On the Effects of Hot Forging and Hot Rolling on the Microstructural Development and Mechanical Response of a Biocompatible Ti Alloy

Abstract

Zr, Nb, and Ta as alloying elements for Ti alloys are important for attaining superior corrosion resistance and biocompatibility in the long term. However, note that the addition of excess Nb and Ta to Ti alloys leads to higher manufacturing cost. To develop low-cost manufacturing processes, the effects of hot-forging and continuous-hot-rolling conditions on the microstructure, mechanical properties, hot forgeability, and fatigue strength of Ti-15Zr-4Nb-4Ta alloy were investigated. The temperature dependences with a temperature difference (ΔT) from β-transus temperature (Tβ) for the volume fraction of the α- and β-phases were almost the same for both Ti-15Zr-4Nb-4Ta and Ti-6Al-4V alloys. In the α-β-forged Ti-15Zr-4Nb-4Ta alloy, a fine granular α-phase structure containing a fine granular β-phase at grain boundaries of an equiaxed α-phase was observed. The Ti-15Zr-4Nb-4Ta alloy billet forged at Tβ-(30 to 50) °C exhibited high strength and excellent ductility. The effects of forging ratio on mechanical strength and ductility were small at a forging ratio of more than 3. The maximum strength (σmax) markedly increased with decreasing testing temperature below Tβ. The reduction in area (R.A.) value slowly decreased with decreasing testing temperature below Tβ. The temperature dependences of σmax for the Ti-15Zr-4Nb-4Ta and Ti-6Al-4V alloys show the same tendency and might be caused by the temperature difference (ΔT) from Tβ. It was clarified that Ti-15Zr-4Nb-4Ta alloy could be manufactured using the same manufacturing process as for previously approved Ti-6Al-4V alloy, taking into account the difference (ΔT) between Tβ and heat treatment temperature. Also, the manufacturing equivalency of Ti-15Zr-4Nb-4Ta alloy to obtain marketing approval of implants was established. Thus, it was concluded that continuous hot rolling is useful for manufacturing α-β-type Ti alloy.

Microstructures and Mechanical Properties of Laser-Sintered Commercially Pure Ti and Ti-6Al-4V Alloy for Dental Applications

“…The effects of the laser sintering direction on σFS of CP Ti G 2 were considered to be small because the anisotropy factor of the fatigue strength was 0.87 ((fatigue strength in 90° direction)/(fatigue strength in 0° direction)). This value was similar to those obtained for the lasersintered Co-Cr-Mo alloy (0.83-1.0) [1] and the anisotropy of σ0.2%PS caused by forging of Ti-15Zr-4Nb-4Ta alloys (0.83-0.94) [40]. Thus, it was considered that the effect of the laser sintering direction is negligible for CP Ti G 2.…”

Strength–Durability Correlation of Osteosynthesis Devices Made by 3D Layer Manufacturing

“…Ti grade 4 (C.P. Ti G 4) can be made similar to that of Ti alloys by 20% cold working [1]. Ti alloys have higher corrosion resistance and biocompatibility than C.P.…”

“…Ti, owing to the addition of Mo, zirconium (Zr), niobium (Nb), tantalum (Ta), and so forth [2]. Ti-15Zr-4Nb-4Ta alloy has been developed in Japan as a highly biocompatible alloy for long-term biomedical applications [1,3] and it is standardized in JIS T 7401-4 [4].…”

Biocompatibility and Surface Properties of TiO2 Thin Films Deposited by DC Magnetron Sputtering

“…One solution is to use a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-tetrazolium bromide (MTT) assay or to develop systems based on transparent material such as indium-tin oxide (ITO) and titanium dioxide (TiO 2 ) [10,11,12,13]. For instance, Titanium alloys are commonly employed to manufacture hard tissue replacement, including dental implants, bone plates and artificial hip joints [14,15,16,17,18]. These materials have positive characteristics such as good mechanical strength, lightweight, biocompatibility, and corrosion resistance, which generally depend of their surface properties [14,19].…”