Study on machinability characteristics of novel additive manufactured titanium alloy (Ti-6Al-4V) fabricated by direct metal laser sintering

Abstract

The pressing demand of Ti-6Al-4V (grade 5) in aerospace, medical, marine, and chemical processing industries has gained momentum in recent years due to its excellent properties such as high strength to weight ratio and corrosion resistance, bio-compatibility and a common material for additive manufacturing. Additive manufactured Ti-6Al-4V have higher mechanical properties as compared to wrought alloys due to difference in microstructure that negatively influences the machinability characteristics and also lacks ductility. The main limitation of fabricated additive manufactured (AMed) component is the poor surface quality, staircase effect and adhering of non-melted powder particles to the fabricated components. Again, fatigue life of components increases with decrease of surface roughness. Therefore the need of machining of AMed titanium alloys in recent years are gaining importance to eliminate these problems so that desired surface quality and tolerances can be achieved. Therefore the objective of the study is to develop additive manufactured Ti-6Al-4V through direct metal laser sintering process and investigate its machinability characteristics under flood cooling environment with respect to responses as tool wear, surface roughness, cutting temperature, and chip morphology. As most of the heat generated at the interfaces has been carried away through flood cooling, the rate of growth of tool wear, cutting temperature, surface roughness, and degree of serration decreases and thus makes the performance of AMed Ti alloys are comparable with wrought Ti alloys. The dominant tool wear mechanism during machining AMed Ti alloy have been found to be abrasion, chipping, adhesion, BUE, chemical interaction between titanium and cutting tool materials, coating delamination. Optimal parameters for multi-responses are 0.1 mm depth of cut, 0.1 mm/rev feed rate, and 70 m/min cutting speed and improved. Mathematical models are said to be significant and fitted well. Because of the improved machinability, AMed Ti alloys find itself suitable in industrial applications.