Static mechanical properties and ductility of biomedical ultrafine-grained commercially pure titanium produced by ECAP process
(Department of Mechanical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, P. O. Box 9177948944, Mashhad, Iran)
Abstract: Equal channel angular pressing (ECAP) is one of the most effective processes to produce ultra-fine grain (UFG) and nanocrystalline (NC) materials. Because the commercially pure titanium exhibits excellent biocompatibility properties, it has a significant potential to be utilized as an implant material. The low static and dynamic strengths of the pure titanium are one of the weaknesses of this material. This defect can be removed by applying the ECAP process on the pure titanium. In this work, the commercially pure titanium Grade 2 (CP-Ti of Grade 2) was pressed at room temperature by the ECAP process via a channel angle of 135° for 3 passes. The microstructural analysis and mechanical tests such as tensile test, hardness test, three-point bending test and Charpy impact test were all carried out on the ECAPed CP-Ti through 3 passes. The microstructural evolution reveals that by applying the ECAP process, coarse grain (CG) structure develops to UFG/NC structure. Moreover, the results of the mechanical tests show that the process significantly increases the yield and ultimate tensile strengths, bending strength, hardness and fracture toughness of the commercially pure titanium so that it can be used as a replacement for metallic alloys used as biomaterials.
Key words: commercially pure titanium; equal channel angular pressing; tensile strength; bending strength; fracture toughness