MICROSTRUCTURE AND MODELING OF THE DEFORMATION-BEHAVIOR OF SUPERALLOYS AT HIGH-TEMPERATURES

This paper presents the application of an effective stress model for m odelling the creep and tensile behaviour of superalloys in a large ran ge of temperature and strain rates. It is the aim of the microstructur e investigations to estimate parameters like dislocation density and p article spacing for a microstructure related modelling using physical equations. A common log (epsilon)over dot-log sigma plot of tensile an d creep data shows a systematic shift of about 10% towards higher stre sses in tension compared to creep. The dislocation densities measured by TEM, agree quite well with those, determined by the evolution equat ion of the model, introducing a time dependent term. The simulation of creep and tensile curves shows satisfying results. With this model, i t is possible to describe quite well the type oi the primary creep cur ves as well as the starting point of the steady-stale region. (C) 1997 Elsevier Science B.V.