| 摘要 |
PURPOSE: Provided is a method for manufacturing oriented electrical steel sheets having superior punchability and free of surface defects where the formation of glass film in edge parts is restrained and also production cost is reduced by adding TiO2 powder to a fusion preventing agent as well as increasing partial pressure of nitrogen of atmospheric gas composition when final annealing at a high temperature. CONSTITUTION: In a manufacturing method of oriented electrical steel sheets where a steel slab comprising Si 2.9-3.4wt.%, C 0.045-0.062wt.%, P 0.015-0.035wt.%, sol-Al 0.022-0.032wt.%, N 0.006-0.009wt.%, S 0.004-0.010wt.%, Mn 0.008-0.012wt.%, Cu 0.012-0.021wt.%, a balance of Fe, and other inevitable impurities is reheated in the temperature range of 1150 to 1190deg.C; hot rolled; annealed at 1100deg.C or lower; pickled; cold rolled to final thickness; decarburized-nitrided under wet gas comprising ammonia, hydrogen, and nitrogen atmospheric condition of 840 to 890deg.C; applied with a fusion prevention agent; coiled; heat-treated under nitrogen contained hydrogen atmospheric condition for at least 20hrs in the temperature range of 1200±10deg.C after temperature elevation within the range of 700 to 1200deg.C at a temperature elevation rate of at least 15deg.C/hr; finish annealed at high temperature; and then coated with a tension coating agent, the present invention is characterized in that the fusion preventing agent comprises 3-6wt.% of silica, 1-6wt.% of TiO2 powder, and an effective amount of MgCl2 that satisfies the following: MgCl2(%)=9.5xSiO2(g/m2)±0.4 wherein SiO2 represents the amount of SiO2 existing in the decarburized/nitrided steel sheet.
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