Effect of annealing temperature on the properties of phosphorus micro-alloyed non-oriented electrical steels

Microstructure, texture, mechanical properties, and magnetic properties of low carbon and silicon non-oriented electrical steels annealed at 800 °C, 820 °C, and 860 °C were studied. Fine precipitates (Al, Si, Mn)xNy-P, a small quantity of (Al, Si, Mn)xNy, and the aforementioned composite precipitates containing MnS were detected in the samples annealed at 820 °C and 860 °C. Compared with the samples annealed at 820 °C, the number density of precipitates decreased by 20% and the average size increased by 25 nm in the samples annealed at 860 °C. The average grain size was 22 μm, 26 μm and 46 μm in the samples annealed at 800 °C, 820 °C, and 860 °C, respectively. The magnetic induction increased by 0.027 T after the annealing temperature of the samples increased from 800 °C to 820 °C. The iron loss reduced 0.94 W/kg when the annealing temperature increased from 800 °C to 860 °C. The tensile strength and yield strength of the samples decreased by 21 MPa and 40 MPa when the annealing temperature increased. The loss iron was 4.27 W/kg(P1.5/50) and magnetic induction was 1.764 T(B50) for the samples annealed at 860 °C. Magnetic properties of the experimental samples were superior to the same grade of commercially available steels.