The Strength of Aluminum

From Automakers to the U.S. Military, Those in the Know Trust Aluminum

Quick Read

If you’re like many people, when you hear the word “aluminum”, you think of everyday convenience items that, while incredibly useful, don’t exactly convey a high-strength image. And it’s true – aluminum is a highly versatile metal – meaning it can be processed to be thin, lightweight, bendable and even crushable by human hands.

What’s less well-understood is that aluminum can also be some of the toughest stuff on earth. Often, the metal is used in applications where high-strength and durability are the most important considerations – from cars and trucks to building material to military vehicles. You likely trust aluminum to keep you safe and secure dozens of times a day without even knowing it.

Take-Away Facts

• The Key to Auto Safety:Automakers are increasingly turning to aluminum as part of the multi-material mix to increase vehicle fuel efficiency while maintaining strength and safety. Every aluminum-intensive vehicle ever crash tested by the National Highway Traffic Safety Administration has earned a 5-star safety rating.
• High-Strength Aluminum is Everywhere: High-strength aluminum alloys are used in hundreds of everyday applications where strength and durability are essential – from planes to trains, buses to trucks – even some of the world’s tallest skyscrapers.
• Extreme Applications: Aluminum is also used by the U.S. military, NASA and others to build vehicles and structures capable of thriving in some of the harshest conditions imaginable. 
• The Chemistry of Strength: By adding elements like silicon, magnesium and lithium to pure aluminum and through special processing techniques, aluminum can be engineered to be as strong if not stronger than some steel.

Everyday Strength 

Aluminum is about one-third the weight of steel, meaning parts can be made thicker and stronger while still reducing weight in vehicles and other applications. Depending on the alloy and processing technique used, pound for pound aluminum can be forged to be just as strong if not stronger than some steel.

Aluminum is already the second-most-used material by automakers, so your car or truck likely has a lot of aluminum in it right now, protecting you from hazards on the road. Engineers know how to work with aluminum to make parts that perform as well or better than steel parts – all while reducing vehicle weight. Aluminum is highly effective at absorbing crash energy, protecting passengers in the event of an accident. And lighter aluminum vehicles improve performance.  Better handling and shorter stopping distances help drivers avoid accidents to begin with.

Aluminum is used for window frames and curtain wall in some of the world’s tallest skyscrapers – maybe even the office building you’re sitting in right now. This versatile metal is used to make planes, trains, buses, trucks – even ocean liners!

In short, every day, people around the world trust the strength of aluminum – whether they know it or not.

Extreme Durability

In addition to “everyday” applications, aluminum’s strength and durability is also trusted for some of the most extreme uses imaginable.Designers know that high-strength aluminum alloys can handle some of the harshest conditions on earth – and beyond. 

• U.S. Army: The U.S. Army has trusted aluminum for decades to help protect our troops. The high-strength, crash-absorbent metal is used in the Humvee (HMMWV), HEMTT and Bradley Fighting Vehicle to reduce weight, resist rust and be reliable under tough conditions. Aluminum armor plate is even used to resist explosives and other attacks.   
• NASA: It’s no exaggeration to say that modern space travel would not be possible without aluminum. The metal was widely used in the space shuttle program and NASA chose a high-strength aluminum-lithium alloy to make the new Orion spacecraft, which will someday take humans to Mars.
• U.S. Air Force: After replacing older wood, steel, wire and fiber aircraft during WWII, high-strength aluminum alloys have become among the most commonly used materials to make military aircraft. Indeed, the airframe for the famed fighter jet – the F-16 – is 80% aluminum.  
• Shark Cages: Even when facing one of nature’s fiercest predators – the strength of aluminum is trusted. Aluminum is the popular choice for shark cages because the metal is more buoyant than alternatives and won’t corrode in salt water. Aluminum bars are more than strong enough to protect divers from direct attacks from Great White and other sharks.      

The Secret to Strength

The secret to aluminum’s strength comes down to chemistry. Pure aluminum is mixed with other elements to create high-strength alloys.Common additives used to increase the strength and formability of aluminum include silicon, magnesium and copper. Aluminum-zinc alloys are some of the strongest alloys available today and are commonly used by the automotive and aerospace industries.

Aluminum can be further strengthened through processing– hot rolling or cold rolling. Some alloys are made stronger by heat-treating followed by rapid cooling. This process freezes the atoms in place strengthening the final metal. Alternatively, some aluminum is “cold worked” -- usually by rolling, stretching forging or drawing -- to make it stronger. This process inhibits the movement of atoms relative to each other, strengthening the finished product.

The strongest aluminum alloys – 7000-series alloys – can reach strengths in excess of 72,000 pounds per square inch.  A 1.2-inch aluminum wire made from this alloy could suspend a fully-loaded tractor-trailer in the air.