KR102483634B1 - Non-oriented electrical steel sheet and method of manufactruing the same - Google Patents

Abstract

Disclosed about a non-oriented electrical steel sheet capable of securing excellent iron loss even at low temperatures by optimizing the texture of the electrical steel sheet by adjusting the temperature and atmosphere of the decarburization annealing heat treatment and the final annealing heat treatment after cold rolling, and a method for manufacturing the same do.
As a result, the non-oriented electrical steel sheet and its manufacturing method according to the present invention can reduce process costs by lowering the decarburization annealing heat treatment temperature to 780 ~ 920 ° C., and reduce the risk of oxidation to lower the defect rate.

Description

Non-oriented electrical steel sheet and manufacturing method thereof

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

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

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 and medium-sized transformers requiring low iron loss and high magnetic permeability. .

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

Recently, according to the trend of increasing the efficiency and miniaturization of electrical devices in terms of energy saving, research is being conducted to minimize iron loss even in non-oriented electrical steel sheets.

KR Patent Publication No. 10-1994-0009347 (published on May 20, 1994)

An object of the present invention is to optimize the texture of the electrical steel sheet by adjusting the temperature and atmosphere of the decarburization annealing heat treatment and the final annealing heat treatment after cold rolling, thereby providing a non-oriented electrical steel sheet that can secure excellent iron loss even at low temperatures and its It is to provide a manufacturing method.

In addition, an object of the present invention is to increase the fraction of non-recrystallized crystal grains by lowering the decarburization annealing heat treatment temperature in the H ₂ gas atmosphere to 780 ~ 920 ℃, more preferably 780 ~ 820 ℃ from 1000 ℃ or more. In addition to increasing the possibility of texture change, by performing final annealing heat treatment in an Ar gas atmosphere at 980 to 1,020 ° C., it is to provide a cost-effective non-oriented electrical steel sheet with excellent core loss and a manufacturing method thereof.

In addition, an object of the present invention is to provide a non-oriented electrical steel sheet and a method for manufacturing the same, which can reduce process costs by lowering the decarburization annealing heat treatment temperature to 780 ~ 920 ° C, reduce the risk of oxidation and lower the defect rate will be.

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 above can be understood by the following description and will be more clearly understood by the examples of the present invention. It will also be readily apparent that the objects and advantages of the present invention may be realized by means of the instrumentalities and combinations indicated in the claims.

The non-oriented electrical steel sheet and its manufacturing method according to the present invention can secure excellent iron loss even at low temperatures by optimizing the texture of the electrical steel sheet by adjusting the temperature and atmosphere of the decarburization annealing heat treatment and the final annealing heat treatment after cold rolling. It is to provide a non-oriented electrical steel sheet and a manufacturing method thereof.

In addition, the non-oriented electrical steel sheet and its manufacturing method according to the present invention, when decarburization annealing heat treatment in an H ₂ gas atmosphere, set the decarburization annealing heat treatment temperature to 780 ~ 920 ℃, more preferably 780 ~ 820 ℃ from 1000 ℃ or more. In addition to increasing the possibility of texture change by increasing the fraction of non-recrystallized crystal grains by lowering the fraction, it is possible to manufacture a cost-effective electrical steel sheet with excellent core loss by performing final annealing heat treatment in an Ar gas atmosphere at 980 ~ 1,020 ° C. can

As a result, the non-oriented electrical steel sheet and its manufacturing method according to the present invention optimize the texture of the electrical steel sheet by adjusting the temperature and gas atmosphere of the decarburization annealing heat treatment and the final annealing heat treatment after cold rolling, so that even at a low temperature, 1.65 Iron loss (W15/50) of ~ 2.15 W/kg and magnetic flux density (B50) of 1.65 ~ 1.80 T can be secured.

