JPS62290823A - Production of ultra low iron loss grain oriented silicon steel sheet provided with surface film having excellent adhesiveness - Google Patents

Abstract

PURPOSE:To improve the adhesiveness of a surface film consisting of TiN, etc., by subjecting the mirror-finished surface of a steel sheet to electron beam heating in a specific temp. range at the time of forming said surface film on the mirror-finished surface of the steel sheet after annealing by the ion plating. CONSTITUTION:After the surface of the grain oriented silicon steel sheet subjected to the finish annealing is removed of the oxide, the surface is finished by polishing to the specular surface having <=0.4mu center line average height Ra. The surface film consisting of at least one kind among TiN, TiC and Ti (C, N) is formed mainly by the ion plating on the surface of such steel sheet. The mirror-finished surface is subjected to the electron beam heating in a 200-600 deg.C heating range prior to the above-mentioned ion plating treatment in the above-mentioned process for producing the silicon steel sheet. The extra- low iron loss grain oriented silicon steel sheet provided with the surface film having the excellent adhesiveness is obtd. by the above-mentioned method.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention (Field of Industrial Application) Satisfies the ultimate requirements for improving the electrical and magnetic properties of grain-oriented silicon steel sheets, especially for reducing iron loss. The remarkable development efforts that have been made in recent years are gradually bearing fruit, but one of the serious drawbacks associated with these efforts is that when using unidirectional silicon steel sheets, so-called strain relief annealing is applied after processing and assembly. It has been pointed out that, when such a material is used, it inevitably causes characteristic deterioration, resulting in a disadvantage in that its usage is restricted.

In this specification, the following is related to the results of research and development that will lead to a new method that can advantageously meet the above requirements, regardless of whether or not it undergoes a high-temperature thermal history such as strain relief annealing. state

As is well known, unidirectional silicon steel sheets are products in which secondary recrystallized grains are highly concentrated in the (1101<001>, Goss orientation), and are mainly used in transformers and other electrical equipment. Used as an iron core, the product's magnetic flux density (B,.

It is required that the iron loss (represented by the value W+?/S) be high and the iron loss (represented by the value W+?/S) be low.

This unidirectional silicon steel sheet is manufactured through a wide variety of complicated processes, but numerous inventions and improvements have been made so far, and today products with a thickness of 0.30+n have magnetic properties of B.
,. 1, 90T or more, 1,7. . The magnetic properties of products with a weight of 1.05 mm/kg or less and a plate thickness of 0.23+n are 81°1.
, 89T or more, h, 7. . Unidirectional silicon steel sheets with ultra-low core loss of 0.90 W/kg or less are being manufactured.

In particular, recently there has been a marked increase in demand for features that reduce power loss from an energy-saving perspective, and in Europe and the United States, when creating a transformer that requires less heating, the reduction in iron loss is converted into a monetary amount and added to the transformer price. The “loss evaluation” (iron loss evaluation) system is becoming widespread.

(Prior Art) Under these circumstances, recently, the surface of a unidirectional silicon steel sheet after final 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 stacked iron cores that are not subjected to strain relief annealing. There is a drawback that the laser irradiation effect disappears because microstrains are released by annealing and the magnetic domain width becomes wider.

On the other hand, earlier in Japanese Patent Publication No. 52-24499, the surface of the unidirectional silicon steel sheet after finishing and final annealing was mirror-finished, or the mirror-finished surface was plated with metal or further insulated. A method of manufacturing an ultra-low core loss unidirectional silicon steel sheet by applying and baking a coating has been proposed.

However, this method of improving iron loss through mirror finishing cannot be adopted from a process standpoint, as it does not contribute enough to reducing iron loss despite the significant cost increase. Due to problems with adhesion after coating, 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) The inventors believe that even if they take advantage of the above-mentioned effect of improving iron loss through mirror finishing, the above-mentioned cost increase is still possible from the perspective of today's energy-saving material development. Based on this basic understanding, we believe that it is important to overcome the problems of insulating layer adhesion and durability without deteriorating the characteristics even during high-temperature treatment, and in particular, we believe that it is important to overcome the disadvantages of ion play. It is an object of the present invention to achieve an advantageous ultra-low iron loss by fundamentally improving the conditions for forming a tensioning film in the tensioning process.

