Coupling multiple first-principles dislocation descriptors to predict solute effects in pearlite steels

Microalloying is crucial for controlling the mechanical properties of steel, as it significantly influences the dislocation structure and motion behavior in ferrite. To gain deeper insight into this solid-solution effect and provide guidance for the compositional design of steels, fifteen strongly ferrite-segregating elements from among Al, Si, P, S, 3d, 4d, and 5d transition metals, as well as rare-earth elements, were screened out using the partitioning enthalpy criterion. Furthermore, three distinct first-principles dislocation descriptors, including the differences in unstable stacking fault energy ( Δ γ us ) and Peierls barrier ( Δ E m ) induced by solute atoms, and the corresponding solute-dislocation interaction energy ( E int j ) were calculated. Notably, a significant positive correlation is observed between Δ γ us and E int j , both of which are primarily governed by chemical factors, while Δ E m shows no significant correlation with either of them. By incorporating these two independent parameters ( E int j and Δ E m ), a first-principles numerical model for critical resolved shear stress (CRSS) was developed to quantitatively predict the influence of alloying elements on ferrite's mechanical properties. The dislocation descriptors and numerical model employed in this work are also applicable to the study of dislocation behavior in other body-centered cubic refractory metals and their alloys.