in sg iron graphite will be in the form of
Ductile iron Ductile iron, also known as ductile cast iron, nodular cast iron, spheroidal graphite iron, spheroidal graphite cast iron[1] and SG iron, is a type of graphite-rich cast iron discovered in 1943 by Keith Millis.[2] While most varieties of cast iron are weak in tension brittle, ductile iron has much more impact and fatigue resistance, due to its nodular graphite inclusions.