Effects of yttrium on the microstructure, texture, and magnetic properties of non-oriented 6.5 wt% Si steel sheets by a rolling process

Non-oriented 6.5 wt% Si steel thin sheets with three different yttrium (Y) contents (0, 0.012, and 0.03 wt%) were prepared by hot rolling, warm rolling, intermediate annealing, cold rolling and final annealing processes. The effects of the Y content on the microstructure, texture, and magnetic properties of cold-rolled 6.5 wt% Si steel sheets were studied by optical microscopy, scanning electron microscopy, energy-dispersive x-ray spectroscopy, and electron backscattered diffraction. The results showed that the sample with 0.012 wt% Y had the lowest volume fraction of inclusions, and Y played a role in purifying steel. The final average grain size of sheets decreased upon increasing the Y content. As the Y content increased, the {100} texture continuously weakened, and the overall intensity of the eta (100//RD) texture increased first and then decreased, while the intensity of the detrimental gamma (111//ND) texture decreased first and then increased. Adding an appropriate amount of Y optimized the recrystallization texture by promoting the occurrence of shear bands, which provided more nucleation sites for eta - fiber oriented grains. When the Y content was 0.012 wt%, the magnetic induction B (50) reached the maximum (1.64655 T) due to the enhanced eta texture and weakened gamma texture. The sample with 0.012 wt% Y showed the lowest core loss at high frequencies (>5 kHz) because of the favorable grain size. The addition of excess Y increased the number of inclusions and increased gamma -fiber oriented grain nucleation, which deteriorated the magnetic properties of non-oriented 6.5 wt%Si steel.

Automated summary

The addition of yttrium (Y) affects the microstructure, texture, and magnetic properties of cold-rolled 6.5 wt% Si steel sheets. Adding an appropriate amount of Y can optimize the recrystallization texture, increase magnetic induction strength, and reduce core loss. Excessive Y content deteriorates the magnetic properties by increasing inclusions and gamma-fiber oriented grain nucleation.