JPH0543945A - Manufacture of low iron loss grain-oriented silicon steel sheet - Google Patents

Abstract

PURPOSE:To stabilize the effect of fractionating a magnetic domain and particularly to improve the magnetostriction in the case it is formed into a laminated iron core as well as noise and the shape of a steel sheet in the case it is used as a transformer in the method for manufacturing a low iron loss grain-oriented silicon steel sheet utilizing the irradiation of electron beams. CONSTITUTION:The surface of a grain-oriented silicon steel sheet subjected to finish annealing and thereafter coated with an insulated film is subjected to continuous or intermittent irradiation by electron beams of 2 to 9J/cm<2> in such a manner that the irradiating width in the rolling direction is regulated to 0.2 to 1.0mm and it elongates in a direction crossed with the rolling direction in zigzags at intervals of 2 to 20mm in the rolling direction, by which a magnetic domain fractionating core can be introduced without deteriorating magnetostriction, noise and the shape of the steel sheet.

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 a low iron loss unidirectional silicon steel sheet using electron beam irradiation,
In addition to stabilizing the magnetic domain subdivision effect, especially the magnetostriction when used as a laminated iron core (hereinafter simply referred to as magnetostriction), noise when used as a transformer (hereinafter simply referred to as noise) and steel plate shape Then, this unidirectional silicon steel sheet is advantageously used as a material for an iron core of a transformer or electric equipment.

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 unidirectional silicon steel sheet is mainly used as an iron core of transformers and other electric devices, and has a high magnetic flux density (represented by B ₈ value) of the product as a magnetic property, and an iron loss (W _{17 /} (Represented by ₅₀ values) is low, and an insulating film with good surface properties is applied. 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 this unidirectional silicon steel sheet is the history of improving the goss orientation secondary recrystallization texture.

[0003]

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. 89.
5, JP-B-57-2252, JP-B-57-53419,
A laser is disclosed in JP-B-58-26405 and JP-B-58-26406, and JP-A-62-96617, JP-A-62-151511, JP-A-62-151516, JP-A-62-151517 and the like propose an epoch-making method for reducing the iron loss by irradiating the surface of the steel sheet with plasma to introduce local micro-strain into the steel sheet to subdivide the magnetic domains. It is disclosed. However, the energy efficiency of each of these methods is as low as 5 to 20%, and thus there is a disadvantage that cost reduction is unavoidable for reducing iron loss.

[0005]

Therefore, the inventors of the present invention have disclosed a method of subdividing a magnetic domain with high energy efficiency, as disclosed in Japanese Patent Laid-Open No.
63-186826, JP-A-2-118022 and JP-A-2-277780. That is, it is a method of locally and intermittently irradiating the surface of a steel sheet with an electron beam generated at a high voltage and a small current in the width direction of the steel sheet intersecting the rolling direction, and press-fitting the coating into the base metal. However, although these methods can improve the magnetic properties, they have a large problem in that it is difficult to stably produce a steel plate having quality as a product because of large variations in magnetostriction, noise and steel plate shape. It is considered that this is because the penetration depth of the electron beam from the steel plate surface to the inside is deeper than that of other methods such as laser.

On the other hand, regarding the magnetic domain subdivision by electron beam irradiation, US Pat. Nos. 4,1997,33 and 4,195,750 each describe an energy density of 60 J / in ² or more for a laminated iron core.
Also, it is disclosed that the energy density of 150 to 4000 J / in ² is used for wound iron cores, but no consideration is given to the penetration depth of the electron beam, and the energy density depends on the type of electron beam irradiation device and the irradiation method. The stable production of the product is difficult because it changes depending on the situation. An object of the present invention is to solve the above problems and propose a method for stably producing a high quality product.

[0007]

The present invention is directed to the rolling direction of an unidirectional silicon steel sheet, which has been subjected to finish annealing and then covered with an insulating coating, with an electron beam having an energy density of ^{2 to} 9 J / cm ^2. Irradiation width of 0.2 to 1.0 mm, which extends continuously or intermittently in a zigzag shape in the direction intersecting the rolling direction.
The method for producing a low iron loss unidirectional silicon steel sheet is characterized in that the step is performed at an interval of 2 to 20 mm.

FIG. 1 shows an electron beam irradiation apparatus used directly in the present invention. Number 1 in the figure is exhaust port 1
a casing for forming a vacuum chamber including a and 1b,
A high pressure insulator 2, an electron gun 3 for emitting electrons, and an electron gun 3 arranged to face the electron gun 3 for accelerating the electrons emitted from the electron gun 3 in a casing 1 having a high vacuum of preferably 10 ⁻² Torr or less. The electron beam 5 is emitted from the anode 4. Further, 6 is a column valve for always maintaining the electron beam generating part in a high vacuum, 7 is a focusing coil for focusing the electron beam 5, and 8 is a traveling direction of the electron beam 5 focused by the focusing coil 7. It is a deflection coil that changes the direction and irradiates a predetermined area of the steel sheet 9. As shown in FIG. 2 (b), this deflection coil 8 realizes intermittent irradiation or continuous irradiation in which the electron beam extends in a zigzag shape in the irradiation width of 0.2 to 1.0 mm in the direction intersecting the rolling direction.

