Applications of Aluminium Alloys
Aluminium itself is a soft, pliable metal. But, once it’s gone through an alloying process—where it’s combined with other elements like copper, silicon, zinc, magnesium and manganese—it gains more strength and properties.
These added properties allow the many different applications of aluminium alloys across multiple industries, including electronic technology, wind and solar energy management, electric module packaging and automotive body structures. Their strength, processability, conductivity, predominantly anti-erosion and eco-friendly nature bring many use cases and applications.
Here’s more on the different types of aluminium alloys and the application of common aluminium alloys.
What are the different types of aluminium alloys?
There are two types of aluminium alloys: Cast and wrought. Each type is formed in different ways, giving them unique characteristics.
The process of creating cast aluminium alloys involves melting pure aluminium and combining it with other metals while still in the liquid form. It’s then poured into a mould where it’s left to solidify. Once removed from the mould, it’s either in its final form or can be used for further processing.
Wrought aluminium alloys are also combined with other metals. However, they are formed into their final shape through a different process, either extrusion, rolling or bending, after the metal has solidified into ingots or billets.
How are the different types of aluminium alloys classified?
There are seven different common aluminium alloys used in aluminium manufacturing. Each series starts with a number 1-7 (1xxx, 2xxx, 3xxx, 4xxx, 5xxx, 6xxx & 7xxx). The first digit is the most important and tells you the primary alloying metals. It’s also used to differentiate between different alloy “series” or “grades.”
The second and third digits are randomly assigned to identify the different alloys in each series. The fourth digit specifies if the alloy is casting or an ingot. For the 1000 Series aluminium alloys, the last two numbers describe the aluminium purity in the alloy.
The different alloying elements are as below:
- 1000 series: The purest aluminium with a minimum of 99% aluminium
- 2000 series: Mixed with copper alloys
- 3000 series: Mixed with manganese
- 4000 series: Mixed with silicon
- 5000 series: Mixed with magnesium
- 6000 series: Mixed with magnesium and silicone
- 7000 series: Mixed with zinc alloys
Cast aluminium alloys also have an 8000 series, which is combined with tin, primarily used for bearing and bushing applications.
The most common aluminium used in the general fabrication industry is 3000, 5000 or 6000 series alloys. Wrought aluminium also accounts for the majority of aluminium products.
The differences in how cast and wrought aluminium alloys are classified
Both cast and wrought aluminium alloys are classified and named according to the type and amount of the alloying metals. Their naming convention takes the form of four digits. The main difference between the two is that the third and fourth digits are separated by a decimal point for cast alloys, making them look like this: xxx.x.
Wrought alloys naming convention does not include a decimal point.
What is the difference between aluminium alloys?
There are a few differences between cast and wrought aluminium alloys. However, the most significant difference is the fabrication process they go through to deliver the final product.
Cast alloys contain higher amounts of other metals (> 22% alloying elements vs. ≤4% alloying metals for wrought alloys). It’s important to note that aluminium loses its flexibility as more alloying elements are added, making most cast alloys susceptible to brittle fracture. Cast aluminium alloys typically have lower melting points and tensile strength than wrought alloys.
Wrought alloys still go through several modifications after getting to a solid state, and this difference is what impacts the different possible forms and physical properties of the final products. Wrought alloys have allowed designers to increase aluminium’s strength, conductivity and corrosion resistance while retaining flexibility and other beneficial qualities.
What are the different applications of aluminium alloys?
Aluminium and its alloys are used widely in architectural, aerospace, automotive, electrical, lithographic, packaging, and electronic applications.
Here are each aluminium series’s main alloying elements, including examples of aluminium alloy applications.
Cast alloys: Big electrical rotors.
Wrought alloys: Electrical conductors and chemical processing equipment.
Cast alloys: Cylinder heads and pistons, housings, and bearings.
Wrought alloys: Truck wheels and suspensions, aircraft fuselage, and wings.
Cast alloys: Motor parts, structural parts, marine and aircraft castings.
Wrought alloys: General sheet work, vehicles, electronics.
Cast alloys: Bridge railing support castings, dental equipment, cookware.
Wrought alloys: Welding wire and brazing alloy, architectural applications, forged engine pistons.
Cast alloys: Architectural and ornamental castings, welded assemblies.
Wrought alloys: Appliances, automotive parts, marine components.
Cast alloys: Automotive parts, mining equipment, castings for brazing.
Wrought alloys: Airframe structures, mobile equipment, high-stress parts.
|Cast alloys: Bearing and bushing applications.
How to choose the suitable aluminium alloy for each application
When it comes to using suitable aluminium alloys, it’s essential to understand the different characteristics and strengths.
For example, with the 6000 Series aluminium, engineers often request 6061-T6 aluminium. While this aluminium alloy has high tensile strength, it’s also quite brittle. So, the metal may fracture at the bend line when the part has to be formed or fabricated.
A better option for fabricated aluminium would be from the 5000 Series aluminium, as it forms well without cracking and has a reliable tensile strength.
The most significant factors that influence your choice of aluminium grade include:
- The intended physical properties of your product
- The fabrication process that you want to use to obtain them
You should also consider the cost of tooling, which is much higher for cast alloys than wrought alloys.