Homogenization of ductile iron using partial melting aided by modeling

To provide sufficient hardenability, ductile iron is alloyed with some elements like Mn, Cu, Mo or Ni. However, alloying elements segregation is intrinsic to solidification of ductile iron. Segregation of these elements causes a non-uniform structure which reduces the mechanical properties of iron. It was shown by many researches that high temperature solid state homogenization even after a long period does not effectively reduce the segregation of alloying elements. s study, partial melting homogenization (PMH) of 1% Mn ductile iron was used for studying homogenization. The homogenization was carried out at different temperature for different periods. The results show that heating above eutectic temperature increases liquid fraction as a function of time while, heating between eutectic temperatures of different region causes melting of heavily segregated regions only. It was shown that the liquefied region shrinks during PMH process which eventually disappears. SEM–EDX analysis results show heating below eutectic temperature reduces segregation extensively, while above it, segregation intensity increases. calculated segregation profile, assuming uniform chemical composition of liquid pool and local equilibrium at solid–liquid interface, homogenization time for different homogenization temperatures were calculated. The calculated results show good agreement with experimental results.