Development of Nozzle Clogging Index to Assess The Casting Behavior During Continuous Slab Caster At

Abstract

The formation and deposition of non-metallic inclusions inside the submerged entry nozzle (SEN) as well as tundish is widely recognized as a crucial problem in the continuous casting of Al-killed steel. The agglomeration of inclusion inside the nozzle not only limits the production by restricting the passage of liquid steel into the mold, but also disturbs the flow pattern. In addition to that, the periodic dislodgement of clogged alumina particles lead to undue melt level fluctuations in the mold and may become an important source of non-metallic macro-inclusions in the cast sections. Thus it is important to take suitable corrective measures in advance to avoid the severe clogging problem. In light of the above, a model has been developed for a more precise quantification of nozzle clogging (clogging index). The model is capable of providing a real-time measure of clogging online during slab casting. This index can be served as a more reliable tool for scheduling the tube change, SEN lancing, tundish change and manual flushing. In addition, an extensive investigation was performed to correlate the rate of clogging with the available liquid steel cleanliness parameters viz., nitrogen pick-up, aluminium fading and LF addition practice to take suitable corrective measures in the upstream of process for smooth casting operation.