Numerical study on the effect of high efficient cooling nozzles and varying cooling intensity on metallurgical transport behaviors during the slab continuous casting

Abstract

In this study, the spray characteristics of the cooling water flux of the traditional single nozzle and novel dual nozzle were innovatively and effectively incorporated into a 3D/2D flow-temperature-concentration segmented model. The model was used to investigate the effects of spray characteristics on the flow, heat distribution, solute transport, solidified shell, and mushy zone of steel in the continuous casting. The results showed that various flow patterns of liquid steel in the turbulent zone significantly affected the temperature and carbon concentration distribution. Until Zone 7, the cooling water fluxes in the six cases remained unchanged. The peak temperatures of cases 1 and 4 in Zone 7 were 1253.11 and 1273.51 K, respectively, indicating that the spray characteristic was the primary cause of the variations in slab surface temperatures. The cooling water fluxes in the six cases change from Zone 8 onward. The six cases had differences of −21.39, 17.87, 46.95, −22.08, 16.86, and 45.68 K between the initial and final temperatures in Zone 8, respectively, meeting the requirement of keeping the maximum temperature recovery rate of slab surface under 100 °C/m. However, the final temperatures for cases 2, 3, and 6 were 1225.62, 1196.50, and 1218.91 K, respectively. These temperatures fall within a realistic plastic temperature range, which must be higher than 1220 K. As a result, the plastic cracking in the slab was possible. The maximum temperature gradient differences of the six cases between feature lines at the end of Zone 8 were 0.793, 0.814, 0.829, 0.185, 0.179, and 0.179 K/mm. These results showed that the optimization effect on the temperature gradient difference was insignificant as the cooling intensity rose. However, the carbon concentration uniformity was marginally improved by increasing the cooling water flux. Finally, a state-owned steel company in China chose case 5 (dual nozzle with moderate cooling intensity at the slab solidified end) as the optimum option for the slab continuous casting caster. The dual nozzle enhanced and promoted the efficient and homogeneous production of the metallurgical process.