The peritectic solidification of high manganese Fe–C–Mn–Al steel (Fe-0.18 C-23.8 Mn-2 Al) under different cooling rates (10, 20 and 30 °C/min) was studied using a confocal laser scanning microscope. The complete transformation from liquid to γ-Fe, including L → δ-Fe, L + δ-Fe → γ-Fe and δ-Fe → γ-Fe, was directly observed. As the cooling rate increased, the initial precipitation temperature of δ-Fe decreased from 1436 °C to 1418 °C, while the starting temperature of peritectic transformation decreased from 1426 °C to 1396 °C. Correspondingly, the initial growth velocity of δ-Fe declined from 14.825 µm/s at 10 °C/min to 5.836 µm/s at 30 °C/min. For γ-Fe, the initial growth velocities were 1218.63 µm/s and 1029.85 µm/s at 10 °C/min and 20 °C/min, respectively, with average velocities decreasing to 324.15 µm/s and 231.29 µm/s. The average secondary dendrite arm spacing (SDAS) reduced from 99.09 µm to 61.28 µm with increasing cooling rate, exhibiting a clear inverse correlation summarized as <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11663_2025_3675_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="163" /> </InlineMediaObject> <EquationSource Format="TEX">${\lambda }_{2}=271.38\times {{C}_{R}}^{-0.435}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>λ</mi> <mn>2</mn> </msub> <mo>=</mo> <mn>271.38</mn> <mo>×</mo> <msup> <mrow> <msub> <mi>C</mi> <mi>R</mi> </msub> </mrow> <mrow> <mo>-</mo> <mn>0.435</mn> </mrow> </msup> </mrow> </math></EquationSource> </InlineEquation>. EBSD analysis revealed that the massive-like transformation at 30 °C/min accelerated the interface migration, increasing low-angle grain boundaries through dislocation rearrangement. Additionally, Al(O)N inclusions predominated in the microstructure, with their area fraction increasing markedly at higher cooling rates.

In-Situ Observation of Peritectic Solidification of Fe–C–Mn–Al Steel with High Manganese Under Different Cooling Rates

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发表日期：

2025年7月7日

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Jiaxi Chen,
Yi Ji,
Jingzhou Lu,
Wanlin Wang,
Lejun Zhou,
Jianghua Qi,
Peng Liu,
Kui Chen

摘要

The peritectic solidification of high manganese Fe–C–Mn–Al steel (Fe-0.18 C-23.8 Mn-2 Al) under different cooling rates (10, 20 and 30 °C/min) was studied using a confocal laser scanning microscope. The complete transformation from liquid to γ-Fe, including L → δ-Fe, L + δ-Fe → γ-Fe and δ-Fe → γ-Fe, was directly observed. As the cooling rate increased, the initial precipitation temperature of δ-Fe decreased from 1436 °C to 1418 °C, while the starting temperature of peritectic transformation decreased from 1426 °C to 1396 °C. Correspondingly, the initial growth velocity of δ-Fe declined from 14.825 µm/s at 10 °C/min to 5.836 µm/s at 30 °C/min. For γ-Fe, the initial growth velocities were 1218.63 µm/s and 1029.85 µm/s at 10 °C/min and 20 °C/min, respectively, with average velocities decreasing to 324.15 µm/s and 231.29 µm/s. The average secondary dendrite arm spacing (SDAS) reduced from 99.09 µm to 61.28 µm with increasing cooling rate, exhibiting a clear inverse correlation summarized as ${\lambda }_{2}=271.38\times {{C}_{R}}^{-0.435}$ $λ_{2} = 271.38 \times {C_{R}}^{- 0.435}$ . EBSD analysis revealed that the massive-like transformation at 30 °C/min accelerated the interface migration, increasing low-angle grain boundaries through dislocation rearrangement. Additionally, Al(O)N inclusions predominated in the microstructure, with their area fraction increasing markedly at higher cooling rates.