Microstructure-related modelling of the relaxation behaviour of high-temperature sheet materials

The present study deals with the application of microstructure-based models to predict the tensile and relaxation behaviour of the highly loaded super alloy CoCr22Ni22W14 and NiCr22Co12Mo9. The results of tensile and/or relaxa tion tests and TEM investigations of the microstructure were used as input data into two models. which describe the high-temperature relaxation of a c omplex technical material. The effective stress model by Haasen and Alexander yields qualitatively cor rect predictions of the relaxation behaviour. if the evolution of the dislo cation density is described by a cubical time-dependent relation. The const itutive one-parameter model by Kocks and Mecking is only applicable, if the preceding tensile deformation starts in stage III, under the assumption of steady-stage deformation.