Design of a submerged entry nozzle for optimizing continuous casting of stainless steel slab

To solve slag entrapment and casting slab defects in the process of stainless steel continuous casting, submerged entry nozzle (SEN) for slab casters operating at casting speed of 1 m/min was developed based on 3D numerical simulation and water modeling experiments by controlling the outlet shape and angle of original SEN with oval and 15 degrees angle outlet under current industrial use. Mathematical simulations of fluid velocity at outlets with different shapes and angles of SENs have been carried out. The results showed that oval outlet with 5 degrees and 15 degrees angle led to asymmetric rotating flow pattern at outlet, as well as square outlet with 15 degrees angle, but symmetric flow pattern formed at square outlet with 5 degrees angle. The effect of these SENs on meniscus stability, flow field and slag entrapment behavior of stainless steel slab casting mold was further studied by water modeling experiments. The results showed that difficult floating fine droplets formed when the angle of outlet was 15 degrees under the dual effect of vortex convection and shear force due to the strong swirling flow from outlet and rotating flow of outlet. However, outlet with 5 degrees angle could lead to the formation of larger slag droplets, while the oval outlet with 5 degrees angle could result in the scour to the mold wall. Thus, the square outlet with 5 degrees angle was a relatively ideal solution for the submerged entry nozzle from the aspects of the stability of the mold and the slag entrapment behavior. After the design of a new SEN according to the experimental result, the solidification structure of continuous casting slab was obviously improved by industrial test.