7075 vs 6061 aluminum: What are the Differences?

Aluminum is perhaps the only metal that gets as much attention as steel when it comes to structural metal fabrication. Aluminum weighs roughly a third the weight of steel and has excellent mechanical properties. However, aluminum comes in different grades, and each grade has unique features. For that reason, it is essential to understand the differences between various alloys of aluminum if you want to choose a material for your project. Two of the most used aluminum alloy grades for structural works include 7075 and 60161 aluminum. This article discusses the differences between 7075 and 6061 aluminum to give a better insight that can be used to select each grade for specific applications

The differences between 6061 and 7075 aluminum 

Comparing 6061 aluminum to 7075 aluminum requires a look into different categories of features. In this section, the main areas that bring out the differences between 7075 and 6061 aluminum are:

  1. Mechanical properties
  2. Uses/applications
  3. Fabrication considerations
  4. Chemical compositions

Each of these attributes is discussed differently to draw a comparison between 6061 and 7075 aluminum.

7075 vs 6061 aluminum chemical composition

7075 aluminum comes from the 7xxx series, while 6061 aluminum from the 6xxx series of aluminum alloys grade. With that in mind, it is notable that 6061 aluminum has a higher concentration of silicon, while 7075 aluminum has higher zinc content. Both 6061 and 7075 aluminum have a significant amount of magnesium. However, 7075 aluminum has slightly more magnesium and copper in its chemical make-up compared to 6061 aluminum.

6061 vs 7075 aluminum fabrication considerations 

6061 aluminum has a lower hardness and tensile strength compared to 7075 aluminum and therefore boasts of better fabrication.  This means that 6061 aluminum can be machined easily compared to 7075 aluminum. Additionally, 6061 aluminum has better formability than 7075 aluminum. On the other hand, both 7075 and 6061 aluminum can be joined through soldering and using adhesives or brazing. Still, 6061 aluminum is considered weldable while 7075 is not.

6061 vs 7075 aluminum applications

As mentioned earlier, there is more application overlap between 7075 and 6061 aluminum.  However, both alloys are used in making bike parts, aerospace apparatuses, and in building construction. The difference in the use of 6061 and 7075 aluminum lies in how the two are applied in the same industry. For instance, 7075 aluminum is used in the aerospace industry as a rod. At the same time, 6061 is used in the same sector in areas that require more elasticity, and due to its excellent formability, 6061 aluminum is preferred in projects that perfect edges and shapes like in tanks. On the other hand, 7075 aluminum is mostly preferred where strength is required, such as in making bike frames.

Comparing 6061 and 7075 aluminum using mechanical properties

6061 vs 7075 aluminum yield strength

Yield strength is the maximum amount of stress that a material can withhold deforming permanently. 7075 aluminum has a higher yield strength compared to 6061 aluminum. This means that 7075 aluminum can withstand more impact and pressure without deforming. This feature is brought by heat treatment and the chemical composition of 7075 aluminum. However, 6061 is not entirely weak as it has a yield strength of 276MPa, which is slightly lower than low-carbon steel.

6061 vs 7075 aluminum elasticity

Elasticity is the measure of the resilience of a material. This attribute also implies resistance to plastic deformation, and other people look at it as the stiffness of a material. Both 6061 and 7075 aluminum have the same response to elastic deformation.

6061 vs 7075 aluminum thermal conductivity

The thermal conductivity of a material is the measure of how well it transfers heat. Aluminum alloys are good conductors of heat and are therefore not used as insulating materials. However, thermal conductivity varies significantly depending on factors like heat treatment and chemical composition. 6061 aluminum has a slightly higher thermal conductivity compared to 7075 aluminum and is, therefore, preferred where heat dissipation is a primary requirement such as in heat exchangers.

6061 vs 7075 aluminum temperature resistance

Temperature resistance can be compared using a melting point, which is the temperature at which a material changes from solid to liquid. 7075 aluminum a slightly lower melting point compared to 6061 aluminum despite being twice as strong. This means that 6061 aluminum can withstand higher temperatures than 7075 aluminum. However, 7075 aluminum reacts excellently to heat treatment and allows better distribution of alloying elements in the metal.

6061 vs 7075 aluminum electrical resistivity

6061 vs 7075 aluminum electrical resistivity

Electrical resistivity is measured by how well a material resists the transfer of electricity. In other words, it is the opposite of electrical conductivity. Both 6061 and 7075 aluminum have low electrical resistivity, which means they are good conductors of electricity. For this reason, both alloys are useful in electrical applications. However, 6061 aluminum has the lowest electrical resistivity, which implies it is more conductive than 7075 aluminum.

6061 vs 7075 aluminum hardness

6061 vs 7075 aluminum hardness

The hardness of a material is measured by how it responds to indentation. If the material is easy to dent, then it is considered hard. The opposite of hard in this context is soft. Harder materials are mostly brittle and dent easily when under pressure. On the other hand, less hard materials are ductile and can withstand bending without cracking or denting. Both 6061 and 7075 aluminum are hard enough to resist deformation. At the same time, they are sufficiently pliable to avoid cracking when under pressure. However, when comparing the two, 7075 aluminum is harder compared to 6061 aluminum.

6061 vs. 7075 aluminum machinability

Machinability of a material is how it responds to machining processes. Machinability can also be looked at as fabrications considerations. In this context, 6061 aluminum responds well to machining since it is weldable and formable.

The bottom line

This article has looked at the differences between 6061 and 7075 aluminum based on various factors and properties. Notably, both alloys are suitable for a specific application, and users should, therefore, consider each material based on its features that are ideal for the project.