JPH11286775A - Production of ultralow core loss grain-oriented silicon steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ultralow core loss grain-oriented silicon steel sheet markedly excellent in core loss compared to that of a conventional material at an extremely low cost. SOLUTION: At the time of forming a ceramic tensile film composed of the nitride or carbide of Cr or Al on the surface of a grain oriented silicon steel sheet with 0.05 to 0.5 mm sheet thickness subjected to finish annealing by plasma coating, as a target at the time of the plasma coating, a ferrochromium or matrix aluminum material is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an ultra-low iron loss unidirectional silicon steel sheet, and more particularly to a surface of a silicon steel sheet which has been subjected to finish annealing or a surface of a silicon steel sheet which has been subjected to finish annealing having a linear concave region. In addition, when a ceramic tension coating is applied to improve iron loss characteristics, the target used for plasma coating is devised to improve the iron loss characteristics advantageously to reduce manufacturing costs. It is also to be achieved.

[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] 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 magnetic 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 a magnetic domain effect is applied by utilizing the demagnetizing field effect of the groove. 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.

In addition, Japanese Patent Publication No. 52-24499 discloses that a forsterite base film formed after finish annealing of a silicon steel sheet is removed, the steel sheet surface is polished, and then the steel sheet surface is subjected to metal plating. 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, etc., as a solution to the above disadvantage.
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 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 knowledge on ceramic coating. Further, the following knowledge has been obtained on the surface condition of the ceramic film and the steel sheet. (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 to achieve the desired object, 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 unidirectional silicon steel sheet has an extremely thin ceramic film having excellent adhesion and a tensile coating, 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.

[0017]

However, in order to form such a dense ceramic film, not only treatment in a vacuum but in a high plasma atmosphere is indispensable, but also in plasma coating. Materials used (for example, pure Ti material for TiN film formation, high purity for Si ₃ N ₄ film formation)
(Si, etc.) is very expensive, so that there is a problem that the cost is increased in industrialization.

[0018] In view of the above, the present inventors have proposed to reduce the cost of an Al or Cr target used in plasma coating of nitride or carbide of Al or Cr in order to manufacture silicon steel plates at low cost. Worked on That is, the current AlN and CrN
Of ceramics such as nitrides and carbides such as AlC and CrC
In magnet coating, magnetron sputtering is generally used because it is the most reliable in terms of ceramic film quality, uniformity of film, film forming speed and stability of long-time continuous coating. This magnetron
The targets of Al and Cr used in the sputtering method include high-purity Al and high-purity Cr of about 99.9999 wt% to 99.99 wt% in order to purify the coating film quality and prevent contamination of the vacuum chamber. Is used. However, since these high-purity Al and Cr are highly purified by employing many techniques including melting, the material cost is high, and as a result, the target used is extremely expensive.

Therefore, the present inventors have studied various Al and Cr materials in order to solve the above problems. Among them, extremely inexpensive ferro-chrome and ingot aluminum commonly used for adjusting the composition of steel products at the steelmaking stage were used as target materials, and these materials were simply inexpensive. Not only that, it has been found that the adhesiveness of the formed ceramic coating is enhanced, which effectively contributes to the improvement of iron loss characteristics. The present invention is based on the above findings.

That is, the gist of the present invention is as follows. 1. Ultra-low iron loss unidirectional by applying a ceramic tension coating consisting of Cr or Al nitride or carbide by plasma coating on the surface of a finish-annealed unidirectional silicon steel plate with a thickness of 0.05 to 0.5 mm When manufacturing silicon steel sheet, as a target for plasma coating,
A method for producing an ultra-low iron loss unidirectional silicon steel sheet, comprising using ferro-chromium or ingot aluminum material.

2. In the above item 1, the surface of the finish-annealed unidirectional silicon steel sheet has a thickness of 2 to 2 in a direction crossing the rolling direction.
At intervals of 10 mm, width: 50-500 μm, depth: 0.1-50 μm
A method for producing an ultra-low iron loss unidirectional silicon steel sheet, characterized in that a linear concave region is provided.

