JPS6396218A - Production of extremely low iron loss grain oriented silicon steel sheet - Google Patents

Abstract

PURPOSE:To produce a grain oriented silicon steel sheet which is extremely decreased in iron loss, by removing the surface oxide of a grain oriented silicon steel sheet subjected to finish annealing, then subjecting the steel sheet to mirror finishing, forming a film by ion plating and subjecting the sheet to EB projection. CONSTITUTION:After the oxide film on the surface of the grain oriented silicon steel sheet subjected to the finish annealing is removed by a strong acid such as sulfuric acid, the surface of the steel sheet is mirror-finished by a known polishing method to <=0.4mu center line average height Ra. The film of about 0.05-5mu thickness consisting of at least one kind among the nitride and/or carbide of Ti, Zr, Hf, V, Nb, Ta, Cr, Mn, Mo, W, Co, Ni, Al, B, Si and the oxide of Al, Ni, Cu, W, Si, Zn is formed by ion plating thereon. The film is further subjected to the EB project at about 3-15mm intervals in the direction crossing the rolling direction (more preferably the direction of about 60-90 deg.). The iron loss is thereby decreased to the level more than enough to offset the increased cost by the mirror finishing.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a unidirectional silicon mouth plate.
In particular, ultra-low iron loss can be achieved by performing ion plating treatment of nitrides, carbides, oxides, etc. on the mirror-finished steel sheet surface after final annealing, and then subsequently applying EB irradiation in a direction transverse to the rolling direction. That is.

Remarkable development efforts in recent years to improve the electrical and magnetic properties of unidirectional silicon steel sheets, and in particular to meet the extreme requirements of reducing iron loss, are gradually bearing fruit.

As is well known, unidirectional silicon steel sheets are products in which secondary recrystallized grains are highly concentrated in the (110) <001>, or Goss, orientation, and are mainly used in transformers and other electrical equipment. When used as an iron core, the product is required to have a high magnetic flux density (represented by the value B) and a low value (represented by the iron mcH+tIso value) as electromagnetic properties.

This unidirectional silicon steel plate is manufactured through a wide variety of complicated processes, but numerous inventions and improvements have been made so far, and today the magnetic properties of a product with a plate r￥0.30 mm have improved to BI.
G value 1.90T or more, WI? The magnetic properties of products with a straight line of 1.0 g or less or a plate thickness of 0.23 mm are B17.
1 value 1.89T or more, 1. /,. Unidirectional silicon steel sheets with ultra-low core loss of 0.90 core loss/kg or less are being manufactured.

Particularly in recent years, demand for reducing power loss has become much stronger from an energy-saving perspective, and in Europe and the United States, when creating a transformer with low loss, the reduction in iron loss is converted into a monetary value and added to the transformer price.・The "evaluation" (iron loss evaluation) system is becoming widespread.

(Prior art) Under these circumstances, recently, the surface of a unidirectional silicon steel plate after finish annealing is irradiated with a laser in a direction approximately perpendicular to the rolling direction to introduce local microstrain to subdivide the magnetic domains. It has been proposed to reduce iron loss (see Japanese Patent Publication No. 57-2252, Japanese Patent Publication No. 57-53419, Japanese Patent Publication No. 58-26405 and Japanese Patent Publication No. 58-26406).

This magnetic domain refining technology is effective for transformer materials for laminated core transformers that are not subjected to strain relief annealing, but for material for wound core transformers that are subjected to strain relief annealing,
There is a drawback that the local minute strain introduced by laser irradiation is released by annealing and the magnetic domain width becomes wider, so that the laser irradiation effect disappears.

On the other hand, earlier in Japanese Patent Publication No. 52-24499, the surface of a unidirectional silicon steel sheet after finish annealing was polished to a mirror finish, or the mirror finish surface was coated with metal plating or an insulating film was applied thereon. A method for manufacturing ultra-low core loss unidirectional silicon steel sheets by baking has been proposed.

