JPH02118022A - Manufacture of grain oriented silicon steel sheet reduced in iron loss - Google Patents

Abstract

PURPOSE:To make uniform and reduce iron losses in respective positions at a sheet surface by irradiating the surface of a finish-annealed grain-oriented silicon steel sheet with an electron beam having an intensity distribution uniform in a width direction so that the electron beam is scanned across the above sheet surface in a direction across the rolling direction of the sheet. CONSTITUTION:A finish-annealed grain-oriented silicon steel sheet 8 is irradiated with an EB(electron beam) 7 from an EB gun 2 having a high voltage insulator 1 via an anode 3 and a column valve 4, and the electron beam 7 is scanned across the surface in a direction across the rolling direction of the above steel. By the above procedure, local microstrain nearly perpendicular to the rolling direction is introduced into the surface of the above silicon steel sheet 8, by which a grain-oriented silicon steel sheet reduced in iron loss is obtained. At this time, by dynamically controlling the above EB 7 by means of an electric current from an electromagnetic lens 5 and an electric current from a deflection coil 6, respective focal distances toward focuses 7-1, 7-2, 7-3 in the width-direction central part and both edge parts of the above silicon steel sheet 8 can be properly corrected. By this method, the uniformization and reduction of iron loss mentioned above can be attained and, as a result, the low-iron-loss grain-oriented silicon steel sheet in which iron loss is uniformly reduced in respective positions at the sheet surface can be obtained.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing a grain-oriented silicon steel sheet, and in particular to irradiating the surface of the steel sheet after finish annealing with an electron beam (EB) in a direction transverse to the rolling direction. By adding innovations to the EB irradiation method used in the EB process, the aim is to achieve effective subdivision of magnetic domains and, in turn, to advantageously improve iron loss characteristics.

Unidirectional silicon steel sheets are generally made by highly accumulating secondary recrystallized grains of cold-rolled sheets that have undergone hot rolling and cold rolling in the (110) (001) orientation (i.e., Goss orientation) to achieve the desired magnetic properties. It is mainly used in the iron cores of transformers and other electrical equipment, and has a high n flux density (represented by the Boo value) and iron loss (represented by the W+, zs value). )
However, due to past research efforts, we have now achieved Boo: 1.90T or more, W+tzso: 1.05 W/kg or less for a plate thickness of 0.3 mm, and B1° for a plate thickness of 0.23 mm. : 1.89T or more, WI?
15°: Unidirectional silicon steel sheets with low iron loss of 0.90 W/kg or less can now be manufactured.

However, from the standpoint of energy conservation, demands for more stringent reductions in power loss have led to the development of loss evaluation systems, particularly in Europe and the United States, in which the reduction in iron loss is converted into cash and added to the transformer price. It has also become established.

(Prior art) JP-A-57-2252, JP-A-57-53419, JP-A-5
No. 8-26405 and No. 58-26406 disclose that the surface of a grain-oriented silicon steel sheet after finish annealing is irradiated with a laser in a direction substantially perpendicular to the rolling direction to introduce local minute strain. It has been disclosed that magnetic domain refining is used to reduce iron loss, but in this case, although it is effective in applications where so-called strain relief annealing is not added, when such annealing is performed, the introduced local There is a disadvantage that microstrains are released during heating and holding, the magnetic domain width expands, and the iron loss reduction effect by laser irradiation is lost.

On the other hand, the inventors have previously succeeded in producing a low core loss unidirectional silicon steel sheet that does not suffer from characteristic deterioration despite the above-mentioned high-temperature treatment.

That is, after final finish annealing according to the usual method for grain-oriented silicon steel sheets, an insulating film containing phosphate and colloidal silica as the main components is formed, or after the final annealing process described above, the insulating film is 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, N are deposited by CVD, ion blating or ion implantation.
b, Ta, Cr, Mo.

W, Mn, Co, Ni, AI! ,, B and S
i nitride and/or carbide and Aj! , Ni,
After forming an ultra-thin tensile coating made of at least one oxide selected from Cu, W, Si, and Zn oxides, an insulating coating mainly composed of phosphate and colloidal silica is formed, and then the steel plate is rolled. Low iron loss is achieved by irradiating an electron beam in a direction that crosses the direction.

