What is the difference between 7075 and 7005 aluminum?
The main difference between 7075 and 7005 aluminum is that 7075 has higher strength, making it more suitable for high-performance applications, while 7005 is easier to weld and is commonly used in bicycle frames and automotive components.
7075 is a high-strength alloy with excellent performance, making it suitable for aerospace, military, and structural applications, but its weldability is poor. On the other hand, 7005 has better weldability, is more cost-effective, and is ideal for bicycle frames, automotive parts, and other structures that require good strength and toughness as well as weldability.
7075 and 7005 Aluminum Key Differences
| Feature | 7075 Aluminum | 7005 Aluminum |
| Strength | Higher strength, steel-like | Lower strength than 7075, good toughness |
| Composition | High zinc (5-6%), magnesium, copper | Lower zinc, magnesium |
| Weldability | Poor (not suitable for welding) | Good (weldable) |
| Applications | Aerospace, military, high-performance sporting equipment | Bicycle frames, automotive, large heat exchangers |
| Workability | Difficult to machine and process | Easier to machine and weld |
| Cost | More expensive | Less expensive |
7075 vs. 7005 Strength and Hardness
- 7075 Aluminum: 7075 is recognized as one of the strongest aluminum alloys, with strength similar to steel, making it ideal for applications that require extremely high strength. Its hardness is significantly higher than that of 7005, offering greater durability and wear resistance. It is commonly used in aerospace, military, and high-performance sports equipment, where strength is crucial.
- 7005 Aluminum: While 7005 is still strong, its strength is lower than that of 7075. However, it has good toughness and high fracture resistance, making it suitable for applications that require a certain degree of flexibility and impact resistance.
7075 and 7005 Aluminum Weldability
- 7075 Aluminum: This alloy is not suitable for welding because the heat-affected zone (HAZ) often weakens significantly after welding. This is due to its high zinc content, which causes the material to lose strength during the heating process in welding. Therefore, 7075 is typically used in applications that do not require welding or those that need special welding techniques and heat treatment processes.
- 7005 Aluminum: Unlike 7075, 7005 can be effectively welded. It is specifically used in applications that require welding, such as the construction of bicycle frames or automotive components. Its lower zinc content makes it less sensitive to heat, improving its weldability.
7075 and 7005 Aluminum Mechanical Properties Comparison
7075 aluminum has poorer machinability due to its higher zinc content, and the zinc makes it less weldable. This characteristic means that it is often used in components for CNC machines.
| Property | 7005 Aluminum | 7075 Aluminum |
| Elastic (Young's, Tensile) Modulus (GPa) | 70 | 70 |
| Elongation at Break (%) | 10 - 20 | 1.8 - 12 |
| Fatigue Strength (MPa) | 100 - 190 | 110 - 190 |
| Poisson's Ratio | 0.33 | 0.32 |
| Shear Modulus (GPa) | 26 | 26 |
| Shear Strength (MPa) | 120 - 230 | 150 - 340 |
| Tensile Strength: Ultimate (UTS) (MPa) | 200 - 400 | 240 - 590 |
| Tensile Strength: Yield (Proof) (MPa) | 95 - 350 | 120 - 510 |
7075 and 7005 Aluminum Thermal Properties Comparison
| Property | 7005 Aluminum | 7075 Aluminum |
| Latent Heat of Fusion (J/g) | 380 | 380 |
| Maximum Temperature: Mechanical (°C) | 200 | 200 |
| Melting Completion (Liquidus) (°C) | 640 | 640 |
| Melting Onset (Solidus) (°C) | 610 | 480 |
| Specific Heat Capacity (J/kg-K) | 880 | 870 |
| Thermal Conductivity (W/m-K) | 140 - 170 | 130 |
| Thermal Expansion (µm/m-K) | 23 | 23 |
7075 and 7005 Aluminum Electrical Properties Comparison
| Property | 7005 Aluminum | 7075 Aluminum |
| Electrical Conductivity: Equal Volume (% IACS) | 35 - 43 | 33 |
| Electrical Conductivity: Equal Weight (% IACS) | 110 - 130 | 98 |
7075 and 7005 Aluminum Alloy Composition Comparison
- 7075 Aluminum: This alloy contains a high amount of zinc (about 5-6%) and magnesium, along with some copper. Zinc is the primary alloying element, helping to improve its strength and corrosion resistance. The higher zinc content in 7075 gives it significantly higher strength compared to 7005 but also makes it less weldable.
- 7005 Aluminum: This alloy has a lower zinc content than 7075 but still contains magnesium and small amounts of other elements, such as silicon. The reduced zinc content results in slightly lower strength but also enhances its weldability.
| Element | 7005 Aluminum (%) | 7075 Aluminum (%) |
| Aluminum (Al) | 91 - 94.7 | 86.9 - 91.4 |
| Chromium (Cr) | 0.060 - 0.2 | 0.18 - 0.28 |
| Copper (Cu) | 0 - 0.1 | 1.2 - 2.0 |
| Iron (Fe) | 0 - 0.4 | 0 - 0.5 |
| Magnesium (Mg) | 1.0 - 1.8 | 2.1 - 2.9 |
| Manganese (Mn) | 0.2 - 0.7 | 0 - 0.3 |
| Silicon (Si) | 0 - 0.35 | 0 - 0.4 |
| Titanium (Ti) | 0.010 - 0.060 | 0 - 0.2 |
| Zinc (Zn) | 4.0 - 5.0 | 5.1 - 6.1 |
| Zirconium (Zr) | 0.080 - 0.2 | 0 - 0.25 |
| Residuals | 0 | 0 - 0.15 |
7075 and 7005 Aluminum Applications
- 7075 Aluminum: Due to its excellent strength, 7075 is commonly used in critical aerospace applications, including aircraft structures, engine components, and satellite parts. It is also used in high-performance automotive components and military equipment. Its high strength-to-weight ratio makes it an ideal choice for situations where both strength and lightness are crucial.
- 7005 Aluminum: This alloy is commonly used in products that require a combination of strength, weldability, and impact resistance. Typical applications include the manufacture of bicycle frames, automotive parts, structural components, and large heat exchangers. Its weldability makes it suitable for products where welded joints are essential.
