JPS6335684B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial application field) Improvement of electrical and magnetic properties of unidirectional silicon steel sheets,
In particular, the remarkable development efforts made in recent years to meet the extreme requirements of reducing iron loss are gradually bearing fruit, but one serious problem associated with their implementation is the use of grain-oriented silicon steel sheets. It has been pointed out that when so-called strain-relief annealing is applied after initial processing and assembly, deterioration of properties inevitably occurs, resulting in restrictions on usage. In this specification, the following is related to the results of research and development to open up 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 (100) [001], or Goss, orientation, and are mainly used in transformers and other electrical equipment. Used as an iron core, the product is required to have high electrical and magnetic characteristics such as high magnetic flux density (represented by the B ₁₀ value) and low iron loss (represented by the W _17/50 value). 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 products with a thickness of 0.30mm have magnetic properties of B ₁₀ 1.90T or more, W _{17/ 50} 1.05W/Kg or less, and the magnetic properties of products with a plate thickness of 0.23mm are B ₁₀ 1.89T
As described above, ultra-low core loss unidirectional silicon steel sheets with a W _17/50 of 0.90 W/Kg or less are being manufactured. In particular, recently there has been a marked increase in the demand for reducing power loss as a top priority from the standpoint of energy conservation.・The "Evaluation" (iron loss evaluation) system is becoming widespread. (Prior art) Under these circumstances, recently, a method has been developed in which micro-strain is introduced into the surface of a unidirectional silicon steel plate after final annealing by laser irradiation in a direction approximately perpendicular to the rolling direction to subdivide the magnetic domains. It was proposed to reduce iron loss by
No. 57-53419, Special Publication No. 58-26405 and Special Publication No. 58-
(See Publication No. 26406). This magnetic domain refining technology is effective for transformer materials for laminated cores that are not subjected to strain relief annealing, but for transformer materials for rolled cores that are subjected to strain relief annealing, it is difficult to introduce by laser irradiation. The disadvantage is that the laser irradiation effect is lost because the local microstrain is released by the annealing treatment and the magnetic domain width becomes wider. On the other hand, earlier in Japanese Patent Publication No. 52-24499, the surface of a unidirectional silicon steel plate after finish annealing was mirror-finished, or the mirror-finished surface was coated with metal thinning or an insulating coating was applied thereon. A method of manufacturing an ultra-low core loss unidirectional silicon steel sheet by coating and baking has been proposed. However, this method of improving iron loss through mirror finishing cannot be adopted from a process perspective, as it does not contribute enough to reducing iron loss at the cost of a significant increase in costs. 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 thin film of oxide ceramics is deposited after mirror-finishing the surface of a steel plate. 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 have sought to take advantage of the above-mentioned effect of improving iron loss due to the mirror finish, and in particular, from the viewpoint of the development of today's energy-saving materials, the inventors have developed a characteristic that outweighs the disadvantage of increased cost as described above. , especially the adhesion of the insulating layer without deteriorating its properties even during high-temperature treatment.
We believe that it is important to overcome the problem of durability,
Based on this basic understanding, we fundamentally reexamined the method of processing steel sheets after mirror finishing and arrived at this invention. (Means for solving the problem) As a result of various studies, C: 0.04 to 0.05 wt% (hereinafter simply expressed as %),
Si: 2.5~4.0%, Mn: 0.01~0.2%, Mo: 0.003
~0.1%, Sb: 0.005-0.2%, a total of 0.005-0.05% of any one or both of S and Se, and the remainder substantially consists of Fe, C: 0.04-0.08%, Si: 2.0 ~4.0%, Mn:
0.01~0.2%, sol Al: 0.005~0.06%, S:
0.005~0.05%, N: 0.001~0.01%, Sn: 0.01~
0.5%, Cu: 0.01~0.3%, the balance is essentially Fe
Composition consisting of C: 0.03-0.06%, Si: 2.0-4.0%, Mn:
0.01~0.2%, S: 0.005~0.05%, B: 0.0003~
0.004%, N: 0.001 to 0.01%, the remainder substantially consisting of Fe, C: 0.04 to 0.08%, Si: 2.0 to 4.0%, Mn:
0.01~0.2%, Sol Al: 0.005~0.06%, S:
A hot rolled sheet obtained by hot rolling a silicon steel slab having a composition of 0.005 to 0.05%, N: 0.001 to 0.01%, and the remainder substantially consisting of Fe is subjected to one or two intermediate annealing steps. Oxidation on the surface of a grain-oriented silicon steel sheet that has been cold rolled to the final thickness, decarburized and primary recrystallized annealed, and then subjected to final finishing annealing including secondary recrystallization annealing and purification annealing. After removing the material, use CVD, ion plating or ion implantation.
Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Co,
An ultra-thin tensile coating made of one or more selected from Ni, Al, B, and Si nitrides and/or carbides, and firmly adhered to the steel plate surface through a mixed phase with iron. (for example, the first invention), further forming thereon an insulating film containing phosphate and colloidal silica as main components (for example, the second to fourth inventions), and after forming an ultra-thin tensile film, An ultra-low core loss unidirectional silicon steel sheet can be advantageously obtained by following the steps of irradiating the laser beam in a direction transverse to the rolling direction (for example, the fifth invention) and further applying a low-temperature insulation coating thereon (for example, the sixth invention). I discovered that it can be done. Prior to this, the inventors mirror-polished a final annealed unidirectional silicon steel plate, and then formed an ultra-thin tensile coating of nitrides and carbides to create a low core loss unidirectional silicon steel plate. We found that it is possible to manufacture the steel sheet, but in this case, the surface of the steel plate must be polished to a mirror finish by chemical polishing or electrolytic polishing, so the manufacturing cost is extremely high. In the invention, the oxides on the surface of the finish annealed steel sheet are removed without an expensive polishing step, e.g. by pickling or mechanically grinding the surface, followed by CVD, ion plating or By forming an ultra-thin tensile film of the above-mentioned nitrides and carbides by ion implantation, we have established a means to obtain grain-oriented silicon steel sheets with ultra-low core loss at a lower cost. The explanation will proceed according to specific experiments that led to the success of each of the above inventions. C 0.046%, Si 3.38%, Mn 0.068%, Se
A continuously cast silicon steel slab containing 0.022%, Sb 0.025%, and Mo 0.025%, with the remainder substantially consisting of Fe,
After heating at 1340°C for 4 hours, it was hot rolled to obtain a 2.0 mm thick hot rolled sheet. Thereafter, after uniform annealing at 900°C for 3 minutes, cold rolling was performed twice with intermediate annealing at 950°C for 3 minutes to obtain a final cold-rolled plate with a thickness of 0.23 mm. After decarburization and primary recrystallization annealing in a wet hydrogen atmosphere at 820°C, inert Al ₂ O ₃ is added to the surface of the steel sheet.
(80%) and MgO (20%), followed by secondary recrystallization annealing at 850°C for 50 hours.
Purification annealing was performed at 1200°C in dry hydrogen for 5 hours.
The final annealed unidirectional silicon steel sheet coil thus obtained was divided into six sections, and each section was then lightly pickled (in a 10% HCl solution) to remove oxides on the surface of the steel sheet.

[Table] The samples were then processed as follows according to the categories (a) to (f) shown in Table 1. (a): An ultra-thin tension film of 0.5 μm made of TiN was formed at a sample temperature of 700° C. using an ion plating device. (b): Thereafter, an insulating film was formed on the phosphate using a coating liquid containing colloidal silica as a main component. (c): Separately, an ultra-thin tension film of TiN is formed and then laser irradiated (laser irradiation conditions:
Using YAG laser, laser irradiation scanning trace interval = 1 = 6 mm width, energy per laser spot: 4.0 × 10 ^-3 J, spot diameter: 0.2
mm, center-to-center spacing of subbots: 0.5 mm)
did. (d): Thereafter, baking treatment was performed at 600°C for 1 minute using a coating liquid containing phosphate and colloidal silica as main components. The magnetic properties of these products are summarized in Table 1, comparing the performance of comparative materials under each process treatment (e): pickling treatment after final annealing and (g): normal process conditions. As is clear from Table 1, the magnetic properties obtained by each of the treatments (a) to (d) according to the first to fourth inventions have a B ₁₀ of 1.91.
