JP4626155B2 - Oriented electrical steel sheet with low magnetic field magnetic properties and excellent stability over time and method for producing the same - Google Patents

Description

    The present invention relates to a grain-oriented electrical steel sheet with an insulating coating and a method for forming the coating, and more particularly to a grain-oriented electrical steel sheet that does not contain chromium and has excellent temporal stability of low magnetic field magnetic characteristics and a method for producing the same.

  A film is applied to the surface of the grain-oriented electrical steel sheet in order to provide insulation, workability, rust prevention, and the like. In general, this surface film is composed of a base film mainly composed of forsterite formed during finish annealing and a phosphate-based overcoat film formed thereon, and is disclosed in Patent Document 1, Patent Document 2, and the like. In this way, the steel sheet is given a lower thermal expansion coefficient than that of the steel sheet, and the steel sheet is tensioned by the difference in thermal expansion coefficient between the steel sheet and the iron loss reduction effect is exhibited.

  These coatings are formed on a steel plate by applying a coating treatment liquid mainly composed of aluminum phosphate or magnesium phosphate, colloidal silica and chromic anhydride onto a steel plate having a forsterite coating as a base coating, followed by drying and baking. To be deposited. These treatment liquids contain chromium as an essential component. Therefore, with the recent increase in interest in environmental conservation, conversion to a film containing no chromium has been directed, and for example, proposals as shown in Patent Documents 3 to 6 have been made.

  In addition, it is possible to reduce the iron loss value by suppressing the formation of a base film mainly composed of forsterite during finish annealing, or forming a tension-imparting film on the surface of the exposed steel sheet after removing the generated base film. It is known to be advantageous. There is also the above-mentioned demand for an insulating coating formed on an electromagnetic steel sheet having no such forsterite base coating.

Japanese Patent Publication No.53-28375 Japanese Patent Publication No.56-52117 Japanese Patent Publication No.57-9631 Japanese Unexamined Patent Publication No. 2000-169972 JP 2000-169973 A Japanese Unexamined Patent Publication No. 2000-178760

  However, the means described in Patent Document 1 provides a tension imparting effect substantially equivalent to the chromium-containing insulating film disclosed in Patent Documents 1 and 2 and the like, thereby improving iron loss and providing moisture absorption resistance. According to the study by the present inventors, there is a problem that the improvement effect deteriorates with time. Magnetic steel sheets generate heat with repeated magnetization during their use, and may be exposed to high temperatures up to about 100 ° C., and this deterioration over time is a serious problem because it is overlooked in the initial inspection.

In addition, each means described in Patent Documents 3 to 6 also gives a certain effect on moisture absorption resistance and iron loss improvement, but is estimated to be caused by grain boundary oxidation when kept in a high-temperature air atmosphere. There is a problem that deterioration of iron loss over time occurs. In particular, along with the recent increase in low-noise requirements when using a transformer, the number of cases in which a transformer is designed to have a low magnetic field is increasing, and the iron loss characteristic has a lower magnetic field than W _17/50 , which is a normal evaluation index. W _15/50 is becoming important.

  The object of the present invention is to propose a solution to the deterioration over time of the iron loss improving effect of the above-mentioned conventional chromium-containing phosphate insulating coating, thereby reducing the same as the conventional chromium-containing insulating coating. The present invention provides means for improving the temporal stability of magnetic characteristics in a magnetic field.

  The present inventor has discovered that a factor that decreases the temporal stability of magnetic properties having an insulating coating containing no chromium is an increase in the brittle fracture tendency of the grain boundary, and an increase in the brittle fracture tendency of the grain boundary, As a result, the present invention was completed based on the knowledge that the deterioration of magnetic properties over time can be prevented by highly managing segregation elements and precipitate forming elements in the grain-oriented electrical steel sheet obtained through finish annealing.

  The grain-oriented electrical steel sheet excellent in temporal stability of the low magnetic field magnetic characteristics of the present invention is a grain-oriented electrical steel sheet having an insulating coating containing no chromium on the surface of the grain-oriented electrical steel sheet obtained by finish annealing. The grain oriented electrical steel sheet contains either or both of B and Ca in the ground iron in a mass ratio of 0.0005% or more in total, and the Se content is 0.0005% or less and the Sb content is limited to 0.0005% or less. It is what. It is preferable that the grain-oriented electrical steel sheet further contains 0.002% or more of Mo in the ground iron.

