Ductile iron—sometimes called ductile iron, nodular cast iron, ductile iron, or SG (cast) iron—has been an industry favorite since its invention in the 1940s and perfected in the 50s, 60s and beyond. reason? Spheroidal graphite nodules dot its infrastructure, providing structural integrity not found in ordinary cast iron (aka gray iron). Mechanical Properties of Ductile IronUnlike...