What Metals Rust and Can You Prevent It?

When delivering exceptional sheet metal fabrication projects for our clients, it’s important we understand exactly what properties the metals we use have – so we can work out what will deliver the desired results. Such properties include considering the metals that rust, so we can avoid causing damage to the structures we create. 

If you’re interested in finding out more about what metals rust, we discuss it all in our blog below. Read on to find out more about which metals rust, what metal fabrication companies use to prevent it, and ways you can treat rusting. 

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What is rust?

Rust is a chemical compound made from iron and oxygen. It occurs when a specific type of metal is exposed to oxygen and moisture – such as humidity in the air. The iron atoms in the metal respond to the oxygen and moisture in the air by forming an iron oxide, also known as rust. 

Put simply, rust is a form of corrosion that can happen to any iron-containing metal. Reddish-brown in appearance, the texture of rust will begin rough, and eventually wear in time and become flaky. 

Why is rusting a serious problem?

Rusting can be a serious problem for those working in industries that rely on the application of different types of metals to form structures, or as part of a manufacturing process. These reasons might include:

Structural damage

As a result of the wear and tear rusting creates, it can cause damage to any structures being manufactured with iron-containing metals. For example, as time goes by, the rust will replace parts of the metal with a flaky powder instead which ultimately makes them weaker. 

This can cause problems for structures such as bridges or automobiles, which rely on the strength of the metal they use to hold a considerable amount of weight. 

Reduced inefficiency 

In addition to the damage it can cause to metal structures, rust can also increase the likelihood of inefficiency in products that use metals with iron in them. For example, in some metal structures, magnetism is a key property to ensure it delivers its purpose. 

This includes medical equipment, such as hospital water infiltration systems – which use magnetism to change the physical and chemical characteristics of the water to make it safer. If rust occurs in these systems it will decrease the levels of magnetism in the metals they use. Subsequently, the systems will fail to work as well and won’t be able to produce the same results as they did initially. 

Costly

Rust in metal systems can also cause problems when it comes to the cost spent on repairing them. For example, companies that rely on iron-containing metal (or otherwise known as a ferrous metal) structures will have to account for the possibility of rust occurring. 

In fact, it’s reported that the annual cost of corrosion worldwide is over £1.8 trillion, which is about 3-4% of the world’s Gross Domestic Product (GDP). This means that businesses will have to budget for the cost of rust prevention techniques and treatment, which can have an overall effect on its revenue. 

What metals rust? 

There are several different types of metals that rust, including:

Steel 

Steel is an alloy of iron and carbon, so it is prone to rusting. Typically, steel that has cheap production will also be more likely to rust than steel that has been manufactured to a high-quality standard. But it also depends on the environment the steel is located in. For example, steel is more likely to rust in acidic conditions – such as certain mining operations, than alkaline conditions – like seawater. 

Cast iron 

A combination of iron and carbon, cast iron is likely to rust despite its resistance to wear and tear. Cast iron is typically used in cooking for manufacturing skillets. If it’s left too long in water, such as if the user is soaking it after cooking, it can cause it to rust. To avoid this, it might have a protective coating, such as a carbonised oil called ‘seasoning’.

To find out more about the manufacturing processes of metals, you can check out our guide. 

Wrought iron 

Another alloy of iron and carbon (albeit, a very low amount), wrought iron will likely rust if exposed to moisture and oxygen. Wrought iron is more difficult to produce than cast iron, as it is made by heating and moulding the iron within it. But it also has a smaller chance of rusting than cast iron, so might be the best option to use out of the two.  

Which metals do not rust?

Fortunately for sheet metal fabrication projects, there are still a number of metals that do not rust, including:

Stainless steel

Unlike normal steel, stainless steel does not rust. Whilst it does actually contain iron, it also contains chromium – a corrosion-resistant material. When the stainless steel reacts with oxygen, it creates a protective oxidised layer. As the iron doesn’t get a chance to be exposed to oxygen or moisture because of this layer, it therefore won’t rust. 

Aluminium

As it contains no iron, aluminium will not rust. It is a standalone element on the periodic table that contains nothing but itself. That’s why it is commonly used in outside/outdoor projects and sculptures, such as pergolas and verandas attached to a property. 

Copper and bronze

Bronze is a metal that does contain iron but only in small amounts. A mixture of copper and tin, bronze can react to oxygen but in different ways. For example, it might deteriorate as time passes. Meanwhile, copper is a completely pure element on the periodic table and contains no iron, so it does not rust either. 

How do you prevent metals from rusting?

Fortunately for sheet metal fabrication companies and other businesses that use metal in their manufacturing, there are ways you can prevent metals from rusting.  

Apply a powder coating

One way you can prevent metals from rusting is by applying a powder coating. A powder coating has excellent resistance to corrosion as it creates a barrier between the metal surface and oxygen/moisture, meaning it’s less likely to rust. 

Better yet, it’s a much more cost-effective solution compared to liquid coatings, because it has more longevity and will therefore require less maintenance and upkeep. 

Galvanise the metal

Galvanising metal is the process of applying a layer of zinc to steel or iron to prevent corrosion. If the zinc coating is scratched, the exposed steel or iron will still be protected from rusting by the remaining zinc. 

Similar to powder coating, galvanising metal creates a barrier that prevents the metal from being exposed to oxygen and moisture, and therefore prevents rust occurring. 

Paint the metal and store it properly

As with the above solutions, painting the metal will act as a barrier that protects the metals from rusting. 

Paint also acts as an electrical insulator; slowing down the process of corrosion by slowing the flow of the current. This current encourages a reaction that stimulates corrosion. 

What metals rust: FAQs

Can you remove rust from metal?

Yes, you can remove rust from metal – it just depends on the severity of it and how much it has affected the material. Some ways you can remove rust from metal include:

• Vinegar: This solution is best used on steel or on metal coated in significant rust. Individuals can remove the rust once soaking the metals affected in a vinegar bath overnight. Or, if it cannot be submerged in vinegar, you can soak a cloth and wrap it around the rusted area instead. 
• Potato and soap: You can also use potato and dish soap to remove rust from metal. Slice a potato in half and cover it with dish soap, then rub it on the rust. This creates a chemical reaction in the rust that makes it easier to remove. 
• Lemon and salt: Small amounts of rust can be removed with a combination of lemon and salt. You can do this by coating the layer of rust with salt, and then squeezing lemon juice on top. Let the coating sit for a little bit, then scrub it with the rind of the fruit. Repeat until the rust disappears. 

Can you paint rusted metal?

In theory, it is possible to paint rusted metal, but it’s advisable not to. 

Ideally, you should remove the rust first and then paint, as a coat of paint can be easily damaged or flake off if applied on top of the rust. 

What are the three types of rusting?

There are three different types of rusting that can occur, including: 

• Red rust: Red rust is the most common type of rust you can find on metals.
• White rust: White rust can form when zinc in metals reacts with oxygen.
• Yellow rust: Yellow rust is often found on copper and brass surfaces. 

Choose Salamander Fabrications for Accurate Results

At Salamander Fabrications, we can make your metal sheet fabrication projects come to life – taking protective measures to avoid rusting.  

With services ranging from laser cutting and powder coating, to welding and sheet metal fabrication, we’re here to help provide you with a solution that your business will be proud of. 
Interested in how we can help get your project off the ground? Contact our team of experts today.