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Aluminum vs Steel: A Comprehensive Comparison 

When it comes to manufacturing, two materials that get a lot of usage are steel and aluminum. And, considering their similarities, it won’t be a surprise to see many people comparing them. 

In the aluminum vs stainless steel debate, there are several points to consider – whether convergent or divergent. So, we thought it would be best to lay out the steel vs aluminum conversation clearly to provide more clarity on their properties and what to expect from them.

Aluminum: How It Became So Popular

aluminum bars

To start with the steel vs aluminum debate, it is important to know what both are. 

Aluminum is one of the most prominent metals available. It is one of the most popular elements in the world and is especially notable for its lightweight build and silvery-white look.

Here’s a fun fact – aluminum is actually the third most abundant element in the Earth’s crust. 

The metal is known for having impressive corrosion resistance and not being so dense. Besides that, aluminum is highly malleable and ductile.And, as you can expect, this combination of characteristics makes the material suitable for use in different industries.

Over the years, many manufacturers have been able to bank on the operational flexibility of aluminum – as well as the material’s ability to be recycled. In a world where more people and companies are changing their operations to be more eco-friendly, aluminum provides a simple way to comply with this rule. 

Aside from that, advancements in technology have led to the formulation of aluminum alloys.  These alloys are made by mixing aluminum with other materials, essentially giving them the best of both worlds when it comes to functionality and physical properties. Fromheat resistance to durability and strength, these alloys are also as versatile as the primary aluminum material.

Steel: Its Compositions, And What Makes It So Valuable

Unlike aluminum, stainless steel isn’t an element. Instead, it is an alloy. 

In most cases, stainless steel is determined by its content of not aluminum; but chromium. Most times, steel contains about 10.5% of the element, as well as a combination of other materials. All in all, the material is prominent for its impressive combination of long-term durability and physical appeal. And, like aluminum, it is also used in different industries due to its unique properties. 

Aluminum vs Steel: Understanding Their Properties

steel nuts

Of course, it won’t be a comparison without understanding the different properties that both materials have. Here, you ask questions like, “What is the aluminum vs steel strength?” and more. 

Below is a breakdown for better understanding:

Aluminum: Chemical Compositions

As explained earlier, aluminum has a simple chemical composition that consists of just the material itself. That’s pretty much all. Aluminum is a pure metal, and it is capable of operating on its own. 

Nevertheless, it is worth noting that aluminum doesn’t work on its own when you consider its practical applications. In most cases, you see the material being used in the form of alloys, which allow you to mix aluminum with other materials. 

Metallurgists and manufacturers use these elements to alter the primary properties of aluminum, bolstering it on different fronts to improve its compatibility with different functions. Although alloying materials will vary, below are some of the most prominent available: 

  • Copper (Cu): One of the most popular alloying elements that get paired with aluminum is copper. With a dash of copper, aluminum becomes stronger and is able to better hold its own against external rust. With copper-aluminum alloys (which include the 2,000 and 6,000 series), you get optimal machinability and high levels of strength. 
  • Zinc (Zn): Another common alloying element for aluminum is zinc. The element helps to improve an alloy’s hardness and durability, and you can usually find zinc-aluminum alloys in applications that require optimal tensile strength. 
  • Magnesium (Mg): In most cases, magnesium is often added to aluminum to increase its strength and improve its workability. Aluminum-magnesium alloys are lightweight and have good corrosion resistance, making them suitable for structural applications.
  • Silicon (Si): Most manufacturers add silicon to aluminum to improve the alloy’s fluidity while casting. These alloys are properly castable, making them perfect for automotive functionalities. 
  • Manganese (Mn): Manganese is another element that can be coupled with aluminum to make the latter stronger and more corrosion-resistant. MAny metallurgists also prefer it for its availability and cost-effectiveness. In cases where proper formability and corrosion resistance are required, you can count on these alloys to work. 
  • Other Elements: Besides the elements listed above, you can also find others such as lithium (Li), titanium (Ti), and zirconium (Zr) that can be added in trace amounts to aluminum – or aluminum alloys to improve specific properties. 

