JP6660025B2 - Manufacturing method of grain-oriented electrical steel sheet - Google Patents

Description

  The present invention relates to a method for manufacturing a grain-oriented electrical steel sheet mainly used for an iron core of a transformer.

  Electrical steel sheets are soft magnetic materials that are widely used as core materials for transformers and generators. In particular, grain-oriented electrical steel sheets have a highly integrated crystal orientation in the {110} <001> orientation called the Goss orientation. And is characterized by having excellent magnetic properties. Of the properties required for grain-oriented electrical steel sheets, iron loss properties, in particular, are very important because they directly lead to energy loss of products.

  Conventional methods of reducing iron loss in grain-oriented electrical steel sheets include increasing the electrical resistance of the steel, reducing the thickness, and reducing the grain size to reduce eddy current loss. Known from. Furthermore, by irradiating the surface of the steel sheet with plasma jet, laser light, electron beam, etc., locally introducing strain on the steel sheet surface or forming grooves on the steel sheet surface, the magnetic domain width can be artificially subdivided. Also, techniques for reducing eddy current loss have been developed. Further, as a technique for reducing the hysteresis loss, a technique has been proposed in which the crystal orientation of secondary recrystallized grains is more highly aligned, and impurities in steel are reduced. However, these techniques have undergone various improvements to date, and there is less room for further improvement, and development of a new iron loss improvement technique is desired.

  Therefore, for example, Patent Literatures 1 and 2 propose a technique in which the surface of a steel sheet is mirror-finished by electrolytic polishing or chemical polishing, and the unevenness on the surface of the steel sheet is reduced to reduce hysteresis loss. This technology focuses on the fact that a forsterite film is formed on the surface of conventional grain-oriented electrical steel sheets, and the interface between the steel sheet substrate and the forsterite film has large irregularities, which causes a large hysteresis loss. is there. However, in order to reduce iron loss by this method, the presence of a coating that imparts a strong tension to the steel sheet surface is indispensable. The reason is that since the surface of the steel sheet is smooth, in the absence of a tension-imparting coating, the expansion of the magnetic domain width is promoted, and the iron loss increases significantly.

  However, when a strong tension-imparting film is formed on the surface of a steel sheet, a strong shear stress is generated at the interface between the steel sheet surface and the tension-imparting film. However, in a mirror-finished steel sheet, the film peels off due to poor adhesion of the film. easy. Therefore, there is a problem that the intended effect of imparting tension is not exhibited, and as a result, the reduction of the iron loss value is not achieved.

  As means for solving this problem, Patent Literature 1 and Patent Literature 3 described above propose a method in which metal plating is applied to a mirror-finished steel sheet surface, and a tension-imparting coating is applied thereon. Patent Document 4 proposes a method of forming a ceramic tension applying film by a sol-gel method, and Patent Document 5 proposes a method of forming a ceramic tension applying film by chemical vapor deposition or vacuum vapor deposition. Have been.

Japanese Patent Publication No. 52-24499 Japanese Patent Publication No. 05-87597 JP-A-11-131251 JP-A-2-243770 JP-B-56-04150

  However, in the methods disclosed in Patent Literatures 1 and 3, the metal-plated insulating coating is easily peeled off during the baking treatment, and the suitable range in which the peeling is suppressed is very narrow. Further, even if the peeling is avoided, there is still room for improvement in the adhesion of the coating, such as a significant decrease in the adhesion of the coating after the strain relief annealing. Further, in the methods disclosed in Patent Documents 4 and 5, it takes a long time to form the ceramic tension-imparting film, so that the manufacturing cost is high and the method is not yet practically used.

  The present invention has been made in view of the above-mentioned problems of the related art, and has an object of forming a tension-imparting coating having excellent adhesion on a steel sheet surface having a mirror-finished ground iron surface in a short time and at a low pressure. It is to propose a method of manufacturing a grain-oriented electrical steel sheet that can be formed at a low cost.

In order to solve the problem that the adhesion of the tension-imparting film on the mirror-finished steel sheet surface is extremely poor, the inventors have studied a method of forming an intermediate layer between the steel sheet surface and the tension-imparting film, which has been conventionally studied. As a result of intensive studies on, the following was found.
1) In order to increase the adhesion of the tension-imparting coating, it is important to increase the surface roughness of the intermediate layer.
2) In order to suppress a decrease in adhesion due to heat treatment or strain relief annealing when forming the tension imparting film, the intermediate layer is desirably an inorganic component.
3) In a wet process such as plating, a large-scale coating facility and a drying facility are required. Therefore, the dry process is more advantageous from the viewpoint of manufacturing cost.

