Recrystallization behaviour and texture of non-oriented electrical steels

Abstract

Five numbers of Si steels with different alloying elements, viz., 1.35% Si, 2.2% Si, 1.48% Si with 0.11% Sn, 1.44% Si with 0.05% Sb and, 1.52% Si with 0.11% P (all are in wt%), were made in laboratory. Hot bands of 2.2% Si and 1.52% Si with 0.11% P showed recovered grains of very coarse elongated ferrite while that of 1.35% Si steel showed fine ferrite grain of both elongated and fine equiaxed type similar to that of remaining two steels. Grain boundary misorientation and recrystallization study of hot bands before and after annealing indicated nearly complete recrystallization of 1.35% Si and partial recrystallization of Sn and Sb added steels containing low Si. In the case of 2.2% Si and 1.52% Si with 0.11% P steels, the recovered grains were observed mostly containing substructures. The retardation to recrystallization in these two steels has been attributed to the elemental effect of P and high Si. The no-recrystallization temperature (Tnr) of only these two steels were noticed at ≤ 1000 °C. The ϕ2 = 45° and ϕ2 = 90° ODF sections of hot bands indicated that all experimental steels except 1.35% Si steel show magnetically favourable texture components of θ fiber (<001>//ND) and η fiber (<001>//RD) components. The beneficial θ fiber components were also further noticed in cold rolled and final annealed 2.2% Si, 1.44% Si with 0.05% Sb and, 1.52% Si with 0.11% P steels. The presence of the magnetically favourable texture in these steels probably resulted in reduced core loss of these steels while the highest core loss was noticed in 1.35% Si steel. The mechanical properties of final processed steels were also found to be suitable for cold forming and stamping operation during their electrical applications.