  Although the pearlitic steel is one of the most extensively studied
materials, there are still questions unanswered about the interface in the
lamellar structure. In particular, to deepen the understanding of the
mechanical behavior of pearlitic steel with fine lamellar structure, it is
essential to reveal the structure-property relationship of the
ferrite/cementite interface (FCI). In this study, we analyzed the in-plane
shear deformation of the FCI using atomistic simulation combined with extended
atomically informed Frank-Bilby (xAIFB) method and disregistry analyses. In the
atomistic simulation, we applied in-plane shear stress along twelve different
directions to the ferrite/cementite bilayer for Isaichev (IS), Near Bagaryatsky
(Near BA) and Near Pitsch-Petch (Near PP) orientation relationship (OR),
respectively. The simulation results reveal that IS and Near BA ORs show
dislocation-mediated plasticity except two directions, while Near PP OR shows
mode II (in-plane shear) fracture at the FCI along all directions. Based on the
xAIFB and disregistry analysis results, we conclude that the in-plane shear
behavior of the FCI is governed by the magnitude of Burgers vector and
core-width of misfit dislocations.
