What Is 6063 Aluminum Alloy?
Chemical Composition and Alloy Design
6063 aluminum belongs to the 6xxx series aluminum alloys, where magnesium (Mg) and silicon (Si) are the primary alloying elements. These elements combine to form magnesium silicide (Mg₂Si), which enables precipitation hardening and strength development.
Typical chemical composition of 6063 aluminum alloy (wt%):
| Element | Content | Function |
|---|---|---|
| Silicon (Si) | 0.2–0.6 | Improves fluidity and forms Mg₂Si |
| Magnesium (Mg) | 0.45–0.9 | Enables age hardening |
| Iron (Fe) | ≤ 0.35 | Controlled to preserve ductility |
| Copper (Cu) | ≤ 0.10 | Slight strength improvement |
| Manganese (Mn) | ≤ 0.10 | Grain refinement |
| Chromium (Cr) | ≤ 0.10 | Controls grain growth |
| Zinc (Zn) | ≤ 0.10 | Limited to maintain corrosion resistance |
| Titanium (Ti) | ≤ 0.10 | Grain refiner |
| Others | ≤ 0.05 each / ≤ 0.15 total | Strictly limited |
| Aluminum (Al) | Balance | Base metal |
Physical and Mechanical Properties of 6063 Aluminum Alloy
Physical Properties
| Property | Value |
|---|---|
| Density | 2.70 g/cm³ |
| Thermal Conductivity (20 °C) | 201 W/m·K |
| Electrical Conductivity | ~35% IACS |
| Elastic Modulus | 69 GPa |
| Thermal Expansion | 23.4 × 10⁻⁶ K⁻¹ |
Mechanical Properties by Temper
| Temper | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) | Hardness (HB) |
|---|---|---|---|---|
| T1 | 130–160 | 95–120 | 10–14 | 40–55 |
| T5 | 160–200 | 125–155 | 8–12 | 60–75 |
| T6 | 190–240 | 160–200 | 8–12 | 60–80 |
6063 aluminum retains approximately 80% of its room-temperature strength at 100°C, with good fatigue resistance for outdoor and transportation applications. Extruded profiles show slight anisotropy, so critical load paths are typically aligned with the extrusion direction.
Corrosion Resistance and Surface Protection
6063 aluminum naturally forms a dense aluminum oxide (Al₂O₃) layer that provides strong resistance to atmospheric corrosion. When anodized, it can withstand over 1,000 hours of salt spray testing, making it suitable for architectural and marine environments.
In chloride-rich environments, thicker anodizing layers or protective coatings are recommended. Galvanic corrosion can be avoided by isolating 6063 aluminum from copper or carbon steel using gaskets or primers.
Anodizing processes include:
Sulfuric acid anodizing (Type II) for decorative finishes
Hard anodizing (Type III) for enhanced wear resistance
Color anodizing and powder coating for long-term aesthetics
Fabrication and Joining of 6063 Aluminum Alloy
Extrusion Performance
6063 aluminum is widely regarded as the industry benchmark for extrudability. It extrudes smoothly at temperatures between 450 and 550°C, allowing complex hollow and thin-wall profiles with excellent surface finish.
Key extrusion advantages include:
Lower extrusion pressure than 6061
Fine surface quality without secondary machining
High production efficiency for architectural profiles
Machining
In soft tempers, 6063 aluminum machines easily with high-speed steel tools. Carbide tools are preferred for T6 temper. Proper coolant use significantly reduces tool wear and improves surface finish.
Welding
6063 aluminum demonstrates excellent weldability:
TIG welding with 4043 filler provides high joint quality
Friction stir welding delivers near-base-metal strength
Post-weld stress relief improves dimensional stability
Heat Treatment and Age Hardening
Heat treatment transforms 6063 aluminum from a ductile as-extruded condition into a precipitation-hardened alloy.
Common tempers include:
T1: Natural aging with maximum formability
T5: Artificial aging for balanced strength and low distortion
T6: Highest strength after solution heat treatment
T7: Overaged condition for dimensional stability and stress resistance
T6 temper offers the highest mechanical strength, while T5 and T7 are often preferred for complex or welded assemblies.
Surface Treatments and Coatings
6063 aluminum responds exceptionally well to surface finishing:
Chemical conversion coatings improve paint adhesion
Powder coating (60–120 μm) enhances durability
Emerging nano-coatings offer self-cleaning and hydrophobic properties
These treatments extend service life and reduce maintenance costs.
Main Applications of 6063 Aluminum Alloy
Architectural and Construction
Window and door frames
Curtain wall systems
Railings and handrails
Transportation
Automotive trim and roof rails
Marine fittings and gangways
Bicycle frames
Electrical and Lighting
LED housings
Heat sinks
Electrical enclosures
Consumer Products
Furniture frames
Display systems
Ladders and racks
Industrial Equipment
Automation framing
Conveyor systems
Cooling system housings
Advantages and Limitations
Key advantages
Outstanding extrudability
Excellent anodizing quality
Cost-effective compared to higher-strength alloys
Limitations
Lower strength than 6061 and 7075
Strength decreases above 150°C.
Requires fire protection in critical structures
Standards and Availability
6063 aluminum alloy supplied by GNEE complies with major international standards, including ASTM B221, EN 573, ISO 6361, and JIS H4040. Products are available as extrusions, sheets, tubes, and rods, with custom profiles produced according to customer drawings.
Conclusion
6063 aluminum alloy delivers an excellent balance of formability, corrosion resistance, surface finish, and economic efficiency. From architectural facades to marine hardware and industrial systems, it remains one of the most widely used extrusion alloys worldwide.
By understanding its composition, processing methods, and performance characteristics, manufacturers can confidently select GNEE 6063 aluminum alloy to meet both functional and aesthetic requirements while maintaining cost control and long-term reliability.
