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KR-20260062159-A - NON-ORIENTED ELECTRICAL STEEL SHEET AND METHOD FOR MANUFACTURING THE SAME

KR20260062159AKR 20260062159 AKR20260062159 AKR 20260062159AKR-20260062159-A

Abstract

The present invention provides a non-oriented electrical steel sheet comprising silicon (Si): 4.0 to 5.0 wt%, manganese (Mn): 0.1 to 0.5 wt%, aluminum (Al): 0.1 to 0.5 wt%, and the remainder being iron (Fe) and other unavoidable impurities, wherein the yield strength is 700 MPa or higher and the iron loss (W 10/400 ) value is 15 to 25 W/kg.

Inventors

  • 이승태
  • 강춘구
  • 첸 레이
  • 이강노

Assignees

  • 현대제철 주식회사

Dates

Publication Date
20260507
Application Date
20241025

Claims (10)

  1. It is a non-oriented electrical steel sheet comprising silicon (Si): 4.0 to 5.0 wt%, manganese (Mn): 0.1 to 0.5 wt%, aluminum (Al): 0.1 to 0.5 wt%, and the remainder being iron (Fe) and other unavoidable impurities, and With a yield strength of 700 MPa or higher and an iron loss (W 10/400 ) value of 15~25 W/kg, Non-oriented electrical steel sheet.
  2. In Article 1, Carbon (C): greater than 0 and less than or equal to 0.003 wt%, Sulfur (S): greater than 0 and less than or equal to 0.003 wt%, Nitrogen (N): greater than 0 and less than or equal to 0.003 wt%, and Titanium (Ti): greater than 0 and less than or equal to 0.003 wt%, further comprising Non-oriented electrical steel sheet.
  3. In Article 1 or Article 2, Characterized by the thickness of the above non-oriented electrical steel sheet being 0.20 to 0.25 mm, Non-oriented electrical steel sheet.
  4. In Article 1 or Article 2, The above-mentioned non-oriented electrical steel sheet is, 20 to 80 percent of the microstructure area is recrystallized, Non-oriented electrical steel sheet.
  5. A step of providing a steel material comprising silicon (Si): 4.0 to 5.0 wt%, manganese (Mn): 0.1 to 0.5 wt%, aluminum (Al): 0.1 to 0.5 wt%, and the remainder being iron (Fe) and other unavoidable impurities; A step of hot rolling the above steel material; A step of pre-annealing the above hot-rolled steel; A step of warm rolling the above pre-annealed steel at a temperature of 200~400℃, a reduction rate of 75~82%, and a number of passes of 4~6 times; The step of cold rolling the above-mentioned hot-rolled steel; and A step comprising cold rolling annealing the above cold-rolled steel at a temperature of 650 to 750°C for 1 to 5 minutes; Method for manufacturing non-oriented electrical steel sheets.
  6. In Article 5, The above steel material is, Carbon (C): greater than 0 and less than or equal to 0.003 wt%, Sulfur (S): greater than 0 and less than or equal to 0.003 wt%, Nitrogen (N): greater than 0 and less than or equal to 0.003 wt%, and Titanium (Ti): greater than 0 and less than or equal to 0.003 wt%, further comprising Method for manufacturing non-oriented electrical steel sheets.
  7. In Article 5 or 6, The above hot rolling step is, Finish rolling temperature (FDT): 800~900℃, and the thickness of the hot-rolled steel is 2.0~2.5mm, Method for manufacturing non-oriented electrical steel sheets.
  8. In Article 5 or 6, The above-mentioned warm rolling step is, The step of rolling the above-mentioned pre-annealed steel to a thickness of 0.45 to 0.5 mm, Method for manufacturing non-oriented electrical steel sheets.
  9. In Article 5 or 6, The above cold rolling step is, A step of rolling to a thickness of 0.20–0.25 mm with a reduction rate of 50–60%, Method for manufacturing non-oriented electrical steel sheets.
  10. In Article 5 or 6, The above cold rolling annealing step is, A step in which 20 to 80 area percent of the microstructure of the above cold-rolled steel is recrystallized, Method for manufacturing non-oriented electrical steel sheets.