However, this method of improving iron loss through mirror finishing cannot be adopted from a process perspective because it does not contribute enough to reducing iron loss, although it increases the cost significantly. Due to problems with adhesion, it has not been adopted in current manufacturing processes. Japanese Patent Publication No. 56-4150 also proposes a method in which a steel plate surface is mirror-finished and then an oxide-based ceramic thin film is vapor-deposited. However, this method cannot be used in actual manufacturing processes because the steel sheet and the ceramic layer will separate when subjected to high-temperature annealing at 600° C. or higher.

(Problems to be Solved by the Invention) It is an object of the present invention to compensate for the disadvantage of increased cost due to mirror finishing and achieve a significant reduction in iron loss.

(Means for Solving the Problems) This invention removes oxides on the surface of a grain-oriented silicon steel plate and then polishes it to a centerline average roughness of 0.4.
After finishing to a mirror surface of μm or less, Ti, Zr, Hf, V, and Nb are coated by ion plating.

Ta, Crt Mo+ 'A+ Mn+ Co, N
t, Al, BI Si nitride and/or carbide and A1. After forming an ultra-thin tensile film made of at least one selected from oxides of Nt, Cu, A, Si and Zn and firmly adhered to the finished surface through a mixed phase of these with the base iron, A method for producing an ultra-low iron loss unidirectional silicon steel sheet (first invention) including a step of applying EB irradiation in a direction transverse to the rolling direction of the steel sheet, and further comprising forming an insulating coating on the EB irradiation surface. A method for manufacturing an ultra-low core loss unidirectional silicon steel sheet (second invention) including the steps.

The explanation will proceed according to specific experiments that led to the success of these inventions.

C: 0.048% (hereinafter simply expressed as %), Si
: 3.48%, Mn: 0.062%, Se: 0.
022%, Sb: 0.026% and Mo: O'
Continuously cast silicon steel slabs containing 0.020% were heated to 1350℃.
After heating for 4 hours, the sheet was hot-rolled to obtain a hot-rolled sheet with a width of 2.0 mm.

After that, after equalization annealing at 900℃ for 3 minutes, at 950℃ for 3 minutes.
Cold rolled twice with intermediate annealing for 0.2 min.
A final cold-rolled sheet with a thickness of 3 mm was obtained.

After that, after decarburization and next crystal annealing in a wet hydrogen atmosphere at 820℃, inert AIZO3 (75%) is applied to the steel plate surface.
and MgO (25%), followed by secondary recrystallization annealing at 850°C for 50 hours and 1200°
Purification annealing was performed at C for 5 hours in saturated hydrogen.

The final annealed grain-oriented silicon steel sheet coil thus obtained was divided into four sections, and each section was then lightly pickled (10
% HCJ solution) and then chemically polished in a 3% IIP and H2Ot solution to give a mirror-like finish with an average surface roughness of 0.03 μm.

Thereafter, the four groups of samples divided as described above were each treated under the following conditions.

(a) A thin film of TiN with a thickness of 1.0 μm was formed on a mirror-finished steel plate using a continuous ion plating device (HCD method).

fb) After forming a 1.0 μm thick TiN film on a mirror steel plate using a continuous ion plating device,
Continuously, electron beam irradiation is performed in a vacuum in a direction perpendicular to the rolling direction to a width of 10 mm (EB irradiation is performed at an accelerating voltage of near 0K).
V, accelerating current: 0.5 A, beam diameter 0.1 x, beam scanning interval: 10 x scanning).

fc) After forming a 1.0 μm thick TiN film on a mirror steel plate using a continuous ion plating device, it was then irradiated with an electron beam in a 10 mm width in a direction perpendicular to the rolling direction in a vacuum, and then heated at 500°C for 1 minute. - Processed with low temperature baking insulation coating.

(dl) Used as mirror polished (comparison material).

The magnetic property values of each sample are summarized in Table 1.

