Clogging behavior of submerged entry nozzles for Ti-bearing IF steel

The nozzle clogging behavior of Ti-bearing IF steel was studied by metallographic analysis, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). According to the experimental results, nozzle clogging primarily appears three layers. There are a lot of large-sized iron particles in the inner layer and mainly slag phase in the middle and outer layers. The principal clog constituents of the inner layer are loose alumina cluster inclusions and granular shaped alumina inclusions, containing iron particles. The clog constituents of the middle layer are mainly dendrite alumina inclusions. The primary phases existing in nozzle clogging are FeO center dot TiO2 and FeO center dot Al2O3 besides alpha-Al2O3 and alpha-Fe. The FeO center dot TiO2 phases among the deposits adhere the deposits together firmly enough to lead to the inferior castability of Ti-bearing ultra low carbon steel compared with that of Ti-free low carbon Al-killed steel.