technical field
[One]
It relates to an electrical steel sheet and a method for manufacturing the same. More specifically, it relates to an electrical steel sheet having improved insulation properties and adhesion with an insulating coating layer by partially remaining scale present on the surface of the hot-rolled sheet after manufacturing the hot-rolled sheet, and a method for manufacturing the same.
background
[2]
Electrical steel sheet is a product used as a material for transformers, motors, and electric machines, and is a functional product that places importance on electrical properties, unlike general carbon steel that emphasizes processability such as mechanical properties. Required electrical properties include low iron loss, high magnetic flux density, magnetic permeability and space factor.
[3]
Electrical steel sheet is further divided into grain-oriented electrical steel sheet and non-oriented electrical steel sheet. Grain-oriented electrical steel sheet is an electrical steel sheet with excellent magnetic properties in the rolling direction by forming a Goss texture ({110}<001> texture) throughout the steel sheet by using an abnormal grain growth phenomenon called secondary recrystallization. Non-oriented electrical steel sheet is an electrical steel sheet with uniform magnetic properties in all directions on the rolled sheet.
[4]
As a production process of non-oriented electrical steel sheet, after manufacturing a slab, an insulating coating layer is formed through hot rolling, cold rolling and final annealing.
[5]
As a production process of grain-oriented electrical steel sheet, after manufacturing a slab, an insulating coating layer is formed through hot rolling, cold rolling, primary recrystallization annealing, and secondary recrystallization annealing.
[6]
In the production process of electrical steel sheet, it was common to improve the efficiency of the subsequent process by removing the scale generated on the surface after hot rolling.
[7]
However, a large amount of Fe is present on the surface of the steel sheet after pickling, and the bonding force with the OH and O functional groups does not significantly act on the surface of the steel sheet. When an insulating coating layer containing an oxide composed of O and OH components is formed on such a surface, there are problems in that the insulating coating layer is not formed uniformly and the adhesion between the steel sheet and the insulating coating layer is deteriorated.
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[8]
An electrical steel sheet and a manufacturing method thereof are provided. More specifically, the present invention provides an electrical steel sheet having improved insulating properties and adhesion with an insulating coating layer by partially remaining scale present on the surface of the hot-rolled sheet after manufacturing the hot-rolled sheet, and a method for manufacturing the same.
means of solving the problem
[9]
An electrical steel sheet manufacturing method according to an embodiment of the present invention comprises the steps of: manufacturing a hot-rolled sheet by hot-rolling a slab; removing some of the scale formed on the hot-rolled sheet and leaving a scale layer having a thickness of 10 nm or more; controlling the roughness of the hot-rolled sheet on which the scale layer remains; manufacturing a cold rolled sheet by cold rolling; and annealing the cold-rolled sheet.
[10]
Slab in wt%, C: 0.1% or less, Si: 6.0% or less, P: 0.5% or less, S: 0.005% or less, Mn: 1.0% or less, Al: 2.0% or less, N: 0.005% or less, Ti: 0.005% or less, Cr: 0.5% or less, and may contain Fe and unavoidable impurities as the balance.
[11]
The scale may include Si: 5 to 80% by weight, O: 5 to 80% by weight, and the balance Fe and unavoidable impurities.
[12]
In the step of the remaining scale, the amount of the particles used to blast method the steel sheet per unit area 20g / m 3 to 1000g / m 3 speed of the particles may be treated with 0.1 km / s to 200km / s.
[13]
In the step of controlling the roughness of the hot-rolled sheet, the roughness may be controlled to 0.1 to 2.0 nm.
[14]
Controlling the roughness of the hot-rolled sheet may include passing the hot-rolled sheet between blades coated with rubber.
[15]
The elasticity of the rubber may be 7 to 45 Mpa.
[16]
After the step of controlling the roughness of the hot-rolled sheet, the step of pickling may be further included.
[17]
The pickling step may be immersion in an acid solution of 15 wt% or less for 20 to 70 seconds.
[18]
After the step of manufacturing the cold-rolled sheet, the thickness of the scale layer may be 1 to 100 nm.
[19]
After the step of manufacturing the cold-rolled sheet, the roughness of the scale layer may be 0.01 to 0.5 nm.
