The effect of Nb content on precipitates, microstructure and texture of grain oriented silicon steel

Niobium has the potential as an inhibitor forming element in grain oriented silicon steel. The grain oriented silicon steels with different Nb contents (0.028 wt% and 0.052 wt%) were prepared, and the effect of Nb content on the evolution of precipitates, microstructure and texture were investigated by the various analysis methods and thermodynamic calculations. The results show that the smaller size and larger number density of precipitates were obtained in the sample with low Nb steel after hot rolling. In the process of normalization, Nb(C, N) are more inclined to precipitate along the dislocations caused by hot rolling, contributing to finer and more dispersed precipitates in normalized bands. The finer and more dispersed precipitates in 0.028% Nb containing silicon steel perform a stronger pinning force during whole heat treatment processes, resulting in the smaller grain size and higher intensity of Goss texture in the specimen containing 0.028%Nb. After normalization, the intensities of Goss texture in both steels decrease.