The Family of Ductile Irons

The majority of Ductile Iron castings are produced in one of the following three types, all of which can be produced in the as-cast condition without the need for heat treatment.

FERRITIC DUCTILE IRON (60-40-18)

Graphite spheroids in a matrix of ferrite which is basically pure iron. High impact resistance. Relatively good thermal conductivity. High magnetic permeability. Low hysteresis loss. In some exposures, good corrosion resistance. Good machinability.

PEARLITIC-FERRITIC DUCTILE IRON (80-55-06)

Graphite spheroids in a mixed matrix of ferrite and pearlite. This is the most common grade of Ductile Iron. Properties are between those with "fully ferritic" or "fully pearlitic" structures. Good machinability. Usually the least expensive Ductile Iron.

PEARLITIC DUCTILE IRON (100-70-03)

Graphite spheroids in a matrix of pearlite. Pearlite is a fine aggregate of ferrite and cementite (Fe3C). Relatively hard. Moderate ductility. High strength. Good wear resistance. Moderate impact resistance. Somewhat reduced thermal conductivity. Low magnetic permeability. High hysteresis loss. Good machinability.

MATRIX

Ferric Grade 60-40-18	Ferric- pearlitic Grade 80-55-06	Pearlitic Grade 100-70-03	Martensitic (With retained austenite)	Tempered Marten- sitic	ADI Grade 150-100-7	ADI Grade 230-185--	Austenitic
60000 psi 414 mPa	80000 psi 552 mPa	100000 psi 690 mPa	N.A. *	115000 psi 793 mPa	150000 psi 1050 mPa	230000 psi 1600 mPa	45000 psi 310 mPa

*Approximate ultimate tensile strength 87,000 psi (600 mPa) Hard, Brittle
(Note that the magnifications are different)