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<p>Advanced low-density (LD) steels of the Fe–Mn–Al–C system are promising for transportation applications due to their combination of high strength, ductility, and reduced density. In these steels, austenite remains the stable matrix; however, aging promotes phase transformations involving ferrite and κ-carbide. Microalloying elements such as V, Nb, or Ti influence these transformations by modifying precipitation kinetics and altering microstructural stability. In this study, the precipitation kinetics and phase evolution in a duplex Fe−12Mn–8Al–1C LD steel microalloyed with 0.2 wt pct V were investigated during aging at 600&#xa0;°C using <i>in situ</i> high-energy synchrotron X-ray diffraction combined with dilatometry and stress–relaxation. Results reveal that V reduces the ferrite and κ-carbide fraction by retarding the eutectoid reaction (<i>γ</i> → <i>α</i> + <i>κ</i>). The total transformed fraction (<i>α</i> + <i>κ</i>) decreases from 21.8 to 9.9 pct, corresponding to ~ 55 pct reduction in <i>α</i> + <i>κ</i> in the V-microalloyed steel. Microstructural characterization by LOM and SEM/EDS corroborated the lower <i>α</i> + <i>κ</i> fraction and the presence of VC particles located at austenite-ferrite interfaces. These findings elucidate the V role as microalloying in controlling the phase transformation and precipitation kinetics of <i>α</i> + <i>κ</i>, thereby stabilizing the austenitic matrix. Understanding V effect is therefore essential for designing optimized thermo-mechanical processing routes of duplex LD steels.</p><p></p>

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Effect of V Microalloying on the Precipitation Kinetics of a Duplex Fe–12Mn–8Al–1C Low-Density Steel Using In Situ High-Energy Synchrotron X-ray Diffraction

  • 期刊论文

  • 发表日期：

    2026年7月27日

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  • M. García-Domínguez,
  • I. Mejía,
  • N. Schell,
  • A. Stark,
  • J. M. Cabrera,
  • P. Barriobero-Vila

摘要

Advanced low-density (LD) steels of the Fe–Mn–Al–C system are promising for transportation applications due to their combination of high strength, ductility, and reduced density. In these steels, austenite remains the stable matrix; however, aging promotes phase transformations involving ferrite and κ-carbide. Microalloying elements such as V, Nb, or Ti influence these transformations by modifying precipitation kinetics and altering microstructural stability. In this study, the precipitation kinetics and phase evolution in a duplex Fe−12Mn–8Al–1C LD steel microalloyed with 0.2 wt pct V were investigated during aging at 600 °C using in situ high-energy synchrotron X-ray diffraction combined with dilatometry and stress–relaxation. Results reveal that V reduces the ferrite and κ-carbide fraction by retarding the eutectoid reaction (γ → α + κ). The total transformed fraction (α + κ) decreases from 21.8 to 9.9 pct, corresponding to ~ 55 pct reduction in α + κ in the V-microalloyed steel. Microstructural characterization by LOM and SEM/EDS corroborated the lower α + κ fraction and the presence of VC particles located at austenite-ferrite interfaces. These findings elucidate the V role as microalloying in controlling the phase transformation and precipitation kinetics of α + κ, thereby stabilizing the austenitic matrix. Understanding V effect is therefore essential for designing optimized thermo-mechanical processing routes of duplex LD steels.