KR20040041772A - Method for manufacturing a high-silicon steel sheet - Google Patents

Abstract

PURPOSE: A method for effectively manufacturing high silicon strip having superior magnetic property in large quantities by diffusion annealing the coated silicon strip at high temperature after coating a slurry type Fe-Si based composite compound powder having certain particle size and Si content on the surface of a silicon strip is provided. CONSTITUTION: The method for manufacturing high silicon strip comprises a step of drying the coated strip after coating a slurry type Fe-Si based calcined powder having particle size corresponding to a sieve size of -25 mesh and containing 20 to 70 wt.% of Si on the surface of strip; and diffusion annealing the dried strip at an atmosphere of nitrogen gas containing 20% or more of hydrogen in the temperature range of 1,050 to 1,200 deg.C, wherein the Fe-Si based calcined powder is Fe-Si based composite compound powder, wherein the strip to be coated with the slurry contains 2.0 to 3.3 wt.% of Si, and wherein the strip to be coated with the slurry is dried in the temperature range of 200 to 700 deg.C.

Description

Method for manufacturing a high-silicon steel sheet

The present invention relates to a method for manufacturing a high silicon steel sheet having excellent magnetic properties, particularly magnetic properties at high frequencies, and more specifically, Fe-Si alloy powder on the surface of the steel sheet containing Si in the range of 2.0 to 3.3% The present invention relates to a method for producing a high Si steel sheet by applying a slurry solution of a coating composition for silicic acid diffusion and containing diffusion.

In general, high silicon steel products are excellent soft magnetic materials because hysteresis loss, magnetostriction, coercive force, magnetic anisotropy, and maximum permeability increase in iron loss as the silicon content increases in Fe-Si alloy. At this time, the decrease in magnetostriction and increase in maximum permeability do not increase indefinitely with the increase of silicon content and show the highest value in 6.5% Si steel, and 6.5% Si steel has the highest magnetic properties in the high frequency region as well as the commercial frequency. Reaching is well known. And by using the magnetic properties of high frequency band of high silicon steel, it is mainly applied to high frequency reactors such as generators for electric turbines, tram power, induction heating, and uninterruptible power supply, and high frequency transformers such as plating power, welding machine, and X-ray power. It is mainly used as a substitute for oriented silicon steel sheet. In addition, it can be applied to reduce the power consumption of the motor and increase the efficiency.

However, as the silicon content in Fe-Si steel increases, the elongation of the steel sheet decreases rapidly. Therefore, it is known that it is almost impossible to manufacture a cold rolled silicon steel sheet containing more than 3.5% of silicon. Therefore, despite the fact that the higher the silicon content, the better magnetic properties can be obtained, due to the limitation of cold rolling, it is not possible to manufacture high-silicon steel sheet by cold rolling, so it is possible to overcome the limitations of cold rolling. Research on alternative technologies has been attempted for a long time.

Techniques known to produce high silicon steel sheet have been the direct casting method of high silicon steel using single roll or twin roll, such as Japanese Patent Application No. 56-3625, and rolling in a heating state of proper temperature such as Japanese Patent Application No. 62-103321. It is known that the rolling method of rolling in a state in which high silicon steel is put inside and low silicon steel is put in the outside of a hot rolling method, such as Japanese Patent Laid-Open Publication No. 5-171281, but these techniques are not commercialized yet.

The technology being mass-produced as a high siliconization product is a technology for producing high silicon steel by incubating the silicon component on the surface of the material by chemical vapor deposition (CVD method) using 3% grade non-oriented products by SiCl4 gas. It is well known as Japanese Pat. No. 62-227078 and US Pat. No. 3,423,253. However, due to the difficulty of chemical vapor deposition technology, the diffusion annealing treatment after chemical vapor deposition is difficult to popularize and commercialize despite the fact that it is inevitable to sell more than 5 times higher price than existing 3% Si steel products. have.

In addition, EP1052043A2, JP2000192204, JP2000144248, JP200045025 and the like are also known to manufacture high silicon steel sheets using powder metallurgy, but this technique is also limited to cold rolling due to high Si content, so that steel sheets having a desired thickness can be manufactured. There was no problem.

