TYPES
Gray iron— Flake graphite provides gray iron with unique properties (such as excellent machinability) at hardness levels that produce superior wear-resistant characteristics, the ability to resist galling and excellent vibration damping.
Ductile iron— An unusual combination of properties is obtained in ductile iron because the graphite occurs as spheroids rather than as flakes. Ductile iron exhibits a linear stress-strain relationship, a considerable range of yield strengths and ductility. Castings are made in a wide range of sizes with very thin or thick sections.
Carbidic Austempered Ductile Iron (CADI)— Although not widely used, CADI combines the wear resistance of high-chromium abrasion- resistant irons with toughness.
Compacted Graphite Iron (CGI)— CGI is an alternative to both gray iron and light metals in heavily loaded applications. It combines much of the strength and stiffness of ductile iron with the thermal conductivity and castability of gray iron.
White iron— White iron is hard and essentially free of graphite. The carbides are in a matrix that may be pearlitic, ferritic, austenitic, martensitic or any combination thereof.
Malleable iron— In malleable iron, the graphite occurs as irregularly shaped nodules called temper carbon because it is formed in the solid state during heat treatment. The iron is cast as a white iron of a suitable chemical composition to respond to the malleabilizing heat treatment.
Alloyed iron— This classification includes gray irons, ductile irons, and white irons that have more than 3% alloying elements (nickel, chromium, molybdenum, silicon, or copper). Malleable irons are not heavily alloyed because many of the alloying elements interfere with the graphite-forming process that occurs during heat treatment.