KR20210083569A - Non-oriented electrical steel sheet and method of manufactruing the same - Google Patents

Abstract

Disclosed are a non-oriented electrical steel sheet having properties similar to a front coating method by forming a plurality of island insulating pattern layers by an island-type partial coating method, and a manufacturing method thereof. To this end, according to the present invention, the non-oriented electrical steel sheet has an iron loss of 2.3 to 2.7 W/kg and magnetic flux density of 1.6 to 1.9T, which are magnetic physical values similar to a structure using an insulating layer covering an entire surface of a steel sheet by a front coating method by application of the plurality of island insulation pattern layer.

Description

Non-oriented electrical steel sheet and its manufacturing method {NON-ORIENTED ELECTRICAL STEEL SHEET AND METHOD OF MANUFACTRUING THE SAME}

The present invention relates to a non-oriented electrical steel sheet and a method for manufacturing the same.

Electrical steel sheet can be divided into grain-oriented electrical steel sheet and non-oriented electrical steel sheet according to magnetic properties.

An oriented electrical steel sheet is manufactured to be easily magnetized in the rolling direction of the steel sheet and has particularly excellent magnetic properties in the rolling direction, so it is mainly used as an iron core for large, small and medium-sized transformers requiring low iron loss and high permeability. .

In contrast, a non-oriented electrical steel sheet has uniform magnetic properties regardless of the direction of the steel sheet. Accordingly, non-oriented electrical steel sheets are mainly used as iron cores for linear compressor motors, air conditioner compressor motors, and high-speed motors for vacuum cleaners.

In line with the recent trend of increasing the efficiency and miniaturization of electrical equipment in terms of energy saving, research is being conducted to reduce iron loss as much as possible in non-oriented electrical steel sheets.

As such, the non-oriented electrical steel sheet requires a technique for improving the efficiency of the motor through reduction of iron loss.

In general, technology for reducing iron loss of non-oriented electrical steel sheet includes improvement of specific resistance through composition control of electrical steel sheet, grain orientation distribution and grain size control, steel sheet thickness reduction, surface insulation layer control technology, and the like.

When insulation between electrical steel sheets laminated in a motor core manufactured by additive manufacturing of electrical steel sheets is secured, eddy current loss can be reduced, thereby contributing to high efficiency of the motor.

KR Patent Publication No. 10-2018-0074438 (published on Jul. 3, 2018)

SUMMARY OF THE INVENTION An object of the present invention is to provide a non-oriented electrical steel sheet having insulation properties similar to those of the front coating method by forming a plurality of island insulation pattern layers in an island-type partial coating method, and a method for manufacturing the same.

In addition, an object of the present invention is to introduce a plurality of island insulation pattern layers, and a magnetic property value similar to that of a structure in which an insulation layer covering the entire surface of a steel sheet is applied in a full-surface coating method is 2.3 ~ 2.7 W/kg of iron loss and 1.6 ~ 1.9 To provide a non-oriented electrical steel sheet having a magnetic flux density of T and a method for manufacturing the same.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention not mentioned may be understood by the following description, and will be more clearly understood by the examples of the present invention. Moreover, it will be readily apparent that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

In the non-oriented electrical steel sheet and the method for manufacturing the same according to the present invention, insulating properties similar to those of the front coating method can be realized by forming a plurality of island insulating pattern layers in an island-type partial coating method.

Accordingly, the present invention provides an insulating coating material by forming an island insulating pattern layer by a partial coating method of an island type, unlike the formation of an insulating layer by a full-surface coating method that ^{requires approximately 8 to 10 g/m 2 of an insulating coating material.} Since the material takes approximately 4 to 6 g/m ² , the insulation coating material can be reduced by approximately 50%.

In addition, the non-oriented electrical steel sheet and the method for manufacturing the same according to the present invention introduce a plurality of island insulating pattern layers, and the magnetic property value of 2.3 ~ 2.7W similar to that of the structure in which an insulating layer covering the entire surface of the steel sheet is applied in a front coating method It has an iron loss of /kg and a magnetic flux density of 1.6 ~ 1.9T.

