6061 aluminum sheet is the most versatile and widely specified aluminum alloy in the world. As a heat-treatable alloy in the 6xxx magnesium-silicon series, it combines high strength with excellent machinability, good corrosion resistance, and reliable weldability—making it the default choice for structural applications, machined components, automotive parts, and general engineering.
The T6 temper (solution heat treated and artificially aged) delivers optimal mechanical properties for load-bearing applications, while the T651 temper adds stress relief by stretching to ensure flatness in plate form. From aerospace structures to bicycle frames, 6061 aluminum sheet is trusted across industries for its consistent performance, ease of fabrication, and cost-effectiveness.
Table of Contents
What is 6061 Aluminum Sheet?
6061 aluminum sheet is a versatile, heat-treatable alloy in the 6xxx (Al-Mg-Si) series, known for its excellent combination of strength, corrosion resistance, machinability, and weldability. It is the most widely used aluminum alloy across industries worldwide.
This alloy responds well to solution heat treatment and artificial aging, achieving significantly higher strength than non-heat-treatable alloys. The T6 and T651 tempers are most common, offering optimal mechanical properties for structural applications, machined parts, automotive components, and general engineering use. 6061 is often considered the "structural alloy" of choice when high strength, good corrosion resistance, and ease of fabrication are required.
Chemical Composition
| Element | Weight % |
|---|---|
| Magnesium (Mg) | 0.8 – 1.2 |
| Silicon (Si) | 0.4 – 0.8 |
| Copper (Cu) | 0.15 – 0.40 |
| Chromium (Cr) | 0.04 – 0.35 |
| Iron (Fe) | ≤ 0.7 |
| Zinc (Zn) | ≤ 0.25 |
| Titanium (Ti) | ≤ 0.15 |
| Manganese (Mn) | ≤ 0.15 |
| Others (each) | ≤ 0.05 |
| Others (total) | ≤ 0.15 |
| Aluminum (Al) | Remainder |
The Mg₂Si precipitates formed during aging provide the primary strengthening mechanism.
Mechanical Properties
6061 aluminum properties vary significantly with heat treatment. The O (annealed) temper is soft and formable, while T6 and T651 (artificially aged) offer high strength for structural use.
| Temper | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) |
|---|---|---|---|
| O (Annealed) | ≤ 150 (typ. 125) | ≤ 85 (typ. 55) | 16 – 25 |
| T4 (Naturally aged) | ≥ 205 (typ. 240) | ≥ 110 (typ. 145) | 16 – 22 |
| T6 (Artificially aged) | ≥ 290 (typ. 310) | ≥ 240 (typ. 275) | 8 – 12 |
| T651 (T6 + stretched) | ≥ 290 (typ. 310) | ≥ 240 (typ. 275) | 8 – 12 |
Limits per ASTM B209; "typ." values from the ASM Handbook. Elongation depends on thickness. T651 is stress-relieved by stretching (1–3% permanent set) for flatness.
Physical Properties
| Property | Value |
|---|---|
| Density | 2.70 g/cm³ |
| Melting Range | 582 – 652 °C |
| Thermal Conductivity (25°C, T6) | 167 W/m·K |
| Electrical Conductivity (T6) | 43% IACS |
| Elastic Modulus | 68.9 GPa |
| Shear Strength (T6) | 205 MPa |
| Fatigue Strength (T6, 500M cycles) | 95 MPa |
Heat Treatment Process
6061 aluminum gains its strength through solution heat treatment followed by artificial aging:
- Solution Heat Treatment: Heat to about 530°C (985°F), hold to dissolve Mg₂Si, then rapidly water quench.
- Artificial Aging (T6): Age at 160°C (320°F) for about 18 hours, or 175°C (345°F) for about 8 hours. This precipitates fine Mg₂Si particles that strengthen the alloy.
- Natural Aging (T4): After quenching, allow to age at room temperature for several days. Provides moderate strength with better formability than T6.
- Stress Relieving (T651): Stretch the T6 material by 1-3% permanent set to relieve residual stress and improve flatness. Common for plate.
Key Characteristics
- High Strength-to-Weight Ratio: T6 temper offers structural strength comparable to mild steel at one-third the weight.
- Good Machinability: In T6/T651 condition it machines cleanly with good surface finish; the O temper is gummy and machines poorly.
- Good Corrosion Resistance: Performs well in most environments; better than mild steel, though not as resistant as 5xxx series in marine conditions.
- Weldable: Can be welded using TIG, MIG, and resistance welding with ER4043 or ER5356 filler, but the heat-affected zone loses much of its T6 strength.
- Excellent Anodizing Response: Produces bright, uniform anodized finishes. Widely used for architectural and decorative applications.
- Good Formability in O Temper: Can be formed, bent, and deep drawn in annealed condition before heat treating.