To this end, the non-oriented electrical steel sheet according to the present invention contains C: more than 0 wt% and less than 0.05 wt%, Si: 1.0 to 3.5 wt%, Al: 0.2 to 0.6 wt%, Mn: 0.02 to 0.20 wt%, P: 0.01 to 0.20 wt%, S: more than 0 wt% to 0.01 wt% or less, and the remainder including Fe and unavoidable impurities.

In addition, the non-oriented electrical steel sheet according to the present invention contains at least one of Cu: more than 0% by weight and less than 0.03% by weight, Ni: more than 0% by weight and less than 0.03% by weight, and Cr: more than 0% by weight and less than 0.05% by weight. may further include.

Here, the non-oriented electrical steel sheet according to the present invention preferably has a thickness of 0.05 to 0.50 mm.

In addition, the non-oriented electrical steel sheet according to the present invention has a tensile strength of 400 to 560 N/mm 2 and a hardness of 200 to 270 Hv.

The non-oriented electrical steel sheet according to the present invention and its manufacturing method strictly control the content ratio of Si, Al, etc., lower the heat treatment temperature in the decarburization annealing heat treatment and the final annealing heat treatment, and adjust the gas atmosphere while lowering the temperature. It is possible to exhibit low iron loss characteristics.

In addition, the non-oriented electrical steel sheet and its manufacturing method according to the present invention can reduce process costs and reduce the risk of oxidation by lowering the decarburization annealing heat treatment temperature to 780 ~ 920 ℃, more preferably 780 ~ 820 ℃. can reduce the failure rate.

As a result, the non-oriented electrical steel sheet and its manufacturing method according to the present invention optimize the texture of the electrical steel sheet by adjusting the temperature and gas atmosphere of the decarburization annealing heat treatment and the final annealing heat treatment after cold rolling, so that even at a low temperature, 1.65 Iron loss (W15/50) of ~ 2.15 W/kg and magnetic flux density (B50) of 1.65 ~ 1.80 T can be secured.

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

1 is a process flow chart showing a method for manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention.
Figure 2 is a photograph showing the results of analysis by ODF and IPF through EBSD measurement for the specimen according to Example 1.
Figure 3 is a photograph showing the results of analysis by ODF and IPF through EBSD measurement for the specimen according to Example 3.
Figure 4 is a photograph showing the results of analysis by ODF and IPF through EBSD measurement for the specimen according to Comparative Example 1.
5 is a photograph showing the results of analysis by ODF and IPF through EBSD measurement for a specimen according to Comparative Example 3.
Figure 6 is a photograph showing the comparison of the results of ODF and IPF analysis through EBSD measurement for specimens according to Example 1 and Comparative Example 5.

The above objects, features and advantages will be described later in detail with reference to the accompanying drawings, and accordingly, those skilled in the art to which the present invention belongs will be able to easily implement the technical spirit of the present invention. In describing the present invention, if it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the subject matter 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 indicate the same or similar components.

Singular expressions used herein include plural expressions unless the context clearly dictates otherwise. In this application, terms such as "consisting of" or "comprising" should not be construed as necessarily including all of the various components or steps described in the specification, and some of the components or some of the steps It should be construed that it may not be included, 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.

In general, a non-oriented electrical steel sheet is performed in the order of a hot rolling step, a hot rolling annealing heat treatment step, a cold rolling step, a decarburization annealing heat treatment step, and a final annealing heat treatment step.

Here, each of the decarburization annealing heat treatment and the final annealing heat treatment is performed in an H ₂ gas atmosphere at 1,000° C. or higher. In general, when heat treatment is performed in an H ₂ gas atmosphere, heat treatment is possible while maintaining a reducing atmosphere to reduce oxidation.

However, when each of the decarburization annealing heat treatment temperature and the final annealing heat treatment temperature is performed at 1,000 ° C. or more, there is a problem in that the risk of oxidation is high and the process cost increases due to the application of a high temperature process.

