Deformation behaviour of a ferritic hot-work tool steel with respect to the microstructure

A ferritic hot-work tool steel was investigated, which is in use as die for extrusion processes and exposed to cyclic load spectra with overlapping of both, thermal and mechanical loads. The occurring stresses and temperatures in the tool material were used to simulate the material behaviour of the tool steel in service by means of Abaqus StandardTM v.6.8–3 software in conjunction with Z-Mat package. A sensitivity analysis of the used elastic–viscoplastic Chaboche model was performed to characterize the most influencing parameters. To describe the microstructure evolution during thermo-mechanical loads via a physical based approach and to compare it with the phenomenological predictions, precipitation kinetics simulations as well as a dislocation density model for thermal creep using the rate theory, were applied to characterize the hardening and softening behaviour.