Iron Loss Influenced by Magnetic Annealing in 0.1-mm-Thick Grain-Oriented High-Silicon Steels

The influence of magnetic annealing on iron loss has been investigated in 0.1-mm-thick grain-oriented high-silicon steels. To prepare such thin high-silicon steels, 0.3-mm-thick commercial electrical steels were mechanically ground to a specific thickness and then annealed at 1200°C under a high vacuum atmosphere. Due to much faster evaporation of Fe than Si, strip thickness decreased and silicon content increased. The 0.23-mm-thick 3% Si samples typically were thinned to a thickness of 0.10 mm, and silicon content increased to 6.5% after annealing for approximately 50 h. The high-silicon steels were further magnetically annealed at 770°C in a dc magnetic field, and an excellent iron loss of around 0.65 W/kg (at 1.5 T/60 Hz) was obtained. The iron loss behavior with both siliconizing and magnetic annealing processes is discussed in the light of microstructural evolution of B2 ordering phases and domain boundary drag effect of surface subsidiary domains.