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KR-20260064982-A - Non-oriented electrical steel sheet, motor containing the same, and method of manufacturing the same

KR20260064982AKR 20260064982 AKR20260064982 AKR 20260064982AKR-20260064982-A

Abstract

The present invention relates to a non-oriented electrical steel sheet comprising, in weight percent, silicon (Si): 0.2 to 2.0%, manganese (Mn): 0.1 to 0.5%, aluminum (Al): 0.1 to 0.8%, carbon (C): 0.005% or less (greater than 0), sulfur (S): 0.005% or less (greater than 0), nitrogen (N): 0.005% or less (greater than 0), titanium (Ti): 0.005% or less (greater than 0), the remainder being iron (Fe) and unavoidable impurities, wherein the non-oriented electrical steel sheet has a thickness deviation defined as the difference between a minimum value and a maximum value of thickness, and the non-oriented electrical steel sheet is [Equation 1] [Unit: mm] [Unit: mm] is provided, a non-oriented electrical steel sheet satisfying [Unit: mm]. (where a represents the thickness variation of the steel sheet and c represents the minimum thickness value. In this case, the units of a and c are each mm.)

Inventors

  • 강춘구
  • 배성민
  • 채원기
  • 신경식

Assignees

  • 현대제철 주식회사

Dates

Publication Date
20260508
Application Date
20241030

Claims (19)

  1. As a non-oriented electrical steel sheet, In weight percent, silicon (Si): 0.2 to 2.0%, manganese (Mn): 0.1 to 0.5%, aluminum (Al): 0.1 to 0.8%, carbon (C): 0.005% or less (greater than 0), sulfur (S): 0.005% or less (greater than 0), nitrogen (N): 0.005% or less (greater than 0), titanium (Ti): 0.005% or less (greater than 0), the remainder being iron (Fe) and unavoidable impurities, The above non-oriented electrical steel sheet has a thickness variation defined by the difference between the minimum and maximum values of thickness, and The above non-oriented electrical steel sheet is a non-oriented electrical steel sheet satisfying the following Equation 1. [Equation 1] [Unit: mm] (Note: a represents the thickness variation of the steel plate, and c represents the minimum thickness value. The units of a and c are each in mm.)
  2. In paragraph 1, When the above-mentioned non-oriented electrical steel sheet is punched, the above-mentioned non-oriented electrical steel sheet after punching has a burr protruding upward or downward at the edge of the corner, and The above non-oriented electrical steel sheet is a non-oriented electrical steel sheet satisfying the following Equation 2. [Equation 2] a×1.8b < 0.12 [Unit: mm² ] (Note: a represents the thickness variation of the steel plate, and b represents the burr height. The units of a and b are each in mm.)
  3. In paragraph 1, A non-oriented electrical steel sheet having an average thickness of 0.3 mm to 0.65 mm.
  4. In paragraph 1, A non-oriented electrical steel sheet having an iron loss (W 15/50 ) of 4.8 W/kg or less.
  5. In paragraph 1, A non-oriented electrical steel sheet having a magnetic flux density (B 50 ) of 1.68T or more.
  6. In paragraph 1, A non-oriented electrical steel sheet having a grain size of 30㎛ or more and 150㎛ or less.
  7. In paragraph 1, A non-oriented electrical steel sheet having a tensile strength (TS) of 300 MPa or more and a yield strength (YP) of 200 MPa or more.
  8. As a method for manufacturing non-oriented electrical steel sheets, A hot rolling step for manufacturing a hot-rolled plate by hot rolling a slab comprising, in weight%, silicon (Si): 0.2 to 2.0%, manganese (Mn): 0.1 to 0.5%, aluminum (Al): 0.1 to 0.8%, carbon (C): 0.005% or less (greater than 0), sulfur (S): 0.005% or less (greater than 0), nitrogen (N): 0.005% or less (greater than 0), titanium (Ti): 0.005% or less (greater than 0), and the remainder being iron (Fe) and unavoidable impurities; A hot rolling annealing step for manufacturing a hot rolling annealed plate by hot rolling and annealing the above hot rolling plate; A cold rolling step for manufacturing a cold-rolled plate by cold-rolling the above hot-rolled annealed plate; and A cold rolling annealing step for manufacturing a cold rolling annealed plate by cold rolling annealing the above cold rolling plate; Includes, A method for manufacturing a non-oriented electrical steel sheet, wherein the non-oriented electrical steel sheet formed through the above manufacturing steps satisfies the following Equation 1. [Equation 1] [Unit: mm] (Note: a represents the thickness variation of the steel plate, and c represents the minimum thickness value. The units of a and c are each in mm.)
  9. In paragraph 8, The above cold-rolled annealed plate further includes a stamping step for processing it into a predetermined shape, and A method for manufacturing a non-oriented electrical steel sheet, wherein the non-oriented electrical steel sheet after the above stamping step has a burr protruding upward or downward at the edge of the corner, and the non-oriented electrical steel sheet satisfies the following Equation 2. [Equation 2] a×1.8b < 0.12 [Unit: mm² ] (Note: a represents the thickness variation of the steel plate, and b represents the burr height. The units of a and b are each in mm.)
  10. In paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the average thickness of the non-oriented electrical steel sheet after the above hot rolling step is 1.6 mm to 2.6 mm.
  11. In paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the average thickness of the non-oriented electrical steel sheet after the above cold rolling step is 0.3 mm to 0.65 mm.
  12. In paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the iron loss (W 15/50 ) of the above non-oriented electrical steel sheet is 4.8 W/kg or less.
  13. In paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the magnetic flux density (B 50 ) of the above non-oriented electrical steel sheet is 1.68T or higher.
  14. In paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, further comprising a coating step of coating the above-mentioned cold-rolled annealed sheet.
  15. A motor comprising a motor core, wherein the motor core is, It comprises a non-oriented electrical steel sheet comprising, in weight percent, silicon (Si): 0.2 to 2.0%, manganese (Mn): 0.1 to 0.5%, aluminum (Al): 0.1 to 0.8%, carbon (C): 0.005% or less (greater than 0), sulfur (S): 0.005% or less (greater than 0), nitrogen (N): 0.005% or less (greater than 0), titanium (Ti): 0.005% or less (greater than 0), and the remainder being iron (Fe) and unavoidable impurities. The above non-oriented electrical steel sheet has a thickness deviation defined as the difference between the minimum and maximum values of the thickness, and satisfies the following Equation 1, motor. [Equation 1] [Unit: mm] (Note: a represents the thickness variation of the steel plate, and c represents the minimum thickness value. The units of a and c are each in mm.)
  16. In paragraph 15, The above non-oriented electrical steel sheet is provided with a burr protruding upward or downward at the end of the corner, and the above non-oriented electrical steel sheet satisfies the following Equation 2. [Equation 2] a×1.8b < 0.12 [Unit: mm² ] (Note: a represents the thickness variation of the steel plate, and b represents the burr height. The units of a and b are each in mm.)
  17. In paragraph 15, A motor having an average thickness of 0.3 mm to 0.65 mm of the above-mentioned non-oriented electrical steel sheet.
  18. In paragraph 15, A motor in which the iron loss (W 15/50 ) of the above non-oriented electrical steel sheet is 4.8 W/kg or less.
  19. In paragraph 15, A motor in which the magnetic flux density (B 50 ) of the above non-oriented electrical steel sheet is 1.68 T or greater.

