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<p>This study uses small-angle neutron scattering (SANS) to investigate vanadium carbide (VC) random precipitation (RP) kinetics in two nanosteels with varying vanadium and carbon contents during aging for up to 10&#xa0;hours at 600 and 650&#xa0;°C. Starting from a martensitic microstructure, the evolution of the VC precipitate size distributions is tracked over time. Atom probe tomography (APT) and scanning transmission electron microscopy (STEM) provide complementary characterization of precipitate shape, morphology, and composition. The precipitation process follows a sequence of burst nucleation, rapid growth, and coarsening, driven by enhanced diffusion along dislocations and interfaces. VC precipitates form primarily at martensitic interfaces, adopting predominantly oblate ellipsoidal particles. Analysis of the time-dependent precipitate size indicates that pipe diffusion along dislocations is the dominant diffusion mechanism during coarsening. Using the Ashby-Orowan model, we estimate the strength enhancement from VC precipitation. Maximum VC strengthening occurs at different aging times depending on steel composition. For steels with a high carbon and vanadium content, peak strengthening occurs after 120&#xa0;minutes of aging at 650&#xa0;°C. Reducing the carbon and vanadium content prolongs the time required to reach peak strengthening, extending it to 300&#xa0;minutes at 650&#xa0;°C. The nuclear-to-magnetic scattering ratio shows a time-dependent evolution indicating a temporal compositional change in the VC precipitates during aging.</p>

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Role of Dislocations and Interfaces on the Nanoscale Random Precipitation Kinetics in Vanadium-Alloyed Steels Studied by SANS

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月11日

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  • Zamran Zahoor Khan,
  • Amir Sabet Ghorabaei,
  • Sonia Guehairia,
  • Steven R. Parnell,
  • Dirk Honecker,
  • Peter Hedström,
  • Bart J. Kooi,
  • S. Erik Offerman,
  • Niels H. Van Dijk

摘要

This study uses small-angle neutron scattering (SANS) to investigate vanadium carbide (VC) random precipitation (RP) kinetics in two nanosteels with varying vanadium and carbon contents during aging for up to 10 hours at 600 and 650 °C. Starting from a martensitic microstructure, the evolution of the VC precipitate size distributions is tracked over time. Atom probe tomography (APT) and scanning transmission electron microscopy (STEM) provide complementary characterization of precipitate shape, morphology, and composition. The precipitation process follows a sequence of burst nucleation, rapid growth, and coarsening, driven by enhanced diffusion along dislocations and interfaces. VC precipitates form primarily at martensitic interfaces, adopting predominantly oblate ellipsoidal particles. Analysis of the time-dependent precipitate size indicates that pipe diffusion along dislocations is the dominant diffusion mechanism during coarsening. Using the Ashby-Orowan model, we estimate the strength enhancement from VC precipitation. Maximum VC strengthening occurs at different aging times depending on steel composition. For steels with a high carbon and vanadium content, peak strengthening occurs after 120 minutes of aging at 650 °C. Reducing the carbon and vanadium content prolongs the time required to reach peak strengthening, extending it to 300 minutes at 650 °C. The nuclear-to-magnetic scattering ratio shows a time-dependent evolution indicating a temporal compositional change in the VC precipitates during aging.