During an extrusion process, tools are exposed to thermal and mechanical loading conditions, which cause creep-fatigue. Such cyclic thermal and mechanical loads and their interaction, respectively, is the main reason for local imperfections and finally component failure at critical regions. The lifetime of tools used for extrusion processes should be predicted and therefore the microstructure evolution during service should also be taken into account. Hence a main topic of this module is to describe the microstructure evolution, i.e. the precipitation kinetics as well as substructure and dislocation density evolution, to achieve a physical based approach characterizing the material behaviour under such special loading conditions. The lifetime of the tools can be subsequently optimised with respect to both the tools conditions like specific heat treatment, which has an influence onto the initial microstructural configuration, tools geometry, temperature control, and process conditions such as billet temperatures and final microstructure of the product and punch speed.