Abstract: This article investigates the influence of microalloying with different Ce contents on the precipitation of carbonitrides in 441 ferritic stainless steel through high-temperature thermal simulation experiments and thermodynamic calculation.The results indicate that there are two main types of carbonitrides in 441 ferritic stainless steel without rare earth Ce addition： separately precipitated carbonitrides and heteronucleated composite carbonitrides. After adding rare earth elements to the steel， Al in the nucleation oxide of carbon nitride is gradually replaced by Ce， and the modification order is Al2O3·Ti2O3→AlCeO3·Ti2O3→Ce2O3·Ti2O3. After modification， the mismatch between Ce2O3 and carbonitrides is higher， resulting in a weakened nucleation ability. This not only transforms the morphology from fully encapsulated to semi encapsulated structure， but also intensifies the precipitation of individual carbonitrides. With the addition of high content rare earth elements， CeN gradually precipitates in the steel， and the precipitation process of TiN is inhibited， reducing the precipitation area of carbonitrides and gradually spheroidizing the morphology of carbonitrides. As high content rare earth elements are added， CeN gradually precipitates in the steel The precipitation process of TiN is inhibited during this process， reducing the precipitation area of carbonitrides and gradually spheroidizing their morphology.By comparing different Ce samples， the rare earth addition amount is 0.007%， which increase the density of heterogeneous nucleation compared to the original cast carbonitrides. The density of carbonitrides increases from 66.7 number/mm2 to 74.5 number/mm2， with an average size concentration of 1-3 μm. The best effect is to refine the grain size.

Key words: 441 Stainless Steel, Solidification Process, Rare Earth, Carbonitrides, Rare Earth Inclusions

摘要： 通过高温热态模拟实验和热力学计算，考察了不同Ce含量微合金化对441铁素体不锈钢中碳氮化物特征的影响规律。结果表明，无Ce添加的441铁素体不锈钢中碳氮化物主要有两种类型：单独析出的碳氮化物和异质形核的复合碳氮化物。钢中加入稀土后，碳氮化物形核氧化物中的Al逐渐被Ce取代，改性顺序为 Al2O3·Ti2O3→AlCeO3·Ti2O3→Ce2O3·Ti2O3。改质形成的Ce2O3与碳氮化物的错配度较高，形核能力减弱，这既使形貌由全包裹向半包裹结构转变，又造成了单独析出碳氮化物析出加剧。高含量稀土添加后，CeN会逐渐出现，TiN的析出过程受到抑制，降低了碳氮化物的析出面积，碳氮化物逐渐转化为类球形形貌。通过对比不同Ce含量试样，当稀土添加量为0.007%，与原始铸态的碳氮化物相比，增加了异质形核的数量密度，碳氮化物的数量密度由66.7个/mm2上升到74.5个/mm2，平均尺寸集中在1~3 μm，细化晶粒效果最好。

关键词: 441不锈钢, 凝固过程, 稀土含量, 碳氮化物, 稀土夹杂物