3. In 1 or 2, the method for producing an ultra-low iron loss unidirectional silicon steel sheet, wherein the surface of the finish-annealed unidirectional silicon steel sheet is a surface subjected to a smoothing treatment. 4. In the above 1 or 2, a method for producing an ultra-low iron loss unidirectional silicon steel sheet, in which 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. In any one of the above items 1 to 4, the ceramic tension coating is a multilayer film composed of two or more layers composed of nitride and / or carbide, the thermal expansion coefficient of which is smaller toward the outer layer side, and the outermost ceramic tension coating is A method for producing an ultra-low iron loss unidirectional silicon steel sheet having an insulating property.

[0024]

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: 0.071 wt%, Si: 3.36 wt%, Mn: 0.070 wt%, Se:
0.020 wt%, Sb: 0.025 wt%, Al: 0.020 wt%, N: 0.
A silicon steel continuous cast slab containing 0068 wt% and Mo: 0.012 wt%, with the balance being substantially Fe, was subjected to a heat treatment at 1350 ° C. for 4 hours, followed by hot rolling to obtain a sheet thickness of 2.0 mm. Hot rolled sheet. This hot-rolled sheet was subjected to uniform annealing at 1020 ° C. for 3 minutes, and then twice rolled with intermediate annealing at 1050 ° C. 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.

Thereafter, after decarburization and primary recrystallization annealing in wet H ₂ at 840 ° C., MgO (10%), Al ₂ O ₃ (55%),
Slurry coating of an annealing separating agent with the composition of CaSiO ₃ (5%) and SiO ₂ (30%), then annealing at 850 ° C for 15 hours, then rising from 850 ° C to 1150 ° C at a rate of 12 ° C / h After heating to develop secondary recrystallized grains strongly integrated in the Goss orientation, they were purified in 1220 ° C. dry H ₂ .

After removing the surface coating of the product thus obtained and then smoothing the surface of the silicon steel sheet by chemical polishing, the surface of the silicon steel sheet is magnetron-sputtered (PV
0.5Nm thin CrN and AlN
A coating was applied. Cr target and Al used at that time
Targets were prepared by the following four methods. (A) The ferro-chromium material was melted in a 100 kg vacuum melting furnace, hot-rolled and rolled to a thickness of 12 mm, the surface was polished, and then sheared to 10 mm x 127 mm x 476 mm. A bonding process was performed. In this bonding process, after plating one side of the Cr substrate with Cu, the substrate of Cu
(A magnet can be installed on the back side of this water-cooled Cu substrate.) This is to use it as a Cr target by attaching it on top. In addition,
The main component of this ferro-chromium target is Cr: 92.5
wt%, Si: 2.0 wt%, Fe: 1.5 wt%, Al: 1.4 wt%, T
i: 1.3 wt%, C: 0.7 wt%, S: 0.04 wt%, P: 0.02w
At t%, it contained some other trace elements. The ferro-chromium target was charged into a magnetron sputtering apparatus, and a voltage of 400 V and a current of about 0.5 μm were formed on a silicon steel plate by a magnetron sputtering method using an operating power of 50 A.
An m-thick CrN film was coated.

(B) High-purity Cr material (Cr: 99.99 wt%)
After melting in a 100kg vacuum melting furnace, 10mm x 127mm x 47
It was sheared to 6 mm and then subjected to a bonding treatment. The chemical analysis value of the main component of this high-purity chromium target is Cr: 99.99 wt%. This high purity chrome tar
The get is charged into the magnetron sputtering device, and the voltage:
400V, current: 50A operating power using magnetron
A CrN film having a thickness of about 0.5 μm was coated on a silicon steel plate by sputtering.

(C) The aluminum material of the base metal is melted in a 100 kg vacuum melting furnace, hot-rolled and rolled to a thickness of 12 mm, the surface thereof is polished and then reduced to 10 mm × 127 mm × 476 mm. After shearing, a bonding process was performed. The main components of the Al target of this metal were Al: 98.5 wt%, Fe: 0.40
wt%, Si: 0.18, Ti: 0.08 wt%, Cu: 0.04 wt%, and other trace elements. This metal aluminum target was charged into a magnetron sputtering apparatus, and a voltage of 400 V and a current of about 0.5 μm were formed on a silicon steel plate by a magnetron sputtering method using an operating power of 50 A.
A thick AlN film was coated.

