Which standards apply to 6061 aluminum alloy?
6061 is a heat-treatable Al-Mg-Si (6xxx series) wrought aluminum alloy, designated as UNS A96061. It is governed by:
- ASTM B209 - Aluminum and Aluminum-Alloy Sheet and Plate
- ASTM B211 - Aluminum and Aluminum-Alloy Bar, Rod, and Wire
- ASTM B221 - Aluminum and Aluminum-Alloy Extruded Bars, Rods, Profiles, and Tubes
- ASTM B308 / B308M - 6061-T6 Standard Structural Profiles
- EN 573-3 - Chemical Composition and Form of Wrought Products
- GB/T 3190 - Wrought Aluminum and Aluminum Alloy Chemical Composition (Chinese designation: 6061, formerly LD30)
- ISO 209-1 - Wrought Aluminum and Aluminum Alloy Designation
The primary strengthening phase is Mg₂Si (magnesium silicide), precipitated during artificial aging (T6 temper). 6061 is one of the most widely used aluminum alloys worldwide due to its balanced strength, weldability, corrosion resistance, and machinability.
EN AW-6061 Equivalent Designations
The table below lists the international equivalent designations for 6061 aluminum:
| Standard System | Designation | Notes |
|---|---|---|
| Aluminum Association (AA) | AA6061 | Primary North American designation |
| UNS (Unified Numbering) | A96061 | ASTM/SAE unified system |
| EN (European) | EN AW-6061 / AlMg1SiCu | Per EN 573-3 |
| DIN (German) | 3.3211 (AlMgSi0.5Cu) | German material number |
| JIS (Japanese) | A6061 | Per JIS H4000 / H4040 |
| GB (Chinese) | 6061 (formerly LD30) | Per GB/T 3190 |
| ISO | AlMg1SiCu | Per ISO 209-1 |
Chemical Composition of 6061 T6 Aluminum (wt %) - Per ASTM B209 / GB T3190
| Element | Symbol | Min (%) | Max (%) | Role / Function |
|---|---|---|---|---|
| Silicon | Si | 0.40 | 0.80 | Forms Mg₂Si strengthening phase with Mg |
| Iron | Fe | - | 0.70 | Controlled impurity; excess reduces ductility |
| Copper | Cu | 0.15 | 0.40 | Additional solid-solution strengthening accelerates aging |
| Manganese | Mn | - | 0.15 | Grain refinement; mitigates Fe intermetallic effects |
| Magnesium | Mg | 0.80 | 1.20 | Primary strengthening element; forms Mg₂Si with Si |
| Chromium | Cr | 0.04 | 0.35 | Controls grain structure; improves stress corrosion resistance |
| Zinc | Zn | - | 0.25 | Residual impurity; limited to preserve corrosion resistance |
| Titanium | Ti | - | 0.15 | Grain refiner (Al₃Ti particles) |
| Others (each) | - | - | 0.05 | Individual trace element limit |
| Others (total) | - | - | 0.15 | Combined trace element limit |
| Aluminum | Al | Remainder (≈ 95.8 – 98.6%) | Base matrix | |
Source: ASTM B209, GB/T 3190, EN 573-3. Values are composition limits per standard; actual mill certificate values may vary within these ranges.
Mechanical Properties by Temper
6061 achieves its mechanical properties through heat treatment. The table below lists typical values per ASTM B221 / B209 for common tempers:
| Temper | UTS (MPa) | Yield 0.2% (MPa) | Elongation (%) | Hardness (HB) | Shear (MPa) | Fatigue (MPa) |
|---|---|---|---|---|---|---|
| O (Annealed) | ≤ 150 | ≤ 85 | 10 – 18 | 30 | ~84 | - |
| T4 (Solution + Natural Age) | ≥ 180 | ≥ 110 | 10 – 16 | 65 | ~110 | - |
| T6 (Solution + Artificial Age) | ≥ 290 | ≥ 240 | 8 – 12 | 95 | ~207 | ~97 |
| T651 (Stress-Relieved + Artificial Age) | ≥ 290 | ≥ 240 | 8 – 12 | 95 | ~207 | ~97 |
| F (As-Fabricated) | Not specified-properties depend on manufacturing process | |||||
Notes: UTS = Ultimate Tensile Strength. Fatigue strength values are approximate, based on 5 × 10⁸ cycles for unnotched specimens. Elongation values depend on thickness and test direction (longitudinal vs. transverse). Values per ASTM B221 minimums; actual mill test results typically exceed these.