As a result, the non-oriented electrical steel sheet and its manufacturing method according to the present invention can secure the price competitiveness of the non-oriented electrical steel sheet through reduction of the material cost and process cost of the insulating layer, thereby helping to secure the price competitiveness of motor products. It is possible to achieve high efficiency by reducing the loss of the motor as it is possible to secure insulation.

The non-oriented electrical steel sheet and its manufacturing method according to the present invention suggest an insulating layer coating technology to secure the insulation of the electrical steel sheet, and break away from the entire surface coating method, which is a deposition and coating method using an existing organic/inorganic material.

To this end, the non-oriented electrical steel sheet and the method for manufacturing the same according to the present invention can reduce process costs and material costs by applying the island-type partial coating method using the spray method, as well as insulating properties similar to the front coating method When applied as a core by maintaining the magnetic properties, the magnetic properties can also exhibit a similar level.

In addition, the non-oriented electrical steel sheet and its manufacturing method according to the present invention can secure excellent insulation while using a small amount of insulating coating material by applying an island-type partial coating method.

As a result, the non-oriented electrical steel sheet and its manufacturing method according to the present invention can minimize the eddy current loss by securing insulation between the electrical steel sheets laminated in the motor core manufactured by the additive processing of the electrical steel sheet, so that it is possible to minimize the eddy current loss. can contribute

In addition to the above-described effects, the specific effects of the present invention will be described together while describing specific details for carrying out the invention below.

1 is a plan view showing a grain-oriented electrical steel sheet according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along line II-II' of FIG. 1 .
3 is a process flow chart showing a method for manufacturing a grain-oriented electrical steel sheet according to an embodiment of the present invention.
FIG. 4 is a process schematic diagram for explaining the partial coating method of the island type of FIG. 3 .
5 is an exterior photograph showing specimens according to Example 1 and Comparative Example 1. FIG.
6 is an SEM photograph showing a specimen according to Example 1. FIG.
7 is an SEM photograph showing a specimen according to Comparative Example 1. FIG.
8 is a photograph for explaining the surface elemental analysis (SEM-EDS) process of the specimen according to Example 2.
9 is a graph showing a cross-sectional elemental analysis (SEM-EDS) result of a specimen according to Example 2.

The above-described objects, features and advantages will be described below in detail with reference to the accompanying drawings, and accordingly, those of ordinary skill in the art to which the present invention pertains will be able to easily implement the technical idea of the present invention. In describing the present invention, if it is determined that a detailed description of a known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to refer to the same or similar components.

As used herein, the singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as "consisting of" or "comprising" should not be construed as necessarily including all of the various components or various steps described in the specification, some of which components or some steps are It should be construed that it may not include, or may further include additional components or steps.

Hereinafter, a non-oriented electrical steel sheet and a manufacturing method thereof according to some embodiments of the present invention will be described.

1 is a plan view showing a grain-oriented electrical steel sheet according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II' of FIG. 1 .

1 and 2 , a non-oriented electrical steel sheet 100 according to an embodiment of the present invention includes a steel sheet 120 and an island insulating pattern layer 140 .

The steel plate 120 may have a plate shape having an upper surface and a lower surface opposite to the upper surface.

At this time, the steel plate 120 preferably has a thickness of 0.1 ~ 0.5mm. When the thickness of the steel plate 120 is less than 0.1 mm, it is not preferable because it may cause shape defects when used as a core of a linear compressor motor, an air conditioner compressor motor, and a high-speed motor for a vacuum cleaner. Conversely, when the thickness of the steel plate 120 exceeds 0.5 mm, it is not preferable because a large amount of texture of the (100) plane cannot be secured, and the magnetic flux density is deteriorated.

Here, the steel sheet 120 is C: 0.05 wt% or less, Si: 3.5 wt% or less, Al: 1.0 wt% or less, Mn: 0.3 wt% or less, P: 0.5 wt% or less, S: 0.01 wt% or less, O : 0.05 wt% or less and the remaining Fe and unavoidable impurities may be included, but is not limited thereto.

When carbon (C) is added in a large amount, the austenite region is enlarged, the phase transformation period is increased, and the iron loss is deteriorated by suppressing the grain growth of ferrite during the final annealing heat treatment. In addition, since carbon (C) increases iron loss due to magnetic aging when used after processing from a final product to an electrical product, it is preferable to control so that the content ratio of 0.05 wt% or less is contained.