In order to solve this problem, in the present invention, by adjusting the temperature and atmosphere of the decarburization annealing heat treatment and the final annealing heat treatment after cold rolling to optimize the texture of the electrical steel sheet, it is to manufacture an electrical steel sheet having excellent iron loss even at a low temperature. it could be possible

That is, in the present invention, during the decarburization annealing heat treatment in the H ₂ gas atmosphere, the decarburization annealing temperature is lowered from the existing 1000 ° C or higher to 780 ~ 920 ° C, more preferably 780 ~ 820 ° C. In addition to increasing the possibility of changing texture, it is possible to manufacture a cost-effective electrical steel sheet with excellent iron loss by performing final annealing heat treatment in an Ar gas atmosphere at 980 to 1,020 ° C.

To this end, the non-oriented electrical steel sheet according to an embodiment of the present invention contains C: more than 0 wt% and less than 0.05 wt%, Si: 1.0 to 3.5 wt%, Al: 0.2 to 0.6 wt%, and Mn: 0.02 to 0.20 wt%. , P: 0.01 to 0.20% by weight, S: more than 0% to 0.01% by weight and the remainder including Fe and unavoidable impurities, iron loss (W15/50) of 1.65 to 2.15 W/kg and magnetic flux of 1.65 to 1.80 T It has a density (B50).

Here, it is more preferable that the non-oriented electrical steel sheet according to the embodiment of the present invention has an iron loss (W15/50) of 1.70 to 1.90 W/kg and a magnetic flux density (B50) of 1.65 to 1.80 T.

In addition, the non-oriented electrical steel sheet according to an embodiment of the present invention contains Cu: more than 0 wt% to 0.03 wt% or less, Ni: more than 0 wt% to 0.03 wt% or less, and Cr: more than 0 wt% to 0.05 wt% or less. One or more may be further included.

Here, the non-oriented electrical steel sheet according to the embodiment of the present invention preferably has a thickness of 0.05 to 0.50 mm. If the thickness of the non-oriented electrical steel sheet is less than 0.05 mm, it is not preferable because it may cause shape defects when used as an iron core for linear compressor motors, air conditioner compressor motors, and high-speed motors for vacuum cleaners. Conversely, when the thickness of the non-oriented electrical steel sheet exceeds 0.50 mm, a large amount of the texture of the (100) plane cannot be secured and the magnetic flux density is deteriorated, which is not preferable.

In addition, the non-oriented electrical steel sheet according to the embodiment of the present invention has a tensile strength of 400 ~ 560N / ㎟ and a hardness of 200 ~ 270Hv.

Hereinafter, the role and content of each component included in the non-oriented electrical steel sheet according to an embodiment of the present invention will be described.

carbon (C)

When a large amount of carbon (C) is added, the austenite region is enlarged, the phase transformation period is increased, and iron loss is deteriorated by suppressing grain growth of ferrite during final annealing heat treatment. In addition, since carbon (C) increases iron loss due to magnetic aging when used after being processed into electrical products from final products, it is preferable to control the content ratio to be greater than 0% by weight and less than 0.05% by weight.

Silicon (Si)

Silicon (Si) is added to increase the specific resistance to lower eddy current loss among core losses.

Silicon (Si) is preferably added in a content ratio of 1.0 to 3.5% by weight of the total weight of the non-oriented electrical steel sheet according to an embodiment of the present invention, and 2.5 to 3.2% by weight may be presented as a more preferable range. When a small amount of silicon (Si) is added, such as less than 1.0% by weight, it is difficult to obtain low iron loss characteristics and it is difficult to improve magnetic permeability in the rolling direction. In addition, if the amount of silicon (Si) is excessively added, exceeding 3.5% by weight, the magnetic flux density may be lowered, the torque of the motor may decrease or the copper loss may increase, and cracks or plate breakage may occur during cold rolling due to increased brittleness. there is.

Aluminum (Al)

Aluminum (Al) contributes to lowering the core loss of the non-oriented electrical steel sheet together with silicon (Si).

