رفتار انسداد نازل در فولادهاي بسياري كم كربن تيتانيم دار آرام شده با آلومينيوم

Behavior of Nozzle Clogging in Ti-bearing Al-killed Ultra Low Carbon Steel during Continuous Casting

In the present study, the effect of Ti on the castability of Al killed ultra low carbon (ULC) steel, and the possible reasons for the poor castability of the Ti bearing ULC steel Ti-free grades are investigated. In addition, suitable evaluations have been countered to prevent inclusion deposition in the submerged entry nozzles (SEN) during continuous casting of Ti bearing Al-killed ULC steels. Characteristics of inclusions in the submerged entry nozzle deposit and corresponding liquid steel and slag samples from VD degasser and tundish were investigated. The presence of small quantity of Ti-bearing alumina inclusion was identified to be responsible for the extensive melt freezing inside the SEN deposit and poor castability of Ti-bearing Al-killed ULC steels. The effect of all materials contacting liquid steel subsequent to the VD degassing, on the reoxidation behavior and castability of liquid steel was measured from their chemical composition. The result of this study showed that whereas reoxidation is not enough for the castability of all Al-killed steels, it becomes