  In the above-mentioned invention, the grain-oriented electrical steel sheet original plate may have a ceramic film mainly composed of forsterite on the ground iron or be exposed from the ground iron.

  The grain-oriented electrical steel sheets according to each of the inventions described above are B and Ca in the base iron through finish annealing performed by applying hot rolling, cold rolling, decarburization annealing, and annealing separator to at least the grain-oriented electrical steel sheet material. Producing a grain-oriented electrical steel sheet having a total amount of one or both of 0.0005% or more in terms of mass ratio, Se amount is 0.0005% or less, and Sb amount is 0.0005% or less, and And applying a dielectric coating that does not contain chromium to the obtained grain-oriented electrical steel sheet. In the above production method, it is preferable that the grain-oriented electrical steel sheet further contains 0.002% or more of Mo.

  In each of the above inventions, the grain-oriented electrical steel sheet has a ceramic film mainly composed of forsterite, a ceramic film removed from such a ceramic film by chemical or mechanical means, and a finish. Any one that has not substantially produced a ceramic film mainly composed of forsterite at the end of annealing can be selected.

  In each of the above inventions, a phosphoric acid having a concentration of 0.5 to 5% by mass ratio between the step of producing the grain-oriented electrical steel sheet and the step of applying an insulating coating containing no chromium to the obtained grain-oriented electrical steel sheet It is preferable to perform pickling with an aqueous solution containing 1 to 10 seconds, and then heat treatment is performed at a temperature of 100 ° C. to 300 ° C. for 1 second to 15 seconds.

  The insulating coating according to the present invention is an insulating coating that does not contain chromium, but does not cause deterioration over time of low magnetic field magnetic properties, and has an iron loss improvement effect equivalent to or higher than that of an insulating coating containing chromium. Can be provided to the electromagnetic steel sheet. Therefore, according to the present invention, various industrial problems caused by using chromic acid can be solved.

The grain-oriented electrical steel sheet according to the present invention has a component composition containing either one or both of B and Ca in the ground iron in a total amount of 0.0005% or more, and the Se amount is 0.0005% or less, and the Sb amount is It is limited to 0.0005% or less. As will be clarified later based on the examples, the Se content in the ground iron is 0.0005% or less, the Sb content is 0.0005% or less, and the sum of B content and Ca content (B + Ca) content Is 0.0005% or more, the low magnetic field magnetic deterioration amount ΔW _15/50 is 0.002 W / kg or less, and reaches a level where there is no practical problem. On the other hand, when any of the above conditions is not satisfied, the low magnetic field magnetic deterioration amount ΔW _15/50 exceeds 0.05 W / kg, which impedes practical use. Note that a steel satisfying the above conditions and further containing 0.002% or more of Mo has a low magnetic field magnetic deterioration amount ΔW _{15/50 of} almost 0, so that the magnetic characteristics are not substantially deteriorated with time.

Here, the low magnetic field magnetic degradation amount ΔW _15/50 means low magnetic field iron by SST (Single Sheet Tester) of a directional electrical steel sheet with a width of 100 mm and a length of 280 mm with an insulating coating. loss value _{(W 15/50)} and the grain-oriented electrical steel sheet subjected to 96hr held in an air atmosphere of 80 ° C., the difference (increment deterioration of the low-field iron loss value _{(W 15/50)} in the state of gradual cooling ) And is an index of the temporal stability of the low magnetic field iron loss value. In addition, the content of trace elements such as B in the ground iron can be adjusted with nitric acid after removing the film with a mixed acid of hydrochloric acid + hydrofluoric acid when the grain oriented electrical steel sheet has a forsterite film. It is an analysis result of the iron obtained by pickling until metallic luster appears, and further washing with water and drying. On the other hand, if the grain-oriented electrical steel sheet does not have a forsterite coating, it is coated on it. It is the analysis result about the iron obtained by pickling until the metallic luster appears with nitric acid after removing the insulating coating that has been removed with a mixed acid of sulfuric acid + hydrofluoric acid, and further washing with water and drying.

