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KR-20260064808-A - NON-ORIENTED ELECTRICAL STEEL SHEET AND METHOD FOR MANUFACTURING THE SAME

KR20260064808AKR 20260064808 AKR20260064808 AKR 20260064808AKR-20260064808-A

Abstract

The present application relates to a non-oriented electrical steel sheet and a method for manufacturing the same. According to the non-oriented electrical steel sheet and the method for manufacturing the same of the present application, excellent magnetic properties can be obtained.

Inventors

  • 첸 레이
  • 박세호
  • 강춘구

Assignees

  • 현대제철 주식회사

Dates

Publication Date
20260508
Application Date
20241029

Claims (15)

  1. In weight percent, C: greater than 0% and less than or equal to 0.005%, Si: greater than or equal to 3.8%, Mn: greater than or equal to 0.2% and less than or equal to 0.4%, Al: greater than or equal to 0.8% and less than or equal to 1.5%, Cu: greater than or equal to 0.5% and less than or equal to 2.2%, P: greater than 0% and less than or equal to 0.02%, S: greater than 0% and less than or equal to 0.005%, N: greater than 0% and less than or equal to 0.005%, Ti: greater than 0% and less than or equal to 0.005%, and the remainder being Fe and other unavoidable impurities, An obstructive electrical steel sheet satisfying the following Equation 1. [Equation 1] Equation 20[S]+2.1≥[Cu]≥20[S]+0.5 ([S] and [Cu] represent weight%.)
  2. In Article 1, Non-oriented electrical steel sheet having yield strength ( σy ) > 650 MPa, tensile strength ( σT ) > 750 MPa, iron loss (W10 /400 ) < 30 W/kg, and magnetic flux density ( B50 ) > 1.6 T.
  3. In Article 1 or Article 2, Non-oriented electrical steel sheet having a grain size of 80 μm or more and 100 μm or less.
  4. In Article 1 or Article 2, Non-oriented electrical steel sheet containing additional CuS precipitates.
  5. In Article 1 or Article 2, A non-oriented electrical steel sheet having an average diameter of the CuS precipitates of 10.0 nm or less and a number density of 0.01 × 10¹⁵ mm⁻³ or more and 100 × 10¹⁵ mm⁻³ or less.
  6. A step of manufacturing a hot-rolled steel sheet by reheating and hot-rolling a slab containing, in weight%, C: greater than 0% and less than or equal to 0.005%, Si: greater than or equal to 3.8%, Mn: greater than or equal to 0.2% and less than or equal to 0.4%, Al: greater than or equal to 0.8% and less than or equal to 1.5%, Cu: greater than or equal to 0.5% and less than or equal to 2.2%, P: greater than 0% and less than or equal to 0.02%, S: greater than 0% and less than or equal to 0.005%, N: greater than 0% and less than or equal to 0.005%, Ti: greater than 0% and less than or equal to 0.005%, and the remainder being Fe and other unavoidable impurities; A step of heat-treating the above hot-rolled steel sheet after hot rolling; A step of manufacturing a cold-rolled steel sheet by cold-rolling a steel sheet that has been heat-treated after hot rolling; A step of finally heat treating the above cold-rolled steel sheet; Step of coating the final heat-treated steel plate; and A method for manufacturing a non-oriented electrical steel sheet, comprising the step of aging a coated steel sheet.
  7. In Article 6, A method for manufacturing a non-directional electrical steel sheet satisfying the following Equation 1. [Equation 1] Equation 20[S]+2.1≥[Cu]≥20[S]+0.5 ([S] and [Cu] represent weight%.)
  8. In Article 6 or Article 7, Non-obstructive electrical steel sheet having a grain size of 80 μm or more and 100 μm or less, yield strength ( σy ) > 650 MPa, tensile strength ( σT ) > 750 MPa, iron loss (W10 /400 ) < 30 W/kg, and magnetic flux density ( B50 ) > 1.6 T.
  9. In Article 6 or Article 7, The step of manufacturing the above hot-rolled steel sheet is a method for manufacturing a non-oriented electrical steel sheet in which the reheating temperature is 1000℃ or higher and 1200℃ or lower.
  10. In Article 6 or Article 7, The step of manufacturing the above hot-rolled steel sheet is a method for manufacturing a non-oriented electrical steel sheet in which the hot-rolling finishing temperature is 800°C or higher and 900°C or lower.
  11. In Article 6 or Article 7, The step of manufacturing the above hot-rolled steel sheet is a method for manufacturing a non-oriented electrical steel sheet in which the coiling temperature after rolling is 500℃ or higher and 650℃ or lower.
  12. In Article 6 or Article 7, A method for manufacturing a non-oriented electrical steel sheet, wherein the step of heat treatment after hot rolling is performed by heat treatment at a starting temperature of 900℃ or higher and 1100℃ or lower, a heating rate of 10℃/s or higher, and for a duration of 30 seconds or higher and 90 seconds or lower after hot rolling.
  13. In Article 6 or Article 7, A method for manufacturing a non-oriented electrical steel sheet, wherein the step of heat treatment after cold rolling is performed by heat treatment at a temperature of 900°C or higher and 1100°C or lower, a heating rate of 10°C/s or higher and 80°C/s or lower, and heat treatment for 30 seconds or higher and 90 seconds or lower after cold rolling.
  14. In Article 6 or Article 7, A method for manufacturing a non-oriented electrical steel sheet, wherein the aging treatment step involves heating to a temperature of 490°C or higher and 600°C or lower, and maintaining for 4 minutes or more and 16 minutes or less.
  15. In Article 6 or Article 7, A method for manufacturing a non-oriented electrical steel sheet, wherein the thickness of the above cold-rolled steel sheet is 0.10 mm or more and 0.35 mm or less.

