The Importance of Solidification Structure with Respect to Hot Tearing during Continuous Casting of Steels

During the solidification of steels, events such as micro/macro segregation as well as the generation of defects and porosity strongly depends on the solidification grain structure. Until now, the relevant literature generally has dealt with the primary or the secondary dendrite arm spacing to characterize the solidification structure. However, these phenomena and particularly the phenomenon of hot tearing during continuous casting of steels occur mainly between primary grains along primary grain boundaries. In this regard, it is very important to note that the primary grain size increases with increasing distance from the surface of the product. Based on theoretical considerations and investigations into the solidification structure of a continuously cast round bloom in combination with the appearance of hot tears, the present study responds to the following questions: How does the primary grain size and subsequently the number of primary grain boundaries, respectively influence the phenomenon of hot tearing and how does the morphology of the solidification structure (i.e. zone of columnar vs. equiaxed grains) influence the extent of open hot tears and hot tear segregations?