  A grain-oriented electrical steel sheet excellent in temporal stability of low magnetic field magnetic properties according to the present invention is produced by manufacturing a grain-oriented electrical steel sheet having the above-mentioned ground iron composition, and forming an insulating coating containing no chromium thereon. Can be manufactured. Among these, the residual contents of Se, Sb, B, Ca, and Mo in the grain-oriented electrical steel sheet having the above-mentioned base iron composition are the yields of these component elements that are empirically determined in the production process of grain-oriented electrical steel sheets. And can be determined based on the amount of contamination from the outside.

  For example, Ca is not a component element that is positively added to the steel sheet, but is a component element that is mixed in the iron and steel as impurities in the alloying agent such as ferrosilicon and impurities in the annealing separator. The yield of Ca brought into the iron from the impurities of the alloying agent is about 80%, while the yield of Ca brought into the iron from the impurities in the annealing separator is about 30%. The amount of Ca in the medium can be controlled by selecting an alloying agent and an annealing separator having an appropriate purity. B is the sum of what is added to the steel material and what is brought in from the annealing separator, and about 80% of what is added to the steel material remains, about 30% of B contained as an impurity in the annealing separator. % Can be controlled by adding an appropriate amount to the steel material or selecting an annealing separator having an appropriate B content.

  On the other hand, Se and Sb are contained in the starting material as inhibitor elements in the production of grain-oriented electrical steel sheets. Among these, the residual amount of Se is determined by the time corresponding to the purification annealing in the series of grain-oriented electrical steel sheet manufacturing processes, particularly the finish annealing, so the final content is the amount of impurities in the starting material, the amount of added alloy and the purification annealing time. Can be controlled by. Moreover, since Sb contained in the starting material remains almost 100% in the base iron, its content can be controlled by the impurities and the amount of Sb alloy in the starting material. Also, Mo also shows a yield of almost 100%, like Sb, and can be controlled by the same means as Sb.

  In addition, since the numerical value concerning the said yield is fluctuate | varied with operation conditions, in controlling the residual content of these elements, it is necessary to define basic numerical values, such as a yield, for every operation condition. In the present invention, there is no particular limitation other than paying attention to the residual contents of the above various elements, and the treatment may be performed by a normal grain-oriented electrical steel sheet manufacturing process. Moreover, since each said element exists in the level normally contained as an impurity in the scrap and ore which are iron sources, pay special attention to a raw material and you must select what satisfies these conditions.

  An insulating coating that does not contain chromium is applied to a grain oriented electrical steel sheet that contains Ca, B, and, if necessary, Mo in the above range and has a limited Se and Sb content. This insulation coating can be performed using a grain-oriented electrical steel sheet having a forsterite coating as a base plate, or obtained by removing the forsterite coating or producing forsterite such as a large amount of chloride in the annealing separator. A grain-oriented electrical steel sheet exposed with a base iron obtained by adding an inhibitory component can be used as an original sheet.

As a composition for depositing an insulating film not containing chromium, typically, the composition described in Patent Document 3 can be used, and the compositions described in Patent Documents 4 to 6 are used. be able to. Further, it is possible to improve the anti-sticking property by adding inorganic mineral particles such as silica and alumina to these compositions. The deposition thickness of the phosphate-based insulating coating that does not contain chromium is preferably ² to ²⁰ g / m ^{2 on} both sides as measured by the basis weight of the coating. This is because if the amount is less than 2 g / m ^2, the interlayer resistance of the electrical steel sheet decreases, while if it exceeds 20 g / m ² , the space factor decreases.

  The above composition is dispersed in a suitable dispersion medium, applied to a magnetic steel sheet original plate having the above composition in the form of a solution or slurry, and dried. The conditions may also be those disclosed in the above patent documents. That is, the coating composition is prepared as a coating treatment liquid having an appropriate concentration, and this is applied to the magnetic steel sheet original plate by an appropriate application means such as a roll coater, which is 100 ° C. or higher by an appropriate furnace such as a continuous furnace. Bake at a temperature of.

