Influence of Annealing Temperature on Microstructure and Magnetic Properties of High-Silicon Electrical Steel

This paper investigated the effect of annealing temperature on the microstructure and magnetic properties of the high-Si electrical steel using optical microscopy and a vibrating sample magnetometer. The melted steel containing 3.385 wt.% Si and 0.006 wt.% C was hot-forged and skin-passed into the 1 mm thickness sheet, then annealed at 800, 900, and 1000 °C for 2 h in the argon atmosphere. The results showed that the obtained samples had only the ferrite phase and no precipitation in the microstructure which was preferred for the electrical steel. As the raising of annealing temperature from 800 to 1000 °C, the average grain size of the ferrite phase increased from 216 to 350 µm. Although, both the maximum permeability and initial permeability of the samples were improved from 96.7 to 125 emu/g and 4.9 to 9.4 emu/g, respectively, the magnetic saturation had a trend to decrease from 211 to 182 emu/g. These magnetic properties of the steel samples referred that the annealing temperature of 800 °C was reasonable in this study condition.