Effect of types of calcium-containing alloy on non-metallic inclusions in high-Al steel

The influence of different calcium-containing alloys on inclusions in high-Al steel is investigated in the current study. The effects of SiCa, AlCa20, AlCa75 and FeSi alloys on the modification of solid inclusions in molten steel are compared, and the mechanism of inclusion evolution is revealed based on the non-uniform distribution of elements and the lattice mismatch between the inclusion particles. The results show that the Ca yield of FeSi alloy is 26%, which is significantly higher than that of other alloys (<5%). In addition, the calcium treatment by FeSi alloy causes less aspiration of molten steel, which is conducive to avoiding the increase of AlN in high-Al steel. After calcium treatment, the primary Al 2 O 3 particles in steel are transformed into CaO-Al 2 O 3 -CaS and CaO-Al 2 O 3 -MgO complex inclusions, while AlN can only be precipitated in the form of a single particle, or precipitated from the transformed CaO · 2Al 2 O 3 oxide. In general, FeSi alloy has the best effect on the modification of Al 2 O 3 inclusions, which can maximize the transformation of solid particles into liquid inclusions in steel liquid without introducing too much impurities.