JP4239454B2 - Method for producing grain-oriented electrical steel sheet - Google Patents

Description

【００３８】
表１に示したとおり、この発明に従い、電解脱脂処理時に、鋼板の表面に蛍光Ｘ線による測定強度で0.10〜0.45 kcps に相当する量のSiを電着させると共に、脱炭焼鈍の昇温過程における雰囲気酸化度〔Ｐ(H₂0)/Ｐ(H₂)〕を0.45以上とし、表層酸化物におけるSiO₂生成比率を70％以下とすることによって、優れた被膜特性および電磁特性を併せて得ることができる。
なお、この発明に従い、優れた被膜特性および電磁特性が得られた製品板の脱炭焼鈍後の鋼板について、SiO₂欠乏層の有無について調査したが、発明例はいずれもSiO₂欠乏層は生じていないことが確認されている。
【００３９】
【発明の効果】
かくして、この発明によれば、脱炭焼鈍時におけるSiO₂欠乏層の生成を効果的に防止して、被膜特性および磁気特性に優れた方向性電磁鋼板を安定して得ることができ、その工業的価値は極めて大といえる。
【図面の簡単な説明】
【図１】 最終的に磁気特性の劣化を招いた脱炭焼鈍板(a) および最終的に良好な磁気特性が得られた脱炭焼鈍板(b) のサブスケール断面を比較して示した図である。
【図２】 FT-IR 測定によるSiO₂生成比率の算出要領を示した図である。
【図３】 SiO₂欠乏層を有する脱炭焼鈍板およびSiO₂欠乏層のない脱炭焼鈍板について、FT-IR 法により測定したSiO₂生成比率を比較して示した図である。
【図４】 脱炭焼鈍板のFT-IR 測定によるSiO₂生成比率と最終製品板の磁束密度Ｂ₈ との関係を示したグラフである。
【図５】 電解脱脂処理の際の電着Si量と脱炭焼鈍の昇温過程における雰囲気酸化度〔Ｐ(H₂0)/Ｐ(H₂)〕がSiO₂欠乏層の生成に及ぼす影響を示したグラフである。[0001]
[Industrial application fields]
The present invention relates to a method for producing a grain-oriented electrical steel sheet having excellent coating characteristics and electromagnetic characteristics, and in particular, by appropriately controlling the state of subscale generation in decarburization annealing, the coating characteristics and electromagnetic characteristics are advantageously improved. It is something to try.
[0002]
[Prior art]
Oriented electrical steel sheets are mainly used as core materials for transformers and other electrical equipment, and basically have excellent electromagnetic properties such as magnetic flux density and iron loss, and coating properties such as insulation and adhesion. It is considered important.
[0003]
Such grain-oriented electrical steel sheet is obtained by hot rolling a steel slab containing an inhibitor necessary for secondary recrystallization, such as MnS, MnSe, AlN, etc., and then performing hot rolling sheet annealing as necessary, and then once or The final thickness is obtained by cold rolling at least twice with intermediate annealing, followed by decarburization annealing, followed by the application of an annealing separator such as MgO to the surface of the steel sheet, followed by final finish annealing. The In general, a forsterite (Mg ₂ SiO ₄ ) -like insulating film is formed on the surface of the grain-oriented electrical steel sheet except for special cases.
[0004]
This forsterite insulating coating electrically contributes to reducing the eddy current by electrically insulating the layers when the steel plates are laminated, but the insulating coating on the surface of the steel plate is not uniform. If the film is peeled off during the production of the wound core, not only will the product value be reduced, but the space factor will be reduced, and further, the insulation will be lowered due to tightening during the assembly of the iron core, causing local heat generation. It can also cause accidents in transformers.
[0005]
In addition, this forsterite insulating coating contributes to the improvement of iron loss and magnetostriction by applying tensile stress to the steel sheet using its low thermal expansion property as well as electrical insulation of the steel sheet surface. Yes.
