Deciphering the atomic-scale interactions between screw dislocation and copper precipitate in austenitic stainless steel using molecular dynamics simulation

S Biswal and RK Barik and A Bakshi and S Neogy and R Tewari and A Dutta and D Chakrabarti, COMPUTATIONAL MATERIALS SCIENCE, 250, 113703 (2025).

DOI: 10.1016/j.commatsci.2025.113703

Molecular dynamics simulation was employed to investigate the interaction of screw dislocation with copper precipitate and the resulting precipitation strengthening in austenitic stainless steel. The maximum value of strength was achieved when the dislocation exited the precipitate, indicating attractive interaction between the dislocation and the precipitate. Additionally, numerous instances of dislocation recombination into constrictions were observed within the precipitate, whose probability increased with increasing precipitate size, leading to higher strengthening. Besides, higher precipitation strengthening was observed for screw dislocation interaction with Cu precipitate as compared to edge dislocation interaction, which could be attributed to the repeated formation of constrictions in the former in comparison to the latter. Furthermore, the prime contributor of precipitate strengthening was found to be the modulus strengthening, which was subsequently correlated with the well-known Russell-Brown strengthening model, with some modifications. The results were subsequently validated with discrete dislocation dynamics simulation and TEM analysis, providing a good corroboration with the experimental data. The present study provides valuable insights into the atomic scale mechanism of precipitation strengthening in austenitic stainless steel, which could also be applied to investigate similar phenomena in other alloy systems. To the best of our knowledge, such comprehensive simulation-based analysis of screw dislocation interaction with FCC precipitate in an FCC matrix, coupled with experimental validation, exemplifies a hitherto unexplored novel investigation.

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