ORIENTED ELECTROMAGNETIC STEEL SHEET FOR LOW-NOISE TRANSFORMER, AND METHOD FOR MANUFACTURING SAID SHEET

摘要

An oriented electromagnetic steel sheet processed using magnetic domain segmentation by the steel sheet surface being irradiated with an electron beam in a linear area having a direction intersecting with the rolling direction, wherein: the irradiation line area is made into repeating units made up of two types of areas comprising a retention area and a travel area; modulated-irradiation line areas are obtained by connecting the repeating units in the line-area direction; the period of the repeating units in the modulated-irradiation line area is 0.20-1.0 mm; the repeating interval of the modulated-irradiation line area in the rolling direction is 4.0-12.5 mm; and the intensity of the electron beam is brought to a level equal to or greater than that at which split magnetic domains are formed extending in the direction of the modulated-irradiation line area at least on the irradiation-surface side, and up to a level at which the coating is not damaged and no plastic strain areas are formed on the irradiation-surface side. It is thereby possible to carry out a hitherto challenging magnetic-domain segmentation process in a transformer in which iron loss and noise are both low, and obtain an oriented electromagnetic steel sheet that has unprecedentedly low iron loss and magnetic distortion.