Table 1 As is clear from Table 1, the magnetic properties under each condition (b) and (C) according to the present invention have a B10 value of 1.92T.

WIT/S. It is noteworthy that the value is 0.63 to 0.60 W/kg, which indicates ultra-low iron loss.

In this way, the unidirectional silicon steel plate is mirror-finished, and then T
After the IN ultra-thin tension coating treatment, by further introducing micro-strain by EB irradiation, a product with extremely low iron loss can be obtained.

In particular, this EB irradiation can be performed in the same vacuum after coating with an ultra-thin TiN film, which has the advantage of producing ultra-low core loss unidirectional silicon steel sheets by utilizing two innovative functions in one continuous line. There is.

(Function) As shown above, an ultra-thin tension film is formed on the surface of the mirror-finished steel plate, utilizing the strong elastic tension caused by the difference in thermal expansion with the base steel, and the surface of the steel plate is then subjected to EB treatment. Ultra-low iron loss can be achieved by introducing local minute plastic strain.

The above experimental results are based on a tension coating made of TiN, but the tension coating can also be made of other materials such as Ti, Zr, and V.

Nb+ Ta+ Cr, Mo, Co, Ni, Mn, AI
, B, Si, W, Hf nitrides and/or carbides, and AI, Ni, Cu, W, Si and Zn oxides.
Almost the same effects as those described for iN are obtained, and both are suitable for the purpose of the present invention.

Next, the manufacturing process of a unidirectional silicon steel plate according to the present invention will be explained.

The starting material is a conventionally known unidirectional silicon steel material, such as ■ C: 0.01 to 0.050%, St: 2.5
0-4.5%, Mn: 0.01-0.2%, Mo:
0.003-0.1%, Sb: 0.005-0.
2%, one or two types of S or Se, 0.
Composition containing 005-0.05%■ C: 0.01
~0.08%, Si: 2.0-4.0%, S: 0.
005-0.05%, Al: 0.005-0.06
%, N: o, ooi~0.01%, Sn: 0.0
1-0.5%, Cu: 0.01-0.3%.

Composition containing Mn: 0.01 to 0.2% ■C:
0.011-0.06%, Si: 2.0-4.0%
, S: 0.005~0.05%, B: 0.0003~
0.0040%, N: 0. OO1~0.01%,
It is applicable to compositions containing Mn: 0.01 to 0.2%.

Next, the hot-rolled sheet undergoes uniform annealing at 800 to 1100°C.
One-time cold rolling method, in which the final plate thickness is obtained by two cold rolling steps, or two-concave cold rolling method, in which intermediate annealing is usually performed at 850°C to 1050°C, and then further cold rolling is performed.In the latter case, the first rolling rate is 50
% to about 80%, the final rolling reduction is about 50% to 85%, and the final cold rolled plate thickness is from 0.15 mm to 0.35 mm.

After finishing the final cold rolling, the steel plate finished to the product thickness is subjected to decarburization and primary recrystallization annealing treatment in wet hydrogen at 750°C to 850°C after surface degreasing.

After that, an annealing separation material containing MgO as a main component is usually applied to the surface of the copper plate.

At this time, it is effective not to form forsterite, which is generally required to be formed after finish annealing, in order to simplify the subsequent mirror polishing treatment of the steel plate.
As the annealing separator, it is preferable to use an annealing separator in which 50% or more of Al2O2, ZrO□, Ti0z, etc. is mixed into MgO.

After that, secondary recrystallization annealing is performed, but this step is (110)
This is carried out to sufficiently develop secondary recrystallized grains with the <001> orientation, and is usually performed immediately after box annealing.
This is done by raising the temperature to 00°C or higher and maintaining it at that temperature.

In this case, in order to develop a highly uniform secondary recrystallized grain structure in the (110) <001> orientation, the
It is more advantageous to carry out retention annealing at a low temperature of 00°C, and in addition, for example, 0.5-b annealing may be used.