(Means for Solving the Problems) The above-mentioned objectives are advantageously satisfied by a configuration based on the following matters.

After removing the oxides on the surface of the unidirectional silicon steel plate that has undergone finish annealing, the steel plate surface is polished to a mirror finish with a center line average roughness Ra of 0.4 μm or less, and then ion plating is performed, Mainly 7TiN,
TiC or Ti (C,N) (7) In a method for producing a grain-oriented silicon steel sheet coated with a surface coating consisting of at least one kind, the mirror-finished surface is coated at an angle of 200 to 600° prior to the ion plating treatment. A method for producing an ultra-low-iron unidirectional silicon steel sheet having a surface coating with excellent adhesion, the method comprising performing electron beam heating in a temperature range of C.

The following description will be based on specific experiments in which the success of this invention was achieved.

C: 0.044 wt: (hereinafter shown in %), Si
:3.44%Mn:0.070%, Se:0.020
%, Sb: 0.025% and Sb: 0.025% at 1350 °C.
After heating for an hour, it was hot-rolled to obtain a hot-rolled sheet with a thickness of 2.4 mm. Then, cold rolling was performed twice with intermediate annealing at 950° C. to obtain a final cold rolled sheet having a thickness of 0.23 mm. Then 820
After primary recrystallization annealing that also serves as decarburization in wet hydrogen at ℃, Al zOs (70%), Mg0 (
After applying an annealing separator containing Zr0z (5%) as the main component, secondary recrystallization annealing was performed at 850°C for 50 hours, followed by purification annealing at 1200°C for 110 hours in a dry hydrogen atmosphere. .

Thereafter, oxides on the surface of the steel plate were removed, and the surface of the steel plate was finished into a mirror-like state with a centerline average roughness Ra of 0.1 μm by chemical polishing.

After that, using an ion plating device R (IICD method), a TiN film (about 1.0 m thick) was applied to the sample with a load of 1 kg/m2.
The experiment was conducted in the following manner.

■After polishing, ultrasonic cleaning, Freon gas cleaning, bombardment (10 nin bombardment treatment in argon gas, sample temperature 300°C), and then ion plating treatment.

■After polishing, bombardment (10m in argon gas)
1n bombardment treatment, sample temperature was 300℃),
Then ion plating treatment.

■After polishing, the surface of the steel plate is heated to 300℃ using an electron beam, and then subjected to ion plating treatment.

Table 1 shows the results of investigating the magnetic properties and adhesion of the product plates obtained by applying each of the above treatments.

*Diameter that does not peel off even after 180° bending As is clear from the results shown in Table 1, the steel plate obtained by polishing (■), ultrasonic cleaning, Freon gas cleaning, bombardment, and then ion plating treatment. The magnetic properties are B
IG is 1.92T, iron loss is 77. is 0.70W/
kg, and the adhesion was not good as peeling occurred at 20 mm diameter.

In addition, after polishing (■), bombardment, and then ion plating, the magnetic properties are as follows:
1.92T, iron 1 member 1,7. . is 0.72W/fur
The peeling limit diameter was 25.times.1φ, and both magnetic properties and adhesion were insufficient.

On the other hand, the magnetic properties of the steel sheet obtained by polishing (■), preheating with an electron beam, and then ion plating are B. is 1.93T, iron...WIT/S.

is 0.67g, and the peeling limit diameter is 15a.
s, magnetic properties, and film adhesion were all excellent.

Next, a TiN coating experiment was conducted using a continuous ion plating device capable of processing in a high vacuum.

C: 0.048%, Si: 3.36%, Mn: 0.66
%, Se: 0.020%, Sb: 0.025% and M
A hot-rolled silicon steel sheet having a composition containing 0.025% o: was cold-rolled twice with intermediate annealing at 950° C. to obtain a final cold-rolled sheet with a thickness of 0.23 mm. After that, after decarburization and primary recrystallization annealing at 820°C in wet hydrogen, the surface of the steel sheet was coated with MgO (60%), A 1 z (h (35%),
After applying an annealing separator mainly composed of Zr(h(3%) and TiOz(2%)), secondary recrystallization annealing was performed at 850°C for 50 hours, and then in saturated hydrogen at 1200°C for 5 hours. Purification annealing was performed.

