JPH11310882A - Ultralow iron loss grain oriented silicon steel sheet and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably produce an ultralow iron loss grain oriented silicon steel sheet exceedingly low in iron loss and moreover excellent in magnetostriction characteristics at a low cost. SOLUTION: In a grain oriented silicon steel sheet of 0.05 to 0.5 mm sheet thickness provided with a tensile insulating film essentially consisting of a phosphate and colloidal silica on the surface and subjected to finish annealing, on the boundary between the surface of the steel sheet and the tensile insulating film, an extra thin base film in which the nitrides ore oxides of one or >= two kinds selected from Fe, Si, Al and B are finely dispersed into the film components the same as those in the tensile insulating film is interposed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-low iron loss unidirectional silicon steel sheet and a method for producing the same, and more particularly, to a method of finishing annealed silicon steel sheet having a surface or a linear concave region of the finish annealed silicon steel sheet. The surface is coated with a tensile insulating film via an ultra-thin undercoating film in which one or more kinds of nitrides / oxides selected from Fe, Si, Al and B are finely dispersed in the film components. By doing so, it is intended to improve the adhesion of the coating film, and to further improve the iron loss characteristics at the same time as improving the compression stress characteristics of magnetostriction and at a low cost.

[0002]

BACKGROUND ART grain oriented silicon steel sheet is mainly being used as transformer cores and other electrical equipment, (represented by ₈ value B) flux density as the magnetization characteristic is high, the iron loss (W
_17/50 ) is required to be low.

In order to improve the magnetic properties of a grain-oriented silicon steel sheet, it is necessary to first align the <001> axis of the secondary recrystallized grains in the steel sheet in the rolling direction, and secondly, to make the final It is necessary to minimize impurities and precipitates remaining in the product.

[0004] For this reason, since NPGoss proposed a basic manufacturing technique by two-stage cold rolling of a grain-oriented silicon steel sheet, a number of improvements have been made to the technique, and the magnetic flux density and the density of the grain-oriented silicon steel sheet have been improved. Iron loss values have improved over the years. Among them, the most typical ones are Sb and MnSe or
JP-B-51-13469 using MnS as an inhibitor, and JP-B-33-4710 and JP-B-40-156 using AlN and MnS as inhibitors.
The method according to 44 JP and Sho 46-23820 Patent Publication, according to these methods B ₈ is now the product is obtained having a high magnetic flux density exceeding 1.88T.

In order to obtain a product having a higher magnetic flux density, Japanese Patent Publication No. 577-14737 discloses a method in which Mo is added to a material in a complex manner.
In Japanese Patent Publication No. 62-42968, Mo is added to the material in a complex manner, and then the quenching treatment is applied after intermediate annealing immediately before the final cold rolling, so that B ₈ has a high magnetic flux density of 1.90 T or more. And iron loss W _17/50 is 1.05 W / kg (product thickness: 0.30m
m) It is disclosed that the following low iron loss can be obtained, but there is still room for improvement in sufficiently reducing iron loss.

[0006] In particular, the demand for reducing power loss as much as possible after the energy crisis of more than ten years ago has been remarkably increased, and accordingly, further improvements in the use of iron core materials are desired. Therefore, in order to minimize eddy current loss, the product thickness was reduced.
Many of those having a thickness of 23 mm (9 mil) or less have come to be used.

[0007] Apart from this, improvements have also been made from the standpoint of insulating coatings on unidirectional silicon steel sheets. In other words, silicon steel sheets currently being commercialized can reduce iron loss by applying tension to the steel sheet by utilizing the difference in the coefficient of thermal expansion between the steel sheet surface and the insulating coating on the forsterite-based undercoat. Magnetostriction is improved. As a typical method of forming an insulating film, a method using a coating solution containing aluminum phosphate, colloidal silica and chromic anhydride as main components disclosed in Japanese Patent Publication No. 53-28375, and Japanese Patent Publication No. 56-28375. No. 52117 discloses a method using a coating solution containing magnesium phosphate, colloidal silica and chromic anhydride as main components.

[0008] All of the above-mentioned techniques are mainly metallurgical techniques, but apart from these methods, Japanese Patent Publication No. 57-2252
Irradiation of laser or plasma on the surface of the steel sheet after finish annealing as proposed in Japanese Patent Publication (B. Fukuda, K. Sato,
T.Sugiyama, A.Honda and Y.Ito: Proc. Of ASM Con.
of Hard and Soft Magnetic Materials, 8710-008, (US
A), (1987)), and a method for reducing iron loss by artificially reducing the magnetic domain width by 180 ° (magnetic domain refinement technology) was developed. With the development of this technology, the iron loss of the grain-oriented silicon steel sheet has been significantly reduced. However, this technique has a disadvantage that it cannot withstand annealing at high temperatures, and has a problem that its application is limited to a laminated iron core transformer that does not require strain relief annealing.

In this regard, as a domain refining technique capable of withstanding strain relief annealing, a linear groove is introduced into the surface of a steel sheet after finish annealing of a unidirectional silicon steel sheet, and the demagnetizing effect by the groove is applied to the magnetic domain. Has been industrialized to subdivide the technology (H. Kobayashi,
E.Sasaki, M.Iwasaki and N.Takahashi: Proc.SMM-
8., (1987), P.402). Separately, a method has been developed in which a final cold-rolled sheet of unidirectional silicon steel sheet is subjected to local electrolytic etching to form grooves and subdivide magnetic domains (Japanese Patent Publication No. 8-6140). , Has been industrialized.

Further, apart from the above-described method for producing a silicon steel sheet, as disclosed in JP-B-55-19976, JP-A-57-127749 and JP-A-2-3213,
Amorphous alloys are receiving attention as materials for ordinary power transformers and high-frequency transformers. However, such an amorphous material can provide extremely excellent iron loss characteristics as compared with a normal unidirectional silicon steel sheet, but lacks thermal stability, has a low space factor, and is easy to cut. However, since it is too thin and brittle, there are many practical disadvantages such as a large increase in the cost of assembling the transformer, so that it has not been used in large quantities at present.

[0011] In addition, Japanese Patent Publication No. 52-24499 discloses that a forsterite undercoat formed after finish annealing of a silicon steel sheet is removed, the steel sheet surface is polished, and then the metal surface is plated with metal. A method has been proposed. However, this method has a disadvantage that although a low iron loss can be obtained at a low temperature, the metal is diffused into the silicon steel sheet when subjected to a high temperature treatment, so that the iron loss is rather deteriorated.

In this regard, the inventors have previously disclosed in Japanese Patent Publication No. 63-54767 and the like, as solutions to the above disadvantages.
Si, Mn, Cr, Si, Mn, Cr, etc. are applied on a grain-oriented silicon steel sheet by dry plating (PVD) such as CVD, ion plating and ion implantation.
Ni, Mo, W, V, Ti, Nb, Ta, Hf, Al, Cu, Zr and B
It has been disclosed that an ultra-low iron loss can be obtained by forming one or two or more kinds of tension films selected from nitrides and carbides. This manufacturing method has made it possible to obtain extremely excellent iron loss characteristics as a material for power transformers and high frequency transformers, but nevertheless, it has sufficiently responded to recent demands for low iron loss. It was hard to be there.

Therefore, the present inventors have made a fundamental reexamination from all viewpoints in order to further reduce iron loss as compared with the prior art. That is, the inventor formed one or two or more kinds of tension films selected from various nitrides and carbides on the surface of a grain-oriented silicon steel sheet smoothed in a stable process to form an ultra-low iron loss. In order to obtain a product of the following, from the recognition that a fundamental review from the raw material composition of the unidirectional silicon steel sheet to the final processing step is necessary, from tracking the texture of the silicon steel sheet, Smoothness of steel sheet surface and final CVD and P
Intensive studies were conducted up to the VD processing step. as a result,
The following findings were obtained.

