Thermomechanical fatigue behaviour of nickel base superalloy IN738LC Part 2 - Lifetime prediction

摘要

An experimental programme was carried out to study the thermomechanical fatigue life of the nickel base superalloy IN738LC used in gas turbines. First, out of phase and in phase thermomechanical fatigue experiments were performed on uncoated and air plasma spray coated materials. In the temperature range investigated, it was observed that deposition of a NiCrAlY coating did not affect the thermomechanical fatigue resistance. A physically based life prediction model that takes into account the contribution of different damage mechanisms was then applied. This model successfully reflected the temperature and strain rate dependences of isothermal cycling fatigue lifetimes, and the strain - temperature history effect on thermomechanical fatigue lifetimes.