A two step SPD processing of ultrafine-grained titanium

Equal channel angular pressing (ECAP) and high pressure torsion (HPT) are t wo severe plastic deformation (SPD) processes that have been used to proces s ultrafine-grained (UFG) materials. In this investigation, we have attempt ed to combine these two processes to refine the grain size of coarse-graine d pure titanium. ECAP processing was first carried out at 500-450 degrees C to refine the grain size to about 300 nm. Further processing by HPT result ed in finer grain size and higher dislocation density. The second step, HPT processing, also increased the microhardness, ultimate strength, yielding strength and ductility of the UFG pure titanium. Published by Elsevier Scie nce Ltd.