JPH0445274A - Production of extra thin grain-oriented silicon steel sheet minimal in iron loss - Google Patents

Abstract

PURPOSE:To easily produce an extra thin grain-oriented silicon steel sheet minimal in iron loss by forming a tension-giving film of Si nitride, etc., on the surface of a rerolled steel sheet at the time of removing nonmetallic matter from the surface of a grain-oriented silicon steel sheet and applying rerolling and annealing to the above steel sheet under respectively specified conditions. CONSTITUTION:Nonmetallic matter is removed from the surface of a finish- annealed grain-oriented silicon steel sheet, and this steel sheet is rerolled at 5-80% reduction of area to 0.01-0.15mm sheet thickness and then annealed at 700-1,100 deg.C. At this time, before or after the annealing after rerolling, a tension- giving film of one or more kinds among the nitrides, carbides, and carbonitrides of Si, Mn, Cr, Ni, Mo, W, V, Ti, Nb, Ta, B, Cu, Zr, Hf, and Al is formed on the steel sheet surface to about 0.005-5mu film thickness. By this method, the extra thin grain-oriented silicon steel sheet minimal in iron loss can be obtained stable and advantageously.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a grain-oriented silicon steel sheet with an extremely thin product thickness and having an ultra-low core loss comparable to that of amorphous steel. The ultra-low iron loss unidirectional ultra-thin silicon steel sheet produced by this method is advantageously used as a core material for transformers and the like.

Unidirectional silicon steel sheets are manufactured by having the product's secondary recrystallized grains highly concentrated in the Goss orientation, and by forming a forsterite film on the surface of the steel sheet, and then coating it with an insulator with a small coefficient of thermal expansion. Magnetic properties are improved by applying a coating to the steel plate and applying tension to it, and it is manufactured through a complex and diverse process that requires strict control.

Unidirectional silicon steel sheets of this type are mainly used as iron cores in transformers and other electrical equipment, and their magnetic properties include high magnetic flux density and low core loss, as well as an insulating coating with good surface quality. It is required that the applicant has completed the following. In the wake of the energy crisis, demand for features that reduce power loss has become significantly stronger, and the need for unidirectional silicon steel sheets with lower iron loss as core materials for transformers is increasing.

The history of improving iron loss in unidirectional silicon steel sheets is as follows.
It is no exaggeration to say that this is a history of improvement in the Goss-oriented secondary recrystallization texture.

(Conventional technology) AlN as a method for controlling secondary recrystallized grains.

A method of preferentially growing secondary recrystallized grains in the Goss orientation using a primary recrystallized grain growth inhibitor, such as MnS and MnSe, has been implemented.

On the other hand, various iron loss improvement techniques different from the metallurgical means of controlling the secondary recrystallization texture described above have also been developed. Namely, Tadashi Uchiuchi: Tetsu to Hagane, 69 (1983).

P, 895, Special Publication No. 57-2252, Special Publication No. 57
7-53419, Japanese Patent Publication No. 58-26405, and Japanese Patent Publication No. 58-26406, etc., and Japanese Patent Application Laid-Open No. 62-96617, Japanese Patent Application Laid-open No. 62-1982.
No. 51511, Japanese Patent Application Laid-open No. 151516/1983,
and Japanese Unexamined Patent Publication No. 62-151517 propose an innovative method of irradiating the surface of a steel plate with plasma to introduce local minute strain into the steel plate, subdividing the magnetic domains, and reducing iron loss. Disclosed. However, the steel sheets obtained by these methods lose their microstrains when heated to a high temperature range, so when used as materials for wound core transformers that undergo high-temperature strain relief annealing, they have the disadvantage that the above effects cannot be achieved. Ta.

On the other hand, a method has also been proposed in which the iron loss does not deteriorate even if such high-temperature strain relief annealing is performed.

