Abstract
Secondary cooling and final electromagnetic stirring (F-EMS) are both key technologies for continuous casting. These parameters are usually optimized and controlled separately which caused internal quality fluctuations in unsteady conditions. In this paper, a coordinated optimal control strategy based on a multiobjective particle swarm optimization (MOPSO) algorithm is proposed for the parameter optimization of secondary cooling and F-EMS, which is solved based on multiobjective particle swarm optimization (MOPSO) algorithm. The solidification and heat transfer model are developed for the computation of billet temperature and the solidification, and the adaptive grid method is used to improve the diversity and robustness of optimal solutions. The secondary cooling water and F-EMS’ stirring current are dynamically controlled based on the optimization results. The results of field trials showed that the maximum carbon segregation and other quality indexes of billets can be improved significantly.
Highlights
Continuous casting of steel is a process that molten steel is solidified into “semifinished” products, such as billets, blooms, and slabs, which are subsequently sent for rolling in the mills
Primary cooling occurs and makes a supporting solidified shell with molten steel inside. en, the strand is continuously withdrawn through a series of secondary cooling zones (SCZs) where water cooling happens with sprays
In this paper, aiming at improving the production quality of continuous casting billets such as macrosegregation of high-carbon steels, a coordinated multiobjective optimization and control strategy is developed based on solidification and heat transfer model. e optimal solution and research results are applied to the dynamic control of the actual billet caster and good effects have been achieved
Summary
Continuous casting of steel is a process that molten steel is solidified into “semifinished” products, such as billets, blooms, and slabs, which are subsequently sent for rolling in the mills. When exit from the secondary cooling zones, the strand is cooling off by radiation in the air It is cut into fix-length strips and transported to rolling mills for further processing. In the continuous casting process, electromagnetic stirring is commonly used to improve the billet quality, including mold electromagnetic stirring (M-EMS), secondary cooling electromagnetic stirring (S-EMS), and final electromagnetic stirring (F-EMS). Secondary cooling water flows are determined by steel grade and size of billet and optimized as functions of casting speed for a specific caster.
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