PRODUCTION OF GRAIN ORIENTED ELECTRICAL STEEL SHEET HAVING UNIFORM GLASS FILM AND EXCELLENT MAGNETIC CHARACTERISTIC

摘要

PURPOSE:To produce a grain oriented electrical steels sheet having a uniform glass film and excellent magnetic characteristics by using MgO formed by forming a prescribed amt. of a hydration layer on only the extreme surface layer of the low-activity MgO obtd. by calcination of an Mg compd. such as magnesium hydroxide which is a raw material at a relatively high temp. to activate said surface as a separating agent for annealing. CONSTITUTION:A silicon steel slab is subjected to hot rolling and annealing then to 1 or >=2 passes of cold rolling including intermediate annealing followed by decarburization annealing. After the separating agent for annealing is coated on such steel sheet, the steel sheet is subjected to final finish annealing to produce the grain oriented electrical steel sheet. Said separating agent for annealing is formed by forming the hydration layer on the extreme surface layer of the particles of the MgO of a low hydration characteristic obtd. by the high-temp. calcination of the Mg compd. such as magnesium hydroxide or magnesium carbonate to activate said surface then adding 1 or >=2 kinds of Ti, B and S compds. to such MgO.