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WO-2026095284-A1 - NON-ORIENTED ELECTRICAL STEEL SHEET AND METHOD FOR MANUFACTURING SAME

WO2026095284A1WO 2026095284 A1WO2026095284 A1WO 2026095284A1WO-2026095284-A1

Abstract

The present application relates to a non-oriented electrical steel sheet and a method for manufacturing same. The non-oriented electrical steel sheet and the method for manufacturing same, according to the present application, can provide excellent magnetic properties, and, specifically, the non-oriented electrical steel sheet may have low iron loss and a low angle-specific average iron loss.

Inventors

  • CHO, HAN HYUK
  • CHAE, Won Kee
  • KOH, Jae Hyeon
  • CHOE, Hye Jeong

Assignees

  • 현대제철 주식회사

Dates

Publication Date
20260507
Application Date
20250819
Priority Date
20241028

Claims (15)

  1. In weight percent, composed of C: greater than 0% and less than or equal to 0.0030%, Si: greater than 2.8% and less than or equal to 4.0%, Mn: greater than 0.1% and less than or equal to 0.5%, Al: greater than 0.3% and less than or equal to 0.9%, S: greater than 0% and less than or equal to 0.0030%, N: greater than 0% and less than or equal to 0.0015%, Ti: greater than 0% and less than or equal to 0.0030%, P: greater than 0% and less than or equal to 0.01%, and the remainder being Fe and other unavoidable impurities, and A non-oriented electrical steel sheet having a ratio of the fraction of {001}<130> orientation and the fraction of {334}<4-83> orientation represented by the following Formula 1 to 1.45 or greater and 1.80 or less. [Equation 1] {001}<130> fraction of directions / {334}<4-83> fraction of directions
  2. In Article 1, A non-oriented electrical steel sheet having an average iron loss (W 10/400 ) of 11.5 W/Kg or less, measured at azimuth angles of 0° and 90° with respect to the rolling direction, respectively.
  3. In Article 1 or Article 2, A non-oriented electrical steel sheet having an average iron loss (W 10/400 ) of 11.5 W/Kg or less, measured at azimuth angles of 0°, 30°, 45°, 60°, and 90° respectively with respect to the rolling direction.
  4. A step of manufacturing a hot-rolled steel sheet by reheating and hot-rolling a slab comprising, in weight%, C: greater than 0% and less than or equal to 0.0030%, Si: greater than 2.8% and less than or equal to 4.0%, Mn: greater than 0.1% and less than or equal to 0.5%, Al: greater than 0.3% and less than or equal to 0.9%, S: greater than 0% and less than or equal to 0.0030%, N: greater than 0% and less than or equal to 0.0015%, Ti: greater than 0% and less than or equal to 0.0030%, P: greater than 0% and less than or equal to 0.01%, and the remainder being Fe and other unavoidable impurities; A step of manufacturing a hot-rolled annealed material by annealing the above hot-rolled steel plate; A step of manufacturing a cold-rolled steel sheet by cold-rolling the above hot-rolled annealed material; A method for manufacturing a non-oriented electrical steel sheet comprising the step of finally annealing the above cold-rolled steel sheet, A method for manufacturing a non-oriented electrical steel sheet, wherein the non-oriented electrical steel sheet produced through the above final annealing step has a ratio of the fraction of {001}<130> orientation represented by Formula 1 below to the fraction of {334}<4-83> orientation of 1.45 or more and 1.80 or less. [Equation 1] {001}<130> fraction of directions / {334}<4-83> fraction of directions
  5. In Article 4, A method for manufacturing a non-oriented electrical steel sheet, wherein the crystal grain size of the hot-rolled annealed material is 350 μm or more and 500 μm or less.
  6. In Article 4 or Article 5, The step of manufacturing the above hot-rolled steel sheet is a method for manufacturing a non-oriented electrical steel sheet in which the finishing rolling temperature during hot rolling is 860°C or higher and 900°C or lower.
  7. In Article 4 or Article 5, Prior to the step of manufacturing the above hot-rolled annealed material, the method further includes the step of winding the hot-rolled steel sheet, The above-mentioned winding step is a method for manufacturing a non-oriented electrical steel sheet, wherein the winding temperature is 660°C or higher and 710°C or lower.
  8. In Article 4 or Article 5, A method for manufacturing a non-oriented electrical steel sheet, wherein the thickness of the hot-rolled steel sheet is 1.8 mm or more and 2.6 mm or less.
  9. In Article 4 or Article 5, A method for manufacturing a non-oriented electrical steel sheet, wherein the step of manufacturing the above cold-rolled steel sheet is performed such that the ratio of the roll speed of the upper cold-rolling roll located above the steel sheet to the roll speed of the lower cold-rolling roll located below the steel sheet (roll speed of the lower cold-rolling roll / roll speed of the upper cold-rolling roll) is 1.5 or more and 1.7 or less.
  10. In Article 4 or Article 5, The step of manufacturing the above hot-rolled annealed material is a method for manufacturing a non-oriented electrical steel sheet, wherein the heat treatment temperature is 950°C or higher and 1100°C or lower.
  11. In Article 10, The step of manufacturing the above hot-rolled annealed material is a method for manufacturing a non-oriented electrical steel sheet in which the average heating rate to the heat treatment temperature is 15℃/s or higher.
  12. In Article 4 or Article 5, A method for manufacturing a non-oriented electrical steel sheet, comprising the step of manufacturing the above-mentioned hot-rolled annealed material and heat treating for 200 seconds or more and 500 seconds or less.
  13. In Article 4 or Article 5, A method for manufacturing non-oriented electrical steel sheets, wherein the final annealing step is performed in a mixed atmosphere of hydrogen and nitrogen.
  14. In Article 4 or Article 5, The above final annealing step is a method for manufacturing a non-oriented electrical steel sheet, wherein the heat treatment temperature is 900°C or higher and 1100°C or lower.
  15. In Article 4 or Article 5, The above final annealing step is a method for manufacturing a non-oriented electrical steel sheet in which the average cooling rate after heat treatment is 30℃/s or higher.

