Do All Metals Rust?
Metal is often associated with strength and durability. However, over time, the toughest metals can show signs of wear and tear. So do all metals rust?
No, only certain ones do but many can corrode. When working on a project, it is important to understand which metals resist corrosion to ensure longevity.
What is Rust?
Rust and Corrosion are often used interchangeably, but they are not the same thing.
- Rust refers to the reddish brown flaky coating that forms on iron and steel when exposed to oxygen and moisture. It is a type of corrosion that only applies to ferrous metals.
- Corrosion is a broader chemical reaction that causes metal to break down or change form. This may include tarnishing , patina formation or pitting corrosion. Every metal corodes differently depending on its composition and environment.
All rust is corrosion, but not all corrosion is rust.
What Metals do Rust?
Mild Steel - Yes
Mild steel primarily made of iron and is highly susceptible to rust. Without any protective coating (such as paint, powder coating, galvanising), it will rust quickly when exposed to air and water. Surface treatments are essential to slow down the rusting process. It is a cost effective option but exposure to moisture must be controlled.
Stainless Steel - Sometimes,
Stainless steel is made by adding chromium (at least 10.5%) to steel. This reacts with oxygen to form a passive layer that protects the surface from rust. Stainless steel will be corrosion free in most indoor and dry environments. However it can suffer from pitting corrosion in marine or acidic environments.
Aluminium - No
Aluminium does not contain iron. Instead, it forms a protective aluminium oxide layer when exposed to air that shields it from corrosion. It is one of the most corrosion - resistant metals available. It performs well in both indoor and outdoor environments.
Copper - No
Copper does not rust, however it can react with the moisture and air to form a greenish blue patina (copper carbonate). This is a type of corrosion, but it's protective and often desired in architectural and design applications. This natural ageing process is often welcomed for its antque look.
Brass - No
As an alloy of copper and zinc it does not rust. Like copper, it can tarnish to form a patina over time. The colour shifts from a bright gold to a dull brown. This does not harm the metal and can be polished off to create a clean look if preferred.
What makes a Metal Rust Resistant?
Some metals are naturally resistant to rust and corrosion due to their chemical makeup or protective properties:
- Chromium (present in stainless steel) helps form a oxide barrier that blocks rust.
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Natural Oxide Layers help block further reaction.
- Alloying elements such as nickel or zinc improve further resistance.
- Surface coatings to physically shield the metal
When choosing a metal, consider the environment it will be exposed to. Humidity, saltwater, chemicals and temperature swings can all impact corrosion.
How to Prevent Metal Rust and Corrosion?
If your metal is prone to rust, there are ways to extend their lifespan:
- Protective Coating - Paint, Powder Coating, Galvanisation.
- Keep it Dry - Reduce exposure to moisture.
- Regular Maintenance - Clean and inspect metals regularly.
- Avoid Dissimilar Metals - Mixing metals can cause galvanic corrosion in most environments.
Want help choosing the Right Metal?
We supply a wide range of corrosion resistant metals. Looking for the best sheet metal for sale? UK shoppers can’t do better than London Metal Store. We pride ourselves on offering the highest quality sheet metal for the most competitive price, so you know you’re getting the most out of your budget. Don’t hesitate to contact our team if you have any questions. Call us on 0203 002 63 53 or drop us an email at sales@londonmetalstore.co.uk.
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