Solution Strengthened Ferritic Ductile Iron (SSF-DI) offers improved mechanical properties compared to conventional cast iron, with a microstructure of spherical graphite nodules embedded in a ductile ferritic matrix. During cooling to ambient temperature, internal stresses develop due to a mismatch between the thermal contraction coefficients of the graphite and the matrix phase and phase transitions during cooling. These stresses, which are highest at the graphite-matrix interface, can lead to local plastic deformation of the matrix through dislocation generation and slip.

Graphite nodules act as stress concentrators, making them primary sites for crack initiation. Therefore, consideration of residual stress fields is crucial in the design of SSF-DI components. Given the complexity of experimentally measuring these internal stresses, reliable numerical models are essential for their prediction and the assessment of their effect on the mechanical properties of SSF-DI.

This study presents an ICME-based approach to determine the local mechanical properties of SSF-DI, thereby improving the efficiency of structural component design. The approach includes a finite element model to simulate thermal, mechanical and metallurgical interactions during cooling from casting temperature to ambient temperature. The model predicts the effect of varying cooling rates on the evaluation of internal stresses, incorporating local phase transitions described by a Johnson-Mehl-Avrami model. A subsequent micromechanical model evaluates the effects of the predicted residual stress fields on the strength of SSF-DI under monotonic loading.