Characterization and Formation Mechanism of Oxide Inclusions in Low-Aluminum Non-oriented Electrical Steels

Abstract

It is recently found that oxide inclusions played a significant effect on the microstructure and magnetic properties in low-aluminum non-oriented electrical steels. In the current study, inclusions with different characteristics were generated through different production process. Inclusions were characterized using an automatic scanning electron microscope and thermodynamic analysis was conducted using FactSageTM. It is observed that the deformation behavior of SiO2–Al2O3–MnO inclusions was closely related to their composition. Inclusions forming during the solidification process showed a smaller size and a higher fraction of SiO2, which was hardly deformed after rolling and had little pinning effect on the grain growth. On the contrast, large inclusions had a lower fraction of SiO2 and were easily deformed after rolling process. From the view of improving the magnetic properties of non-oriented electrical steels, inclusions should be controlled to be undeformed and larger composite SiO2–Al2O3–MnO inclusions should be removed.