In addition, EP 1052043A2, USP 33634148, and USP4073668, etc., are mixed with Fe-Si alloy powder alone or a binder, and propose a long time annealing method at low temperature after rolling with a reduction ratio of less than 5% after coating the mixed powder, but after rolling And mass production, such as the application of low temperature long time annealing, are not suitable for mass production.

Accordingly, the present invention has been made to solve the above-described prior art, in which the Fe-Si composite compound powder, which is formed to have a predetermined particle size and Si content, is applied to the surface of a steel sheet manufactured through a common cold rolling process in the form of a slurry. The purpose of the present invention is to provide a high silicon steel sheet manufacturing method capable of producing a large amount of high Si steel sheet having excellent magnetic properties by high temperature diffusion annealing.

The present invention for achieving the above object,

Applying to the surface of the steel sheet a slurry of Fe-Si-based powder containing a particle size of -25mesh and containing Si in a range of 20 to 70% by weight in the form of a slurry, followed by drying; And a step of diffusing annealing of the dried steel sheet in a 1050-1200 ° C., 20% or more hydrogen-containing nitrogen gas atmosphere.

In addition, the present invention,

Applying to the surface of the steel sheet containing 2.0 to 3.3% by weight of Si, Fe-Si-based small powder containing a particle size of -25mesh in a range of 20 to 70% by weight in the form of a slurry, followed by drying; And hot-diffusion annealing the dried steel sheet in a hydrogen-containing nitrogen gas atmosphere of 20% or more so that Si in the steel sheet diffuses and penetrates substantially uniformly 4.0% by weight or more without generating surface defects. It relates to a manufacturing method.

Hereinafter, the present invention will be described.

When Si metal is contacted with Fe metal under high temperature hydrogen or nitrogen atmosphere, above 950 ℃, Si component diffuses into Fe metal material and Fe metal diffuses into initial Si metal part so that the concentration is uniform. It has the nature to make it. Therefore, when the Si metal powder is brought into contact with the surface of the steel sheet and annealed at a high temperature, the interdiffusion reaction in which Si in the powder moves into the steel sheet and Fe in the steel sheet moves toward the powder due to the difference in Si concentration.

Comparing the diffusion rate of Fe and Si, the diffusion rate of Si is almost twice faster than that of Fe in the temperature range of 1050 ~ 1200 ℃, resulting in the phenomenon of mutually non-uniform diffusion, the Kenkendall Effect. do. However, the non-uniform diffusion state causes the defects of the non-uniform state at the interface of the diffusion reaction part, or the magnetic properties of the material produced by generating various compounds such as FeSi ₂ , FeSi, Fe ₅ Si ₃ and Fe ₃ Si on the reaction part surface. It acts as a deteriorating factor. Therefore, it was practically impossible to produce a high-silicon steel sheet product having a uniform composition without surface defects through the high-temperature diffusion of the Si-containing powder described above.

Therefore, in order to solve the above problems, the present inventors have studied the diffusion principle using the Si powder and the Fe powder. I would suggest.

That is, the present invention is characterized by controlling the particle size and composition of the Si-containing powder used as the dispersing agent so as to relatively suppress the diffusion of Si to Fe as much as possible, and setting the manufacturing conditions thereof. In other words, the present invention controls the particle size and composition of the Si-containing powder so that the Si atoms can be diffused by the same amount with the Fe atoms almost without forming a complex compound in which Fe and Si are bonded to the diffusion reaction portion on the surface of the steel sheet. It is characterized by setting the manufacturing conditions.

Hereinafter, the unit technology employed for controlling the diffusion amount of Si atoms in the present invention will be described in detail.

First, in order to slow down the diffusion rate of the Si component in the present invention, SiSi is a compound form of FeSi ₂ , FeSi or Fe ₅ Si _{3 in} which the Si metal is combined with Fe metal without using Si powder alone as a coating agent for silicic acid. Fe-Si based small component powder is made and used as basic component of coating agent for spreading silicic acid. Further, the content of Si in the powder is limited to less than 70% by weight so that the Fe-Si-based powder may exist in the form of Fe-Si-based compound.

