| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an advantageous method for producing a grain oriented silicon steel sheet where various problems in annealing on an industrial scale in a coiled state which have been the subjects of a Bi-added stock are advantageously solved, and the effect of improving its magnetic flux density can be stably exhibited. <P>SOLUTION: A silicon steel slab containing, by mass, 0.01 to 0.10% C, 2 to 7% Si, 0.01 to 1.0% Mn and 0.005 to 0.050% Bi is subjected to hot rolling, is, if required, subjected to hot rolled sheet annealing, is thereafter subjected to cold rolling for one time or for two more times including process annealing, is subjected to recrystallization annealing, and is subsequently subjected to secondary recrystallization annealing without being coated with a separation agent for annealing essentially consisting of MgO, thus, upon the production of a grain oriented silicon steel sheet which does not comprise a forsterite film, the average temperature rising rate in the temperature range of 600 to 1,000°C in the secondary recrystallization annealing stage is controlled to ≥20°C/h, and further, the average temperature rising rate in the temperature range of 1,000 to 1,100°C is controlled to 10 to <20°C/h. <P>COPYRIGHT: (C)2008,JPO&INPIT |
