With the development of clean steel technology, the control of non-metallic inclusions in steel is of increasing importance. Magnesium–calcium treatment can effectively balance the castability of molten steel and the control on inclusion size, which is an inclusion modification approach with application prospect. In view of this, how three addition methods (i.e., adding Mg before Ca, adding Mg after Ca, and adding Mg together with Ca) influenced the modification effect of inclusions in liquid iron was experimentally studied, and how these inclusions evolved with time was discussed in this paper. The results demonstrated that despite the sharp difference in their inclusion evolution, composite inclusions with a magnesium aluminate spinel (MAS) core and an outer CaO–Al₂O₃–MgO layer were formed by all the three addition methods, with the average inclusion size of 1–2 μm. Furthermore, thermodynamic calculation was adopted to reveal the transformation relationship between MAS and calcium aluminate in each of the three addition methods, and clarify the formation and disappearance mechanisms of the intermediate product CaS in the process of Mg–Ca treatment. The thermodynamic calculation results agreed well with the experiment data.

中文翻译：

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镁钙处理铁液中夹杂物的演变

随着洁净钢技术的发展，钢中非金属夹杂物的控制变得越来越重要。镁钙处理可以有效平衡钢水的可铸性和控制夹杂物尺寸，是一种具有应用前景的夹杂物改性方法。有鉴于此，通过实验研究了三种添加方式（即先加镁、先加钙、加镁和加钙）对铁水夹杂物变质效果的影响，以及这些夹杂物随时间的演变规律。在本文中讨论。结果表明，尽管夹杂物演化存在显着差异，但具有镁铝尖晶石 (MAS) 核心和外部 CaO-Al ₂ O _{3 的}复合夹杂物–MgO 层由所有三种添加方法形成，平均夹杂物尺寸为 1-2 μm。此外，通过热力学计算揭示了三种添加方法中MAS与铝酸钙的转化关系，阐明了Mg-Ca处理过程中中间产物CaS的形成和消失机制。热力学计算结果与实验数据吻合较好。