KR20240013555A - 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 hot rolling first and second steel materials containing silicon (Si), manganese (Mn), and aluminum (Al), respectively; forming a first laminated structure by laminating the hot rolled first steel material and the second steel material with an intermediate layer made of ferrosilicon; Cold rolling the first laminated structure to form a second laminated structure; and cold rolling annealing the cold rolled second 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 capable of securing a uniform texture, high floor space ratio, and productivity, 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 characteristics 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 embodiment of the present invention to solve the above problem involves hot rolling a first steel material and a second steel material containing silicon (Si), manganese (Mn), and aluminum (Al), respectively. steps; forming a first laminated structure by laminating the hot rolled first steel material and the second steel material with an intermediate layer made of ferrosilicon; Cold rolling the first laminated structure to form a second laminated structure; and cold rolling annealing the cold rolled second laminated structure.

In the method of manufacturing the non-oriented electrical steel sheet, the ferrosilicon may be composed of silicon and iron, with silicon (Si): 6 to 50% by weight and the remainder may be iron (Fe).

In the method of manufacturing the non-oriented electrical steel sheet, after the cold rolling annealing step, the content of silicon in the non-oriented electrical steel sheet may be gradually lowered in the direction from the intermediate layer to the first steel material and in the direction to the second steel material. there is.

In the method of manufacturing the non-oriented electrical steel sheet, the first steel material and the second steel material include carbon (C): greater than 0 and less than or equal to 0.003 wt%, silicon (Si): 2.8 to 3.8 wt%, and manganese (Mn): 0.2 to 0.2 wt%. 0.5% by weight, aluminum (Al): 0.5 to 1.5% by weight, phosphorus (P): more than 0 and less than 0.015% by weight, sulfur (S): more than 0 and less than 0.003% by weight, nitrogen (N): more than 0 and less than 0.003% by weight , Titanium (Ti): may contain more than 0 and less than 0.003% by weight, and the remaining iron (Fe) and other inevitable impurities.

The non-oriented electrical steel sheet according to an embodiment of the present invention to solve the above problem contains silicon (Si), manganese (Mn), and aluminum (Al), respectively, but has ferro ferrite between the first and second hot-rolled steels. A laminated structure laminated with an intermediate layer made of silicon is implemented by cold rolling and cold rolling annealing.

In the non-oriented electrical steel sheet, the ferrosilicon is made of silicon and iron, and may contain 6 to 50% by weight of silicon (Si) and the remainder may be iron (Fe).

In the non-oriented electrical steel sheet, the silicon content may gradually decrease in the direction from the intermediate layer to the first steel material and to the second steel material.

In the non-oriented electrical steel sheet, the first steel material and the second steel material include carbon (C): greater than 0 and less than or equal to 0.003 wt%, silicon (Si): 2.8 to 3.8 wt%, and manganese (Mn): 0.2 to 0.5 wt%. , Aluminum (Al): 0.5 to 1.5% by weight, phosphorus (P): more than 0 and less than 0.015% by weight, sulfur (S): more than 0 and less than 0.003% by weight, nitrogen (N): more than 0 and less than 0.003% by weight, titanium ( Ti): may contain more than 0 and less than 0.003% by weight, and the remaining iron (Fe) and other unavoidable impurities.

According to an embodiment of the present invention, a non-oriented electrical steel sheet with excellent high-frequency iron loss characteristics 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 diagram schematically illustrating the distribution of silicon content centered on the middle layer in a non-oriented electrical steel sheet according to an 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.

Recently, as a response to global environmental issues, technology is rapidly changing to hybrid vehicles (HEV)/electric vehicles (EV)/hydrogen vehicles to replace existing internal combustion engines, and in the case of electric vehicles, High-efficiency, high-frequency iron loss (W _10/400 ) characteristics are required.

As a way to improve iron loss, it is possible to improve resistivity by adding elements such as silicon (Si), manganese (Mn), and aluminum (Al), or by making the material thinner. 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, the production cost increases and productivity decreases. It has the disadvantage of decreasing

Figure 1 is a flow chart 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. Figure 3 is a diagram schematically illustrating the distribution of silicon content centered on the middle layer in 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) a first steel material (11) containing silicon (Si), manganese (Mn), and aluminum (Al); ) and the second steel material 12, respectively, hot rolling (S100); (b) forming a first laminated structure 10 in which the hot rolled first steel 11 and the second steel 12 are laminated with an intermediate layer 13 made of ferrosilicon (S200). ; Cold rolling the first laminated structure to form a second laminated structure 20 (S300); and cold-rolling annealing the cold-rolled second laminated structure 20 (S400).

