KR20240010202A - Non-oriented electrical steel sheet and method for manufacturing the same - Google Patents

Abstract

A method of manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention includes the steps of first hot rolling a first steel material and a second steel material containing silicon (Si), manganese (Mn), and aluminum (Al); Forming a first laminated structure by laminating the first hot rolled first steel material and the second steel material; forming a second laminated structure by performing a second hot rolling on the first laminated structure; Preliminarily annealing the second laminated structure; Forming a third laminated structure by cold rolling the pre-annealed second laminated structure; and cold rolling annealing the third laminated structure.

Description

Non-oriented electrical steel sheet and method of manufacturing the same {NON-ORIENTED ELECTRICAL STEEL SHEET AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to a non-oriented electrical steel sheet and a manufacturing method thereof, and more specifically, to a non-oriented electrical steel sheet with excellent high-frequency iron loss and a manufacturing method thereof.

Electrical steel sheets can be divided into oriented electrical steel sheets and non-oriented electrical steel sheets depending on their magnetic properties. Oriented electrical steel sheet is manufactured to facilitate magnetization in the rolling direction of the steel sheet and has particularly excellent magnetic properties in the rolling direction, so it is mainly used as the iron core of large, small and medium-sized transformers that require low core loss and high magnetic permeability. . In contrast, non-oriented electrical steel sheets have uniform magnetic properties regardless of the direction of the steel sheet, so they are widely used as iron core materials for small electric motors, small power transformers, and stabilizers.

Republic of Korea Patent Publication No. 2015-0001467A

The technical problem to be achieved by the present invention is to provide a non-oriented electrical steel sheet with excellent high-frequency iron loss and a method of manufacturing the same.

However, these tasks are illustrative and do not limit the scope of the present invention.

A method of manufacturing a non-oriented electrical steel sheet according to an aspect of the present invention to solve the above problem involves heating a first steel material and a second steel material containing silicon (Si), manganese (Mn), and aluminum (Al), respectively, in the first hot process. rolling; Forming a first laminated structure by laminating the first hot rolled first steel material and the second steel material; forming a second laminated structure by performing a second hot rolling on the first laminated structure; Preliminarily annealing the second laminated structure; Forming a third laminated structure by cold rolling the pre-annealed second laminated structure; and cold rolling annealing the third laminated structure.

In the method of manufacturing the non-oriented electrical steel sheet, the first laminated structure may further include an intermediate insulating layer interposed between the first steel material and the second steel material.

In the method of manufacturing the non-oriented electrical steel sheet, the intermediate insulating layer may include a scale layer formed on the surface of at least one of the first steel material and the second steel material in the first hot rolling step.

In the method of manufacturing the non-oriented electrical steel sheet, the scale layer may be Fe ₃ O ₄ or Fe ₂ SiO ₄ .

In the method of manufacturing the non-oriented electrical steel sheet, the first steel material and the second steel material include silicon (Si): 2.8 to 3.8% by weight, manganese (Mn): more than 0 and less than 0.5% by weight, and aluminum (Al): 0.5 to 0.5% by weight. 1.2% by weight, Carbon (C): more than 0 and less than 0.002% by weight, phosphorus (P): more than 0 and less than 0.015% by weight, sulfur (S): more than 0 and less than 0.002% by weight, nitrogen (N): more than 0 and less than 0.002% by weight Hereinafter, titanium (Ti): may contain more than 0 and less than 0.002% by weight, and the remainder may include iron (Fe) and other unavoidable impurities.