Namely, Japanese Patent Publication No. 50-35679, Japanese Unexamined Patent Application Publication No. 1983
JP-A-28525 and JP-A-59-197520 disclose a method of forming grooves or serrations on the surface of a finish annealed plate, and JP-A-56-130454 describes a method of forming grooves or serrations on the surface of a finish annealing plate. Method for forming recrystallized grain regions, JP-A-60-92479, JP-A-60-9
No. 2480, JP-A No. 60-92481, and JP-A No. 60-258479, etc., disclose a method of forming a different thickness or a defective region in a forsterite film.
Jikai@60-103124 publication, and Japanese Patent Publication No. 60-1
Publication No. 03182 and the like disclose a method of forming a different composition region in a steel base, in a forsterite coating, or in a tension-applying insulating coating.

However, these methods have not been industrially adopted because the process is complicated, but the effect of reducing iron loss is small, and the manufacturing cost is high.

Apart from these, as disclosed in Japanese Patent Publication No. 55-19976, Japanese Patent Application Laid-Open No. 56-127749, and Japanese Patent Application Laid-open No. 2-3213, amorphous alloys are used in ordinary power transformers, high frequency transformers, etc. It is attracting attention as an iron core material. Although such amorphous materials have very superior core loss properties compared to ordinary unidirectional silicon steel sheets, they lack thermal stability, have a poor space factor, are not easy to cut, etc. It has many practical disadvantages and is not used in large quantities.

Also, very recently, it has been reported that iron loss comparable to that of amorphous materials for iron cores can be obtained by rolling commercially available grain-oriented silicon steel sheets even thinner and heat-treating them in a high vacuum to generate tertiary recrystallization. The technology is shown in Ishiyama, Arai: Japanese Institute of Metals Spring Conference Presentation Summary (April 1990), p. 290.

However, this method cannot be applied to actual manufacturing processes because it requires heat treatment at a high temperature of over 1100° C. for a long time.

(Problems to be Solved by the Invention) The present invention eliminates the above-mentioned problems and uses a unidirectional ultra-thin silicon steel sheet having an ultra-low core loss comparable to that of amorphous steel.
The present invention proposes an advantageous and stable manufacturing method.

(Means for solving the problem) First, the gist of the specified invention is to remove non-metallic substances on the surface of the steel plate using a finish-annealed unidirectional silicon steel plate, and to remove non-metallic substances from the surface of the steel plate. Re-rolling the steel plate at a reduction rate of 5% to 80% to obtain a thickness in the range of 0.01 to 0.15 mm, and re-rolling the steel plate at a temperature of 700°C to 1100°C. During the production of ultra-thin unidirectional silicon steel sheets through the steps of annealing at a temperature within
+Mo+W, V, Tt, Nb, Ta,
B, nitride of Cu, Zr, If, and Alfi;
A method for producing a unidirectional ultra-thin silicon steel sheet with ultra-ultra-low iron loss, characterized by forming a tension imparting coating of one or more types selected from carbides and carbonitrides.

In this invention, the tension imparting coating can be formed either before or after the annealing after re-rolling.

Next, the second invention is an extremely low core loss unidirectional pole, characterized in that, in the specified invention, an insulating film is formed on the steel plate on which the tension imparting film is formed after the annealing. This is a method for manufacturing thin silicon steel sheets.

Next, the third aspect of another invention is the ultra-low iron loss unidirectional ultra-thin, characterized in that, in the specified invention, the steel plate coated with the tension imparting coating after the annealing is subjected to a magnetic domain refining treatment. This is a method for manufacturing silicon steel sheets.

A fourth aspect of yet another invention is the ultra-ultra-low core loss unidirectional ultra-thin silicon plate according to the second aspect of the other invention, characterized in that the steel plate coated with the insulating film is subjected to magnetic domain refining treatment. This is a method for manufacturing raw steel sheets.

Here, non-metallic substances such as forsterite and oxide films on the surface of the unidirectional silicon steel sheet after purification annealing can be removed by known chemical removal methods, mechanical removal methods, etc. A combination of these may be used.

After this oxide removal treatment, it is desirable to finish the surface of the steel plate to a mirror finish by a conventionally known polishing method, if necessary. In this case, the center line average roughness is preferably 0.4 μ- or less.

CVD, ion blasting, ion implantation silane, etc. are selected for the coating of the tension imparting film after re-rolling, and the thickness of this film is from 0.005μ to 5, based on the tension imparting effect and space factor. It is preferable to set it as the range of .0 micrometer.