Secondly, in the present invention, in order to suppress diffusion of Si atoms, the particle size of the Fe-Si-based small powder is refined and then coated on the surface of the steel sheet, so that the surface contact area between the material and the metal powder, that is, the mutual reaction area, can be obtained. It could be reduced to less than 10-30% and this fine acupuncture diffusion composition was able to firmly adhere to the material surface. Specifically, in the present invention, the particle size of the Fe-Si-based small powder is limited to -25 mesh.

Third, in the present invention, the Fe-Si-based small powder prepared as described above is applied to the surface of the steel sheet in the slurry state, and then controlled to the atmosphere gas so that a thin oxide film can be formed on the surface of the steel sheet during high temperature diffusion annealing. Since the surface oxide layer acts as a barrier for the interdiffusion reaction, it is possible to reduce the diffusion of Si atoms into the material.

Hereinafter, the high silicon steel sheet manufacturing method of the present invention will be described in detail.

First, the Fe-Si-based small component manufacturing process to be applied to the steel sheet for silicication in the present invention will be described.

The Fe-Si-based small component powder of the present invention may be prepared by mixing Fe powder and Si powder with each other and firing at a temperature of 1000 to 1200 ° C. under nitrogen, hydrogen, or a mixed gas of hydrogen and nitrogen for 3 to 7 hours. However, this is merely an example, and the present invention is not limited thereto, and the powder may be prepared by various methods.

At this time, the compound component of the small powder powder is changed according to the amount of the Fe powder and the Si powder. In theory, the compound of FeSi ₂ is produced in the case of 50% Si + 50% Fe, and in the case of 34% Si + 66% Fe The FeSi compound is present as a compound of Fe ₅ Si ₃ at 25% Si + 75% Fe and as a compound of Fe ₃ Si at 14% Si + 86% Fe. However, in actual firing, several compounds may be mixed little by little depending on the initial mixing state. In particular, during the calcination reaction by mixing Fe and Si powder, the reaction proceeds in a state in which the Si powder and the Fe powder are interspersed and intruded from each other. Therefore, even if the amount of Si blended is large, most of the small powder surface has FeSi ₂ compound or FeSi compound in which Fe is in a diffused state and pure Si exists in the surface thereof. Si-based compound is present.

On the other hand, in the present invention, it is required to limit the Si content in the powder to 70% by weight or less so that the Fe-Si-based small powder prepared as described above can exist in the form of Fe-Si-based compound. If the Si content of the Fe-Si powder exceeds 70%, since the main component of the powder is present in the mixture of excess metal Si phase in addition to FeSi ₂ , the metal Si component is in contact with the surface of the material, and thus defects may be generated on the surface during diffusion annealing. Is large, and control of the amount of silencing can be difficult.

In addition, if the Si content is less than 20%, the Si self content is too small, so the diffusion rate may be too slow. Also, since the self density is large, these small powders may be formed into a slurry, and thus dispersibility may be poor when applied to the material surface in the field. In addition, it is preferable to limit the Si content in the Fe-Si-based small component powder to 20 to 70%.

In the case of using the Fe-Si-based small component powder prepared as described above as a precipitating agent of the steel sheet, it is most economical in the production site to make such small powder into a slurry state and coat it on the surface of the steel sheet using a roll coater. However, the small particle size of Fe-Si-based powder should be as fine as possible, so that the coating workability is excellent in the field coating work and is advantageous in terms of surface shape management of the material during the diffusion reaction.

Therefore, in the present invention, since the Fe-Si-based small powder prepared after the calcination reaction is in a half-lump state fused to each other in a high temperature and long time reaction, it is preferable to refine the particle size, and as the particle size of the powder becomes fine, it is applied on site. It is advantageous from the side of the castle. However, it is more preferable to limit the particle size to -25mesh in consideration of the granulated powder productivity.

Meanwhile, in the present invention, the Fe-Si small component powder whose composition and particle size are controlled as described above is made into a slurry form mixed with water, and then applied to the surface of the steel sheet.

