Abstract: With the global push for carbon neutrality, electric arc furnace (EAF) steelmaking using scrap steel has emerged as a key green technology in the iron and steel industry. However, the accumulation of residual elements like antimony (Sb) during scrap recycling poses significant challenges, including grain boundary segregation and high-temperature brittleness, which degrade mechanical properties. To address this, this study proposes a novel strategy of "active control" via rare earth (RE) additions to induce heterogeneous precipitation of FeSb phase, shifting from traditional removal methods. Based on the two-dimensional lattice disregistry theory, the crystallographic matching between typical rare earth inclusions (Ce2O3, Ce2O2S, CeS) and the FeSb phase was calculated. The results showed that the disregistry values for Ce2O3 (0001)/FeSb (0001), Ce2O2S (0001)/FeSb (0001), and CeS (111)/FeSb (0001) were 2.22%, 1.53%, and 2.92%, respectively, all below the 12% threshold for effective nucleation. This confirmed that these inclusions can serve as heterogeneous nucleation sites for FeSb. Experimental validations were conducted through vacuum induction melting of steels with varying Ce contents (0~0.041wt%). Inclusion evolution was characterized using scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS). After Ce addition, inclusions transformed from Al-O and MnS to Sb-containing rare earth composite inclusions (e.g., Ce-Sb, Ce-O-Sb). The number of inclusions per unit area increased from 29 #/mm2 (S-1, no Ce) to 137 #/mm2 (S-3, 0.041wt% Ce), while the average size rose from 1.1 μm to 3.1 μm. This effectively reduced soluble Sb content by fixing Sb within inclusions, thereby mitigating grain boundary segregation. Thermodynamic analysis indicated that the oxygen/sulfur activity ratio influenced inclusion type evolution, aligning with the precipitation sequence of Ce2O3, Ce2O2S, and CeS. This work provides a theoretical foundation for controlling Sb precipitation via RE inclusions, offering a viable pathway to enhance the quality of high-scrap-ratio EAF steels and support sustainable steelmaking.

Key words: two-dimensional lattice disregistry, rare earth cerium, residual element antimony, heterogeneous nucleation, inclusions

摘要： 本工作针对废钢循环利用过程中残余元素锑(Sb)在钢中积累导致的晶界偏聚和高温脆性问题，研究了稀土夹杂物诱导含锑相异质析出的机制。通过二维点阵错配度理论计算了代表性稀土夹杂物(Ce2O3, Ce2O2S, CeS)与FeSb相的晶格匹配度，并结合高温熔炼实验验证其形核效能。结果表明，Ce2O3 (0001)/FeSb (0001), Ce2O2S (0001)/FeSb (0001)和CeS (111)/FeSb (0001)的二维错配度分别为2.22%, 1.53%和2.92%，均低于有效形核阈值12%，表明这些夹杂物可作为FeSb异质形核核心。实验发现，添加稀土铈(Ce)后，钢中夹杂物从Al-O, MnS转变为含锑稀土复合夹杂物(如Ce-Sb, Ce-O-Sb)，且单位面积夹杂物数量从S-1的29个/mm2增至S-3的137个/mm2，平均尺寸从1.1 μm显著增加至3.1 μm，有效降低了固溶锑含量。本研究为利用稀土夹杂物控制锑析出、减轻晶界偏聚提供了理论依据，对高废钢比电炉钢的质量提升具有重要意义。

关键词: 二维错配度, 稀土铈, 残余元素锑, 异质形核, 夹杂物