PRODUCTION OF LOW CORE LOSS GRAIN ORIENTED SILICON STEEL SHEET

PROBLEM TO BE SOLVED: To stably obtain a grain oriented silicon steel sheet which is low in core loss by subjecting a slab for the grain oriented silicon steel sheet to hot rolling and cold rolling to a final thickness, then forming an etching mask, forming linear or dotted grooves by electrolytic etching and subjecting this slab to final finish annealing. SOLUTION: The slab for the grain oriented silicon steel sheet contg. 2 to 4% Si is hot rolled to a hot rolled sheet and this sheet is subjected to one time or >=2 times of cold rolling including intermediate annealing to the cold rolled sheet having the final thickness. Next, an etching resist is applied on the surface of the cold rolled sheet and is dried and backed to form the etching mask. The linear or dotted grooves are formed by the electrolytic etching on the steel sheet surface. Finally, the mask is removed and the steel sheet is subjected to decarburization annealing and final finish annealing, by which the low core loss grain oriented silicon steel sheet is produced. The application of the etching resist maintains the relation -0.25L+90>D>-25L+75 between a mesh size (L) (100 to 200 mesh/inch) and mesh depth D (30 to 60 μm).