GRAPHITE STRUCTURES IN CAST IRONS : GRAPHITE DISTRIBUTION IN GREY CAST IRON

GRAPHITE DISTRIBUTION IN GREY CAST IRON

TYPE A Random flake graphite in a uniform distribution
TYPE B Rosette flake graphite

GRAPHITE STRUCTURES IN CAST IRONS: GRAPHITE SIZES IN DUCTILE IRON

Diagrammatic representations of the standard graphite nodule sizes in ductile

iron at x100 magnification(Form VI)

(Click image to enlarge)

GRAPHITE STRUCTURES IN CAST IRONS: GRAPHITE SIZES IN GREY CAST IRON

GRAPHITE SIZES IN GREY CAST IRON



Diagrammatic representations of the standard flake graphite sizes in grey cast iron at
x100 magnification (Form I Distribution A)

(Click image to enlarge)

GRAPHITE STRUCTURES IN CAST IRONS: GRAPHITE FORMS

GRAPHITE FORMS

Diagrammatic representations of the standard graphite forms in cast irons.

(Click image to enlarge)

 Table1: Graphite forms

Form	Description of the form	Main spatial characteristics	Occurrence
I	Lamellar (flake) graphite	Interconnected particles within eutectic cells; lamellar (flake) graphite with sharp ends	·  Principal form in grey cast iron ·  Austenitic cast iron with lamellar/flake graphite ·  Can occur in the rim zone of other cast-iron materials
II	Crab graphite	Aggregate of graphite flakes	·  Can occur in rapidly cooled hypereutectic grey cast irons ·  Can also occur in segregation areas of thick-walled spheroidal-graphite cast-iron castings
III	Compacted (vermicular) Graphite	Usually interconnected particles within eutectic cells; worm-like appearance with rounded ends	·  Principal form in compacted-graphite cast irons ·  Can occur in spheroidal graphite cast irons
IV	Temper carbon Irregular spheroidal graphite*	Isolated particles	Principal form in malleable cast irons
			Can occur on spheroidal-graphite cast iron
V	Slightly irregular spheroidal Graphite	Isolated particles	·  Principal form in thick-walled castings made of spheroidal graphite cast irons ·  Occurs to a specified extent in compacted-graphite cast irons ·  Can occur in malleable cast irons
VI	Spheroidal graphite*	Isolated particles	·  Principal form in castings made of spheroidal-graphite cast irons ·  Occurs to a specified extent in compacted-graphite cast irons

Note: *Spheroidal graphite is sometimes referred to as nodular graphite

Classification of Cast Iron

Classification of Graphite in the Microstructure of Cast Iron

CAST IRON is an iron-carbon cast alloy with other elements that is made by remelting pig iron, scrap, and other additions. For differentiation from steel and cast steel, cast iron is defined as a cast alloy with a carbon content (min 2.03%) that ensures the solidification of the final phase with a eutectic transformation. Depending on chemical specifications, cast irons can be nonalloyed or alloyed. The range of alloyed irons is much wider, and they contain either higher amounts of commoncomponents, such as silicon and manganese, or special additions, such as nickel, chromium, aluminum, molybdenum, tungsten, copper, vanadium, titanium, plus others.

Graphitic cast irons including those that contain small amount s of alloying elements are classified as gray, ductile and malleable according to graphite shape and method of graphite production. More highly alloyed graphitic and white irons are classified by their used requirements as abrasion resistant, corrosion resistant and heat resistant.