Tailoring Mechanical Properties of Pearlitic Steels through Size Regulation of Multiscale Microstructures: Experiments and Simulations

Pearlitic steels possess excellent mechanical properties due to their multiscale microstructures, yet this configuration introduces complex size and interface effects, impeding the elucidation of their microscopic deformation mechanisms. In this study, a predictive framework that combines a high-resolution reconstruction algorithm with a strain gradient crystal plasticity model was developed to investigate the relationship between local deformation behaviors in nodules, colonies, and lamellae of various sizes and their mechanical properties. This approach effectively reconstructs the multiscale structures of pearlite and accurately tracks the dynamic mechanical responses. The integrated experimental and computational findings highlight the critical role of microstructure sizes in regulating strain delocalization and dislocation dynamics, which, through strain partitioning and interface density, are vital for optimizing mechanical properties. Notably, a decrease in lamellar spacing and nodule size significantly enhances both strength and toughness, while smaller nodules and colonies promote increased plasticity. Finally, a dual-parameter Hall-Petch equation incorporating lamellar spacing and nodule size is introduced, enabling precise quantification of the impact of all microstructures in pearlite on mechanical properties with robust predictive capabilities.