Process for producing grain oriented silicon steel sheet, and decarburized sheet

摘要

Producing a grain oriented silicon steel sheet by controlling physical properties of the oxides layer, formed in decarburization annealing, in the surface layer of a steel sheet. A silicon compound is adhered to the surface of steel sheet before the decarburization annealing in an amount ranging from about 0.5 to 7.0 mg per square meter, expressed as Si, and the atmosphere of an earlier portion of the temperature holding process is adjusted to a ratio of steam partial pressure to the hydrogen partial pressure of less than about 0.7, and the atmosphere of the temperature rising process up to the temperature holding process is adjusted to an atmospheric composition lower than the atmospheric composition of the earlier portion of the temperature holding process, and the atmosphere of a later part of the temperature holding process is adjusted to an atmospheric composition lower than the atmospheric composition of the earlier part of the temperature holding process and in a range from about 0.005 to 0.2. <IMAGE>