A Comprehensive Review on Machining of Titanium Alloys

Titanium (Ti) alloys are produced with the combination of titanium and alloying elements. Titanium and titanium alloys are lightweight materials with high toughness, corrosion resistance and tensile strength at high temperatures. Titanium and its alloys have been widely used in several industrial applications, such as marine, biomedicine, chemical, energy and other industries. However, machining of Ti alloys is extremely difficult due to the high cutting temperature, high tool wear, and built-up edge formation. Therefore, this research aimed to extensively review the impact of machining inputs on the machining force, chip formation, cutting temperature, tool wear, mechanical properties (residual stress, fatigue and hardness) and surface integrity (surface roughness, surface defect and microstructure) during turning and milling of Ti alloys. Moreover, laser-assisted machining, ultrasonically assisted machining and different cooling systems were reviewed and discussed. It was found that these techniques can significantly improve Ti alloys' machinability. They can improve the surface integrity, tool life and mechanical properties as well as reducing the machining force and cutting temperature. The findings of this research can help manufacturers and researchers who work on machining processes, specially machining of Ti alloys.