Silicon (Si) is added to increase the resistivity to lower the eddy current loss during iron loss. However, if the amount of silicon (Si) added exceeds 3.5 wt%, it may cause a decrease in magnetic flux density, decrease the torque of the motor or increase copper loss, and cracks or plate breakage may occur during cold rolling due to increased brittleness. have. Therefore, silicon (Si) is preferably added in a content ratio of 3.5 wt% or less of the total weight of the non-oriented electrical steel sheet according to the present invention.

Aluminum (Al) together with silicon (Si) contributes to lowering the iron loss of the non-oriented electrical steel sheet. However, when the amount of aluminum (Al) is excessively added exceeding 1.0 wt %, the magnetic flux density is lowered and the torque of the motor is lowered or copper loss is increased. Therefore, aluminum (Al) is preferably added in a content ratio of 1.0 wt% or less of the total weight of the non-oriented electrical steel sheet according to the present invention.

Manganese (Mn) lowers the solid solution temperature of precipitates during reheating and prevents cracks generated at both ends of the material during hot rolling. However, when the addition amount of manganese (Mn) exceeds 0.1 wt %, the roll load increases and cold rolling property deteriorates, so it is not preferable. Therefore, manganese (Mn) is preferably added in a content ratio of 0.3% by weight or less of the total weight of the non-oriented electrical steel sheet according to the present invention.

Phosphorus (P) serves to increase the resistivity and lower the iron loss. However, when the amount of phosphorus (P) is excessively added in excess of 0.5 wt %, it is not preferable because cold rolling properties may be deteriorated. Therefore, phosphorus (P) is preferably added in a content ratio of 0.5% by weight or less of the total weight of the non-oriented electrical steel sheet according to the present invention.

Sulfur (S) tends to react with manganese (Mn) to form fine precipitates of MnS to inhibit grain growth, so it is preferable to control to have the smallest possible amount. Therefore, sulfur (S) is preferably controlled to 0.01% by weight or less of the total weight of the non-oriented electrical steel sheet according to the embodiment of the present invention.

When oxygen (O) is added in a large amount exceeding 0.05 wt %, the amount of oxide increases to inhibit grain growth, thereby deteriorating iron loss characteristics. Therefore, oxygen (O) is preferably controlled to 0.05% by weight or less of the total weight of the non-oriented electrical steel sheet according to the embodiment of the present invention.

The island insulating pattern layer 140 is formed on at least one surface of the steel plate 120 . At this time, although FIG. 2 shows that the island insulating pattern layer 140 is formed only on the upper surface of the steel plate 120, it may be formed on the lower surface as well as the upper surface.

A plurality of such island insulating pattern layers 140 are formed to be spaced apart from each other in an island shape on the surface of the steel plate 120 .

As such, in the present invention, the insulating layer is not formed by the front coating method applied to secure the insulation properties of the conventional non-oriented electrical steel sheet, but a plurality of island insulation pattern layers ( 140) was formed. As a result, in the present invention, by forming the plurality of island insulating pattern layers 140 using the island-shaped partial coating method, the cost and process cost of the insulating layer material compared to the insulating layer formed by the conventional full-surface coating method are reduced. It has a structural advantage that can be significantly reduced.

It is preferable that the plurality of island insulating pattern layers 140 have an average length of 20 to 300 μm and an average separation distance of 10 to 500 μm. When the average length of the plurality of island insulating pattern layers 140 is less than 20 μm or the average separation distance exceeds 500 μm, the formation area of the plurality of island insulating pattern layers 140 is too small, so that the It may be difficult to secure insulation. Conversely, when the average length of the plurality of island insulating pattern layers 140 exceeds 300 μm or the average separation distance is less than 10 μm, the insulating material due to the excessively large formation area of the plurality of island insulating pattern layers 140 . It is difficult to show the effect of reducing the cost of insulating layer material and process cost due to the increase in the amount of

The island insulating pattern layer preferably has a thickness of 7 μm or less, more preferably 3 to 6 μm, in order to secure a stacking factor when stacking the steel sheets 120 .