In order to subdivide magnetic domains using the above electron beam irradiation apparatus, a method is provided which enables effective subdivision of magnetic domains by electron beam irradiation without destroying the coating film on the steel sheet. is there. At this time, the EB irradiation can continuously or intermittently irradiate in a zigzag shape with an energy density of ² to 9 J / cm ² , so that not only the magnetic characteristics but also the magnetostriction, noise and steel plate shape can be improved.

Specifically, it is preferable that the film is press-fitted to a depth of 0.01 to 5 μm, and the conditions for generating the electron beam for this purpose are preferably an accelerating voltage of 60 kV to 500 kV and an accelerating current of 5 mA or less. Yes, and the irradiation diameter is 0.1
〜0.5mmφ electron beam spot center interval: 50〜500
Irradiation in μm or continuously is preferred.

Regarding the composition of the grain-oriented silicon steel sheet in the application of the method of the present invention, any of the conventionally known composition is suitable, and the representative compositions are 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 effective 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, Al: 0.005 to 0.10 wt% and N: 0.004 to 0.015 wt% The range of Al and N may be set to the above range for the same reason as the case of MnS system and MnSe system described above. preferable.

As the inhibitor component, the above-mentioned S, S
In addition to e and Al, Cr, Mo, Cu, Sn, Ge, Sb, Te, Bi and P
It is also suitable for the above, and it may be contained in a small amount. The preferable addition ranges of the above components are Cr, Cu, Sn: 0.01 wt% or more, 0.50 wt% or more, respectively.
Below, Mo, Ge, Sb, Te, Bi: 0.005 wt% or more, 0.1 wt%
Hereinafter, P: 0.01 wt% or more and 0.2 wt% or less, and these inhibitor components are suitable for both single use and combined use.

[0014]

Next, the present invention will be described based on experimental examples. C:
0.082 wt%, Si: 3.54 wt%, Mn: 0.82 wt%, Mo: 0.013w
t%, sol.Al: 0.028wt%, Se: 0.021wt%, and Sb:
A silicon steel slab containing 0.022wt% was heated at 1380 ℃ for 4 hours and hot-rolled into a hot rolled sheet with a thickness of 2.2mm.
2 times cold rolling with intermediate annealing for 3 minutes at ℃
The final cold-rolled sheet was 0.23 mm thick. Then, after decarburization and primary recrystallization annealing in wet hydrogen at 840 ° C, MgO was applied on the surface of the steel sheet.
Slurry application of an annealing separator mainly composed of
After performing secondary recrystallization annealing at 850 ° C for 50 hours at 850 ° C / h to grow goth-oriented secondary recrystallized grains preferentially, perform purification annealing for 5 hours in dry hydrogen at 1230 ° C. did. Then, an insulating coating containing phosphate and colloidal silica as main components was formed on the surface of the steel sheet. Then, using the apparatus shown in FIG. 1, an electron beam (voltage: 150 kV, current: 1.00 mA, energy density: 6 J / cm ² ) was applied in a direction orthogonal to the rolling direction of the steel sheet at a scanning interval of 6 mm and a scanning speed: The irradiation at 670 cm / s is performed in the straight line (irradiation width: 150 mm) shown in Fig. 2 (a) and the same figure.
The zigzag pattern shown in (b) (irradiation width: 0.35 mm) was used. For comparison, a sample not subjected to magnetic domain refinement treatment was also prepared.

Table 1 shows the results of examining the magnetic properties, magnetostriction, noise and shape of the steel sheet thus obtained. Magnetostriction is evaluated by excitation VA (normally expressed in VA / kg) and noise is evaluated by db, but the evaluation at this time is usually 1.
The value is shown at 7T / 50Hz. The shape of the steel sheet was evaluated by the amount of deformation of the steel sheet before and after irradiation in the C direction (direction orthogonal to the rolling direction). These evaluations are the same in the experiments and examples shown below.

[0016]

As is clear from Table 1, both the samples subjected to the magnetic domain refinement treatment showed a remarkable improvement in the iron loss as compared to the samples not subjected to the domain refinement treatment, but when the electron beam was linearly irradiated, the same zigzag pattern was observed. It can be seen that the magnetostriction, noise, and deterioration in the shape of the steel sheet are remarkable as compared with the case of irradiating in the shape of a sheet.

