Optimization of Tensile Strength and Ductility of Grade 2 Ti, Conditioned by Severe Plastic Deformation

Abstract

Among the materials employed for orthopedic implants, Ti-6Al-4V is definitely the best choice due to its excellent properties. However, a more intense use is hindered by high cost and the presence of harmful elements, viz. Al and V. A solution can be found in commercially pure Ti, provided its tensile and fatigue properties can be upgraded by some process of Severe Plastic Deformation. In the present work, Grade 2 Ti was submitted to up to four Equal Channel Angular Pressing passes, followed by cold rolling (30 70 and 90% reduction ratio) Hardness and tensile properties were determined, paying attention to the work hardening behavior. Results show that Severe Plastic Deformation gives a 442 MPa increase over the yield strength of annealed Grade 2 Ti (originally 337 MPa), while elongation reached 21%. Best results were obtained with four passes followed by 70% cold rolling reduction. Finally, the microstructural stability was assessed by hardness measurements.