Aerospace structures
Brackets, ribs, fittings, instrument enclosures. Anodized for corrosion protection and traceability.
Aluminum · Wrought · UNS A96061
Aluminum 6061-T6
The general-purpose aluminum. Easy to machine, weld, and anodize, with the best balance of strength, corrosion resistance, and cost in the wrought aluminum family. If a part doesn't have a reason to be something else, it's probably 6061.
UTS
310 MPa
Density
2.70 g/cc
Modulus
68.9 GPa
Mach.
90 /100
When to use
Pick 6061 when there’s no specific reason not to.
The "T6" condition means solution heat-treated and artificially aged — the standard temper for structural use. 6061-T6 has the best machinability of common structural aluminums (slightly better than 7075), takes anodizing beautifully, and welds with 4043 or 5356 filler.
Step up to 7075 when you need higher strength (UTS 572 MPa vs 310). Step over to 2024 for fatigue-critical aerospace skins. Step down to MIC-6 cast plate for stable optical fixtures. For most everything else, 6061-T6 is the answer.
Strengths
Why it's the default.
- Machinability 90/100Cuts fast and clean with sharp tools. Cycle times often 1/3 of stainless.
- AnodizableType II clear and color, Type III hardcoat. Cosmetic and functional finishes both available.
- WeldableTIG with 4043 or 5356 filler. Loses ~30% of T6 strength in HAZ — design around it or post-heat-treat.
- Corrosion-resistantForms a passive oxide. Anodizing improves it further.
- CostRoughly half the price of stainless and about 1/10 the price of titanium per pound.
- Wide stock availabilityBar, plate, sheet, extrusions in every size from anywhere in the U.S.
Trade-offs
Where it's not enough.
- Strength ceiling310 MPa UTS — about 1/3 of 17-4PH stainless. Not for highly loaded steel-replacement parts.
- High-temp limitsT6 properties degrade above 150 °C. For elevated temp, look at 2618 or step up to titanium.
- Galling on threadsAluminum-on-aluminum galls badly. Use steel inserts (Helicoil) for repeated removal.
- Welding penaltyHAZ drops to ~T4 strength (~210 MPa). Critical joints need post-weld solution + age.
- Galvanic corrosionPairs poorly with steel and stainless in wet environments — use isolation washers.
Specs
Mechanical, physical & chemical data.
Typical values for 6061-T6 wrought bar per ASTM B221. T651 is the same temper, stress-relieved by stretching — preferred for plate where dimensional stability matters during machining.
Mechanical
Properties (T6)
| Ultimate tensile strength | 310 MPa (45 ksi) |
|---|---|
| Yield strength (0.2% offset) | 276 MPa (40 ksi) |
| Elongation at break | 12 – 17% |
| Modulus of elasticity | 68.9 GPa |
| Shear modulus | 26 GPa |
| Shear strength | 207 MPa |
| Poisson's ratio | 0.33 |
| Hardness | 95 HB (≈60 HRB) |
| Fatigue strength 5 × 10⁸ cycles | 97 MPa |
T651 (stretched) has equivalent strength but better residual-stress profile for thin-wall machining.
Physical & thermal
Properties at room temp
| Density | 2.70 g/cc (0.0975 lb/in³) |
|---|---|
| Melting range | 582 – 652 °C |
| Specific heat | 0.896 J/g·°C |
| Thermal conductivity | 167 W/m·K |
| CTE (20–100 °C) | 23.6 µm/m·°C |
| Electrical conductivity | 43% IACS |
| Magnetic | Non-magnetic |
Thermal conductivity 25× higher than Ti-6Al-4V — heat flows out through the chip and the part.
Composition
Chemistry, weight %
| Magnesium (Mg) | 0.8 – 1.2 |
|---|---|
| Silicon (Si) | 0.4 – 0.8 |
| Iron (Fe) | 0.7 max |
| Copper (Cu) | 0.15 – 0.40 |
| Chromium (Cr) | 0.04 – 0.35 |
| Manganese (Mn) | 0.15 max |
| Zinc (Zn) | 0.25 max |
| Titanium (Ti) | 0.15 max |
| Aluminum (Al) | balance (≥95%) |
Strengthening is from Mg₂Si precipitates that form during the artificial aging step.
Specifications
Common purchase specs.
ASTM B221
Extruded bar, rod, profiles
ASTM B209
Sheet, plate
AMS 4117
Bar, rod, wire — T6/T651
AMS-QQ-A-200/8
Bar, rod, profiles — T6
AMS-QQ-A-250/11
Sheet, plate — T6
MIL-A-22771
Forgings
AA 6061
Aluminum Association designation
EN AW-6061
European equivalent
Machining
How we cut it.
6061 cuts fast — the trick is chip control and surface finish. Sharp positive-rake tools, high RPM, generous coolant, and good chip evacuation are the four rules.
Cutting speed
1,500 – 3,500 SFM with carbide. Limited mostly by spindle speed and chip evacuation.
Feed rate
Aggressive. 6061 doesn't work-harden — keep it cutting.
Tooling
Polished, uncoated carbide for finishing. Diamond-coated (DLC) for high-volume.
Coolant
Flood with light oil or air-blast for high-speed roughing. Some shops run dry with MQL.
Chip control
Plan for it. Long stringy chips wrap fast. Chipbreaker geometry on inserts.
Drill speeds
Roughly 4× steel. Through-tool coolant for deeper holes.
Threading
Roll forms preferred over taps — stronger threads, no chips. Cut taps work fine for low volume.
Surface finish
Easy to hold 32 µin Ra. Sub-16 µin needs sharp finishing tool + light DOC + climb mill.
Applications
Where 6061 shows up.
Robotics & automation
Frame extrusions, end-of-arm tooling, sensor mounts, motor brackets — anywhere stiffness-to-weight beats raw strength.
Optics & instrumentation
Optical breadboards, camera housings, microscope fixtures. T651 plate's stress relief is critical for thin-wall stability.
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