Research progress on formation mechanism and control of crack breakout in hypoperitectic steel continuous casting slab

Crack breakout often occurs during the continuous casting process of peritectic steel, which seriously restricts the high-efficiency and high-quality production of peritectic steel continuous casting. Crack breakout mainly originates from solidification defects of the initial solidified shell in the mold. The phase transformation shrinkage of peritectic reaction forms air gaps, leading to uneven heat transfer and uneven thickness of the solidified shell, and crack breakout is prone to occur at the weak parts of the shell. This paper reviews the formation mechanism and conditions of depressions in peritectic steel continuous casting slabs, summarizes the typical characteristics and main influencing factors of slab corner crack breakout, wide-face off-corner breakout and wide-face center crack breakout, and also summarizes the influence laws of steel composition and process factors on crack formation. Aiming at the frequent crack breakout of peritectic steel, this paper puts forward requirements for improving crack breakout from aspects of process factors, mold flux properties and mold design, and points out that establishing a crack breakout risk prediction model for the continuous casting process based on the key influencing factors of crack breakout, and conducting early warning and timely intervention on accident precursor characteristics, is the development direction of future breakout prediction models.