The most widely machined aluminum alloy in the world. 6061-T6 combines excellent machinability with moderate strength, superb corrosion resistance, and predictable anodizing behavior — making it the default choice for enclosures, brackets, fixtures, and structural parts.
6061 is a precipitation-hardened aluminum alloy whose primary alloying elements are magnesium and silicon. These combine during heat treatment to form Mg₂Si precipitates, which give 6061 its characteristic strength in the T6 temper.
The "-T6" designation is the key: it means the alloy has been solution heat-treated and artificially aged, bringing it to peak mechanical properties. 6061-T6 is roughly three times stronger than annealed 6061, but its machinability stays excellent — unlike high-strength aerospace alloys where hardness comes at the cost of cutting tool life.
6061-T6 is the Swiss Army knife of machinable metals. It's:
6061-T6 is not the strongest aluminum — if you need higher tensile strength and don't need to weld or anodize, 7075-T6 gives you roughly 2× the yield strength. But 6061 is usually the right default unless you have a specific reason to choose otherwise.
| Element | Min (%) | Max (%) | Role in alloy |
|---|---|---|---|
| Aluminum (Al) | 95.8 | 98.6 | Base metal |
| Magnesium (Mg) | 0.80 | 1.20 | Principal strengthener (with Si) |
| Silicon (Si) | 0.40 | 0.80 | Forms Mg₂Si precipitates |
| Iron (Fe) | — | 0.70 | Impurity, reduced ductility above max |
| Copper (Cu) | 0.15 | 0.40 | Minor strength contributor |
| Chromium (Cr) | 0.04 | 0.35 | Improves stress corrosion resistance |
| Manganese (Mn) | — | 0.15 | Grain refinement |
| Titanium (Ti) | — | 0.15 | Grain refinement during casting |
| Zinc (Zn) | — | 0.25 | Impurity |
| Others, each | — | 0.05 | — |
| Others, total | — | 0.15 | — |
| Property | Metric | Imperial | Test method |
|---|---|---|---|
| Ultimate tensile strength | 310 MPa | 45,000 psi | ASTM E8 |
| Yield strength (0.2% offset) | 276 MPa | 40,000 psi | ASTM E8 |
| Elongation at break | 12–17% | 12–17% | ASTM E8 |
| Modulus of elasticity | 68.9 GPa | 10 × 10⁶ psi | ASTM E111 |
| Shear strength | 207 MPa | 30,000 psi | ASTM B769 |
| Fatigue endurance (5×10⁸ cycles) | 96.5 MPa | 14,000 psi | ASTM E466 |
| Hardness | 95 HB | 60 HRB | ASTM E10 / E18 |
| Density | 2.70 g/cm³ | 0.0975 lb/in³ | ASTM B311 |
| Melting range | 582–652 °C | 1,080–1,205 °F | — |
| Thermal conductivity | 167 W/m·K | 1,160 BTU·in/hr·ft²·°F | ASTM E1461 |
| Electrical conductivity | 43% IACS | 43% IACS | ASTM E1004 |
| Coefficient of thermal expansion | 23.6 μm/m·°C | 13.1 × 10⁻⁶ /°F | ASTM E831 |
Starting values for uncoated carbide tooling on rigid machining centers (Haas VF, DMG MORI DMC). Adjust 10–20% based on tool condition, fixturing rigidity, and coolant flow. TiAlN-coated tools can typically run 15–25% faster.