The present invention is not limited to a specific solvent component in forming such a slurry. Preferably, the colloidal silica solution or the sol state of the colloidal silica solution, which is an ultra fine particles having a colloidal particle size having excellent powder separation in water, is excellent. A slurry may be prepared by blending Lonisol particles or ultrafine silica particles with the Fe-Si-based small powder.

The present invention is also not particularly limited to the steel sheet to which the Fe-Si-based small powder is to be applied, it is possible to use a steel sheet which can be produced through the production process of the oriented silicon steel sheet or non-oriented silicon steel sheet using a conventional cold rolling method . For example, conventional oriented silicon fabricated through steel slab manufacture, reheating, hot rolling, hot rolled sheet annealing and cold rolling, thickness adjustment, decarbonization annealing, optionally annealing, hot annealing for secondary recrystallization and final insulation coating A steel sheet may be used, or a cold rolled steel sheet obtained in a conventional non-oriented silicon steel sheet manufacturing process may be used.

The present invention is also not limited to the steel sheet composition to which the slurry is to be applied, but at least the steel sheet preferably contains 2.0 to 3.3% of Si. If the Si content is less than 2.0%, it takes not only too long time but also economical disadvantages in the precipitation diffusion reaction using Fe-Si powder, which is a silicon diffusion agent, and if it exceeds 3.3%, the steel is vulnerable to cold rolling. This can be extremely bad.

Next, in the present invention, the steel sheet coated with the slurry is dried and then wound into a large coil. At this time, it is preferable to limit the drying temperature to 200 ~ 700 ℃, because the drying time is too long at the drying temperature of less than 200 ℃ is not good productivity, if the temperature exceeds 700 ℃ there is a fear of generating oxide on the material surface.

Subsequently, the dried steel sheet is charged into an annealing furnace to be subjected to high temperature diffusion annealing. In this case, it is necessary to control the remainder containing 20% or more of hydrogen to a nitrogen gas atmosphere. If the hydrogen content is less than 20%, a rather thick and non-uniform oxide layer of Fayalite is formed on the surface of the material, resulting in uneven deposition reaction inside the material. This is because iron loss may rapidly deteriorate due to the formation of AlN precipitates during the cooling process after annealing.

In addition, the diffusion annealing of the steel sheet coated with the Fe-Si-based powder powder at an annealing temperature and time sufficient to diffuse and penetrate substantially uniformly in the range of 4.0 to 6.5% by weight without causing surface defects in the steel sheet by diffusion annealing. It is preferable to.

Specifically, in the present invention, it is preferable to limit the annealing temperature to 1050 ~ 1200 ℃. If the annealing temperature is lower than 1050 ° C., the soaking rate is too slow to take a long time to spread, and the surface shape of the soaking reaction interface may be coarse, which may deteriorate the magnetism. And if it exceeds 1200 ℃ and the reaction rate is too fast, the surface of the coiling coil appears between the appearance of the coiling work may be worse after work separation.

In addition, the annealing time is preferably limited to 1 to 10 hours, which means that the annealing time is less than 1 hour and the amount of deposition is difficult and difficult to control uniformly. This is because the shape of the surface of the material may be deteriorated by excessive long time reaction.

Meanwhile, in the present invention, the insulating coating layer may be formed again on the surface of the steel sheet subjected to the immersion diffusion annealing as described above. For example, when the steel sheet is a oriented silicon steel sheet, it is formed by applying an insulating coating agent consisting of a small amount of chromic anhydride to a mixed phosphate and colloidal silica of magnesium, aluminum and calcium, or to improve the punchability of the chromate and acrylic resin center The organic-inorganic composite coating agent may be formed by coating, but the present invention is not limited to the specific composition of the insulating coating agent. If the steel sheet is a non-oriented silicon steel sheet, the insulating coating layer may be formed by applying an organic-inorganic composite coating agent containing chromate and an acrylic resin as a main component.

Hereinafter, the present invention will be described in detail with reference to examples, but these examples are not limited by the description of these specific embodiments of the present invention as one possible embodiment of the present invention.