[20]
The electrical steel sheet according to an embodiment of the present invention includes an electrical steel sheet substrate and a scale layer present in an inward direction from the surface of the electrical steel sheet substrate, and the thickness of the scale layer may be 1 to 100 nm.
[21]
The scale layer may include Si: 5 to 80% by weight, O: 5 to 80% by weight, and the remainder Fe and unavoidable impurities.
[22]
The scale layer may have a roughness of 0.01 to 0.5 nm.
[23]
An insulating coating layer positioned on the scale layer may be further included.
Effects of the Invention
[24]
According to one embodiment of the present invention, by forming a firm bond between the insulating coating layer and the scale layer, it is possible to improve adhesion with the insulating coating layer.
[25]
In addition, according to an exemplary embodiment of the present invention, since the scale layer itself has an insulating property, the insulating property can be improved.
[26]
In addition, according to one embodiment of the present invention, when the hot-rolled coil is in the standby state, oxidation of the hot-rolled sheet from oxygen in the air can be prevented.
Brief description of the drawing
[27]
1 is a schematic diagram of a cross-section of an electrical steel sheet according to an embodiment of the present invention.
[28]
2 is a scanning electron microscope (SEM) photograph of a cross-section of a steel sheet after pickling in Examples.
[29]
Figure 3 is a scanning electron microscope (SEM) photograph of the surface of the steel sheet after pickling in Example.
[30]
4 is a scanning electron microscope (SEM) photograph of a cross-section of a steel sheet after hot rolling in a comparative example.
[31]
5 is a scanning electron microscope (SEM) photograph of the surface of the steel sheet after hot rolling in Comparative Example.
[32]
6 is a scanning electron microscope (SEM) photograph of a cross section of a steel sheet after cold rolling in Example.
[33]
7 is a scanning electron microscope (SEM) photograph of a cross-section of a steel sheet after cold rolling in Example.
Modes for carrying out the invention
[34]
Terms such as first, second and third are used to describe, but are not limited to, various parts, components, regions, layers and/or sections. These terms are used only to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Accordingly, a first part, component, region, layer or section described below may be referred to as a second part, component, region, layer or section without departing from the scope of the present invention.
[35]
The terminology used herein is for the purpose of referring to specific embodiments only, and is not intended to limit the present invention. As used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite. As used herein, the meaning of "comprising" specifies a particular characteristic, region, integer, step, operation, element and/or component, and the presence or absence of another characteristic, region, integer, step, operation, element and/or component. It does not exclude additions.
[36]
When a part is referred to as being “on” or “on” another part, it may be directly on or on the other part, or the other part may be involved in between. In contrast, when a part refers to being “directly above” another part, the other part is not interposed therebetween.
[37]
In addition, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %.
[38]
In an embodiment of the present invention, the meaning of further including the additional element means that the remaining iron (Fe) is included by the additional amount of the additional element.
[39]
Although not defined otherwise, all terms including technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Commonly used terms defined in the dictionary are further interpreted as having a meaning consistent with the related technical literature and the presently disclosed content, and unless defined, are not interpreted in an ideal or very formal meaning.
[40]
Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein.
[41]
An electrical steel sheet manufacturing method according to an embodiment of the present invention comprises the steps of: manufacturing a hot-rolled sheet by hot-rolling a slab; removing some of the scale formed on the hot-rolled sheet and leaving a scale layer having a thickness of 10 nm or more; controlling the roughness of the hot-rolled sheet on which the scale layer remains; manufacturing a cold rolled sheet by cold rolling; and annealing the cold-rolled sheet.
[42]
Hereinafter, each step will be described in detail.
[43]
First, a hot-rolled sheet is manufactured by hot-rolling a slab.
[44]
The alloy component of the slab is not particularly limited, and all alloy components used in the electrical steel sheet can be used. For example, the slab is in weight%, C: 0.1% or less, Si: 6.0% or less, P: 0.5% or less, S: 0.005% or less, Mn: 1.0% or less, Al: 2.0% or less, N: 0.005% or less, Ti: 0.005% or less, Cr: 0.5% or less, and may include Fe and unavoidable impurities as the balance.
