Method For Manufacturing Grain Oriented Electromagnetic Steel Sheet

Abstract: This method for manufacturing a grain oriented electromagnetic steel sheet comprises: a hot rolling step; a hot rolled sheet annealing step; a cool rolling step; a decarburization annealing step; an annealing separator application step; a nitriding step; and a finishing annealing step. The finishing annealing step includes a heating process and a homogenizing process and at least in a certain period from the start of secondary recrystallization in the heating process until the completion of the secondary recrystallization a temperature gradient of 0.5???/cm or more is generated in a boundary area between a primary recrystallization area and a secondary recrystallization area. The nitriding step is performed through annealing in an atmosphere containing nitriding gas in at least one stage during the decarburization annealing step between the decarburization annealing step and the finishing annealing step or until the start of the secondary recrystallization in the heating process of the finishing annealing step. The nitrogen content of the steel sheet after the nitriding step is on a mass basis 210 ppm or more.

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