Effect of severe plastic deformation realized by hydrostatic extrusion and rotary swaging on the properties of CP Ti grade 2

Abstract

The study is concerned with the influence of severe plastic deformation induced in CP Ti grade 2 by cold hydrostatic extrusion combined with rotary swaging on the process parameters, surface quality, tolerances, material microstructure, grain refinement, mechanical properties, thermal stability and mechanical homogeneity. The nano-size refinement to <90nm achieved in CP Ti grade 2 by this method resulted in the increase of its strength to above 1000MPa, with moderate ductility of ∼13%, and good thermal stability up to 500°C. The rotary swaging which followed cold hydrostatic extrusion improved the surface quality and increased the grain refinement. The applicative potential of nano-titanium CP Ti grade 2 is discussed and illustrated using three examples, namely the medical implants intended for surgical osteosynthesis, high strength fixing components, and net-shape complex profiles for structural components. The major advantage of nano CP Ti grade 2 over the alternative materials lies in its high purity and the absence of toxic components whereas the high strength of titanium is preserved during its refinement to the nanosize. The properties of nano CP Ti grade 2 are compared with those of the Ti–6Al–4V Ti grade 5 alloy and CP Ti grade 4, commonly used at the present.