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Is Aluminum Stronger than Steel?

Photo collage of different types of aluminum and steel.

No! When compared to aluminum, stainless steel is much heavier and more robust. A few aluminum grades are so strong that they are often compared to the strongest steels. Still, when comparing identically sized samples of the strongest steel alloys and aluminum alloys, steel will typically be the stronger material.

It’s not common practice to instantly think about aluminum when discussing or working with durable materials. Many people think of aluminum products like tin cans, aluminum foil, and foldable furniture as not necessarily things that prove strength.

On the contrary, if you’re looking for a sturdy material, steel is perhaps the first thing that comes to mind. After all, steel is used for virtually every aspect of modern life, from safety rails and car chassis to building beams and even naval vessels. Let’s look in-depth at the difference in strength between steel and aluminum, their uses, alloys, and more as you continue reading. 

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Is Aluminum Stronger Than Steel?

Recycling aluminum or metal empty cans top view.

A few aluminum grades are so strong that they are often compared to the strongest steels. Yet, when comparing identically sized samples of the strongest aluminum alloys and steel alloys, steel will typically be the stronger material. One of the strongest aluminum alloys, AA7068-T6, and one of the strongest steel alloys, AISI 1080, have maximum tensile strengths of 710 and 965 MPa, respectively.

Their Yield Strength and Ultimate Tensile Strength are compared here. However, when compared to steel in terms of their strength-to-weight ratios, aluminum alloys come far closer to steel than you may think. They can even perform better than steel in distinct situations.

Strength alone is not enough of a measure for selecting a material, as seen here. Aluminum may be the superior option if you need a very strong material but have weight restrictions, whereas steel may have the upper hand if you need a very strong material but has size restraints.

Materials Strength Testing

Without a common definition of “strength,” it is difficult to make meaningful comparisons between the various materials. The ability of a material to sustain a given load (also known as force or stress) before showing visible signs of deformation or strain is a common definition of its strength. Typically, these curves are created by applying tensile tension to a sample of material, such as aluminum, and allowing it to deform until it ruptures.

Megapascals (MPa) or kilopascals (kPa) are commonly used to measure stress and, by extension, material strength (ksi). The degree of deformation is expressed as a percentage of the undistorted length.

Strength at Yield vs. Absolute Strength

Yield strength and ultimate strength are featured by the stress-strain curve depicted above. The term “yield strength” is used to describe the greatest stress a material can sustain before yielding plastically (permanently). All of the deformations that have occurred in the material up to this stage can be undone by removing the load.

Compare this to stretching a rubber band beyond its yield point; once the tension is removed, the band returns to its original shape. Instead, ultimate strength refers to the max force we can exert on the material before it breaks. Between the yield strength and the maximum strength, all deformation is plastic deformation.

To do this stress-strain test, we can use a mixture of forces. Tensile strength, or tearing the material apart, is the most prevalent method.  We can determine the ultimate tensile strength of a material with this method, making it possible to use that value as a standard by which other strengths are judged.

Pressure, twisting, impact, as well as shearing, are some other forms of loads that we can apply to materials to determine how they hold up under stress.

Aluminum Comes in a Wide Variety of Strengths and Grades

Metal profiles and tubes, different stainless steel products.

Ultimate tensile strength in aluminum is notoriously difficult to predict. This is because the strength of various classes of aluminum varies based on the specific alloying elements used and in what quantities. Pure aluminum is a rather soft metal, but certain of its alloys can acquire remarkable strength.

Where to Use the Most Durable Aluminum Alloys?

New aluminum fence in black color.

Steel has been superseded by some of the strongest regularly used aluminum alloys. That’s because they’re not only strong enough for the job but also have some benefits that steel doesn’t. These features include increased resistance to corrosion and low relative weight.

Check your assumptions about strength with context. When comparing steel to aluminum, the former is typically much stronger in both the vacuum and by volume. Aluminum, like steel, has many desirable qualities, but strength is only one of many that must be considered before settling on a material for a certain project.

Important Features of Stainless Steel and Aluminum

Stainless steel pipes on a white background.

