| 摘要 |
PURPOSE:To produce an ultralow core loss grain oriented silicon steel sheet by annealing an extra low carbon high silicon hot rolled steel strip, thereafter subjecting it to cold rolling to regulate its sheet thickness into a final one and executing primary recrystallization annealing and finish annealing. CONSTITUTION:The hot rolled steel sheet of extra low silicon steel of 0.8 to 4.8wt.% Si and <100ppm C is annealed at 1100 deg.C and is thereafter subjected to cold rolling for one time or >= two times including process annealing to regulate its sheet thickness into a prescribed final one. Next, primary recrystallization annealing is executed in a nonoxidizing atmosphere to regulate the oxygen content in the steel sheet into <=200ppm. The surface of the steel sheet subjected to the primary recrystallization is electrostatically coated with a separation agent for annealing constituted of the powder of oxides such as MgO, Al2O3, SiO2, ZrO, BaO, CaO and SrO in a state in which water of hydration is not brought in a laminating manner, and finish annealing is executed to complete secondary recrystallization. Next, it is annealed in an atmosphere contg. at least >=50% hydrogen and is thereafter freed of the separation agent for annealing. The surface of the steel sheet is subjected to specular finishing and is purified, and domain subdividing treatment if executed by laser irradiation as necessary, by which the grain-oriented silicon steel sheet having excellent magnetic properties can be produced. |