Common Applications
- Structural components: frames, beams, supports
- Automotive and transportation: chassis, body panels, structural parts
- Aircraft fittings and secondary structures
- Marine: boat hulls, masts, superstructures
- Machined parts: fittings, fasteners, valve bodies, pneumatic components
- Bicycle frames and sporting goods
- Architectural applications: window frames, storefront systems
- Electrical enclosures and chassis
- Tooling and jigs
Comparison with Other Alloys
| Property | 6061-T6 | 6063-T6 | 7075-T6 |
|---|---|---|---|
| Strength | High | Medium | Very High |
| Machinability | Excellent | Good | Good |
| Weldability | Good | Excellent | Fair |
| Corrosion Resistance | Good | Good | Fair |
| Formability (O temper) | Good | Excellent | Fair |
| Typical Use | Structural, machined parts | Extrusions, architectural | Aerospace, high-stress |
6061 offers the best all-around balance of strength, weldability, and corrosion resistance. 7075 is stronger but less weldable. 6063 is more formable but weaker.
Welding Considerations
6061 aluminum can be welded using standard fusion welding processes, but the heat-affected zone (HAZ) loses strength due to dissolution of strengthening precipitates:
- Filler Alloy Selection: ER4043 (Al-Si) offers good fluidity and crack resistance; ER5356 (Al-Mg) provides higher strength and better color match after anodizing.
- HAZ Strength Loss: The heat-affected zone is partly over-aged/annealed. AWS D1.2 uses a minimum as-welded tensile strength of 165 MPa for 6061-T6, roughly 55–60% of the base metal.
- Post-Weld Heat Treatment: Full T6 properties can be restored by solution heat treating and re-aging the entire assembly after welding.
- Joint Design: Use larger fillet welds or increased material thickness to compensate for HAZ strength loss if post-weld heat treatment is not feasible.
- Preheat: Not required for most thicknesses. Keep interpass temperature below 150°C.
Weight Reference
| Thickness (mm) | Weight (kg/m²) | 1220 × 2440 mm sheet (kg) | 1250 × 2500 mm sheet (kg) |
|---|---|---|---|
| 0.5 | 1.35 | 4.02 | 4.22 |
| 1 | 2.70 | 8.04 | 8.44 |
| 1.5 | 4.05 | 12.06 | 12.66 |
| 2 | 5.40 | 16.07 | 16.88 |
| 3 | 8.10 | 24.11 | 25.31 |
| 4 | 10.80 | 32.15 | 33.75 |
| 5 | 13.50 | 40.19 | 42.19 |
| 6 | 16.20 | 48.22 | 50.63 |
| 8 | 21.60 | 64.30 | 67.50 |
| 10 | 27.00 | 80.37 | 84.38 |
| 12 | 32.40 | 96.45 | 101.25 |
| 20 | 54.00 | 160.75 | 168.75 |
Weight (kg) = thickness (mm) × width (m) × length (m) × density (g/cm³). Theoretical values; actual weight varies within thickness tolerance.
Supply Specifications
Thickness Range: 0.3 mm – 300 mm
Width: Up to 2600 mm
Length: Up to 12000 mm (plate) or coil
Tempers Available: O, T4, T6, T651 (plate)
Standards: ASTM B209, EN 485, GB/T 3880
Surface Finish: Mill finish, PE film protected
Certification: Mill test certificate (EN 10204 3.1)
International Equivalent Grades
| Standard | Designation |
|---|---|
| AA / ASTM | 6061 |
| UNS | A96061 |
| EN | AlMg1SiCu / EN AW-6061 |
| ISO | Al-Mg1SiCu |
| JIS | A6061 |
| GB (China) | 6061 / LD30 |
Frequently Asked Questions
What is the difference between 6061 T6 and T651?
6061-T6 is solution heat treated and artificially aged. 6061-T651 undergoes the same T6 treatment, then is stress-relieved by stretching 1-3% to improve flatness and dimensional stability. T651 is typically specified for plate (thickness ≥6.3mm), while T6 is used for sheet. Both have the same mechanical properties.
Can 6061 aluminum be welded?
Yes, 6061 can be welded using TIG, MIG, and resistance welding. However, the heat-affected zone (HAZ) loses much of its T6 strength (as-welded minimum about 165 MPa per AWS D1.2). Use filler alloy ER4043 or ER5356. Post-weld heat treatment can restore full T6 properties if needed.
Is 6061 aluminum good for machining?
Yes. In T6 and T651 tempers, 6061 machines well at high cutting speeds with clean surface finishes, which is why it is widely used for CNC parts, fixtures and plates. The soft O temper is gummy and is not recommended for machining.
Can 6061 aluminum be anodized?
Yes, 6061 anodizes well and produces bright, uniform finishes suitable for both decorative and functional (corrosion protection) purposes. It is widely used in architectural and consumer product applications requiring anodized surfaces.
What is the weight of 6061 aluminum sheet?
The weight of 6061 aluminum sheet is calculated as: thickness (mm) × width (m) × length (m) × 2.70 (g/cm³). For example, a 5mm × 1220mm × 2440mm sheet weighs approximately 40.2 kg.
Related Grades
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