The island insulating pattern layer 140 is formed of SiO ₂ based inorganic glass. More specifically, the island insulating pattern layer 140 is a SiO ₂ based inorganic glass containing 1 to 10% by weight of at least one _{of Na 2} O and K _{2 O, Fe 2} O ₃ 1% by weight or less, and the remaining SiO _{2 .} is formed

In the non-oriented electrical steel sheet 100 according to the embodiment of the present invention described above, by forming the plurality of island insulating pattern layers 140 in an island-type partial coating method, insulating properties similar to the front coating method can be implemented.

Accordingly, in the present invention, the island insulation pattern layer 140 is formed by the island-type partial coating method, unlike the formation of the insulation layer by the full-surface coating method that requires approximately 8 to 10 g/m ^{2 of the insulation coating material.} , it is possible to save about 50% of the insulation coating material because it takes about 4 ~ 6g/m ^{2 of the insulation coating material.}

In addition, the non-oriented electrical steel sheet 100 according to the embodiment of the present invention is similar to the structure in which an insulating layer covering the entire surface of the steel sheet 120 is applied by the introduction of a plurality of island insulating pattern layers 140 , in a front coating method. It has an iron loss of 2.3 ~ 2.7W/kg, which is a magnetic property value, and a magnetic flux density of 1.6 ~ 1.9T.

As a result, since the non-oriented electrical steel sheet 100 according to the embodiment of the present invention can secure the price competitiveness of the non-oriented electrical steel sheet 100 through reduction of material cost and process cost of the insulating layer, price competitiveness of motor products It can help to secure, and it is possible to secure insulation, so it is possible to reduce the loss of the motor and achieve high efficiency.

Hereinafter, a method for manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention will be described with reference to the accompanying drawings.

3 is a process flowchart showing a method for manufacturing a grain-oriented electrical steel sheet according to an embodiment of the present invention, and FIG. 4 is a process schematic diagram for explaining the island type partial coating method of FIG. 3 .

As shown in Figure 3, the grain-oriented electrical steel sheet manufacturing method according to an embodiment of the present invention includes a steel sheet preparation step (S110), a partial coating step (S120) and a drying step (S130).

grater preparation

In the steel plate preparation step (S110), a steel plate is prepared.

At this time, the steel sheet is C: 0.05 wt% or less, Si: 3.5 wt% or less, Al: 1.0 wt% or less, Mn: 0.3 wt% or less, P: 0.5 wt% or less, S: 0.01 wt% or less, O: 0.05 wt% or less % or less and reheating and hot rolling of a steel slab containing Fe and unavoidable impurities may be used. Alternatively, the steel sheet may be applied to a steel slab having the above composition after reheating, hot rolling and hot rolling annealing, and then pickling and cold rolling.

Here, the steel sheet preferably has a thickness of 0.1 to 0.5 mm. If the thickness of the steel sheet is less than 0.1mm, it is not preferable because it may cause shape defects when used as a core of a linear compressor motor, an air conditioner compressor motor, and a high-speed motor for a vacuum cleaner. Conversely, when the thickness of the steel sheet exceeds 0.5 mm, it is not preferable because a large amount of texture of the (100) plane cannot be secured and the magnetic flux density is deteriorated.

Here, the hot-rolling annealing heat treatment is performed for the purpose of recrystallizing the drawn grains in the center of the hot-rolled steel sheet and inducing uniform grain distribution in the thickness direction of the steel sheet. Such hot rolling annealing heat treatment is preferably performed under the conditions of 800 ~ 1,100 ℃. When the hot-rolling annealing heat treatment temperature is less than 800° C., a uniform grain distribution may not be obtained, and thus the effect of improving magnetic flux density and iron loss may be insufficient. Conversely, when the hot-rolling annealing heat treatment temperature exceeds 1,100° C., the (111) plane texture unfavorable to magnetism increases and the magnetic flux density deteriorates.

partial coating

3 and 4 , in the partial coating step S120 , an insulating coating solution is locally partially coated on the steel plate 120 to form an island insulating material layer.

In this step, partial coating was performed using a spray method in which an insulating coating solution was locally sprayed on the surface of the steel plate 120 from a spray nozzle 200 mounted on the upper side spaced apart from the steel plate 120 .

