Simulation‐Based Assessment of Second‐Order Residual Stress Fields on the Fatigue Performance of Silicon‐Strengthened Ferritic Ductile Irons

Ductile cast irons (DCIs) offer a unique combination of excellent mechanical properties, low cost, and high geometric flexibility, making them particularly suitable for large‐scale complex components. However, their heterogeneous microstructure, consisting of defects like microshrinkage pores and graphite nodules embedded in an iron matrix, exhibits strong variations throughout large structural components due to thermal gradients caused by changes in wall thickness of cast components. These microstructural variations lead to local and global differences in mechanical properties. Combined with intrinsic residual stresses present in the microstructure, this uncertainty in mechanical properties hinders efficient design and often results in overdimensioned components. To address this uncertainty, the present work introduces a simulation‐based framework that incorporates second‐order residual stresses into a subsequent shakedown analysis to evaluate their effect on the fatigue properties of SSF‐DI. The results show that second‐order residual stress fields significantly influence the predicted fatigue limit obtained from the shakedown analysis. Neglecting second‐order residual stresses leads to a slight overestimation of the yield strength under tensile loading but a pronounced overestimation of the fatigue limit. The study demonstrates that reliable simulation models within process–structure–property–performance simulations require careful consideration of the interactions between microstructure and residual stresses.