  Following the drying step of the coating liquid, planarization annealing that also serves as baking is performed. The conditions for the flattening annealing are not particularly limited. However, it is desirable that the temperature increase rate over the temperature range of 200 to 700 ° C. is 10 to 60 ° C./s. This is because if the temperature rising rate in this temperature range is too small as less than 10 ° C./s, gas such as water vapor tends to remain as blisters, while cracks tend to remain when it exceeds 60 ° C./s. The annealing temperature is desirably set to a soaking time of about 2 to 120 seconds in a temperature range of 700 ° C to 950 ° C. If the temperature is too lower than the above conditions and the time is too short, the flattening is insufficient and the yield is lowered due to the shape defect, while the flattening annealing is performed when the temperature is too high and the time is too long. This is because the effect is too strong, and the steel sheet creeps and the magnetic properties deteriorate.

  The above-described series of steps can produce a grain-oriented electrical steel sheet having excellent low-field magnetic property stability over time, which is the object of the present invention. In order to surely prevent this, it is preferable to perform a surface modification treatment prior to the formation of the insulating coating. This surface modification treatment is pickled with an aqueous solution containing phosphoric acid having a concentration of 0.5 to 5% (mass ratio) for 1 to 10 seconds, and then at a temperature of 100 ° C. to 300 ° C. for 1 second to 15 seconds. This heat treatment is carried out for a long time, and this treatment produces a dense oxide such as alumina or silica on the surface of the steel sheet, which becomes a protection film against the subsequent oxidation, and has a long-lasting low resistance due to the effect of preventing grain boundary oxidation. It is considered that the magnetic field magnetic characteristics can be maintained stably. In any case, this process can substantially reduce the deterioration of the low magnetic field magnetic characteristics over time.

  Thus, the holding temperature is limited because the formation of a dense oxide is insufficient when the temperature is lower than 100 ° C., and the oxide becomes an oxide containing porous iron when the temperature exceeds 300 ° C. is there. Also, the holding time is limited because the sufficient effect does not appear if it is less than 1 second, while the effect is saturated and economical disadvantage is caused if it exceeds 10 seconds.

C: 0.045% (mass ratio, the same shall apply hereinafter), Si: 3.3%, Mn: 0.07%, Al: 0.3%, N: 0.01%, the content of Se, Sb and B is changed, the balance is substantially Fe After heating the slab made of 1380 ° C. for 30 min to a hot-rolled sheet having a thickness of 2.2 mm by hot rolling, this is subjected to hot-rolled sheet annealing at 950 ° C. for 1 min, and then cold sandwiched at 1000 ° C. for 1 min. Cold rolling was performed by hot rolling to a final thickness of 0.23 mm. This was subjected to decarburization annealing at 850 ° C. for 2 min, and after drying an annealing separator comprising 100 parts of magnesium oxide (mass ratio, the same applies hereinafter), 2 parts of titanium oxide, and 1 part of strontium sulfate. 12 g / m ² (per both sides) in terms of mass was applied, and after drying, finish annealing including secondary recrystallization and purification annealing was performed. At this time, the purification annealing was performed at 1200 ° C. in a dry hydrogen stream, and the holding time was changed. The grain-oriented electrical steel sheet obtained in this way had a forsterite film uniformly on the surface.

A test piece having a size of 300 mm × 100 mm was cut out from the obtained grain-oriented electrical steel sheet, and aluminum phosphate: 50 parts (mass ratio, the same applies hereinafter) colloidal silica: 40 parts, boric acid: 5 parts, magnesium sulfate : A coating agent with a blending ratio of 10 parts is converted to a dry state and applied to 10 g / m ^{2 on} both sides, then baked in a dry nitrogen atmosphere to form an insulating coating that does not contain chromium. It was.

The obtained product was measured for low magnetic field magnetic properties (W _15/50 ) and low magnetic field magnetic degradation amount ΔW _15/50 . The results are shown in Table 1 along with the purification annealing time and the contents of Se and the like in the ground iron. From Table 1, steels 1, 2, 7, 8, and 9 having low Se and Sb contents and sufficient Ca + B contents according to the present invention have low low magnetic field magnetic degradation ΔW _15/50 , especially Mo is 0.02%. It can be seen that the steels 8 and 9 contained above have a low magnetic field magnetic deterioration amount ΔW _15/50 of zero.

