A fully coupled analysis of fluid flow, heat transfer and stress in continuous round billet casting

The thermal and vectorial fields in the strand and the temperature distribu tion in the mold were analyzed with a finite difference method (FDM) consid ering the effects of turbulence and natural convection of molten steel. The thermo-elasto-plastic behaviors of the strand and the mold were analyzed w ith a finite element method (FEM) laking into account the ferrostatic press ure due to the gravity force and the mechanical behaviors of the strand in liquid phase, mushy zone and delta/gamma phase. The microsegregation of sol ute elements in steel was assessed to determine some characteristic tempera tures and solid, delta-Fe and gamma-Fe fractions in the mushy zone. The hea t transfer coefficient between the solidifying shell and the mold wall was iteratively determined with the coupled analysis of the fluid flow-heat tra nsfer analysis by the FDM and the thermo-elasto-plastic stress analysis by the FEM. With the above procedure, the mathematical model has been develope d to predict the possibility of cracks in the strand, originated from the i nterdendritic liquid film in the mushy zone, through the fully coupled anal ysis of fluid flow, heal transfer and stress in the continuously cast round billet. The calculated mold temperature and heat flux at various casting s peeds show good agreements with the reported experimental observations.