FAQ: Is Corten Steel Rust Proof?

Is corten steel rust proof?

FAQ: Is Corten Steel Rust Proof?

Most low alloy steels have the tendency to rust, or corrode, over time as they are exposed to water and/or moisture in the air. Overtime, this rust layer becomes porous and detaches from the metal surface. One of the benefits of using corten steel, also referred to as weathering steel, is its ability to resist the corrosion that other low alloy steels experience. 

Is corten steel rust proof?  

With corten steels, the rusting process occurs in a similar fashion, but instead produces a stable rust layer known as the patina, which adheres to the base metal and is much less porous. This naturally-developed patina regenerates continuously when exposed to weather and produces a protective barrier that impedes further access of oxygen, moisture and pollutants. 

So, does this make corten steel rust proof? No, it does not. Corten steel is allowed to rust in order to form the protective patina coating. While this results in a much lower corrosion rate compared to other steels, it does NOT mean corten steel is rust proof. 

Patina vs. rust

Patina and rust both are forms of surface corrosion.The patina forms through oxidation and protects corten steel from the deeper and more destructive rust. Rust, on the other hand, is caused by deterioration, and will begin to chip away the metal surface creating porous cracks and hazardous edges. 

In its original state, corten steel is silver in color like standard steel and develops the orange-brown color overtime as the patina develops. The rate at which the patina forms depends on the environment the steel is in as well as various factors, such as humidity and proximity to bodies of water. In our experience, the patina forms quicker when the steel is exposed to more environmental cycles. Likewise, cold-rolled materials (18 GA sheets or thinner) form the patina quicker than hot-rolled materials (16 GA sheets or thicker). 

Many will mistake the orange-brown patina that corten steel produces as rust, but in reality, the patina of corten steel is doing its job to guard against further corrosion. That’s the beauty and benefit of using corten steel

Patina appreciation

Many builders, designers and architects have fallen in love with not only the practical benefits that weathering steel offers, but also the rustic orange-brown color and texture weathering steel brings to a project. Since Central Steel Service was founded more than 40 years ago, weathering steels have only increased in popularity. Once used for mostly industrial applications, weathering steels are now used for a variety of applications, including bridges, roofing, siding, landscape elements, sculpture and more. 

Contact Central Steel Service for Corten Steel

Central Steel Service stocks high strength weathering steel across all product categories to meet the needs of our customers. We understand that the unique applications requiring these specialty products require the utmost attention to quality and material traceability. By focusing our entire resources on supplying only these specialty products, we can give you complete confidence in your decision to allow us to service your steel requirements. Contact us today!