As long as you have the right material specifications, the composition of an aluminum alloy can easily be formulated.

Aluminum: Physical Properties 

The physical properties of aluminum include:

  • Density: When you compare it with many other materials, aluminum’s density rating isn’t so high. The metric is pegged at just 2.7 grams per cubic centimeter (g/cm³). With such a low density rating, aluminum is light; making it perfect in applications where you want to see more weight reduction.
  • Melting Point: Generally, aluminum melts at about 660 degrees Celsius (1220 degrees Fahrenheit). Again, this is relatively low. However, it makes it quite easy for the material to be melted and cast into different shapes in different manufacturing processes.
  • Thermal Conductivity: Aluminum exhibits excellent thermal conductivity – with the metric measuring up to about 237 watts per meter-kelvin (W/(m·K)). With a high thermal conductivity, aluminum transfers heat seamlessly and is great for applications where heat dissipation is needed.
  • Electrical Conductivity: Aluminum also conducts electricity well. The material has an electrical conductivity of approximately 37.7 million siemens per meter (MS/m), meaning that it can be used to make different electrical components. 
  • Ductility: As explained earlier, aluminum is also quite ductile. It can be rolled to form sheets or drawn to create wires without losing its original form. And, this material flexibility allows the material to be used in multiple fabrication processes. 
  • Malleability: Aluminum is also highly malleable, allowing anyone to shape and form it into their desired specifications. This is one of the major reasons why it is so flexible in manufacturing. 
  • Reflectivity: Aluminum reflects both infrared and visible light easily. As such, the material works in applications where reflective surfaces are needed..
  • Corrosion Resistance: On its surface, you can find an oxide layer that helps to repel external rust effects and keep it functional.

Aluminum: Mechanical Properties 

  • Strength: Aluminum is a relatively strong substance – although its alloys exhibit different strength ranges depending on their composition and heat treatment. It should be noted, however, that in the stainless steel vs aluminum strength debate, this material comes up a bit short.
  • Elasticity: Aluminum alloys have a low elasticity modulus – a factor that indicates that they do well when subjected to significant stress levels. This also means that the alloys absorb energy well, regardless of the structure. 
  • Toughness: Aluminum is quite tough. It absorbs significant amounts of energy without losing its form or fracturing. 
  • Hardness: Compared to steel, aluminum is also not quite as hard. However, as you probably know, it’s possible to harden aluminum alloys by applying certain heat  treatment modules to them to optimize their wear resistance.
  • Fatigue Resistance: With high fatigue resistance, aluminum alloys easily withstand continuous stress cycles without breaking or developing material failure. If you need a material to go through multiple rounds of cyclic loading, then aluminum is a good option for you. 
  • Creep Resistance: Aluminum alloys don’t resist creep that much. However, alloying and heat treatment can help to improve this metric if you’re interested. 
  • Fracture Toughness: Aluminum can hold their own in the fact of sudden impact or load hits. This high fracture toughness isn’t surprising since the material itself is hard. 
  • Machinability: Aluminum alloys are generally considered highly machinable. They have good chip-forming characteristics and can be easily cut, drilled, and machined using standard metalworking processes.

Steel: Chemical Compositions

Stainless steel is an alloy that usually consists of Iron (Fe) and several other elements. Generally, the specific chemical composition of the material will depend on the type and grade you’re talking about. However, some of the key elements that are commonly found in this material include: 

  • Chromium (Cr): Today, there is barely any element that is used to form an alloy that’s as popular as chromium. So, it should come as no surprise that it is found in the stainless steel composition as well. With chromium, steel is able to hold its own against external rust, thanks to the presence of an oxide surface layer.
  • Nickel (Ni): When corrosion resistance and ductility need to be optimized in a stainless steel material, nickel is added to it. Besides this, nickel also provides a stabilization of austenitic properties in the material at lower temperatures. In an ideal case, the nickel content of stainless steel won’t be more than 30%
  • Carbon (C): Carbon is another element that improves stainless steel’s strength. Ideally, its content in the material is usually about 0.08%
  • Molybdenum (Mo): With molybdenum, stainless steel improves resistance to both crevice and pitting corrosion. The specific property given will depend on the molybdenum grade you use. 
  • Other Alloying Elements: Besides the elements listed above, you can also find others being employed in stainless steel alloys to improve its physical properties – ranging from silicon to Nitrogen (N), titanium, and others. 

