Experimental and numerical study of frictional heating during rapid interactions of a Ti6Al4V tribopair

Frictional work dissipated into a pair of bodies in contact can lead to the generation of high temperatures at the interface. For extreme conditions, knowledge of such temperatures is indispensable for predicting material damage. Friction experiments have been performed for a Ti6Al4V tribopair on a ballistic bench at elevated sliding velocities and at high normal pressure (V0=43-65 m/s and p=110 MPa). A specific foil-workpiece thermocouple was developed to measure interface temperature; it was determined that such a sensor is particularly well-adapted to severe interaction conditions (very short response times, adhesive wear and high plastic strain). The experimental study shows that under such extreme conditions, sliding velocity effects on maximum temperatures reached are quite negligible. Using experimentally measured friction coefficients, thermal finite element simulations were performed to examine thermal fields along a sliding path. The temperature and thickness of the heat-affected zone are in good agreement with our postmortem SEM observations, indicating that wear phenomena do not modify the temperature field. A complex partition of heat flux is observed due to differences in the temperatures of the bodies in contact, being accentuated by temperature dependent thermal diffusivity of the Ti6Al4V alloy. Based on these partition coefficients, gradients of dissipated energy along the sliding path are determined.