Can weathering steel be welded?

Choosing the right material is an important starting point for designing a steel structure. Choosing the right material can bring significant advantages. There is a wide range of weathering steels available in different strengths for many applications. Weathering steels combine the advantages of higher strength with better corrosion resistance. Since in most applications weathering steel does not have an anti-corrosion coating, the carbon footprint of the entire structure is smaller than coated steel solutions. For applications with painted surfaces, maintenance painting is less frequent, which saves money and protects the environment.

Weathering steel
Weathering steel is a low alloy steel with excellent atmospheric corrosion resistance. Atmospheric corrosion resistance is based on the formation of an oxide layer on the surface, which forms a sealed, uninterrupted protective layer on the steel surface. This oxide layer is called patina. The term weathering steel is commonly used, sometimes weathering steel and weathering steel are also used.
The patina layer of weathering steel is different in structure and composition from the patina layer of ordinary steel. Ordinary patina layers are weak and cracked, and the material peels off easily. The patina layer contains elements that adhere well to each other and to the steel surface. This results in a protective layer that hardly sheds any material and effectively prevents water and oxygen from entering the steel surface. Under a protective patina layer, corrosion does not stop completely, but the rate of corrosion is much slower, so the steel can be used in outdoor conditions without a protective coating.

Phosphorus-free weathering steels have excellent impact toughness and welding properties, which is why they can be used as structural steels in load-bearing structures. These steels are available in different strengths for different applications, with yield strength ratings from 345 MPa to 960 MPa.