In the method of manufacturing the non-oriented electrical steel sheet, the first hot rolling step includes hot rolling under the conditions of a reheating temperature of 1100 to 1200°C and a rolling temperature of 900 to 1000°C, and the second hot rolling The step includes hot rolling under the conditions of reheating temperature: 1100 to 1200°C, rolling temperature: 800 to 1000°C, and coiling temperature: 560 to 600°C, and the preliminary annealing step is performed at a temperature increase rate of 10°C/s. Above, annealing under the conditions of annealing temperature: 900 ~ 1100℃, holding time: 30 ~ 90 seconds, and cooling under the conditions of cooling rate: 20℃/s or more, and the cold rolling annealing step includes the temperature increase rate: It may include annealing under the conditions of 10°C/s or more, annealing temperature: 900 to 1100°C, holding time: 30 to 90 seconds, and cooling under the conditions of cooling rate: 30°C/s or more.

In the method of manufacturing the non-oriented electrical steel sheet, the first hot rolling step consists of a rough rolling step, wherein the first steel material and the second steel material are each rolled from a thickness of 200 to 300 mm to a thickness of 100 to 150 mm. Includes, wherein the second hot rolling step is sequentially comprised of a rough rolling step and a finishing rolling step, and the step of forming the second laminated structure by rolling the first laminated structure to a thickness of 1.6 to 2.6 mm. Including, the cold rolling step may include forming the third laminated structure by rolling the second laminated structure to a thickness of 0.4 to 0.6 mm.

In the method of manufacturing the non-oriented electrical steel sheet, the first laminated structure further includes an intermediate insulating layer interposed between the first steel material and the second steel material and made of a scale layer formed in the first hot rolling step, The thickness of the intermediate insulating layer may be 1 to 3 mm in the first laminated structure, 10 to 30 ㎛ in the second laminated structure, and greater than 1 ㎛ and 3 ㎛ or less in the third laminated structure.

A non-oriented electrical steel sheet according to another aspect of the present invention for solving the above problems includes a first steel material and a second steel material arranged in a stack; and an intermediate insulating layer interposed between the first steel material and the second steel material, wherein the intermediate insulating layer is a hot rolled scale formed on at least one of the first steel material and the second steel material. It is characterized by being a layer.

In the non-oriented electrical steel sheet, the first steel material and the second steel material include silicon (Si): 2.8 to 3.8 wt%, manganese (Mn): more than 0 and 0.5 wt% or less, and aluminum (Al): 0.5 to 1.2 wt%. , Carbon (C): more than 0 and less than 0.002% by weight, phosphorus (P): more than 0 and less than 0.015% by weight, sulfur (S): more than 0 and less than 0.002% by weight, nitrogen (N): more than 0 and less than 0.002% by weight, titanium (Ti): may contain more than 0 and less than 0.002% by weight, and the remaining iron (Fe) and other unavoidable impurities.

In the non-oriented electrical steel sheet, the final thickness of the laminated structure is 0.4 to 0.6 mm, the final thickness of the intermediate insulating layer is more than 1 μm and less than 3 μm, and the iron loss (W _10/400 ) is less than 14.0 W/kg. It has a magnetic flux density (B ₅₀ ) of 1.6T or more.

According to an embodiment of the present invention, a non-oriented electrical steel sheet with excellent high-frequency iron loss and a method for manufacturing the same can be provided.

Of course, the scope of the present invention is not limited by this effect.

1 is a flowchart showing a method of manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention.
Figure 2 is a diagram schematically illustrating a method of manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention.
Figure 3 is a photograph of a partial cross-section of a laminated structure according to another embodiment of the present invention.

A method for manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention will be described in detail. The terms described below are terms appropriately selected in consideration of their functions in the present invention, and definitions of these terms should be made based on the content throughout the present specification.

Generally, electrical steel is divided into oriented electrical steel and non-oriented electrical steel. Grain-oriented electrical steel sheets are mainly used in stationary equipment such as transformers, while non-oriented electrical steel sheets are mainly used in rotating equipment such as motors. The properties of electrical steel can be evaluated by magnetic flux density and iron loss. Magnetic flux density is mainly evaluated as B ₅₀ , and iron loss is generally evaluated as W _15/50 , but in cases where high frequency characteristics are required, such as in electric vehicles, it is evaluated as W _10/400 . there is. B ₅₀ represents the magnetic flux density at 5000A/m, W _15/50 represents the iron loss at 50Hz and 1.5T, and W _10/400 represents the iron loss at 400Hz and 1.0T.

