Definition - What does Weathering Steel mean?
Weathering steel refers to a type of high strength steel alloy that develops a protective oxide film on its surface. Weathering steel exhibits superior corrosion resistance traits compared to regular carbon steel due to this unique property and its superior yield strength capability.
Corrosionpedia explains Weathering Steel
Weathering steel was first developed in the 1930s by the United States Steel company to resist corrosion of ore wagons in use at the time. In 1964 it was used to construct the John Deere World Headquarters building in Moline, Illinois.
Weathering steel is able to resist significantly higher rates of corrosion. All low alloy steels rust in the presence of air, moisture, atmospheric contaminants and other impurities on the metal's surface. The initiation and propagation of rust is the same for weathering steel as with other steels. However, the rust produced is significantly less porous and adheres to the base metal. Rust formation on weathering steel typically occurs in environments with alternating wetness and dryness. Therefore, it is not advisable to use weathering steel in environments with significant moisture levels.
There are four main types of weathering steels used in industrial applications: ASTM A588, A242, A606-4 and Cor-Ten®.