Mechanical properties prediction of ductile iron with spherical graphite using multi-scale finite element model

In this paper, using the multi-scale finite element method, the effect of graphite particles on the mechanical behavior of ductile iron has been investigated under tensile loading. For this purpose, taking into account the spherical geometric shape of the graphite phase and considering a specific volume fraction, these spheres are randomly placed in the whole body and a two-component composite material is created. As a next step, a micromechanical model of these materials is developed by defining the mechanical properties of the matrix and graphites as well as their interfaces. The mechanical properties of the matrix are simulated using the Ramberg-Osgood elastic-plastic model. By simulation in ABAQUS software and using nonlinear dynamic analysis, the effects of volume percentages and adhesion of graphite particles with matrix on the direct tensile load-displacement behavior of ductile iron were investigated. The results of experimental tests were used to verify the results of the numerical model. The weight percentage of graphite particles has a significant effect on the tensile strength and elastic modulus of these cast irons. The results show that with the increase in the amount of graphite particles, the tensile strength of cast iron increases up to a certain value and then reverses. With 21% graphite particles, the maximum tensile strength of ductile iron is 601 MPa. Compared with a pure sample of cast iron, the tensile strength increases by approximately 13.4% for this weight percentage of graphite particles.