[45]
First, the slab is heated. The heating temperature of the slab is not limited, but when the slab is heated to a temperature of 1300° C. or less, coarse growth of the columnar structure of the slab is prevented, thereby preventing the occurrence of cracks in the plate in the hot rolling process. Therefore, the heating temperature of the slab may be 1050 ℃ to 1300 ℃.
[46]
Next, the slab is hot-rolled to manufacture a hot-rolled sheet. The hot rolling temperature is not limited, and in one embodiment, the hot rolling may be terminated at 950 ° C.
[47]
Next, some of the scale formed on the hot-rolled sheet is removed, and the scale of 10 nm or more remains.
[48]
Since hot rolling is performed at a high temperature, scale is inevitably generated on the surface of the hot-rolled sheet. This scale adversely affects magnetism, and fracture occurs during rolling, so it is common to remove all of it.
[49]
In one embodiment of the present invention, by intentionally remaining the scale layer to a thickness of 10 nm or more, adhesion with the insulating coating layer is improved, and additional insulating properties can be obtained. Scale has a smaller Fe content than a steel plate substrate, but a relatively high Si content, so OH and O components and bonding strength are greatly affected. Therefore, when the insulating coating layer is formed, the insulating coating layer is uniformly formed, and adhesion is improved.
[50]
In addition, the scale has an O content higher than that of the steel plate substrate, and thus provides insulating properties by itself.
[51]
Specifically, the scale may include Si: 5 to 80% by weight, O: 5 to 80% by weight, and the remainder Fe and unavoidable impurities. More specifically, the scale may include Si: 10 to 60% by weight, O: 10 to 60% by weight, and the balance Fe and unavoidable impurities. More specifically, the scale may include Si: 15 to 40% by weight, O: 15 to 40% by weight, and the balance Fe and unavoidable impurities.
[52]
The method of leaving the scale is not particularly limited. For example, it may be processed using a blast method. The blast method is a method of removing scale by colliding fine particles with a steel plate at high speed. At this time, the amount of steel particles per unit area 20g / m 3 to 1000g / m 3 speed of the particles may be 0.1 km / s to 200km / s. More specifically, the amount of steel particles per unit area 100g / m 3 to about 750g / m 3 speed of the particles may be 1 km / s to 100km / s.
[53]
Compared to the existing blasting method that removes all scale, the input amount and speed of fine particles is small. As such, the scale may be left to an appropriate thickness by the blasting method described above. If it is larger or smaller than the above range, the scale of an appropriate thickness may not remain.
[54]
In an embodiment of the present invention, the thickness of the remaining scale is 10 nm or more. The thickness of the scale may be non-uniform across the entire steel plate, and unless otherwise specified, the thickness of the scale means the average thickness of the entire surface of the steel plate. If the scale thickness remains too thick, it may adversely affect magnetism. Accordingly, the thickness of the remaining scale may be 10 nm to 300 nm. More specifically, the thickness of the remaining scale may be 30 to 150 nm.
[55]
Next, the roughness of the hot-rolled sheet in which the scale remains is controlled. In this case, the roughness of the hot-rolled sheet means the roughness of the outermost surface of the hot-rolled sheet, that is, the roughness of the scale. When the scale remains, the illuminance becomes very large. This adversely affects the magnetism. Therefore, it is necessary to control only the illuminance without removing the scale.
[56]
In an embodiment of the present invention, the illuminance of the hot-rolled sheet may be controlled to 0.1 to 2.0 nm through illuminance control. If the illuminance is too high, it may adversely affect magnetism. Conversely, if you try to control the illuminance too low, a problem in which all scale is removed may occur. Therefore, it is possible to control the illuminance within the above-described range. More specifically, the illuminance may be controlled to 1.0 to 1.5 nm.
[57]
As a method of controlling the roughness, it may include passing the hot-rolled sheet between blades coated with rubber.
[58]
At this time, the elasticity of the rubber may be 7 to 45 Mpa. When the elasticity is not appropriate, it may be difficult to control the illuminance.