(1) Even if a thin film of ceramic (a TiN film is used as a representative example) coated on a silicon steel sheet is formed to a thickness of 1.5 μm or more, the degree of improvement in iron loss is reduced. In other words, a TiN film having a thickness of 1.5 μm or more can only expect a slight improvement in iron loss, but rather causes a decrease in space factor and magnetic flux density. (2) In this case, the role of TiN is more important in the role of adhesion to the silicon steel sheet, in addition to the addition of tension specific to ceramic. That is, in the transmission electron microscope observation of the cross section of TiN (see Iguchi, Y .: Journal of the Japan Institute of Metals, 60 (1996), pp. 781-786), horizontal stripes of 10 nm are observed, which are caused by the [011] -Corresponds to a 5-atomic layer of Fe atoms. (3) Simultaneous measurement of texture of two layers by X-ray in TiN coating area and chemical polishing area (Y. Inokuti: ISIJ Internationala)
l, 36 (1996), pp. 347-352).
The {200} peak shape is circular. However, the shape of the {200} peak of Fe in the TiN coating region is elliptical, and the silicon steel sheet is strongly tensioned in the [100] _si-steel direction. (4) Tension of TiN thin film (Ichio Iguchi, Kazuhiro Suzuki, Yasuhiro Kobayashi:
Journal of the Japan Institute of Metals, 60 (1996), p.674-678)
At 10 MPa, an improvement in magnetic flux density of about 0.014 to 0.016 T can be expected. (This is equivalent to increasing the degree of Goss orientation integration by about 1 °.)

The above is new findings on ceramic coating. Further, the following findings concerning the surface condition of the ceramic film and the steel sheet have been obtained. (5) When the final cold-rolled silicon steel sheet is subjected to local electrolytic etching to form grooves, and after the secondary recrystallization treatment, the steel sheet surface is smoothed by polishing and then coated with a TiN ceramic film In addition, in addition to the magnetic domain segmentation caused by the demagnetizing field effect caused by the introduced grooves, the core loss is effectively reduced by the addition of tension by the ceramic coating. (6) The effect of reducing iron loss by tension when a concave groove is formed on the surface of a steel sheet before ceramic coating is greater than that of a silicon steel sheet smoothed by ordinary polishing (Japanese Patent Publication No. 3-32889). Gazette). That is, when grooves are introduced, different tension acts on the surface of the silicon steel sheet, and the degree of reduction in iron loss due to tensile tension increases. (7) When the ceramic film is coated on the silicon steel plate having the concave grooves, the effect of reducing iron loss is more effective than the case where the ceramic film is smoothed by ordinary polishing and coated with the ceramic film. In other words, it is more effective to introduce a linear groove and subdivide the magnetic domain by applying the demagnetizing effect of the groove, and then form a ceramic tension coating and further subdivide the 180 ° main domain. And extremely low iron loss. (8) If grooves are formed by performing local electrolytic etching on the final cold-rolled sheet of silicon steel sheet, the surface of the steel sheet after the secondary recrystallization treatment is not smoothed by polishing and the TiN ceramic Even when a film is formed, a considerable iron loss reduction effect is exhibited. In other words, even when the surface is not smoothed by polishing, for example, even when there are small irregularities on the surface due to pickling treatment or the like, a strong tension is applied to the surface of the silicon steel sheet by coating the ceramic film having a small coefficient of thermal expansion. It is possible to add, and thereby the iron loss can be advantageously reduced.

Therefore, based on the above-mentioned new findings, the inventor repeated numerous experiments and studies in order to achieve the intended purpose, and as a result, introduced a silicon steel sheet having a smooth surface and linear grooves. Regardless of the silicon steel sheet, it is possible to reduce the iron loss by using a plurality of types of ceramic tension coatings formed on the surface of the silicon steel sheet, and reducing the coefficient of thermal expansion of the ceramic tension coating as it goes outward. Was found to be extremely effective, and based on this, a unidirectional silicon steel sheet with extremely low iron loss was newly developed (Japanese Patent Application No. 9-328042).
Specification).

The thus obtained grain-oriented silicon steel sheet has an extremely thin ceramic film having excellent adhesion and a tensile film, and is capable of achieving not only an ultra-low iron loss but also an insulating property. Moreover, since it has an excellent space factor, it can be said that it is an ideal silicon steel sheet.

[0018]

However, in order to form such a dense ceramic film, processing in a plasma atmosphere in a high vacuum is indispensable. In such a method, high-speed formation of the ceramic film is required. Since a film could not be formed and the productivity was low, there was a problem that the cost would increase when industrialized.

In addition, separately from this, recently, Patent No. 26624
Nos. 82 and 2664326 each propose a low iron loss unidirectional silicon steel sheet having improved coating adhesion and iron loss by forming a composite film of Al oxide-B oxide on the surface of a smoothed steel sheet. Was done. However, the iron loss value W _17/50 of the silicon steel sheet by this method is 0.77 to
It is only about 0.83 W / kg, and it cannot be said that there is still room for improvement with this ultimate iron loss value despite the small product plate thickness. Further, it has been pointed out that the insulating coating of this silicon steel sheet has insufficient chemical stability and has problems in corrosion resistance and water resistance.

[0020]

Therefore, based on the above-mentioned new findings, the present inventors have again examined the surface condition of the silicon steel sheet and the tension insulating film formed on the surface. At that time, improvement of the compressive stress characteristic of magnetostriction (hereinafter, simply referred to as magnetostriction characteristic) was also studied. Here, the magnetostriction of a silicon steel sheet is a phenomenon in which the steel sheet expands and contracts and vibrates when the steel sheet is magnetized, and is the largest cause of transformer noise.

This magnetostrictive behavior is caused by the fact that the magnetization process of the steel sheet includes 90 ° domain wall movement and rotational magnetization, and the magnetostriction increases in accordance with the compressive stress applied to the steel sheet. When assembling the transformer, compressive stress is inevitably applied to the steel plate.
Pre-tensioning the steel sheet is advantageous in terms of magnetostriction characteristics. Of course, the addition of tension to the steel sheet effectively contributes to the improvement of the iron loss of the grain-oriented silicon steel sheet. Conventionally, grain-oriented silicon steel sheets have a sub-scale (SiO ₂ ) formed on the steel sheet surface during decarburization and primary recrystallization annealing before secondary recrystallization, and MgO.
Forsterite-based undercoat formed by high-temperature reaction during finish annealing with an annealing separator mainly composed of iron and a tensile insulating coating mainly composed of phosphate and colloidal silica formed thereon Thus, the tension is applied to improve the magnetostriction characteristics, but such a conventional method cannot provide a sufficiently satisfactory improvement in the magnetostriction characteristics.

As a result of the above study, prior to forming a tension insulating film mainly composed of phosphate and colloidal silica on the surface of a silicon steel sheet, the coating solution for the tension insulating film was diluted with water. And Fe, Si,
A thin coating of a treatment solution containing an inorganic compound containing one or more selected from Al and B is applied, and a small amount of an inorganic compound containing Fe or the like is attached to the surface of the steel sheet. When a short heat treatment is performed in the film, an ultrathin film basically having the same film component as the tensile insulating film is formed, and the inorganic compound containing Fe and the like present in the film has high activity. As a result, the ultra-thin film is formed on the steel surface with high adhesion, while the ultra-thin film is formed thereon. Since they are of the same quality as the tensile insulation coating, their adhesion is also very good, and as a result, a tension insulation coating with much better adhesion than before can be formed on the steel sheet surface. Thus, extremely low iron loss and excellent magnetostriction characteristics The grain-oriented silicon steel sheet, with good productivity,
The knowledge that it can be manufactured at low cost was obtained. The present invention is based on the above findings.

That is, the gist of the present invention is as follows. 1. A finish-annealed unidirectional silicon steel sheet having a thickness of 0.05 to 0.5 mm and having a tension insulating coating mainly composed of phosphate and colloidal silica on its surface, wherein an interface between the steel sheet surface and the tensile insulating coating is provided. And an ultra-thin undercoat in which one or more nitrides or oxides selected from the group consisting of Fe, Si, Al and B are finely dispersed in the same coating component as the tensile insulating coating. Ultra-low iron loss unidirectional silicon steel sheet.

