SECONDARY RECRYSTALLIZATION OF THE NITRIDED FE-3-PERCENT-SI ALLOY

Nitrided primary specimens containing 0.07% Bi were coated with MgO an d annealed in 5%H<INF>2</INF>-N<INF>2</INF> (BOX annealing). The magne tic induction (B<INF>8</INF>) after Box annealing increased with incre asing primary recrystallized grain size and decreased with increasing initial nitrogen content. The same primary recrystallized specimens we re intermittently annealed in 100% N<INF>2</INF> without MgO coating ( Model annealing). B<INF>8</INF><SUP></SUP> was measured at each anneal ing. The onset temperature of the secondary recrystallization (T<INF>c r</INF>) was detected by a steep raise of B<INF>8</INF> The maximum B< INF>8</INF> decreased with increasing T<INF>cr</INF> from 1075 to 1100 degrees C. The initial grain size and nitrogen content for the maximu m B<INF>8</INF> was different in both annealing methods. This differen ce was explained on the assumption that T<INF>cr</INF> mainly determin es B<INF>8</INF> in both annealing methods. The direct effect of Bi on the selective growth of sharp Goss orientation was small. Bi worked a s an inhibitor for grain growth in the primary recrystallization annea ling stage.