Weather-resistant steel – ideal for bridge construction and shipbuilding

Corrosion is the greatest enemy of steel structures. When moisture, oxygen, and pollutants come into contact with conventional structural steel, the unstoppable process of rust formation begins. This is precisely where weather-resistant steel shows its strengths. A material that protects itself through targeted alloying elements and thus replaces conventional structural steel in many areas.

What is weather-resistant steel?

Weather-resistant steel, also known as Corten steel (named after the U.S. trademark COR-TEN®), is an alloyed steel with special corrosion-resistant properties. Through the targeted addition of copper, chromium, nickel, and phosphorus, a dense oxide layer—known as patina—forms on the surface. This layer acts as a barrier and prevents further progression of corrosion.

Weather-resistant steel compared to other types of steel

Weather-resistant steel is distinguished by special properties that set it apart from other types of steel, such as regular structural steel or stainless steel. Compared to conventional structural steel, it offers significantly higher corrosion resistance, making it particularly suitable for use in exposed environments.

In contrast, regular steel requires regular treatment or coating to prevent corrosion. This leads to additional maintenance and upkeep costs. Stainless steel also has high resistance to rust, but it is more expensive and may not always be suitable for the same applications as weather-resistant steel.

The choice of the right material therefore depends largely on the environmental conditions and the requirements of the construction project. In many cases, however, weather-resistant steel offers the most cost-effective and durable solution.

Cost-benefit analysis: Weather-resistant steel in steel construction

A detailed cost-benefit analysis shows that, despite the initially higher material costs, weather-resistant steel can be the more cost-effective choice in the long run. In particular, the lower maintenance and upkeep costs offset the higher initial investments over a longer service life.

Weather-resistant steel grades from UnionStahl Nord

Steel grade	Main quality	Properties
S355J2W	1	Weather-resistant steel with good weldability, high yield strength (≥ 355 MPa), and impact toughness at -20°C.
S355J2WP	2	Similar to S355J2W, but with an improved phosphorus alloy for enhanced weather resistance.
S355J0W	-	Weather-resistant structural steel with impact toughness at 0°C.
S355J0WP	-	Similar to S355J0W, but with a phosphorus addition for better patina formation.
S235J0W	-	Weather-resistant steel with a lower yield strength (≥ 235 MPa) and impact toughness at 0°C.
S235J2W	-	Similar to S235J0W, but with better toughness at -20°C.
S355K2W	-	Weather-resistant steel with high strength and improved impact toughness at -40°C.

Properties and Advantages at a Glance

Weather-resistant steel combines high weather resistance with a distinctive appearance. Its key features:

High weather resistance: Self-protecting patina prevents further corrosion.
Long lifespan: Significantly longer durability compared to untreated structural steel.
Low maintenance costs: No need for re-coating or extensive maintenance.
High mechanical strength: Comparable load-bearing capacity to conventional structural steel.
Environmentally friendly: Fewer coatings mean less material and energy usage.

The lifespan of weather-resistant steel can be 50 years or more, depending on the environment.

How does corrosion protection work?

The secret of weather-resistant steel lies in its chemical composition. Through the targeted alloying elements, the type of rust formation changes.

Initial rust formation: Like normal steel, the surface begins to oxidize when exposed to the weather.
Patina development: Instead of porous rust, a dense, firmly adhering protective layer forms.
Long-term stabilization: The patina continuously renews itself, protecting the underlying steel.

Applications of weather-resistant steel

Thanks to its excellent properties, weather-resistant steel is used in many areas.

Bridge construction and civil engineering.

Bridges must withstand extreme weather conditions. Weather-resistant steel reduces maintenance costs and significantly extends the lifespan. Especially in hard-to-reach areas where regular painting would be costly, this steel is an economically sensible solution.

Examples:

Bicycle bridges and canal bridges.
The High Line in New York uses Corten steel for railings and support structures.

Architecture and facade construction.

Modern buildings often use Corten steel not only for its durability but also for its unique appearance. The warm rust-red hue develops individually and gives structures a distinctive touch.

Examples:

The Allianz Arena in Munich is partly made of weather-resistant steel.
The sculpture “Angel of the North” in England is made of Corten steel.

Railway facilities and transportation infrastructure.

Rail companies are increasingly relying on weather-resistant steel for overhead line masts, noise barriers, and infrastructure. The reason for this is the lower maintenance costs and the high resilience to environmental stresses.

Processing of weather-resistant steel.

Due to its special properties, there are some considerations to keep in mind when processing weather-resistant steel.

Welding: Special welding material must be used to avoid affecting the corrosion properties.
Bending and forming behavior: Similar to conventional steel, but with slightly higher strength.
Pre-treatment: For an even patina, the surface should be degreased and cleaned after processing.
Contact corrosion: Direct contact with regular steel can lead to accelerated corrosion at the contact points.

Weather-resistant steel is an economical solution for durable steel structures.

Weather-resistant steel impresses with its high resilience, long lifespan, and low maintenance requirements. In bridge construction, transportation infrastructure, and buildings, it replaces conventional structural steel and reduces long-term maintenance costs.

When processing and planning, the environmental conditions as well as specific requirements for welding and forming should be considered. When used correctly, weather-resistant steel is a reliable and economical choice for demanding steel structures.

Calculate the price for weather-resistant steel.

Now calculate the price for an S355J2C+N product online.

Your contact person

If you have any questions about our range of products or services, please feel free to contact our representative. We are happy to assist you.

Heiner Büsselmann

Tel.: +49 (0)421 / 48 40 1922 – 21
E-mail: hbuesselmann@unionstahl.com

FAQ – Frequently asked questions about weather-resistant steel

How long does it take for the patina on weather-resistant steel to fully form?

The formation of the patina on weather-resistant steel is a continuous process that can take anywhere from a few months to several years, depending on environmental factors and moisture conditions. In regions with variable weather and frequent moisture fluctuations, the patina forms more quickly. However, the protective effect is already noticeable after a short time, even if the patina has not yet fully developed.

Can weather-resistant steel be used in all climate zones?

Weather-resistant steel is especially well-suited for temperate to moderately humid climates. In extremely humid or saline environments (such as coastal areas), the protective layer may be less effective, which can impair corrosion resistance. In such cases, additional protective measures should be considered.

Does weather-resistant steel always need to be specially treated or pretreated?

In most cases, no special treatment is required to ensure weather resistance. However, when processing weather-resistant steel, such as welding or bending, specific requirements must be considered. For example, suitable welding fillers should be used to avoid impairing the corrosion resistance.

Is weather-resistant steel more expensive than conventional structural steel?

Yes, weather-resistant steel generally has higher material costs than conventional structural steel. However, these additional costs are often more than offset by the savings in maintenance and the extended lifespan of the material. Especially in large and long-term projects, the higher initial costs are quickly amortized.

How environmentally friendly is the production of weather-resistant steel?

Weather-resistant steel is more environmentally friendly than many other steel-based materials because it does not require additional coatings, thus needing fewer energy-intensive processes for corrosion protection treatments. Additionally, the long lifespan of weather-resistant steel helps minimize resource consumption.

How to deal with existing rust on weather-resistant steel?

If rust spots already appear on weather-resistant steel, they should be carefully removed to avoid affecting the formation of the patina. Mechanical cleaning, such as sandblasting or brushing, can help. In many cases, the patina forms again quickly after cleaning, protecting the steel from further corrosion.