Fatigue and Corrosion Fatigue Properties of Ti-6Al-4V Implant Grade Titanium Alloy in Ringer Solution

Nowadays, modification of metallic biomaterials which are used as implants for bone and hard tissues replacement is considered as an important subject. In the current study, corrosion fatigue properties of the Ti-6Al-4V alloy were investigated via Rotating-Bending standard test method and then the results were compared with the fatigue properties of the specimens tested in the same conditions. Scanning electron microscopy (SEM) was used to investigate the chemical composition (EDS- Energy-dispersive X-ray spectroscopy), microstructural features and crack propagation characteristics. The results showed that the presence of corrosive environment not only results in the decrease in the fatigue life, but also eliminates the fatigue limit. Further studies revealed that aggregation of the corrosion products with more hardness values at the crack tip will cause an obvious deviation of crack propagation from its main direction. Therefore, a tortuous crack path through the bulk of the specimens was detected concurrent with penetration of solution into the crack. In addition, dimensions and morphology of fatigue crack surfaces were completely different from corrosion fatigue cracks.