Effect of Mold Cooling Intensity on the Depression-Type Crack Formation and Mold Flux Infiltration During Continuous Casting Process

As one of the most serious defects in the products of continuous casting steel, the surface depressions with longitudinal cracks originated from the mold were clearly characterized. A mold simulator technique was developed to investigate the effects of different mold cooling flow rates (3.5, 6.0, 7.5 L/min) on the evolution of depression-type cracks and mold flux infiltration for the steel continuous casting in this study. The mold simulator results indicated that the depression and longitudinal crack become more serious with the increasing of mold cooling intensities. Furthermore, when the cooling intensity enhanced from 3.5 to 7.5 L/min, the average solidification factor of shell increased rapidly from 2.37 to 2.91 (mm/s)1/2, and the mean heat flux in the initial solidified shells with depressions reduced by 0.723 MW/m2 during the initial 0 to 1.5 seconds solidification stage. In addition, the higher mold cooling intensities of 6.0 to 7.5 L/min could result in an increasing of slag film thickness and the formation of amorphous slag, which contributed to the uneven infiltration of mold flux.