Weathering steel is a family of low carbon steels that have additional alloying elements mixed in with the carbon and iron atoms. These alloying elements give weathering steel better strength and more corrosion resistance than typical low carbon steel grades. As a result, weathering steel is commonly used in outdoor applications or environments where normal steel would be inclined to rust. As a low carbon steel, weathering steel typically has less than 0.3% carbon by weight. This low amount of carbon allows it to remain ductile and tough. Weathering steel also includes other alloying elements that help to increase the strength, but more importantly, the corrosion resistance. There are many different alloying elements used, but the key three elements in weathering steel are nickel, copper, and chromium.