High silicon alloyed ductile cast iron (Si-DCI) can show unpredictable brittle fracture which currently prevents a widespread application of this material. The brittleness is associated with local superstructure formation due to silicon segregation which influences the deformation mechanisms of the matrix phase. In order to understand the effect of silicon segregation on the mechanical properties of Si-DCI under monotonous loading, three alloys with different cooling conditions were examined and micromechanical simulations were carried out by using the phenomenological crystal plasticity model. Here, the segregation profiles were determined through multi phase field simulations. The influence of segregation on the mechanical properties was only evident from the model but not from the experimental results. The simulated results show that the toughness of Si-DCI decreases with stronger silicon segregation when ductile damage is considered.

Reactive Air Brazing (RAB) enables the joining of vacuum-sensitive oxide ceramics, such as Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ (BSCF), to metals in a one-step process. However, damage may form in ceramic or joint during RAB. In this work, experimental microstructure characterization, measurement, and prediction of local material properties using finite element analysis were combined to enlighten these damage mechanisms, which are currently not well understood. Micromechanical simulations were performed using representative volume elements. Cooling simulations indicate that small-sized CuO precipitations are most likely to cause crack initiation in BSCF during cooling. The ball-on-three-balls experiment with porous BSCF samples was analyzed numerically to determine the values of temperature-dependent BSCF fracture stresses. The inversely calibrated fracture stresses in the bulk BSCF phase are underestimated, and true values should be quite high, according to an extreme value analysis of pore diameters.

Ductile cast iron (DCI) is characterized by excellent mechanical properties, good castability, and low cost. This predestines it for use in large structural components. However, its highly heterogeneous microstructure and the associated thermal expansion mismatch between graphite and matrix, as well as the phase transformation that occurs during cooling to ambient temperature, result in a highly complex residual stress state in the DCI microstructure. These residual stresses are of non‐negligible magnitude and have a significant impact on the resulting macroscopic mechanical properties of DCI. Experimental measurement of the mesoscopic residual stress fields is complex and equipment is limited, so reliable models for numerical prediction are increasingly in focus. Herein, a representative volume element‐based simulation approach is presented that can be used to predict the mesoscopic residual stress and strain fields in the DCI microstructure. The applicability of a Johnson–Mehl–Avrami–Kolmogorov model, extended for continuous cooling rates, to predict transformation kinetics is demonstrated. The model is calibrated for a silicon solid solution‐strengthened DCI alloy and various cooling rates. The resulting stresses and strains are calculated and the effect of cooling rate variation on the mesoscopic residual stress and strain fields is discussed.

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.