JPH0565543A - Manufacture of low iron loss unidirectional silicon steel sheet having uniform characteristic in transverse direction without deteriorating magnetic characteristic even in the case of applying strain-removal annealing - Google Patents

Abstract

PURPOSE:To advantageously manufacture a low iron loss unidirectional silicon steel sheet having the uniform characteristic in the traverse direction of the steel sheet without deteriorating magnetic characteristic even in the case of applying strain removal annealing. CONSTITUTION:By using deflected electron beam on the surface of the unidirectional silicon steel sheet after executing the finish annealing to form fine pressing-in range lined up at the same intervals in the transverse direction of the steel sheet, magnetic domain fined nuclei which are not eliminated even after the strain-removal annealing are introduced so as not to change the physical property in the transverse direction of the steel sheet.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a low iron loss unidirectional silicon steel sheet having no deterioration of magnetic properties even after strain relief annealing and having uniform properties in the width direction, and particularly to a high voltage,
This unidirectional silicon steel sheet is a material for iron cores of transformers and electric equipment, with an ingenuity in the treatment of the steel sheet after irradiation with an electron beam generated by a small current to enhance the effect of magnetic domain refinement. Is used advantageously.

A unidirectional silicon steel sheet is obtained by highly accumulating secondary recrystallized grains of a product in a Goss orientation, forming a forsterite coating on the surface of the steel sheet, and further forming an insulating coating having a small coefficient of thermal expansion on it. It is intended to improve the magnetic properties by, for example, applying a tension to the steel sheet by coating, and is manufactured through complicated and various processes that require strict control.

Such a unidirectional silicon steel sheet is mainly used as an iron core of a transformer and other electric equipment,
Magnetic flux density of products as magnetic characteristics (represented by B ₈ value)
High, and low iron loss ( _typically W _17/50 value),
Further, it is required to form an insulating film having a good surface property. In particular, the demand for the reduction of power loss has been remarkably strengthened at the border of the energy crisis, and the need for unidirectional silicon steel sheet with lower iron loss as an iron core material for a transformer is increasing more and more.

It is no exaggeration to say that the history of improving the iron loss of the unidirectional silicon steel sheet is the history of improving the goth-oriented secondary recrystallization texture.

[0005]

2. Description of the Related Art As a method for controlling secondary recrystallized grains, Al
A method of preferentially growing secondary recrystallized grains of Goss orientation using a primary recrystallized grain growth inhibitor such as N, MnS, and MnSe, a so-called inhibitor has been implemented. On the other hand, various iron loss improving techniques different from the metallurgical means for controlling the secondary recrystallization texture have been developed. That is, Tadashi Ichiyama: Iron and Steel, 69 (1983), P. 895, Japanese Patent Publication No. 57-2252, Japanese Patent Publication No.
A laser is disclosed in JP-A-57-53419, JP-B-58-26405, JP-B-58-26406, and the like, and JP-A-62-
96617, JP 62-151511, JP 62-15
Japanese Patent Laid-Open No. 1516 and Japanese Patent Application Laid-Open No. 62-151517 disclose an epoch-making technique of irradiating plasma on the surface of a steel sheet to introduce local micro-strain into the steel sheet to subdivide magnetic domains and reduce iron loss. Various methods have been proposed and disclosed. However, the steel sheet obtained by these methods has a drawback that the above effects cannot be exhibited when used for a wound core transformer material subjected to high temperature strain relief annealing, because minute strain disappears when heated to a high temperature range. It was

[0006] On the other hand, a method has been proposed and disclosed in which iron loss is not deteriorated even if such high temperature strain relief annealing is performed.
That is, Japanese Patent Publication No. 50-35679, JP-A-59-28525
JP-A-59-197520 and the like, a method of forming grooves or serrations on the surface of the finish annealed plate,
JP-A-56-130454 discloses a method for forming fine recrystallized grain regions on the surface of a finish annealed plate, JP-A-60-92479, JP-A-60-92480 and JP-A-60-. Japanese Patent No. 92481 and Japanese Patent Laid-Open No. 60-258479 disclose a method of forming a different thickness or defective region in a forsterite coating,
JP-A-60-103124, JP-A-60-103182 and the like disclose a method of forming a different composition region in a base metal, a forsterite coating, or a tension-imparting insulating coating.

However, none of these methods have been industrially adopted because the effect of reducing iron loss is small in spite of the complicated process and the manufacturing cost is high.

[0008]

Therefore, the inventors have proposed a method disclosed in Japanese Patent Laid-Open No. 2-277780 as an industrial manufacturing method in which iron loss is not deteriorated even when strain relief annealing is performed. That is, it is a method of locally and intermittently irradiating the surface of the steel sheet with an electron beam in the width direction of the steel sheet intersecting the rolling direction and press-fitting the coating into the base steel. However, in this method, there is a large variation in the magnetic properties in the width direction of the steel sheet, which is the direction of electron beam irradiation, and 90 ° bending characteristics of the steel sheet (hereinafter referred to as bendability), which is particularly important as a material for wound cores.
Also, there was a problem in that the adhesion of the insulating coating to the base steel (hereinafter referred to as peeling resistance) varies in the width direction.

