Influence of Chemical Composition on Inclusion Control of Non-oriented Silicon Steel

The magnetic properties of non-oriented silicon steel mainly depend on the ferrite grain size, crystal texture and inclusions in the steel. In the industrial production process, no obvious texture is generally formed. Therefore, the grain size of ferrite and the inclusions in the steel become the main factors affecting the magnetic properties of non-oriented silicon steel. In particular, inclusions in steel, their presence not only inhibit grain growth, promote lattice distortion, but also hinder the movement of magnetic domains, thereby deteriorating the magnetic properties of non-oriented silicon steel. Therefore, in the production process, it is desirable to remove it as much as possible or render it harmless. Reducing the content of harmful elements such as C, S, O, and N, or using rare earth and calcium treatment methods can remove the inclusions in the steel. When the content of manganese is increased, the size distribution of inclusions is improved, and the inclusions of small MnS inclusions are coarsened. The addition of Sn and Sn elements to steel promotes the polymerization, floating, and removal of inclusions.

Researchers from Wuhan University of Science and Technology combined non-oriented silicon steel produced industrially with non-aqueous solution electrolysis + scanning electron microscopy (SEM) observations to explore the influence of chemical composition systems on inclusion control. The results show that with the increase of Si and Al content, the number of oxide inclusions is significantly reduced. The number of nitride inclusions first increases rapidly and then gradually decreases. At the same time, the average size of inclusions gradually increases. In the low aluminum state, the number of inclusions is greater; in the high aluminum state, the inclusions of the inclusions are significantly reduced, and CuxS inclusions disappear. The number of inclusions of high-silicon low-aluminum series steels, medium-silicon low-aluminum series steels, low-silicon aluminum-free series steels, and high-silicon high-aluminum series steels decreased in turn.