JPH0765106B2 - Method for manufacturing low iron loss unidirectional silicon steel sheet - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a unidirectional silicon steel sheet, and particularly to a surface of a steel sheet after finish annealing, which is irradiated with an electron beam (EB) in a direction transverse to the rolling direction. The purpose of this study is to improve the EB irradiation method during the treatment to effectively subdivide the magnetic domains and thus to improve the iron loss characteristics.

In a unidirectional silicon steel sheet, generally, secondary recrystallized grains of a cold-rolled thin sheet that has undergone hot rolling and cold rolling are highly integrated in the (110) [001] orientation (that is, Goss orientation) to obtain a desired magnetic field. It is used for the iron core of transformers and other electric devices, and has a high magnetic flux density (represented by B ₁₀ value) and iron loss (represented by W _17/50 value). However, due to research efforts to date, the plate thickness is now 0.
3 mm B ₁₀ : 1.90 T or more, W _17/50 : 1.05 W / kg or less
In 0.23mm, B _10: 1.89T or more, W _17/50: 0.90W / kg low iron loss grain-oriented silicon steel sheet as described below also began to be manufactured.

However, from the viewpoint of energy saving, the stricter demand for reduction of electric power loss has developed into a loss evaluation system that replaces the reduced iron loss in the US and Europe and adds it to the transformer price. It has become established.

(Prior Art) Japanese Unexamined Patent Publication Nos. 57-2252, 57-53419, 58-26405, and 58-26406 disclose that the surface of a unidirectional silicon steel sheet after finish annealing is rolled. It is disclosed that the laser loss is applied in a direction substantially perpendicular to the direction to reduce the core loss by subdividing the magnetic domain by the introduction of local microstrain, but in this case, so-called strain relief annealing is not used. However, even if it is effective, there is a disadvantage that when the annealing is applied, the local microstrain introduced with great care is released during heating and holding, and the magnetic domain width is expanded and the iron loss reduction effect due to laser irradiation is lost. is there.

On the other hand, the present inventors have succeeded in producing a low iron loss unidirectional silicon steel sheet which does not cause characteristic deterioration despite the above high temperature treatment.

That is, after the final finish annealing according to the usual method of grain-oriented silicon steel sheet, after forming an insulating coating containing phosphate and colloidal silica as a main component, or after the final finish annealing step, formed on the outer surface of the steel sheet. After removing the oxides, the front and back surfaces are polished to a mirror finish.
Then Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, C by CVD, ion plating or ion implantation.
o, Ni, Al, B and Si nitrides and / or carbides and Al,
After forming an ultra-thin tension film consisting of at least one selected from Ni, Cu, W, Si and Zn oxides, after forming an insulating film containing phosphate and colloidal silica as main components,
A low iron loss is achieved by irradiating an electron beam in a direction crossing the rolling direction of the steel sheet.

(Problems to be solved by the invention) Normally, EB irradiation on the surface of a unidirectional silicon steel sheet is performed in a direction perpendicular to the rolling direction of the steel sheet. ) Is constant, it is strong in the widthwise central part of the steel sheet and weak at both ends.

Therefore, the effect of EB scanning on the magnetic domain subdivision of the steel sheet differs between the central part and both ends.As a result, the iron loss differs at each position on the steel plate surface, and the iron loss characteristics at both ends are worse than at the central part. Was leaving a problem with.

This invention advantageously solves the above problems, and when irradiating the surface of the finish-annealed unidirectional silicon steel sheet with EB to reduce the iron loss, the iron loss at each position of the plate surface of the steel sheet is reduced. It is an object of the present invention to provide a suitable EB irradiation method that leads to a uniform reduction of EB.

(Means for Solving the Problems) That is, the present invention is directed to unidirectional silicon having a low iron loss by irradiating the surface of a finish-annealed unidirectional silicon steel sheet with an electron beam in a direction transverse to the rolling direction. When manufacturing a steel sheet, the focal length of the beam is corrected to an appropriate distance by dynamic control of the current of the electromagnetic lens and the current of the deflection coil according to the change in the distance to the surface of the steel sheet due to the scanning of the electron beam. A method for manufacturing a low iron loss unidirectional silicon steel sheet, which comprises irradiating an electron beam.