(Example 1)

0.23mm thick oriented silicon steel sheet, which contains 3.05% Si, 0.12% Mn, 0.025% Cu, 0.13% P, 0.013% P, residual iron and unavoidable impurities in weight% through the usual manufacturing process of oriented silicon steel sheet Prepared. Then, after removing the insulating coating layer on the surface of the steel sheet thus prepared, as shown in Table 1, Fe-Si based small powders having different particle sizes and compositions were dispersed in a colloidal silica solution and applied to the surface in the form of a slurry.

On the other hand, the solvent colloidal silica solution used herein is a commercially available 30% colloidal silica solution product in the market, and the mixing ratio is 100 parts by weight of Fe-Si powder, so that the silica is 20 parts by weight based on the solid content The colloidal silica solution was mixed.

The steel sheet coated with Fe-Si-based powder was dried at a temperature of 400 ° C., and then visually observed after coating on its surface to make a large coil. The coiled steel sheet was diffused and annealed at 1125 ° C. for 4 hours in a 50% hydrogen-containing nitrogen atmosphere. Then, after removing the unreacted material from the surface of the steel sheet after the immersion diffusion reaction, the state after the surface annealing was observed. The coated silicon phosphate and colloidal silica components of magnesium, aluminum and calcium were coated with a coating agent consisting of a small amount of chromic anhydride to prepare a grain-oriented silicon steel sheet having an insulating coating layer.

The Si content and magnetic properties of the manufactured products were investigated. The magnetic loss values of iron loss and magnetic flux density (B8) were measured using a single plate measuring instrument. The iron loss value W _10/50 is 50Hz, the core loss in the 1.0Tesla, W _10/400 at 400Hz, 1.0Tesla, W _5/1000 represents the core loss at 1000Hz, 0.5Tesla, the magnetic flux density value B8 is The magnetic flux per unit area generated when the magnetizing force of 800A-turn / m is received is represented by Tesla, and the amount of Si of the material is the result of wet analysis.

division Fe-Si powder Application state Magnetic properties Surface condition Material Si (%) Si (%) Mesh B ₈ (Tesla) W _10/50 (W / Kg) W _10/400 (W / Kg) W _5/1000 (W / Kg) Comparative Example 1 12 -325 Good 1.88 0.32 7.3 8.7 Good 3.7 Inventive Example 1 25 -325 Good 1.79 0.30 6.7 7.4 Good 4.3 Inventive Example 2 45 -325 Good 1.71 0.27 6.0 6.7 Good 5.8 Inventive Example 3 62.5 -325 Good 1.69 0.26 5.8 6.4 Good 6.2 Comparative Example 2 75 -325 Good 1.57 0.35 7.9 8.6 Small 7.4 Comparative Example 3 85 -325 Good 1.55 0.36 8.2 9.4 Hole 7.9 Comparative Example 4 100 -325 Good 1.52 0.38 8.8 10.9 Hole 8.5 Comparative Example 5 50 +150 tenuity 1.73 0.32 7.1 7.9 flaw 4.9 Comparative Example 6 50 +250 Heterogeneity 1.71 0.32 6.9 7.5 flaw 5.2 Inventive Example 4 50 -325 Good 1.70 0.27 6.1 6.4 Good 5.9 Inventive Example 5 50 -450 Good 1.70 0.26 6.0 6.4 Good 6.0

As shown in Table 1, Examples 1 to 5 of the present invention (1 to 5) in which the Si content was properly controlled in the Fe-Si-based small powder were increased, and the iron loss at the high frequency as well as the commercial frequency was extremely excellent. The application state was also favorable.

On the contrary, the comparative example (1) having a small content of Si in the Fe-Si small powder had a small amount of deposition of the material, so that the magnetic improvement effect was insignificant, and the comparative material (2-4) having a Si content of 70% or more had a Si enrichment amount. Although the defects such as holes are formed on the surface of the material, the magnetism of the material is rather deteriorated.

