Numerical and Experimental Investigation of Solidification Structure and Macrosegregation in Continuously Cast 2311 Die Steel Slab

A cellular automaton-finite element model and secondary dendrite arm spacing (SDAS) model were established to study the solidification structure and secondary dendrites on the slab of 2311 die steel. The temperature field and solidification structure were verified by nail shooting and acid etching experiments. The SDAS model was obtained by mathematical model and simulation results, which were in good agreement with the results observed by the metallographic microscope. After that, two models were used to simulate the solidification structure and SDAS under different slab thicknesses. In this study, the effect of slab thickness on equiaxed crystal ratio (ECR) and SDAS under the same specific water flow and superheat was studied, and its impact on macrosegregation was further analyzed. With the increase of slab thickness, the ECR increases. The distance between the columnar to equiaxed transition position and the slab surface increases by about 5 mm for every 25-mm increase in slab thickness. Within 30 mm from the slab center, with the increase of slab thickness, the SDAS increases. When the slab thickness increases by 25 mm, the SDAS at the center of the slab increases by about 20 & mu;m. The thicker the slab is, the larger the absolute thickness of center segregated zone, but the segregation degree decreases.

Automated summary

A cellular automaton-finite element model and secondary dendrite arm spacing (SDAS) model were established to investigate the solidification structure and secondary dendrites of 2311 die steel slab. The experimental results of nail shooting and acid etching were used to validate the temperature field and solidification structure. The mathematical model and simulation results were used to obtain the SDAS model, which was consistent with the metallographic microscope observation. The effects of slab thickness on equiaxed crystal ratio (ECR) and SDAS were studied under the same water flow and superheat, and their impact on macrosegregation was analyzed.