2. In the above item 1, on the surface of the steel plate
At a distance of 2 to 10 mm in the direction crossing the rolling direction, width: 50 to
An ultra-low iron loss unidirectional silicon steel sheet having a linear concave area of 500 μm and a depth of 0.1 to 50 μm.

3. The ultra low iron loss unidirectional silicon steel sheet according to 1 or 2, wherein the surface of the finish-annealed unidirectional silicon steel sheet is a surface subjected to a smoothing treatment.

4. The ultra low iron loss unidirectional silicon steel sheet according to 1 or 2 above, wherein the surface of the finish-annealed unidirectional silicon steel sheet is an as-picked surface that is not subjected to a smoothing treatment.

5. A coating solution for a tensile insulating coating mainly composed of phosphate and colloidal silica is diluted with water on the surface of a finish-annealed unidirectional silicon steel sheet having a thickness of 0.05 to 0.5 mm, and By applying and drying a treatment liquid containing a small amount of an inorganic compound containing one or more selected from Fe, Si, Al and B, a small amount of Fe, Si, Al and B An ultra-low iron loss characterized by applying an inorganic compound containing one or more kinds selected from the above, and then forming a tension insulating film mainly composed of phosphate and colloidal silica according to a conventional method. A method for producing a unidirectional silicon steel sheet.

6. A coating solution for a tensile insulating coating mainly composed of phosphate and colloidal silica is diluted with water on the surface of a finish-annealed unidirectional silicon steel sheet having a thickness of 0.05 to 0.5 mm, and By applying and drying a treatment liquid containing a small amount of an inorganic compound containing one or more selected from Fe, Si, Al and B, a small amount of Fe, Si, Al and B After attaching an inorganic compound containing one or two or more kinds selected from the above, a short-time heat treatment is performed in a non-oxidizing atmosphere, and Fe, Si, Al And B, forming an ultra-thin undercoat in which one or more nitrides or oxides selected from the group consisting of fine particles are dispersed finely, and a tension insulating material mainly composed of phosphate and colloidal silica according to a conventional method. Ultra low iron loss unidirectional silicon steel characterized by forming a coating Plate manufacturing method.

7. In the above 5 or 6, on the surface of the steel plate of the steel sheet, at an interval of 2 to 10 mm in a direction crossing the rolling direction,
A method for producing an ultra-low iron loss unidirectional silicon steel sheet, comprising a linear concave region having a width of 50 to 500 μm and a depth of 0.1 to 50 μm.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. First, the process that led to success according to the present invention will be described. C: 0.067 wt%, Si: 3.38 wt%, Mn:
0.077 wt%, Se: 0.020 wt%, Sb: 0.023 wt%, Al: 0.
021 wt%, N: 0.0078 wt% and Mo: 0.012 wt%, the remainder being a silicon steel continuous cast slab having substantially the composition of Fe, heat-treated at 1340 ° C for 5 hours, and then hot-rolled. This was a hot-rolled sheet having a thickness of 2.0 mm. After subjecting this hot-rolled sheet to uniform annealing at 980 ° C for 3 minutes, intermediate annealing at 1030 ° C is performed.
Rolling was performed twice to obtain a final cold-rolled sheet having a sheet thickness of 0.23 mm.

Thereafter, the final cold rolled sheet was processed as follows. On the surface of the final cold-rolled sheet, an etching resist ink containing an alkyd-based resin as a main component is subjected to gravure offset printing so that a non-applied portion has a width of approximately 200 at right angles to the rolling direction.
The coating was performed so as to remain in a linear shape at a distance of 4 mm and baked at 200 ° C. for 3 minutes. At this time, the resist thickness was 2 μm. By performing electrolytic etching on the steel sheet coated with the etching resist in this way,
A linear groove having a width of 200 μm and a depth of 20 μm was formed, and then immersed in an organic solvent to remove the resist. At this time, the current density in the electrolytic etching was 10 A / d in a NaCl electrolytic solution.
m ² , treatment time: 20 seconds. For comparison, a silicon steel sheet not subjected to these treatments was also prepared.

Thereafter, these and these steel plates were 840
After decarburization and primary recrystallization annealing in wet H ₂ at ℃ C, the steel sheet surface is separated by MgO (15%), Al ₂ O ₃ (75%), CaSiO ₃ (10%) Apply the slurry and then at 850 ° C
After annealing for 15 hours, the temperature was raised from 850 ° C to 1150 ° C at a rate of 12 ° C / h to develop secondary recrystallized grains that were strongly integrated in the Goss orientation, and then purified in dry H ₂ at 1220 ° C. did.

After removing the surface coating of the product thus obtained and then smoothing the surface of the silicon steel sheet by chemical polishing, the following six treatments were performed. (A) A coating solution for a tension insulating film mainly composed of phosphate and colloidal silica: 250 cc diluted with 1500 cc of distilled water, and further added with 50 cc of a SiCl ₄ solution in the diluted solution at 80 ° C. A silicon steel plate was immersed in the solution for 20 seconds, washed with water and dried. (B) Dilute 250 cc of a coating solution for tensile insulation coating mainly composed of phosphate and colloidal silica with 1500 cc of distilled water, and further dilute the solution with 25 cc of SiCl ₄ solution and FeC
l ₃ : A silicon steel sheet was placed in a treatment
It was immersed for 20 seconds, washed with water and dried. (C) tension insulating film coating liquid mainly composed of phosphate and colloidal silica: a 250 cc was diluted with distilled water 1500cc, further SiCl ₄ solution in its diluted solution: 25 cc and AlP0 ₄
· 3 / 2H ₂ O: 25g into the processing liquid of 80 ° C. was added in combination, the silicon steel sheet for 20 seconds immersion, washed with water, and then dried. (D) A coating solution for a tensile insulating film mainly composed of phosphate and colloidal silica: 250 cc is diluted with 1500 cc of distilled water, and further, 20 g of FeCl ₃ and Al (NO ₃ ) are contained in the diluted solution.
20 g, H ₃ BO ₃ : In a treatment liquid at 80 ° C. to which 10 g was added in combination,
A silicon steel plate was immersed for 20 seconds, washed with water and dried. (E) Coating solution for tension insulating coating containing phosphate and colloidal silica as main components: immersing silicon steel sheet for 20 seconds in a treatment solution of 250 cc diluted with 1500 cc of distilled water at 80 ° C., and after washing with water Dried. (F) Treatment at 80 ° C. by diluting 250 cc of a coating solution for tension insulating coating mainly composed of phosphate and colloidal silica with 1500 cc of distilled water, and further adding 50 cc of a SiCl ₄ solution to the diluted solution. A silicon steel plate was immersed in the solution for 20 seconds, washed with water and dried. (G) After finish annealing, oxides on the surface of the silicon steel sheet were removed by pickling. Then (A) for the silicon steel sheet was subjected to treatment of _{~ (E), N 2 (} 50%) + H 2 (50%) 950 ℃ a mixed gas, 10
Heat treatment for a minute. Thereafter, a tensile insulating coating (about 2 μm thick) containing magnesium phosphate and colloidal silica as main components was formed on the surface of the steel sheet (at 800 ° C.).

Table 1 shows the results obtained by examining the magnetic properties and adhesion of each product thus obtained.

[0035]

[Table 1]

As is clear from the results shown in Table 1,
The invention examples of -A to -D, that is, a silicon steel sheet whose surface has been smoothed by chemical polishing, a coating solution for a tension insulating film mainly composed of phosphate and colloidal silica is diluted with distilled water, and further a diluent thereof. After immersion in a processing solution containing a trace amount of an inorganic compound containing Fe, Si, Al, B, etc.,
Annealed in a non-oxidizing atmosphere to finely disperse one or more nitrides / oxides selected from Fe, Si, Al and B in the tensile insulating coating component on the steel sheet surface When an ultra-thin undercoating is applied and then a tensile insulating coating mainly composed of phosphate and colloidal silica is applied according to a conventional method, the iron loss W _17/50 is extremely low at 0.6 W / kg or less. Along with the iron loss, it was possible to obtain an excellent adhesiveness having a diameter of 15 mm or less that does not peel off even after being bent at 180 °.

