Study On The Flow Behavior Of Molten Steel In A New Immersion Nozzle Crystallizer For FTSC Thin Slab Continuous Casting

In this paper,the flowing field for the molten steel in the mold connected to the submerged nozzle using in the continuous casting process for four kinds of the FTSC(Flexible Thin Slab Casting)thin slab was studied by the physical water simulation experiment and the finite element data simulation.The model for the nozzle with 1:1 ratio(compared to the practical nozzle)was used in physical water simulation experiments.Moreover,the morphology of the flow field under three pulling speeds was took a picture to obtain the proper parameters close to the actual working conditions.On the basis of the results obtained from physical water simulation experiments,the finite element data simulation was conducted with a rational grid division.The flow field data for the molten steel in the in the mold connected to the submerged nozzle was obtained through data simulation method.According to the internal flow state,the surface velocity and the free surface flow field of the mold,the metallurgical effect of four kinds of new nozzle was preliminary evaluated.The results were showed as follows: For nozzle 1#,the flow field morphology and the impact depth of the steel in the mold has little change with the slow increase of casting speed.For nozzle 2#,the liquid level in the mold was easy to fluctuate as casting speed increasing,which could improve the effect of liquid level slagging,while it was not beneficial for the coil slag controlling.For nozzle 3#,a small vortex was easy to form at the bottom of molten steel in the mold,at the same time,the extent for the fluctuation of meniscus level was large,which resulted in the inclusion floating and the greater probability of the coil slag.For nozzle 4#,the fluctuation of the meniscus level for the molten steel in the mold could cause uneven heat transfer,at the same time,the impact depth of the molten steel was relative shallow that could result in the less decrease of the stream temperature,which was helpful for the slagging due to the increase the surface temperature for the molten steel.In conclusion,the nozzle 1# was more suitable for the steel sensitive to the crack sensitive steel and the nozzle 4# was suitable for the steel under the high pulling speeds.