| 摘要 |
PURPOSE:To stably produce an ultrahigh magnetic flux density grain-oriented silicon steel sheet extremely high in magnetic flux density by adding Bi to the stock of a grain-oriented silicon steel sheet using AlN as a main inhibitor and controlling the temp. at the time of steel sheet coiling after the completion of hot rolling to a specified one. CONSTITUTION:A silicon steel slab having a compsn. contg., by weight, 0.03 to 0.15% C, 2.5 to 4.0% Si, 0.02 to 0.30% Mn, 0.005 to 0.040% S, 0.010 to 0.065% acid soluble Al, 0.0030 to 0.0150% N and 0.0005 to 0.05% Bi or moreover contg. 0.05 to 0.50% Sn independently or contg. 0.01 to 0.10% Cu is subjected to hot rolling, and the hot rolled sheet is coiled round a coil at <=500 deg.C and is thereafter annealed. Successively, it is subjected to cold rolling for one time or >=two times including process annealing and is subjected to final cold rolling at 65 to 95% draft. This cold rolled sheet is subjected to decarburizing annealing at 700 to 900 deg.C in a humid hydrogen atmosphere or the like. After that, the surface is coated with a separation agent for annealing, and it is subjected to continuous annealing and is moreover subjected to secondary recrystallization annealing. |