It is noted that at ~1.90T, the W _17/50 is extremely good at 0.82-0.75W/Kg. On the other hand, the magnetic properties obtained by simply removing oxides after pickling under condition (e) are B ₁₀ 1.89T and W _17/50.
is 0.94W/Kg, B ₁₀ of normal process material (f) is 1.89T,
Extreme deterioration is seen compared to W _17/50 which is 0.89W/Kg, and all are much worse than (a) to (d). As described above, in this invention, the oxide film on the surface of the steel plate after finish annealing is removed by pickling or mechanical grinding, and the finish is applied to the surface of the steel plate through an extremely thin mixed phase of nitrides, carbides, and base iron. Ultra-low iron loss unidirectional silicon steel sheets can be manufactured by forming an ultra-thin tensile film firmly adhered to the surface, and this manufacturing method does not require mirror polishing of the steel sheet surface after final annealing. This shows that it is possible to manufacture a unidirectional silicon steel sheet with low manufacturing cost and good magnetic properties. (Function) As mentioned above, after finishing annealing and removing the oxides on the surface, an ultra-thin tensile film is formed by CVD, ion plating or ion implantation to achieve ultra-low iron loss. It is possible to manufacture grain-oriented silicon steel sheets. Furthermore, in the present invention, an ultra-low core loss unidirectional silicon steel sheet can also be produced by introducing local strain onto this ultra-thin tension coating by laser treatment. The above experimental results are exclusively about the tension coating made of TiN, but the tension coating can also be made of Ti,
Zr, V, Nb, Ta, Cr, Mo, Co, Ni, Mn,
Even when it is composed of one or more and four or less selected from among the nitrides and/or carbides of Al, B, W, and Si, it has almost the same effect as described for TiN, and both Compatible with the purpose of the invention. Next, the manufacturing process of the unidirectional silicon steel sheet will be described in detail, including a general explanation. First, the reason for limiting the composition of the material for a unidirectional silicon steel sheet, which is the object of this invention, will be described below. C is an element that plays an important role in controlling a fine and uniform structure during hot rolling or cold rolling, but it is limited as follows depending on the inhibitor. In the Al-N-S and Al-N-Sn-Cu systems,
If the amount exceeds 0.08%, decarburization annealing before secondary recrystallization annealing takes a long time, reducing productivity, and decarburization becomes insufficient, resulting in deterioration of magnetic properties, while C decreases. As the iron loss increases, it becomes difficult to control the hot rolling texture and large elongated grains are formed, deteriorating the magnetic properties. Therefore, in order to obtain good iron loss properties, it is necessary to set the content to 0.04% or more. be. Next, Mo-S-Sb system, Mo-Se-Sb system and Mo
In the -S-Se-Sb system, if the amount exceeds 0.05%, the decarburization annealing before the secondary recrystallization annealing takes a long time, reducing productivity, and decarburization becomes insufficient, resulting in poor magnetic properties. On the other hand, as C decreases, it becomes difficult to control the hot rolling texture and large elongated grains are formed, deteriorating the magnetic properties. is 0.04
% or more. In addition, when the B-N-S system exceeds 0.06%, it takes a long time during decarburization annealing before secondary recrystallization annealing, reducing productivity, and decarburization becomes insufficient, resulting in poor magnetic properties. On the other hand, as C decreases, it becomes difficult to control the hot rolling texture and large elongated grains are formed, deteriorating the magnetic properties. teeth,
It needs to be 0.03% or more. Si is an important element for magnetic properties, especially iron loss properties, but it is limited as follows depending on the inhibitor. Al-N-S system, Al-N-Sn-Cu system and B-N
- In the S system, if it is less than 2.0%, the electrical resistance is low and the iron loss value increases due to increased eddy current loss;
If it is more than 4.0%, brittle cracking tends to occur during cold rolling, so Si needs to be in the range of 2.0 to 4.0%. Mo-S-Sb system, Mo-Se-Sb system and Mo-S