Stainless Steel

Many quality tiers of stainless steel are commercially ready. Each series of grades is given a numeric grade that matches the series number. Steel grades are arranged numerically based on their makeup, physical qualities, and uses. Stainless steel 304 and 316 are the most common types.

Aluminum

  • Non-magnetic
  • Low in density
  • A type of alloy that doesn’t contain iron is called “non-ferrous.”

Aluminum is often alloyed with other metals to increase its tensile strength and acquire other desirable qualities. Among the most popular aluminum alloys are 3003 and 3004.

Which Should I Use, Aluminum or Stainless Steel?

Stainless steel profiles and tubes. 3d illustration

The qualities of these metals make them useful in production. However, the unique characteristics of each metal play a significant role in finalizing the selection process.

Principal Benefits of Each Metal

Aluminum

  • Aluminum has high ductility and is quite malleable.
  • High Electrical Conductivity
  • Minimalist in Bulk

Steel

  • High Tensile Strength, Heat Resistance, and Stainless Steel
  • Very Long Lasting
  • Simple Upkeep

Important Distinctions Between Aluminum and Stainless Steel

Strength

When compared to aluminum, stainless steel is much heavier and more robust. Aluminum weighs just about a third as much as steel. Aluminum outperforms stainless steel in terms of strength-to-weight ratio.

Conductivity

Due to its thick oxide coating, steel is a poor conductor of electricity. Aluminum, on the other hand, has excellent thermal and electrical conductivity.

Price

Compared to stainless steel, the price of aluminum is higher due to its lighter weight. If you consider the cost per unit of output, however, Aluminum is the clear winner.

The Ability to Withstand High Temperatures

Stainless steel has a much higher resistance to heat than aluminum, with a melting point of 2500 °F versus aluminum’s 1220 °F. Aluminum also becomes very soft at temperatures as low as 400 °F. But aluminum outperforms steel at sub-zero temperatures.

Aluminum’s tensile strength improves with decreasing temperature, while steel’s brittleness increases.

Resistance to Corrosion

While aluminum won’t rust, it will corrode in the presence of salt. Stainless steel is not prone to rust or corrosion. Plus, stainless steel’s lack of pores makes it exceptionally corrosion-resistant.

Distinct Uses for Aluminum and Steel

Metals such as aluminum and steel may be found practically anywhere. You can probably find something that contains one of these metals wherever you go. Here are some typical settings in which stainless steel and aluminum are used.

Functions of Aluminum

Close-up view of aluminum door window handles, against a blurry background.

Because of its low weight and high corrosion resistance, aluminum is frequently used in the transportation sector.

  • Automotive
  • Metal tracks used by trains
  • Airplanes
  • Spaceships

As a result of its low density, high malleability, and excellent conductivity, aluminum has widespread usage in the electrical sector.

  • Transmission lines that carry electricity over long distances

Architectural applications of aluminum take advantage of the material’s malleability, high strength-to-weight ratio, and low cost.

  • Doors and handles
  • Casement and awning windows

Construction of tall buildings and the widespread usage of aluminum in home appliances due to its high thermal conductivity

  • Dishwashers
  • Washers and Dryers
  • Refrigerators

Steel’s Wide Range of Uses

Due to its high corrosion and heat resistance, stainless steel is frequently used in cooking utensils.

  • A place to wash dishes or prepare food
  • Cutlery
  • Kitchen workstations

Stainless steel’s resistance to corrosion makes it a common material for medical implements.

  • Forceps
  • Metal and ceramic artificial joints
  • Scissors

Stainless steel’s strength and durability make it useful in other areas of the building industry as well.

  • Bridges
  • Structures set in stone and metal
  • Buildings

Because of its durability and resilience to high temperatures, stainless steel is also widely utilized in the transportation sector.

  • Structures for Motor Vehicles
  • Automobiles that run on rails
  • Engines

A set of heads in a plastic chrome light stand for the repair of engines and cars.

Both stainless steel and aluminum share features that make them desirable building materials. Aluminum and stainless steel have distinct properties, and it’s helpful to be aware of those variances. While stainless steel is not employed in electrical applications due to its weight and lack of conductivity, aluminum is. 

Stainless steel, on the other hand, is often used in places where high levels of strength, heat resistance, and corrosion resistance are required, such as in engines and processing equipment.