Cast Iron is a group of iron–carbon alloys containing 2%–4% carbon, along with silicon, manganese, and controlled impurities. It is known for excellent castability, high wear resistance, superior vibration damping, and strong compressive performance.
Produced by melting iron and casting it into molds, cast iron is ideal for complex geometries and heavy-duty applications across automotive, construction, machinery, infrastructure, and energy sectors.
Major Types of Cast Iron
| Type | Graphite Form | Key Feature |
|---|---|---|
| Gray Cast Iron | Flake graphite | Excellent damping & machinability |
| Ductile (SG) Iron | Spheroidal graphite | High strength & ductility |
| White Cast Iron | Iron carbides (Fe₃C) | Extreme hardness & wear resistance |
| Malleable Cast Iron | Temper carbon | Tougher than gray iron |
| Compacted Graphite Iron (CGI) | Vermicular graphite | Strength + thermal performance |
Chemical Composition
| Element | Typical Range (%) | Function |
|---|---|---|
| Carbon (C) | 2.5 – 4.0 | Graphite / carbide formation |
| Silicon (Si) | 1.0 – 3.0 | Promotes graphite |
| Manganese (Mn) | 0.2 – 1.0 | Strength, sulfur control |
| Phosphorus (P) | 0.02 – 0.30 | Improves fluidity |
| Sulfur (S) | 0.02 – 0.15 | Controlled impurity |
| Iron (Fe) | Balance | Matrix |
Key Mechanical Properties
| Property | Typical Range |
|---|---|
| Tensile Strength | 150 – 900 MPa |
| Compressive Strength | 600 – 1,500 MPa |
| Yield Strength | 100 – 600 MPa |
| Elongation | 0 – 25% |
| Hardness | 130 – 600 HB |
| Impact Resistance | Low to High |
| Fatigue Resistance | Moderate to Excellent |
Physical Properties
| Property | Value |
|---|---|
| Density | 7.0 – 7.3 g/cm³ |
| Melting Range | 1,150 – 1,250 °C |
| Thermal Conductivity | 30 – 60 W/m·K |
| Specific Heat | ~460 J/kg·K |
| Thermal Expansion | 10 – 13 µm/m·°C |
| Damping Capacity | High |
Key Characteristics
✔ Excellent castability
✔ High compressive strength
✔ Good wear resistance
✔ Superior vibration damping
Available Forms
Sand cast components
Centrifugal cast pipes
Continuous cast bars & plates
Precision machined parts
Wear plates and liners
Applications
Engine blocks, brake discs, cylinder liners
Water & sewage pipes, manhole covers
Machine tool beds and housings
Pump, compressor & gearbox components
Crusher liners and power plant parts
Advantages
✔ Excellent castability
✔ High compressive strength
✔ Cost-effective for mass production
✔ Wide property range via grade selection
Limitations
❌ Brittle behavior (type dependent)
❌ Lower tensile strength than steel
❌ Weldability can be challenging
❌ Heavier than aluminum alloys
Why Choose Cast Iron?
Cast iron is selected when complex geometry, vibration control, wear resistance, and cost efficiency are more critical than extreme tensile strength.