On the other hand, the comparative examples (5 to 6) in which the particle size of the Fe-Si-based small powder was outside the scope of the present invention had a thin and uneven coating thickness when applied in a slurry state. Defects were observed to show relatively poor quality characteristics such as weak or deteriorated magnetic improvement.

(Example 2)

By weight steel slab composed of Si 2.9%, Mn 0.022, Al 0.3%, Sn 0.025%, P 0.003%, C 0.0025%, S 0.0011%, N 0.0003%, balance iron and inevitable impurities at 1220 ℃ After reheating and hot rolling, a hot rolled sheet having a thickness of 2.5 mm was prepared. Subsequently, after hot-rolled sheet annealing at 1000 DEG C for 5 minutes and pickling treatment, it was cold rolled to a final thickness of 0.20 mm, and then the rolled oil adhered to the surface was removed.

The Fe-Si-based small component powders prepared as shown in Table 2 on the surface of the plurality of cold rolled plates thus prepared were dispersed in a colloidal silica solution and applied in a slurry form. As the colloidal silica solution used here, a commercially available 30% colloidal silica solution was used. The mutual mixing ratio is 100 parts by weight of Fe-Si powder, and the colloidal so that the silica is 20 parts by weight based on the solid content. The silica solution was mixed.

The Fe-Si-based small powder coated steel sheet was dried at a temperature of 400 ° C., and then the surface coating state was visually observed, followed by winding to make a large coil. After diffusion annealing at 1125 ° C. for 4 hours in a 50% hydrogen-containing nitrogen atmosphere, the unreacted material on the surface of the steel sheet after the immersion diffusion was removed and the state after diffusion annealing on the surface of the material was observed. A non-oriented high silicon steel sheet having an insulating coating layer was prepared by applying an organic-inorganic composite coating agent containing a resin as a main component.

Si content and magnetic properties of the products thus prepared are investigated and shown in Table 2 below, wherein the specific characteristic evaluation criteria are the same as in Example 1.

division Fe-Si powder Application state Magnetic properties Surface condition Material Si (%) Si (%) Mesh B ₈ (Tesla) W _10/50 (W / Kg) W _10/400 (W / Kg) W _5/1000 (W / Kg) Comparative Example 1 12 -325 Good 1.46 0.80 11.45 11.06 Good 3.5 Inventive Example 1 25 -325 Good 1.38 0.72 10.24 10.01 Good 4.2 Inventive Example 2 50 -325 Good 1.32 0.64 9.14 8.98 Good 5.6 Inventive Example 3 62.5 -325 Good 1.28 0.62 8.52 8.43 Good 6.0 Comparative Example 2 75 -325 Good 1.23 0.71 11.02 11.23 Small 6.8 Comparative Example 3 85 -325 Good 1.21 0.73 11.11 11.52 Hole 7.1 Comparative Example 4 100 -325 Good 1.20 0.74 11.36 12.02 Hole 7.7 Comparative Example 5 50 +150 tenuity 1.36 0.70 10.12 9.96 flaw 4.5 Comparative Example 6 50 +250 Heterogeneity 1.35 0.68 9.88 9.75 flaw 4.8 Inventive Example 4 50 -325 Good 1.31 0.64 9.03 8.82 Good 5.7 Inventive Example 5 50 -450 Good 1.26 0.61 8.50 8.41 Good 6.1

As shown in Table 2, the present invention examples (1 to 5) using the Fe-Si-based small powder of which the composition as well as the particle size is optimally controlled is increased as the amount of Si enrichment of the material is not only commercial frequency but also iron loss at high frequency. It was extremely excellent and the application state was also good.

On the contrary, Comparative Example (1) using Fe-Si-based small powder containing too small Si content had a weak magnetic improvement effect because the amount of material deposition was too small, and Comparative Example (2-4) having Si content exceeding 70% Although the amount of Si enrichment is large, defects such as holes are formed on the surface of the material, and thus the magnetic property of the material is rather deteriorated.

On the other hand, in the comparative examples (5 to 6) in which the particle size of the Fe-Si-based small powder was outside the scope of the present invention, the coating layer was thin and nonuniform. Accordingly, the amount of Si enrichment of the material was small and many defects on the surface of the material were observed. Tends to be weak or worsening.

