Evolution of plasticized MnO-Al2O3-SiO2-based nonmetallic inclusion in 18wt%Cr-8wt%Ni stainless steel and its properties during soaking process
Evolution of plasticized MnO-Al2O3-SiO2-based nonmetallic inclusion in 18wt%Cr-8wt%Ni stainless steel and its properties during soaking process
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DOI：
10.1007/s12613-019-1945-z
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发表时间：
2020-03-01
影响因子：
4.8
通讯作者：
Guo, Han-jie
中科院分区：
文献类型：
--
作者：
Guo, Jing;Chen, Xing-run;Guo, Han-jie
由于mno - al2o3 - sio2基增塑夹杂物的熔点较低，其性能在浸泡过程中可能发生变化。通过室内实验和热力学分析，研究了18wt%Cr-8wt%Ni不锈钢在1250℃等温浸泡过程中不同时间mno - al2o3 - sio2基夹杂物的演变。结果表明：包裹体密度先增大后减小，平均尺寸先减小后增大；此外，浸泡前夹杂中几乎没有Cr2O3的富集区，但浸泡过程中形成了越来越多的Cr2O3沉淀。浸泡后，液相数量减少，高熔点相MnO-Cr2O3尖晶石数量增加，导致夹杂物塑性下降。高温共聚焦激光扫描显微镜（CLSM）原位观察证实，包裹体中产生液相，包裹体在浸泡过程中生长较快。实验结果和热力学分析均表明，保温过程中夹杂物的演化有三条路径。其中，奥斯特瓦尔德成熟在包裹体演化过程中起着重要作用，即基于mno - al2o3 - sio2的包裹体通过吸收新析出的小尺寸MnO-Cr2O3包裹体生长。
The properties of MnO-Al2O3-SiO2-based plasticized inclusion are likely to change during soaking process due to its low melting point. In this study, the evolution of the MnO-Al2O3-SiO2-based inclusion of 18wt%Cr-8wt%Ni stainless steel under isothermal soaking process at 1250 degrees C for different times was investigated by laboratory-scale experiments and thermodynamic analysis. The results showed that the inclusion population density increased at the first stage and then decreased while their average size first decreased and then increased. In addition, almost no Cr2O3-concentrated regions existed within the inclusion before soaking, but more and more Cr2O3 precipitates were formed during soaking. Furthermore, the plasticity of the inclusion deteriorated due to a decrease in the amount of liquid phase and an increase in the high-melting-point-phase MnO-Cr2O3 spinel after the soaking process. In-situ observations by high-temperature confocal laser scanning microscopy (CLSM) confirmed that liquid phases were produced in the inclusions and the inclusions grew rather quickly during the soaking process. Both the experimental results and thermodynamic analysis conclude that there are three routes for inclusion evolution during the soaking process. In particular, Ostwald ripening plays an important role in the inclusion evolution, i.e., MnO-Al2O3-SiO2-based inclusions grow by absorbing the newly precipitated smaller-size MnO-Cr2O3 inclusions.