  The reason why such a result is obtained is not necessarily clear, but does not affect the interpretation of the present invention, but is presumed as follows.

First, the deterioration over time of the magnetic properties of the steel sheet coincides with the embrittlement tendency of the steel sheet, that the embrittlement origin of the steel sheet is not in the crystal grains but at the grain boundaries, and when the insulating film containing Cr is present In light of the fact that no oxidization is observed, it is presumed that when there is no effect of suppressing oxidation by Cr compounds, grain boundary oxidation of the steel sheet occurs, which causes embrittlement of the steel sheet and deterioration of the magnetic properties of the steel sheet over time. . On the other hand, Se in the ground iron exists as precipitates such as MnSe at the grain boundaries of the secondary crystal grains, promotes embrittlement and at the same time becomes the starting point of oxidation, and Sb is on the steel plate surface and the grain boundaries of the secondary crystal grains. It is presumed that segregation promotes embrittlement of grain boundaries in the same manner as Se. For this reason, when the content of these elements is high, it is considered that the surface segregation suppresses the oxidation of the grain surface, while the grain boundary preferential oxidation proceeds. In contrast, B segregates at the grain boundaries, but it is presumed to suppress grain boundary oxidation because its properties are relatively close to oxygen, and Ca also has the effect of delaying grain boundary oxidation by trapping oxygen. It is estimated that On the other hand, it is presumed that Mo forms a uniform protection film and contributes to the strengthening of grain boundaries to delay the deterioration of magnetic properties with time. Thus, in steels with low Se and Sb contents and sufficient Ca + B contents, and steels containing Mo, the deterioration with time of low magnetic field properties is delayed, and the low magnetic field magnetic deterioration amount ΔW _15/50 is low. It will be very small.

  The grain-oriented electrical steel sheet obtained in Example 1 is pickled with a 2% (mass ratio) phosphoric acid aqueous solution for 6 seconds, heat treated at 120 ° C. for 3 seconds, and then containing the same chromium as in Example 1. The product was coated with an insulating film that did not. The properties of the product obtained are shown in Table 2.

C: 0.07%, Si: 3.3%, Mn: 0.07%, Se, Sb, and B contents were changed, and the remaining slab consisting essentially of Fe was heated at 1150 ° C for 30 min and then hot rolled to a thickness of 2.2 mm The sheet was subjected to hot-rolled sheet annealing at 950 ° C. for 1 min, and then cold-rolled to finish a cold-rolled sheet having a final sheet thickness of 0.30 mm. After decarburization annealing at 850 ° C. for 2 minutes, the surface was dried with an annealing separator consisting of 100 parts of magnesium oxide (mass ratio, the same shall apply hereinafter), 2 parts of tin chloride, and 1 part of strontium sulfate. 9 g / m ² (per both sides) in terms of mass, and after drying, finish annealing including secondary recrystallization and purification annealing was performed. At this time, the purification annealing was performed at 1200 ° C. in a dry hydrogen stream, and the holding time was changed. The grain-oriented electrical steel sheet obtained in this way had a metallic luster with no forsterite coating on the surface.

A test piece having a size of 300 mm × 100 mm was cut out from the obtained grain-oriented electrical steel sheet, and colloidal silica was solid content: 20 parts, magnesium phosphate: 10-120 parts (Mg (H ₂ PO ₄ ) ₃ conversion) ) Manganese sulfate: After coating the coating agent to a blend ratio of 4 to 40 parts in a dry state to 10 g / m ^{2 on} both sides, it is baked in a dry nitrogen atmosphere and does not contain chromium. The low magnetic field magnetic properties (W _15/50 value) and low magnetic field magnetic degradation amount ΔW _15/50 of the obtained products were measured. The results are shown in Table 3 together with the purification annealing time and the contents of Se and the like in the ground iron.

  The grain-oriented electrical steel sheet obtained in Example 1 was pickled with a 4% (mass ratio) phosphoric acid aqueous solution for 8 seconds, heat treated at 220 ° C. for 2 seconds, and then containing the same chromium as in Example 2. The product was coated with an insulating film that did not. The properties of the obtained product are shown in Table 4.