Due to policies to reduce _CO2 emissions to prevent global warming, existing internal combustion engine vehicles are rapidly being replaced by eco-friendly vehicles (hybrid vehicles (HEV), electric vehicles (EV)), especially electric vehicles (EV). In response to the increasing demand for electric vehicles (EVs), the energy conversion of electric vehicle drive motors is becoming more efficient, and for this purpose, excellent magnetic properties of motor core materials are required. Non-oriented electrical steel used as a motor core material plays a role in converting electrical energy into mechanical energy in rotating machines, and for energy saving, it is important to have its magnetic properties, that is, low iron loss and high magnetic flux density. In particular, non-oriented electrical steel sheets with low core loss at high frequencies (400 Hz) are required to increase motor efficiency at high speeds where energy loss is high. In response to these demands, non-oriented electrical steel products are being developed to improve resistivity or make materials thinner by adding elements such as silicon (Si), manganese (Mn), and aluminum (Al). However, when alloy elements such as silicon (Si), manganese (Mn), and aluminum (Al) increase, rolling becomes difficult and thinning becomes difficult, and when the thickness of the electrical steel sheet is reduced, production costs increase and productivity decreases. There is a problem.

In the present invention, a method for producing a non-oriented electrical steel sheet having excellent high-frequency iron loss characteristics while producing a thick material of 0.4 mmt or more, which can suppress the decrease in production yield and increase in production cost due to the thinning of the product, and a laminated structure using the same are provided. I would like to present it.

Figure 1 is a flowchart showing a method of manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention, and Figure 2 is a diagram schematically illustrating a method of manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention.

Referring to Figures 1 and 2, the method of manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention includes a first steel material 11 containing silicon (Si), manganese (Mn), and aluminum (Al) and a first steel material 11 containing silicon (Si), manganese (Mn), and aluminum (Al). A first hot rolling step of each of the two steel materials 12 (S10); Forming a first laminated structure 10 by laminating the first hot rolled first steel 11 and the second steel 12 (S20); Forming a second laminated structure 20 by performing a second hot rolling of the first laminated structure 10 (S30); Preliminarily annealing the second laminated structure 20 (S40); Forming a third laminated structure 30 by cold rolling the pre-annealed second laminated structure 20 (S50); and a step of cold rolling annealing the third laminated structure 30 (S60).

First hot rolling step (S10)

The first steel material 11 and the second steel material 12 input into the first hot rolling process are steel materials for manufacturing non-oriented electrical steel sheets, and for example, silicon (Si): 2.8 to 3.8% by weight, manganese ( Mn): more than 0 and less than 0.5% by weight, aluminum (Al): 0.5 to 1.2% by weight, carbon (C): more than 0 and less than 0.002% by weight, phosphorus (P): more than 0 and less than 0.015% by weight, sulfur (S): Nitrogen (N): 0.002% by weight or less above 0, Titanium (Ti): 0.002% by weight or less above 0, and the remaining iron (Fe) and other inevitable impurities. However, the method of manufacturing a non-oriented electrical steel sheet according to the technical idea of the present invention is not limited by this example of composition range, and can be expanded to any composition range that can perform the function of a non-oriented electrical steel sheet. Below, the role and content of exemplary composition components to which the method for manufacturing a non-oriented electrical steel sheet according to the technical idea of the present invention can be applied will be described.

Silicon (Si): 2.8 to 3.8% by weight

Silicon (Si) is a major added element that increases resistivity and lowers iron loss (eddy current loss). If the silicon addition amount is low, below 2.8% by weight, it becomes difficult to obtain the desired low core loss value, and as the addition amount increases, the magnetic permeability and magnetic flux density decrease. Additionally, if the amount of silicon added exceeds 3.8% by weight, brittleness increases, making cold rolling difficult and productivity decreasing.

