20MnSi steel samples with different rare-earth yttrium (Y) contents are prepared in the laboratory. Microstructure analysis is performed using the methods of microscopy and electron probe microanalysis, and the mechanical and physical properties are assessed using the tensile tester and thermal dilatometer. The results show that with increasing Y content, the thickness of the martensite layer on the surface of 20MnSi steel decreases gradually until it almost disappears, which is attributed to Y reducing martensitic transformation temperature. Y refines the size of the pearlitic lamellae, which improves the yield strength. Y-containing composite inclusions (Y₂O₂S) of microsized spheres are easily formed in the steel, which assists the nucleation of ferrite, thereby resulting in an increase in the yield point elongation. In addition, the content of inclusions increases, thereby resulting in a decrease in uniform elongation.

中文翻译：

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钇对20MnSi钢组织和性能的影响

在实验室中制备了不同稀土钇 (Y) 含量的 20MnSi 钢样品。使用显微镜和电子探针微量分析的方法进行微观结构分析，并使用拉伸试验机和热膨胀仪评估机械和物理性能。结果表明，随着Y含量的增加，20MnSi钢表面的马氏体层厚度逐渐减小直至几乎消失，这是由于Y降低了马氏体转变温度。Y细化了珠光体片晶的尺寸，从而提高了屈服强度。含Y复合夹杂物（Y ₂ O ₂S)的微球容易在钢中形成，这有助于铁素体的形核，从而提高屈服点延伸率。此外，夹杂物的含量增加，从而导致均匀伸长率降低。