Purification annealing after secondary recrystallization annealing requires annealing in saturated hydrogen at 1100° C. or higher for 1 to 20 hours to achieve purification of the steel sheet.

After this purification annealing, the oxide film on the surface of the steel sheet is pickled with a strong acid such as sulfuric acid, nitric acid or hydrofluoric acid, or mechanically ground.
Remove by cutting etc.

Next, the surface of the steel plate is polished to a mirror-like state, that is, with a centerline average roughness R, using conventionally known methods such as chemical polishing and/or electrolytic polishing.
A is finished to 0.4 μm or less.

After that, Ti, Zr, V,
Nb.

Ta, Cr+ Mo+ W+ Mn+ Co, Ni
, AI, B, Si nitride and/or carbide, 81. A seed coat of about 0.05 to 5 .mu.m consisting of at least one selected from oxides of Ni, Cu, Si, and Zn is formed.

Thereafter, EB irradiation is applied to this ultra-thin film in a direction transverse to the rolling direction, preferably in a direction of 60 to 90 degrees, at intervals of about 3 to 15 mm. The EB irradiation conditions at this time are 10 to 300 KV.
acceleration voltage, current of 0.005 to IOA, beam diameter of 0
．． It is effective to apply dots or lines using 005 to 51.

Furthermore, although the EB irradiation after ion plating of the present invention can be performed in separate lines, it is effective to perform it in vacuum on the same line.

In this way, it is necessary to ensure insulation properties after EB irradiation, but in order to take advantage of the ER irradiation effect, this insulation coating treatment requires a short baking process of 1 second to 30 minutes at a low temperature of 600°C or less. This is effective.

The silicon steel plate treated as described above can be subjected to flattening heat treatment.

(Example) 1-1C: 0.045%, Si: 3.40%, Mn:
0.066% 9th station: 0.020%, Se: 0.0
20%, Sb: 0.025%,
After uniform annealing at 900° C. for 3 minutes, cold rolling was performed twice with intermediate annealing at 950° C. to obtain a final cold rolled sheet with a thickness of 0.23 mm.

Then, after decarburization annealing in wet hydrogen at 820℃, Al
After applying an annealing separator mainly composed of 2O2 (75%) and Go (25%), secondary recrystallization annealing was performed at 850°C for 50 hours, and purification annealing was performed in dry hydrogen at 1200°C for 8 hours. went.

After that, after removing the oxide film by pickling, 3% IIF and H,
O□ Chemically polished in liquid to a mirror finish.

Thereafter, a Si3N4 film (about 1.5 μm thick) was formed using a continuous ion plating (IIcD method) device.

Thereafter, EB irradiation was performed on this film in the form of dots at 81 intervals in a direction substantially perpendicular to the rolling direction. (EB irradiation conditions are acceleration voltage: 35KV, current: 0.5A, spot diameter is Q.
, 1 mm, spot spacing l, 5++n. The magnetic properties of this product are Boo = 1.92T, 匈, 7
7. - It was 0.62W/kg.

1 application 1 C: 0.052%, Si: 3.46%, Mn:
0.077%, AI=0.024%, S: 0.0
020%, Cu: 0.1%, Sn: 0.06%
The hot-rolled sheet containing the following was uniformly annealed at 1130°C for 3 minutes and then rapidly cooled, and then warm-rolled at 300°C to obtain a final cold-rolled sheet with a thickness of 0.20 mm.

After decarburization annealing in wet hydrogen at 850°C, 81 Z is formed on the surface.
O:l (80%), Mg0 (15%) and Zr0z (5
After applying an annealing separator mainly composed of Ta.

After that, after removing the oxide film by pickling, add 3% HF and 820
□ After chemically polishing in liquid to give a mirror finish, ion plating (HCD method) is applied to (1) BN, (21Ti
(CN).

