Precipitation Behavior of 1.3%Si Non-oriented Silicon Steels During Strip Casting Process

In this work, the precipitation behaviors of 1.3%Si non-oriented silicon steel during the sub-rapid solidification process under different melt superheat were investigated using scanning electron microscope and transmission electron microscope, based on strip casting process. The results showed that the precipitates of as-cast strips were dominated by coarse AlN, and MnS particles were seldom observed. The mean size of AlN particles rapidly increased from 75 to 1060 nm, and the volume fraction increased from 0.028 to 0.069%, when the melt superheat increased from 20 to 70 degrees C. Besides, the precipitation quantity in the center layer of as-cast strip was obviously more than the surface layer. According to the different solubility ability in the liquid and ferrite matrix, Al or N elements tend to segregate during the sub-rapid solidification process, which is attributed to the nucleation and coarsening of AlN. On the condition of low melt superheat, the solidified layers suffered from hot deformation from the solidification end point to the nip point, which provided additional nucleation sites for precipitates and can be attributed to fine particles size. In addition, different heat conductivity and hot deformation degree in various thickness layer resulted in inhomogeneous distribution of particles through the thickness of as-cast strips.