Aluminum vs Steel: The Best Metal for Your Project

Steel and aluminum are the two most widely used materials in metal manufacturing. Despite their obvious visual similarities, several key differences in the underlying properties influence their use and application. 

As specialists in the metal manufacturing industry, The Federal Group USA understands these distinct characteristics and can help you choose the ideal material for your next project. This guide offers extensive insight into the main distinguishing physical characteristics of aluminum vs steel and their many possible applications.

Physical Characteristics Comparison

Aluminum and steel have many different traits that make them suitable for a range of projects. Check out this overview and compare the physical properties that impact applications for aluminum and steel. 

Strength and Malleability

A material’s malleability determines how metal manufacturers like The Federal Group manage weight and optimize strengths. This requires evaluating the metal’s strength-to-weight ratio. 

Steel’s overall greater density makes it generally stronger than aluminum. However, the significantly greater strength comes with weight differences and reduced malleability. 

Aluminum’s highly desirable malleability makes it a no-brainer for metal casting projects that require intricate designs and enhanced mobility. Despite its excellent resilience and toughness, you can’t push steel to its dimensional limits without running the risk of it cracking or ripping.

Weight

Steel is stronger and harder than aluminum, so it naturally follows that it weighs more. In fact, steel is about 2.5 times denser than aluminum, a factor that can be a disadvantage unless your project requires exceptional load-bearing capacity or needs to withstand extreme forces.

Aluminum, on the other hand, weighs about one-third as much as steel, making it easier to work with in manufacturing processes like machining, bending, and casting. For projects where strength is less critical, aluminum’s lighter weight offers both efficiency and cost savings.

Heat Conductivity

Thermal conductivity refers to a material’s ability to transmit heat energy. The unit for measuring this rate is watts per meter per kelvin (W/m·K). 

Metals with excellent heat conductivity can quickly transfer large quantities of heat. The number of mobile electrons in a metal determines its thermal conductivity. Additionally, the heat transfer rate improves with a material’s quality, with metals being in their purest form when annealed. 

Pure aluminum offers much better heat conductivity than steel at 235 W/m·K. This makes aluminum an ideal material for applications that require heat dissipation, like in:

• Heat sinks
• Air conditioning units

Below are some thermal conductivity rates for different steel variants.

• Carbon steel: 45 W/m·K
• Stainless steel: 15 W/m·K
• Tool steel: 24 W/m·K
• High-speed steel: 25 W/m·K
• Ferritic stainless steel: 25 W/m·K
• Duplex stainless steel: 30 W/m·K

Corrosion Resistance

Steel is a metal alloy derived from iron ore, while aluminum is a derivative of bauxite ore. Steel’s ferrous component contributes to its increased susceptibility to corrosion.

Aluminum is more resistant to corrosion owing to a naturally forming protective coating of aluminum oxide. This non-reactive layer safeguards the inner layers from harsh environmental elements. 

Some steel types, like stainless steel, contain a higher percentage of chromium, which improves their corrosion resistance. However, a bronze and aluminum alloy matches this resistance level, making it the preferred option in some applications.  

Shapes

As raw materials, steel and aluminum both come in a variety of shapes, from sheets and rods to ingots and bars. Through The Federal Group’s metal manufacturing capabilities, both types of metal can be shaped to meet your project’s specific design requirements. 

Each material is best suited to certain forms based on properties such as malleability, strength, and grain structure. For example, aluminum’s malleability and lightness make it ideal for thin sheets and complex shapes. Steel, with its high strength and durability, is typically used to manufacture sturdier shapes like beams, gears, and turbine parts. 

Electrical Conductivity

Steel has about 10% of the electrical conductivity of copper, while aluminum offers an impressive 60%. Aluminum also has excellent heat conductivity and dissipation, which is why cooking pans leverage its electro-thermal features to maintain even heat at the core. In many cases, a stainless steel surface is added on top. 

Environmental Impact

When considering sustainability, aluminum generally has a lower environmental impact than steel. Aluminum is infinitely recyclable without damaging its quality or durability. 

Other factors that contribute to aluminum’s ecofriendliness include:

• It requires less time and energy to recycle than steel.
• The aluminum production process emits fewer greenhouse gases. 

