Abstract: A problem of nozzle clogging in submerged entry nozzle (SEN) used in the continuous casting process of Tibearing ultralow carbon steel was studied.Experimental analysis methods like XRF and SEMEDS were used to analyze the composition and phase of the nodule in the upper inner wall and inside the bottom of the SEN,and the precipitation conditions of the inclusions were calculated by using the Factsage thermodynamic calculation software.The results showed that the deposition in the upper inner wall of the nozzle was mainly Al₂O₃ inclusions and frozen steel,which were obvious stratified into different layers. And the blocking at the bottom of the nozzle was caused by the deposition from the upper inner wall and the accumulation of frozen steel.Thus,a model of “clogging-scouring-accumulating-blocking” was established to describe the process at the bottom of the nozzle.Al₂O₃

Key words: SEN, clogging, inclusion, stratification, thermodynamic calculation