| 摘要 |
A method for manufacturing a thick grain-oriented electrical steel sheet by a low temperature slab heating method capable of obtaining excellent magnetic properties by properly controlling decarburization annealing conditions according to low melt carbon content, thereby stably developing secondary recrystallization even in a thick electrical steel sheet is provided. In a grain-oriented electrical steel sheet manufacturing method comprising: reheating a slab comprising, by weight percent, 0.005 to 0.045% of C, 2.0 to 4.0% of Si, 0.05 to 0.5% of Mn, 0.002 to 0.015% of S, 0.01 to 0.05% of soluble Al, 0.003 to 0.012% of N, and the balance of Fe and inevitably contained elements at a temperature of 1,300 deg.C or less; hot rolling the reheated slab; annealing the hot rolled steel sheet at 700 to 1,200 deg.C for 10 minutes or less; cold rolling the annealed steel sheet to a final thickness of 0.36 to 0.6 mm; simultaneously decarburizing and nitriding the cold rolled steel sheet in a primary recrystallization annealing process; coating an annealing separator on the decarburized and nitrided steel sheet; subjecting the annealing separator coated steel sheet to a high temperature annealing process; and insulation-coating the high temperature annealed steel sheet with phosphate, colloidal silica and chromic acid, a method for manufacturing a thick grain-oriented electrical steel sheet comprises performing the primary recrystallization annealing process in a temperature range of satisfying the relational expression, 884-1,750C<=T<=948-1,000C, for 1 to 20 minutes such that a residual carbon amount becomes 30 ppm or less by considering content of melt carbon, wherein T is a primary recrystallization annealing temperature(deg.C), C is a melt carbon content(%), and 0.005<=C<=0.045. |
