Method for producing non-oriented electrical steel sheet, method for producing motor core, and motor core

A motor core constituted with

• a rotor core made of a non-oriented electrical steel sheet having a component composition comprising C:
• not more than 0.0050 mass %, Si:
• 2.8 to 6.5 mass %, Mn:
• 0.05 to 2.0 mass %, P:
• not more than 0.10 mass %, S:
• not more than 0.0050 mass %, Al:
• 0.3 to 2 mass %, N:
• not more than 0.0050 mass %, Zn:
• 0.0005 to 0.0050 mass %, Ti:
• not more than 0.0030 mass %, Nb:
• not more than 0.0030 mass %, 0:
• not more than 0.0050 mass %, satisfying Si+Al≥4 mass % and the remainder being Fe and inevitable impurities and
• a stator core made of the same non-oriented electrical steel sheet,
• characterized in that
• the steel sheet constituting the rotor core has a yield stress of not less than 480 MPa;
• N1, N2 and t in the steel sheet constituting the stator core satisfy the following equation (2):
• (t×N2)/{(t/10)×N1}≥5.0 (2),
• where N1 (mass %) is a content of nitrogen present as AlN (N as AlN) in a layer from a one-side surface to 1/20 of a sheet thickness and N2 (mass %) is a content of nitrogen present as AlN in a full sheet thickness (N as AlN) and t (mm) is a sheet thickness of the steel sheet;
• and
• an iron loss W10/400 (W/kg) satisfies the following equation (3) in relation to the sheet thickness t (mm):
• W10/400≤8+20×t (3).