The magnetic domain refining treatment performed on a steel plate coated with a tension-applying coating or a steel plate coated with an insulating coating on the tension-applying coating may be performed by a method using a laser, plasma, etc., or a method using an electron beam.

Next, regarding the chemical composition of the grain-oriented silicon steel sheet to which the method of the present invention is applied, any conventionally known chemical composition is suitable, but typical compositions are as follows.

C: 0.01 wt% or more and 0.10 wt% or less.

In addition to uniform refinement of the structure during hot rolling and cold rolling,
An element useful for the development of Goss orientation, with at least 0.0
It is preferable to add 1 wt% or more.

However, if the content exceeds 0.10 wt%, the Goss orientation will be disturbed, so the upper limit is preferably 0.10 wt%.

Si: 2. Owt% or more and 4.5 wt% or less.

It increases the specific resistance of the steel plate and effectively contributes to reducing iron loss, but 2
．． If it is less than Owt%, not only will the specific resistance decrease,
During the final high-temperature annealing performed for secondary recrystallization and purification, randomization of crystal orientation occurs due to α-T transformation, and a sufficient iron loss improvement effect cannot be obtained. Ductility is impaired. Therefore, the lower limit is set to 2. Ow
t%, and the upper limit is preferably 4.5 wt%.

? In: 0.02wt% or more and 0.12wt% or less.

At least 0.02 wt% is required to prevent hot embrittlement, but too much content will deteriorate the magnetic properties, so the upper limit is preferably 0.12 wt%.

Inhibitors can be broadly classified into MnS+MnSe type and AlN type. In the case of MnS and MnSe,
S: 0.005 wt% or more, 0.06 wt% or less, and Se: 0.005 wt% or more, 0.06w
At least one species selected from t% or less.

Both S and Se are effective elements as inhibitors that control secondary recrystallization of grain-oriented silicon steel sheets. In both cases, from the viewpoint of securing suppressive power, at least 0.005 wt%.
However, if it exceeds 0.06 wt%, the effect will be impaired, so the lower limit is set at 0.005 wt%,
It is preferable that the upper limit is 0.06 wt%.

In the case of AlN-based, Al: 0.005 wt% or more, 0.10 wt% or less, and N: 0.004 wt% or more, 0.015
wt% or less.

Regarding the range of Al and N, the above-mentioned MnS system, Mn
For the same reason as in the Se-based case, it is preferable to fall within the above range.

As inhibitor components, the above-mentioned S, Se, If
! In addition to Cr, Mo, Cu, Sn, Ge,
It is also advantageously compatible with sb, Te, Bt, P, etc., and may also be included in small amounts. Here, the preferred addition range of the above components is Cr,
Cu, Sn: 0.01wt% or more, 0.15wt
% or less, Mo, Ge+ sb, Te, Bl: 0
．． 005 wt% or more, 0.1 wt% or less, P:
The amount is 0.01 wt% or more and 0.2 wt% or less, and each of these inhibitor components can be used either alone or in combination.

(Function) Finish annealed unidirectional silicon steel sheet as a material is
Generally, hot-rolled plates made of hot-rolled silicon steel slabs are
A single cold rolling method is applied after uniform annealing at a temperature of 0° C. to 1100° C., or a two-time cold rolling method is applied, in which intermediate annealing is usually performed at a temperature of 850° C. to 1050° C. and further cold rolling is performed. In the latter case, the first rolling is done at a reduction rate of 50% to 80%.
In the former case and the second rolling of the latter, the cold-rolled plate is usually 0.15mm to 0.35cm thick at a reduction rate of 50% to 85%, but if necessary, the cold rolled plate is 0.15mm thick. The following may be used.

Next, the cold-rolled steel sheet is subjected to surface degreasing and decarburization and primary recrystallization annealing in wet hydrogen at 750°C to 850°C.

After performing such treatment, an annealing separator is applied to the surface of the steel sheet.

