JPH02138421A - Production of low-iron loss unidirectional silicon steel sheet - Google Patents

Abstract

PURPOSE:To stably produce the low-iron loss unidirectional silicon steel sheet having uniform magnetic characteristics by irradiating the surface of the unidirectional silicon steel sheet after finish annealing with sheet plasma in the direction orthogonal with the rolling direction. CONSTITUTION:Sheet plasma 6 generated by a low voltage and large current from an HCD gun 1 having a hollow cathode 2 is made into the sheet shape of the length corresponding to at least the width of the unidirectional silicon steel sheet 8 subjected to finish annealing by control of the magnetic fields of 1st, 2nd electrodes 3, 4. This sheet plasma 6 is guided into a treating chamber 10 having a discharge port 11 by an electromagnet 5 and is further introduced by a permanent magnet 9 to the steel sheet 8 so that the steel sheet is irradiated with the sheet plasma. The sheet plasma 6 is adjusted to a narrow width of 0.01 to 0.1mm and the steel sheet 8 is irradiated with this sheet plasma across the transverse direction thereof in the direction orthogonal with the rolling direction. A shutter 7 is opened and closed in this irradiation state in synchronization with the movement of the steel sheet 8, by which the steel sheet is irradiated with the plasma at prescribed intervals. Local microstrain regions are uniformly introduced onto the surface of the steel sheet 8 in this way, by which the stable formation of the finer magnetic domains is surely executed and the low-iron loss unidirectional silicon steel sheet having the uniform quality is obtd.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a unidirectional silicon steel plate with low core loss, and involves subdividing magnetic domains by introducing minute strain regions on the surface of the steel plate. , which aims to reduce iron loss.

(Prior technology) Unidirectional silicon steel sheets have secondary recrystallized grains of the product highly concentrated in the Goss orientation, and a forsterite film is formed on the surface of the steel sheet, which has a small coefficient of thermal expansion. It is coated with an insulating film and is complex and requires strict control.
It is manufactured through a wide variety of processes.

Such unidirectional silicon steel sheets are mainly used as iron cores for transformers and other electrical equipment, and their magnetic properties include high magnetic flux density 1 (s, represented by the value) and iron loss (W+7). /S (represented by the value) and an insulating film with good surface properties.

Particularly in the wake of the energy crisis, the demand for reduced power loss has increased significantly, and the need for unidirectional silicon steel sheets with lower iron loss as transformer core materials has become increasingly important. .

Now, the history of iron loss improvement of unidirectional silicon steel sheets is based on Goss direction 2.
It is no exaggeration to say that this is a history of improvements in the secondary recrystallization texture. As a method for controlling such secondary recrystallized grains, a method has been implemented in which primary recrystallized grain growth inhibitors such as AIN, MnS, and MnSe are used to preferentially grow Goss-oriented secondary recrystallized grains. ing.

On the other hand, a completely different method is used to control the secondary recrystallization texture, namely laser irradiation on the steel plate surface (Tsuchiyama
Correct: Tetsu to Hagane, 69 (1983), P, 895, Special Publication No. 57-2252, No. 57-53419, No. 5B-2
4605, 58-24606) or plasma flame irradiation (JP-A-62-96617, JP-A-62-1)
No. 51511, No. 62-151516 and No. 62-
No. 151,517 (see the above-mentioned publication) proposed an innovative method for subdividing magnetic domains by introducing local microstrain, thereby reducing iron loss.

However, these methods introduce micro-strain by simultaneously irradiating multiple spot laser beams or plasma flames onto the surface of the steel sheet, making it difficult to make the irradiation conditions uniform, making it difficult to maintain the magnetic properties of the product at a constant level. It wasn't easy to maintain.

(Problems to be Solved by the Invention) The purpose of the present invention is to propose a method for manufacturing a low core loss unidirectional silicon steel sheet that can achieve stable magnetic domain refinement by uniformly introducing local microstrain. do.

(Means for Solving the Problems) This invention provides a unidirectional silicon steel plate that has undergone finish annealing.
A narrow sheet plasma generated by a hollow cathode gun and extending across the width of the steel plate is irradiated onto the surface in a direction perpendicular to the rolling direction to introduce a micro-strain region on the steel plate surface. This is a method for manufacturing a low core loss unidirectional silicon steel sheet.

