Corten steel is a material like no other – strong, stylish, and built to withstand extreme temperatures, high waves, and journeys around the world. Where other metals would rust or fail, this steel thrives in the elements, forming a protective patina that prevents further corrosion and maintains itself.
You'll find corten steel used in everything from bridges to outdoor sculptures and modern architecture. However, one of its most iconic roles is in building shipping containers, where its strength and weather resistance make it perfect for withstanding harsh conditions at sea and on land.
The history of Corten steel
Back in the early 20th century, manufacturers in the United States started experimenting with different types of steel. They tested steels alloyed with other metals and chemicals to see how well they survived wind, rain, and waves. Over time, they made more discoveries, such as how adding phosphorus makes steel more resistant to rust.
In 1933, corten steel was born - also known as weathering steel or by its original trademark, Cor-Ten. It was first used for railroad cars that carried heavy materials such as coal, grain, and minerals.
So, what is Corten steel?
The name "Cor-Ten" describes exactly what it does. It's steel with extra cor-rosion resistance and ten-sile strength, meaning it's less likely to rust and can withstand heavy loads.
When it does corrode, the corten rust forms a protective layer over the steel, so it's ideal for damp conditions such as sea travel. Strangely enough, corten steel rust has even become a popular design aesthetic. If you've ever seen a modern building with red, weathered metal details, that's inspired by the iconic corten steel.
How is Corten steel made?
Corten steel is still under trademark by the United States Steel Corporation. It's made with a blend of elements such as copper and phosphorus. Different amounts of each element create corten steel with different properties.
The alloys are added to the steel during production. Next, the metal is passed between rollers at a very high temperature to remove any impurities. It's formed into sheets which can be cut and shaped to make shipping containers.
What is Corten steel made from?
Steel is mostly made from very pure, low-carbon iron. Corten steel also contains small amounts of copper, chromium, and phosphorus, as well as trace amounts of nickel, silicon, and manganese.
The science behind Corten steel
Every element that's added to corten steel gives it extra properties. For example, chromium, copper, and nickel help protect the steel from corrosion.
The most important thing about weathering steel is the chemical reaction that happens when it rusts. When normal steel corrodes, the rust flakes away, leaving the metal underneath vulnerable. Eventually, the rust eats all the way through the steel.
But corten steel reacts differently. Instead of flaking off, it creates a tough rusty layer that sticks on top of the steel. That layer continues to develop and reinforce itself over time, so it's perfect for wet and windy weather - whether at sea or on land in the UK!
Corten steel patina formation
The weathering process - or rust formation - takes around 6-9 months. Corrosion happens when the metal is exposed to water and air, so the speed can vary depending on how damp the weather is.
How does Corten steel weather?
The patina of rust on corten steel takes a while to form. It slowly develops into a blend of warm brown and orange tints which many people like. Over time, it also gets tougher and protects the metal underneath.
How to protect Corten steel
Corten steel mostly protects itself. However, it might need extra protection in some environments. Damp weather, regular contact with waves, and high levels of air pollution can all make the metal more vulnerable.
Many shipping containers are painted to give them extra protection. If you want to keep the natural patina of the corten steel, you can coat it with oil instead, although this will make the surface slightly shiny rather than matte. The look is often described as similar to smooth antique leather.
Types of Corten steel
Corten steel comes in two main types: Cor-ten A and Cor-ten B. The key difference between them is the amount of phosphorus they contain.
Most shipping containers are made of Cor-ten B, which is produced in tubes or sheets. Cor-ten A is produced in coils and it's mainly used for finer items, such as ductwork.
Common uses of Corten steel
Shipping containers use corten steel because it's strong, weather-resistant, and lasts for a long time. But there are other uses for this super-steel, too.
You can also see corten steel used on building facades, roofs, landscape design, and even major engineering projects. Because of its attractive weathered appearance, it's also popular in garden ornaments and sculpture.
Advantages of Corten steel
There are several reasons why shipping companies, engineers, and builders choose corten steel. As well as rust resistance, corten steel is also known for its durability, versatility, and low lifetime costs.
Corrosion resistance
Unlike some other types of steels, corten steel gets stronger when it rusts. The top layer of metal forms a protective patina that can last for years. Even better, the patina can repair itself if it's scratched or damaged.
Durability
Because of their tensile strength and corrosion resistance, shipping containers can put up with a lot. They hold heavy loads, get transported all over the world, and resist extreme weather. With the right maintenance, corten steel can last for decades.
Low maintenance
Corten steel's natural patina means that it doesn't even need to be painted. It requires minimal maintenance, at minimal cost. Although shipping containers should be checked regularly for rust or dents, corten steel can protect itself for a very long time.
Company profile
Founded in 2008, Gnee (Tianjin) Supply Chain Group Co., Ltd. specializes in the global trade and processing of Corten steel products.
• We handle all kinds of Corten engineering projects, such as bridges, gardens, hotels, and facade systems.
• Compliant with ASTM, EN, and other international standards; third-party inspection supported.
• Exported to over 200 countries and regions worldwide.
• 8 subsidiaries across China and overseas, ensuring global service coverage.
Application Fields: Architecture, landscaping, gardening, cladding, and urban infrastructure.
