JPH02285065A - Production of grain-oriented silicon steel sheet with superlow iron loss - Google Patents

Abstract

PURPOSE:To produce a grain-oriented silicon steel sheet having high magnetic flux density and reduced in iron loss by polishing the surface of a finish- annealed grain-oriented silicon steel sheet and then forming a high-tension TiN film and a TiAlN film by means of ion plating. CONSTITUTION:A silicon steel slab is hot-rolled, and the resulting hot rolled plate is subjected to homogenizing annealing and further to cold rolling twice, while process-annealed between the cold rolling stages, so as to be formed into a cold rolled steel sheet of the final sheet thickness. Subsequently, decarburizing and primary recrystallization annealing is applied to the above steel sheet, and a separation agent at annealing is applied to the steel sheet to carry out secondary recrystallization annealing and purification annealing. After the removal of surface oxide film, the steel sheet surface is polished so as to be finished into mirror-like state. Successively, a high-tensile TiN film and a TiAlN film are formed by means of ion plating. By this method, the grain- oriented silicon steel sheet excellent in thermal stability, remarkably reduced in iron loss, and having superior electromagnetic characteristics can be produced.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to improving the electrical and magnetic properties of unidirectional silicon steel, particularly to reducing iron loss, and in particular to improving the electrical and magnetic properties of unidirectional silicon steel. The present invention relates to a new method that can advantageously achieve ultra-low iron loss characteristics, regardless of whether or not the process is completed.

(Prior art) As is well known, unidirectional silicon steel sheets are
It is a product in which secondary recrystallized grains are highly integrated in the Goss orientation (110) [:OO1], and is mainly used as the iron core of transformers and other electrical equipment, and its electrical and magnetic properties are represented by the magnetic flux density (B+) of the product. ) is high, and iron loss (W17/
S. low value) is required.

This unidirectional silicon steel is manufactured through a wide variety of complicated processes, but recently, micro-strains have been introduced into the surface of the unidirectional silicon steel plate after final annealing by laser irradiation in a direction approximately perpendicular to the rolling direction. It was proposed to subdivide the magnetic domain by using
No. 252, Special Publication No. 57-53419, Special Publication No. 58-2
6405 and Special Publication No. 58-26406)
.

This magnetic domain refining technology is effective for transformer materials that do not undergo strain relief annealing, but it is effective for core transformer materials that undergo strain relief annealing. There is a drawback that the laser irradiation effect disappears because microstrains are released by annealing and the magnetic domain width becomes wider.

On the other hand, earlier in Japanese Patent Publication No. 52-24499, the surface of a unidirectional silicon steel plate after finish annealing was mirror-finished, or the mirror-finished surface was coated with metal plating or an insulating film was applied thereon. By baking,
A method for manufacturing ultra-low iron loss unidirectional silicon steel sheets has been proposed.

However, this method of improving iron loss through mirror finishing cannot be adopted from a process perspective because it does not contribute enough to reducing iron loss despite the significant increase in cost. Furthermore, it has not been adopted in current manufacturing processes because it has problems with adhesion to steel plates after being subjected to strain relief annealing at a high temperature of 600° C. or higher for a long time. Japanese Patent Publication No. 56-4150 also proposes a method in which a steel plate surface is mirror-finished and then an oxide-based ceramic thin film is vapor-deposited. However, this method cannot be used in actual manufacturing processes because the ceramic layer peels off from the steel sheet annealed at a high temperature of 600° C. or higher.

Therefore, as disclosed in Japanese Patent Publication No. 63-54767, Japanese Patent Publication No. 63-32850, and Japanese Patent Publication No. 63-32849, the inventors developed a forsterite coating on the surface of a finish annealed unidirectional silicon steel sheet. After removal, polishing treatment, ion plating, CVD
(Chemical Vapor Depositio
n) or by ion implantation, Ti,
Zr, Hf.

V, Nb, Ta, Mn, Cr, Mo, %1.
Co, Ni, Aj! , Forming a tension coating consisting of one or more and four or less selected from B and Si nitrides and/or carbides, or further depositing an insulating coated and baked layer on this tension coating. We have previously invented a method for obtaining ultra-low iron loss unidirectional silicon steel sheets with excellent thermal stability in magnetic properties. However, although these inventions can provide ultra-low iron loss characteristics, for example, when forming an insulating coated and baked layer over a TiN coating, it must be performed in a separate process, which increases costs accordingly. is the problem.

(Problems to be Solved by the Invention) The inventors have achieved the following by taking advantage of the effectiveness of improving iron loss through polishing treatment, including the above-mentioned mirror finishing.
Characteristics that outweigh the disadvantage of increased cost required for this treatment, in particular, do not require a separate process for forming an insulating coated and baked layer on the tension coating layer, which does not cause characteristic deterioration even during high-temperature treatment, - It is an object of the present invention to achieve ultra-low iron loss that is advantageous for layers.

(Means for Solving the Problems) The present invention removes oxides on the surface of finish annealed unidirectional silicon steel, and then forms a tension film of TiN on the polished surface by ion plating. This is a patented and excellent method for manufacturing a unidirectional silicon steel sheet with ultra-low core loss, which is characterized by further forming a TiAl1N coating thereon.