  Therefore, on the premise of the above findings, further studies have been made on a technique for forming a tension-imparting film that can form the intermediate layer with high efficiency and low cost and that has good adhesion to the tension-imparting film. As a result, a metal powder having an average particle size of 0.1 μm or more is supplied onto the surface of the mirror-oriented grain-oriented electrical steel sheet, and the metal powder is intensively irradiated with a high energy beam such as an electron beam or a laser beam, It has been found that the above-mentioned object can be achieved by melting to form a metal intermediate layer, and the present invention has been developed.

  That is, the present invention has a metal intermediate layer having a composition different from that of the above-described substrate on a substrate of a grain-oriented electrical steel sheet subjected to a mirror finishing treatment, and a directionality having a tension imparting coating on the metal intermediate layer. A method for producing an electrical steel sheet, characterized in that a metal intermediate layer between the substrate and the tension-imparting coating is formed by melting a metal powder having an average particle diameter of 0.1 μm or more supplied to the substrate. We propose a method for manufacturing grain-oriented electrical steel sheets.

  In the method for producing a grain-oriented electrical steel sheet according to the present invention, the means for melting the metal powder is electron beam irradiation or laser beam irradiation.

  The method for producing a grain-oriented electrical steel sheet according to the present invention is characterized in that the surface roughness of the metal intermediate layer is in the range of 0.1 to 10 μm in terms of arithmetic average roughness Ra.

  According to the present invention, a metal powder having an average grain size of 0.1 μm or more is supplied to a mirror-oriented grain-oriented electrical steel sheet surface, irradiated with an electron beam, a laser beam, or the like, and is melted to form a metal having a large surface roughness. Since the intermediate layer is formed, it is possible to realize a metal intermediate layer that satisfies all of the improvement of adhesion with the tension imparting film, the reduction of manufacturing cost and the reduction of processing time, and the directional electromagnetic layer with excellent hysteresis loss. Steel plates can be manufactured at low cost.

First, an experiment on which the present invention is developed will be described.
<Experiment 1>
Etching grooves having a width of 100 μm and a depth of 25 μm are formed on one surface of a cold-rolled sheet rolled to a final sheet thickness of 0.23 mm containing Si at 3 mass% at intervals of 5 mm in the rolling direction for magnetic domain refining treatment. By performing primary recrystallization annealing also serving as decarburization, applying an annealing separator containing MgO as a main component and containing 1 mass% of antimony chloride, and performing finish annealing to have a smooth surface without a forsterite film. A grain-oriented electrical steel sheet was manufactured. In addition, the mirror finishing of the steel sheet surface is achieved by antimony chloride added to the annealing separator.

Next, the steel sheet is divided into four pieces in the length direction, and the first steel sheet is coated with a tension-imparting coating mainly composed of 60 mass% of colloidal silica and 40 mass% of magnesium phosphate while being subjected to mirror finishing. -It was baked to obtain a steel sheet 1.
The second steel sheet is coated with a 1 μm-thick TiC film using a CVD method in an atmosphere composed of a mixed gas of TiCl ₄ : 10% + H ₂ : 80% + CH ₄ : 10% in vol% ratio. After that, a tension-imparting coating mainly composed of 60 mass% of colloidal silica and 40 mass% of magnesium phosphate was applied and baked to obtain a steel sheet 2.
Further, the third steel sheet is supplied with pure Ti powder having an average particle size of 1.0 μm on a mirror-finished steel sheet surface, leveled by a roller, and then irradiates the Ti powder with an electron beam to be melted and melted. Formed a 1 μm Ti intermediate layer, and then applied and baked a tension-imparting coating containing 60 mass% of colloidal silica and 40 mass% of magnesium phosphate as a main component on the Ti intermediate layer. . The average particle size is a value measured using a laser diffraction / scattering type particle size distribution measuring device (the same applies hereinafter). The irradiation of the electron beam was performed at an output of 2 kW, and the beam deflection speed (scanning speed) was adjusted so as to obtain an appropriate input energy. The formation of the metal intermediate layer was not performed simultaneously on both sides, but was performed twice on each side.
The fourth steel sheet is supplied with pure Ti powder coated with an organic binder (acrylic binder) and having an average particle diameter of 1.0 μm on the surface of the steel sheet, leveled by a roller, and then irradiated with a laser beam to the Ti powder. Irradiation and sintering formed an intermediate layer of Ti having a thickness of 1 μm. The laser irradiation was performed at an output of 600 W, and the beam deflection speed (scanning speed) was adjusted so that the input energy became appropriate. Further, the formation of the metal intermediate layer was performed not on both sides simultaneously but on one side. Thereafter, a tension-imparting coating mainly composed of 60 mass% of colloidal silica and 40 mass% of magnesium phosphate was applied and baked to obtain a steel sheet 4.
In addition, about a part of said 4 types of steel plates, 800 degreeC x 3 hours distortion relief annealing was given after that in nitrogen atmosphere.

