Two-phase modelling of mushy zone parameters associated with hot tearing

A two-phase continuum model for an isotropic mushy zone is presented. The model is based upon the general volume averaged conservation equations, and quantities associated with hot tearing are included; i.e., after-feeding of the liquid melt due to solidification shrinkage is taken into account as well as thermally induced deformation of the solid phase. The model is implemented numerically for a one-dimensional model problem with some similarities to the aluminium direct chill casting process. The variation of some key parameters which are known to influence the hot-tearing tendency is then studied. The results indicate that Loth liquid pressure drop due to feeding difficulties and shear stress due to tensile deformation caused by thermal contraction of the solid phase are necessary for the formation of hot tears.