Hot rolling step (S100)

The first steel material 11 and the second steel material 12 are steel materials for manufacturing non-oriented electrical steel sheets, for example, carbon (C): more than 0 and less than 0.003% by weight, silicon (Si): 2.8 to 3.8% by weight. %, manganese (Mn): 0.2 to 0.5% by weight, aluminum (Al): 0.5 to 1.5% by weight, phosphorus (P): more than 0 and less than 0.015% by weight, sulfur (S): more than 0 and less than 0.003% by weight, nitrogen ( N): exceeds 0 and does not exceed 0.003% by weight, titanium (Ti): exceeds 0 and does not exceed 0.003% by weight, and the remainder includes iron (Fe) and other unavoidable 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.

Carbon (C): greater than 0 and less than or equal to 0.003% 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 0.003% by weight or less. If the carbon content exceeds 0.003% by weight, self-aging occurs and magnetic properties deteriorate, and if the carbon content is less than 0.003% by weight, the self-aging phenomenon is suppressed.

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): 0.2 to 0.5% by weight

Manganese (Mn), along with silicon, increases resistivity and improves texture. When manganese is added in amounts of less than 0.2% by weight, it forms fine MnS precipitates to suppress grain growth, and when added in excess of 0.5% by weight, coarse MnS precipitates are formed, which reduces magnetic flux density and deteriorates magnetic properties. 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.

Aluminum (Al): 0.5 to 1.5% 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 effects, and fine nitrides may be formed, which may increase the variation in magnetic properties. If the aluminum content exceeds 1.5% by weight, cold rolling properties are deteriorated, and Excessive nitride formation reduces magnetic flux density and deteriorates magnetic properties.

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 0.003% 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 0.003% 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 0.003% 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 0.003% by weight or less. If the nitrogen content exceeds 0.003% by weight, the problem of increased iron loss occurs.

Titanium (Ti): More than 0 and less than 0.003% 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 0.003% by weight or less. If the titanium content exceeds 0.003% 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 each undergo a hot rolling process.

The step of hot rolling the steel (S100) includes reheating the steel under reheating temperature (SRT) conditions of 1110 to 1250°C, hot rolling under finish rolling temperature (FDT) conditions of 800 to 900°C, and 560 to 600°C. It may include the step of winding at a coiling temperature (CT) of ℃.

If the slab reheating temperature exceeds 1250°C, precipitates such as C, S, and N in the slab may be re-dissolved and fine precipitates may be generated in the subsequent rolling and annealing process, suppressing grain growth and deteriorating magnetism. If the slab reheating temperature is less than 1110℃, the rolling load increases. More preferably, the slab reheating temperature can be set to 1110 to 1250°C.

The thickness (t1) of the hot rolled first steel material 11 and the second steel material 12 may be 1.6 to 2.6 mm, respectively. As the thickness of the hot-rolled sheet increases, the cold rolling reduction rate increases and the texture becomes inferior, so it is desirable to set the thickness to 2.6 mm or less.

First layered structure forming step (S200)

Referring to (b) of FIG. 2, a first laminated structure 10 is laminated between hot rolled first steel materials 11 and second steel materials 12 with an intermediate layer 13 made of ferrosilicon. form The thickness of the intermediate layer 13 may be, for example, 1.5 to 2.5 μm, and the thickness t2 of the first laminated structure 10 may be, for example, 3.2 to 5.2 mm.

The ferrosilicon is an iron alloy made of silicon and iron. For example, it may be made of silicon (Si): 6 to 50% by weight and the remainder is iron (Fe).

Silicon constituting ferrosilicon may diffuse into the first steel material 11 and the second steel material 12 due to the subsequent cold rolling annealing process. Meanwhile, in a modified embodiment of the present invention, a separate heat treatment process other than the cold rolling annealing process may be performed so that the silicon constituting the ferrosilicon diffuses into the first steel material 11 and the second steel material 12.

