7075-T6 Aluminum Aerospace Alloy Technical Material Specification
Complete technical specification for 7075-T6 aluminum alloy, covering properties, Canadian stock sizing, machinability, common defects, and storage guidelines for fabrication and machining operations.
Material Overview & Common Uses
7075-T6 is a precipitation-hardened aluminum alloy with zinc as the primary alloying element. It offers the highest strength of any commercially available aluminum alloy, comparable to many steels, while maintaining excellent fatigue resistance and good machinability. The T6 temper indicates solution heat-treated and artificially aged, providing maximum strength. Common applications include aerospace structural components (wing spars, fuselage frames, bulkheads), high-performance automotive parts (suspension components, connecting rods), bicycle frames, rock climbing equipment, and precision tooling jigs. In Canadian fabrication shops, it is frequently used for CNC-machined parts requiring high strength-to-weight ratio, such as drone frames, robotic arms, and defense components. Note: 7075-T6 has lower corrosion resistance than 6061-T6 and is not recommended for marine or chemical exposure without protective coating.
Core Technical Properties & Sizing
| Property | Value |
|---|---|
| Density | 2.81 g/cm³ (0.101 lb/in³) |
| Tensile Strength (Ultimate) | 572 MPa (83,000 psi) |
| Tensile Strength (Yield) | 503 MPa (73,000 psi) |
| Elongation at Break | 11% (in 50 mm) |
| Modulus of Elasticity | 71.7 GPa (10,400 ksi) |
| Shear Strength | 331 MPa (48,000 psi) |
| Fatigue Strength | 159 MPa (23,000 psi) at 5e8 cycles |
| Hardness | Brinell 150, Rockwell B 87 |
| Thermal Conductivity | 130 W/m·K |
| Electrical Resistivity | 5.74e-6 ohm·cm |
| Coefficient of Thermal Expansion | 23.6 µm/m·°C (20-100°C) |
| Melting Range | 477-635°C (890-1175°F) |
| Machinability Rating | 70% (relative to 2011-T3 at 100%) |
| Weldability | Poor (not recommended for fusion welding; friction stir welding possible) |
| Corrosion Resistance | Fair (susceptible to stress corrosion cracking under sustained tensile stress) |
| Standard Canadian Sheet Sizes (thickness tolerance ±0.005" for 0.032"-0.125") | 0.032", 0.040", 0.050", 0.063", 0.080", 0.090", 0.100", 0.125" |
| Standard Canadian Plate Sizes (thickness tolerance ±0.010" for 0.250"-0.500") | 0.250", 0.375", 0.500", 0.625", 0.750", 1.000" |
| Common Sheet/Plate Dimensions | 48" × 96" (4'×8'), 48" × 120" (4'×10'), 60" × 120" (5'×10') |
| Standard Bar Stock (rectangular, tolerance ±0.005") | 1/4" × 1", 1/4" × 2", 1/2" × 1", 1/2" × 2", 1" × 2", 1" × 3" |
| Standard Round Bar (diameter tolerance ±0.002") | 1/4", 3/8", 1/2", 5/8", 3/4", 1", 1-1/4", 1-1/2", 2", 2-1/2", 3" |
| Standard Hex Bar (across flats tolerance ±0.005") | 1/4", 3/8", 1/2", 5/8", 3/4", 1" |
| Typical Sheet Flatness | 0.010" per foot (can be tighter on precision ground plate) |
Machinability, Tooling & Feeds
7075-T6 has good machinability (70% rating) but requires sharp tooling and rigid setups due to its hardness. It produces small, broken chips (similar to brass) which are easy to evacuate.
| Operation | Parameter | Recommended Value |
|---|---|---|
| Turning | Tooling | Carbide inserts (C2 or C3 grade) |
| Turning | Cutting Speed | 300–500 SFM (90–150 m/min) |
| Turning | Feed | 0.005–0.015 IPR (0.13–0.38 mm/rev) |
| Turning | Depth of Cut | 0.050–0.200" (1.3–5.1 mm) |
| Milling | Tooling | Carbide inserts (C2 or C3 grade) |
| Milling | Cutting Speed | 600–1000 SFM (180–300 m/min) |
| Milling | Feed | 0.002–0.006 IPT (0.05–0.15 mm/tooth) |
| Milling | Radial Depth of Cut | 0.020–0.100" (0.5–2.5 mm) |
| Drilling | Tooling | 135° split-point carbide drills |
| Tapping | Tooling | Spiral point taps, 2–3 flute design; pre-drill to 75% thread depth |
| Coolant | Type | Water-soluble or mist to prevent built-up edge |
| Surface Finish | Standard tooling | 32–63 microinches Ra |
| Surface Finish | Wiper inserts | 16 microinches Ra |
| Stress Relief (critical parts) | Cryogenic treatment | −320°F for 24 hours after rough machining |
Common Defects & Quality Control
| Defect | Description | Detection / Rejection Criteria |
|---|---|---|
| Stress Corrosion Cracking | Occurs under sustained tensile stress in corrosive environments | Do not exceed 50% of yield stress in service; inspect with dye penetrant |
| Exfoliation Corrosion | Layered corrosion along grain boundaries | Inspect with dye penetrant or eddy current |
| Porosity | Gas pockets from casting; visible as small pits on machined surfaces | Reject if pits >0.010" diameter |
| Inclusions | Non-metallic particles causing tool chipping | Detect with ultrasonic testing |
| Laminations | Internal separations in plate, visible on cut edges | Reject if >0.005" wide |
| Warpage | From residual stress relief during machining | Control by roughing and stress relieving before finishing |
| Surface Scratches / Gouges | From handling | Depth limit 0.003" for aerospace applications |
Quality Control: Verify temper with conductivity meter (26–30% IACS for T6); check hardness (Rockwell B 85–90); perform tensile test per ASTM B209; inspect dimensions with calibrated micrometers and CMM; flatness check on surface plate with feeler gauge. For critical parts, require mill test report (MTR) with heat number and chemical analysis.
Storage, Handling & Racking Guidelines
- Store in a dry, indoor environment with relative humidity below 50% to prevent corrosion.
- Do not store directly on concrete floors – use wooden pallets or plastic dunnage to avoid moisture wicking.
- Rack sheet and plate vertically in A-frame racks with padded supports (rubber or plastic) to prevent scratching. Maximum rack load: 500 lbs per linear foot for 0.125" sheet, 1000 lbs for 0.500" plate.
- Bar stock should be stored horizontally on cantilever racks with protective sleeves or paper wrap.
- Separate by alloy and temper to avoid mix-ups – use color-coded tags (red for 7075-T6).
- Implement FIFO (first-in, first-out) rotation; label each bundle with heat number, date received, and thickness.
- For long-term storage (>6 months), apply a light coat of corrosion-preventive oil (e.g., LPS-3) and wrap in VCI (vapor corrosion inhibitor) paper.
- Inspect monthly for signs of corrosion or mechanical damage.
- Do not stack sheet directly on top of each other without interleaving paper or plastic film to prevent galling.
- For CNC shops, maintain a dedicated aluminum storage area away from steel and stainless steel to prevent contamination from iron particles.