Steel: Physical properties 

Stainless steel has different physical properties that tend to vary based on the grade you’re talking about. However, you can easily find some properties that stand out and form a baseline for the mild steel vs aluminum debate. 

Here are some metrics you ant to keep in mind: 

  • Density: The density range for stainless steel moves from 7.75 to 8.05 grams per cubic centimeter (g/cm³), depending on the grade. Compared to aluminum, this is significantly higher. 
  • Melting Point: Generally, stainless steel melts within the range of  1370 to 1520 degrees Celsius (2500 to 2770 degrees Fahrenheit). This is significantly higher than aluminum, meaning that you would need to apply much more heat to stainless steel to get it to melt.
  • Thermal Conductivity: Compared to most other metals, stainless steel comes with a lower thermal conductivity. The metric stands between about 14 to 20 watts per meter-kelvin (W/(m·K)), depending on the specific alloy.
  • Electrical Conductivity: Stainless steel doesn’t conduct electricity quite like several other metals – including and especially aluminum. Its electrical conductivity typically stands lower than 3.5 million siemens per meter (MS/m).
  • Magnetic Properties: Depending on the composition, you can see stainless steel exhibiting different magnetic properties. For instance, austenitic steels aren’t so magnetic – while ferritic and martensitic steels tend to exhibit massive volumes of this property.
  • Hardness: Generally, you can see stainless steel hardness ranging from relatively soft to very hard. But, processes like cold working and precipitation hardening can help you to increase this metric if it’s not sufficient for you. 
  • Corrosion Resistance: One of the major reasons why stainless steel is so popular is that it exhibits an impressive level of corrosion resistance. Thanks to chromium in its build, the material does well to resist corrosion. But, if you’re really looking to maximize this metric, then you might want to consider a steel aluminum alloy. 
  • Strength: Stainless steel alloys exhibit a wide range of strength levels depending on their composition, heat treatment, and other factors. Different stainless steel grades can have varying levels of tensile strength, yield strength, and impact resistance.
  • Appearance: Stainless steel comes in a silver-gray hue, giving it a pretty unique appearance. If  you want aesthetic appeal, it just might be a perfect addition to your collection. 

Mechanical Properties Of Steel

Next, let’s take a look at the mechanical properties of this material. While these properties also vary based on the grade of stainless steel you’re working with, you can easily get an overview that looks like this:

  • Strength: Tensile strength on stainless steel is quite solid. It easily withstands high levels of applied stress without deforming or losing its original properties. Note, of course, that austenitic stainless steels usually have lower tensile strength compared to the other classes. 
  • Hardness: Stainless steel can have varying levels of hardness depending on the specific grade and heat treatment. Hardness is an important property for resistance to wear and abrasion. Some stainless steel grades, such as martensitic stainless steels, can be hardened to achieve high levels of hardness.
  • Ductility: In general, stainless steel is ductile. You can stretch and form it without fracturing, making the material ideal for numerous manufacturing processes. 
  • Toughness: As expected, stainless steel is also quite tough. When faced with sudden impact, it absorbs the energy and maintains its form. Just as well, stainless steel is known for its resistance to brittle fracture and its ability to withstand stress. 
  • Fatigue Strength: When it encounters cyclic loading or repeated stress, stainless steel also does well to maintain its original form. 
  • Elasticity: Of course, stainless steel deforms under pressure and will return to its original shape once that stress is taken out. There are no permanent shape changes when it comes to stainless steel and stress, and it is always possible to revert its effects. 
  • Wear Resistance: Stainless steel alloys can exhibit good wear resistance, depending on their composition and surface treatment. Hardened stainless steel grades can have excellent resistance to abrasion and wear.

