Metal Allies: A Guide to Aluminum Grades

aluminum fence

You can’t help but keep looking and admiring some aluminum fences. It is not about the aesthetics, mind you, but how awesome aluminum is as a material.

Aluminum is a metal often found in different alloys. It can be made into something strong and heat-resistant. It is often used as a material for heat transfer objects such as heatsinks. On the other hand, you also have the aluminum foil often used to wrap food to preserve its temperature.

Aluminum is something that your hands can handle. You can crumple and tear it if you want. You also have the frames of mountain bikes that are light yet still tough. So why is there such a disparity? It turns out that aluminum alloys have various grades. Let’s find out what they are and where they are used.

The Three Types

Creating an alloy involves combining two or more metals. Although aluminum itself is a metal, most still call its alloys as aluminum. And these have produced many interesting materials. A lot of these are things you see every day.

Aluminum alloys are split into three types. Commercially pure means that it is at least 99 percent made of aluminum. The other two are dependent on how they can be strengthened: via cold work or heat treatment. The last two types are called non-heat treatable and heat treatable, respectively. To understand better, here are the strengthening methods:

Cold work is done by rolling and pressing on the alloy sheet and at the same time cooling it. This is done to get the desired shape or form of the alloy. Heat treatment happens when the alloy is heated up and mixed with a solute. It is this substance that enhances the strength of the alloy.


The Grading System

The aluminum grading system uses four numerical digits to categorize its alloy composition. The highest grade contains some of the strongest materials you can find. Here are the different grades:

  • 1xxx – The commercially pure fall under this, which is also non-heat treatable. One of the characteristics is how easy you can form the material in your hands. Aluminum foil is a perfect example.
  • 2xxx – Aluminum and copper. The material is tough and lightweight. Frames of light aircraft are made out of this.
  • 3xxx – Aluminum, manganese, and magnesium. Strength lies between 1xxx and 2xxx. Its form can be manipulated easily as well. Heat sinks and soda cans fall under here.
  • 4xxx – Aluminum and silicon. These are easy to melt. Filler alloys used in welding fall under this grade.
  • 5xxx – Aluminum and magnesium. This alloy can be very tough, and corrosion won’t be a problem. Some examples include boat hulls and construction beams.
  • 6xxx – Aluminum, silicon, and magnesium. The strength is also high, but the shape can be altered without much difficulty. Road vehicles are good examples.
  • 7xxx – Aluminum, zinc, and magnesium. The toughness is first-rate. Commercial airplanes are made out of this alloy

Are you curious about where the things around you fall under this grading system? With that kind of variety, it looks like there’s an alloy for everybody. This is the start of a new appreciation for aluminum.

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