PRODUCTION OF GRAIN ORIENTED SILICON STEEL SHEET HAVING EXTREMELY HIGH MAGNETIC FLUX DENSITY AND LOW IRON LOSS

摘要

PURPOSE:To produce a grain oriented silicon steel sheet having a low iron loss and high magnetic flux density by segmenting the surface of the steel sheet to a decarburization accelerating resion and decarburization retarding region by a decarburization adjusting liquid and annealing the steel sheet in the stage of subjecting the grain oriented silicon steel sheet to decarburization and primary recrystallization annealing. CONSTITUTION:A grain oriented silicon steel slab is hot rolled and is then subjected to one pass of cold rolling or two passes of cold rolling including intermediate annealing to a final sheet thickness. The rolled sheet is then subjected to decarburization and primary recrystallization annealing and is further subjected to secondary recrystallization annealing and purification annealing after MgO is coated thereon as a separating agent for annealing. A dilute aq. soln. of Mg(NO3)2 as the decarburization accelerator and the aq. dilute soln. of MgSO4 as the decarburization retarder are coated at 0.3mm width and 5mm interval on the steel sheet in the direction perpendicular to the rolling direction in the stage of the decarburization and primary recrystallization annealing of this case. Both aq. solns. to be used are coated under the conditions iof 40-100 deg.C soln. and 20-300 deg.C steel sheet temp.