Further, this forsterite insulating coating contributes to the improvement of magnetic properties by sucking up the inhibitor component which is no longer necessary after the completion of secondary recrystallization into the coating and purifying the steel.
Therefore, controlling the formation process of such an insulating film to form a uniform and smooth forsterite insulating film is one of the important points affecting the product quality of grain-oriented electrical steel sheets.
[0006]
By the way, the forsterite insulating coating as described above is formed by causing a solid-phase reaction between SiO ₂ in the subscale generated during decarburization annealing and MgO in the annealing separator in accordance with the following equation during high-temperature finish annealing. It is formed.
2MgO + SiO ₂ → Mg ₂ SiO ₄
Therefore, conventionally, various studies have been conducted on the subscale generated during decarburization annealing in order to form a good forsterite insulating coating.
[0007]
For example, in JP-A-6-336616, in the soaking process of decarburization annealing, the atmosphere in the furnace is set to a non-FeO production region, and in the temperature raising process, the atmosphere oxidation degree is set lower than that in the soaking process. In this way, a method for controlling oxidation is proposed.
JP-A-7-41861 discloses that the amount of SiO _{2 in} the oxide after decarburization annealing is set by setting the atmospheric oxidation degree in the intermediate annealing to a range of 0.4 to 2.0 and controlling the preferential oxidation of Si. A method for stabilizing the above has been proposed.
[0008]
[Problems to be solved by the invention]
However, even when the above technology is applied, if the surface condition of the steel plate before intermediate annealing or before decarburization annealing varies, the subscale quality after decarburization annealing varies, and additional oxidation occurs during final finish annealing. In some cases, the electromagnetic characteristics are deteriorated.
The present invention advantageously solves the above-mentioned problem, and effectively suppresses the variation in subscale quality after decarburization annealing to obtain a forsterite insulating coating film that is uniform and excellent in adhesion after finish annealing. It is an object of the present invention to propose a novel method for producing a grain-oriented electrical steel sheet that can obtain good electromagnetic characteristics.
[0009]
[Means for Solving the Problems]
The elucidation process of the present invention will be described below.
As described above, even if the decarburization annealing conditions are appropriately controlled in advance, if the surface state of the steel plate before intermediate annealing or before decarburization annealing varies, the subscale quality varies, As a result, electromagnetic characteristics may deteriorate.
Therefore, the inventors have confirmed that the subscale generation status in the decarburization annealing stage of the product plate that has finally deteriorated the magnetic properties due to the change in the subscale quality, and the subscale quality does not change and is finally good. We investigated the difference in the generation of subscales in the decarburization annealing stage of the product plate with magnetic properties.
[0010]
Figures 1 (a) and 1 (b) compare the subscale cross sections of the decarburized and annealed sheet that ultimately caused the deterioration of the magnetic properties and the decarburized and annealed sheet that finally obtained good magnetic properties. , Schematically.
As shown in Fig. 2 (b), in the decarburized annealed plate that finally obtained good magnetic properties, SiO ₂ was uniformly formed from the surface to the inside of the steel plate, whereas finally the magnetic In the decarburized and annealed sheet that deteriorated the characteristics, a SiO ₂ -deficient layer was formed immediately below the surface layer of the steel sheet, as shown in FIG.
[0011]
Thus, not uniform SiO ₂ is formed during decarburization annealing, by depletion layer of SiO ₂ is produced directly under the surface layer of the steel sheet, why the film formation and thus the electromagnetic characteristics deteriorate is considered as follows .
That is, the annealing separator mainly composed of MgO, which is one of the raw materials of the forsterite coating, is applied to the steel sheet as a slurry suspended in water, so that the physically adsorbed H ₂ O remains after drying. In addition to holding it, it partially hydrates and changes to Mg (OH) ₂ , so it keeps releasing H ₂ O in a small amount up to about 800 ° C during finish annealing. For this reason, the steel sheet surface is subjected to so-called additional oxidation by the H ₂ O. When this additional oxidation is large, not only the forsterite production rate is suppressed, but also the oxidation and decomposition of the inhibitor are promoted.