Manganese (Mn): greater than 0 and less than or equal to 0.5% by weight

Manganese (Mn), along with silicon, increases resistivity and improves texture. If manganese is added in excess of 0.5% by weight, coarse MnS precipitates are formed and magnetic properties are deteriorated, such as reducing magnetic flux density. Furthermore, when the manganese content exceeds 0.5% by weight, the reduction in iron loss is small compared to the addition amount, but cold rolling properties are significantly reduced. Furthermore, if the manganese content is less than 0.2% by weight, fine MnS precipitates may be formed and grain growth may be suppressed. More strictly, the composition range of manganese may be adjusted to 0.2 to 0.5% by weight.

Aluminum (Al): 0.5 to 1.2% by weight

Aluminum (Al) is a major added element that, along with silicon, increases resistivity and lowers iron loss (eddy current loss). Aluminum plays a role in reducing magnetic deviation by reducing magnetic anisotropy. Aluminum meets nitrogen and induces AlN precipitation. If the aluminum content is less than 0.5% by weight, it is difficult to expect the above-mentioned effect, and fine nitrides may be formed, which may increase the variation in magnetic properties. If the aluminum content exceeds 1.2% by weight, cold rolling properties are deteriorated, and Excessive nitride formation reduces magnetic flux density and deteriorates magnetic properties.

Carbon (C): greater than 0 and less than or equal to 0.002% by weight

Carbon (C) is an element that increases iron loss by forming carbides such as TiC and NbC. The smaller the carbon, the more desirable it is, and it is limited to 0.002% by weight or less. If the carbon content exceeds 0.002% by weight, self-aging occurs and magnetic properties deteriorate, and if the carbon content is less than 0.002% by weight, the self-aging phenomenon is suppressed.

Phosphorus (P): greater than 0 and less than or equal to 0.015% by weight

Phosphorus (P) is a grain boundary segregation element that develops texture. If the phosphorus content exceeds 0.015% by weight, grain growth is suppressed due to the segregation effect, magnetic properties are deteriorated, and cold rolling properties are deteriorated.

Sulfur (S): greater than 0 and less than or equal to 0.002% by weight

Sulfur (S) increases iron loss by forming precipitates such as MnS and CuS, and suppresses grain growth, so its addition is limited to 0.002% by weight or less. If the sulfur content exceeds 0.003% by weight, the problem of increased iron loss occurs.

Nitrogen (N): greater than 0 and less than or equal to 0.002% by weight

Nitrogen (N) increases iron loss by forming precipitates such as AlN, Tin, and NbN, and suppresses grain growth, so its addition is limited to 0.002% by weight or less. If the nitrogen content exceeds 0.002% by weight, the problem of increased iron loss occurs.

Titanium (Ti): More than 0 and less than 0.002% by weight

Titanium (Ti) suppresses grain growth by forming fine precipitates such as TiC and TiN. The magnetic properties deteriorate as titanium is added, so the addition is limited to as low as possible and limited to 0.002% by weight or less. If the titanium content exceeds 0.002% by weight, the problem of magnetic properties deterioration occurs.

The first steel material 11 and the second steel material 12 having the above-described composition are each subjected to a first hot rolling process. The first hot rolling process includes a rough rolling process but does not include a finishing rolling process. The first hot rolling step (S100) of the steel is a rough rolling step and may include hot rolling under the conditions of a reheating temperature of 1100 to 1200°C and a rolling temperature of 900 to 1000°C.

If the slab reheating temperature exceeds 1200°C, precipitates such as C, S, and N in the slab may be re-dissolved and fine precipitates may be generated during the subsequent rolling and annealing process, suppressing grain growth and deteriorating magnetism. If the slab reheating temperature is less than 110°C, the rolling load increases, and since the intermediate insulating layer 13 has a thickness of 1㎛ or less in the final product, a problem of increased iron loss may occur.