The present invention provides a unidirectional silicon steel sheet having iron loss improved by magnetic domain refinement, which is not deteriorated even after subsequent strain relief annealing, and which has uniform characteristics in the width direction of the steel sheet. The aim is to propose a method for stable and advantageous production.

[0010]

The inventors investigated the cause of the variation in the characteristics of the unidirectional silicon steel sheet in the width direction, and as shown in FIG. 1, the conventional electron beam irradiation showed a beam deflection angle θ. Since it was adjusted uniformly, the distance between electron beam point irradiation marks (hereinafter referred to as spots) was different between the central portion and the end portion in the width direction of the steel sheet, and the physical properties between the central portion and the end portion changed. It has been found. The present invention has been completed based on the finding that it is effective to irradiate the electron beam in a widthwise direction at regular intervals in order to suppress variations in characteristics.

That is, the gist of the present invention is the surface of a unidirectional silicon steel sheet having a forsterite coating obtained by finish annealing, or the surface of a unidirectional silicon steel sheet obtained by forming an insulating coating on the forsterite coating. In order to locally and intermittently irradiate an electron beam generated by a high voltage and a small current in the width direction of the steel sheet that intersects the rolling direction, a minute press-fitting lined up at equal intervals in the width direction of the steel sheet using a deflected electron beam. A method for producing a low iron loss unidirectional silicon steel sheet having a uniform property in the width direction without deterioration of magnetic properties even after strain relief annealing characterized by forming a region.

Further, in order to improve the magnetic characteristics, it is advantageous to further perform etching after the irradiation of the electron beam, and when this etching is performed, it is preferable to further form an insulating film. Here, the electron beam has a weak point that it has to be used under a high vacuum, but it has advantages such as narrow diameter, easy scanning, deep penetration and high energy efficiency. , More recently 10
Combined with the development of an electron beam with a high voltage of 0 kV or more and a small current of 10 mA or less, it is advantageously suitable for magnetic domain subdivision processing of unidirectional silicon steel sheet. In the local intermittent irradiation of electron beams, the irradiation areas of the electron beams that diverge the spot center intervals from each other are called local areas, and a single irradiation is performed in each spot.

Further, in order to obtain a low iron loss by subdividing the magnetic domains, the forsterite coating or the forsterite coating and the insulating coating is applied to the interior of the base metal in a very narrow range by electron beam irradiation. Is preferably pressed to a depth of 0.05 to 100 μm, and the electron beam generation condition for this is to set the acceleration voltage to 100 KV to 500 KV and the acceleration current to 0.05 mA to 10 mA. It is preferable to irradiate an electron beam having an irradiation diameter of 0.5 mmφ or less with a spot center interval of 50 to 500 μm and a scanning interval of 1 to 20 mm. Although the present invention is applicable not only to the rolled iron core steel plate but also to the laminated iron core steel plate, the spot center interval and scanning interval of the electron beam are widened in the laminated iron core steel plate.

Further, in the present invention, it is essential to make the spot center intervals of the electron beams equal in the width direction of the steel plate, and specifically, it is preferable to use the deflection coil of the electron optical system. That is, as shown in FIG. 2, an alignment coil 4, a focusing coil 5 and a deflection coil 6 are arranged in this order from the gun 1 on the path of the electron beam 2 from the electron beam gun 1 to the steel plate 3 so that the electron beam passes through the center. First, the alignment coil 4 adjusts the position in the X-axis and Y-axis directions, then the focusing coil 5 narrows the electron beam diameter to a predetermined value, and finally the CPU 7 controls the current to the deflection coil 6 to control the electron beam diameter. The deflection amount of the beam 2 is adjusted to make the spot center intervals equal in the width direction of the steel sheet as shown in FIG. Compared to the conventional method shown in FIG. 1, this method can perform spot irradiation on a steel sheet at equal intervals (equal distance). That is, in the current method for uniformly adjusting the beam deflection angle θ as shown in FIG. 1, the center portion and the end portion have different width-direction intervals, so that the characteristics also change.

