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KR-20260064956-A - Non-oriented electrical steel sheet, motor containing the same, and method for manufacturing non-oriented electrical steel sheet

KR20260064956AKR 20260064956 AKR20260064956 AKR 20260064956AKR-20260064956-A

Abstract

The present invention provides a non-oriented electrical steel sheet comprising a base material and an oxide layer located on the base material and formed inwardly from the surface, wherein the base material comprises, in weight% (wt%), silicon (Si): 0.2 to 2.8%, aluminum (Al): 0.8 to 1.5%, manganese (Mn): 0.2 to 0.4%, carbon (C): 0.08% or less (greater than 0), sulfur (S): 0.0050% or less (greater than 0), nitrogen (N): 0.0030% or less (greater than 0), titanium (Ti): 0.0050% or less (greater than 0), and the remainder being iron (Fe) and other unavoidable impurities, and the interfacial roughness between the oxide layer and the base material satisfies the following Equation 1. [Equation 1] (However, Ra0° is the interface roughness between the oxide layer and the base material with respect to the rolling direction (0°), and Ra90° is the interface roughness between the oxide layer and the base material with respect to the rolling vertical direction (90°).)

Inventors

  • 김민성
  • 채원기
  • 고재현
  • 최혜정

Assignees

  • 현대제철 주식회사

Dates

Publication Date
20260508
Application Date
20241030

Claims (18)

  1. A non-oriented electrical steel sheet having a base material and an oxide layer located on the base material and formed from the surface inward, The above base material comprises, in weight% (wt%), silicon (Si): 0.2 to 2.8%, aluminum (Al): 0.8 to 1.5%, manganese (Mn): 0.2 to 0.4%, carbon (C): 0.08% or less (greater than 0), sulfur (S): 0.0050% or less (greater than 0), nitrogen (N): 0.0030% or less (greater than 0), titanium (Ti): 0.0050% or less (greater than 0), and the remainder being iron (Fe) and other unavoidable impurities. A non-oriented electrical steel sheet in which the interfacial roughness between the oxide layer and the base material satisfies the following Equation 1. [Equation 1] (However, Ra0° is the interface roughness between the oxide layer and the base material with respect to the rolling direction (0°), and Ra90° is the interface roughness between the oxide layer and the base material with respect to the rolling vertical direction (90°).)
  2. In paragraph 1, A non-oriented electrical steel sheet in which the thickness variation of the oxide layer satisfies the following Equation 2. [Equation 2] (However, T Max 0° and T Avg 0° are the maximum thickness and average thickness of the oxide layer measured in the rolling direction (0°), respectively, and T Max 90° and T Avg 90° are the maximum thickness and average thickness of the oxide layer measured in the rolling vertical direction (90°), respectively.)
  3. In paragraph 1, A non-oriented electrical steel sheet having a deviation of 10% or less in iron loss with respect to the rolling direction and iron loss with respect to the rolling perpendicular direction.
  4. In paragraph 1, A non-oriented electrical steel sheet having an iron loss (W 10/400 ) of 13.0 W/kg or less.
  5. In paragraph 1, A non-oriented electrical steel sheet having a magnetic flux density (B 50 ) of 1.65T or more.
  6. 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 wt%, silicon (Si): 0.2 to 2.8%, aluminum (Al): 0.8 to 1.5%, manganese (Mn): 0.2 to 0.4%, carbon (C): 0.08% or less (greater than 0), sulfur (S): 0.0050% or less (greater than 0), nitrogen (N): 0.0030% or less (greater than 0), titanium (Ti): 0.0050% or less (greater than 0), and the remainder being iron (Fe) and other 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 hot-rolled annealed plate above; and A cold rolling annealing step for manufacturing a cold rolling annealed plate by annealing the above cold rolling plate; Includes, A method for manufacturing non-oriented electrical steel sheets, wherein the above cold rolling annealing step is an annealing step performed in an atmosphere containing hydrogen, nitrogen, and residual oxygen, wherein the amount of residual oxygen is controlled according to the ratio of hydrogen and nitrogen.
  7. In paragraph 6, The above non-oriented electrical steel sheet comprises a base material and an oxide layer located on the base material and formed from the surface inward, and A method for manufacturing a non-oriented electrical steel sheet, wherein the interface roughness between the oxide layer and the base material satisfies the following Equation 1. [Equation 1] (However, Ra0° is the interface roughness between the oxide layer and the base material with respect to the rolling direction (0°), and Ra90° is the interface roughness between the oxide layer and the base material with respect to the rolling vertical direction (90°).)
  8. In paragraph 6, A method for manufacturing a non-oriented electrical steel sheet in which the thickness variation of the oxide layer satisfies the following Equation 2. [Equation 2] (However, T Max 0° and T Avg 0° are the maximum thickness and average thickness of the oxide layer measured in the rolling direction (0°), respectively, and T Max 90° and T Avg 90° are the maximum thickness and average thickness of the oxide layer measured in the rolling vertical direction (90°), respectively.)
  9. In paragraph 6, A method for manufacturing a non-oriented electrical steel sheet, wherein the deviation of iron loss with respect to the rolling direction and iron loss with respect to the rolling perpendicular direction of the above non-oriented electrical steel sheet is 10% or less.
  10. In paragraph 6, A method for manufacturing a non-oriented electrical steel sheet, wherein the iron loss (W 10/400 ) of the above non-oriented electrical steel sheet is 13.0 W/kg or less.
  11. In paragraph 6, 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 1.65T or higher.
  12. In paragraph 6, A method for manufacturing a non-oriented electrical steel sheet, wherein in the above cold rolling annealing step, the hydrogen ( H₂ ) fraction is 10% to 60%, the nitrogen ( N₂ ) fraction is 90% to 40%, and the residual oxygen ( O₂ ) concentration is 350 ppm or less.
  13. In paragraph 6, A method for manufacturing a non-oriented electrical steel sheet, wherein the above cold rolling annealing step is performed at a heating rate of 10 ℃/s or more at 900℃ to 1100℃ for 5 seconds to 70 seconds.
  14. A motor comprising a motor core, wherein the motor core is, A non-oriented electrical steel sheet comprising, in weight% (wt%), silicon (Si): 0.2 to 2.8%, aluminum (Al): 0.8 to 1.5%, manganese (Mn): 0.2 to 0.4%, carbon (C): 0.08% or less (greater than 0), sulfur (S): 0.0050% or less (greater than 0), nitrogen (N): 0.0030% or less (greater than 0), titanium (Ti): 0.0050% or less (greater than 0), the remainder being iron (Fe) and unavoidable impurities, and an oxide layer located on the base material and formed from the surface inward. A motor in which the interfacial roughness between the oxide layer and the base material satisfies the following Equation 1. [Equation 1] (However, Ra0° is the interface roughness between the oxide layer and the base material with respect to the rolling direction (0°), and Ra90° is the interface roughness between the oxide layer and the base material with respect to the rolling vertical direction (90°).)
  15. In Paragraph 14, A motor in which the thickness variation of the oxide layer satisfies the following Equation 2. [Equation 2] (However, T Max 0° and T Avg 0° are the maximum thickness and average thickness of the oxide layer measured in the rolling direction (0°), respectively, and T Max 90° and T Avg 90° are the maximum thickness and average thickness of the oxide layer measured in the rolling vertical direction (90°), respectively.)
  16. In Paragraph 14, A motor in which the deviation of iron loss with respect to the rolling direction and iron loss with respect to the rolling perpendicular direction of the above non-oriented electrical steel sheet is 10% or less.
  17. In Paragraph 14, A motor in which the iron loss (W 10/400 ) of the above non-oriented electrical steel sheet is 13.0 W/kg or less.
  18. In Paragraph 14, A motor in which the magnetic flux density (B 50 ) of the above non-oriented electrical steel sheet is 1.65T or greater.