The first hot rolling step (S10) may include rolling the first steel material 11 and the second steel material 12 from a thickness of 200 to 300 mm to a thickness t1 of 100 to 150 mm. .

First layered structure forming step (S20)

Referring to (a) of FIG. 2, a first laminated structure 10 can be formed by laminating the first hot rolled first steel 11 and the second steel material 12.

The first laminated structure 10 may further include an intermediate insulating layer 13 interposed between the first steel material 11 and the second steel material 12. The intermediate insulating layer 13 may include a scale layer formed on the surface of at least one of the first steel material 11 and the second steel material 12 in the first hot rolling step (S10). The scale layer may be Fe ₃ O ₄ or Fe ₂ SiO ₄ . The thickness of the intermediate insulating layer 13 may be 1 to 3 mm in the first layered structure 10.

Second hot rolling to form a second laminated structure (S30)

Referring to (b) of FIG. 2, the first laminated structure 10 may be subjected to a second hot rolling to form the second laminated structure 20. The second hot rolling process is characterized by sequentially including a rough rolling process and a finishing rolling process. Here, the rough rolling process of the second hot rolling process is distinguished from the rough rolling process of the first hot rolling process in that the rolling object is different.

The second hot rolling step (S30) may include hot rolling under the conditions of reheating temperature: 1100 to 1200°C, rolling temperature: 800 to 1000°C, and coiling temperature: 560 to 600°C.

The second hot rolling step (S30) may include forming the second laminated structure 20 by rolling the first laminated structure 10 to a thickness (t2) of 1.6 to 2.6 mm. You can. The thickness of the intermediate insulating layer 13 may be 10 to 30 ㎛ in the second laminated structure 20.

Preliminary annealing treatment step (S40)

The second laminated structure 20 may be subjected to preliminary annealing. The preliminary annealing step (S40) is annealing under the conditions of temperature increase rate: 10°C/s or more, annealing temperature: 900 to 1100°C, holding time: 30 to 90 seconds, and cooling rate: 20°C/s or more. It may include a cooling step.

Forming a third laminated structure by cold rolling (S50)

Referring to (c) of FIG. 2, the third laminated structure 30 may be formed by cold rolling the pre-annealed second laminated structure 20.

The cold rolling step may include forming the third laminated structure 30 by rolling the second laminated structure 20 to a thickness t3 of 0.4 to 0.6 mm (S50). The reduction rate of cold rolling may be 60 to 85%.

The thickness of the intermediate insulating layer 13 may be greater than 1 μm and less than or equal to 3 μm in the third laminated structure 30.

Cold rolled annealing treatment step (S60)

The third laminated structure 30 may be subjected to cold rolling annealing. The cold rolling annealing step (S60) is annealing under the conditions of temperature increase rate: 10°C/s or more, annealing temperature: 900 to 1100°C, holding time: 30 to 90 seconds, and cooling rate: 30°C/s or more. It may include a cooling step.

Cold rolling annealing is performed with the cold rolled sheet obtained after cold rolling. The temperature that results in the optimal grain size is applied considering the improvement of iron loss and mechanical properties. In cold rolling annealing, heating is performed under mixed atmosphere conditions to prevent surface oxidation and nitriding. The surface condition becomes smoother through a mixed atmosphere of nitrogen and hydrogen. If the cold rolling annealing temperature is less than 900°C, the grain size may be fine and hysteresis loss may increase, and if the cold rolling annealing temperature exceeds 1100°C, the grain size may become coarse and eddy current loss may increase.

Referring to (d) of FIG. 2, a coating process may be performed to form the insulating coating layer 15 after final annealing. By forming the insulating coating layer 15, improved punching properties and insulation properties can be secured. The thickness of the insulating coating layer 15 formed on the upper part of the third laminated structure 30 is about 1 to 2 ㎛, and the thickness of the insulating coating layer 15 formed on the lower part of the third laminated structure 30 is also about 1 to 2 ㎛. It can be.

