Verfahren zur Herstellung kornorientierter Elektrobleche mit verbesserten magnetischen Eigenschaften und besserer Oberflächenschicht

A process for producing a grain-oriented steel sheet having superior magnetic and surface film characteristics, which comprises the steps of: heating to a temperature of 1200 DEG C or lower an electrical steel slab comprising 0.025 to 0.075 wt% C, 2.5 to 4.5 wt% Si, 0.012 wt% or less S, 0.010 to 0.060 wt% acid-soluble Al, 0.010 wt% or less N, 080 to 0.45 wt% Mn, and the balance consisting of Fe and unavoidable impurities; hot-rolling the hated slab to form a hot-rolled steel sheet; cold-rolling the hot-rolled sheet to a final product sheet thickness by single cold rolling step or by two or more steps of cold rolling with an intermediate annealing therebetween; decarburization-annealing the cold-rolled sheet under a condition such that decarburization alone is effected until primary-recrystallized grains grow to an average grain size of at least 15 mu m, and thereafter, concurrently effecting a decarburization and nitriding; applying an annealing separate to the decarburization-annealed sheet; and final-annealing the annealing separator-applied sheet.