You’re probably familiar with the existence of pure aluminum as one of the main chemical elements of the periodic table. If you’re environmentally conscious, you’d also know that aluminum has excellent recycling properties alongside glass and steel. It’s startling that almost 75% of all aluminum produced is still used today.
The never-ending life cycle of aluminum products reveals a lot about their valuable mechanical properties. However, producing aluminum in its pure form is extremely labor-intensive. If you’re not a welder, fabricator, or manufacturer, there’s a small chance you’d know that the Aluminum Association classifies aluminum alloys based on their composition and capabilities. In this guide, we’ll be discussing the importance of aluminum alloys, the various types, and the most common applications.
The Evolution of Aluminum and its Impact on Everyday Life
It might seem strange, but aluminum was discovered in 1807, and it wasn’t until the early 1900s that a commercially viable production process was established. When first discovered, aluminum was as precious as gold is today and was used to manufacture expensive cutlery and the finest jewelry. Following the discovery, there was a lot of debate surrounding aluminum’s name and production process. In 1845, a German scientist brought to light the groundbreaking aluminum property of lightness while in 1886, two metallurgists dissolved aluminum oxide in molten cryolite and pulled the aluminum with electrolysis. In the late 1800s, an Austrian scientist further refined the aluminum extraction process, and it soon became one of the most precious commodities.
As the aluminum manufacturing industry started to gain a stronghold in the market, mass production began to soar. For example, aluminum production was less than 200 tons in 1885 and skyrocketed to more than 22 million tons in 1998. Despite initial failures, the discovery of aluminum and subsequent efforts to make it more financially accessible to the market proves that the human mind never settles until a vision is fully realized.
Today, aluminum is a core component of the manufacturing industry, providing equipment with corrosion resistance and rigidity. In the automotive industry, aluminum has been used to manufacture automobiles for more than a hundred years. Kitchen appliances would not be as safe and sturdy to use without the addition of aluminum in the manufacturing process. The applications of aluminum in our lives are endless, indicating just how valuable its characteristics are compared to other metals.
Types of Aluminum Alloys
Aluminum is a powerful substitute for steel since these two metals share many of the same properties. Just like steel, aluminum can be composed of many other materials, particularly manganese, copper, silicon, magnesium, and zinc. For this reason, aluminum can be grouped into specific aluminum alloys, which are further classified through a unique identification system developed by the Aluminum Association.
Aluminum alloys are further categorized into groups based on their ability to endure mechanical and thermal treatment. The two most prominent aluminum alloy categories are wrought and cast aluminum. Wrought aluminum alloys can be divided into heat-treatable and non-heat-treatable.
The wrought alloy designation system is comprised of a 4-digit identification process. The first digit pinpoints the principal alloying element, the second digit, if different from 0, shows the modification of the specific alloy, and the third and fourth digits are arbitrary numbers used to identify the alloy in the series. Heat treatable alloys can only be strengthened by the addition of extreme heat and include alloys in the 2xxx, 6xxx, and 7xxx series. The most common thermal treatments deployed to harden heat-treatable alloys are Solution Heat Treatment and Artificial Aging. Typically, alloys are heated to a specific point to absorb the elements and then cooled to freeze them in the right place.
- 2xxx Series: Aluminum alloys that belong in the 2xxx series consist of copper ranging from 0.7 to 6.8%. Their primary characteristics are high strength and high performance and they are excellent for withstanding extremely high temperatures, particularly in aerospace and aircraft industries. Some alloys are non-weldable due to their sensitivity to hot cracking and stress corrosion.
- 6xxx Series: With the addition of magnesium and silicon, this series of aluminum alloys is used primarily in welding fabrication. Magnesium and silicon make aluminum heat-treatable. However, these alloys are naturally crack-sensitive and shouldn’t be welded without any filler material. Adding filler material during the arc welding process will prevent any heat-cracking issues.
- 7xxx Series: This series contains alloys with aluminum and zinc, and they are some of the highest-strength alloys. Similar to the 2xxx series, these alloys can be used in aircraft and aerospace industries, but are usually unsuitable for arc welding.
Non-heat treatable aluminum alloys gain the optimum mechanical properties and strength through Strain Hardening, which applies cold working for strengthening purposes. This aluminum alloy category includes wrought alloys in the 1xxx, 3xxx, and 5xxx series.
- 1xxx Series: This series contains aluminum alloys in their purest form. While they are weldable, their narrow melting range requires special considerations for an effective welding procedure. These alloys are typically preferred in the piping and chemical tank manufacturing industries but are usually avoided for structural applications due to their poor mechanical properties.
- 3xxx Series: This series consists of aluminum alloys containing manganese, which provides moderate strength, corrosion resistance, and good formability. They are strong enough for high-temperature applications, especially in kitchen manufacturing, vehicles, and power plants.
- 5xxx Series: With magnesium being the primary alloying element, alloys in this specific series are readily weldable, high-strength, and primarily used in transportation, shipbuilding, bridge building, and pressure vessels.
Cast aluminum alloys include both heat-treatable and non-heat-treatable alloys. This group includes aluminum alloys in the 2xxx, 3xxx, 4xxx, and 7xxx series.
- 4xxx Series: These are alloys that contain aluminum and silicon, and they can be both heat-treatable and non-heat-treatable. Since silicon reduces aluminum’s melting point and improves fluidity, it can be used predominantly as a filler material. Silicon also prevents brittleness since it’s often enhanced with magnesium or copper. This makes this alloy series perfect for welding wires and structural applications.
What to Look for in An Aluminum Service Center?
A reputable aluminum service center should have the expertise, technology, and customer service in place to assist you with your aluminum alloy needs. Different aluminum service centers will specialize in different aluminum alloys depending on the end-use, but the great majority will offer the most common series. If you’re in the manufacturing industry, you know firsthand that aluminum is the most inexpensive, ductile, malleable, and versatile metal for various applications. Aluminum can be found in our homes, aerospace, and various other structures we admire every day, and the benefits to society are tenfold.
