李民, 刘洪波, 车晓锐, 刘颖, 张杰, 张彩东, 田志强, 徐浩. Fe-8.5Mn-2.1Cr-0.95C中锰耐磨钢凝固过程溶质微观偏析模型及分析[J]. 工程科学学报. DOI: 10.13374/j.issn2095-9389.2023.07.12.003
引用本文: 李民, 刘洪波, 车晓锐, 刘颖, 张杰, 张彩东, 田志强, 徐浩. Fe-8.5Mn-2.1Cr-0.95C中锰耐磨钢凝固过程溶质微观偏析模型及分析[J]. 工程科学学报. DOI: 10.13374/j.issn2095-9389.2023.07.12.003
Solute micro segregation models and analysis during the solidification of Fe-8.5Mn-2.1Cr-0.95C medium manganese wear-resistant steel[J]. Chinese Journal of Engineering. DOI: 10.13374/j.issn2095-9389.2023.07.12.003
Citation: Solute micro segregation models and analysis during the solidification of Fe-8.5Mn-2.1Cr-0.95C medium manganese wear-resistant steel[J]. Chinese Journal of Engineering. DOI: 10.13374/j.issn2095-9389.2023.07.12.003

Fe-8.5Mn-2.1Cr-0.95C中锰耐磨钢凝固过程溶质微观偏析模型及分析

Solute micro segregation models and analysis during the solidification of Fe-8.5Mn-2.1Cr-0.95C medium manganese wear-resistant steel

  • 摘要: 通过定向凝固、电子探针(EPMA)、Factsage等多种实验与理论计算相结合的手段对中锰耐磨钢凝固过程溶质元素微观偏析行为进行了系统研究。研究表明在定向凝固试验中当拉速为50 μm/s时,中锰钢的二次枝晶间距平均值为59.77μm;中锰钢凝固过程组织转变为L→ L + γ → γ属于奥氏体凝固模式,无包晶反应的发生,也无铁素体相及其它相的出现;中锰钢定向凝固过程中Mn、Cr在枝晶间的含量明显高于枝晶内,表明Mn、Cr元素发生了明显的正偏析行为;通过对各特征参数求解,构建了中锰钢溶质元素微观偏析模型,发现中锰钢定向凝固过程中Mn元素偏析指数与Brody-Flemings模型符合较好,而Cr元素偏析指数与Clyne-Kurz模型分布较为一致。

     

    Abstract: The solute element micro segregation behavior during the solidification of medium manganese wear-resistant steel has been systematically studied by means of directional solidification, electron probe microanalysis (EPMA), Factsage and other experiments combined with theoretical calculation. The results showed that the solidification structure of Fe-8.5Mn-2.1Cr-0.95C medium manganese steel was dendrite, and there exist no interconversion between cell and dendrite. Besides, the avera ge secondary dendrite arm spacing of medium manganese steel was 59.77μm when the pulling speed was 50 μm/s during the directional solidification experiment. The results calculated by Factsage showed that the microstructure transformation of medium manganese steel during solidification was L → L + γ → γ, which belonged to the austenite solidification mode, and there is no peritectic reaction and no δ phase and other phase appeared. Based on the “equilibrium cooling” and “IF” modes, the liquidus temperature and solids temperature of medium manganese steel which calculated by Factsage were 1422.93 ℃ and 1280.98 ℃ respectively. In addition, The EPMA experiments indicated that the content of Mn and Cr at the edge of secondary dendrites were significantly higher than those at the center of secondary dendrites. Specifically speaking, the content of Mn decreased from 9.13% to 7.49%, and the content of Cr declined from 2.03% to 1.68% at the same time. Which suggested that the positive segregation behavior of Mn and Cr elements occured during directional solidification of medium manganese steel. By solving the characteristic parameters during the solidification process, the micro segregation model of Mn and Cr elements in medium manganese steel was established. It can be found that the segregation index of Mn calculated by Scheil mode was much higher than the experimental value of EPMA when the solidification fraction was close to 1. However, the results obtained by lever-ruler, Brody-Flemings, Clyne-Kurz, Ohnaka and Won-Thomas models were closer when the solidification fraction was lower than 0.5. Besides, when the solid fraction was less than 0.7, the segregation index of Cr calculated by Scheil model were lower than experiments by EPMA. However, with the solidification process continued, the results of Cr from Scheil model were much higher than experiments. It should be noted that the segregation index of Cr from Brody-Flemings models showed the opposite trend to Scheil model. And there exist little difference among Lever-ruler, Clyne-Kurz, Ohnaka and Won-Thomas models. On the whole, the segregation index of Mn was in good agreement with the Brody-Flemings model. On the whole, the segregation index of Mn is in good agreement with the Brody-Flemings model, while the Cr segregation index was in good agreement with the Clyne-Kurz model.

     

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