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

摘要

PURPOSE:To produce the grain oriented electrical steel sheet having a uniform glass film and excellent magnetic characteristics by using an MgO-contg. annealing and separating agent obtd. by forming an OH chemical adsorption layer under specific conditions on an Mg compd. obtd. by calcination at the time of subjecting a decarburization annealed grain oriented silicon steel sheet to a finish annealing. CONSTITUTION:A scale layer essentially consisting of SiO2 is formed on the cold rolled grain oriented silicon steel stock having the final sheet thickness by the decarburization annealing thereof and thereafter, the annealing and separating agent essentially consisting of the MgO is applied thereon and the steel stock is subjected to the finish annealing. The annealing and separating agent which is obtd. by calcining the Mg compd. consisting of one or =2 kinds of magnesium hydroxide, basic magnesium carbonate, magnesium carbide, and magnesium sulfate and is then formed with the OH chemical adsorption layer at 0.8 to 2.5 in terms of H2O based on the weight of the MgO by treating the MgO in a steam-contg. vapor phase kept at =100 deg.C is used in this case. The film defects are drastically decreased in this way and the grain oriented electrical steel sheet having the excellent magnetic characteristics is obtd.