Thereafter, the surface of the copper plate was pickled, and then electrolytically combined to give a mirror surface with a centerline average roughness Ra of 0.05 μm.

Thereafter, Ti(C,N) coating was performed using continuous ion plating in the following manner.

First, prior to TiN(C,N) coating, an electron beam (pierce type EB with 90° deflection) was applied to the steel plate.
Preheating was carried out over a temperature range of 100 to 800° C. using a method of heating, and then a Ti(C,N) coating with a thickness of 0.8 μm was applied by ion plating (IIcD method).

In this case, the electron beam heating method was such that the electron beam was heated over the entire surface of the steel plate under conditions such that the electron beam was operated densely at the edges of the plate while being coarse at the center.

FIG. 1 shows the results of an investigation regarding the magnetic properties (core loss properties) and adhesion of the thus obtained product.

As is clear from the results shown in FIG. 1, both core loss characteristics and adhesion properties are significantly improved in the electron beam heating temperature range of 200 to 600°C.

(Function) In this way, prior to the ion plating treatment of TiN, TiC or Ti(C,N), by performing electron beam heating in a predetermined temperature range, ultra-low iron content and good film adhesion can be achieved. It is possible to obtain a unidirectional silicon steel sheet having the following properties. Electron beam heating, which precedes such ion plating, has the effect of raising the temperature of the plate while simultaneously cleaning the surface of the steel sheet by manipulating the beam, resulting in ultra-low iron loss. It seems possible. Incidentally, such an effect of cleaning the 'gI+Ji surface cannot be expected in the case of bombardment treatment because the surface becomes uneven.

In other words, in order to obtain ultra-low iron loss, it is necessary to clean and heat the surface of the steel plate to be subjected to brating treatment, and electrobeam heating is extremely effective for this purpose. In ion plating, it is possible to form a surface film with excellent adhesion, and as a result, a strong tension is exerted on the surface of a clean steel sheet while maintaining strong adhesion between the surface film and the steel sheet. The domain walls can move easily, and as a result, ultra-low iron loss unparalleled in the past can be achieved. Since the above method does not utilize the action of plastic minute strain components, there is no problem with thermal stability, and even when subjected to high temperature thermal history such as strain relief annealing, electrical and magnetic The physical characteristics will not deteriorate.

After finish annealing, it is necessary to remove oxides on the surface of the grain-oriented silicon steel sheet, polish it to make it mirror-like, and then perform ion plating treatment. In addition, the center line average roughness of the finished surface in a mirror state is Ra≦
It is necessary to have a mirror surface of 0.4 μm, and Ra>0.
When the thickness is 4 μm, the surface is rough, so a sufficient reduction in iron loss cannot be expected. Furthermore, the removal of oxides at this time may be performed using chemical treatments such as pickling or mechanical treatments such as grinding.
Furthermore, chemical polishing, electrolytic polishing, or Hough polishing can be suitably used to form a mirror surface.

Next, the thickness of this tension-applying film is preferably in the range of 0.05 to 5.0 μm.

If the film thickness is less than 0.05 μm, satisfactory tension cannot be expected to be applied, while if it exceeds 5.0 μm, the space factor and stoneness deteriorate, and it is also economically disadvantageous.

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

Before starting, the material contains conventionally known unidirectional silicon steel material components, such as ■C: 0.01 to 0.05%, Si: 2.50
~4.5910, Mn: 0.01~0.29'o,
Mo: 0.003-0.1%, Sb: 0.0
05 to 0.2%, a total of one or two types of S or Se,
Composition containing 0.005-0.05% ■C: 0. Old ~
0.08%, Si:2. O~4.0%, S:
0.005 ~ 0°05%, N2 0.001 ~
0.01%, Sol At: 0.01-0.06
X.

