The 4000 Series Aluminium alloys are primarily aluminium–silicon (Al-Si) based alloys, where silicon (typically 4%–13%) is the dominant alloying element. The addition of silicon significantly alters aluminium’s melting and solidification behavior, providing excellent fluidity, lower melting temperature, improved wear resistance, and reduced thermal expansion.
Unlike many other aluminium alloy series, the 4000 series is used extensively as welding and brazing filler materials, as well as in automotive engine components, pistons, and high-temperature parts. Certain grades (such as 4032) are heat-treatable and offer enhanced mechanical strength.
Typical Chemical Composition
| Element | Content (%) |
|---|---|
| Aluminium (Al) | Balance |
| Silicon (Si) | 4.0 – 13.0 |
| Magnesium (Mg) | 0.2 – 1.3 (selected grades) |
| Copper (Cu) | ≤ 1.0 |
| Nickel (Ni) | ≤ 1.0 |
| Iron (Fe) | ≤ 0.8 |
| Others | Trace |
Mechanical & Physical Properties
(Typical ranges – vary by grade and heat treatment)
Physical Properties
Density: ~2.65 – 2.70 g/cm³
Melting Range: ~560 – 630°C
Thermal Conductivity: Good
Thermal Expansion: Lower than other aluminium alloys
Electrical Conductivity: Moderate
Mechanical Properties
Tensile Strength: 150 – 380 MPa
Yield Strength: 90 – 300 MPa
Elongation: 2 – 15%
Brinell Hardness: 45 – 120 HB
Elastic Modulus: ~70 GPa
Strengthening & Metallurgical Behavior
Role of Silicon in Aluminium
Improves fluidity during casting
Lowers melting temperature
Reduces shrinkage and cracking
Enhances wear resistance
Improves thermal stability
Heat Treatment Capability
❌ Most 4000 series alloys are non-heat-treatable
✔ Selected grades (e.g., 4032) are heat-treatable through solution treatment and ageing
Key Characteristics (Expanded)
1. Excellent Fluidity & Castability
Ideal for:
Thin-wall castings
Intricate geometries
Precision automotive parts
2. Lower Melting Point
Makes 4000 series alloys ideal for:
Brazing filler metals
Welding wire
Minimizes base metal distortion
3. Improved Wear & Abrasion Resistance
Silicon particles act as hard phases
Suitable for:
Pistons
Cylinder liners
Sliding components
4. Good High-Temperature Performance
Maintains stability under thermal cycling
Lower coefficient of thermal expansion reduces distortion
Refining & Processing Properties
Casting Performance
Low solidification shrinkage
Fine microstructure
Reduced hot cracking tendency
Weldability
Excellent when used as filler material (4043, 4047)
Produces smooth weld beads
Machinability
Moderate
Silicon increases tool wear but improves surface finish
Surface Treatment
Limited anodizing quality due to high silicon content
Suitable for coating and painting
Available Forms of 4000 Series Aluminium
Welding Wires & Rods
Brazing Sheets & Foils
Cast Components
Billets & Ingots
Machined Engine Parts
Applications of 4000 Series Aluminium
1. Welding & Brazing Industry
Filler wires (4043, 4047)
Aluminium joining applications
2. Automotive Industry
Engine pistons (4032)
Cylinder heads
Engine blocks
3. Heat Exchangers
Radiators
Condensers
HVAC systems
4. Industrial Casting Applications
Wear-resistant components
Thermal cycling parts
Advantages of 4000 Series Aluminium
Excellent castability
Lower melting temperature
Good wear resistance
Reduced shrinkage and cracking
Ideal for welding and brazing
Limitations
Lower ductility compared to 1000, 3000, and 5000 series
Limited anodizing quality
Not suitable for high-impact structural components
Standards & Specifications
ASTM: B209, B221, B547
AWS: A5.10 (welding fillers)
EN: EN 573
JIS: A4043, A4047
Why Choose 4000 Series Aluminium?
4000 Series aluminium alloys are the preferred choice where fluidity, low melting point, wear resistance, and thermal stability are critical. They are indispensable in welding, brazing, and automotive engine applications, offering reliable performance, dimensional accuracy, and excellent high-temperature behavior.