Atomistic investigation into interfacial effects on the plastic response and deformation mechanisms of the pearlitic microstructure

Abstract

Atomistic modeling is used to investigate the mechanical response and deformation mechanisms at 5 K temperature within the commonly reported orientation relationships between ferrite and cementite within pearlite: Bagaryatskii, Pitsch-Petch, Isaichev, and their associated near orientations. For each orientation, compressive and tensile simulations were performed in the transverse and longitudinal directions for a range of ferrite to cementite volume ratios. Important mechanical properties such as peak stress, flow stress, and the activated slip systems in both lamella are reported. Significant variation in mechanical response is found between the various orientation relationships. In the transverse direction, the responses are well described by composite theory; longitudinal loading requires further consideration of the strain compatibility of the interface. Plasticity within the ferrite is found to initiate from the interface and is well described by Schmid factors; slip and failure in the cementite are affected by slip transfer mechanisms across the interface between the lamella. Simulation results are used to create a simple model for predicting deformation behavior in pearlite, allowing for greater understanding of the plasticity and failure mechanisms within the various reported orientations, and raising the possibility of the targeted creation of specific microstructures based on the intended mechanical loading.