(Example 3)

Fe-Si-based small powder was dispersed in a colloidal silica solution on the surface of the grain-oriented silicon steel sheet of Example 1 and applied in the form of a slurry. At this time, the Si content of the Fe-Si powder was 50%, the particle size of the powder was -25mesh, the colloidal silica was used as a solution of 30% solids in the market, the compounding ratio of 100 parts by weight of Fe-Si powder, silica The colloidal silica solution was mixed to make 20 parts by weight based on the solid content, thereby preparing a slurry.

The steel sheet coated with the Fe-Si-based small component powder was dried at a temperature of 400 ° C., and then made into a large coil. Then, the coated steel sheet was subjected to diffusion annealing for 5 hours by varying the diffusion annealing temperature and the atmospheric gas ratio as shown in Table 3 below. After observing the following state, the coating agent of Example 1 was applied to prepare a final high silicon oriented electrical steel sheet with an insulating coating layer.

The Si content and magnetic properties of the products manufactured as described above are shown in Table 3 below, and the specific evaluation method is the same as in Example 1.

division Diffusion Annealing Condition Magnetic properties Surface condition Material Si (%) Temperature (℃) H ₂ / N ₂ + H ₂ (%) B ₈ (Tesla) W _10/50 (W / Kg) W _10/400 (W / Kg) W _5/1000 (W / Kg) Comparative Example 1 950 50 1.76 0.34 6.8 7.7 Small hole 4.8 Comparative Example 2 1000 50 1.73 0.31 6.3 6.9 Defect 5.4 Inventive Example 1 1050 50 1.72 0.27 6.1 6.5 Good 5.9 Inventive Example 2 1100 50 1.70 0.26 5.9 6.3 Good 6.1 Inventive Example 3 1175 50 1.70 0.26 5.8 6.3 Good 6.2 Comparative Example 3 1225 50 1.65 0.28 6.1 6.7 Defect 6.4 Comparative Example 4 1125 0 1.85 0.30 7.3 8.9 Good 3.6 Comparative Example 5 1125 10 1.83 0.29 6.8 8.0 Good 3.8 Inventive Example 4 1125 25 1.70 0.26 5.8 6.2 Good 6.2 Inventive Example 5 1125 70 1.69 0.26 5.7 6.2 Good 6.3

As shown in Table 3, the present invention examples (1 to 5) in which the diffusion annealing temperature and the atmosphere gas conditions were properly controlled, all the Si amount of the material was increased, the iron loss at the high frequency as well as the commercial frequency was extremely excellent.

On the contrary, in Comparative Examples (1 to 2) having relatively low annealing temperatures, the amount of increase in the amount of Si of the material was insignificant, resulting in not only the improvement of iron loss but also the surface defects. . In Comparative Example (3) where the annealing temperature was too high, many surface defects occurred, and the magnetic properties were also poor.

On the other hand, in Comparative Examples (4 to 5) in which the hydrogen ratio in the total gas during diffusion annealing was too small, there was almost no change in the amount of Si in the material, so that high silicon steel having excellent magnetic properties could not be obtained.

(Example 4)

Fe-Si powder was dispersed in a colloidal silica solution on the surface of a cold rolled steel sheet prepared as in Example 2 and applied in the form of a slurry. At this time, the Si content of the Fe-Si-based powder was 60%, the particle size of the powder was -25mesh, the colloidal silica used a solution of 30% solids in the market. The blending ratio was mixed with 100 parts by weight of Fe-Si powder based on solid content, and a colloidal silica solution such that silica was 20 parts by weight based on the solid content.

The steel sheet coated with the Fe-Si-based small component powder was dried at a temperature of 400 ° C., and then made into a large coil. Then, the coated steel sheet was subjected to diffusion annealing for 5 hours by changing the diffusion annealing temperature and the atmospheric gas ratio as shown in Table 4 below. After observing the state after, the coating agent as in Example 2 was applied to prepare a non-oriented silicon steel sheet having an insulating coating layer.

