Fe-3%Si-Cu alloys with different Cu content were aging treated at 500 ∼ 800 °C. In order to study the dynamic behavior of the aging precipitations, the microstructure and the aging precipitation behavior of copper-rich phase in these alloys under different aging heat treatment were tested by OM, TEM technology and Vickers hardness. The results show that the amount of the copper-rich precipitates in the two alloys are gradually increase with the aging time going after aging treated at 600 °C. Within the 10³ s aging time, the size of the copper-rich precipitates of the two samples is below 20 nm. When it reaches 10^5.5 s, the copper-rich precipitates have obvious cluster phenomenon and the size are not more than 100 nm. After being treated with different aging temperature, the hardness of Fe-3% Si-Cu alloys with different copper component increases first and then decreases with time going, with obvious aging hardening peaks. When the aging temperature is 500 °C and the aging time is 10^4.5 s, the hardness of the two alloys reaches the maximum and they are 264 HV and 238 HV, respectively. The precipitation kinetics curve of the copper-bearing Fe-3% Si-Cu alloy is in the shape of ‘C’, and there is a certain precipitation incubation period. When the aging temperature is 600 ∼ 650 °C, the precipitation incubation period is the shortest. The increase of the copper content in the alloy will shorten the incubation period of the precipitation kinetic curve, increase the precipitation tendency of copper and cause the curve shifted to the left obviously.

Baiyun Ebo ore in Inner Mongolia in China is an associated ore rich in RE, Nb, Ti and other elements, which still have trace residues after smelting. In order to promote the comprehensive utilization of superior mineral resources and give full play to the role of these alloying elements in steel, the microstructure, texture and precipitates evolution of non-oriented silicon steel containing Nb were studied in different annealing processes in this research. The results show that when the non-oriented silicon steel containing Nb is annealed at 850°C, with the extension of annealing time, the recrystallized grains preferably nucleate and grow in the deformation band and grain boundary on the surface of the annealing plate. When the holding time is 3 min, the recrystallization proportion is about 20%. When the holding time reaches 9 minutes, recrystallization occurs completely, and the final recrystallization texture is mainly {111} orientation. The precipitates of the steel is mainly Fe₁₆Nb₆Si₇ after annealing, the particle size can reach 100 nm. When annealed at 850°C, the volume fraction of Fe₁₆Nb₆Si₇ phase decreases with the increase of annealing time, from 0.03236% to 0.01036%. When annealed at 850 °C for 3 min, the strength of the second phase increases to 9.4 MPa, and when the annealing time reaches 9 min, the strength of the second phase increases to 3.88 MPa. Therefore, when annealed at 850 °C, the precipitation of Fe₁₆Nb₆Si₇ particles has little effect on the intensity increment. In the design of annealing process, the Nb-rich phase should be solid dissolved into the matrix as much as possible, on one hand, the adverse effects of particles on magnetic induction and iron loss are reduced, on the other hand, the strength of non-oriented silicon steel can be improved by solid solution strengthening.