What is the difference between ductile iron and cast iron?

Ductile iron is an alloy of cast iron or grey iron in which the carbon forms into nodules as opposed to plates as it is in grey iron. This makes the metal more ductile than cast iron hence the name.

Ductile iron has greater strength and ductility than gray iron. Those properties allow it to be used effectively in a wide variety of industrial applications, including pipe, automotive components, wheels, gear boxes, pump housings, machine frames for the wind-power industry, and many more.