Referring to FIG. 3 , which is an enlarged image of area A indicated in (d) of FIG. 2 showing the final product, the final product is a non-oriented electrical steel sheet, including a first steel material and a second steel material arranged in a stack; It can be confirmed that it is a laminated structure including; and an intermediate insulating layer interposed between the first steel material and the second steel material.

The intermediate insulating layer is a hot-rolled scale layer formed on at least one of the first steel and the second steel, and the final thickness of the laminated structure is 0.4 to 0.6 mm, and the final thickness of the intermediate insulating layer is 1. It is greater than ㎛ and 3㎛ or less, and can have an iron loss (W _10/400 ) of 14.0 W/kg or less and a magnetic flux density (B ₅₀ ) of 1.6T or more.

The non-oriented electrical steel sheet implemented by the above-described manufacturing method includes a first steel material and a second steel material arranged in a laminated manner; and an intermediate insulating layer interposed between the first steel material and the second steel material, wherein the intermediate insulating layer is formed on at least one of the first steel material and the second steel material. It is characterized by being a hot-rolled scale layer. The first steel material and the second steel material are each subjected to a hot rolling process before and after forming the laminated structure. That is, the hot rolling process performed before forming the laminated structure can be distinguished as a first hot rolling process, and the hot rolling process performed after forming the laminated structure can be distinguished as a second hot rolling process. The first hot rolling process consists of a rough rolling process and does not include a finishing rolling process. The second hot rolling process may sequentially include a rough rolling process and a finishing rolling process.

Experiment example

Below, preferred experimental examples are presented to aid understanding of the present invention. However, the following experimental examples are only intended to aid understanding of the present invention, and the present invention is not limited by the following experimental examples.

1. Composition of the Psalm

In this experimental example, specimens having the alloy element composition (unit: weight%) shown in Table 1 are provided.

Si Mn Al C P S N Ti Bal. 3.3 0.3 0.9 0.0018 0.0055 0.0021 0.0019 0.0020 Fe

Referring to Table 1, the composition of the non-oriented electrical steel sheet according to the experimental example is silicon (Si): 2.8 to 3.8% by weight, manganese (Mn): more than 0 and less than 0.5% by weight, and aluminum (Al): 0.5 to 1.2% by weight. , Carbon (C): more than 0 and less than 0.002% by weight, phosphorus (P): more than 0 and less than 0.015% by weight, sulfur (S): more than 0 and less than 0.002% by weight, nitrogen (N): more than 0 and less than 0.002% by weight, titanium (Ti): Satisfies more than 0 and less than 0.002% by weight and the remaining iron (Fe).

2. Evaluation of process conditions and physical properties

hot acting
method 1st hot-rolled railway
Reheating temperature
(℃) hot rolled thickness
(mm) Cold rolling reduction rate
(%) final thickness
(mm) Presence or absence of intermediate oxidation layer Medium oxide layer thickness
(㎛) iron loss magnetic flux density Experimental Example 1 S/S 1150 2.0 87.5 0.25 X - 12.7 1.66 Experimental Example 2 M/L 1150 2.0 75.0 0.50 O 2.5 12.9 1.67 Experimental Example 3 M/L 1080 2.0 75.0 0.50 O 1.0 14.5 1.65

In Table 2, S/S (Single Sheet) in the heat annealing method corresponds to hot rolling (single sheet hot rolling) on a single sheet of steel, and M/L (Multi Layer) in the heat annealing method refers to 2 layers. The case of performing hot rolling corresponds to the case of performing the first hot rolling and the second hot rolling described in FIGS. 1 and 2. The hot rolled thickness item refers to the thickness after hot rolling is completed before cold rolling, and the final thickness item refers to the thickness after cold rolling is completed. The presence or absence of the intermediate oxide layer and the thickness refer to the presence or absence of the intermediate insulating layer 13 and the final thickness described above. means. Iron loss means iron loss (W _10/400 ) whose unit is W/kg, and magnetic flux density means magnetic flux density (B ₅₀ ) whose unit is T.