Alternatively, steel offers unmatched durability and strength, making it ideal for long-lasting structures and heavy-duty reuse in construction and infrastructure. This longevity offsets the need for frequent replacements.

A Summary of Key Differences in Steel vs Aluminum

To help you make an informed decision for your next metal project, here is a quick reference to compare the physical characteristics of aluminum and steel. 

Fabrication & Workability

The physical properties of steel and aluminum significantly influence their workability and response to manufacturing and fabrication. These differences can determine how you select aluminum vs steel for various processes.

Machinability

Material machinability refers to the ease with which you can mill or cut a workpiece to produce a prototype or a final custom part. 

Aluminum is characteristically softer than steel, making it relatively easier to process with different machining methods. Its excellent thermal conductivity further contributes to less heat buildup in the cutting zone, reducing the likelihood of tool wear. 

Aluminum’s superior machinability properties make it a clear favorite in industries that require intricate parts with tight tolerances and fast turnarounds. Aluminum is especially common in industries like  medical device manufacturing, telecommunications,  and electronics. 

Meanwhile, a steel variant like stainless steel is three times harder to cut. Machining this high-strength material requires lower cutting speeds and increases the cost of tool replacements. Processing steel also generates more heat and may require specialized lubricants and tooling. 

Steel’s greater machining demands are acceptable in heavy-duty uses where wear resistance is a key factor. This makes steel a preferred choice in industries such as die making, construction equipment, and heavy machinery production.

Weldability

Due to their unique physical characteristics, steel and aluminum respond differently to welding. Common welding methods used for both types of metal include stick welding, tungsten inert gas (TIG) welding, and metal inert gas (MIG) welding.

When it comes to welding, aluminum poses more challenges than steel. One reason is that aluminum has an oxide layer that melts at about 3700°F, which is much higher than the melting point of 1221°F of the aluminum underneath. The high thermal conductivity and porosity of aluminum further complicate the welding process.

By contrast, steel is more forgiving with a higher melting point of 2500°F. It lacks many of the variances of aluminum and has a wider workable temperature range for welding. As a result, steel tends to produce higher quality welds with less defects, making it the preferred choice for structural welding applications.

To improve aluminum welding outcomes, several practices can help minimize defects and cracking. First, choose the correct filler metal. Thoroughly clean the metal to remove oil, moisture, and other contaminants. Removing the oxide layer, whether that’s by sanding, acid etching, or alkaline cleaning, can also optimize the welding quality.

Additionally, when welding aluminum, avoid the weaving technique. Instead, use a stringer bead that enables proper fusion and penetration. Always store the filler metals and base materials properly to prevent porosity and trapping water. And be sure to evaluate your consumables, like hoses and gas lines, before use to ensure they are in optimal condition.

Forming and Bending Tolerance

Metal forming enables you to shape materials into angles, curves, curls, seams, and flanges without compromising structural integrity. Aluminum is more malleable than steel, making bending at room temperature, especially thinner gauges, easier. However, aluminum is more prone to cracking if over-bent and tends to exhibit more springback. 

Aluminum is an excellent material for complex curved designs like decorative panels, marine structures, and enclosures. Mild or annealed steel variants have good forming capabilities with less spring back and a lesser risk of cracking during bending, making them an excellent option for structural shapes and heavier gauges.

Applications of Aluminum

Aluminum’s durable yet malleable nature makes it popular across various industries. Some of the major sectors that utilize fabricated aluminum products include: 

Chemical Processing

Aluminum’s naturally occurring oxide layer protects the underlying metal from acidic and reactive environments. This is a contributing factor to its significant use in the construction of chemical processing tools, including:

• Equipment for water treatment and producing medicines, textiles, and paints
• Storage tanks
• Piping systems

Farming and Agriculture

Aluminum is lightweight, corrosion-resistant, and able to withstand harsh weather extremes, making it a good choice for the farming and agriculture industry. It is used to produce components such as:

• Frames for equipment
• Storage systems
• Irrigation systems
• Equipment like plows, cultivators, and sprayers

Oil and Gas

The petroleum industry benefits from aluminum’s natural resistance to corrosion to create parts that can withstand extreme conditions, including:

• Oil rigs
• Offshore platforms
• Structural frames

Healthcare

The healthcare sector heavily relies on aluminum parts to develop lightweight, easy-to-sterilize medical products that assist with patient care. 