(Problem to be Solved by the Invention) Normally, EB irradiation on the surface of a unidirectional silicon plate is performed perpendicular to the rolling direction of the steel plate, but the EB intensity is determined by the current of the electromagnetic lens (focus Since the current (current) is constant, it is strong at the center in the width direction of the steel plate and weak at both ends.

Therefore, the magnetic domain refining effect of the steel plate due to EB constant scanning is different between the center and both ends, resulting in a difference in iron loss at each position on the steel plate surface, and the iron loss characteristics at both ends are worse than at the center. There remained a problem.

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

(Means for Solving the Problems) That is, the present invention irradiates the surface of a finish-annealed unidirectional silicon steel sheet with an electron beam in a direction transverse to its rolling direction to produce unidirectional silicon steel with low core loss. When manufacturing steel plates, a low iron loss method characterized in that electron beam irradiation is performed by adjusting the focal length of the beam to an appropriate distance according to changes in the distance to the steel plate surface as the electron beam scans. This is a method for manufacturing a unidirectional silicon steel sheet.

This invention will be specifically explained below.

FIG. 1 schematically shows an EB irradiation device suitable for carrying out the present invention, in which numeral 1 is a high-pressure insulator, 2 is an EB gun, 3 is an anode, 4 is a column valve, 5 is an electromagnetic lens,
6 is a deflection coil, 7 is an EB, 8 is a grain-oriented silicon steel plate, and 9 and 10 are exhaust ports.

Normally, EB irradiation onto the surface of a steel plate is performed in a direction perpendicular to the rolling direction as shown in Figure 2a. Since the current (current) is constant, the central part in the width direction of the steel plate (
It is strong at 7-2') and weak at both ends (7-1', 7-3'), which is why the magnetic domain refining effect of the steel sheet due to EB constant scanning is different at each position on the sheet surface, as mentioned above. As I said.

Therefore, in this invention, in order to solve the above problem,
The focal length of EB is corrected according to the change in the focal position accompanying the scanning of B, and the correction of the focal length is performed using the current of the electromagnetic lens 5 and the current of the deflection coil 6 shown in FIG. This can be done accurately by performing dynamic control with the EB, and as a result, the center and both ends of the steel plate can be scanned with the same EB intensity, as shown in FIG. 2C. Hereinafter, such processing will be referred to as dynamic focus swing.

Next, specific experimental results that form the basis of this invention will be explained.

C: 0.043 wt% (hereinafter simply expressed as %), S
i: 3.39%, Mn: 0.066%, Se
: 0.020%, Sb: 0.023% and Mo
: A slab for silicon steel plate containing 0.015%
After heat treatment at 360°C for 4 hours, it was hot rolled to a thickness of 2. It was made into an OM hot rolled sheet. Then, after homogenization annealing at 950°C for 3 minutes, cold rolling was performed twice with intermediate annealing at 950°C for 3 minutes to obtain a final cold-rolled sheet with a thickness of 0.20 mm.

Then, after decarburization and primary recrystallization annealing in wet hydrogen at 820"C, an annealing separator containing MgO as a main component was applied to the surface of the steel plate, and then secondary recrystallization at 850°C for 150 hours. Annealing was performed, followed by purification annealing at 1200° C. for 25 hours in dry hydrogen.

After that, an insulating coating film mainly composed of phosphate and colloidal silica is formed on the surface of the steel sheet, and then normal EB irradiation (a-1) and EB irradiation by dynamic focusing according to the present invention (a-2) are performed. was applied. For comparison, a steel plate without EB irradiation was also prepared.

Furthermore, after applying an annealing separator mainly composed of AlzOy to the surface of the above-mentioned primary recrystallization annealed plate, secondary recrystallization annealing and purification annealing were performed under the same conditions as above, and then the surface was lightly annealed. After pickling and electrolytic polishing, the steel plate surface was finished to a mirror surface with a center line average roughness R of 0.1 μm.
Ion blating device (accelerating voltage near 0 using HCD method)
■, Accelerating current: 1000A, Vacuum degree: 7 Xl0-
'Torr) to form a thin film of TiN with a thickness of 1.0, l/m, followed by normal EB irradiation (
b-1) and EBB10b-2) according to the present invention were performed, and then an insulating film containing phosphate and colloidal silica as main components was formed.

