It is safe to assume that the world as we know it would be a whole lot different without aluminum since it’s an incredibly important metal. It’s used to make a wide variety of things, ranging from cans, kitchen utensils, beer kegs, and window frames, all the way to airplane parts and supercar bodies.
However, aluminum is a metal. And we know that metals like iron or steel all rust. But, like them, does aluminum rust in water? Or at all? It would spell disaster for a lot of industries if it did - or would it? In this article, we hope to answer this question, along with a few others that might arise.
Does Aluminum Rust or Corrode? Does It Have Corrosion Resistance?
“Why does aluminum not rust?” is the wrong question to be asking when approaching this topic. Instead, we need to be asking, “How long does it take aluminum to rust?” The long and short of it is that aluminum rusts as it’s no super-metal. Even stainless steel, famed for its rust resistance, rusts. Before we all panic, though, let’s try to understand what rust really is.
A Look at Rust and Corrosion
What we call rust refers mainly to iron. When exposed to the atmosphere, the outer layer of the iron oxidizes, forming a red oxide layer that we call rust. This chemical reaction is basically corrosion. So, does aluminum rust outside? Yes, it does. However, unlike iron and its alloys, this isn’t a wholly bad thing.
Pure aluminum and aluminum alloys, when they corrode, form a thin layer of oxide on the surface. Unlike iron oxide rust, aluminum oxidation is not flaky and does not come off. Instead, it hugs the surface and produces a protective coating that does not let the aluminum corrode any further within.
This layer of “rust” thus formed is chemically inert. It does not react with anything, for the most part, making it excellent protection against further corrosion. Ironic, we know, but that is how it works. This process takes a while, depending on the intensity of environmental factors assailing the metal. However, do keep in mind that aluminum oxidizes faster than steel because it is a lot more reactive to oxygen. It will stop when the aluminum atoms in the outer layer have all reacted and oxidized.
Corrosion, by its very nature, eats away at the metal, so it gets progressively weaker over time. Furthermore, there are different types of corrosion at play. We will look at the most dangerous variants of these in the following section.
Pitting Corrosion and Its Effects On Aluminum
Pitting corrosion is a kind of galvanic corrosion. This only happens in metals that have a passive layer of protection, like stainless steel and aluminum. The passive layer protects the metal from corrosive agents in the atmosphere until they get removed by accidental means like scratching.
For example, steel usually has a protective layer of zinc on it. This zinc coating itself is protected from the elements by the layer of patina it develops. For aluminum and its alloys, this protective coating can be alclad, alodine (a kind of an organic coating like paint or powder), or achieved via anodization.
The corrosion usually affects a very small area, though it grows over time if left unchecked. Because pitting corrosion grows into the metal, detecting it with a look is nearly impossible. You won’t even be able to tell, but the aluminum within will lose all its structural integrity. Given how the most important things in the world, like airplanes, are made from aluminum products, this type of corrosion is the worst thing that can possibly happen since it endangers lives.
On a smaller scale, it is no less troublesome. If you’re wondering, ”Does aluminum wire rust?”, the answer should be quite clear now. Aluminum corrosion occurs in every aluminum product, even wires, and this can have some undesirable effects. Corrosion in wires causes extra resistance, leading to heating up and eventual failure. On important equipment, this can be especially damaging. The good thing is that you can call customer service to deal with this.
How Can You Protect Aluminum From Corrosion?
There are a few things you can do to protect aluminum from corrosion. Obviously, the best thing to do is to buy aluminum products that are already protected by a corrosion-resistant or retarding agent. As discussed earlier, there are many kinds of coating to choose from. You can also get them clear coated after you buy them. This stops the environment from doing anything to interfere with the metal and keeps it in pristine condition.
Keep in mind that any anodizing you do will need to be replaced and reapplied periodically. If you use a coat of zinc as a sacrificial layer of protection, it will eventually diminish due to exposure to the elements. The same goes for applied coats. Once you see a hint of corrosion, it is important to take action quickly, lest it spread and cause undesirable results.
If not, there are other strategies that can help you out. The main reason behind corrosion is exposure. Whether it be moisture or corrosive agents like sulfides in the atmosphere, water, or other environmental factors that cause a chain reaction in the aluminum, it always leads to outside causes. So, the best thing you can do is to store your aluminum products safely somewhere indoors. It is preferable to keep them in a climate-controlled room where humidity, rain, or other elements don’t get to it.
If you are dealing with alloys of aluminum, it is important to know the best variant to choose for surviving corrosion. Some alloys, like 5052 and 3003, have much better corrosion resistance than their cousins.
So, does aluminum rust? Yes and no. Aluminum does not rust. This is because rusting is a process limited only to iron and its many alloys. Aluminum does, however, corrode, and this is often equated to rusting. Does aluminum alloy rust? Only if it is alloyed with iron or steel. Otherwise, yes, alloys of aluminum corrode and oxidize but do not rust. Technically.
GET STANDARD AND CUSTOM ALUMINUM PROFILES FROM BK-ALPROF
BK-ALPROF is a top-level aluminum extrusion company. We supply aluminum of different shapes and sizes with value-added fabrication technologies — glazing systems, aluminum beams, extruded aluminum tubes, aluminum angles, custom extrusions. Though we were founded in 1999, we have used the following years to become a respected Russian aluminum profile manufacturer equipped with modern machinery and technology.
Every raw material we use complies with international standards. We also specialize in coating and anodizing aluminum shapes, casting solid extrusion billets, producing translucent structures, etc. All our extrusions are made of alloys 6060 and 6063.