7075 t6 aluminum foil
Most people meet 7075-T6 aluminum as a headline material: "aircraft-grade," "high strength," "premium." But foil is a different world. Foil is not a beam, not a plate, not a proud machined part you can hold up to the light and admire. Foil is where a metal has to prove it can behave while being extremely thin, extremely wide, and extremely unforgiving. If plate is a marathon runner, foil is a tightrope walker: a small mistake in chemistry, temper, flatness, or surface cleanliness becomes visible immediately-through buckles, edge cracks, pinholes, or unpredictable forming.
From that angle, 7075-T6 foil is less about the romance of aerospace and more about disciplined control: composition that stays inside a narrow window, rolling schedules that respect a high-strength alloy's limits, and heat treatment that delivers properties without sacrificing uniformity. It's a product that asks, bluntly, whether you can make "strong" also mean "consistent."
What makes 7075 "7075," even when it's foil
7075 is an Al-Zn-Mg-Cu alloy. Its strength comes from precipitation hardening: a carefully orchestrated sequence of solution heat treatment, quenching, and artificial aging that grows fine precipitates that impede dislocation motion. In T6 temper, 7075 is pushed toward high strength by aging to a peak-strength condition.
In foil form, though, the same strengthening mechanisms create a manufacturing paradox. The alloy wants to be strong, but strong alloys tend to be less forgiving during rolling and subsequent fabrication. That's why production of thin gauge 7075 can require especially careful control of reduction per pass, interpass anneals where applicable, lubrication, edge trimming, and tension leveling.
A lot of "foil problems" are actually "process memory." A subtle rolling defect, a local segregation band, or a contaminated surface might not matter in thick plate, but it will announce itself in foil when the gauge drops and the safety margin disappears.
Typical chemical composition (7075 aluminum alloy)
Below is the widely used composition range for 7075 per common standards such as ASTM B209 (sheet/plate) and EN 573-3 (chemical composition). Actual producer specifications may be tighter.
| Element | Typical Range (wt.%) |
|---|---|
| Zn | 5.6–6.1 |
| Mg | 2.1–2.5 |
| Cu | 1.2–1.6 |
| Cr | 0.18–0.28 |
| Fe | ≤ 0.50 |
| Si | ≤ 0.40 |
| Mn | ≤ 0.30 |
| Ti | ≤ 0.20 |
| Other (each) | ≤ 0.05 |
| Other (total) | ≤ 0.15 |
| Al | Balance |
What "T6" really implies in a foil purchase
T6 means the material has been solution heat-treated and artificially aged. In 7075, the standard concept is:
- Solution heat treatment to dissolve soluble phases into a supersaturated solid solution
- Rapid quench to retain supersaturation
- Artificial aging to precipitate strengthening phases
In foil, thermal processing isn't only a metallurgical step; it is a flatness and residual stress step. Thin gauges are sensitive to quench distortion and to slight temperature gradients. Good processors treat uniformity like a mechanical property: not just "meet tensile," but "meet tensile everywhere, without waviness."
It's also worth stating a practical point: many high-strength aluminum foils in demanding forming applications are supplied in softer tempers such as O, T4, or intermediate tempers to allow shaping, then heat treated after forming. 7075-T6 foil is typically chosen when the foil must already be high-strength in service and will not undergo severe forming, or when forming is minimal and carefully designed.
Mechanical property expectations (typical, not guaranteed)
Properties depend strongly on thickness, grain structure, and exact processing route. Standards define minimums for many product forms, but foil is often specified by agreement because extremely thin gauges behave differently than thicker sheet. Still, for context, typical 7075-T6 properties for sheet/plate are commonly in the range:
| Property | Typical Value (Room Temp) |
|---|---|
| Ultimate tensile strength | ~ 510–570 MPa |
| Yield strength (0.2%) | ~ 430–505 MPa |
| Elongation | ~ 5–11% (varies with thickness) |
| Hardness | ~ 150 HB (approx.) |
| Density | 2.81 g/cm³ |
| Electrical conductivity | ~ 33–38 %IACS (approx.) |
For foil procurement, it's smart to specify not only tensile requirements but also flatness, edge condition, burr limits, surface cleanliness, and coil set-because those are the parameters that decide whether the foil can be laminated, slit, stamped, or bonded without surprises.
