IPMモータのロータ鉄心用鋼板、その製造方法およびIPMモータのロータ鉄心

Japanese Patent JP5448979

B2

PROBLEM TO BE SOLVED: To provide a steel sheet for the rotor iron core of an IMP motor which has satisfactory punching workability, has high yield strength when being made into a rotor iron core, and also has excellent magnetic properties.SOLUTION: The steel sheet is obtained by subjecting a hot rolled steel sheet having a componential composition comprising, by mass, 0.05 to 0.35% C, 0.05 to 1.0% Si, 0.2 to 1.5% Mn, ≤0.05 P, ≤0.02% S, 0.005 to 2.95% acid soluble Al and also Si+Al: ≤3.0%, and the balance Fe with inevitable impurities to cold rolling for one time or for two or more times including intermediate annealing into a prescribed sheet thickness, and subjecting the steel sheet to three step annealing including the first heat treatment of holding the steel sheet in the temperature range of Ac-50°C to