A METHOD FOR MANUFACTURING LOW TEMPERATURE SLAB HEATING GRAIN-ORIENTED ELECTRICAL STEEL SHEET WITH SUPERIOR MAGNETIC PROPERTY

摘要

PURPOSE: To manufacture grain-oriented electrical steel sheets with superior magnetic property, annealing condition of hot rolled steel sheet is properly controlled and then proper amount of N is added in steel via nitriding treatment to conserve inhibition power against crystal growth of Al precipitates. CONSTITUTION: The method includes the steps of hot rolling a steel slab comprising Si 2.0-4.0 wt.%, sol-Al 0.006-0.030 wt.%, N 0.007-0.013 wt.%, C 0.025-0.055 wt.%, Cu 0.3-1.0 wt.%, Mn 0.32 wt.% or less, S 0.007 wt.% or less, a balance of Fe and other inevitable impurities in the temperature range of 1250 to 1330C; after heating the hot rolled steel sheet to temperatures of 1000 to 1200C, keeping the hot rolled steel sheet within the temperature range of 800 to for 1000C for 30-600 seconds followed by quenching; primary cold rolling of the hot rolled steel sheet; process annealing the cold rolled steel sheet in a mixed gas atmosphere of dried hydrogen and nitrogen at 800 to 1000C; secondary cold rolling the cold rolled steel sheet in a reduction ratio of 70-45.%; decarburizing and nitriding the cold strips in wet atmosphere at 800-950C; and final hot annealing after applying an annealing separator mainly consisting of MgO.