Ti-Fe-MgO复合球团原位制造镁蒸气的脱氧行为及其在钢液中的弥散冶金机制研究

Fine inclusions less than 1μm are sufficient to accelerate nucleation of intragranular acicular ferrite during solidification process of liquid steel, as well as improve the comprehensive properties of steel. So far, the study and control of dispersive distribution for non-metallic inclusion particles in liquid steel has been an important development direction of clean steel metallurgical technology. According to the theory of metallothermic reduction, the present work has proposed a novel multiple pellet composed of metal and submircon oxide particles. After the pellet is added to liquid steel, MgO inside the pellet can be reduced by titanium, and Mg vapor then reacts with dissolved oxygen. Since Mg vapor yields as it then reacts with oxygen, the utilization rate of Mg vapor is also improved, and it is expected to be a new attempt of Mg addition into liquid steel. Both reduction products and deoxidation products constitute the inclusion system in liquid steel, which combines the advantages of endogenous and foreign introduction of fine particles. In general, the inclusion particles containing Ti and Mg present a good dispersion and disaggregation, it is therefore desired to provide more nucleation sites for intragranular acicular ferrite and provide a novel method to obtain the fine particles during the process of oxide metallurgy. The expected results for this project will provide the important theoretical directions for developing the high value-added large heat input welding steel, unquenched micro-alloyed steel and so on.

钢中微小夹杂物粒子（<1μm）可以诱发钢液凝固过程中晶内铁素体形核，显著提高钢基体的性能。研究和控制钢中微小夹杂物粒子的弥散化分布已成为洁净钢冶炼工艺技术的一个重要发展方向。本项目基于金属热还原原理，设计并制备了一种由金属-亚微米氧化物粒子构成的Ti-Fe-MgO系复合球团。利用球团内部金属钛原位还原MgO产生的镁蒸气脱氧，该过程具备"边生成、边消耗"的特征，可以克服金属镁直接加入钢液收得率低的困扰，是高温钢液中镁加入方法的全新尝试。球团内部钛系还原产物（TiOx）最终分散于钢中并与镁系脱氧产物组成微小夹杂物体系，可发挥在钢中内生和引入外来氧化物粒子的双重优势。由于Mg系、Ti系夹杂物在钢液中弥散性好、不易聚合，可为晶内铁素体形核提供更多的反应地点，并期望为氧化物冶金技术提供一种全新的微小夹杂物获取手段。项目预期成果将对于高附加值大线能量焊接用钢、非调质钢等的研制开发具有重要理论指导意义。

控制钢中微小夹杂物粒子的弥散化分布已成为洁净钢冶炼工艺技术的一个重要发展方向，这主要是因为钢中微小夹杂物粒子（<1μm）可以诱发钢液凝固过程中晶内铁素体形核，显著提高钢基体的性能。本项目基于金属热还原原理，设计并制备了一种Ti-Fe-MgO系复合球团，利用球团内部金属钛原位还原MgO产生的镁蒸气脱氧，实现了在钢液中原位制备镁系微小弥散分布的夹杂物。实验钢组织与性能检测结果表明，采用该种方法，可有效控制凝固过程、轧制过程钢材组织的演变，有利于机械性能的提高；可有效起到诱导晶内铁素体形核的作用，进而对实验钢焊接热影响区组织实现了有效控制，有利于提高焊接热影响区的性能。本项目对钢中非金属夹杂物细小弥散化机制的解析以及晶内铁素体形成机制的探讨，对于完善氧化物冶金理论具有重要的科学意义。该技术在大能量焊接用钢、微合金钢中等的实际生成中将具有广泛的应用前景。