Description

Non-oriented electrical steel sheet and method for 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). Drive motors, which are core components of these new energy vehicles, must achieve higher speeds, smaller sizes, and higher efficiency. To this end, electric motor steel sheets with high magnetic induction strength, low iron loss, and high strength are required. However, the magnetic properties and strength of electrical steel sheets are mutually limiting to achieve the optimal balance, which is a critical issue that must be addressed for the development of high-performance non-oriented electrical steel sheets. To this end, there is a requirement for non-oriented electrical steel sheets used as motor core materials to possess excellent magnetic properties and improved strength. 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 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. This application relates to non-oriented electrical steel sheets, which are core materials used in motors that convert electrical energy into mechanical energy. To improve motor efficiency in permanent magnet synchronous motors, the width between the magnet pocket and the stator must be reduced. However, if the width between the magnet pocket and the stator is reduced, the centrifugal force acting on the rotor bridge exceeds the yield strength that the electrical steel sheet can withstand during high-speed rotation. Therefore, high-strength materials are required for the rotors of high-speed rotating machines. Furthermore, the materials used in the motor must minimize eddy current losses caused by high frequencies. In this regard, since iron loss generally tends to increase as the strength of non-oriented electrical steel improves, it is difficult to achieve excellent results in both strength and iron loss. Therefore, it is important to adjust the composition and manufacturing methods of non-oriented electrical steel to minimize iron loss degradation while improving its strength. The above non-oriented electrical steel sheet comprises, in weight percent, C: greater than 0% and less than or equal to 0.005%, Si: greater than or equal to 3.8%, Mn: greater than or equal to 0.2% and less than or equal to 0.4%, Al: greater than or equal to 0.8% and less than or equal to 1.5%, Cu: greater than or equal to 0.5% and less than or equal to 2.2%, P: greater than 0% and less than or equal to 0.02%, S: greater than 0% and less than or equal to 0.005%, N: greater than 0% and less than or equal to 0.005%, Ti: greater than 0% and less than or equal to 0.005%, and the remainder being Fe and other unavoidable impurities, satisfying the following Equation 1, and having a yield strength ( σy ) > 650 MPa, a tensile strength ( σT ) > 750 MPa, an iron loss (W10 /400 ) < 30 W/kg, and a magnetic flux density ( B50 ) > 1.6 T, and is non-directional. It is an electrical steel sheet. [Equation 1] Equation 20[S]+2.1≥[Cu]≥20[S]+0.5 ([S] and [Cu] represent weight%.) Equation 1 above formulas the control of the copper content in the composition of a non-oriented electrical steel sheet to a certain range relative to the sulfur content. By controlling the copper content to satisfy the range of Equation 1, the size and number density of copper sulfide (CuS) precipitates can be controlled. When the copper content satisfies the range of Equation 1, the strength of the non-oriented electrical steel sheet can be sufficiently improved, while minimizing the deterioration of iron loss relative to the improved strength. On the other hand, if the copper content has a value smaller than the lower limit of Equation 1, it is difficult to achieve excellent yield strength and tensile strength. Furthermore, if the copper content has a value larger than the upper limit of Equation 1, excellent yield strength and tensile strength are achieved, but the deterioration of iron loss increases, making it difficult to achieve excellent magnetic properties. In other words, by controlling the copper content to satisfy the range of Equation 1, it is possible to achieve excellent yield strength and tensile strength while suppressing the deterioration of iron loss