EN AW-7075 (AlZn5.5MgCu): An Aerospace Grade High Strength Aluminium Alloy
Alloy Definition and Chemical Composition
EN AW-7075 is one of the materials with the highest mechanical strength among the 7xxx series aluminium alloys. This alloy has been formulated to be suitable for precipitation hardening, especially with the additions of zinc (Zn), magnesium (Mg) and copper (Cu). 7075 is generally preferred as an alternative to steel in applications requiring a high strength-to-weight ratio.
Its typical chemical composition (% by weight):
- Aluminium (Al): Balance
- 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), Silicon (Si): Max. 0.5 – 0.4%
- Manganese, Titanium: In trace amounts
The high strength of this alloy is obtained through precipitation hardening and temper operations such as T6 or T73.
EN AW-7075 Standards and Specifications
EN AW-7075 has been defined in many international norms:
- EN 573-3 – Chemical composition
- EN 485-2 / EN 755-2 – Mechanical properties (sheet, profile)
- EN 515 – Temper classifications
- ASTM B209 / B221
- UNS A97075
- DIN 3.4365
- AMS 4045 / AMS 4078 / AMS 4339 – (aerospace grade)
Temper codes:
- T6: Solution treated and artificially aged (maximum hardness)
- T73: Temper with increased resistance to temperature
- T651: Stress relieved, plate form
EN AW-7075 Trade Names and Equivalents
- EN AW-7075
- AlZn5.5MgCu
- AA7075
- UNS A97075
- DIN 3.4365
- Ergal 7075 (especially in the European aerospace sector)
EN AW-7075 Mechanical and Physical Properties
T6 temper — characteristic mechanical properties:
- Tensile Strength (Rm): 510 – 580 MPa
- Yield Strength (Rp0.2): 430 – 500 MPa
- Elongation (A50): 7 – 10%
- Density: 2.81 g/cm³
- Modulus of Elasticity: 71.7 GPa
- Hardness (Brinell): ~150 HB
- Melting Point: 477 – 635 °C
- Thermal Conductivity: 130 – 160 W/m·K
- Fatigue Strength: High (especially in the T73 temper)
This alloy offers one of the highest strength levels in the aluminium family and provides performance rivalling that of steel.
Application Areas
EN AW-7075 finds a broad area of use in applications requiring extreme strength together with lightness:
1.Aerospace Industry
#Aircraft fuselage fittings
#Landing gear components
#Helicopter rotor systems
2.Defence and Ballistic Systems
#Lightweight armour plates
#Weapon parts and frames
3.Automotive and Motorsport
#Suspension components
#Wheels, chassis reinforcements
4.Bicycle and Sports Equipment
#High performance bicycle frames
#Climbing equipment and carabiners
5.Mould and Machine Parts
#High strength mould plates
#CNC machined high precision parts
Advantages
- Superior Strength / Weight Ratio: With this property it is preferred instead of steel in the aerospace sector.
- Good Machinability: It provides excellent CNC machinability especially in the T6 temper
- Suitability for Heat Treatment: Properties can be customised with temper operations.
- High Fatigue Strength: It provides long-term performance under dynamic load.
Disadvantages
- Poor Corrosion Resistance: Because of the copper content in particular, it needs to be protected against atmospheric and galvanic corrosion. It is generally supported with alodine coating or anodising.
- Poor Weldability: It is not suitable for MIG/TIG welding. A loss of strength occurs after welding.
- High Price: It is more expensive than other aluminium alloys; consequently it is preferred only in applications requiring high performance.
Conclusion and Engineering Evaluation
EN AW-7075 is an ideal solution for situations in engineering applications where strength is the most critical parameter. It stands out as a strategic material especially in sectors such as aerospace, defence and motorsport, thanks to offering performance close to steel at a much lower weight.
Alongside the expectation of high performance, however, limiting factors such as corrosion resistance and weldability should be assessed carefully. These limitations can be overcome with the correct temper selection, surface treatments and joining methods. Ultimately 7075 is an alloy that is indispensable in high cost but critical projects where high engineering expectations are met.
#ENAW7075
#AMSQQ-A-250/12
#AMSQQ-A-225/9
#AMS4078
#AMS4124
#ASTMB209
#ASTMB211
#AIR9048-690
#3.4364
| Chemical Composition | % Value | Physical Properties | % Value | Mechanical Properties | Value |
|---|---|---|---|---|---|
| Silicon (Si) | 0,00 – 0,40 | Density | 2.81 g/cm³ | Yield Strength | 410 MPa |
| Tin (Sn) | 0,00 – 0,00 | Melting Point | 477 °C | Tensile Strength | 510 MPa |
| Chromium (Cr) | 0,18 – 0,28 | Coeff. of Thermal Expansion | 23 x 10^-6 /K | Shear Strength | 300 MPa |
| Manganese (Mn) | 0,00 – 0,30 | Modulus of Elasticity | 72 GPa | Elongation | 8% |
| Magnesium (Mg) | 2,10 – 2,90 | Heat Capacity | 155 W/m.K | Elasticity | 72 GPa |
| Copper (Cu) | 1,20 – 2,00 | Electrical Conductivity | 33% IACS | | |
| Lead (Pb) | 0,00 - 0,00 | | | ||
| Titanium (Ti) | 0,00 – 0,20 | | | ||
| Iron (Fe) | 0,00 – 0,50 | | | ||
| Zinc (Zn) | 5,10 – 6,10 | | | ||
| Nickel (Ni) | 0,00 – 0,00 | | | ||
| Aluminium (Al) | Balance | | | ||
| Titanium + Zirconium (Ti+Zr) | 0,00 - 0,25 | | |
We supply this material
We supply EN AW 7075 (3.4365) — to AMS 4045, AMS 4078 standards, in the dimensions and forms required. For stock availability and pricing:
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