Referring to Table 2, Experimental Example 1, which performs single plate hot rolling, which is a typical process, requires a final thickness of 0.25 mm to ensure iron loss (W _10/400 ) of 14.0 W/kg or less. On the other hand, Experimental Example 2, in which two-ply hot rolling was performed according to the technical idea of the present invention, secured an iron loss (W _10/400 ) of 13.0 W/kg or less at a final thickness of 0.50 mm. The oxide layer, which is the intermediate insulating layer 13 formed in the center of the specimen, had the effect of insulating the upper and lower plates, thereby reducing iron loss. In Experimental Example 3, an intermediate insulating layer was formed through two-ply hot rolling as in Experimental Example 2, but it is judged that the iron loss increased because the thickness was not sufficient.

So far, a method for manufacturing a non-oriented electrical steel sheet according to the technical idea of the present invention has been described. The present invention seeks to provide a method of manufacturing a non-oriented electrical steel sheet with excellent high-frequency iron loss at a thickness of 0.40 mm or more by forming an insulating oxide layer (Fe ₃ O ₄ , Fe ₂ SiO ₄ ) in the middle. Bars are manufactured by performing first hot rolling (rough rolling) on two or more slabs, and stacking two or more first hot rolling (rough rolling) bars for two or more layers. By performing the second hot rolling (rough rolling and finishing rolling), a multi-layer hot rolled sheet with an insulating oxide layer formed in the middle is manufactured. By annealing this multi-layer hot-rolled sheet and then cold rolling it, a method of manufacturing a non-oriented electrical steel sheet with a thickness of more than twice that of the existing single-plate cold-rolled non-oriented electrical steel sheet and having the same level of high-frequency iron loss is provided. Since high-frequency iron loss can be secured at a thickness of 0.40 mm or more, the decrease in production yield and increase in production cost due to thinning can be suppressed.

The effect that can be achieved through the present invention is that it is possible to secure excellent high-frequency iron loss in products with a thickness of 0.4 to 0.6 mm by securing an insulating layer in the middle of the product. When producing a thinner specimen from a single specimen, productivity decreases and process costs increase. However, in the present invention, the thinning effect can be secured even in products with a thickness of 0.4mm or more, which is the thicker material, thereby improving productivity and reducing process costs.

Although the above description focuses on the embodiments of the present invention, various changes and modifications can be made at the level of those skilled in the art. These changes and modifications can be said to belong to the present invention as long as they do not depart from the scope of the present invention. Therefore, the scope of rights of the present invention should be determined by the claims described below.

Claims (11)