Sn: 0.01-0.5%, Cu: 0.01
~0.3%, Mn: O, composition containing O1~0.2% ■C: 0.01~0.06%, Si: 2.
0-4.0%, S: 0.005-0.05%, B
: 0.0003-0.0004%, N: 0.00
Composition containing 1-0.01%, Mn: 0.01-0.2% ■C: 0.01-0.06χ, Si: 2.0-4
．． 0%, Mn: 0.01-0.2% S or Sc, or 0.005-0.0% in total.
The hot-rolled sheet is then subjected to homogenization annealing at 800-1100°C and then cold-rolled once to form the final sheet II7. A one-time cold rolling method, in which the product is rolled, or a two-time cold rolling method, in which intermediate annealing is usually performed at 850°C to 1050°C, followed by further cold rolling; in the latter case, the initial rolling reduction is approximately 50% to 80%. , the rolling reduction at the end of R is approximately 50% to 85%, and the final cold-rolled plate thickness is 0.151 m to 0.35+n.

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, Al 203. is applied to the surface of the steel plate. ZrO□ or T
iO□.

Apply an annealing separator mainly composed of MgO or the like. The present invention is applicable regardless of whether forsterite is formed or not. In order to prevent the formation of a forsterite film after final annealing, it is necessary to increase the content of an inert annealing separator such as A I ZO:1.

After that, secondary recrystallization annealing is performed, but this step is (110)
This is done to sufficiently develop secondary recrystallized grains with <001> orientation, and is usually box annealed to immediately
This is done by raising the temperature above ℃ 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 is performed at 1100° in saturated hydrogen.
It is necessary to perform annealing at C or higher for 1 to 20 hours to achieve purification of the steel plate.

Next, in the present invention, after purification annealing, the oxide film on the surface of the steel sheet is removed using a strong acid such as sulfuric acid, nitric acid, or hydrofluoric acid. Further, this oxide removal may be performed by mechanical grinding.

After this oxide removal treatment, chemical polishing or electrolytic polishing
Alternatively, the surface of the steel plate can be polished to a mirror finish using a conventional method such as mechanical polishing using puff polishing, that is, the center line average roughness Ra is 0.4.
Finished to below μm.

The reason why Ra is limited to 0.4 μm or less is that Ra is 0.
．． This is because if it exceeds 4 μm, the surface will be rough and a sufficient reduction in iron content cannot be expected.

After that, ion plating equipment (HCD method, EB+
TiN, TiC by RF method, Fluti-arc method)
A surface coating consisting mainly of Ti(C,N) or Ti(C,N) is formed.Prior to such ion plating, the surface of the steel sheet is heated to a depth of 200 to 600% by electron beam heating.
It is essential to heat to a temperature of °C. In this case, the scanning method of the electron beam is preferably such that the steel plate is heated uniformly so that both edges of the steel plate are dense and the center is rough, as shown in the second section above.

Furthermore, such surface v1. The thickness of the membrane is 0.05 to 5.0μ
As mentioned above, it is desirable to set the value to m.

After forming the tension-applying film in this way, applying and baking an insulating film whose main components are phosphate and colloidal silica is the best way to use a transformer with a large capacity of up to 1,000,000 KVA. This is especially necessary in the formation of this insulating coated and baked layer, and conventionally known methods may be used.

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

(Example) n-Example - C: 0.044%, Si: 3.41%, Mn:
0.063%, Mo: 0.021%, Se:
A hot rolled sheet having a composition containing 0.020% and Sb: 0.025% was homogenized at 900°C for 3 minutes and then cold rolled twice with intermediate annealing at 950°C. A final cold-rolled sheet with a thickness of 0.23 mm was obtained.

After that, after primary recrystallization annealing that also served as decarburization annealing in wet hydrogen at 820°C, the steel plate surface was heated to A e 203 (70%) 1M.
After applying an annealing separator mainly composed of gO (30%), secondary recrystallization annealing was performed at 850° C. for 50 hours, followed by purification annealing at 1200° C. for 18 hours in saturated hydrogen.

After that, after removing the oxide film by pickling, 3% IIF and 11
20□ Finished to a mirror surface by chemical polishing in liquid.

Next, the finished iU surface was heated to 450°C by electron beam heating, and then ion plating was performed for 10 minutes using an ion plating device (HCD method) to form a 1.2 μm TiN tension-imparting insulating film. formed. The conditions for the sample at this time were an elastic tension of 0.8 kg/mm.

Next, an insulating coated and baked layer containing phosphate and colloidal silica as main components was formed, and strain relief annealing was performed at f&800'c for 2 hours.

The magnetic properties of the thus obtained product were as follows.

B+o=1.927. W+? /S. =0.68W/kg
.

