Corrosion behavior of interstitial free (IF) steels with nanocrystalline surface layers

The interstitial free (IF) steels are widely used as car bodies in automotive industry. The production of IF sheets with nanocrystalline surface layers are of great industrial importance. Besides, the nanograins only in near surface layers might be accomplished by simpler processes with less amount of plastic-working energy than the nanocrystalline of bulk materials After producing the nanostructure layer by surface severe plastic deformation (SSPD), the nanostructure layer on the surface of the sheet steels was then characterized using atomic force microscopy (AFM), X-ray diffraction (XRD) patterns and micro-hardness measurements. The results show that equiaxed nanograins ranging from 30 to 200 nm were observed in the near surface regions of sheet steels. The depth of nanocystalline surface layer, depending on the process variables, lies between 35 and 40 μm. The harness of the nanostructured layer exhibited an increase up to three times higher than the starting one.

Keywords:

Nanocrystalline materials , Surface nanocrystalline layer , Nanocrystalline properties , Severe plastic deformation , IF Steel ,