Numerical Analysis of High-Temperature Tensile and Compressive Creep in Cast Irons: Local Effects of Microstructure

Cast irons are extensively used in high-temperature applications such as cylinder heads of heavy-duty diesel engines, where sustained exposure to high stresses and temperatures can initiate creep-related failure mechanisms, impacting their long-term durability and efficiency. Our previous experimental research demonstrated significant differences in creep mechanisms and behaviour of compacted graphite iron (CGI) under tensile and compressive loading. In situ analysis of the microstructural effects defining these differences during long-term high-temperature experiments is hardly possible. An alternative way to study these effects is to develop advanced micromechanical models using a finite-element method. The aim of this paper is to study the local responses at microscale (considering local distributions of stresses and strains) to macroscale long-term loading at high temperature employing direct introduction of microstructural features into numerical models. The models consider elasto-visco-plastic behaviour of the CGI material under tensile and compressive loading regimes. The novel results presented in this paper are applicable to cast irons as well as other heterogeneous materials such as metal matrix composites and the models presented can be used as a tool in the development of materials with microstructures customised for high-temperature applications.