Weathering steels, such as ASTM A588, A242, A606-4 and Cor-Ten exhibit superior corrosion resistance over regular carbon steel as a result of the development of a protective oxide film on the metals surface which slows down further corrosion. Their 50,000 minimum yield strength characteristic allows cost reduction through the ability to design lighter sections into structures. These steels were designed primarily to be used in unpainted applications where a reduction in maintenance costs, such as painting, were desired. Since their development, weathering steels are now being used in a variety of applications, including bridges, rail cars, transmission towers, highway poles and shipbuilding.