Effect of hot band annealing on microstructure, texture and magnetic properties of non-oriented electrical steel processed by twin-roll strip casting

Abstract

In the present study, an as-cast strip of Fe-3.2Si wt% non-oriented electrical steel was processed successfully by a new compact and low cost twin-roll strip casting process. After hot rolling, both the hot rolled bands with and without annealing were subjected to cold rolling and final annealing. The aim of the study is to elucidate the effect of hot band annealing on the microstructure, texture and magnetic properties of non-oriented electrical steel processed by twin-roll strip casting using a combination of optical microscopy (OM), X-ray diffraction (XRD), electron back-scattered diffraction (EBSD) and transmission electron microscopy (TEM). The study indicated that the AlN and MnS particles precipitated during hot band annealing process affected crystal rotation of the cold rolled sheet. {1 0 0}〈0 1 1〉 texture with a higher intensity and {1 1 0}〈1 1 0〉 texture with a lower intensity was observed after cold rolling compared to the cold rolled sheet without hot band annealing. The recrystallization and growth behavior of grains was impeded because of the precipitation during final annealing, and a strong λ-fiber texture with a smaller average grain size was obtained in the annealed sheet without hot band annealing process. However, the recrystallization texture in the final annealed specimen subjected to the hot band annealing process was characterized by pronounced {4 1 1}〈1 4 8〉 texture and the average grain size was significantly larger than without hot band annealing. The results suggested that hot band annealing is a suitable route to remarkably improve the magnetic properties of non-oriented electrical steel.