Physical Properties of 6061 T6 Aluminum (Typical Values, All Tempers)
| Property | Value | Unit | Notes |
|---|---|---|---|
| Density (ρ) | 2.70 | g/cm³ | ~1/3 of steel; identical across all tempers |
| Melting Range | 582 – 652 | °C (1,080 – 1,205 °F) | Solidus 582°C, liquidus 652°C |
| Elastic Modulus (E) | 68.9 | GPa (10,000 ksi) | Young's modulus: consistent across tempers |
| Shear Modulus (G) | 25.9 | GPa (3,750 ksi) | - |
| Poisson's Ratio (ν) | 0.33 | - | - |
| Specific Heat (cₚ) | 896 | J/(kg·K) | At 20°C |
| Electrical Conductivity (T6) | 43 | % IACS | Lower than pure aluminum (6101 ~57%) |
| Electrical Resistivity (T6, 20°C) | 3.99 × 10⁻⁸ | Ω·m | - |
Source: ASM Handbook Vol. 2, ASTM B209, Aluminum Association Standards & Data.
Thermal Properties of 6061 T6 Aluminum Plate
| Property | 20°C | 100°C | 200°C | 300°C | 400°C |
|---|---|---|---|---|---|
| Thermal Conductivity (W/m·K) | 167 † | - | - | - | - |
| CTE (μm/m·°C) | - | 23.6 | 24.5 | 25.6 | 26.6 |
| Thermal Diffusivity (m²/s × 10⁻⁵) | 6.69 | - | - | - | - |
† Thermal conductivity of 167 W/m·K applies to T6 temper. In O temper, conductivity is higher (~180 W/m·K) due to fewer precipitates scattering electrons. CTE values represent average coefficients over the range 20°C to the indicated temperature.
Heat Treatment & Temper Guide
6061 is a heat-treatable alloy - its mechanical properties are achieved through controlled thermal cycles rather than cold working. The table below summarizes common tempers and their applications:
| Temper | Process | Characteristics | Typical Use |
|---|---|---|---|
| F | As-fabricated, no thermal control | Properties not guaranteed | Non-critical applications |
| O | Fully annealed | Lowest strength, maximum formability | Deep drawing, complex forming |
| T4 | Solution heat-treated + naturally aged | Moderate strength, good formability | Parts requiring post-forming aging |
| T6 | Solution heat-treated + artificially aged | Peak strength, good overall performance | Structural components, machined parts |
| T651 | Solution + stress-relieved by stretching (1–3%) + artificially aged | Low residual stress, excellent dimensional stability | Precision-machined plates, tooling |
The Product Specification of 6061 Aluminum Sheet Plate
|
Alloy |
6061 aluminum sheet plate |
|
Temper |
F,O,T4,T6,T651,etc. |
|
Thickness (mm) |
0.30-500 |
|
Width (mm) |
500-2650 |
|
Length (mm) |
500-16000 |
|
Package |
Export packaging (protective film, interleaved paper) |
Solution Heat Treatment Temperature of 6061 Aluminum Sheet Plate
For 6061 aluminum, the solution heat treatment temperature is 530°C ± 5°C (985°F ± 10°F), followed by immediate water quenching. Artificial aging for T6 temper is performed at 175°C ± 5°C (350°F ± 10°F) for 8 hours.
Important: After welding, the heat-affected zone (HAZ) reverts to near-annealed (O temper) condition. To restore T6 properties, re-solution treatment at 530°C + re-aging at 175°C is required. Without re-heat treatment, the HAZ typically retains only ~40–50% of T6 strength.
Corrosion Resistance of 6061 Aluminum Sheet Plate
- General atmospheric corrosion: 6061 forms a stable, protective Al₂O₃ oxide film that provides good resistance in most atmospheric environments. Performance is adequate for outdoor architectural and structural use.
- Marine environments: 6061 is not the optimal choice for continuous seawater exposure. In chloride-rich environments, pitting and crevice corrosion can occur. For marine applications, 5052 or 5083 (5xxx series) offer superior resistance.
- Galvanic corrosion: When 6061 is in contact with more noble metals (e.g., stainless steel, copper, titanium) in the presence of an electrolyte, 6061 acts as the anode and corrodes preferentially. Proper electrical isolation (nylon washers, gaskets) or protective coatings should be used at dissimilar-metal joints.
