Abstract：To investigate the influence of cementite lamellar continuity on the deformation behavior of pearlite, four atomistic models of pearlite with varying lamellar continuity are constructed based on the experimentally observed cementite lamellae in S38C axle steel. Uniaxial tensile deformation of these models is simulated using molecular dynamics to systematically analyze the influence of lamellar continuity on microstructural evolution and plastic deformation mechanisms. The simulation results indicate that differences in lamellar continuity do not alter the dislocation nucleation mechanism dominated by ferrite-cementite interfaces in pearlite. In continuously distributed cementite lamellae, dislocations primarily nucleate at interfacial misfit dislocations and propagate via slip transfer across phase boundaries. In contrast, for discontinuously distributed lamellae, dislocation nucleation preferentially occurs near high-energy atomic planes. Moreover, as the spacing between discontinuous regions increases, the evolution of dislocation density undergoes significant changes, manifested by a marked reduction in interfacial slip transfer accompanied by local cementite decomposition. Quantitative analysis of the mean flow stress reveals a nonlinear relationship between cementite lamellar continuity and the hardening effect in pearlite, with a moderate reduction in lamellar continuity leading to a significant improvement in hardening response. This work elucidates the fundamental mechanisms through which the characteristics of cementite lamellae govern the plastic deformation and hardening of pearlite at the atomic level, thereby establishing a framework for the design and optimization of such materials.
2026, Vol. 47 
