Microstructural evolution mechanisms of nanolaminated pearlitic steels upon large-strain deformation

SS Yin and YG Zhang and Y Zhang and LC Zhou and J Zhou, INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES, 289, 110076 (2025).

DOI: 10.1016/j.ijmecsci.2025.110076

Pearlitic steels with nano-laminar structures exhibit complex microstructural changes during mechanical deformation. In this work, we investigated large-strain simple shearing behaviors of four nanolaminated samples with the Bagaryatskii orientation relationship but varying layer thickness using molecular dynamics simulations. The results indicate that the ferrite lamella deforms through dislocation glide, while the cementite lamella deforms via a combination of dislocation glide and shear transformation zones. The interface serves as sources and sinks for these plastic deformation carriers. These deformation mechanisms lead to evolutions and interplays of various microstructures, including thinning and rotation of both lamellae, changes in type, density and arrangement of dislocations in both lamellae, development of vacancies and nanovoids in ferrite, and amorphization and dissolution of cementite. These microstructural evolutions are found to agree with experimental observations. Furthermore, the Burgers vectors and slip systems in cementite are explicitly determined. Cementite amorphization can be triggered by dislocation glide, while the mechanism of cementite dissolution is attributed to the attraction of carbon atoms by vacancies migrating from the ferrite to the interface. These findings provide significant insights into the mechanisms of microstructural evolution and contribute to a deeper understanding of the deformation behavior of pearlitic steels.

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