Description

Non-oriented electrical steel sheet, motor containing the same, and method for manufacturing non-oriented electrical steel sheet The present invention relates to a non-oriented electrical steel sheet and a method for manufacturing the same. A motor generates mechanical energy by using electrical energy as the driving force to rotate an internal iron core. The internal iron core is formed by stacking multiple sheets of non-oriented electrical steel that have been punched into the shapes of a stator and a rotor; in this process, the magnetic properties of the non-oriented electrical steel have a dominant influence on the performance of the motor (or motor core). The magnetic properties of non-oriented electrical steel are evaluated by magnetic flux density and iron loss. Magnetic flux density is related to the motor's torque, while iron loss is the amount of energy lost as heat. To improve the energy efficiency of a motor, iron loss must be reduced, and iron loss is significantly affected by the surface quality of the steel plate. Specifically, if there are irregularities or cracks on the steel plate surface, they hinder the flow of magnetic flux during magnetization, thereby increasing iron loss. Furthermore, an increase in the surface roughness of the steel plate reduces the motor core fill factor, which has the adverse effect of decreasing torque compared to a motor of the same volume. Therefore, research is actively underway to manage surface quality in non-oriented electrical steel sheets. FIG. 1 is a flowchart schematically illustrating a method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention. FIG. 2 is a cross-sectional view schematically illustrating a cross-section of a non-oriented electrical steel sheet according to one embodiment of the present invention. FIG. 3 is a cross-sectional view schematically illustrating a cross-section of a non-oriented electrical steel sheet according to a comparative example of the present invention. FIGS. 4 and FIGS. 5 are cross-sectional views schematically illustrating a cross-section of a non-oriented electrical steel sheet according to an embodiment of the present invention to explain the process of deriving Equation 2. 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 the drawings are depicted arbitrarily for convenience of explanation, and therefore the present invention is not necessarily limited to what is illustrated. In the following embodiments, terms such as "include" or "have" mean that the features or components described in the specification are present, and do not preclude the possibility that one or more other features or components may be added. In this specification, "A and/or B" indicates the case where it is A, B, or both A and B. Additionally, in this specification, "at least one of A and B" indicates the case where it is A, B, or both A and B. Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined. Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. FIG. 1 is a flowchart schematically illustrating a method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention. Referring to FIG. 1, a method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention may include a hot rolling step (S100), a pre-anneali