As such, in the present invention, a plurality of island insulating material layers are formed by applying an island-shaped partial coating method, rather than forming the insulating layer by the full-surface coating method applied to secure the insulation properties of the conventional non-oriented electrical steel sheet. formed. As a result, in the present invention, by applying the island-type partial coating method, there is an advantage in that the cost of the insulating layer material and the process cost can be significantly reduced compared to the conventional full surface coating method.

This island-type partial coating method is not performed as a full-surface coating method using deposition, roll coating, bar coating, etc., but is applied to an insulating coating solution SiO ₂ based inorganic glass with a solvent. It is a partial coating in the form of an island while controlling the coating content by coating the liquid glass mixed with the spray coating method.

Here, as the insulating coating solution, SiO ₂ based inorganic glass is used. More specifically, as the insulation coating solution, it is more preferable to use a SiO ₂ based inorganic glass containing 1 to 10% by weight of at least one _{of Na 2} O and K _{2 O, Fe 2} O ₃ 1% by weight or less, and the remaining SiO _{2 .} Do.

dry

In the drying step ( S130 ), the steel sheet 120 on which the island insulating material layer is formed is dried on a drying rack 300 to form an island insulating pattern layer.

In this step, drying is preferably carried out at 150 ~ 300 ℃ for 10 ~ 120 minutes. When the drying temperature is less than 150° C. or the drying time is less than 10 minutes, it may be difficult to secure adhesion between the steel sheet and the island insulation pattern layer. Conversely, if the drying temperature exceeds 300° C. or the drying time exceeds 120 minutes, it may act as a factor of increasing only the drying temperature and time without further increasing the effect, so it is not economical.

In this step, a plurality of island insulating pattern layers are formed to be spaced apart from each other in an island shape on the surface of the steel plate 120 . In this case, it is preferable that the plurality of island insulating pattern layers have an average length of 20 to 300 μm and an average separation distance of 10 to 500 μm.

When the average length of the plurality of island insulating pattern layers is less than 20 μm or the average separation distance exceeds 500 μm, the formation area of the plurality of island insulating pattern layers is too small, so it may be difficult to secure insulation of the electrical steel sheet. Conversely, when the average length of the plurality of island insulation pattern layers exceeds 300 μm or the average separation distance is less than 10 μm, the formation area of the plurality of island insulation pattern layers is excessively large due to an increase in the amount of the insulation material used. It is difficult to achieve the effect of material cost and process cost reduction.

The island insulating pattern layer preferably has a thickness of 7 μm or less, more preferably 3 to 6 μm, in order to secure a stacking factor during lamination of steel sheets.

On the other hand, the non-oriented electrical steel sheet manufacturing method according to an embodiment of the present invention may further include a final annealing heat treatment step performed after the drying step (S130).

In this final annealing heat treatment step, the steel sheet on which the island insulation pattern layer is formed is subjected to final annealing heat treatment at a temperature of 800 to 1,100° C. for 0.5 to 3 hours.

At this time, when the final annealing heat treatment temperature is less than 800 ° C. or the final annealing heat treatment time is less than 0.5 hours, P and S inside the steel sheet do not sufficiently diffuse to the surface, so it is difficult to properly exert the effect of strengthening the strength of the (100) plane. Conversely, when the final annealing heat treatment temperature exceeds 1,100° C. or the final annealing heat treatment time exceeds 3 hours, energy loss is large, which is uneconomical.

The non-oriented electrical steel sheet according to the embodiment of the present invention is manufactured by the above-described process (S110 to S130).

The non-oriented electrical steel sheet and its manufacturing method according to an embodiment of the present invention present an insulating layer coating technology to secure the insulation of the electrical steel sheet, and break away from the entire surface coating method of deposition and coating using existing organic/inorganic materials.

To this end, the non-oriented electrical steel sheet and its manufacturing method according to an embodiment of the present invention can reduce the process cost and material cost by applying the island type partial coating method using the spray method, as well as the front coating method and By maintaining similar insulating properties, the magnetic properties also exhibit a similar level when applied as a core.

In addition, the non-oriented electrical steel sheet and the method for manufacturing the same according to an embodiment of the present invention can secure excellent insulation while using a small amount of insulating coating material by applying an island-type partial coating method.

