Investigation of nanostructured surface layer on a low carbon steel induced by mechanical milling

In the present study, the microstructural properties of the nanostructured surface layer of a low carbon steel (CK15) fabricated by ball milling technique was characterized using X-ray diffractometry, optical and scanning electron microscopies (SEM and FESEM). The results indicate that a nanostructured layer with the thickness of more than 30 m was formed on the surface of the steel by applying surface milling treatment. The minimum of the average grain size in top of surface layer was found to be about 15 nm after milling for 12 hours. Moreover, it was found that by applying the mentioned method, the average grain size and the hardness in the top of surface layer gradually vary as a function of depth below the surface.