| 摘要 |
PURPOSE:To prepare a unidirectional silicon steel plate excellent in iron loss characteristics, by coating a steel plate containing a specific compositional amount of Si and a minute amount of S, Se and N with an annealing separating agent containing Nb-oxide before applying final annealing to the coated steel plate under a specific condition. CONSTITUTION:After a steel plate after final cold rolling containing 4.5wt% or less Si and a minute amount of at least one element among S, Se and N is subjected to decarburizing annealing, the treated steel plate is coated with an Nb-oxide-containing annealing separating agent and, succeedingly, final annealing is applied to the coated steel plate at a temp. ranging from 1,000-1,200 deg.C in a hydrogen atmosphere to completely remove precipitates such as nitride, sulfide or selenide after the completion of secondary recrystallization from steel as impurities. By this method, a unidirectional silicon steel plate excellent in iron loss characteristics is obtained. As the above mentioned annealing separating agent, it is pref. to use one containing Nb-oxide in an amount so as to bring Nb-adhesion amount per the single surface of the steel plate to be 0.02- 0.5g/m<2>. |
