Converting from Steel to Aluminum Forging
Aluminum is prized for its strength-to-weight ratio. Much of the modern aerospace and aircraft construction industries wouldn’t exist without the highly advanced aluminum industry to provide ideal materials. Customers should have a complete understanding of why aluminum is used, what it is used for, and the benefits of forged aluminum relative to steel. The following should provide you with a greater understanding of the different properties and uses of forged aluminum versus steel.
The Properties of Aluminum
Aluminum is the most abundant metal available and is thus generally very affordable to procure for a wide variety of uses. In addition, aluminum is generally found much closer to the Earth’s crust due to its natural lower density. The process of forging aluminum produces a high-quality product with speed and efficiency that has excellent strength-to-weight ratios, making it useful in applications where high performance is necessary, but excess weight is prohibitive.
The greatest strengths of forged aluminum are:
- Weight: Aluminum has excellent weight for the strength it provides. This weight is vital when a heavy part would be undesirable for a given application. The heaviest duty and stress-laden applications may not be appropriate for aluminum, but when producing lightweight performance parts for aerospace or racing applications, aluminum is the proper choice.
- Ductility: At normal forging temperatures, aluminum is an incredibly ductile material. This allows for a number of forging applications to be easily performed on aluminum stock without risk of damage, failure, or deformation of a part during the process. In addition, this ductility allows the part to be subjected to closed-die forging procedures that are not possible for steel.
- Simple Tooling: One simple but not obvious benefit for forging aluminum is the ease of tooling. Aluminum is forged in steel dies, which will absorb heat from the part. However, because aluminum heats more rapidly and becomes elastic at much lower temperatures, a steel die can be heated to the same temperature as the aluminum piece and suffer no deformation.
- Corrosion Resistance: Aluminum is naturally corrosion resistant. Aluminum oxide forms in a thin layer around a natural aluminum part and provides a protective layer of inert material, protecting the aluminum below the oxide layer. Some special 2000 series alloys can introduce a reduction in corrosion resistance, but most common aluminum alloys do not suffer this problem.
- Versatility: Aluminum has a vast number of alloy standards, heat treat standards, and post-production treatments that can modify the properties of the aluminum part. The variety of aluminum alloys and treatment standards means a specific lot of production parts can be tailor-made to fit nearly any application.
- Workability: Because of the lower density of aluminum, it is considerably easier to forge. Lower pressures, smaller presses, smaller dies, and lower temperatures mean that aluminum is overall much less costly to forge than steel. In addition, the greater thermal conductivity of aluminum means that an equal weight of aluminum heats up and cools down faster, making the heating and cooling processes faster and thus cheaper.
- Non-Magnetic: Aluminum is non-magnetic in nearly all its forms. It is electrically conductive (in fact, aluminum is a better conductor than stainless steel), but its non-magnetic properties can make it a safer material to use in or near electrical applications.
Aluminum forgings are used in a wide variety of home and professional applications. From airplane frames and various components to hobby hang-gliders, stairwell railings, and bicycles, forged aluminum is a powerful and versatile material.
The Properties of Steel
Steel, on the other hand, is still an abundant and cheaper structural metal available on the market. Steel, in general, is also much stronger, more rigid, and durable than an equal volume of aluminum. When considering forged aluminum to steel, steel has the following advantages:
- Strength: Steel is, on average, 2.5x denser than aluminum. This contributes in equal measure to the strength and weight of steel versus aluminum. Some mild steels weigh a similar amount to aluminum and are not nearly as strong as harder steels, but some hardened stainless alloys can provide over triple the strength by volume when compared to aluminum.
- Cost: Iron is one of the most abundant metals in the Earth’s crust and is generally easier to smelt. The cost of raw materials for steel means that the final steel product will be cheaper.
- Versatility: Steel is by far the most versatile structural metal available. Varying levels of carbon, alloying elements, heat treatment, and post-work treatments produce thousands of different types of steel. Steel can be almost as dense and strong as tungsten or almost as light as aluminum. Stainless steels are corrosion-resistant, while basic carbon steel is easily degradable. Hard tool steels are almost as hard as ceramics, whereas soft annealed steel can be as soft as aluminum or silver. This immense versatility can mean that whatever the application is, there is almost always a type of steel that is appropriate.
- Welding: Steel is easily weldable due to the presence of carbon, which means that for structural applications where joining is needed, steel will almost always perform better than aluminum.
Forged Aluminum vs. Steel
So why would a customer choose forged aluminum over steel products? Well, simply put, aluminum is often the superior choice. Forged aluminum is strong, lightweight, and versatile; steel is too heavy for applications in some of the most high-performance fields like aerospace. It may offer superior strength by volume, but its multitude of shortfalls, when compared to forged aluminum products, are numerous. In fact, the entire aerospace industry would not exist as it does now without lightweight aluminum alloys.
Anchor Harvey is proud to continue a legacy of high-quality aluminum forging for aerospace and other performance fields that have continued since the beginning of the 20th century. When it comes to finding the strongest, lightest, and most versatile parts with the highest quality and fastest turnarounds, Anchor Harvey does it all. Request a quote today.