Cast Aluminium refers to aluminium and aluminium-based alloys shaped by pouring molten metal into moulds, where it solidifies into near-net-shape components.
This process allows complex geometries, thin walls, internal cavities, and intricate surface details that are difficult or costly to achieve with wrought aluminium. Cast aluminium combines lightweight properties with good mechanical strength, corrosion resistance, excellent thermal conductivity, and cost efficiency.
Chemical Composition & Alloying Elements
| Element | Role in Cast Aluminium |
|---|---|
| Silicon (Si) | Improves fluidity, reduces shrinkage, enhances castability |
| Magnesium (Mg) | Increases strength and enables heat treatment |
| Copper (Cu) | Improves strength and hardness |
| Iron (Fe) | Improves die release; excess reduces ductility |
| Zinc (Zn) | Enhances strength in selected alloys |
| Manganese (Mn) | Improves corrosion resistance |
Typical silicon content ranges from 5–12%, which gives cast aluminium excellent flow into moulds.
Mechanical & Physical Properties
| Property | Typical Value |
|---|---|
| Density | 2.65 – 2.75 g/cm³ |
| Melting Range | 560 – 700 °C |
| Tensile Strength | 120 – 250 MPa (up to 320 MPa T6) |
| Yield Strength | 60 – 250 MPa |
| Elongation | 1 – 12% |
| Hardness | 50 – 110 HB |
| Thermal Conductivity | High |
| Corrosion Resistance | Excellent |
Major Cast Aluminium Alloys
| Alloy | Key Features | Typical Uses |
|---|---|---|
| A356 / AlSi7Mg | Heat-treatable, good ductility | Wheels, structural parts |
| A380 | Excellent die-casting alloy | Automotive housings |
| ADC12 | High strength, smooth finish | Engine & electronics parts |
| LM6 | Excellent corrosion resistance | Marine components |
| LM25 | High strength after heat treatment | Aerospace & automotive |
Casting Methods
✔ Sand Casting – large and complex components
✔ Die Casting (HPDC) – high precision, mass production
✔ Gravity Die Casting – improved mechanical properties
✔ Investment Casting – very high precision and detail
Heat Treatment
✔ T5 – Artificially aged after casting
✔ T6 – Solution treated, quenched & aged
✔ T7 – Over-aged for stability
Available Forms
✔ Finished cast components
✔ Semi-finished castings
✔ Cast aluminium ingots
✔ Custom & OEM castings
Industry Applications
✔ Automotive & EV components
✔ Industrial machinery & pumps
✔ Electrical & electronics heat sinks
✔ Aerospace & defense parts
✔ Marine fittings
✔ Construction & architectural hardware
✔ Consumer & household products
Advantages
✔ Complex near-net-shape designs
✔ Lightweight with good strength
✔ Excellent corrosion resistance
✔ High thermal conductivity
✔ Cost-effective production
✔ Highly recyclable
Limitations
⚠ Lower ductility than wrought aluminium
⚠ Porosity risk if casting is poorly controlled
⚠ Mechanical properties depend on casting quality
Cast Aluminium offers an optimal balance of performance, manufacturability, and cost. Its versatility and reliability make it indispensable across automotive, industrial, electrical, marine, and consumer sectors worldwide.