Non-oriented electrical steel sheet and manufacturing method therefor
A non-oriented electrical steel sheet according to an embodiment of the present invention comprises Si: 2.0 to 3.5%, Al: 0.3 to 3.5%, Mn: 0.2 to 4.5%, Zn: 0.0005 to 0.02% in wt % and Fe and inevitable impurities as a balance amount.
1. A non-oriented electrical steel sheet, comprising:
Si: 2.0 to 3.5%, Al: 0.3 to 3.5%, Mn: 0.2 to 4.5%, Zn: 0.0005 to 0.02% in wt %, Y: 0.0005 to 0.01% and Fe and inevitable impurities as a balance amount,
wherein the non-oriented electrical steel sheet comprises an inclusion, and the inclusion having a diameter of 0.5 to 1.0 μm is 40 vol % or more of the total inclusion, and
wherein the non-oriented electrical steel sheet satisfies the following Formula 1:
[Zn]/[Y]>1 Formula 1
wherein [Zn] and [Y] represent the contents (wt %) of Zn and Y, respectively.
2. The non-oriented electrical steel sheet of claim 1 , satisfying the following Formula 2
[Zn]+[Y]≤0.025 [Formula 2]
wherein [Zn] and [Y] represent the contents (wt %) of Zn and Y, respectively.
3. The non-oriented electrical steel sheet of claim 1 , further comprising
N: 0.0040% or less (excluding 0%), C: 0.0040% or less (excluding 0%), S: 0.0040% or less (excluding 0%), Ti: 0.0040% or less (excluding 0%), Nb: 0.0040% or less (excluding 0%), and V: 0.0040% or less (excluding 0%).
4. The non-oriented electrical steel sheet of claim 1 , wherein an inclusion having a diameter of 2 μm or less is 80 vol % or more of the total inclusion.
5. The non-oriented electrical steel sheet of claim 1 , wherein
the non-oriented electrical steel sheet comprises an inclusion, and the area of the total inclusion is 0.2% or less with respect to the area of the total non-oriented electrical steel sheet.
6. The non-oriented electrical steel sheet of claim 1 , wherein
an average particle diameter of a crystal grain is 50 to 95 μm.
7. A method for manufacturing a non-oriented electrical steel sheet comprising:
heating a slab comprising Si: 2.0 to 3.5%, Al: 0.3 to 3.5%, Mn: 0.2 to 4.5%, Zn: 0.0005 to 0.02%, Y: 0.0005 to 0.01% in wt % and Fe and inevitable impurities as a balance amount;
performing hot rolling on the slab to manufacture a hot rolled sheet;
performing cold rolling on the hot rolled sheet to manufacture a cold rolled sheet; and
performing final annealing on the cold rolled sheet,
wherein the non-oriented electrical steel sheet comprises an inclusion, and the inclusion having a diameter of 0.5 to 1.0 μm is 40 vol % or more of the total inclusion, and
wherein the non-oriented electrical steel sheet satisfies the following Formula 1:
[Zn]/[Y]>1 [Formula 1]
wherein [Zn] and [Y] represent the contents (wt %) of Zn and Y, respectively to thereby manufacture the non-oriented electrical steel sheet according to claim 1 .
8. The method of claim 7 , wherein
the slab satisfies the following Formula 2
[Zn]+[Y]≤0.025 [Formula 2]
wherein [Zn] and [Y] represent the contents (wt %) of Zn and Y, respectively.
9. The method of claim 7 , wherein
the slab further comprises N: 0.0040% or less (excluding 0%), C: 0.0040% or less (excluding 0%), S: 0.0040% or less (excluding 0%), Ti: 0.0040% or less (excluding 0%), Nb: 0.0040% or less (excluding 0%), and V: 0.0040% or less (excluding 0%).
10. The method of claim 7 , further comprising
performing hot rolled sheet annealing on the hot rolled sheet after the step of manufacturing a hot rolled sheet.
11. The method of claim 7 , wherein
an annealing temperature in the step of performing final annealing on the cold rolled sheet is 850 to 1050° C.
12. The method of claim 11 , comprising
cooling at a cooling rate of 25 to 50° C./sec to 600° C., after the step of performing final annealing on the cold rolled sheet.
13. The method of claim 7 , further comprising
manufacturing molten steel;
adding Si ferro alloy, Al ferro alloy and Mn ferro alloy to molten steel;
adding Zn to molten steel and bubbling using an inert gas; and
performing continuous casting to manufacture a slab before the step of heating the slab.