[59]
After the step of controlling the roughness of the hot-rolled sheet, the step of pickling may be further included. The roughness of the hot-rolled sheet can be further controlled through pickling. During pickling, if the concentration of the acid solution is high or the immersion time is long, a problem in which all the scale is removed may occur. Therefore, it can be immersed in an acid solution of 15 wt% or less for 20 to 70 seconds.
[60]
Next, a hot-rolled sheet is cold-rolled, and a cold-rolled sheet is manufactured. It may be applied differently depending on the thickness of the hot-rolled sheet, but cold rolling may be performed to a final thickness of 0.2 to 0.65 mm by applying a reduction ratio of 70 to 95%. Cold rolling may be performed by one cold rolling or by performing two or more cold rollings with intermediate annealing therebetween as needed.
[61]
In the cold rolling process, the scale layer is also rolled, so that the thickness is reduced. After cold rolling, the thickness of the scale layer may be 1 to 100 nm. More specifically, it may be 5 to 20 nm.
[62]
Next, the cold-rolled sheet is annealed. At this time, the annealing process of the cold-rolled sheet is different depending on the use of the non-oriented electrical steel sheet or the grain-oriented electrical steel sheet.
[63]
Specifically, when manufacturing a non-oriented electrical steel sheet, it can be annealed for 30 seconds to 3 minutes at a temperature of 850 to 1050 ℃. If the cracking temperature is too high, rapid growth of crystal grains may occur, which may lower magnetic flux density and high-frequency iron loss. More specifically, the final annealing may be performed at a soaking temperature of 900 to 1000°C. In the final annealing process, all (ie, 99% or more) of the processed structure formed in the cold rolling step, which is the previous step, may be recrystallized.
[64]
In the case of manufacturing grain-oriented electrical steel sheet, the cold-rolled cold-rolled sheet is subjected to primary recrystallization annealing. In the primary recrystallization annealing step, primary recrystallization occurs in which Goss grain nuclei are generated. In the primary recrystallization annealing process, decarburization and nitridation of the steel sheet may be performed. For decarburization and nitridation, primary recrystallization annealing can be performed under a mixed gas atmosphere of steam, hydrogen and ammonia.
[65]
For nitriding, nitrogen ions are introduced into the steel sheet using ammonia gas for nitriding to form nitrides such as (Al, Si, Mn)N and AlN, which are tin extracts. There is no problem in exhibiting the effects of the present invention in either method of performing nitriding treatment at the same time, or performing decarburization after performing nitriding treatment in advance so that they can be used together.
[66]
Primary recrystallization annealing may be carried out in a temperature range of 800 to 900 ℃.
[67]
Next, the secondary recrystallization annealing is performed on the cold-rolled sheet on which the primary recrystallization annealing has been completed. At this time, after the annealing separator is applied to the cold-rolled sheet on which the primary recrystallization annealing has been completed, secondary recrystallization annealing may be performed. At this time, the annealing separator is not particularly limited, and an annealing separator containing MgO as a main component may be used.
[68]
The purpose of secondary recrystallization annealing is broadly to form a {110}<001> texture by secondary recrystallization, to provide insulation by forming a glassy film by the reaction between the oxide layer formed during decarburization and MgO, and to remove impurities that impair magnetic properties. . As a method of secondary recrystallization annealing, in the temperature rising section before secondary recrystallization occurs, a mixed gas of nitrogen and hydrogen is maintained to protect nitride, which is a grain growth inhibitor, so that secondary recrystallization is well developed. % Maintain in a hydrogen atmosphere for a long time to remove impurities.
[69]
Then, the step of forming an insulating coating layer may be further included. Except for forming a thin thickness, the insulating layer may be formed using a general method. Since the method for forming the insulating coating layer is widely known in the field of electrical steel sheet technology, detailed description thereof will be omitted.
[70]
1 schematically shows a cross section of an electrical steel sheet 100 according to an embodiment of the present invention. Referring to Figure 1, the structure of the electrical steel sheet according to an embodiment of the present invention will be described. The electrical steel sheet of FIG. 1 is only for illustrating the present invention, and the present invention is not limited thereto. Therefore, the structure of the electrical steel sheet can be variously modified.
