| 摘要 |
PURPOSE:To obtain a grain-oriented silicon steel sheet having a low iron loss without deterioration of the characteristic by stress relief annealing by delineating and forming regions consisting of different insulating films having the compsn. different from the compsn. of forsterite on the surface of the steel sheet. CONSTITUTION:A slilicon-bearing steel slab is hot-and cold-rolled to a final thickness and is then subjected to decarburization and primary recrystallization annealing. A material which reacts with SiO2 and a material which solutionizes with forsterite are locally stuck at >=0.01g/m<2> to the surface of such steel sheet. A separating agent for annealing consisting principally of MgO is then coated thereon and thereafter the steel is subjected to secondary recrystallization annealing and purification annealing. A glass film region which is different from forsterite, is continuous or discontinuous and has 60-90 deg. angle with the rolling direction of the steel sheet is formed on the surface of the steel sheet after the purification annealing. An insulation coating film of a tension applying type having <=9.8X10<-6>/ deg.C coefft. of thermal expansion is formed on said film. |