The magnetic properties (magnetic flux density B ₈ , iron loss W _17/50 ) of the four types of steel sheets obtained as described above were measured, and the test pieces before and after the strain relief annealing were wound around a cylinder. The minimum cylindrical diameter (bending peeling diameter (mm)) at which peeling of the coating was not observed was measured, and the adhesion of the tension-imparting coating was evaluated.
Further, for steel plates 2 to 4 having a metal intermediate layer formed on the surface of the steel plate (substrate), the thickness of the metal intermediate layer was actually measured, and the amount of metal powder used for forming the metal intermediate layer was calculated. The ratio to the amount of metal powder supplied for formation, that is, the “yield (%)” of the metal powder was determined.
The results are shown in Table 1. Table 1 also shows the processing time required to form a 1.0 μm thick metal intermediate layer on both sides of a 1 m × 1 m steel plate.

  As can be seen from Table 1 above, in the steel plates 2 and 3, the adhesion of the tension imparting film is good (the bending peeling diameter is small) and low iron loss is obtained before and after the strain relief annealing. When the tension imparting coating peels off, there are cases where it peels off at the interface between the steel sheet base and the metal intermediate layer and cases where it peels off at the metal intermediate layer and the tension insulating coating interface. Means that the adhesion at both interfaces is good. The reason why the adhesion between the tension applying film and the metal intermediate layer was good is considered to be that the surface roughness of the metal intermediate layer was larger than that of the mirror-finished steel sheet. Although both steel sheets have good iron loss characteristics and good adhesion of the tension-imparting coating, the processing time required for forming the metal intermediate layer and the yield of metal powder are greatly different. In the steel plate 2 employing the CVD method, the metal as a material is vaporized and then vapor-deposited on the surface of the steel plate. However, vapor deposition is also performed on a place other than the steel plate such as a furnace wall, so that the yield is low and the treatment is long. This requires time and increases the manufacturing cost. On the other hand, since the steel sheet 3 directly intensively inputs energy while deflecting an electron beam at a high speed to the metal powder supplied on the steel sheet and melts to form a metal intermediate layer, the metal powder is applied to portions other than the steel sheet. Since the intermediate layer was not formed, the metal intermediate layer could be formed at a high yield and in a short time. On the other hand, the steel sheet 4 is obtained by coating the surface of the metal powder with an organic binder for binding the powder and sintering, instead of melting the metal powder to form a metal intermediate layer. Poor bending peelability, the reason why low iron loss was not obtained is that the organic matter contained in the binder is decomposed during heat treatment and strain relief annealing at the time of forming a tension imparting film, and between the metal intermediate layer and the steel sheet base. It is considered that the adhesion was reduced.