[71]
As shown in FIG. 1 , the electrical steel sheet 100 according to an embodiment of the present invention includes a scale layer 20 present in an inward direction from the surface of the electrical steel sheet substrate 10 . By including the scale layer 20 as described above, a firm bond between the insulating coating layer 30 and the scale layer 20 may be formed, and adhesion with the insulating coating layer 30 may be improved. In addition, since the scale layer 20 itself has an insulating property, it is possible to improve the insulating property.
[72]
Hereinafter, each configuration will be described in detail.
[73]
First, the electrical steel sheet substrate 10 may use all alloy components used in the electrical steel sheet. As an example, the electrical steel sheet substrate 10 is, by weight, C: 0.1% or less, Si: 6.0% or less, P: 0.5% or less, S: 0.005% or less, Mn: 1.0% or less, Al: 2.0% or less, N : 0.005% or less, Ti: 0.005% or less, Cr: 0.5% or less, and may contain Fe and unavoidable impurities as the balance.
[74]
The scale layer 20 is present in an inward direction from the surface of the electrical steel sheet substrate 10 . The thickness of the scale layer 20 may be 1 to 100 nm. More specifically, it may be 5 to 20 nm. If the scale layer 20 is too thin, it is difficult to properly obtain the effect of improving adhesion and insulating properties with the insulating coating layer 30 generated due to the presence of the scale layer 20 described above. In addition, if the scale layer 20 is too thick, it may adversely affect the magnetism. Accordingly, the thickness of the scale layer 20 may be 1 to 100 nm. More specifically, it may be 5 to 20 nm.
[75]
The scale layer 20 may include Si: 5 to 80 wt%, O: 5 to 80 wt%, and the remainder Fe and unavoidable impurities. More specifically, the scale may include Si: 10 to 60% by weight, O: 10 to 60% by weight, and the balance Fe and unavoidable impurities. More specifically, the scale may include Si: 15 to 40% by weight, O: 15 to 40% by weight, and the balance Fe and unavoidable impurities.
[76]
The scale layer 20 has less Fe content than the electrical steel sheet base 10, but has a relatively high Si content, so that the OH and O components and bonding force act greatly. Therefore, when the insulating coating layer 30 is formed, the insulating coating layer 30 is uniformly formed, and adhesion is improved. In addition, the scale layer 20 has an O content higher than that of the electrical steel sheet base 10 , and thus provides insulating properties by itself.
[77]
In FIG. 1 , the surface of the scale layer 20 (ie, the interface between the scale layer 20 and the insulating coating layer 30 ) is expressed as flat, but it is substantially rough as shown in FIG. 6 . The scale layer 20 may have a roughness of 0.01 to 0.5 nm. If the illuminance is too high, it may adversely affect magnetism. Conversely, when trying to control the illuminance too low, a problem in which the scale layer 20 is all removed may occur. Therefore, it is possible to control the illuminance of the scale layer 20 within the above-described range.
[78]
As shown in FIG. 1 , an insulating coating layer 30 may be further formed on the scale layer 20 . In one embodiment of the present invention, since the scale layer 20 is properly formed, the adhesion of the insulating coating layer 30 can be improved, and sufficient insulation can be secured even when the thickness of the insulating coating layer 30 is formed thin. . Specifically, the thickness of the insulating coating layer 30 may be 0.7 to 1.0 ㎛. Since the insulating coating layer 30 is widely known in the field of electrical steel sheet technology, a detailed description thereof will be omitted.
[79]
Hereinafter, the present invention will be described in more detail through examples. However, these examples are only for illustrating the present invention, and the present invention is not limited thereto.
[80]
Example
[81]
3.4 wt% of silicon (Si), and the balance was prepared as a slab consisting of Fe and other unavoidable impurities.
[82]
The slab was heated at 1130° C. and then hot-rolled to a thickness of 2.3 mm to prepare a hot-rolled sheet.
[83]
The hot-rolled sheet was controlled at a fine particle input amount of about 650 g/m 3 , and an input speed of about 50 km/s using a shot blaster, leaving a scale layer with a thickness of about 100 nm. After that, the surface roughness was controlled to about 1.5 nm by passing between the blades coated with a rubber with an elasticity of about 30 Mpa. Then, it was immersed for about 50 seconds in a hydrochloric acid solution (about 15 wt%) at a temperature of about 70 ° C. Thereafter, washing was performed.
