Towards a Micro-Macro Model of Hot Tearing

Modelling of hot tearing must encompass several aspects: solidification, percolation of grains, stress/strain development, liquid feeding. The present contribution reviews recent progress made in this domain, both at the macro- and microscopic levels. At the macroscopic level, average two-phase approaches based on the coupling of a porous medium model for the solid skeleton and liquid feeding (Darcy model) will be presented briefly. Such models provide a clear enhancement of the RDG model[1], especially from a rheology point of view. At the microscopic level, a new granular approach has been undertaken recently. Considering in a first step the solidification and coalescence of equiaxed grains, it has been extended recently to the calculation of feeding using a Kirchhoff-Poiseuille (KPL) model. Percolation of grains and localisation of feeding could be clearly evidenced in this way.