As a result, according to the present invention, eddy current loss can be minimized by securing insulation between laminated electrical steel sheets in a motor core manufactured by additive manufacturing of electrical steel sheets, and thus can contribute to high efficiency of the motor.

Example

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, this is presented as a preferred example of the present invention and cannot be construed as limiting the present invention in any sense.

Content not described here will be omitted because it can be technically inferred sufficiently by a person skilled in the art.

1. Manufacture of non-oriented electrical steel sheet

Example 1

C: 0.015wt%, Si: 2.10wt%, Al: 0.41wt%, Mn: 0.11wt%, P: 0.021wt%, S: 0.002wt%, O: 0.021wt% After reheating at 1,150° C., finish hot rolling was performed at 860° C. to prepare a steel sheet with a thickness of 0.3 mm.

And then used as _{a, Na 2 O 3wt%, K} 2 O 4wt%, Fe 2 O 3 0.5wt% and the balance SiO ₂ SiO ₂ type inorganic glass spray a liquid glass mixed with a solvent in a coating method comprising a steel sheet on the Thus, a layer of an island insulating material having a thickness of 5 μm was formed by partial coating.

Next, the steel sheet on which the island insulating material layer was formed was dried at 250° C. for 60 minutes to form an island insulating pattern layer having an average length of 210 μm and an average spacing of 340 μm.

Next, the steel sheet on which the island insulation pattern layer was formed was subjected to hot rolling annealing heat treatment at 800° C. for 2 hours, pickling and cold rolling, and then final annealing heat treatment at 1,100° C. for 5 minutes to prepare a non-oriented electrical steel sheet.

Example 2

C: 0.016wt%, Si: 2.10wt%, Al: 0.42wt%, Mn: 0.11wt%, P: 0.022wt%, S: 0.002wt%, O: 0.021wt% After reheating at 1,150° C., finish hot rolling was performed at 870° C. to prepare a steel sheet having a thickness of 0.4 mm.

And then used as _{a, Na 2 O 3wt%, K} 2 O 4wt%, Fe 2 O 3 0.5wt% and the balance SiO ₂ SiO ₂ type inorganic glass spray a liquid glass mixed with a solvent in a coating method comprising a steel sheet on the Thus, it was partially coated to form an island insulating material layer with a thickness of 6 μm.

Next, the steel sheet on which the island insulating material layer was formed was dried at 230° C. for 80 minutes to form an island insulating pattern layer having an average length of 230 μm and an average spacing of 360 μm.

Next, the steel sheet on which the island insulation pattern layer was formed was subjected to hot rolling annealing heat treatment at 800° C. for 2 hours, pickling and cold rolling, and then final annealing heat treatment at 1,100° C. for 5 minutes to prepare a non-oriented electrical steel sheet.

Example 3

C: 0.020wt%, Si: 2.10wt%, Al: 0.45wt%, Mn: 0.11wt%, P: 0.020wt%, S: 0.002wt%, O: 0.021wt% After reheating at 1,150° C., finish hot rolling was performed at 870° C. to prepare a 0.2 mm thick steel sheet.

And then used as _{a, Na 2 O 3wt%, K} 2 O 4wt%, Fe 2 O 3 0.5wt% and the balance SiO ₂ SiO ₂ type inorganic glass spray a liquid glass mixed with a solvent in a coating method comprising a steel sheet on the Thus, it was partially coated to form an island insulating material layer with a thickness of 4 μm.

Next, the steel sheet on which the island insulating material layer was formed was dried at 210° C. for 100 minutes to form an island insulating pattern layer having an average length of 210 μm and an average spacing of 320 μm.

Next, the steel sheet on which the island insulation pattern layer was formed was subjected to hot rolling annealing heat treatment at 800° C. for 2 hours, pickling and cold rolling, and then final annealing heat treatment at 1,100° C. for 5 minutes to prepare a non-oriented electrical steel sheet.

Comparative Example 1

C: 0.020wt%, Si: 2.10wt%, Al: 0.41wt%, Mn: 0.11wt%, P: 0.022wt%, S: 0.002wt%, O: 0.021wt% After reheating at 1,150° C., finish hot rolling was performed at 860° C. to prepare a steel sheet having a thickness of 0.4 mm.