The present invention will be specifically described below.

FIG. 1 schematically shows an EB irradiation apparatus suitable for carrying out the present invention. In the figure, reference numeral 1 is a high pressure insulator, and 2 is an EB.
Gun 3 is an anode, 4 is a column valve, 5 is an electrode lens, 6 is a deflection coil, 7 is an EB, 8 is a unidirectional silicon steel plate, and 9 and 10 are exhaust ports.

Normally, the EB irradiation on the surface of the steel sheet is performed in a direction perpendicular to the rolling direction as shown in Fig. 2a. At that time, the EB intensity is as shown in Fig. 2b. Since the electric current) is constant, the widthwise central portion (7-
It is strong at 2 ') and weak at both ends (7-1', 7-3 '), so that the magnetic domain subdivision effect of the steel plate by EB scanning becomes different at each position on the plate surface as described above. is there.

Therefore, in the present invention, in order to solve the above problems, EB
The focal length of the EB is corrected according to the change of the focal position due to the scanning of 1. The focal length is corrected by the dynamics of the current of the electromagnetic lens 5 and the current of the deflection coil 6 shown in FIG. This can be done accurately by controlling, and thus the central portion and both end portions of the steel sheet can be scanned with the same EB intensity as shown in FIG. 2c. Hereinafter, such processing is called dynamic focusing.

Next, specific experimental results will be described as the basis of the present invention.

C: 0.043wt% (simply indicated by% below), Si: 3.39%, Mn: 0.0
A slab for silicon steel sheet containing 66%, Se: 0.020%, Sb: 0.023% and Mo: 0.015% was heat-treated at 1360 ° C for 4 hours and then hot-rolled to a thickness of 2.0 mm. And Then, after the uniform annealing at 950 ° C for 3 minutes, the uniform annealing at 950 ° C for 3 minutes, and the intermediate cold annealing at 950 ° C for 3 minutes. And

After that, decarburization and primary recrystallization annealing are performed in wet hydrogen at 820 ° C, and then an annealing separator containing MgO as a main component is applied to the steel sheet surface, and then secondary recrystallization at 850 ° C for 50 hours. Annealing was carried out, followed by purification annealing in dry hydrogen at 1200 ° C. for 5 hours.

After that, an insulating coating film containing phosphate and colloidal silica as a main component is formed on the surface of the steel sheet, and then ordinary EB irradiation (a-1) and EB irradiation by dynamic focusing according to the present invention (a-2). Was applied. For comparison, a steel plate that was not irradiated with EB was also prepared.

In addition, after applying an annealing separator containing Al ₂ O ₃ as a main component to the surface of the above-mentioned primary recrystallization annealed plate, 2
Subsequent recrystallization annealing, followed by purification annealing, lightly pickled the surface, and then electrolytically polishing the surface of the steel plate to a mirror surface of 0.1 μm with a center line average roughness Ra, followed by ion plating (HCD method). And acceleration voltage: 70V, acceleration current: 1000
A, TiN thin film with a thickness of 1.0 μm was formed at a vacuum degree of 7 × 10 ⁻⁴ Torr), and then the same ordinary EB irradiation (b-1) and the EB irradiation according to the present invention (b-2) as described above were formed. After that, an insulating coating mainly composed of phosphate and colloidal silica was formed.

Furthermore, for a part of the sample coated with a thin film of TiN, an insulating coating containing phosphate and colloidal silica as a main component was coated on the surface of the sample, followed by normal EB irradiation (b-3) and according to the present invention. EB irradiation (b-4) was performed.

For comparison, a steel sheet with an insulating coating that did not undergo EB irradiation was also prepared.

Table 1 shows the results of examining the magnetic properties of the product plates thus obtained.

As is clear from the table, when the EB irradiation by the dynamic focusing according to the present invention is performed, the iron loss characteristics are improved as compared with the case where the normal EB irradiation is performed.