As shown in FIG. 1 (a), when a SiO ₂ deficient layer is present immediately below the surface layer of the steel sheet, it is considered that such additional oxidation increases, and as a result, the film characteristics and magnetic characteristics are deteriorated. .
[0012]
In particular, in grain-oriented electrical steel sheets using AlN as an inhibitor, the SiO ₂ deficient layer immediately below the surface layer of this steel sheet affects the de-N-behavior during finish annealing or the N-penetration behavior of the steel from the annealing atmosphere. It is thought that the magnetic properties are also affected through the action of. That is, as de-N progresses, the inhibitor's suppressive power is weakened, and the magnetic properties deteriorate. On the other hand, when the penetration N proceeds too much, the inhibitor becomes too strong and normal secondary recrystallization hardly occurs, and this also leads to deterioration of characteristics.
[0013]
Therefore, whether in order to obtain good film characteristics and magnetic characteristics, although not important to not to generate such a SiO ₂ depletion layer, and generated such a SiO ₂ depletion layer during decarburization annealing Taking a sample for each coil and conducting a cross-sectional investigation takes a lot of time and is not practical.
Therefore, a simple method that can accurately grasp the presence or absence of a SiO ₂ deficient layer after decarburization annealing was investigated. As a result, it was found that the surface reflection infrared absorption spectrum method (FT-IR method) is advantageously adapted as such a determination method.
That is, according to this FT-IR method, the existence state of the substance in the outermost layer of the steel sheet can be evaluated. For example, as shown in FIG. 2, SiO ₂ and other substances (firelight etc.) are formed in the outermost layer of the steel sheet. ), The SiO ₂ peak is a, and the peaks of other substances are b, and the production ratio of SiO ₂ can be obtained by a / (a + b) × 100 (%).
[0014]
FIG. 3 shows a comparison of SiO ₂ generation ratios measured by the FT-IR method for a decarburized annealed plate having a SiO ₂ -deficient layer and a decarburized annealed plate having no SiO ₂ -deficient layer.
As shown in the drawing, SiO ₂ production ratio by FT-IR measurements, SiO ₂ depletion layer decarburization annealing it is rather small decarburization annealed sheet with no SiO ₂ depletion layer than plate having a 70% or less It has become.
[0015]
Next, Fig. 4 shows the results of examining the relationship between the SiO ₂ production ratio and the magnetic flux density B ₈ of the final product plate by FT-IR measurement of the decarburized annealed plate. It has been found that excellent electromagnetic characteristics of B ₈ of 1.895 (T) or more can be obtained when the SiO ₂ production ratio is 70% or less.
[0016]
From the results shown in FIGS. 3 and 4, in order to obtain excellent coating properties and electromagnetic properties in the final product plate, the SiO ₂ generation ratio by the FT-IR measurement should be 70% or less, and the SiO ₂ deficient layer immediately below the surface layer of the steel plate. It was found that it is important to suppress the production of.
[0017]
Therefore, as a result of intensive investigations on means for suppressing the formation of SiO ₂ deficient layers immediately below the surface layer of the steel sheet, an appropriate amount of Si, which is the SiO ₂ generation nucleus, was electrodeposited on the steel sheet surface during electrolytic degreasing. In addition, the atmospheric oxidation degree [P (H ₂ 0) / P (H ₂ )] in the temperature raising process of decarburization annealing is set to a relatively high value so that the surface of the steel plate is exposed to the extreme surface at an early stage of decarburization annealing. It was found that it is extremely effective to form a thin and dense SiO ₂ layer.
In other words, if an extremely thin SiO ₂ layer is formed on the outermost surface of the steel sheet in the initial stage of decarburization annealing, in the subsequent soaking process, immediately below the surface layer due to forced oxidation of the steel sheet surface layer part by oxygen in the atmosphere It has been found that the diffusion of Si from the region to the surface layer is suppressed, and as a result, the formation of the SiO ₂ -deficient layer in the region immediately below the surface layer is effectively prevented.
