Using a Combination of ECAP and HE Processes to Produce Isotropic Ultrafine-Grained Titanium.

This paper proposes a complex plastic forming process for grade 2 titanium using a combination of severe plastic deformation techniques, equal-channel angular pressing (ECAP) and hydrostatic extrusion (HE). The aim of the combination of these methods is to reduce the strength of the phenomenon of microstructural anisotropy and the resulting anisotropy of mechanical properties characteristic of the HE process. Two routes of plastic deformation (HE and ECAP + HE) were compared using the same total strain rate of ε ~ 3.5. Results: The analysis of mechanical properties and microstructure studies using TEM and SEM/EBSD techniques showed that it is possible to obtain large microstructure refinement of titanium with almost identical mechanical properties via both studied techniques. In addition, this also leads to a significant improvement in the strength of UTS by ~ 1000 MPa, YS by ~ 945 MPa and ductility (E) by ~ 25%. These findings indicate that applying a sequential ECAP + HE strategy can effectively reduce anisotropy and improve the overall performance of grade 2 titanium.