C: 0.05%, Si: 3.0%, Mn: 0.05%, Sn: 0.12%, Ni: 0.11%, B: 0.0012%, Cr: 0.08%, Bi: 0.003%, Cu: 0.02%, Ca: 0.0009%, S: 0.04%, Se: 0.0006%, Al: 0.0036%, N: 0.0022%, Sb: 0.0003%, the remainder consisting essentially of Fe, heated at 1180 ° C for 30 min, then hot rolled Then, a hot-rolled sheet having a thickness of 2.2 mm was subjected to hot-rolled sheet annealing at 950 ° C. for 1 min, and then finished to a cold-rolled sheet having a final thickness of 0.30 mm by cold rolling. This was subjected to decarburization annealing at 850 ° C. for 2 minutes, and then annealed separation consisting of 100 parts of magnesium oxide (mass ratio, the same applies hereinafter), 3 parts of titanium oxide, 1 part of strontium sulfate, and 1 part of sodium hydroxide. The agent was subjected to finish annealing including secondary recrystallization annealing and purification annealing after drying on both sides at 8 g / m ² (calculated after drying). The conditions for the purification annealing are those held at 1200 ° C. for 8 hours in a dry hydrogen stream. The magnetic steel sheet obtained in this way had a forsterite film uniformly on the surface.

A test piece having a size of 300 mm × 100 mm was cut out from the obtained magnetic steel sheet original plate, and magnesium phosphate: 60 parts (in terms of Mg (H ₂ PO ₄ ) ₃ ), colloidal silica: 20 parts (in terms of solid content), Manganese sulfate: After coating the coating agent with a blending ratio of 10 parts in a dry state to 10 g / m ^{2 on} both sides, it is baked in a dry nitrogen atmosphere to form an insulating film containing no chromium. Product.

The obtained steel has Se: 0.0003%, Sb: 0.0001%, B: 0.0007%, Ca: 0.0005%, Mo: less than 0.0001%. As a result of magnetic measurement, low magnetic field magnetic degradation amount ΔW _{15 / 50} was 0.002 W / kg.

The grain-oriented electrical steel sheet obtained in Example 5 was pickled with a 5% (mass ratio) phosphoric acid aqueous solution for 10 seconds, heat treated at 290 ° C. for 12 seconds, and then with a phosphoric acid aqueous solution having a concentration of 0.5%. A surface modification treatment was performed by pickling for 2 seconds and drying at 150 ° C. for 20 seconds. As a result, the low magnetic field magnetic deterioration amount ΔW _15/50 was substantially zero.

C: 0.03%, Si: 2.9%, Mn: 0.04%, Sn: 0.01%, Ni: 0.01%, B: 0.007%, Cr: 0.02%, Bi: 0.003%, Mo: 0.026%, Ca: 0.0007%, S: 0.018%, Se: 0.0003%, Al: 0.0192%, N: 0.0077%, Sb: 0.0002%, and the remainder consisting essentially of Fe, heated at 1480 ° C for 10 min, hot rolled after heating To a hot rolled sheet with a thickness of 1.6 mm, subjected to a hot rolled sheet annealing at 950 ° C. for 1 min, followed by a primary cold rolling to 0.60 mm, followed by an intermediate annealing at 1120 ° C. for 30 s and a final sheet thickness of 0.18 mm Finished in cold rolled sheet. This was decarburized and annealed at 850 ° C. for 2 min, and then an annealing separator comprising magnesium oxide: 100 parts (mass ratio, the same applies hereinafter), bismuth chloride: 1 part, strontium sulfate: 1 part on both sides was 9 g / m. ² (Mass conversion after drying) After drying, it was subjected to finish annealing including secondary recrystallization annealing and purification annealing. The conditions for the purification annealing were maintained at 1200 ° C. for 2 hours in a dry hydrogen stream. The magnetic steel sheet obtained in this way had a metallic luster with no forsterite film remaining on the surface.