[0018]
FIG. 5 shows the effect of the amount of electrodeposited Si during electrolytic degreasing and the degree of atmospheric oxidation [P (H ₂ 0) / P (H ₂ )] in the temperature raising process of decarburization annealing on the formation of SiO ₂ deficient layers. The results of the investigation are summarized and shown. In addition, the presence or absence of the generation of SiO ₂ deficient layer shall be judged by the generation ratio of SiO ₂ by FT-IR measurement. If this SiO ₂ generation ratio is 70% or less, the SiO ₂ deficient layer is not generated. Can think.
As shown in the figure, the amount of electrodeposited Si during the electrolytic degreasing treatment is controlled in the range of 0.10 to 0.45 kcps as measured by fluorescent X-ray, and the degree of atmospheric oxidation [P ( By setting H ₂ 0) / P (H ₂ )] to 0.45 or more, the SiO ₂ generation ratio by FT-IR measurement of the decarburized and annealed plate can be reduced to 70% or less. It was possible to effectively suppress the formation of _2- deficient layers.
The present invention is based on the above findings.
[0019]
That is, the gist configuration of the present invention is as follows.
1. After hot rolling the silicon-containing steel slab, after cold rolling at least once with intermediate or intermediate annealing to the final sheet thickness, and then electrodepositing Si on the steel sheet surface by electrolytic degreasing In producing a grain-oriented electrical steel sheet through a series of processes for performing final carbonization annealing after decarburization annealing,
Steel sheet after decarburization annealing by adjusting the amount of Si electrodeposition in the electrolytic degreasing process and adjusting the atmospheric oxidation [P (H ₂ 0) / P (H ₂ ) ] in the temperature raising process of the decarburization annealing in the surface, the production method of the oriented electrical steel sheet towards you and controlling the SiO ₂ generation ratio from 32 to 70% in the oxide formed on the surface layer.
[0020]
2. In the electrolytic degreasing treatment in 1 above, an amount of Si corresponding to 0.10 to 0.45 kcps in intensity measured by fluorescent X-rays is electrodeposited on the surface of the steel plate, and the atmospheric oxidizability in the temperature rising process of the decarburization annealing [P (H ₂ 0) / P method for producing oriented electrical steel sheets towards you, characterized in that (H _2)] is referred to as 0.45 to 0.7.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the preferred component composition of the grain-oriented electrical steel sheet targeted by the present invention will be described. As the starting silicon-containing steel, any conventionally known component composition can be used. The typical composition is as follows.
C: 0.01-0.10mass%
C is a component useful not only for uniform refinement of the structure during hot rolling and cold rolling, but also for the development of goth-oriented grains, and is preferably added in an amount of at least 0.01 mass%. However, if the content exceeds 0.10 mass%, the Goth orientation is disturbed. Therefore, the upper limit is preferably about 0.10 mass%.
[0022]
Si: 2.0 to 5.5 mass%
Si increases the specific resistance of the steel sheet and contributes effectively to the reduction of iron loss. However, if the content exceeds 5.5 mass%, the cold-rolling property is impaired. In addition, since the crystal orientation is randomized by the α-γ transformation during the high-temperature final finish annealing performed for secondary recrystallization and purification, a sufficient iron loss improvement effect cannot be obtained. It is preferably about mass%.
[0023]
Mn: 0.02-2.5 mass%
Mn needs to contain at least about 0.02 mass% in order to prevent hot embrittlement, but if it is too much, the magnetic properties are deteriorated, so the upper limit is preferably limited to about 2.5 mass%. Moreover, MnS and MnSe can be precipitated as an inhibitor with a content in this range.
[0024]
The presence of an inhibitor that precipitates uniformly and finely in the steel prior to the secondary recrystallization is indispensable for highly accumulating crystal grains aligned in the Goss direction by secondary recrystallization. As this inhibitor, there are a precipitate type such as so-called MnS, Cu _{2 -X} S, MnSe, Cu _{2 -X} Se and AlN, and a grain boundary segregation type such as Sn, As and Sb.