Further, after applying a diluting solution of a coating solution for a tensile insulating film to which a small amount of -F containing an inorganic compound containing Fe, Si, Al, and B has been added, the subsequent annealing treatment is omitted, and the coating solution is immediately treated immediately. According to the method, even when a tension insulating coating mainly composed of phosphate and colloidal silica is formed, excellent iron loss characteristics and coating adhesion comparable to those of the above-described cases -A to -D are obtained. Was completed.

On the other hand, when a simple diluting solution of a coating solution for a tension insulating film, which does not contain a trace amount of an inorganic compound containing Fe, Si, Al, and B, is used as a treatment solution for the base film of -E. Although a considerable iron loss improving effect can be seen by the smoothing treatment by chemical polishing, it cannot be used as a silicon steel sheet because the adhesion is extremely poor and peeling occurs immediately in a bending test. Further, when the chemical polishing of -G and the subsequent formation of the ultrathin undercoat film were not performed, only the improvement of iron loss improvement by magnetic domain subdivision was performed. Is inferior to

Next, FIG. 1 compares the coating structures of a conventional unidirectional silicon steel sheet (FIGS. 1A and 1B) and a unidirectional silicon steel sheet according to the present invention (FIG. 1C). Shown. Fig. 1 (a)
Is a case where a tension insulating coating mainly composed of phosphate and colloidal silica is simply formed on the surface of a finish-annealed unidirectional silicon steel sheet as disclosed in JP-A-5-311353. However, in this case, the adhesion between the silicon steel sheet and the insulating film becomes a major problem, and it is difficult to use the product as a practical product. FIG. 2B shows an ultra-thin ceramic coating such as TiN or CrN on the surface of a grain-oriented unidirectional silicon steel sheet as disclosed in Japanese Patent Publication No. 63-35686 by CVD or PVD. Is formed, and then a tensile insulating film is further formed on the surface.In this case, although it is very effective in reducing iron loss, as described above, plasma treatment in a high vacuum is required. Since it is necessary, there is a disadvantage that the cost is increased.

On the other hand, in the example of the present invention shown in FIG. 3 (c), a small amount of Fe, S was present at the interface between the unidirectional silicon steel sheet and the tensile insulating film.
The formation of an ultra-thin undercoat in which nitrides and oxides such as i, Al and B are finely dispersed makes it possible to significantly improve the adhesion to silicon steel sheets, and thus more effectively tension the tensile insulation coating. Is considered to be performed. That is, in the present invention, the undercoat is firmly adhered to the silicon steel ground iron by finely dispersing nitride / oxide such as Fe, Si, Al and B in the ultra-thin undercoat. Since the main component of this undercoat is the same as that of the tension insulating film formed thereon, the adhesion between the undercoat and the overcoat tension insulating film is also good. Therefore, by interposing such an undercoat, the overcoat tension is increased. The tension imparting function of the insulating coating can be sufficiently exerted, and as a result, a further iron loss improving effect is achieved. Therefore, this ultra-thin undercoat film has the adhesion between the silicon steel sheet and the tensile insulation film (the role of the binder).
Can be said to be a coating having a gradient functionality.

Here, as the above-mentioned ultra-thin undercoat,
It is important that Fe, Si, Al and B are contained in the film in the form of nitrided oxides.
It is important to use a coating solution for a normal tension insulating film as a diluting solution diluted with water so that inorganic compounds including Fe, Si, Al and B, which are raw materials, are likely to be nitrided or oxide. It is important that the film thickness also satisfies the required thickness and is as thin as possible.

As described above, if the coating solution for the tension insulating film is diluted, Fe, Si, Al contained in the diluted solution is diluted.
Table 2 shows that inorganic compounds such as B and B easily become nitrided / oxide by subsequent heat treatment. Table 2
Is an X-ray photoelectron microscope (X-ray Photoelectron S)
It shows the analysis values of Fe, Si, N, and O on the surface of the silicon steel sheet before the formation of the tensile insulating film, which was measured by using the spectroscopy method (XPS method). A feature is that a large amount of Fe, N, and O are observed, and a large amount of O is also observed despite treatment in a non-oxidizing atmosphere, indicating that Fe is easily bonded to oxygen. Also,
In this case, the amount of Si is slightly increased, which is considered to be due to the inclusion of colloidal silica in the undercoating.

[0043]

[Table 2]

FIG. 2 shows that an ultra-thin undercoating in which Si nitride / oxide is dispersed was formed on the surface of a steel sheet using SiCl ₄ as an inorganic compound such as Fe, Si, Al and B. The results obtained by measuring the oxide composition in the nitrided / oxide in this case by the XPS method are shown. As is clear from the figure, the oxide formed by this method is mainly composed of FeSiO ₃ (Clinoferros
It is noted that ILite) and consist Fe ₂ SiO ₄ (Fayalite) (Strictly speaking, towards the production of FeSiO ₃ is Fe ₂ Si
O ₄ ). Here, it is considered that the above-mentioned oxide is formed by a reaction represented by the following formula: SiCl ₄ + 2H ₂ O + 2FeO → Fe ₂ SiO ₄ + 4HCl. The oxides described above are extremely dense, unlike the conventional SiO ₂ subscale, and such dense oxides are formed together with fine nitrides. It is considered that the adhesion is improved.

As a prior art of this kind, Japanese Patent Application Laid-Open
No. 131976, JP-A-6-184762 and JP-A-9-78252
In each of the publications, there is proposed a method of forming an oxide layer of an external oxidation type SiO ₂ film on a polished silicon steel sheet surface. However, the gist of these methods is a subscale mainly composed of SiO ₂ by a treatment in wet H ₂ at the time of decarburization and primary recrystallization annealing performed to remove harmful carbon of a silicon steel sheet. Is similar to the formation of In particular, the method of utilizing SiO ₂ obtained by such oxidation treatment of a steel sheet,
It has already been pointed out that the effect of reducing the iron loss due to the mirror finishing of the silicon steel sheet is severely killed.

[0046]

The silicon-containing steel used as the material of the present invention is compatible with any of the conventionally known component compositions, but typical compositions are as follows. C: 0.01 to 0.08 wt% If the content of C is less than 0.01 wt%, the suppression of hot rolled texture is insufficient and large elongated grains are formed, thereby deteriorating the magnetic properties. Since it takes a long time to decarburize in the charcoal process and is not economical, it is preferable to set the content to about 0.01 to 0.08 wt%.

Si: 2.0 to 4.0 wt% If the content of Si is less than 2.0 wt%, sufficient electric resistance cannot be obtained, so that eddy current loss increases and iron loss deteriorates.
If the content is more than wt%, brittle cracks are likely to occur during cold rolling, so it is preferable to be in the range of about 2.0 to 4.0 wt%.

Mn: 0.01 to 0.2 wt% Mn is an important component that determines MnS or MnSe as a dispersed precipitation phase that affects secondary recrystallization of a unidirectional silicon steel sheet. If the amount of Mn is less than 0.01% by weight, the absolute amount of MnS or the like necessary for causing secondary recrystallization becomes insufficient, causing incomplete secondary recrystallization and increasing the number of surface defects called blisters. On the other hand, if the content exceeds 0.2 wt%, even if dissociated solid solution of MnS or the like is performed in slab heating or the like, the dispersed precipitate phase precipitated during hot rolling is likely to be coarse, and the optimal size distribution desired as an inhibitor is impaired. Therefore, Mn is preferably set to about 0.01 to 0.2 wt%.

S: 0.008 to 0.1 wt%, Se: 0.003 to 0.1
wt% S and Se are each 0.1 wt% or less, and S is 0.0
Preferably, the content of Se is in the range of 08 to 0.1 wt%, and the content of Se is in the range of 0.003 to 0.1 wt%. The reason is that if these contents exceed 0.1 wt%, the hot and cold workability deteriorates, and if they do not reach the lower limits, respectively, there is no particular effect on the primary grain growth suppressing function as MnS and MnSe. It is. In addition, the composite addition of Al, Sb, Cu, Sn, B and the like, which are conventionally known as inhibitors, does not hinder the effects of the present invention.

