PURPOSE: To manufacture nonoriented electrical sheet exhibiting low iron loss and no magnetic ageing, by hot rolling and cold rolling of nonoriented electrical steel slab having specific composition contg. C, Si, S, Al, etc. to a final sheet thickness, and by annealing it in a nondecarburizing atmosphere gas of specific conditions.
CONSTITUTION: Nonoriented electrical steel slab consisting by weight. of ≤0.003% C, 1.5W3.5% Si, ≤0.005% S, 0.1W1.5% Al, ≤0.005% N, the balance being Fe and inevitable impurities is hot and cold rolled to a final sheet thickness. Then it is annealed in nondecarburizing atmosphere contg. ≥45% H2 (≥60% preferably). Hereby the formation of oxides such as SiO2, Al2O3, and at the same time the formation of nitride are prevented.
TANAKA TOSHIHIKO
MOCHINAGA KISHIO