[0025]
MnS of precipitates _{type, Cu 2-X S, MnSe} , in the case of Cu _2-X Se system, S, 1 kind of Se or two: 0.005 ~0.06mass%
Both S and Se are useful components as inhibitors for controlling secondary recrystallization of grain-oriented electrical steel sheets. From the standpoint of securing such a suppressive force, at least about 0.005 mass% is required, but if it exceeds 0.06 mass%, the effect is impaired, so the lower and upper limits should be about 0.005 mass% and 0.06 mass%, respectively. desirable.
Moreover, when using Cu as an inhibitor component, it is desirable that the amount of Cu is about 0.005 to 0.50 mass%.
[0026]
In the case of AlN, Al: 0.005 to 0.10 mass%, N: 0.004 to 0.015 mass%
For even range of the content of Al and N, MnS described _{above, Cu 2-X S, MnSe} , for the same reason as in the case of Cu _2-X Se system, it is preferable ranges described above. Here, MnS described _{above, Cu 2-X S, MnSe} , Cu 2-X Se system and AlN system may be more desirable combination, respectively.
[0027]
Further, as the grain boundary segregation inhibitor, Sn and Sb are preferably about Sn: 0.01 to 0.25 mass% and Sb: 0.005 to 0.15 mass%, respectively, and these inhibitor components may be used alone or in combination. good. The upper limit of these is because if the addition exceeds this value, the saturation magnetic flux density is lowered and good magnetic properties cannot be obtained.
Further, conventionally known Cr, Te, Ge, As, Bi, P, etc. can be added for improving the magnetic characteristics. These preferred ranges are preferably Cr: 0.01 to 0.15 mass%, Te, As, Ge and Bi: 0.005 to 0.1 mass%, and P: 0.01 to 0.2 mass%. Each of these inhibitor components may be used alone or in combination.
[0028]
Next, typical production conditions for the grain-oriented electrical steel sheet will be described.
The silicon-containing steel slab used as a raw material is one that is continuously cast or one that is subjected to partial rolling from an ingot, but it goes without saying that the slab that has been pre-rolled after continuous casting is also included in the object.
[0029]
In the silicon-containing steel slab, the inhibitor needs to be solutionized by heat treatment of the slab. In the present invention, the conditions for solution treatment are not particularly limited, but it is preferable to heat at a temperature equal to or higher than the solubility product of each inhibitor component for 5 minutes or more by a gas furnace or an induction electric furnace or a combination of both. . Moreover, it is also possible to refine the slab structure after heating by reducing the pressure by 20% or less during heating or before heating. The slab after heating is subjected to normal rough rolling to form a sheet bar, and then subjected to hot finish rolling. Then, hot-rolled sheet annealing is performed as necessary.
[0030]
When performing the cold rolling method twice after the hot-rolled sheet annealing, the first cold rolling is performed at a reduction ratio of about 5 to 50%. Next, after the intermediate annealing, the final cold rolling is performed to the target sheet thickness, but the final cold rolling is improved by improving the texture of primary recrystallization by warm rolling or aging between passes as is well known. since that is possible to adopt a manufacturing method of the present invention to obtain better results. Needless to say, the cold rolling method may be performed once.
After the final cold rolling, it is possible to perform a process of providing a linear groove on the surface of the steel plate for magnetic domain fragmentation as is well known.
[0031]
The steel sheet having the final thickness by the above method is subjected to decarburization and primary recrystallization annealing after electrolytic degreasing treatment.
First, in the electrolytic degreasing treatment, it is important to electrodeposit an amount of Si corresponding to 0.10 to 0.45 kcps (kiro count per second) as measured by fluorescent X-rays on the surface of the steel sheet.