Description

Non-oriented electrical steel sheet, motor containing the same, and method of manufacturing the same The present invention relates to a non-oriented electrical steel sheet and a method for manufacturing the same. Due to policies aimed at reducing carbon dioxide emissions to prevent global warming, conventional internal combustion engine vehicles are being rapidly replaced by eco-friendly vehicles (such as hybrid or electric vehicles). In line with the increasing demand for these electric vehicles (EVs), the energy conversion efficiency of EV motors is being improved, and to achieve this, superior magnetic properties are required for the motor core materials. Generally, electrical steel sheets are classified into oriented and non-oriented types; oriented steel is used in stationary components such as transformers. On the other hand, non-oriented electrical steel, which possesses uniform magnetic properties in all directions regardless of the rolling direction, is utilized in automotive drive motors that perform rotational motion. Therefore, non-oriented electrical steel requires low deviation in magnetic properties between the rolling direction and other directions at a certain angle relative to the rolling direction. In other words, non-oriented electrical steel must have low magnetic anisotropy; if magnetic anisotropy is high, motor rotation becomes difficult and energy efficiency may decrease. Since electric vehicles must generate high torque during low speeds or acceleration and rotate at high speeds during constant speed and high-speed driving, non-oriented electrical steel sheets used as core materials for motors must simultaneously satisfy high magnetic flux density and low iron loss, as well as high mechanical strength capable of withstanding centrifugal force or stress fluctuations. In particular, non-oriented electrical steel sheets with low high-frequency iron loss are required to improve motor efficiency during high-speed driving, where energy loss is high. Magnetic flux density refers to the number of magnetic field lines induced in a material under a specific magnetic field, and Tesla [T] is used as the unit of magnetic flux density. Generally, the B 50 value, which is the magnetic flux density induced under a magnetic field of 5,000 A/m, is evaluated. This magnetic flux density can vary depending on the chemical composition, grain size, and texture. Iron loss refers to the energy loss that occurs during the magnetization process of electrical steel sheets, and the unit of iron loss is W/kg. Iron loss can be classified into hysteresis loss, which is caused by the magnetization phenomenon itself, and eddy current loss, which is caused by eddy currents generated during magnetization. Therefore, methods such as reducing the sheet thickness or increasing the resistivity are being studied to reduce iron loss in non-oriented electrical steel sheets. When the content of alloying elements with high resistivity, such as Si, Mn, and Al, is increased to increase resistivity, the magnetic flux density decreases and brittleness increases, which may lead to a decrease in cold rolling performance. Consequently, a problem arises in that it becomes difficult to thin the steel sheet. In addition, the added elements combine with elements such as C, S, N, and Ti to form precipitates, and these precipitates hinder the movement of magnetic domains when a magnetic field is applied, resulting in inferior magnetic properties. FIGS. 1 and FIGS. 2 are flowcharts schematically illustrating a method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention. FIG. 3 is a cross-sectional view schematically illustrating a non-oriented electrical steel sheet according to one embodiment of the present invention. FIG. 4 is a drawing showing the end of a non-oriented electrical steel sheet according to one embodiment of the present invention. The present invention will be described in detail below. However, in describing the present invention, if it is determined that a detailed description of related known technologies or configurations may unnecessarily obscure the essence of the present invention, such detailed description will be omitted. In the following embodiments, terms such as first, second, etc. are used not in a limiting sense, but for the purpose of distinguishing one component from another component. In the following examples, singular expressions include plural expressions unless the context clearly indicates otherwise. In the following embodiments, when various components such as layers, films, regions, and plates are described as being "on" another component, this includes not only cases where they are "directly on" another component, but also cases where another component is interposed between them. In the drawings, the size of components may be exaggerated or reduced for convenience of explanation. For example, the size and thickness of each component shown in th