On the other hand, if the silicon content in the ferrosilicon constituting the intermediate layer 13 is less than 6% by weight, the effect of reducing iron loss of the final non-oriented electrical steel sheet is minimal, and if the silicon content exceeds 50% by weight, the intermediate layer composed of ferrosilicon Excessive diffusion of silicon from the surface of the non-oriented electrical steel sheet may increase surface brittleness, resulting in poor punching and poor coating.

The bonding force between the intermediate layer 13 made of ferrosilicon and the first steel material 11 or the second steel material 12 is increased when a pressing force is applied in the subsequent cold rolling process and silicon diffuses from the ferrosilicon in the subsequent cold rolling annealing process. , It is due to homogeneous bonding in which the iron constituting the ferrosilicon and the iron constituting the first steel material 11 or the second steel material 12 are joined. According to this homogeneous bonding, in constructing the first laminated structure 10, the intermediate layer 13 made of ferrosilicon is introduced, thereby interposing the intermediate layer 13 between the first steel material 11 and the second steel material 12. A beneficial effect can be expected in that there is no need to additionally form a separate bonding layer.

On the other hand, if the middle layer 13 is composed of silicon oxide, which is a ceramic, rather than ferrosilicon, the bonding between silicon oxide, which is an insulating material, and the first steel material 11 or the second steel material 12 is due to instability of the interface due to heterogeneous bonding. It becomes defective. In the case of homogeneous bonding in which the middle layer 13 is made of ferrosilicon, the bonding force between the middle layer 13 and the first steel material 11 or the second steel material 12 is higher than in the case of heterogeneous bonding in which the middle layer 13 is made of silicon oxide. Significantly improved effects can be expected.

Second layered structure forming step (S300)

Referring to (c) of FIG. 2, the second laminated structure 20 can be formed by cold rolling the above-described first laminated structure 10. Cold rolling is performed on the first laminated structure 10 to a final thickness (t3) of about 0.2 mm to 0.6 mm. To facilitate rolling, warm rolling can be performed by raising the plate temperature to 100 to 200°C. The final reduction rate can be adjusted from 50% to 85%.

In the method of manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention, the step of forming the second laminated structure 20 (S300) is performed by hot pressing after the step of forming the first laminated structure 10 (S200). It may include cold rolling the first laminated structure without performing a rolling annealing process.

Cold rolled annealing treatment step (S400)

Referring to (d) of FIG. 2, the cold rolled second laminated structure 20 may be subjected to cold rolling annealing.

The step of performing the cold rolled annealing treatment (S400) is the ACL (Annealing and Coating Line) step of final annealing the cold rolled sheet, temperature increase rate: 10°C/s or more, annealing temperature: 900 ~ 1100°C, holding time: 30 ~ It may include annealing under the condition of 90 seconds and cooling under the condition of cooling rate: 30°C/s or more.

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.

After final annealing, a coating process may be performed to form the insulating coating layer 15. By forming the insulating coating layer 15, punchability can be improved and insulation properties can be secured. The thickness of the insulating coating layer 15 formed on the top of the second laminated structure 20 may be about 1 ㎛, and the thickness of the insulating coating layer 15 formed on the top of the second laminated structure 20 may also be about 1 ㎛.

Figure 3 is a diagram schematically illustrating the distribution of silicon content centered on the middle layer after cold rolling annealing in a non-oriented electrical steel sheet according to an embodiment of the present invention.

Referring to FIG. 3, during cold rolling annealing heat treatment, silicon may diffuse from the ferrosilicon constituting the intermediate layer 13 to the first steel material 11 and the second steel material 12. However, the cold rolling annealing process can be controlled so that the silicon content is gradually lowered in the direction from the middle layer 13 to the first steel material 11 and from the middle layer 13 to the second steel material.

If silicon diffusion proceeds sufficiently throughout the middle layer 13, the first steel material 11, and the second steel material 12 in the final non-oriented electrical steel sheet, and the silicon concentration is uniformly distributed, excellent iron loss characteristics and punching properties are achieved. Defect prevention cannot be implemented simultaneously. In the non-oriented electrical steel sheet according to the present invention, the concentration of silicon in the intermediate layer 13 is relatively high, which has the effect of insulating the first steel material 11 and the second steel material 12, thereby ensuring excellent iron loss characteristics and at the same time maintaining the electrical steel sheet. The concentration of silicon on the surface is relatively low, making it possible to prevent punching defects.