(D) Using high-purity Al (Al: 99.9999 wt%) as a starting material, redissolve, shear to 10 mm × 127 mm × 476 mm, and then perform a bonding process to obtain a high-purity aluminum target. used. This high-purity aluminum target was charged into a magnetron sputtering apparatus, and about 0.5 V was applied on a silicon steel plate by magnetron sputtering using an operating power of a voltage of 400 V and a current of 50 A.
An AlN film having a thickness of μm was coated. Table 1 shows the results obtained by examining the magnetic properties and adhesion of each product thus obtained.

[0031]

[Table 1]

As is apparent from Table 1, the ferro-chromium target (A) according to the present invention and the
When the film was formed using the aluminum base target of (C), the magnetic properties, especially the iron loss W _17/50, were 0.49 and 0.51 W /
It is noteworthy that not only did it exhibit an extremely low value of kg, but the adhesion at that time was also remarkably excellent at 10 mmφ. On the other hand, when the high-purity chromium target (B) and the high-purity aluminum target (D) are used, the magnetic properties, particularly the iron loss W _17/50, are only about 0.63 or 0.68 W / kg. Also, the adhesion was inferior to about 30 mmφ or 40 mmφ.

As described above, as a target for plasma coating, a ferromagnetic material (A) having a low material cost can be used.
When a film is formed using a chromium target and a base metal aluminum target (C), the magnetic properties, particularly iron loss properties, of the silicon steel sheet are significantly improved because of the ceramic film and the silicon steel sheet. Traces of F in the ceramic film at the interface of
It is considered that the presence of nitrides such as e, Al, and Ti effectively improves the adhesion. In this regard, when a high-purity chromium target (B) or a high-purity aluminum target (D) is used, the adhesion is low because these elements are not present in the ceramic film. Since no improvement can be achieved, and as a result a strong tensile tension cannot be applied to the silicon steel sheet, it is considered that the degree of reduction in iron loss is reduced.

[0034]

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 grain-oriented 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% Both S and Se are 0.1 wt% or less, and among them, 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, even if Al, Sb, Cu, Sn, B and the like which are conventionally known as inhibitors are added in combination, the effect of the present invention is not hindered.

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 smelt the raw material, not only an LD converter, an electric furnace, an open hearth furnace, and other known steelmaking furnaces can be used, but also vacuum melting and RH degassing can be used together.

According to the present invention, S, Se contained in the raw 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 continuous 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 homogenization 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 a 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 decarburizing 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, to reduce the content ratio of MgO to form a forsterite base coating (hereinafter 50%), CaO not to form a Kakaru replace _{film, Al 2 O 3, CaSiO 3} , high content of SiO ₂ or the like (50% The annealed separator described above is advantageous.

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, or a mechanical method such as cutting or polishing, or a combination thereof. 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-mentioned treatment, a ceramic film made of nitride (AlN, CrN) and carbide (AlC, CrC) of Al or Cr is formed on the surface of the steel sheet by using a plasma coating method. In the present invention, it is important to use commercially available inexpensive ferro-chromium and bare metal aluminum as the Al target and the Cr target when forming such a ceramic film. Because, such ferro-
Since chromium and aluminum aluminum contain a small amount of Fe, Ti, Si, etc., they are suitable from the viewpoint of ensuring adhesion to silicon steel sheets, and thus are suitable for Al targets and Cr targets.
For the get, the significant cost reduction is realized together with the improvement of the iron loss characteristics.

As the plasma coating method, a magnetron sputtering method is particularly suitable, but in addition, an HCD method (one type of ion plating method), a plasma CVD method, an (EB + RF) method, a multi-arc method Etc. can also be used. In addition, Al target and
In order to produce a Cr target, ferro-chromium or ingot aluminum is melted, sheared to a predetermined size, and then subjected to a bonding treatment.