Next, the etching performed after the electron beam irradiation is intended to ensure the subdivision of the magnetic domain by further deeply etching the base iron in the region of the electron beam irradiation where the pressure is small. Alternatively, it may be dipped in a solution of nitric acid or the like, or may be performed by known electrolytic etching. Electrolytic etching is performed with a current density of 5-40 A / dm ² and NaC
It may be performed for 0.1 to 20 seconds using an etching solution such as l, HCl, H ₂ SO ₄ . The forsterite coating or insulating coating in the electron beam irradiation area is damaged by the electron beam irradiation, and this portion is easily etched. After etching, it is preferable to form an insulating film in order to maintain the insulating property of the electron beam irradiation region. For the formation of the insulating coating, it is preferable to use a low thermal expansion coating treatment liquid containing phosphate and colloidal silica as the main components, and it is usually applied on the surface of the steel sheet at 1 to 10 g / m ² .

Regarding the composition of the grain-oriented silicon steel sheet with respect to the application of the method of the present invention, any of the conventionally known composition is suitable, but the representative composition is as follows. C: 0.01 to 0.10 wt% Not only the refinement of the structure during hot rolling and cold rolling but also
It is an element useful for the development of the Goss orientation, and at least 0.01
Addition of wt% or more is preferable. However, if the content exceeds 0.10 wt%, the Goss orientation is rather disturbed, so the upper limit is preferably 0.10 wt%. Si: 2.0 to 4.5 wt% Increases the specific resistance of steel sheet and effectively contributes to the reduction of iron loss.
If it is less than 0 wt%, not only the resistivity decreases, but also α- during the final high temperature annealing for secondary recrystallization and purification.
The gamma transformation causes the crystal orientation to be randomized, so that a sufficient iron loss improving effect cannot be obtained, and if it exceeds 4.5 wt%, cold ductility is impaired. Therefore, the lower limit is 2.0 wt% and the upper limit is
It is preferably 4.5% by weight. Mn: 0.02 to 0.12 wt% At least 0.02 wt% is necessary to prevent hot embrittlement, but if it is too much, the magnetic properties deteriorate, so the upper limit is preferably 0.12 wt%.

The inhibitors are roughly classified into MnS and Mn.
There are Se series and AlN series. In case of MnS and MnSe system, S: 0.
At least one selected from 005 to 0.06 wt% and Se: 0.005 to 0.06 wt% S and Se are both powerful elements as inhibitors for controlling the secondary recrystallization of grain-oriented silicon steel sheet. Both require at least about 0.005 wt% from the viewpoint of securing suppression, but if it exceeds 0.06 wt%, its effect is impaired, so it is preferable to set the lower limit to 0.005 wt% and the upper limit to 0.06 wt%. ..

In the case of AlN system, the range of Al: 0.005 to 0.10 wt% and N: 0.004 to 0.015 wt% Al and N is set to the above range for the same reason as in the case of MnS system and MnSe system described above. Preferably. As the inhibitor component, in addition to S, Se and Al described above, Cr, Mo, Cu, Sn, Ge, Sb, Te, Bi and P are also suitable, and a small amount of each may be contained. Good. The preferred addition ranges of the above components are Cr, Cu, Sn: 0.01 wt% or more, 0.50 wt% or less, Mo, G
e, Sb, Te, Bi: 0.005 wt% or more, 0.1 wt% or less, P:
It is 0.01 wt% or more and 0.2 wt% or less, and these inhibitor components are suitable for both single use and combined use.

[0019]

Next, the present invention will be described based on experimental examples. C: 0.082 wt%, Si: 3.54 wt%, Mn: 0.82 wt%, Mo:
0.013wt%, sol.Al: 0.028wt%, Se: 0.021wt%, and
Sb: silicon steel slab containing 0.022 wt% at 1380 ° C
After heating for an hour, hot rolling into a hot rolled sheet with a thickness of 2.2 mm,
Two cold-rollings were carried out with intermediate annealing at 1050 ° C. for 3 minutes to obtain a final cold-rolled sheet having a thickness of 0.23 mm. Then, after decarburizing and primary recrystallization annealing in wet hydrogen at 840 ℃,
An annealing separator containing MgO as a main component was applied as a slurry, and then secondary recrystallization annealing was performed at 850 ° C for 50 hours at a temperature rise of 10 ° C / h to preferentially grow goth-oriented secondary recrystallized grains. After 1230
Purification annealing was performed for 5 hours in dry hydrogen at ℃. Then, an insulating coating containing phosphate and colloidal silica as main components was formed on the surface of the steel sheet. Thereafter, the following magnetic domain refinement treatments (a) to (d) were performed, and further strain relief annealing was performed at 800 ° C. for 2 hours.

Note (a): CO ₂ laser (output: 1.5 kW, beam diameter: 0.2 mm
φ) in the direction orthogonal to the rolling direction of the steel sheet, the scanning interval: 5
mm and scanning speed: 12 m / s, after irradiating for 30 seconds in nitric acid with a concentration of 60%, then an insulating coating was applied. (b): As shown in Fig. 2, the electron beam (voltage: 22
After irradiation with 5 kV, current: 0.9 mA) in the direction orthogonal to the rolling direction of the steel sheet at a spot center interval of 200 μm and a scanning interval of 5 mm, some of the samples were treated with NaCl at a concentration of 30%. After electrolytic etching (20 A / dm ² , 5 s), an insulating film was formed.