Aluminum vs Steel: How Are They Manufactured?  

aluminum manufacturing

Next, we go into the processes of manufacturing both materials to understand how they work. 

Aluminum: Manufacturing Process

When it comes to manufacturing aluminum, you have to go through several steps – ranging from extraction and refining to casting and smelting. Below is a breakdown for you:

Bauxite Mining: 

First, you extract bauxite – the raw material that forms the ore of aluminum. Bauxite is usually mined in open-pit mines with some pretty heavy tools. Once it is extracted, it is moved to a processing plant. 

Bayer Process: 

The next step is the Bayer process, which the bauxite ore needs to undergo. Here, the ore is crushed and mixed with a solution of sodium hydroxide. With this process, the aluminum hydroxide is separated from impurities in the ore, thus providing a solution that contains dissolved alumina. 

Precipitation and Calcination: 

When gotten, the alumina solution is cooled and made to undergo precipitation. Here, the aluminum hydroxide is essentially formed for the first time. After it is precipitated, the aluminum hydroxide is heated in a calcination kiln to take out water and convert it to alumina. 

Smelting: 

The alumina is placed in a smelter and smelted. In this process, it is dissolved in molten cryolite within an electrolytic cell. Electric current is introduced thanks to an iron cathode and a carbon anode, thus causing the ions to be reduced and deposited at the cathode as molten aluminum metal

Casting: 

The casting process will involve forming the aluminum into different shapes, based on the intended function. Casting can usually be done in two ways:

Continuous casting: Here, the molten aluminum is poured continuously into a water-cooled mold. It is allowed to solidify, then forms a continuous strand. This strand is then cut into the perfect length.

Billets or Ingots: For this casting form, molten aluminum is poured into molds to form billets or ingots – essentially, solid blocks or cylinders made of aluminum. They can be further processed into different products through additional manufacturing processes.

Rolling or Extrusion: 

Whatever it is your form will need to undergo extrusion or rolling to shape it into the right form. With rolling, you pass the aluminum through different rollers to cut its thickness and produce aluminum foils, sheets, or plates. 

But, with extrusion, you force the material through a die to produce a profile with complex cross-sectional shapes – rode, tubes, etc. 

Heat Treatment: 

In some cases, an aluminum product might need to undergo heat treatment to enhance its mechanical properties. From quenching and tempering to annealing and precipitation hardening, this is a fairly important step in determining the final product. 

Surface Treatment and Finishing: 

This is a fairly optional step, where products might undergo finishing and surface treatment processes to improve their durability and appearance. 

Fabrication and Assembly: 

Then, you can put the finished aluminum products through additional fabrication processes -such as cutting, bending, welding, or machining. This helps to create the final components or assemblies that allow the material to work in different functions. 

While all of these steps vary based on the final desired product, you want to ensure that you incorporate as many of them a s possible.

How Is Stainless Steel Made?

making steel

Stainless steel also has a manufacturing process that involves several steps. Some of those include the following: 

Raw Material Preparation: 

First, you prepare the raw material itself. Stainless steel comes with the main iron ore material, as well as add-ons like chromium, nickel, and other alloying elements. They are carefully selected and analyzed, with their chemical compositions making them especially adept. 

Melting: 

Once the raw materials have been selected, they’re melted in an electric arc or induction furnace. This process requires a significant temperature if you hope to achieve the right alloy composition. And, to achieve the desired stainless steel grade, you’d need to add alloying elements to the molten metal.

Casting: 

After it reaches the right composition, the molten metal is cast into molds to form large billets or ingots. Generally, a billet aluminum vs steel strength is usually in the same range. As long as they are cast properly, you shouldn’t have a problem.

Hot Rolling:

The billets or ingots are then reheated and hot rolled into large slabs, coils, or blooms. The hot rolling process involves passing the stainless steel through different rolling mills, which cut the material’s thickness and shape it. 

Note that you can repeat the process several times as you hope to achieve the right specifications.

Cold Rolling: 

Next, you take the stainless steel through cold rolling – another process that reduces the steel’s thickness and refines its surface finish. 