At this time, in order to more easily remove the forsterite film, which is essential after finishing annealing for boat fishing, Aj! is added to MgO as an annealing separator. !
03+ Zr0z, Tio! It is preferable to mix 50% or more of the like, and this can also be useful for simplifying the mirror finishing of the surface of the steel plate.

In any case, this is done to sufficiently develop the secondary recrystallized grains after applying the annealing separator, and is usually performed by immediately raising the temperature to 1000°C or higher by box annealing and maintaining it at that temperature. It is done.

In addition, in order to develop a secondary recrystallized grain structure that is highly aligned in the coz orientation, holding annealing at a low temperature of 820°C to 900°C or other methods such as 0.5°C/h to 15°C
It may also be one that has been subjected to slow heat annealing at a temperature increase rate of °C/h.

The purification annealing after the secondary recrystallization sufficiently purifies the steel plate under the conditions of 1 to 20 hours at 1100° C. or higher in saturated hydrogen.

In the manner described above, a finish annealed unidirectional silicon steel plate is obtained.

Using the above-mentioned steel plate as a raw material, first, the non-metallic substance on the surface of the steel plate, that is, the oxide film (this includes the forsterite film, of course), is removed by a known chemical removal method such as pickling, cutting, or grinding. or a combination of these methods.

After this non-metallic substance removal treatment, the surface of the steel plate may be finished to a mirror finish as necessary, and this mirror finish can be achieved by chemical polishing, electrolytic polishing, mechanical polishing such as puffing, or a combination of these methods. You can do it at

Next, the steel plate from which the oxides have been removed is made from a rolling reduction of 5% to 80%.
% re-rolling to a thickness in the range of 0.01mm to 0.15mm.

The reason for limiting the rolling reduction rate in this case is that when the rolling reduction rate is less than 5%, the processing strain imparted to the steel plate is small.
Because the mobility of grain boundary movement (Mobfility) is small,
Coarsening of crystal grains is less likely to occur, and conversely, when the reduction rate is 80
%, the dislocation density becomes too high and it becomes difficult to coarsen the crystal grains.

In addition, the reason for limiting the plate thickness is that if the thickness exceeds 0.15 m, it will be too thick and the iron loss reduction effect due to plate thickness will not be sufficient.
, 0.01 m5+ or less, it is too thin and difficult to manufacture and handle, making it impractical.

After re-rolling, annealing is performed, and before or after this annealing, Si, ? In, Cr.

Ni, Mo, w, v, Til Nbl Ta
+ At least one tension-imparting coating of one or more selected from nitrides, carbides, or carbonitrides of BI Cu, Zrl Hfl, and Al is formed on the surface of the steel sheet.

If the thickness of this tensioning coating is less than o, oosp-, the tensioning effect is small, so the effect of reducing iron loss is small (
Also, if the film thickness exceeds 5μ, it is disadvantageous both in terms of space factor and economical efficiency, so from 0.005μ to 5μ
It is preferable to keep it within the range of μ error.

The conditions for annealing after re-rolling are 700°C or higher and 1100°C.
Recrystallization is carried out at a temperature within the range below .degree.

The reason for limiting this annealing temperature range is that at temperatures below 700°C, processing strain in the crystal cannot be released and recrystallization cannot occur.
Further, if the temperature is 1100° C. or higher, the plate thickness is thin, making it difficult to obtain a stable product with a good shape, and the cost efficiency is also poor.

In addition, in this annealing, it is preferable to set the time to 2 hours or more in order to sufficiently perform the recrystallization necessary to reduce iron loss, but a long time exceeding 20 hours is not necessary. .

In order to further enhance the insulation properties of the tensile coating on the ultra-low iron loss unidirectional ultra-thin silicon steel sheet obtained in this way and make it more suitable for applications such as transformer cores, an insulating coating was added on the tension coating. can be overlaid.

This insulating film is composed of a baked layer of colloidal silica or a coating film containing phosphate and colloidal silica as main components, and may be formed using a conventionally known method as is.

Furthermore, the steel plate coated with the tension imparting coating or the steel plate coated with the insulating coating on the tension imparting coating may be subjected to magnetic domain refining treatment for the purpose of further improving iron loss.