Further, the inventors also conducted experiments on the energy density of the electron beam. That is, a steel plate with an insulating coating obtained in the same manner as the experiment whose results are shown in Table 1 is
Electron beam (voltage: 150-225
kV, current: 0.5 to 1.50mA, beam diameter: 0.2 to 0.3mm φ)
Irradiating in a zigzag pattern with a scanning interval of 6 mm and an irradiation width of 0.35 to 0.80 mm in the direction orthogonal to the rolling direction of the steel sheet,
The energy density was changed from 1 to 30 J / cm ² .
For comparison, a sample not subjected to magnetic domain refinement treatment was also prepared. The results of examining the magnetic properties, magnetostriction, noise and shape of the steel sheet thus obtained are shown in FIG. 3, respectively.

As is clear from the figure, when the energy density is 9.0 J / cm ² or less, the magnetic properties, magnetostriction, noise and steel plate shape are all improved, but the iron loss is less than 2.0 J / cm ^2. Deteriorated. Therefore, the energy density is 2.0 to 9.
By setting the range to 0 J / cm ² , all of the magnetic characteristics, magnetostriction, noise and steel plate shape can be further improved.

Disadvantages caused by electron beam irradiation, particularly, are magnetostriction, noise, and deterioration of the shape of the steel sheet, because electron beams have high energy efficiency and can be narrowed down.
This is because the micro strain is deeply dispersed in the steel sheet irradiated with the electron beam. Therefore, by performing electron beam irradiation in a zigzag manner and at an energy density of 2.0 to 9.0 J / cm ² , it is possible to increase the frequency of generation of domain wall nuclei that can subdivide a 180 ° magnetic domain. As a result, the magnetic domains can be sufficiently subdivided at a lower energy density than that disclosed in the already-known U.S. Pat. Nos. 4,1997,33 and 4,195,750. Further, according to the present invention, by providing such an energy density, it is possible for the first time to improve the magnetic characteristics as well as the magnetostriction, the noise and the shape of the steel plate. Therefore, although the above-mentioned U.S. patents can improve the magnetic characteristics, they have problems with magnetostriction, noise, and the shape of the steel sheet, and it has been impossible to manufacture a product.

[0021]

【Example】

(A) C: 0.044 wt%, Si: 3.42 wt%, Mn: 0.068 wt
%, Mo: 0.012 wt%, Se: 0.019 wt% and Sb: 0.023 wt
% (B) C: 0.068 wt%, Si: 3.41 wt%, Mn: 0.082 wt%,
Mo: 0.015 wt%, Se: 0.025, Cu: 0.2 wt%, Sn: 0.05 wt%
And a silicon steel slab containing Al: 0.021 wt% were heated at 1380 ℃ for 4 hours and hot-rolled to a hot rolled sheet with a thickness of 2.2mm.
After performing cold rolling twice with intermediate annealing for 3 minutes at 0.
The final cold rolled sheet had a thickness of 23 mm. Then, after decarburizing and primary recrystallization annealing in wet hydrogen at 840 ° C, an annealing separator containing MgO as the main component is slurry-coated on the surface of the steel sheet, and then 10 ° C.
After performing secondary recrystallization annealing at 850 ° C for 50 hours at a temperature of / h to preferentially grow Goss-oriented secondary recrystallized grains, then perform purification annealing in dry hydrogen at 1230 ° C for 5 hours. .. Then, an insulating coating containing phosphate and colloidal silica as main components was formed on the surface of the steel sheet. Then, using the device shown in Fig. 1, an electron beam [voltage: 150 kV, current: 1.0 mA, beam diameter: 0.30 mm
φ (by knife edge method), vacuum degree: 5 × 10 ^-4 Torr]
Was irradiated in a zigzag shape with an irradiation width of 0.5 mm and a scanning interval of 6 mm in a direction orthogonal to the rolling direction of the steel sheet at an energy density of 6.4 J / cm ² . Table 2 shows the results of examining the magnetic properties, magnetostriction, noise and steel plate shape of the product thus obtained.

[0022]

[0023]

According to the present invention, excellent magnetic characteristics,
In particular, a unidirectional silicon steel sheet with a low iron loss can be produced without causing magnetostriction, noise and deterioration of the steel sheet shape,
An excellent product can be stably provided.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an electron beam irradiation apparatus used in the method of the present invention.

FIG. 2 is a schematic diagram showing an electron beam irradiation procedure.

FIG. 3 is a graph showing the relationship between electron beam energy density, iron loss, magnetostriction, noise, and steel plate shape.

[Explanation of Codes] 1 casing 1a exhaust port 1b exhaust port 2 high pressure insulator 3 electron gun 4 anode 5 electron beam 6 column valve 7 focusing coil 8 deflection coil 9 steel plate

Claims (1)

[Claims] 1. An energy density of 2 to 9 is formed on the surface of a unidirectional silicon steel sheet on which an insulating coating is applied after finishing annealing.
Irradiation width in the rolling direction is 0.2 with an electron beam of J / cm ^2.
A method for producing a low iron loss unidirectional silicon steel sheet, characterized in that continuous or intermittent irradiation extending in a zigzag shape in a direction intersecting with the rolling direction at an interval of ~ 1.0 mm is carried out at an interval of 2 to 20 mm in the rolling direction.