Study of the Submerged Entry Nozzle Failure during Casting of Ti‐Bearing Ultra‐Low Carbon Steel

The failure of the submerged entry nozzle (SEN) during continuous casting of Ti‐bearing ultra‐low carbon steel is studied experimentally based on morphological analysis and related thermodynamic calculations. The types of inclusions in molten steel have been discussed, and the failure mechanism has been studied in detail. The results show that the carbothermic reaction of SiO 2 and graphite and the formation of pores promote the adhesion of Al 2 O 3 inclusions in the inner wall. The clogging can be divided into: dense clogging, solidified steel, and loose clogging. Among them, the initial clogging is caused by the decarburization. Large‐size inclusions fall off from the loose clogging and enter the mold, which deteriorates the slab quality. The inclusions in the slab are mainly composed of TiN‐wrapped Al 2 O 3 , TiN‐bearing Al 2 O 3 , and Al 2 O 3 . With the further increase of the size of Al 2 O 3 , the inclusions in the slab are mainly Al 2 O 3 . To improve the service life of the SEN, suggestions of optimizing the refining process, changing the position of slag‐line erosion, and adopting carbon‐free SEN are given. Additionally, applying electric field may help as well.