Damage Evolution and Fatigue After Impact of the TiAl Alloy TNBV3B

Abstract

TiAl-alloys show a low ductility, which limits their application especially in components prone to impact damage like turbine blades or vanes. Therefore, the influence of impact damage on the mechanical behavior of a cast and a forged TiAl-alloy has been investigated. Ballistic tests were performed with impact energies up to several Joules. In order to approach the impact situation with real blades or vanes, a blade-like geometry was chosen for the specimen edges. The caused damage has been evaluated as a function of the impact speed, the particle weight and the impact location. Fatigue experiments at different temperatures were performed to determine the threshold for crack growth as a function of the damage size after impact. For these tests, specimens showing cracks with lengths up to some millimeters on the specimen back side as well as specimens with other damages like blow-outs were chosen.