if it exceeds 200 nm, it may precipitate in the treatment liquid. The average particle size) is preferably 200 nm or less. More preferably, it is 170 nm.
[0103]
　Even if the particle size of the colloidal silica is less than 100 nm, there is no problem in dispersion, but since the manufacturing cost increases, 100 nm or more is preferable from the economical point of view. More preferably, it is 150 nm or more.
[0104]
　The insulating coating is formed by applying an insulating coating forming liquid to the surface of the steel sheet by a wet coating method using a roll coater or the like and baking in air at 800 to 900° C. for 10 to 60 seconds.
Example
[0105]
　Next, an example of the present invention will be described. The condition in the example is one condition example adopted for confirming the feasibility and effect of the present invention, and the present invention is based on this one condition example. Not limited. The present invention can employ various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.
[0106]
　
　A steel slab having the composition shown in Table 1-1 was heated to 1150°C and subjected to hot rolling to obtain a hot-rolled steel sheet having a plate thickness of 2.6 mm. After annealing, followed by hot-rolled sheet annealing in which annealing is performed at 900° C., one cold rolling or multiple cold rolling with intermediate annealing is performed to obtain a cold rolled steel sheet having a final sheet thickness of 0.22 mm. did.
[0107]
[Table 1-1]

[0108]
　A cold-rolled steel sheet with a final thickness of 0.22 mm is subjected to decarburization annealing in which the soaking is performed at 860° C. in a wet atmosphere, and then subjected to nitriding treatment (annealing for increasing the nitrogen content of the steel sheet), mainly magnesia. An annealing separator as a component was applied and held at 1200° C. for 20 hours in a hydrogen gas atmosphere. After the retention, the temperature range of 1200 to 1000° C. was cooled at 40° C./hour, and the temperature range of 1000 to 600° C. was cooled at 20° C./hour. The cooling was performed in a temperature range of 1200° C. to 600° C. in a 100% H 2 atmosphere and in a temperature range of less than 600° C. in a 100% N 2 atmosphere.
　After annealing, excess magnesia was removed from the steel sheet, and an insulating coating mainly composed of colloidal silica and phosphate was formed on the generated forsterite coating to obtain a product.
　The chemical composition contained in the base steel sheet in the product is shown in Table 1-2. Note that A1 to A15 and a1 to a11 in Table 1-1 represent slab numbers, and A1 to A15 and a1 to a11 in Table 1-2 represent base material steel plate numbers. For example, the base material steel plate A1 is manufactured based on the slab A1.
[0109]
[Table 1-2]

[0110]
　Magnetic domain control was performed on the product with the insulating film formed by using a mechanical method, laser, or electron beam.
[0111]
　
　Regarding the precipitate, 5 μm in the depth direction from the inside of the glass coating of the C section of the steel sheet (that is, from the outermost surface of the glass coating (interface between the glass coating and the insulating coating) toward the base steel sheet). The B compound observed in the range) was observed by SEM-EDS in 10 visual fields of 4 μm in the plate width direction and 2 μm in the plate thickness direction, and the long side of the precipitate identified to be BN by EDS was measured and the circle equivalent The particle diameter of each precipitate was calculated by converting the particle diameter. Based on the calculated particle size of each precipitate, the number density of BN having a particle size of 50 to 300 nm and the average particle size of BN were determined.
　Table 2 shows the presence/absence of BN precipitation and the average particle size of BN.
[0112]
　 When the number density of BN was measured, the insulating coating was removed from the grain-oriented electrical steel sheet obtained by the above-mentioned manufacturing method using sodium hydroxide. Next, up to 5 μm of the glass coating surface layer having a cross section perpendicular to the rolling direction of the steel sheet was observed using SEM in a visual field of 4 μm in the plate width direction×2 μm in the plate thickness direction, and 10 fields of view were observed. Were counted.
　Table 2 shows the number density of BN.
[0113]
　
　The emission intensity I B of B was measured by glow discharge emission analysis (GDS) . When the emission intensity of B is measured by glow discharge emission analysis from the outermost surface of the steel sheet excluding the insulating film, the sputtering time from the start of measurement to reaching the glass film is defined as t(glass), and the base metal from the start of measurement when the sputtering time to reach the steel plate was t (Fe), the emission intensity I of B at time t (Glass) B_t (Glass) and the emission intensity I of B at time t (Fe) B_t (Fe) and Was measured. Table 2 shows the ratio of the two, IB_t(glass) / IB_t(Fe) . In addition, the case of IB_t(glass) / IB_t(Fe) >1 was set as the pass.
　Note that t(glass) and t(Fe) were obtained from the emission intensity of Al and Fe by GDS. More specifically, the peak of Al generated in the insulating coating is the first peak of Al, the peak of Al generated in the glass coating is the second peak of Al, and the emission intensity of Al is maximum at the second peak of Al. When it became, it was set as t (glass). Further, the time when the strength of Fe becomes constant is defined as t(Fe), and "the strength of Fe becomes constant" means that the strength of Fe does not become constant but the strength of Fe becomes constant. It was a stable point. More specifically, "the intensity of Fe has become constant" is determined by whether the emission intensity of Fe within 50 seconds falls within the change of 0.5. The time point at the end of 50 seconds was designated as t(Fe).
[0114]
　
　Film adhesion is defined as the peeling area ratio at each diameter after forming an insulating film on the primary film produced after finish annealing and then winding steel plates around round bars with different diameters (20 mm, 10 mm, 5 mm). It was evaluated by. The peeled area ratio is a ratio obtained by dividing the actually peeled area by the processed area (the area where the steel plate contacts the round bar, which corresponds to the test width×the round bar diameter×π). Even if the insulating coating is peeled off by strong bending, the peeling does not progress, and if the peeled area ratio is small, it can be evaluated that the deterioration of the transformer characteristics is small.
[0115]
　As for the film adhesion, the peeled area ratio is 0%, A is more than 0% and less than 20%, B is more than 20%, less than 40%, C is more than 40%, less than 60%, D is more than 60%, and less than 80% is E, 80. %, and less than 100% was taken as F, and 100% was taken as G. Evaluation of B or higher was evaluated as good film adhesion.
[0116]
　
　[Magnetic Flux Density B8] The
　magnetic flux density B8 (the magnetic flux density when magnetized at 800 A/m) was measured on the grain-oriented electrical steel sheet obtained by the above-described manufacturing method by single-plate magnetic measurement (SST). ..
[0117]
　[Iron loss W 17/50 ], [Iron loss after magnetic domain control W 17/50 ]
　Test pieces (for example, 100 mm×500 mm test pieces) were prepared from grain- oriented electrical steel sheets before and after magnetic domain control. The iron loss W17/50 (unit: W/kg), which is the energy loss per unit weight measured under the excitation condition at a magnetic flux density of 1.7 T and a frequency of 50 Hz, was measured.
　In addition, except for some examples, magnetic domain control was performed after forming the insulating film. As will be described later, in some of the examples, magnetic domain control was performed before forming the insulating film (sometimes referred to as an intermediate step).
[0118]
　Table 2 shows the precipitation state of BN, the B emission intensity, the evaluation of coating adhesion, and the magnetic properties of the grain-oriented electrical steel sheet (product). In Inventive Examples B1 to B15 within the scope of the present invention, grain-oriented electrical steel sheets having excellent coating adhesion and magnetic properties were obtained. In Comparative Examples b1 to b11 out of the range of the present invention, the coating adhesion and magnetic properties were inferior.
[0119]
[Table 2]

