Rusting away is exactly what isn’t happening with Weathering Steel. Because of its chemical composition it exhibits increased resistance to atmospheric corrosion compared to mild steel.
Corten steel sometimes referred to as high-strength low-alloy steel, is also a type of mild steel that is formulated to produce a dense, stable oxide layer that provides adequate protection. It itself forms a thin film of iron oxide on the surface, which acts as a coating against further rusting.
This oxide is produced by adding alloying elements such as copper, chromium, nickel and phosphorus, and is comparable to the patina found on uncoated cast iron exposed to the atmosphere.
◉Corten steel needs to undergo cycles of wetting and drying.
◉Exposure to chloride ions should be avoided, as chloride ions prevent steel from being adequately protected and lead to unacceptable corrosion rates.
◉If the surface is continuously wet, no protective layer will form.
◉Depending on conditions, it may take several years to develop a dense and stable patina before further corrosion can be reduced to a lower rate.
Due to the superior corrosion resistance of corten steel itself, under ideal conditions, the service life of items made of corten steel can reach decades or even a hundred years.