Furthermore, the adhesion was good, with no peeling occurring even after 180' bending with a diameter of 25 mm.

Greater digitorum plexus C: 0.059%, Si: 3.38%, Mn:
0.076%, Al: 0.025%, S:
0.023%, N: 0.0069%, Cu: 0.1
% and Sn: A hot rolled sheet having a composition containing 0.05% was uniformly annealed at 1150°C for 3 minutes and then rapidly cooled, and then warm rolled at 300°C to a thickness of 0.20. The final cold-rolled sheet was obtained.

After that, after decarburization annealing in hydrogen at 850℃, the surface is coated with AI.
! After applying an annealing separator mainly composed of z03 (80%) and MgO (20%), the temperature was raised from 850°C to 1150°C at a rate of 8°C/h for secondary recrystallization, and then in soft hydrogen. Purification annealing was performed at 1200°C for 8 hours.

After that, the oxide film was removed by pickling, and then 3% HF
It was chemically polished in HzOt solution and finished to a mirror surface.

Next, the mirror-finished surface was uniformly heated to 500°C by scanning with an electron beam, and then an elastic tension of 0.5 kg/mm was applied to the steel plate using a multi-arter ion plating device. A thin film of TiC (1.7 μm thick) was formed on the mirror surface under the following conditions while adding , and then an insulating coated and baked layer containing phosphate and colloidal silica as main components was formed. 80
Strain relief annealing was performed at 0°C for 2 hours.

The magnetic properties of the thus obtained product were as follows.

B+o=1.92T, W+? /S. =0.70 匈/
kg.

The adhesion was also good with no peeling even after 25 layers - 1806 bends by -.

Injury ■ Yu C: 0.044%, Sj: 3.43%, Mn:
0.064%, Mo: 0.021%, Se: 0
．． After homogenization annealing of a hot rolled sheet having a composition containing 0.022% and Sb: 0.025% at 900°C for 3 minutes,
A final cold rolled sheet with a thickness of 0.20 layer m was obtained by cold rolling twice with intermediate annealing at 950°C.

After that, after decarburization annealing in wet hydrogen at 800℃, A
lzo:+ (60%), MgO (25%),
After applying an annealing separator mainly composed of Zn0 (15%), secondary recrystallization annealing was performed at 850°C for 50 hours, followed by purification annealing at 1180°C for 110 hours in soft hydrogen.

After that, after removing the oxide film on the steel plate surface by pickling, 3%
Chemical polishing was performed in IIF and 1120□ solution to give a mirror finish.

After that, continuous line ion plating equipment (IIC)
D method), T at a sample tensile load of 0.9 kg/mm2
A thin film (0.5 μm thick) of iN was formed. Prior to this ion plating, the surface of the plate was uniformly heated to 450° C. by electron beam scanning.

The magnetic properties of the thus obtained product were as follows.

B1゜”1.93T, W+7ys.-0,68W/k
g, and the adhesion was good, with no peeling occurring even when bent by 180 degrees with a diameter of 1511 mm.

(Effects of the Invention) Thus, according to the present invention, it is possible to obtain an ultra-low iron loss unidirectional silicon steel sheet that has excellent not only film adhesion but also iron loss characteristics, and the magnetic properties of the steel sheet thus obtained are Even when subjected to high temperature treatment such as strain relief annealing, it does not deteriorate.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between the heating temperature of the steel plate surface by the electron beam and the iron loss value and film adhesion of the product plate. Figure 2 is a diagram showing the scanning procedure of the electro beam on the steel plate surface. .

Claims (1)

[Scope of Claims] 1. After removing oxides from the surface of a unidirectional silicon steel plate that has undergone finish annealing, the steel plate surface is polished to a mirror finish with a center line average roughness Ra of 0.4 μm or less. Then, by ion plating, mainly TiN, T
In a method for manufacturing a grain-oriented silicon steel sheet coated with a surface coating made of at least one of iC or Ti(C,N), the mirror-finished surface is heated at a temperature of 200 to 600°C prior to the ion plating treatment. A method for producing an ultra-low iron loss unidirectional silicon steel sheet having a surface coating with excellent adhesion, the method comprising applying electron beam heating at a temperature within a range of 100 to 100 nm.