Ductile Iron (SGI)
Spheroidal-graphite (SG) iron for knuckles, calipers and housings, distinct from grey iron and CGI.
Overview
Ductile iron, also called spheroidal graphite iron (SGI or SG iron), is a cast iron in which graphite forms as spheres rather than flakes. That morphology gives useful ductility and fatigue strength, which is why it dominates steering knuckles, brake calipers, differential housings and many suspension nodes. The library's cast-iron page is grey (flake-graphite) iron; compacted-graphite iron (CGI) is a separate listing for engine blocks. Ductile iron is the toughness-oriented foundry grade — typically EN-GJS / ASTM A536 families — not grey iron and not CGI. Typical buyable form is a sand or die casting, often machined and sometimes austempered (ADI) for higher strength. It remains a recyclable iron.
Automotive Applications
Similar Materials
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.
Aluminium
Aluminium Alloy
Lightweight metallic element used extensively in automotive construction
Cast Iron
Gray Cast Iron
Traditional metal for engine blocks and brake components
Properties
Category
Type
Spheroidal Graphite Iron
Available Forms
Key Properties
- Spheroidal graphite morphology
- Ductility and fatigue vs grey iron
- Distinct from grey cast iron and CGI
- Cast then machined
- Austempered ADI grades available
- Recyclable iron