| 摘要 |
PURPOSE: To prevent exfoliation of oxidation layer formed on silicon steel sheet during stress relief annealing that is conducted after inorganic film coated steel sheets are drawn into iron core. CONSTITUTION: The method for forming oxidation layer on silicon steel sheet is characterized in that the temperature inside decarburization furnace is set at 830 deg.C and the temperature of annealing furnace is set at 1010 deg.C when oxide film is deposited on silicon steel sheet inside annealing furnace; wet dew point of atmosphere gas inside the annealing furnace is set at 35 to 45 deg.C; flow rate of the atmosphere gas is set in decarburization zone as follows: H2 11 to 13 Nm¬3 /hr and N2 30 to 33 Nm¬3/hr, flow rate of the atmosphere gas is set in annealing zone as follows, H2 33 to 36 Nm¬3/hr, N2 123 to 125 Nm¬3/hr, flow rate of the atmosphere gas is set in cooling zone as follows, H2 33 to 35 Nm¬3/hr, N2 139 to 141 Nm¬3/hr; line speed is set at 38 to 41 MPM.
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