Next, the manufacturing process of the ultra-low iron loss unidirectional silicon steel sheet according to the present invention will be described. First, in order to melt the raw material, it is needless to say that an LD converter, an electric furnace, an open hearth furnace, and other known steelmaking furnaces can be used, and vacuum melting and RH degassing can also be used together.

According to the present invention, S, Se contained in the material
Alternatively, as a method of adding a small amount of another primary grain growth inhibitor to molten steel, any conventionally known method may be used. For example, LD converter, RH degassing at the end of molten steel or at the time of ingot casting Can be added. In slab production, it is advantageous to use the continuous casting method because of economic and technical advantages such as cost reduction and uniformity of components or quality in the slab longitudinal direction. It does not hinder.

The continuously cast slab is heated to a temperature of 1300 ° C. or more in order to dissociate and form a solid solution of the inhibitor in the slab. Thereafter, the slab is subjected to hot rough rolling and then hot finish rolling to form a hot-rolled sheet having a thickness of usually about 1.3 to 3.3 mm.

Next, the hot-rolled sheet is subjected to hot-rolled sheet annealing (also referred to as homogenizing annealing) in a temperature range of about 850 to 1100 ° C. as necessary, and then is subjected to one or two cold-pressing steps including intermediate annealing. Rolling is performed to obtain a final thickness, but in order to obtain a product having high magnetic flux density and low iron loss, attention must be paid to the final cold rolling rate (normally 55 to 90%). At this time, the upper limit of the product thickness is 0.5 from the viewpoint of minimizing the eddy current loss of the silicon steel sheet.
mm, and the lower limit of the plate thickness was limited to 0.05 mm in order to avoid the adverse effect of hysteresis loss.

When forming a linear groove on the surface of the steel sheet,
It is particularly advantageous to carry out the process on a steel sheet which has finished the final cold rolling and has a product thickness. That is, on the surface of the final cold-rolled sheet or the steel sheet before and after the secondary recrystallization, the width: 50 to 500 μm, the depth: 0.1 at intervals of 2 to 10 mm in a direction crossing the rolling direction.
That is, a linear concave region of about 50 μm is formed. Here, the interval between the linear concave regions is limited to the range of 2 to 10 mm. If it is less than 2 mm, the unevenness of the steel sheet is too remarkable, the magnetic flux density is lowered and it is not economical. This is because the conversion effect is reduced. If the width of the concave region is less than 50 μm, it will be difficult to use the demagnetizing effect, while if it exceeds 500 μm, the magnetic flux density will decrease and it will not be economical, so the width of the concave region will be in the range of 50 to 500 μm. Limited to. Furthermore, if the depth of the concave region is less than 0.1 μm, the demagnetizing effect cannot be effectively used.
If the thickness exceeds 50 μm, the magnetic flux density decreases and it becomes not economical. Therefore, the depth of the concave region is limited to the range of 0.1 to 50 μm. In addition, the forming direction of the linear concave region is optimally set to a direction perpendicular to the rolling direction, that is, the sheet width direction, but substantially the same effect can be obtained as long as it is within ± 30 ° with respect to the sheet width direction. .

Further, as a method of forming the linear concave region,
On the surface of the final cold-rolled sheet, an etching resist is applied by printing, after baking, an etching process is performed, and then the method of removing the resist is compared with a method using a conventional knife edge or a laser, This is advantageous in that it can be carried out industrially stably, and that iron loss can be more effectively reduced by tensile tension.

Hereinafter, a typical example of the above-described linear groove forming technique by etching will be specifically described. An etching resist ink containing an alkyd resin as a main component is gravure offset printed on the surface of the final cold-rolled sheet so that the non-applied portion remains linearly at a right angle to the rolling direction with a width of 200 μm and a spacing of 4 mm in a line. After applying, bake at 200 ° C for about 20 seconds. At this time, the resist thickness is about 2 μm.
The steel plate coated with the etching resist in this way,
By performing electrolytic etching or chemical etching, a linear groove having a width of 200 μm and a depth of 20 μm is formed.
Next, the resist is removed by immersion in an organic solvent. The electrolytic etching conditions at this time are as follows:
10 A / dm ² , treatment time: about 20 seconds, and chemical etching conditions: immersion time in HNO ₃ solution: about 10 seconds.

Next, the steel sheet is subjected to decarburization annealing. This annealing makes the cold rolled structure the primary recrystallized structure,
{110} <00 in final annealing (also called finish annealing)
1) For the purpose of removing harmful carbon when secondary recrystallized grains having an orientation are developed, the process is performed in, for example, 750 to 880 ° C. in wet hydrogen.

The final annealing is performed to sufficiently develop secondary recrystallized grains having a {110} <001> orientation.
Usually, it is carried out by immediately raising the temperature to 1000 ° C. or higher by box annealing and maintaining the temperature. This final annealing is usually performed by applying an annealing separating agent such as magnesia, and a base coat called forsterite is simultaneously formed on the surface. However, in the present invention, even if a forsterite undercoat is formed, an annealing separator that does not form such a forsterite undercoat is more advantageous because the undercoat is removed in the next step. That is, the content ratio of MgO for forming the forsterite undercoat is reduced (50% or less), and the content ratio of Al ₂ O ₃ , CaSiO ₃ , PbCl ₃ or the like which does not form such a coating is increased (50% or more). Preferred is an annealed separator.

In the present invention, in order to develop a secondary recrystallized structure highly integrated in the {110} <001> orientation, it is more advantageous to carry out the constant annealing at a low temperature of 820 ° C. to 900 ° C. For example, slow annealing at a heating rate of about 0.5 to 15 ° C./h may be used.

After this purification annealing, the forsterite undercoat or oxide film on the surface of the steel sheet is removed by a known chemical method such as pickling, a mechanical method such as cutting and polishing, or a combination thereof, and the surface of the steel sheet is removed. Is smoothed. That is, after removing various coatings on the steel sheet surface, chemical polishing,
The surface of the steel sheet is smoothed to a center line average roughness Ra of about 0.4 μm or less by a conventional method such as chemical polishing such as electrolytic polishing or mechanical polishing such as buff polishing or a combination thereof.

In the present invention, it is not always necessary to smooth the surface of the silicon steel sheet. Therefore, in this case, there is an advantage that a sufficient iron loss reducing effect can be exerted only by the pickling treatment without performing the smoothing treatment accompanied by the cost increase. Nevertheless, it is still advantageous to perform the smoothing process. At this stage, a concave groove can be introduced into the surface of the steel sheet. The grooves may be introduced by the same method as that used for the surface of the final cold-rolled sheet or the steel sheet before and after the secondary recrystallization.

After the above treatment, prior to forming a tension insulating coating mainly composed of phosphate and colloidal silica on the steel sheet surface, Fe, Si, An ultra-thin film in which one or two or more kinds of nitrides / oxides selected from Al and B are finely dispersed is formed. In order to form this ultra-thin undercoat, first, a coating solution for a tension insulating film mainly composed of phosphate and colloidal silica is diluted with water, and the diluted solution is added to the diluted solution.
A treatment liquid to which a trace amount of an inorganic compound containing one or more selected from Fe, Si, Al and B is added is used. In addition, when applying to the surface of the steel sheet, such a treatment liquid may be applied directly to the surface of the silicon steel sheet.
After applying an aqueous solution to which an inorganic compound such as Fe, Si, Al, and B is added to the surface of the steel sheet, the treatment liquid may be applied.

Here, as a coating solution for a tension insulating film containing phosphate and colloidal silica as main components, for example, as disclosed in JP-B-53-28375, colloidal silica: 4 to 16 wt%, phosphorus Aluminum oxide: 3-24wt
%, Chromic anhydride and / or chromate: 0.2-4.
Coating liquid containing 5 wt%, colloidal silica: 7 to 24 wt% as disclosed in JP-B-56-52117,
Magnesium phosphate: 5 to 30 wt% (however, the molar ratio of magnesium phosphate to colloidal silica: 20/80 to 30 /
70), and, if necessary, a coating liquid to which chromic anhydride, chromate and / or dichromate: 0.01 to 5% by weight is advantageously applied.

