Grain refinement of as-cast structure of Cr-Ni stainless steels was experimentally studied using heterogeneous nuclei. Refinement of primary grains was achieved in both cast ferritic and austenitic grades. However, imposing a mixed solidification sequence of FCC and BCC phases resulted in a macrostructure without a recognizable Columnar-to-Equiaxed Transition Zone (CET). Non-metallic inclusions in the casting were recorded using automated scanning electron microscopy/energy-dispersive x-ray spectroscopy method, and simulated with FACTSAGE thermodynamic software. In the discussion, the CFD simulated thermal gradient (G) and isotherm velocity (V) in the casting are plotted on Hunt’s map and compared to the experimental position of CET in different steels.