Ductile iron, also known as nodular cast iron, is a type of cast iron that has been treated to improve its mechanical properties. It contains small amounts of magnesium, which helps to create a more flexible and resilient material. This makes ductile iron ideal for applications where strength and durability are essential, such as in automotive components and pipe fittings. The unique structure of ductile iron allows it to withstand significant stress without breaking, making it superior to traditional cast iron. Its excellent castability and machinability also contribute to its popularity in various industries, including construction and manufacturing.