Next, on a steel plate, Na ₂ O 3wt%, K ₂ O 4wt%, Fe ₂ O ₃ 0.5wt%, and the remaining SiO ₂ Liquid glass containing a solvent mixed with SiO ₂ inorganic glass using a bar coating method. The entire surface was coated to a thickness of 6 μm to form an insulating material layer.

Next, the steel sheet on which the insulating material layer was formed was dried at 250° C. for 70 minutes to form an insulating layer.

Next, the steel sheet having the insulating layer formed thereon was subjected to hot rolling annealing heat treatment at 800° C. for 2 hours, pickling and cold rolling, and then final annealing heat treatment at 1,100° C. for 5 minutes to prepare a non-oriented electrical steel sheet.

Comparative Example 2

C: 0.016wt%, Si: 2.10wt%, Al: 0.50wt%, Mn: 0.11wt%, P: 0.022wt%, S: 0.002wt%, O: 0.021wt% After reheating at 1,150°C, finish hot rolling was performed at 860°C.

Next, the finish hot-rolled steel sheet was subjected to hot-rolling annealing heat treatment at 800° C. for 2 hours, pickling and cold rolling, and then final annealing heat treatment at 1,100° C. for 5 minutes to prepare a non-oriented electrical steel sheet.

2. Physical property evaluation

Table 1 shows the results of evaluation of physical properties of the non-oriented electrical steel sheets prepared according to Examples 1 to 3 and Comparative Examples 1 to 2. At this time, the iron loss W15/50 is the amount of energy lost due to heat when a magnetic flux density of 1.5 Tesla is induced in the iron core at an alternating current of 50 Hz, and the magnetic flux density B50 is a value induced by an excitation force of 5000 A/m.

Here, the insulation resistance was shown by measuring the contact resistance between the steel sheets after stacking 10 non-oriented electrical steel sheets prepared according to Examples 1 to 3 and Comparative Examples 1 to 2, respectively.

[Table 1]

As shown in Table 1, the non-oriented electrical steel sheet according to Examples 1 to 3 to which the island type partial coating method is applied, Comparative Example 1 to which the front coating method is applied, and Comparative Example 2 to which the insulating layer is not formed. All grain-oriented electrical steel sheets satisfied iron loss of 2.3 ~ 2.7W/kg and magnetic flux density of 1.6 ~ 1.9T.

In addition, it was confirmed that the non-oriented electrical steel sheet according to Examples 1 to 3 exhibited properties similar to the insulating resistance of the non-oriented electrical steel sheet according to Comparative Example 1 to which the front coating method was applied.

On the other hand, the non-oriented electrical steel sheet according to Comparative Example 2 in which the insulating layer was not formed had an insulating resistance value of 0.5 MΩ, confirming that the insulating performance was not good.

As can be seen based on the above experimental results, the non-oriented electrical steel sheets manufactured according to Examples 1 to 3 were non-oriented electrical steel sheets prepared according to Comparative Example 1 in which the entire surface coating method was applied, despite the island-type partial coating applied. It was confirmed that physical properties similar to those of steel sheets were exhibited.

3. Appearance Characteristics and Microstructure Analysis

5 is an exterior photograph showing specimens according to Example 1 and Comparative Example 1. FIG. In addition, FIG. 6 is an SEM photograph showing the specimen according to Example 1, and FIG. 7 is an SEM photograph showing the specimen according to Comparative Example 1. Referring to FIG.

As shown in FIG. 5 , in the case of the specimens according to Example 1 and Comparative Example 1, there was no significant difference in appearance.

However, as shown in FIGS. 6 and 7 , as a result of microstructure analysis, it can be confirmed that, in the specimen according to Example 1, a plurality of island-type insulating pattern layers partially coated in an island type are formed on the surface of the steel sheet. .

On the other hand, it can be seen that the specimen according to Comparative Example 1 has an insulating coating layer covering the entire surface of the steel sheet.

4. Component Analysis

Table 2 shows the surface elemental analysis results of the specimen according to Example 2, and FIG. 8 is a photograph for explaining the surface elemental analysis (SEM-EDS) process of the specimen according to Example 2. Also, FIG. 9 is a graph showing the results of cross-sectional elemental analysis (SEM-EDS) of the specimen according to Example 2. Referring to FIG.