In the -Se-Sb system, if it is less than 2.5%, the electrical resistance is low and the iron loss value increases due to increased eddy current loss.On the other hand, if it is more than 4.0%, brittle cracks are likely to occur during cold rolling. Must be within the range of 4.0%. Mn is an inhibitor that controls the formation of secondary recrystallized grains with {110}<001> orientation, that is, an element essential for the precipitation of MnS or MnSe as a dispersed precipitation phase. If the Mn content is less than 0.01%, the absolute amount of MnS or MnSe to suppress primary recrystallized grain growth is insufficient, causing incomplete secondary recrystallization. On the other hand, if the Mn content exceeds 0.2%, MnS
Alternatively, it becomes difficult to dissociate solid solution of MnSe, and even if dissociated solid solution is carried out, the dispersed precipitated phase that precipitates during hot rolling tends to become coarse, and the optimal size distribution as an inhibitor is lost, resulting in poor magnetic properties. to degrade. For these reasons, Mn is 0.01-0.2
% range. Both Sb and Mo suppress the growth of primary grains in secondary recrystallization and promote the growth of secondary recrystallized grains with {110}<001> orientation due to the coexistence of S and Se, which will be described later. This plays a role in further improving the magnetic properties of the product. Therefore, the silicon steel material used in the method of the present invention should contain Sb and Mo in addition to S and/or Se, which will be described later. However, if Sb exceeds 0.2%, cold workability deteriorates, the magnetic flux density begins to decrease, leading to deterioration of magnetic properties, and Mo exceeds 0.1%.
%, not only hot workability and cold workability deteriorate, but also iron loss characteristics deteriorate. On the other hand, Sb
If Mo is less than 0.005% or 0.003%, the effect of these additions will be poor, so the Sb content should be 0.005 to 0.2.
%, and the content of Mo needs to be regulated within the range of 0.003 to 0.1%. S and Se act as inhibitors that suppress the growth of primary grains during secondary recrystallization.
It is an element necessary for the formation of MnS and MnSe, and it is fine if at least one of them is contained, but if the content exceeds 0.05%, whether added alone or in combination, hot or cold Since processability deteriorates, the upper limit of the content is set to 0.05%, whereas if the content is less than 0.005%, the absolute amount of MnS and MnSe is insufficient and the function as an inhibitor cannot be obtained, so the lower limit of the content is set to 0.005%. %. When Al is included in steel, it combines with N to form fine precipitates of AlN and acts as a strong inhibitor. In particular, sol Al
It is necessary to contain it in the range of 0.005 to 0.06%. This is because if the Al content is less than 0.005%, there will be insufficient precipitated grains of AlN fine precipitates as an inhibitor.
The development of secondary recrystallized grains with {110}<001> orientation becomes insufficient, and on the other hand, if it exceeds 0.06%, the {110}<
This is because the development of secondary recrystallized grains in the 001> orientation becomes poor. N is an essential element when using AlN or BN as an inhibitor. If the amount of N is less than 0.001%, the inhibitor effect of AlN or BN will be weak, while if the amount added exceeds 0.01%, surface defects called blisters will occur. Since this occurs frequently and the product yield decreases, N needs to be regulated within the range of 0.001 to 0.01%. B combines with N contained in steel to form fine BN precipitates and acts as a strong inhibitor. When B is less than 0.0003%, it is not effective as an inhibitor.
B should be limited to a range of 0.0003 to 0.004% because the amount of BN fine precipitates will be insufficient, and if it exceeds 0.004%, the development of secondary recrystallized grains with {110}<001> orientation will deteriorate. be. Sn is useful for refining secondary recrystallized grains and is 0.01
Below 0.5%, the effect is weak, while above 0.5%, Cu
Because it is added in combination with the above, rolling properties and pickling properties deteriorate. Cu is 0.01%, which is preferable for forming a multilayer film.
If it is less than 0.3%, it will have little effect on improving the coating, while if it exceeds 0.3%, it is unfavorable from the viewpoint of magnetic properties. Next, the hot-rolled sheet is uniformly annealed at 800-1100°C and then cold-rolled once to reach the final thickness, or it is usually subjected to intermediate annealing at 850-1050°C and further processed. In the two-step cold rolling method, in the latter case, the initial rolling reduction is about 50% to 80%, and the final rolling reduction is 50%.
