PRODUCTION OF GRAIN ORIENTED SILICON STEEL SHEET HAVING LOW IRON LOSS

摘要

PURPOSE:To produce a silicon steel sheet having an excellent iron loss characteristc in the stage of subjecting a hot rolled sheet of a high silicon steel to decarburization annealing and final finish annealing after cold rolling and producing a grain oriented silicon steel sheet by subjecting locally the steel sheet to a high temp. quick heating treatment in short time in the stage of decarburization annealing. CONSTITUTION:A hot-roll sheet of a grain oriented silicon steel contg. 2.0-4.5% Si is subjected to 1 or 2 passes of cold rolling including intermediate annealing to produce a cold-rolled steel sheet having the final thickness. The steel sheet is then subjected to decarburization annealing serving also as primary recrystallization annealing in which the steel sheet is subjected to a heating treatment for 0.01-60sec at the temp. higher by >=100 deg.C than the temp. of the steel sheet and <=1,000 deg.C by a laser light source, etc. in the continuous or discontinuous linear region approximately perpendicular to the rolling direction of the steel sheet as shown in the figure in the temp. elevating stage up to the annealing temp. The linear region to be heated is of the shape having 0.1-30mm. width l and 1-100mm. space (d) and the total area thereof is made 3-50% the entire part of the steel sheet. A separating agent for annealing consisting principally of MgO is finally coated on the steel sheet and the final finish annealing is performed.