Corten steel is a class of alloy steel, after several years of outdoor exposure can form a relatively dense rust layer on the surface, so it does not need to be painted protection. Most low-alloy steels tend to rust or corrode over time when exposed to moisture in water or air. This rust layer becomes porous and falls off the metal surface. It is resistant to the corrosion experienced by other low alloy steels.
Corten steel resists the corrosive effects of rain, snow, ice, fog, and other weather conditions by forming a dark brown oxidizing coating on the metal surface. Corten steel is a type of steel with added phosphorus, copper, chromium, nickel and molybdenum. These alloys improve the atmospheric corrosion resistance of weathering steel by forming a protective layer on its surface.
Corten steel is not completely rust-resistant, but once aged, it has high corrosion resistance (about twice that of carbon steel). In many applications of weathering steel, the protective rust layer usually develops naturally after 6-10 years of natural exposure to the element (depending on the degree of exposure). The corrosion rate is not low until the protective ability of the rust layer is shown, and the initial flash rust will contaminate its own surface and other nearby surfaces.