Further, the degree of dilution of the coating solution is about 0.1 to 60%, preferably 1 to 20% (for example,
It is preferable to dilute the solution to the extent that 10 to 1000 cc of the coating solution is dissolved in a 1500 cc aqueous solution). That is, in the present invention, in order to form an undercoat film firmly adhered to the base iron, Fe,
It is necessary to convert inorganic compounds such as Si, Al, and B into nitrides and oxides. However, if the concentration of the underlayer treatment solution is too high, the treatment atmosphere (preferably N ₂ (50%) + H ₂ (50%) mixed gas atmosphere), it is difficult to convert inorganic compounds into nitrides / oxides well, and it is effective to dilute with an appropriate amount of water to effectively promote such nitridation / oxidation. is there.

Further, a selection is made from among Fe, Si, Al and B.
In a diluted solution of an inorganic compound containing one or more
Addition amount of inorganic compound is about 5 to 500 g
(About 0.001 to 0.5 mol / l). When
This is because if the amount of these inorganic compounds is too small,
If the effect cannot be achieved,
Is not only economical, but does the coating properties deteriorate instead?
It is. Here, among the various inorganic compounds described above, Fe
FeCl as an inorganic compound containing_Three, Fe (NO_Three)_ThreeEtc. include Si
SiCl as an inorganic compound_Four, Na_TwoSiO_ThreeEtc. containing Al
AlCl as the organic compound_Three, Al (NO_Three)_Three, AlPO_FourEtc. include B
H as an inorganic compound_ThreeBO _Three, Na_TwoB_FourO₇Etc. are particularly advantageous
Complies with

The above-mentioned treatment liquid obtained by adding a small amount of an inorganic compound such as Fe, Si, Al and B to a diluting liquid of a coating liquid for a tension insulating film as described above is applied to a steel sheet surface and dried. Traces of Fe, Si, Al and B on the surface
After attaching inorganic compounds such as Fe, Si, Al, B and other nitrides and oxides to the surface of the steel plate, a short heat treatment is applied in a non-oxidizing atmosphere. To form an ultra-thin undercoating dispersed in In the present invention, the above-mentioned short-time heat treatment is not always necessary. This is because even without such a short-time heat treatment, the heat treatment at the time of forming the insulating film makes it possible to finely form nitrides and oxides such as Fe, Si, Al and B on the steel sheet surface as described above. This is because the dispersed ultrathin undercoat is formed preferentially.

Here, as a coating method, in addition to coating with a normal roll coater or the like, a dipping method in which the steel sheet itself is immersed in a processing liquid, a method in which the processing liquid is directly sprayed or sprayed on the steel sheet surface, and an electrolytic processing method Any known method such as the method can be used. The treatment temperature may be normal temperature, but it is preferable to perform the treatment in a warm solution of about 50 to 100 ° C. for more effective adhesion. When immersion treatment is used, the immersion time is desirably about 1 to 100 seconds.

Then, after washing with water and drying, fine F
In order to form a nitrided / oxide such as e, Si, Al and B on the surface of the steel sheet, more preferably, a short-time heat treatment is performed in a non-oxidizing atmosphere. The treatment atmosphere is preferably an N-containing non-oxidizing atmosphere in order to promote nitriding, and for example, a (N ₂ + H ₂ ) mixed gas atmosphere and an ammonia-containing (NH ₃ + H ₂ ) mixed atmosphere are particularly suitable. . The processing temperature is about 200 to 1200 ° C (preferably 500 to 10
The processing time is about 1 to 100 minutes (preferably about 3 to 30 minutes).

Thus, the finely dispersed Fe,
Due to the presence of nitrides / oxides such as Si, Al and B, it is possible to form an ultra-thin undercoat firmly adhered to the surface of the steel sheet. The coating amount of the undercoating solution is 0.001 to 0.5 g / m ²
It is preferable to apply this amount, and then apply a heat treatment to finally obtain 0.001 to 3.0 μm
It is possible to obtain an ultrathin undercoat having a suitable thickness.

Then, on the surface of the above-mentioned ultrathin undercoat,
After applying the above-mentioned coating solution for the tensile insulating film mainly composed of colloidal silica and phosphate, 500 to 10
Baking at a temperature of 00 ° C, a tensile insulating coating (0.5 to 5 μm
Thickness). Here, since the above-mentioned ultra-thin base film and the tensile insulating film formed thereon are of the same quality, their adhesion is extremely high, and as a result, as a result, the adhesion is remarkably superior to the conventional one. A tensile insulating coating can be formed on the surface of the steel sheet, and thus a unidirectional silicon steel sheet having extremely low iron loss can be obtained with good productivity and at low cost.

In some cases, as the insulating film,
It is also possible to use an insulating coating containing phosphate and chromic acid as main components without adding colloidal silica in the coating. Further, in order to exert a better tilting function on the silicon steel sheet, it is advantageous to apply a normal insulating coating on the silicon steel sheet side and apply a tensile insulating coating on the silicon steel sheet side. .

[0072]

EXAMPLES Example 1 C: 0.076 wt%, Si: 3.38 wt%, Mn: 0.069 wt%, Se:
0.020 wt%, Sb: 0.025 wt%, Al: 0.021 wt%, N: 0.
A continuously cast slab of silicon steel containing 0076 wt% and Mo: 0.012 wt%, with the balance being substantially Fe, was subjected to a heat treatment at 1360 ° C. for 5 hours, followed by hot rolling to a thickness of 2.2 mm. A hot rolled sheet was used. Then, after subjecting to homogenization annealing at 1000 ° C, 1050 ° C
Was subjected to two times of cold rolling with intermediate annealing being carried out to obtain a final cold-rolled sheet having a thickness of 0.23 mm. Then, after decarburization and primary recrystallization annealing in wet H ₂ at 840 ° C., MgO (20%), Al ₂ O ₃ (70
%), CaSiO ₃ (10%), and then applied with a slurry, followed by annealing at 850 ° C for 15 hours.
After the temperature was raised to 1180 ° C. at a rate of / h to develop secondary recrystallized grains strongly integrated in the Goss orientation, a purification treatment was performed in dry H ₂ at 1200 ° C.

After removing the oxide film on the surface of the silicon steel sheet thus obtained, a smoothing treatment by chemical polishing was performed.
A pickling treatment with% HCl was performed. Then, the silicon steel sheet is diluted with a coating solution for tension insulating coating mainly composed of magnesium phosphate and colloidal silica: 250 cc with 1500 cc of distilled water, and further, SiCl ₄ : 20 cc, FeC
l ₃ : 20 g, Al (NO ₃ ) ₃ : immersed in a treatment liquid (80 ° C.) added with 10 g for 20 seconds, then at 950 ° C. for 7 minutes, N ₂ (50%) + H ₂ (5
(0%) It was treated in a mixed gas to form an ultra-thin undercoat having a thickness of 0.2 μm. After that, a tension insulating coating consisting mainly of colloidal silica and magnesium phosphate (approximately 2
μm thick) and baked at 800 ° C.

The magnetic properties, adhesion and magnetostriction properties of the product thus obtained were as follows. Smoothing processing applied was the case where the magnetic properties _{B 8: 1.94 T W 17/50:} 0.64 W / kg adhesion diameter: even if the 180 ° bending on a 25mm round bar no peeling was better. Magnetostriction characteristics Magnetostriction at compressive stress σ = 0.4 kg / mm ² λ _PP = 0.8 × 10 ^-6磁 気 = Magnetostriction at 0.6 kg / mm ² λ _PP = 0.9 × 10 ^-6 Indicated. Magnetic properties when subjected to pickling treatment _{B 8: 1.93 T W 17/50:} 0.68 W / kg adhesion diameter: even if the 180 ° bending on a 25mm round bar no peeling was better. Magnetostriction characteristics Magnetostriction at compressive stress σ = 0.4 kg / mm ² λ _PP = 0.7 × 10 ^-6磁 気 = Magnetostriction at 0.6 kg / mm ² λ _PP = 0.9 × 10 ^-6 Indicated.