[84]
2 shows a scanning electron microscope (SEM) photograph of a cross section of a steel sheet after pickling. As shown in FIG. 2 , the scale layer is displayed as a white part, and it can be confirmed that the scale layer remains.
[85]
3 shows a scanning electron microscope (SEM) photograph of the surface of the steel sheet after pickling. As shown in FIG. 3 , it can be seen that the feather-shaped scale layer covers the surface of the steel sheet.
[86]
After that, cold rolling was performed to make the plate thickness 0.25 mm, and final annealing was performed. A cross-section of the steel plate is shown in FIGS.
[87]
As shown in FIGS. 6 and 7 , it can be confirmed that the scale layer remains after cold rolling and final annealing.
[88]
It was confirmed that the scale layer was about 50 nm thick and the roughness was about 0.1 nm. In addition, the alloy component of the scale layer was analyzed by TEM-FIB. It was confirmed that Si:35.25% by weight, O: 34.02% by weight, and the remainder Fe and impurities.
[89]
In addition, it was confirmed that the area fraction of the scale in the area of ​​2 μm × 2 μm was 30% or more.
[90]
Comparative Example 1
[91]
3.4 wt% of silicon (Si), and the balance was prepared as a slab consisting of Fe and other unavoidable impurities.
[92]
The slab was heated at 1130° C. and then hot-rolled to a thickness of 2.3 mm to prepare a hot-rolled sheet.
[93]
The hot-rolled sheet was controlled at a fine particle input amount of 1300 g/m 3 and an input speed of 50 km/s using a Shot Blaster, and all scale layers were removed. Then, it was immersed in a hydrochloric acid solution (about 30 wt%) at a temperature of about 80° C. for about 100 seconds to carry out pickling treatment. Thereafter, washing was performed.
[94]
4 shows a scanning electron microscope (SEM) photograph of a cross section of a steel sheet after pickling. As shown in FIG. 4 , it can be confirmed that the scale layer is all removed.
[95]
5 shows a scanning electron microscope (SEM) photograph of the surface of the steel sheet after pickling. As shown in FIG. 5 , there is no feather-shaped scale layer, and only scratches are observed on the steel plate.
[96]
After that, cold rolling was performed to make the plate thickness 0.25 mm, and final annealing was performed.
[97]
In addition, it was confirmed that the area fraction of the scale was 10% in the area of ​​2 μm × 2 μm.
[98]
Comparative Example 2
[99]
3.4 wt% of silicon (Si), and the balance was prepared as a slab consisting of Fe and other unavoidable impurities.
[100]
The slab was heated at 1130° C. and then hot-rolled to a thickness of 2.3 mm to prepare a hot-rolled sheet.
[101]
The hot-rolled sheet was controlled at a fine particle input amount of about 80 g/m 3 and an input speed of about 50 km/s using a Shot Blaster, leaving a scale layer with a thickness of about 500 nm. Then, it was immersed for about 50 seconds in a hydrochloric acid solution (about 15 wt%) at a temperature of about 70 ° C. Thereafter, washing was performed. After that, cold rolling was performed to make the plate thickness 0.25 mm, and final annealing was performed. A scale layer of about 250 nm was confirmed after cold rolling.
[102]
Experimental Example 1: Confirmation of rust generation
[103]
After pickling and cleaning of the hot-rolled sheet in Examples and Comparative Examples, the hot-rolled sheet was wound up before cold rolling and left for the time shown in Table 1 below.
[104]
The gloss was measured at two points and shown in Table 1 below. Gloss was expressed as the ratio of the intensity of the light when the reflected light was received at the same angle as the incident light using the ASTM D 523 gloss meter, and the gloss of the glass surface with a refractive index of 1.567 was set to 100. At this time, the angle was set to 60 °.