<Experiment 2>
Etching grooves having a width of 50 μm and a depth of 20 μm are formed on one surface of a cold-rolled sheet rolled to a final sheet thickness of 0.20 mm containing 3 mass% of Si at 5 mm intervals in the rolling direction for a magnetic domain refining treatment. A grain-oriented electrical steel sheet having a forsterite film was manufactured by performing primary recrystallization annealing also serving as decarburization, applying an annealing separator containing MgO as a main component, and performing finish annealing. Thereafter, the grain-oriented electrical steel sheet was subjected to a mirror finishing treatment for removing a forsterite film by electrolytic polishing to obtain a grain-oriented electrical steel sheet having excellent surface smoothness.
On the surface (base) of the mirror-oriented grain-oriented electrical steel sheet obtained as described above, as shown in Table 2, pure Fe having variously changed average particle diameters in the range of 0.01 to 50 μm. After the powder was supplied and leveled using a roller, the Fe powder was directly irradiated with a laser beam and melted to form a metal intermediate layer made of pure Fe. At this time, the laser irradiation was performed under the condition of an output of 1 kW, and the beam deflection speed was adjusted so as to obtain an appropriate input energy. Further, as in Experiment 1, the metal intermediate layer was formed not on both sides simultaneously but on one side.
Thereafter, a tension-imparting coating mainly composed of 60 mass% of colloidal silica and 40 mass% of magnesium phosphate was applied and baked to obtain a product plate.

An Epstein test piece was cut out from each of the product sheets thus obtained, and the iron loss W _17/50 and the magnetic flux density B ₈ were measured. In addition, a part of the test piece was subjected to strain relief annealing at 800 ° C. for 3 hours, the bending peeling diameter before and after the strain relief annealing was measured, and the coating adhesion was evaluated. The results are shown in Table 2.

From Table 2, it can be seen that when the average particle size of the metal powder is less than 0.1 μm, the adhesion of the insulating film is poor, and the expected low iron loss is not obtained. When observing the surface of these steel sheets, the thickness uniformity of the tension-imparting film was poor, and there were also parts where the tension film was partially peeled off. Can be Before applying the tension-imparting coating, the surface roughness of the metal intermediate layer was measured by arithmetic average roughness Ra, which was very low, less than 0.1 μm, which is considered to be the cause of poor adhesion.
On the other hand, when the average particle size of the metal powder exceeds 10 μm, a tendency that iron loss is slightly deteriorated is recognized. This is because, when the average particle size is more than 10 μm, the surface roughness of the metal intermediate layer is large, so that the thickness of the tension applying film is small at the convex portions of the metal intermediate layer and thick at the concave portions, and the variation is large. Therefore, it is considered that the applied tension was also non-uniform, and the iron loss was deteriorated.
From the above results, there is a correlation between the average particle size of the metal powder and the surface roughness of the metal intermediate layer, and in order to secure the adhesion of the coating and obtain a low iron loss, it is necessary to form the metal intermediate layer. It has been found that it is preferable to use metal particles having an average particle size in the range of 0.1 to 10 μm.
The present invention has been developed based on the above new findings.

Next, a method for manufacturing a grain-oriented electrical steel sheet according to the present invention will be described.
The present invention is characterized in that a metal powder is supplied onto the surface (base) of a grain-oriented electrical steel sheet subjected to mirror finishing, and the metal powder is melted to form a metal intermediate layer having an appropriately rough surface roughness. is there. Therefore, other manufacturing conditions are not particularly limited, and a conventionally known method can be used.

  First, the preferred composition of the steel material (slab) used for producing the grain-oriented electrical steel sheet of the present invention will be described. In order to obtain a grain-oriented electrical steel sheet having excellent magnetic properties, C, Si and It is preferable to use a slab containing Mn in the following range. The method for producing steel and the method for producing slabs may be in accordance with ordinary methods, and are not particularly limited.

C: 0.01 to 0.08 mass%
C is an element necessary for improving the texture during primary recrystallization, and is preferably contained in an amount of 0.01 mass% or more in order to obtain the effect. On the other hand, when C exceeds 0.08 mass%, it becomes difficult to reduce the carbon aging to 0.0050 mass% or less at which magnetic aging does not occur by decarburizing annealing. Therefore, C is preferably set in the range of 0.01 to 0.08 mass%. More preferably, it is in the range of 0.03 to 0.07 mass%.

Si: 2.0 to 8.0 mass%
Si is an element effective for increasing the electrical resistance of the steel and improving the iron loss, but if it is less than 2.0 mass%, it is difficult to obtain a sufficient iron loss reducing effect. On the other hand, if it exceeds 8.0 mass%, the workability is remarkably reduced, and it is difficult to manufacture by rolling, and the magnetic flux density tends to be reduced. Therefore, Si is preferably set in the range of 2.0 to 8.0 mass%.
More preferably, it is in the range of 2.5 to 4.0 mass%.

