What is "ductile iron"

n. A form of cast iron used in many industrial applications.

Ductile iron, also known as ductile cast iron, nodular cast iron, spheroidal graphite iron, spheroidal graphite cast iron and SG iron, is a type of cast iron invented in 1943 by Keith Millis. While most varieties of cast iron are brittle, ductile iron has much more impact and fatigue resistance, due to its nodular graphite inclusions.

On October 25, 1949, Keith Dwight Millis, Albert Paul Gagnebin and Norman Boden Pilling received US patent 2,485,760 on a Cast Ferrous Alloy for ductile iron production via magnesium treatment.