Compacted Graphite Iron (CGI)
Vermicular-graphite iron for modern engine blocks, distinct from grey cast iron.
Overview
Compacted graphite iron (CGI) has a vermicular graphite morphology between grey iron and ductile iron. It is the modern diesel and some high-output petrol engine-block material, offering higher strength and stiffness than grey iron at similar castability. The library's Cast Iron page is grey iron (and mentions ductile) for blocks, heads and brake discs. CGI is a distinct foundry grade, specified where peak cylinder pressure needs more than grey iron without jumping to aluminium. It is cast and machined and fully recyclable in the iron stream. It is not the default brake-disc material — those remain grey iron — and it is not a wrought steel.
Automotive Applications
Similar Materials
Aluminium
Aluminium Alloy
Lightweight metallic element used extensively in automotive construction
Aluminium-SiC MMC
Metal Matrix Composite
Aluminium metal-matrix composite reinforced with silicon carbide, used for brake discs, drums and pistons.
Aluminium-Silicon Casting Alloys
Al-Si Casting Alloy
Al-Si casting alloys such as A356 and AlSi10Mg for engines, gearboxes and additive aluminium parts.
Brass / Copper Alloys
Copper Alloy
Brass and copper-alloy strip and rod for busbars, terminals and connectors, distinct from pure copper.
Properties
Category
Type
Compacted Graphite Iron
Available Forms
Key Properties
- Vermicular graphite morphology
- Higher strength than grey iron
- Engine-block foundry grade
- Distinct from Cast Iron (grey)
- Cast and machinable
- Iron-stream recyclable