The solidification behaviors of Fe–5Mn–0.15C– (0.018,1.93) Al medium Mn peritectic steels were investigated by the simulation of Diffusion Module (DICTRA), combining Differential Scanning Calorimetry (DSC) and High-Temperature Confocal Scanning Laser Microscopy (CSLM) under the heating and cooling rate of 20 °C/min in the critical temperature range of 1230 °C–1550 °C. In the DICTRA simulation, the real diffusion of all solute elements in all solid (δ and γ) and liquid phases quantitatively considering for the actual temperature gradients was proposed to predict the solidification behavior in this study. The DICTRA simulation was more accurate than the conventional equilibrium solidification calculations (EQS) assumption of infinitely fast diffusion in the liquid and the solid phases. Meanwhile, the experimental studies using DSC and CSLM not only certify the accuracy of characteristic phase transition temperatures and solidification mode predicted by DICTRA but also reveal further details of phase transformation. The results showed that, according to the DICTRA simulation, the solidification mode of 0.018 Al hyper-peritectic steel was the L+δ, L+δ+γ, and L+γ phase in turn. The peritectic reaction left 33.7 pct residual liquid phase, which transformed into the γ phase during subsequent cooling. However, when the Al content was 1.93 pct, it was a hypo-peritectic steel and solidified through the L+δ, L+δ+γ, and δ+γ phase. The peritectic reaction consumed the liquid phase, leaving 64.5 pct δ phase which was then transformed into γ phase by an allotropic transformation. During heating, DSC measurements of phase transformation temperatures agreed more closely with DICTRA predictions than CSLM observations. For the 0.018 Al steel, the average deviation was 5.8 °C for DSC versus DICTRA, compared to 14.5 °C for CSLM. However, some localized and subtle phase transformations during heating are difficult to observe by CSLM, which accounts for the relatively large deviations with the DICTRA predictions. Conversely, during 0.018 Al steel cooling, CSLM showed better agreement with DICTRA (8.9 °C average deviation) compared to DSC (26.0 °C). At relatively low temperatures, phase transformation temperatures may not be reliably detected by DSC owing to its diminished thermal signal. Compared with the EQS results, the DICTRA simulation are in relatively good agreement with the experimental CSLM and DSC results.

A Novel Approach for Interpreting the Solidification Behavior of Fe–Mn–Al–C Medium Mn Peritectic Steels by DICTRA Simulation Combining DSC and CSLM

期刊论文
发表日期：

2026年4月6日

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LIBIN JIN,
SHUGUO ZHENG,
MIAOYONG ZHU

摘要

The solidification behaviors of Fe–5Mn–0.15C– (0.018,1.93) Al medium Mn peritectic steels were investigated by the simulation of Diffusion Module (DICTRA), combining Differential Scanning Calorimetry (DSC) and High-Temperature Confocal Scanning Laser Microscopy (CSLM) under the heating and cooling rate of 20 °C/min in the critical temperature range of 1230 °C–1550 °C. In the DICTRA simulation, the real diffusion of all solute elements in all solid (δ and γ) and liquid phases quantitatively considering for the actual temperature gradients was proposed to predict the solidification behavior in this study. The DICTRA simulation was more accurate than the conventional equilibrium solidification calculations (EQS) assumption of infinitely fast diffusion in the liquid and the solid phases. Meanwhile, the experimental studies using DSC and CSLM not only certify the accuracy of characteristic phase transition temperatures and solidification mode predicted by DICTRA but also reveal further details of phase transformation. The results showed that, according to the DICTRA simulation, the solidification mode of 0.018 Al hyper-peritectic steel was the L+δ, L+δ+γ, and L+γ phase in turn. The peritectic reaction left 33.7 pct residual liquid phase, which transformed into the γ phase during subsequent cooling. However, when the Al content was 1.93 pct, it was a hypo-peritectic steel and solidified through the L+δ, L+δ+γ, and δ+γ phase. The peritectic reaction consumed the liquid phase, leaving 64.5 pct δ phase which was then transformed into γ phase by an allotropic transformation. During heating, DSC measurements of phase transformation temperatures agreed more closely with DICTRA predictions than CSLM observations. For the 0.018 Al steel, the average deviation was 5.8 °C for DSC versus DICTRA, compared to 14.5 °C for CSLM. However, some localized and subtle phase transformations during heating are difficult to observe by CSLM, which accounts for the relatively large deviations with the DICTRA predictions. Conversely, during 0.018 Al steel cooling, CSLM showed better agreement with DICTRA (8.9 °C average deviation) compared to DSC (26.0 °C). At relatively low temperatures, phase transformation temperatures may not be reliably detected by DSC owing to its diminished thermal signal. Compared with the EQS results, the DICTRA simulation are in relatively good agreement with the experimental CSLM and DSC results.