First hot rolling a first steel material and a second steel material containing silicon (Si), manganese (Mn), and aluminum (Al);
Forming a first laminated structure by laminating the first hot rolled first steel material and the second steel material;
forming a second laminated structure by performing a second hot rolling on the first laminated structure;
Preliminarily annealing the second laminated structure;
Forming a third laminated structure by cold rolling the pre-annealed second laminated structure; and
Including, cold rolling annealing the third laminated structure.
Method for manufacturing non-oriented electrical steel sheet. According to claim 1,
The first laminated structure further includes an intermediate insulating layer interposed between the first steel material and the second steel material,
Method for manufacturing non-oriented electrical steel sheet. According to claim 2,
The intermediate insulating layer includes a scale layer formed on the surface of at least one of the first steel material and the second steel material in the first hot rolling step,
Method for manufacturing non-oriented electrical steel sheet. According to claim 3,
Characterized in that the scale layer is Fe ₃ O ₄ or Fe ₂ SiO ₄ .
Method for manufacturing non-oriented electrical steel sheet. According to claim 1,
The first steel material and the second steel material contain silicon (Si): 2.8 to 3.8% by weight, manganese (Mn): more than 0 and less than or equal to 0.5% by weight, aluminum (Al): 0.5 to 1.2% by weight, and carbon (C): 0. Exceeding 0.002% by weight or less, phosphorus (P): exceeding 0 and not exceeding 0.015% by weight, sulfur (S): exceeding 0 and not exceeding 0.002% by weight, nitrogen (N): exceeding 0 and not exceeding 0.002% by weight, titanium (Ti): exceeding 0 and not exceeding 0.002% by weight Containing less than % by weight and the remainder of iron (Fe) and other unavoidable impurities, respectively,
Method for manufacturing non-oriented electrical steel sheet. According to claim 5,
The first hot rolling step includes hot rolling under the conditions of reheating temperature: 1100 to 1200°C and rolling temperature: 900 to 1000°C,
The second hot rolling step includes hot rolling under the conditions of reheating temperature: 1100 to 1200°C, rolling temperature: 800 to 1000°C, coiling temperature: 560 to 600°C,
The preliminary annealing step includes annealing under the conditions of temperature increase rate: 10°C/s or more, annealing temperature: 900 to 1100°C, holding time: 30 to 90 seconds, and cooling under the conditions of cooling rate: 20°C/s or more. Including,
The cold rolling annealing step includes annealing under the conditions of temperature increase rate: 10°C/s or more, annealing temperature: 900 to 1100°C, holding time: 30 to 90 seconds, and cooling under the conditions of cooling rate: 30°C/s or more. Including,
Method for manufacturing non-oriented electrical steel sheet. According to claim 6,
The first hot rolling step consists of a rough rolling step and includes rolling the first steel material and the second steel material from a thickness of 200 to 300 mm to a thickness of 100 to 150 mm, respectively,
The second hot rolling step consists of a rough rolling step and a finishing rolling step, and includes the step of rolling the first laminated structure to a thickness of 1.6 to 2.6 mm to form the second laminated structure,
The cold rolling step includes forming the third laminated structure by rolling the second laminated structure to a thickness of 0.4 to 0.6 mm.
Method for manufacturing non-oriented electrical steel sheet. According to claim 7,
The first laminated structure further includes an intermediate insulating layer interposed between the first steel material and the second steel material and made of a scale layer formed in the first hot rolling step,
The thickness of the intermediate insulating layer is 1 to 3 mm in the first laminated structure, 10 to 30 ㎛ in the second laminated structure, and greater than 1 ㎛ and 3 ㎛ or less in the third laminated structure,
Method for manufacturing non-oriented electrical steel sheet. A first steel material and a second steel material arranged in a stacked manner; and an intermediate insulating layer interposed between the first steel material and the second steel material,
Characterized in that the intermediate insulating layer is a hot-rolled scale layer formed on at least one of the first steel material and the second steel material,
Non-oriented electrical steel sheet. According to clause 9,
The first steel material and the second steel material contain silicon (Si): 2.8 to 3.8% by weight, manganese (Mn): more than 0 and less than or equal to 0.5% by weight, aluminum (Al): 0.5 to 1.2% by weight, and carbon (C): 0. Exceeding 0.002% by weight or less, phosphorus (P): exceeding 0 and not exceeding 0.015% by weight, sulfur (S): exceeding 0 and not exceeding 0.002% by weight, nitrogen (N): exceeding 0 and not exceeding 0.002% by weight, titanium (Ti): exceeding 0 and not exceeding 0.002% by weight Containing less than % by weight and the remainder of iron (Fe) and other unavoidable impurities, respectively,
Non-oriented electrical steel sheet. According to claim 10,
The final thickness of the laminated structure is 0.4 to 0.6 mm, and the final thickness of the intermediate insulating layer is more than 1 ㎛ and 3 ㎛ or less,
With iron loss (W _10/400 ) of less than 14.0W/kg and magnetic flux density (B ₅₀ ) of more than 1.6T
Non-oriented electrical steel sheet.