| Operation | SFM (m/min) | Feed per tooth | Depth of cut | Coolant |
|---|---|---|---|---|
| Face mill, roughing | 1,000–1,500 (305–457) | 0.20–0.40 mm (0.008–0.016") | 2–5 mm axial | Flood or MQL |
| End mill, roughing (Ø6–16 mm) | 800–1,200 (244–366) | 0.10–0.20 mm (0.004–0.008") | 0.5 × D axial | Flood |
| End mill, finishing | 1,200–1,800 (366–549) | 0.05–0.10 mm (0.002–0.004") | 0.1 × D axial | Air blast |
| Slot milling | 600–900 (183–274) | 0.08–0.15 mm (0.003–0.006") | 0.3 × D axial | Flood |
| Drilling (HSS-Co, Ø1–10 mm) | 80–120 (24–37) | 0.10–0.30 mm/rev | — | Through-tool |
| Tapping (M3–M12) | 20–40 (6–12) | Pitch / rev | — | Cutting fluid |
| Turning, rough (carbide insert) | 300–600 (91–183) | 0.20–0.40 mm/rev | 2–5 mm | Flood |
| Turning, finish (carbide insert) | 600–900 (183–274) | 0.05–0.15 mm/rev | 0.1–0.5 mm | Flood or mist |
6061-T6 produces continuous chips that can wrap on the tool and cause crashes or poor finish. Use polished-flute end mills with high helix (45° or more) for best chip evacuation. Avoid climbing milling ramps — prefer helical entry or pre-drilled pilot holes for pockets.
"Standard" tolerances are included in our default pricing. "Precision" tolerances trigger additional inspection and may increase cost 15–40%. "Ultra-precision" usually requires grinding or additional finishing passes.
| Feature | Standard | Precision | Ultra-precision |
|---|---|---|---|
| Linear dimensions | ±0.1 mm (±0.004") | ±0.025 mm (±0.001") | ±0.005 mm (±0.0002") |
| Hole diameter, drilled | +0.1 / 0 mm | H8 (~+0.022 mm) | H7 (~+0.015 mm) |
| Hole diameter, reamed | H8 | H7 | H6 |
| Flatness (per 100 mm) | 0.1 mm | 0.02 mm | 0.005 mm |
| Parallelism | 0.1 mm | 0.02 mm | 0.005 mm |
| Perpendicularity | 0.1 mm | 0.025 mm | 0.005 mm |
| Concentricity | 0.1 mm TIR | 0.025 mm TIR | 0.01 mm TIR |
| Surface roughness (Ra) | 3.2 μm (125 μin) | 0.8 μm (32 μin) | 0.2 μm (8 μin) |
| Angular tolerance | ±0.5° | ±0.1° | ±0.05° |
| Thread pitch (metric) | 6H | 6G | 4H |
If your drawing has a tight tolerance on every dimension, you're overpaying. Standard ISO 2768-m tolerances are sufficient for ~85% of CNC parts. Apply tight tolerances only to features that actually need them — mating surfaces, bearing bores, locating datums. See our tolerance guide for the full breakdown.
Industrial controller housings, RF shielding boxes, server-rack brackets, instrumentation chassis. 6061 anodizes to a uniform finish that both protects and communicates "professional hardware."
Mounting plates, linkage arms, gripper bodies, sensor brackets. When strength-to-weight matters more than absolute strength, 6061 beats steel every time.
Fluid distribution manifolds up to 3,000 psi (pneumatic) and 2,000 psi (hydraulic). 6061's weldability allows fitting-to-body joins for complex flow geometries.
Fixtures, tooling, ground support equipment, and non-flight structural elements per AMS 4027. For flight-critical aerospace parts, 7075-T651 or 2024-T3 is typically specified.
Camera rigs, tripod mounts, lens adapters, optical table components. Type II black anodize is the de facto finish for this category.
Extruded or machined heat sinks for power electronics, EV battery cold plates, LED luminaire bodies. 6061's 167 W/m·K thermal conductivity is a key driver here.
| Alloy | Tensile | Yield | Elong. | Corrosion | Weldable | Cost |
|---|---|---|---|---|---|---|
| 6061-T6 | 310 MPa | 276 MPa | 12% | Excellent | Yes | $ |
| 7075-T6 | 572 MPa | 503 MPa | 11% | Fair | No (hot cracking) | $$ |
| 2024-T3 | 483 MPa | 345 MPa | 18% | Poor (needs clad) | Difficult | $$ |
| 5052-H32 | 228 MPa | 193 MPa | 12% | Excellent (marine) | Yes | $ |
| 6063-T6 | 241 MPa | 214 MPa | 12% | Excellent | Yes | $ |
| MIC-6 (cast plate) | 172 MPa | 145 MPa | 3% | Good | Limited | $$ |
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