Mn: 0.005 to 1.0 mass%
Mn is an element effective for improving hot workability, but if the content is less than 0.005 mass%, the above effect cannot be obtained. On the other hand, if the content exceeds 1.0 mass%, the magnetic flux density decreases. Become. Therefore, Mn is preferably in the range of 0.005 to 1.0 mass%. More preferably, it is in the range of 0.01 to 0.2 mass%.

Further, the basic components other than the above components of the steel material used for manufacturing the grain-oriented electrical steel sheet of the present invention are classified into a case where an inhibitor is used to cause secondary recrystallization and a case where the inhibitor is not used.
In the case where an inhibitor is used to cause secondary recrystallization, for example, when an AlN-based inhibitor is used, Al and N are respectively Al: 0.01 to 0.065 mass% and N: 0.005 to 0.5%. It is preferable to contain manganese in a range of 012 mass%. When a MnS · MnSe-based inhibitor is used, Se and / or S are respectively S: 0.005 to 0.03 mass% and Se: 0.005 to 0.5 mass%. It is preferable to contain it in the range of 03 mass%.

  On the other hand, when the inhibitor is not used to cause secondary recrystallization, Al, N, S, and Se, which are inhibitor-forming components, have Al: 0.0100 mass% or less, N: 0.0050 mass% or less, respectively. Preferably, S is reduced to 0.0050 mass% or less, and Se is reduced to 0.0050 mass% or less.

The steel material used for producing the grain-oriented electrical steel sheet of the present invention may further include Ni: 0.03 to 1.50 mass in addition to the basic components described above, for the purpose of improving magnetic properties, in addition to the above-described component composition. %, Sn: 0.01 to 1.50 mass%, Sb: 0.005 to 1.50 mass%, Cu: 0.03 to 3.0 mass%, P: 0.03 to 0.50 mass%, Mo: 0. One or two or more selected from 005 to 0.10 mass% and Cr: 0.03 to 1.50 mass% may be contained.
Ni is an element useful for improving the hot rolled sheet structure and improving the magnetic properties. However, when the content is less than 0.03 mass%, the above effect is small. On the other hand, when the content exceeds 1.50 mass%, the secondary recrystallization becomes unstable and the magnetic characteristics are deteriorated. Further, Sn, Sb, Cu, P, Mo and Cr are useful elements for improving the magnetic properties, but when all of them are less than the above lower limits, the effect of improving the magnetic properties is small. If it exceeds, the development of the secondary recrystallized grains is hindered.

  In the steel material used for manufacturing the grain-oriented electrical steel sheet of the present invention, the balance other than the above components is Fe and inevitable impurities. Since C is decarburized by primary recrystallization annealing and Al, N, S and Se are purified in finish annealing, these components are reduced to a content of inevitable impurities in the steel sheet after finish annealing. You.

Next, a method of manufacturing a grain-oriented electrical steel sheet using a steel material (slab) having the above component composition will be described.
The slab whose component composition has been adjusted to the appropriate range is then reheated to a predetermined temperature according to a conventional method, hot-rolled, and if necessary, subjected to hot-rolled sheet annealing, and once or twice with intermediate annealing. The above cold rolling is performed to obtain a cold-rolled sheet having a final thickness, and thereafter, the above-mentioned cold-rolled sheet is subjected to primary recrystallization annealing also serving as decarburization, and after applying an annealing separating agent, is subjected to secondary recrystallization and purification. For a grain-oriented electrical steel sheet. The decarburization can be performed by setting the primary recrystallization annealing to a wet atmosphere, but may be performed separately.

The grain-oriented electrical steel sheet of the present invention is required to have a mirror-finished (smoothed) surface, but as a means for achieving the mirror-finish, a conventional forsterite film is formed. It may be performed by applying mechanical polishing, chemical polishing, electrolytic polishing, or the like, or an annealing separator that does not form a forsterite film, for example, Li, Na, K, Mg, Ca, Sr, Ba, Annealing separating agent to which chlorides, oxides or hydroxides such as Fe, Ni, Sn, Sb and Bi are added, or annealing in which the ratio of MgO is reduced and the ratio of Al ₂ O ₃ or CaSiO ₃ is increased. A separating agent or the like may be used. Even when an annealing separator that does not form a forsterite film is used, mechanical polishing, chemical polishing, electrolytic polishing, or the like may be further performed to further improve smoothness.

