A METHOD FOR MANUFACTURING GRAIN ORIENTED ELECTRICAL STEEL SHEET WITH HIGH MAGNETIC INDUCTION USING LOW TEMPERATURE SLAB REHEATING PROCESS

摘要

PURPOSE: A method for manufacturing oriented electrical steel sheet having high magnetic flux density. CONSTITUTION: The oriented electrical steel sheet having high magnetic flux density is manufactured by (i) reheating a steel slab comprising C 0.020-0.070wt.%, Si 2.90-3.30wt.%, Mn 0.05-0.30wt.%, B 0.0005-0.005wt.%, P 0.03-0.09wt.%, Al 0.01wt.% or less, S 0.007wt.% or less, Cu 0.03-0.30wt.%, Sn 0.04-0.15wt.%, Cr 0.03-0.20wt.%, a balance of Fe, and other inevitable impurities in the temperature range of 1150 to 1320deg.C; hot rolling; (ii) annealing the hot rolled steel sheet; cold rolling it to 0.4-0.7mm; (iii) decarburizing annealing for 30sec-10min. in the temperature range of 800 to 900deg.C under nitrogene contained gas atmospheric condition; (iv) nitriding the steel sheet for 30sec-10min. under nitrogen gas atmospheric condition of 750-900deg.C wherein the nitrogene gas satisfies the follow equation: T(C) = 100t - 52 (T: dew point(C), t: thickness of final cold rolled steel sheet(mm)); (v) applying a fusion preventing agent; and then finish annealing at high temperature. The nitrogen content of the final oriented electrical steel sheet reaches from 150 to 250ppm.