A Simulative Approach for the Prediction of Mesoscale Residual Stress Fields in Solution‐Strengthened Ferritic Ductile Iron

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.