Thick-Gauge Ultra-High-Strength High-Silicon Non-Oriented Silicon Steel with Balanced Mechanical and Magnetic Properties Controlled by Partial Recrystallization Annealing

Abstract

To find the process equilibrium point between the mechanical properties and magnetic properties of 0.65-mm-thick ultra-high-strength non-oriented silicon steel, the microstructure and texture evolution mechanism of 3.20% Si non-oriented silicon steel was studied. The results show that, as the annealing temperature increases from 690°C to 730°C, the recrystallization ratio of the annealing sheet increased rapidly from 24 to 62% at the first stage from 690°C to 710°C, then increased to 73% slowly from 710°C to 730°C. However, the yield strength decreased rapidly from 4.1 MPa/°C to 5.6 MPa/°C. The Goss texture strengthened and the γ-fiber weakened quickly, accompanied by the move of the peak from {111} < 110 > to {111} < 112 > , while the λ-fiber texture inherited from the normalization annealing sheet strengthened slowly. Iron loss and magnetics were gradually improved. When the annealing temperature was 710°C and the recrystallization ratio was 62%, iron loss P_1.5/50 and P_1.0/400 were 7.56 W/kg and 54.49 W/kg, respectively, magnetic polarization J₅₀₀₀ and J₁₀₀₀₀ were 1.596 T and 1.713 T, respectively, and yield strength was 693 MPa, which reached the requirement of the magnetic properties and strength requirement of the generator set. When the annealing temperature was 730°C, the yield strength sharply decreased to 582 MPa, which cannot meet the requirement of the mechanical property.