Aluminum (Al) is preferably added in a content ratio of 0.2 to 0.6% by weight of the total weight of the non-oriented electrical steel sheet according to an embodiment of the present invention, and 0.3 to 0.5% by weight may be presented as a more preferable range. When the amount of aluminum (Al) added is less than 0.2% by weight, it is difficult to sufficiently exert the effect of the addition. Conversely, when the amount of aluminum (Al) is excessively added, exceeding 0.6% by weight, the magnetic flux density is lowered, and thus the torque of the motor is lowered or the copper loss is increased.

Manganese (Mn)

Manganese (Mn) lowers the solid solution temperature of the precipitate during reheating and serves to prevent cracks generated at both ends of the material during hot rolling.

Manganese (Mn) is preferably added in a content ratio of 0.02 to 0.20% by weight of the total weight of the non-oriented electrical steel sheet according to the embodiment of the present invention. When the added amount of manganese (Mn) is less than 0.02% by weight, the risk of defects due to cracks increases during hot rolling. Conversely, when the added amount of manganese (Mn) exceeds 0.20% by weight, the roll load increases and cold-rollability deteriorates, which is not preferable.

Phosphorus (P)

Phosphorus (P) serves to lower iron loss by increasing specific resistance.

Phosphorus (P) is preferably added in a content ratio of 0.01 to 0.20% by weight of the total weight of the non-oriented electrical steel sheet according to the embodiment of the present invention. When the added amount of phosphorus (P) is less than 0.01% by weight, there is a problem in that crystal grains are excessively increased and magnetic deviation is increased. Conversely, when the added amount of phosphorus (P) exceeds 0.20% by weight and is excessively added, it is not preferable because cold rolling properties may be deteriorated.

Sulfur (S)

Sulfur (S) reacts with manganese (Mn) to form fine precipitates, MnS, which tends to inhibit crystal grain growth. Therefore, sulfur (S) is preferably controlled to more than 0% by weight and less than 0.01% by weight of the total weight of the non-oriented electrical steel sheet according to the embodiment of the present invention.

Copper (Cu)

Copper (Cu) is added because it improves texture, suppresses fine CuS precipitation, and resists oxidation and corrosion. However, when a large amount of copper (Cu) is added in excess of 0.03% by weight, it may cause uniformity on the surface of the steel sheet, which is not preferable. Therefore, it is preferable to control the content ratio of copper (Cu) in an amount greater than 0% by weight and less than 0.03% by weight of the total weight of the non-oriented electrical steel sheet according to the embodiment of the present invention.

Nickel (Ni)

Nickel (Ni) is added because it improves the texture, suppresses the precipitation of S into fine CuS by adding it together with Cu, and resists oxidation and corrosion. However, when the added amount of nickel (Ni) exceeds 0.03% by weight, the effect of improving the texture is insignificant despite the addition of a large amount, which is undesirable because it is uneconomical. Therefore, it is preferable to control the content ratio of nickel (Ni) to greater than 0% by weight and less than or equal to 0.03% by weight of the total weight of the non-oriented electrical steel sheet according to the embodiment of the present invention.

Chromium (Cr)

Chromium (Cr) serves to improve iron loss by increasing resistivity while not increasing the strength of the material. However, when a large amount of chromium (Cr) is added in excess of 0.05% by weight, there is a problem in that the magnetic flux density is reduced by promoting the development of texture unfavorable to magnetism. Therefore, it is preferable to strictly control the content ratio of chromium (Cr) in a content ratio of more than 0% by weight to less than 0.05% by weight of the total weight of the non-oriented electrical steel sheet according to the embodiment of the present invention.

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.

1 is a process flow chart showing a method for manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention.

