Brightever’s ductile iron foundry can make ductile iron casting (SG Iron Casting) of weight from 0.5 kg to 30 tons.. Ductile iron, also known as ductile cast iron, nodular cast iron, spheroidal graphite cast iron, spherulitic graphite cast iron and SG iron which has grown in popularity because its ductility, elasticity and high strength properties allow heavier service loads.