On the other hand, if we assume as a comparative example a case where the iron loss is reduced by coating the surface of the electrical steel sheet with silicon using silicon tetrachloride (SiCl ₄ ), etc. and then performing heat treatment, the high silicon concentration on the surface of the electrical steel sheet increases brittleness, resulting in perforation. Defects and coating defects occur, and there is a problem of using reaction gases that are harmful to the environment. In the present invention, the silicon concentration on the surface of the electrical steel sheet is low without using a reaction gas harmful to the environment, making punching easy, and the component that insulates the first steel material 11 and the second steel material 12 is installed inside the electrical steel sheet. Due to its location, the insulation coating properties are improved.

The final product has a grain size of 80 to 150㎛, magnetic flux density (B ₅₀ ) of 1.65T or more, and iron loss (W _10/400 ) of 14.5W/Kg or less at a thickness of 0.2mm or more. Mechanical properties can achieve yield strength (YP) of more than 400 MPa and tensile strength (TS) of more than 500 MPa.

The non-oriented electrical steel sheet implemented by the above-described manufacturing method contains silicon (Si), manganese (Mn), and aluminum (Al), respectively, with an intermediate layer made of ferrosilicon interposed between the hot rolled first and second steel materials. The stacked laminated structure is implemented by cold rolling and cold rolling annealing. The ferrosilicon is made of silicon and iron, and may contain 6 to 50% by weight of silicon (Si) and the remainder may be iron (Fe).

In the non-oriented electrical steel sheet, the silicon content may gradually decrease in the direction from the intermediate layer to the first steel material and to the second steel material.

The first steel material and the second steel material include carbon (C): greater than 0 and less than or equal to 0.003 wt%, silicon (Si): 2.8 to 3.8 wt%, manganese (Mn): 0.2 to 0.5 wt%, and aluminum (Al): 0.5 wt%. ~ 1.5% by weight, phosphorus (P): more than 0 and less than 0.015% by weight, sulfur (S): more than 0 and less than 0.003% by weight, nitrogen (N): more than 0 and less than 0.003% by weight, titanium (Ti): more than 0 and less than 0.003% by weight % or less and the remainder may contain iron (Fe) and other unavoidable impurities, respectively.

Looking at it from another perspective, the non-oriented electrical steel sheet according to the present invention is characterized in that the silicon content gradually decreases from the center of the electrical steel sheet toward the surface, and the iron loss (W _10/400 ) at a thickness of 0.2 mm or more is 14.5 W. It has physical properties of less than /Kg.

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.

C Si Mn Al P S N Ti Bal. 0.0018 3.3 0.3 0.9 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 carbon (C): more than 0 and less than 0.003% by weight, silicon (Si): 2.8 to 3.8% by weight, manganese (Mn): 0.2 to 0.5% by weight. , Aluminum (Al): 0.5 to 1.5% by weight, phosphorus (P): more than 0 and less than 0.015% by weight, sulfur (S): more than 0 and less than 0.003% by weight, nitrogen (N): more than 0 and less than 0.003% by weight, titanium ( Ti): exceeds 0 and satisfies 0.003% by weight or less and the remaining iron (Fe).

2. Evaluation of process conditions and physical properties

division presence or absence of middle layer Cold rolling method cold rolling
Reduction rate final
thickness B ₅₀
(A/m) W _10/400
(W/kg) Experimental Example 1 doesn't exist veneer cold rolling 87.5% 0.3mm 1.66 12.7 Experimental Example 2 has exist 2-ply cold rolling 75.0% 0.2mm 1.67 9.5

Table 2 shows the process conditions and physical properties in the method of manufacturing a non-oriented electrical steel sheet according to an experimental example of the present invention. Experimental Examples 1 and 2 were hot rolled under the same conditions of hot rolling reheating temperature (SRT): 1250°C, finish rolling temperature (FDT): 850°C, and coiling temperature (CT): 580°C for steel materials having the compositions in Table 1. was carried out.

Experimental Example 1 is a comparative example in which a hot-rolled single steel sheet was cold-rolled under the conditions of a cold-rolling reduction ratio of 87.5% without introducing an intermediate layer made of ferrosilicon, and cold-rolled and annealed under the conditions of an annealing temperature: 1000°C and holding time: 60 seconds, and then magnetic flux. Density and iron loss were measured.

