Abstract: Non⁃oriented silicon steel is the core soft magnetic material of generators, motors and other equipment. Metallurgical defects are one of the important factors affecting its magnetic properties and product quality. The characteristics of inclusions significantly affect the magnetic properties of non⁃oriented silicon steel. In this paper, the influence law and mechanism of the type, shape, size and quantity of inclusions on magnetic properties were systematically sorted out, and the effective control technology of inclusions was summarized. The type, shape, size and quantity of inclusions are closely related to magnetic properties. In terms of type, the stress field generated by oxide inclusions ( such as Al2O3 ) significantly pins the magnetic domain wall and aggravates the hysteresis loss. Sulfide inclusions ( such as MnS ) change the magnetic domain structure and affect the magnetic permeability anisotropy due to the difference in morphology and distribution. Nitride inclusions ( such as AlN ) pin grain boundaries and dislocations in a small dispersed form, hindering the movement of magnetic domain walls. In terms of morphology, angular inclusions cause stress concentration and have a greater hindrance to the magnetic domain wall than spherical inclusions. In terms of size, fine inclusions ( < 1 μm ) lead to an increase in coercivity, an increase in iron loss, and a decrease in magnetic induction intensity by inhibiting grain growth and strong pinning effect. In terms of the number of inclusions, the increase of the volume fraction of inclusions will enhance the interaction, and the decrease of the spacing will lead to the superposition of the stress field, so that the iron loss will increase significantly.In terms of mechanism, inclusions affect magnetic properties in multiple dimensions by changing the energy state of magnetic domain wall, regulating grain boundary migration and recrystallization texture. In view of the regulation of inclusions, calcium treatment and rare earth treatment technology are mainly used at present. Through spheroidization and aggregation of inclusions, they are transformed into composite inclusions, which can increase the size and reduce the number, and effectively improve the magnetic properties of non⁃oriented silicon steel.

Key words: non?oriented silicon steel, inclusions, magnetic properties, calcium treatment, rare earth treatment