Patent number: 5507883
Abstract: A grain oriented electrical steel sheet having no significant glass film and having a high magnetic flux density and an excellent iron loss property, comprising, in terms of by weight, 2.5 to 4.5% of Si, the steel sheet having, as oxides on its surface, a glass film comprising 0.6 g/m.sup.2 or less in total of forsterite and spinel composed of MgO, SiO.sub.2 and Al.sub.2 O.sub.3 and an insulating coating having a thickness of 6 .mu.m or less, the face tension imparted on the surface of the steel sheet by the coating being in the range of from 0.5 to 2.0 kg/mm.sup.2. In the final box annealing of the steel sheet after primary recrystallization annealing, use is made of an annealing separator comprising 100 parts by weight of MgO and, added thereto, 2 to 30 parts by weight of at least one member selected from the group consisting of chlorides, carbonates, nitrates, sulfates and sulfides of Li, K, Bi, Na, Ba, Ca, Mg, Zn, Fe, Zr, Sr, Sn, Al, etc.
Type:
Grant
Filed:
June 9, 1994
Date of Patent:
April 16, 1996
Assignee:
Nippon Steel Corporation
Inventors:
Osamu Tanaka, Hiroaki Masui, Hotaka Honma, Katsuro Kuroki, Tsutomu Haratani, Yoichi Mishima, Maremizu Ishibashi, Yoshio Nakamura