As shown in FIG. 1, the non-oriented electrical steel sheet manufacturing method according to an embodiment of the present invention includes a hot rolling step (S110), a hot rolling annealing heat treatment step (S120), a cold rolling step (S130), and a decarburization annealing heat treatment step (S140). ) and a final annealing heat treatment step (S140).

hot rolled

In the hot rolling step (S110), C: more than 0 wt% to 0.05 wt% or less, Si: 1.0 to 3.5 wt%, Al: 0.2 to 0.6 wt%, Mn: 0.02 to 0.20 wt%, P: 0.01 to 0.20 wt% , S: After reheating the steel slab containing more than 0% by weight and less than 0.01% by weight and the rest of Fe and unavoidable impurities, it is hot-rolled.

Here, the steel slab may further include one or more of Cu: greater than 0 wt% to 0.03 wt% or less, Ni: greater than 0 wt% to 0.03 wt% or less, and Cr: greater than 0 wt% to 0.05 wt% or less. .

In this step, in order to facilitate hot rolling in the process of charging a steel slab having the above composition into a heating furnace and reheating it, it is preferable to set the reheating temperature of the steel to 1,050° C. or higher. However, when the reheating temperature of the steel exceeds 1,250 ° C, precipitates harmful to iron loss characteristics such as MnS are re-dissolved, and fine precipitates tend to be excessively generated after hot rolling. Such fine precipitates are undesirable because they impede crystal grain growth and degrade iron loss characteristics. Therefore, the reheating temperature of the steel is preferably carried out at 1,050 to 1,250 ° C for 1 to 3 hours.

In addition, in this step, the finish hot rolling temperature is preferably carried out under conditions of 800 to 950 ° C. in order to prevent excessive occurrence of an oxide layer on the hot-rolled steel sheet.

Here, the hot-rolled steel sheet may be cooled in a coil state in air after being wound at a temperature of 650 to 800° C. so that an oxide layer is not excessively generated and crystal grain growth is not inhibited.

Hot rolled annealing heat treatment

In the hot rolling annealing heat treatment step (S120), the hot rolled steel sheet is subjected to hot rolling annealing heat treatment and pickling.

The hot-rolling annealing heat treatment is performed for the purpose of recrystallizing the stretched grains in the center of the hot-rolled steel sheet and inducing uniform distribution of grains in the thickness direction of the steel sheet.

The hot rolling annealing heat treatment is preferably performed under conditions of 850 to 1,000 ° C. If the hot rolling annealing heat treatment temperature is less than 850 ° 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 1,000 ° C., the texture of the (111) plane, which is unfavorable to magnetism, increases and the magnetic flux density deteriorates.

cold rolled

In the cold rolling step (S130), the pickled steel sheet is cold rolled at a reduction ratio of 55% or less.

In this step, cold rolling is final rolling to a thickness of 0.05 to 0.50 mm. If the thickness of the cold-rolled steel sheet is less than 0.05 mm, it is not preferable because it may cause shape defects when used as an iron core for linear compressor motors, air conditioner compressor motors, and high-speed motors for vacuum cleaners. Conversely, when the thickness of the cold-rolled steel sheet exceeds 0.50 mm, it is not possible to secure a large amount of the texture of the (100) plane and the magnetic flux density deteriorates, which is not preferable.

In this step, cold rolling is preferably performed at a reduction ratio of 55% or less, more preferably 45 to 50%. If the rolling reduction of cold rolling exceeds 55%, there is a problem in that the (111) plane texture is strongly developed and the fraction of the (100) plane texture with excellent magnetic properties decreases.

Therefore, in order to suppress the generation of the (111) surface texture and improve the magnetic properties by increasing the generation of the (100) surface texture, the reduction ratio in the cold rolling process is strictly controlled to a reduction ratio of 55% or less. it is desirable

Here, the reduction ratio of cold rolling corresponds to (initial steel sheet thickness - final steel sheet thickness) / (initial steel sheet thickness) × 100. Here, the initial steel sheet is a hot-rolled steel sheet, and the final steel sheet is a cold-rolled steel sheet.

