Effect of RD type columnar crystals on the texture evolution and magnetic properties of Fe-4.5 wt.% Si electrical steel

Columnar grains are a common feature in cast slabs of Fe-4.5 wt% Si electrical steels, with their morphological and crystallographic anisotropies significantly impacting the microstructure and texture evolution. This study investigates the rolling texture and microstructure of Fe-4.5 wt% Si electrical steels, specifically focusing on columnar grains initially aligned along rolling direction(RD), with particular attention given to the nucleation mechanisms and development of {210}<001> components. Experimental findings reveal that the inheritance of "structure and texture" from the initial strong <001> columnar grains, results in warm-rolled sheets exhibiting {210}<001> and {113}<361> textures, which are characterized by widely distributed shear bands throughout the thickness. The beneficial η-fiber(<001>∥RD) with a peak at {210}<001> dominates the primary recrystallization texture. The {210}<001> component observed in annealed sheets originate from both the nucleation of {113}<361> shear bands and the inheritance of the initial <001> texture. As the annealing temperature increases, the {210}<001> grain-oriented undergo secondary recrystallization through high-energy grain boundaries, resulting in a final product with a sharp {210}<001> texture, and consequently the magnetic property is significantly improved. The development of the {210}<001> recrystallization texture is governed by two mechanisms: "oriented nucleation" during low-temperature annealing and "selective growth" during high-temperature annealing.