7075 Aluminum Coil

First, 7075 aluminum alloy core characteristics

7075 belongs to the Al-Zn-Mg-Cu ultra-high strength aluminum alloy (7xxx series), known for its extremely high strength and hardness, and is the "ace alloy" in the aerospace and military fields. Its core features are as follows:

1. Chemical composition (typical value)

Zn (Zinc) : 5.1-6.1% - the main strengthening element

Mg (Magnesium) : 2.1-2.9% - forms a strengthening phase with Zn

Cu (Copper) : 1.2-2.0% - improved strength and heat resistance

Other: Residual Al, containing trace Cr (0.18-0.28%) to control the grain.

2. Physical properties

Density: 2.81 g/cm³ (slightly higher than the 2.7 g/cm³ of pure aluminum)

Melting point: about 635°C

Electrical conductivity: approximately 33% IACS (significantly lower than 1xxx/6xxx series)

Thermal expansion coefficient: 23.6×10⁻⁶/K (close to steel, suitable for composite structure).

3. Mechanical properties (after T6 heat treatment)

Typical performance indicators

Tensile strength (UTS) 500-570 MPa

Yield strength (YS) 430-480 MPa

Elongation (%) 5-10%

Hardness (HB) 150-175

4. Strengths and weaknesses

Advantages:

Very high specific strength (strength/density ratio close to titanium alloy);

Excellent fatigue resistance and wear resistance;

It still maintains high strength at high temperatures (short-term use temperature ≤120°C).

Weaknesses:

Poor corrosion resistance (need surface coating protection, such as anodizing or plating);

The processing is difficult (good cutting performance but plastic forming is difficult);

High stress corrosion sensitivity (requires strict heat treatment control).

Second, 7075 aluminum coil processing and specifications

7075 aluminum coil is produced by hot-cold rolling combined process. Due to high alloy strength and large deformation resistance, it has strict requirements on equipment and technology.

1. Production process flow

Melting casting: strictly control the ratio of Zn, Mg and Cu to avoid segregation;

Homogenizing annealing: 480°C for 24 hours to eliminate internal stress;

Hot rolling: 400-450°C rolling to medium thick plate (thickness 5-50mm);

Cold rolling: multi-pass rolling (need intermediate annealing), final thickness 0.5-6mm;

Aging treatment: T6 state requires 120°C artificial aging for 24 hours.

2. Typical specifications

Thickness range: 0.5mm-50mm (cold rolled coil common 0.5-6mm, hot rolled coil 6-50mm);

Width range: 500mm-2500mm (custom roll required);

Roll weight: 1-8 tons (limited by material density and equipment).

3. Material status

O state (annealed state) : soft state, elongation up to 12%, easy to deep stamping;

T6 state (peak aging) : highest strength, but lowest plasticity;

T73/T76 state: over-aged treatment, sacrificing some strength to improve stress and corrosion resistance.

Third, 7075 aluminum coil core application areas

7075 aluminum coil is mainly used in extreme working conditions of high strength and light weight, typical applications include:

1. Aerospace

Aircraft skin, wing spars, landing gear components;

Rocket fuel storage tank, satellite structure frame.

2. Military equipment

Armored vehicle bulletproof plate (need composite ceramic layer);

Firearms components (e.g., sniper rifle cartridges).

3. High-end industry

Precision mold substrate (instead of steel);

High speed centrifuge rotor, hydraulic cylinder.

4. Sports equipment

Bicycle frame, mountaineering equipment (heat treatment to reduce weight);

Racing transmission components (e.g. gearbox housing).

Fourth, 7075 aluminum coil vs other high-strength aluminum alloy comparison

Features 7075 Aluminum Coil (T6) 2024 Aluminum Coil (T3) 6061 Aluminum Coil (T6)

Tensile strength (MPa) 500-570 430-480 290-310

Yield strength (MPa) 430-480 290-345 240-270

Elongation (%) 5-10 10-20 8-12

Poor corrosion resistance (coating required) (better than 7075)

Typical uses aviation structure, military aircraft skin, rivet machinery parts, ship structure

The cost is high (about 2-3 times of 6061) and medium low

5. Use precautions and market suggestions

Processing difficulty

Cold rolling cracking: the rolling temperature and the reduction rate need to be precisely controlled;

Poor weldability: riveting or bonding is recommended, and welding requires a special process (such as friction welding);

Stress concentration sensitive: Avoid sharp notch design, need rounded corner transition.

Material selection suggestion

The T73 state is preferred (if stress corrosion resistance is required);

Alternative: For slightly lower strength requirements, consider 7050 aluminum coils (improved corrosion resistance).

Market supply

7075 aluminum coil is mostly produced by military grade suppliers (such as Alcoa, RusAL);

The civil market requires proof of compliance (e.g. AMS standard for aviation materials).

Cost control

The use of near-net forming processes (such as precision stamping) to reduce machining allowance;

Recycled materials should be used with caution (impurities can easily lead to performance deterioration).

Vi. Summary

7075 aluminum coil is the preferred material for the pursuit of extreme strength-weight ratio, suitable for aviation, military and other high value-added fields;

It is necessary to support strict processing technology and surface protection measures, and the cost is significantly higher than that of ordinary aluminum alloy;

In non-extreme conditions, alternative alloys with slightly lower strength but easier to process (such as 2024, 6063) can be considered.