Two of the most popular aluminum alloys for high-strength, low-weight applications are 6061 and 7075. When comparing the two on paper, the incredible strength of 7075—almost twice that of 6061—is often the major difference that jumps off the page.
While 7075 is one of the strongest aluminum alloys available, aluminum 6061 is more versatile. There are other important differences between 6061 and 7075 that make them suitable for very different applications.
In this post, we’ll compare the properties, manufacturability, and applications of aluminum 6061 vs. 7075 so you can make an informed decision about which one is best for your project.
Comparing 6061 vs. 7075
Aluminum alloys can have very different properties based on their composition. The main alloying elements of 6061 are silicon and magnesium, while 7075 is alloyed with zinc, magnesium, and copper.
Strength and Hardness
7075 has one of the highest strength-to-weight ratios of any aluminum alloy, so this alloy is primarily used by the aerospace and defense industries. It is comparable to many grades of steel in tensile strength. It’s also much harder than 6061. However, although the strength of 6061 is only about half that of 7075, it is still strong enough for many applications in the construction, aerospace, and automotive industries.
One of the biggest drawbacks of 7075 compared to 6061 is its inferior corrosion resistance, a result of the presence of copper as an alloying element. There is a higher aluminum content in 6061 than in 7075, and 6061 also contains less copper, so it forms a more consistent protective oxide layer that protects it against corrosion.
Working with 6061 vs. 7075
While 7075 is one of the strongest aluminum alloys, 6061 is much easier to work with. The exceptional strength and hardness of 7075 also make it more difficult to cut and form.
Because of its higher ductility, 6061 is much easier to form and weld than 7075. While 6061 is easily weldable, 7075 is prone to welding defects like heat cracking and is generally considered unweldable. This is an important consideration if parts will need to be joined, as 7075 can only be joined with rivets or other fasteners.
Both 6061 and 7075 have good machinability. However, because it’s not as hard, 6061 is more easily machined than 7075. Manufacturers and fabricators consider 6061 the go-to aluminum alloy for most machined parts because of its balance of machinability, strength, and other desirable properties.
Applications of 6061 vs. 7075
Aluminum 6061 is an extremely versatile alloy and is suitable for a wide range of structural applications. It is particularly useful when:
- Welding will be required.
- Corrosion is a concern.
- Cost is an important factor.
However, 7075 might be a better choice when:
- A maximum strength-to-weight ratio is needed.
- Parts will not need to be welded.
- Cost is less of a concern.
Aluminum 7075 is an extraordinarily strong alloy, but that extra strength comes with a higher price tag. Because of this, it should usually not be used when 6061 has sufficient strength for the application. However, 7075 is useful for high-stress structural components like gears and shafts, especially in aircraft where weight is a critical factor.
For a quick comparison, the properties of both aluminum 6061 and 7075 are listed in the table below.
|Property||Aluminum 6061||Aluminum 7075|
|Ultimate Tensile Strength||45 ksi||83 ksi|
|Yield Strength||40 ksi||73 ksi|
|Shear Strength||31 ksi||48 ksi|
Where to Buy 6061, 7075, and Other Aluminum Alloys
Industrial Metal Service specializes in supplying 6061, 7075, and a variety of other aluminum alloys to machine shops, fabricators, and manufacturers in the San Francisco Bay Area. We also ship to a growing number of customers across the U.S. who don’t have the benefit of a local supplier. We stock an extensive inventory of aluminum alloys, including 6061 and 7075, and offer customers the option of buying new metal sourced from U.S. mills or verified remnants, which offer considerable savings. We also provide cut-to-size sawing services.