Surface nanocrystallization induced by fast multiple rotation rolling on Ti-6Al-4V and its effect on microstructure and properties

A nanostructured layer was fabricated by using fast multiple rotation rolling (FMRR) on the surface of Ti-6Al-4V alloy, with grain size 10-19 nm in the top surface layer by means of XRD and TEM analysis. A deformation layer with thickness about 80 μm is clearly observed in the cross section of FMRR sample. The microhardness of the FMRR sample has an obvious change along the depth from about 368 HV in the top surface layer to about 260 HV in the matrix. The corrosion resistance of the Ti-6Al-4V alloy was improved after FMRR. The high density of grain boundaries in the surface nanocrystalline layer was beneficial to the formation of passive film, which accounted for the improvement of the polarization behavior of the FMRR sample.