Cast Iron Specification

Gray Iron

Gray iron is the original and most common cast iron, so named because of its fracture surface which is typically dark gray in colour. Due to its high carbon content, it has ‘flake graphite’ in its structure. The formation of the flakes or nodules of graphite can be suppressed in part by rapid cooling.

Ductile Iron

Ductile iron was first patented in 1949 after foundrymen searched for the ideal cast iron, which was easy to cast like gray cast iron, but had properties equal to or better than malleable iron. Ductile irons are in fact a family of cast irons characterized by spherical graphite nodules in the structure. These form as a result of the addition of spheroidizers to the cast iron composition.