Dr. Corinna Thomser, Dr. Jesper Thorborg
Cast steels are characterized by a large variety of mechanical properties and microstructures after the heat treatment process in dependence on their final application. Process variations like differences in austenitization time and temperature, cooling conditions and chemical compositions play the significant role for high quality cast products. Process simulation with MAGMASOFT® is able to predict phase contents as well as mechanical properties including theses process variations in heat treatment and supports therefore a robust industrial heat treatment process design. Industrial examples for microstructure optimization of cast steels for a chain link will be given within the paper.
Furthermore residual stresses in the cast part based on the temperature history are calculated over the entire casting and heat treatment process. In the high temperature range like in the austenitization process for steels the material behavior is dominated by creep effects. The application of a unified creep model allows the quantitative prediction of stress reduction from the casting process linked to inelastic deformation during heat treatment.
In fast water or oil quenching processes stresses are built up again because of high thermal gradients in the steel casting, in addition the volume increase due to the diffusion less martensitic phase transformation increases stresses tremendously. Quench cracks because of high levels of tensile stresses as well as large amounts of distortion are results of these phenomena. Thus a compromise between desired material properties, namely high strength martensitic microstructures and acceptable stress levels in order to minimize distortion and avoid crack risks has to be found in order to deliver desired properties of the steel casting. As industrial examples the results of the virtual experimentation for a chain link and a brake disc will be discussed.
Please read the complete publication in the linked PDF.