(C): According to the conventional method shown in FIG. 1, the above (b)
Processing was performed under the same conditions as in. (d): As shown in Fig. 2, the electron beam (voltage: 65
(kV, current: 1.5 mA) was applied in the direction orthogonal to the rolling direction of the steel sheet at a spot center interval of 200 μm and a scan interval of 5 mm, and some of the samples were electrolyzed in NaCl of 30% concentration. After performing etching (20 A / dm ² , 5 s), an insulating film was formed.

For comparison, a sample not subjected to the magnetic domain subdivision treatment was also prepared. Table 1 shows the results of examining the magnetic properties, bendability, peeling resistance, surface irregularities, and space factor of the steel sheet thus obtained.

[0023]

[Table 1]

As is clear from Table 1, the steel sheet which has been subjected to the treatment (b) is excellent in all of magnetic properties, bendability, peeling resistance, surface irregularities and space factor. In addition, as shown in Fig. 4, which shows the measurement results of the steel plate surface after being irradiated with a CO ₂ laser or electron beam by a three-dimensional roughness meter, the steel plate that has undergone the treatment of (a) has wide grooves, and therefore bend peeling occurs. Sex and space factor are deteriorated. On the other hand, in the steel sheet that has been subjected to the treatment of (b), the micro press-fitting region is formed in a narrow range, in particular, deeper in comparison with the treatment of (c), and thus effective subdivision of the magnetic domain and bend peeling property and The space factor has been improved.

[0025]

EXAMPLES Example 1 (A) C: 0.043 wt%, Si: 3.25 wt%, Mn: 0.068 wt
%, Mo: 0.013 wt%, Se: 0.019 wt% and Sb: 0.025 wt
% (B) C: 0.82 wt%, Si: 3.30 wt%, Mn: 0.072 wt%, M
For a 0.23 mm thick finished annealed plate with a forsterite coating produced using a silicon steel slab containing o: 0.015 wt%, Se: 0.022 wt%, and Al: 0.028 wt%, 25
An electron beam generated at 0 kV, 0.7 mA is irradiated at a spot center interval of 150 μm and a scanning interval of 5 mm, and then an insulating film containing phosphate and colloidal silica as a main component is formed at 800 ° C. Strain relief annealing was performed for 2 hours.

The magnetic properties of the products thus obtained are as follows, and products exhibiting excellent iron loss even after high-temperature strain relief annealing were obtained. (A) B ₈ : 1.90 T, W _17/50 : 0.79 W / kg (B) B ₈ : 1.92 T, W _17/50 : 0.77 W / kg Also, the bend characteristics and peeling resistance of these products are
Both the end and center of the steel sheet in the width direction were good.

[0027]

According to the present invention, a unidirectional silicon steel sheet whose core loss does not deteriorate even when subjected to strain relief annealing is stably manufactured without causing variations in various properties in the width direction of the steel sheet. It is possible to provide a product which is particularly suitable for a material for wound core.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a conventional electron beam irradiation procedure.

FIG. 2 is a schematic diagram showing an electron beam irradiation device used in the present invention.

FIG. 3 is a schematic diagram showing an electron beam irradiation procedure according to the present invention.

FIG. 4 is a schematic diagram showing a measurement result of surface roughness.

[Explanation of symbols]

 1 Electron Beam Gun 2 Electron Beam 3 Steel Plate 4 Alignment Coil 5 Focusing Coil 6 Deflection Coil 7 CPU

Claims (4)

[Claims] 1. A high voltage is applied to the surface of a unidirectional silicon steel sheet having a forsterite coating obtained by finish annealing.
When locally irradiating the electron beam generated with a small current in the width direction of the steel sheet intersecting the rolling direction, form small press-fitted regions arranged at equal intervals in the width direction of the steel sheet using the deflected electron beam. A method for producing a low iron loss unidirectional silicon steel sheet having no deterioration in magnetic properties even after strain relief annealing and having uniform properties in the width direction. 2. Electrons generated at high voltage and small current on the surface of a unidirectional silicon steel sheet having a forsterite coating obtained by finish annealing and having an insulating coating on the forsterite coating. When locally intermittently irradiating the beam in the width direction of the steel sheet that intersects the rolling direction, a strain relief annealing characterized by forming minute press-fitted regions arranged at equal intervals in the width direction of the steel sheet by using a deflected electron beam. A method for producing a low iron loss unidirectional silicon steel sheet which has uniform characteristics in the width direction without deterioration of magnetic properties afterwards. 3. The method according to claim 1, further comprising etching after irradiation with the electron beam. 4. The method of claim 3, further comprising depositing an insulating coating after the etching.