This magnetic domain refining process uses laser, plasma, or electron beams to irradiate in the direction intersecting the rolling direction from three points at scanning intervals of 20 mm. These methods can be performed by using conventionally known methods as they are. good.

In any of the above cases, strain relief annealing is performed after cutting and other processing, and a conventional method can be used for this annealing.

(Example) Example 1 Five types of silicon steel slabs containing the chemical components shown in Table 1 were subjected to hot rolling, intermediate annealing, cold rolling, decarburization, and primary recrystallization annealing using normal methods. After that, secondary recrystallization annealing is performed to reduce the temperature from 0.15 to 0.25-
It is made of a unidirectional silicon steel plate with an ugly thickness.

Using these silicon steel plates as raw materials, after removing the oxides on the steel plate surface with a belt sander and applying electrolytic polishing,
It was rolled at a rolling reduction of 10% to 70% to give a plate thickness of 0.08■■.

After rolling to a thickness of 0.08 mm, a TiN film was applied as a tensioning film before or after annealing at 1070°C (thickness: 0.08 mm).
The steel plate obtained from 2μ intestines to 0.3μ■) was further subjected to the following treatments.

An insulating film containing phosphate and chromic acid as main components is formed on the TiN film.

Magnetic domain refining treatment is performed on the TiN film using an electron beam.

Perform magnetic domain refining treatment using a laser on the insulating coating.

Iron loss of steel plate obtained by these treatments (Wls/s-)
are shown in Table 2.

table Note 80 marks indicate conformity items.

As is clear from Table 2, the iron loss of these steel plates is 0.1
It shows excellent values ranging from 1W/kg to 0.36W/kg.

Example 2 C: 0.073 wt%, St: 3.39
wt%Mn: 0.072 eyt%, Mo
: 0.013 wt%Se: 0.021 wt
%, Al: A silicon steel slab containing 0.026 wt% was heated at 1420° C. for 3 hours and then hot rolled to obtain a hot rolled sheet with a thickness of 2.2. Thereafter, cold rolling was performed twice with intermediate annealing at 1050° C. to obtain a cold rolled sheet with a thickness of 0.23 mm. After that, after performing primary recrystallization annealing that also serves as decarburization in wet hydrogen at 840°C, an annealing separator mainly composed of forsterite is applied to the surface of the steel plate, and the temperature is increased to 850°C.
A unidirectional silicon steel sheet obtained by raising the temperature from 10°C/h to 1150°C to develop Goss-oriented secondary recrystallized grains, and then performing purification annealing in saturated hydrogen at 1230°C was used as the material. there was.

The forsterite film on the surface of this steel plate was removed using a belt sander, and then electropolishing was performed to give a mirror finish with a centerline average roughness Ra of 0.08 μmm, followed by cold rolling at a reduction rate of 56.5% during re-rolling. 0.1■ after rolling
Made thick. Thereafter, after degreasing the surface of the steel plate, a tension imparting film (film thickness 0.05 μm) made of various nitrides, carbides, and carbonitrides was formed using the methods classified in Table 3. Annealing was carried out at a temperature within the range of 0.degree. C., and then an insulating film (thickness: 0.2 .mu.m) mainly composed of colloidal silica and phosphate was formed.

After that, accelerating voltage: 250 kV, accelerating current: 1. Magnetic domain refining was performed by irradiating an electron beam of 0 mA in a direction making an i angle with respect to the rolling direction at a scanning interval of 8 cm.

Iron loss W of the steel plate thus obtained, 3. ．． . are shown in Table 3.

Table: Ion implantation silane...3 As is clear from Table 3, the iron loss of these steel plates subjected to magnetic domain refining treatment is from 0.12 W/kg to 0.25 W/kg at W+3/sll.
kg and exhibits extremely low iron loss, comparable to amorphous iron cores.

(Effect of the invention) According to the present invention, after re-rolling a finish-annealed unidirectional silicon steel plate into an extremely thin material, in the specific invention, a tension imparting coating is applied and recrystallization annealing is performed. As a result, it is possible to easily produce a unidirectional ultra-thin silicon steel sheet that exhibits ultra-low iron loss comparable to that of amorphous iron cores. Further, in the third and fourth aspects of the invention, the iron loss can be further improved by performing magnetic domain refining processing.

