BASE SHEET FOR GRAIN-ORIENTED ELECTRICAL STEEL SHEETS, GRAIN-ORIENTED SILICON STEEL SHEET THAT SERVES AS MATERIAL FOR BASE SHEET FOR GRAIN-ORIENTED ELECTRICAL STEEL SHEETS, METHOD FOR PRODUCING BASE SHEET FOR GRAIN-ORIENTED ELECTRICAL STEEL SHEETS, AND METHOD FOR PRODUCING GRAIN-ORIENTED ELECTRICAL STEEL SHEETS

摘要

For this base sheet for grain-oriented electrical steel sheets, the oxygen amount x per one side of the surface of the base sheet and the value y of the SiO₂ peak (ΔR/R₀ @ 1250 cm^-1) of the surface of the base sheet obtained by reflectance infrared spectroscopy satisfy y≥1500x^2.5 and y≥0.24. This method for producing a base sheet for grain-oriented electrical steel sheets is provided with: a step for regulating the amount of surface oxygen per one side of a finish-annealed grain-oriented silicon steel sheet to greater than 0.01 g/m² to 0.05 g/m² or greater than 0.05 g/m² to 0.10 g/m²; and a step for forming an external oxide layer on the surface of the grain-oriented silicon steel sheet by performing thermal oxide annealing at a soaking temperature of not more than 1000°C in an atmosphere in which the oxidation potential represented by the ratio P_H2O/P_H2 of the water vapor pressure to hydrogen pressure is not more than 0.0081 when the amount of surface oxygen is greater than 0.01 g/m² to 0.05 g/m² and in an atmosphere in which the oxidation potential is not more than 0.005 when the amount of surface oxygen is greater than 0.05 g/m² to 0.10 g/m².