Thereafter, the magnetic properties of the above product plate after the strain relief annealing at 800 ° C. for 3 hours were examined. As shown below, no deterioration of the properties was observed in any case. .

For comparison, after decarburization and primary recrystallization annealing were performed in wet H ₂ at 840 ° C., an annealing separator containing MgO as a main component was slurry-coated on the surface of the steel sheet. 15 ° C
After annealing time, after developed a secondary recrystallized grains accumulated strongly Goss orientation was heated to 1180 ° C. at a rate of 10 ° C. / h from 850 ° C., a purification treatment in dry of H ₂ 1200 ° C. After that, a tensile insulating coating (about 2 μm thick) mainly composed of colloidal silica and magnesium phosphate is formed on the forsterite base coating, and baked at 800 ° C to obtain a directional silicon steel sheet. The results obtained by examining the magnetic properties, adhesion and compressive stress properties of magnetostriction were as follows. Magnetic properties _{B 8: 1.94 T W 17/50:} 0.76 W / kg adhesion diameter: even if the bending 20 mm 180 ° in a round bar on there was no peeling. Magnetostriction Magnetostriction at compressive stress σ = 0.4 kg / mm ² λ _PP = 1.6 × 10 ^-6磁 気 Magnetostriction at λ = 0.6 kg / mm ² λ _PP = 4.8 × 10 ^-6 .

Example 2 C: 0.069 wt%, Si: 3.42 wt%, Mn: 0.073 wt%, Se:
0.020 wt%, Sb: 0.023 wt%, Al: 0.020 wt%, N: 0.
A continuous cast slab of silicon steel containing 0072 wt% and Mo: 0.013 wt%, with the balance being substantially Fe, was heated at 1360 ° C. for 4 hours and then hot-rolled to a thickness of 2.0 mm. Hot rolled sheet. After 980 ° C uniform annealing, 1050
Cold rolling was performed twice with intermediate annealing at a temperature of ° C to obtain a final cold-rolled sheet having a thickness of 0.23 mm. Then, on the surface of the final cold-rolled sheet, an etching resist ink containing an alkyd resin as a main component is subjected to gravure offset printing so that the non-applied portion has a width of approximately 200 μm in a direction substantially perpendicular to the rolling direction, and a distance between the rolling directions of 4 mm.
And then baked at 200 ° C. for about 20 seconds. At this time, the resist thickness was 2 μm.
The steel plate coated with the etching resist in this way,
By performing electrolytic etching, a linear groove having a width of 200 μm and a depth of 20 μm was formed, and then immersed in an organic solvent to remove the resist. At this time, the electrolytic etching was performed in a NaCl electrolyte at a current density of 10 A / dm ² and a processing time of 20 A / dm ² .
The test was performed under the condition of seconds.

Then, after performing decarburization and primary recrystallization annealing in 850 ° C. wet H ₂ , MgO (20%), Al ₂ O ₃ (70%),
Slurry coating of an annealing separating agent with the composition of CaSiO ₃ (10%), then annealing at 850 ° C for 15 hours, 850 ° C to 12 ° C / h
Temperature increased to 1150 ° C at high speed and strongly accumulated in Goss direction 2
After developing the next recrystallized grains, a purification treatment was performed in dry H ₂ at 1200 ° C. After removing the oxide film on the surface of the silicon steel sheet thus obtained, the surface of the unidirectional silicon steel sheet was smoothed by chemical polishing. Then, put the silicon steel plate in 1500cc of water
After dissolving 20 cc of SiCl _{4 and} immersing it in an aqueous solution at 80 ° C. for 10 seconds, it was treated at 950 ° C. in a mixed gas of N ₂ (50%) + H ₂ (50%) for 3 minutes. Thereafter, 250 cc of a coating solution for a tensile insulating film containing magnesium phosphate and colloidal silica as main components is further diluted with 1500 cc of distilled water, and the diluted solution further contains 20 cc of SiCl ₄ , 15 g of AlPO _{4 and} 15 g of H _3. BO ₃ : immersed in a treatment solution (80 ° C) containing 10 g for 20 seconds, then 900 ° C
For 10 minutes in N ₂ (93%) + H ₂ (7%) mixed gas, thickness:
An ultra-thin 0.4 μm undercoat was applied. Thereafter, a tension insulating coating (about 2 μm thick) containing colloidal silica and magnesium phosphate as main components was formed on the surface of the steel sheet, and baked at 800 ° C.

The magnetic properties and adhesion of the product thus obtained were as follows. Magnetic properties _{B 8: 1.91 T W 17/50:} 0.57 W / kg adhesion diameter: even if the 180 ° bending on a 20mm round bar no peeling was better.

Thereafter, the magnetic properties of the above product sheet after the strain relief annealing at 800 ° C. for 3 hours were also investigated. No deterioration in magnetic properties due to strain relief annealing was observed.

Further, a steel plate which had not been subjected to chemical polishing and which had been subjected to pickling treatment was used in the same manner as described above, and 250 cc of a coating solution for a tension insulating film mainly composed of magnesium phosphate and colloidal silica was mixed with 1500 cc of distilled water. And then immersed in a treatment solution (80 ° C.) containing 20 cc of SiCl ₄ , 15 g of AlPO ₄ , and 10 g of H ₃ BO ₃ added to the diluted solution for 20 seconds.
Treated in a N ₂ (93%) + H ₂ (7%) mixed gas for 10 minutes. Thereafter, the magnetic properties and adhesion of the product obtained by forming the tension insulating film were as follows. Magnetic properties _{B 8: 1.91 T W 17/50:} 0.65 W / kg adhesion diameter: even if the 180 ° bending on a 25mm round bar no peeling was better.

This product plate was also examined for magnetic properties after performing strain relief annealing at 800 ° C. for 3 hours. No deterioration in magnetic properties due to strain relief annealing was observed.

Example 3 C: 0.042 wt%, Si: 3.46 wt%, Mn: 0.070 wt%, Se:
A continuous cast steel slab containing 0.021 wt%, Sb: 0.025 wt% and Mo: 0.012 wt%, with the balance being substantially Fe, was heated at 1340 ° C for 4 hours and then hot-rolled. And a hot-rolled sheet having a thickness of 2.4 mm. Then, after cold annealing at 900 ° C, cold rolling is performed twice with intermediate annealing at 950 ° C.
The final cold-rolled sheet was 0.23 mm thick. Then, on the surface of the final cold-rolled sheet, an etching resist ink containing an alkyd-based resin as a main component is subjected to gravure offset printing so that the non-applied portion has a width of approximately 200 μm in a direction substantially perpendicular to the rolling direction, and a distance between the rolling directions of 4 mm. After applying so that it remains in a line with
Bake at ℃ for about 20 seconds. The resist thickness at this time is 2 μm
Met. The steel plate coated with the etching resist in this manner is subjected to electrolytic etching to obtain a width: 200
A linear groove having a thickness of 20 .mu.m and a depth of 20 .mu.m was formed, and then immersed in an organic solvent to remove the resist. The electrolytic etching at this time was performed in a NaCl electrolytic solution under the conditions of a current density of 10 A / dm ² and a processing time of 20 seconds.

Then, after decarburization and primary recrystallization annealing in wet H ₂ at 840 ° C., MgO (25%), Al ₂ O ₃ (70%),
Slurry with CaSiO ₃ (5%) annealing separator, then
After the secondary recrystallized grains strongly integrated in the Goss orientation were developed by holding annealing at 0 ° C. for 50 hours, purification treatment was performed in dry H ₂ at 1200 ° C. After removing the oxide film on the surface of the silicon steel sheet thus obtained, the surface of the unidirectional silicon steel sheet was smoothed by chemical polishing. Further, this silicon steel plate is diluted with 1500 cc of distilled water of a coating solution for tension insulating coating consisting mainly of aluminum phosphate and colloidal silica: 250 cc, and a treatment solution obtained by adding 50 cc of SiCl _{4 to the} diluted solution. (80 ° C) for 20 seconds, then 950 ° C for 10 minutes, N ₂
(50%) + H ₂ (50%) The mixture was treated in a mixed gas to form an extremely thin undercoating having a thickness of 0.6 μm. Thereafter, a tension insulating coating (about 2 μm thick) containing colloidal silica and aluminum phosphate as main components was formed on the surface of the steel sheet, and baked at 800 ° C.

