Slab Center Segregation Of The Hangang Two Steelworks

The thesis studies the centerline segregation of the 180×1200mm superlow head slab from the second plant of the Handan Iron and Steel Corporation(HISCO) experimentally and theoretically. It searches the inclusions in the slab through experiments as follow: sulphur prints, acid etches, display of the solidified structure, observation with the multiple purpose metallograph and analysis with flying clectron microscope and so on. It erects heat-transfer mathematics model of solidification to optimize the second cooling. And it uses PHOENICS software to simulate current field in the crystallizer, especially the submerged nozzle. It optimizes the parameters of the submerged nozzle with an eye to draw speed, immersion depth and angle of submerged nozzle. And then, it erects mathematics models which simulate the centerline segregation in slabs. It analyzes the characters of the solute distribution in liquid and solid steel and the effective distribution coefficient. Meanwhile it expounds the relation between the flow of liquid steel and centerline segregation. According to the experiments, it has proved that the centerline segregation mathematics module and the flow mathematics module are applicable. And it forecasts the centerline segregation successfully.Through all of the experiments, it studies the centerline segregation in slabs synthetically in view of raw and processed materials for steelmaking, steel making, protecting pour, current field in the crystallizer, heat-transfer in solidification and casting facilities. On the basis of experiments, it proposes some improving measures which aim at HISCO. And it has succeeded. Such as, it adopts continuous rectification instead of multi-point rectification. It also adopts slight compressing technology without increasing any equipment by shortening rollpass in the second cooling.