Furthermore, for some of the samples covered with a thin TiN film,
After an insulating film containing phosphate and colloidal silica as main components was formed on the surface, normal EB irradiation (b-3) and EB irradiation according to the present invention (b-4) were performed.

For comparison, a steel plate with an insulating coating that was not subjected to EB irradiation was also prepared.

Table 1 shows the results of investigating the magnetic properties of each product board thus obtained.

Table 1: Namic Focus Ink As is clear from the table, the iron loss characteristics are improved in all cases where EB irradiation by dynamic focusing according to the present invention is applied, compared to those subjected to normal EB irradiation. .

(Function) After final annealing of a unidirectional silicon steel sheet, when applying EB irradiation to the unidirectional silicon steel sheet that has been subjected to insulation coating treatment, or after finishing the final annealing sheet to a mirror finish, TiN Iron loss can be reduced by applying dynamic focusing in the board width direction when coating the film and then applying EB irradiation before and after insulating coating.

The reason for this is that, as shown schematically in Fig. 2(b), by correcting the focal length of the beam according to the change in focal position due to EB scanning, This is because it is possible to give a certain irradiation mark, and as a result, it is possible to effectively subdivide sections over the entire surface of the steel plate, and as a result, a steel plate with low core loss can be obtained.

(Example) @ C: 0.040%, Si: 3.45%,
Mo: 0.015%.

Se: 0.025% and Sb: 0.030%
C: 0.057%, Si: 3.42%
, 5oj2Aj2: 0.026%, S: 0
．． 029%, Cu: 0.1% and Sn: 0.05
A silicon steel hot-rolled plate (thickness: 2.2 mm) containing After decarburization and primary recrystallization annealing in wet hydrogen at °C, annealing separator containing 0Mg0 as the main component AlzOx: 60%, MgO: 35%, Z
r0z: 3%.

An annealing separator having a composition of TiOz: 2% was applied.

Next, among the steel plates using the annealing separator (■), 850
After secondary recrystallization annealing for 150 hours at °C, 120 °C in dry H2
Purification annealing was performed at 0°C for 15 hours, while O was 850"
After secondary recrystallization by raising the temperature from C to 1050°C at a rate of 10°C/h, purification annealing was performed in dry H2 at 220°C for 18 hours.

Thereafter, an insulating coating containing phosphate and colloidal silica as main components was formed on the surface of these steel plates.

In addition, after removing surface oxides from the steel sheets using the annealing separator b, they were finished to a mirror-like finish by electrolytic polishing, and then polished to a 1.0 μm diameter using an ion blating device.
After a tension coating of 〒iN thickness was applied, an insulating coating similar to that described above was applied.

The surface of each silicon steel plate thus obtained was applied with an accelerating voltage of near 0, a sample current of 10 mA, and a scanning frequency of 200 μ.
Table 2 shows the results of examining the magnetic properties (average value in the sheet width direction) after applying EB irradiation by dynamic focusing at intervals of 8 mm perpendicular to the rolling direction under conditions of 50 m.

Table 2 (Effects of the Invention) Thus, according to the present invention, the effect of improving the iron loss of a grain-oriented silicon steel sheet by EB irradiation can be significantly improved by one degree compared to the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an EB irradiation device suitable for carrying out the present invention, FIG. 2 a is a diagram showing EB irradiation traces, and FIG. FIG. 3 is a diagram showing the EB intensity in the board width direction when the EB is scanned according to the above. 1...High pressure insulator 2...EB gun 3...Anode 4...Column valve 5...Electron lens 6...Deflection coil 7...EB8...Silicon steel plate 9.
10... Exhaust port patent applicant Kawasaki Steel Corporation Figure 1

Claims (1)

[Claims] 1. In manufacturing a unidirectional silicon steel plate with low iron loss by irradiating the surface of a finish annealed unidirectional silicon steel plate with an electron beam in a direction transverse to the rolling direction. , A low iron loss unidirectional silicon steel plate characterized in that the electron beam irradiation is performed by correcting the focal length of the beam to an appropriate distance according to the change in the distance to the steel plate surface as the electron beam scans. Production method.