Characterisation of foreign object damage and fatigue strength in titanium based aerofoil alloys

Simulated foreign object damage has been inflicted at room temperature on two competing titanium based materials destined for compressor aerofoil applications in future gas turbine engine designs. Laboratory specimens, manufactured in the conventional titanium alloy Ti–6Al–4V and the γ titanium aluminide Ti–45Al–2Mn–2Nb, were subjected to impacts of various energy, representative of severe in-service damage. Damage sites were fully characterised prior to subsequent fatigue assessment at both room temperature and elevated temperatures typical of the envisaged maximum working temperatures for each alloy. In terms of absolute fatigue endurance levels the γ aluminide offers the weaker response at room temperature, however, this system offers clear advantages in terms of temperature capability.