Further, in this invention, the width of the sheet plasma is 0.0
Advantageously, it is between 1 and 0.1 mm.

This invention is characterized by irradiating a narrow sheet plasma that extends across the width of the steel plate in a direction perpendicular to the rolling direction. It is advantageous to use an apparatus, which is described below.

In the figure, l is the HCD gun, 2 is the hollow cathode, 3 is the first electrode, and 4
5 is a second electrode, 5 is an electromagnet, 6 is a sheet plasma, 7 is a shutter, 8 is a steel plate, 9 is a permanent magnet, 10 is a processing tank, and 11 is an exhaust port. In this device, the sheet plasma 6 generated from the HCD gun 1 at low voltage and high current is generated into a sheet having a length at least equivalent to the width of the steel plate by controlling the magnetic fields of the first electrode 3 and the second electrode 4. The plasma flow is as follows. Next, this sheet plasma is guided into the processing tank 10 by the electromagnet 5 and further to the steel plate by the permanent magnet 9, and is irradiated onto the steel plate 8. In this irradiation state, the shutter 7 is opened and closed in synchronization with the movement of the steel plate 8, and a narrow sheet plasma extending across the width of the steel plate is irradiated at predetermined intervals.

(for production) Next, this invention will be described in detail based on experimental examples.

C: 0.044 wt% (hereinafter simply referred to as %), S
i: 3.36%, Mn: 0.072%, S
e: 0.021%, Sb: 0.025%.

Mo: 13 silicon steel slabs containing 0.013%
After heating at 80°C for 4 hours, hot rolling was performed to obtain a 2.2 mm thick hot rolled plate, which was then cold rolled twice with intermediate annealing for 120 minutes at 1000°C to obtain a 0.20 mm thick sheet. The final cold-rolled sheet was obtained.

Then, after decarburizing primary recrystallization annealing in wet hydrogen at 820°C, ■ an annealing separator mainly composed of MgO or ■ MgO (35%), ^]zO, (60%) was applied to the surface of the steel sheet. , T
An annealing separator mainly composed of i0z (2%) and ZrOg (3%) was applied as a slurry. Thereafter, each was subjected to secondary recrystallization annealing at 850°C for 50 hours to preferentially grow Goss-oriented secondary recrystallized grains, followed by purification annealing for 5 hours in saturated hydrogen at 1200''C.

Next, the steel plate that underwent the treatment in (■) was coated with an insulating film containing phosphate and colloidal silica as main components on its surface.
On the other hand, after the oxides on the surface of the steel plate treated in A) were removed by electrolytic polishing, a TiN film with a thickness of 1 μm was formed on the steel plate by ion blasting to prepare sample (B).

Thereafter, samples (A) and (B) were coated using the apparatus shown in FIG.
1. Sheet plasma with a length of 500 mm (width of the steel plate is 300 mm) was irradiated at intervals of 10 mm in the rolling direction to introduce microstrain regions. The results of measuring the magnetic properties of the steel plate after strain introduction are shown in Table 1 in comparison with the magnetic properties before sheet plasma irradiation.

Table 1 As is clear from the same table, the iron loss of all steel plates introduced with the micro-strain region is 0.07 to 0.08 W/k compared to before introduction.
g and increased significantly. This significant improvement in iron loss is due to
This is because the subdivision of magnetic domains was advantageously achieved by introducing linear microstrain across the width of the steel sheet, and the effect was that even if the film beneath the insulating film was forsterite or TiN, iron loss could be reduced. It turns out that it is possible.

Next, FIG. 2 shows the preferred range of the width of the sheet plasma and the output of the HCD gun when the apparatus shown in FIG. 1 is used. Note that this figure summarizes the results of measuring the iron loss when varying the width of the sheet plasma and the output of the HCD gun in the above-mentioned experiment.

As is clear from the figure, the width of the sheet plasma is set to 0.
01-1.0 mm, HCD gun output 50-30
It is advantageous to have a large capacity of 0 kW. That is, if the width of the sheet plasma is less than 0.01 mm, the minute strain is too small to differentiate the magnetic domains, while if it exceeds 1.0 mm, the area to which thermal strain is applied becomes large and the effect of magnetic domain refining is lost. Further, unless the output of the HCD gun is set to a large capacity of 50 to 300, minute distortion cannot be introduced. Furthermore, it is desirable to introduce minute strains at intervals of 5 to 20 mm in the rolling direction. This is because the magnetic domains of a silicon steel plate can be subdivided by newly creating artificial grain boundaries at intervals of 5 to 20 m111, and therefore iron loss can be effectively reduced.