This is because if the amount of electrodeposited Si is less than 0.10 kcps as measured by fluorescent X-rays, it is extremely thin and dense on the outermost layer of the steel sheet even if the temperature rise treatment is performed under appropriate conditions in the subsequent decarburization annealing. This is because a SiO ₂ layer cannot be formed, and if it exceeds 0.45 kcps, the formation of SiO _{2 on} the outermost layer proceeds excessively, and a SiO ₂ deficient layer is formed immediately below the surface layer.
[0032]
Here, as the means for adjusting the amount of electrodeposited Si, adjustment of the amount of electricity during the electrolytic degreasing treatment is effective. Although the amount of electricity for electrolytic degreasing varies somewhat depending on the bath composition, the amount of electricity is preferably about 1.8 A / dm ² or less in order to obtain the preferred amount of electrodeposited Si.
As for the bath composition, it is preferable to use an alkaline aqueous solution containing sodium silicate, and alkali metal silicates such as potassium silicate and lithium silicate may be used instead of soda.
The concentration is preferably about 0.5 to 15 mass%, more preferably 1.0 to 8.0 mass%.
[0033]
Next, decarburization and primary recrystallization annealing are performed, and the degree of atmospheric oxidation [P (H ₂ 0) / P (H ₂ )] in the temperature rising process of decarburization annealing is set to 0.45 or more.
This is because if the degree of atmospheric oxidation [P (H ₂ 0) / P (H ₂ )] is less than 0.45, even if an appropriate amount of Si is electrodeposited during the electrolytic degreasing treatment, the decarburization annealing is increased. This is because an extremely thin and dense SiO ₂ layer cannot be formed on the outermost surface layer of the steel sheet during the temperature process.
On the other hand, when the atmosphere of oxidation in the Atsushi Nobori process is more than 0.7, FeO inhibits the formation of generating and dense SiO ₂ layer, the protective subscales is deteriorated, the upper limit is made 0.7 it Is preferred.
The degree of atmospheric oxidation [P (H ₂ 0) / P (H ₂ )] at the time of soaking is preferably about 0.2 to 0.7 as in the prior art.
[0034]
After the above decarburization annealing, an annealing separator is applied to the steel sheet surface and dried, followed by final finish annealing. This final finish annealing may be performed according to conventionally known conditions.
Next, after removing the unreacted annealing separator, an insulating coating is applied to the surface of the steel sheet to obtain a product, but if necessary, the surface of the steel sheet may be mirrored before applying the insulating coating, A tension coating may be used as the insulating coating. Moreover, you may perform the application | coating baking process of coating also with the planarization process.
Furthermore, in order to obtain the iron loss reduction effect, the steel sheet after the secondary recrystallization is subjected to a known magnetic domain refinement process, that is, a plasma jet or laser irradiation is applied to the linear region, or a linear dent region by a protruding roll is provided. It is also possible to perform processing to be provided.
[0035]
【Example】
C: 0.041 mass%, Si: 3.21 mass%, Mn: 0.070 mass% and Se: 0.021 mass%, and the balance is hot-rolled with a silicon steel slab having a composition of Fe and inevitable impurities, Subsequently, a cold-rolled sheet having a thickness of 0.23 mm was obtained by cold rolling twice with intermediate annealing.
Next, electrolytic degreasing treatment was carried out under various amounts of electrolytic electricity in an electrolytic bath containing 1 to 10 mass% of sodium orthosilicate (Na ₄ SiO ₄ ) and 0.5 mass% of surfactant. Then, various amounts of Si were electrodeposited on the surface of the steel plate.
Next, decarburization treatment was performed by varying the degree of atmospheric oxidation [P (H ₂ 0) / P (H ₂ )] in the temperature raising process as shown in Table 1. The degree of atmospheric oxidation [P (H ₂ 0) / P (H ₂ )] in the soaking process was kept constant at 0.5.
After the above decarburization annealing, an annealing separator containing MgO as a main component was applied, wound around a coil, and then subjected to finish annealing at 850 ° C. for 70 hours in a hydrogen atmosphere.