The Si content and magnetic properties of the products manufactured as described above are shown in Table 4 below, and the specific evaluation method is the same as in Example 1.

division Diffusion Annealing Condition Magnetic properties Surface condition Material Si (%) Temperature (℃) H ₂ / N ₂ + H ₂ (%) B ₈ (Tesla) W _10/50 (W / Kg) W _10/400 (W / Kg) W _5/1000 (W / Kg) Comparative Example 1 950 50 1.35 0.69 10.03 9.97 Small hole 4.7 Comparative Example 2 1000 50 1.32 0.67 9.41 9.35 Defect 5.1 Inventive Example 1 1050 50 1.28 0.62 8.59 8.38 Good 5.9 Inventive Example 2 1100 50 1.27 0.62 8.48 8.36 Good 6.0 Inventive Example 3 1175 50 1.27 0.61 8.46 8.31 Good 6.1 Comparative Example 3 1225 50 1.23 0.68 9.23 9.38 Defect 6.3 Comparative Example 4 1125 0 1.41 0.78 10.52 10.48 Good 3.5 Comparative Example 5 1125 10 1.38 0.74 9.87 9.85 Good 3.7 Inventive Example 4 1125 25 1.27 0.61 8.46 8.33 Good 6.1 Inventive Example 5 1125 70 1.27 0.60 8.43 8.29 Good 6.2

As shown in Table 4, the present invention examples (1 to 5) in which not only the diffusion annealing temperature but also the atmospheric gas conditions are appropriately controlled, the amount of Si of the material is increased so that the iron loss at the commercial frequency and the high frequency is extremely excellent. There was no defect.

On the contrary, in Comparative Examples (1 to 2) having relatively low annealing temperatures, the amount of increase in the amount of Si of the material was insignificant, so that the iron loss was poor, and surface defects occurred. In Comparative Example (3) where the annealing temperature was too high, many surface defects occurred, and the magnetic properties were also poor.

On the other hand, in Comparative Examples (4 to 5) in which the hydrogen ratio in the total gas during diffusion annealing was relatively small, there was almost no change in the amount of Si in the material, so that high silicon steel could not be obtained and the degree of magnetic improvement was also weak.

As described above, the present invention is applied to the surface of the silicon steel sheet produced by a common cold rolling process, the slurry of Fe-Si composite compound composition formed to have a predetermined particle size and Si content in the form of a slurry, followed by high temperature diffusion annealing By doing so, it is possible to efficiently manufacture high Si steel sheets having excellent magnetic properties in large quantities.

Claims (8)

Applying to the surface of the steel sheet a slurry of Fe-Si-based powder containing a particle size of -25mesh and containing Si in a range of 20 to 70% by weight in the form of a slurry, followed by drying; And And a step of diffusion annealing the dried steel sheet in a 1050-1200 ° C., at least 20% hydrogen-containing nitrogen gas atmosphere. The method of claim 1, wherein the Fe-Si-based small component powder is a Fe-Si-based composite powder manufacturing method characterized in that the powder. 2. The method of claim 1, wherein the steel sheet to be coated with the slurry contains 2.0 to 3.3% by weight of Si. The method of claim 1, wherein the slurry-coated steel sheet is dried at 200 ~ 700 ℃. Applying to the surface of the steel sheet containing 2.0 to 3.3% by weight of Si, Fe-Si-based small powder containing a particle size of -25mesh in a range of 20 to 70% by weight in the form of a slurry, followed by drying; And A high-temperature diffusion annealing of the dried steel sheet in a hydrogen-containing nitrogen gas atmosphere of 20% or more so that Si in the steel sheet diffuses and penetrates more than 4.0 wt% substantially uniformly without generating surface defects. Way. The method of claim 5, wherein the Fe-Si-based small component powder is a Fe-Si-based composite powder powder manufacturing method. The method of claim 5, wherein the dried steel sheet is subjected to diffusion annealing at a temperature range of 1050 ~ 1200 ℃. The method of claim 5, wherein the slurry-coated steel sheet is dried at 200 ~ 700 ℃.