METHOD FOR PRODUCING NON-ORIENTED ELECTROMAGNETIC STEEL SHEET, METHOD FOR PRODUCING MOTOR CORE, AND MOTOR CORE

摘要

In the production of a non-oriented electrical steel sheet by hot rolling and cold rolling a steel slab containing by mass% C: not more than 0.0050%, Si: 2-7%, Mn: 0.05-2.0%, P: not more than 0.2%, S: not more than 0.005%, Al: not more than 3%, N: not more than 0.005%, Ti: not more than 0.003%, Nb: not more than 0.005% and V: not more than 0.005% and then subjecting to a finish annealing and a stress-relief annealing, conditions of the finish annealing and stress-relief annealing are adjusted so that a yield stress of the steel sheet after the finish annealing is not less than 400 MPa and a ratio (B_50S/B_50H) of a magnetic flux density B_50S of the steel sheet subjected to the stress-relief annealing after the finish annealing to a magnetic flux density B_50H of the steel sheet after the finish annealing is not less than 0.99, whereby a non-oriented electrical steel sheet being high in the strength after the finish annealing and small in the decrease of magnetic flux density after the stress-relief annealing is obtained. Also, a motor core is produced by using such a steel sheet.