After subjecting the obtained magnetic steel sheet to a magnetic domain fragmentation process to mechanically form linear grooves, a 300 mm × 100 mm size test piece was cut out and subjected to CVD treatment (temperature: 1000 ° C., atmosphere (volume ratio) N ₂ : 50%, H ₂ : 48%, TiCl ₂ : 2%), treatment time: 30 seconds) and coated with a 0.3μm thick TiN film per side, 35% boric acid, 65% alumina A fine particle dispersion mixed with (dry state, mass ratio) is applied, and this is baked at 850 ° C. for 1 minute in an N ₂ atmosphere containing 3% by volume of H ₂ , so that boric acid becomes 3 g / m ² per side. An alumina-based insulating coating was applied to obtain a product.

The obtained product contains Se: 0.0002%, Sb: 0.0001%, B: 0.0015%, Ca: 0.0007%, Mo: 0.0018%. As a result of magnetic measurement, the amount of magnetic deterioration ΔW _15/50 is 0.001 W / kg.

Claims (10)

A grain-oriented electrical steel sheet having an insulating coating not containing chromium on the surface of a grain-oriented electrical steel sheet obtained through finish annealing, wherein the grain-oriented electrical steel sheet has either one of B and Ca in the ground iron or Grain boundary oxidation resistance and low magnetic field magnetic properties characterized in that both are contained in a mass ratio of 0.0005% or more, Se content is limited to 0.0005% or less, and Sb content is limited to 0.0005% or less. Oriented electrical steel sheet with excellent aging stability. 2. The grain-oriented electrical steel sheet has a Mo content of 0.002% or more in the base iron, and has excellent grain boundary oxidation resistance and low-field magnetic properties over time. Oriented electrical steel sheet. 3. The grain boundary oxidation resistance and low magnetic field magnetic properties according to claim 1, wherein the grain-oriented electrical steel sheet has a ceramic film mainly composed of forsterite on the ground iron. Oriented electrical steel sheet with excellent aging stability. 3. A grain oriented electromagnetic steel sheet having excellent grain-time oxidation resistance and low magnetic field magnetic property over time, according to claim 1, wherein the grain oriented electromagnetic steel sheet is exposed from a base metal. steel sheet. For the grain-oriented electrical steel sheet material, hot rolling, cold rolling, decarburization annealing, and finish annealing performed by applying an annealing separator, the total amount of B and Ca in the ground iron is totaled by mass ratio A stage of producing a grain-oriented electrical steel sheet having a content of 0.0005% or more, a Se content of 0.0005% or less, and an Sb content of 0.0005% or less, and the obtained grain-oriented electrical steel sheet does not contain chromium. A method for producing a grain-oriented electrical steel sheet having excellent intergranular oxidation resistance and low-field magnetic property temporal stability, characterized by comprising an insulating coating step. 6. A method for producing a grain-oriented electrical steel sheet excellent in grain oxidation resistance and low-field magnetic property over time, characterized in that the grain-oriented electrical steel sheet further contains 0.002% or more of Mo. . 7. Grain boundary oxidation resistance and low-field magnetic property over time stability according to claim 5 or 6, wherein the grain-oriented electrical steel sheet is produced as having a ceramic film mainly composed of forsterite. For producing a grain-oriented electrical steel sheet having excellent properties. 7. The grain boundary oxidation resistance according to claim 5 or 6, wherein the grain-oriented electrical steel sheet original plate is manufactured as having a ceramic coating mainly composed of forsterite, and then the step of removing the ceramic coating is sandwiched. And the manufacturing method of the grain-oriented electrical steel sheet excellent in the temporal stability of a low magnetic field magnetic characteristic. The grain-resistant boundary according to claim 5 or 6, wherein the grain-oriented electrical steel sheet is produced as a material substantially free of a ceramic film mainly composed of forsterite at the final annealing end stage. A method for producing a grain-oriented electrical steel sheet having excellent aging stability and low magnetic field magnetic properties over time. 1-10 by an aqueous solution containing phosphoric acid having a concentration of 0.5-5% by mass between the stage of producing the grain-oriented electrical steel sheet and the stage of applying the insulating coating containing no chromium to the obtained grain-oriented electrical steel sheet. 10. The grain oxidation resistance according to any one of claims 5 to 9, characterized by performing a second pickling, and then performing a heat treatment at a temperature of 100 ° C to 300 ° C for 1 second to 15 seconds. And the manufacturing method of the grain-oriented electrical steel sheet excellent in the temporal stability of a low magnetic field magnetic characteristic.