[0126]
　In Invention Examples D1 to D7 in which the emission intensity IB_t(glass) and IB_t(Fe) of B at the center of the steel sheet and the surface layer of the steel sheet satisfy the above formula (1), the coating adhesion and magnetic properties were excellent. On the other hand, in any of the manufacturing conditions d1 to d4, which are out of the range of the present invention, at least one of the film adhesion and the magnetic property was inferior.
　In addition, since magnetic domain control was performed in the intermediate steps in D6 and D7, the iron loss W 17/50 was measured only once unlike the other examples and comparative examples . Therefore, the item "Iron loss after magnetic domain control" in Table 4 is "-".
Industrial availability
[0127]
　As described above, according to the present invention, in the grain-oriented electrical steel sheet using BN as an inhibitor, it is possible to suppress the peeling of the primary coating film that occurs in the strongly bent portion of the steel sheet that is the inner peripheral side of the iron core, and the coating adheres. It is possible to stably provide a grain-oriented electrical steel sheet which is excellent in productivity, has low iron loss, and is excellent in manufacturability as a wound core. Therefore, the present invention is highly applicable in the electrical steel sheet manufacturing and utilization industries.
The scope of the claims
[Claim 1]
　A base steel sheet;
　; the base material steel plate onto glass and a coating film formed in contact with the
　formed in contact with the glass on the film, an insulating film composed mainly of phosphate and colloidal silica;
equipped with,
　said base As a chemical component, the material steel plate is, by mass%,
　　C: 0.085% or less;
　　Si: 0.80 to 7.00%;
　　Mn: 0.05 to 1.00%;
　　Acid-soluble Al: 0.010 to
　　0.065%; N: 0.012% or less,
　　Seq = S + 0.406 · Se: 0.015% or
　　less, B: 0.0005 ~ 0.0080%
contained,
　the balance Fe and impurities,
　wherein the glass film, in the range of 5μm in the depth direction from the interface between the base steel sheet and the glass film, BN having an average particle diameter of 50 ~ 300 nm is at number density, 2 × 10 6 ~ 2 × 10 10 pieces /Mm 3 present, and when
　the emission intensity of B is measured from the surface of the insulating coating by glow discharge emission analysis, the emission intensity of B inside the glass coating is greater than the emission intensity of B inside the base steel sheet.
A grain-oriented electrical steel sheet characterized by the above.
[Claim 2]
　In the glow discharge emission analysis, the emission intensities of Al and Fe were further measured, and
　among the observed peaks of the emission intensity of Al, the two peaks observed most on the side of the insulating coating were Al in order from the side of the insulating coating. The second peak of Al, the sputtering time at which the second peak of Al was observed
　was defined as t(glass), and the sputtering time at which the emission intensity of Fe became constant was defined as t(Fe). when,
　wherein t (Glass) of B in the light-emitting intensity I B_t (Glass) and the emission intensity I of B in the t (Fe) B_t (Fe) and satisfies the following formula (1)
according to claim, characterized in that 1. The grain-oriented electrical steel sheet according to 1.
　　I B_t (Glass) > I B_t 　　　　　　　　　　　　　　　　(Fe) · · · (1)
[Claim 3]
　The grain-
oriented electrical steel sheet according to claim 1 or 2, wherein the ratio of the major axis to the minor axis of the BN is 1.5 or less .