- Stress corrosion cracking (SCC): 6061-T6 has good resistance to SCC in most environments, particularly in the T651 condition where residual stresses are minimized. Chromium (0.04–0.35%) in the composition specifically enhances SCC resistance.
- Surface treatments: Anodizing (Type II sulfuric or Type III hardcoat), chromate conversion coating (Alodine), powder coating, and PVDF coating all improve corrosion resistance and aesthetics.
Fabrication and Processing
Welding
6061 has excellent weldability using MIG (GMAW) and TIG (GTAW) processes. Recommended filler metals are ER4043 (Si-based, lower crack sensitivity) or ER5356 (Mg-based, higher strength). ER4043 is preferred for general welding; ER5356 provides higher weld strength and better color match after anodizing.
Note: Welding reduces strength in the HAZ to near-O temper levels (~150 MPa UTS). Post-weld solution heat treatment + aging can restore T6 properties.
Machinability
6061-T6 has excellent machinability - rated "A" by the Aluminum Association. It produces short, free-breaking chips and supports high cutting speeds. T6 and T651 tempers machine significantly better than O temper (which tends to be gummy and produces long chips). Carbide tooling is recommended for production runs.
Formability
Formability depends heavily on temper. O temper offers maximum formability (suitable for deep drawing and complex bending). T4 temper can be formed with moderate radii. T6 temper has limited formability and requires larger bend radii (typically 5–6 × thickness for 90° bends) to avoid cracking.
Surface Finishes Available from GNEE
| Finish | Description | Typical Application |
|---|---|---|
| Mill Finish | Natural as-rolled surface | Structural, industrial, non-decorative |
| Anodized (Type II) | Sulfuric anodizing, 10–25 μm | Architectural, consumer electronics |
| Anodized (Type III) | Hardcoat anodizing, 25–75 μm | Wear surfaces, military, automotive |
| Brushed / Polished | Mechanical finish (#4 satin, #6, #7 mirror) | Decorative panels, architectural trim |
| Powder Coated | Electrostatic spray, RAL colors | Outdoor equipment, building facades |
| PVDF Coated | 70% PVDF fluorocarbon, 20+ year warranty | Architectural cladding, curtain walls |
Applications of 6061 Aluminum Sheet
6061 aluminum sheet plate is used across a wide range of industries where medium-to-high strength, good weldability, and corrosion resistance are required:
- Automotive: Chassis components, body panels, battery trays and enclosures (EV), heat exchangers, truck and trailer frames
- Aerospace: Secondary structural fittings, wing ribs, fuselage frames (non-primary structure)
- Electronics: Mobile phone cases, laptop housings, heat sinks, EMI shielding enclosures
- Marine: Deck hardware, railings, small boat hulls (with appropriate coating)
- Industrial: Hydraulic and pneumatic fittings, valve bodies, machine guards, fixtures
- Tooling: Precision molds, jigs, CNC fixture plates, welding tables
- Architecture: Structural frames, curtain wall components, signage and display systems
- Containers: ISO container panels, transport containers, storage tanks
Need 6061 Aluminum Sheet Plate for Your Project?
GNEE supplies 6061 aluminum sheet and plate in all tempers (O, T4, T6, T651), thicknesses from 0.30 mm to 500 mm, with full mill test certificates. Custom cutting, surface treatment, and export packaging available.
6061 vs. 5052 vs. 7075 vs. 6063: Key Differences
| Property / Feature | 5052 | 6061 | 6063 | 7075 |
|---|---|---|---|---|
| Series | 5xxx (Al-Mg) | 6xxx (Al-Mg-Si) | 6xxx (Al-Mg-Si) | 7xxx (Al-Zn-Mg-Cu) |
| Heat-Treatable | No | Yes | Yes | Yes |
| Typical Temper | H32 / H34 | T6 / T651 | T5 / T6 | T6 / T651 |
| UTS (MPa, typical) | ~190 | ~310 | ~240 | ~570 |
| Yield (MPa, typical) | ~140 | ~275 | ~215 | ~500 |
| Elongation (%) | 7 – 12 | 8 – 12 | 8 – 12 | 7 – 11 |
| Relative Cost | Low | Low | Lowest | High |
| Primary Use | Marine, fuel tanks | General structural, machined parts | Architectural extrusions, frames | Aerospace, high-stress parts |
