Effect of primary recrystallization microstructure on abnormal growth of Goss grains in a twin-roll cast grain-oriented electrical steel

Various primary recrystallization microstructures and textures were produced in a twin-roll cast grain-oriented electrical steel by employing different routes. The relationship between the primary recrystallization microstructure and texture and the abnormal growth of secondary Goss grains was investigated. The results show that the cold rolling reductions have a significant influence on secondary recrystallization by changing the primary recrystallization microstructure. Sheet processed by single-stage cold rolling with 88.3% reduction displayed the poorest secondary recrystallization microstructure as it contained many small equiaxed grains. By contrast, the employment of two-stage cold rolling markedly improved the secondary recrystallization microstructure. In the case of two moderate reductions of 65.2% and 66.3%, dense deformation substructures formed during both the first and second cold rolling, leading to a homogeneous primary recrystallization microstructure together with a strong gamma-fiber texture. In this way, a suitable secondary recrystallization microstructure consisting of large Goss grains was produced. In the case of the inappropriate reductions, many large lambda- and alpha-grains in the primary recrystallization matrix blocked the growth of secondary Goss grains along the transverse direction, resulting in a poor secondary recrystallization microstructure.