The magnetic properties and adhesion of the product thus obtained were as follows. Magnetic properties _{B 8: 1.88 T W 17/50:} 0.63 W / kg adhesion diameter: even if the 180 ° bending on a 25mm round bar no peeling was better.

[0086] An ultra-thin tension film in which Si oxide is finely dispersed is formed on the surface of the steel plate which has not been chemically polished and which has been pickled as described above. The magnetic properties and adhesion of the product obtained by applying the tension insulating film of the system were as follows. Magnetic properties _{B 8: 1.88 T W 17/50:} 0.67 W / kg adhesion diameter: even if the 180 ° bending on a 20mm round bar no peeling was better.

Further, when the magnetic properties of these product sheets after the strain relief annealing at 800 ° C. for 3 hours were examined, no deterioration of the properties was observed in any case as shown below.

Example 4 C: 0.073 wt%, Si: 3.40 wt%, Mn: 0.072 wt%, Se:
0.020 wt%, Sb: 0.023 wt%, Al: 0.019 wt%, N: 0.
A continuous cast slab of silicon steel containing 0074 wt% and Mo: 0.013 wt%, with the balance being substantially Fe, was subjected to a heat treatment at 1340 ° C. for 5 hours, followed by hot rolling to a thickness of 2.0 mm. Hot rolled sheet. Then, after subjecting to homogenization annealing at 1000 ° C, 1050
Cold rolling was performed twice with intermediate annealing at a temperature of ° C to obtain a final cold-rolled sheet having a thickness of 0.23 mm. Then, on the surface of the final cold-rolled sheet, an etching resist ink containing an alkyd resin as a main component is subjected to gravure offset printing so that the non-applied portion has a width of approximately 200 μm in a direction substantially perpendicular to the rolling direction, and a distance between the rolling directions of 4 mm.
And then baked at 200 ° C. for about 20 seconds. At this time, the resist thickness was 2 μm.
The steel plate coated with the etching resist in this way,
By performing electrolytic etching, a linear groove having a width of 200 μm and a depth of 20 μm was formed, and then immersed in an organic solvent to remove the resist. At this time, the electrolytic etching was performed in a NaCl electrolyte at a current density of 10 A / dm ² and a processing time of 20 A / dm ² .
The test was performed under the condition of seconds.

Then, after performing decarburization and primary recrystallization annealing in 840 ° C. wet H ₂ , MgO (20%), Al ₂ O ₃ (70%),
Slurry coating of an annealing separating agent with the composition of CaSiO ₃ (10%), then annealing at 850 ° C for 15 hours, 850 ° C to 12 ° C / h
Temperature rises to 1100 ° C at a high speed and strongly accumulates in Goss direction 2
After developing the next recrystallized grains, a purification treatment was performed in dry H ₂ at 1200 ° C. After removing the oxide film on the surface of the silicon steel sheet thus obtained, the surface of the unidirectional silicon steel sheet was smoothed by chemical polishing. Then, put the silicon steel plate in 1500cc of water
25 cc of SiCl ₄ and 5 g of AlNO ₃ were dissolved and immersed in an aqueous solution at 90 ° C. for 40 seconds. Thereafter, further tension insulating film coating liquid mainly composed of magnesium and colloidal silica phosphate: 250 cc was diluted with distilled water 1500cc, SiCl ₄ further into this diluted _{solution: 20cc, AlPO 4: 15g,} H 3 BO ₃ :
It was immersed in a treatment liquid (80 ° C.) to which 10 g was added for 20 seconds. After that, a tensile insulation film (about 1.5 μm thick) composed mainly of colloidal silica and magnesium phosphate was formed on the surface of the steel sheet, and baked at 800 ° C.

The magnetic properties and adhesion of the product thus obtained were as follows. Magnetic properties _{B 8: 1.91 T W 17/50:} 0.59 W / kg adhesion diameter: even if the 180 ° bending on a 20mm round bar no peeling was better.

[0091]

Thus, according to the present invention, an ultra-low iron loss unidirectional silicon steel sheet having extremely low iron loss and excellent magnetostriction characteristics as compared with conventional materials can be produced at very low cost and high productivity. You can get under sex.

[Brief description of the drawings]

FIG. 1 (a) shows a conventional unidirectional silicon steel sheet in which the surface of a finish-annealed unidirectional silicon steel sheet is simply coated with a tension insulating coating mainly composed of phosphate and colloidal silica, )
Is to add TiN or CrN on the surface of
After forming an ultra-thin ceramic coating such as, a conventional unidirectional silicon steel sheet further coated with a tensile insulating coating on its surface,
(c) is an embodiment according to the present invention in which an ultra-thin undercoating in which minute amounts of nitrides and oxides such as Fe, Si, Al and B are finely dispersed is formed at the interface between the unidirectional silicon steel sheet and the tensile insulating coating. It is a grain-oriented silicon steel sheet.

FIG. 2 is a view showing an oxide composition in a nitride / oxide of Si dispersed in an ultrathin undercoat.

Claims (7)

[Claims] 1. A surface having a tension insulating film mainly composed of phosphate and colloidal silica, and having a thickness of 0.05 to 0.5.
1 mm selected from the group consisting of Fe, Si, Al and B at the interface between the surface of the steel sheet and the tensile insulating film, in the same film component as the tensile insulating film. An ultra-low iron loss unidirectional silicon steel sheet having an ultra-thin undercoat in which one or more kinds of nitrides / oxides are finely dispersed. 2. The steel sheet according to claim 1, wherein
At a distance of 2 to 10 mm in the direction crossing the rolling direction, width: 50 to
An ultra-low iron loss unidirectional silicon steel sheet having a linear concave area of 500 μm and a depth of 0.1 to 50 μm. 3. The ultra-low iron loss unidirectional silicon steel sheet according to claim 1, wherein the surface of the finish-annealed unidirectional silicon steel sheet is a surface subjected to a smoothing treatment. 4. The ultra-low iron loss unidirectional silicon steel sheet according to claim 1 or 2, wherein the surface of the finish-annealed unidirectional silicon steel sheet is a surface that has not been subjected to a smoothing treatment and is still pickled. 5. A coating solution for a tension insulating coating mainly composed of phosphate and colloidal silica is diluted with water on the surface of a finish-annealed unidirectional silicon steel sheet having a thickness of 0.05 to 0.5 mm, and By applying and drying a treatment solution in which a small amount of an inorganic compound containing one or more selected from Fe, Si, Al and B is added to the diluent, a small amount of Fe, Si , After applying an inorganic compound containing at least one selected from the group consisting of Al, B and B, forming a tension insulating coating mainly composed of phosphate and colloidal silica according to a conventional method. For producing ultra low iron loss unidirectional silicon steel sheet. 6. A coating solution for a tensile insulating film containing phosphate and colloidal silica as main components is diluted with water on the surface of a finish-annealed unidirectional silicon steel plate having a thickness of 0.05 to 0.5 mm, and By applying and drying a treatment solution in which a small amount of an inorganic compound containing one or more selected from Fe, Si, Al and B is added to the diluent, a small amount of Fe, Si , Al and B, and then heat-treated in a non-oxidizing atmosphere for a short time after the inorganic compound containing one or two or more selected from the group consisting of An ultra-thin undercoating is formed by finely dispersing one or more nitrides / oxides selected from Fe, Si, Al and B. Then, phosphate and colloidal silica are mainly used according to a conventional method. Ultra-low iron loss characterized by forming a tensile insulating coating as a component Method for producing a grain-oriented silicon steel sheet. 7. The method according to claim 5, wherein the surface of the steel plate of the steel sheet is disposed at an interval of 2 to 10 mm in a direction crossing the rolling direction.
A method for producing an ultra-low iron loss unidirectional silicon steel sheet, comprising a linear concave region having a width of 50 to 500 μm and a depth of 0.1 to 50 μm.