These products include:

• Ventilation devices
• Testing apparatus
• Stethoscopes
• Hospital beds
• Surgical tools
• Wall-mounted enclosures
• Cylinder storage cabinets

Power Distribution

The power and electrical energy distribution sector relies on aluminum products to create highly conductive, corrosion-resistant products like:

• Junction boxes
• Electronic enclosures
• Control rooms
• Utility boxes
• Electrical bus bars
• Connectors 
• Transformers

Telecommunications

The telecommunications sector requires aluminum products to construct and maintain its extensive infrastructure. 

Examples of aluminum telecommunication applications include:

• Data storage centers
• Instrument enclosures
• Control rooms
• Masts

Applications of Steel

Steel fabricated parts offer enduring strength and structural reliability that is indispensable in a variety of industries, such as:

Energy

Steel’s exceptional strength and durability make it a backbone raw material for various infrastructure and processes in the energy sector, including:

• Pipelines
• Transmission towers
• Solar panel parts
• Wind and water turbines

Infrastructure

The Federal Group is a trusted partner for using steel extrusion services to manufacture large, custom steel components for infrastructure development. Modern infrastructure projects that rely on steel’s excellent tensile strength and longevity include:

• Highways
• Rail systems
• Bridges
• Utility poles

Architecture

Architects can utilize steel parts to create bold, expressive structures. The Federal Group supports architectural projects with precision steel fabrication, where aesthetics and durability must align perfectly. 

Marine

Steel offers unmatched strength and durability that finds extensive applications in the marine industry, such as:

• Shipbuilding sturdy hulls, superstructures, and internal components, such as decks and support systems
• Offshore structures like gas and oil platforms, as well as wind turbines
• Maritime constructions like sheet piling, docks, and piers

A few of the marine-grade steels that are ideal for this role include:

• Carbon steel
• Duplex stainless steel 
• Cor-Ten Steel
• 316 stainless steel

To enhance the material’s durability and corrosion resistance, steel fabricators can opt for protective coatings like:

• Epoxy
• Coal tar
• Polyurethane
• Zinc-rich primers
• Hot-dip galvanizing
• Thermally sprayed aluminum

Steel offers superior load capacity and impact resistance to aluminum, making it ideal for structurally sensitive applications.

Aluminum vs Steel Cost

While physical properties like weight, strength, and durability are key factors to consider when choosing a material, price is another critical determinant. Aluminum vs. steel prices tend to fluctuate depending on these factors:

• Raw material cost: Steel is generally cheaper than aluminum. Iron ore, the main raw material for steel,  is abundant and generally cheaper per pound than bauxite ore, the main source of aluminum.
• Processing cost: Aluminum production requires more energy than steel. Extraction from bauxite ore requires electrolysis, which is more energy-intensive than smelting iron ore, which is done in a furnace.
• Lifecycle cost: Generally, aluminum has a lower lifecycle cost, owing to its corrosion resistance and recyclability. In environments prone to corrosion, aluminum has a lower maintenance cost, making it a more cost-effective option for long-term applications.  Steel, while more durable under certain conditions, requires more maintenance in corrosive environments. . 

Future Trends and Innovations

Future trends in the aluminum and steel manufacturing industry are focusing on both performance and sustainability. New material developments, like high-strength low-alloy and advanced high-strength steels,  have given rise to different metals with exceptional durability and reduced weights. 

3D printing is becoming more common in metal manufacturing, particularly for prototyping, but also for manufacturing complex shapes. While 3D steel and aluminum printing isn’t as widespread as traditional methods, the technology is gaining traction in some industries, such as healthcare. 

When it comes to sustainability, the metal manufacturing industry is responding to growing consumer demands, environmental concerns,  and regulatory requirements. Eco-friendly manufacturing methods, like using hydrogen instead of carbon fuels in the smelting process, are significantly reducing the carbon footprint of the entire industry. Recycling scraps and optimizing material usage are additional steps being taken to reduce waste and environmental impact.

Choose Between Steel and Aluminum

Choosing between aluminum vs steel depends on your project’s needs and the final product’s specific use. These factors largely depend on the different physical characteristics of steel and aluminum, which can be tricky to keep track of without expert help. 

Our experts can help you select the ideal material for your next project. Contact The Federal Group today for a free consultation.