Decarburization annealing heat treatment

In the decarburization annealing heat treatment step (S140), the cold-rolled steel sheet is subjected to decarburization annealing heat treatment under a temperature condition of 780 to 920 °C.

In this step, the decarburization annealing heat treatment is more preferably carried out for 1 to 60 minutes in an H ₂ gas atmosphere under conditions of 780 to 820 ° C.

When the decarburization annealing heat treatment temperature is less than 780 ° C or the decarburization annealing heat treatment time is less than 1 minute, there is a problem in that carbon diffusion is very slow and decarburization is not performed well. Conversely, when the decarburization annealing heat treatment temperature exceeds 920 ° C or the decarburization annealing heat treatment time exceeds 60 minutes, decarburization is not well performed due to the rapid formation of an oxide layer on the surface, and also crystal growth is caused by rapid heating to a high temperature. As it occurs coarsely, the recrystallization structure becomes non-uniform and unstable secondary form recrystallization.

final annealing heat treatment

In the final annealing heat treatment step (S150), the decarburization annealed steel sheet is subjected to final annealing heat treatment at a temperature condition of 980 to 1,020 ° C.

In this step, the final annealing heat treatment is preferably carried out in an Ar gas atmosphere at 980 to 1,020 ° C for 1 to 30 minutes.

If the final annealing heat treatment temperature is less than 980 ° C or the final annealing heat treatment time is less than 1 minute, P and S inside the steel sheet are not sufficiently diffused to the surface, making it difficult to properly exert the effect of strengthening the strength of the (100) plane. Conversely, when the final annealing heat treatment temperature exceeds 1,020 ° C or the final annealing heat treatment time exceeds 30 minutes, there is a problem in that the iron loss increases due to the increase in strength near the Goss texture.

The non-oriented electrical steel sheet according to the embodiment of the present invention manufactured by the above processes (S110 to S150) strictly controls the content ratio of Si, Al, etc., lowers the heat treatment temperature in the decarburization annealing heat treatment and the final annealing heat treatment, By adjusting the gas atmosphere, it is possible to exhibit low iron loss characteristics while lowering the temperature.

In addition, the non-oriented electrical steel sheet manufactured by the method according to the present invention can reduce process costs by lowering the decarburization annealing heat treatment temperature to 780 ~ 920 ° C, more preferably 780 ~ 820 ° C, and reduce the risk of oxidation. can reduce the failure rate.

As a result, the non-oriented electrical steel sheet manufactured by the method according to the present invention is optimized for the texture of the electrical steel sheet by adjusting the temperature and gas atmosphere of the decarburization annealing heat treatment and the final annealing heat treatment after cold rolling, even at a low temperature. Iron loss (W15/50) of ~ 2.15 W/kg and magnetic flux density (B50) of 1.65 ~ 1.80 T can be secured.

In addition, the non-oriented electrical steel sheet manufactured by the method according to the present invention has a tensile strength of 400 ~ 560N / ㎟ and a hardness of 200 ~ 270Hv.

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 by this in any sense.

Contents not described herein can be technically inferred by those skilled in the art, so descriptions thereof will be omitted.

1. Specimen preparation

Specimens according to Examples 1 to 3 and Comparative Examples 1 to 5 were prepared under the composition shown in Table 1 and the process conditions shown in Table 2. Here, the specimens according to Examples 1 to 3 and Comparative Examples 1 to 5 were subjected to reheating of steel slabs having the composition shown in Table 1 at 1,150 ° C, finishing hot rolling at 860 ° C, hot rolling annealing heat treatment at 910 ° C, and 50 After cold rolling at a reduction ratio of %, it was prepared by performing each of the decarburization annealing heat treatment and final annealing heat treatment conditions described in Table 2.

