铝热还原制备高钛铁脱氧性能的研究

Research on the Deoxidation Performance of High Titanium Ferro Prepared by Thermite Reaction

摘要:

炉外铝热反应制备的高钛铁合金由于Al、O含量高，不能直接用于钢水精炼过程。本文研究了高铝高钛铁在钢液精炼过程中的热力学，以及高钛铁中铝和铁含量对钢液精炼过程的影响。结果表明：采用Ti和Al作为复合脱氧剂，在1873K当钢水中的aTi/aAl大于8时，脱氧产物为Ti2O3；但事实上，只有当液态钢中的aTi/aAl值高于10时，Ti2O3才会作为脱氧产物沉淀。采用高铝高钛铁作为脱氧剂，钢水中铝和钛的含量可以满足相关钢的成分要求。随着高钛铁含量的增加，精炼后的铸钢中夹杂物由硅酸盐转变为Ti-Al-Mn复合夹杂物；同时，在这些夹杂物周围形成径向针状铁素体，细化了钢的微观结构。实际系统中的aTi/aAl值为17.78（> 8），与理论结果一致。当钢液中的氧含量高时，控制钢水中aTi/aAl的值是至关重要的。

Abstract:

Due to the defects of high aluminum residue and high oxygen residue, high titanium ferro alloy prepared by thermite reaction outside the furnace cannot be directly used in liquid steel refining process. In this paper, thermodynamics of the high titanium ferro with high aluminum used in liquid steel refining process was researched, and then effects of the amount and the aluminum content in high titanium ferro onthe liquid steel refining process were also studied. The results indicate that: using Ti and Al as composite deoxidizers, the deoxidizing product at 1873K is Ti2O3 when the aTi/aAl in liquid steel is above 8; but in fact, only when the aTi/aAl value in liquid steel is above 10, Ti2O3 precipitates as deoxidizing product. Using high titanium ferro with high aluminum content as deoxidizer, the content of aluminum and titanium in liquid steel can meet the requirements of composition for the related steel. With the increasing amount of high titanium ferro, inclusions in cast steel after refining transformed from silicate into Ti-Al-Mn composite inclusions；and at the same time, obvious or part of radial acicular ferrite forms around those inclusions, which refines the microstructure of steel. The aTi/aAl value in the actual system is 17.78(>8), which is consistent with the theoretical results. It is vital to control the values of aTi/aAl in the liquid steel when the oxygen content in liquid steel is high.