Iron loss of tertiary recrystallized silicon steel

Tertiary recrystallization was observed after cold-rolling and annealing of conventional silicon steels. The magnetic induction B ₈ at 800 Å/m of tertiary recrystallized sheets about 75-μm thick is as high as 1.97 T. Magnetic domain width in these sheets is greater than 1 mm; hence domain-refining techniques such as mechanical scratching and chemical etching are employed in order to reduce the iron loss. The iron loss of the sheet mechanically scratched under the application of a tensile stress of 4 kg/mm² is W17/50=0.42 W/kg and W13/50=0.19 W/kg. However, this domain-refining effect disappears after annealing for 30 min at 800°C. On the other hand, domain refining by the chemical etching is effective against iron loss even if the sheets are annealed; the loss of a sheet 71-μm thick under the application of a tensile stress of 4 kg/mm² is W17/50=0.35 W/kg and W13/50=0.17 W/kg. The iron loss of a chemically etched sheet with a thickness of 31 μm is W17/50=0.21 W/kg and W13/50=0.13 W/kg