The final cold-rolled plate thickness is 0.15mm to 0.35mm at a rate of 85% to 85%. After the final cold rolling, the steel plate finished to the product thickness is surface degreased and then subjected to primary decarburization recrystallization annealing in wet hydrogen at 750°C to 850°C. After that, an annealing separator whose main component is MgO is usually applied to the surface of the steel sheet. At this time, it is effective to prevent the formation of forsterite, which is generally prohibited from forming after final annealing, in order to simplify the subsequent pickling or mechanical grinding treatment of the steel plate, so it is recommended to use an annealing separator. as Al ₂ O ₃ , ZrO ₂ ,
It is preferable to use TiO ₂ or the like mixed with MgO in an amount of 50% or more. After that, secondary recrystallization annealing is performed, but this step is carried out to sufficiently develop secondary recrystallized grains with {110}<001> orientation, and is usually box annealed to immediately raise the temperature to 1000℃ or higher. This is done by heating and holding at that temperature. In this case, in order to develop a highly aligned secondary recrystallized grain structure in the {110}<001> orientation, it is advantageous to perform holding annealing at a low temperature of 820°C to 900°C.
In addition, slow heat annealing at a heating rate of 0.5 to 15° C./h may also be used. Purification annealing after secondary recrystallized grain annealing is performed in dry hydrogen.
It is necessary to perform annealing at 1100°C or higher for 1 to 20 hours to achieve purification of the steel plate. After this purification annealing, the oxide film on the surface of the steel sheet is removed with a strong acid such as sulfuric acid, nitric acid, or hydrofluoric acid, or by mechanical grinding, cutting, etc. of the surface. Then, by CVD, ion plating or ion implantation, Ti, Zr, V,
Nb, Ta, Cr, Mo, W, Mn, Co, Ni, Al,
An extremely thin film of about 0.1 to 2 μm is formed from one or more and four or less selected from B, Si nitrides and/or carbides. Although the effects of the present invention are not affected in any way by any combination of compounds constituting this ultra-thin film, the number is limited to four or less due to processing complexity and cost issues. Thereafter, an insulating film is formed on this ultra-thin tension film, mainly consisting of phosphate and colloidal silica, to ensure insulation. Further, laser irradiation is applied to this ultra-thin tension coating at intervals of approximately 3 to 15 μm in a direction substantially perpendicular to the rolling direction. The irradiation conditions at this time were to use a pulse laser, and the energy per spot was 1 to 10×.
10 ^-3 J/m ² , the spot diameter is 0.05 to 0.5 mm, and the optimal distance between the centers of the laser spots is 0.1 to 2.5 mm. It is also necessary to ensure insulation after laser irradiation, but in order to take advantage of the laser irradiation effect, insulation coating treatment must be performed at a low temperature of 600℃ or less.
It is appropriate to perform a short-time baking treatment of from seconds to 30 minutes. The main component of the treatment solution for this insulation coating treatment at 600℃ or below is a treatment solution containing one or more of phosphates and chromates, and includes colloidal silica, colloidal alumina, titanium oxide, and boric acid. Some contain one or more compounds added. In addition, as reducing agents for chromate, organic compounds such as polyhydric alcohols and glycerin, aqueous solutions or emulsion resins to improve processability, and organic resin powders with particle sizes of 1 μm or more to improve processability and high resistance are also available. One or more organic compounds may be contained. (Example) Example 1 C: 0.44%, Si: 3.42%, Mn: 0.068%, Mo:
A hot-rolled sheet containing 0.025%, Se: 0.024%, and Sb: 0.020%, and whose acid part is essentially Fe, was uniformly annealed at 900°C for 3 minutes, then intermediate annealed at 950°C.
