Know Your Metals: An Introduction to Aluminum Alloys

Aluminum is the most common metal found on earth, but the metal can be difficult to work with, prior to adequate alloying. Fortunately, aluminum is quite accepting of the alloying process. What it means is that the metal can be easily mixed with alloying elements/compounds like zinc, copper, magnesium, silicon, magnesium-silicon compounds, manganese, lithium, etc.

Industrial products manufactured from aluminum alloys can be just as strong or as malleable as the manufacturer needs them to be. Decades of research and experimentation with aluminum alloys have transformed aluminum into the most cost-effective metal across all industries today. There are still limitations, of course, but the scope of both present-day usage and future improvements is huge with aluminum alloys.

Wrought Aluminum Vs Cast Aluminum: Chemical Composition

Aluminum alloys can be separated under two broad classifications based on their respective chemical compositions:

  1. Wrought aluminum alloy: Alloying elements are not allowed to exceed 4%.
  2. Cast aluminum alloy: Alloying element(s) generally have a higher than 22% presence in the composition.

Wrought aluminum alloys are superior in almost every way, as compared to cast aluminum alloys. To put that into better perspective, take a look at the several advantages that wrought aluminum alloys have over cast aluminum alloys.

  • Wrought aluminum alloys can reach both tensile strength and yield strength higher than any cast aluminum alloy.
  • Almost no chance of casting defects and greater corrosion resistance means better structural integrity.
  • Extruded wrought aluminum alloys provide engineers with endless customization options, especially thanks to the alloy’s superior ability to support cross-sections.

Aluminum Alloy Manufacturing

Aluminum ingots are melted down and then smelted in with the right percentage of each alloying element. The manufacturer usually follows temperature and chemical composition standards, as have been set for aluminum grading in the United States. For custom orders, manufacturers should be able to make alterations that are more in line with client instructions. After smelting, the liquid aluminum alloy is then poured into a billet. To attain the desired shape and formation, manufacturers will roll, extrude, and forge as necessary from thereon.

Aluminum Alloy Grading System: What do the Numbers Mean?

The best way to explain the aluminum grading system is with an example. With extruded aluminum channel 6061, like in this linked aluminum stock, the four-digit number 6061 can be broken down in the following manner:

  • 1st number (6) denotes the primary alloying element(s), which in this case are magnesium and silicon.
  • 2nd number (0) represents modifications made to the primary alloying agent(s), which in this case is none.
  • 3rd & 4th numbers (61) identify it as a unique alloy within the 6xxx series of aluminum alloys.

6061 is accepted universally as the most adaptable aluminum alloy because it’s tough and corrosion-resistant, but without the brittleness of rigidity. In case your business is involved in renovation and architecture, use extruded aluminum channel 6063 instead for better results. Keep in mind that there are 7 grades for aluminum alloys from 1xxx – 7xxx, so know your options before finalizing your choice.