In the case of the purification annealing after the secondary recrystallization annealing in the finish annealing, when an inhibitor is used to cause secondary recrystallization, the maximum temperature must be 1100 ° C. or higher. Is preferably 3 hours or more. If the temperature is lower than 1100 ° C., the precipitate cannot be decomposed and diffused to the surface of the steel sheet, so that sufficient purification cannot be obtained.
On the other hand, when the inhibitor is not used for the secondary recrystallization, purification annealing is not always necessary if nitrogen and the like can be sufficiently reduced. However, in order to form a good forsterite film, high-temperature annealing at 1100 ° C. or more is required. Is preferably applied.

Next, a method for forming the metal intermediate layer will be described.
Metal powder is used as a material for forming the metal intermediate layer. The metal powder is not particularly limited, and powders having a wide range of component compositions such as pure metals such as Fe, Ti, Al, Ni, and Co and alloys thereof can be used. These metal powders may be used alone or as a mixture of a plurality of types of powders.

  It is preferable to use a high energy beam such as an electron beam or a laser beam as a means for inputting thermal energy for melting the metal powder. With these means, thermal energy can be intensively applied to the metal powder while suppressing the input of thermal energy to the material, so that even a metal having a higher melting point than the material can be formed as an intermediate layer. Because you can do it. The amount of thermal energy to be input may be determined as appropriate while adjusting the beam output and the scanning speed.

  The supply and melting of the metal powder to the surface of the steel sheet may be performed by supplying the metal powder to the surface of the steel sheet from a nozzle or the like, uniformly spreading the powder using a roller, a blade, or the like, and then performing the melting treatment by the above-described means. Then, a method may be adopted in which the metal powder is supplied to the beam irradiation part on the steel plate while irradiating the high energy beam, and the supply and the melting are simultaneously performed. Compared with the so-called "spraying" that sprays the melted metal powder, in the case of spraying, the particle density in the spraying range is not uniform, so there is a problem in forming a uniform coating, and the metal powder is uniformly supplied on the steel sheet surface According to the present technology, it is easier to form a uniform coating. Furthermore, in the present technology, since the material is directly supplied onto the steel plate, it is advantageous in terms of yield.

The thickness of the metal intermediate layer formed on the surface of the steel sheet may be controlled by adjusting the supply amount of powder (thickness when laying down, injection amount when irradiating), but is in the range of 0.05 to 5.0 μm. Is preferred.
As described above, the average particle size of the metal powder is preferably 0.1 μm or more from the viewpoint of ensuring adhesion, and is preferably 10 μm or less from the viewpoint of ensuring magnetic characteristics.
The point is that the metal intermediate layer of the present invention is formed by melting metal powder. This is because, when the surface of the metal powder is coated with an organic binder and sintered to form an intermediate layer, the presence of the organic substance deteriorates the adhesion of the coating.

  The grain-oriented electrical steel sheet having the metal intermediate layer formed on the surface (base) of the steel sheet may be thereafter coated with a known tension-imparting coating (insulating coating) by a known method. For example, colloidal silica, A tension-imparting coating made of a phosphate such as magnesium phosphate or aluminum phosphate can be suitably used. The application and baking of the tension imparting film may be performed in the same step as the flattening annealing after the finish annealing or in another step.

  The steel sheet on which the tension-imparting coating is formed as described above may be further subjected to a magnetic domain refining treatment by irradiating an electron beam, a laser, a plasma flame, or the like for the purpose of further reducing iron loss. Further, at an optional stage of the manufacturing process, grooves may be formed at regular intervals on the surface of the steel sheet by using etching, a toothed roll, or the like, and magnetic domain refinement may be performed.

