What is Corten Steel?

Corten steel, which is also known as ‘weathering steel’, is a group of steel alloys that were originally developed to eliminate the need for painting or applying protective coatings to steel surfaces. So, what truly sets Corten Steel apart from its peers? When subjected to atmospheric elements, this remarkable material develops a protective layer resembling rust on its surface. This unique characteristic makes it highly resistant to corrosion.

This innovative material was first brought to life back in the 1930s. Its primary application was within the railroad industry, and it was subsequently patented by the well-known U.S. Steel (USS). Interestingly, the name “COR-TEN” stands for the material’s two primary properties. ‘Cor’ signifies Corrosion Resistance, while ‘Ten’ indicates Tensile Strength.

What is Corten Steel Made of?

Primarily composed of iron and a small amount of carbon, Corten steel sets itself apart due to the inclusion of unique alloying elements: chromium, nickel, copper and added phosphorous which gives the steel its self-protecting properties. A particularly noteworthy feature of this composition is the ability of the materials outer layer to naturally repair itself when subjected to scratches or damage, demonstrating its resilience and longevity.

Is Corten Steel Weldable?

If you’re wondering about the welding prospects of Corten steel, it is relatively similar to other low-carbon steels, such as mild steel. However, a special filler material may be required depending on the particular application. This means that, provided with the right machinery and tools, Corten steel can easily be welded and shaped to cater to your unique requirements.

Is Corten Steel Expensive?

Although corten might come with a higher upfront cost when you compare corten steel vs mild steel, it turns out to be an economical choice in the long run. Given its resilience and low maintenance requirements, your investment in Corten steel recoups itself as time goes by.

Furthermore, when you consider the expenses associated with protecting other sheet metals via processes like painting or galvanizing, the price difference starts to level out, reaffirming the cost-effectiveness of Corten steel.

How does Corten Steel Weather?

One of the fascinating aspects of Corten steel is its weathering process, which typically takes around 6-9 months, depending on the prevailing weather conditions. At the start of the process, the steel develops an orange patina. As time goes on, this turns into a darker brown hue, providing Corten steel its iconic look. It’s important to note that Corten steel requires a cycle of alternating wet and dry conditions to form this protective layer effectively.

Step 1 – Newly created Corten Steel. At this point, a dark, oily coating is visible on the Corten Steel.

Step 2 – The dark coating starts to degrade, marking the start of Corten Steel’s weathering process.

Steps 3 & 4 – The “Run-Off” phase. This stage can take between 3 to 9 months, depending on weather conditions and location.

Steps 5 & 6 – During these final phases of weathering, occasional ‘run-off’ may still occur. Meanwhile, Corten Steel’s patina evolves towards a more uniform and striking appearance.

How is Corten Steel made?

A significant point to bear in mind is that Corten steel is only produced in sheet form. This differs from other types of steel, such as mild steel, which are readily available in different section forms. The specific production process lends Corten steel its unique position in the market, albeit making it somewhat less accessible compared to other materials.

Where is Corten Steel used?

Corten steel’s unique properties have led to its use across a range of industries, including architecture, construction, and landscape. You’ve probably seen it in the form of large structures like bridges, or even the Angel of the North, a renowned sculpture. But Corten steel isn’t limited to grand structures alone. It’s also become very popular in recent years for creating outdoor garden products such as steel planters, artwork, edging, water features, and street furniture, adding a natural and rustic aesthetic to any outdoor space.

Run-Off

Another significant aspect to understand about Corten steel is the occurrence of ‘run-off’ during the initial stages of its weathering process. ‘Run off’ refers to the rusty water that can drain off from Corten steel, potentially causing staining on the surfaces upon which it is placed.

To ensure that run-off doesn’t become a concern, there are several steps you can take:

1. Complete Weathering Before Placement: You could allow the Corten steel product to undergo the complete weathering process and let any run-off occur before positioning it in its final location. If you’re aiming for a more rapid transition, you could apply a weathering treatment to speed up this process.
2. Use Protective Layer: Alternatively, you might consider placing the Corten steel product on a slab or other protective material that can be moved or replaced once the product has fully weathered. This acts as a barrier, protecting your surfaces from potential staining.
3. Opt for Easily Replaceable Materials: Lastly, you could choose to position the Corten steel product on grass or soil which won’t cause any issues or loose materials such as stone, slate, or wood chippings. These materials can easily be turned over or replaced to eliminate any run-off stains.

To learn more about run-off, check out our blog post how do i prevent corten steel from staining?

Looking to add Corten Steel to your outdoor area?

In summary, Corten stands out from the crowd thanks to its unique characteristics and a huge array of benefits. Its superior corrosion resistance, robust tensile strength, and cost-effectiveness over the long haul make it a highly desirable material for a wide range of projects. Whether you’re contemplating a landscape feature, a statement artwork piece, or a practical piece of street furniture, Corten Steel brings an unbeatable blend of durability, aesthetic appeal, and practicality to the table.

We invite you to browse our extensive range of corten steel products and imagine how this unique material can lend a distinctive edge to your next project. If you have any questions or require further information please don’t hesitate to contact our friendly team today at hello@luxunique.co.uk who will be happy to help.