Cold rolling was performed twice to obtain a final cold rolled sheet with a thickness of 0.23 mm. After decarburization annealing in wet hydrogen at 820°C, an annealing separator containing Al ₂ O ₃ (80%) and MgO (20%) as main components was applied to the surface of the steel sheet, followed by secondary re-treatment at 850°C for 50 hours. Crystal annealing was performed, followed by purification annealing in dry hydrogen at 1200° C. for 8 hours. Thereafter, the oxide film was removed by pickling, and then an ultra-thin 0.5 μm TiN film was formed by ion plating. Some subsequent products were coated with an insulating coating consisting mainly of phosphate and colloidal silica. The magnetic properties of products that have undergone these treatments are as follows: Ultra-thin film formation B ₁₀ = 1.92T, W _17/50 = 0.79W/
Kg ●Insulating coating on ultra-thin coating B ₁₀ = 1.91T, W _17/50 =
It was 0.78W/Kg. Example 2 C: 0.063%, Si: 3.36%, Mn: 0.086%, Al:
A hot-rolled sheet containing 0.024%, S: 0.028%, and N: 0.0068%, with the remainder substantially consisting of Fe, was uniformly annealed at 1150°C for 3 minutes and then rapidly cooled, and then quenched at 300°C.
A final cold-rolled sheet with a thickness of 0.23 mm was obtained by warm rolling. After decarburization annealing in wet hydrogen at 850℃, the surface
After applying an annealing separator mainly composed of Al ₂ O ₃ (60%) and MgO (40%), it was heated from 850℃ to 1150℃ at 8℃/
After secondary recrystallization by raising the temperature to hr, purification annealing was performed in dry hydrogen at 1200°C for 8 hours. After removing the oxide film by pickling,
Heat treatment was performed using a mixed gas of TiCl ₄ , H ₂ and N ₂ at a temperature of 900°C using the CVD method to form TiN with a thickness of 0.8 μm on the surface. Thereafter, laser irradiation was performed using a pulse laser under the following conditions. (The laser irradiation energy is 5×
10 ^-3 J/m ² , spot diameter 0.10 mm, spot center spacing: 2 mm). After that, the first part of the product is 550
A low-temperature insulating coating treatment was performed at ℃. The magnetic properties of these treated products are: Laser treatment B ₁₀ = 1.95T, W _17/50 = 0.76W/
Kg ●Insulating coating after laser treatment B ₁₀ =
It was 1.94T, W _17/50 = 0.75W/Kg. Example 3 C: 0.043%, Si: 3.44%, Mn: 0.066%,
A hot-rolled sheet containing Mo: 0.025%, Se: 0.0222, Sb: 0.025, with the remainder substantially consisting of Fe, was uniformly annealed at 900℃ for 3 minutes, and then subjected to intermediate annealing at 900℃ for 2 hours.
A final cold-rolled sheet with a thickness of 0.20 mm was obtained by cold rolling twice. After decarburization annealing in wet hydrogen at 820°C, an annealing separator containing Al ₂ O ₃ (80%), MgO (15%), and ZrO ₂ (5%) as main components was applied to the surface of the steel sheet, and then annealing was performed at 850°C. Secondary recrystallization annealing was performed for 50 hours, and purification annealing was performed in dry hydrogen at 1200°C for 10 hours. After that, the oxide film was removed by pickling, and then BN, Si ₃ N ₄ , ZrN,
Nitride of AlN, VN, NbN, MnN, CrN, WN,
After forming a tensile thin film (0.4 to 0.7 μm thick) of carbides of TiC, SiC, ZrC, MoC, TaC, CoC, and NiC, an insulating coating film mainly composed of phosphate and colloidal silica is applied to the surface. provided. Table 2 shows the magnetic properties of the products subjected to these treatments.

[Table] Example 4 (A)C 0.042%, Si 3.39%, Mn 0.066%, S
0.022%, Sb 0.031%, Mo 0.015%, (B)C 0.058
%, Si 3.43%, Mn 0.078%, S 0.026%, Al
0.031%, Cu 0.1%, Sn 0.04%, N 0.0081% and (C)C 0.036%, Si 3.31%, Mn 0.049%, S
A hot-rolled sheet of unidirectional silicon steel containing 0.029% B, 0.0022% B, and 0.0072% N, with the remainder substantially consisting of Fe was used. Among these, the hot rolled sheet (A) was uniformly annealed at 900°C for 3 minutes. Thereafter, it was cold-rolled twice with intermediate annealing at 950°C to obtain a final cold-rolled sheet with a thickness of 0.20 mm. In addition, the hot rolled sheets of (B) and (C) are heated at 1050℃ (B) and 950℃.