In addition to the above-mentioned forsterite and TiN, the coating under the insulating coating on the steel plate includes Ti, Zr, and Hf.

V, Nb, Ta, Cr, MO, Ni, Si
, B and AI nitrides, carbides and nitrides are also advantageously applicable to the present invention.

(Example) (A) C: 0.066%, Si: 3.39%,
Mn: 0.069%, ^1: 0.026%, Se:
0.028%, Cu: 0.1%, Mo: 0.025% or (B) C: 0.042%, Si: 3.41%
, Mn: 0.066%, Se: 0.021%,
Sb: 0.026%, M.

: A silicon hot-rolled plate containing 0.013%, respectively, was cold-rolled twice with intermediate annealing in between to give a thickness of 0.0 and 20 mm.
The final cold-rolled steel sheet is then decarburized and primary recrystallized annealed in wet hydrogen at 830'C.
Annealing separator mainly composed of MgO (28%), A
An annealing separator mainly composed of 12O2 (70%) and Ti0z (2%) was applied as a slurry.

After that, the steel plate that becomes the component (A) is heated to 105°C from 850°C.
After heating at 10°C/h to 0°C to preferentially grow Goss-oriented secondary recrystallized grains, purification annealing was performed for 8 hours in soft hydrogen at 1200°C, resulting in one component (8). Steel plate is 85
Secondary recrystallization annealing was performed at 0°C for 50 hours to obtain Goss orientation 2.
After preferential growth of the next recrystallized grains, purification annealing was performed for 5 hours in soft hydrogen at 1180'C.

Next, the steel plate that has undergone the treatment in (■) is coated with an insulating film that is mainly composed of phosphate and colloidal silica on the Forstera I) film, while the steel plate that has undergone the treatment in (■) is coated with an insulating film that is mainly composed of phosphate and colloidal silica. After removal, the surface roughness is 0.1 μm by electrolytic polishing.
Finished to Ra, then C by ion blating
An rN film was formed to a thickness of 1.0 μm, and then a similar film was formed on top of it. ! A coating was applied.

Thereafter, using the apparatus shown in FIG. 1 described above, sheet plasma with a width of 0.3 mm and a length of 500 mm (the steel plate width is 300 mm) extending in a direction perpendicular to the rolling direction is irradiated at intervals of 10 mm+ in the rolling direction. A micro-strain region was introduced.

Table 2 shows the results of measuring the magnetic properties of the steel sheet after introducing strain. As is clear from Table 2, (8).

Both materials in (B) were treated by sheet plasma irradiation.
Iron loss WI? It is noteworthy that 150 has significantly improved to 0.05-0.09W/kg.

table

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the apparatus used in the present invention, and FIG. 2 is a graph showing the width of the sheet plasma and the preferred range of the output of the HCD gun. 1...HCD gun 2 Hollow cathode 3-first electrode 4-second electrode 5...electromagnet 6-sheet plasma 7
-.Shutter 8-Steel plate 9--Permanent magnet 10-.Processing tank 11-.
Exhaust port*Fol: Forsterite coating CrN: CrN coating (Effects of the invention) According to this invention, it is possible to reliably subdivide the magnetic domains by uniformly introducing minute strain in a direction perpendicular to the rolling direction. ,
A silicon steel plate without variations in magnetic properties can be stably manufactured. Patent applicant Kawasaki Steel Corporation stock 4'! 4 negative candy seedlings 0θ05W/Nishie bending upward curve Δ0.03W/KIMJJLh X#I topless sheet plus small item (mm)

Claims (1)

[Claims] 1. A unidirectional silicon steel plate that has undergone finish annealing is rolled with a narrow sheet plasma generated by a hollow cathode gun that spans the width direction of the steel plate on its surface. A method for producing a low core loss unidirectional silicon steel sheet, characterized by irradiating the steel sheet in a direction perpendicular to the direction and introducing a micro-strain region on the surface of the steel sheet. 2. The method according to claim 1, wherein the width of the sheet plasma is 0.01 to 0.1 mm.