| 摘要 |
PURPOSE:To produce a grain-oriented silicon steel sheet excellent in magnetic properties by annealing a hot rolled plate of silicon steel, subjecting the plate to one or more cold rollings including final cold rolling at specific draft and also including, if necessary, process annealing between cold rolling stages, and then applying decarburizing annealing and final finish annealing to the resulting sheet. CONSTITUTION:A slab of a silicon steel which has a composition containing, by weight, 0.03-0.10% C, 2.5-4.0% Si, 0.010-0.065% acid soluble Al, 0.0010-0.0150% N, 0.02-0.30% Mn, and 0.005-0.040% S or further containing one or >=2 kinds among <=0.4% each of Sn, Cu, Sb, and Se is hot-rolled at 1300 deg.C, and the resulting hot rolled plate is annealed. Subsequently, the hot rolled plate is cold-rolled one or more times while process-annealed between cold rolling stages and then subjected to final cold rolling at >=80% draft. The resulting sheet is subjected to decarburizing annealing in a mixed atmosphere of H2+N2 and successively to final finish annealing. At this time, the average diameter of primary recrystallized grains in the steel sheet after decarburizing annealing is regulated to 6-11mum and also the coefficient of fluctuation of diameter is regulated to <=0.5. Further, by the time just before the initiation of secondary recrystallization at final finish annealing, the average diameter of the primary recrystallized grains is increased by 5-30% based on the average diameter in the steel sheet after decarburizing annealing. |