Description

Non-oriented electrical steel sheet and method of manufacturing the same The present application relates to a non-oriented electrical steel sheet and a method for manufacturing the same. Recently, due to policies aimed at reducing CO2 emissions to prevent global warming, conventional internal combustion engine vehicles are being rapidly replaced by eco-friendly vehicles such as hybrid electric vehicles (HEVs) and, in particular, electric vehicles (EVs). These electric vehicles (EVs) must generate high torque at low speeds or during acceleration, and rotate at high speeds of over 200 Hz during constant speed and high-speed driving. Consequently, non-oriented electrical steel sheets, which serve as the core material for motors, must simultaneously satisfy high magnetic flux density and low iron loss. Factors affecting the magnetic properties of such non-oriented electrical steel include chemical composition, the size and distribution of inclusions, thickness, microstructure, insulating coating layer, and/or texture. These various factors are influenced by the manufacturing process conditions of the non-oriented electrical steel. Generally, non-oriented electrical steel is manufactured through the processes of steelmaking/continuous casting, hot rolling, pre-annealing, cold rolling, final annealing, and coating, and excellent magnetic properties can be achieved by optimizing the conditions of each process. Furthermore, to reduce iron loss in non-oriented electrical steel sheets, the sheet thickness must be reduced and the resistivity increased. However, reducing the sheet thickness requires advanced manufacturing technology and lowers productivity during the process, leading to increased costs during machining and lamination in the motor core manufacturing process. In addition, high-alloy elements such as Si, Al, and Mn are added to increase the resistivity of non-oriented electrical steel sheets. At this time, elements such as Ni and P may be added to improve the texture, including the {001} orientation which facilitates magnetization, and high-efficiency non-oriented electrical steel sheets can be manufactured through chemical composition control, such as managing impurities such as C, S, N, and Ti to extremely low levels to produce clean steel that does not interfere with magnetization. Patent Document 1 (Korean Published Patent No. 10-2024-0081966) discloses a method for manufacturing a non-oriented electrical steel sheet with excellent magnetic properties by reheating a semi-finished product, performing hot rolling, and then performing cold rolling and final annealing without performing a hot-rolled steel sheet annealing process after hot rolling. However, when the hot-rolled steel sheet annealing process is not performed, the microstructure becomes non-homogeneous, causing an increase in the average value of the iron loss value by angle of the final product, which results in a problem that it is not suitable for use as a core material for motors. Therefore, a non-oriented electrical steel sheet and a method for manufacturing the same are required to solve these problems. Embodiments of the present invention will be described in detail below. Furthermore, the scope of the present invention is not limited to the embodiments described below, and may be implemented with arbitrary modifications within the scope that does not deviate from the gist of the present invention. In the description of numerical ranges in this specification, the notation “X~Y” indicates X or greater and Y or less, unless otherwise specifically stated. Additionally, “greater than or equal to” may be replaced with “greater than,” and “less than or equal to” may be replaced with “less than.” In the numerical ranges described stepwise in this specification, an upper or lower limit value described in any numerical range may be substituted with an upper or lower limit value of another numerical range described stepwise, or may also be substituted with a value shown in the examples. The present application relates to a non-oriented electrical steel sheet, which is a core material used in a motor that converts electrical energy into mechanical energy. The ratio of the fraction of {001}<130> orientation represented by Formula 1 below to the fraction of {334}<4-83> orientation is 1.45 or more and 1.80 or less. [Equation 1] {001}<130> fraction of directions / {334}<4-83> fraction of directions The above non-oriented electrical steel sheet may have a ratio of the fraction of {001}<130> orientation represented by Equation 1 to the fraction of {334}<4-83> orientation of 1.47 or more, 1.48 or more, or 1.49 or more, and may be 1.79 or less, 1.78 or less, or 1.77 or less. According to the non-oriented electrical steel sheet of the present application, excellent magnetic properties can be obtained by satisfying the numerical range of the above-mentioned value calculated by Equation 1, and specifically, low iron loss and a low average iron loss value pe