Description

Non-oriented electrical steel sheet and method for manufacturing the same The present invention relates to a non-oriented electrical steel sheet and a method for manufacturing the same, and more specifically, to a non-oriented electrical steel sheet having excellent mechanical and magnetic properties and a method for manufacturing the same. Electrical steel sheets can be classified into oriented and non-oriented electrical steel sheets based on their magnetic properties. Oriented electrical steel sheets are manufactured to facilitate magnetization along the rolling direction, resulting in particularly excellent magnetic properties in that direction; consequently, they are primarily used as cores for large, medium, and small transformers that require low iron loss and high permeability. In contrast, non-oriented electrical steel sheets possess uniform magnetic properties regardless of the sheet's orientation, making them widely used as core materials for small electric motors. In particular, as conventional internal combustion engine vehicles are rapidly being replaced by electric vehicles (EVs), interest in non-oriented electrical steel sheets used as drive motor core materials is increasing, and specification standards are also becoming more sophisticated. During high-speed rotation in electric vehicles (EVs), the motor rotor is subjected to not only centrifugal force but also stress fluctuations resulting from changes in rotational speed; consequently, there is a risk that motor efficiency and noise/vibration (NVH) performance will deteriorate due to deformation and fatigue failure. As such, the non-oriented electrical steel used in high-speed motors requires high-strength materials capable of withstanding centrifugal force and stress fluctuations. However, since strength and iron loss are typically proportional, there are difficulties in manufacturing products that possess both high strength and low iron loss. To satisfy both high strength and low iron loss characteristics of non-oriented electrical steel sheets, methods have been proposed such as increasing the Si content among alloying elements by utilizing chemical vapor deposition (CVD) or melt spinning processes, and coating the surface of non-oriented electrical steel sheets with an insulating film to provide a high level of surface resistivity while simultaneously imparting high functionality to the surface. The chemical vapor deposition (CVD) process is a method of diffusion annealing using SiCl₄ , but it has the disadvantage of low productivity due to the need to use toxic SiCl₄ and the long time required for diffusion annealing. The melt spinning process is a technology that manufactures very thin ribbon-shaped metal by rapidly spraying molten metal at high temperatures; utilizing this technology can solve the problem where processing becomes difficult due to increased brittleness when the silicon content is high. However, the melt spinning process has the disadvantage of being limited to very thin thicknesses (usually at the level of tens of micrometers) and requiring complex subsequent processing steps. On the other hand, while applying an insulating coating to the surface of electrical steel sheets can reduce iron loss, if the coating thickness is too thick, problems such as reduced flexibility and deterioration of mechanical properties arise. Figure 1 is an image showing the microstructure of a non-oriented electrical steel sheet according to one embodiment of the present invention. FIG. 2 is a flowchart illustrating a method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. The embodiments of the present invention are provided to more completely explain the technical concept of the present invention to those skilled in the art, and the following embodiments may be modified in various different forms, and the scope of the technical concept of the present invention is not limited to the following embodiments. Rather, these embodiments are provided to make the present disclosure more faithful and complete and to fully convey the technical concept of the present invention to those skilled in the art. In this specification, the same reference numerals denote the same elements throughout. Furthermore, various elements and areas in the drawings are depicted schematically. Accordingly, the technical concept of the present invention is not limited by the relative sizes or spacing depicted in the attached drawings. A non-oriented electrical steel sheet implemented according to an embodiment of the present invention is a non-oriented electrical steel sheet comprising silicon (Si): 4.0 to 5.0 wt%, manganese (Mn): 0.1 to 0.5 wt%, aluminum (Al): 0.1 to 0.5 wt%, and the remainder being iron (Fe) and other unavoidable impurities, characterized by having a yield strength