[105]
[Table 1]
[106]
As shown in Table 1, the Example in which the scale layer was present immediately after washing had inferior gloss compared to the Comparative Example. However, after 1 day and 2 days, it can be seen that the Example prevents rust from being generated by the scale layer, whereas the Comparative Example shows rust, which significantly lowers the gloss.
[107]
Experimental Example 2: Insulation measurement
[108]
After the final annealing in Examples and Comparative Examples, the insulation properties of the steel sheet were measured at 3 points and shown in Table 2 below. In addition, after forming an insulating coating layer with a thickness of 1 μm, insulation properties were measured and shown in Table 2 below. Insulation properties were measured using a Franklin measuring instrument in accordance with ASTM A717 international standard.
[109]
In addition, adhesiveness was judged by the presence or absence of film peeling when the specimen was bent by 180 degrees. When observing under a microscope x100, if there is none at all, it is very good, and x100 with 3 or less defects /5cmx5cm is marked as good.
[110]
The iron loss (W 15/50 ) refers to the power loss that occurs when a magnetic field with a frequency of 50 Hz is magnetized up to 1.5 Tesla.
[111]
[Table 2]
[112]
As shown in Table 2, it can be confirmed that the example in which the scale layer is present has superior insulating properties and improved adhesion compared to Comparative Example 1. Furthermore, it can be confirmed that the iron loss is also improved. It can be seen that Comparative Example 2, in which too much of the scale layer remains, has very poor iron loss.
[113]
The present invention is not limited to the embodiments, but can be manufactured in various different forms, and those of ordinary skill in the art to which the present invention pertains can use other specific forms without changing the technical spirit or essential features of the present invention. It will be appreciated that this may be practiced. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.
[114]
[Explanation of code]
[115]
100: electrical steel sheet
[116]
10: electrical steel plate substrate
[117]
20: scale layer
[118]
30: insulating coating layer
Claims
[Claim 1]
It includes an electrical steel sheet substrate and a scale layer present in the inward direction from the surface of the electrical steel sheet substrate, and the thickness of the scale layer is 1 to 100 nm, and the electrical steel sheet substrate is in weight %, C: 0.1% or less, Si: 6.0% or less , P: 0.5% or less, S: 0.005% or less, Mn: 1.0% or less, Al: 2.0% or less, N: 0.005% or less, Ti: 0.005% or less, Cr: 0.5% or less, the balance being Fe and Electrical steel sheet containing unavoidable impurities.
[Claim 2]
The electrical steel sheet according to claim 1, wherein the scale layer includes Si: 5 to 80 wt%, O: 5 to 80 wt%, and the balance Fe and unavoidable impurities.
[Claim 3]
The electrical steel sheet according to claim 1, wherein the scale layer has a roughness of 0.01 to 0.5 nm.
[Claim 4]
The electrical steel sheet according to claim 1, further comprising an insulating coating layer positioned on the scale layer.
[Claim 5]
preparing a hot-rolled sheet by hot-rolling the slab; removing some of the scale formed on the hot-rolled sheet and leaving a scale layer having a thickness of 10 nm or more; controlling the roughness of the hot-rolled sheet on which the scale layer remains; manufacturing a cold rolled sheet by cold rolling; and annealing the cold-rolled sheet.
[Claim 6]
The method of claim 5, wherein in the step of residue of the scale layer, by using a blasting method the dose of the particle steel plate per 20g / m 3 to 1000g / m 3 processing at the speed of the particle is 0.1 km / s to 200km / s A method for manufacturing an electrical steel sheet.
[Claim 7]
The method of claim 5, wherein, in the step of controlling the roughness of the hot-rolled sheet, the roughness is controlled to 0.1 to 2.0 nm.
[Claim 8]
The method of claim 5 , wherein the controlling of the roughness of the hot-rolled sheet comprises passing the hot-rolled sheet between blades coated with rubber.
[Claim 9]
The method of claim 8, wherein the rubber has an elasticity of 7 to 45 Mpa.
[Claim 10]
The method for manufacturing an electrical steel sheet according to claim 5, further comprising, after the step of controlling the roughness of the hot-rolled sheet, pickling.
[Claim 11]
The method of claim 10, wherein the pickling comprises immersing in an acid solution of 15 wt% or less for 20 to 70 seconds.