Cold rolling was performed twice with intermediate annealing at °C (C) to obtain a final cold rolled sheet with a thickness of 0.20 mm. After that, the final cold-rolled sheet (A) was heated in wet hydrogen at 820°C after degreasing the surface, and the cold-rolled sheets (B) and (C) were heated at 850°C (B) and 840°C (C).
After performing primary recrystallization annealing that also serves as decarburization in wet hydrogen, an annealing separator containing Al ₂ O ₃ (65%) and MgO (35%) as main components was applied onto the surface of the steel sheet. After that, the steel plate (A) was subjected to secondary recrystallization annealing at 850℃ for 50 hours, and the steel plates (B) and (C) were annealed for 150 hours from 850℃ to 1050℃.
After increasing the temperature at a rate of °C/hr to develop Goss-oriented secondary recrystallized grains, purification annealing was performed at 1200 °C in dry H ₂ for 10 hours. After that, oxides on the surface of the steel sheet were removed by pickling, and then a thin film tension coating of 2 to 4 types of nitrides, carbides, and nitrides and carbides shown in Table 2 was applied to the surface of the steel sheet by ion plating. After depositing an insulating film (approximately 1 μm thick), an insulating film containing phosphate and colloidal silica as its main components was baked. after that
Strain relief annealing was performed at 800°C for 2 hours. Table 3 shows the magnetic properties of the product at that time.

[Table] (Effects of the invention) In both the first to sixth inventions, oxides on the surface of grain-oriented silicon steel sheets that have undergone finish annealing form a tension film directly on the surface from which the film has been removed, without the need for mirror polishing. Therefore, a significant improvement in iron loss characteristics can be advantageously achieved without the disadvantage of increased processing costs due to mirror finishing.

Claims (1)

[Claims] 1 C: 0.04-0.05wt% Si: 2.5-4.0wt% Mn: 0.01-0.2wt% Mo: 0.003-0.1wt% Sb: 0.005-0.2wt% Any one of S and Se species or two species total
A hot-rolled sheet obtained by hot rolling a silicon steel slab containing 0.005 to 0.05 wt% with the remainder substantially consisting of Fe is cold-rolled once or twice with intermediate annealing in between to form a final sheet. After thickening, decarburization and primary recrystallization annealing are performed.
After removing oxides on the surface of a grain-oriented silicon steel sheet that has been subjected to final finish annealing including secondary recrystallization annealing and purification annealing, Ti, Zr, V, Nb, etc. are removed by CVD, ion plating or ion implantation.
Ta, Cr, Mo, W, Mn, Co, Ni, Al, B, Si
1 selected from nitrides and/or carbides of
A thermally stable, ultra-low iron loss unidirectional silicon steel sheet characterized by forming an ultra-thin tensile film firmly adhered to the surface of the steel sheet through a mixed phase with iron. manufacturing method. 2 C: 0.04-0.05wt% Si: 2.5-4.0wt% Mn: 0.01-0.2wt% Mo: 0.003-0.1wt% Sb: 0.005-0.2wt% Any one or two of S and Se in total
A hot-rolled sheet obtained by hot rolling a silicon steel slab containing 0.005 to 0.05 wt% with the remainder substantially consisting of Fe is cold-rolled once or twice with intermediate annealing in between to form a final sheet. After thickening, decarburization and primary recrystallization annealing are performed.
After removing oxides on the surface of a grain-oriented silicon steel sheet that has been subjected to final finish annealing including secondary recrystallization annealing and purification annealing, Ti, Zr, V, Nb, etc. are removed by CVD, ion plating or ion implantation.
Ta, Cr, Mo, W, Mn, Co, Ni, Al, B, Si
1 selected from nitrides and/or carbides of
Forms an ultra-thin tensile film that firmly adheres to the surface of the steel plate through a mixed phase with iron, and then forms an insulating film whose main components are phosphate and colloidal silica. A method for producing a thermally stable, ultra-low iron loss unidirectional silicon steel sheet characterized by: 3 C: 0.04-0.08wt% Si: 2.0-4.0wt% Mn: 0.01-0.2wt% sol Al: 0.005-0.06wt% S: 0.005-0.05wt% N: 0.001-0.01wt% Sn: 0.01-0.5wt % Cu: 0.01 to 0.3 wt%, and the remainder substantially consists of Fe. A hot rolled sheet obtained by hot rolling is subjected to cold rolling once or twice with intermediate annealing in between. After making the final plate thickness, decarburization and primary recrystallization annealing were performed.
