Steel and aluminum are two materials commonly used in industries from aerospace to automotive manufacturing and from construction to electrical components and beyond. They often look similar and are both highly recyclable; however, they aren’t always interchangeable.
There are many grades and alloys of both aluminum and steel; therefore, any comparison between the two will be somewhat general. And of course, the specific application, its design intent, and function in an assembly or structure usually determine the optimal material.
Here, we will explore some properties of aluminum and steel and some significant differences between the two materials.
Aluminum vs. Steel Fabrication
Let’s look at both materials in terms of several key properties: conductivity, malleability/formability, weight, strength, and corrosion resistance, as well as cost.
Conductivity
Conductivity is a measure of how good a conductor a material is, and the higher a material’s conductivity, the lower its resistivity, and vice versa. Thermal and electrical conductivity are important properties for metals. Aluminum is more conductive than steel, making it a good choice when rapid heat dissipation or electrical transfer are needed. Because aluminum is less resistant to heat, it softens at lower temperatures than steel, which limits its use in some applications. Steel has low thermal and electrical conductivity and is well-suited to high-temperature applications or when thermal or electrical insulating properties are needed.
Malleability
Malleability, or plasticity, is how easily a material can be shaped (e.g., drilling, bending) without breaking. Aluminum is very malleable and can be easily cut, folded, and bent. Steel alloys are much harder than aluminum and as a result, they are less malleable. This gives steel materials their high strength but also makes them more difficult to bend, machine, and cut.
Weight
In comparing steel vs aluminum weight, application requirements are critical. Aluminum is about one-third as dense as steel, making it very lightweight. For this reason, it is often used in vehicles and aerospace components to minimize weight and improve fuel efficiency and EV battery life. Steel is far more dense and heavy.
Strength
Which is stronger, aluminum or steel? Aluminum has a high strength-to-weight ratio compared to steel, so it provides structure and strength without the added weight of steel. However, steel, and especially carbon steel, is stronger than aluminum and has a particularly high tensile strength. This makes it a good choice for load-bearing applications, such as in construction.
Corrosion Resistance
Aluminum is highly resistant to corrosion, though it can be susceptible to powdery, white rust when exposed to saltwater or salt spray. Stainless steel is also highly corrosion-resistant because it includes chromium. Carbon steel does not resist corrosion well and usually requires a coating of paint or other material for extra protection.
Cost
Cost is a major consideration when selecting materials. Because it is lighter, transportation costs are often lower for aluminum materials. Steel is heavier and will cost more to transport, though it is generally less expensive to manufacture and is readily available. Of course, supply chain and logistics and global supply and demand cause metal prices to fluctuate over time as well.
Metal Fabrication From Atlantic Tool & Die
When choosing steel versus aluminum alloy materials for a fabrication project, start by defining the critical features or functions the application requires. Then assess those against the properties and considerations discussed here. The team at Atlantic Tool & Die can help with material selection along with stamping, tube manufacturing, assembly, welding, and other fabrication capabilities.
Contact us or request a quote to discuss your next metal fabrication project.