Performed at room temperature, cold rolling helps to optimize the stainless steel’s strength, surface smoothness, and hardness. 

Heat Treatment: 

There are several heat treatment steps that can help to improve the mechanical properties of stainless steel – from annealing to tempering and quenching. As long as they are applied properly, they will be able to achieve the right strength and hardness levels. 

Surface Finishing: 

You can also put your stainless steel material through different surface finishing processes to optimize its performance and rust resistance. Steel vs aluminum rust is also comparable, as long as the surface finishing process is done right. 

Inspection and Testing: 

All through the manufacturing process, you want to make sure that you inspect and test the stainless steel material to ensure that it meets the required quality standards. We recommend that you especially watch out for defects using non-destructive testing methods. 

Cutting and Fabrication: 

The stainless steel products are cut into desired lengths or shapes using cutting tools, such as shearing machines or laser cutting equipment. The stainless steel can then be further fabricated through processes like bending, welding, machining, or assembly to create final components or products.

Recycling: 

Stainless steel is highly recyclable, and scrap or used stainless steel products can be collected, sorted, and recycled back into the manufacturing process. Recycling stainless steel helps conserve resources, reduce waste, and minimize environmental impact.

Aluminum vs Steel: What Are They Best Used For? 

applications

Next, we need to look at both materials and their functionalities to understand how they differ fundamentally. 

Construction & Architecture

First, let’s examine the applications of both materials in the architecture and construction space

Primarily, stainless steel is used to build components like roofing, facades, and cladding. It is strong, aesthetically appealing, and resistant to corrosion. 

On the flip side, aluminum is used to construct things like windows, doors, and curtain walls thanks to its lightweight build and flexibility Now, to be fair, you can get converging lines such as an aluminum vs steel fence or cladding. On this front, focus more on the characteristics that mean more to you.

Consumer Products

Next, we look at consumer products – where we consider things like the aluminum vs steel trailer and the aluminum vs steel bike. 

Both materials are used to make consumer products. However, while aluminum is primarily applied due to its durability and aesthetic appeal, stainless steel is better suited for products that require hygienic properties, easy maintenance, and resistance to corrosion and staining. 

Automotive & Transportation 

In the automotive space, stainless steel is used to make materials such as grills, exhaust systems, and decorative elements. These components take advantage of the material’s strength, corrosion resistance, and aesthetic appeal. 

On the flip side, aluminum’s lightweight build and impressive strength-to-weight nature make it useful for building components such as integral components for automobiles, trains, planes, and more.  

When comparing equal components like the aluminum vs steel wheels or aluminum vs steel driveshaft, availability, as well as the aluminum vs steel price, should help you to make a clear decision here. 

Unique Stainless Steel Applications 

Medical and Pharmaceutical Equipment: You can find stainless steel in pharmaceutical and medical equipment manufacturing thanks to its hygienic properties and ease of sterilization. From surgical instruments to medical devices and implants, the material is used to make a broad array of items.

  • Oil and Gas Industry: With optimal corrosion and temperature resistance, stainless steel is used to make fittings, pipes, valves, and other items that are used in the oil and gas field. 
  • Chemical and Petrochemical Industry: Stainless steel is also perfect for developing components for reactors, tanks, heat exchangers, and more in the chemical and petrochemical industry. 
  • Food and Beverage Industry: Finally, the material’s hygienic properties and corrosion resistance make it a great fit for developing processing equipment, brewing equipment,m and other components that are used in the beverage and food industry.

Unique Aluminum Properties:

Packaging Tools: Aluminum can be used for packaging materials thanks to its formability, lightweight properties, and preservative functionalities. Whether it is food containers or packaging for pharmaceutical products, the material is clear. 

  • Electrical Applications: With optimal conductivity and lightweight properties, aluminum is also used in the electrical industry. From making wires and busbars to transmission lines, the material is viable.
  • Industrial Equipment: Aluminum is utilized in various industrial equipment and machinery due to its strength, corrosion resistance, and lightweight build. It is used in manufacturing equipment, machine components, scaffolding, and material handling systems.

