Thermal Stability and Mechanical Behavior of Ultrafine-Grained Titanium with Different Impurity Content

Abstract

Ultrafine-grained (UFG) commercially pure (Ti Grade 2) and high-purity (Ti 99.99%) titanium can be a good alternative to less biocompatible Ti alloys in many biomedical applications. Their severe plastic deformation may lead to a substantial increase of strength, but their highly refined microstructure show a lower thermal stability which may limit their range of applications. The purpose of this study was to investigate the effect of interstitial elements on the thermal stability of UFG Ti Grade 2 and high-purity Ti 99.99% processed by a multi-pass cold rolling to the total thickness reduction of 90%. The severely cold rolled Ti sheets were annealed at temperature in the range of 100–600 °C for 1 h and, subsequently, they were evaluated in terms of microstructure stability, mechanical performance as well as heat effects measured by differential scanning calorimetry (DSC). It was found that the microstructure and mechanical properties were relatively stable up to 200 and 400 °C in the case of UFG Ti 99.99% and Ti Grade 2, respectively. DSC measurements confirmed the aforementioned results about lower temperature of recovery and recrystallization processes in the high-purity titanium. Surprisingly, the discontinuous yielding phenomenon occurred in both investigated materials after annealing above their thermal stability range, which was further discussed based on their microstructural characteristics. Additionally, the so-called hardening by annealing effect was observed within their thermal stability range (i.e., at 100–400 °C for UFG Ti Grade 2 and 100 °C for UFG Ti 99.99%).

Improving Pure Titanium’s Biological and Mechanical Characteristics through ECAP and Micro-Arc Oxidation Processes

“…Furthermore, the microstructure of the 2-pass sample revealed a more refined structure than the 0-pass sample. This observation is consistent with the research, which indicated that multi-pass rolling leads to a refined microstructure and improved mechanical properties of titanium [77].…”

Enhancing the tribological properties of pure Ti by pinless friction surface stirring

“…Commercially pure Ti is considered as a potent alternative to the commonly-used Ti-6Al-4 V alloy for biomedical applications owing to its low density, excellent corrosion resistance, inertness, and proper biocompatibility [1,2]. However, because of the low hardness and tensile strength, low fatigue strength, and poor tribological properties of CP-Ti, it is necessary to improve its mechanical and tribological properties through appropriate methods [2][3][4].…”

Mechanical Performance and Microstructural Characterization of Light Alloys

“…More recently, additive manufacturing and dissimilar metal welding have attracted much attention for its various advantages, such as high efficiency and easy repeatability. Nonetheless, due to the manufacturing characteristics [5][6][7], mechanical anisotropy and performance distribution may become inhomogeneous and further deep microstructural characterizations should be performed.…”