Grain oriented electrical steel sheet having high magnetic flux density and ultra low iron loss and process for producing the same

摘要: A grain oriented electrical steel sheet having no significant glass film and a high magnetic flux density an excellent iron loss property, comprising, in terms of by weight, 2.5 to 4.5% Si, the having, as oxides on its surface, comprising 0.6 g/m² or less total forsterite spinel composed MgO, SiO₂ Al₂O₃ insulating coating thickness 6 µm less, face tension imparted surface being range from 0.5 2.0 kg/mm². In final box annealing after primary recrystallization annealing, use is made separator 100 parts weight MgO and, added thereto, 2 30 at least one member selected group consisting chlorides, carbonates, nitrates, sulfates sulfides Li, K, Bi, Na, Ba, Ca, Mg, Zn, Fe, Zr, Sr, Sn, Al, etc., heating effected atmosphere N₂ H₂ with nitrogen content 30% more rate 20°C/hr seam spotty flaw angle 45 90° rolling direction sheet.