[Table 2] (Unit: wt%)

As shown in Table 2, FIGS. 8 and 9, the component analysis results for each coating site for the specimen according to Example 2 are shown. In this case, the component analysis results for the island portion (①) in which the island insulation pattern layer is formed and the US island portion (②) in which the island insulation pattern layer is not formed among the specimens according to Example 2 are shown.

Here, a large amount of Fe was detected in the US island part (②), but Fe was not detected in the island part (①).

As can be seen from the above experimental results, the island portion (①) was well formed with an island insulation pattern layer, so Fe was not detected, and the island portion (②) did not form an island insulation pattern layer, so the surface of the steel sheet was exposed and Fe was confirmed to be detected.

As described above, the present invention has been described with reference to the illustrated drawings, but the present invention is not limited by the embodiments and drawings disclosed in this specification, and various methods can be obtained by those skilled in the art within the scope of the technical spirit of the present invention. It is obvious that variations can be made. In addition, although the effects according to the configuration of the present invention are not explicitly described and described while describing the embodiments of the present invention, it is natural that the effects predictable by the configuration should also be recognized.

100: non-oriented electrical steel sheet
120: steel plate
140: island insulation pattern layer
200: spray nozzle
300: dryer
S110: steel plate preparation step
S120: Partial coating step
S130: drying step

Claims (13)

grater; and
Including; an island insulating pattern layer formed on at least one surface of the steel sheet;
The island insulating pattern layer is a non-oriented electrical steel sheet formed so as to be spaced apart in the form of an island on the surface of the steel sheet.
According to claim 1,
The steel plate
Non-oriented electrical steel sheet having a thickness of 0.1 ~ 0.5mm.
According to claim 1,
The plurality of island insulating pattern layers are
A non-oriented electrical steel sheet having an average length of 20 ~ 300㎛ and an average spacing of 10 ~ 500㎛.
According to claim 1,
The island insulating pattern layer is
Non-oriented electrical steel sheet having a thickness of 7㎛ or less.
According to claim 1,
The island insulating pattern layer is
Non-oriented electrical steel sheet formed of SiO _{2 based inorganic glass.}
6. The method of claim 5,
The island insulating pattern layer is
Na ₂ O and K ₂ O 1 to 10% by weight of one or more, Fe ₂ O ₃ Non-oriented electrical steel sheet containing 1% by weight or less and the remaining SiO _{2 .}
According to claim 1,
The electric steel plate
Non-oriented electrical steel sheet with iron loss of 2.3 ~ 2.7W/kg and magnetic flux density of 1.6 ~ 1.9T.
(a) preparing a steel plate;
(b) forming an island insulating material layer by partially coating an insulating coating solution on the steel sheet; and
(c) drying the steel sheet on which the island insulating material layer is formed to form an island insulating pattern layer;
A non-oriented electrical steel sheet manufacturing method comprising a.
9. The method of claim 8,
In step (a),
The steel plate
A method for manufacturing a non-oriented electrical steel sheet having a thickness of 0.1 to 0.5 mm.
9. The method of claim 8,
In step (c),
The insulating coating solution is
Manufacture of non-oriented electrical steel sheet, which is a liquid glass in which a solvent is mixed with SiO ₂ based inorganic glass containing 1 to 10 wt% of at least one of Na ₂ O and K ₂ O, 1 wt% or less of _{Fe 2} O _{3 and the remaining SiO 2} Way.
9. The method of claim 8,
In step (c),
the drying
A non-oriented electrical steel sheet manufacturing method carried out at 150 ~ 300 ℃ for 10 ~ 120 minutes.
9. The method of claim 8,
In step (c),
A plurality of the island insulating pattern layers are formed to be spaced apart from each other in an island shape on the surface of the steel sheet,
A method for manufacturing a non-oriented electrical steel sheet having an average length of 20 to 300 μm and an average spacing of 10 to 500 μm.
9. The method of claim 8,
In step (c),
The island insulating pattern layer is
A method for manufacturing a non-oriented electrical steel sheet having a thickness of 7 μm or less.

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