| 摘要 |
PROBLEM TO BE SOLVED: To obtain a grain oriented silicon steel sheet with ultralow iron loss by forming grooves under specific conditions in the course of final cold rolling and also using Al2 O3 as a separation agent at annealing, at the time of producing a grain oriented silicon steel sheet from a slab of silicon steel with specific composition. SOLUTION: A grain oriented silicon steel sheet is produced by the conventional method from a silicon steel slab having a composition consisting of, by weight, <=0.085% C, 2.5-4.5% Si, 0.050-0.45% Mn, <=0.015% S, 0.010-0.040% acid soluble Al, <=0.010% N, 0.02-0.15% Sn, and the balance Fe with inevitable impurities. At this time, in the stage of intermediate sheet thickness at the final cold rolling, grooves, having 10-150μm width, t×1/8 to t×1/30 depth [where (t) means sheet thickness], and 1-20mm spacing in rolling direction, are formed into dotlike or linear state in the surface of the steel sheet, at 90 to 45 deg. with respect to rolling direction. Subsequently, rolling is carried out to the final sheet thickness, and, after the application of Al2 O3 as a separation agent at annealing, finish annealing and tension coating are applied to the steel sheet. By this method, the grain oriented silicon steel sheet with ultralow iron loss, free from forsterite film, can be easily obtained. |