[Table 1] (Unit: % by weight)

[Table 2]

2. Property evaluation

Table 3 shows the iron loss and magnetic flux density measurement results for the specimens according to Examples 1 to 3 and Comparative Examples 1 to 5, and Table 4 shows the results of measuring the iron loss and magnetic flux density for the specimens according to Examples 1 to 3 and Comparative Examples 1 to 5. It shows the result of measuring the value of mechanical properties. At this time, the iron loss W15/50 is the energy loss consumed as heat when a magnetic flux density of 1.5 Tesla is induced in the iron core at 50Hz alternating current, and the magnetic flux density B50 is a value induced by an excitation force of 5000A/m.

[Table 3]

[Table 4]

As shown in Tables 1 to 4, in the case of the specimens according to Examples 1 to 3, despite the fact that the decarburization annealing heat treatment was performed at a low temperature, the core loss (W15/ 50) and a magnetic flux density of 1.65 to 1.80 T (B50).

In particular, in the case of Example 1 in which the decarburization annealing heat treatment was performed by lowering the temperature to 800 ° C in a H ₂ gas atmosphere and the final annealing heat treatment was performed under the condition of 1,000 ° C in an Ar gas atmosphere, the iron loss (W15 / 50) value of 1.87 W / Kg was exhibited and the most It was confirmed that it showed a low value. This is determined to be due to the fact that the texture was changed by lowering the decarburization annealing heat treatment temperature to 800 ° C. to increase the fraction of non-recrystallized crystal grains.

In addition, in the case of the specimens according to Examples 1 to 3, it can be confirmed that both the tensile strength of 400 to 560 N/mm2 and the hardness of 200 to 270 Hv corresponding to the target values are satisfied.

On the other hand, the specimens according to Comparative Examples 1 to 5 satisfied the target values in tensile strength and hardness, but in the case of specimens according to Comparative Examples 1 to 3 subjected to final annealing heat treatment in an H ₂ gas atmosphere, according to Examples 1 to 3 Compared to the specimens, the iron loss value showed a tendency to increase.

In addition, in the case of the specimen according to Comparative Example 4, due to the final annealing heat treatment being performed at 900 ° C., it is determined that the crystal grain size is too small and the iron loss is large.

In addition, in the case of the specimen according to Comparative Example 5, due to the final annealing heat treatment at 1,100 ° C., the crystal grain size increased, but the strength near the Goss texture increased, and it was determined that the iron loss increased.

3. Microstructure analysis

Figure 2 is a photograph showing the results of ODF and IPF analysis through EBSD measurement of the specimen according to Example 1, Figure 3 is the result of ODF and IPF analysis through EBSD measurement of the specimen according to Example 3 This is the picture shown In addition, Figure 4 is a photograph showing the results of ODF and IPF analysis through EBSD measurement for the specimen according to Comparative Example 1, Figure 5 is a photograph showing the results of ODF and IPF analysis through EBSD measurement for the specimen according to Comparative Example 3 This is a picture showing the result.

As shown in FIGS. 2 to 5 , it can be confirmed that the atmosphere in the final annealing heat treatment gives a difference to the texture formation of the electrical steel sheet.

Like the specimens according to Examples 1 and 3, a relatively uniform texture is distributed in the H ₂ gas atmosphere. On the other hand, as in the specimens according to Comparative Examples 1 and 3, in the Ar gas atmosphere, strength around γ-fibers and cube texture was strongly formed.

In addition, when the final annealing heat treatment was performed in an Ar gas atmosphere, it can be confirmed that γ-fibers of the steel sheet subjected to the decarburization annealing heat treatment in the H ₂ gas atmosphere at 900 ° C. were strongly formed, which is due to the recrystallization difference in the final annealing heat treatment step. It is thought that γ-fibers are strongly formed in γ-fibers, and this causes a decrease in iron loss.

On the other hand, Figure 6 is a photograph showing the comparison of the results of ODF and IPF analysis through EBSD measurement for specimens according to Example 1 and Comparative Example 5.

As shown in FIG. 6, as can be seen in the specimens according to Example 1 and Comparative Example 5, it can be seen that iron loss characteristics change with the final annealing heat treatment temperature even in an Ar gas atmosphere.

