Prediction and optimisation of solidification structure growth and transformation behaviour in microalloy chamfered continuous casting slab

Abstract

The solidification structure of complex chamfered slabs of microalloyed steel was analysed and controlled. A computational model of solidified structures was applied and the model was verified. The research results show that there are differences in the solidification structure inside the slab. The slab successively produces fine-grained areas, large-size columnar grain areas, CET (columnar to equiaxed grain transition), and equiaxed grain areas. The effects of different carbon contents on the solidification structure were analysed. As the c content decreases from 0.23% to 0.20%, the tip growth fitting coefficient a3 increases from 4.077172e-06 to 5.403274e-06, which increases the grain growth rate. Considering the different sensitivities of grain growth in the lateral direction, a lateral zoning water supply strategy is used to flexibly control the uniformity of grain growth. By simulating different water flow ratios in the corners and centre areas, the optimal nozzle water flow density ratio is 0.840. Superheat can effectively control grain distribution. The proportion of central equiaxed grains increases with decreasing superheat. The study found that the proportion of equiaxed grains has different sensitivities affected by different degrees of superheat. The superheat degree ranges of strong sensitivity and weak sensitivity were obtained. In the production practice of superheat adjustment to control particle distribution, the adjustment effect is better within the strong sensitivity range.