Abstract: Effect of different annealing temperatures with holding time of 2 min on the recrystallization structure, texture, mechanical properties and magnetic properties of 3.52%Si-1.10%Al non-oriented silicon steel was studied. The results show that the initial recrystallization temperature of the experimental steel is about 630 ℃. When annealed below 630 ℃, the microstructure of the annealed sheet is very similar to that of the cold rolled sheet, without no significant difference. When annealed above 630 ℃, recrystallization begins to occur in the annealed sheet, and the recrystallization fraction increases significantly with the increase of annealing temperature. The size of recrystallized grains slowly increases with the increase of annealing temperature, but without significant growth within the entire experimental temperature range of 500-790 ℃, far from reaching the optimal grain size. The texture of cold rolled sheet is mainly composed of α-fibre texture and γ-fibre texture, while η deformation texture strength is weak. As the annealing temperature increases, the deformed α-fibre texture decreases significantly, and the {001}<110>and {112}<110>textures have completely disappeared at 790 ℃, while the γ-fibre texture {111}<110> decreases first and then increases with the increase of annealing temperature. The variation pattern of {111}<112> texture is generally the same as that of {111}<110> texture. The intensity of η texture {100}<001> and {110}<001> which are beneficial for magnetic properties increases significantly when annealed at temperature over 690 ℃. As the annealing temperature increases, the iron loss P_1.5/50 of the product shows a monotonic decreasing trend, while the magnetic polarization intensities J₅₀₀₀ and J₁₀₀₀₀ show a monotonic increasing trend. As the annealing temperature increases, the yield strength shows a decreasing trend, but the rate of decrease varies within different temperature ranges. In the two temperature ranges of 610-630 ℃ at the beginning of recrystallization and 670-690 ℃ where the recrystallization ratio rapidly increases, there are two peaks in the decrease rate, while the decrease rate in other temperature ranges becomes more moderate. Annealing in the range of 630-670 ℃ can produce ultra-high strength non-oriented silicon steel products with R_p0.2≥650 MPa and excellent magnetic properties.

Key words: ultra-high strength, non-oriented silicon steel, annealing temperature, microstructure, properties