LOW-IRON-LOSS DIRECTIONAL ELECTROMAGNETIC STEEL SHEET

摘要

PURPOSE: To obtain a directional electromagnetic steel sheet realizing large reduction of an iron loss by a method wherein an insulating film constituted of fine crystal particles and having a tensile force giving effect is formed on the surface of the directional electromagnetic steel sheet of which finishing annealing is completed. CONSTITUTION: A directional electromagnetic steel sheet having an insulating film constituted of a crystalline oxide. It is a low-iron-loss directional electromagnetic steel sheet of which the crystalline material has a thremal expansion coefficient of 9×10<-6> / deg.C or below and a very small particle size of 80nm or below and has a grain boundary layer being an amorphous layer of a thickness within a range of 1/10-1/5 of the particle size.