Effect of remelting time on initial phase in semisolid microstructure of hypereutectic high chromium cast iron

To investigate the effect of thixo-remelting time on the morphologies of initial carbides, semi-solid billets of Crl7 hypereutectic high chromium cast iron were partially remelted at 1270°C for four distinct periods (5 min, 15 min, 25 min, and 30 min, respectively), and the shape factor and grain factor of carbide grains were characterized quantitatively via a Leica image analyzer. The results indicate that firstly the evolution process of grain morphology during partial remelting undergoes grains melting, spheroidization and refining, and grains growth; secondly, the solute diffusion and interface tension play a predominant role respectively at the primary stage and the middle-final stage in the process of microstructure evolution; finally, the perfect remelting microstructure could be expected to obtain at 1270°C for 15 min in this investigation.