A method to control ausferritic as-cast microstructure in ductile iron parts

A method to control the ausferritic as-cast microstructure in iron parts with sections of different thicknesses, which comprises:

a) Calculate the cooling rate for the maximum and minimum thermal moduli considering an air cooling.

b) Calculate the minimum cooling rate needed to avoid the pearlitic nose, as a function of different contents of Ni, Cu and Mo (CRmin).

c) Select one of the compositions with a minimum cooling rate (CRmin) lower than the cooling rate for the maximum thermal modulus.

d) Calculate the eutectoid temperature (Teutectoid) as a function of the thermal modulus for the composition selected, for all the different thermal moduli of the part.
e) Calculate the shake-out temperature (Tshakeout) for all the different thermal moduli of the part.

f) Identify if Tshakeout for the minimum thermal modulus is over the eutectoid temperature (Teutectoid) calculated in d) and if Tshakeoutfor the maximum thermal modulus is below the solidus temperature (Tsolidus)