Continuous caster mould digital twin development for fluid flow control and sliver defect minimization

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Steelmakers are constantly challenged to increase the productivity of their continuous casters (CC) while simultaneously maintaining steel slab quality. This is especially challenging for Drawn & Ironed (D&I) and Ultra Low Carbon (ULC) slabs because of stringent quality demands imposed by the customers. These slabs are flat rolled into thin sheets (less than 0.5 mm) and are extremely susceptible to internal and external defects. Therefore, increasing the casting speed for these grades often results in a detrimental impact on cost of poor quality. The defects are created by entrapment of non-metallic inclusions (NMI), such as alumina and mould slag, by the solidifying steel shell inside the CC mould, which continuously receives liquid steel and argon gas through a submerged entry nozzle (SEN). Bubbly steel flow turbulence and instabilities inside the mould are significantly increased at higher casting speeds. This exacerbates the risk of entrapping NMI particles circulating inside the liquid pool. Thus, the flow inside the CC mould must be optimized and then controlled at high caster throughput conditions. The continuous caster digital twin and its application will aim to improve product quality for AMD's slabs and coils. This research program will also utilize a physical modeling approach for flow visualization and quantification and development of a flow index for various casting conditions. A reduced order model-based CFD will also be developed for predicting defects (i.e. NMI particle capture near mould walls) in steel. The flow index will be controlled and adjusted in real time if NMI entrapment is predicted by CFD. At the caster, the project outcomes are expected to enable the increase of maximum casting speed of D&I and ULC steel grades, reduction in defects, and development of real time defect prediction techniques. This will be achieved by identification of improved SEN designs, optimized argon flow rates and better process control techniques. The cost saving arising from improving steel quality is expected to exceed $2.5 million/year. The proposed research project is aligned with AMD's strategic vision and business goals, and will create immediate benefits to AMD, located in Ontario, Canada.