The explanation will be as follows according to a specific experimental example that led to the success of this invention.

C: 0.043% by weight (hereinafter simply expressed as %) Si
: 3, 33%, Mn: 0. 072%. Se
: 0.021%. Sb: 0.026%. M
O: 0. A silicon steel slab containing 0.13% and the balance consisting of Fe was heated at 1350° C. for 4 hours and hot rolled to obtain a 20 mm thick hot rolled plate.

After that, after homogenization annealing at 950℃ for 3 minutes,
Cold rolled twice with intermediate annealing for 0.2 min.
A final cold-rolled sheet with a thickness of 3 mm was obtained.

After that, after decarburization and primary recrystallization annealing in wet hydrogen at 800°C, MgO (3%) and ^l203 (
6%), T102 (2%), ZrO, (3%
) was coated with the main component Tosul annealing separator and heated at 850°C for 50°C.
Secondary recrystallization annealing for 1 hour and purification annealing for 5 hours in dry H2 at 1200°C were performed.

Thereafter, oxides on the surface of the steel plate were removed, and the surface of the steel plate was polished to a mirror-like finish with a center line average roughness of 0.1 μm.

After that, ion plating (IOO
O.A. After depositing 0.7 μm of TiN with 55 V),
Subsequently, 1.07-4 m of TilN was deposited (see (A) in Table 1).

For comparison, as in the current process, after depositing TiN to a thickness of 0.7 μm as described above, an insulating coated and baked layer containing phosphate and colloidal silica as main components is applied to a thickness of 1.5 to 2.0 μm. accomplished. (See (B) in Table 1).

After performing these treatments, strain relief annealing was performed at 800° C. for 2 hours, and the magnetic properties, interlayer resistance, and space factor are summarized in Table 1.

As is clear from Table 1, it is noteworthy that the magnetic properties and space factor of the product of the present invention are far superior, and the interlayer resistance is also equivalent to that of the current product.

(Function) Figure 1 (^) and (B) show a comparison between the process of the present invention and the conventional process.

That is, in the present invention, after forming TiN1 by ion plating as shown in FIG. It was discovered that ultra-low iron loss can be achieved by depositing TiN 1 by ion plating in the conventional process shown in Figure 1 (B), and then by applying phosphate in a separate process. Insulating coating and baking layer 3 whose main components are colloidal silica and colloidal silica.
As mentioned above, this is significantly different from the case where .

The reason for the improvement in properties according to the present invention is that, as shown in FIG. Small (α: 3 Xl0-'/l')
It was discovered that magnetic properties and space factor can be improved by forming a thin TiAiN film that also has insulating properties, and this enables the production of unprecedentedly superior unidirectional silicon steel sheets. can be performed stably. Also this 2
The layer coating can be formed only by ion plating, so TiN is deposited in one line and then Ti is deposited on top of it.
It is sufficient to form a film of 1N, and a significant cost reduction can be achieved. Note that the TiN film at this time is 0.1~
Approximately 5 μm 1 TiAiNOJ to 10 μm is appropriate.

(Example) (^) C: 0.063%, Si: 3.46%,
A10.026%, N: 0.0085%, Se
: 0.025%, Mo: 0.013% and Sn
: 0.15%, (B) C: Q, 042%, Si: i, 33%
, Se: 0.019%.

A hot-rolled sheet (2,Qrnm
) was cold-rolled twice with intermediate annealing at 970° C. to obtain a final cold-rolled sheet with a thickness of 0.20 mm. Then 840
After decarburization and primary recrystallization annealing in wet hydrogen at 85°C
Goss by increasing the temperature from 0℃ to 1050℃ at 3℃/hr.
After developing oriented secondary recrystallized grains, purification annealing was performed in dry H2 at 1200° C. for 8 hours.

After that, the oxide film on the surface of the steel plate was removed and polished to a mirror surface with a center line average roughness of 0.15 μm.
CD method (100OA, 65V) l:J, TiN
(0.7 μm), and on top of that TiAj! N (1,
3 μm) was subjected to ion plating treatment. then 8
Strain relief annealing was performed at 00°C for 2 hours.

Table 2 shows the magnetic properties of the product at that time.

Table 2 (Effects of the Invention) According to the present invention, TiAji! can be formed by ion plating without requiring a separate step of forming an insulating coating and baking layer on the TiN tension film by ion plating!
Since the N coating is particularly formed in the same line, better electromagnetic properties can be particularly advantageously obtained without the increase in cost required by a separate process for forming the coated and baked layer.

[Brief explanation of drawings]

FIG. 1 is a comparison diagram showing the coating structure of the process of the present invention and the conventional process. 1...TiN 2...TiAj! N 3...Insulating coating baking layer

Claims (1)

[Claims] 1. After removing the oxides on the surface of the unidirectional silicon steel plate after finish annealing, a TiN tension film is formed on the polished surface by ion plating, and A method for producing an ultra-low core loss unidirectional silicon steel sheet with excellent thermal stability, which comprises forming a TiAlN film thereon.