Physical Simulation On Influence Of Nozzle Configuration Parameters On Flow Field In Heavy Slab Mold

With the development of continuous casting process of high efficiency, the metallurgical effects of mold and submerged entry nozzle (SEN) become more and more important. The strand quality and smooth production are affected by unreasonable liquid steel flow behaviors. Besides the casting speed and gas blowing rate, the liquid steel flow behaviors is mainly affected by the structure parameters of SEN. Therefore, it's very important to investigate and optimize the structure parameters of SEN to improve slab quality and production process.A 0.5:1 mold model based on slab mold at No.3 slab caster of BaoSteel was established in the paper. Associate with the condition in plant and the defects of slab quality, the influences of the original nozzle and the candidate nozzle on the liquid surface level fluctuation, the distribution of liquid slag, slag entrapment, bubble distributions, impact depth and flow flied in the mold were investigated. The influence of the bottom shape and port shape on the flow behaviors of the liquid steel was studied to optimize the working nozzle. Finally, the trials were carried out in plant.The results showed that surface longitudinal cracks in the wide slab were mainly caused by the weak upper flow circulation in the mold, the slow heat exchange near the meniscus and the non-uniform melting of the mold powder. Therefore, the five new nozzles were designed by changing the shape of the nozzle, the ratio of central orifice to port area and bottom shape, and two nozzles were chosen at last. The modified SEN with smaller outlet thickness, 15°downward port angle and convex bottom was designed to the mold of thickness of 220mm.The nozzle of mold of thickness of 300mm was modified with 15°downward port angle and flat bottom.As a result, the fluid flow of molten steel was stable and the temperature distribution was uniform to improve the wide slab quality when the optimized nozzle was used. The trials in plant showed that the slag distribution was uniform by the use of optimized nozzle. The surface longitudinal crack was decreased over 30%, and the rejection of slab did not occur. The surface inclusions were decreased more than 5%. It's indicated that the use of the optimized nozzle was very well.