• CN:11-2187/TH
  • ISSN:0577-6686

机械工程学报 ›› 2020, Vol. 56 ›› Issue (18): 73-80.doi: 10.3901/JME.2020.18.073

• 材料科学与工程 • 上一篇    下一篇

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B439铁素体不锈钢凝固过程中TiN析出热力学分析

董旭光1, 付俊伟2   

  1. 1. 沈阳理工大学材料科学与工程学院 沈阳 110159;
    2. 合肥工业大学材料科学与工程学院 合肥 230009
  • 收稿日期:2020-01-06 修回日期:2020-05-28 出版日期:2020-09-20 发布日期:2020-11-17
  • 通讯作者: 付俊伟(通信作者),男,1979年出生,博士,副教授,硕士研究生导师。主要研究方向为耐热钢、模具钢及耐热铝合金组织及性能控制。E-mail:hitfujw@163.com
  • 作者简介:董旭光,男,1982年出生,博士,副教授。主要研究方向为合金的成分设计及组织性能控制。E-mail:xgdong@alum.imr.ac.cn
  • 基金资助:
    国家自然科学基金资助项目(51571081)。

Precipitation Thermodynamics of TiN in B439M Ferritic Stainless Steel during Solidification

DONG Xuguang1, FU Junwei2   

  1. 1. School of Materials Science and Engineering, Shenyang Ligong University, Shenyang 110159;
    2. School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009
  • Received:2020-01-06 Revised:2020-05-28 Online:2020-09-20 Published:2020-11-17

摘要: 虽然TiN析出热力学已有较为广泛的研究,但TiN异质形核热力学报道较少。TiN热力学计算表明,TiN不会在熔炼过程中析出,凝固过程中Ti和N元素被逐渐排到固、液界面,和初始成分相比,凝固末期液相中Ti和N的浓度分别提高了7.4和3.2倍。依据析出热力学以及钢中MgO及Al2O3的能谱分析可知,钢液冷却时首先析出镁铝尖晶石(MgO·Al2O3),TiN以这些氧化物为核心进行异质形核。Ti、Nb稳定的B439M铁素体不锈钢中观察到存在复合型夹杂:TiN以氧化物为核心形核,TiN被外层的NbC包裹住,形成复合型夹杂,试验结果和热力学计算一致。试验结果证明,Ti优先和N结合形成TiN,而Nb倾向和C结合形成NbC。

关键词: B439M铁素体不锈钢, TiN夹杂物, 凝固析出, 热力学分析

Abstract: The precipitation thermodynamic of TiN in ferritic stainless steel has been extensively researched. However, few works referring to the thermodynamics of TiN precipitation heterogeneously is performed. Thermodynamic calculation of TiN shows that TiN does not precipitate during the melting process in B439M ferritic stainless steel. During solidification, the content of Ti and N in the liquid is increased by 7.4 and 3.2 times the initial composition at the end of solidification. The EDS mapping and thermodynamics calculations of MgO and Al2O3 show that the Mg-Al spinel (MgO·Al2O3) will form preferentially in the melts. As a result, the composite inclusion can be observed in the microstructure. First, TiN can nucleate heterogeneously with MgO and Al2O3 oxides acting as heterogeneous sites. Then, NbC will nucleate with TiN as the core to form the composite include, which is in agreement with the calculated results. This can provide experimental evidences that in ferritic stainless steels, Ti tends to combine with N to form TiN, and Nb is prone to combine with C to form NbC.

Key words: B439 Ferritic stainless steel, TiN inclusion, solidification precipitation, thermodynamics analysis

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