The strength of the spheroidal graphite(SG) or nodular cast iron is a result of a change in morphoglgy of flake graphite into graphite spheroids. The lower surface area to volume of the spheroids increases its fracture toughness and hence reduces crack propagation. SG iron is an excellent conductor of heat and increases the resistance to fire-cracks by reducing the locally induced thermal stresser. The impact resistance is also increased to that of flake graphite iron.
This grade, Alloyed with the Nickel, Manganese and Chromium with a Bainitic-Acicular-Martensitic Matrix has a higher UTS, hardness and is more wear resistant than the SGP quality. Semi-continuous carbides maintain the wear resitance, while at the same time exhibiting high strength and resistance to fire-cracks. The extensive heat treatment procedure ensures an acicular matrix. This grade can be produced by Static Casting (Monoblock) or by using the Centrifugal Cast (CC) Double-pour method.