Surface mechanical attrition treatment was an innovative technique which could produce layers of several tens of micrometers thickness on surfaces of metallic materials. Here, the grade structures of commercially pure Ti, processed by surface mechanical attrition treatment, was studied intensively, and the microstructure observations indicated that the dislocation evolution could be separated into 3 steps: formation of dislocation tangles, formation of dislocation bands and dynamic recrystallization of dislocation bands up to the formation of nanocrystalline Ti.

Dislocation Evolution in Titanium during Surface Severe Plastic Deformation. M.Wen, G.Liu, J.Gu, W.Guan, J.Lu: Applied Surface Science, 2009, 255[12], 6097-102