7075-T6 Aluminum
A 7000-series Al-Zn-Mg-Cu alloy, one of the strongest in common use
Typical values, T6 temper
7075 is an aluminum alloy whose main alloying element is zinc (about 5.6%), with magnesium and copper. Alcoa introduced it in 1943, and it has been the workhorse alloy of the aerospace industry ever since. In the T6 temper (artificially aged) it reaches a typical tensile strength of 572 MPa, about 1.8 times that of 6061-T6, at the density of aluminum.
The price of that strength: fusion welding is practically ruled out, general corrosion resistance is moderate, and the T6 temper is susceptible to stress corrosion cracking (SCC). Choosing 7075 is therefore mostly about choosing the right temper and the right protection.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Tensile strength Rm | 503–572 MPa | 572 typical; the range depends on product and thickness |
| Yield strength Rp0.2 | 434–503 MPa | 503 typical |
| Elongation A | 11% | |
| Hardness | 150 HB | |
| Modulus of elasticity E | 71.7 GPa | like the other aluminum alloys |
| Density ρ | 2.81 g/cm³ | |
| Melting range | 477–635 °C | |
| Fracture toughness KIc (plate, L-T) | about 28.6 MPa√m | T7351: about 32 MPa√m |
| Machinability | 70% | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| Zn zinc | 5.1–6.1 | with magnesium, forms the precipitates (MgZn₂) that give the strength |
| Mg magnesium | 2.1–2.9 | part of the strengthening precipitates |
| Cu copper | 1.2–2.0 | adds strength, but lowers corrosion resistance and weldability |
| Cr chromium | 0.18–0.28 | improves resistance to stress corrosion cracking |
| Si silicon | max 0.40 | |
| Fe iron | max 0.50 | |
| Mn manganese | max 0.30 | |
| Ti titanium | max 0.20 | |
| Others | max 0.05 each, 0.15 total | |
| Al aluminum | balance |
Common tempers
The same alloy behaves very differently depending on its heat treatment. This is the most important decision when choosing 7075.
| Temper | Rm / Rp0.2 (typical) | When to choose it |
|---|---|---|
| O (annealed) | 228 / 103 MPa, 16% elongation | for forming and bending, with heat treatment afterwards |
| T6 | 572 / 503 MPa | maximum strength; susceptible to SCC, relatively low toughness |
| T651 | as T6 | T6 stretched to relieve stress (plate and bar): less distortion when machining |
| T73 / T7351 | 505 / 435 MPa, 13% elongation | overaged: about 10–15% lower strength, much better SCC resistance. T7351 is also stretched |
| T76 | slightly below T6 | improved resistance to exfoliation corrosion, limited SCC resistance |
Applications
- Highly loaded aerospace structures: fittings, frames, wing and fuselage parts
- Defense assemblies where strength-to-weight is critical
- Plate for molds, fixtures and jigs
- Sports and racing equipment
- Highly stressed mechanical parts where weight matters
Fabrication
Machining
Machines well. Its relatively high hardness breaks the chip and gives a good finish, usually better than the softer 6061, which tends to smear. For precise or thin parts, order T651 or T7351 plate (stress relieved by stretching) to limit distortion, and work in stages: rough, pause, finish. Use sharp, positive-rake tools and good cooling.
Welding
Fusion welding (TIG, MIG) is not recommended: the alloy is prone to hot cracking, and the heat-affected zone loses much of its strength. Join with rivets, bolts or adhesives. Friction stir welding (FSW) is possible and used.
Corrosion and protection
General corrosion resistance is lower than that of 6061 because of the copper. In humid or marine environments it is usually protected: anodizing (including hard anodizing, Type III), conversion coating and paint, or Alclad sheet (clad with purer aluminum). Under sustained tensile load, mainly in the short-transverse direction of thick plate, T6 is susceptible to stress corrosion cracking; there, T73 or T7351 is the choice.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it beats 7075-T6 |
|---|---|---|---|
| 6061-T6 | 310 / 276 MPa | good (ER4043) | when you do not need the strength: weldable, more corrosion resistant and cheaper · material page |
| 2024-T4 | 470–480 / 325–345 MPa | not recommended | fatigue resistance and damage tolerance, e.g. fuselage skin · material page |
| 7050-T7451 | 496–531 / 434–469 MPa | not recommended | thick plate (50–150 mm): better SCC resistance and damage tolerance · material page |
Common mistakes
Welding 7075 like 6061
Fusion welding creates cracks and a weakened zone. If the part must be welded, the material is probably wrong.
T6 in a thick part under sustained load
In a humid environment this invites stress corrosion cracking. Choose T73 or T7351.
Replacing 6061 with 7075 to reduce deflection
The modulus is almost the same (71.7 vs 68.9 GPa). Strength goes up, stiffness does not. To reduce deflection, change the geometry.
Machining a thin part from ordinary T6 plate
Residual stresses distort it once it comes off the machine. Order T651 or T7351.
Equivalents, standards and supply
| EN | EN AW-7075, AlZn5,5MgCu |
|---|---|
| DIN / W.Nr | AlZnMgCu1.5, 3.4365 |
| UNS | A97075 |
| JIS | A7075 |
| BS / AFNOR | 2L95 / A-Z5GU |
| Standards | ASTM B209 (plate), ASTM B211 (bar), ASTM B210 (tube), EN 485-2, EN 754-2, AMS 2770 (heat treatment) |
| Forms | plate · rod · extrusion |
| Producers | Alcoa · Novelis · Constellium · UACJ · Kaiser |
Learn more
- Materials & Metallurgy course: chapter 12 Aluminum, chapter 4 Strengthening mechanisms
- Coatings course: chapter 6 Anodizing
- Glossary: Stress Corrosion Cracking
- Glossary: Anodizing
- Glossary: Friction Stir Welding
- Cutting speed → RPM calculator
- 7075-T6 in Smart Search (with comparisons)
- The full materials database
Values are typical and for comparison only. For design, rely on the standard and on the mill certificate. Sources: Aluminum Association (composition), Alcoa 7075 data sheet, ASM and MatWeb data sheets.
Updated: October 31, 2026