Siliconizing Behavior in Surface Nanostructure of Non-Oriented Silicon Steel

Nanostructured surface layer was fabricated on a 3% non-grain oriented silicon steel by means of surface mechanical attrition treatment(SMAT),and then a solid powder siliconizing treatment was carried out for the SMAT sample at 550-650 ℃ for 4 h.The microstructural evolution was examined by using transmission electron microscopy(TEM),scanning electron microscopy(SEM) and X-ray diffraction(XRD).Experimental results show that: average grain size of the top surface layer of 3% non-grain oriented silicon steel can be refined to about 10 nm after SMAT,and the thickness of the nanostructured surface layer is about 20 μm.After the siliconizing treatment at 550-650 ℃ for 4 h,a compound layer forms on the SMAT sample,its thickness increases from 27 to 150 μm with the increment of the siliconizing temperature.The compound layer consists of FeSi and Fe3Si phases,and the FeSi phase was found to increase with the increment of the siliconizing temperature.