[0052]

EXAMPLES Example 1 C: 0.074 wt%, Si: 3.38 wt%, Mn: 0.076 wt%, Se:
0.020 wt%, Sb: 0.025 wt%, Al: 0.020 wt%, N: 0.
A continuously cast slab of silicon steel containing 068 wt% and Mo: 0.012 wt%, with the balance being substantially Fe, was heated at 1350 ° C. for 4 hours and then hot-rolled to a thickness of 2.2 mm. Hot rolled sheet. Then, after subjecting to a uniform annealing at 1010 ° 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 performing decarburization and primary recrystallization annealing in wet H ₂ at 840 ° C., MgO (10%), Al ₂ O ₃ (70
%), CaSiO ₃ (10%), SiO ₂ (10%), and then annealed at a temperature of 850 ° C for 15 hours.
The temperature was raised from 50 ° C to 1180 ° C at a rate of 12 ° C / h to develop secondary recrystallized grains strongly integrated in the Goss orientation.
It was subjected to purification treatment in H _2.

The oxide film on the surface of the silicon steel sheet thus obtained was removed, and a part thereof was further subjected to a smoothing treatment by chemical polishing. Next, a 0.6 μm CrN ceramic film was formed on the surface of the silicon steel plate by magnetron sputtering.
m thick coating. At this time, a Cr target used for plasma coating was prepared as follows. The ferro-chromium material is melted in a 100 kg vacuum melting furnace, hot-rolled and rolled to a thickness of 12 mm, and the surface is polished.
It was sheared to 10 mm x 127 mm x 476 mm. Next, a bonding process was performed. This bonding process is performed for use as a Cr target by plating one surface of a Cr substrate with Cu and then attaching the substrate to a Cu substrate using In. The main components of the ferro-chromium target are: Cr: 92.0 wt%, Si: 2.5 wt%, Fe: 1.8 wt%, A
l: 1.6 wt%, Ti: 1.5 wt%, C: 0.8 wt%, S: 0.06 w
t%, P: 0.03 wt%. The ferro-chromium target was charged into a magnetron sputtering apparatus, and a CrN film having a thickness of about 0.6 .mu.m was formed on a silicon steel plate by a magnetron sputtering method using an operating power of a voltage of 400 V and a current of 50 A.
The membrane was coated.

The magnetic properties and adhesion of the product thus obtained were as follows. Magnetic properties B ₈ : 1.95 _{TW 17/50} : 0.57 W / kg Adhesiveness Even after a 180 ° bending on a 10 mm diameter round bar, there was no peeling and good results. When subjected to pickling treatment Magnetic properties _{B 8: 1.94 T W 17/50:} 0.62 W / kg adhesion diameter on 10mm round bar 180 ° bend without peeling even if the were good.

Separately, a ferro-chromium target was charged into a magnetron sputtering apparatus, and a voltage: 400
V, current: A CrC film having a thickness of about 0.7 μm was coated on a silicon steel sheet by a magnetron sputtering method using an operating power of 50 A. The magnetic properties and adhesion of the product at this time were as follows. Smoothing processing applied was the case where the magnetic properties _{B 8: 1.95 T W 17/50:} 0.59 W / kg adhesion diameter on 10mm round bar 180 ° bend without peeling even if the were good.

Example 2 C: 0.070 wt%, Si: 3.42 wt%, Mn: 0.073 wt%, Se:
0.020 wt%, Sb: 0.025 wt%, Al: 0.020 wt%, N: 0.
A continuously cast slab of silicon steel containing 066 wt% and Mo: 0.012 wt%, with the balance being substantially Fe, was heated at 1350 ° C. for 5 hours and then hot-rolled to a thickness of 2.0 mm. Hot rolled sheet. Then, after performing uniform annealing at 1000 ° C, 1030 ° 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, 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. By subjecting the steel sheet coated with the etching resist in this way to electrolytic etching, the width: 200 μm and the depth:
A 20 μm linear groove was formed and then immersed in an organic solvent to remove the resist. The electrolytic etching at this time is
In a Cl electrolyte, the current density was 10 A / dm ² , and the treatment time was 20 seconds.

