BASE SHEET FOR GRAIN-ORIENTED ELECTRICAL STEEL SHEET, GRAIN-ORIENTED SILICON STEEL SHEET WHICH IS USED AS MATERIAL OF BASE SHEET FOR GRAIN-ORIENTED ELECTRICAL STEEL SHEET, METHOD OF MANUFACTURING BASE SHEET FOR GRAIN-ORIENTED ELECTRICAL STEEL SHEET, AND METHOD OF MANUFACTURING GRAIN-ORIENTED ELECTRICAL STEEL SHEET

摘要

In a base sheet for a grain-oriented electrical steel sheet of the present invention, an amount of surface oxygen x per one surface of the base sheet and a value y of a peak (ΔR/R0 @1250 cm−1) of SiO2 on the surface of the base sheet obtained by infrared reflection spectroscopy satisfy y≥1500x2.5 and y≥0.24. A method of manufacturing the base sheet for a grain-oriented electrical steel sheet of the present invention includes: adjusting the amount of surface oxygen per one surface of a final-annealed grain-oriented silicon steel sheet to more than 0.01 g/m2 and 0.05 g/m2 or less, or more than 0.05 g/m2 and 0.10 g/m2 or less; and performing thermal oxidation annealing in an atmosphere in which an oxidation potential represented by a ratio PH2O/PH2 of water vapor pressure to hydrogen pressure is 0.0081 or less in a case where the amount of surface oxygen is more than 0.01 g/m2 and 0.05 g/m2 or less, or in an atmosphere in which the oxidation potential is 0.005 or less in a case where the amount of surface oxygen is more than 0.05 g/m2 and 0.10 g/m2 or less, at a soaking temperature of 1000° C. or lower to form an externally oxidized layer on a surface of the grain-oriented silicon steel sheet.