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KR-20260063633-A - NON-ORIENTED ELECTRICAL STEEL SHEET AND METHOD FOR MANUFACTURING THE SAME

KR20260063633AKR 20260063633 AKR20260063633 AKR 20260063633AKR-20260063633-A

Abstract

A non-oriented electrical steel sheet according to one embodiment of the present invention comprises 2.7 to 3.5 wt% silicon (Si), 0.2 to 0.4 wt% manganese (Mn), 0.5 to 1.5 wt% aluminum (Al), and the remainder being iron (Fe) and other unavoidable elements, and can have excellent stamping characteristics with a rollover and shear surface ratio of 60% to 90% on the stamped surface.

Inventors

  • 이강노
  • 강춘구
  • 배성민

Assignees

  • 현대제철 주식회사

Dates

Publication Date
20260507
Application Date
20241030

Claims (12)

  1. It comprises 2.7 to 3.5 wt% silicon (Si), 0.2 to 0.4 wt% manganese (Mn), 0.5 to 1.5 wt% aluminum (Al), and the remainder being iron (Fe) and other unavoidable elements, The ratio of the rollover and shear surface of the stamped surface is 50% to 90%, Non-oriented electrical steel sheet.
  2. In paragraph 1, Non-oriented electrical steel sheet satisfying Equation 1. [Equation 1] 1.16 ≤ (Work Hardening Index (n) / Average Grain Size (s)) * 1000 ≤ 1.55 (However, the average grain size(s) is expressed in μm units.)
  3. In paragraph 2, Non-oriented electrical steel sheet having an average grain size of 110㎛ to 150㎛.
  4. In paragraph 1, Non-oriented electrical steel sheet with a burr length of less than 10㎛ on the stamped surface.
  5. In paragraph 1, Non-oriented electrical steel sheet with iron loss (W15/50) of 2.5 W/kg or less.
  6. A first step of preparing a steel material comprising 2.7 to 3.5 wt% silicon (Si), 0.2 to 0.4 wt% manganese (Mn), 0.5 to 1.5 wt% aluminum (Al), and the remainder being iron (Fe) and other unavoidable elements; A second step of hot-rolling the above steel material to form a hot-rolled steel plate; A third step of hot-rolling and annealing the above hot-rolled steel sheet; A fourth step of forming a cold-rolled steel sheet by cold-rolling the hot-rolled steel sheet that has undergone the third step above; and The above cold-rolled steel sheet includes a fifth step of cold-rolling and annealing, The above 5th step satisfies Equation 2 Method for manufacturing non-oriented electrical steel sheets. [Equation 2] 17 ≤ 9.52*log 10 (heat treatment temperature - 900)+0.99*log 10 (heat treatment time - 20)-0.66*log 10 (cooling rate) ≤ 20 (However, the heat treatment temperature, heat treatment time, and cooling rate are values corresponding to °C, sec, and °C/sec, respectively.)
  7. In paragraph 6, A method for manufacturing non-oriented electrical steel sheets satisfying Equation 1. [Equation 1] 1.45 ≤ (Work Hardening Index (n) / Average Grain Size (s)) * 1000 ≤ 1.60 (However, the average grain size(s) is expressed in μm units.)
  8. In paragraph 6, Method for manufacturing a non-oriented electrical steel sheet having an average grain size of 110㎛ to 150㎛.
  9. In paragraph 6, Method for manufacturing non-oriented electrical steel sheets with a burr length of less than 10㎛ on the stamped surface.
  10. In paragraph 6, Method for manufacturing non-oriented electrical steel sheets with an iron loss (W15/50) of 2.5 W/kg or less.
  11. An iron core for an electric motor comprising a non-oriented electrical steel sheet according to any one of claims 1 to 5.
  12. An electric motor comprising a non-oriented electrical steel sheet according to any one of paragraphs 1 to 5.

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 a non-oriented electrical steel sheet. With environmental regulations tightening globally in recent years, conventional internal combustion engine vehicles are being rapidly replaced by eco-friendly vehicles such as hybrid, electric, and hydrogen cars. Eco-friendly vehicles utilize electric motors to generate the driving force required for the vehicle and can reduce environmental pollution by significantly decreasing the emission of harmful exhaust gases. As interest in and demand for such eco-friendly vehicles increase, the demand for electric motors that generate the driving force required for the vehicles is also rising. Non-oriented electrical steel sheets are primarily used as core materials for such electric motors, and various factors such as alloying elements, processing conditions, microstructure, and precipitates affect the characteristics of the electrical steel sheets and the electric motors utilizing them. The characteristics of electrical steel sheets are largely evaluated based on magnetic flux density and iron loss. Iron loss refers to the total sum of hysteresis loss, eddy current loss, and anomalous loss, which occurs during the magnetization process of the electrical steel sheet material, and is measured in W/kg. To improve the iron loss of electrical steel sheets, methods such as increasing resistivity by adding major alloying elements like Si, Al, and Mn, or reducing eddy currents by thinning the material, are being utilized. Meanwhile, since the motor core is composed of multiple laminated electrical steel sheets, it is necessary to improve motor performance by reducing not only the iron loss of the electrical steel sheets themselves but also the iron loss generated in the laminated state. If multiple electrical steel sheets constituting the iron core of a motor are not laminated in close contact with each other, or if large gaps occur between the electrical steel sheets or if the gaps between the electrical steel sheets are formed irregularly, the motor's performance may deteriorate due to increased iron loss. Since electrical steel sheets are manufactured into motor cores through punching and lamination processes, the quality of the shear surface generated during punching affects the lamination of the electrical steel sheets, and this can be one of the major factors determining the performance of the drive motor. Specifically, the shear surface formed during the punching of electrical steel sheets consists of rollover, shear surface, fracture surface, and burr, and it is known that motor performance improves as the ratio of the shear surface to the fracture surface increases. Therefore, it is necessary to develop methods to improve not only the iron loss and magnetic flux density of electrical steel sheets, but also the quality of the shear surface formed during the punching of electrical steel sheets. FIG. 1 (a) is a photograph showing a punched surface of a non-oriented electrical steel sheet according to an embodiment of the present invention and a corresponding conceptual diagram, and FIG. 1 (b) is a drawing showing the configuration of the punched surface of a non-oriented electrical steel sheet according to an embodiment of the present invention. FIG. 2 is a flowchart illustrating a method for manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention. Hereinafter, preferred embodiments of the present invention are described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. However, the present invention is not limited or restricted by the following embodiments. Additionally, when it is stated that a component (or area, layer, part, etc.) is "on," "connected," or "combined" with another component, it means that it may be directly placed/connected/combined with the other component, or that a third component may be placed between them. Terms such as "include" or "have" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof. In order to clearly explain the present invention, detailed descriptions of related prior art that are irrelevant to the explanation or that may unnecessarily obscure the essence of the invention have been omitted. Furthermore, when assigning reference numerals to the components of each drawing in this specification, identical or similar reference numerals are assigned to identical or similar components throughout the entire specification. Furthermore, terms and words used in this specification and claim