When you consider the areas where both materials converge, you want to note several factors before making a choice – such as the cost of aluminum vs steel, the aluminum alloy vs steel availability, and much more. 

When you find the material that works best for you, stick to them. Fortunately, you never have to worry about material compatibility when you’re working with KDM Fabrications. Whether you’re purchasing aluminum or stainless steel, rest assured that we will be able to help get the best in quality materials straight to you. 

From providing a simple and reliable delivery service to offering a consultation, we’re your all-round partner in material sourcing for stainless steel and aluminum. Give us a call, and let’s see how we can help you.

Aluminum vs Steel: What To Consider For Cost-Efficiency 

eco friendly

As you can imagine, stainless steel and aluminum will also vary on the cost parameter. Both materials are very distinct, and this means that their prices will also differ. 

On a volume basis, aluminum is actually less expensive than stainless steel. However, as you probably know, the prices can easily change based on several factors. To ensure proper cost savings, here are some strategies you could employ: 

  • Material Selection: Carefully analyze the specific requirements of your project and select the most appropriate material for you. Since different material grades and alloy vary in cost, finding the right mix will be crucial to maximizing your savings. 
  • Optimize Volume & Quantity: You will most likely be able to get volume discounts if you purchase large amounts of stainless steel or aluminum. If you need to, take advantage of this as well. 
  • Standard Stock Sizes: Check if the available standard stock sizes of stainless steel or aluminum will meet your requirements. Standard sizes are usually more readily available and can be cost-effective compared to the custom size options.
  • Material Efficiency: Also, remember to optimize your material’s design and reduce waste in order to get the most cost-efficient setup. We can work closely with you to ensure that your material is used efficiently, cutting down on scrap and reducing overhead costs. 

All in all, being able to determine the steel vs aluminum price and how much to pay for each will undoubtedly be important as you hope to save and cut costs. Still, remember that in your mood to optimize the price of steel vs aluminum, you shouldn’t compromise the quality of the product itself under any circumstances. 

Aluminum vs Steel: Which Metal Option Is Greener? 

Comparing aluminum and stainless steel on the basis of their environmental impact is a complex process that depends on several factors. Some of them include: 

Energy Consumption: 

Generally, aluminum requires more energy for production compared to stainless steel. Aluminum’s production process is more energy-intensive, contributing to higher greenhouse gas emissions overall. 

Recyclability: 

Aluminum and stainless steel are both highly recyclable. However, you should note that you will need significantly less energy to recycle aluminum compared to its primary production. Nevertheless, the high recyclability of both materials contributes easily to their general sustainability. 

Overall Durability: 

Both materials are known to be durable and resistant to corrosion – meaning that you should be able to use them for long. However, aluminum will most likely require more protective coatings or surface treatments to optimize its corrosion resistance – a step that will affect its sustainability.  

So, while we can debate the steel strength vs aluminum metric, aluminum’s need to be more coated does affect its eco-friendliness.

Material Weight: 

On the aluminum vs steel weight comparison, you’ll find that aluminum is generally lighter than stainless steel. Its lightweight build directly contributes to fuel efficiency and a drop in energy consumption as it is being moved from place to place. 

As the factors show, both materials are quite even on the sustainability front. We recommend conducting a Life Cycle Assessment (LCA) to help provide a comprehensive evaluation of their environmental impact across the board. 

An LCA considers a material’s entire life cycle, from raw material extraction to production and even end-of-life disposal. It factors components like greenhouse gas emissions, energy consumption, and water usage to determine the material’s true sustainability levels. 

All in all, however, both materials have environmental impacts that vary based on their production methods and recycling states. 

Conclusion 

Comparing stainless steel and aluminum for your project can be a daunting task. You need to take a broad range of actors into consideration. Generally, most experts will recommend getting a consultation and expert views to learn more about how the materials work. 

At KDM Fabrications, we will be able to help you understand the implications of your choice between both materials and help you make the right decisions across the board. Give us a call, and we’ll be able to help you out. 

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