Corrosion-fatigue resistance of ultrafine grain commercially pure titanium in simulated body fluid

Abstract

Commercially pure titanium (CP-Ti) due to excellent biocompatibility and high specific strength is known as a metallic biomaterial and is widely utilized in medical applications as implant material. Because of low strength of CP-Ti as compared to other bio-metals, it has been proved in literatures that applying equal channel angular pressing (ECAP) process can be useful to enhancement of mechanical and metallurgical properties of CP-Ti by improvement of initial microstructure to ultrafine grained (UFG). Implant in human body is attacked from cyclic fatigue loads and corrosion, simultaneous. Hence, aim of this study is examination of corrosion-fatigue resistance of CP-Ti before and after introducing ECAP in simulated body fluid (SBF) as a saline solution close to blood plasma. In this study, multi-pass ECAP is conducted on CP-Ti at room temperature and then the axial fatigue test is performed in SBF environment with temperature 37 °C. The comparison of stress-cycle curves demonstrated that corrosion-fatigue resistance of ECAPed CP-Ti is extremely higher than initial annealed one. Moreover, it was observed that by increasing the pass number of ECAP, corrosion-fatigue resistance improves significantly. Furthermore, these results are compared to fatigue behavior of CP-Ti in air environment. The results show that corrosion-fatigue resistance of unECAPed and ECAPed CP-Ti in SBF is slightly lower than fatigue ones in air. According to the results of this experimental research, it is concluded that UFG CP-Ti has an awesome corrosion-fatigue resistance in human body and it is very suitable for utilizing as material of implants.