Experimental Investigations on Tribological Characteristics of Ti–6Al–4V Under Wet Conditions

Abstract

Titanium alloys are well known as difficult-to-machine materials due to their chemical affinity, low thermal conductivity, and low modulus of elasticity, causing premature wear of the tool, compromising the machining quality and increasing costs. Several solutions have been followed to improve the machinability of these alloys: development of new machining techniques, tool geometries, and protection of tools’ surface with coatings, to yield high productivity, good surface finish of the work piece, and extended tool life. In this paper, the contact phenomenon between tool and workwise used for machining operation in various machine tools is simulated to estimate the coefficient of friction (COF), friction force (FF), and wear rate of titanium alloy grade 5 (Ti–6Al–4V). In this work, the experiments are performed on a pin-on-disk apparatus to estimate tribological features of titanium alloy for different speeds and loading conditions. Pins were mounted in a pin holder and fed against a rotating disk at required speeds. The trials were performed on a titanium alloys for duration of 5, 7.5, and 10 min for load of 5 kg, 6 kg, 7 kg, 8 kg, 9 kg, and 10 kg with disk speeds of 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, and 900 rpm. The results show that the COF varies with duration of rubbing, normal load, and speeds. In general, COF decreases continuously for certain duration of rubbing and after that it remains constant for the rest of the experimental time. The wear of titanium alloys significantly increases initially as load varies from 7 to 10 kg due to more contents of Al and vanadium. Hence, it becomes imperative to analyze the wear characteristics of different types of titanium alloy.