Abstract: In the current study, automatic scanning electron microscope and field emission scanning electron microscope were employed to analyze types and morphologies of inclusions and precipitates in nonoriented electrical steels. A thermodynamic software FactSage was conducted to analyze the inclusion formation behavior. With the increase of aluminum content, oxide inclusions changed with the the sequence of SiO2-Al2O3-MnO→Al2O3→MgO·Al2O3. For Aldeoxidized nonoriented electrical steels, angular AlN was the dominative nitride. Besides, the relationship between the average size of AlN and Al content was {d}μm=3.75·[%Al]-0.57. The content of Mg increased with the increasing Al content. With the increase of magnesium content and the decrease of sulfur, sulfides changed with the sequence of (Mn,Cu)S→(Mn,Mg)S→MgS.

Key words: Inclusions, precipitates, nonoriented electrical steel