Image-based numerical simulation of the local cyclic deformation behavior around cast pore in steel

The local cyclic stress/strain responses around an actual, irregular pore in cast Hadfield steel under fatigue loading are investigated numerically, and compared with those around a spherical and an ellipsoidal pore. The actual pore-containing model takes into account the real shape of the pore imaged via high-resolution synchrotron X-ray computed tomography and combines both isotropic hardening and Bauschinger effects by using the Chaboche's material model, which enables to realistically simulate the cyclic deformation behaviors around actual pore. The results show that the stress and strain energy density concentration factors (K-sigma and K-E) around either an actual irregular pore or an idealized pore increase while the strain concentration factor (K-epsilon) decreases slightly with increasing the number of fatigue cycles. However, all the three parameters, K-sigma, K-epsilon and K-E, around an actual pore are always several times larger than those around an idealized pore, whatever the number of fatigue cycles. It is suggested that the fatigue properties of cast pore-containing materials cannot be realistically evaluated with any idealized pore models. The feasibility of the methodology presented highlights the potential of its application in the micromechanical understanding of fatigue damage phenomena in cast pore-containing materials.