Aluminum is a highly versatile material for prototyping and production runs. Aluminum alloys offer the desired strength and corrosion resistance at a low cost, and, like steel and titanium, they are easy to machine. However, no two aluminum alloys are the same. Depending on the primary and secondary alloying elements, essential properties may vary between each alloy. Failure to determine the right aluminum alloy for your application may cost you in performance and reliability.
Below, we discuss the most common causes of poor aluminum performance as well as the most commonly used aluminum alloys and their preferred applications so you can ensure you’re using satisfactory aluminum for your project.
Common Causes of Poor Aluminum Performance
There are many causes of poor aluminum performance. For instance, you may have purchased and received a batch of aluminum with extrusion defects. Any sign of bubbles, layering, or inclusions can confirm that the batch received has some extrusion defects, and you should consider talking to your supplier for a replacement.
Some manufacturers look for every way possible to reduce the production cost. For example, decreasing chemical reagent content can lower the price but at the cost of poor corrosion resistance. The manufacturer may also decrease the wall thickness to less than the required national standard. That’s why it is imperative to purchase alloys from a reputable metal supplier with proper verification procedures.
However, the main reason for poor aluminum performance is failing to select the right alloy for the application; for example, you may select a 2xxx series aluminum alloy for a high-strength, high-corrosion application; however, while the 2xxx series alloys are high in strength, they have moderate to low corrosion resistance properties.
Copper is the main alloying element in 2xxx-series aluminum alloys, often followed by magnesium as a secondary addition. The presence of copper offers strength and improves workability. The strength of the 2xxx series alloys is further elevated through precipitation heat treatment. However, under certain instances, such as in corrosive environments, the alloys may develop intergranular corrosion due to the presence of micro-constituents. Thus, they need additional galvanic protection in the form of a high-resistance alloy coating.
6061: The Versatile Aluminum Alloy
Aluminum 6061 is the most commonly used aluminum alloy. It has moderate strength coupled with excellent corrosion resistance due to less copper content as compared to other high-strength aluminum alloys, such as 7075.
Tempering is the heat treatment applied to aluminum to further improve its strength and hardness. 6061 is available in the following different tempers:
- 6061-F: As Fabricated
- 6061-O: Annealed
- 6061-W: Solution Heat-Treated
- 6061-TX: Thermally Treated
These tempers may score differently when it comes to formability, machinability, and weldability. For instance, 6061-T4 and 6061-T4511 are aged naturally for applications requiring good formability and weldability. However, they are difficult to machine. If formability is not the concern, 6061-T51 is the best option, as it offers excellent weldability and machinability. Thus, having a clear understanding of material properties can help ensure a satisfactory aluminum purchase.
Most Widely-Used Aluminum Alloys
Let’s take a look at some of the other commonly used aluminum alloys and the unique properties that make them highly sought-after.
7075 is the strongest aluminum alloy available, with a strength almost twice that of 6061. The main alloying elements are zinc, magnesium, and copper. With a high strength-to-weight ratio and tensile strength equivalent to that of steel, 7075 is the primary choice for the aerospace and defense industry.
However, it is not a versatile alloy. For instance, if parts need to be joined, you should choose 6061 over 7075, as the latter is prone to welding defects. Also, 7075 is prone to corrosion resistance due to the presence of copper. Thus, 7075 would be your ideal choice for high-strength applications not requiring frequent welding.
MIC-6 aluminum is a cast plate, often recommended for applications requiring precise control of tolerances and dimensions. The machinability is excellent with minimal risk of distortion, and uniform chips are produced, even at high speeds. Given its excellent machinability, MIC-6 is a popular choice for precision machining and instrumentation applications, such as base plates, jigs, and gauges.
However, it’s important to be extremely careful while welding MIC-6 plates. As they are prone to corrosion cracking, experts recommend MIG welding over TIG welding to avoid failures.
ACP 5080 is known for its excellent machinability and dimensional stability required for manufacturing PCB substrates and high-precision machine components. Furthermore, the low porosity of 5080 makes it immune to metal cracking during machining. With extremely fine grain microstructures, ACP 5080 features high yield strength for heavy machining applications; thus, it is one of the best low-tension aluminum tooling plates.
Aluminum 6082 is a medium-strength structural aluminum option, yet it offers the highest strength among all 6xxx series alloys and is an ideal alternative to 6061 in many applications. The 6082 alloy is available in various tempers; it’s important to select the right temper to experience a satisfactory aluminum purchase. For instance, if you need good machinability, the T6 and T651 tempers would be an excellent choice over annealed wrought alloys.
Purchase Satisfactory Aluminum from a Professional Supplier
Industrial Metal Service specializes in offering high-quality aluminum and aluminum alloys to fabricators and machine shops in the San Francisco Bay Area and beyond. Aside from aluminum, our vast inventory of metals also includes titanium, copper, angle iron, and specialty metals such as Invar 36 and Hastelloy. Moreover, our fast and reliable metal sawing service can provide you with aluminum metals cut to size for your desired applications.