After removing oxides on the surface of a grain-oriented silicon steel sheet that has been subjected to final finish annealing including secondary recrystallization annealing and purification annealing, Ti, Zr, V, Nb, etc. are removed by CVD, ion plating or ion implantation.
Ta, Cr, Mo, W, Mn, Co, Ni, Al, B, Si
1 selected from nitrides and/or carbides of
Forms an ultra-thin tensile film that firmly adheres to the surface of the steel plate through a mixed phase with iron, and then forms an insulating film whose main components are phosphate and colloidal silica. A method for producing a thermally stable, ultra-low iron loss unidirectional silicon steel sheet characterized by: 4 Contains C: 0.03-0.06wt% Si: 2.0-4.0wt% Mn: 0.01-0.2wt% S: 0.005-0.05wt% B: 0.0003-0.004wt% N: 0.001-0.01wt%, and the remainder is substantially A hot rolled sheet obtained by hot rolling a silicon steel slab made of Fe is cold rolled once or twice with intermediate annealing to achieve the final thickness, then decarburized and primary recrystallized. After annealing 2
After removing oxides on the surface of a grain-oriented silicon steel sheet that has been subjected to final finish annealing including secondary recrystallization annealing and purification annealing, Ti, Zr, V, Nb, etc. are removed by CVD, ion plating or ion implantation.
Ta, Cr, Mo, W, Mn, Co, Ni, Al, B, Si
1 selected from nitrides and/or carbides of
Forms an ultra-thin tensile film that firmly adheres to the surface of the steel plate through a mixed phase with iron, and then forms an insulating film whose main components are phosphate and colloidal silica. A method for producing a thermally stable, ultra-low iron loss unidirectional silicon steel sheet characterized by: 5 Contains C: 0.04-0.08wt% Si: 2.0-4.0wt% Mn: 0.01-0.2wt% Sol Al: 0.005-0.06wt% S: 0.005-0.05wt% N: 0.001-0.01wt%, the remainder being substantially A hot rolled sheet obtained by hot rolling a silicon steel slab made of Fe is cold rolled once or twice with an intermediate annealing to achieve the final thickness, and then decarburized and primary recycled. After crystal annealing 2
After removing oxides on the surface of a grain-oriented silicon steel sheet that has been subjected to final finish annealing including secondary recrystallization annealing and purification annealing, Ti, Zr, V, Nb, etc. are removed by CVD, ion plating or ion implantation.
Ta, Cr, Mo, W, Mn, Co, Ni, Al, B, Si
1 selected from nitrides and/or carbides of
It is characterized by forming an ultra-thin tensile film that firmly adheres to the surface of the steel plate through a mixed phase of these and iron, and then irradiating the steel plate with a laser in a direction transverse to the rolling direction of the steel plate. A method for producing thermally stable, ultra-low core loss unidirectional silicon steel sheets. 6 Contains C: 0.04-0.08wt% Si: 2.0-4.0wt% Mn: 0.01-0.2wt% Sol Al: 0.005-0.06wt% S: 0.005-0.05wt% N: 0.001-0.01wt%, the remainder being substantially A hot rolled sheet obtained by hot rolling a silicon steel slab made of Fe is cold rolled once or twice with an intermediate annealing to achieve the final thickness, and then decarburized and primary recycled. After crystal annealing 2
After removing oxides on the surface of a grain-oriented silicon steel sheet that has been subjected to final finish annealing including secondary recrystallization annealing and purification annealing, Ti, Zr, V, Nb, etc. are removed by CVD, ion plating or ion implantation.
Ta, Cr, Mo, W, Mn, Co, Ni, Al, B, Si
1 selected from nitrides and/or carbides of
Forms an ultra-thin tensile film that firmly adheres to the surface of the steel plate through a mixed phase with iron, and then irradiates the steel plate with a laser in a direction transverse to the rolling direction of the steel plate. A method for producing a thermally stable, ultra-low core loss unidirectional silicon steel sheet characterized by applying a low-temperature insulation coating treatment.