Density
Aluminium has the same density. But because these are alloys made by adding other metals with different densities, the density of the alloy will change. Density is one of the most essential characteristics to consider when comparing the physical properties of metals.
7075 aluminium has a density of 2.81g/cm3, which is higher than that of pure aluminium. The alloy can also be strengthened using heat treatment processes, with the most common temper being 7075-T6.
6061 aluminium has a density of 2.7 g/cm3. It is about the same as pure aluminium metal, largely because of the high amount of aluminium the alloy contains.
Mechanical Properties
The alloys also have different mechanical properties with varying compositions in types and concentrations of alloying elements.
| Type 6061 Aluminium | Type 7075 Aluminium | |||
| Metric | English | Metric | English | |
| Yield strength | 276 MPa | 40,000 psi | 503 MPa | 73,000 psi |
| Modulus elasticity | 68.9 GPa | 10,000ksi | 71.7GPa | 10,400ksi |
| Thermal conductivity | 167 W/m-K | 1160 BTU-in/hr-ft2_0F | 130 W/m-K | 900 BTU-in/hr-ft2_0F |
| Melting point | 1080-12050F | 582 - 6520C | 890-11750F | 477-6350C |
| Electrical resistivity | 3.99 x 10-6 ohm-cm | 5.15 x 10-6 ohm-cm | ||
| Hardness (Brinell) | 95 | 150 | ||
| Machinability | Good | Fair | ||
Thermal Conductivity
Thermal conductivity measures how well a material transfers heat. Although 6061 and 7075 are heat treatable, 7075 is much stronger than 6061 and melts at a slightly lower temperature.
6061 aluminium, on the other hand, has a higher thermal conductivity than 7075 and is better suited for certain applications. Among the heat-treated options, the aluminium plate is more versatile and best known for its corrosion resistance and high toughness.
Understanding the differences between two alloys, even those with the same base metal, better informs which of the two is better suited for the intended applications. The addition of alloying elements greatly alters the metal's properties, hence the need to consider the differences between 6061 and 7075 aluminium.