(Function) After the finish annealing of the unidirectional silicon steel sheet as described above, the EB irradiation is applied to the unidirectional silicon steel sheet with the insulating coating treatment, or the finish annealed plate is mirror-finished and TiN Iron loss can be reduced by adopting dynamic focusing in the plate width direction when coating the film and then performing EB irradiation before and after the insulating coating.

The reason for this is, as is clear from the schematic illustrations in FIGS. 2B and 2C, that the focal length of the beam is corrected by correcting the focal length of the beam in accordance with the change in the focal position due to the scanning of the EB. This is because it is possible to give a constant irradiation mark in the width direction of the plate, and by this, it is possible to effectively subdivide the magnetic domains over the entire surface of the steel plate, and as a result, a steel plate with low iron loss is obtained. Of.

(Example) C: 0.040%, Si: 3.45%, Mo: 0.015%, Se: 0.025% and Sb: 0.030% C: 0.057%, Si: 3.42%, solAl: 0.026%, S: 0.029%, C
Silicon steel hot-rolled sheet (thickness: 2.2 mm) containing u: 0.1% and Sn: 0.05%, respectively,
After the final cold-rolled sheet with a thickness of 0.20 mm was obtained by cold rolling twice with intermediate annealing at 1050 ° C for 2 minutes, decarburization and primary recrystallization annealing were performed in wet hydrogen at 840 ° C, and then MgO was added. Annealing Separator as Main Component An annealing separator having a composition of Al ₂ O ₃ : 60%, MgO: 35%, ZrO ₂ : 3%, TiO ₂ : 2% was applied.

Among the steel sheets with the subsequent annealing separator, 850
After secondary recrystallization annealing at 50 ° C for 50 hours, 1200 ° C in dry H _{2 for} 5 hours, and annealing for 5 hours.
After the temperature was raised at a rate of 0 ° C./h to carry out secondary recrystallization, purification annealing was carried out in dry H ₂ at 1220 ° C. for 8 hours.

After that, an insulating coating containing phosphate and colloidal silica as a main component was formed on the surface of each of these steel sheets.

In addition, after removing the surface oxide, all steel sheets using the annealing separating agent of b were finished to a mirror surface state by electrolytic polishing and then 1.0 μm by an ion plating device.
After depositing a thick TiN tension coating, an insulating coating similar to that described above was applied.

On the surface of each silicon steel sheet thus obtained, acceleration voltage: 70k
V, sample current: 10 mA, scanning interval: 200 μm, EB irradiation by dynamic focusing at a direction perpendicular to the rolling direction at intervals of 8 mm, and then magnetic properties (average value in the width direction) were examined. Is shown in Table 2.

(Effect of the Invention) Thus, according to the present invention, the effect of improving the iron loss of the grain-oriented silicon steel sheet by EB irradiation can be significantly improved as compared with the conventional case.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an EB irradiation apparatus suitable for carrying out the present invention, FIG. 2a is a diagram showing an EB irradiation trace, and FIGS. 1b and 1c are the conventional method and the method of the present invention, respectively. FIG. 6 is a diagram showing EB intensity in the plate width direction when EB is scanned according to the above. 1 …… High pressure insulator 2 …… EB gun, 3 …… Anode 4 …… Column valve, 5 …… Electron lens 6 …… Deflecting coil, 7 …… EB 8 …… Silicon steel plate, 9,10 …… Exhaust port

Claims (1)

[Claims] 1. A method for producing a unidirectional silicon steel sheet having a low iron loss by irradiating the surface of a finish-annealed unidirectional silicon steel sheet with an electron beam in a direction transverse to the rolling direction of the unidirectional silicon steel sheet. According to the change in the distance to the surface of the steel plate due to the scanning of, the focal length of the beam is corrected to an appropriate distance by the dynamic control of the current of the electromagnetic lens and the current of the deflection coil to irradiate the electron beam. And a method for producing a low iron loss unidirectional silicon steel sheet.