Ductile iron

![Ductile iron microstructure at 100×. Note carbon islanding effect[4] around nodules.](/uploads/202502/10/Ductile_Iron4450.png)
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.