Precipitation morphology of niobium and its influence on the microstructure and mechanical properties of Fe–Mn–Al–C lightweight steel

The effects of Nb alloying on the organization of Fe–28Mn–10Al–C low-density steels and the form of Nb present in the steels were investigated. Thermodynamics simulation with Thermo-Calc, transmission electron microscopy (TEM), electron backscattering diffraction (EBSD) X-ray diffraction (XRD), meta...

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Main Authors: Litu Huo, Xiaoyuan Bo, Tao Ma, Weimin Gao, Yungang Li
Format: Article
Language:English
Published: Elsevier 2025-09-01
Series:Journal of Materials Research and Technology
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Online Access:http://www.sciencedirect.com/science/article/pii/S2238785425019696
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author Litu Huo
Xiaoyuan Bo
Tao Ma
Weimin Gao
Yungang Li
author_facet Litu Huo
Xiaoyuan Bo
Tao Ma
Weimin Gao
Yungang Li
author_sort Litu Huo
collection DOAJ
description The effects of Nb alloying on the organization of Fe–28Mn–10Al–C low-density steels and the form of Nb present in the steels were investigated. Thermodynamics simulation with Thermo-Calc, transmission electron microscopy (TEM), electron backscattering diffraction (EBSD) X-ray diffraction (XRD), metallurgical microscopy, and scanning electron microscopy (SEM) were used to study the presence of Nb and its precipitation characteristics in Fe–28Mn–10Al–C−xNb steels after solid solution treatment at 950 °C. The solubility of Nb in low-density steel and the composition of Nb-containing analytes were also calculated and analyzed. The results revealed that Nb alloying significantly refines the austenite grain structure of Fe–28Mn–10Al–C steel, and based on the basis of microscopic characterization techniques, Nb exists in the form of NbC analytes with a face-centered cubic (FCC) structure in Fe–28Mn–10Al–C−0.5Nb steel and is distributed in a finely dispersed state within the austenite grains and at the grain boundaries. Compared with the test steel without Nb, the Fe–28Mn–10Al–C−0.5Nb low-density steel exhibits superior strength and ductility. Through experimental observations and solid solution theory calculations, the solubility of Nb in the austenite of the Fe–28Mn–10Al–C−0.5Nb steel is less than 0.01 % with the designed alloying composition, the molar fraction of the NbC phase in the Nb-containing precipitates is more than 99.9999 %, and the concentration of Nb in the solid solution and the extent of NbN or Nb(CN) precipitation are very low and negligible. The experimental conclusions obtained from the study and calculations provide a theoretical basis for designing the composition and applying Nb-containing high-manganese and high-aluminum Fe–Mn–Al–C low-density steels.
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spelling doaj-art-43f8e62ea2bf400880cb2b08f3b537ca2025-08-20T03:02:59ZengElsevierJournal of Materials Research and Technology2238-78542025-09-01381868187810.1016/j.jmrt.2025.08.016Precipitation morphology of niobium and its influence on the microstructure and mechanical properties of Fe–Mn–Al–C lightweight steelLitu Huo0Xiaoyuan Bo1Tao Ma2Weimin Gao3Yungang Li4College of Metallurgy and Energy, North China University of Science and Technology, Tangshan, 063210, ChinaCollege of Iron and Steel Carbon Neutrality, North China University of Science and Technology, Tangshan, 063210, ChinaCollege of Metallurgy and Energy, North China University of Science and Technology, Tangshan, 063210, China; College of Iron and Steel Carbon Neutrality, North China University of Science and Technology, Tangshan, 063210, China; Corresponding author. College of Metallurgy and Energy, North China University of Science and Technology, Tangshan, 063210, China.College of Metallurgy and Energy, North China University of Science and Technology, Tangshan, 063210, ChinaCollege of Metallurgy and Energy, North China University of Science and Technology, Tangshan, 063210, ChinaThe effects of Nb alloying on the organization of Fe–28Mn–10Al–C low-density steels and the form of Nb present in the steels were investigated. Thermodynamics simulation with Thermo-Calc, transmission electron microscopy (TEM), electron backscattering diffraction (EBSD) X-ray diffraction (XRD), metallurgical microscopy, and scanning electron microscopy (SEM) were used to study the presence of Nb and its precipitation characteristics in Fe–28Mn–10Al–C−xNb steels after solid solution treatment at 950 °C. The solubility of Nb in low-density steel and the composition of Nb-containing analytes were also calculated and analyzed. The results revealed that Nb alloying significantly refines the austenite grain structure of Fe–28Mn–10Al–C steel, and based on the basis of microscopic characterization techniques, Nb exists in the form of NbC analytes with a face-centered cubic (FCC) structure in Fe–28Mn–10Al–C−0.5Nb steel and is distributed in a finely dispersed state within the austenite grains and at the grain boundaries. Compared with the test steel without Nb, the Fe–28Mn–10Al–C−0.5Nb low-density steel exhibits superior strength and ductility. Through experimental observations and solid solution theory calculations, the solubility of Nb in the austenite of the Fe–28Mn–10Al–C−0.5Nb steel is less than 0.01 % with the designed alloying composition, the molar fraction of the NbC phase in the Nb-containing precipitates is more than 99.9999 %, and the concentration of Nb in the solid solution and the extent of NbN or Nb(CN) precipitation are very low and negligible. The experimental conclusions obtained from the study and calculations provide a theoretical basis for designing the composition and applying Nb-containing high-manganese and high-aluminum Fe–Mn–Al–C low-density steels.http://www.sciencedirect.com/science/article/pii/S2238785425019696Fe–Mn–Al–CNbMicrostructurePrecipitationSolid solubility
spellingShingle Litu Huo
Xiaoyuan Bo
Tao Ma
Weimin Gao
Yungang Li
Precipitation morphology of niobium and its influence on the microstructure and mechanical properties of Fe–Mn–Al–C lightweight steel
Journal of Materials Research and Technology
Fe–Mn–Al–C
Nb
Microstructure
Precipitation
Solid solubility
title Precipitation morphology of niobium and its influence on the microstructure and mechanical properties of Fe–Mn–Al–C lightweight steel
title_full Precipitation morphology of niobium and its influence on the microstructure and mechanical properties of Fe–Mn–Al–C lightweight steel
title_fullStr Precipitation morphology of niobium and its influence on the microstructure and mechanical properties of Fe–Mn–Al–C lightweight steel
title_full_unstemmed Precipitation morphology of niobium and its influence on the microstructure and mechanical properties of Fe–Mn–Al–C lightweight steel
title_short Precipitation morphology of niobium and its influence on the microstructure and mechanical properties of Fe–Mn–Al–C lightweight steel
title_sort precipitation morphology of niobium and its influence on the microstructure and mechanical properties of fe mn al c lightweight steel
topic Fe–Mn–Al–C
Nb
Microstructure
Precipitation
Solid solubility
url http://www.sciencedirect.com/science/article/pii/S2238785425019696
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