GRADE TRANSITION STUDY IN COMBINED TUNDISH MOLD ARRANGEMENT IN CONTINUOUS CASTING PROCESS

Abstract

The dominance of the continuous casting method over conventional casting in primary metal production has been recognized for over a century. Continuous casting is the most up-to-date technology available for producing high-quality steel at low cost, and good understanding of what goes on in the tundish is critical because it affects the purity and chemistry of the output steel. The advantages which include a substantial increase in yield, better quality, more uniform production, energy saving and higher productivity made the metallurgical industry, and the entire world of the metal users explore methods to optimize the processes parameters involved in continuous casting. Ladle change over in continuous casting steelmaking process leads to change in 'grade of the steel coming out through the tundish. The main function of tundish has been as a distributor or buffer vessel in continuous casting process. More recently it has been found that apart from serving as a buffer between ladle and mold, quality of steel is greatly governed by the tundish owing to its metallurgical capabilities in terms of mixing, inclusion removal, stratification etc. The intermixing phenomenon takes place when new composition (grade) of steel is made to flow in tundish from the new ladle after the old ladle (carrying old grade steel) is emptied into it. The final casting containing the intermixing amount is of inferior type and has low value and downgrade or re circulated for re melting. The intermixing amount is depends on the flow pattern in the continuous casting tundish and the flow control devices such as dam in the tundish. The flow of molten steel is simulated by water modelling. An experimental set up has been fabricated using Perspex glass. Two different shapes of tundishes and molds has been fabricated. The experiments have been conducted with bare tundishes as well as tundish with dam. The flow field in the tundish is computed by solving the mass and momentum conservation equations in a boundary fitted coordinate system along with a set of realistic boundary conditions. For experiment purpose different condition of flow rate and height has been taken. Analysis has been done for tundish mold combination. The experiment has been performed on slab caster and billet caster. The simulation work also carried out for these shapes with the help of CFD software Fluent 6.3 & Gambit.