Patent ID: RE39482

Claim:
A method of manufacturing a grain-oriented magnetic steel sheet, comprising the steps of hot-rolling a steel slab containing up to about 0.12 wt % C, from about 1.0 to 8.0 wt % Si, and from about 0.005 to 3.0 wt % Mn, optionally applying annealing to the resulting hot-rolled steel sheet, subjecting said annealed sheet or said hot-rolled sheet to one or more runs of cold rolling including intermediate annealing in between , optionally applying to the intermediate annealed cold- rolled sheet decarburization annealing, optionally coating the intermediate annealed cold- rolled sheet or the decarburized annealed sheet with an annealing separator and then applying final finish annealing; wherein: (1) the O content of said steel slab is limited to up to about 30 wtppm; (2) for the entire steel sheet having final thickness including oxide film before final finish annealing, the Al content is limited to up to about 100 wtppm, and the respective contents of B, V, Nb, Se, S, P, and N, are limited to up to about 50 wtppm each; and (3) during final finish annealing, the N content in the steel is limited within a range of from about 6 to 80 ppm, at least in a temperature region of from from 850 to 950Â° C.