Effect of Cu Additive on the Microstructure and Magnetic Properties of Fe-6.5wt%Si High Silicon Steel by Induction Melting Method

Fe-6.5wt%Si high silicon steel alloy was prepared using the vacuum induction melting method. Ordered phase formation in Fe-6.5wt%Si alloy was inhibited by adding trace Cu and induction cycle heating purification treatment. The microstructure and magnetic properties of high silicon steel were investigated. The results show that with the increase of Cu content, the alloy microstructure first changed from coarse grain to fine isoaxial crystal, followed by strip dendrite, with ordered cracking. The saturated polarization strength of the alloy decreased from 25.1 emu of the sample without adding Cu and heating once to 21.5 emu for seven cycles, the residual magnetic polarization increased from 0.0255 emu to 0.048 emu, the slope of the magnetization curve slowed down, and the coercive force increased from 2.4 Oe to 4.0 Oe. With the increase of cyclic heating times, the microstructure of the alloy without added Cu refined and transitioned from columnar to equiaxial crystals, from isoaxial dendrite to strip with the addition of 0.03 wt%Cu, and from strip to isoaxial structure with the addition of 0.05 wt%Cu. With the increase of cycle heating times, the saturation magnetization strength of the alloy without Cu and with 0.03 wt%Cu alloy increased, while the recalcitrant force reduced. Conversely, the saturation polarization strength decreased for the alloy with 0.05 wt% Cu, and the coercive force was also reduced.