Fatigue, fretting fatigue and corrosion characteristics of biocompatible beta type titanium alloy conducted with various thermo-mechanical treatments

Plain and fretting fatigue properties of β type titanium alloy, Ti-29Nb-13Ta-4.6Zr, underwent various thermo-mechanical treatments were investigated in order to judge its potential for biomedical applications. Ti-29Nb-13Ta-4.6Zr aged directly at 723 K for 259.2 ks after cold rolling shows the greatest fatigue strength in both low cycle fatigue life and high cycle fatigue life regions, and the fatigue limit, which is around 770 MPa, is nearly equal to that of hot-rolled Ti-6Al-4V ELI conducted with aging, which is one of representative α + β type titanium alloys for biomedical applications. Fretting fatigue strength tends in proportion to Young's modulus. Fretting fatigue limits of the forged bar of Ti-29Nb-13Ta-4.6Zr conducted with solution treatment, and aging at 723 K after solution treatment are around two thirds and a half of plain fatigue limits, respectively, and those are around 180 MPa and 285 MPa, respectively. Passive current densities of the plate of Ti-29Nb-13Ta-4.6Zr conducted with a multi-step-thermo-mechanical treatment, where the cold rolling and solution treatment are repeated 4 times, in 0.5%HCI and Ringer's solutions are much smaller than that of Ti-29Nb-13Ta-4.6Zr conducted with general thermo-mechanical treatment, and the values are a little smaller than those of forged Ti-15Mo-5Zr-3Al conducted with annealing and hot rolled Ti-6Al-4V ELI conducted with aging.