Influence Factors on σ-Phase Precipitation of FeCr16 Corrosion-resistant Soft Magnetic Alloy

doi:10.20057/j.1003-8620.2024-00201

Abstract

Abstract: In order to investigate the influencing factors of the precipitation of σ phase in the solidification structure of FeCr16 corrosion-resistant soft magnetic alloy during electroslag remelting process， a series testes has been conducted to study the solidification process and precipitation of FeCr16 corrosion-resistant SMA （Soft Magnetic Alloy） from 1 600 ℃ to 1 400 ℃ at different cooling rates of 5， 10， 20 ℃/min by using 1 LM21H-SVF17SP LSCM （Laser Scanning Confocal Microscopy）. Meanwhile combining with thermodynamic calculation via JMatPro software， the relationship between segregation of Cr and σ-phase precipitation was studied. In addition， the test was performed with different melting rates during ESR process ， and the relationship between σ-phase precipitation and ESR speed was also investigated. The results showed that while the cooling rate of solidification was low， the segregation degree of Cr element in the alloy was relatively high. With the increase of cooling rate， the maximum segregation rate and average segregation rate of Cr element both decreased； The segregation of Cr element provided favorable kinetic conditions for the precipitation of σ-phase. The higher ESR speed was， the slower the solidification rate， the higher the segregation， the more easily the σ-Phase precipitated. When ESR speed was set as 3.5 kg/min-4.5 kg/min， no σ Phase was found in the microstructure of ESR ingot after heat treatment， while the ESR speed was adjusted to 5.0 kg/min-6.0 kg/min， σ-Phase precipitation was detected. The optimal ESR speed was 3.5 kg/min-4.5 kg/min.

Key words: FeCr16 Corrosion-resistant SMA, Cooling Rate, ESR Speed, Segregation, σ-Phase

摘要： 分析了FeCr16耐蚀软磁合金在电渣重熔过程中凝固组织内σ相析出的影响因素，采用1 LM21H-SVF17SP激光共聚焦显微镜，以5、10、20 ℃/min不同冷却速率对FeCr16耐蚀软磁合金进行了从1 600 ℃至1 400 ℃的凝固析出实验。并结合JMatPro软件进行热力学计算，研究了Cr的偏析和σ相析出之间的关系。此外，进行了电渣重熔过程不同熔速的试验，并研究了σ相析出和熔速之间的关系。试验结果表明，冷却速率较低时，合金的Cr偏析程度较大，随着冷却速率的增加，Cr的最大偏析率和平均偏析率均有所下降；Cr的偏析为σ相的析出提供了良好的动力学条件。电渣重熔速度越大，凝固速率越慢，偏析程度越高，越易析出σ相；电渣重熔速度为3.5~4.5 kg/min时，热处理后的组织中未发现σ相，而当熔速调整为5.0~6.0 kg/min时，经过热处理后的组织在晶内及晶界处均有σ相析出。最佳电渣重熔速度为3.5~4.5 kg/min。

关键词: FeCr16耐蚀软磁合金, 冷却速率, 电渣重熔速度, 偏析, σ相

CLC Number:

TG142.1

Zhu Yincun, Song Changjiang, Tian Yuxin. Influence Factors on σ-Phase Precipitation of FeCr16 Corrosion-resistant Soft Magnetic Alloy[J]. Special Steel, 2025, 46(2): 62-66.

朱银存, 宋长江, 田玉新. FeCr16耐蚀软磁合金中σ相析出的影响因素[J]. 特殊钢, 2025, 46(2): 62-66.

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