Process for producing grain-oriented electrical steel sheet having superior magnetic and surface film characteristics

Abstract

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.degree. 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, 0.080 to 0.045 wt % Mn, and the balance consisting of Fe and unavoidable impurities; hot-rolling the heated 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 separator to the decarburization-annealed sheet; and final-annealing the annealing separator-applied sheet.

Dependencies are inferred from the claim text.