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What is weathering steel?

Guide to weathering steel High strength, low alloy weldable structural steel with exceptional corrosion resistance.
Nov 17th,2025 371 Views

Guide to weathering steel
    High strength, low alloy weldable structural steel with exceptional corrosion resistance.

What is weathering steel?

    Weathering steel definition: steels that are chemically formulated to develop a protective patina layer - rust-like in appearance - that eliminates the need for paint. Thedense oxide patina layer of weathered steel seals it off from the atmosphere. If a weathered steel panel is scratched, its patina will self-heal. The weathered steel is onlynot protected against further corrosion: it also delivers a unique finish that is an aesthetically pleasing - a warm, dark-brown, textured appearance that needs low or nomaintenance.

The patina formation process of weathering steel

       Once it's exposed to alternating wet and dry conditions, weathering steel begins to rust in the same fashion as non-weathering steel. However, as time passes, the rustlayer transforms into a patina layer, and its color changes from a fresh, newly developed orange-brown to a light or dark brown.

    The speed of change and the final color of a weather-resistant steel sheet are dependent on the atmospheric conditions of a site and the level of pollution.Sulfur-denseatmospheres will speed up the oxidation process and result in a darker patina. Frequent cycles of wet and dry conditions will also speed up oxidation. The entire oxidationprocess for this corrosion-resistant steel usually takes between 2-6 years.

Rust - the perfect protection

    Weathering steel's patina process has no effect on the steel's mechanical properties, including its strength.As a result,structures made from SSAB Weathering steel require low- to no-maintenance for as long as the structure stands.Weatheringsteel from SSAB is strong, reliable, and guaranteed to last, as will its vivid natural appearance.

Weathering steel sheets, heavy plates, strips, tubes and sections

    SSAB offers weathering steel in a large selection of strengths - from 345 to 960MPaYS- and configurations, includingweathering sheets, hot- and cold-rolled strips, tubes, and sections. To save time when selecting grades, contact us so we canmutually determine the most appropriate configurations, grades, and thicknesses.

Choose the right type of weathering steel for your industry

Structure and bridges Heavy transport Process industry Buildings Arts and parks









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