The product obtained by this invention is suitable for use in iron cores of transformers and the like.

Claims (6)

[Claims] 1. Using a finish annealed unidirectional silicon steel sheet as a material, removing non-metallic substances on the surface of the steel sheet, and re-rolling the steel sheet from which the non-metallic substance has been removed at a reduction rate of 5% to 80%. 0.01mm to 0
．． When producing ultra-thin unidirectional silicon steel sheets through the following steps: making the plate thickness within the range of 15 mm, and annealing the re-rolled steel plate at a temperature within the range of 700°C to 1100°C. After re-rolling, Si, Mn, Cr, Ni, Mo
, W, V, Ti, Nb, Ta, B, Cu, Zr, Hf,
An ultra-low iron loss unidirectional ultra-thin silicon steel sheet characterized by being coated with one or more tension imparting coatings selected from the group consisting of nitrides, carbides, and carbonitrides of Al. manufacturing method. 2. 2. The method for producing an ultra-low core loss unidirectional ultra-thin silicon steel sheet according to claim 1, wherein the tension imparting coating is formed before annealing after re-rolling. 3. 2. The method for producing an ultra-low core loss unidirectional ultra-thin silicon steel sheet according to claim 1, wherein the tension imparting coating is formed after re-rolling and annealing. 4. Using a finish annealed unidirectional silicon steel sheet as a material, removing non-metallic substances on the surface of the steel sheet, and re-rolling the steel sheet from which the non-metallic substance has been removed at a reduction rate of 5% to 80%. 0.01mm to 0
．． When producing ultra-thin unidirectional silicon steel sheets through the following steps: making the plate thickness within the range of 15 mm, and annealing the re-rolled steel plate at a temperature within the range of 700°C to 1100°C. After re-rolling, Si, Mn, Cr, Ni, Mo
, W, V, Ti, Nb, Ta, B, Cu, Zr, HF,
and coating one or more types of tension imparting coating selected from nitrides, carbides, or carbonitrides of Al, and forming an insulating coating on the steel plate coated with the tension imparting coating after annealing. A method for producing an ultra-low iron loss unidirectional ultra-thin silicon steel sheet, characterized by: 5. Using a finish annealed unidirectional silicon steel sheet as a material, removing non-metallic substances on the surface of the steel sheet, and re-rolling the steel sheet from which the non-metallic substance has been removed at a reduction rate of 5% to 80%. 0.01mm to 0
．． When producing ultra-thin unidirectional silicon steel sheets through the following steps: making the plate thickness within the range of 15 mm, and annealing the re-rolled steel plate at a temperature within the range of 700°C to 1100°C. After re-rolling, Si, Mn, Cr, Ni, Mo
, W, V, Ti, Nb, Ta, B, Cu, Zr, Hf,
and forming one or more types of tension imparting coating selected from nitrides, carbides, or carbonitrides of Al, and performing magnetic domain refining treatment on the steel plate coated with the tension imparting coating after annealing. A method for producing an ultra-low iron loss unidirectional ultra-thin silicon steel sheet, characterized by: 6. Using a finish annealed unidirectional silicon steel sheet as a material, removing non-metallic substances on the surface of the steel sheet, and re-rolling the steel sheet from which the non-metallic substance has been removed at a reduction rate of 5% to 80%. 0.01mm to 0
．． When producing ultra-thin unidirectional silicon steel sheets through the following steps: making the plate thickness within the range of 15 mm, and annealing the re-rolled steel plate at a temperature within the range of 700°C to 1100°C. After re-rolling, Si, Mn, Cr, Ni, Mo
, W, V, Ti, Nb, Ta, B, Cu, Zr, Hf,
and coating one or more types of tension imparting coating selected from nitrides, carbides, or carbonitrides of Al, and forming an insulating coating on the steel plate coated with the tension imparting coating after annealing. 1. A method for producing an ultra-low iron loss unidirectional ultra-thin silicon steel sheet, characterized by: applying a magnetic domain refining treatment to the steel sheet coated with an insulating film.