Dimensions, tolerances, and surface: the foil reality
7075-T6 foil is generally considered a specialty product because pushing 7075 into very thin gauges increases the risk of:
- Edge cracking during rolling or slitting
- Pinholes and localized thin spots
- "Roping" or surface streaking that becomes visible after anodizing or bonding
- Residual stress that shows up as coil curl or warpage
When specifying, buyers often focus on thickness and mechanical properties, but for foil the "fit-for-use" metrics include:
- Thickness tolerance across width and along length
- Crown and wedge control (thickness profile)
- Surface roughness appropriate for bonding or coating
- Cleanliness limits if the foil will be adhesively bonded or diffusion bonded
- Grain direction sensitivity if any forming is involved
If the foil is intended for adhesive bonding, ask about rolling oils and cleaning methods. A high-strength alloy with a strong oxide film can bond beautifully-if the surface preparation is consistent.
Standards and implementation references
7075 chemistry is commonly aligned with EN 573-3 and ASTM alloy definitions. Product delivery and tolerances may reference:
- ASTM B209 for aluminum sheet and plate (often adapted for thinner gauges where applicable)
- EN 485 series for sheet/strip tolerances and mechanical properties (depending on region)
- AMS specifications in aerospace supply chains (often more stringent on process control and traceability)
In practice, foil procurement typically becomes a negotiated specification: thickness and temper per a standard framework, plus agreed tolerances and quality clauses tailored to gauge and end-use.
Corrosion behavior: strength has a personality
7075-T6 can be more susceptible to stress corrosion cracking than more moderate-strength alloys, especially in certain environments and stress states. In foil, the concern can appear in unexpected ways: a sharply slit edge can act like a stress concentrator; residual stresses from winding can add to service stress; and a humid, chloride-rich environment can exploit weaknesses.
If corrosion resistance is a central requirement, many designers consider tempers like T73 or T76 (overaged conditions) that trade some strength for improved stress corrosion resistance. Whether those are feasible in foil depends on availability and the intended mechanical targets, but the point remains: "T6" is not a universal good; it is a specific choice with specific consequences.
Protective strategies include cladding (not common for 7075 foil), conversion coatings, anodizing (with attention to fatigue and cracking risk in high-strength alloys), and sealing/coating systems designed for the environment.
Where 7075-T6 foil earns its keep
7075-T6 foil is usually chosen when a design wants high specific strength in a thin section and can control forming severity. Potential uses include specialty aerospace or defense components, thin high-strength shims, reinforcement layers in bonded structures, and applications where stiffness and strength per unit mass matter more than deep drawability.
The most successful applications treat the foil as a functional layer rather than a generic wrapping material. They design around grain direction, avoid sharp radii, control edge quality, and specify surface condition with the same seriousness as tensile strength.
A strong foil is only as good as its weakest meter. When you're sourcing 7075-T6 aluminum foil, it helps to think like a process engineer, not only like a materials engineer. Ask for coil-to-coil consistency data. Clarify inspection methods for pinholes and surface defects. Define acceptable edge cracks after slitting. Decide whether you need tension leveling. Confirm traceability to heat lot and temper certification. These are not administrative details; they are the difference between a foil that performs in a lab and a foil that survives production.
7075-T6 aluminum foil, seen this way, is not simply "high strength aluminum made thin." It is an agreement between metallurgy and manufacturing, written in microns and measured in repeatability. When it's done right, it feels almost paradoxical: a foil that behaves with the authority of a structural alloy-quietly, consistently, and without drama.