Then, after decarburization and primary recrystallization annealing were performed in wet H ₂ at 840 ° C., MgO (25%), Al ₂ O ₃ (55%),
Slurry coating of an annealing separating agent with the composition of CaSiO ₃ (5%) and SiO ₂ (15%), then annealing at 850 ° C for 15 hours, then rising from 850 ° C to 1150 ° C at a rate of 10 ° C / h After heating to develop secondary recrystallized grains strongly integrated in the Goss orientation, a purification treatment was performed in dry H ₂ at 1220 ° C. After removing the oxide film on the surface of the silicon steel sheet thus obtained, the surface was smoothed by chemical polishing.

Then, a 0.7 μm thick AlN ceramic film was formed on the surface of the silicon steel plate by magnetron sputtering. At this time, Al used for plasma coating is used.
The target was prepared as follows. The aluminum ingot is melted in a 100 kg vacuum melting furnace and then hot-rolled.
After rolling to a thickness of 10 mm, the surface is polished and then 10 mm x 127 m
It was sheared to m × 476 mm. Next, a bonding process was performed. The main components of the metal aluminum target are Al: 98.0 wt%, Fe: 0.60 wt%, Si: 0.38 wt%, Ti: 0.
14 wt%, Cu: 0.19 wt%. This metal aluminum target was charged into a magnetron sputtering apparatus, and an AlN film having a thickness of about 0.7 μm was formed on a silicon steel sheet by magnetron sputtering using an operating power of 400 V and a current of 50 A. Coated.

The magnetic properties and adhesion of the product thus obtained were as follows. Magnetic properties _{B 8: 1.91 T W 17/50:} 0.51 W / kg adhesion diameter on 10mm round bar 180 ° bend without peeling even if the were good.

In addition, separately from this,
The target was placed in a magnetron sputtering apparatus, and a magnetron sputter method was used to apply a voltage of 400 V and a current of 50 A to a silicon steel plate to obtain a 0.7 μm thick A.
The 1C film was coated. The magnetic properties and adhesion of the obtained product were as follows. Magnetic properties _{B 8: 1.91 T W 17/50:} 0.54 W / kg adhesion diameter on 10mm round bar 180 ° bend without peeling even if the were good.

Further, the magnetic properties and adhesion of the product obtained by applying the AlN ceramic on the surface of the as-picked steel sheet without chemical polishing in the same manner as described above were as follows. Magnetic properties _{B 8: 1.91 T W 17/50:} 0.59 W / kg adhesion diameter on 10mm round bar 180 ° bend without peeling even if the were good.

Example 3 C: 0.044 wt%, Si: 3.36 wt%, Mn: 0.071 wt%, Se:
A continuously cast silicon steel slab containing 0.020 wt%, Sb: 0.025 wt% and Mo: 0.012 wt%, with the balance being substantially Fe, was heated at 1330 ° C for 5 hours and then hot-rolled. And a hot-rolled sheet having a thickness of 2.4 mm. Next, after uniform annealing at 950 ° C, cold rolling is performed twice with intermediate annealing at 1000 ° 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 820 ° C., MgO (10%), Al ₂ O ₃ (60%),
After applying an annealing separator of CaSiO ₃ (15%) and SiO ₂ (15%), the secondary recrystallized grains strongly integrated in the Goss orientation were developed by holding annealing at 850 ° C. for 50 hours. 1200 ℃ dry
It was subjected to purification treatment in H _2. After removing the oxide film on the surface of the silicon steel sheet thus obtained, the surface was smoothed by chemical polishing.

Then, a 0.5 μm thick AlN ceramic film was formed on the second surface of the silicon steel plate by magnetron sputtering. At this time, Al used for plasma coating is used.
The target was prepared as follows. The aluminum ingot is melted in a 100 kg vacuum melting furnace and then hot-rolled.
After rolling to a thickness of 10 mm, the surface is polished and then 10 mm x 127 m
It was sheared to m × 476 mm. Next, a bonding process was performed. The main components of the metal aluminum target are Al: 98.2 wt%, Fe: 0.55 wt%, Si: 0.35 wt%, Ti: 0.
12 wt%, Cu: 0.11 wt%. The bare aluminum target was charged into a magnetron sputtering apparatus, and an AlN film having a thickness of about 0.5 μm was formed on a silicon steel sheet by a magnetron sputtering method using an operating power of a voltage of 400 V and a current of 50 A. Coated.