(31SiJi, f41VN, (51ZrN,
Nitride such as (61CrzN, (7)AIN, (81HfN), (91ZrC, αIHfC, QυSiC, Q
3TaC.

carbides such as α31ZrC0α41MnC and QS)
ZnO, Q61NiO.

αη5iOz, Q8) WO, Q9) Al5O12 (20
) Thin film of CuO(7) oxide (0.5-1.9 μm thick)
formed. Thereafter, EB irradiation was performed in a linear manner with a width of 101 mm perpendicular to the rolling direction. (EB irradiation conditions: acceleration voltage 60KV, current 0.3A.

(Beam diameter: 0.05n+) After that, a 550°C low-temperature insulation coating was applied. The magnetic properties of this product are shown in Table 2.

Table 2 C: 0.043%, St: 3.36%, Mn:
0.067%, Se: 0.021%, Sb: 0
．． A hot rolled sheet containing 0.025% and Mo: 0.18% was homogenized at 1000°C for 1 minute and then heated at 950°C for 3 minutes.
Cold rolling is carried out twice with an intermediate annealing of 1 minute in between.
．． A final cold-rolled sheet with a thickness of 18 mm was obtained. After that, after performing primary recrystallization annealing that also serves as decarburization in wet hydrogen at 820°C, an annealing separator whose main components are Ah (h (70%)) and MgO (30%) is applied to the steel plate surface. After performing secondary recrystallization at 850°C for 50 hours, purification annealing was performed at 1200°C for 10 hours in dry hydrogen.

After that, after removing the oxide film by pickling, 3% IIF and H,
O□ After chemically polishing in liquid to give a mirror finish, ion plating (IIcD method) was performed to prepare (1) TiN, (2)
1NbN.

(31MozN, (41W2N, (51CoN, (5
) NiN, (7) TiC, (81NbCj9)MOzC
.

αωWC, αυCoC, Q3NiC, Q31VC+α4
) CrC, Q5) AIC tension thin film (target 1.0μ thickness)
formed. Thereafter, the strip was irradiated with EB irradiation in a direction perpendicular to the rolling direction with a width of 811 mm. (EB irradiation conditions: acceleration voltage 80KV, current 0.5A.

(Beam diameter: 0.05 yen) After that, a low temperature insulation coating was applied at 550°C.

The magnetic properties of this product are shown in Table 3.

Table 3 (Effects of the Invention) According to the first invention, it is possible to achieve a significant reduction in iron loss by compensating for the disadvantage of increased cost due to mirror finishing of the surface of a grain-oriented silicon steel sheet that has been finish annealed. . Further, according to the second invention, in addition to the above-described low iron loss, effective enhancement of insulation properties is realized.

Claims (1)

[Claims] 1. After removing surface oxides from a unidirectional silicon steel plate that has undergone finish annealing, the steel plate surface is polished to a mirror surface with a center line average roughness Ra of 0.4 μm or less, and then ionized. By plating, Ti, Zr, Hf, V, Nb
, Ta, Cr, Mn, Mo, W, Co, Ni, Al, B
, Si nitride and/or carbide, and Al, Ni, C
An ultra-low iron loss characterized in that after forming a coating made of at least one kind selected from oxides of u, W, Si and Zn, EB irradiation is applied on the surface in a direction transverse to the rolling direction. A method for manufacturing unidirectional silicon steel sheet. 2. After removing surface oxides from the unidirectional silicon steel plate that has undergone final annealing, the steel plate surface is polished to a mirror finish with a centerline average roughness Ra of 0.4 μm or less, and then Ti, Zr, Hf, V, Nb
, Ta, Cr, Mn, Mo, W, Co, Ni, Al, B
, Si nitride and/or carbide, and Al, Ni, C
After forming a film made of at least one selected from oxides of u, W, Si, and Zn, EB irradiation is performed on the surface in a direction transverse to the rolling direction, and then a low-temperature tension insulation film is formed. A method for producing an ultra-low core loss unidirectional silicon steel sheet.