C: 0.05 mass%, Si: 3.0 mass%, Mn: 0.02 mass%, Al: 0.02 mass%, N: 0.01 mass%, S: 0.005 mass%, and Se: 0.01 mass%. A steel slab having a component composition and containing an inhibitor-forming component was hot-rolled and cold-rolled into a cold-rolled sheet having a final thickness of 0.23 mm according to a conventional method, and then decarburized according to a conventional method. After performing a primary recrystallization annealing and applying an annealing separator containing MgO as a main component, a finish annealing including a secondary recrystallization annealing and a purification annealing in which a soaking temperature is maintained at 1200 ° C. for 10 hours is applied to the steel sheet surface. A grain-oriented electrical steel sheet having a forsterite coating. Next, the surface of the grain-oriented electrical steel sheet was subjected to a mirror finishing treatment for removing a forsterite film by electrolytic polishing. In addition, about a part of said grain-oriented electrical steel sheet, it did not perform a mirror-finish process and it had a forsterite film, and it was set as the comparative material.
Next, various metal powders are supplied to the entire surface of the steel sheet surface on the surface of the mirror-oriented grain-oriented electrical steel sheet, and after leveling with a roller, the beam is applied to the metal powder so as to have an appropriate input energy. While adjusting the deflection speed, the electron beam was irradiated at an output of 6 kW to melt the metal powder and form a metal intermediate layer. Table 3 shows the types of metal powder used for forming the intermediate layer, the average particle size thereof, and the processing required to form a metal intermediate layer having a thickness of 1.0 μm in an area of 1 m × 1 m. The time (electron beam irradiation time) is shown.
Thereafter, a tension-imparting coating mainly composed of 60% of colloidal silica and 40% of magnesium phosphate was applied and baked on the metal intermediate layer to obtain a product plate.
An Epstein test piece was cut out from each of the product sheets thus obtained, subjected to strain relief annealing at 820 ° C. × 3 Hr, and then subjected to the measurement of iron loss W _17/50 , magnetic flux density B ₈ and bending peeling diameter for evaluating coating adhesion. The measurement was performed, and the results are shown in Table 3. In addition, the same measurement was performed on the comparative material having the forsterite film, and the results are shown in Table 3.

  Table 3 shows that a metal intermediate layer was formed on a mirror-polished surface of a conventional grain-oriented electrical steel sheet (No. 1) having a forsterite coating using various metal powders under conditions compatible with the present invention. All of the grain-oriented electrical steel sheets (Nos. 2 to 8) can form a metal intermediate layer in a high yield and in a short time. It can be seen that in addition to having the same level of film adhesion as that of No. 1, it also has good iron loss characteristics.

Using the same steel slab as in Example 1, hot-rolled according to a conventional method and cold-rolled to obtain a cold-rolled sheet having a final thickness of 0.27 mm, and then primary recrystallization combined with decarburization according to a conventional method. After annealing and applying an annealing separator containing MgO as a main component and 1 mass% of antimony chloride added thereto, a secondary recrystallization annealing and a finish annealing including a purification annealing in which a soaking temperature of 1200 ° C. is maintained for 10 hours are applied. The grain-oriented electrical steel sheet had a smooth surface without a forsterite film.
Next, while irradiating the laser beam onto the surface of the mirror-oriented grain-oriented electrical steel sheet, metal powder is continuously injected into a laser beam irradiation area from a nozzle arranged around the laser beam, and the heat of the laser beam is increased. To melt the metal powder to form a metal intermediate layer. Table 4 shows the types and average particle diameters of the metal powders used for forming the intermediate layer.
Then, after applying and baking a tension-imparting coating containing 60 mass% of colloidal silica and 40 mass% of magnesium phosphate as main components on the metal intermediate layer, a magnetic domain in which electron beam irradiation is performed at intervals of 4 mm in the rolling direction. The product plate was subjected to the subdivision treatment. As a comparative material, a grain-oriented electrical steel sheet having a forsterite film was prepared by a conventional method, and the same measurement was performed.

  From Table 4, when the average particle size of the metal powder is within the range of the present invention, the comparative material No. In contrast to No. 1, it has excellent iron loss characteristics while having the same level of film adhesion. In particular, it can be seen that, even within the scope of the present invention, a metal powder having an average particle size of 0.1 to 10 μm has the best iron loss characteristics.

Claims (1)

A method for producing a grain-oriented electrical steel sheet having a metal intermediate layer having a composition different from that of the above-described base material, and having a tension-imparting coating on the metal intermediate layer, on a substrate of a grain-oriented electrical steel sheet subjected to a mirror finishing treatment. So,
The metal intermediate layer between the substrate and the tension-imparting coating is formed by irradiating an electron beam or a laser beam to a metal powder having an average particle diameter of 0.1 μm or more supplied to the substrate and melting the metal powder. A method for producing a grain- oriented electrical steel sheet, wherein the surface roughness of the intermediate layer is in the range of 0.1 to 10 μm in arithmetic average roughness Ra .