Cast Irons: Graphite Shape Controls Behaviour
Understand why flakes, nodules and compacted graphite produce very different engineering properties.
More than high-carbon steel
Cast irons contain enough carbon and silicon to promote graphite or carbide formation during solidification and cooling.
Graphite morphology
Flake graphite gives excellent damping and machinability but concentrates stress. Spheroidal graphite greatly improves ductility and toughness.
Matrix control
Ferritic, pearlitic, bainitic or martensitic matrices set strength and wear response around the graphite population.
Processing sensitivity
Inoculation, magnesium treatment, cooling rate and section size control nodule count, chill tendency and matrix structure.
Engineering takeaway
Specify graphite morphology, matrix and defect acceptance together; the generic label cast iron is not enough.