Experimental Example 2 is an example in which an intermediate layer made of ferrosilicon was sandwiched between two hot rolled steel sheets, then cold rolled under the condition of a cold rolling reduction rate of 75.0%, and cold rolled and annealed under the conditions of annealing temperature: 1000°C and holding time: 60 seconds. Afterwards, the magnetic flux density and iron loss were measured.

In Experimental Example 1, the iron loss (W _10/400 ) was 12.7W/kg, while in Experimental Example 2, the iron loss (W _10/400 ) was confirmed to be 9.5W/kg, showing the formability according to the technical idea of the present invention. It can be confirmed that non-oriented electrical steel sheets with excellent high-frequency iron loss characteristics can be produced using this excellent high-strength cold-rolled steel sheet manufacturing method.

Experimental Example 1, which underwent single plate cold rolling, which is a typical process, requires a final thickness of 0.30 mm to secure an iron loss (W _10/400 ) of 14.0 W/kg or less. Experimental Example 2, which underwent two-ply cold rolling, which is an example of the present invention, secured an iron loss (W _10/400 ) of 10.0 W/kg or less at a final thickness of 0.20 mm. In Experimental Example 2, the high-resistance Si-Fe layer formed in the center of the electrical steel sheet had the effect of insulating the upper and lower plates, reducing iron loss, and improved magnetic flux density due to the high permeability of the high-concentration Si layer. .

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 (8)

Hot rolling first and second steel materials containing silicon (Si), manganese (Mn), and aluminum (Al), respectively;
forming a first laminated structure by laminating the hot rolled first steel material and the second steel material with an intermediate layer made of ferrosilicon;
Cold rolling the first laminated structure to form a second laminated structure; and
Including a step of cold rolling annealing the cold rolled second laminated structure.
Method for manufacturing non-oriented electrical steel sheet. According to claim 1,
The ferrosilicon is made of silicon and iron, with silicon (Si): 6 to 50% by weight and the balance being iron (Fe),
Method for manufacturing non-oriented electrical steel sheet. According to claim 1,
After the cold rolling annealing step, the non-oriented electrical steel sheet is characterized in that the silicon content is gradually lowered in the direction from the intermediate layer to the first steel material and in the direction to the second steel material,
Method for manufacturing non-oriented electrical steel sheet. According to claim 1,
The first steel material and the second steel material include carbon (C): greater than 0 and less than or equal to 0.003 wt%, silicon (Si): 2.8 to 3.8 wt%, manganese (Mn): 0.2 to 0.5 wt%, and aluminum (Al): 0.5 wt%. ~ 1.5% by weight, phosphorus (P): more than 0 and less than 0.015% by weight, sulfur (S): more than 0 and less than 0.003% by weight, nitrogen (N): more than 0 and less than 0.003% by weight, titanium (Ti): more than 0 and less than 0.003% by weight % or less and the remaining iron (Fe) and other unavoidable impurities, respectively,
Method for manufacturing non-oriented electrical steel sheet. A laminated structure containing silicon (Si), manganese (Mn), and aluminum (Al), respectively, and laminated with an intermediate layer made of ferrosilicon between the hot-rolled first and second steel materials is subjected to cold rolling and cold rolling annealing. implemented,
Non-oriented electrical steel sheet. According to claim 5,
The ferrosilicon is made of silicon and iron, with silicon (Si): 6 to 50% by weight and the balance being iron (Fe),
Non-oriented electrical steel sheet. According to claim 5,
Characterized in that the content of silicon gradually decreases in the direction from the intermediate layer to the first steel material and to the second steel material,
Non-oriented electrical steel sheet. According to claim 5,
The first steel material and the second steel material include carbon (C): greater than 0 and less than or equal to 0.003 wt%, silicon (Si): 2.8 to 3.8 wt%, manganese (Mn): 0.2 to 0.5 wt%, and aluminum (Al): 0.5 wt%. ~ 1.5% by weight, phosphorus (P): more than 0 and less than 0.015% by weight, sulfur (S): more than 0 and less than 0.003% by weight, nitrogen (N): more than 0 and less than 0.003% by weight, titanium (Ti): more than 0 and less than 0.003% by weight % or less and the remaining iron (Fe) and other unavoidable impurities, respectively,
Non-oriented electrical steel sheet.