Modelling the Microstructure Evolution of a Ferritic Hot-Work Tool Steel during Short-Term Creep

摘要

Hot work tool steels have to sustain high thermal and mechanical loads. To establish an authentic lifetime prediction of hot work tool steels during service, an accurate investigation and characterization of microstructure evolution is obligate since the material properties depend on the microstructural configuration. Therefore the microstructure of a ferritic hot work tool steel was investigated at different heat-treatment stages. Short-term creep specimen were investigated after rupture and their microstructural state was characterized and compared with precipitation kinetics simulations. The investigated tool material, which has a bcc lattice structure, forms a distinct dislocation cell and subgrain structure, respectively, which is described by a dislocation density model for thermal creep using the rate theory, in which the precipitation state influences the subgrain boundary migration.