That is, in the case of the specimen according to Example 1 in which the final annealing heat treatment was performed at 1,000 ° C., compared to Comparative Example 5 in which the final annealing heat treatment was performed at 1,100 ° C., it is determined that the iron loss is lowered due to the decrease in grain size.

On the other hand, in the case of the specimen according to Comparative Example 5, due to the final annealing heat treatment at 1,100 ° C., the crystal grain size was increased, but the strength near the Goss texture was increased and the iron loss was thought to be increased.

As can be seen based on the above experimental results, by lowering the decarburization annealing heat treatment temperature from the existing 1,000 ℃ to 780 ~ 920 ℃ to increase the fraction of non-recrystallized grains to increase the possibility of changing the texture, 980 ~ 1,020 ℃ It was confirmed that a cost-effective electrical steel sheet with excellent iron loss can be produced by final annealing heat treatment in an Ar gas atmosphere.

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

S110: hot rolling step
S120: Hot rolling annealing heat treatment step
S130: Cold rolling step
S140: Decarburization annealing heat treatment step
S150: final annealing heat treatment step

Claims (10)

(a) C: greater than 0 wt% to 0.05 wt% or less, Si: 1.0 to 3.5 wt%, Al: 0.2 to 0.6 wt%, Mn: 0.02 to 0.20 wt%, P: 0.01 to 0.20 wt%, S: 0 More than 0.01% by weight and less than or equal to 0.01% by weight, Cu: more than 0% by weight and less than or equal to 0.03% by weight, Ni: more than 0% by weight and less than or equal to 0.03% by weight, and Cr: more than 0% by weight but less than or equal to 0.05% by weight, with the remainder Fe and unavoidable impurities. After reheating the steel slab comprising a, hot rolling step;
(b) subjecting the hot-rolled steel sheet to hot-rolling annealing heat treatment and pickling;
(c) cold-rolling the pickled steel sheet;
(d) subjecting the cold-rolled steel sheet to a decarburization annealing heat treatment under a temperature condition of 780 to 920° C.; and
(e) subjecting the decarburized annealed steel sheet to a final annealing heat treatment for 1 to 30 minutes in an Ar gas atmosphere at a temperature of 980 to 1,020 ° C;
After the step (e), the steel sheet has a core loss (W15 / 50) of 1.70 ~ 1.90 W / kg and a magnetic flux density (B50) of 1.65 ~ 1.80 T Method of manufacturing a non-oriented electrical steel sheet.
delete According to claim 1,
After step (c),
The electrical steel sheet
Method for manufacturing a non-oriented electrical steel sheet having a thickness of 0.05 to 0.50 mm.
According to claim 1,
In step (d),
The decarburization annealing heat treatment
A non-oriented electrical steel sheet manufacturing method performed for 1 to 60 minutes in an H ₂ gas atmosphere at 780 to 820 ° C.
delete delete C: more than 0 wt% to 0.05 wt% or less, Si: 1.0 to 3.5 wt%, Al: 0.2 to 0.6 wt%, Mn: 0.02 to 0.20 wt%, P: 0.01 to 0.20 wt%, S: more than 0 wt% to 0.01 wt% or less, Cu: more than 0 wt% to 0.03 wt% or less, Ni: more than 0 wt% to 0.03 wt% or less, and Cr: more than 0 wt% to 0.05 wt% or less, and the remainder Fe and unavoidable impurities, ,
Non-oriented electrical steel sheet with iron loss (W15/50) of 1.70 ~ 1.90 W/kg and magnetic flux density (B50) of 1.65 ~ 1.80 T.
delete According to claim 7,
The electrical steel sheet
Non-oriented electrical steel sheet with a thickness of 0.05 ~ 0.50mm.
According to claim 7,
The electrical steel sheet
Non-oriented electrical steel sheet with tensile strength of 400 ~ 560N/㎟ and hardness of 200 ~ 270Hv.

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