Aerospace aluminum · UNS A97075

Aluminum 7075-T6

The high-strength aerospace aluminum. Zinc as the primary alloying element pushes 7075-T6 to ~85% higher tensile strength than 6061-T6 — at a small density penalty. Standard for airframes, weapon platforms, bike frames, and high-stress aluminum applications.

UTS
572 MPa
Density
2.81 g/cc
Modulus
71.7 GPa
Mach.
70 /100

When to use

Pick 7075 when 6061 isn’t strong enough — and weight still matters.

7075-T6 has a yield strength of 503 MPa (73 ksi) — roughly twice 6061-T6. That’s why it’s the default for primary aircraft structures: wing skins, fuselage frames, bulkheads, and load-carrying brackets. It’s also the bicycle-frame and aluminum-firearm-frame standard.

The catches: less corrosion resistance than 6061, much harder to weld (zinc-magnesium alloys are crack-sensitive), and roughly 60% more expensive per pound. The T651 temper is identical strength to T6 but stress-relieved by stretching — strongly preferred for plate that will be machined into thin-wall parts.

Strengths

Why aerospace specifies it.

  • Strength rivals mild steel
    UTS 572 MPa is comparable to 1018 cold-drawn steel — at ⅓ the weight.
  • Excellent fatigue
    Endurance limit ~159 MPa at 5×10⁸ cycles. Standard for cyclically loaded airframe parts.
  • Anodizes well
    Type II clear and color, Type III hardcoat. Corrosion protection + cosmetic finish.
  • Machinability 70/100
    Slightly worse than 6061 — chips break differently — but still very fast cutting.
  • Forgings widely available
    Major aerospace forging stock material. Parts with grain flow and properties forgings provide.

Trade-offs

What 6061 does better.

  • Corrosion resistance
    Stress-corrosion cracking susceptibility in T6. T73 and T7351 tempers exist for SCC-prone applications, at lower strength.
  • Welding
    Generally not weldable — heat-affected zone cracks. Mechanical fasteners only. (T6 specifically; weldable variants exist with sub-strength joints.)
  • Cost
    ~60% more than 6061 per pound. Multi-axis machined airframe parts often start as plate, with high scrap rates.
  • Anodizing color depth
    T6 produces darker anodize than 6061 due to copper content. Cosmetic appearance differs across batches.
  • Heat-soak limits
    T6 properties degrade above 120 °C (250 °F). For elevated temp, look at 2618 or step up to titanium.

Specs

Mechanical, physical & chemical data.

Mechanical

Properties (T6)

Ultimate tensile strength572 MPa (83 ksi)
Yield strength (0.2% offset)503 MPa (73 ksi)
Elongation at break11%
Modulus of elasticity71.7 GPa
Shear modulus26.9 GPa
Shear strength331 MPa
Poisson's ratio0.33
Hardness150 HB (~87 HRB)
Fatigue strength5 × 10⁸ cycles, R = -1159 MPa

T651 (stretch-relieved) values are equivalent. T7351 trades ~10% strength for stress-corrosion resistance.

Physical & thermal

Properties at room temp

Density2.81 g/cc (0.102 lb/in³)
Melting range477 – 635 °C
Specific heat0.960 J/g·°C
Thermal conductivity130 W/m·K
CTE (20–100 °C)23.4 µm/m·°C
Electrical conductivity33% IACS
MagneticNon-magnetic

Thermal conductivity ~80% of 6061 — slightly less heat dissipation, otherwise machines very similarly.

Composition

Chemistry, weight %

Zinc (Zn)5.1 – 6.1
Magnesium (Mg)2.1 – 2.9
Copper (Cu)1.2 – 2.0
Chromium (Cr)0.18 – 0.28
Iron (Fe)0.50 max
Silicon (Si)0.40 max
Manganese (Mn)0.30 max
Titanium (Ti)0.20 max
Aluminum (Al)balance (~90%)

The Zn-Mg-Cu system gives the strength; the copper is also the reason 7075 is less corrosion-resistant than copper-free aluminums.

Specifications

Common purchase specs.

AMS 4045
Sheet, plate — T651
AMS 4078
Plate — T7351 (overaged)
AMS 4126
Forgings — T6
AMS 4124
Bar, rod, wire — T7351 (rolled or cold finished)
ASTM B221
Extruded bar, rod, profiles
ASTM B211
Bar, rod, wire — rolled or cold finished
MIL-A-22771
Forgings — T6 and T73
EN AW-7075
European equivalent

Machining

Machining considerations.

7075 cuts almost as easily as 6061 — chips break a little stringier, but with sharp tools it’s a non-issue. The bigger machining concern is residual stress in plate stock. Always specify T651 for thin-wall machined parts.

Cutting speed
1,200 – 3,000 SFM with carbide. Slightly less than 6061 — chip control favors moderate speeds.
Feed rate
Aggressive. Same rules as 6061 — keep the chip continuous.
Tooling
Polished uncoated carbide for finishing. PCD for high-volume.
Coolant
Flood, light oil. Some shops run dry with MQL on smaller parts.
Use T651 for plate
Stretch-relieved plate machines straight. Non-relieved plate (T73 or T6) springs after machining.
Watch deep pockets
Aluminum's high CTE + machining heat can warp thin-wall pockets. Roughing pass + cool-down + finish pass.
Threading
Roll forms preferred. Cut taps work but a thread insert is bulletproof in 7075 for repeated assembly.
Surface finish
Easy to hold 32 µin Ra. 16 µin needs a sharp finishing tool and light DOC.

Applications

Where 7075 shows up.

Primary aerospace structure

Wing skins, fuselage frames, bulkheads, longerons, ribs. The default for load-bearing aircraft aluminum.

Defense & weapons

Rifle and pistol frames, tactical mounts, military hardware. The strength and weight balance 4140 can’t match.

Sporting & precision

High-end bicycle frames, rock-climbing hardware, precision optics mounts. Where stiffness-to-weight is the dominant requirement.

Compare

Related materials.

General purpose

6061-T6 →

Easier to machine, weld, and corrosion-resist — at ~half the strength.

Higher specific strength

Ti-6Al-4V →

Higher absolute strength + better corrosion + temperature capability — at higher cost.

Strength + cost

4140 Steel →

More strength, much cheaper, much heavier. Only when weight isn’t critical.

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Tell us about your part and we'll get back to you promptly. Aerospace, medical, defense, and semiconductor production work welcome.Email CAD models and drawings to sales@digitalmachine.com, including ITAR, EAR, CUI and AS9100 work. Keep controlled technical data out of web forms.

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