Micromechanical modeling of ductile cast iron incorporating damage. Part I: Ferritic ductile cast iron

The market for ductile cast iron as a substitute material increases every year. The material structural performance is strongly dependent on the microstructure. Micromechanics can help in understanding the role played by the microstructure constituents as well as the effects associated to the shape of the spheroids, their density, surface roughness, etc. The potential of application for micromechanics modeling can be further increased if features such damage mechanics and residual stresses are incorporated. In this paper, a micromechanics modeling approach based on the unit cell development has been developed paying particular attention to the role and the behavior of the constituents. Residual stresses, resulting from the cooling down to room temperature, have been demonstrated to be critical for an accurate prediction of the non-linear behavior of the DCI in the early deformation range. As far as damage mechanics is concerned, it has been demonstrated that voids nucleating from debonded spheroids are not sufficient to explain catastrophic failure at the macroscale while the occurrence of additional ductile damage in the matrix material is the driving process for rupture in ferritic DCI.