The project aim is to develop predictive modelling for the lifespan of gas turbine components made from polycrystalline Ni-based casting alloys. These components can undergo stress creep as a result of high temperatures caused by, for example, centrifugal forces on the moving turbine blades, as well as high cyclic fatigue from, for instance, vibrations of the rotor blade. In particular, we will examine the interplay between creep-induced grain boundary damage, fatigue-crack formation at creep-induced defects, crack formation on slip bands and micro-crack growth, which is significantly influenced by grain boundary damage. Based on our experiments, we aim to develop predictive models of the components’ lifespan, taking into account these microstructural parameters.