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 10mm round bar no peeling was better.

Example 4 C: 0.072 wt%, Si: 3.41 wt%, Mn: 0.076 wt%, Se:
0.020 wt%, Sb: 0.025 wt%, Al: 0.021 wt%, N: 0.
A continuously cast slab of silicon steel containing 066 wt% and Mo: 0.012 wt%, with the balance being substantially Fe, was heated at 1340 ° C. for 5 hours and then hot-rolled to a thickness of 2.0 mm. Hot rolled sheet. 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, 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. By subjecting the steel sheet coated with the etching resist in this way to electrolytic etching, the width: 200 μm and the depth:
A 20 μm linear groove was formed and then immersed in an organic solvent to remove the resist. The electrolytic etching at this time is
In a Cl electrolyte, the current density was 10 A / dm ² , and the treatment time was 20 seconds.

Then, after decarburization and primary recrystallization annealing were performed in wet H ₂ at 840 ° C., MgO (25%), Al ₂ O ₃ (60%),
Slurry coating of an annealing separating agent with the composition of CaSiO ₃ (5%) and SiO ₂ (10%), then annealing at 850 ° C for 15 hours, then rising from 850 ° C to 1150 ° C at a rate of 10 ° C / h After heating to develop secondary recrystallized grains strongly integrated in the Goss orientation, purification 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 was smoothed by chemical polishing.

Next, a CrN ceramic film was formed on the surface of the silicon steel sheet by using a magnetron sputtering method to a thickness of 0.7 μm.
Then, CrC was formed on CrN to a thickness of 0.2 μm. At this time, a Cr tar used for plasma coating is used.
Gets were produced as follows. Ferrochrome material (Cr: 75.0 wt%, Fe: 23.0 wt%, Al: 0.3 wt%, Ti: 0.
(8 wt%, the remaining impurities) was melted in a 100 kg vacuum melting furnace and then sheared to 10 mm x 127 mm x 476 mm. Next, a bonding process was performed. This ferrochrome target was charged into a magnetron sputtering apparatus, and the voltage: 400
V, current: A CrN film having a thickness of 0.7 μm was coated on a silicon steel plate by magnetron sputtering using an operating power of 50 A, and a CrC film having a thickness of 0.2 μm was further coated thereon.

The magnetic properties and adhesion of the product thus obtained were as follows. The CrN film only if the magnetic properties _{B 8: 1.91 T W 17/50:} 0.51 W / kg adhesion diameter on 10mm round bar 180 ° bend without peeling even if the were good. Of (CrN + CrC) composite film when the magnetic properties _{B 8: 1.91 T W 17/50:} 0.48 W / kg adhesion diameter on 10mm round bar 180 ° bend without peeling even if the were good.

[0070]

As described above, according to the present invention, it is possible to obtain an ultra-low iron loss unidirectional silicon steel sheet having extremely excellent iron loss as compared with conventional materials, at extremely low cost.

Claims (5)

[Claims] 1. A ceramic tension coating made of nitride or carbide of Cr or Al is formed on the surface of a finish-annealed unidirectional silicon steel sheet having a thickness of 0.05 to 0.5 mm by plasma coating. In producing an iron-loss unidirectional silicon steel sheet, a ferro-chromium or ingot aluminum material is used as a target in plasma coating. Production method. 2. The method according to claim 1, wherein the surface of the finish-annealed unidirectional silicon steel sheet is formed in a direction intersecting the rolling direction.
At intervals of 10 mm, width: 50-500 μm, depth: 0.1-50 μm
A method for producing an ultra-low iron loss unidirectional silicon steel sheet, characterized in that a linear concave region is provided. 3. The method for producing an 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 has not been subjected to a smoothing treatment and is a surface as it is in an pickling treatment. Production method. 5. The ceramic tension coating according to claim 1, wherein the ceramic tension coating comprises a plurality of two or more layers made of a nitride and / or a carbide, and the thermal expansion coefficient decreases toward the outer layer, and A method for producing an ultra-low iron loss unidirectional silicon steel sheet, wherein the ceramic tension coating of the outer layer has insulating properties.