[0036]
The results of examining the electromagnetic characteristics of the product plate thus obtained are shown in relation to the amount of electrodeposited Si during electrolytic degreasing and the degree of atmospheric oxidation [P (H ₂ 0) / P (H ₂ )] during the temperature rising process. Table 1 shows.
In addition, the results of examining the coating properties of the product plate are also related to the amount of electrodeposited Si during electrolytic degreasing and the degree of atmospheric oxidation [P (H ₂ 0) / P (H ₂ )] during the temperature rising process. Table 1 shows. The coating properties were evaluated by coating adhesion (minimum diameter of a steel bar that does not cause peeling of the coating when wound on a steel bar).
[0037]
[Table 1]

[0038]
As shown in Table 1, according to the present invention, during electrolytic degreasing, the surface of the steel sheet was electrodeposited with an amount of Si corresponding to 0.10 to 0.45 kcps in intensity measured by fluorescent X-ray, and the decarburization annealing temperature rising process By making the atmospheric oxidation degree [P (H ₂ 0) / P (H ₂ )] at 0.45 or more and the SiO ₂ production ratio in the surface layer oxide at 70% or less, it is possible to combine excellent film characteristics and electromagnetic characteristics. Obtainable.
Incidentally, according to the present invention, the steel sheet after decarburization annealing of excellent coating properties and electromagnetic properties obtained product sheet has been investigated for the presence of SiO ₂ depletion layer, invention examples Both the SiO ₂ depletion layer occurs Has not been confirmed.
[0039]
【The invention's effect】
Thus, according to the present invention, it is possible to effectively prevent the formation of a SiO ₂ deficient layer during decarburization annealing, and to stably obtain a grain-oriented electrical steel sheet having excellent coating properties and magnetic properties. Target value is extremely high.
[Brief description of the drawings]
FIG. 1 shows a comparison of subscale cross sections of a decarburized and annealed sheet (a) that ultimately deteriorated magnetic properties and a decarburized and annealed sheet (b) that finally achieved good magnetic properties. FIG.
FIG. 2 is a diagram showing a calculation procedure of a SiO ₂ generation ratio by FT-IR measurement.
FIG. 3 is a diagram showing a comparison of SiO ₂ production ratios measured by the FT-IR method for a decarburized annealed plate having a SiO ₂ -deficient layer and a decarburized annealed plate having no SiO ₂ -deficient layer.
FIG. 4 is a graph showing the relationship between the SiO ₂ production ratio by FT-IR measurement of a decarburized annealed plate and the magnetic flux density B ₈ of the final product plate.
[Fig. 5] Effect of electrodeposited Si amount during electrolytic degreasing and the degree of atmospheric oxidation [P (H ₂ 0) / P (H ₂ )] in the temperature rise process of decarburization annealing on the formation of SiO ₂ deficient layers It is the graph which showed.

Claims (2)

After hot rolling the silicon-containing steel slab, after cold rolling at least once with intermediate or intermediate annealing to the final sheet thickness, and then electrodepositing Si on the steel sheet surface by electrolytic degreasing In producing a grain-oriented electrical steel sheet through a series of processes for performing final carbonization annealing after decarburization annealing,
Steel sheet after decarburization annealing by adjusting the amount of Si electrodeposition in the electrolytic degreasing process and adjusting the atmospheric oxidation [P (H ₂ 0) / P (H ₂ ) ] in the temperature raising process of the decarburization annealing in the surface, the production method of the oriented electrical steel sheet towards you and controlling the SiO ₂ generation ratio from 32 to 70% in the oxide formed on the surface layer. In the electrolytic degreasing treatment according to claim 1, an amount of Si corresponding to 0.10 to 0.45 kcps measured by fluorescent X-rays is electrodeposited on the surface of the steel sheet, and the atmospheric oxidation property in the temperature raising process of the decarburization annealing P (H ₂ 0) / P method for producing oriented electrical steel sheets towards you, characterized in that (H _2)] is referred to as 0.45 to 0.7.

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