A reduction in hot cracking via microstructural modification in dc cast billets

Abstract

The Kozeny-Carman relationship is a widely acknowledged analytical model that describes the permeability of porous structures using structural parameters. This model is applied frequently to DC casting simulations and descriptions to describe the hot-tearing sensitivity of the mushy zone. Often, the structural parameters used in the Kozeny-Carman expression are difficult to obtain and uniform values are applied for a variety of casting conditions. However, changes in fluid flow within the molten pool with all other casting conditions identical can significantly alter the microstructure, and thus the permeability of the mushy zone. In this study, we perform a set of stirring experiments using a standard DC casting setup, which demonstrate the relative importance of not only the grain size, but also the grain morphology in decreasing the hot-cracking sensitivity of cast aluminum products.