| 摘要 |
PURPOSE:To reduce iron loss after stress relief annealing by forming a specific insulating film on the surface of a finish-annealed silicon steel sheet and then locally forming regions increased in crystallinity on the above insulating film. CONSTITUTION:A silicon slab is hot rolled and then subjected to finish annealing. At this time, a separation agent at annealing is selected, if necessary, and a forsterite film is formed on the steel sheet surface. An insulating film composed principally of phosphate and colloidal silica is formed on the above steel sheet surface. Subsequently, e.g., by applying electron beam in vacuum in a direction perpendicular to the rolling direction, regions having a crystallinity higher than that of the original surface can be locally formed on the above insulating film. By this method, a grain-oriented silicon steel sheet of low iron loss free from deterioration in properties due to stress relief annealing can be provided. |
